Method of phasing threaded grinding stone, as well as gear grinding machine

A method of phasing a threaded grinding wheel, with a gear to be machined which is to be ground by use of the threaded grinding wheel, or with a dresser which is to dress the threaded grinding wheel, the method characterized by comprising:

• measuring a projection-indentation amount of a side surface of the threaded grinding wheel which is being rotated, by radiating a laser beam from a laser displacement sensor on the side surface;
• finding a position of a thread groove of the threaded grinding wheel on the basis of the projection-indentation amount;
• adjusting a phase of the threaded grinding wheel so th at a tooth tip of the gear to be machined or a blade edge of the dresser faces the position of the thread groove;
• storing as a first phase a phase of the threaded grinding wheel when one of thread surfaces of the threaded grinding wheel comes into contact with a corresponding one of tooth surfaces of the gear to be machined or with a corresponding one of blade surfaces of the dresser by rotating the threaded grinding wheel in one direction;
• storing as a second phase a phase of the threaded grinding wheel when the other one of the thread surfaces of the threaded grinding wheel comes into contact with the other one of the tooth surfaces of the gear to be machined or with the other one of the blade surfaces of the dresser by rotating the threaded grinding wheel in the other direction;
• finding an intermediate phase of the threaded grinding wheel between the first phase and the second phase;
• and
• adjusting the phase of the threaded grinding wheel so that a tooth tip of the gear to be machined or a blade edge of the dresser is placed at the intermediate phase.

A gear grinding machine for grinding a gear to be machined by rotating a threaded grinding wheel and the gear to be machined in a state of being meshed with each other, the gear grinding machine characterized by comprising:

• a dresser for dressing the threaded grinding wheel;
• a laser displacement sensor for measuring a projection-indentation amount of a side surface of the threaded grinding wheel which is being rotated, by radiating a laser beam on the side surface;
• a thread groove position detection unit for detecting a position of the thread groove of the threaded grinding wheel on the basis of the projection-indentation amount measured by the laser displacement sensor;
• a rough phasing means for phasing the threaded grinding wheel so that a tooth tip of the gear to be machined or a blade edge of the dresser faces the position of the thread groove detected by the thread groove position detection unit;
• a phase storing unit for storing phases of the threaded grinding wheel when each thread surface of the threaded grinding wheel comes into contact with two opposite tooth surfaces of the material to be machined or with two opposite blade surfaces of the dresser by rotating in two directions the threaded grinding wheel phased by the rough phasing means;
• an intermediate phase calculating unit for calculating an intermediate phase between the phases of the threaded grinding wheel which are stored in the phase storing unit;
• and
• a precise phasing means for phasing the threaded grinding wheel so that the tooth tip of the gear to be machined or the blade edge of the dresser faces the position of the thread groove detected by the thread groove position detection unit.