The Process Monitoring And Control On High Hardness Spherical Precision Grinding

Because of the advantages of less fluid resistance, convenient operation, quickly opening and closing, good sealing and high reliability,metal sealing ball valve is widely applied in industrial areas such as liquefaction of coal, steel and iron smelting, petroleum chemical industry, nuclear electricity, etc. In order to meet the strict requirements in working condition, ball valve core have to owning the strengthened surface.And in order to meet the sealing requirements, the shape accuracy is very high. So it is a great difficult problem in machining high rigidity and high precision sphere. Therefore, in the paper, the technology of spherical grinding process monitoring and control was studied based on self-developed spherical grinding machine.First, through the modeling of spindle-wheel-workpiece system in the spherical grinding machine, the relationship between actual feed and theory feed was given, and the method of decreasing the feed error was figured. The mechanism of the simi-crawling phenomenon was revealed based on the experiment, and suppression measures were given.Second, experimental research was designed based on self-developed sphere grinding machine, through the signal processing, grinding sound and current were determined to monitor and control spherical grinding.Mathematical model of multi-objective parameter optimization in high hardness spherical grinding was established based on orthogonal test. The genetic algorithm based on NSGA-â…¡was adapted to optimize initial parameters of the spherical grinding. The comparison experiments indicates that both in terms of material removal rate or reduce the surface roughness the grinding initial parameters come from NSGA-â…¡genetic algorithm are better than orthogonal test.In the last part of the paper, a fuzzy adaptive control based on dual-threshold of sound and current signal was presented to monitor and control spherical grinding and comparative experiments showed that the method effectively suppress the occurrence of the simi-crawling phenomenon while improve efficiency and surface quality of spherical grinding.