How to vary SFM on a straight bore

[use2machine]

We have a 15" deep 3" dia. bore that the operator wants to know if I can create a program for that will adjust the sfm from 140 to 155 and back down every .015 along the length of the bore. It is on a mazak lathe with a t32 control but I was going to make an eia program. I have Gibbs and Solutionware for toolpath software and I have Cimcoe edit and MetaCut utilities for editing. Thanks for any help!

[Bluesman]

Why???






Bluesman

[use2machine]

They vary the speed to stop chatter.

[Bluesman]

oh OK



Bluesman

[Andre' B]

Somthing like this is all I can think of and how smooth it runs will depend on how fast you control can do the calculations. Could maybe use a faster function then a sin wave.

Edit: Note that the step size needs to be less then the period or you will not get what you are expecting.
If you want to know why do some googleing on "Harry Nyquist" AND sampling

This is not a complete program but just a starting point.
And the X move inside the loop is just to plot the speed change so you can see what it is doing here. It would not be used in a real program.

(CHANGE THESE AS NEEDED)
#100=-15.000(Z FINISH)
#101=0.100(Z START)
#102=147.5(SPEED)
#103=7.5(SPEED RIPPLE)
#104=0.030(RIPPLE PERIOD)
#105=0.002(STEP SIZE)

G0X3.0Z#101
#110=#101-#100(CURRENT POSITON)
WHILE[#110GT0.0]DO1
#109=#102+#103*SIN[[#110/#104]*360.0]
(NOTE THE X WORD IN THE FOLLOWING IS)
(ONLY TO PRODUCE A VISUAL OF THE    )
(SPEED CHANGE IN THE TOOL PATH PLOT )
G1Z[#100+#110]S#109 X[[#109/36]-3]
#110=[#110-#105]
END1
G1Z[#100]

G0X0
G0Z0.2

[beege]

Can you program two offsets for the bore, one for the start of the bore, one for the end? Then have two different diameters programmed, but use the offsets to "straighten" the bore. I think you could on a Fanuc, don't know about Mazak