SU373040A1 - METHOD OF HOT PILGRIM ROLLING TRA - Google Patents

Description

one

The invention relates to the field of production of pipes by hot shiligrim rolling, in ocHOiBHOM these are “walls” of pipes with a diameter of 40 or more thicknesses of the wall.

There are known methods of hot piliprim tube rolling, including deformation of a liner with back pressure on the mandrel rolls with crimping and polishing sections 1 on their working part. However, at the beginning of the deformation of the thin-walled pipes from the side of the pilgrim head, there is a local swelling of the profile in the zone not covering the top of the gauge, i.e., loss of its stability in the longitudinal direction.

To prevent the loss of longitudinal stability of a rolled thin-walled tube, it proposes adjusting the back end of the liner during the rolling process, increasing it at the deformation moment of the squeeze liner of the rolls and lowering it at the moment of deformation by the polishing site.

According to the described method, before rolling the liner, an abutting ring, which provides support for the liner, is withdrawn by means of a hydrocillium forward relative to the back end of the mandrel and fixes the liner with a predetermined force, at least by a smaller force, at which a pipe of a given size loses longitudinal stability. The magnitude of the predetermined force required to prevent the pipe from losing longitudinal stability depends on the cross section

rolled tube, rolling temperature and friction coefficient on the mandrel.

In the rolling process in connection with the occurrence of the advance of the metal (current) relative to the mandrel in the direction of rolling

the stop ring is displaced in the rolling direction along the mandrel. In order to reduce the displacement of the rear end of the liner relative to the mandrel and, consequently, the amount of pre-retraction of the ring during each rolling cycle, the backpressure is automatically controlled, raising it to a value preventing the relative displacement of the mandrel during the period of deformation of the pipe and reducing to a value that prevents the loss of longitudinal stability of the pipe during its deformation by the polishing roll area. The limits of the regulation of the magnitude of the backwater

The liner can be changed by the stop ring, if necessary, in the process of cutting all the Tipy6bi, depending on the change in rolling temperature, which is lower at the end of pipe rolling than at the beginning. The ability to adjust the force of the backwater to the ring when

A rather low coefficient of friction at the contact of the pipe with the mandrel allows rolling thin-walled pipes without losing longitudinal stability, which provides an increase in the yield.

Subject invention

Sposo (b hot saws for prim rolling tubes, including deformation of the liner with

With the rear end of the aperture with the rollers with obsiming and polishing sections of the working part, characterized in that, in order to prevent the loss of longitudinal stability of the rolled thin tube, the amount of backwater in the rolling process is controlled by increasing it at the moment of deformation of the sleeve rolls and lowering at the moment of deformation by the polishing area.