SU442632A1 - Method of tube production - Google Patents

Description

The invention relates to the field of butt welding of products, such as pipes, I-beams, etc., and can be used in the design of appropriate welding equipment.

Known methods of continuous butt welding of pipes and other products by heating the edges to be welded (radio frequency, induction, resistance welding, etc.).

Lime is a method of high-frequency (radiofrequency) welding, which consists in converging at a sharp angle. The scrap edges to be welded are heated with a high frequency current flowing along the edges in opposite directions, squeezed in a compressing stand and welded. This method is widely used in the manufacture of welded pipes from ferrous and non-ferrous metals as well as in the production of other products with a long weld seam.

However, due to the discrepancy between the forces of prilol epiys to the edges for

the bending of the elements of the workpiece in the formation of the desired angle of convergence of the edges, and the efforts required for the draft and welding, the quality of the welded joint deteriorates significantly, and irreducible edge displacements appear.

The forces required to bend the workpiece elements transmitted through the seam are much higher than the forces required for welding.

The purpose of the invention is to improve the quality of welding.

To do this, according to the proposed method, the welded pipe, after a welding point at some distance from the axis of the compression VSK1KV, is unclamped from the inside by a force unloading from the efforts needed to bend the edges of the workpiece to form the required angle of convergence. After the application of the decompression force, the weld is subjected to compression by the force unloading it from the tensile force arising

the divergence of the previously curved edges of the workpiece.

FIG. 1 shows schematically the bending of edges by a known method of pipe welding: FIG. -2 - the same, according to the proposed.

The essence of the method is as follows.

The excessive force of the bending of elements, the workpieces, is perceived not by weld edges, but, for example, by rolls of the inner mandrel (when welding pipes). By adjusting the magnitude and location of the force application, it is possible to obtain any pressure at the joint necessary for welding.

According to the proposed method (see Fig. 2), the welded seam is partially unloaded from the action of force N by unclamping the welded pipe from the inside by forces S at some distance from the axis of the compressing rolls. As a result, it is no longer the force N that acts on the seam, but the force N, which is the difference N and Ng

Thus, by adjusting the pressing force P and unclamping the MS, any force of N 2 precipitation can be obtained. This makes it possible to make the parameters of pipe slump and welding conditions independent and optimal, which is especially important when welding pipes of both small and large sizes x significant rigidity. The welding according to the proposed method is carried out as follows. . Krom1si 1 and 2 pipe billet with a specific V-shaped gap between them is heated to the welding temperature, for example, high-frequency currents. Passing through the welding unit, they are simultaneously subjected to the action of a compressing and unclamping device 3 and 4. As a result, the edges to be welded are under the action of only welding pressure, unloading in whole or in part from bending forces in the weld center.

After welding, which takes place at the maximum approaching of the edges being welded, they tend to disperse under the action of the unclamping forces N2, which can negatively affect the quality of welding of the end sections of the products of measuring length. To avoid this, after the efforts of expansion, the seam is repeatedly subjected to compression by the clamping device 5 with the force Ni, unloading it from the tensile forces resulting from the divergence of the previously bent edges of the workpiece.

Claims (2)

1. A method of manufacturing pipes, mainly of large diameter, by high-frequency welding, in which the welded edges when moving the workpiece are brought together at a certain angle, heated, squeezed and welded, in order to increase the quality of welding, by some distance from the axis after the welding point, the welded pipe is compressed from the inside by a force unloading from the forces necessary to bend the edges of the workpiece to form the required angle of convergence of the edges, 2. Method pop. 1, which is also distinguished by the fact that, after the application of unclamping forces, the weld is subjected to compression by a force that unloads it from the tensile forces arising due to the divergence of the billet edges previously bent.