| The requirements of the lightweight and energy-saving environmental protection for cars and ships become higher and higher in the modern society in the 21 st century.The low-pressure casting are widely used in automotive,aviation, marine, etc. fields,because of its products have many advantages such as fewer casting defects and tissue density and so on. The low-pressure casting method has been widely used for 30 years and has established a position of one of the important work of law aluminum alloy castings.Especially in the case of the cylinder and the huge role in the casting process, it will continue to be the main low-pressure casting method in the future. It primarily make the liquid metal into the cavity by applying pressure in the liquid metal surface. Relative to gravity casting and pressure casting, molten metal flow more smoothly and without turbulence in the low-pressure casting process. When the cavity is filled with liquid metal,make the casting solidification under greater pressure by rapidly increasing surface pressure,then we can obtain dense castings. So the study of the aluminum alloy and sump in the low-pressure casting process has important significance,also it has certain reference value to the development of the automotive industry.This article for low-pressure casting sump study relies on Chongqing GaoKin Industrial Co., Ltd.The material of sump is A356 alloy. How to design the mold and the process optimization in order to make the production of castings with good surface properties and mechanical properties are the main research directions in this article. In this paper,the three-dimensional modeling for the sump and design the mold have been finished by using the the current mainstream CAD / CAE integration technology.Then finishing the numerical simulation for filling and solidification of the casting process and defect prediction judgment by using Anycasting.And the mold and process optimization are based on these judgments. Finally,the actual production operations which are based on the mold and process optimization verificate the results of the optimization.It realized the combination of casting and computer technology and improve the efficiency of the development of low-pressure die casting, while reducing the rejection rate of the casting.(1) Determined the rational structure of the low-pressure casting mold according to the performance of the low-pressure casting machine.In this article the low pressure die casting mold design of the sump combined sump casting production quality of the product itself and the structural characteristics of its own,mainly including gate design,gating system design, cooling system, exhaust system design, sand system design,resisted institutions and other system design have been finished.Then the whole solid modeling of the mold was finished by using the three-dimensional modeling software UG.(2) Determined the main casting parameters according to the low-pressure casting sump oil pan parameter calculation methods and structural characteristics,such as liter fluid pressure and speed, pouring liquid metal temperature, mold preheat temperature,liquid metal flow rate and dwell time and pressure. The filling process and solidification process of the casting was simulated after importing the low-pressure casting molds andcastings sump into Anycasting as STL format and setting the casting process parameters.Then we predicted casting defects based on the criterion of residual melt modulus, including shrinkage prediction, cracks and other holes and so on. Finally,we completed the actual mold tryout production verification test based on the simulation.It had been found in the testing process that he defect actually appear consistent with the simulation results in order to verify the reliability of the simulation.Then we proposed optimization according to analysis these defects.(3)Achieved mold optimization and optimal parameters optimization in turn.According to the mechanism and location of the defect,we have fulfilled to optimize the mold local repair mode, exhaust system and overflow system.Then re-optimized three-dimensional modeling and carried out simulation verification test.The resulets showed that the mold surface optimized to achieve the effect of reducing certain defects;The orthogonal test was designed by pouring temperature,filling velocity, mold temperature as the factors influencing the quality of casting.From the experiment results the optimal parameters were obtained.The pouring temperature is 650 ℃,the filling velocity is 10cm/s, the mold temperature is 200℃. That is the best process parameter value parameter value at this time.(4) Completed mold dressing and actual production of castings. On the basis of the optimum process parameters, debugging the pressure curve in the low-pressure casting process to ensure the liquid metal flow rate to achieve the best results in each stage. After①charge on paint, ready to die, installation②melting, slag, degassing③casting operation④ mounted gate residue net ⑤ mounted sand core ⑥ blowing air ⑦ compound die ⑧pressurized ⑨ solidified and opened the mold to remove the product to get the final casting.Finaly we tested the quality to see if it reached the the desired effect or not. The results proved that the casting was good and could be mass producted. |
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