The forming process of seamless pipe fittings elbow

Keywords:seamless pipe fittings, elbow
Seamless pipe fittings elbow is the main connecting part of pressure pipeline. At present, the production of seamless elbow has cold push, hot push, stamping and other methods, and the cold push process still occupies an important position in elbow production. Although the cold push elbow has outstanding advantages, but the deformation law is more complicated and the process is difficult to control, it is very necessary to study the cold forming process of the elbow, improve the cold push elbow technology, and provide technology for the development of the elbow production process. stand by. 

The simulation analysis of the cold push process of the elbow was carried out, and the results obtained by the finite element simulation were compared with the actual production. The reliability of the finite element simulation was confirmed, and the optimized tube blank size determination method was used to determine Φ273×8. The elbow blank size was optimized and the feasibility of using a reverse thrust simulation to obtain the tube blank size was demonstrated. Using the orthogonal test method, the optimized parameters of the cold push elbows of Φ219×8 and Φ508×8 are obtained. The cold-formed elbow was measured and the forming results were analyzed. The parameters such as the uniformity of the wall thickness of the elbow and the ellipticity of the end face were tested. The parameters of the elbow were tested to meet the standard index of the pipe fittings. With the continuous development and advancement of industrialization, the use of pipelines has played an increasingly important role in various fields and industries. In particular, the demand for pipe fittings and components in the power and petroleum industries is increasing, and the requirements for pipeline equipment are constantly increasing, which inspires the pipeline industry to continuously carry out technological innovation. With the continuous advancement of industrial production, the development of forming technology for pipe fittings is particularly important.

Pipe fitting forming is a processing technique for pipe fittings required in the production process by means of plastic deformation. In order to meet the various needs of the produced elbows, the skilled workers and many scholars have carried out a large number of experiments and research, and constantly carry out technological innovations on the processing technology of the elbows, so that the processing technology of the elbows is perfect. The goal of simulating the bending tube forming technology is an important part of improving the production technology of the elbow.

The hot push forming technology uses the induction heating method to heat the tube blank to plasticize the material, and then uses two-step hydraulic push to bend and expand the diameter under the action of the core rod inside the tube blank to form a larger diameter than the tube blank. A forming method of the elbow. The hot push forming elbow is suitable for continuous production, has a fast production rate, and can produce elbows of different specifications. In the existing elbow forming method, it is a forming method with low production cost, and thus is widely used in bending. The production of the head. However, when forming the carbon steel elbow, the internal horn core rod has a higher red hardness requirement, and the heating temperature of the elbow during the forming needs to be controlled between 750 °C and 950 °C.

The elbows produced by the hot push process are beautiful in appearance, good in forming quality, relatively uniform in wall thickness, and very suitable for continuous large-volume production, so when forming alloy steel, stainless steel and carbon steel elbows like the hot push forming process is usually used. When using the hot push forming method to form the elbow, it is very important to use which heating method. Among the heating methods currently applied, there are mainly three heating methods: induction heating, reverberating furnace heating, and flame heating. In actual production, a suitable heating method is usually selected according to product requirements and actual plant conditions.

The so-called press forming is a method in which a tube blank having an inner core is directly used to press and press an elbow by using a mold. At the beginning of the production of seamless elbows, the stamping method realized mass production of elbows and was widely used in the production of elbows. The stamping forming method has certain disadvantages, that is, the forming quality of the elbow formed by press forming is not good, the wall thickness deviation of the elbow is large, and the appearance of the formed elbow is not beautiful, and the mold required when forming a large-sized elbow is required. The cost is also very high. Therefore, in today's elbow production, stamping has been gradually replaced by other forming methods. However, in the production of some special specifications elbows, the stamping method is still used.

When the elbow is produced by the stamping method, it is determined whether the cold stamping or the hot stamping is performed according to the actual production requirements and the tonnage of the production equipment.

Extrusion method: a method of forming an elbow by extrusion of upper and lower molds. The elbow formed by this method has good forming quality and the elbow is beautiful in appearance, and is usually applied when manufacturing some thin-walled elbows. However, the extrusion method requires very high precision for the upper and lower molds, and the required wall thickness deviation is also small.

Welding method: a method in which a slab is pressed out of a half of a pipe body by a die, and then two half pipes are welded to form a complete elbow. The elbow manufactured by the welding method needs to be processed multiple times, and the forming quality is poor.

Through the introduction of different elbow forming methods, it can be seen that each forming elbow method has its own application range, efficiency of forming elbow and quality of forming elbow, but each has its own production. Advantage. When forming the pipe fittings, it is necessary to find a forming method capable of rapidly producing the required qualified elbow according to the current actual situation, to ensure the fundamental production efficiency.

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