SU1523202A1 - Method of pilger rolling of very thin-walled tubes - Google Patents

Abstract

The invention relates to the processing of metals by pressure. The purpose of the invention is to reduce metal losses. When preparing blanks for subsequent cold (warm) roller or roller periodic rolling, the end surface of the blanks is strengthened to a depth of 1-2 mm with a degree of deformation of 15-25% of the metal deformation per pass. After machining the butt (lay-up of the end surface with a chisel and removing burrs on the edges of the butt), it is either deposited axially, or it acts on the end surface with vibrating strikers. 1 tab.

Description

The invention relates to the processing of metals by pressure and can be used, in particular, during the rolling of very thin-walled pipes on HPT and HPPR mills.

The purpose of the invention is to reduce metal losses.

The method is carried out as follows.

After machining the end face (planing the end surface with a cutter and removing burrs on the edges of the end face), the end face is either axially upset, or the end face is affected by vibrating beams;

In this case, the end is strengthened to a depth of 1-2 mm with a degree of deformation of 15-25% of the value of the subsequent deformation of the metal per pass. Burrs occurring during the upsetting or impact of the dies.

The proposed and well-known methods were tested when rolling tubes of steel 08Х18Н10Т on a KPW 25VMR mill along the route 18-1.0-7.9-0.45 mm with a degree of deformation per pass equal to 80%. In this case, the ends of the blanks are strengthened with a hammer. The degree of penetration of the deformation is fixed by the magnitude of the thickening of the wall of the workpiece, and the magnitude of the deformation is determined by the shrinkage of the end face.

Rolling blanks with reinforced and non-reinforced ends is carried out at a feed of 3 mm. The composition of the lubricant-oh: d w

&9

the binding liquid and the number of binary passages (160 min) do not change.

The results of pipe rolling are shown in the table.

From the analysis of the data presented in the table it can be seen that the deformation of the less proposed limits is insufficient (experiment 1) and does not provide the necessary strengthening of the end surface, the deformation of the more proposed limits is excessive. Although the cutting of the ends does not occur, however, the plastic property of the metal in the end zone exceeds the allowable dp of this steel, therefore, the ends of the blanks crack in the rolls (approximately in the middle part of the working cone). The total deformation exceeds 95%.

Thus, the proposed method, in comparison with the known, provides rolling (without a dock) of very thin-walled pipes without stopping the mill and without the need to cut the damaged ends of the blanks. This is due to the fact that the found connection of the hardening parameters with the amount of deformation per pass eliminates the joining of pipes in the process of deformation.

Claims (1)

Invention Formula Pilger rolling method of specially thin-walled tubes, including preparation of billets and their subsequent cold or warm roller or roller periodic rolling, characterized in that, in order to reduce metal losses, in preparing billets, their ends are strengthened to a depth of 1-2 mm with the degree of deformation 15-25% of the metal strain per pass. 0.5 one 1.5 2.0 2.5 Without hardening 10 (12.50) Poor cutting of the ends to a depth of 1.5-2.0 mm 15 (18.75) There is no end cutting 20 (25.00) (31.25) (37.50) Cracking of the ends in the deformation zone Piercing of the ends on the pile to 5 mm. Rolling stopped