Star orbiting

Process control by PLC

The resulting geometry of the “star orbiting” machining strategy is shown in the figure in the section Superimposing geometry and escape motions. This operation mode is designed to finish-machine cavities in corners. It requires the orbit channel to remain in position in each corner while the down channel expands. After expanding, the down channel must wait at the centre until the orbit channel has positioned itself in the next corner before the down channel can expand again. Synchronising the two channels can be achieved using the #SIGNAL and #WAIT commands, as shown in the following program excerpts.

One way of organising velocity planning is for the spark generator to specify an external velocity for the escape channel as usual. The velocity of the down channel is also specified by the spark generator, but if a negative velocity is specified by the spark generator, it is overwritten in the PLC by zero velocity. Consequently, escape motions are only executed by the escape channel.

Programing Example

Down channel - star orbiting

%star

N0290 G01 Z30 F1500 ; down

N0300 G19

N0310 $WHILE V.P.SliceCounter < 4 ; 3 corners

N0320 #SIGNAL SYN [ID 1000 CH2] ; signal to move to next corner

N0330 #WAIT SYN [ID 2000 CH2] ; wait until the orbit channel reaches the next corner

N0340 G03 Y30 Z60 J0 K30 ; expand

N0350 G01 Z70

N0360 G01 Z60

N0370 G02 Y0 Z30 J-30 K0 ; move back to centre

N0380 V.P.SliceCounter=V.P.SliceCounter+1

N0390 $ENDWHILE

Programing Example

Orbit channel - star orbiting

%L channel_sync

N2000 #SIGNAL SYN[ID 2000 CH1]

N2010 #WAIT SYN[ID 1000 CH1]

N2020 M17

N2170 #CHANNEL SET [FAST_FORWARD_IN_CENTER=ON]

(----- Orbit geometry -----)

N2180 G01 XP1 Y-P2 ; first corner

N2190 LL channel_sync; wait for signal to move to next corner

N2200 X0

N2210 X-P1

N2220 LL channel_sync

…

N2380 #CHANNEL SET [FAST_FORWARD_IN_CENTER=OFF]

N2390 LL channel_sync

(----- End of orbit geometry -----)

N2400 #TRACK CHAN OFF [EXTEND]

N2410 #CS DEL ALL

N2420 M30