Sheet metal processing is generally a comprehensive cold working process for metal sheets with a thickness of less than 6 millimeters, which includes cutting, punching, cutting, laminating, folding, welding, riveting, splicing, and forming processes. Among them, welding is a very important link. There are some issues that need to be paid attention to before, during, and in terms of welding standards for metal welding in sheet metal processing
1, Requirements before welding sheet metal parts:
1. All sheet metal raw materials must not be lower than the drawing requirements, otherwise they cannot be cut and produced.
2. The surface flatness of the welded steel shall not exceed 0.2%, and the total curvature shall not exceed 0.3% of the total length.
Before welding sheet metal parts, all deformed parts must be straightened and leveled before welding can be carried out.
Before starting welding, it is necessary to choose a suitable welding wire, and select welding wires with different thickness specifications according to different parameters such as part size, material thickness, and weld requirements.
2, Requirements for the welding process of sheet metal parts
1. The welding process must be strictly carried out in accordance with the drawings, technology, and process requirements.
2. When welding, it is required to process the groove at the location where the groove is processed. If the processed part does not have a groove or welding profile, a polishing machine or mechanical processing method should be used for groove processing according to the situation.
3. During welding, it is necessary to ensure that the external dimensions and positional tolerances of the workpiece meet the requirements of the drawing. The positional tolerances of non machined surfaces shall be executed according to IT15 level without special requirements.
If material substitution is required during welding, written consent from the technical department must be obtained, and the thickness of the sheet metal must also meet the requirements of the drawing. Otherwise, material substitution cannot be used.
5. The size of the weld seam during welding must strictly follow the requirements of the drawing. If the drawing does not specify the size and length of intermittent welding, welding should be carried out at intervals of 8 to 10 millimeters every 50 millimeters, and the distance between each welding point should be uniform and consistent.
6. Continuous welds must be straight and smooth, without obvious unevenness, welding penetration, welding deviation, welding scar, porosity, undercutting, and other phenomena. The welding angle of the weld shall be subject to the requirements of the drawing, and if there are no requirements, the welding angle shall be guaranteed to be the small thickness of adjacent parts.
After welding is completed, each weld seam should be polished to remove both welding slag and burrs around it.
8. Some parts are not suitable for welding, such as parts that require bending on the drawing, which cannot be welded without the written consent of the technical department.
During the welding process of sheet metal parts, the parts that need to be struck can be lightly hammered with a small manual hammer until the size meets the requirements. Do not use a heavy hammer to strike on the sheet metal surface, otherwise it will cause damage and scrap of the workpiece.
3, Requirements and standards for post weld treatment of sheet metal parts
1. It is required that the weld seam of sheet metal parts be smooth and present a fish scale shape, without any bulging or uneven phenomenon.
2. It is necessary to ensure that the edges of the workpiece are aligned and the surface is flat. After welding is completed, use sandpaper to polish it again, remove the welding slag, welding points, and burrs with sharp edges and corners, and maintain the flatness and smoothness of the weld seam.
On the plane of box type workpieces, the height of the weld seam should not exceed the height of the plane. In principle, after applying putty, the weld seam should be completely covered.
4. For turnover parts and flat surfaces that do not require further processing after welding, strict protection should be taken during welding to avoid arc damage or slag damage, and polishing should not be carried out casually under the premise of uniform weld seam.
5. For metal parts that need to be processed through processes such as blueing and electroplating after welding, sandblasting treatment should be carried out uniformly after welding meets the requirements. During the turnover process, strict protection should be taken to avoid collisions and scratches, and no further polishing treatment is allowed.
