Hollow core rod used for planetary rolling mill

Abstract

The invention relates to an improvement method of a core rod of a metal rolled tube, in particular to a hollow core rod used for a planetary rolling mill. According to the technical scheme provided in the invention, the hollow core rod used for the planetary rolling mill comprises a rod body, a screw thread section positioned at the left end of the rod body and a conical section positioned at the right end of the rod body. The invention is characterized in that the rod body is also in a conical shape, thus ensuring that the left end of the rod body is greater than the right end of the rod body; through-holes which are communicated with each other and are arranged on the same axial line are arranged in the rod body, the screw thread section and the conical section; two planes are arranged on the outer surface close to the screw thread section on the rod body, and the two planes are in parallel and are symmetrical to the axial line of the rod body; the conical degree of the rod body is 150:0.08; the material quality of the hollow core rod is H13; and the hardness of the hollow core rod is HRC53-55. The invention can improve the comprehensive yield, labor productivity of tubing and the level of product quality.

Description

technical field [0001] The invention relates to a method for improving a mandrel of a metal rolling tube, in particular to a hollow mandrel for a planetary rolling mill. Background technique [0002] At present, the mandrel molds used in planetary rolling mills at home and abroad are all made of solid cores. Its material: 3Cr2W8V in China, heat treatment hardness: HRC45-50, and it has to be replaced after a service life of 3-5 tons. After grinding, the service life 2 to 4 pieces, the reason for the low service life of the mandrel: the analysis is that when the rolling mill is rolling the billet at high speed (∮88*24→∮48*2.2), the temperature is instantaneously raised to 750~ 850 ℃, long-term (30 minutes) use at high temperature, the surface hardness of the mandrel gradually decreases until the surface of the mandrel has a ring groove when it reaches HRC36-38; if the rolling continues, the inner wall of the pipe will have a spiral shape Stretch marks, it is difficult to elim...

AI Technical Summary

Problems solved by technology

[0002] At present, the mandrel molds used in planetary rolling mills at home and abroad are all made of solid cores. Its material: 3Cr2W8V in China, heat treatment hardness: HRC45-50, and it has to be replaced after a service life of 3-5 tons. After grinding, the service life 2 to 4 pieces, the reason for the low service life of the mandrel: the analysis is that when the rolling mill is rolling the billet at high speed (∮88*24→∮48*2.2), the temperature is instantaneously raised to 750~ 850 ℃, long-term (30 minutes) use at high temperature, the surface hardness of the mandrel gradually decreases until the surface of the mandrel has a ring groove when it reaches HRC36-38; if the rolling continues, the inner wall of the pipe will have a spiral shape Scratch, it is difficult to eliminate the stretch mark after stretching the pipe wall thickness ≥ 0.5. The copper pipe used in the air-conditioning industry has high requirements on the inner wall. In order to ensure the product quality, the mandrel has to be replaced, which not only increases the production cost but also wastes the pipe.

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