wojciech płowucha, władysław jakubiec university of ... ath-turyn 2018/research on the...
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Laboratory of Metrology [email protected] Metrologii
Wojciech Płowucha, Władysław JakubiecUniversity of Bielsko-Biała, Laboratory of Metrology
Laboratory of Metrology [email protected] Metrologii
Laboratory of Metrology [email protected] Metrologii
Laboratory of Metrology [email protected] Metrologii
Calibration of CMMs, ACMM, microscopes, measuring projectors, special geometrical gauges.
Laboratory of Metrology [email protected] Metrologii
Coordinate measuring technique (CMT) – quickly developing and widely present in the industry (not only machine) measurement technology.
Geometrical product specification (GPS) – intensive standardization works are underway (ISO TC 213) aimed at organizing, clarifying and filling gaps in a large series (almost 100) of standards.
Measurement uncertainty – the problem is generally known, but it is not easy (especially in the case of coordinate measuring technique), and recently the quality management systems used in industry require that the uncertainty is "known and appropriate".
Laboratory of Metrology [email protected]
Coordinate measuring technique
Tactile (touch-trigger, scanning) with rotary table (fourth axis) Optical and multisensor
Laboratory of Metrology [email protected]
Coordinate measuring technique
ACMM – articulated measuring arms
Laboratory of Metrology [email protected]
Coordinate measuring technique in comparison with conventional measurements (examples)
Measurement of size (diameter)
Conventional measurement: - caliper, micrometer – two-point measurement,- bore-gage – three-point measurement,- gauges – realization of Taylor pronciple (E),- circumference measurement devices.
Coordinate measurement:- Tactile measurements: significant numer of probing points; result is associated circle (in particular section) or cylinder; different association criteria may be applied, calculation of two-point diameter possible if required,- Optical measurement: as above.
Laboratory of Metrology [email protected]
Coordinate measuring technique in comparisonwith conventional measurements (examples)
Gears’ measurements
Conventional measurement: - Special measuring devices a required to measurediffenet characteristics
Coordinate measuring technique:- CMM-evaluation-software option required; somecharacteristics may be evaluated „virtualy”
Laboratory of Metrology [email protected]
Coordinate measuring technique in comparison with conventional measurements - summary
Advantages of Coordinate measuring technique- necessity for large number of different measuring
devices (special devices in particular) iseliminated.
- the time of starting a new production is reduced(the time needed to "write" the measurement program is definitely shorter than the time needed to design and manufacture a special device)
- with CMT it’s easier to implement design changesduring production (short time for updatingmeasuring programmes)
LM ATH LM had the opportunity to participate in the implementation of a new product for production at Avio Bielsko-Biała(a set of blades) where for the first time thespecial measuring instruments werereplaced with direct CMM measurement.
Laboratory of Metrology [email protected]
Coordinate measuring technique in comparison with conventional measurements - summary
Special requirements
- Measurement of roughness on CMM –development is ongoing, some solutionsare available (even for machine tools),
- Measurement of small radii and edges –these are important characteristics in some applications (fatigue strength)
In short time no complex solution can be expected.
Laboratory of Metrology [email protected]
CMM softwarePost-inspectionStatistical analysisGraphical presentationAnalysis of measurement uncertainty
Computer Aided Accuracy CAAGeometrical error correctionThermal effects correction
ProgrammingOffline programming and simulationParametric programmingFeature oriented programming
Core softwareProbing system qualificationCoordinate system definition and manipulationAssociation of geometrical featuresRelations between geometrical features (distance, angle, intersections,…)Geometrical deviations evaluationTolerances analysis (OK, NOK)
Specialized optionsGearsThreadsCamshaftsFreeform surfacesReverse engineering
AccesoriesMultisensorProbe changerRotary tableAutomatic workpiece handlingMulticolumn CMMs
ISO 10360-6???
Laboratory of Metrology [email protected]
What we measure?
Geometrical characteristics
• Sizes• Dimensions other than sizes
Geometrical tolerances
According to the modern approach of GPS, the toleranced dimensions should only be used for features of size.
Laboratory of Metrology [email protected]
Structure of the ISO GPS system
3 type of standards are distinguished: fundamental, general and complementary.Standards follow a 9 x 7 matrix system. Rows (9) are geometrical properties. Columns (7) are chain links.
Chain links:A: Symbols and indications, B: Feature requirements, C: Feature properties, D: Conformance and non-conformance, E: Measurement, F: Measurement equipment, G: Calibration
Geometrical properties:- size, - distance, - form, - orientation, - location, - run-out, - profile surface texture, - areal surface texture,- surface imperfections
The GPS standards standards relate to geometric properties as a whole (not only designation symbols to express the requirements but also all aspects concerned with verification). It’s often misinterpreted that GPS is synonymous with GD&T. The chain links B and C clearly refer to the coordinate technique.
Laboratory of Metrology [email protected]
Main GPS standards
ISO 286 (1988, 2010) Geometrical product specifications (GPS).ISO code system for tolerances on linear sizes. Part 1: Basis of tolerances, deviations and fits
ISO 14405-1 (2016) Geometrical product specifications (GPS).Dimensional tolerancing. Part 1: Linear sizes
ISO 14405-2 (2011) Geometrical product specifications (GPS). Dimensional tolerancing. Part 2: Dimensions other than linear sizes
ISO 1101 (2006, 2012, 2017) Geometrical product specifications (GPS). Geometrical tolerancing. Tolerances of form, orientation, location and run-out
ISO 5459 (2011) Geometrical product specifications (GPS).Geometrical tolerancing. Datums and datum systems
Laboratory of Metrology [email protected]
Features of sizeThe features of size are shafts and holes as defined in ISO 286, namely cylindrical elements or pairs of parallel planes.
Laboratory of Metrology [email protected]
Sizes
Basic interpretation of size is local two-point size. Such interpretation does not require special designation.
Other interpretation of size, very often applied, is global size understood as size of feature calculated with one of following association criteria: Gaussian (GG) (Fig. a), maximum inscribed (GX) (Fig. b), minimum circumscribed (GN) (Fig. b) or minimax (GC).
Laboratory of Metrology [email protected]
Sizes
In case of envelope requirement (modifier (E)) the verification of the product geometry practically consists on simultaneous check for fulfilling the two requirements mentioned previously.
Laboratory of Metrology [email protected]
Example
0
5
10
15
20
25
30
35
Freq
uenc
y
D(LP)
D = 363,22 +/-0,04
D(LP) = (363,2382 - 363,2625) (297 values)
D(GG) = 363,2503
D(E) = 363,2751
Laboratory of Metrology [email protected]
Example: specification of requirements for bearings
aaa
GN – minimum circumscribed sizeLP – two-point size
ALS – any longitudinal section
Intersection plane indicator (symmetry) (applies to the crossection symmetrical with datum K which is the hole axis)
A ↔ B – „between A and B”; defines lengthof the toleranced element (applies to the perpendicularity of the outer ring axis)
SR – range of sizesSD – standard deviation of sizesACS – any cross section
Laboratory of Metrology [email protected]
Geometrical tolerances (ISO 1101)
Classification:• Form• Orientation• Location• Run-out
Tolerances of orientation limit form deviations. Tolerances of location limit form and orientation deviations.
Laboratory of Metrology [email protected]
Datums as tangential elements
Evaluation method for the measurement
Evaluation method for datum assignment
Laboratory of Metrology [email protected]
Perfect verification operator for perpendicularity
No direct solution in CMM software:Form deviation of the toleranced feature is not taken into account
Laboratory of Metrology [email protected] Metrologii
Laboratory of Metrology [email protected] Metrologii
Laboratory of Metrology [email protected] Metrologii
Laboratory of Metrology [email protected] Metrologii
n11 – EUCoMStandards for the evaluation of the uncertainty of coordinate measurements in industry
Laboratory of Metrology [email protected] Metrologii
n11 – EUCoMStandards for the evaluation of the uncertainty of coordinate measurements in industry
Objectives: 1. To develop traceable and standardised methods for evaluating coordinate measurements a posteriori. This should include the improvement of existing methods in EN ISO 15530-3 and prEN ISO 15530-4. 2. To develop a simplified and validated method for predicting the uncertainty of coordinating measurements a priori using type B evaluation (i.e. expert judgement). 3. To demonstrate the validity of existing methods and those from objective 1 & 2 in industrial conditions and evaluate their consistency and accuracy against the Guide to the Expression of Uncertainty in Measurement (GUM) and its supplements. 4. To contribute to revisions of EN ISO 15530 and EN ISO 14253-2 by providing the necessary data, methods, guidelines and recommendations, in a form that can be incorporated into the standards at the earliest opportunity. In addition, to collaborate with the technical committees CEN TC 290 and ISO TC 213 WG10 and the users of the standards they develop to ensure that the outputs of the project are aligned with their needs and recommendations for incorporation of this information into future standards at the earliest opportunity.