Resistance projection-welding hybrid connecting method and system

Abstract

The invention provides a resistance projection-welding hybrid connecting method and system. The resistance projection-welding hybrid connecting method comprises the following steps that (1) a metal hemisphere is arranged on the surface of one of two to-be-connected workpieces through arc welding; (2) to-be-connected parts of the two to-be-connected workpieces are placed between an upper electrodeand a lower electrode of a resistance projection-welding device, wherein the metal hemisphere is located between the two to-be-connected workpieces as well as between the two electrodes; (3) the two electrodes move relatively by delta to complete pre-pressing within a time T1, so that the two to-be-connected workpieces are in good contact at the position of the metal hemisphere; (4) a current I1 is applied to the space between the two electrodes so as to make the two electrodes move relatively by delta within a time T2; (5) a current I2 is applied to the space between the two electrodes for atime T3 with the positions of the electrodes kept unchanged, wherein I2>I1; and (6) the current between the two electrodes is cut off, and pressure-maintaining cooling is conducted within a time T4. According to the resistance projection-welding hybrid connecting method and system, the process is simple, operation is easy and convenient, the energy-saving effect is remarkable, and the life of theelectrodes is prolonged; the probability of material softening in a heat-affected zone of a joint is lowered, surface indentations of the connected workpieces are obviously reduced, and the method andsystem are suitable for connecting different materials; and the strength of the joint is remarkably improved, and polishing cleaning of oxide films on surfaces of the materials is not needed.

Description

technical field [0001] The invention relates to a technique in the field of welding, in particular to a resistance projection welding composite connection method and a system thereof. Background technique [0002] Resistance spot welding has become the most important connection technology for automobile body assembly due to its advantages of high efficiency and easy automation. However, for the connection of light metals and heterogeneous metals, the traditional resistance spot welding process has obvious shortcomings: the surface of the plate needs to be oxidized before connection. The film is specially treated to improve the weldability; commonly used light materials, such as aluminum alloy, have the characteristics of high thermal conductivity and fast heat dissipation, so that a large current of about 30kA ~ 55kA must be used during welding, and the energy consumption is large; large current The input makes the chemical reaction between copper and light metals and their ...

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Problems solved by technology

[0003] The present invention aims at defects in the prior art that often involve additional coatings so that the cost is high, or that the addition of iron-based alloys leads to an increase in quality, and the additional coatings will also increase the complexity of the manufacturing process, etc., and proposes a resistance projection welding composite connection method and its system

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