SU1585031A1 - Roll for filger rolling of tubes - Google Patents

Abstract

The invention relates to pipe production and can be used for hot pipe rolling in pilger mills. The aim of the invention is to improve the quality of the pipe surface. Each of the rolls consists of alternating alternating at least twice gripping areas, described by a curve of increasing radius, and polishing sections, described by a constant radius curve, with an outlet section between them, described by a decreasing radius curve. The radius at the end of the section is 0.91-0.99 of the radius of the previous polishing section. 2 Il.

Description

The invention relates to the processing of metals by pressure and can be used in the hot rolling of pipes in pilger mills.

The aim of the invention is to improve the quality of the pipe surface.

FIG. 1 shows a swath, cross section; in fig. 2 is a diagram of sweep deformation.

In the drawings, the following notation is accepted: 1 - gripping section; 2 - polishing area; 3 - release area; 4 - capture area; 5 polishing station; eleven

- one ,. - according to the length of the sections; R., - distance to the center of the roll at the beginning

site release; R2 is the distance to the center of the roll at the end of the release section. The brook of the proposed roll is constructed as follows.

The rolling part of the brook is divided into sections depending on the distribution of deformation between alternating gripping and polishing surfaces. The curve of the first gripping section is determined from the conditions of the beginning of deformation of the workpiece (seed) and the maximum deformation per roll roll, while the distance from the center of the roll to the curve increases to a value from the center of the roll to the first polishing surface.

cl

00

cl

about

WITH

The curve of the first polishing section is equidistant from the center of the roll, its length is determined by the degree of metal drawing in the first gripping section. This is followed by an outlet section, defined by a curve, the distance to which from the center of the roll decreases from a value equal to the distance to the first polishing area to a value of 0.99-0.91 of this distance, the length of the release section equal to the length of the previous polishing area. Then follows the second gripping section, which goes along a curve, the distance of which from the center of the roll increases to the magnitude of the distance to the second polishing section, which, if a finished pipe is produced on it, is determined by its dimensions in the bulk state.

The use of a roller with alternating gripping and polishing sections ensures a fractional deformation along the length of the deforming section of the brook of the piligrim roll. The presence between the previous polishing section and the subsequent gripping section of the additional section of the output stabilizes the deformation mode, since it prevents the backpressure in the subsequent section of the grip when changing the feed of the billet or the mass of the specified metal to the first crimping section. ki (sleeves), which allows to obtain an increase in the quality of the pipe surface. In addition, the presence of additional release between the deforming sections facilitates the longitudinal movement of the metal relative to mandrel pilger mill, which has a special effect when rolling on cylindrical mandrels, providing a reduction in the longitudinal difference in the thickness of the finished pipe.

The execution of the discharge section along the curve, the shortest distance from which to the center of the roll is 0.99-0.91 distances from the curve of the previous polishing section to the center of the roll, is determined by the conditions of filling the stream in the discharge section. At a distance from the center of the roll to the curve of the outlet area greater than 0.99, the backwater in the subsequent section of the stream limited by the gripping surface cannot be removed, which leads to its overflow with metal, an increase in thickness and a formation of whiskers on the pipe surface. With a distance from the center of the roll to the curve of the outlet section, less than 0.91 distance to the previous polishing surface, there is a risk of loss of the longitudinal stability of the pipe at the outlet area, which is accompanied by the formation of transverse folds on the pipe surface and can cause an emergency stop of the rolling process.

As an example of a specific embodiment, consider the use of the proposed roll in the manufacture of pipes of 245 to 9.5 mm in size on an injection molding machine with a pilger mill. The rolling part of the roll consists of two gripping sections and two polishing sections alternating with them, passing along a curve, the distance to which from the center of the roll is 285 and 326 mm, respectively. Between the first polishing section and the second gripping section there is an output section, the distance of which describing the curve from the center of the roll varies from the value at the beginning of the section, equal to the distance to the first calibration section - 285 mm, to the value at the end of the release equal to 0.97 the same distance is 276 mm. When rolling a pipe from a 390 x 70 mm liner, the liner section is deformed, corresponding to the metal feed per roll of 22.5 mm, in the first roll gripping section to 340 mm in size, which corresponds to the change in distance from the roll center to the gripping surface from 260 to 285 mm. Then the same portion of the liner is rolled in the first polishing portion, the distance from the center of the roll is 285 mm. Then, the sleeve section enters the discharge section, where it is lifted above the mandrel and the cross section of the pipe is designed. The distance of the outlet surface from the center of the roll decreases from a value of 285 mm at the beginning to a value of 276 mm at the end, which is 0.97 of the distance to the curve defining the first polishing site. Then, the sleeve section falls on the second crimping section, the distance of which from the center of the roll smoothly increases from 276 to 326 mm, where gradually

formed by wall thinning. Finally, the wall is formed in the second polishing section, the distance from the center of the roll being equal to the entire length of 326 mm, which corresponds to a hot pipe diameter of 258 mm. The presence of an additional release area between the first polishing surface and the second gripping surface stabilizes the rolling process, compensating for the change in the metal feed to the rolls due to the imperfection of the designs of the feeding apparatus or an increase in the feed during the seed of the workpiece. In addition, the transverse thickness of the liner coming to the pilger mill reaches 25–40%, which significantly affects the volume of metal fed in one feed to the mill rolls on the first gripping surface, while dramatically changing the stretch in the first sections gripping and polishing and the presence of a polishing surface behind the surface prevents the metal from overflowing the second gripping surface, the formation of defects and differences on the pipe. When using a roll with an intermediate release, the surface of which at the end is at a distance of more than 282.2 mm from the center of the roll, which is 0.99 from the distance to the first polishing section, the spread of roll supply and the sleeve height are not compensated. Using a roll with a distance to con

This intermediate release section is less than 259 mm, which is 0.91 from the distance to the first polishing section, can lead to a loss of stability of the hot pipe profile in the longitudinal direction in the section corresponding to the exhaust surface, with the formation of transverse folds on the pipe surface and creating emergency in the rolling process.

. The use of the proposed roll for piligrim tube rolling allows improving the surface quality of the tubes, reducing the transverse wall thickness by 10-12%.

Claims (1)

Invention Formula A roll for piligrim rolling of tubes containing a body with a variable cross-section stream consisting of alternating alternating at least twice gripping areas, described by an increasing radius curve, and polishing sections, described by a constant-radius curve, characterized in that, in order to improve the surface quality between the polishing section and the subsequent gripping section, there is an exhaust section, described by a curve of decreasing radius to a value at the end of the section, which is 0.91-0.99 of the polishing section radius. g 1 FIG .. % w