SU1479234A1 - Method of resistance fusion butt welding - Google Patents

Abstract

This invention relates to flash butt welding technology. The purpose of the invention is to simplify the technology and equipment for flash butt welding. The parts are melted and precipitated with a predetermined allowance. During the welding process, the joint zone is protected from contact with air, and the protection is carried out by installing guard plates on the connected ends. The initial distance between the plates is set equal to the reflow allowance and the draft increased by the amount of reinforcement formed on the surface of the parts after the settlement. The height of the flaps is set at least three reflow allowances. In order to increase the service life of the flaps, the latter are cooled. The method allows to protect the connection area from oxidation in the absence of expensive protective chambers. 1 hp f-ly, 2 ill.

Description

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This invention relates to flash butt welding of parts, preferably with a large cross section.

The aim of the invention is to simplify the technology and equipment in flash butt welding.

FIG. 1 shows pipes with installed protective shields prior to welding; in fig. 2 - the same after welding.

The drawing shows the welded pipe 1; bottoms 2; shield 3; option plate 4 with a cooling system; Days - allowance for fusion and draft; - the amount of reinforcement on the surface of the part after precipitation.

The physical essence of the described technical solution is that the concentration of the emission of sparks and splashes of molten metal in a narrow space around the reflow zone drastically reduces the flow of free oxygen.

into the spark gap due to the fact that oxygen is bound by the molten metal and its vapors, continuously flowing into this limited area during the melting process. Thus, the level of oxidation of the molten metal at the ends of the parts during the welding process is significantly reduced.

The method is implemented by installing gas-tight shields on the parts to be welded. In order for the shields to best contribute to the process of joining parts, the distance between them should be set equal to the allowance for melting and draft, since these details are shortened during the welding process, plus the amount of reinforcement on the surface of the parts after settling. This is necessary so that the plates are not deformed during the precipitation process and can be reused.

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The height of the shields should be set at least three reflow allowances. This value was experimentally determined as optimal when welding parts from low alloyed steels used in structures of responsible purpose. Reducing the height of the plates above the surface of the part compared to the optimum value reduces the stability of the properties of the joints. The upper limit of the height of the plates in terms of technology is not limited, but it should be chosen taking into account the design features of the welding installation. If the pipes are welded by K-700 in-line welding machines, then there are no obstacles to the installation of shields on the outside of the pipe. When welding with external machines, such as K584, the height of the plates should be coordinated with the structural elements of the machine that are located in the space between the current-carrying shoes.

The proposed method allows the connection zone to be protected from oxidation with no less effect than the prototype, in the absence of expensive unreliable protective chambers. Reduces the time to install the protective device, increasing its durability.

The supply of guards to the cooling system minimizes the time required to clean them from sticking metal splashes, as the guards self-clean the heating-cooling cycle.

Example. Welded pipes 0 219ХЮ mm by machine K.584. Before welding, bottoms 2 are installed in the pipes 1 to prevent air from entering through the flow section. The bottoms 2 are made of a gas-tight material and set independently or in conjunction with an internal reamer. The flaps 3 are installed on the outer surface of the pipes 1. Reflow and draft allowance for welding of pipes 0219ХЮ mm To ,,, mm. The magnitude of the reinforcement on the surface is coarse. Thus, the initial distance between the plates is House -) - -) mm. The height of the plates is set to 3 mm. After that, the pipes are installed in the welding machine and welded.

Mechanical testing of welded joints showed complete compliance of mechanical properties with SNiP requirements with high stability of indicators.

The monitoring of the implementation of the method is carried out visually and with the help of a measuring tool, as well as by monitoring the parameters of the welding mode and the results of the mechanical tests of the welded joints.

The proposed method greatly simplifies the flash butt welding technology using protection of the joint zone from contact with air oxygen, and also simplifies the equipment for creating a protective closed volume.

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Claims (2)

1. A flash butt flash welding method, in which, before welding, the joined ends of the parts are placed in a confined space, protecting the joint area during welding from contact with air, and then they are melted and deposited with a specified allowance, characterized in that simplification of the method and the equipment that implements it, a limited space is created by installing, on the connected ends, parts of the plates, the initial distance between which is set equal to the allowance for melting and draft, increased by the amount of reinforcement formed on the surfaces of the parts after precipitation, with the height of the flaps being set to at least three reflow allowances. 2. A method according to claim 1, characterized in that, in order to increase the service life of the plates by reducing the amount of molten metal spatters sticking during the melting process, the plates are cooled. one / / 7 S ъ S 7 / s / / / /// / / / at figl h