rexroth psx 6xxx edition 02 technology and timer functions
TRANSCRIPT
Description of application
Electric Drivesand Controls Pneumatics Service
Linear Motion and Assembly TechnologiesHydraulics
Rexroth PSx 6xxxTechnology and timer functions
R911172825Edition 02
R911172825 / 02Bosch Rexroth AG Electric Drivesand Controls
PSx 6xxx| |2�/�78
The data indicated below is intended to describe theproduct. Should information on its use be provided,such information represents application examplesand suggestions only. Catalog specifications shallnot be deemed as warranted quality. This information does not release the user from performing his own assessments and verifications. Our products are subject to natural wear and aging.
� All rights reserved, including applications forprotective rights by Bosch Rexroth AG.Reproduction or distribution by any means subject toour prior written permission.
An example configuration is shown on the coverpage. The delivered product may therefore deviatefrom the picture.
Language version of the document: ENOriginal language of the document: DE
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Contents
Contents
1 Regarding this documentation 5. . . . . . . . . . . . . . . . 1.1 Validity of this documentation 5. . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Additional documentation 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Presentation of information 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.1 Safety instructions 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.2 Icons 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.3 Designations 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.4 Abbreviations 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Safety instructions 9. . . . . . . . . . . . . . . . . . . . . . . . . .
3 General information on damage to property andproducts 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Scope of delivery 13. . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Information on this product 15. . . . . . . . . . . . . . . . . . . 5.1 General information 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 Program execution 17. . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Programmable times 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Current blocks 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Electrode force 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7 Functions 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Schedule modes 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Single spot 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.2 Repeat 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3 Seam 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Impulse mode 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Slope (current increase) 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 Welding modes: 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1 Phase angle (PHA) 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2 Constant-current regulation (KSR) 30. . . . . . . . . . . . . . . . . . . . . 7.4.3 UI regulation (UIR) 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 %I prewarning and limitation 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.1 %I limitation 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.2 %I warning 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.3 Lower %I warning 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 Monitoring 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.1 Current monitoring 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.2 Time monitoring 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.3 Monitor stepper 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.4 Measuring loop test 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6.5 Minimum current verification 40. . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7 Latching 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8 Automatic reweld by timer active 40. . . . . . . . . . . . . . . . . . . . . . . . 7.9 1. Halfcycle limit 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Contents
7.10 Post-warming pulse (NWI) 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11 Electrode management 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11.1 %I stepping (Stepper) 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11.2 Tip dressing 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11.3 Warning and end of Stepper 50. . . . . . . . . . . . . . . . . . . . . . . . . . 7.11.4 Warning table 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.12 Tip dresser result monitoring 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.13 Monitoring dresser change 54. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.14 Gun life monitoring 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.15 Outputting the electrode force 56. . . . . . . . . . . . . . . . . . . . . . . . . . . 7.16 Calibration 57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.16.1 Force calibration 57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.16.2 Current calibration 59. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.17 Corrections 60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.18 KSR changeover 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.19 Close weld contactor 62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.20 Weld Circuit Degradation (WCD) 62. . . . . . . . . . . . . . . . . . . . . . . . 7.21 Reference to additional important functions 63. . . . . . . . . . . . . . . 7.21.1 UI regulation 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.21.2 Thin-sheet function 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.21.3 Q Stop (Quality Stop) 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.21.4 Glue function 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.21.5 Static gun resistance compensation 63. . . . . . . . . . . . . . . . . . . . 7.21.6 Force monitoring 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8 List of tables 65. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9 List of figures 67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10 Abbreviations 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11 Index 73. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Regarding this documentation
1 Regarding this documentation
This chapter includes important information on the use of the documentation.
� Inform yourself about the product before you work with it!
1.1 Validity of this documentation
The present documentation• applies to
our weld timers PSx 6xxx.Except for: PSI 6xxx.000 (master−slave) and PSI 6xxx.190 (roll seam types)
• is designed for planning, programming, start-up personnel, operators, service technicians, plant operators.
• provides information about• programming principle,• basics on the definition of a welding schedule and• important timer functions.
1.2 Additional documentation
Several documents are available for the product which are needed together for comprehensive information.
� Only start the product when you are familiar with and understand thedocuments marked with �.
Table 1: Necessary and supplementary documents
Title Doc. no. Document type
� PST 6xxx: Weld timer with thyristorpower unit
1070080029 Operating instructions
� PST 6xxx.xxx: Weld timer withthyristor power unit, type-specificsupplement
dependingon type
Operating instructions (type-specific supplement)
� PSI 6xxx: Weld timer with medium-frequency inverter
1070080028 Operating instructions
� PSI 6xxx.xxx xx: Weld timer withmedium-frequency inverter, type-specific supplement
dependingon type
Operating instructions (type-specific supplement)
� PSG 3xxx/6xxx: MF welding transformers
1070087062 Operating instructions
� PSG 3xxx/6xxx: MF-welding transformers, type-specific supplement
dependingon type
Operating instructions (type-specific supplement)
� PSx 6xxx: Technology and timerfunctions
R911172825 Description of application
� BOS 6000 online help 1070086446 Reference
PSI 6xxx: UI regulation and monitoring
1070087072 Description of application
�: necessary document
For which product?
Target group?
Topics dealt with?
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Regarding this documentation
1.3 Presentation of information
We use uniform icons, terms and abbreviations in this documentation.They will be explained in the following paragraphs.
1.3.1 Safety instructions
Safety instructions call your attention specifically to danger potentials orrisks.
We distinguish among the following places where safety instructionsmay be required:
• Basic safety instructions:
They are related to general important matters and apply to the complete documentation.These safety instructions are provided in Sections 2 and 3 of operating instructions „PSI 6xxx: Weld timer with medium-frequency inverter“ (doc. no. 1070080028; also refer to page 5).
• Preceding safety instructions:
They refer to topic-related matters and are provided at the beginningof a chapter or at the beginning of a whole procedure.
• Integrated safety instructions:
They are related exactly to a separate procedure step and areprovided right before the relevant step within the procedure.
A safety instruction is always structured as follows:
• Warning sign (only in case of personal injury)
• Signal word to indicate the danger level
• Type and source of danger
• Consequences of failure to observe
• Action for averting danger.
Table 2: Example for the structure of a safety instruction
Warning sign + SIGNAL WORD
Type and source of danger!
Consequences of failure to observe!
� Action for averting danger.
� Further action(s) for averting danger.
Integrated safety instructions may be embedded in the format of theenvironment so that no ”visual” break in the action sequence is provoked. Therefore they do not necessarily use the layout shown in theexample but they do use the indicated structure.
Where?
Structure?
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Regarding this documentation
The safety instructions are classified into danger levels (dangerclasses). The signal word represents the danger level.
Table 3: Danger classes according to ANSI Z535.6-2006
Signal word Meaning
DANGER Dangerous situation where death or serious physical injurieswill occur if it is not avoided.
WARNING Dangerous situation where death or serious physical injuriesmay occur if it is not avoided.
CAUTION Dangerous situation where light to moderate physical injuries may occur if it is not avoided.
NOTICE Situation where damage to property or the environment mayoccur if it is not avoided.
Table 4: Examples for classification of safety instructions
DANGER
Type and source of danger!
Consequences of failure to observe!
� Action for averting danger.
WARNING
Type and source of danger!
Consequences of failure to observe!
� Action for averting danger.
CAUTION
Type and source of danger!
Consequences of failure to observe!
� Action for averting danger.
NOTICE
Type and source of danger!
Consequences of failure to observe!
� Action for averting danger.
Danger levels?
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Regarding this documentation
1.3.2 Icons
The following icons are used to mark text passages specifically.
Table 5: Icons used
Symbol Meaning
This icon indicates a tip or an information. It helps useand operate the product optimally or understand thecontext better.
� This icon indicates the need to observe/perform certainthings.
• This icon indicates an (unsorted) list.
1.2.3.
This icon indicates a (sorted) list or specific proceduresteps where a certain sequence has to be observed.
1.3.3 Designations
The following designations may appear in our documentation:
Table 6: Designations
Name Meaning
BOS Welding user interface
PE Protective Earth. PE conductor.
PG Programming terminal/welding computer
PSG Transformer-rectifier unit for PSI types.Medium-frequency welding transformer 1000 Hz
PSI Programmable weld timer with inverter.
PSQ 6000XQR
Plug-in module for PSI with UI controller functionality.Is not needed for PSI 6xCx types.
PST Programmable weld timer with thyristor power unit.
PLC Programmable Logic Controller.
WT Weld timer. Also referred to as timer or resistance weld timer.
1.3.4 Abbreviations
Refer to Section 10 on page 71 et seq.
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Safety instructions
2 Safety instructions
� Please note the section with the identical name in the operating instructions for the PSI 6xxx and PST 6xx0 product families (for information on document numbers, refer to table 1: page 5).
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Safety instructions
Notes:
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General information on damage to property and products
3 General information on damage to property andproducts
� Please note the section with the identical name in the operating instructions for the PSI 6xxx and PST 6xx0 product families (for information on document numbers, refer to table 1: page 5).
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General information on damage to property and products
Notes:
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Scope of delivery
4 Scope of delivery
� Please note the section with the identical name in the operating instructions for the PSI 6xxx and PST 6xx0 product families (for information on document numbers, refer to table 1: page 5).
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Scope of delivery
Notes:
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Information on this product
5 Information on this product
5.1 General information
Welding systems equipped with our PSx 6xxx timer types normally consist of the following main components:
• weld timer (with integrated MF inverter or with integrated thyristorpower unit)
• suitable welding transformer (including current sensor for secondarymeasurement)
• pneumatically or electrically operated electrode gun.
Furthermore, a higher-level controller is required that controls the entiremanufacturing process of the part and also monitors its safety aspects.Suitable controllers include
• a programmable logic controller (PLC)
• a robot controller
• manual control (e.g. of manual guns), or even
• a combination of these possibilities.
PLC or robot
I
O
OStart
WC
(WLD)
Gun
PSx 6xxx
Prog. No./spot No.
Electrodes
optional external current sensorI: inputO: OutputWC: Weld completeWLD: Weld time
Transformer
Internalcurrentsensor
Force control variable
II
Force feedback
Fig.�1: Main components of a welding plant
The weld timer ensures the controlled performance of the actual welding process. For this purpose, it must provide open- and closed-loopcontrol of many functions and physical quantities. Its main tasks include, e.g.
• Communication with a higher-level PLC or robot controller via I/Osignals.
• Control of a welding gun for influencing the electrode force.
• Ensuring the proper welding schedule by different, technologicallyrequired time intervals (e.g. pre-weld, main weld, post-weld timeetc.) or regulation methods.
• Driving the power unit to generate the proper welding heat.
• Signalling a correct or incorrect weld at the end of the welding program schedule.
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Information on this product
Primarycircuit
Transformer
Secondary circuit
Current I
Power (heat, %I)
PreSQZ+
SQZWLD HLD
Start
Force F
SQZ: Squeeze time (for explanations, refer to Sect. 6.1 starting on page 17)WLD: Weld timeHLD: Hold time (for explanations, refer to section 6.1)
Time
Fig.�2: Physical basic parameters for influencing the weld
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Program execution
6 Program execution
A total of 256 separate welding programs (prog.no. 0 to 255) are available.
Each welding program contains all of the parameters that are requiredfor the precise definition of a weld. Basic parameters include, e.g.
• times that are to be subsequently processed (refer to Section 6.1)
• %I values that are to be effective in different current blocks(refer to Sect. 6.2 starting on page 20)
• electrode force (for a description, refer to page 21 et seq.).
6.1 Programmable times
The way in which a welding program is executed depends on the use ofvarious programmable periods of time. Within the program execution,each period of time serves a specific purpose.
In timers with MF inverters, the times are programmed in milliseconds (in 1 ms grid) and in timers with thyristor power unit in mainscycles (at 50 Hz system frequency: in 20 ms grid).
PreSQZ SQZ PreWLDMainWLD
PstWLD HLD
Start
2. Current block 3. Current block1. Current block
UST DST
Time
Current
1.C
T
3.C
T
Time
Fig.�3: Example: Time diagram of a welding program execution without impulse operation in 2nd current block
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Program execution
PreSQZ SQZ PreWLDMainWLD
PstWLD HLD
Start
2. Current block 3. Current block1. Current block
UST DST
MainWLD
Time
Current
MainWLD
2.CT
Time1.C
T
3.C
T
2.CT
Fig.�4: Example: Time diagram with all programmable periods of time (incl. impulse mode with 3 impulses)
PreSQZ, 1. SQZ (pre-squeeze time):
The electrode gun should entirely close during the PreSQZ. No currentflows during this period of time.
The PreSQZ is processed immediately following the Start signal in allwelding modes (single spot, repeat, and seam).
In the "Repeat" welding mode, the PreSQZ is only executed for the1st spot weld of a series because the gun does not open as widely forthe subsequent spot welds of the series due to the mostly relativelyshort Off time (OFF).
SQZ (squeeze time):
During this time, the working pressure of the electrodes is built up.
No current flows during this period of time.The electrode gun must be entirely closed at the beginning of SQZ(refer to PreSQZ).
Shortest possible SQZ: 16 ms.
During the SQZ - if parametrized - the timer checks whether or notthe connected measuring loop is faultless by performing an ohmicresistance measurement for secondary current measurement. In the event of a fault, the timer aborts the welding program.
At the end of SQZ, some timer types check the signaled force / pressure for tolerance (”Tolerance force monitoring”) if the corresponding function has been selected via BOS within the electrodeparametrization under ”Pressure/force monitoring”. In case of afault, the message ”Welding fault force monitoring: Force too low/toohigh” will be generated at the end of SQZ.
At the end of the SQZ, some timer types check whether a high level ispresent at the digital input X2/4. Otherwise, the timer extends theSQZ by max. 5 seconds before the schedule is aborted and a faultmessage is output.
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Program execution
PreWLD (pre-weld time, pre-heating time)
Refer to page 20.
1.CT (1.Cool time)
If a value greater than 0 has been programmed, it separates the firstand the second current block. Serves to reduce stress in the parts to bewelded.Refer to page 20.
The 1. CT can only be programmed if PreWLD is greater than 0.
MainWLD (main weld time)
Refer to page 20.
2.CT (2nd cool time)
If a value greater than 0 has been programmed, it separates the individual impulses in impulse mode. Serves to reduce stress in the parts tobe welded.Refer to page 26.
The 2.CT can only be programmed if impulse mode has been activated ("Impulse" parameter > 1). Exception: Seam operation.
UST (upslope time / time of current rise)
Refer to page 27.
DST (downslope time / current decrease time)
Refer to page 27.
PstWLD (post-weld time / post-heating time)
Refer to page 20.
3.CT (3rd cool time)
If a value greater than 0 has been programmed, it separates the secondand the third current block. Serves to reduce stress in the parts to bewelded.Refer to page 20.
The 3. CT can only be programmed if PstWLD is greater than 0.
HLD (Hold time)
Is used to fix the parts welded together while cooling down. No currentflows during this period of time.
The welding schedule is completed at the end of HLD.
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Program execution
6.2 Current blocks
For reasons of process technology, it may be necessary to supply theamount of heat required for a single spot weld in the form of consecutivecurrent blocks.
Therefore, a spot weld can be generated from a maximum of three current blocks (PreWLD, MainWLD, PstWLD), with each block being separately programmable in terms of duration and %I.
Cool times (1.CT, 3.CT) can be programmed in between the blocks. If acool time is set = 0, the relevant blocks are seamlessly performed.
PreWLD 1.%I
1.CT
Start program execution
MainWLD 2.%I
PstWLD 3.%I
3.CT HLD
1. Current block(Pre-heating time)
2. Current block 3. Current block(Post-heating time)
SQZ: Squeeze time (For description refer to Sect. 6.1 on page 17 et seq.).WLD: Weld timeHLD: Hold time (For description refer to Sect. 6.1)%I: Power/Heat (%I)
PreSQZ+
SQZ
End program execution
Fig.�5: Current blocks
1.WLD (1.weld time / Pre-heating time)
Using this current block, the metal can be pre-heated before the actualweld is performed (in the 2nd current block) using a suitable heat (1.%I).This allows you to reduce expulsions or drive out the adhesive.
If you do not want to use the PreWLD, simply program PreWLD=0.
MainWLD (main weld time / 2nd current block))
Welds the actual spot using the command heat (2.%I).• The MainWLD time has to be programmed in all instances.
• Within the MainWLD, the functions - ”Impulse mode” (refer to page 26) and - ”Slope” (refer to page 27) can be used.
PstWLD (post-weld time / post-heating time)
Using this current block, the metal can be post-heated after the actualweld has been performed (in the 2nd current block) using a suitableheat (3.%I).
The purpose is to prevent the spot from cooling too fast, e.g., as a resultof electrode cooling. This post-heating will improve the joint betweenthe parts to be welded and serves to balance stress.
If you do not want to use the PstWLD, simply program PstWLD=0.
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Program execution
6.3 Electrode force
Each welding program includes the information concerning the force tobe used by the electrode to squeeze the parts to be welded together(e.g. in kilo-Newton: kN).
The electrode force needed for a weld may be specified in the „Basepressure value“ parameter („Programming“ topic, „Schedule“ tab).
For additional information on electrode force, refer to page 56 et seq.
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Program execution
Notes:
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Functions
7 Functions
Several functions or partial functions described in this section areonly available in certain timer types.
The implementation of some function may vary in detail in the different timer types.
� Therefore please always also note the type-specific operating instructions of your timer.
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Functions
7.1 Schedule modes
In order to perform a welding process, the weld timer can be controlledautomatically by a PLC/robot or manually by the operator via start signal.
The following welding modes are available for different applications(type-dependent):
• Single spot
• Repeat
• Seam
7.1.1 Single spot
Suitable for use in connection with robots, welding machines, automaticwelding equipment or manual welding guns; for spot welding, projectionwelding, butt welding.
A high level at the start input initiates the welding schedule (the weldingprogram) exactly once, starting with the pre-squeeze time (1.SQZ).
For the next program start, the Start signal has to be switched off andback on.
Start
WC
a spot weldis generated
another spot weldis generated
Fig.�6: Single spot welding mode; signal sequence
7.1.2 Repeat
Suitable for manual electrode guns and manually operated welding machines.
The weld timer initially responds to the start signal as in single spotmode and starts the welding schedule with the PreSQZ.
If the corresponding start input is still high after the end of the hold time(HLD), the solenoid valve signal will be switched off via discrete outputsignal, if available. The welding gun is opened.
The Off time (OFF) runs. During this time, the operator can pull on thewelding gun towards the next spot.
After the end of the OFF time, the solenoid valve will be energizedagain, and the welding schedule will be restarted - this time beginningwith the SQZ. This sequence will be repeated for as long as the relevantstart input is high.
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Functions
When the start signal becomes low, the timer will terminate the actualcurrent cycle and start the hold time (HLD) instead of the OFF time.
Start
Solenoid
a spot weldis generated
another spot weldis generated
OFF
Fig.�7: Repeat welding mode; signal sequence
7.1.3 Seam
Suitable for roll seam systems. The parts to be welded are joined by individual spot welds while rollingelectrodes are moved along.
The weld timer initially responds to the start signal as in single spotmode and starts the welding schedule.
The weld time (MainWLD) and a cool time (2.CT), if programmed, will berepeated for as long as the start input remains high.
When the start signal becomes low, the timer will cancel the actual current cycle and start the hold time (HLD).
In seam operation, a distinction is made between a stitch weld and aseal weld.
Stitch seam: A series of weld times is separated in time by sufficientlylong cool times (2.CT) so that subsequent spot weldsneither touch nor overlap.
Seal weld: The cool time (2.CT) is configured very short so that subsequent spot welds overlap.
ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈ
2.CT MainWLD
Stitch seam Seal weldSeal weld
CT very short or 0
Fig.�8: Seam operation principle
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Functions
7.2 Impulse mode
In addition to the possibility of providing the amount of heat required fora single spot through 3 subsequent current blocks (refer to page 20),impulse mode may be used.
It serves to apply the required amount of heat in the 2nd current block tothe spot weld through up to 9 consecutive impulses.
A cool time (2.CT) can be programmed in between the impulses. If the 2nd cool time is set = 0, all impulses are seamlessly performed.
You can influence the impulse mode via the "Impulse" parameter. It determines how often the MainWLD is to be repeated with due regardto a programmed 2.CT.
Example: Impulse mode OFFIMP = 1MainWLD = 60 ms2.CT (not relevant because 1 impulse only)
Example: 2 ImpulsesIMP = 2MainWLD = 60 ms2.CT = 40 ms
Example: 3 ImpulsesIMP = 3MainWLD = 60 ms2.CT = 40 ms
2. current block
MainWLD
MainWLD2.CT
2. current block
2. current block
2.CT 2.CT
MainWLD
MainWLD MainWLD MainWLD
Fig.�9: Programming examples for impulse mode
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Functions
7.3 Slope (current increase)
If slope has been activated, the weld timer automatically generates alinear current increase/decrease for the 2nd current block within a programmable period of time. In this way, switch-on peaks and thus stress on the welding plant can bereduced.
For programming, you use
• upslope time (UST) to define the period of time during which the current is to increase from its "start value" to the commanded currentduring the MainWLD (2.%I), and/or
• downslope time (DST) to define the period of time during which thecurrent is to decrease from the MainWLD (2.%I) to the "final %I".
� Please note:
• The upslope/downslope times are always part of the 2. currentblock. The upslope time starts at the beginning of the 2nd current block. The downslope time ends at the end of the 2nd current block.
• The upslope and downslope times are not influenced by activeimpulse mode and a programmed 2.CT, if any. They are also performed throughout a possible 2.CT.
• If the total time of the UST and DST is longer than the 2nd currentblock, the command %I is never reached in the 2nd current block(2.%I)! Fault messages such as "Low current" will be output.
• In connection with the slope, you should use the fade-out time(refer to page 35).
Example: 3 impulses with slopeUST = 120 msDST = 40 msIMP = 3MainWLD = 60 ms2.CT = 40 ms
2. current block
2.CT 2.CTMainWLD MainWLD MainWLD
UST DST
Fig.�10: Example: Slope in connection with impulse mode
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Functions
7.4 Welding modes:
The timer offers you different welding modes:
• Phase angle (PHA)
• Constant-current-regulation (KSR)
• UI-regulation (UIR).
It is possible to set how and which welding mode is to be used in a program:
• Standard mode:The PHA or KSR welding mode applies to all 3 weld times of the program.
• Mixed mode:The PHA or KSR welding mode can be separately configured foreach weld time.
If activated in a program, UI regulation only applies to the MainWLD.
7.4.1 Phase angle (PHA)
Special case.
PHA mode does not involve regulation of an actual value (e.g. current)but only controls the power unit.
• In PST the activation of the thyristors is influenced during the sinehalf-wave (el. ignition angle: 130 degrees to 30 degrees).The bigger the ignition angle, the less current flows in the secondarycircuit.
• For PSI, the pulse width is influenced.
PHA features:
• The %I values are programmed as scale values (%I).Programmable range: 0 to 100 %I.Programming resolution: 0.01 %I
• No regulation takes place.
• The resulting amount of current in the secondary circuit depends onthe secondary circuit resistance and the secondary voltage.
• A current sensor is not necessary from the point of view of regulationtechnology.
Current or time monitoring can be activated in PHA mode. A current sensor is absolutely necessary for current monitoring. If theintegrated current sensor is not used, a current sensor must beprovided on the secondary side.
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Functions
Mains
Power unit
Welding transformer
Actual current valueMeasured valuepreparation
kA actual current
mean phase anglein %I
Actual value display
- Tolerance band
Current monitoring
-Status-Error
programmable reference current (in kA)
Current sensor(only required withcurrent monitoring onthe secondary side)
Actual currentvaluefor display
purposes only
ElectrodesProgramming:Commanded %I valuein %I
without currentmonitoring
with currentmonitoring
Fig.�11: Principle of open-loop PHA mode
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Functions
7.4.2 Constant-current regulation (KSR)
Standard case.
Current regulation has been activated in KSR mode. For this purpose,the actual current is scanned by a current sensor (programmable: secondary or primary side) and permanently compared to the programmedcurrent. A downstream current controller processes the differencebetween actual/programmed value and controls the power unit so thatthe programmed current is reached.KSR features:
• The %I values are programmed in kilo-Amps (kA).Programmable range: 0.5 to 250 kA (can be restricted by parameter settings and the power unit used). Programming resolution: 10 A
• There is closed-loop control of the current in the secondary circuit.• Eliminates the influence of the secondary circuit resistance on the
weld (e.g. transfer resistance between electrode and part to be welded).
• A current sensor is absolutely necessary from the point of view ofregulation technology. If the integrated current sensor is not used, acurrent sensor must be provided on the secondary side.
Controller
Mains
Power unit
Welding transformer
Actual current valueMeasured valuepreparation
Actual value display
- Tolerance band
Current monitoring
-Status-Error
Electrodes-
Programming:Commanded currentvalue in kA
kA actual currentmean phaseangle in %I
programmable reference current (in kA)
Current sensor(only required formeasurement on thesecondary side)
Fig.�12: Principle of KSR regulation mode with secondary current sensor
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Functions
7.4.3 UI regulation (UIR)
This function is only available if the "UI Regulation" option has beenactivated!
The U/I controller measures not only the welding current, but also thevoltage at the electrodes. In this way, more profound information can beobtained with respect to the welding process, and an adaptive intervention by the controller can be achieved if influencing variables arepresent.
For detailed information refer to description of application „PSI 6xxx:UI regulation and monitoring“.
7.5 %I prewarning and limitation
The mean phase angle (%I value) generated is checked after eachwelding schedule. In case of limit value violations the timer generates acorresponding warning.
These warnings are reset• at the next tip dress operation• at the next electrode change• at reset of the %I values via BOS (”Warning” window, ”%I warning”
tab).
7.5.1 %I limitation
The "%I Limitation" parameter is used to define the maximum permitted%I value that may be generated by the inverter.
If the %I limitation responds, the timer will output the message "Maximum phase angle".
The input value for %I limitation has an absolute effect! The "%I correction" (refer to page 60) and "%I stepper" (refer to page46) functions can trigger a %I limitation response for this reason.
In some timer types, this value cannot be changed in BOS. In thesecases, it is internally fixed to 100 %I.
7.5.2 %I warning
%I values generated which are higher than the ”%I warning” parameterwill trigger the ”Phase angle warning reached” message.
As a result, the timer may draw the operator's attention to an imminent%I limitation - due to, e.g., line losses in the secondary circuit - in KSRregulation mode.
The parameter value must be lower than the value for the %I limitation.
7.5.3 Lower %I warning
%I values generated which are lower than the ”Lower %I warning” willtrigger a corresponding message.
The parameter value must be lower than the value for the %I warning.
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Functions
7.6 Monitoring
The timer is capable of monitoring the weld for the following quantities:
• current (refer to section 7.6.1 on page 33 et seq.)
• time (refer to section 7.6.2 on page 38 et seq.).
Both monitoring functions can be separately turned on and off.
An activated monitoring function checks the relevant actual valueagainst programmable reference values and tolerance bands.
As the "current" and "time" parameters influence the amount of heat inthe spot, a correct setting of the reference values and activated monitoring functions are essential measures and conditions for quality assurance.
The reference values used for current monitoring can be programmed independent of the regulation parameters! Changing theregulation command values does not influence the monitoring parameters!If he has suitable access privileges, the user may set new referencevalues manually, or accept a measured actual value as the new reference value.
Further monitoring functions
• Monitor stepper:
Acts in conjunction with Current monitoring if stepper/dressingcurves are active. Refer to page 38.
• Tip dresser result monitoring:
Acts in conjunction with Tip dressing. Refer to page 52.
• Monitoring the process quality (UIP), process stability (PSF) andforce (FQF):
Acts in conjunction with UI regulation and the "Q Stop" function. Refer to page LEERER MERKER.
• Monitoring tip dress (dresser blade):
Refer to page 54.
• Monitoring gun life:
Refer to page 55.
• Monitoring phase angle (%I warning):
Refer to page 31.
• Measuring loop test:
Refer to page 39.
• Minimum current verification:
Refer to page 40.
• Post-warming pulse:
Refer to page 42.
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Functions
7.6.1 Current monitoring
Tolerance ranges
In current monitoring, the actual current determined by rms value measurement is compared to the "tolerance band".
Whether or not the timer interprets a measured actual current as "acceptable" depends on the programming of the tolerance band. The following values are decisive for the definition of the tolerance band:
• Reference current in kA
• positive tolerance in % of the reference current (upper tolerance band).Actual values above the upper tolerance band generate the message type �”High current ...”.
• negative tolerance in % of the reference current(Lower tolerance band).Actual values below the lower tolerance band generate the messagetype ”Low current ...” or "No current ...".
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Reference current in kA
upper tolerance band(in %)
lower tolerance band (in %)
toleranceband
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
High current ...
Low current... / No welding current...
Current ok
Fig.�13: Principle: tolerance band
Conditional tolerance range
In addition to qualifying welds as “good/bad", it is often also desirable tobe timely informed about the trend of the current actual values. Especially, an increasing number of actual current values in the lower rangeof the tolerance band is of interest: Gradual faults of the system (e.g.slow increase in cable resistance in the secondary circuit prior to an interruption of a cable) may result in such effects.
For this reason, the following parameters are additionally available inconnection with the tolerance band (BOS: ”Programming” topic,”Schedule” tab):
• "conditional tolerance band" (in % of the reference current) and
• ”Reweld factor”.
The "conditional tolerance band" parameter defines the program-specific upper limit of the conditional tolerance range. The lower limit isdefined by the "lower tolerance band" parameter.The "Reweld factor" determines the program-specific number of consecutive welds that may be within the conditional tolerance range. If thenumber of consecutive welds within the conditional tolerance range ishigher, the message "Series of welds below lower threshold point ..."will be output.
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Functions
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Reference current in kA
upper tolerance band(in %)
lower tolerance band(in %)
Conditional tolerance range
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
High current ...
Low current... / No welding current...
with respect to asingle measurement:Current ok
Conditional toleranceband (in %)
spots welded"Series of welds below lower threshold point" message
Fig.�14: Example: principle of the conditional tolerance band with a Reweld factor = 4
Messages can be defined as either "welding faults" or "warnings".While an event defined as a "warning" does not inhibit the timer, a"welding fault" must always be followed by "Fault reset" before starting the next welding schedule.
Current monitoring modes
Since a total of 3 independent current blocks can be programmed (referto page 20), it is necessary to handle current monitoring with the required degree of flexibility.
For this reason, a distinction is made between "Standard" and "Mixed"monitoring modes.
• Standard mode:
The entire current profile (1st, 2nd and 3rd current block includingcool times) is included in rms value measurement.
The complete current profile is represented by a single actual value,and monitored by a single tolerance band.
Although this simple and often sufficient monitoring mode keeps theamount of data to be processed low, any cool times that may havebeen programmed and different amounts of current in the individualblocks alter the measured result.
The reference current to be indicated should be determined by testwelds in this case. If you only use the MainWLD without impulse orslope operation, you can specify the commanded current programmed for regulation as reference current as well.
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Functions
Measuring time
PreWLD1.CT 3.CT PstWLD
* *
*: 2.CT
2nd block
Tolerance band
Referencecurrent
1stblock
3rdblock
Fig.�15: Principle of "Standard" monitoring mode
• Mixed mode:
The rms value is measured separately for each current block andmonitored by individual tolerance bands (for 1st, 2nd and 3rd currentblock). The programmed cool times are not accounted for in the determination of the actual value for the individual current blocks.
This results in higher transparency of the individual current blocks,however, the amount of data to be processed is larger.
In mixed mode, you can generally use the commanded currents programmed for regulation as reference currents as well.
Referencecurrent
1stblock 3rd block
Measuring time 1 Measuring time 32nd block
Measuring time 2 = t1 + t 2 + t3
Reference current
Referencecurrent
t1 t2 t3
: Tolerance band
Fig.�16: Principle of "Mixed" monitoring mode
Fade out time and trail current
In the previous explanations, the current curve as a function of time wasrepresented by an ideal graph (in rectangular shape). In reality,however, there is a current upswing and downswing at the beginningand after the end of any weld time. Due to their very nature, these effects affect rms value measurements. For this reason, programming different values as the commanded and reference current (in connectionwith current monitoring) may be necessary.
The course of measurement can be specifically influenced using the"fade-out time" and "trail current" functions.
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Functions
• Fade out time:
Indicates the period of time after the start of a weld time during whichthe measured current values should not be used in the determination of the rms value.
The total upswing process can thus be faded out if the setting ismade correctly.
Time
Current
Weld time
Fade out time
Irms_1
Irms_2
Irms_1: Fade out time accounted forIrms_2: Fade out time not accounted for
Fig.�17: Effect of the fade-out time
Use of the fade-out time
• In connection with the "Slope" function (refer to page 27):you should program the same value for the fade-out time as forthe upslope time (UST).
• When welding very thick sheets and great immersion depths (gunprojects far into the material).
• In connection with current calibration:Reference ammeters also have a "fade-out function" (e.g. Miyachi "First Cycle"; to specify the first cycle of the weld time whosemeasured values are to be considered).In connection with current calibration, you should therefore makesure that the metering device used has been set to the timer's current fade out time setting.
• Trail current:
Indicates whether or not the downswing process at the end of a weldtime is to be included in the calculation of the rms value (trail currentON).
If trail current is switched off, rms measurement of the current valuewill exactly terminate at the end of a weld time.
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Functions
Time
Current
Weld time Trail current
Fig.�18: Trail current
Start times of fade-out time and trail current
1stblock 3rd block
2nd block
Fade out time:
Trail current:
Fig.�19: Start times of fade-out time and trail current
The programmed fade out time is identical for all weld times and forall welding programs.Therefore, you should make sure that the fade out time is alwaysshorter than the shortest programmed weld time!
The programmed trail current is identical for all weld times and for allwelding programs!
If the only quality criterion for your application is the amount of heatapplied to the spot weld (amount of heat: Q ≈ i2 x t x R), you shouldprogram "0" for the fade-out time and switch the trail current ON.
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Functions
7.6.2 Time monitoring
Time monitoring can be separately configured for each program andcompares the actual time required for the complete current profile to aprogrammed reference time.
Actual time: the period of time from the beginning of the first currentblock until the end of the last current block including all cool times, if programmed.
In this way, it can be ensured that no excessive weld time changes canbe made manually in the individual welding programs.
The following values are decisive for programming time monitoring:
• Time monitoring ON/OFF
• Reference time.
• Permitted time tolerance with respect to the programmed referencetime.Actual times above the permitted time tolerance generate the message type ”Weld time too long ...”. Actual times below the permitted time tolerance generate the message type ”Weld time too short ...”.
Reference time
PreWLD1.CT
3.CT PstWLD
* *
*: 2.CT
2nd block
permitted time tolerance
1stblock 3rd block
Fig.�20: Principle of time monitoring
7.6.3 Monitor stepper
Is used in conjunction with the electrode management functions
• ”Stepper” (refer to page 46) and
• ”Tip dressing” (refer to page 49)
for monitoring the programmed %I stepping.
In this way, it can be ensured that no excessive changes can be mademanually with respect to the individual stepper or tip dress curves.
If %I stepping is active, the timer changes the programmed %I subjectto the electrode count value. Using the ”Monitor stepper” function the timer is able to change the pertaining programmed reference value appropriately, also in dependenceon the electrode wear.
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Functions
7.6.4 Measuring loop test
This function checks the relevant sensor circuit for interruption andshort-circuit during the squeeze time while secondary current measurement is active. Faults in the area of the cables/current sensor can bedetected in time by this function.
The following testing criteria apply:
Ohmic resistance measured Result
< 7 ohms Measuring loop short circuit
12 to 950 ohms Measuring loop ok
> 1100 ohms Measuring loop open
If measured values are in the intermediate ranges, they cannot beclearly evaluated.
If a fault has been detected, the weld timer will abort the running weldingprogram before initiating the first programmed weld time, the timer willbe inhibited and generate the "Measuring circuit open" or "Measuringcircuit shorted” message.
To activate the function, switch the "Measuring loop check" parameter"On".
Conditions:
• Parameter "Inhibit monitoring" has been switched off and
• ”Current monitoring” function (refer to page 33) has been switchedon.
Messages can be defined as either "faults" or "warnings". While anevent defined as a "warning" does not inhibit the timer, a "fault" mustalways be followed by "Fault reset" before starting the next weldingschedule.
NOTICE
Incorrect declaration of process-critical messages
Excessive weld current possible!
� Make sure that the messages "Measuring circuit open" or "Measuring circuit shorted" are defined as "faults" in any case.
The controller receives incorrect actual value information, or noinformation at all. As a result, the controller may fully activate thepower unit initially.The point of time in which the timer eventually cancels the weldingschedule with a fault message depends on the "Minimum currentverification" function (refer to Sect. 7.6.5).
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Functions
7.6.5 Minimum current verification
This function checks whether, from the beginning of WLD, a minimumaverage current was measurable for a selected period of time (parameter "Time to terminate weld time"). Otherwise, the timer interrupts the sequence and outputs the fault message ”No welding current”.
7.7 Latching
When the SQZ has elapsed, the timer will start to be latching in the welding mode "single spot". In latched condition, the PreWLD to PstWLD including HLD will continue to be executed even when the start signal hasbeen reset.
Signal latching can only be cancelled by opening the stop circuit.
Signal latching is not available in "seam" welding schedule. If thestart signal is reset during a weld time in "seam" mode, the timer willcomplete the cycle just initiated and continue with the hold time.
7.8 Automatic reweld by timer active
Reweld by timer active is only possible in PHA or KSR welding mode.
This function reduces the need for operator interventions in the event ofsporadic welding faults of the type "Low current ..." or "No current".
Conditions:
• Current monitoring is active and
• "Monitoring stopped" function has been turned off.
Automatic reweld by timer active can be turned on and off separately foreach welding program using the "Reweld" parameter” (BOS: ”Programming” topic, „Schedule“ tab”).
When automatic reweld by timer has been activated, the timer is able toautomatically repeat an improper welding schedule once - starting withSQZ - if "Low current ..." or "No current" has been signaled. In this case,the gun will remain closed after the improper schedule, and the programmed squeeze time, weld times and hold time are repeated. The event is logged additionally.
If the reweld results in a proper weld, the welding system will continuerunning normally afterwards. If the reweld results in another fault, thecorresponding message will be output ("Low current ...", "No current...”).
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Functions
It may be a problem that every single spot may have to be rewelded inthe event of bad fits or electrodes that do not have optimum contact withthe metal in extreme cases if reweld has been activated. As a result, thecycle time may strongly increase without even being noticed.
For this reason, the timer offers the global parameter "Max. rewelds"(maximum number of rewelds by timer).An internal counter is reset to 0 whenever a weld is ok after the first attempt. In return, the counter is incremented if the current remains belowthe "lower tolerance band" and automatic rewelds have been activated.Automatic rewelds are carried out only if the internal counter value islower than/equal to the "Max. rewelds" parameter. If this is not the case,the timer will generate the "Series of welds below lower threshold point"message.
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Reference current in kA
upper tolerance band(in %)
lower tolerance band(in %)
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎHigh current ...
Low current... / No welding current...
Currentok
Welds"Series of welds below lower threshold point" message
Weld triggered byautomatic reweldby timer.
:
Fig.�21: Example: Principle of automatic reweld by timer using "Max. rewelds" = 4.
Messages can be defined as either "faults" or "warnings". While anevent defined as a "warning" does not inhibit the timer, a "fault" mustalways be followed by "Fault reset" before starting the next weldingschedule.
NOTICE
Incorrect declaration of process-critical messages
Defective welds may remain undiscovered!
� Make sure that the messages ”Low current ...”, ”No current ...” and”Series of welds below lower threshold point” are always definedas "fault".
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Functions
7.9 1. Halfcycle limit
The function or the parameter is only available for PST types.
The first current half-cycle value can be limited in order to protect thewelding transformer and thyristor unit.
Example: Input value of 55 %I means
• the 1st half-cycle will not be influenced by welds with low programmed %I (0 to 55 %I).
• for higher programmed %I values (> 55 %I), the 1st half-cycle will belimited to 55 %I.
Two parameters are available for programming:
• "1st half-cycle limit":Parameter acting globally for the weld timer.Only the first half-cycle of a weld will be limited.
• "1. half-cycle after cool time":Can be separately set for each welding program.The first half-cycle of each weld time or each pulse is limited if a cooltime greater than 0 has been programmed before.
7.10 Post-warming pulse (NWI)
The functionality changes the default behavior of the timer
• during monitoring in PstWLD,
• in the case of a fault and
• in the case of reweld.
Program the function in the ”Post-warming pulse” window (”Programming” topic, ”Schedule” tab, ”NWI” command button). To deactivate the function, the ”Upper tolerance band PstWLD” is set tothe value of the ”Upper tolerance” there.
Monitoring of PstWLD
In addition to the inputs and definitions of the known limit values forlower, upper and (lower) conditional tolerance, it is possible to define an”Upper tolerance band” incl. the corresponding repeat factor specifically for PstWLD:
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Reference current in kA
Upper tolerance (in %)
Lower tolerance (in %)
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
High current ...
Low current... / No current
Cond. tolerance band (in %)
Upper tolerance band PstWLD (in %)
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Functions
”Repeat factor” defines program-specifically how many consecutivewelds of a spot may lie between the ”Upper tolerance band PstWLD”and the ”Upper tolerance”. If the number of consecutive welds withinthis range is higher, the message ”High current in consecutive welds”will appear.
NOTICE
Incorrect declaration of process-critical messages
Defective welds may remain undiscovered!
� Make sure that the message: ”High current in consecutive welds”is always defined as "Fault".
Behavior in the case of faults
Fault Reaction without NWI Reaction with NWI
Series of welds belowlower threshold (PstWLD) No automatic spot re
petition
Automatic spot repetition
Low current (UI monitoring)
High current in consecutive welds (PstWLD)
none because the”Upper toleranceband PstWLD” is notrelevant in this case.
Behavior in the case of reweld
In order to repeat the welding schedule, the timer increases the %I ofMainWLD by the program-specific ”Increasing factor”. In the same way as for the correction functions (refer to page 60), anincrease factor of e.�g. 0% means: no %I increase.
A reweld principally only takes place if the permitted maximum %I isnot exceeded by the %I increase (also refer to Sect. 7.5, page 31).
The %I increase is effective both in case of a reweld triggered automatically (refer to page 40 et seq.) and a reweld triggered via input signal(”Fault reset with reweld” signal).
Special features in connection with the ”NWI” function.
• PstWLD is not monitored as soon as at least one UI monitoring parameter has been activated in the relevant program.
• PstWLD is not monitored if ”Standard” monitoring mode has beenset in the relevant program instead of ”Mixed”.
• When the UI controller is active and the ”PHA” regulation mode isused at the same time (in PstWLD), %I values in accordance with thereference curve will be input to generate the %I for PstWLD.
• The original reference current for monitoring PstWLD can beentered manually in the ”Post-warming pulse” window for documentation purposes. It does not have a functionality within the timer and isnot changed by the timer.
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Functions
7.11 Electrode management
In the course of their life, electrodes are subject to process-related wear(count value; refer to Section "Wear counter and wear (count) factor"),which manifests itself by a larger contact surface, among other features.
Wear
Fig.�22: Enlarged contact area through electrode wear
The timer offers two methods of compensating this effect, which can beused in isolation as well as in combination:• automatic %I stepping (Stepper, refer to page 46 and• Tip dressing (refer to page 49).
Wear counter and wear (count) factor
Electrode wear depends on different factors, such as programmed %I,thickness and material of the parts to be welded.For as long as only one material type of identical thickness is welded inthe course of an electrode's life with identical %I, the number of weldsthat can be performed before an electrode is worn and must be replaced can be predicted based on experience. Electrode wear can be mapped by a "spot counter" in this case. Thespot counter is simply incremented by "1" after each spot welded.
However, if different materials or material thicknesses are welded in thecourse of the electrode life, the wear per spot no longer is constant. Aspot counter is inappropriate in this case.
For this reason, the electrode wear is monitored by a "count value (wearcounter)" integrated in the timer.Using this function, the timer increments the count value after each spotwelded by the "count factor” (BOS: ”Programming” topic, ”Stepper”tab). As a result, the count value cannot only be incremented by "1" (likethe spot counter), but rather by any desired values.As it is possible to specify the count factor that fits the weld performedby each individual program, proper recording of the electrode's wear isensured.
Wear per component
The parameter "Wear per component" (BOS: ”Programming” topic,”Stepper” tab) is used to enter the wear occurring on the electrode whena single part is welded. This value is used by the timer to calculate thenumber of parts that can be welded by an electrode until the End ofStepper is reached. The number of remaining parts is displayed in the"Warning table" (refer to page 51).
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Example:
6 welds have to be performed on a part. Every single spot (P1 to P6) is generated by a separate welding program (Prog1 to Prog6). The upper 3 spots (P1 to P3) have to weld 2 sheets, the lower 3 spots(P4 to P6) have to weld 3 sheets, each. Consequently, electrode wear is higher for spot welds P4 to P6 (greatermaterial thickness). For this reason, the program-specific count factor isdefined by the value "1" for Prog1 to Prog3, and by 1.5 for Prog4 toProg6.The resulting wear per component is 7.5.
The count factors in this example are of an exemplary nature only. Inpractice, they are determined in advance with respect to the materials and thicknesses used.
P1.CF=1
Counts:
P2.CF=1
P3.CF=1
P6.CF=1.5
P5.CF=1.5
P4.CF=1.5
0(new electrodes)
1 2 3
4.567.5CF: Count factor
Fig.�23: Example: Determining the count value
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Functions
7.11.1 %I stepping (Stepper)
%I stepping keeps the current density constant in the spot weldthroughout the electrode life although the spot increases in size. Forthis purpose the system changes the %I automatically in dependenceon the current electrode wear.An optimal adaptation of %I stepping to your application is possible bymeans of the „Start“, „Stepper“ and „Dressing“ function areas which areconfigurable separately (in the „Programming“ topic, „Stepper“ tab).
The resulting %I changes can be monitored using the "Monitor stepper" function (refer to page 38).
„Start“ function area:
Allows %I to be influenced directly after tip change and - if parametrized- after each tip dress operation.Using the „%I for new electrode“ parameter you can determine the percentage of the programmed base %I which is to be effective at a tipwear rate of „0“. The „Count“ parameter can be used to additionally define up to what„Actual count“ the %I is to be changed again linearly to 100% of theprogrammed base %I.
To deactivate the %I stepper for the „Start“ function area, programthe „Count“ parameter with the value „0“.
If the „Start“ function area is active, this influences the effect of the„Stepper“ function area.
Act. count
Power (heat, %I) in %(with reference to the programmed base %I)
100%
Value in „%I for newelectrode“ para
meter
„Count (wear)“parameter
1 linear stepper curveresulting heat (%I)
0%
Count (wear) = 0
Fig.�24: Operating principle of stepping in the „Start“ function area
„Stepper“ function area:
Using the „%I at end of 1. stepper phase“ parameter it is possible to determine what percentage of the programmed base %I is to be effectivewhen the „Actual count“ wear counter reaches the „Max. count“ value.Using the „Stepper curve“ parameter it is possible to additionally selectone out of max. 10 curves (from the „Setup“ topic, „Stepper curves“tabs).A stepper curve determines the percentage of the „%I at end of 1. stepper phase“ parameter value that is to be effective in dependence on the
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„Actual count“. It thus describes the course of %I in dependence on the„Actual count“.
To deactivate the %I stepper for the „Stepper“ function area, program the „%I at end of 1. stepper phase“ parameter with the value„100“.
Act. count
„Max. count“ parameter
one out of 10 stepper curvesresulting heat (%I)
Power (heat, %I) in %(with reference to the programmed base %I)
Count (wear) = 0
100%
Value in the „%I atend of 1. stepper
phase“ parameter
Fig.�25: Operating principle of stepping in the „Stepper“ function area
„Dressing“ function area:
You can use „%I after last dressing“ to determine the percentage of theprogrammed base %I that is to be effective when the „Actual count“wear counter reaches the value of the „Max. count“ parameter and the„Actual“ tip dress counter reaches the value of the „Dressing steps“parameter.The „Tip dress curve“ parameter may be used to additionally select oneout of max. 10 curves (from „Setup“ topic, „Tip dress curves“ tab).
A tip dress curve determines the percentage of the „%I after last dressing“ parameter value which is to be effective in dependence on the „Actual“ tip dress counter. It thus influences the amount of stepping after atip dress operation.
To deactivate the %I stepper for the „Dressing“ function area, program the „%I after last dressing“ parameter with the value „100“.
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Act. count
Example: Number of dressings („Dressing steps“ parameter) = 4
one out of 10 tip dress curve shapesresulting heat (%I)
1 20 3 4Tip dress counter:
Power (%I) in %(with reference to the programmed base %I)
Value in „%I afterlast dressing“ para
meter
Count (wear) = 0
100%
Fig.�26: Operating principle in the „Dressing“ function area
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7.11.2 Tip dressing
Tip dressing cleans the electrode tip and periodically restores the desired contact surface throughout the electrode life.
For this purpose, the electrodes must be dressed accordingly in anelectrode dressing station whenever a certain count is reached.
A number of type-specific signals are available to inform the robot/thePLC when the tips of the current gun (=�electrode assigned to the selected welding program) have to be dressed.
These signals are only used if the electrode management functionshave been activated (BOS: ”Programming” topic, ”Stepper” tab,"Stepper" parameter: ON).
The signal names may vary depending on the timer type. Therefore use the type-specific operating instructions of your timerto inform yourself about what signals are available.
The timer requests tip dressing by means of an output signal designated accordingly.
Using an acknowledgment input (e.�g. ACKNOWLEDGE TIP DRESS)the robot is able to increment the timer-internal tip dress counter andreset the timer-internal wear counter of the current gun after the dressing operation.
If the electrode 0 has been programmed in the selected welding program, the input will influence all internal tip dress and wear countersin some timer types!
As feedback for the robot some timers reflect the status of the acknowledgment input to a dedicated output.
Other functions in connection with tip dressing
• Start tip dress:
Initial dressing can be activated by the parameter "Dress new electrode" (BOS: ”Programming” topic, ”Electrode” tab).When start tip dress is active, the timer will immediately request tipdressing when an electrode has been replaced using an output signal.
For new electrodes, this serves to, e.g.- obtain a defined size of plug - obtain a defined application angle - remove a protective coating.
• Monitoring the tip dressing result:
Some timers are able to check whether tip dressing was successful. For detailed information, refer to Section 7.12 page 52.
• Monitoring tip dresser (dresser blade):
Some timer types can monitor whether or not the dresser blades arereplaced in the intervals provided.For more information on this topic, refer to Section 7.13 page 54.
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• Activating tip dress stations:
A tip dress management for activation of external tip dress stationshas been integrated in some timer types.For more information on this topic, please refer to the type-specificoperating instructions.
7.11.3 Warning and end of Stepper
When the maximum acceptable count value is reached, new electrodetips have to be used.
A number of type-specific signals are available to inform the robot/thePLC when the tips of the current gun (=� electrode assigned to the selected welding program) have to be changed.
These signals are only used if the electrode management functionshave been activated (BOS: ”Programming” topic, ”Stepper” tab,"Stepper" parameter: ON).
The signal names may vary depending on the timer type. Therefore use the type-specific operating instructions of your timerto inform yourself about what signals are available.
The timer requests a tip change by means of an output signal designated accordingly. It is set when the ”Max. count” limit value is reached or exceeded (”Programming” BOS topic, ”Stepper” tab).
Using an acknowledgment input (e.�g. ACKNOWLEDGE ELECTRODES HAVE BEEN CHANGED) the robot is able to reset the timer-internal electrode-specific tip dress counter and the timer-internalelectrode-specific wear counter of the current gun after changing theelectrode (tip). This event is interpreted and logged by the timer as „Tip change“.
If the electrode 0 has been programmed in the selected welding program, the input will influence all internal tip dress and wear countersin some timer types!
As feedback for the robot some timers reflect the status of the acknowledgment input to a dedicated output.
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7.11.4 Warning table
The BOS window ”Warning table” provides an overview of and quick access to all important information and operations with respect to electrodes whose electrode management function is active (BOS:”Programming” topic, ”Stepper” tab, parameter ”Stepper”: ON):
• Weld timers to which the individual electrodes have been assigned,
• actual counts (percentage, numerically and graphically). The graphic representation is color coded. Any imminent warnings,tip dress requests or the reaching of the end of stepper can bequickly detected.
• Remaining parts that can still be manufactured using the respectiveelectrode.
For a correct output of the remaining parts, the electrode-specific"Wear/Comp." parameter must be adjusted (BOS: ”Programming”topic, ”Stepper” tab).
• Manual reset of wear counters by the user after a tip change.
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7.12 Tip dresser result monitoring
The ”Tip dresser result monitoring” function checks whether the electrode dressing was performed correctly. An activation of the monitoring function is always expressed as warning. As a result, an ”error” does not require user intervention - the robotcan repeat the dressing operation automatically.
Requirements for monitoring:
1. Definition of a welding program (for each electrode). Both reference welds as well as a subsequent monitoring weld areperformed using this program.
Required settings:- PreWLD and PstWLD = 0- MainWLD: PHA mode- %I stepping (Stepper): OFF- %I correction = 0- the electrode to be tested must be assigned to the program- HLD greater than / equal to 20 ms- WC start time greater than / equal to 0 ms
2. Execution of 2 reference welds.They are used to determine the currents that flowed in MainWLD
• following a proper dressing (visual inspection!) of a new electrode(= case 1) and
• directly before another required dressing (= case 2).
These currents are stored as electrode-specific reference currentsand used as comparison criteria for later monitoring welds of the actual current measured then.
The currents which flowed are treated as actual values within thetimer and displayed in the ”Programming” BOS topic, ”Electrode” tabunder the ”Tip dresser result monitoring” parameter group. That is why changes of these values do not appear in the datachange log and are not saved via backup.
The following applies to a subsequent check of a successful electrodedressing:
• After correct dressing, the actual current of the monitoring weldshould clearly differ from the actual current of the reference weld before dressing (refer to case 2 above).
• After correct dressing, the actual current of the monitoring weldshould approximately correspond to the actual current of the reference weld after dressing (refer to case 1 above).
A separate tolerance band must be parametrized for both situations(”Programming” BOS topic, ”Electrode” tab under the ”Tip dresser result monitoring” parameter group) which is used for evaluation of the actual current of the monitoring weld.
Tolerance value inputs are always taken into account in the backup.Tolerance changes appear in the data change log.
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1st test
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Reference currentin kA
+toler. before tipdressing(in %)
prohibited range
is identified by the reference weld directly beforea new required dressing
-toler. before tip dressing(in %)
Current ok
Iact MONIact MON: Actual current during monitoring weld
Current ok
prohibited range
Fig.�27: ”Tip dresser result monitoring” function: Effect of the tolerance bands - Testing 1 (for prohibited range)
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Reference currentin kA
+toler. new electrode(in %)
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Current ok
is identified by thereference weld afterdressing
-toler. new electrode(in %)
Current ok
Iact MONIact MON: Actual current during monitoring weld
2nd test
prohibited range
prohibited range
Fig.�28: ”Tip dresser result monitoring” function: Effect of the tolerance bands - Testing 2 (for permitted range)
The dressing operation is regarded as good when test 1 and test 2 during monitoring weld were successful. Otherwise the timer sets the TIP DRESSING DEFECTIVE output (ifavailable).
Since phase angle values are programmed for reference and monitoring welds as %I input, mains voltage fluctuations may influence theactual current and thus the test result.
� Therefore the tolerance bands should be dimensioned so that theycompensate normal mains voltage fluctuations safely but do notoverlap!
Relevant signals for the ”Tip dresser result monitoring” function:
• Input REFERENCE WELD FOR NEW ELECTRODE
• Input REFERENCE WELD TIP DRESS
• Input MONITORING WELD
• Output REFERENCE WELD ACTIVE
• Output MONITORING WELD ACTIVE
• Output TIP DRESSING DEFECTIVE
Please refer to the type-specific operating instructions of your timerfor the addresses to which these signals are assigned in the I/O interface.
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Default settings of the ”Tip dresser result monitoring” function:
• both reference currents of each electrode: 0 kA
• all 4 tolerance values of each electrode: 100 %
(”Programming” BOS topic, ”Electrode” tab under the ”Tip dresser result monitoring” parameter group”).
With the default settings the limit values are chosen at a high level sothat the function does not signal a dressing fault.
If you do not want to use one of the two checks, simply parametrizetheir tolerance limits with 100%.
7.13 Monitoring dresser change
This function serves for wear monitoring of the tip dressers used. Ithelps to prevent damages resulting from imperfect electrodes or bad tipdress results caused by worn tip dressers in advance by replacing thetip dressers in time.
For this purpose, the timer offers not only the ”normal” tip dress counter(which is reset after each electrode replacement) but also an additionalcounter (value ”Act. cutter status”). This tip dresser wear counter is notreset by an electrode replacement.
The timer increments the relevant cutter status counter wheneverdressing is performed on an electrode. When it reaches its programmedwarning value (value ”Tip dresser change warning”) or maximum value(value ”Tip dresser end of life”), certain output signals will be set.
To deactivate wear monitoring of a tip dresser, set the ”Tip dresserend of life” parameter to ”0”.
Tip dresser wear counters can be reset by the programming terminal(BOS), but also via input signal.
Please refer to the type-specific operating instructions of your timerfor the addresses to which the pertaining signals are assigned in theI/O interface.
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7.14 Gun life monitoring
This function serves for wear monitoring of the guns used. It helps toprevent damages resulting from increasing wear of the electrode gun inadvance by replacing the gun in time.
For this purpose, the timer offers not only the ”normal” wear counter(which is reset after each electrode replacement) but also an additionalcounter (value of ”Act. gun life”). This gun life counter is not reset whenthe electrode is replaced.
The timer increments the relevant gun life counter whenever a spot iswelded, provided that the maximum value (value "Maximum gun wear")has been programmed > 0. Once it has reached its programmed warning value (value "Gun wear warning") or its maximum value (value"Maximum gun wear"), the related output signals will be set and at thesame time a corresponding message will be displayed by BOS.
To deactivate gun life monitoring of a gun, program "0" for the relevant "Maximum gun wear" parameter.
Gun life counters can be reset by the programming terminal (BOS),but also via an input signal.
Please refer to the type-specific operating instructions of your timerfor the addresses to which the pertaining signals are assigned in theI/O interface.
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7.15 Outputting the electrode force
For outputting the force actuating variable, the following options - depending on the timer type - are available:
• an analog signal at X2Voltage range of values: 0 to 10 VDCCurrent range of values: 0 to 20 mA and 4 to 20mA
The type of analog output can be set in the ”Programming” BOStopic, ”General” tab using the ”Pressure output mode” parameter.
• serial output signals at the digital interface.Range of values: type-specific
For information on the actuating variables available, please refer tothe type-specific operating instructions of your weld timer.
The value of the output signal that corresponds to the programmedforce is calculated using an internal characteristic. Alternatively, the internal characteristic can be generated as follows:
• automatically via force calibration (refer to Section 7.16.1 from page57), or
• manually by means of parameters ”Conversion factor” and ”Zero adjust”.
� In order to ensure that the programmed force actually acts on theelectrodes in case of servo guns, a proper calibration of the servogun circuitry is necessary!
In the course of force calibration, the current values of the ”Conversion factor” and ”Zero adjust” parameters are overwritten!
Other functions in connection with electrode force
• Pressure profile: For each welding program, 10 different force values can be separately programmed which are activated at certain points of time withinthe welding schedule.
• Pressure stepping:Depending on the stepper or tip dress curve selected, you can definethe percentage by which the programmed base pressure value is tobe automatically increased subject to the actual electrode countvalue.
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7.16 Calibration
� Calibrate force first, and current afterwards!
7.16.1 Force calibration
The "Force calibration" function is used to adjust all components of thetimer system that are involved in force generation to your referenceforce meter (e.g. pressure pickup). This feature has the following advantages:• Input of gun force in Kilonewton (kN)• Precise reproducibility of logged force values (ISO 9000)• The force values of all calibrated systems are comparable to each
other and can be transferred to additional systems.• Comparable documentation.
Force calibration changes the "Conversion factor" and "Zero adjust"parameters (in Stepper parameters; also refer to page 21). For thisreason, these parameters must not be manually changed once forcecalibration has been completed!
NOTICE
Operating the timer without or with incorrect force calibration
Possibility of damage to the gun / defective welds!
� The base pressure value to be programmed must be determinedempirically - starting with "0" - for each electrode force requiredand whenever guns have been replaced if force calibration is notcarried out!
If force calibration is not used, the timer cannot generate a properreference between the programmed force and the force actuatingvariable to be output (for controlling the gun force). Therefore, the actual force acting on the gun may differ considerably from the programmed force!
Conditions for force calibration:
• Proportionate control valve, servo gun or other suitable device capable of converting the force actuating variable output by the timerinto a mechanical force at the gun.
• external reference force meter with a suitable measuring range.• programming terminal with BOS software (for operation and meas
ured value input) is connected.
For force calibration, specify 2 different values of the force actuatingvariable in the % unit of measurement (with respect to the maximumvalue that can be output), measure the resulting forces between theelectrodes using the reference force meter and enter the forces measured in the timer (in kN). The timer will then calculate internally all of thedata required for calibration.
The following things should be especially noted for force calibration:
� The following applies for the 2 values of the force actuating variableused for force calibration:
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• if possible, the higher value should generate the force that is maximally used for welding (upper end of the force working range).
• The two values should differ by a minimum of 20 %.
• The force used for tip dressing should not be allocated to the normal working range (because it is usually lower).
• If you do not know the values you have to enter for force calibration, first perform force calibration using low values in order tocheck the forces that are adjusted at the gun, and abort calibration, if necessary. Thus, you avoid overloading or damaging thegun during force calibration. Then, you should increase the inputvalues by new force calibration processes until the higher inputvalue generates the maximum force used for welding.
� Use the same reference force meter for all plants that should be comparable.
� Perform calibration for each gun of the welding equipment andwhenever a gun has been replaced.
� Verify any calibration made by comparing the base pressure valuesprogrammed for test welding programs with the actual values on thegun. When doing so, make sure that the test programs work without current and that no persons are at risk during the measurements (e.g.as a result of robot movements).
� Repeat calibration whenever a component that is actively involved inforce generation has been replaced (weld timer, proportionate control valve, gun, ...).
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7.16.2 Current calibration
The "Current calibration" function is used to adjust the entire measuringand control loop of the timer system to your reference welding ammeter.This feature has the following advantages:• Reproducible, preconfigurable currents with a maximum error of less
than +/-2% (with respect to the actual value of the reference welding ammeter)
• Precise reproducibility of logged current values (ISO 9000)• The currents of all calibrated systems are comparable to each other
and can be transferred to additional systems• Comparable documentation.
The weld timer also works without current calibration. However, the benefits listed above cannot be achieved unless current calibration has been performed.
Conditions for current calibration:
• internal current sensor or external sensor connected to X3• external reference welding ammeter with a suitable current sensor.• programming terminal with BOS software (for operation and meas
ured value input) is connected.• force calibration properly carried out (refer to page 57).
For current calibration, enter 2 different %I values in scale values (%I),measure the currents resulting in the secondary circuit with the reference ammeter, and enter the current values measured in the timer. The timer will then calculate all of the data required for calibration.
The following things should be especially noted for current calibration:
� The current sensor of the reference welding ammeter must havebeen properly installed in the secondary circuit. That means:- always connect it in the same location - vertically to the current-carrying conductor- sensor cable points away from current-carrying conductor
� The following applies for the 2 %I values (in %I) used for current calibration:
• the higher %I value should be at the upper end of the normal workingrange of your welding plant.
� the two values should differ by a minimum of 20 %I.
� Use the same reference welding ammeter for all plants that shouldbe comparable.
� Set your reference welding ammeter to "DC" type of current and theappropriate measuring range.
� Programmed fade-out times or an active trail current are also effective with current calibration! Therefore, you should check prior to the calibration process whetherthe corresponding functions are offered by your reference weldingammeter, and whether they have been properly set.
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� Calibration should always be performed without parts to be weldedwith the electrodes closed.
� Perform calibration for each gun of the welding equipment andwhenever a gun has been replaced.
� Verify any calibration made by performing a test weld and comparingthe current displayed on the timer with the current displayed on thereference welding ammeter.
� Repeat calibration whenever a component that is actively involved inthe control loop has been replaced (weld timer, transformer,sensor ...).
7.17 Corrections
Using the timer's correction function you can change
• the %I, and
• the pressure (electrode force).
Corrections are programmed as a percentage of the correspondingbase values.
Thus, the welding schedule can be quickly adjusted to process-specificrequirements without the need to change the originally programmedbase values.
The following types of correction can be activated
• electrode-specific correction:acts on a specific electrode/gun (= Corr.(E)), and
• program-specific correction:acts on a specific program (= Corr.(P)).
The two types of correction always act in addition to one another.
If the %I correction is changed, the reference current to be monitoredis also automatically adjusted - if activated via BOS configurationtool.
The maximum correction values that can be input can be limitedglobally for the whole timer. This limitation can be set to any value inthe range of +/-20% (”Programming” BOS topic, ”General” tab, ”Min/Max %I corr.” and ”Min/Max pressure corr.” parameters).
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7.18 KSR changeover
Timers may be equipped with a sensor change-over function that drivesthe discrete outputs depending on the active electrode (e.g. KSRSELECTION x).
The following applies:
• Electrodes 1 to 9 set KSR SELECTION 1 output
• Electrodes 10 to 19: set KSR SELECTION 2 output
• Electrodes 20 to 29: set KSR SELECTION 3 output
If an external change-over box is used, the timer's sensor input can bechanged over to different KSR sensors. Please refer to the following figure.
Electrodes 0, 30 and 31 are not assigned to a sensor. Therefore the output signal 'KSR SELECTION x' output last does notchange when one of these electrodes is activated.
Please refer to the type-specific operating instructions of your timerfor the addresses to which the pertaining signals are assigned in theI/O interface.
X3
1
2
3
4
5
�
Toroid input
Secondary circuit 1
Shield connection to terminal 3 of X3only !
externalchange-over boxfor KSRchangeover
KSR SELECTION 3
�
�
�
In addition to the external KSR change-over box, a suitable connection must be provided to change over the secondary circuitto the individual transformers!
KSR SELECTION 2KSR SELECTION 1
Toroid inputShield
Secondary circuit 2
Secondary circuit 3
Fig.�29: Principle of KSR change-over; application with 3 separate welding circuits (transformers), for example
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Functions
7.19 Close weld contactor
The timer requests a higher-level monitoring instance to isolate theweld contactor.
Isolating the weld contactor is useful
• as a safety function during an electrode change
• If no new program start is given within 60 s of the end of a weldingschedule
• in the event of a fault in the welding contactor area
Signals used
• Inputs:
”Weld contactor closed” (discrete signal)“Weld contactor enable" (serial signal)
• Outputs:
"Close weld contactor" (discrete signal)
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Functions
7.20 Weld Circuit Degradation (WCD)
The WCD function serves to detect anomalies in the welding circuit.These anomalies may be caused e.g. by changes in the• mains voltage• internal resistance of the secondary circuit cable (broken cable)• electrode contact resistance (contamination).
The weld timer calculates the normalized actual ratio between weldingcurrent and phase angle at the end of a welding schedule. If the value isoutside the tolerance range around the "Maximum reference current(WCD)", the timer will generate a corresponding message and set the"WCD warning" output signal.
The function is programmed - if supported by the present timer type - inthe "Programming" topic, "Electrode" tab using the "WC degradation"and „WCD tolerance band“ parameter groups.
� Proceed as follows:
1. First perform a weld using the respective electrode under normalconditions (secondary circuit cable ok, electrodes clean and dressedcorrectly, workpiece clean).
2. Write down the actual current of MainWLD (!) and the correspondingphase angle value in %I (PHA).
3. Calculate the percentage %I using the PHA written down accordingto the following equation: %I = (PHA * 100/106) + 5.5
4. Calculate the theoretical current at 100% %I on the basis of the actual current written down and the %I calculated in the precedingstep, according to the following equation: Max. reference current (WCD) = actual current (kA) * 100% / %I
5. Enter the result in the "Max. reference current" parameter (parameter group "WC degradation").
6. Define the tolerance band using the „WCD tolerance band“ parameter group.
If tolerances are too narrow, this may lead to unintended activationof WCD monitoring in the case of mains voltage fluctuations. Therefore we recommend to set the tolerance limits to 75% initiallyand to optimize them to the respective application environment bysuitable tests.
7. Set the „WCD monitoring“ parameter ("WC degradation" parametergroup) to the value ON.
8. Send the new value to the timer.
Signals used:
• Outputs:
”WCD warning”
Upon delivery (or after deletion of the timer memory), the function isdeactivated, the "Max. reference current" parameter ("WC degradation" parameter group) is preset to 3 kA and the WCD tolerance bandparameter to 100%.
Purpose
Mode of functioning
Programming
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Functions
7.21 Reference to additional important functions
A series of important and helpful functions are available as options andare not included in timer types without these options. The present document gives a description of these additional functionsfor the sake of completeness.
7.21.1 UI regulation
The UI regulation protects your welding process against interfering variables much better than e.�g. a constant-current regulation.Higher process reliability and fewer user interventions in the system arerequired as a result.
The function is described in detail in the manual „PSI6 xxx: UI regulation and monitoring“ (for document number refer to table 1: page 5).
7.21.2 Thin-sheet function
The thin-sheet function activates a regulation algorithm which was optimized specifically for thin-sheet connections (sheet thickness lessthan 1 mm) and feeds energy to the spot weld as early as possible.
The function is described in detail in the manual „PSI 6xxx: UI regulation and monitoring“ (for document number refer to table 1: page 5).
7.21.3 Q Stop (Quality Stop)
Using the "Q Stop" function, the type PSI 6xxx weld timers can detectany problems occurring in the technologically important process stability (PSF), process quality (UIP) or force (FQF) monitoring variables andsignal them to the operator and/or the PLC.
7.21.4 Glue function
When the function is active, the controller defines the length of PreWLDrequired to drive the glue out and adapts itself automatically to thebreakthrough time of the adhesive.
The function is described in detail in the manual „PSI 6xxx: UI regulation and monitoring“ (for document number refer to table 1: page 5).
7.21.5 Static gun resistance compensation
The function is suited for compensation of static resistance deviationsbetween initial gun (gun used to record the reference curve) and thecurrently connected gun.
The interpretation of different process variables is more difficult withoutthis compensation.
The function is described in detail in the manual „PSI 6xxx: UI regulation and monitoring“ (for document number refer to table 1: page 5).
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Functions
7.21.6 Force monitoring
The "„Force monitoring“ " function allows the analysis of the force actingon the electrodes in the course of a weld.
You can thus draw conclusions about the thermal and mechanical processes taking place during the welding process and derive an assessment of the welding quality.
The function is described in detail in the manual „PSI 6xxx: UI regulation and monitoring“ (for document number refer to table 1: page 5).
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Functions
Notes:
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List of tables
8 List of tables
Table 1: Necessary and supplementary documents 5. . . . . . . . . . . . . . . . . . . . . . . . . . Table 2: Example for the structure of a safety instruction 6. . . . . . . . . . . . . . . . . . . . . Table 3: Danger classes according to ANSI Z535.6-2006 7. . . . . . . . . . . . . . . . . . . . . Table 4: Examples for classification of safety instructions 7. . . . . . . . . . . . . . . . . . . . . Table 5: Icons used 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6: Designations 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7: Abbreviations and definitions 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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List of figures
9 List of figures
Fig.�1: Main components of a welding plant 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�2: Physical basic parameters for influencing the weld 16. . . . . . . . . . . . . . . . . . . Fig.�3: Example: Time diagram of a welding program execution without impulse
operation in 2nd current block 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�4: Example: Time diagram with all programmable periods of time
(incl. impulse mode with 3 impulses) 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�5: Current blocks 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�6: Single spot welding mode; signal sequence 24. . . . . . . . . . . . . . . . . . . . . . . . . Fig.�7: Repeat welding mode; signal sequence 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�8: Seam operation principle 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�9: Programming examples for impulse mode 26. . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�10: Example: Slope in connection with impulse mode 27. . . . . . . . . . . . . . . . . . . . Fig.�11: Principle of open-loop PHA mode 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�12: Principle of KSR regulation mode with secondary current sensor 30. . . . . . Fig.�13: Principle: tolerance band 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�14: Example: principle of the conditional tolerance band with a
Reweld factor = 4 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�15: Principle of "Standard" monitoring mode 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�16: Principle of "Mixed" monitoring mode 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�17: Effect of the fade-out time 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�18: Trail current 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�19: Start times of fade-out time and trail current 37. . . . . . . . . . . . . . . . . . . . . . . . . Fig.�20: Principle of time monitoring 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�21: Example: Principle of automatic reweld by timer using
"Max. rewelds" = 4. 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�22: Enlarged contact area through electrode wear 44. . . . . . . . . . . . . . . . . . . . . . Fig.�23: Example: Determining the count value 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�24: Operating principle of stepping in the „Start“ function area 46. . . . . . . . . . . . Fig.�25: Operating principle of stepping in the „Stepper“ function area 47. . . . . . . . . Fig.�26: Operating principle in the „Dressing“ function area 48. . . . . . . . . . . . . . . . . . . Fig.�27: ”Tip dresser result monitoring” function: Effect of the tolerance bands -
Testing 1 (for prohibited range) 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�28: ”Tip dresser result monitoring” function: Effect of the tolerance bands -
Testing 2 (for permitted range) 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig.�29: Principle of KSR change-over; application with 3 separate welding circuits
(transformers), for example 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Abbreviations
10 Abbreviations
Table 7: Abbreviations and definitions
Abbreviation Meaning
%I General abbreviation for heat (%I). May be specified in %I (scale values) or kA.
%I Scale values (%I) With thyristor power units: Measure for the electrical phasevalue.For MF inverters: Measure for the pulse width.
AC Alternating Current
BOS Welding user interface
BQR User interface for U/I controller
CAN Controller Area Network; data bus
CT Cool time Time between the current impulses/blocks (1., 2., 3. CT)
Cyc Cycles. Refer to P.
Cyc. Refer to P.
daN Deka-Newton. 1 daN = 10 N
DC Direct current
dimmed The relevant object or its text is shown in grey color. In thiscondition, the relevant functionality is inhibited, or cannotbe activated for reasons of the very system.
DST Downslope time. Time in which the %I decreases until the end of the MainWLD.
ELMO Electromotive.
EMC Electromagnetic compatibility
EOS End of Schedule. Refer to WC.
ESD ElectroStatic Discharge. Abbreviation of all references to electrostatic discharge,e.g. ESD protection, ESD hazard.
ESD-sensitive components
Electrostatically Sensitive Devices
FPO Freely programmable output. Is not offered for all timers.
FQF Force Quality Factor.Value for the welding quality, derived from the characteristic of the counterforce to the electrodes during a weld.
HLD Hold time. Time after the last weld time in which the parts to be welded can cool down.
HSA (mainswitch trip)
Main switch trip.
Ignition Ignition. Firing pulses for triggering the power unit are switched onand off.
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Abbreviations
MeaningAbbreviation
IMP Number of impulses. Number of impulses, impulses forming the MainWLD.
IP Internet Protocol
kA Kilo-Ampere (amount of current)
kN Kilo-Newton (force)
KSR Constant-current regulation (CCR). Keeps the current in the welding circuit constant.
KUR Constant-voltage regulation. Compensates line voltage fluctuations.
LT Power unit (thyristor or inverter)
MF Medium Frequency
ms Milliseconds.
NBS Mains load limitation control. Monitors and influences the mains load.
NWI Post-warming pulse.
OFF Off time. Time between two spot welds in which the solenoid valveis not driven. Relevant for Repeat mode only.
Option button Round object on the user interface for toggling a functionon/off.
P Cycles (mains cycles)With a line frequency of 50 Hz: 1 P -> 20 ms.With a line frequency of 60 Hz: 1 P -> 16.6
PE Protective Earth. PE conductor.
PG Programming terminal/welding computer
PHA Phase angle.
PLC Programmable Logic Controller.
Post-Heat Post-heating time, also referred to as PstWLD.
Pre-heat Pre-heating time, also referred to as PreWLD.
PSF Process stability.Value for the consistency between the current resistancecharacteristic and the resistance characteristic of the reference curve.
PSG Transformer-rectifier unit for PSI types.Medium-frequency welding transformer 1000 Hz
PSI Programmable weld timer with inverter.
PST Programmable weld timer with thyristor power unit.
Radiobutton
Refer to "Option button".
REPEAT Repeat mode. Operating mode for manually operated systems.
RO Relay output
SINGLE Single spot operating mode. For automatic and manual systems
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Abbreviations
MeaningAbbreviation
Slope Current increase. Current increases/decreases from an initial to a final heatvalue.
Solenoid Solenoid valve. Drives the cylinders for closing the electrodes.
SQZ Squeeze time. Time that runs before the weld time. The electrodessqueeze the parts to be welded together.
Stepper %I stepping in order to compensate for electrode wear.
TCP Transmission Control Protocol.TCP controls the way in which data is exchanged betweencomputers. It is a link-oriented, packet-switching transportprotocol and belongs to the range of Internet protocols(IP).
Temp. Temperature.
Timer Weld timer. Also referred to as timer or resistance weld timer.
Tool tip Explanatory text. Appears when the mouse pointer remains on an inputfield/object for a moment.
ÜK Monitoring contact e.g. for monitoring the pressure cylinder that closes theelectrodes or monitoring of the electrode position (e.g. gunclosed”).
UIR UI regulation
UIP Process quality.Value for the welding quality, derived from the resistancecharacteristic of the current weld.
UST Up-slope time. Time in which the %I increases from the beginning of theMainWLD.
WLD Weld time. A distinction is made between PreWLD (pre-heating time),MainWLD (main weld time), and PstWLD (post-heatingtime). All 3 weld times can be programmed separately in terms ofduration and %I. Impulses and slope values can only be programmed forthe MainWLD.
WC Weld complete (contact). This signal is output when the schedule has been completed.
WCD Weld circuit degradation
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Abbreviations
Notes:
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Index
11 Index
%%I limitation, 31%I stepping, 46%I warning, 31%I warning, lower, 31
11.CT (cool time), 191st half-cycle, 42
AAbbreviations, 71AC, 71Automatic reweld by timer active, 40
BBOS, 8
CCalibration, 57Close weld contactor, 62Conditional tolerance range, 33Constant-current regulation, 30Corrections, 60CT (cool time), 19Current blocks, 20Current calibration, 59Current monitoring, 33
DDamage to products, 11Damage to property, 11DC, 71Designations, 8Downslope time (DST), 27Dresser change monitoring, 54Dressing, 49DST (downslope time), 27
EElectrode force, 21ELMO, 71EMC, 71End of Stepper, 50EOS, 71ESD, 71ESD-sensitive components, 71
FFade out time, 35Force, 21Force calibration, 57Force monitoring, 65
GGlue function, 64Gun life monitoring, 55Gun resistance compensation, 64
HHLD (Hold time), 19HSA (main switch trip), 71
IIcons, 8Impulse mode, 26
KKSR, 30, 72KSR changeover, 61KUR, 72
LLatching, 40Lower %I warning, 31
MManual electrode guns, 24Measuring loop test, 39MF, 72Minimum current verification, 40Minimum current, Verification, 40Mixed mode
Monitoring, 35Regulation, 28
Monitor stepper, 38Monitoring, 32Monitoring dresser change, 54Monitoring gun life, 55Monitoring modes, 34
NNBS, 72NWI, 42
OOFF, 72
PPG, 8, 72PHA, 28Phase angle, 28PLC, 8, 72Post-heating time, 20Post-warming pulse (NWI), 42Pre-heating time, 20Pressure profile, 56Pressure stepping, 56PSF, 72PSG, 8, 72PSI, 8, 72PST, 8, 72
QQ Stop, 64
RRepeat, 24
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Index
Reweld by timer active, 40Reweld factor, 33Robots, 24Roll seam, 25
SSchedule modes, 24Scope of delivery, 13Seal weld, 25Seam operation, 25Single spot, 24Slope, 27, 73Solenoid, 73SQZ (squeeze time), 18Standard mode
Monitoring, 34Regulation, 28
Stepper, 46, 73Stepper monitoring, 38Stitch seam, 25
TThin-sheet function, 64Time monitoring, 38Timer , 73
Tip dresser result monitoring, 52Tip dressing, 49Tip dressing monitoring, 52Tip dressing result, 52Tolerance ranges, 33Trail current, 35
UUI regulation, 64UIP, 73UIR, 31, 73ÜK, 73UST (upslope time), 27
WWarning, 50Warning table, 51WCD, 63Wear (Count) factor, 44Wear per component, 44Weld Circuit Degradation, 63Welding modes, 28WLD (weld time), 20WT, 8
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Notes:
DOK-PS6000-TECH*******-AP02-EN-P
Bosch Rexroth AG Electric Drives and Controls P.O. Box 13 57 97803 Lohr, Germany Bgm.-Dr.-Nebel-Str. 2 97816 Lohr, Germany Tel. +49 9352 18 0 Fax +49 9352 18 8400 www.boschrexroth.com/electrics