Hydraulic press design need help.

[NBR90]

Hello, I'm designing a typical hydraulic press. I'm using 2 posts [2 solid cylinders] instead of usual 4 posts for support. It is used for hydro-testing valves. [jpeg pic included]

The two cylinder posts [Grey color in the jpeg pic] ~ 130 mm diameter.

The thickness of two plates [purple color in the jpeg pic] ~ 100 mm thick each]

The 300 ton hydraulic press on RIGHT side [In red].

Cylinder rod of the hyraulic JACK ~ 200 mm diameter [not seen in jpeg].

The movable solid cylinder with unknown 'X' diameter on LEFT SIDE[stripped grey in jpeg].

The maximum length (daylight) between the two plates is approximately 1320 mm. The maxium width between the two cylinder posts are 800 mm.


Quenstions:

1) The 2 cylinders I will be using is about 130 mm diameter. Will this be sufficient?

2) The 2 plates on each end [purple], are about 100 mm thick [1200 mm wide [in the same direction as the two posts and about 1000 mm height]. Will this be thick enough?

3) I am also designing a cylinder with X diameter that is movable [turning gearbox - thread type] that will move along the length of 1300 mm. It will be screwed on the left side of the plate. At its maxiumum reach, ~1300 mm away from the left plate, what would be minimum diameter required to withstand 300 ton of force from the right side? I'm thinking about 150 mm diameter.


Any help would be appreciated!

 

[TED7]

I can't be much help on the calculation side but have you looked into a vertical setup? That way you will have less of a problem with deflection of the guides as they wont be bearing the same kind of loads.

I assume the screw device is to allow you to reduce the travel of the press to increase speed processing smaller parts. All the presses at our place have travel stops which keep the press from retracting all the way. These mostly use blocks on in a t-slot to set distance, picked up by a proximity sensor, all connected to the pump control.

Designer of machine tools - user of modified screws

 

[ricklts]

you haven't said at what pressures you will be testing nor the strength of the materials you have selected?

why 300 Ton on one side and only 200 ton on the other?

how will you support the valve once it is installed for test?

more questions, but these will do for a start.

 

[JStephen]

If you're asking us if it's stout enough, then you're not designing it, you're asking us to design it for you, and that is not the purpose of the forums.

 

[MiketheEngineer]

There a number of companies that build these ---- and they still have trouble.

Look into a new or used one..

 

[NBR90]

Typical carbon steel, the two cylinder posts will be heat treated, hardened to 50 degrees hrc. There is only one hydraulic jack that will go up to 300 ton at 6000 psi. The 200 mm is the rod diameter of 300 ton hydraulic jack that will be pushing the green plate. On the right side I chose a handwhee type threaded bolt that can move the length [0 to 1200 mm] to provide the opposing force to squeeze the valve between 300 ton jack and threaded bolt. The reason is the valve length range from 100 mm to 1320 mm. It is not economical to purchase a 300 ton jack with 1300 mm stroke. Also the handwheel turning threaded bolt can act as a non-squeezing force as it stops dead right at the flange face as opposed to hydraulic squeezing force that can deform the valve. So some customer do not want destructive force leak testing [hydraulic jacks squeezing the valve between two plates] so we would use the handwheel turning threaded bolt.

I know the 300 ton jack has a rod that is 200 mm in diameter. Im wondering on the other side, what the minimum diameter must be to support the opposing force of the 300 ton jack at up to 1300 mm length.


The pressure of the valve is variable as as we so many classes and dimensions. I have only 300 ton of force to work with that can be adjusted[ ie we would use ~300 ton to test 8"x2500#, 160 ton to test 6"x2500#] these numbers are just off top of my head, the exact calculation will be done later. Our limit will be at around 10"x 1500# valves [required api 598 hydro tested to 5625 psi or so]

The point is to design the bolt to withstand 300 ton force. Im thinking at least 170 mm diameter now.

Aso it must be horizontal placed as that is easiest way to use a overhead crane to place the valve between thd plates. Soms of the valves are 2 tons.

 

[NBR90]

Jstephen,

Im asking for help, a way to calculate the dimensions required to withstand the forces. These dimensions are not random gibberish, they are based on information offered by few machinists and even a similar 200 ton model that was shown to me, no one is expecting them to design it for me, they just kindly help me with what they could. That is far from asking you to design it. Ive done much research into this, and even built a smaller 20 ton version based on intuition, so far it has worked flawlessly. Now we are getting to 300 tons, I would like to know how you would calculate the required forces even though i have an approximation. I thought these are what these forums are for, Ive seen more complicated questions asked here without any drawings or efforts. I mean do you go telling them the same thing? If you do., u seriously have too much time on your hands... why not use it constructively.

 

[btrueblood]

"Hello, I'm designing a typical hydraulic press." ... "It is used for hydro-testing valves. "

Um. I'm no expert, though I do the same thing for a living.

We proof-pressure test our valves with blind flanges or end cap fittings, i.e. we force the valve body to bear the resultant stress of the piping attached under the rated pressure. Since that is how they are actually used in the field...or at least can be.

To put end forces onto your valves that can/may/might diminish those resultant stresses could be considered an under-test. Dunno if the piping code would agree with me or not, but that is my interpretation.

FWIW, we use a similar arrangement for speeding the flow testing setups, but decided to not use that above a certain size, i.e. when hydraulics became called for, since use of them would require a much higher level of safety and lockouts, and much higher potential threat to human life/safety than a manually operated over-center clamp. 'Twas my decision to make, and it's the side I came down on. But then, I like the people I work with...

 

[JStephen]

1) The 2 cylinders I will be using is about 130 mm diameter. Will this be sufficient?

That depends. Actually calculating stress in a rod under tension comes from about the first chapter of a Strength of Materials textbook. The bigger issues here are selection of materials, connection details, and fatigue and stress concentration at the connection points. For structural materials, it would be reasonable to use allowable structural stresses from steel codes or other sources. For other materials you're on your own.

2) The 2 plates on each end [purple], are about 100 mm thick [1200 mm wide [in the same direction as the two posts and about 1000 mm height]. Will this be thick enough?

You could analyze these in various approximate ways either by treating them as beams, or using plate-bending formulas from Roark's Formulas For Stress and Strain. For a more detailed analysis, consider FEA.

3) I am also designing a cylinder with X diameter that is movable [turning gearbox - thread type] that will move along the length of 1300 mm. It will be screwed on the left side of the plate. At its maxiumum reach, ~1300 mm away from the left plate, what would be minimum diameter required to withstand 300 ton of force from the right side? I'm thinking about 150 mm diameter.

See the first answer above, and refer to various machine design handbooks for design of threads.

 

[Cockroach]

The reason why the plates are vertical is that the valve is lowered into the unit from a crane or jib. The end nubbin on the cylinder not only hold the valve through the axis, but seal against the flange face during hydro testing.

I've done equipment like this in the past, but not to 300 tonne. I think you're equipment components are too weak, judging by experience. I would need more numbers to justify that.

Also, how are you securing the cylinders from hydro jacking under your test medium pressure? Safety concern as well as protection of equipment damage would be paramount in this case.

I also suggest putting the unit into an underground bunker. Having blown up a valve in the past, it is a pretty dangerous situation and you will NEVER get all the air out of the valve.

I would strongly suggest doing an FEA on the assembly or at least selected components at a margin above the intent of operations. I would probably be thinking in terms of FOS=3.0 because of the nature of failure. So actually you are building a 900 tonne unit. You need some pretty big steel for that, bracing, weldament consideration, etc, all of which has not been mentioned.

Good luck with it.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada