Spindle acceleration/deceleration

Good morning,


We have another new to us 2012 OKUMA LT2000EX Serial #163297 machine.


The main spindle is not the "standard" or the same size as the other 2 machines that we have. It is 68mm through the draw tube, the other ones are 2".


The max speed on the main is 5,000 rpm, 6,000 on the sub.





The problem is that it takes a very long time to accelerate up to speed. It's so bad that I have taken CSS out of some tools because it is "waiting" for the spindle to get to speed between roughing passes. During the cutoff process when the spindles are synced it takes forever to start and stop. That's only with a 2" dia bar!





I wrote a simple program to just sync the spindles and accelerate up to a speed and back to stop. (below)


When the spindles are synced together at 2,500 rpm it takes 22 seconds to get up to speed and back to zero. @ 4,500 rpm it takes 56 seconds! The other machines @ 4,500 rpm it takes 26 seconds!




Now this problem isn't just during the transfer when they are synced together. But it is only on the main spindle. The sub spindle is the standard 2" dia. and accelerated and decelerates just like our other machines.

The only suggestion tech support has suggested is the Work weight setting must be set to heavy. But the work weight parameter is set to no chuck on all the machines except for one. Which is our LB3000IIEX with 3" spindles. It's set to 10" (main) 6" (sub). But even this machine is within 1-2 seconds of the other machines running the test program.

This is adding a considerable amount of cycle time!




Any ideas what is going on here???


G13
G140 (MAIN SPINDLE)
G144 G136 M109 M76
(SPINDLE SYNC TIME TEST)
G50 S5000
P200

P201 G97 S1500 M3

M185 M247 (CHK ROT I'LOCK OFF, OPP SPDL ROTATION I'LOCK OFF)

M249 (OPEN SUB)
M151

G04 F.5
M248 (CLOSE SUB)
M84
G4 F.5 (SUB PULL)
M83
G97 S4500 M3
G97 S4500 M5
M150
P990

G14
G141 (SUB SPINDLE)
G144 G136 M109
G50 S5000
P200

P201 G97 S1500 M4

G140
P990
M2
%

hy :) what options do you have at " workweight (main spindle ) " ? i understood that now it is at " no chuck ", but what else is there ? okuma dealer is the one that can enable them; is ok if okuma dealer recomanded setting change, but is not ok if options are not enabled; they should enable that even if machine was delivered without a chuck

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Now this problem isn't just during the transfer when they are synced together. But it is only on the main spindle

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to be sure that you check only main spindle, use M150+G140; if it works in M150, then begin to investigate also 151

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Which is our LB3000IIEX with 3" spindles.

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you mean 3" spindle bore ?

i have acceleration times for 3000series, normal and big bore; i will share them and test program as reference

besides workweight, there is at least other spindle acc parameter; i will look for it a bit later / kindly :)

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Originally Posted by deadlykitten

hy :) what options do you have at " workweight (main spindle ) " ? i understood that now it is at " no chuck ", but what else is there ? okuma dealer is the one that can enable them; is ok if okuma dealer recomanded setting change, but is not ok if options are not enabled; they should enable that even if machine was delivered without a chuck

There are just settings for 3 different settings for the main and sub.
Main is No chuck, 8" or 10"
Sub is No chuck 6" or 8"


to be sure that you check only main spindle, use M150+G140; if it works in M150, then begin to investigate also 151
I was running the program in (M150) mode and there was very similar rough turning operations on the main and sub spindles.
With CSS turned on both spindles. The main spindle was just finishing roughing the part, while on the sub it roughed turned, finish turned, drilled 2" deep, C'bore .30 deep and then tapped a M16-1.5 hole 1.5 deep before the main was done! That is nutz!

Isolated just one spindle at a time 0-5,000-0
Main 14 seconds
sub 6 seconds

you mean 3" spindle bore ? Yes that's correct

i have acceleration times for 3000series, normal and big bore; i will share them and test program as reference

besides workweight, there is at least other spindle acc parameter; i will look for it a bit later / kindly :) They asked me to check for several other pages but they were not there.

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hmmm

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There are just settings for 3 different settings for the main and sub.Main is No chuck, 8" or 10"
Sub is No chuck 6" or 8"

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hy :) there may be more or less options; normally, 1st is the standard chuck for that spindle, and futher options are for bigger chucks

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he only suggestion tech support has suggested is the Work weight setting must be set to heavy

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heavy setting is enabled :
... on standard spindles with heavier than standard chuck
... on big bore spindles

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The max speed on the main is 5,000 rpm, 6,000 on the sub

I was running the program in (M150) mode and there was very similar rough turning operations on the main and sub spindles.With CSS turned on both spindles.

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you should take out from equation the 2nd spindle, because it seems to be smaller & faster, and this is normal

you should compare the 1st spindle to a similar spindle from other machine; if i get it right, you have problems with the big bore, and you also have 2 more lathes with normal 1st spindle; i don't have times for 2000series, but for 3000, the difference between normal and big bore is <0.4seconds @ 2500rpm; i don't know if this applies proportionally to the 2000 ?!

also, when you compare spindles for 2000 series, there are 3 variants for main spindle ( standard, high power, big bore ) and 1 variant for the sub spindle

what i try to say, is that you need a real reference, and stop comparing to the subspindle and/or sync more, or whatvere else; i would look into spindle diagram, and search for a similar machine, with same chuck ... but as you describe it, it seems to be slowed down for whatever reason

little list :
... work weight : if heavy is missing, then try the latest option : for example, if now is [ no chuck ], then simply switch to [ 8 ] or better to [ 10 ]
... machine user para spindle \ page 5 \ spindle power peek cut : change it, cycle power, check for difference
... machine sys para spindle : torque limit to be 100%
... parameter SPINDLE ACCEL SET; possible not to find it, because it is optional

if you need a reference program for acceleration time :

Code:

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G50 S2000
G04 F1.5
M331
V1=VDIN[1000]
G97 S2000 M3 M42
G04 F1.5
M331
V1=VDIN[1000]-V1
M05


FWRITC D.TXT;A
PUT V1
WRITE C


M02

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please be aware, there may be something related to your power source : High power source inductance of input power supply results in longer acceleration/deceleration time of the spindle. Also, operating with a high-inductance power supply can trigger the protection circuit in the DC power supply unit. Rated output is guaranteed under normal rated voltage. Fluctuation in input voltage can result in rated output not being met, even if the fluctuation is within the allowable voltage range / kindly :)

Have you check your torque limit value for the spindle? It should be in the "machine system parameters (spindle)" area. Maybe it has been turned down from 100%. What you describe is very unusual and not normal by any means.

Another thing to check is orientation sync speed. Perform an M151 with the spindles stopped and 1 chuck open. It should complete quickly...say under 2 seconds. If it doesn't then we may have something going on there that's slowing the sync.

If I'm understanding you correctly, when accelerating/decelerating without sync, The main goes slowly and the sub goes normally, correct?

Best regards,

Yes, I checked this. All the machines are set at 100% for the torque limit value.

With the sub spindle open, M151 less than 2 seconds.

That's correct, even without the spindles synced together the main spindle takes twice as long to accelerate and decelerate than the sub.

I understand what Deadlykitten is saying about comparing machines with like features. But even our LB3000 with the big bore is within a second of the LT2000 machines with the 2" bores.
Something isn't set right on this machine or has gotten changed to suit who had it before us.

I changed the main and the sub to the largest chuck that was available and it added 5 seconds to the cycle.

hy zufan, check the power suply; it appears a few times inside manuals as a warning, and leads to increased acc/dec time :)

there is a faulty situation during which the spindle still works, but slower

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I understand what Deadlykitten is saying about comparing machines with like features. But even our LB3000 with the big bore is within a second of the LT2000 machines with the 2" bores.

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in such a case, sorry :) ignore my advice / kindly :)

Ok, I think that you should check the current draw on all 3 phases going to the motor and compare readings. My suspicion is that you have a motor problem. If familiar, you could meg the motor to check the windings. If it's pulling on only 1 then it will be much slower and weaker.

Does the motor seem weak when cutting?

If the motor checks out, then you would need to contact Okuma and have them use their SPIN-V software to make adjustments to the spindles.

If the motor doesn't check out, check by the bottom of the spindle for the labyrinth vent. Occasionally these got clogged and caused the coolant to not drain properly and back up into the integrated spindle causing the motor to short the windings. Be careful though if you have someone try to repair it. Our dealer wanted almost 2x the cost due to wanting to order parts that weren't needed. Armature was scored but perfectly functional, just needed cleaning. Windings were toasted.

Best regards,

PS> more details on the pictured mustang please! ;-) Need for speed?!

Thanks! I'll pass this info on to our maintenance team.
I've only ran a few jobs through the machine. Nothing that was really pushing the load. Now the part that I have setup in one of the other machines would be a good test, if they would get the high pressure hooked up. It's a radiator hose extension and I'm drilling a Ø1.375 hole 5.5" deep.

2011 45th Anniversary Shelby GT350 Super charged with 600+hp
We went to church with a older couple and he passed away less than a year after he had it built. He was only able to drive it once or twice. Being a 6 speed she couldn't drive it. So she let me take it to the car shows for her. Incredible car! She sold both of them in the last couple years :'(

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if they would get the high pressure hooked up. It's a radiator hose extension and I'm drilling a Ø1.375 hole 5.5" deep

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hy :) i have reached 6" without high pressure, with a similar drill, using custom peking