Technology for producing hollow steel by hot squeeze method

Abstract

A technology for manufacturing hollow steel by hot extrusion method includes such steps as perforating a blank, heating and extruding by the hot extruder which has a float mandrel and its protecting sleeve for inserting them into the pre-made hole on the blank. Its advantages are small hole diameter (the smallest hole down to 5 mm), high extruding speed and productivity, and high utilization rate of material (90% or more).

Description

technical field [0001] The invention relates to a hollow steel hot extrusion production method, in particular to a hollow steel manufacturing process which combines a hot extrusion method, a floating mandrel and a drawing method. Background technique [0002] Hollow steel manufacturing processes at home and abroad mainly include hot piercing and hot rolling, cast pipe core rolling and mechanical drilling. The hot piercing and hot rolling method has a simple process and a high yield, but because there is no core, the inner diameter will inevitably be deformed during the reduction and hot rolling process, resulting in poor quality of the inner hole. Cast pipe core rolling method is widely used in my country, but due to small ingot shape and small compression ratio, there are metallurgical defects such as shrinkage cavity, porosity, non-metallic inclusions, etc., and the shape and geometric size of steel are poor. The mechanical drilling method is rolled by a special hollow st...

AI Technical Summary

Problems solved by technology

The hot piercing and hot rolling method has a simple process and a high yield, but due to the absence of a core, the inner diameter will inevitably be deformed during the reduction and hot rolling process, resulting in poor quality of the inner hole

Cast pipe core rolling method is widely used in my country, but due to small ingot shape and small compression ratio, there are metallurgical defects such as shrinkage cavity, porosity, non-metallic inclusions, etc., and the steel shape and geometric size are poor

The mechanical drilling method is rolled by a special hollow steel rolling mill, and the geometric size is better, but it inevitably has the defect of low material utilization rate, and the yield is only about 78%, resulting in high manufacturing cost.

[0003] The hot extrusion method is the most advanced production technology in domestic and foreign pipe making, but the mandrel of the complete hot extrusion method is subjected to high temperature stretching and strong friction stress during the extrusion process, and it will break if it is too thin. Therefore, there is no precedent for using mandrels smaller than 60mm in China.

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