A dynamic threshold-based fuzzy adaptive control algorithm for hard sphere grinding

Abstract

Grinding wheel wearing fast and metal adhering were severe in hard sphere grinding, which led to wheel overload and clogging. If a fixed-feed grinding was used, the normal pressure between the workpiece and the grinding wheel increased rapidly. Once the grinding load on the grinding wheel was greater than the strength of the retaining bond bridges, a large amount of grains dropped out, which can even damage the wheel. This led to the sphere surface to be scratched. In this study, a dynamic threshold-based fuzzy adaptive control algorithm (DTbFACA) is proposed for hard sphere grinding to avoid scratches on the workpiece. The grinding force was indirectly obtained by measuring the motorized spindle current which was used as a feedback to control hard sphere grinding process. The current threshold in DTbFACA was obtained and online-rectified automatically. The depth of cut and the cup wheel swing speed that affect the motorized spindle current was online-adjusted by fuzzy algorithm. The experimental results indicated that DTbFACA can avoid scratches on the workpiece without sacrificing the sphere form error and grinding efficiency. DTbFACA has been implemented on MD6050 sphere grinding machine tool in production.