| In order to improve the service life of car, the car body usually adopts the coated steel which is good at corrosion resistance, especially with the largest usage of the galvanized steel. At present, resistance spot welding is the most widely applied connection modes in manufacture of galvanized steel plated vehicle bodies.This paper mainly discusses about the quality of resistance spot welding which takes the measure of DX54D+Z cold-rolled galvanized steel which adopts the experimental methods of single factor rotation, orthogonal experiment and variance analysis. Furthermore, this paper combines the modern test analysis technique, which is mainly about the impacts on the welding quality from the parameters of spot welding, welding technology parameters of different welding materials, the choosing of electrode cap in spot welding and the application of current gain compensation method. The main conclusions are as follows:(1)The test used assembly of two or three layers sheets ,in the precondition of the nugget forming in the welding joint area, the former of main influence factor is welding time and the latter is welding current, the former of secondary influence factor is welding current and the latter is welding time, both of the weakest is welding stress. The best welding technology parameters of the two: the welding time is 12Cycles for both, the former of welding current is 11kA and the latter is 12kA, the welding stress are 2.1 kN and 2.3kN respectively.(2)With the different thickness of the reference plate forming current value of qualified welds and the maximum current which does not produce splash to produce the welding current window which fits the thickness of reference plate in 0.6mm to 1.5mm. When the thickness of reference plate is more than 0.6 mm, the density of the welding current must be greater than 275A/mm2 can ensure the quality of welding spot. Moreover, each increase by 50% of galvanized layer coverage of the steel plate surface, the welding current should be increased by 15% or so.(3)The electrode of Dispersion Strengthened Copper(DSC) is a relatively better selection for the robot welding. However, the electrode of Chrome Zirconium and Copper(Cr-Zr-Cu) is relatively better for artificial spot welding. Only in view of electrode life span, the models of P911-310-112 are the highest, whose materials are chromium zirconium and copper.(4)Through the usage of current gain compensation control method maps accurate current steps curve which limits the amount of wear of the two kinds of electrode caps'diameter within 1.5mm and 1.8mm, the diameter of melt nugget of the welding spot is greater than 4mm, the welding quality is stable and reliable, and that the performance of solder mechanics is good. At the same time, it can ensure the beat of the line beat. When the qualified solder is arriving, the electrode cap can still continue to be used after grinding which is better than the original current step curve. Not only the qualified rate of the welding spot reaches over 99%, but also the life span of electrode cap of oxidation of aluminum which is copper material will be increased, which reduces the cost of production.
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