Thermal expansion is a pressure processing technology that uses a four-column hydraulic press or a mechanical method to adjust the speed from the inner wall of the seamless steel pipe so that the seamless steel pipe is expanded along the axis. The mechanical method is simpler and more efficient than the four-column hydraulic method. High, in today's society, many large-diameter straight seam welded pipe expansion production processes have been adopted. The process flow is:
Industrial equipment diameter expansion uses the split arc-shaped block at the end of the diameter expander to expand in the radial direction, so that the pipe material undergoes full-length short plastic deformation along the length direction by servo motor, which is divided into five stages.
Basically in the rounding stage, the sector blocks are opened until all the sector blocks are in contact with the inner wall of the seamless steel pipe. At this time, the radius of each point in the rectangular steel in the seamless steel pipe within the step range is almost the same, and the seamless steel pipe is basically rounded. round.
What is the tensile strength of straight seam welded pipe?
The strength of straight seam welded pipes is generally higher than that of straight seam steel pipes. Welded pipes with larger pipe diameters can be produced from narrow forging billets, or welded pipes with different pipe diameters can be produced from billets of the same width. However, compared with straight seam welded pipes of the same length, the weld length is increased by 30 to 100%, and the production speed is very low. Therefore, most of the larger-sized welded pipes use straight seam welding, while the vast majority of large-diameter welded pipes use straight seam welding.
The basic concept of straight seam welded pipe, straight seam high frequency welded steel pipe, and high frequency welding machine: after the hot rolled steel plate is formed by the forming machine, the surge current and proximity effect of high frequency current are used to heat and melt the edge of the pipe material. Seamless steel pipes are produced by pressure welding under the action of rollers. Features of high-frequency welded steel pipes: The burrs in the electric welding form of ERW welded pipes are all shaved off to the raw material.
The graphic standards are high-precision, high parallelism, uniform thickness, and the alloy composition is uniform after welding after heat treatment. It has the same high crush resistance as seamless steel pipes. The straight seam angle of straight seam welded pipe welding is generally 50-75 degrees. , so the stress field formed at the joint of the straight seam weld is 60-85% of the shear stress of the straight seam welded pipe. Under the same pressure, the thickness of straight seam welded pipes with the same outer diameter can be reduced compared with straight seam steel pipes.
