A kind of high pressure crack initiation method in liquid at the root of surface annular groove of pipe blanking

Abstract

Provided is a liquid inner high-pressure crack initiation method for the root of an annular groove in the surface of tube blanking. Before crack initiation, the annular groove is prefabricated in the surface of a metal tube, a flange connector and a charging tube are assembled at one end of the metal tube, a sealing head is assembled at the other end of the metal tube, the two ends of the metal tube are sealed through a C-shaped sealing ring and a step sealing sleeve respectively, and axial tensioning is carried out through bolts. In the crack initiation process, the metal tube is fast filled with emulsified liquid or hydraulic oil through the charging tube, the inner wall of the metal tube bears initial inner pressure, then high-pressure low-speed fluid is charged into the metal tube, inner high pressure is continuously applied to the inner wall of the metal tube, metal crystals at the root of the annular groove of the metal tube are made to slide and shift under the stress concentration effect, a persistent slip band is formed, and a microcrack group is formed finally. After crack initiation is finished, the metal tube is fed into a blanking machine to for segmented blanking. The stress concentration effect is utilized, the crack expansion time in the blanking process is effectively shortened, and blanking efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of blanking of metal pipes, and in particular relates to a liquid internal high-pressure cracking method at the root of an annular groove on the surface of blanking pipes. Background technique [0002] The blanking of metal pipes is widely used in the preparation process of gun barrels, inner (outer) rings of rolling bearings, bearing bushes of sliding bearings, roller sleeves of conveyor chains, etc. The quality of the blanking directly affects the manufacturing accuracy, production efficiency and economy of parts. cost. The traditional pipe blanking process mainly includes three types: one is cutting processing, which mostly adopts turning, sawing, grinding wheel cutting and other forms, the production efficiency is low, and the processing quality is difficult to guarantee; the other is stamping processing, which is mainly processed by mechanical press. Cutting with a special mold, but because the pipe is...

AI Technical Summary

Problems solved by technology

In recent years, the low-stress pipe material precision cutting technology developed by using the prefabricated notch stress concentration effect and the dynamic crack propagation method has made a new breakthrough in the metal pipe material cutting process. Stress bending fatigue fracture precision blanking machines have achieved chip-free material-saving production, but due to the long life of dynamic crack growth, the blanking efficiency still cannot meet mass production

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