ch4capp apt

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APT


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Computer Assisted Part Programming

The alternative to manual part programming is the useof high-level programming language, which:

Defines the geometry part in terms of basicgeometry elements (points, lines )

Instructs the machine about the cutting tool


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Computer Assisted Part

Programming

So the following procedures must be used to obtain the G-code:

The programmer identifies the part geometry, cutter motions,

feeds, speeds and cutter parameters The programmer codes the part geometry, cutter motion,

feed etc and this is the source using a programminglanguage

The source is then compiled to produce the machineindependent list of cutter movements and other machinecontrol information (the cutter location control data file or CLdata file)

The CL data are processed by post-processor to generatemachine control data for the particular machine


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APT Language

The most comprehensive and widely used language is

Automatically Programmed Tool (APT) the first prototype of the

APT system was developed at MIT in 1956.

The APT statements belong to one of the five types:

Identification statements

Geometry statements

Motion statements Post-processor statements

Auxiliary statements


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Sample Point Statements

PTA = POINT/3,4,5

PTB LIN1

LIN2

PTB = POINT/ INTOF, LIN1,LIN2

PTC

PTDC1

LIN3

PTC = POINT/YLARGE, INTOF, LIN3,C1

PTC = POINT/XLARGE, INTOF, LIN3,C1

PTD = POINT/YSMALL, INTOF, LIN3,C1

PTD = POINT/XSMALLE, INTOF, LIN3,C1

x

y


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APT Language

Geometry statements, the general form of geometrystatement is:

Symbol = geometry_word/descriptive data

In the case of points:

P1 = POINT/X, Y, Z

P2 = POINT/L1, L2

P3 = POINT/CENTER, C1

P4= POINT/YLARGE, INTOF, L1, C1P5= POINT/XLARGE, INTOF, L1, C1

P6= POINT/XLARGE, INTOF, C1, C1

P7= POINT/YLARGE, INTOF, C1, C1


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APT Language

In the case of lines:

L1 = LINE/X1, Y1, Z1, X2, Y2, Z2

L2 = LINE/P1, P2

L3 = LINE/P1, PARLEL, P2L4 = LINE/P1, PERPTO, L0

L5 = LINE/P1, LEFT, TANTO, C1

L6 = LINE/P1, RIGHT, TANTO, C1

L7 = LINE/LEFT, TANTO, C1, LEFT, TANTO, C2

L8 = LINE/LEFT, TANTO, C1, RIGHT, TANTO, C2L9 = LINE/RIGHT, TANTO, C1, LEFT, TANTO, C2

L10 = LINE/RIGHT, TANTO, C1, RIGHT, TANTO, C2

L11 = LINE/P1, ATANGL, L0


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APT Language

In the case of circles:

C1 = CIRCLE/X, Y, Z, R

C2 = CIRCLE/CENTER, P1, RADIOUS, R

C3 = CIRCLE/CENTER, P1, TANTO, L0C4 = CIRCLE/P1, P2, P3

C5 = CIRCLE/XSMALL, L1, XSMALL, L2, RADIOUS, R

And the same with XLARGE, YLARGE or YSMALL

In the case of planes:PL1 = PLANE/P1, P2, P3

PL2 = PLANE/PARLEL, PL0, XLARGE, D

And the same with XLARGE, YLARGE, YSMALL, ZLARGE or ZSMALL


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APT Language

Motion statements, with regard to point-to-point

operation there are three motion statements for

positioning the tool at a desired point:

FROM/point_location

GOTO/point_location

GODLTA/x, y, z


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APT Language

Example 1:


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APT Language

Answer:

P0 = POINT/0.0, 3.0, 0.1P1 = POINT/1.0, 1.0, 0.1P2 = POINT/2.0, 1.0, 0.1

FROM/P0GOTO/P1GODLTA/0, 0, -0.7GODLTA/0, 0, 0.7

GOTO/P2GODLTA/0, 0, -0.7GODLTA/0, 0, 0.7GOTO/P0


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APT Language

Other Motion statements: GO/{TO}, Drive surface, {TO} Part surface, {TO},

Check surfaceOr

GO/{TO}, Drive surface, {TO} Part surface, {TANTO},Check surfaceAnd the same with PAST or ON instead of TO

GOLFT/ GORGT/ GOUP/

GODOWN/ GOFWD/ GOBACK/

For example:GO/TO, L1, TO, PS, TANTO, C1GO/PAST, L1, TO, PS, TANTO, C1


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APT Language

Example 2:


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APT Language

Answer:

FROM/SP

GO/TO, L1, TO, PS, ON, L4

GORGT/L1, PAST, L2GOLFT/L2, PAST, L3

GOLFT/L3, PAST, C1

GOLFT/C1, PAST, L3

GOLFT/L3, PAST, L4GOLFT/L4, PAST, L1

GOTO/SP


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APT Language

Example 3:


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APT Language

Answer:

FROM/SP


GORGT/L1, PAST, L2

GORGT/L2, TANTO, C1

GOFWD/C1, TANTO, L3

GOFWD/L3, PAST, L4

GOLFT/L4, PAST, L5

GOLFT/L5, PAST, L6

GOLFT/L6, PAST, L1

GOTO/SP


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APT Language

Additional statements: MACHIN/DRILL, 2

COOLNT/

For example:COOLNT/MIST COOLNT/FLOOD COOLNT/OF FEDRAT/

SPINDL/

For example:SPINDL/ON SPINDL/1250, CCLW TOOLNO/ TURRET/

END


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APT Language

Other capabilities of APT, the macro facility, with use variable argument as in aFORTRAN subroutine, for example:P0 = POINT/0.0, 0.3, 0.1FROM/P0CALL/DRILL, X=1.0, Y=1.0, Z=0.1, DEPTH=0.7

CALL/DRILL, X=2.0, Y=1.0, Z=0.1, DEPTH=0.7GOTO/P0

when the definition of the macro DRILL is:DRILL = MACRO/X, Y, Z, DEPTH

GOTO/X,Y,ZGODLTA/0,0, -DEPTHGODLTA/0,0, DEPTHTARMAC


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APT Language

Example 4 (1/2):


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APT Language

Example 4 (2/2):


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APT Language

Answer (1/4):

PARTNO PART11

MACHIN/MILL, 3 ;machine selection

CLPRINT ;prints out CL data file

OUTTOL/0.002SP =POINT/5,0,1P1 =POINT/1,2,0.5P2 =POINT/4,2,0.5P3 =POINT/6,4,0.5

P4 =POINT/8,5,0.5P5 =POINT/9,7,0.5P6 =POINT/2,7,0.5PL1 = PLANE/P1, P2, P3PS = PLANE/PARALEL, PL1, ZSMALL, 0.5

;define part surface to be z = 0


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APT Language

Answer (2/4):

C1 = CIRCLE/CENTER, P4, RADIOUS, 1.0L1 = LINE/P2, P3L2 = LINE/P3, RIGHT, TANTO, C1L3 = LINE/P5, LEFT, TANTO, C1L4 = LINE/P5, P6L5 = LINE/P6, P1L4 = LINE/P1, P2

MILL = MACRO/CUT, SPIN, FEED, CLNTCUTTER/CUT

FEDRAT/FEEDSPINDL/SPINCOOLNT/CLNTFROM/SP


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APT Language

Answer (3/4):

FROM/SP


GORGT/L1, TO, L2

GORGT/L2, TANTO, C1GOFWD/C1, TANTO, L3

GOFWD/L3, PAST, L4

GOLFT/L4, PAST, L5

GOLFT/L5, PAST, L6GOLFT/L6, PAST, L1

GOTO/SP

TERMMAC

TURRET/4


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APT Language

Answer (4/4):

TURRET/4

CALL/MILL, CUT=0.52, SPIN=600, FEED=3.0, CLNT=ON

TURRET/6CALL/MILL, CUT=0.5, SPIN=900, FEED=2.0, CLNT=ON

SPINDL/0

COOLNT/OFF

ENDFINI


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Other Part Programming

Languages

ADAPT (ADaptation APT) was the first attempt to adapt APTprogramming system for smaller computers

AUTOSPOT (AUTOmatic Sytem for POsitioning Tools) wasdeveloped by IBM and first introduced in 1962

EXAPT (EXtended subset of APT) was developed jointly in

German in about 1964 by several universities to adapt APT forEuropean use. It is compatible with APT and thus can use thesame processor as APT

COMPACT was developed by Manufacturing Data Systems,Inc. (MDSI)

SPLIT (Sundstrand Processing Language Internally

Translated) was developed by Sundstrand Corporation,intended for its own machine tools

MAPT (Micro-APT) is a subset of APT, to be run on themicrocomputers


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NC program preparation may be tedious and

difficult if the part to be machined has acomplex geometry. The main difficulty is tofind out the cutter locations during themachining. Computers may be used to assist

the programmers in preparing the NC codes.

Computer Aided Part Programming:


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It reduces the manual calculations involves indetermining the geometric characteristics ofthe part.

It provides the cutter path simulation.

It provides tool collision checking.

It shortens the program preparation time. It makes the program preparation easier.

Advantages of applying computer-aided

part programming include the following:


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The output of any CAD package include the geometricdata of the part to be machined. Therefore, manyCAD/CAM package can produce cutter location (CL)

data to be used for NC code generation. There is still to be a process planning module for a

workable NC code generation.

Some of the CAD/CAM packages that have the NCcode generation capabilities are Computervision,CATIA, CADAM, ProEngineer, MechanicalDesktop(Auto Desk).

CAD/CAM Based Part Programming:

ch4capp apt

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