Motor speed for press

B

boilermaker

Joined
Aug 26, 2005
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110
G'day all, I've been assembling all the parts to start building a press, ram pump motor etc. Here in Australia the biggest single phase motor i could get was 5.5hp 2900 rpm. and this thing is big!:eek: I mean BIG!:eek: :eek: 110# all up! needless to say carrying the thing up the stairs to my house was rather awkward! anyhoo my question is, will 2900rpm be enough to efectively power a 16 gpm pump running a 6" ram? or should i try to find some sort of bolt on gearbox to up the rpm? but will this affect the hp? sorry about all the questions. thanx in advance..
cheers!:) :) :) :) :)
 
5.5Hp? You obviously didn't try checking a Dairy farm Milking shed outfit. Sludge pumps and vacuum system motors run up to 25Kw, or close to 30 horses :P pretty reasonable costs for second hand motors if theres a farm upgrading to larger systems in the area.

Hope it works for you, I'd hate to think you carried that all the way up the stairs for nothing :D
 
Pumps are usually rated at 3600 RPM. If run at 2900 RPM you will get 80% of the flow rate. So a 16GPM pump will deliver a little less than 13 GPM. A 6" ram powered at 13 GPM will travel about 1.75 IPS. That will work.
A 22 or 28 GPM pump would be better for a 6" ram,but the one you have will do OK.The 5.5HP is plenty of power. Have fun and post photos.
Stacy
 
thanks for your replies, i had thought about buying a bigger pump but would 5.5hp be enough to power a 22gpm pump? I should alter my comments about the biggest hp availabe, i can get bigger 10hp+, but way to expensive and i would have to virtually get my house re-wired to run anything bigger than 5.5hp so the costs just become way too much. 1.75 Ips seems pretty quick though? maybe i'll just build it with what i've got and see how it works.
Thanks again.:)
 
A two stage 22 GPM pump at 2900 RPM would create 25 tons of force in a 6" cylinder. It would be a bit under powered at 5.5HP for a lifting device, but I think it should work fine when used as a forging press ( in theory it requires an 8HP motor).

With a 5.5HP motor, in the travel mode (first stage on the pump) it will only need to move the ram with no load at a fast speed, running at 650PSI.You should get somewhere around 2.5IPS ram speed. When the die contacts the billet, the second stage kicks in and the GPM drops to about 5GPM (running at 2900 RPM) and the PSI jumps to 2500. It moves slower and with more force. Your setup will cover the speed of travel on the stage one just fine. In stage two, it may not develop quite the full theoretical power in a 6" cylinder, but it will have more than enough for welding up damascus and flattening out bar stock.

Since the pump only increases the ram speed, not the force,I would say to make your rig with the 16 GPM pump you have, and change it to a 22 later if you are doing larger billets. If it is free, then use the 22GPM, if you have to buy it, use the 16.

Stacy
 
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