Research & Development Of Portable Intelligent Sand Mold Hardness Tester

In the foundry production, molding sand quality has a significant impact on product quality, but in the fields of actual casting process, usually, the quality of sand mixture can be measured and controlled. For the prepared sand molds, the one of parameters that can be accurately and quickly determined is the surface hardness of sand mold. Since the surface hardness of sand mold is a key parameter that has a direct impact on casting quality, the ability to accurately and quickly determine for mold hardness plays an important role to control the degree of compaction of the sand and to prevent the casting surface defects, such as sand inclusion, peeling and metal penetration.The instrument to be used for measuring the surface hardness of sand mold is called sand mold hardness tester. Because the mold hardness tester is easy to operate and without damage to the mold, it is a simple and feasible way to enhance the quality control and improve the casting quality. So, sand mold hardness tester naturally becomes necessary testing equipment in sand mold casting process. At the present time, mechanical sand mold hardness tester employing spring dynamometer is widely used by foundry industry. The existing problems are mainly as follows: test data is not precise enough, Instrument type is too much resulting test data out of current use, and recording, storing and processing for test data are inconvenient. Therefore, it now might be an oncoming research subject to develop a high precise, multipurpose, intelligent, economical sand mold tester.First, the testing principle of sand mold hardness tester is briefly introduced, and the formula for conversion of the pressure to sand mold hardness is deduced. And then the sand mold hardness tester prototype's assembly diagram, part drawing and the injection mold for the shell of the prototype are designed and drawn. In addition, a multipurpose pressure head to unify the sand mold hardness data is designed. Finally, the hardware design and software design of the sand mold hardness tester are introduced in detail.The sand mold hardness tester use single chip microcomputer C8051F350 as core, adopt 24bit high precisionΣ-ΔA/D converter to convert the load signal from load cell FSS1500N into the hardness value to display at LED displayer. It can improve the testing precision and sensitivity. At the same time, it also has functions of data storage and communication with PC. This paper expounded the C8051F350's software design such as A/D conversion, pressure transformation to hardness, serial port UART to USB and parameter adjustment module and so on. It also introduced the software programming of PC host computer extract, analysis and save data in details.Final, the paper provides the debugging and verification results of the prototype. The results indicate that the prototype not only fulfill the demand of digital display but also achieve the accuracy test requirements of the sand mold hardness tester, which laid a foundation for the finished product's finalization, batch production, reduce volume and improve its portability.