The important elements of a hydraulic shaper are
- Constant discharge hydraulic pump
- Pressure relief valve
- Four way control valve
- Cylinder with piston
Hydraulic liquid is pumped by a constant discharge pump into the direction control valve. It has four ports and three stages. If the pressure goes beyond desired limits, the same is released by the pressure relief valve.
The liquid reaches the right side of the cylinder through the inlet E and outlet A of the valve. Due to the pressure of the liquid, the piston moves towards left. The toolhead moves forward to perform the forward cutting stroke. The liquid on the left side of the piston is sent back to the reservoir through B and P.
Due to the change of position of plunger inside the valve, the liquid reaches the left side of the cylinder through the inlet E and outlet B. Piston moves towards right. The toolhead moves in the opposite direction and this movement is known as the return stroke. The liquid on the right side of the piston is sent back to the reservoir through A and P.
Quick Return of the Ram
Due to the change of stroke volume of the cylinder during forward and return stroke, the piston returns at a faster rate.
The stroke volume of the cylinder during return stroke is comparitively smaller than during forward stroke due to the presence of the piston rod. So, the pressure increases automatically to push the piston and the toolhead at a faster speed during return stroke.