When welding defects occur in sheet metal welding bottom box, the repair work needs to be flexibly dealt with according to the defect type, severity and use requirements of the bottom box. From subtle pores and undercuts to more serious cracks and incomplete penetration, each defect has its own cause and corresponds to different repair strategies. Only by accurately judging the root cause of the problem and taking appropriate repair methods can the sheet metal welding bottom box restore its performance and meet the use requirements again.
When pore defects are found in the welding part, the cause of the pores must be clarified first. Porosity is usually caused by the failure of gas to be discharged in time during welding, which remains inside the weld to form cavities. To repair such defects, the welds around the pores must be polished flat with a grinding tool to expose the full picture of the pores. When grinding, pay attention to controlling the depth and range to avoid excessive grinding and damaging the surrounding intact sheet metal structure. After cleaning the impurities and oxides in and around the pores, select a welding rod or welding wire that matches the original welding material, and use a small current and short arc welding method for repair welding to allow the new welding metal to fill the pores. At the same time, pay attention to the discharge of gas during welding to prevent the generation of new pores. After the repair welding is completed, the weld surface is ground and polished again to make it transition naturally with the surrounding welds, ensuring the smooth appearance of the bottom box and not affecting the subsequent installation and use.
In the face of undercut defects, the repair idea is to supplement the missing metal and reshape the weld contour. Undercut is caused by excessive melting of the parent material at the edge of the weld due to excessive current, excessive welding speed or improper welding rod angle during welding, forming a depression. Before repair, the undercut area also needs to be polished to remove the oxide layer and uneven parts at the undercut to form a groove that is easy to weld. According to the depth and length of the undercut, select appropriate welding parameters and gradually fill the undercut area with multi-layer and multi-pass welding. During the welding process, the swing amplitude and speed of the electrode or welding wire must be strictly controlled to ensure that the filler metal evenly covers the undercut area, and pay attention to the fusion quality with the parent material. After welding is completed, the repaired weld is polished and trimmed to make its surface smooth and consistent with the weld height of other parts of the bottom box, eliminate stress concentration points, and improve the overall strength of the bottom box.
If cracks appear in sheet metal welding bottom box, it is relatively difficult to repair and needs to be handled with caution. First, the nature and extension of the cracks should be determined. For small surface cracks, stop holes can be drilled at both ends of the cracks to prevent further extension of the cracks. Then, a suitable groove is made along the direction of the crack. The angle and depth of the groove should ensure that the cracks can be completely removed and good fusion conditions can be provided for welding. Select welding materials with good crack resistance, and use segmented back welding and multi-layer multi-pass welding methods for repair. After each section is welded, hammer the weld in time to release the welding stress. For penetrating cracks or long cracks, it may be necessary to add reinforcement plates inside or outside the bottom box, and weld the reinforcement plates to enhance the structural strength of the bottom box and compensate for the performance loss caused by the cracks. After the repair is completed, the repair area needs to be inspected to ensure that the cracks are completely eliminated to avoid safety hazards.
Incomplete penetration defects will seriously weaken the connection strength of the sheet metal welding bottom box. The incomplete penetration part needs to be completely removed during repair. By grinding or machining, the weld parts that are not fully welded are processed into grooves with a certain angle until the root of the weld is exposed. Reselect appropriate welding process parameters, use a larger welding current and a slower welding speed to ensure that the root of the weld can be fully fused during welding. During the welding process, pay attention to the state of the molten pool to ensure that the penetration depth meets the requirements. If necessary, use swing welding or add filler metal to increase the fusion area of the weld. After welding is completed, the repaired weld is visually inspected and strength tested to confirm that the incomplete penetration defect has been effectively repaired and the bearing capacity of the bottom box has returned to normal.
Welding deformation is also one of the common defects, which will affect the dimensional accuracy and installation adaptability of the sheet metal welding bottom box. For slight deformation, mechanical correction methods can be used, such as using tools such as presses and jacks to apply external force to the deformed parts to restore them to their original shape. During the correction process, pay attention to controlling the strength and correction direction to avoid new deformation or damage to the surface of the bottom box. For more serious deformation, it may be necessary to combine flame correction or heating correction methods. Use flame or heating equipment to locally heat the deformed part, so that the metal material will produce plastic deformation under the action of thermal expansion and contraction, and then restore the bottom box to the correct shape by external force assistance or natural cooling. After the correction is completed, the bottom box is fully inspected to ensure that it meets the design requirements.
After the repair is completed, in order to ensure the quality and service life of the sheet metal welding bottom box, the repaired part must be post-processed as necessary. The first is surface treatment, grinding and polishing the repaired weld to make its surface finish consistent with other parts of the bottom box to prevent corrosion acceleration caused by surface roughness. For the bottom box that needs rust prevention treatment, anti-rust paint can be sprayed on the repaired part or electroplated to form a protective film to isolate the external corrosive medium. In addition, according to the use requirements of the bottom box, the repaired part can also be sealed, such as applying sealant, to prevent moisture, dust, etc. from entering the bottom box and affecting its function.
Repairing the welding defects of sheet metal welding bottom box is a meticulous and technically demanding job, which requires the comprehensive use of a variety of repair methods and process techniques. From defect diagnosis, repair operation to post-processing, every link cannot be ignored. Only by strictly controlling the repair process can the performance and safety of the sheet metal welding bottom box be ensured, so that it can play a reliable and stable role in practical applications.
