Exhaust Elbow For High Horsepower Engine With Investment Casting Process

Exhaust elbow is mainly used in special vehicles,ships and other fields of high horsepower engine internal,is a special exhaust parts of high horsepower engine,the study of its production preparation technology,the development and application of China’s high horsepower engine is of great significance.At present,the exhaust elbow manufacturing method is mainly casting,machining,welding molding and other technologies with the production,its manufacturing processes,long cycle,high cost,low product qualification rate.Therefore,the study of the exhaust elbow die casting new process,its production process and reliability has an important impact.The main purpose of this paper is to improve the production process of exhaust elbow,apply the investment casting technology to achieve the overall casting of exhaust elbow,and finally obtain qualified castings.Explore the process using a combination of computer numerical simulation technology and test methods,the use of computer numerical simulation technology simulation analysis of the causes of defects in the casting,optimize the optimal process parameters,combined with the actual production test to get qualified castings,summarized the exhaust bend casting process,the production of exhaust bend class thin-walled complex bent pipe production has a certain application value.First,the structural characteristics of the castings were analyzed to draw a three-dimensional rough drawing,and then the material used in the casting 1Cr20Ni14Si2 was briefly analyzed,and the casting simulation software(Pro CAST2018)was selected in combination with the material and casting structure,and the material for the preparation of the fusion mold casting shell was determined.Then,a variety of pouring systems for exhaust bend castings were designed by using the gate cup capacity replenishment shrinkage method and actual production experience to judge the shrinkage and shrinkage holes and thermal cracking defects of the castings during the solidification process of filling,and to compare and select the optimal pouring system by combining the test results under the initial pouring parameters.Secondly,the influence of different process parameters on the shrinkage and shrinkage and thermal cracking defects of exhaust bends is studied,and the optimal casting process parameters for exhaust bend casting are optimized.Finally,the optimal process parameters were used in the trial production of exhaust bend castings,and qualified castings were produced to summarize the investment casting process of exhaust bend castings.The results were obtained as follows:(1)Two different pouring systems were designed by setting the internal sprue at different locations of the exhaust elbow flange,option 1 set two internal sprue at the largest outer face of the exhaust elbow flange,option 2 set four internal sprue on the four ears of the flange,followed by simulation analysis using the selected initial process parameters,comparing and analyzing the filling and solidification process under the two pouring system options as well as the shrinkage and shrinkage holes of the casting,thermal cracking The two solutions were tested under the initial pouring parameters,and the simulation and test results were combined to determine the optimal pouring system for solution 1.(2)In the study,Pro CAST numerical simulation technology was used to simulate the filling and solidification of the casting process as well as the shrinkage,shrinkage and thermal crack defects on the exhaust bend castings under different casting parameters and shell temperatures.The results show that the selected pouring system scheme I can be filled smoothly under different pouring process parameters,and the filling state is good,no under-pouring and cold separation defects.The pouring system was set up reasonably,and the castings could be solidified sequentially,which effectively reduced the formation of shrinkage holes,shrinkage loosening and thermal cracking defects,but the defects formed on the castings were different.After repeated simulation and optimization for several times finally selected a set of optimal parameters,respectively: 1650 ℃,1.5kg / s,1050 ℃.(3)The optimal process parameters and pouring system were applied to the actual casting test,and the results showed that the casting filling requirements could be met,and the number of shrinkage and shrinkage defects in the casting was low and there were no thermal cracking defects.In addition,the castings generated from the test had good visual surface quality and passed dimensional inspection.The internal quality of the exhaust bend meets the standard and the product is qualified by CT testing.