Mechanical forging press: Mechanical forging press is a type of forging machine in which the forging action is carried out by means of a mechanical system and the die moves up & down by mechanical forces.
There are basically 2 types of mechanical forging presses.
Lets see each of these mechanical forging presses one by one.
#1) Crank press
Crank press uses an electric motor to drive a large heavy flywheel that drives the ram of the press through a crankshaft.
The function of crank press is to translate the rotary motion into reciprocating motion (i.e linear motion).
In order to engage and disengage the flywheel, a clutch is used. Also it is used to stop the crankshaft motion after the completion of forging stroke.
By using a crankshaft, the process of forging takes place in several repetitive strokes.
In crank press, the length of the stroke is shorter than the stroke in drop forging process.
The crank presses are rated on the basis of the force developed on the workpiece at the end of the stroke.
The pressing of the workpiece takes place like a squeezing process, and not like an impact force generated in hammer forging press.
Because of this, the damage occurring to the dies is also less in crank press operation.
#2) Screw press
Screw presses consist of a vertical screw which rotates in a nut fitted near the frame of press.
As shown in the schematic diagram of screw press, the upper end of the screw is connected with the flywheel and the bottom end is connected with the ram.
This ram reciprocates up and down due to the rotation of the screw which is attached with the flywheel.
The energy which is required to press the workpiece is obtained from the rotation of the flywheel via the screw.
Hence a limited amount of energy is transmitted to the workpiece from the flywheel.
As the ram moves downward and strikes the workpiece, the energy of flywheel gets transferred to the workpiece.
Screw press is used for forging presses of small precise parts like turbine blades, etc.
It is also used for bending and straightening operations as well as upsetting bolt heads.