Encoder Pendant for manual motion control of hydralic pistons.

[leitmotif]

Press setup is just about as dangerous as maintenance - normal safeties are bypassed in both cases. In addition setup is done with the dies not fully aligned and dies can be damaged.

Instead of all this electric control to "manually" move the piston what if you put two valves in parallel with the "normal ie electric controlled" valve. One would be "high speed" the other would be "creep" with an adjustible needle which would allow them to creep into the position they want. These would be in locked box with only supervisor or setup guy with the key. Granted -- more valves fittings to leak etc etc and you will NEVER get them in the right position for all tasks but I think a little more foolproof.

I really like the pendant idea - that way the guy has the controls right there and his eyeball focused where he wants it.

IF I understand correct you are using multiple position push button switch. My concern here is that like a crane pendant the button can be bumped (like when you screw up and let go of the pendant and it hits whatever). A guard over the button would prevent this of course.

What about two buttons. Press button one which activates time delay THEN press button two to activate - other hand would be free to dial in the encoder -- as long as both buttons are pressed with the "delay time frame" then it would activate.

I guess when it comes to press setup you have to trust your people to understand the dangers and to know what they are doing.

I would not want to screw up a die and have to pay for it - there goes at least a year salary.

Dan Bentler

 

[CharlesM]

I haven't decided yet between using a Delta RMC or a couple of HYD02 modules in the CLX chassis (I guess either way they're made by Delta). The operators really liked the idea of something similar to the MPGs on some of our CNCs.

I think Delta is working on an encoder ref module that will fit into the first slot of an RMC150. This would be perfect for your application.

I have a manual mode where I do an open loop move that opens the valve a %. I let the operator select a % from 1 to 20 (depending on cylinder size) Then all I have is a 3 pos spring center selector that gives them an up and down.

 

[Peter Nachtwey]

I think you have the right input devices.

I would do what OkiPC suggest. I would just use a low pass filter to give the system a 'ramping'. It is easy to add acceleration and velocity limits. Position and jerk limits too.

The RMC75 has a reference encoder module. The RMC150 can use quadrature modules now. They are full axis modules, not a half axis reference module. The RMC150 reference half axis module is still vaporware. Someone want Profibus DP first.

 

[widelto]

I designed a flying cutoff machine for a steel pipe plant and use a 1756-hyd02 with a magnetostrictive feedback element located along the cylinder, the reason was that the cylinder has double rod and the feedback element can not be located inside the cylinder, the hyd02 drives a servo proportional valve that handles the cylinder.
I also use a 1756-M02AE to install a 2048 ppr quadrature encoder as a feedback only axis and this one is going to be your pendant unit, so when you move the encoder your cilinder is going to move in the same direction, in your case if you can install the magnetostrictive feedback element inside the cylinder is better, you´re gonna avoid some mechanical problems like alignment between feedback element and cylinder.

 

[Peter Nachtwey]

OT. Hint, use a higher resolution encoder.

I also use a 1756-M02AE to install a 2048 ppr quadrature encoder as a feedback only axis and this one is going to be your pendant unit

It is very difficult to gear to a master reference with such low resolution. I have a customer that was doing the same thing except I talked him into 72000 lines or 288000 counts per revolution. Then it is possible to calculate better velocities and accelerations for the master and therefore better velocity and acceleration feed forwards for the slave. This results in much tighter control.

 

[widelto]

Peter:
Thanks for your advise, your comments are always welcome.

 

[ndzied1]

This looks promising but probably overkill for your applicaiton:

http://www.microinnovation.com/en/desktopdefault.aspx/tabid-4/5_view-302

Not sure if it's really released yet. Not too much informaiton on specifics for the unit...

 

[TConnolly]

This looks promising but probably overkill for your applicaiton:

http://www.microinnovation.com/en/desktopdefault.aspx/tabid-4/5_view-302

Not sure if it's really released yet. Not too much informaiton on specifics for the unit...

I once tried to use one of ABs version of one of those things on the welding machine I mentioned earlier. It turns out that the integratation (at that time anyways) was far from complete and required us to set it up as a client on another HMI and write quite a bit of VBA to get the info into the PLC. It wasn't worth our time so that thing is still in a box around here somewhere.