Manufacturing method for continuously rolling seamless steel pipe by using hollow mandril

Abstract

The invention provides a method for manufacturing a hollow mandril of a continuously rolling seamless steel pipe. The method comprises the following steps of: designing the steel grade and the specification of the hollow mandril; performing continuous casting, cogging, and forging; rolling a mandril material, performing tempering heat treatment; and detecting the performance of the mandril material, and processing and connecting the mandril material. The method has the advantages that: the problem that the retained mandril depends on import for a long time is solved, so that the production localization of the retained madril is realized; the service life of the mandril is close to or the same as that of the solid mandril of the same specification which is imported from foreign countries or bought in China; and the quality of the inner and outer surfaces of a seamless steel pipe product in the production process is good, 1.5 to 1.7kg of steel is consumed for one ton of mandrils, the cost of one ton of steel is 30 yuan which is only one third the original cost, and the production cost is greatly reduced. Due to the development and use of the hollow mandril, the consumption cost of a tool is reduced, and the market competitiveness of a steel pipe product is improved; the technology promotion of the mandril manufacturing industry in China is driven, and the method has a profound and lasting significance for the top potential and consumption reduction of metallurgical industry.

Description

technical field [0001] The invention belongs to the steel pipe rolling technology in the metallurgical industry, in particular to a method for manufacturing a hollow mandrel for continuously rolling seamless steel pipes. Background technique [0002] The hot tandem rolling units that produce hot-rolled seamless steel pipes at home and abroad all use solid mandrels. Most of these mandrels are H13 steel grades imported from abroad. The average price of a single piece is more than 200,000 yuan. The cost of hot-rolled tools is more than 40%, and the steel consumption per ton is 60 yuan / ton. The cost is extremely high. At the same time, the purchase price continues to rise, and the delivery cycle has reached more than one year. [0003] As the market situation changes, it is urgent to reduce production costs and improve steel pipe quality to improve product competitiveness. However, through negotiations with foreign mandrel manufacturers, there is no new mandrel that meets the r...

AI Technical Summary

Problems solved by technology

However, rolling thick-walled steel pipes with the same steel type as H13, on the one hand, the steel smelting and heat treatment processes are relatively complicated, and there is no record of rolling H13 steel pipes at home and abroad, especially for the production of extra-thick-walled steel pipes, the load of the rolling mill is large, and it is difficult to meet the batch production requirements

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