Abstract: In order to achieve the lightweight, low-cost and high-efficiency design of a spindle apparatus, speed-change device 50 is provided such that slots 31 are formed in one of a spindle 10 and a cam shaft 12 while spiral torque cam grooves are formed in another, and extend around the axis thereof. A torque cam pin 34 is engaged in each slot and its associated torque cam groove, and the position of the spindle 10 relative to the cam shaft 12 in a circumferential direction can be changed by moving the torque cam pins 34 in the axial direction by drive device 43. Drawing tools 8 are moved in opening and closing directions by changing the position of the spindle 10 relative to the cam shaft 12 in the circumferential direction.

Abstract: In order to achieve the lightweight, low-cost and high-efficiency design of a spindle apparatus, speed-change device 50 is provided such that slots 31 are formed in one of a spindle 10 and a cam shaft 12 while spiral torque cam grooves are formed in another, and extend around the axis thereof. A torque cam pin 34 is engaged in each slot and its associated torque cam groove, and the position of the spindle 10 relative to the cam shaft 12 in a circumferential direction can be changed by moving the torque cam pins 34 in the axial direction by drive device 43. Drawing tools 8 are moved in opening and closing directions by changing the position of the spindle 10 relative to the cam shaft 12 in the circumferential direction.