Hydraulic Pressure Relief Valve Question

[rwunn]

Folks,

I know we are mostly about tractors. I don't have a question about my Kubota, but do have one about hydraulics. Because you guys seem to understand the topic I am coming to you.

I have a new custom built, electric hydraulic press and need advice. The press has a 2 hp motor and a 5" cylinder with a 16" stroke. I need to install some type of "valve" or "device" to be able to dial in a specific, and in my case, lower, gauge pressure. I am familiar with calculating force. That is not the problem. I would like to put in a device that I could set to a specific pressure that would shut off the motor, or bypass the hydraulic lines at a specific, preset pressure. I would like repeatable pressing within small limits. Advice is welcomed on how this can be accomplished. Thanks to any who reply.

Admin, if this is inappropriate for this forum, please delete and accept my apology.

Ric

 

[birddog0304]

Welcome Ric. Lots of very intelligent folks on tbn. Are you wanting a single preset pressure, multiple presets or something adjustable?
I would think an adjustable relief valve on the high pressure side emptying in to return line or reservoir along with a pressure gauge teed in to the high pressure side would allow you to accomplish your goal at a basic level.
I welcome any additions or corrections to my thought process.

 

[SSdoxie]

I agree with Birdog, an adjustable relief dumping to tank. Locate the valve and guage close to the inlet to cylinder for most accurate reading then if you have if you have some commonly used pressure setting you can put different marks the guage face to adjust/set pressure without going back to the pressure to force calculations.

 

[leonz]

Folks,

I know we are mostly about tractors. I don't have a question about my Kubota, but do have one about hydraulics. Because you guys seem to understand the topic I am coming to you.

I have a new custom built, electric hydraulic press and need advice. The press has a 2 hp motor and a 5" cylinder with a 16" stroke. I need to install some type of "valve" or "device" to be able to dial in a specific, and in my case, lower, gauge pressure. I am familiar with calculating force. That is not the problem. I would like to put in a device that I could set to a specific pressure that would shut off the motor, or bypass the hydraulic lines at a specific, preset pressure. I would like repeatable pressing within small limits. Advice is welcomed on how this can be accomplished. Thanks to any who reply.

Admin, if this is inappropriate for this forum, please delete and accept my apology.

Ric

You should contact the folks at Mentor hydraulics in Mentor, Ohio
and you can obtain the right valve assemble with the relief in one unit
with both pressure and flow control.

 

[J_J]

The relief has to be caused by a hard stop to stop at a certain distance.

If the item you are bending, is soft, then the relief will not be met

 

[shona13]

G,Day j-j.
Why ?????????????.
Hutch.

 

[J_J]

Why what,

You don't always need relief pressure to shape and bend parts.

If you allow the cyl to reach relief pressure, it may go past your intended stop.

I believe you need a physical stop on the cyl to form the part correctly.

If you only intend to bend, then there is room for error. You bend until the shape is made. You may have to bend past the angle to get the correct fitting. For instance, you may have to go 95 degrees
to get the 90 due to spring back.

 

[shona13]

G,day jj.
If the relief valve was set at the correct pressure to give the required result the ram would stop at the same point everytime,the machine is custom made I would not think it would be made so much overspec that it could not be controlled by relief pressure.
Anyway a more accurate result would be achieved by either installing an adjustable trip stop and or an auto return solenoid,also depending on what is being done adjust the relief valve pressure to lower the operating pressure no need to be running at max pressure with this ram size and a supply pressure of say 2000 psi it would be possible to exert a force in excess of forty tons at the ram end.
Thats all .
Happy Days.
Hutch.

 

[IceStationZebra]

I am not an expert on presses by any means, but I do not believe that they are normally pressure controlled. The ones I am familiar with actually stroke the same amount every time, but the lower form is raised or lowered to control the minimum distance between the dies. Like JJ says if you rely on pressure you will get inconsistant results as your raw material changes. Each batch will vary a little in temper, thickness, etc.

ISZ

 

[wdchyd]

I've seen it done by using a series of microswitches....an adjustable on the extend and a fixed on the retract (home position)......but this would usually be accomplished by using soleniod control valves to limit stroke, not manual valves.......