Method and apparatus for use in detecting grinding wheel wear

A method and an apparatus is decribed for sensing the extent of actual wear of a grinding wheel (22) at an area where the wear will be the greatest during the grinding of a workpiece (30). The grinding wheel (22) is dressed by removing material from the grinding wheel (22) to an extent which is a function of the extent of sensed wear at the location where the wear is the greatest. The apparatus includes a probe member (54) which is movable toward the circular working surface or side (26) of the grinding wheel (22) from a retracted position and a detector assembly (70) which detects when the probe member (54) initially engages the circular side (26) of the grinding wheel (22). In some embodiments of the invention, the probe member (54) is moved toward the grinding wheel (22) in incremental steps with sufficient time between the steps to enable the grinding wheel (22) to rotate through slightly more than one complete revolution. In one embodiment of the invention the detector assembly (70) includes a mass which is connected with a probe member (54). Upon initial engagement of the probe member (54) with the circular side (26) of the grinding wheel (22), relative acceleration occurs between the mass and probe member (54). In another embodiment of the invention the detector assembly (70) includes a load cell which detects the occurrence of deflection upon initial engagement of the probe member (54) with the grinding wheel (22). In still another embodiment of the invention, the probe member (54) is moved with a wheel dressing tool (42) to detect when a wheel dressing operation has been completed. After a wheel dressing operations has been completed the rotational speed of the grinding wheel (22) is increased to maintain a desired surface speed even though the diameter of the grinding wheel (22) has decreased.