5
Programming Tool Movements
5.5 Path Contours - Polar Coordinates
Example for exercise: Tapping
L
TNC 370
Given Data
Thread:
Right-hand internal thread M64 x 1.5
Pitch P: 1.5 mm
Start angle A,: 0”
End angle A,: 360” = 0” at Z, = 0
Thread revolutions n+ 8
Thread overrun
l
at start of thread ns: 0.5
l
at end of thread r-y 0.5
Number of cuts: 1
‘A,
1%
=O”
A=
,
;
,
,
-180”+ + -I ?A=O”
‘\
Calculating the input values
l
Total height H: H = P.n
P=1.5mm
n = nT + ns + nE = 8 + 0.5 + 0.5 = 9
H = 1.5 mm.9 = 13.5 mm
l
Incremental polar coordinate angle IPA:
IPA = n 360”
n = 9 (see total height H)
IPA = 36OO.9 = 3240”
l
Start angle A, with thread overrun ns
ns = 0.5
n = 1 = 360”. n = 0.5 = 180” (half a revolution)
The starting angle of the helix is advanced by 180”. With positive
rotation this means that A, with ns = A, - 180” = -180”
l
Starting coordinate: Z = P,(n, + ns) = -1.5.8.5 mm = -12.75
Note:
l
The thread is being cut in an upward direction towards Z, = 0; there-
fore Z, is negative.
Part program
0 BEGIN PGM 360535 MM
1 BLK FORM 0.1 Z X+0 Y+O Z-20
2 BLK FORM 0.2 X+100 Y+lOO Z+O
3 TOOL DEF 1 L+O R+5
4 TOOL CALL 1 Z S 1500
5 L Z+lOO RO FMAX M6
6 L X+50 Y+50 FMAX
7 cc
8 L Z-12.75 RO FMAX M3
9 LP PR+32 PA-180 RL FIOO
10 CP IPA +3240 lZ+13.5 DR+ RL F200
11 L X+50 Y+50 RO
12 L Z+lOO FMAX M2
13 END PGM 360535 MM
Part program for cutting a thread with more than 15 revolutions (also see Chapter 6)
.
8’
L Z-12.75 RO F MAX M3
9 LP PR+32 PA-180 RL FIOO
10 LBL 1 _......._..____..._............................................... Identify beginning of program section repeat
11
CP IPA +360 12+1.5 DR+ F200 .._..____._..___...... Enter thread pitch directly as an IZ dimension
12 CALL LBL 1 REP 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Program the number of repeats (thread revolutions)
13
L X+50 Y+50 RO F500
.
.
5-3
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