Weld Inc

I am looking into going with an accumulator. With my five gpm pump and five inch bore cylinder what size accumulator is sufficient to make it worth the extra cost of accumulator and valving? Is a piston or bladder type better? What type of accumulator circuit is recommended? Thanks for all the help everybody!

I would like to do general smithing but punching and drifting is more important for me then drawing out. Grant, when you say that you have preached that 15 tons is enough but it needs to be fast, how fast is fast? Is two inches per minute fast? Is the speed just for getting to the work or for doing the work once it is there as well? I see most people are using the two stage log splitter pumps and many with just a five horse. That gives a fairly slow speed once under pressure doing the work right? Thanks

Sounds like a scary or at least messy learning curve! Given correct and balanced valving and an appropriate cylinder do you think I could come up with a good forging press for punching and drawing with a 5hp 5 gpm power unit? Not sure why but I am stuck on getting the unit. Seems like a good price and I like the idea of a single stage variable displacement pump. I have calculated that with a four to five inch bore size I could get around an inch per minute ram speed at normal pressure and almost two inches per minute with the regenerative circuit. That's with 15 to 20ish tons pressure if I can get 2500 psi out if the pump. I don't have my calcs with me so that is from my heavily weathererd memory. Thanks for the input!

I was also wondering how important is the retraction speed? Is it important for lessoning work contact time (heat loss or seizing punches etc) or just general practicality?

If I am understanding things correctly, a 5gpm pump is adequate for doing the actual work but not efficient practically in terms of getting the ram to and from the work? I have done some research on valving circuits and discovered the regeneration circuit which in essence can negate the bore size and run a cylinder with less force at the speed of a cylinder with a bore the diameter of the the rod, of course with correspondingly less force. Then it can switch back using the cylinder in a normal fashion at slower speed and higher force. Here is a link to a very good example, ( and much better explanation!) My link. Does anyone have any thoughts if this could work and be a good set up? I like the idea of an adjustable displacement pump with on demand pressure explained above. It could also mean I could get this power unit for the $250 i metioned earlier and spend more doe on the frame and dies! Thanks for your opinions!

Thanks. That helps a lot. I will look into finding an accumulator. I do like the aspects of the variable displacement piston pump and would like to make it work. With an accumulator and the variable displacement is it possible to get the best of both worlds being able to work smaller delicate operations backed off and larger operations full on with the accumulator in function? What type of accumulator would you suggest? I was also considering replacing the motor with a higher rpm motor or having this one rebuilt for higher rpm if possible.. . Thanks for all the help Jose

Thanks! Do you think that 5 GPM is to slow for a forging press used for punching and drawing out?

The power unit has a 5 hp motor 1730 rpm 3 phase. The pump model is PVB5RSY20CC11. I haven't seen the unit first hand yet so hopefully this us accurate. Any more info is greatly appreciated!

Thanks for the fast responses! How many inches per second is considered fast?

I have a chance to pick up a Vickers hydraulic power unit for $250. It has a 3 phase 5 hp motor running at 1730 rpm. the pump is a variable displacement piston ranging from 300 to 3000 psi. It is only 5gpm. Would it be too slow for a hydraulic forging press? I am shooting for a 15 to 30 ton press. This unit comes with a 5" or 6" x 18ish" cylinder (exterior dimensions). No exact specs on the cylinder but I could always get a different cylinder. Thanks!