| 摘要 |
PROBLEM TO BE SOLVED: To minimize the vibration of a tool by forming a balance weight so as to intermediately position the center of gravity thereof between a spindle and a drive shaft. SOLUTION: A balance weight 66 has an approximately U-shaped structure including an arm 76 having curved parts 74 and far end parts 78. and the far end parts 78 of the balance weight 66 extend upward to a maximum limit, with necessary clearance kept between a housing and a sleeve 48. Also, a spindle 42 and the sleeve 48 are partly exposed between both far end parts 78 of the balance weight 66. In order to minimize a vibration. the balance weight 66 is positioned so as to have the center of the gravity thereof near the reciprocating shaft of the spindle 42 as much as possible. |
