SU965535A1 - Mandrel for shaping tube blanks - Google Patents

Description

(54) FRAME FORMING PIPE PREPARATIONS

one

The invention relates to the manufacture of pipes, and more specifically to the production of electrically welded electric pipes or billets, and can most effectively be used in argon-arc welding mills.

A known mandrel for forming tubular blanks, made of two cylindrical parts with the same radius of curvature. The mandrel contains calibrating and intake areas and is installed on the rod with the aid of the holder. Calibration part in. The upper half of the mandrel, executed with a slope to the axis of the mandrel, guides and supports the mating pipe edges as they pass through the squeeze rolls 1.

The disadvantage of this design of the mandrel is that, prior to the forced extension of the tube blank, half of the tube blank, formed along radii smaller than the radius of the finished tube, are in a different stress state. Therefore, when extending the edges of the tubular billet, the resulting friction forces between it and the mandrel result in rapid wear of the latter. This necessitates frequent replacement of mandrels and forced downtime of the mill.

Closest to the proposed technical entity is a mandrel for forming billets containing offset and calibrating sections that are displaced in a horizontal plane. The cylindrical calibration section is made of two semi-cylinders of different curvature and length, and the intake section of two half-cones of different curvature that are displaced relative to each other. Both halves of the calibrating section, along with the halves of the intake section, are offset one relative to the other in the axial direction 2.

A disadvantage of the known construction of the mandrel for forming billets is that during the molding process the mandrel contacts the inner surface of the blank on a considerable surface. It causes great friction.

Claims (2)

20 and leads to the rapid deterioration of the mandrel itself and its frequent replacement. In addition, such a mandrel cannot operate at elevated speeds, since at welding speeds of more than 2 m / min, due to considerable frictional forces, the mandrel heats up, and the workpieces stick to its surface. This significantly affects the internal surface of the welded pipes. The aim of the invention is to increase the welding speed by reducing the frictional forces and increasing the wear resistance of the mandrel. The goal is achieved by the fact that the mandrel for forming billets, containing, and the intake and calibrating sections displaced in a horizontal plane, is made in the form of a stepped axis and a pair of workers installed on it and the rollers arranged between them, while the axis of rotation of the roller is mixed relative to the axes of rotation of the work rolls vertically. Such a design embodiment of the mandrel for forming tubular blanks allows operation at higher speeds. This is due to the fact that during the molding, the inner surface of the workpiece contacts the mandrel by rotating in opposite directions eccentrically shifted working and support rollers. Due to the support roller, the friction of the non-working sections of the forming rollers with the inner surface of the workpiece is eliminated, and contact occurs only in the deformation zone. This prevents the working surfaces of the rollers from overheating, sticking of metal and rapid wear, which contributes to an increase in the service life of the mandrel and an increase in the quality of the workpiece. FIG. 1 shows the mandrel, a general view; in fig. 2 shows section A-A in FIG. one; on. FIG. 3 shows a section BB in FIG. 2; in fig. 4 —stage of the forming pipe in front of the welding unit; in fig. 5 is a sectional view BB in FIG. four; in fig. 6 is a cross-section of the FIG. four; in fig. section dd in fig. four; in fig. 8 is a view E of FIG. four; in fig. 9 shows the position of the pipe pellet at the moment of its contact with the working roller 4; in fig. 10 - position of the billet at the moment of its contact with the working roller 3. The mandrel for forming the billets includes a cylindrical body 1. On the housing 1 in the U-shaped notch there is a step-like axis 2, on which three rollers are located eccentrically relative to each other in the horizontal plane. Work forming, rollers 3 and 4 have intake 5 and 6 and calibrating 7 and 8 sections. Between the working rollers 3 and 4 with vertical mixing, the support roller 9 is located. The housing is attached by screws 10 to the holder 11. Calibration sections 7 and 8 are the upper ones forming the working rollers 3 and 4. The working roller zones are from the contact point of the tubular billet at the initial moment the molds to the calibrating portions are intake portions 5 and 6. The lower forming portion of the mandrel body lies in line with the lower generatrix of the support roller. The device works as follows. Pipe billet 12 is formed along a radius smaller than the radius of the finished pipe. In this case, one Loudness is under the other. When the workpiece 12 is pulled over the mandrel, each half of the pipe stock is unbent by a certain angle to create the same stress state in the left and right half of the workpiece 12. One half of the billet with an excess edge advances onto the forming roller 3, and the other half with a smaller radius moves onto the roller 4. As the billet 12 moves along the sizing sections 7 and 8 of the mandrel, each half of it is extended, and an equal tension is created in each half, with half of the billet 12, molded along a larger radius, is extended by a working roller 3 having a smaller radius. Upon further movement, the workpiece passes through the outlet section 13 of the mandrel, having a diameter equal to the internal diameter of the pipe, where the gap between the edges is gradually reduced due to the reverse springing of the material of the pipe billet. At the same exit section 13, the edges of the billet 12 are completely flattened, and due to the coincidence of the forming output section 13 and the support roller, the inner surface of the workpiece contacts the mandrel only in the deformation zone. The proposed design of the mandrel for forming tubular billets as compared to the known ones allows to increase the welding speed, significantly increase the service life of the mandrels, reduce equipment downtime, improve the quality of the blanks and increase the yield. The invention of the mandrel for forming billets, containing offset and calibrating sections that are displaced in a horizontal plane, characterized in that, in order to increase the welding speed by reducing friction forces and increase the wear resistance of the mandrel, it is made in the form of a stepped axis and mounted on It has a pair of workers and supporting rollers arranged between them, while the axis of rotation of the supporting roller is offset relative to the axes of rotation of the working rollers vertically. Sources of information taken into account in the examination 1. US patent number 2782293, cl. 219-59, 1957. 2. USSR author's certificate number 660743, cl. B 21 C 37/00, 1977 (prototype). -m if ( fig 5 Kidw Yr Dd 7 eleven 12