Self-locking clamping system for a hollow shaft

1 . A clamping device for a hollow shaft, comprising one or more clamping segments and a tension bolt cooperating with the clamping segments,

wherein each clamping segment has, at a front end on an outer side of the clamping segment, a front clamping claw, and, on an inner side of the clamping segment cooperating with the tension bolt, a front lug,

wherein each clamping segment has, at a rear end on an outer side of the clamping segment, a rear clamping claw, and, on an inner side of the clamping segment cooperating with the tension bolt, a rear lug,

wherein, in a clamping position, the front clamping claw of each clamping segment engages in a clamping groove of the hollow shaft and the rear clamping claw is pressed against a cone of a surrounding part or a spindle,

wherein, in an open position, the front clamping claw of each clamping segment does not engage in the clamping groove of the hollow shaft,

wherein, by means of axial displacement, the tension bolt moves the clamping segment or segments from the clamping position into the open position and from the open position to the clamping position,

wherein the clamping segment or segments perform(s) a first pivoting movement during the transition from the open position to the clamping position, such that the front clamping claws of the clamping segments engage in a positively-locking manner in the clamping groove and form a joint for a subsequent second pivoting movement of the clamping segment or segments,

wherein, during the second pivoting movement, the rear lugs of the clamping segment or segments slide on a third cone section of the tension bolt and press the rear clamping claws of the clamping segments against the cone of the surrounding part or the spindle and axially clamp the clamping segment or segments, and

wherein, during a further axial movement of the tension bolt following the second pivoting movement, the rear lugs of the clamping segment or segments slide on a second cone section of the tension bolt, such that a self-locking effect is produced between the clamping segments and the tension bolt, the self-locking effect holding the tension bolt in position by friction between the rear lugs and the second cone section without an external force to maintain the clamping position.

2 . The clamping device according to claim 1 , characterized in that a first cylindrical section, a first cone section, a second cylindrical section, the second cone section, the third cone section, and a third cylindrical section are successively formed on the tension bolt, starting at a front end of the tension bolt.

3 . The clamping device according to claim 1 , characterized in that an angle of inclination of the second cone section is less than 5° or less than the arc tangent (arctan) of a coefficient of friction (μ) of a material pairing at the contact surfaces between the clamping segment and the tension bolt.

4 . The clamping device according to claim 1 , characterized in that an angle of inclination of the second cone section is in a range between 3° and 5°.

5 . The clamping device according to claim 1 , characterized in that an angle of inclination of the first cone section and/or an angle of inclination of the third cone section is in a range between 30° and 60°.

6 . The clamping device according to claim 5 , characterized in that the angle of inclination of the first cone section and/or the angle of inclination of the third cone section is 45°.

7 . The clamping device according to claim 1 , characterized in that the second cone section and the third cone section merge into one another without a diameter change and without an intermediate cylindrical section.

8 . The clamping device according to claim 2 , characterized in that the front lugs of the clamping segment or segments, starting at the front end, have a first contact surface having an angle of inclination substantially corresponding to an angle of inclination of the first cone section and a second contact surface shaped to conform to the first cylindrical section.

9 . The clamping device according to claim 2 , characterized in that the rear lugs of the clamping segment or segments have a third contact surface having an angle of inclination substantially corresponding to an angle of inclination of the third cone section.

10 . The clamping device according to claim 1 , characterized in that the rear lugs of the clamping segment or segments have a fourth contact surface having an angle of inclination substantially corresponding to an angle of inclination of the second cone section.

11 . The clamping device according to claim 1 , characterized in that the rear clamping claws have a fifth contact surface, and in that the fifth contact surface has an angle of inclination substantially corresponding to an angle of inclination of the cone.

12 . The clamping device according to claim 11 , characterized in that an angle of inclination of the cone and/or an angle of inclination of a fifth contact surface of the clamping segments is in a range of 20° to 45°.

13 . The clamping device according to claim 1 , characterized in that the clamping segment or segments are supported with their rear end against a spring-loaded intermediate disk or directly against a compression spring, the compression spring being configured to permit the clamping segments to deflect in the axial direction when the clamping segments are unable to slide from the first cone section onto the first cylindrical section.

14 . The clamping device according to claim 1 , characterized in that a stop disk is provided at a front end of the tension bolt.

15 . The clamping device according to claim 2 , characterized in that the first cylindrical section has a slight negative taper defined by a negative angle of inclination α, wherein a magnitude of the angle of inclination α is less or equal to 4°.

16 . The clamping device according to claim 13 , characterized in that the intermediate disk is formed to be frustoconical on its side facing the clamping segment.

17 . The clamping device according to claim 13 , characterized in that clamping segments have a chamfer at their rear ends, at least in some regions.

18 . The clamping device according to claim 1 , characterized in that an offset is formed on the tension bolt, which offset serves as a stop for the clamping segments.

19 . The clamping device according to claim 1 , characterized in that the cone is integrated into the adjacent part or the spindle or is designed as a separate component.

20 . The clamping device according to claim 1 , characterized in that the clamping device is part of a driven or stationary tool holder.

21 . The clamping device according to claim 1 , characterized in that the clamping device is used on a turret of a lathe.