Process flow for production of welding elbow

Welding elbow production process, if the long radius of the elbow, you must first select specifications, put forward the tube material. Spread ratio, through theoretical calculation, the general expansion rate of 35% - 33%, and push back. The diameter rate of short radius 219mm general expansion to 50%. selected raw materials, according to the specifications of elbow material, and then consider the radius of curvature, for example, elbow 90 degrees, can be calculated by how long the material can be processed by the 90 degree bend curvature. It can be calculated by theoretical calculation, and then cut off with the length of the length. Finally, the material pushing system. You may have seen the machine, 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 a support pipe section to penetrate mandrel material, one behind the arch frame will be fixed mandrel. There is a car in the middle, some of the car through the hydraulic transmission, and some through mechanical transmission that screw drive, and then push the car forward. Pushing the tube along the mandrel car ahead, there is an induction coil outside the mandrel, the pipe is heated, heated, and then push the tube under the car, is a good process. After the push, the elbow to the thermal state of plastic. Because some elbow handled 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.

The plastic mold is actually a press, to have a set of mold, 2.5 arc, up and down each one. After shaping the outer diameter of the finished product has reached the size requirements. The wall thickness of the material is controlled by the wall thickness. Wall thickness of elbow and pipe are the same, are in the process of pushing + 12.5%., under normal circumstances, wall thickness should not be changed, but if because of reasons, some places will reduce wall phenomenon, so the general material, wall thickness to add some allowance, such as the elbow is 8.18mm the wall thickness is generally provided about 8.5mm tube to prevent the push system due to local reduction of thick and super bad. After the whole shape, the outer diameter and wall thickness of the elbow reach the requirement. The finishing process, after shot peening, the elbow of the inner and outer surface of iron oxide removal, the ends of the groove processing for welding. After checking, playing steel word, spray paint, packaging and other processes, you can leave the factory.

The above is 24 "below elbow production method of material with seamless pipe as more than 24," after more than 600mm, the maximum elbow in 2.032 meters ~2.80 meters, is done with the steel plate. The steel plate according to the requirements of the cut into the material, like UOE molding, stamping die stamping into a round. There are two halves and then assembled and welded. Because of the existence of the welding seam, so we should carry out nondestructive testing. Due to the existence of welding stress, the heat treatment should be carried out. Welding elbow more than two processes: one is the detection, one is the heat treatment. Other programs the same.

Three links of the production process is also basically the case. According to the three different specifications for the next. Sand blasting before the first, to the surface of the surface before the formation of the oxide scale removal. It is formed by hydraulic bulge forming method. Have the mold, the mold base is straight, above has the flange hole. The pipe into pipe, fixed by the hydraulic cylinder, on both sides of the filling liquid inward bulging, the tube is squeezed into a convex shaped bulge, removed from the place again, also hit into the groove. It must be shot through two times. Because of the machining process, there is work hardening, so the heat treatment is also required. The production process of pipe fittings is the case.

Need to explain is cut off, the required pipe cutting machine, and sawing machine, some of the specifications on the flame cutting. No matter what method is used, we must ensure that the tube end straight, no burr, the rule is accurate. Otherwise, in the process of pushing, the tube end is easy to break. Technical problems in this area, in the tool design. If the design is good, push out of the type is more positive, basically meet the requirements. Some waste more, mainly due to the problem of tools. Design is mainly based on experience. Also need to have the experience of the workers continue to repair, to put into normal use. Tool is very important. In addition, the system is now using hydraulic pressure method. Hydraulic pushing speed adjustable. Big elbow and small elbow pushing speed is different, the heating speed is not the same. In addition, the deformation of the hydraulic system is relatively stable. Now the mechanical method is not a lot, heating is also important. Old fashioned heating uses a gas stove, heating pipes, and now to switch to if heating. After about 70s this heating mode of our country just cross the border. This method is relatively good temperature control, heating is more uniform. Heating temperature control by regulating coil number. If burn Tsui, not too good control. In addition to pre heating before the system. After the fixed mandrel preheating pipe. The use of intermediate frequency heating technology is a great progress in the production of elbow, the yield and quality are greatly improved.