SU764765A1 - Apparatus for welding straight-seam tubes - Google Patents

Description

I

The invention relates to pipe electric welding production and to the improvement of devices for welding of direct-flow pipes.

A device for welding straight pipes, containing a mandrel with a roller holder and a welding cage, is known, while the roller cage is installed directly behind the welding cage and supports the welded edges of the pipe at the draft, reducing the probability of mixing of the edges 1.

However, the known design does not allow to reduce the draft pressure to the value required by the welding technology.

Closest to the present invention is a device for welding direct-flow pipes, comprising an inner mandrel with expanding roller gauges and a welding stand with squeezing rollers (2).

A disadvantage of the known device is that it is possible to obtain a high-quality welded joint due to the compressive forces that occur when the required angle of convergence of the edges and acting on the welds are formed.

Ch. No. ZD№; and y: IDE Ze

The purpose of the invention is to improve the quality of the weld by unloading the latter from the compressive forces that occur during the formation of the convergence angle of edges.

This goal is achieved by the fact that, in a device for welding straight pipes, the expanding roller gauges of the inner mandrel are offset from the vertical plane of the welding stand passing through the axis of the compression rollers, by a distance of 0.05-0.3 times the diameter of the pipe being welded in the direction of movement of the product.

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FIG. Figure 1 shows schematically a device for welding straight pipes, a general view; in fig. 2 and 3 are examples of the development of an expanding roller caliber of the inner mandrel.

15

The device contains a voyage mandrel 1 with supporting rollers 2 and cornering rollers 3, as well as a welding stand made in the form of inductor 4 and squeeze rolls 5.

At one of the ends of the mandrel, located 20 nom behind the plane of the welding stand at a height of 0.05-0.3 of the pipe diameter, a roll gauge, made in the form of two hinges, is installed along the molding.

Claims (2)

a tess ss "saEseM es" fe B (connected sleeves 6 and 7 and rolls 8. Between the sleeves there is a mechanism 9 (for example, pneumohydraulic) to create a constant force of pressing the rolls 8 to the pipe 10. In the case of a constant value of draft during welding The expanding roll gauge can be made as one-piece cage II and rolls 8 set to a specified size (see Fig. 2). The maximum compressive force in the seam (upsetting pressure) for high-frequency welding is located behind the plane of the welding stand. up to the cross section of the maximum squeezing mustache The diameter is determined by the diameter and thickness of the pipe wall, the mechanical properties of the material, the angle of convergence of the edge, etc. The specified range of location of the expanding roller gauge ensures its operability in extreme cases, for example, at maximum and minimum ratios of diameter and wall thickness used in practice.The approach of the expanding roll gauge to the plane of the stand outside the specified range in almost all cases leads to a sharp decrease in the efficiency of its work and, moreover, Surely increases the load on the rolls. Installing expansion roll gauges further than 0.3 of the pipe diameter from the stand of the stand in any case leads it from the zone of compression to the zone of tensile forces in the seam. In this case, the caliber has a harmful effect on the seam, which can even lead to its rupture. As is known, with a stable welding process, the angle of convergence of the edges is at least 4-5 °. The reshaping of the sections of the workpiece adjacent to the edges, while creating such an angle of convergence, causes considerable compressive forces in the groove directly behind the plane of the welding stand. These forces are an order of magnitude higher than those required by the welding technology. For example, when welding pipes of 720 mm with a wall thickness of 9 mm (high-frequency welding mill "530-820 ChTPZ), the slump force is 25-30 tons, while to obtain a quality weld of metal of such thickness (according to the results of E. E. Paton of the Academy of Sciences of the Ukrainian SSR) it is necessary to apply an effort of 2.5-3 tons. The proposed design of the mandrel allows bending the edges of the billet during welding necessary to create the required angle of convergence of the edges between the three structural elements, the cornering rollers 3, and the rolls and welding cage 5 and rolls 8 expanding caliber. Under these conditions, the proportion of compressive forces on the seam depends on the ratio of the perimets () of the welding stand and the expanding roll gauge and can be set using the appropriate exhibition of rolls 8 of the expanding gauge. In the process of welding, the degree of heating of the edges can be reduced, for example, the amount of sludge decreases, the perimeter of the pipe behind the welding stand increases, and the pressure of the rolls of the expanding 8 gauge on the inner surface of the pipe decreases, which leads to an increase in the draft pressure. If the expansion roll gauge is designed as shown in FIG. 3, the pneumatic-hydraulic mechanism 9, which provides almost constant pressure on the sleeves 6 and 7 with a stroke of 3-4 mm, expands them and increases the perimeter of the expanding roll gauge, maintaining the specified pressure of the rolls on the pipe. The fluctuations of precipitation forces in this case are largely smoothed out. The combination of a relatively large angle of convergence at and a desired slump pressure makes it possible to make seams of very high quality. Improving the stability of the quality of welds along the length will make it possible in the near future to manufacture domestic-purpose products, such as large-diameter pipes for gas and oil pipelines, using high-frequency welding. Apparatus of the invention for welding of straight seam pipes, comprising an inner mandrel with expanding roll gauges and a welding stand with squeezing rolls, characterized in that, in order to improve the quality of the weld by unloading the latter from the compressive forces arising from the formation of the corner of convergence of the edges, the expanding roll the gauges of the inner mandrel are offset from the vertical plane passing through the axis of the squeeze rolls of the welding cage by a distance of 0.05-0.5 of the diameter of the pipe being welded in the direction of movement Cereal. Sources of information taken into account in the examination 1. USSR author's certificate number 356010, cl. In 21 of 37/08, 1969. 2. USSR author's certificate No. 219045, cl. At 21 from 37/08. 1967 (prototype). FIG. 2 Fig.Z