| 摘要 |
The grinding wheel (1) comprises a concavity (8) at the base of which there is provided a metal ring (4) which is non-abrasive but is sufficiently hard to resist wear by rubbing against the material being ground. The grinding wheel (1) hence removes material only until the metal ring (4) encounters the summit of the convex shape obtained. The ring (4) therefore operates as a stop-rest which automatically prevents superfluous removal of material. <IMAGE> |
