SU566640A1 - Billets for cross-helical tube rolling - Google Patents

Description

one

The invention relates to the field of production of seamless hot rolled pipes and can be used in the production of pipes on roll mills, in particular on a plant with a three-roll grip mill.

A well-known pre-rolling tube for rolling seamless pipes on rolling mills, for example, an automatic and pilgrim one, which has a main hollow cylindrical part with profiled end sections 1.

The workpiece has an end portion with an internal cone, which improves the gripping conditions of the mandrel. However, such a profile of the end sections conjugated to the cylindrical main part does not provide an increase in the rolling speed.

The closest solution to the technical essence is a billet for the production of pipes on a three-roll oblique rolling mill, the end sections of which are made conical with a reduced thickness by one wall to the ends, where the wall thickness is less than the thickness, and the other walls of the finished pipe 2.

However, a preform of this shape does not significantly increase the speed of rolling the pipe. For example, at the end of the rolling process, the formation of a socket is observed when the feed angle is not increased.

more than one degree compared to the feed angles when rolling billets without profiled sections.

This is due to the fact that during the rolling of the end sections, a distortion of the circular initial shape (faceting) of the cross section occurs as a result of extrafocal deformation.

The purpose of the invention is to increase the speed of the helical rolling, as well as improve the conditions for gripping the liner, which ultimately will lead to an increase in the productivity of the rolling process.

This is achieved by the fact that the billet has a main cylindrical part and end sections, the length of which is 0.5-2.0 times the diameter of the cylindrical part and on which external transverse grooves are made increasing towards the end with a depth of 0.2-0.5 wall thickness of the cylindrical parts up to 0.6-0.9, with a width equal to 0.3-0.8 wall thickness, and with a distance between adjacent grooves of 1.5-2 groove widths.

This makes it possible to improve the secondary capture and thereby contribute to an increase in the rolling speed.

The drawing schematically shows the workpiece, the total vnd.

The workpiece consists of a main hollow cylindrical part 1 and profiled

end sections 2, on the outer surface of which the grooves 3 are made, for example a trapezoidal profile. The depth of the grooves increases to the end from 0.2-0.5 to 0.6-0.9 of the wall thickness of the workpiece in the main part. Sh.Nrina groove is equal to 0.3-0.8 wall thickness, and the distance between adjacent grooves is 1.5-2 times the width of the groove. This, on the one hand, ensures the sealing of the jumpers inside the naz without increasing the section size and, on the other hand, a sufficient number of slots on the selected length of the end section. Increasing the depth of the grooves towards the end is necessary to control the increasing lateral deformation directly in the profiled section. The depth of tsazov is limited at the end by a size of 0.6-0.9 of the wall thickness by the conditions of the cross section along the bottom of the groove.

The length of the end sections within 0.5-2.0 of the diameter of the billet is chosen from the condition of providing a stable grip during the cross-helical rolling and a sufficient length of the rigid end. Increasing the length of the end sections is not economically feasible, since it will lead to exceeding the cutting standards due to the fact that a long number of annular grooves leads to the need to cut off the end sections at this length.

Cylindrical floor billet: ka with end sections in which transverse annular grooves are inserted, is rolled into

a pipe at a temperature of hot deformation on a cross-helical rolling mill, for example, on a three-roll mill with a long mandrel. At the task of the workpiece into rolls, the gripping conditions are improved due to the existing required reduction in wall thickness before the roll ridge.

Invention Formula

Claims (2)

1. Preparation for a cross-helical pipe rolling, comprising a main cylindrical part and profiled end sections, characterized in that, in order to increase the rolling speed, the end sections, which are 0.5-2 times the diameter of the cylindrical part, are made transverse external grooves with uniformly increasing depth to the end; 2. Preparation under item 1, characterized in that the depth of the groove is increased to the end from 0.2-0.5 to 0.6-0.9 of the wall thickness of the cylindrical part, the width of the groove is 0.3-0.8 of the thickness walls, the distance between adjacent slots is 1.5-2 times the width of the groove. Sources of information taken iBO attention in the examination 1. USSR author's certificate number 418235, cl. B 21 B 17/00, 1972. 2. USSR author's certificate number 144814, cl. B21 B 19/02, 1960