Error analysis and in-process compensation on cup wheel grinding of hard sphere

Grinding using cup wheel has been widely used in hard sphere machining process. In conventional sphere grinding (CSG), the linear velocity of the point with the same latitude on the sphere varies, which causes the sphericity error. The misalignment of the machine tool is another source of sphericity error. In this paper, these two types of sphericity errors are analyzed, and an adjustable depth of cut sphere grinding (ADCSG) is proposed to reduce the sphericity error. CSG and ADCSG were carried out on a home-made MD6050 NC precision sphere grinding machine, and the effectiveness of ADCSG is demonstrated with grinding tests. The results showed that ADCSG can reduce the sphericity error effectively compared with CSG. The sphericity error can reach less than 5 μm.