The following is a brief analysis of the various functions of sheet metal processing.
Connection: Many products need to be assembled, but the assembly needs to be connected. There are many ways to connect, such as welding, pull (screw) riveting, and hole riveting. Welding is relatively common. Welding includes spot welding, argon welding, etc. The following focuses on spot welding. After the weldment is assembled, pressure is applied through the electrode, and the resistance heat generated by the contact surface and the nearby area of the current joint is used for welding. Aluminum and iron, aluminum and copper, stainless steel and tinplate can all be mixed welding, but spot welding of aluminum and aluminum is difficult. The total thickness of spot welding must not exceed 8mm. The size of the solder joint is generally 2T+3 (2T means the material thickness of the two weldments). Since the upper electrode is hollow and cooled by cooling water, the electrode cannot be reduced indefinitely. The minimum diameter Generally, it is 3 to 4 mm. Spot welding workpieces must be in contact with each other on a certain side of the welding points, in order to increase the welding strength, usually the size of the welding point is φ1.5~2.5mm, and the height is about 0.3mm. The thicker the weldment, the greater the center distance between the two solder joints. If the weldment is too small, overheating will make the workpiece easily deformed. If the weldment is too large, the strength will not be enough to cause cracks between the two workpieces. Usually the distance between the two solder joints is not more than 35mm (for materials below 2mm ). The gap between the two workpieces before spot welding is generally not more than 0.8mm. When the workpiece is bent and then spot welded, the position and height of the row of welding points are very important at this time. If improperly, the spot welding is prone to dislocation or deformation, resulting in relatively large errors. Big.
Argon welding: arc welding using argon as a shielding gas. Clamping fixtures must be used for positioning. The heat generated by argon welding is extremely large, which makes the workpiece easy to deform, while thin materials are more likely to burn out. Aluminum and aluminum alloy have low melting point, low strength and shape at high temperature, burn through due to accidental welding, and weld bead on the weld surface. If two aluminum materials are welded on the plane, a salad hole is usually punched on one side to enhance the welding strength. If it is a long seam welding, the segmented spot welding is generally carried out, and the length of the spot welding is about 30mm (metal thickness 2~5mm). When welding iron materials, if two workpieces are welded vertically, consider opening process positioning holes and positioning openings on the two workpieces respectively, so that it can be positioned by itself, and the port cannot exceed the thickness of the other workpiece, and it can also be punched and positioned. Point to position the workpiece and clamp the welded area with a fixture to prevent the workpiece from being affected by heat and causing inaccurate dimensions.
Pull stud riveting: Pull the two parts with through holes with a stud gun through the pull studs, and pull the rod until it breaks, so that the outer stud sleeve expands and becomes larger, so that it becomes a non-detachable connecting body. Pull studs are divided into flat head and round head (also called umbrella). For the riveting of flat-head studs, the side contacting the stud head must be a salad hole, and the contact surfaces of round-head studs are flat. The distance between the center of the stud hole and the edge is more than 2 times the size of the stud hole, at this time, the riveting strength is the best, if it is too small, the strength will be greatly reduced.
