Surface Grinder and PLC?

[topdoug]

I would like to replace the existing table cross feed controls(8 logic cards in a rack) for an old surface grinder with a PLC and an optional C-more control panel(Automation direct). This means starting, stopping, reversing, and controlling the run time of a 1/3 hp three phase motor. There are six proxy sensors indicating when to cross feed, when to change direction of cross feed, and maximum travel limits. There are three, functional, solid state relays that run the motor, also a contactor and a reversing contactor. Anyone have thoughts to share on this? Thanks, Doug

 

[jstolaruk]

Some would say overkill but you shouldn't have any problem. Should be a manual rapid traverse for the up/down of the spindle to get it quickly to a wheel dressing height and back, usually a couple of push buttons.

 

[JeffKiper]

Doug welcome to the forum...

I did a project just like that in a training class. I would use PB as jstolaruk if you try to increment down and the communications freeze from the HMI in the on state what happens??? Just some food for thought.

 

[TConnolly]

I did one many years ago to an old Chevalier surface grinder. I used a SLC-150 (so, yeah, it was a very long time ago).

Just watch the current loads on your IO.

 

[Peter Nachtwey]

On off control is pretty crude. Alaric has a point about the current. Grinders we have done go to a position or torque( current ) which ever comes first. Usually the grinder goes down in position mode and makes contact with the material. Torque tends to increase and the control output to the motor drops so the torque limit is not exceeded. Grinding proceeds at the torque limit for a short time until the final griding position is reached and the grinder retracts. A low select scheme works well in these applications but there is little you can do with just on/off relays.

 

[topdoug]

Thank you, gentlemen. I am encouraged. I intend to leave the spindle PB's intact. We downfeed by hand and usually go to size in one pass on this machine. It occured to me this morning that I can also leave the reversing of the crossfeed intact. Leaving me to deal with on, off, duration of the run time, and rapid traverse of crossfeed. This may seem elementary but I deal mostly with things like flashlights. Thanks again, Doug