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quadrant protrusion in Y axis, but only in high feedrates, while backlash already set!

Created by: justbabak at: 12/10/2010 11:50 AM (15 Replies)

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12/11/2010 7:11 PM	Rate (0)
OvidiuNastac Silver Member Joined: 1/29/2008 Last visit: 7/26/2022 Posts: 419 Rating: (19)	Hi Ekalavya I know about the Circularity Test on 840 with HMI Advanced but I didn't know about 802D. Thank you for information but any way, what about the measurement system (he has only the encoders on the motors) which will not give the real displacements values? Nit

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12/12/2010 3:40 AM	Rate (0)
Ekalavya Posts: 2964 Rating: (482)	Hi NIt.... Good Morning.... If all axis is properly Optimized he can get the result...... Regards, Ekalavya
Ekalavya Posts: 2964 Rating: (482)
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12/14/2010 10:12 AM	Rate (0)
justbabak Posts: 11 Rating: (0)	Ekalavya justbabak thanks Ekalavya , ok, I can try although I have not done this before! but, how the measurements are done, as there is no linear encoder (scale) on my machine installed, so how the circularity test is done? Hi.... Attach Document is PDF file check out the procedure how the Circularity test is done.... Check it out.... Regards, Ekalavya I checked it, but you did not tell me about not having a scale (linear encoder), I still wonder how can we do it without feedback?
justbabak Posts: 11 Rating: (0)
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12/14/2010 10:34 AM	Rate (0)
justbabak Posts: 11 Rating: (0)	Nit Hi Usually a step of 0,05 mm or around it will be not observed on the surface of the piece. You must try and see. It would be better if you can perform a test with a Ballbar instrument (similar with the Circularity test from the HMI but as a stand alone system) which can show you the results at different speeds. As about the incapacity of the Y axis to travel fast enough, I'm not agree with you since the X axis is moving at the maximum speed at the Y quadrant transition and the Y axis must stop at that point (for a split second). The real issue is that the Y axis motor jumps suddenly at that point in such a way that it must compensate the entire amount of the backlash (in a single IPO cycle) even if it must move only some microns. Good luck Nit I checked the parameter, it was 0.1, so I changed it to 0.05, but It seems there's nothing changed. I changed #36500 only for Y axis, right? or, should I have changed other axes as well? I let them be 0.1 as before for X & Z axes. then I noted some fishy thingsin my machine: 1- the backlash has changed since 2 weeks ago that I set, yesterday I checked andit was 0.4 (0.07 increased!!) 2- there is impact at the reversingdirectionof Y axis, when I give it a repeating back and forthmovemnet, there is a significant impact at the reverse point, also I found out that this impact exists when I change the speed (by pressing "rapid" button in jog mode) at the same direction of Y axis movement. I took a video for back and forth state, it is not so good, but may help I worry so much about the machine, I think it is going out of control whats wrong?! Attachment VIDEO_033 shock impact.zip (185 Downloads)
justbabak Posts: 11 Rating: (0)
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12/14/2010 4:22 PM	Rate (0)
OvidiuNastac Silver Member Joined: 1/29/2008 Last visit: 7/26/2022 Posts: 419 Rating: (19)	Hi If the MD 36500 was 0,1 that means that the number of IPO cycles in which the backlash is applied is 3. It is normal to nothing change since you decreased this parameter. Any way since the backlash value has changed in two weeks means only one thing: you have mechanical issue(s) on the axis especially if you hear an impact. Most probably the bearings. You must find at first the mechanically issue(s) and resolve it and after that you can put the correct value for the backlash and the MD 36500. Good luck Nit

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12/14/2010 4:24 PM	Rate (0)
Ekalavya Posts: 2964 Rating: (482)	Hi... I checked it, but you did not tell me about not having a scale (linear encoder), I still wonder how can we do it without feedback? ==> Motor ENCODER its self is quite sufficent.... I feel better to take graph and check out...there will be clear idea... >Check the error Quadrant change over of axis and to reduce it, Enable frictionalError compensation ( MD32510=1) and Use Frictional compensation constant(MD32520) and frictional compensation time (MD32540)Reduce the error as much as possible > Similarly Circularity test to be done between XZ and YZ > Enter the Backlash Value(MD32450) and Enable Pitch error compensation(MD32700=1) Hope this will helps out... Regards, Ekalavya
Ekalavya Posts: 2964 Rating: (482)	Last edited by: Ekalavya at: 12/14/2010 4:26 PM
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