| 摘要 |
PURPOSE:To make high accurate and heavy cutting work possible, and to avoid overthrust from acting to such as bearings of a spindle by cramping a tool holder via balls having moved toward the center of the spindle with movement of a drawber to one side and uncramping the same with its movement to the other side. CONSTITUTION:Balls 6 are guided movably in radial direction of a spindle 1 via a cylindrical member 20 being the same body with the spindle 1, while a drawber 4 formed with a wedge surface 21a abutting on the balls 6 from outside is movably fitted around the cylindrical member 20 along the rotary center of the spindle 1. A tool holder 2 is cramped via the balls 6 moving toward the center of the spindle 1 by movement of the drawbar 4, to one side and uncramped by its movement to the other side. From the fact that moving force of the drawber 4 to one side is doubled by wedge action between the wedge surface 21a and the balls 6 for transmitting the same to the balls 6, the balls 6 are strongly moved toward the center of the spindle 1 and the tool holder 2 can be firmly cramped with this constitution. |
