Explain principle, construction and working of Hydraulic press
Answers
WORKING PRINCIPLE: The working principle of a hydraulic jack may be explained with the help of Fig. 23. Consider a ram and plunger, operating in two cylinders of different diameters, which are interconnected at the bottom, through a chamber, which is filled with some liquid.
Let
W= Weight to be lifted,
F = Force applied on the plunger,
A = Area of ram, and
a = Area of plunger.
Pressure intensity produced by the force F, p = F/Area of plunger = F/a
As per Pascal’s law, the above intensity p will be equally transmitted in all directions.
Therefore, The pressure intensity on ram = p = F/a = W/A or W= F(A/a)
Above Equation indicates that by applying a small force F on the plunger, a large force W may be developed by the ram.
Mechanical advantage of press = A/a
If the force in the plunger is applied by a lever which has a mechanical advantage (L/l) then total mechanical advantage of machine = (L/l)(A/a)
The ratio (L/l) is known as leverage of press.
Hydraulic jack may be employed for the following jobs:
Metal press work (to press sheet metal to any required shape).
Drawing and pushing rods.
Bending and straightening any metal piece .
Packing press.
Construction and working of Hydrualic Press:⤵️⤵️
In practical hydraulic press system, generally multiple rams are assembled together. The number of rams used depends upon the working load. In hydraulic press multiple rams of small sizes are preferred instead of a single large size ram to control the thrust forces because it is easy to control the thrust forces on small size as compare to large size. In press assembly one side/table is always fixed while the other is moving by the application of ram force and in between fixed as free side pressing operation is take place. Ram is operated by the hydraulic pressure of fluid. The high pressure liquid is supplied by using pump and hydraulic accumulator. Hydraulic accumulator works as the junction between the pump and the rams. Hydraulic accumulator stores the high pressure liquid when press is at stationary position. Hydraulic press is used where high thrust is required for operation.