This invention relates to a face grinder used for grinding the end surface of, for example, a cylindrical workpiece.
A face grinder having the structure shown in FIGS. 6 to 9 is generally known.
This is composed of two wheel heads 4, one for rough grinding and the other for finishing, which are provided side by side on a bed 1 such as to be vertically movably supported thereby, a rotary index table 6 which is disposed under the wheel heads such as to face them, as shown in FIGS. 6 and 7, and a multiplicty of chucks 8 which are disposed on the index table 6, as shown in FIG. 8 and 9. The wheel heads 4 are provided with cup-shaped grinding wheels 2 which are rotated by drive motors 3. The index table 6 and the chuck 8 are rotated by a drive motor 5 and a drive motor 7, respectively. A workpiece 9 is supplied to the chuck 8 at the loading position of the index table and is held by an appropriate method. The grinding wheel 2 cuts the workpiece 9 which is being rotated together with the chuck 8, whereby the end surface of the workpiece 9 is ground to a predetermined dimension.
The end surface of the workpiece 9 which has been ground by the face grinder bears the grinding mark shown in FIG. 10 if it has a center hole 9a and the grinding mark shown in FIG. 11 if it has no center hole. Accordingly, when the wheel 2 becomes locally worn, the workpiece 9 without a center hole 9a has a protruding portion 9b left unground due to the partial wear of the wheel 2, so that the required working accuracy of the workpiece 9 is not obtained. As a result, the lift of the wheel 2 is short, thereby necessitating frequent changes of the wheel, and it is difficult to obtain good working efficiency.