Precautions for the production of square and rectangular tubes
1. Selection and inspection of raw materials
The quality of steel: The main raw materials for square and rectangular tubes are hot-rolled or cold-rolled steel strips. High-quality steel that meets national or industry standards must be selected to ensure it has good mechanical properties and ductility. The chemical composition, tensile strength and yield strength of raw materials need to be strictly inspected.
Surface quality inspection: The surface of the steel strip should be free of obvious defects such as cracks, bubbles, rust, etc. The surface quality of raw materials directly affects the effect of subsequent processes such as welding and coating.
2. Cold bending forming process
Bending radius control: In the production of square and rectangular tubes, cold bending forming is a key step. Steel strips must be bent into square or rectangular cross-sections under certain forming pressure. During bending, the bending radius needs to be controlled to avoid excessive deformation, which may cause cracks or depressions on the pipe wall.
Winding accuracy: During the winding process, it is essential to ensure the winding accuracy to guarantee the dimensional stability and uniform shape of the square and rectangular tubes. Excessive deviation may make it difficult to assemble the square and rectangular tubes in subsequent processing, and even prevent them from being used normally
3. Welding Process and Control
Welding method selection: The production of square and rectangular tubes generally adopts high-frequency welding or automatic gas shielded welding (MAG welding). During the welding process, the control of welding temperature and current is of vital importance. Excessively high temperatures may cause the material to overheat, deform or burn through, while excessively low temperatures may result in an insecure weld.
Welding quality control: During the welding process, the width, depth and welding speed of the weld seam should be well controlled to ensure the firmness of the welded joint. After welding, square and rectangular tubes need to undergo weld seam inspection. Common inspection methods include visual inspection, ultrasonic testing and X-ray testing.
Release of welding stress: During the welding process, thermal stress is generated, which can easily cause deformation of square and rectangular tubes. Therefore, heat treatment or straightening is required after welding to reduce internal stress and ensure the stability of the geometric dimensions of the tubes.
