The straight seam steel pipe is a steel pipe with a longitudinal parallel of welding seams and steel pipes. It is generally divided into public welding steel pipes, welding thin wall pipes, transformer cooling oil pipes, and so on. The production process of straight steel pipes is simple, high production efficiency, low cost, and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight seam steel pipe. The welded pipe with a large pipe diameter can be produced with a narrow square billet. The steel pipes of different pipe diameters can be produced at the same square billet width. The weld length increased by 30 % and 100 %, respectively, and the production speed was lower.
Stranding steel tube pre -welding quality: pre -welding quality includes the quality of the joints and the quality of the weld.
1. The seam (that is, the formation seam) without error or the wrong edge is less than the specified value. Generally, it specifies that the error edge amount ≤ is 8 % of the thickness of the steel plate, and the maximum does not exceed 1.5mm.
2. To ensure that the welded seams have a suitable melting depth and melting amount, not only must it ensure that there is no cracking after the welding, no combustion, but also control the height of the weld.
3. Welded welds continuously and good for molding to ensure the final external welding quality.
4. There are no defects such as welding deviation, pores, cracks, scum, burning, and welding tumors on the back of the weld.
5. No arc burns, small splash, does not affect the tank end and surface quality.
6. Welding seams match the mother material, and the physical and chemical performance of welding metal meets the quality requirements.
The molding method of manufacturing large -caliber straight sewing pipes includes rolling roller molding method (CFE), UOE molding method, CE molding, etc. For most molding methods, the last process is The shape and quality of the steel pipe has become an important process for ensuring the quality of the finished pipe in a large -caliber straight seam welded pipe. The diameter is a kind of pressure machining technology that uses hydraulic or mechanical means to perform force from the inner wall of the steel pipe to expand the steel pipe along the radial direction. The mechanical method is simpler and efficient than the hydraulic method. It adopts the expansion process of several large -caliber straight seam welding control pipelines. The mechanical diameter is to use the segmented fan -shaped block of the end of the diameter to expand it. Classified plastic deformation of the entire tube length.
1. It is the initial circular stage. The fan -shaped block kept opening until all the fan -shaped blocks were in contact with the inner wall of the steel pipe. At this time, the radius of the round tube in the steel pipe was almost the same within the step size range, and the steel pipe was preliminary.
2. Name inner diameter stage. Fan -shaped blocks start from the front, until they reach the required position, which is the Zhouxiang position of the quality requirements of the quality requirements.
3. Elastic recovery compensation stage. At the position of the second stage, the fan -shaped block will be further reduced until the required position, that is, the round position of the elastic front steel pipe required by the process design.
