Hydraulic System In Shaper

In this type of shaper machine mechanism, the ram is moved forwards and backwards by a piston moving in cylindrical placed under the ram.

The machine is consists of a constant discharge oil pump, a cylinder, a valve chamber and a piston. The Piston-rod is bolted to the ram body. 

The oil under high pressure is drawn from the reservoir. The oil is passed through the valve chamber to the right side of the oil cylinder exerting pressure on the piston.

This cause the ram connected to the piston to perform forward stroke. Any oil present on the left side of the cylinder is discharged to the reservoir through the throttle valve.

At the end of a forward stroke, the shaper dog hit against the reversing lever causing the valves to alter their positions within the valve Chamber.

Oil under high pressure is now pumped to the left side of the piston causing the ram to perform return stroke. Oil present on the right side of the piston is now discharged to the reservoir.

At the end of the return stroke, another shaper dog hits against the reversing lever altering the direction of stroke of the piston and the cycle is thus repeated.

The quick return is affected due to the difference in the stroke volume of the cylinder at both ends. The left-hand end being smaller due to the presence of the piston rod.

As the pump is a constant discharge one, within a fixed period, the same amount of oil will be a pump into the right or to the left-hand side of the cylinder. This will mean that the same amount of oil will be packed within a smaller stroke volume causing the oil pressure to rise automatically and increasing the speed during the return stroke.

The length and position of stroke are adjusted by shifting the position of reversing dogs.

The cutting speed is changed by controlling the throttle valve which controls the flow of oil. When the throttle valve is lost the excess oil flow cut through the relief valve to the reservoir maintaining uniform pressure during the cutting stroke.

Credit:- https://www.theengineerspost.com/shaper-machine-mechanism/