Workpiece holding assembly for a grinding machine and grinding methods

A workpiece holding assembly for a grinding machine, the assembly comprising:

• a magnetic chuck for holding a workpiece which has an outer circumferential surface and an inner circumferential surface located concentrically about a workpiece central axis;
• a reversible chuck drive for rotating the chuck about a chuck rotational axis during grinding;
• and
• first and second separate sets of workrests for engaging with the outer circumferential surface of an annular workpiece held by the chuck with a transverse side surface in engagement with the chuck,
• wherein the workrests of at least one of the first and second sets of workrests are configured as movable workrests which are movable relative to the chuck rotational axis independently of the workrests of the other set, such that:
• when the outer circumferential surface of said workpiece is ground by a grinding wheel rotating in a grinding wheel rotation direction with the chuck rotating in a chuck rotation direction, the outer circumferential surface is only urged in contact with the first set of the first and second sets of workrests;
• and
• when the inner circumferential surface of said workpiece is ground by a grinding wheel rotating in the grinding wheel rotation direction, with the direction of rotation of the chuck reversed relative to the chuck rotation direction during grinding of the outer circumferential surface, the outer circumferential surface is only urged in contact with the second set of the first and second sets of workrests.