1. Cracking at the R-Corner
1.1. Material Selection and Quality Control
Selecting high-quality materials: Ensure that the selected square tube materials meet quality standards and avoid using hot-rolled plates with original cracks or excessive inclusions.
Strengthening material testing: Conduct rigorous testing before materials are stored, including chemical composition analysis and metallographic structure observation, to eliminate potential quality issues.
1.2. Production Process Optimization
Improving welding processes: For welded square tubes, optimize welding parameters such as current, voltage, and welding speed to ensure weld quality and reduce the risk of welding stress and crack formation.
Optimizing bending processes: Reasonably control the bending angle and force during bending to avoid excessive stress concentration at the R-corner. Consider using multi-pass bending or pre-bending to distribute stress.
Heat treatment: For square tubes requiring heat treatment, strictly control heating temperature and soaking time to prevent material performance degradation or new crack formation due to overheating.
1.3. Design and Structural Improvements
Enhancing the R-corner structure: When designing square tubes, consider adding reinforcing ribs or using thicker materials at the R-corner to improve its strength and stiffness, reducing the risk of cracking.
Optimizing force distribution: Optimize force distribution by reasonably designing the support structure and connection method of square tubes to reduce stress concentration at the R-corner.
1.4. Post-Processing and Maintenance
Surface treatment: Apply surface treatment to square tubes, such as sandblasting and painting, to improve their corrosion resistance and fatigue resistance.
Regular inspection and maintenance: Regularly inspect and maintain square tubes during use to promptly identify and address defects such as cracks, preventing issues from escalating.
2. Twisting
2.1. Production Process Optimization
Rotating wheel operation: Reduce the overhang length of thick-walled square tubes on the rotating wheels to a reasonable range (e.g., ≤600mm) to decrease centrifugal force during heat treatment, thereby reducing twisting. Additionally, adjust the rotating wheel speed ratio and core position to ensure stability and uniformity during rotation.
2.2. Equipment Maintenance
Regularly maintain and service production equipment to ensure it is in good condition, avoiding processing errors and twisting due to equipment failure or reduced accuracy.
2.3. Correction Methods
Hydraulic straightening, pressure reverse jacking, heat straightening, manual straightening, etc.
