SU829227A1 - Method of tube die rolling - Google Patents

Description

I

The invention relates to the production of Tpy6onpoKat, and specifically to a method of periodically rolling tubes, including hard-to-form pipes, using elongated cylindrical mandrels.

- A method is known for rolling tubes on batch mills with the use of elongated mandrels of a length of their working part of a populated cross section - straight cylindrical ij.

However, in such methods, high specific pressures in the deformation zone, and the strong heating of the working tool results in the mandrel in the rolling process working in a mode of intensive, uniformly along the length of its working part of thermomechanical loading, which causes frequent mandrel breaks in the critical section. This reduces the productivity of mills by increasing the Bp @ vieHH idle time for replacing mandrels, and increases the consumption of working tools.

2

Closest to the proposed method of periodic rolling of pipes, providing increased productivity and reducing breakage of the mandrel

The method consists in batch feeding of metal into the deformation zone, defo | / 4aain billet reciprocating movable rollers on the length of a cylindrical mandrel mounted in the workpiece cartridge and evenly moved in the direction of supply of the workpiece, simultaneously with the flow to turn the pipe 2,

The disadvantage of this method is that the rear end of the previous billet is pushed by the front end of the next, i.e. pipe rolling occurs butt, which 1FIVODITES to the cracking of the pipe ends. In addition, the return of the mandrel to its original position after rolling the entire billet lengthens the time of the deformation process. The purpose of the invention is to prevent pipe cracking and stabilization of the thermal rolling conditions. This goal is achieved by the fact that, according to the method of periodic rolling of pipes, including batch iodine of the metal into the deformation zone, the deformation of the workpiece held from the axial movement of the reciprocatingly moving rollers on the cylindrical mandrel, uniform axial displacement of the mandrel at the time of feeding each batch of metal, axial the displacement of the mandrel, up to the moment preceding the deformation of the rear end of the billet, is carried out in the direction opposite to the rolling stroke, and from the moment the metal feeds the rear end ahhztovki - rolled in the direction of turn. Moving the mandrel when applying each batch of metal in the direction 1 of the rolling stroke when feeding each batch of metal creates the possibility of uniform distribution of loads, along the lengths of the working part of the mandrel and stabilizes its thermal conditions, and moving the mandrel during rolling of the end of the slit prevents the joining of pipes, and the most and cracking their ends. H a fig, I presents the schematic impl. the rolling process at the position of the mandrel at the beginning of the process; in fig. 2 is the same at the position of the mandrel by deforming the rear end of the billet. The method is carried out as follows. Pipe billet 1, dredvarite ehne heated by inductor 2, the portion of the mi-metal is fed into the deformation zone formed by the sawmill rolls or the roller of the 7th circuit 3 and is deformed by them on a cylindrical mandrel 4 fixed by continuously cooling the 1st hollow rod 5 in the cartridge 6 of the rod. The length of the opraozki is (2.5-3.0) 6j where the length of the deformation zone. At the initial moment of the process (Fig. 1, the mandrel 4 is extended beyond the deformation zone during rolling and in the rolls zone its first working account & drain is located where the formation of the working Cone of the workpiece is started. At the same time, the workpiece cartridge 7 is carried out by cycling the next portion of metal workpieces into rolls of streams with a continuous reciprocating motion. The feed is carried out when the working cone of the workpiece is released from contact with the rolls. After the final formation of the working cone and the transition At the same time as each piece of metal is fed, i.e., in each deformation cycle by moving the chuck 6 of the rod, the mandrel is uniformly metered in the direction opposite to the rolling stroke, i.e. in the opposite direction to the finished pipe exit. Thus, in each deformation cycle in the deformation zone there is a new working section of the mandrel. At the same time, the front end of the mandrel is forced to be cooled until it is completely covered with the finished pipe, after Cooling stops. At this point, part of the mandrel sections that have been deformed in the deformation zone goes into the forced cooling zone inside the workpiece, where intensive heat removal from the mandrel sections that are not in contact with the heated billet through the cooled rod 5 begins. The magnitude of one-time movement of the mandrel is selected so that end of the workpiece in the area of the work rolls was the area of the mandrel Density of the rear end of the workpiece is equal to the sum of the length of the & cone and unstrained training Stack billet length O, 3-JO, S of the working cone length. The rolling process with the removal of the mandrel or by rolling it against the rolling process is carried out until the moment preceding the deformation of the billet end, i.e. until the metal is supplied to the workpiece in the deformation zone. From the moment before the rear bucket rolling (figure 2), when the next billet, 8, is clamped in cartridge 7, is already heated in inductor 2, by the reverse movement of cartridge 6 of the rod, the mandrel with the tube rolled on it by the metered feed amount occurring during the steady state process. The billet is periodically supplied to the deformation zone during the rolling of the rear end due to the contact friction forces between the mandrel and the rolling part of the billet. Axial movement of the mandrel relative to the workpiece is missing. By the chuck 7, the billet is no longer maintained that it is impossible to grip the rear end of the billet within the deformation zone, and the process of continuous joining of the pipes is underway.

After deforming the rear end, the process is stopped and the mandrel is returned to its original position (Fig. I).

Example. The pipes are rolled on the KhPTR-15-ZOA mill from steel-Х18Н1О. The pipes (4 pieces) are rolled along the route 21.5x0.35 -2O, 4xO, 2 with preheating of the workpiece to 350 ° C on an elongated cylindrical mandrel COUP a75O mm from ШХ15, the feed amount is 4.2 mm, retraction) of the mandrel for each double stroke - 1.2 mm, and when the rear end is fed - 4.2 mm for each double stroke. Over the deformation zone, the mandrel areas are cooled with an emulsion, and they are blown into the air before the deformation area. The whole pipe batch is rolled on: one mandrel, without stopping the mill to cool it outside the deformation zone.

The proposed method makes it possible to carry out pipe skipping without pipes,. to stabilize the thermal mode of rolling uniformly redistribute the mechanical loads along the length of the mandrel and reduce wear on the latter.

Claims (1)

1. USSR author's certificate No. 378267, cl. B 21 B 21 / GS, 1971. 2, US Patent No. 4О9О386, cl. 72-208, 1978.