| 摘要 |
PURPOSE:To make it possible to detect a tool with the use of a tool head itself by removing an engaging projection from a receiving wall through variation in torque applied to a cutting tool and retreating a tool driving shaft into a base end side with the aid of the guide of a drawing groove. CONSTITUTION:As wear and the like generates at the cutting edge of a cutting tool 3 and the cutting resistance becomes larger, the torque of the tool driving shaft 2 holding the cutting tool 3 increases. As a result, an engaging pin 20 attached to the driving shaft is to slip relatively to an engaging annular body 4 rotating in connection with a tool head main body 1. Then, the engaging pin 20 (engaging projection) rides on a pressing surface so as to press the engaging annular body 4 to the tip side against the energizing force of a disc spring 5 so that the engaging annular body 4 removes from a receiving wall 15 and jumps in a drawing groove 14. Thereafter, the engaging pin 20 or driving shaft 2 is guided in the drawing groove 14 for retreating the cutting tool 3 to the base end side since the enaging pin 20 is energized to the base end side by the drawing spring 21. Thus,the tool 3 is removed from a work piece. |
