Study On Drilling Property Of High Strength Gray Cast Iron Processed By Inoculation Treatment

Auto manufacturing is a pillar industry for Jilin Province, which are playing a key role in the revitalization of old northeast industrial bases for the tactic of national economic development, and during the revitalization of the economic development for Jilin Province, it account for an extremely important position. As the rapid development of China's highway, there are an increasing demands for heavy trucks. Usually, engines of heavy-duty truck are high powered, more than 300 horsepower, which are the heart of heavy-duty trucks. At present, FAW Group has invested over one billion yuan to built new production line to manufacture the engine. The high-powered engine cylinder block is the key parts of the engine, therefore, FAW Group Foundry Co., Ltd. has been building a production blank of the engine block production line which invested 100 million yuan. It can be clearly seen that high horsepower engine is the block production for heavy-duty trucks, rough localization of the bottleneck. As engine horsepower engine required a large body tensile strength greater than 240MPa, it requires ultimate tensile strength greater than 300MPa. However, such a high strength cast iron bound to bring the problem with poor processing performance. Therefore, how to make high-strength alloy cast iron with excellent cutting performance while facing serious challenges? With the propose of ensuring the performance, FAW Group Corporation in the trial casting of high-powered engine cylinder block blank made of the process, without Mo, the key to solve the cost problem, But fell into the plight of poor processing performance, has seriously affected China-made high-powered engine block Localization of rough. How to improve horsepower engine cylinder block blanks made of the performance as its key relationship to the FAW Group Foundry Company's ability to hold this market, and even threaten the survival of enterprises. Therefore, it is as soon as possible to improve the domestic high-powered performance engine block blanks to achieve this critical part of domestic production, thus occupying the market in the country, and even export to international markets, is needed to solve FAW Foundry Company The major technical difficulties, with major economic and social benefits.The paper optimized the drilling process of Cast FAW Group Corporation production process by measuring the resistance force in the drilling, torquemoment, bit wear and surface roughness of the work pieces. Besides, we also studied effect of different modification breeds on the drilling performance of high strength gray cast iron, discussed the discipline of microstructure deformation of high-strength gray cast iron during drilling process, hoping to provide theoretical disciplines to improve the cutting performance. The important conclusions emerging out of this study are the following.(1) treated by JF-1 modification, the shape of curved graphite are much more smaller as the JF-1 was added into the gray cast iron and spacing of pearlite are decreased. As a result, tensile strength of gray cast iron is improved greatly;(2) when treated by JF-2 modification, the shape of graphite changed but there are no influence on the spacing of pearlite. Therefore, it has little effect on the tensile strength of high strength gray cast iron;(3) Estimations based on a comprehensive marking are made about the torquemoment during the drilling process, drilling resistance force, drill wear loss and the surface roughness drilled work specimens. The drilling performance of the six kinds of gray cast iron is given as follow:(4) there are abrasive wear during the drilling process accompanied a certain degree of wear processing to some extent.(5) During the cutting process, deformation of graphite in gray cast iron will occur regularly: there are no deformation for graphite outside the shear region, but in the shear region where the closer with the tools, the more deformation of graphite happens, and when formed cut layers of metal chips, graphite is almost vertical with rake face, as shown in Figure 1;(6) The more the number of graphite in gray cast iron is, the more easily shear in deformation zone, the lower the amount of energy is, thus cutting resistance force is reduced during the machining process.(7) In order to improve the cutting performance of high strength gray cast iron, one of the best ways is to obtain the number of bended graphite while keeping the total graphite without any changing, and this helps improve the high-strength mechanical properties of gray cast iron, also can improve the cutting performance of high strength gray cast iron.