Stepper Motor Cutting System

[cmarcus]

Hello Forum,

 

I've got a project where I've spec'd a V430 to run the show on an existing material handling and cutting system.  Everything was going great until I realized that the rotary cutter motor was a Nema 34 stepper.  What I thought was a digital "Go" signal feeding a programmable motor controller, ended up being a pulse train being sent to a simple pulse train amplifier.  

 

The proper sequence is to run a home routine when brought online (one revolution at 2kHz, and stop on the home sensor).  Then on the rise of a position sensor, run one revolution and stop back on the home sensor.

 

Clocking the existing PLC's pulse train, it accelerates to 5kHz in 30mS, when the cutter wheel is 45 degrees from home, coasts back to 2kHz, then stops back on the home sensor.

 

I tested out the PWM on my V430, but the signal is a bit dirty at 5kHz and the best I was able to get out of it was 3.2kHz and have the cutter work reliably.  Does anyone know any alternatives to get the full speed out of the cutter, short of swapping out everything for a new motor and drive?

 

Thanks,

-Chris

[Joe Tauser]

Been there and found that out the hard way myself.  Sounds like you know how to use a scope, which is good!

 

You've determined the speed limit of a regular transistor output, which I always tell people is 2 kHz.  The only way to properly drive a stepper controller is with a PLC that has the NPN high speed outputs, so you're looking at a -TR34 or a -TRA22.  With a maximum speed of 200 kHz you can micro-step and get real precision.

 

If you've still got the box and packing your distributor may let you swap yours out.

 

Joe T.

[cmarcus]

Thank you for the response, Joe.  I'll look into changing to a TR34 or TRA22.

 

Best Regards,

-Chris