Method for detecting phase on gear, method for producing gear, method for detecting position on edge of workpiece, and machine tool for detecting phase on gear

A method for producing a gear, comprising:

• obtaining a first determination result indicating whether the gear has been detected at a first detection position, the first detection position being at a first angle relative to a reference position in a circumferential direction of a rotation axis of a spindle holding the gear;
• obtaining a second determination result that indicates whether the gear has been detected at a second detection position and that is different from the first determination result, the second detection position being at a second angle relative to the reference position in the circumferential direction, the second angle being different from the first angle;
• obtaining a third angle that is between the first angle and the second angle;
• obtaining a third determination result indicating whether the gear has been detected at a third detection position that is at the third angle relative to the reference position in the circumferential direction;
• replacing the first angle with the third angle when the third determination result and the first determination result are same, or the second angle with the third angle when the third determination result is different from the first determination result;
• detecting the phase on the gear in the circumferential direction based on an angle that is between the first angle and the second angle;
• and
• performing, based on the phase on the gear that has been detected, at least one treatment among finishing on a tooth surface of the gear, burr removal off the gear, copying measurement of the tooth surface, and key hole formation through the gear.

A method for detecting a position on an edge of a workpiece, the method comprising:

• obtaining a first determination result indicating whether the workpiece has been detected at a first detection position with the workpiece held at a machine tool;
• obtaining a second determination result that indicates whether the workpiece has been detected at a second detection position different from the first detection position, the second determination result being different from the first determination result;
• obtaining a third detection position that is between the first detection position and the second detection position;
• obtaining a third determination result indicating whether the workpiece has been detected at the third detection position;
• replacing the third detection position with the first detection position when the third determination result and the first determination result are same, or the third detection position with the second detection position when the third determination result is different from the first determination result;
• and
• detecting, as the position on the edge of the workpiece relative to the machine tool, one position located between the first detection position and the second detection position.

A machine tool configured to detect a phase on a gear, the machine tool comprising:

• a spindle which is configured to hold the gear and which is rotatable about a rotation axis of the spindle;
• a sensor control circuit configured to determine whether the gear has been detected at a detection position;
• an angle changer configured to change an angle of the detection position relative to a reference position in a circumferential direction of the rotation axis;
• and
• a processor configured to obtain a determination result from the sensor control circuit and control the angle changer, the processor being configured to:
• obtain a first determination result indicating whether the gear has been detected at a first detection position, the first detection position being at a first angle relative to the reference position in the circumferential direction;
• obtain a second determination result that indicates whether the gear has been detected at a second detection position and that is different from the first determination result, the second detection position being at a second angle relative to the reference position in the circumferential direction, the second angle being different from the first angle;
• obtain a third angle that is between the first angle and the second angle;
• obtain a third determination result indicating whether the gear has been detected at a third detection position that is at the third angle relative to the reference position in the circumferential direction;
• replace the first angle with the third angle when the third determination result and the first determination result are same, or the second angle with the third angle when the third determination result is different from the first determination result;
• and
• detect the phase on the gear in the circumferential direction based on an angle that is between the first angle and the second angle.