hydraulic extrusion press

[keyur trivedi]

Hello everybody,
A 39 mm dia. rod is required to be hot extruded to 19.5 mm. The material is high carbon steel with 40 HRC. Please note that extrusion is hot. The extrusion is required to be done on 100 mm length. And it's indirect operated(die is moving not rod). Can any tell me the hydraulic force required for that? Plz send formula's for that also. Another 22 mm dia. is also required to be converted to 19.5 mm dia. So i request if anyone can guide me on right path.

With regards,

keyur v. trivedi

[Doug Hanson]

Keyur, attached is the formula for calculating extrusion force. Sorry it's in inches and pounds. Metal extrusion is not my area of expertise, so use at your own risk!!. Being that you are using backwards extrusion, there of course is no allowance for friction between the load and the chamber, as there is no movement between the two.

The biggest factor in calculating is what the extrusion constant is, which depends on the properties of the material and the termperature that you will be extruding at. Maybe your steel supplier can help with that number, I used a number for around 1100 degrees celcius, I probably shoud have went a little higher, but you can see how it's done.

I hope this helps. Once you decide on your hydraulic cylinder configuration, we can then work on the hydraulic side of things.

[keyur trivedi]

Hello,
By using diff. formula's i have decided to take extrusion force as 32 tons(32000kg).
For that load i have derived the following things,

Pressure required p = 200 bar (kg/cm2)
Pump type = vane type
Pump flow = 50 LPM
Bore of cylinder = 160 mm
Hp of motor = 30 HP

The derived entities are good enough for best design or some change is required? If required then please guide me in right direction so i can correct my self!

[Doug Hanson]

Sounds like a good starting point. What type of controls are required in this application? Will there be any pressure or position feedback?
What kind of delay time in between press cycles? What I'm getting at is,1) will this be a variable displacement or fixed displacement? and 2) will a standard on/off type soloinoid valve be adequate, or is a proportional or servo valve required?

What formula did you end up using to calculate extrusion force?

[keyur trivedi]

I have used different formula's and then checked the answer,
one of them is,
Extrusion force = A1*P1*(1+B)/B*(1-R^B), which is not very diff.to formula given by you!
where A1 = actual rod area,
P1 = flow stress of material
B = mu COTa, where mu=friction coefficient, a=coneangle of die
R = Ratio of radiuses!

Well feed must be lowered during operation, and it should be highest possible during return in order to save time. A regenrative cycle can be used. Solenoid operated 3 and 2 position valves req. to be used. but not propotional. Due to higher flow rate chances are there for pilot operated solenoid, but not sure yet. Cycle will be very simple i think since it will be a horizontal press no counter balance valve require. One big flow control valve and pr. relief valve, a press. switch and one 3 position solenoid, one 2 position solenoids are enough though i am thinking about variable disp. pump if i get it in my budget. Your suggetions are always welcome! positional sensors will be used for forward return and feed control!

[Doug Hanson]