Thread: Another hydraulics question

whats size is your cylinder is the obvious question but in short i would say no,its not big enough,im running a 10 hp three phase on a bosch pump and a 7.5" id cylinder and i get 33 tons on my horizontal bumper press at aspeed that is satisfactory.you may well get satisfactory tonnage or speed but not both.cheers danny

Tonnage is directly related to pressure....This machine makes 3000psi, so the tonnage it can generate in a ram is the area of oil acting on the piston...

The flow rate means that it will run a big ram slow and a small ram fast...

For the record I would prefer a hand pump on a press...You have far more control over how much you are pressing...My press is a 60 tonne one and has a two stage hand pump for fast and slow speeds...The fast speed generates negligible pressure, while the slow speed goes up to 5000psi.

HI,
I don't have a Cylinder as yet, I was merely asking if the Pump would be big enough for a 30 Ton Ram. I don't know what the Formula is to do the Calculations for Flow Rate, Pressure, Cylinder Ram, Bore and Stroke size. I would be looking for reasonable Cycle Times as well. I agree that a Hand Pump does give You more Control, but sometimes You need Hands Free Operation (without getting you're fingers squashed).
I am looking at making a Press Brake Attatchment to go with the Press. For a Press Brake I would prefer Hands Free Operation. I may make a seperate Unit with a 20 Ton Ram (like Shop outfitters one) for the Pressbrake though. I might get some Quotes at some stage for Manual Pump, Air Hydraulic, Electric Hydraulic and 30 Ton Ram.

All The Best steran50 Stewart

The shortest way to do many things is to do only one thing at once.

As .RC. said tonnage directly relates to pressure. And flow rate directly relates to cycle times. Here are some formulas to work it all out. I prefer to work in metric, but I will put the conversions here too.

Pressure PSI to N per square metre/Pascals is PSI 6894.76.
So 3000 x 6894.76 = 20684280Pa (which is also 20684kPa = 20.7Mpa).

Pressure X Area = Force and Area = PI X (radius squared).
For a 125mm diameter ram, radius is 62.5mm. Area is PI X (62.5 squared) = 12271.85mm squared. We need the area in metres squared, so divide by 1000000 (1000mm X 1000mm). This gives an area of 0.0123m squared.

Therefore Force = 20684280 X 0.0123 = 253834.3Nm. To get this into tonnage you need to divide by gravity's acceleration 9.81 metres per second per second. This gives 25875kg of force or 25.8 ton. Easy!

Now for speed/cycle times. For this we need the area - 0.0123m squared - in square centimetres. To do this we need to multiply by 10000 (100cm X 100cm). This gives an area of 122.72 cm squared.

Flow rate / Volume = Ram speed.
The pump you mentioned lists its output as 5.6L/min. One litre is 1000 cubic centimetres or 1000 millilitres. So this flow is also 5600 cubic centimetres. If we divide the cylinders area into this volume it will give us the rams speed in centimetres per minute - 5600/122.72 = 45.63cm/min. This for extension only - retraction will be quicker due to the shaft reducing the volume of the cylinder on that side.

So a 5" or 125mm ram will only generate 26 ton of force, and extend at a rate of 46cm per min. You need a larger diameter ram to generate the force required, and your speed will be slower. 6" or 150mm will give figures of 37.3 ton and 31.7 cm/min. 8" or 200mm will give figures of 66.2 ton and 17.8cm/min.

Hope this helps a bit.

HI,
Thankyou very much 'markjaffa' that info will be very useful. I was looking on eBAY on the Weekend and seen this Workshop Press 30,000KG / 30 TON HYDRAULIC H PRESS * Tools, Workshop * - eBay Other, Tools, Car Parts, Accessories, Cars, Bikes, Boats. (end time 21-Jun-10 21:33:38 AEST) the Picture is not the Best. I would say by the Price its Chinese, but it's sound too Cheap to Me - probably not very good Quality.

All The Best steran50 Stewart

The shortest way to do many things is to do only one thing at once.

Steran

most smaller (up to around 5HP i think) 3 phase motors are configured in delta (or can be configured to) and will run ok via a single phase input- three phase output vfd/vsd

HI All,
I had a look around at prices for Hydraulic Rams and Pumps since I was last on. They are far more in Dollars then what I want to Spend. I estimate about $750.00 to $1000.00 for a 30 Ton ram and Manual or Air Pump I am swinging back to the Inverted Bottle Jack Press. I have seen some of the Chinese made Workshop Presses and they are not built very well. Thats why I want to build My own.So I did some searching for Inverted Bottle Jacks. I found 'Larzep' make a 15 Ton and 30 Ton Inverted Jack. Also 'Armstrong' does the same sizes (could even be the same Jacks). I have in the Past built a 20 Ton Press with a Jack that I Inverted Myself heres the link to it. https://www.woodworkforums.com/f184/b...-press-102480/

What My question now (out of curiosity) is what size Diameter Work Table Pins would I need if I was to build a 50 Ton Press ?. I know from Research that 'Larzep' 30 Ton Press has 27mm Diameter Holes in the Press Frame http://www.larzep.com.au/downloads/a...ve/EZ03012.pdf.
The Larzep 250 Ton press has 80mm Dia Holes in its Frame http://www.larzep.com.au/downloads/a...EE25030-CE.pdf.
On My 20 Ton Press that I built used 19mm 4140 Solid Round Bar for the Work table Pins. I drilled Holes through My Press Worktable so the Support Pins pass through it. The larzep Presses Worktables seem to rest on the Support pins.

Out of interest has anyone ever Converted a Air Hydraulic Jack to Work Upside down (Inverted) ?. If I decided to make a 50 Ton Press I have been looking at this Jack LHJ50 50T AIR HYDRAULIC JACK-4RET/SP - $289.58 : Belic Tools and Machinery Pty Ltd, For All Trades And Industries and converting it. I have heard that If You add an external Oil Reservoir to the Jack it will Work upside down. I do not know if this applies to an Air Hydraulic Jack, as I know very little about them.
Thanks in advance.

All The Best steran50 Stewart

The shortest way to do many things is to do only one thing at once.

I have a 60 tonne press, I can take measurements if you want..

Originally Posted by .RC.

I have a 60 tonne press, I can take measurements if you want..

HI RC, Yes Please that would be good if you could Measure the Support Pin Size. On Your 60 Ton Press. Do the Support Pins pass through the Worktable or does the Worktable rest on them ?. I am seriously considering the 50 Ton Option. The Only thing though the Holes for the Support Pins would have to be done out of House. My Drill Press can only Drill 32mm. Another downside with the 50 Ton option is 50 Ton Bottle Jacks don't (not that I have found) have a Screw Extension which can be handy.

All The Best steran50 Stewart

The shortest way to do many things is to do only one thing at once.

The pins are 1 7/8" The pins pass through the worktable...

I really doubt you need a 50 tonne press... The most pressure I have ever used is 42 tonnes and that was to remove a rusted pin out of a dozer ram. 90% of the time I use under 5 tonnes..