Research On Pressure Control Technology Of Precision Ball Grinding Machines

Hardess material precision ball plays an important role in precision engineering field, which is considered as one of the most important elements. The precision ball griding machine is an important instrument in hardess material precision balls’machining. And its level of sophistication determines the balls’processing quality directly. Polishing pressure is an important variable in the polishing process, its value influences the surface quality of the balls and the polishing rate seriously in the polishing process. In consideration of the lack of pressure loading in the precision ball griding machine at home and abroad, this paper improved the pressure loading device and its control system to adapt to the requirements of hardess material precision balls’ultra-precision machining.Aiming at the lack of ordinary precision ball griding machine’s pneumatic loading system, this paper put forward a new pressure loading device which was based on stepper motor. The new loading device consisted of the stepper motor driving equipment and spring-weighted equipment. To control the top lap’s vibration in the polishing process, this paper put forward a method of adding a magneto rheological damper into the spring-weighted equipment. For controlling the magneto rheological damper’s damping, the semi-active control in the top lap’s vibration could be achieved. This paper focused on the study of pressure’s loading. The loading system’s dynamic performance was analyzed and the process of the pressure loading was designed optimally. In this paper, the process of pressure loading was divided into two stages:the stage of sinusoidal loading and the stage of fuzzy PID controlling. In the stage of sinusoidal loading, the system controlled the pressure loading on the sinusoidal curve by controlling the stepper motor’s speed. When the speed added to a constant, the speed of the stepper motor stayed. In the stage of fuzzy PID controlling, the stepper motor’s speed was controlled by the instant pressure and the algorithm of fuzzy PID until the pressure reached the set value. When pressure’s loading complicated, controlling system read the acceleration sensor’s value instantly. By the values read from the acceleration sensor and the algorithm of controlling, the damping of magneto rheological damper was controlled. By this way, the top lap’s vibration can be inhibited efficiently. Through the repeated polishing experiments of hardess material precision balls, the effect indicated that the improved pressure loading system could raise the machining quality of the hardess material precision balls.