4/19/2016 5:26 AM | |
Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (874) |
Well fine. Now configure this axis on motor feed back, i.e. disable external scale feed back & repeat the same procedure as above, note down 10 readings & post here. |
4/19/2016 6:53 AM | |
Joined: 7/4/2014 Last visit: 4/28/2024 Posts: 283 Rating: (0) |
Thanks We have standard list of MDs to bypass direct measuring system, we use the same for other machines whenever needed for test but in this machine with SI control, it does not allow us to bypass direct measuring system In case u suspect Linear scale, we can replace it with new one, but we dont doubt that Like after machine reference, Machine Position of Z is 0.0000 Position actual value meas sys 1 = -0.017 (motor encoder feedback) Position actual value meas sys 2 = 0 (scale feedback) Set Point = 0.0000 We are unable to understand what is causing motor feedback to deviate compared to direct feedback, this is the case at all positions of the machine, only the motor feedback is within +/- 30 microns with respect to scale feedback Kindly advice |
4/19/2016 7:39 AM | |
Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (874) |
I suspect scale alignment. Check scale alignment with respect to axis travel. It must be as per manufacturer applicable tolerance. |
4/20/2016 12:00 PM | |
Joined: 7/4/2014 Last visit: 4/28/2024 Posts: 283 Rating: (0) |
Just one more point which I forgot to inform to Forum is that few months back, scanner of Z axis scale broke and it was single reference type scanner, we were not having this in our stock hence replaced it with distance coded type of scanner retaining the same scale. We don’t exactly remember if this problem of Z axis , wherein only during positive movement, difference between Position actual value measuring system 1 & 2 is as high as upto 38 microns, started after replacement of scanner or not as we had couple of miscellaneous issues in this machine We have taken out scale for cleaning and realignment to check and update further Regards |
4/20/2016 12:48 PM | |
Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (874) |
Could you please post both the scanners ID numbers & part numbers? |
4/20/2016 2:53 PM | |
Joined: 7/4/2014 Last visit: 4/28/2024 Posts: 283 Rating: (0) |
Cleaning & alignment didnot help, still diffrerence between position actual value meas sys 1 and 2 is upto 50 micorns in +ve direction, OK in -ve direction We plan to replace entire scale with scanner with new one which was originally fitted in the machine, then update you the status Pl tell me one thing how do we conclude the problem is in the motor feedback or scale feedback because position value meas sys 1 and position value meas sys 2 are not same in +ve direction, sometimes position value meas sys 1 matches with Set Point, sometimes Position value meas sys 2 matches with Set point (ie Machine Position) Regards |
4/20/2016 3:48 PM | |
Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (874) |
Hello, 1. You will never get measuring position value 1 & measuring position value 2 exactly same. 2. Yet you didn't provide the Heidenhain make scanner details. If you had replaced the scanner with the same ID, it won't make much difference/problem. My suggestion is before proceeding for new scale, please switch over on motor encoder, take the readings. This will help to identify the problem. HTH. |
4/28/2016 12:22 PM | |
Joined: 7/4/2014 Last visit: 4/28/2024 Posts: 283 Rating: (0) |
Thanks a) As already informed, in this SI controller, we are unable to bypass scale as per standard procedure by altering set of MDs b) Last week , we had replaced LS186C with LS186 (originally this machine had LS186 only), reference mark was not coming up hence could not reference but even with LS186, we found diff to be bare minimum in negative direction and upto 40 microns in +ve direction, taken out and fitted back LS186C c) There was one more observation - after running grinding wheel for a while, when we used to stop wheel, and try to pull out with hand, play upto 250 microns observed but after keeping wheel in stationary condition for about 30 minutes, there was no such play. There is unit at the center of the wheel, which actually tightens up the wheel against flange, we found mounting screws were reaching till the dead end, we ground that unit at little then tighten up firmly, now run out on face has improved and we are able to use the machine Regards |
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