Welding method of spiral steel pipe

Abstract

The invention discloses a welding method of a spiral welded pipe, which is characterized in that an extrusion device is firstly used for extruding the inner surfaces of steel plates at the two sides of a non-welded seam to eliminate uneven bulges and ensure that the inner sides of the steel plates at the two sides of the non-welded seam are clean and smooth, and then welding is carried out. At the same time, the extrusion device further serves as a location device of a welding head, namely, the extrusion device is used for tightly fixing the welding head and the extrusion device together to ensure that the welding head also can correctly move along the non-welded seam when the extrusion device moves along the non-welded seam, and thus, the welding head is ensured to be located at the middle position of the seam all the time. Accordingly, the quality of the seam automatically welded by a production line is guaranteed to be stable and excellent, and manual repair is basically not needed.

Description

technical field [0001] The invention belongs to the technical field of spiral welded pipes, and in particular relates to a method for welding spiral welded pipes. Background technique [0002] Spiral welded pipe is a low-carbon carbon structural steel or low-alloy structural steel strip rolled into a tube blank at a certain helical angle, and then welded to form a steel pipe. Spiral welded pipes are produced continuously in the production line, and submerged arc welding is generally used for double-sided automatic welding, which has higher requirements for weld seams. [0003] However, in actual production, more than 15% of the weld seams automatically welded by the production line do not meet the quality requirements, and have to be repaired manually. Manual shielding gas welding is not only labor-intensive, but also has low efficiency and high cost. [0004] In order to solve the above-mentioned problems, domestic and foreign insiders have done a series of research and e...

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Problems solved by technology

For this reason, the applicant has carried out repeated trials and found that there are two reasons for this problem: one is that the inner sides of the steel plates on both sides of the unwelded weld seam inevitably have some uneven protrusions during the previous process. point, during welding, when the welding wire discharges to the right-angled parts of the steel plate on both sides of the weld, it will cause a tip discharge phenomenon, which makes the current fluctuate, which is not uniform and stable. This is a basic problem affecting the quality of the weld

The second is that the traje

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