Research On The Key Technology Of The Hot Cast Molding Of The Turbocharger

Turbocharger pressure shell has complex shapes and a lot of surfaces, which leads to difficult technology control and easy to produce all kinds of casting defects during the casting. This paper, mainly for the flash and shrinkage problems of casting defects and combining with the method of numerical analysis and experimental verification, conducts process analysis, defect prediction, defect compensation and optimization of process parameters during turbocharger pressure shell casting progress.Firstly, numerical analysis of mold thermal deformation during casting progressis carried out. Under the support of thermal deformation theory, the thermal deformation process of mold simulated by ABAQUS, which excludes the impact of equipment and ensures the reason why pressure shell castings produce flash is that the mold in molding progress deforms uncoordinatedby suffering heat, causing additional clearance on the point surface and the molten metal flowing into mold gap to become flash after cooling.Then, based on simulations, we estimate the location and size of the flash, and compensate for the mold structure, by which, the parting surface after the mold thermal deformation turns into a plane, with no gap and casting flash. Then the experiment of preheating clamping is carried to verify the feasibility of the mold correction method to eliminate the casting fiy edge. Through the actual production of the mold and the trial production, the shell castings with no fly edge are obtained. And it proved that the thermal deformation compensation method is effective.Second, using the control variable method to analyze the influence of preheating temperature and equilibrium temperature of contact on both molten metal and mold interface equilibrium temperature in theory, draw a conclusion: When the pouring temperature and the metal liquid mold cavity mass ratio Mb definite, The positive correlation between the equilibrium temperature and the preheating temperature will eventually tend to a certain value; When the preheating temperature and the Mb definite, the equilibrium temperature was positively correlated with the pouring temperature. In the preheating temperature and pouring temperature are certain. As Mbâ†'0, the equilibrium temperature approximation on the preheating temperature. With the Mb creased, the equilibrium temperature is also increased.With the Mb crease to a certain extent, the equilibrium temperature trend on the casting temperature. The mold temperature field analysis, explore mold preheating temperature and pouring temperature on the influence of die thermal deformation, draw the conclusion: Under certain circumstances, the higher the preheating temperature, the flash is greater; the higher the pouring temperature, the flash is smaller, therefore, in a proper range, selecting preheating temperature as small as possible, pouring temperature as big as possible, the flash will be small.Subsequently, pressure shell of the 3D model is established based on parametric modeling. Through the analysis of casting process of turbocharger pressure shell, regularities of the temperature field and flow field distribution about metal filling and solidification process is obtained. Predict the casting shrinkage defects, based on Porosity criterion and Niyama criterion. According to the principle of the design pouring and casting riser, and the shrinkage distribution of loose defects, put forward the corresponding designing scheme about pouring system and process improvements. At the same time, trial-produce the casting and verify the effectiveness of the scheme through Porosity metallographic tests.Finally, through the analysis of the regular influence of preheating temperature and pouring temperature on the basis of control variable method, it comes into the conclusion as follows: the increase in pouring temperature in a suitable range is conductive to the casting filling and the casting riser feeding; the increase in preheating temperature in a suitable range, and the more reasonable temperature distribution of castings is more is conductive to poured riser for casting feeding. Through the metallographic examination of the porosity in the casting experiment, the correctness of the rule is verified.