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View Full Version : Any one do any 'Balanced' turning?



Castle1
08-19-2008, 08:16 PM
I've been told many times in the past that balanced turning works well with dual turret Okuma lathes, but I have never seen it done. Any one with tips pointers, comments on this?
Thinking about trying it out, we have a LU-15 Okuma with 5020L control.
thanks ,
Steve

throttle_jockey
08-25-2008, 09:52 PM
If you've got IGF it's easier to sync the turrets, but then you have to know IGF. The positioning of the turrets before the canned roughing cycle, i.e. Z axis start point, along with assigning a turret as dominant for the G96 (constant surface speed), are critical to the program. As far as the operation end if you've got graphics, and if you've got IGF you've got graphics, run it through the graphics in machine lock but not in dry run, this will show you exactly what it's going to do while cutting. IF the trailing turret catches up to the leading turret you've assigned the G96 to the wrong turret.
The timing of the turrets uses P Codes, i.e. P0010 for A turret, and P0010 for B turret to sync them simultaneous. You'll need to have a good grasp of this for your program as well.

This is a scratch of the surface, if you want to get more in depth let me know.

Cheers

AppsMan
09-25-2008, 01:44 PM
Balance cutting work best for rough out a part. Especially if you have multiple passes to cut. I do not recommend finishing turning with it if possible. If setup is rigid enough you can finish turn different sections of the part at the same time. Just be careful you are not causing deflection in the part. Their several different methods to balance cut which include turning staggered at 2 different depths or same depth and the cutters inline with each other. I prefer the 2nd method but I believe the first method may be more common. Balance turning is easy the program you just have to determine where and when to use it. Anytime one turret is sitting idle your company is losing money so balance cutting makes perfect sense. You may already have this but I attached a example from the Okuma 5020L programming manual.

perkulator
10-19-2008, 11:44 AM
we use it all the time at work in roughing cycles.If you got vibrations due to long workpieces it´s the best way to get rid of them.730mm long and with a smallest diameter of 33mm workpieces works just fine with balanced turning and is impossible to turn with other than balanced turning.Whith balanced turning i mean that A and B turret are fully syncronised and are at the same position at any given time both in X and Z.
this means you can double the feed since the turrets only cuts half the rotation if you know what i mean.But be careful it eats kw from the spindle motor so begin with small cutting dephts and work your way up.
Another issue is that the compensations of the tools is rather critical if for example the tool compensation in the A-turret is wrong by 0.1mm in Z-axis and you have a feed of 0.8mm/r one of the turrets will have a feed of 0.5 and the other 0.3mm/r.Because of that i always set the feed a bit lower than the double feed (0.7mm/r instead of 0.8mm/r) for example
Therefor is it equally critical that the machine zeropoint (or whats it called) for both turrets is accurate.
Programming isn´t that tricky you just do the toolselection and determine the cuttingspeed in the main program and then call the same subprogram from both turrets (CALL Oxxx P100)
The turrets must be in the same position in both X and Z before calling the subprogram
In the subprogram every block between G81 and G80 must have P-codes to ensure that the turrets move syncroniusly
Oxxx
G87 NROUG U=5 D=1.0 W=0.1 F=0.8
NROUG G81
G1 G42 X? Z? P1
G1 ETC P2
G1 ETC P3
G80
RTS
Hope this helps and that you understand my english

perkulator
10-21-2008, 12:32 PM
sorry of course it should be G85 and not G87 in the subprogram