Abstract: A grinding wheel is for use in a grinding machine, and is attached on a wheel spindle of the grinding machine for simultaneously grinding at least two parts of a workpiece. The grinding wheel includes at least two wheel cores. Each of wheel cores has a disk-like shape. An abrasive layer is disposed on a circumferential surface of each of the wheel cores. A spacer portion is inseparably fixed on at least one of the wheel cores for keeping a space between the abrasive layers of the wheel cores. And a first labyrinth portion located on one of side surfaces of one of the wheel cores for forming a labyrinth seal with a second labyrinth portion arranged on the grinding machine. The number of separable parts of the grinding wheel are extremely decreased in consideration of imbalance of every part. The spacer portion is integral with at least one of the wheel cores.

Abstract: A grinding wheel which is formed from super hard abrasive grains is trued by traverse-feeding a truing tool a plurality of times (n). Among the (n) traverse feeds of the truing tool, every traverse feed except for the final (i.e., from the first to the (n-l)th traverse feed) is carried out with an infeed which is set at a relatively small value in order to remove any deflection of the grinding wheel. In the final traverse feed, the infeed of the truing tool is set at a relatively large value in order to form an excellent cutting edge on the grinding wheel. Accordingly, any deflection of the grinding wheel is removed by a plurality of traverse feeds of the truing tool carried out with a relatively small infeed, and a cutting face having an excellent cutting ability is formed on the grinding wheel by the final traverse feed carried out with a relatively large infeed.

Abstract: A cam grinding machine of the type in which a grinding wheel is moved toward and away from a cam shaft rotatably supported on a table, thereby to shape intake and exhaust cams of said cam shaft to predetermined profiles, the cam grinding machine comprising: means for detecting the machined condition of the cams in spark-out grinding; means for setting spark-out ending conditions separately for the intake and exhaust cams; means for judging whether the machined condition in spark-out has reached a level complying with the spark-out ending condition, separately with respect to the intake and exhaust cams; and means for stopping the spark-out when the machined condition comes into compliance with the spark-out ending condition.