Simulation Study On Porosity And Cracks In Remanufacturing Forming Of Heavy-Duty Engine Cylinder Head

The remanufacturing technology is to prepare the cladding layer on the damaged surface through the advanced surface technology of the parts that cannot be used in the waste products,so that the quality reaches or exceeds the original performance.The heavy-duty engine cylinder heads currently used in heavy-duty,high-torque heavy-duty vehicles often have cracks that make them unusable,and people generally scrap them directly.However,after remanufacturing technology is used to repair these used cylinder heads,they can continue to serve,greatly extending the service life of the cylinder heads,and exerting its maximum engineering application value.The heavy-duty engine cylinder head material is gray cast iron,with high carbon content,and it is easy to produce quality problems such as porosity and cracks when remanufacturing the cladding,which has become a research hotspot.In recent years,people have mainly optimized the regulation of remanufacturing repair processes to reduce the occurrence of porosity and cracks,such as preheating the substrate;using powders with different particle sizes or adding different types of elements to the powder;adding some auxiliary measures during cladding.Through these studies,although a large number of research results have been obtained and applied to engineering practice,the effect of remanufacturing is still unsatisfactory.In order to minimize the occurrence of porosity and cracks,it is necessary to reveal the generation process and mechanism of porosity and cracks.Understand the influence of molten pool temperature and substrate preheating on porosity and cracks,so as to provide a theoretical basis for gray iron plasma cladding,in order to solve the quality problems of cylinder head remanufacturing.To this end,this paper aims at the problem of porosity and cracks in plasma cladding of heavy-duty engine cylinder heads.First,based on the study of the influence of working current,scanning speed and nozzle distance on the quality of the cladding layer,the porosity and cracks in the cladding layer were analyzed.Then use Fluent and Workbench software to analyze the influence of the molten pool temperature and the substrate preheating temperature on the porosity and cracks.Through the porosity movement law and stress-strain analysis at the interface between the cladding layer and the substrate,the mechanism of the porosity and cracks is elaborated.Through simulation calculation analysis,the best temperature of the molten pool is 2700K,and the best preheating temperature of the substrate is 800K.This paper explores the mechanism of porosity and cracks in the cladding layer,which provides assistance for the research of plasma cladding technology,and also promotes the further development of remanufacturing technology,contributing to the development of low-carbon economy and circular economy a strength.