Experimental Investigation Of New Vacuum Brazing Technology For Stainless Steel Plate-fin Oil Cooler

The subject comes from the project "low copper stainless steel oil cooler" inZhejiang YinLun Machinery Co., Ltd. According to the project, we firstly do someresearches on the feasibility of brazing production of stainless steel plate-fin oilcooler by replacing the pure copper filler metal with new kinds. The result showsthat Good stainless steel oil cooler plate-fin structure can be brazed when we use thetwo new copper-based filler metal: Cu88SnP and Cu66Mn27Ni7,but because of thelimit of forming,they will increase the assemble difficulty in stainless steel oilcooler production.Alloying elements will evaporate and lose so the meltingcharacteristics will be changed during the slow heating process in low vacuum,resulting in the generation of residues and poor quality plate-fin joints for Cu-Zn-Mn series solder.For the the new iron-based filler metals, using the Fe35Ni20Cr23can produce qualified stainless steel plate-fin oil cooler due to the betterbrazeability of Fe35Ni20Cr23iron-based solder in low vacuum than Fe48Ni20Cr18and Fe60NiCr solder for the plate-fin structure of stainless steel oil cooler.Meanwhile, in the course of this paper, one-side setting filler both-sides formedbrazing seam brazing technology was proposed because the one-side setting fillerboth-sides formed brazing seam phenomenon was found during experiment.Thistechnology can be applied for solder in different series, different thickness anddifferent solder preset modes.In this paper, the research on the mechanism of thistechnology was achieved. It is found that one-side setting filler both-sides formedbrazing seam is a conventional phenomenon including wetting, spreading and gapfilling.The pre-set filler metal take precedence to wet the gap at one side of it whenthe solder melts to liquid, and then the liquid solder at the brazing angle spreadalong the vertical plate surface until it contacts with the another side gap. Then thegap is filled by filler metal under the capillary forces and ultimately the formationof solder joints is achieved.Researches on the feasibility of the production of Y8and Y9stainless steelplate-fin oil cooler with one-side setting filler both-sides formed soldering seambrazing technology show that it is possible to produce this kind of oil coolers usingthe technology.