SU1755990A1 - Method of making composite tubes - Google Patents

Abstract

Use: pipe rolling production. SUMMARY OF THE INVENTION: Cutting after reduction of hollow blanks is joined by ends with the same wall thickness, ranging from 0.8 to 1.2 nominal thickness, and after welding, they are subjected to plastic deformation in inner and outer diameter with compression equal to the difference between the maximum and minimum wall thickness. . 1 il.

Description

The invention relates to pipe production and can be used on pipe rolling units incorporating reduction mills.

One of the ways to realize waste metal is the method of manufacturing a composite pipe, which consists in assembling and butt welding of a short cut and subsequent plastic deformation, according to which short cut pipes are welded and rolled to a smaller pipe size at the reduction mill, after which connections cut out.

A disadvantage of the known method is the necessity of cutting the joints of the scrap after rolling. In addition, it is precisely as a result of rolling that thickened ends are again formed, which are cut.

The purpose of the present invention is to save metal.

The essence of the invention is that the cut is welded with a wall thickness from 0.8 to 1.2 of the nominal pipe wall thickness, the deformation is carried out on the inner and outer diameters with

compression, equal to the difference between the maximum and minimum wall thickness, while in the assembly for welding dock trims with ends having the same wall thickness.

The drawing shows a composite tube prior to calibration.

The method is carried out as follows.

Out of trimming after the reduction mill, which is a nozzle with variable wall thickness, choose nozzles with a wall thickness of 0.8 to 1.2 nominal wall thickness, sorted on the rack so that the ends of the workpieces having the same wall thickness are with one the sides of the rack, then the resulting package is divided into two halves with the help of lifting and transporting equipment, after which those end sections with variable wall thickness, which have the same wall thickness, are welded on stykosvarochnoy machine of known construction, e.g., Type K 315.

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The number of parts to be welded depends on the required length of the composite pipe. After welding, the pipe is calibrated by the inner and outer diameters on the short-adjusting drawing mill with compression equal to the difference between the maximum and minimum wall thickness, straightening on the correct rolling mill, ultrasonic testing on the flaw detector and cutting the ends on the saw.

To test the method, thickened ends going to the pipe were taken after receiving pipes from steel grade 20 at the TPA-140 reduction mill.

The outer diameter of the thickened ends was 57 mm, the wall thickness varied from 3.5 to 5 mm, the length of the parts was 1500 and 1700 mm.

As a result of testing the method, a composite tube with a size of 57x4 mm and a length of 6000 mm was obtained.

It has been established that a pipe obtained by the proposed method from thickened ends according to the requirements of GOST 8732-78 can be used for the manufacture of consumer goods,

By a known method, the pipes were welded with the same wall thickness of 500 and 600 mm, then deformed to obtain a pipe of 1700 mm. After cutting off their ends and welding points, the length of the pipes, which met the requirements of GOST, was 400 mm.

Thus, the use of the proposed method allows to obtain pipes of greater length, which ensures a reduction in metal consumption.

Claims (1)

The invention The method of manufacturing a composite pipe, consisting in the assembly and butt welding of a short trim and subsequent plastic deformation, characterized in that, in order to save metal, weld the trim with a wall thickness from 0.8 to 1.2 nominal pipe wall thickness, the deformation is carried out according to the inner and outer diameters with a reduction equal to the difference between the maximum and minimum wall thicknesses, while during the assembly for welding they join the ends with the same wall thickness.