First of all, in order to elbow as an example, if a long radius elbow, such as the use of the pipe, the first selection of specifications, the tube material. Expanding rate, through theoretical calculation, the general expansion rate of 33% - 35%, but pushed back. The average diameter of the short radius 219mm is 50%.

After the selection of raw materials, according to elbow specifications, and then consider the curvature radius, for example, 90 degrees of elbow, through its curvature can be calculated how long the material can be processed out of 90. Can be calculated by theoretical calculation, and then cut off with the length of the fixed scale. Finally, the material pushing system. Push the machine you may have seen, the actual is very simple.

It is a horn shaped mandrel or mandrel, the mandrel is changed from thin to thick, push the process is a process of expanding with bending. Behind the support, the pipe section to penetrate mandrel material, one behind the arch frame will be fixed mandrel. In the middle of a small car, the car through the hydraulic transmission, some through the mechanical transmission that the screw drive, and then move forward to push the car. Wheeled the pipe along the mandrel to go forward, outside the mandrel has a coil, the tube heating, heating is good, then the handlebar pipe pushing, processing a. After the push, the elbow should be carried out in this heat.

Because some elbow is not treated properly, it will be distorted, which is not allowed. In addition, after the pusher is generally a front end outer diameter to be reshaped by large, plastic mold. Plastic mold is in fact a press, to have a set of mold, 2.5 arc, the upper and lower. The outer diameter of the finished product can reach the size of the finished product. The wall thickness is controlled by the wall thickness. The wall thickness tolerances of elbow and pipe are the same, and are 12.5%.

In the process of pushing, the normal circumstances of the wall thickness should not be changed, but if the tool reason, some places will occur, so when the general material, the wall thickness to add some allowance, such as elbow is the wall thickness of 8.5mm, generally put 8.18mm around the tube, prevent in the push system due to the partial thickness and poor. After the whole good shape, the outer diameter and wall thickness of elbow are achieved. Below are finishing industry and trade order. After the shot peening treatment, the inner surface and the outer surface of the elbow of iron oxide removal, the ends of the groove processing for welding. And then through the inspection, playing steel, paint, packaging and other processes, you can leave the factory.

Above 24 "following in a seamless steel pipe as the raw material, the processing method of elbow, more than 24" after that of more than 600 mm, the maximum elbow between 2.032 meters ~2.80 meters, is made of steel plate. The steel plate according to the requirements of cutting into material, like UOE molding, but also through the punch punch into a circular. There are two halves and then split, welding. Because of the presence of the weld, it is to carry out nondestructive testing. Because of the existence of welding stress, the heat treatment is also carried out. Welded elbow more than two processes: one is the detection, one is heat treatment. Other procedures.