Flexible forming method of secondary forming square tube

Abstract

The invention relates to a flexible forming method of a secondary forming square tube. The flexible forming method comprises the following steps of S1 performing factory inspection on raw materials; S2 feeding the raw materials, conveying on a roller way, and hydraulically propelling; S3 performing flexible extrusion forming; S4 sizing; S5 straightening to prevent distortion; S6 performing R-angle medium-frequency annealing; S7 conveying on the roller way. The flexible forming method has the advantages that the physical dimension of a steel tube can be guaranteed, the physical properties of the steel tube can be improved, the physical properties of the steel tube can reach the standard in the condition of no heat treatment, the production need is satisfied, and the production cost is reduced.

Description

technical field [0001] The invention relates to a method for forming a square-rectangular tube, in particular to a method for forming a square-rectangular tube with secondary forming flexibility. Background technique [0002] The secondary forming square tube technology is the earliest drawing type forming. The round tube is deformed by a deformation mold through a drawing machine. The material is deformed sharply in the mold, and the deformation process is pure sliding friction. The friction resistance is large, and the heat generated by the mold is high. The service life of the mold is low, resulting in low product output and product qualification rate. This molding method also has the following defects: [0003] 1. The deformation interval of the mold is short, resulting in the rapid deformation of the material in this part, which makes the yield strength and tensile strength of the steel pipe rise sharply after forming. It is easy to cause the forming stress of the stee...

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Problems solved by technology

[0002] The secondary forming square tube technology is the earliest drawing type forming. The round tube is deformed by a deformation mold through a drawing machine. The material is deformed sharply in the mold, and the deformation process is pure sliding friction. The friction resistance is large, and the heat of the mold is high. The service life of the mold is low, resulting in low product output and product qualification rate. This molding method also has the following defects:

[0003] 1. The deformation interval of the mold is short, resulting in the rapid deformation of the material in this part, so that the yield strength and tensile strength of the steel pipe after forming are increased sharply

It is easy to cause the forming stress of the steel pipe to be too high

There is a safety hazard in the steel pipe, and it is easy to cause the formed square pipe to have a tendency to crack at the fillet

[0004] 2. One-step drawing forming. In the mold design, due to the excessive concentration of the deformation zone and the sizing zone, the material changes rapidly during the forming process, which makes the steel pipe after forming have a large anti-deformation ability, and the geometric size of the steel pipe, the flatness of the steel pipe, the It is difficult for straightness and twist to meet the requirements of national standards

[0005] 3. One-step drawing and forming, it is difficult or impossible to guarantee the production of rectangular tubes with large aspect ratios

The residual stress of the steel pipe has become a direct safety hazard to the quality of the steel pipe, especially the thick-walled, high-grade square rectangular pipe. If the residual stress of the steel pipe is not removed in time for annealing treatment, there is a danger of direct cracking at the fillet of the steel pipe.

In order to solve the above problems, the most commonly used method is to anneal the steel pipe as a whole, which undoubtedly increases the production cost of the steel pipe. Many customers do not accept the increase in the cost of the steel pipe, and require enterprises not to do heat treatment, and the quality of the steel pipe must also meet the standard

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