Hot-rolling perforation-cold-rolling forming method for hollow rock-drill steel

Abstract

The invention provides a hot-rolled perforation-cold-rolled forming method of hollow drill steel. It is characterized in that: the hot-rolled piercing-cold-rolled forming method is used to produce B and D-type hollow drill steels, and the hot-rolled piercing Φ50 two-roll cross-rolling piercing machine rolls the round solid tube blank of Φ50~Φ65mm in a hot state. Φ50~Φ65mm, hollow capillary tube with wall thickness of 6~17mm, after cooling, it is rolled and formed on a cold rolling mill. The invention starts from the geometric characteristics of the hollow steel and realizes a specific deformation process through tool design. Compared with the existing production method, the main advantages of the present invention are: few working procedures, short flow process, good quality of inner hole, high precision of shape and size.

Description

technical field [0001] The invention belongs to the technical field of metal material processing, and in particular provides a hot-rolled piercing-cold-rolled forming method for hollow drill tool steel. Background technique [0002] Hollow drill steel is the main tool used for rock drilling and drilling in mining. Commonly used specifications are hexagonal B19~B45 (the number indicates the distance between opposite sides in mm) and circular D32~D51 (the number indicates the diameter in mm), and its cross section is as follows: figure 1 As shown, the water injection hole in the center is used for water, dust removal and cooling. [0003] The geometric characteristics of hollow drill steel are: wall thickness (the ratio of wall thickness to outer diameter S / D is 1 / 3.2~1 / 3.5), small inner hole (minimum is only 5.5mm), long length (up to 6mm ). In view of the above-mentioned geometric characteristics of "like (steel) pipe but not (steel) pipe", this product can neither comple...

AI Technical Summary

Problems solved by technology

The main disadvantages of this process are: many procedures, long process, out-of-round inner hole and large mandrel consumption (one mandrel can only roll one hollow drill steel)

The main disadvantage of this process is that due to the absence of the mandrel to process the surface of the inner hole and the severe torsion of the pipe during the cross-rolling extension process, cracks, wrinkles and other defects often appear on the surface of the inner hole, resulting in low service life and instability.

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