Study On Brazing Of Multiple Parallel Flow Condenser In Controlled Atmosphere Brazing Furnace

With China's rapid economic development, the demand for cars is in fast increase. Automotive air conditioning system as an important comfort factor of vehicle, more car manufacturers and users are paying great attention to it. As condenser is one of the cores of automotive air conditioning system, it's requisite to learn enough about it and make sure it's well performance. Especially the successful production of a condenser with qualified mechanical properties needed on service becomes common focus for engineer in material hot processing engineering. Automotive air condenser is generally produced by brazing in controlled atmosphere brazing (CAB) furnace and then be assembled. A key factor to get quality satisfied condensers after the brazing process is making a good choice on technical parameters. The traditional method is picked up one series of brazing process parameters from a group of experiments that condensers brazing in CAB furnace over and over again, therefore, the production cycle, reasonably leads to high costs and low efficiency. However, finite element analysis gives a probability for more efficiency way on the issue.Based on the basic law of heat transfer in the CAB furnace, considering the brazing process technical parameters of the actual situation, a three-dimensional heat transfer model of air condenser in CAB furnace is established. And a hypothesis of setting temperature in different region in the CAB furnace is premised. Then a simulation brazing thermal cycle curve is obtained. Meanwhile, experiments are launched for the real thermal cycle curve during the brazing process of the condenser in the CAB furnace. The result of simulation and real thermal cycle curve fits well. This indicates that heat transfer model in CAB furnace is correct, plus it proves the setting temperature in the CAB furnace is advisable.Relying on a well-known condenser production base in Chongqing, brazing experiments in the CAB furnace are conducted. The experiments take the SF-X05 type condenser, using process parameters simulated by ANSYS software, access to a range of specimen of products. Then a serious of performance testing experiments such as water pressure test, helium leak testing and SWAAT sea salt spray corrosion testing are carried out. The test results demonstrate that there is no leak in condensers and they are completely gets demand application requirements. In this article, brazing joints between collecting pipe-flat tube, flat tube-fin are simulated. Temperature distribution of brazing joints of condenser during the entire brazing process is computed. There shows a intense temperature variation in the condenser, but in the brazing joints temperature comes more uniform, the maximum surface temperature difference does not exceed 2℃; Comparing the brazing temperature curves in simulation for collecting pipe-the flat tube and flat tube-fin, it can be concluded that both the heating rate and cooling rate of flat tube-fin were greater than collecting pipe-flat tube. The surface maximum temperature difference of condenser in the whole brazing process in CAB furnace is in air cooling region, maximum up to 61℃.By simulation temperature field and thermal cycle curves of brazing joints collecting pipe-flat tube and flat tube-fin of the condenser and brazing experiments, it testifies the use of computer simulation for process optimization is feasible.