Study On Automatic Determination Method Of The Effective Bentonite And Multifunctional Control System Of The Molding Sand Quality In Green Clay Casting Process

The clay sand casting process is a main method in casting production, which is widely applied in iron castings, aluminum castings and steel castings, its total production accounts for about 70%～80% casting gross production. Currently, the clay green sand casting plays a leading role in automobile castings production, and its main production pattern is mass-production in pipelining. There are many factors to affect the casting quality in actual production, and one of the main factors is the quality of clay molding sand. Therefore it is important to hold high quality of clay molding sand for clay green sand casting quality control.In this dissertation, the factors of affecting the clay molding sand performances in mass-production condition were studied systemically, and the relationships of "molding sand component-molding sand performance" and "molding sand performance-casting defect rate" were researched and explored. Farther, the methods of controlling molding sand performances and decreasing casting defect ratios in production-line process were researched from two ways. One is to invent "the auto-fast determining method of the used clay sand effective bentonite content", and the other is to develop "the multifunctional clay sand casting quality management system".The influence of the used sand performance, molding sand composition, remained core sand content, ambient temperature and used sand temperature on molding sand performances had been emphatically studied, and the molding sand component of the molding sand product-line had been optimized. Using the statistic analyzing method, the relationships of "molding sand component-molding sand performanc", and "molding sand performance-casting defect rate" were analyzed based on mass-product field data. The "molding sand component X-molding sand performance Y" relationship equation Y =a0+a1X1+a2X2+a3X3 was established, which consists of series equations between the molding sand performances (including compactability Y1, permeability Y2, green compression strength Y3, wet tensile strength Y4, shear strength Y5) and molding sand components (including water content X1, effective bentonite content X2, effective coal dust content X3). The "casting defects rate Z-molding sand performances Y "relationship equation Z=a0+a1Y1+a2Y2+a3Y3+a4Y4+a5Y5 was established also, which consists of series equations between the casting defects (including sand hole rate Z1, blowhole rate Z2, leaky box rate Z3, burning-on rate Z4) and molding sand performances (including compactability Y1, permeability Y2, green compression strength Y3, wet tensile strength Y4, shear strength Y5) too. The measures of controlling casting defects had been proposed.A new automatic test method was invented to determine the used clay sand effective bentonite content base on the image recognition technology in order to achieve the rapid determination of effective bentonite content on molding sand product-line. The new method uses the photosensitive degree difference of the light blue and dark blue in three-channel of red, green and blue. Firstly decompose the color images into three-channel gray images; then make gray value subtraction operation, gray level transformation of the gray images fg=ag+b, and threshold segmentation; finally extract the outer circle light blue halo and the inner circle blue spot to calculate their area ratio A=f(d)×∫S(d), and achieve the automatic test of effective bentonite content. The test results show that the end-point would be reached and the titration process would be ended when the area ratio of the inner circle blue spot to the outer circle light blue halo is higher than 15%, then the ethylene blue adsorbed value and the clay used sand effective bentonite content would be calculated automatically by the instrument system.The auto-fast determine instrument of effective bentonite content is researched and developed base on the computer image recognition techniques. The instrument is constructed by using the advanced image recognition system and the market mature apparatuses including peristaltic pumps, electromagnetic stirrers, stepper motors and so on. It possesses some advantages of simple structure, convenient operation and stable test. The instrument mainly consists of stirring part, removing liquid part, image acquisition part and processor. The test solution is heated and mixed by the electromagnetic stirrer with heating element; the liquid removeing and titrating processes is completed by minitype peristaltic pump; the image acquisition part consists of step-rotation part and minitype camera, and it would ensure the titration and test simultaneous; the instrument operation process would all be controlled by the processor.The multifunctional clay sand casting quality management system had been studied and constructed. The molding sand performances database and casting defects database had been built by selecting the appropriate development tools and platforms, and the connections of databases and quality management system had been achieved. According to the general framework of quality management system, and using the relationship equations of "molding sand performances-casting defects" and the "molding sand components-molding sand performances" as the core, and combining with the molding sand performances database and casting defects database, had completed the interface design of the quality management system. It also finished the design and realization of the system maintenance module, and the system inquiry module, and the system statistics module and the system analysis module. The management system possesses multifunctions of database vindicating, casting defect querying and molding sand performance adjusting.Aiming at the auto-determine instrument of effective bentonite content in clay used sand and the multifunction molding sand quality management system, the applicability of the auto-determine instrument and quality management system were validated in the actual production. The results showed that the effective bentonite content auto-determine instrument could greatly enhance test precision and reduce test time; and the clay sand quality management system could promptly adjust the molding sand components, control the molding sand performances, and reduce the casting defect rate according to the field condition change. So these research results have important practical significance.