Cold rolling method for internally threaded pipe

Abstract

The invention relates to a cold rolling method of an internal thread pipe. The cold rolling method mainly comprises the steps that a billet pipe is fed into a cold rolling machine to be rolled, and meanwhile feeding-in of the billet pipe is kept; in the rolling process, metal flows into an internal thread groove of a core stick, the inner wall of the billet pipe gradually forms a plurality of thread lines from zero to one and from shallow to deeper, meanwhile, wall reduction and diameter reduction of the billet pipe happen, and the internal thread pipe is formed; in the process of rolling the internal thread pipe, the billet pipe rotates while feeding-in of the billet pipe is kept; in the feeding-in and rotating process of the billet pipe, a core stick rotates relative to the billet pipe, and the core stick is subject to derotation relative to the internal thread pipe; and the special internal thread core stick and a special outer mold are adopted, during pipe manufacturing, one-time rolling deformation amount is large, the number of cold rolling passes is reduced, and meanwhile it is ensured that the manufactured pipe has the excellent quality.

Description

technical field [0001] The invention relates to a pipe rolling method, in particular to a cold rolling method of an internally threaded pipe. Background technique [0002] Internally threaded pipe, as the name implies, is a metal pipe with spiral lines on the inner wall, which is usually used in the field of heat exchange. In the prior art, the internally threaded pipes are all manufactured by cold drawing. Be 200510013531.5 Chinese invention patent application as application number, it discloses a kind of production method of cold-drawn internal thread pipe, it comprises: a, the mold of cold-drawn internal thread pipe design according to conventional method, comprises: outer mold, mandrel and Mandrel with spiral groove; b. The mandrel with spiral groove and the outer mold are placed in advance, that is, the relative position of the outer mold of the mandrel is adjusted through the mandrel, so that the starting point of the mandrel sizing belt is directed to the control Th...

AI Technical Summary

Problems solved by technology

However, there are always problems in cold drawing, which involves the forming principle of pipe making. Cold drawing is a stretching method, and the helix always deviates from the setting more or less. If the helix angle is drawn too large, the precision is not good. high

Cold rolling belongs to the extrusion method. It is obviously superior to cold drawing in terms of metal fluidity and product quality, but there are still problems in manufacturing that have not been solved, such as the fitting and locking of the inner helical tube and the inner threaded mandrel during forming. Problems, resulting in no reports of cold-rolled internally threaded pipes

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