The Study And Applicastion On Thermal Deformation Compensation Technology Of Low-pressure Casting Die For Aluminium Alloy Wheel

As well known, Aluminum has been widely used in automotive industry, which has many advantages, such as good appearance, long duration, light-weight, good heat dissipation, high resistance to corrosion and excellent mechanical properties, etc. However, thermal deformation of the die occurs during casting process of Aluminum alloy wheel, leading to the interference of die assembling,larger edge, seriously over proof of the front rim depth for a wheel and thicker part in rim area, etc.By the methods of both microstructures analyzing on vary of area from the dies before and after failure, and the finite element simulation software ANSYS simulating and analyzing the low pressure casting die of Aluminum alloy wheel under thermal state, this paper shows that bottom core has a tendency of expansion outward when heated, the intermediate support parts of the bottom core come into being compressive deformation and bulging upward, the gap appears at both top and bottom areas of side core respectively and the gap at the top area between fitting surfaces of side core in 45 degree is larger than that of the bottom part, and then the thinner in the middle of the wheel.The solution is made according to the result of both thermal deformation simulation and microstructures analyzing. For integrated side core, gradually varied compensation of 0~0.2 mm is adapted on the key areas in larger deformation parts on the 45 degree surface of the lateral. A certain fit clearance is adapted to the 45 degree surfaces of the lateral in cold state, which reserves a certain degree of freedom for thermal deformation. The divided water-cooling side cores are quite special since the contraction of the water-cooling part is severe. Based on this, gradually varied compensation of 0~0.2mm is only adapted on the key areas on the 45 degree surface of non-water-cooling part of the side, rather than the 45 degree surface of the fission cool-water part of the lateral. In order to offset the side core deformation of the central arc transfers to the center under thermal state, the eccentric milling of 0.15~0.45 mm is adapted on the central arc of the surface under cold state. For integrated side core, eccentric milling is made on both top and bottom area of side core. And if two divided side core, only bottom area. A certain clearance is set between the bottom core and the lower plate in order to give a certain freedom for the bottom in thermal deformation.After improvements, the local interferences between the dies after thermal deformation are avoided, the fit quality and the lifetime of the die are promoted, the depth of the frontal rim is improved significantly, the dimensional accuracy of wheel is promoted, the edge is reduced, the wall thickness of the rim trends to be stable, and the cost will be reduced significantly, and thus the comprehensive benefits are improved.