Common problems and solutions in seamless steel pipe bending

Seamless steel pipe bending is a key process in pipeline processing, widely used in oil, natural gas, construction, automotive and other industries. However, in actual operation, the bending process often encounters various problems, such as steel pipe cracking, wrinkling, Angle deviation, etc. These problems not only affect product quality, but also may increase production costs. This paper will analyze the common problems in seamless steel pipe bending in detail, and provide effective solutions. Description: In the bending process, the outside of the steel pipe is subjected to tensile stress, if the bending radius is too small or the bending speed is too fast, it may cause the outside material to crack. 1. Increase the bending radius: according to the diameter and wall thickness of the steel pipe, choose the appropriate bending radius, usually not less than 2-3 times the diameter of the steel pipe. 2. Reduce the bending speed: slow down the bending speed, so that the material has enough time to adapt to the deformation, reduce the concentration of tensile stress. 3. Use hot bending method: For steel pipes with large wall thickness or high strength, hot bending method can be used to heat them to the appropriate temperature and then bend them to reduce the brittleness of the material. 4. Use lubricant: Apply lubricant to the bending area to reduce friction and prevent over-stretching of the material. Description: When bending, the inside of the steel pipe is subjected to compressive stress, if the wall thickness is thin or the bending radius is too small, it may cause the inside material to wrinkle. Solution: 1. Use a mandrel support: Insert a mandrel inside the steel pipe to support the inner material and prevent wrinkling. 2. Increase wall thickness: For thin-walled steel pipes, the wall thickness can be appropriately increased to improve the pressure resistance. 3. Adjust the bending radius: appropriately increase the bending radius to reduce the inner compressive stress concentration. 4. Section bending: For large Angle bending, section bending can be used to complete the bending process step by step.

Three, common problem 3: Bending Angle deviation problem description: After bending, the Angle of the steel pipe is not consistent with the design requirements, which may be due to insufficient equipment accuracy or improper operation. Solution: 1. Calibration equipment: Check and calibrate the bending equipment regularly to ensure that its accuracy meets the requirements. 2. Control bending parameters: set bending Angle, speed and pressure accurately according to steel pipe material and size. 3. The use of numerical control equipment: the use of numerical control bending machine, to achieve high precision bending, reduce human error. 4. Multiple measurement: In the bending process, use the Angle measurement tool to check and adjust in time. Four, common problem 4: steel pipe ellipticity or flat problem description: After bending, the cross section shape of the steel pipe changes, and the phenomenon of ellipticity or flat occurs, affecting its performance. Solution: 1. Control the amount of deformation: Avoid bending at one time too large Angle, using multiple bending, gradually complete. 2. Use mold support: Use mold support in the bending area to keep the shape of the steel pipe stable. 3. Adjust the bending force: according to the material and wall thickness of the steel pipe, reasonably adjust the bending force to avoid excessive deformation. 4. Follow-up shaping: For the steel pipe that has been elliptical or flat, the shape can be restored by shaping process. 5, common problems 5: Surface damage problem description: During the bending process, the surface of the steel pipe may appear scratches, indentation and other damage, affecting the appearance quality. Solution: 1. Use protective devices: Install protective pads or protective covers in the bending area to avoid direct contact with hard objects. 2. Clean the working environment: Ensure that the bending equipment and steel pipe surface is clean to prevent scratches from impurities. 3. Control bending force: Avoid bending force is too large, resulting in surface indentation. 4. Follow-up treatment: For the damaged surface, it can be repaired by polishing or spraying process. 6, common problem 6: internal stress concentration problem description: After bending, the internal stress of the steel pipe may remain large, resulting in deformation or cracking in subsequent use. Solution: 1. Heat treatment to eliminate stress: annealing or tempering the steel pipe after bending to eliminate internal stress. 2. Natural aging: Place the bent steel pipe for a period of time to release the stress using natural aging. 3. Optimized bending process: sectional bending or hot bending method is used to reduce internal stress concentration. 4. Follow-up testing: Use non-destructive testing technology (such as ultrasonic testing) to check the internal stress distribution of the steel pipe and deal with it in time.

There are a variety of common problems in the bending of seamless steel pipes, but through reasonable process optimization and technical improvement, these problems can be effectively solved to improve product quality and production efficiency. In actual operation, it is necessary to select the appropriate bending method and parameters according to the material, size and use of the steel pipe to ensure the smooth bending process. In the future, with the development of intelligent equipment and green manufacturing technology, the seamless steel pipe bending process will be more efficient and accurate, and provide better products for various industries.