Glimmersby Posted May 5, 2015 Share Posted May 5, 2015 I have a motor (screw driven axis) on the bridge of a gantry system that vibrates excessively (as if the tuning is way too high) at certain points in travel. This only occurs after homing or executing a program in automatic or MDI mode of operation. The vibrations will continue to cut in and out (only on the bridge axis) until the emergency stop is activated. Once the emergency stop is cleared and the controller reset, the machine can be driven manually (continuos or incremental/handwheel) with no problems. The vibrations return every time after executing a command or program in MDI/AUTO or homing the machine. They are also eliminated each time by stopping and resetting the drives. What could be causing this? I have tried replacing the Pmac with no change in the machine. If this was a wiring or encoder/resolver problem, I don't see how the mode of operation would matter. Link to comment Share on other sites More sharing options...
Omron Forums Support Posted May 5, 2015 Share Posted May 5, 2015 Hi, Are any of your PLCs doing gain scheduling that might be setting the gains too high at certain points in the travel? Link to comment Share on other sites More sharing options...
Glimmersby Posted May 7, 2015 Author Share Posted May 7, 2015 I don't think so. We use a single gain setting for each motor. We did find the bridge on this machine to be cracked at the welds on both ends. This put a great amount of stress between the X1 and X2 motors. Is it possible that noise from these two motors fighting to overcome this tension has been affecting the Y axis motor? We haven't been getting any foldback faults on the drive amp. Link to comment Share on other sites More sharing options...
chrisb Posted May 11, 2015 Share Posted May 11, 2015 I don't think so. We use a single gain setting for each motor. We did find the bridge on this machine to be cracked at the welds on both ends. This put a great amount of stress between the X1 and X2 motors. Is it possible that noise from these two motors fighting to overcome this tension has been affecting the Y axis motor? We haven't been getting any foldback faults on the drive amp. As a stop gap until you can fix the welds (this is likely one of the root causes) you can try cross-gantry coupling. On Turbo, this is a bit difficult to setup and you need a spare encoder channel. Below is a link to the White paper: http://www.deltatau.com/Common/technotes/Gantry%20with%20Cross%20Coupling.pdf 1. Are you commanding both motors in the same C.S as X (or same)? 2. Avoid master/slave, this will certainly cause poor performance. Regards, Chris Link to comment Share on other sites More sharing options...
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