Unproportional Speed using Powerflex 40

[OkiePC]

The bump a timer number could be a quick fix, but a more elegant long term solution might be external feedback on the driven axis. Perhaps a job for an AMCI resolver module?

I used to work with angled stock cutters in the tire industry, and became a big fan of their resolver modules so your mention of angles and PLC trig reminded of that.

In any case, knowing the position of the cutter itself, you could then turn your "poor man's servo" into a much more precise and reliable "positioner on the cheap". That's something I did many times at the rubber factory and had great success, but I did have an analog speed reference bewteen the PLC and VFD, and resolver feedback in most cases (The HT-20 is indestructible).

If the motor and cutter are positively connected, then a shaft encoder on the motor would be nearly as good less any drive train slack.

 

[Saffa]

Gotta love it when the PLC guy has to "program away" some mechanical / civil engineer's design flaw

I think the general consensus is the need for some additional feedback.

You mentioned the proximity sensor in the middle - would it not be possible to move this to one side, and add another prox on the other side? Bit of a guess without knowing what the cutting blade looks like etc, but you could then stop the blade as it got to each side?

Good luck, hope you can sort it out!

 

[Christoff84]

Gotta love it when the PLC guy has to "program away" some mechanical / civil engineer's design flaw

Job Security!

 

[OkiePC]

You mentioned the proximity sensor in the middle - would it not be possible to move this to one side, and add another prox on the other side? Bit of a guess without knowing what the cutting blade looks like etc, but you could then stop the blade as it got to each side?

Good luck, hope you can sort it out!

If I understand the application correctly, the center is the center at any angle, but the ends would both move when the angle is changed. Having to move two proximity sensors as part of every angle change might be feasible. At my former job, angle changes might happen six or seven times per shift...and scrap caused by a fouled up cut was quite expensive.

 

[only1vip]

OkiePC, you understood the application exactly, thanks for answering Saffa's question.

I am going to suggest using a resolver (Thanks OkiePC) to finetune this problem. They may not want to shell out the money it if they can tinker with the bump I added, but as Christoff said - Job Security!

Thanks All!

 

[milldrone]

only1vip,

I believe the second problem with this system is the extreme slip that your Eurodrive motors have. If you do have a chance to install a feedback loop I hope a motor changeout is also planned.