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Effect Of Welding Time On Spot Welding Machine
Jan 16, 2019

In order to ensure nugget size and weld strength, welding time and welding current can complement each other in a certain range. In order to obtain a certain strength of solder joints, high current and short time (strong condition, also known as hard specification) can be used, but also small current and long time (weak condition, also known as soft specification). The choice of hard or soft specifications depends on the performance, thickness of the metal and the power of the welding machine used. There is a upper and lower limit for the current and time required for metals with different properties and thickness, which shall prevail when used. _4. The influence of electrode pressure_electrode pressure Therefore, the strength of solder joint always decreases with the increase of welding pressure. The solution of spot welding machine is to increase welding current while increasing welding pressure. The effect of current on heat production is greater than that of resistance and time. Therefore, in the welding process, it is a parameter that must be strictly controlled. The main reason of spot welding machine current change is the fluctuation of grid voltage and the change of secondary circuit impedance of AC welding machine. The impedance change is due to the change of the geometry of the circuit or the introduction of different quantities of magnetic metals into the secondary circuit. For DC welding machine, the change of secondary circuit impedance has no obvious influence on the current of workpiece and electrode. The resistance of workpiece depends on its resistivity. Therefore, resistivity is an important performance of the welded material. Metals with high resistivity have poor conductivity (such as stainless steel) and metals with low resistivity have good conductivity (such as aluminium alloy). Therefore, spot welding of stainless steel is easy to produce heat and difficult to dissipate heat, while spot welding of aluminium alloy is difficult to produce heat and easy to dissipate heat. In spot welding, the former can use a small current (thousands of amperes), while the latter must use a large current (tens of thousands amperes). Resistivity depends not only on the type of metal, but also on the state of heat treatment, processing mode and temperature of metal.