Process Research On Cylinder Block Casting Of 4G1 Gasoline Enging

Making use of the existing production equipment and the experiences accumulated and proven for years, this text has proceeded to a study principally in three aspects: casting process solution optimization, casting process parameter optimization and casting process difficulties analysis. The casting process solution optimization concerns mainly the study of casting process performance analysis and the process tooling and equipment design; the casting process parameter optimization concerns mainly determination of the essential process parameters for core making, molding and melting through tests, and the casting process difficulties analysis concerns mainly study and solution of the casting defaults and the metallurgical structure defects occurred during the development.The study and analysis of process show that the casting process plan of《one mold in one box, making core by cold and hot core boxes, close/open pouring system and melting scrap steel in high temperature for carburetion》must be used in order to satisfy the process requirements by using the existing equipment. By using the process mentioned above, the following technical requirements can be reached: cylinder block hardness of HB179～269,σb≥274MPa, graphite length of 4～6 grades and graphite type of A(types B and D≤20%) through analysis of samples cut from the casting, free ferrite≤3% and free cementite≤3%. In the light of production experiences in the past, hot core box for water jacket core making, cold core box for body core and end core making and low alloy plus composite breeding treatment can obtain satisfactory metallurgical structure and mechanical characteristics. The results of a great number of tests and studies show that when the moisture in sand is 2.7%～3.4%, the effective clay is 6%～9% and the total clay is 8%～12%; the chemical composition of the melted iron: C is 3.10%～3.50%, Si is 1.65%～2.50%, Cr is 0.15%～0.40%, Cu is 0.3%～0.6% and Sn is 0.02%～0.10% is assured, satisfactory result can be obtained.The paper has also studied and solved the problems of sand hole, blowhole and crush on the top surface of the cylinder block and thus the conformity rate of the castings has been considerably increased, and 4G1 cylinder block localization production has been realized.