In sheet metal processing, in order to prevent welding deformation, when designing the welded structure, not only the structural strength, stability and economy should be considered, but also the sheet metal welding deformation caused by unreasonable structural design should be estimated. Generally, we should pay attention to the following aspects:
1. Reduce the cross-sectional area of the weld, and on the premise of obtaining a complete weld without exceeding the standard defect, use a smaller groove size (angle and gap) as much as possible.
2. Use a sheet metal welding method with less heat input. Such as CO2 gas shielded welding.
3. Use multi-layer welding instead of single-layer welding for thick plate welding as much as possible.
4. In the case of meeting the design requirements, the longitudinal reinforcement rib and the transverse reinforcement rib can be welded by discontinuous welding.
5. For double-sided welding operations, double-sided symmetrical grooves should be used, and a welding sequence that is symmetrical to the axis of the component should be used for multilayer welding.
6. When the thickness of the T-shaped joint plate is large, the butt welding seam with an open groove is adopted.
7. Use the anti-deformation method before welding to control the angular deformation after welding.
8. Use a rigid fixture fixing method to control post-welding deformation.
9. Use the reserved length method of components to compensate for the longitudinal shrinkage and deformation of the weld. Such as an H-shaped longitudinal weld can be reserved 0.5~0.7 mm per meter.
10. For the distortion of long components, it is mainly to improve the flatness of the plate and the accuracy of a component assembly to make the groove angle and clearance accurate. The direction of the arc is accurate so that the angle deformation of the weld and the longitudinal deformation of the wings and webs are consistent with the length of the member.
11. In the assembly welding or structural installation of components with many welds, a reasonable sheet metal welding sequence should be adopted.
12. When welding thin plates, use underwater welding. That is, the molten pool is surrounded by shielding gas in the water, and the nearby water is completely removed by the gas to ensure normal welding. Using this method, the metal around the solid molten pool is cooled by water in time, and the amount of deformation is controlled to a small extent (the heat generated by the welding is taken away by adding a circulating coolant on the opposite side of the welding side).