Mold CAD/CAE & Plasma Nitriding Surface Treatment Technology Of Cylinder Block For DISA Casting Line

The DISA casting line has many merits such as high production efficiency, good casting quality etc. It is irreplaceable for applying to mass production on small casting. The casting process and mold service life are conspicuous problems which always perplex the manufacture factories. Aiming at it, the mold CAD/CAE and the surface treatment technology of a typical cylinder block were studied to achieve fast design and manufacturing of high quality mold for DISA casting line in this paper.The DISA casting line mold of typical cylinder block casting was designed and the casting process was optimized by using the modern CAD/CAE technology in the paper. It was suggested that the inlaying mold structure apply to sand mold for the DISA line which not only facilitates the manufacture of casting mould blank, but also helps the following regulating of mould casting process and the surface treatment of mold.The flow field of metal liquid in the filling of one mold box within many castings is simulated by HZ-CAE. The defects of inconsistent mold fillings and sand erosion during the fillings were predicted. The casting process was eventually optimized and the probability of the mold debugging success just for the first time was improved. Three kinds of cast iron materials made of the DISA line moulds were nitrided for the study. The influence of the process parameters on the substrate surface hardness of mold,the thickness of nitriding layer and the abrasive resistance ability were detected. The results show that the surface hardness of the nitriding layer of cast iron was improved remarkably by increasing the nitrogen proportion of the nitriding atmosphere properly, raising the nitriding temperature and accessing trace amount of C3H8 to the nitriding atmosphere. The nitriding layers were thickened by lengthening the soaking time properly; the abrasive resistance ability of plasma nitriding layer is proportional to the surface hardness of the nitriding layer, and it is mainly depended on the compound layer of the nitriding layers, but slightly affected by the secondary layer.The process parameters have different influences on the plasma nitriding layers for different cast iron materials. The nitriding effect on the ductile cast iron is better than the gray cast iron. Comprehensively analysing, the material of QT500-7 is better for plasma nitriding and fit to make of DISA line mold. The proper plasma nitriding process is : the proportion of N 2 :H 2 in the nitriding atmosphere is 4:1 , the accessing amount of C3H8 is 5%~10% , the nitriding temperature is 560~570℃, the soaking time is 20 hours.