A grinding system includes a grinding device that meshes and synchronously rotates a gear-shaped workpiece and a grinding tool, thereby grinding a workpiece tooth surface of the workpiece with a helical grinding tooth surface of the grinding tool, an information acquisition unit configured to acquire information indicating a synchronization error between the workpiece and the grinding tool during grinding of the workpiece tooth surface, and a determination unit configured to determine, based on the synchronization error, whether an abnormality has occurred in the grinding of the workpiece tooth surface.

A gear grinder includes a workpiece rotation portion, a grindstone rotation portion, and a movement portion. The workpiece rotation portion rotates a workpiece including a plurality of teeth on an outer peripheral surface about a workpiece axis which is a central axis thereof. The grindstone rotation portion rotates a grindstone including a spiral groove on an outer peripheral surface about a grindstone axis which is a central axis thereof. The movement portion moves the grindstone with respect to the workpiece. The grindstone axis is inclined with respect to the workpiece axis. In the gear grinder, the workpiece rotation portion and the grindstone rotation portion synchronously rotate the workpiece and the grindstone, and the movement portion moves the grindstone along a plane perpendicular or substantially perpendicular to the workpiece axis to grind the workpiece.

A gear grinder includes a workpiece rotator, a grinding wheel rotator, and a first mover. The workpiece rotator rotates a workpiece including teeth on an outer peripheral surface about a workpiece axis which is a central axis thereof. The grinding wheel rotator rotates a grinding wheel including threads on an outer peripheral surface about a grinding wheel axis which is a central axis thereof. The first mover moves the grinding wheel from one end to another end of the workpiece in the tooth width direction. The gear grinder grinds the workpiece, the workpiece including a first region located at a center portion in the tooth width direction and a second region closer to an end portion in the tooth width direction than the first region. The movement speed of the grinding wheel in the tooth width direction when grinding the first region is lower than in the second region.