SU1673237A1 - Welding unit of continuous-action tube-welding mill - Google Patents

Abstract

The invention relates to the processing of metals by pressure and welding, and can be used in the manufacture of welded straight welded pipes by arc or plasma welding at high speeds by several successively located arcs. The purpose of the invention is to increase the welding speed. When the supporting pairs of rollers 4 and the holding rollers 3 are located at an optimal distance from each other, the workpiece entering the welding unit has a stable geometry, and the pipe coming out of the welding rollers 2 is kept from tensile stresses, thereby increasing welding speed and quality of welded pipe joints. 1 il.

Description

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The invention relates to the processing of metals by pressure and to welding, and can be used in the manufacture of welded direct welds with coarse arc or plasma welding at elevated speeds by several successive arcs.

The purpose of the invention is to increase the welding speed in the manufacture of pipes by stabilizing the relative position of the edges of the billet before entering the welding gauge (creating the required gap between the edges along the required length of the welding center) and creating conditions for using multiple or plasma welding in series spaced arcs.

The essence of the invention is that the creation and stabilization of a given gap between the edges excludes defects in the welding zones during the multi-arc process.

Figure 1 shows the structural scheme of the proposed welding unit of a continuous electric pipe welding mill.

The welding unit contains welding sticks 2 installed on the bed 1, which form a welding station. and holding rollers 3 positioned after the welding rollers. 3. Support rollers 4 installed in front of the welding rollers. Each pair of supporting 4 and holding 3 rollers has devices 5 and 7 for indi- vidually adjusting their position in the horizontal plane relative to the longitudinal axis of the pipe . The welding rolls are provided with a device 7 for individually adjusting their position,. also group adjustment in conjunction with supporting and holding rollers.

The welding unit operates as follows.

The formed tubular billet, after it leaves the molding mill, continuously enters the welding unit. The supporting rollers 4 are installed so that between the edges of the tubular billet in them there is a constant gap of the required size for simultaneous heating and melting of both edges with electric or plasma arcs used for preheating and melting of the edges.

With the passage of the billet with the melted edges through the welding rollers 2, the melted edges are compressed

they also carry out the through melting of the edges being welded by the last welding arc with the formation of a weld. The cooling weld after the tube leaves the welding rollers is kept from breaking under the action of tangential stresses with the help of the holding rollers 3.

To ensure that the edges of the tube stock in the support rollers, as well as in the welding rollers and the holding rollers, are parallel and do not diverge between the adjacent pairs of rollers and rollers

5 and rollers, it is necessary to set them at a distance which should not exceed a certain value.

The magnitude of this distance, for example, for steel billets for pipes of 25x1.0 mm; 25x1.5 mm; 25x2.0 mm; 33x1.0; 33x1.5 mm; 33x2.0 mm; 43x1.0 mm; 43x1.5 mm; 43x2.0 mm; 51x1.0 mm; 51x1.5 mm; 51x2.0 mm; 80x1.5 mm; 80x2.0 mm was determined by experiment. For this purpose, molded pipe blanks were used for pipes of the indicated dimensions of 400 mm length with edges welded to one of the ends. The action of any subsequent pair of rollers or rolls imitated a ring

0 clamp moved to different distances from the welded portion of the edges. The presence and size of the gap between the edges was determined with a probe and a caliper.

5It is established that the distance

The adjacent pairs of rollers can be determined from the expression

I KD, where I is the maximum allowable distance

0 between adjacent pairs of rollers, mm;

D is the diameter of the welding caliber, mm; K is a coefficient depending on the size of the diameter of the welding gauge.

For steel strip with D 25-45 mm

5 K 2.8; at 0 50-80 mm K 2.2.

Claims (1)

When using the invention, the geometrical parameters of the workpiece for welding are stabilized, which makes it possible to produce high-quality preheating and melting operations carried out during multi-arc welding. Claims of the Invention Welding unit of a continuous electric pipe welding mill for the manufacture of 5 electric arc welded pipes, including welding rolls mounted on the frame, and retaining rollers located after them, characterized in that, in order to increase the productivity of the pipe manufacturing process, The welding rollers are set to I - the maximum allowable distance at least one pair of rollers supporting between adjacent pairs, mm; rollers, while the distance between adjacent-D is the diameter of the welding caliber, mm; These pairs of rollers and rolls determine-K, a coefficient depending on the magnitude from the expression 20 on the diameter of the welding gauge. I 5K-D,