In general, the customer's drawing has clearly identified the welding methods and requirements. Is welding or spot welding used? How long is the weld? Section size? However, in some cases, for example, we may feel that it will burn. When welding to spot welding is better, the customer can confirm the change of welding method.
1.Process requirements for spot welding:
(1) The total thickness of spot welding must not exceed 8mm. The size of the welding spot is generally 2T + 3 (2T represents the material thickness of the two weldments). Because the upper electrode is hollow and cooled by cooling water, the electrode cannot be unlimited. Reduced, the minimum diameter is generally 3 ~ 4mm.
(2) The spot welded workpiece must be punched out on a certain surface in contact with each other to increase the welding strength. Generally, the size of the row welded spot is Φ1.5 ~ 2.5mm and the height is about 0.3mm.
(3) The distance between two welding points: The thicker the weldment, the larger the center distance between the two welding points. If it is too small, the workpiece will be easily deformed by overheating, and if it is too large, the strength will not cause cracks between the two workpieces. Usually the distance between the two welding points. No more than 35mm (for materials below 2mm).
(4) Weldment gap: The gap between the two workpieces before spot welding generally does not exceed 0.8mm. When the workpiece is spot-welded after bending, the position and height of the welding spot is very important at this time . If not, spot welding Easily misplaced or deformed, resulting in large errors.
(5) Defects in spot welding:
破损工件的表面, 焊点处极易形成毛刺须作抛光及防锈处理。 ①, the surface of the damaged workpiece, the burr easily formed at the solder joint, must be polished and anti-rusted.
点焊的定位必须依赖于定位治具来完成, 如果用定位点来定位其稳定性不。 ② The positioning of spot welding must rely on the positioning fixture to complete. If the positioning point is used to locate its stability. .
2, argon arc welding: arc welding with argon as a shielding gas.
(1) The heat generated by argon welding is particularly large, which has a great impact on the workpiece, making the workpiece easily deformed, and the thin material is more likely to burn out.
(2) Welding of aluminum materials: Aluminum and aluminum alloys have low melting points, low strength and shape at high temperatures, and welding accidentally burns through and weld bumps appear on the surface of the weld. If two aluminum materials are welded on a plane, they are usually included in it. One side punches the welding hole to enhance the welding strength. If it is long seam welding, it is generally performed by spot welding. The length of the spot welding is about 30mm (metal thickness 2mm ~ 5mm).
(3) Welding of iron materials: When two workpieces are welded vertically, consider opening process positioning holes and positioning holes on the two workpieces so that they can be positioned themselves. And the port cannot exceed the material thickness of the other workpiece. Punching the positioning points to position the workpiece and clamp the welded place with a clamp to prevent the workpiece from being affected by heat and causing inaccurate dimensions.
(4) argon arc defects: argon arc welding easily burns out the workpiece, resulting in gaps. The welded workpiece needs to be ground and polished at the welding place.
When the work piece interferes with the development or the work piece is too large, it can be considered (in consultation with the customer) that the work piece is divided into several parts and then overcome by argon arc welding to make it welded into one body.
3.CO2 protection welding
(1) Generally suitable for welding of steel with a thickness of more than 2mm, such as low melting point metals such as aluminum, tin, zinc, etc. cannot be used.
(2) Common defects of CO2 shielded welding are: cracks, unfused, pores, unwelded, slag inclusion, splash, large penetration, etc.
4. Notes on welding:
(1) All thin plate structural parts with t≤2mm can only be welded by argon arc welding or CO2 shield welding.
(2) All welding parts that affect the appearance must be polished smooth and flatness ≤ 0.1 after external welding except for special requirements; welds that do not affect the appearance should also be polished when the weld is 1.5mm higher than the plane; inside corners Welding slag and spatter are not allowed; sharp corners at the outer corners should be ground to rounded corners ≤ R2.