Parker Proportional Valve not Working at Lower Pressures

[FiestaEng]

We recently installed a Eurotherm 3508 controller, a Parker PCD00A Amplifier with two Denison R4R03 and Parker VP01 Sandwich valve assemblies.

It is a horizontal press that closes initially at 100 bars and ramps up from there to a maximum of 240 bars. That part of it works fine. The second cylinder controls the presusre at which we inject material between the press plates. We normally fill the cavity at 15 bars and then increase to 150 bars for part of the cycle. We disconnect the directional valve to the cylinder to eliminate everthing from that point on. On a pressure port on the block manifold before the directional valve; we see no pressure until the controller ramps from the 15 bars to the 150 bars, usually in the 50 bars range we see it start to increase but don't catch up to the controller until it reaches 100 bars or so.

I am thinking the set-up is unable to achieve what we need but not sure. I ran a test where I spiked 100 bars for 2 seconds and then went back to 25 bars and it looked fairly good on the gauge. The problem is, this in production would cut the dies that we use and cause additional issues.

Any suggestions on making this work or other options would be greatly appreciated.

 

[HPost]

The valves you have noted are both pressure control valves.

What are you trying to do and can you provide a picture or a schematic diagram of some sort?

 

[HPost]

Also...

What is the pressure range on the VP01 valve, the data sheet shows are dead band at low pressure? The higher pressure valve don't respond until the command voltage reaches 30%.

If you have low flow through the valves, that will compromise the valve response as well.

What flow are you pushing through the valves?

 

[FiestaEng]

With ED4 disconnected, we monitor pressure from PP5.

30% of 200 bars would put us at 60 bars which is where we see it start to react. This supports my theory that this set-up will not work no matter what I try to do with it. The flow is minimal, basically just pressurizing the cylinder at a controlled rate to get proper slip flow into the cavity.

We switched to this valve/amplifier/controller because the ones we had are obsolete. What options do we have then?

 

[kcj]

Sundstrand/Sauer/Danfoss makes a pressure control valve that we use by the hundreds. It is an MCV nozzle/flapper first stage with two separate spools as second stage. Fairly old technology, open loop, and rugged. (We close the loop on force with other electronics).

Transducers on output and closed loop controller?