| Investment castings have the advantages of high dimensional accuracy,high surface quality and high geometric accuracy,and are widely used in various fields of industrial production.At present,there are relatively few references for the study of the filling process of wax pattern.There is no data platform for the filling process of wax pattern,and there is no universal parameter data to guide the actual production.Therefore,this paper takes the structure size and filling process parameters which affect the filling quality of wax mold as the breakthrough point,takes three typical wax molds as the research object,uses the method of combining software simulation and experimental verification to complete the visualization research of wax mold filling,and obtains the general process parameters which can guide the actual production of wax mold.The specific conclusions are as follows:Firstly,three kinds of typical wax patterns(plate,cylinder and column)in investment casting were selected as the research objects.The filling characteristics of wax molds with different structures were analyzed,and the influence of structure size on the filling quality of wax molds was studied.The defects and the location of defects in the filling process of wax molds with different structures were predicted.On this basis,the typical wax die structure size was selected as plate wax pattern200*100*10 mm,cylinder wax patternΦ150*100 mm and wall thickness 6 mm,column wax patternΦ20*200 mm.Then,by controlling a single variable,the influence of filling process parameters on the filling quality of three typical wax patterns was studied by Moldflow software system.Comprehensive simulation results and engineering practice experience,the initial selection of the plate-shaped wax mold reasonable filling process parameters range of injection wax temperature 56℃-60℃,mold temperature 20℃-24℃,wax injection speed 50 cm~3/s-120 cm~3/s,the holding time was 30 s-40 s;the cylindrical wax mold was the wax temperature of 56℃-60℃,the mold temperature was 20℃-24℃,the wax injection speed was 50 cm~3/s-120 cm~3/s,the holding time was 25 s-35 s;the columnar wax mold was the wax temperature of 56℃-60℃,the mold temperature was 22℃-26℃,the wax injection speed was 50 cm~3/s-120 cm~3/s,and the holding time was 25 s-35 s.Then orthogonal experiment was designed to optimize the process parameters of filling by range analysis with the deformation defect of wax mould as the optimization index:the plate wax pattern was the wax temperature of 58℃,the mold temperature was 20℃,the wax injection speed was50 cm~3/s,the holding time was 40 s;the cylindrical wax mold was the wax temperature of 60℃ The mold temperature was 20℃,the wax injection speed was120 cm~3/s,and the holding time was 35 s.The column wax mold was the wax injection temperature of 56℃,the mold temperature was 22℃,the wax injection speed was 50 cm~3/s,and the holding time was 30 s.Finally,this paper chooses the core section of a super-large thin-walled missile shell wax model(hereinafter referred to as"missile body")to verify the general filling process parameters.Combining with the super-large thin-walled wax mold forming technology,the projectile structure was designed,the wax mold forming scheme was determined,and the complete wax injection process was designed.The range of the initial process parameters of three typical wax molds was analyzed.The results showed that the universal filling parameters ranged from 56℃-60℃ for wax injection temperature,22℃-24℃ for wax injection speed,50 cm~3/s to 120 cm~3/s for mould temperature,and holding time 30 s-35 s.The simulation filling and physical filling validation were carried out by using the projectile wax mold.The results show that the universal filling process parameters can effectively guide the actual production and obtain wax models with good comprehensive quality.On this basis,the rules of selecting the optimal combination of parameters from the range of universal parameters for wax pattern with specific structure are summarized. |
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