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IE 4230 - Systems IntegrationIE 4230 - Systems Integration

CNC Machining

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CNC Machine

Continuous path motion control

Closed loop (PID) control

Components Drive motors Position feedback Computer controller

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Drive Motors DC servo motors

AC servo motors

Stepper motors Hydraulic motors

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Position Feedback Incremental encoder

Quadrature

Absolute encoder Resolver

Tachometer

No feedback (openloop)

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Mechanical Components Ball screw

Ball nut (anti-backlash)

Ways Linear bearings

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Control

Desired path (p, v, a) 3-axis position control (encoder feedback)

Velocity control (tachometer feedback) Torque control (current feedback)

Path generator

Linear interpolation Circular interpolation Complex path interpolation (contouring)

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CNC Programming Manual

Write code directly

Computer-assisted Draw cutter path

CAD/CAM Draw the part Cutter path is generated

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CNC Integration Two Versions of DNC

Distributed Numerical Control Program is stored in a computer Program is loaded to CNC machine and

executed automatically

Direct Numerical Control CNC commands are individually transmittedfrom a computer to the CNC machine andexecuted immediately

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Galil DMC Programming

All units are counts

Independent axis movements

Coordinated (vector mode) movements

Typical sequence Specify parameters Specify motion Begin motionAfter motion

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Vector Mode Moves

Parameters VM vector mode

plane VS vector speed VA vector

acceleration VD vector

deceleration

Motion VP linear position

(from local origin)

CR circular arc (rad, start, sweep)

VE end sequence

Sequence control BGS begin sequence AMS after motion

sequence

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Galil Program Segment

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Other Galil Statements Labels

Begin with #

8 characters total #DRILL

Variables Begin with letter 8 characters total SAFEZ=8000

Remarks Line begins with REM

Ignored during load Program structure

Begin with label #MY_PROG End with EN

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Galil Subroutines Jump to subroutine (by label) from

main program: JS #MYSUB

Place subroutine after main program When subroutine end (EN) is

encountered, returns to main program

just after JS statement One subroutine can be called many

times