ERW Tube Straightness And Roundness Influencing Factors

In recent years, my country's ERW tube mill line production has developed rapidly. According to relevant information, there are more than 1,600 sets of various welded pipe production lines, with an annual production capacity of 7 million tons, and product specifications ranging from 8mm*1mm to 508mm*12mm. wait. However, most of my country's welded steel pipe production lines are small and medium-sized units with low-grade products, mostly water and gas transmission pipes, accounting for about 35% of the total welded pipe production. There are still many gaps compared with industrialized countries. To change this situation, the production of high-quality welded steel pipes must be expanded, such as petroleum pipes, medium and low-pressure boiler steel pipes, mechanical structural steel pipes, pipeline steel pipes, etc. At the same time, the welding quality of welded pipes must be improved.

There are many factors that affect welding quality, mainly including the following aspects:

(1) Quality of tube blanks: The chemical composition, mechanical properties, dimensional deviation, appearance, etc. of tube blanks are intrinsic factors that affect quality.

(2) Welding process parameters: only for high-frequency welding methods, welding power, welding speed, temperature, high-frequency frequency, welding extrusion force, resistor matching, triangle area control, etc. can all affect the welding quality affect.

(3) Forming process: The hole design and adjustment method of the forming part of the welded pipe unit will directly affect the quality of welding.

This article will focus on introducing and analyzing the advantages and disadvantages of different forming process methods and their impact on the quality of welded pipes.

Welding requirements for forming:

At present, most of the welded pipe production units use high-frequency welding technology. Only for pipes made of carbon steel, alloy steel, stainless steel or some special materials with special requirements, gas shielded welding, submerged arc welding, plasma welding, electron beam welding, etc. are sometimes used. Laser beam welding, etc.

Most high-frequency welding uses high-frequency induction welding. In order to obtain a good weld seam from welded steel pipe, the prerequisite is that there must be an ideal forming process. The ideal forming state is that after the strip is formed, the edges on both sides are parallel and the gaps are equal. Due to the high-frequency current skin effect and proximity effect, the current passing through the edge is the same, so that the inner and outer sides of the steel strip thickness reach the same temperature. After extrusion, the welding is good, and the inner and outer burrs are uniform.