computer numerical controler

8/14/2019 Computer numerical controler

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ext oo

from ro rammin to NetworkinS. C. J. Lin, Delmar

1994


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actions are controlled by the direct insertion of

numerical data at some oint. The s stem must

automatically interpret at least some portion of this

data. The coded instructions are converted into two

types of control signals.

pluses of electric output: positioning of the machine

s indle relative to the work iece and its s eed. on/off control signals: spindle rotation control, coolant

su l selection of cuttin tool sto clam in and

unclamping.


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1947 - John Parsons (Michigan UAS): Three-axis

curvature data to control machine tool motion for thecomp ex mac n ng o a rcra componen s.

1949 - Parsons joined MIT.

1951 - First numerically controlled machine tool was

developed in MIT.


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Programming Languages

Development

Automatically Programmed Tool (APT) was

developed in MIT to define part geometry and

cutter aths for work ieces. The ma orit of toda s

computer-aided design/computer-aided

manufacturing (CAD/CAM) NC systems are APT-

based. Other ATP-based lan ua es are

ADAPT(IBM), IFAPT(France), FAPT(Japan).


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Computer Numerical Control (CNC)

and Distributive Numerical Control

A dedicated computer

is built into the MCUto control one

machine tool.

1980 - a network of

computers is used to

coordinate theoperation of a number

of CNC machines.


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Basic Element of

a CNC System

Machine Control Unit

It reads and interprets the

machining a particularwork iece and eneratin

electric output signals. It

also acts as a feedbackcontrollerfor precise

positioning of machine table

or spindle. MCU consists oftwo main units.


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MCU consists of two main units.

Data-processing unit (DPU)

reads coded instructions

processes coded instructions

axis to the CLU.

executes linear or circular interpolations based

and generates control signals

implement auxiliary control function


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Computer Numerical Control

(CNC)CNC is a self-contained NC system for a single

machine tool that uses a dedicated computer con ro e y s ore ns ruc ons n e memory o

implement some or all of the basic NC functions. It is

- .

Monitoring display and graphic representation of the

Data entry: manual data input (MDI) and RS-232-C

ontro er memory: e execut on program res es n

Read only memory (ROM). The part programs are

- .


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Program editing: After part programs are downloaded

to the CNC memory, changes or updates can bema e a e mac ne.

Program verification: Simulation programs allow the

cu er pa o e sp aye an ver e grap ca y ona display unit before the part program is run on the

.

Error diagnostics: program error, operation error and

.

Communication facility. CNC control units have the

microprocessor-based devices.


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Management information: on-line parameter and

information display Coordinate system (absolute vs. Incremental)

Unit system ( inch vs. Metric)

Code format (EIA vs. ASCII) Macro and com utin ca abilit

Cutter compensation for size and length

Advanced programming features


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Increased productivity

High accuracy and repeatability Reduced production costs

Reduced indirect o eration costs

Facilitation of complex machining operations

Improved production planning and control

Facilitation of flexible automation


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Accuracy: agreement between the actual

value of the measured variable and themeasurement as it is output by the sensor.

epeaa y recson : vara on over

repeated measurement.

variable to which the sensor will respond

with a like change in the measurement

Range: the upper and lower limits of the

measured variable for which

measurement can be made.


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Machine control unitTooling system

Three-axis vertical machinin

centre


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Cooling system


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Calibrated by laser equipment


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ra g ness easuremen


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--CNC,,

T e sp n e suspen e y "Act ve Magnet

Bearings". It also uses HSK50 tooling system and

increases the rigidity of the tool clamping. Thisa ows or ex reme g spee cu ng w ra es

up to 40 m/min. The machine employs noiseless

slide covers, oilless guide ways and precision ball

.

Travel___________ __800x500x550mmTable working surface_____900x465mm

______

Spindle speed______Max.10,000-

160,000rpm

____OPT(60x60x30m/min)

computer numerical controler

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