焊管成型时的回弹

低碳钢焊管成型时，反弹一般不是很突出的问题。随着我国焊管行业的发展，各种新材料在焊管行业的应用，各种低合金、合金钢焊管等金属元素的加入，以及合金焊管的开发和生产，成型过程中的反弹已成为一个突出的问题。

During the forming of low carbon steel welded pipe,the springback is generally not a very prominent problem. With the development of China's welded pipe industry,the application of various new terials in the welded pipe industry,the addition of various metal elements such as low alloy and alloy steel welded pipe,and the development and production of alloy welded pipe,their springback in the forming process has become a more prominent problem.

成型回弹为：

Forming springback is inly shown as follows:

1.根据孔型设计方法设计成型辊，由于回弹，实际较终成型不是所需的形状，特别是带钢边缘成型不足。

1.The forming roll is designed according to the pass design method. Due to rebound,the actual final forming is not the required shape,especially the edge forming of strip steel is insufficient.

2.合金焊管高速生产时，回弹会导致离开挤压辊时未完全凝固的焊缝出现裂纹，焊管焊缝内表面出现裂纹。

2.During high-speed production of alloy welded pipe,large rebound will cause cracks at the weld that has not fully solidified when leaving the extrusion roll,and cracks will appear on the inner su ce of the weld of welded pipe.

3.为了提高合金焊管的焊接速度，管坯的两个边缘需要紧密接触。如果回弹较大，挤压辊的前后边缘将打开管坯，使焊接无法进行。

3.In order to improve the welding speed of alloy welded pipe,the two edges of the pipe blank need to be in close contact. If the rebound is large,the pipe blank will open at the front and rear edges of the extrusion roll, king the welding impossible.

焊管的成型是一个塑性变形的过程，包括弹性变形的一部分，弹性变形是导致回弹的。金属不是理想的塑性变形材料。金属材料在焊管成型过程中的加工硬化和变形条件的复杂性使得回弹问题难以准确解决。

The forming of welded pipe is a plastic defor tion process,which includes part of elastic defor tion,and it is elastic defor tion that causes springback. Metal is not an ideal plastic defor tion terial. The work hardening phenomenon of metal terials and the complexity of defor tion conditions in the forming process of welded pipe ke it difficult to accurately solve the springback problem.

就钢材而言，其弹性模量对化学成分的小变化和微结构的变化不是很敏感，弹性模量差别不大，因此其反弹主要取决于屈服强度，因此冷轧带钢作为低碳钢，强度高于热轧带钢，低合金钢和合金钢高于低碳钢，因此反弹较大。

As far as iron and steel terials are concerned,their elastic modulus is not very sensitive to s ll changes in chemical composition and microstructure,and there is little difference in their elastic modulus. Therefore,their resilience inly depends on the yield strength. Therefore,as a low-carbon steel,cold-rolled strip has higher strength and greater resilience than hot-rolled strip,and the strength of low-alloy steel and alloy steel is higher than that of low-carbon steel,Therefore,the rebound is large.

几种克服反弹的方法：

Several methods to overcome rebound:

1.适当增加成型辊的变形量

1.Properly increase the defor tion of forming roll

对于一些大型回弹材料或大型焊管设计成型辊，应考虑大回弹因素，适当增加各成型辊的变形，使管坯回弹后的形状达到所需的形状，特别是金属带的边缘，有利于防止桃管的产生。

For some terials with large springback or large welded pipe,when designing the forming roll,the factor of large springback should be considered,and the defor tion of each forming roll should be appropriately increased to ke the shape of the pipe blank after springback reach the required shape,especially the edge part of the metal belt. This method is conducive to preventing the occurrence of peach shaped pipe.

2.采用加热成型法

2.Heating forming method is adopted

随着温度的升高，金属材料的屈服强度和弹性模量会降低，加热成型可以减少成型过程中的反弹。

Because the yield strength and elastic modulus of metal terials will decrease with the increase of temperature,heating forming can reduce the amount of springback in the forming process.

3.采用非对称成型法

3.Adopt asymmetric forming method

非对称成型法是指挤压辊前使用两组非对称成型辊，使管坯在进入挤压辊前发生两次不对称变形。只要非对称辊设计合理，管坯的两个边缘就可以在一定距离内保持密切接触，以满足焊接要求。

Asymmetric forming method refers to the use of two groups of asymmetric forming rollers before the extrusion roller,so that the pipe blank has two asymmetric defor tion before entering the extrusion roller. As long as the asymmetric roller is reasonably designed,under the action of the two groups of extrusion rollers,the two edges of the pipe blank can intain close contact within a certain distance,so as to meet the welding requirements.