Research On A New Technology Of Steel Ball Grinding By Abrasive Belt

The key part of ball bearings is steel ball, whose grinding quality shows a direct impact on ball bearings'work performance. To improve the grinding uniformity and the grinding efficiency of steel ball in first grinding process,this thesis comes up with a new grinding process using abrasive belt. Then a series of theoretical study and simulation tests were carried out in this thesis, the results of which provide theoretical basis for the production.At first, the thesis made some research on the mechanism of the traditional process, then gave two specific schemes and finally chose the damping-disc-type as the research scheme, under which a grinder and its relevant components were designed.To find out the law of grinding motion, we regarded the ball as rigid body, then established a ball grinding model. We described the general motion of the ball in grinding and analyzed the strained condition, then deduced the differential equations of ball motion based on theorem of centre of mass and law of moment of momentum. At the same time, the equations of the grinding trace were also derived through transformation of coordinates.With the development of the virtual simulation technology, we performed some simulation tests to the grinding model based on ADAMS software. A few of results were obtained, such as time-varying curves of the rotating speed and the attitude angles of the ball, the grinding trace on ball surface, and so on. These proved a better uniformity in new grinding process. Simulation also provided basis for choosing reasonable speed of abrasive belts and speed of the damping disc.When researching into the grinding mechanism, the distribution of abrasive grain and the grinding process were analyzed, which helped establish a cone model for a single abrasive grain. Based on this model, the grinding force of a single ball was calculated. Since the evaluation methods for grinding efficiency were formed, the effect factors of the grinding efficiency were analyzed. In addition, the source and constitution of the grinding heat, the wear and lifetime of abrasive belt were also researched, then effective measures were taken to extend the lifetime of abrasive belt.At last, we set up a geometric model of micro abrasive grain grinding steel ball after appropriate simplification of the steel ball grinding process from a micro perspective, then simulated the grinding process by Deform-2D software, and studied the formation and broken mechanism of tiny chips. From the simulation tests, we also obtained internal distribution images of stress field, strain field and temperature field. We found out variation trend of the grinding force. All of these provides a new idea for in-depth research on steel ball grinding mechanism.