SU1360844A2 - Method of producing welded tubes - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used on continuous pipe welding units. The aim of the invention is to improve the quality of welded pipes by stabilizing the processes of forming and welding pipes. In the manufacture of pipes, a continuous strip 8 after alternating plastic bending in tension device 1 is rolled in rolls 4 of stand 3. Rolling is performed with rear tension relative to stand 3. Tension of strip 8 automatically adjusts the change in parameters of rolling and plastic bending-strip, preventing formation of crescent when rolling a strip with transverse thickness variation. 1 il. (L 00 a: about 00 NU gh

Description

The invention relates to the processing of metals by pressure, can be used on continuous pipe welding units and is an improvement of the method according to the authors. St. No. 1301516.

The aim of the invention is to improve the quality of welded pipes by stabilizing the processes of forming and welding.

pipes .;

The essence of the method is that the alternating plastic bending of the strip in the-vertical plane with tension simultaneously with the bend in the horizontal plane and subsequent rolling allows both to correct the original crescent of the strip and to prevent the crescent induced during rolling. In this case, the type of deformation effects on the strip (multicyclic bending and rolling) are interconnected by tension. In the process of multicyclic bending of a strip having a transverse thickness variation of a trapezoidal cross section, the width of the strip changes both deformation and tension.

A change in the tension across the width of the strip (defined relative to the rolling stand) leads to a change in the critical rolling angle along the length of the roll barrel, which, in turn, affects the speeds of the longitudinal movement of the strip edges.

The drawing shows the implementation of the method.

The alternating bending of the strip is carried out in a tensioning device 1 containing non-driven rollers 2, the axes of which are located in the same horizontal plane. The strip is rolled in a rolling stand 3 containing a work 4 and support 5 rolls.

Then, in the forming mill 6, there are realized 45 non-drive rollers 2, the axes of which

are molded, and in the welding unit 7 are located in one horizontal

welding edges formed polo-plane. The diameter of the rollers 140 mm

8. flange flange height 15 mm, distance. When alternating plastic bending with tension, strip B is elongated. If strip 8 enters the line of the pipe-welding unit, having a trapezoidal cross-section (one edge is thicker than the other), then with multi-cyclical bending in the vertical the plane is thicker, the edge gets more deformation from the bend (where h is the thickness

five

0

five

0

five

0

stripes; D is the diameter of the tensioner roller).

In this case, from the side of the thicker edge of the strip, the retarding effect of the tensioning device 1 increases, consequently, the size of the rear one relative to the rolling tension stand increases. An increase in the latter leads to a decrease in the critical angle -V when rolling the strip in the rolling stand 3 and the speed of the entry of the strip into the stand 3. As the thicker edge gets more elongation and its speed decreases, the passage time of both edges is faulty. Thus, in the tensioning device, the transverse strip thickness variation decreases (the thickness of the edges is equal to the width of the strip to the left and right), and in the rolling stand 3 the irregularity of strip reduction across the width decreases, which leads to the prevention of curvature of the strip in the horizontal plane.

If in some parts of the strip the initial crescent occurs, then in the flanges of the rollers 2 of the tension device 1 it is corrected due to bending in the horizontal plane. In this case, the strip is in a plastic state due to alternating bending in a vertical plane with tension. The bending of the strip in the horizontal plane occurs when the flange of the rollers 2 is applied to the convex part of the crescent strip.

Example. In the manufacture of a pipe of 60x3 mm in size from a strip of 184x3.2 mm in size, alternating plastic bending of the strip is carried out in a tension device 1 containing

50

55

between the shoulders (the length of the working part of the roller) is 185 mm, the distance between the rollers and the axis of the rollers 200 mm. The rolling strip is produced in the rolling stand 3 with work rolls 4 with a diameter of 150 mm.

The diameter of the support rolls 5-500 mm.

In a tensioning device, a continuous, butt-welded from individual strip rolls, strip 8 is subjected to plastic alternating alternating bending in the vertical plane, at the feasibility

For a strip with a thickness of 3.2 mm, power consumption is about 2.5 kW. This power is expended by the rolling stand, which pulls the strip through a tensioning device. Consequently, tension is developing in the strip that is posterior to the rolling stand.

With a lack of transverse thickness, the tension and deformation of the strip are uniform in width. In this case, the plastic tension coefficient, 2, the elongation of the strip in the tension device is 2.5%.

When a strip with a trapezoidal cross section passes through the tension device (let the left edge be thicker than the right, 3 mm,, 2 mm, where h is the thickness of the left and right edge, respectively; the deformation from the bend of the left edge is greater than the right, and transverse The strip thickness decreases 2 mm, 15 mm. The cross thickness variation decreases from 3.125% to 1.56% (two times), which ensures that there is no curvature of the strip during rolling. At the same time, the tension from the left edge is greater than from the right (, 03), and the speed of passage of the left chrome and correspondingly smaller than the right (the critical angle for rolling by the left edge is reduced to 0.02 atm ").

In the presence of the original sickle-shaped strip, its correction occurs due to the bending of the strip in a horizontal direction O. Golovach

Compiled by E. Vetrova Tehred M. Khodanych

, Order 6178/13 Circulation 731Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Noah plane in the flanges of the tensioner rollers. The power expended in correcting the rib curvature of the strip from 30 mm to 2 mm per 1 m of the strip length is 2.5-3.0 kW.

In the rolling stand 3, the strip being rolled with rear tension is crimped. In this case, this compression was about. four%. Total stretching of the strip in the tensioning device and the rolling stand is 6.5%.

Then, in the molding mill 6, a strip is formed into a pipe billet, and in the welding unit 7 a workpiece is compressed and the edges are welded.

When using the proposed method, a strip enters the molding mill without crescent and transverse thickness variation. The tension of the strip in front of the forming mill is either absent or has a constant fixed value, which increases the stability of the processes of forming and welding pipes.

Claims (1)

Invention Formula Method for the production of welded pipes, by bus. St. No. 1301516, which means that, in order to improve the quality of welded pipes by stabilizing the processes of forming and welding pipes, after alternating plastic bending of the strip in the vertical plane with simultaneous bending in the horizontal plane, rolling strip with back tension. Proofreader V. But ha