Introduction:
Hydraulic pipe bender is used for bending almost all types of pipes except conduit pipes. The pipe benders are ideal for pipe fitters and general engineering applications. The bending capacity of hydraulic pipe bender varies as per the strength, power and performance. They are designed with extra power for large jobs and are suited for various types of bending and forming operations.
Construction:
The hydraulic pipe bender setup consists of a hydraulic jack, die of required angle, supporting blocks, pins for supporting blocks, and plates of required shape and size which are drilled with holes of required diameters. A lever having a cut slot at one end is used to loosen or tighten the pin of the jack and also to move the piston up or down by pimping action. The whole assembly is mounted on a base plate, and the plate having drilled holes is attached to the base plate by welding.
Working of Hydraulic Jack:
This system uses a piston type hand pump to power a single hydraulic cylinder and the operation is as explained:
A manual force is applied at a point A of handle ABC, which is pivoted about point C. The piston of the hand is pinned to the input handle at point B. The hand pump essentially consists of a cylinder containing a piston, which is free to move up and down. The piston and rod are rigidly connected together. When the handle is pulled up, the piston raises and creates vacuum in the space below it. As a result the atmospheric pressure forces the oil to leave the tank and flow through the check valve 1 and this is the suction process, where a check valve is a component that allows the fluid flow in only one direction as indicated by the arrow.
When the handle is then pushed down, the oil is released from the hand pump and flows to check valve 2 which enters the bottom of the load cylinder. The load cylinder is similar in construction to the pump cylinder and contains a piston. From Pascal’s law we know that the pressure acting on the load piston equals the pressure generated by the pump below its piston. Thus each time the input handle is cycled up and down; a specified volume of oil is ejected from the pump to raise the load cylinder to a given distance against its load resistance. The below valve is hand operated valve which, when opened allows the load to be lowered by bleeding oil from the load cylinder back to the oil tank. It should be noted that oil enters and exits from each cylinder at only one end.
Working:
The whole assembly is first placed on a flat surface and the pin of the jack is tightened. The piston of the jack is retracted with the help of a lever; the die is mounted on the piston and the supporting blocks are placed in between the two plates using a pin, which is for the support.
The holes in the plate are provided so that the supporting blocks can be adjusted as per the requirement. If the diameter of the pipe which is to be bent is more than the supporting blocks, then the positioning of the block will depend on the diameter and the angle to which the pipe has to be bent. As the die and the piston reciprocates, the pipe which is placed on the support will be pushed towards the supporting block and the further pushing of the block will result in bending of pipe. After the desired angle of bending is attained, giving 3 revolutions to it loosens the pin of the hydraulic jack. A special care should be taken while tightening and loosening the pin. When the pin is half loose, the piston shouldn’t be pressed which will apply pressure on the seals and they may fail and leaking of oil might occur, which is undesirable
