As the core of the welding operation center, the weldin […]
As the core of the welding operation center, the welding manipulator is widely used in various industries due to the advantages of effectively improving welder labor conditions, improving productivity, and simple operation and low input cost. However, there are always some orders in the welding process. The problem of people's headaches, like welding deformation, is very painful for users. Today, Xiaobian will share with you the causes and precautions of welding deformation and welding stress.
The basic forms of welding deformation include shrinkage deformation, angular deformation, bending deformation, wave deformation and distortion.
Uneven heating and cooling of the weldment during the welding process is the root cause of weld stress and deformation.
The main measures to reduce welding stress and deformation are:
First, reserve the amount of shrinkage deformation. According to the theoretical calculation and practical experience, the shrinkage allowance is pre-considered in the preparation and processing of the weldment so that the workpiece can reach the required shape and size after welding.
Second, the anti-deformation method. According to the theoretical calculation and practical experience, the direction and size of the structural welding deformation are estimated in advance, and then a preset deformation of opposite directions and equal magnitude is given during the welding assembly to offset the deformation caused by the welding.
Third, the rigid fixation method. When welding, the weldment is rigidly fixed, and after the weld is cooled to room temperature, the rigidity is removed, which can effectively prevent angular deformation and wave deformation. This method will increase the welding stress and is only suitable for low-carbon steel structures with good plasticity.
Fourth, choose a reasonable welding sequence. Try to make the weld shrink freely. When welding structural parts with many welds, the short welds that are staggered should be welded first, and the long welds should be welded straight to prevent cracks at the weld joint. If the weld is long, the step-down welding method and the jump welding method can be used to make the temperature distribution uniform, thereby reducing the welding stress and deformation.
5. Hammering weld method. During the cooling process of the weld, the weld is evenly and quickly hammered with a round-headed hammer to plastically deform the metal to offset a part of the weld shrinkage deformation, thereby reducing welding stress and deformation.
6. Heating the “subtraction zone” method. Before welding, the area near the welded part (called the subtractive area) is heated to extend it. When cooling after welding, the heated area shrinks together with the weld, which can effectively reduce the welding stress and deformation.
7. Preheating before welding and slow cooling after welding. The purpose of preheating is to reduce the temperature difference between the weld zone and other parts of the weldment, reduce the cooling rate of the weld zone, and enable the weldment to be cooled more evenly, thereby reducing welding stress and deformation.