Annular grinding ring

An annular ring 10 has a radially outward facing peripheral surface 12 and a radially inwardly facing surface 14. The peripheral surfaces 12, 14 are joined by upper 16 and lower 18 surfaces. The outer peripheral surface 12 is substantially flat and is substantially parallel with the axis A of the ring 10. The inner peripheral surface 14 is inclined relative to the axis A. The ring 10 also includes a plurality of projections 20, each of which is connected to the radially inwardly facing peripheral surface 14. The projections 20 are equally spaced from each other about the axis A of the ring 10. Each projection 20 extends away from the inwardly facing peripheral surface 14 generally radially towards the axis A of the ring 10. A lower surface of each projection 20 includes a recess 22 to receive part of a lifting member.