Wire heating mesh resistance welding machine pneumatic pressurized spot welding machine
Part I: The principle of spot welding and the welding process
The spot welding process is a type of metal joining that forms a permanent bond. During welding the weldment is heated locally by the welding current and pressure is applied to the contact heating of the weldment to form a welded joint. Spot welding is a high speed, economical method of making joints that can be lapped, do not require airtight joints and are less than 5 mm stamped and rolled sheet elements. The spot welding process is now widely used in all sectors of industry to weld not only mild and low-alloy steels, but also high-carbon steels. The parts are made of stainless steel, aluminum alloy, titanium alloy, high manganese steel and other materials.
The choice of welding process parameters: the process parameters affecting spot welding include the structural diameter of the welding electrode, welding energy, welding time and welding Stress. According to the welding speed and welding effect can be divided into rapid welding, medium-speed welding, ordinary welding three conditions, for the workpiece welding strength requirements High, small welding deformation of the occasion, the best choice of high power, short time strong specification rapid welding. For less stringent requirements of the workpiece can be used low-power, long-time ordinary welding methods, so that a smaller welding equipment can be selected. The impact on the grid is also relatively small. Usually selected according to the material and thickness of the workpiece, with reference to the welding condition table for that material, and first determine the shape and size of the electrode end face. After that, the electrode pressure and welding time are initially selected, then the welding current is adjusted, the specimen is welded with different currents, and the melting core is tested. After the diameter meets the requirements, then adjust the electrode pressure, welding time and current within the appropriate range to carry out the welding and inspection of the specimen. Until the quality of welded joints fully comply with the requirements set out in the technical conditions. The most common method of testing specimens is the tear-off method, and quality solder joints are marked by a round hole in one piece of the tear-off specimen and a Round Camber. Thick plates or hardened materials sometimes cannot be torn out of round holes and bosses, but the diameter of the nucleus can be judged by the shear fracture. If necessary, low-fold measurement, tensile test and X-ray inspection are also required to determine the melting rate, shear strength and the presence of shrinkage, cracks and so on. . When selecting process parameters by specimen, the influence of specimens and workpieces in terms of diversion, ferromagnetic substances, and assembly gaps should be taken into account. variances, with appropriate adjustments.
Factors affecting the welding quality of spot welded joints include welding current, electrode pressure, welding time, pre-pressure and resting time, and welding electrode diameter.
