SU407598A1 - DORN, PREFERRED, FOR HOT PIPE ROLLING - Google Patents

Description

one

The invention relates to the pipe industry, namely to improving the design of an instrument, in particular a mandrel (mandrel), for hot pilgrim tube rolling.

Knuckles (mandrels) for pilgrim tube rolling are known, having a variable taper in length and a greater taper portion in the tail section.

Such mandrels (mandrels) are used for cold pilgrim tube rolling and do not allow to obtain a multi-bottom billet with a thinned wall at the rear end for subsequent reduction. When pipes are rolled in a reduction mill with tension, their ends are made with a thicker wall, their necks are out of tolerance, and cut off.

Waste is 10-20%, which leads to an increase in the expenditure ratio of the metal.

The purpose of the invention is to create a mandrel, the construction of which will allow to obtain hot piligrim rolling different lengths of the workpiece with a thinned wall at the rear end, which during subsequent reduction with tension will make it possible to obtain the thickness of the rear end wall equal to the middle part of the pipe.

This is achieved by the fact that the section of greater taper at the present mandrel is made equal to the sum of the lengths of the pilger head and the thickened end of the pipe obtained by subsequent reduction with tension, while the length of the section of the greater taper corresponds to 0.2-0.5 of the total length of the mandrel. .

The drawing shows the proposed mandrel, a general view.

The proposed mandrel has a variable taper in length. The tail section 1 of the mandrel is made with a greater taper angle than in the main section 2. The length of section 1 is equal to the sum of the length of the pilger head and the length of the thickened end of the pipe (not shown) obtained by subsequent reduction with tension, and is determined by the formula:

/ t 1

/.l: ,, -Ln, + -,

where LXI is the length of the tail section of the mandrel;

Bn is the length of the pilger head;

LOS is the length of the rear thickened end of the pipe, obtained by reducing with tension;

R. - stretch ratio during reduction.

The ratio of the length of the section with a greater taper is derived from this formula and is equal to 0.2-0.5 of the total length of the sod.

The tail part or part of the sod with a greater taper can be made with a straight or curvilinear generatrix.

When rolling tubes on a pilger mill, a proposed mandrel with an enlarged cone in the tail section at a length equal to the pilger head of the workpiece and its thickened end, obtained by subsequent reduction, reduces the cost of metal at the back end of the rear end, while the amount of waste is reduced by half rolling in the reduction mill of the whole tube uncut after the pilgrim mill and one quarter of the tube on the reduction mill rolling the tube cut in half after pilgerstan.

Subject invention

Claims (2)

1. Dorn, mainly for hot rolling of pipes, having a variable taper in length and a section of greater taper in the tail section, characterized in that, in order to obtain a different thickness the length of the workpiece with a thinned wall at the rear end for the subsequent reduction, a greater taper portion is made with a length equal to the sum of the lengths of the pilger head and the thickened end of the pipe obtained with subsequent reduction with tension. 2. Dorn p. 1, characterized in that a larger taper area is made on length equal to 0.2-0.5 total length of the mandrel. The priority of clause 1 is calculated from 10.UP.1970 T