| Low Pressure Die Casting process is a kind of material shaping method based on Pascal principle by which high precision castings can be got without the need of mechanical machining allowance. The molten metal fills the cavity against gravity under low pressure applying on its’ surface. After the cavity is filled, the pressure increases quickly under which the casting solidifies and crystallize. Lightweight automobile has become the main trend which increasing the application of aluminum alloy on auto. Low pressure die casting is the most common method to product the aluminum alloy castings. Therefore, the researching on low pressure die casting process of aluminum flywheel housing and aluminum alloy material will contribute a lot to the developing of auto industry.The object of our research is aluminum alloy flywheel housing used in auto engine whose material is AlSi11. How to ensure the quality of flywheel housing with good surface and mechanical properties is what we focused on. The article adopted CAD/CAE integration technology and tracked all through the process from mold design to the pouring procedure, achieving the unity of the cast technology and computer technology which shortened the mold development cycle, reduced defective index and saved the cost.(1) The mold and hot box have been designed reasonably based on the combination of the feature of low pressure die casting and the structure of flywheel housing. First, the3-dimensional model of casting has been got with consideration of the pouring position, forming method, part surface, machining allowance, draft allowance and shrinkage factor. Second, we have got the die cavity by using UG and calculated the thickness of the mold. Third, the reasonable pouring system, cooling system, exhaust system, ejection device have been designed. Moreover, we have designed the hot box according to core structure, including sand shooting direction, the position and sectional area of sand blowing nozzle, the structure of hot box and the arranging of heating pipes. (2) The reasonable lifting fluid pressure and velocity, filling pressure and velocity, dwell pressure and time, pouring and mold temperature has been determined according to calculation method of low-pressure casting parameters and structural characteristics of flywheel housing. We imported the low-pressure casting molds and gating system of the flywheel housing into MAGMA, set the casting process parameters and calculated. The effect of mold temperature and pouring temperature on casting quality was discussed using single factor method and the optimal parameters were achieved. The process program was improved by setting chill in the mold for the shrinkage problem which had a good feeding effect. The casting achieved a top-down solidification sequence and got good simulation result.(3) The study of AlSi11material was conducted. The ingredient of Al-Si alloy was adjusted to near the eutectic point by reasonable process of adding silicon to aluminum alloy and melting process using A357alloy and high purity silicon. Tensile test was conducted witht φ8mm standard tensile specimens by permanent mold casting. Using sodium, beryllium and AlTiC compound modification method, aluminum obtained good strength and elongation.(4) The workshop production practices was determined by discussing the problem of all aspects of core making, alloy melting, mold preparation, pouring, casting cleaning and detection. We found the flywheel housing had good surface quality without significant defects such as porosity, shrinkage and crack through X-ray detection and fluorescence detection. And the results of pressure test showed good tightness. Therefore, the flywheel housing can be put into mass production. |
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