The main function of the oil cooler (referred to as the oil cooler) is to cool the engine lubricating oil, and it is an important spare part of the automobile engine cooling system.Nowadays, vehicle oil coolers mostly use multi-layer densely arranged zigzag staggered fin all-aluminum oil coolers. This type of oil cooler is small in size, light in weight and high in cooling efficiency, but the overall structure of the oil cooler is complex. At the same time, it also has very strict requirements on the sealing performance and corrosion resistance of the oil cooler. To achieve precise and reliable connection between oil cooler and cooling system, the connection method has become a research topic that has attracted much attention.This paper takes the CA type plate-fin aluminum alloy oil cooler as the research object. First, the resistance spot welding process of the top plate structure of the oil cooler and the brazing process of the core body in the Nocolok furnace are established.Secondly, after welding, the macro-morphology, microstructure, microhardness, tensile properties and tearing analysis of the spot-welded joints were carried out respectively, and the influence of different process parameters on the properties of the spot-welded joints was studied. .At the same time, the influence of brazing process parameters on the microstructure of the brazed joint of the oil cooler is studied, and the comprehensive performance test of the oil cooler is carried out, which provides some suggestions for the welding of this type of plate-fin aluminum alloy oil cooler. Theoretical basis of craftsmanship.The experimental research shows that: 1) The spot welding joint is composed of three parts: nugget, plastic ring and base metal, and the nugget belongs to the typical "columnar grain + equiaxed grain" structure.With the increase of current and welding cycle, the equiaxed grain structure in the center of the weld nugget gradually coarsened, the number of columnar grain structure decreased with the increase of welding current, and increased with the increase of electrode pressure.2) The effects of welding current, welding cycle and electrode pressure on the microhardness and tensile load of spot welded joints are different. area of influence.3) When the welding current, cycle and electrode air pressure are 22 kA, 8 cyc and 0.20 MPa, respectively, and the preloading time and holding time are 25 cyc and 15 cyc, respectively, the performance of the spot welding joint reaches the best value, and its average value is significantly higher. The microhardness is 40.64 Hv, and the tensile shear force is 2.103 kN.4) The microstructure of the brazing area is a typical α(Al) solid solution and Al+Si eutectic phase.The optimal process parameters of the brazing process are as follows: the temperature of the six zones is 600℃-605℃-610℃-615℃-620℃-615℃, and the speed of the mesh belt in the brazing zone is 320 mm/min.The comprehensive performance test of the oil cooler was carried out, and it was found that the qualified rate of the product was high and met the requirements of production and use, indicating that the optimal process parameters can be used to guide the actual welding production.
