Self-Locking Hollow Shaft Clamping Mechanism

Abstract

This invention concerns a clamping device for firmly holding a part to be clamped at a clamping recess in which the clamping device is arranged. The clamping device comprises a collet with a first external protrusion for engagement with an internal recess in an inner peripheral area of the part that is to be clamped and with a second external protrusion for engagement with an internal recess in an inner peripheral area of the clamping recess. At least one of the first external protrusion or the second external protrusion comprises a first external taper or a second external taper for pulling the part to be clamped axially into the clamping recess by a radial outward movement of the collet or a section of the collet and an operation stud including an external tapered section for effecting the radial outward movement of the collet. The connection between the operation stud and the collet is self-locked and pre-loaded after a clamping movement of the operation stud in axial direction that locks and pre-loads the external taper of the operation stud and the collet or a part between the collet and the operation stud with each other. The invention includes a method for a part to be clamped in a clamping recess.

Claims

1. Clamping device (1) for holding a part that is to be clamped (2) in a clamping recess (3) in which the clamping device (1) is arranged, the clamping device (1) comprising: a collet (10) with a first external protrusion (103) for engagement with an internal recess (25) in an inner peripheral area of the part that is to be clamped (2) and with a second external protrusion (104) for engagement with an internal recess (36) in an inner peripheral area of the clamping recess (3), wherein at least one of the first external protrusion (103) and/or the second external protrusion (104) comprises a first external taper (1031) and/or a second external taper (1041), respectively, for pulling the part to be clamped (2) into the clamping recess (3) by a radial outward movement of the collet (10) or a section of the collet (10) and an operation stud (13) including an external tapered section (131, 132) for effecting the radial outward movement of the collet (10), characterised in that the collet (10) is self-lockable by a movement of the operation stud (13) in axial direction that fixes the external taper of the operation stud (13) and the collet (10) or a part between the collet (10) and the operation stud (13) to each other.

2. Clamping device (1) according to claim 1, wherein the operation stud (13) comprises at least one of a first external tapered section (131) and a second external tapered section (132), characterised in that at least one of a first clamping angle (CA1) between at least a section of the surface of the first external tapered section (131) of the operation stud (13) and a direction of clamping movement (CM) of the operation stud (13) and a second clamping angle (CA2) between at least a section of the surface of the second external tapered section (132) of the operation stud (13) and the direction of clamping movement (CM) of the operation stud (13) is small enough for the operation stud (13) to be self-locking by friction of the faces in contact at its first and second external tapered section (131, 132), respectively, and the collet (10) or a part between the collet (10) and the operation stud (13), wherein, preferably, at least one of the first and the second clamping angle (CA1, CA2) is smaller than the half of the arctangent of a friction coefficient between the surface of the first and/or second external tapered section (131) of the operation stud (13), respectively, and the collet (10) or a part between the collet (10) and the operation stud (13) and/or the first and/or the second clamping angle (CA1, CA2), respectively, is smaller than 6 in case that the materials in contact are both steel or, in case that another contacting material combination is present, the first and/or the second clamping angle (CA1, CA2), respectively, is smaller than an angle that is calculated by multiplying 6 with the quotient of the arctangent of the friction coefficient of the other material combination divided by the arctangent of 0.15, and/or an axial force (AF) created by the clamping mechanism between a part (2) that is to be clamped and a shaft (38) is less than 14 times larger than any axial force (RF) for releasing the clamping device.

3. Clamping device (1) according to claim 1, characterised in that the clamping recess (3) is arranged in a shaft (38) with a through bore (37) and that the clamping device (1) is operable by a locking-releasing bar (17) that is arranged in the through bore (37), wherein the clamping device (1) comprises a clamping device channel (18) for guiding a liquid or gas through the clamping device (1), wherein the clamping device channel (18) is rotatable together with the clamping device (1) and the shaft (38) and a rotary feedthrough (181) for a connection of the rotatable clamping device channel (18) of the clamping device (1) to a supply channel (172) in the locking-releasing bar (17), wherein the locking-releasing bar (17) is preferably non-rotatable, wherein preferably the rotary feedthrough (181) is detachable in axial direction of the shaft (38), wherein at least two parts of the rotary feedthrough (181) are turnable relative to each other together with the shaft (38) and the locking-releasing bar (17), respectively, and are detachable from each other by an axial movement relative to each other.

4. Clamping device (1) according to claim 3, characterised in that a bearing and sealing function of the rotary feedthrough (181) is realised by at least one of an aerostatic, aerodynamic, hydrostatic or hydrodynamic bearing.

5. Clamping device (1) according to claim 1, characterised in that the operating stud (13), at each axial position, does not have a diameter (D) that is greater than a minimum inner diameter of the collet (10), when it is in a position in which its minimum inner diameter is maximised, in direction away from the part to be clamped (2), such that the operation stud (13) is removable from the inside of the collet (10) in axial direction and away from the part that is to be clamped (2).

6. Clamping device (1) according to claim 1, characterised in that the clamping device (1) comprises a guide ring (19) with radially extending guide slots (191) in its outer periphery, wherein each is configured to guide a collet segment (11) in a touching plane (194) with at least one side face (111) of the collet segment(s) (11), wherein the side face(s) (111) are arranged at the collet segments (11) in circumferential direction of the collet (10), and wherein the guide slots (191) preferably extend axially over the complete axial length of the radially outer periphery of the guide ring (19).

7. Clamping device (1) according to claim 1, characterised in that an outer periphery of the operation stud (13) is guided at the inner periphery of a shaft through bore (37), preferably by a tight fit between the outer periphery of the operation stud (13) and the inner periphery of the shaft through bore (37), wherein the tight fit preferably has a play of less than 20 microns, more preferably a play of 3 up to 5 microns.

8. Spinning or positioning device (1000) comprising a shaft (38), characterised in that a shaft (38) of the spindle (1000) comprises a clamping recess (3) comprising a clamping device (1) according to claim 1.

9. Spinning or positioning device (1000) according to claim 8, wherein a shaft (38) has an axial through bore (37) that extends to the clamping recess (3) of the shaft (38), characterised in that clamping device (1) is operable by a locking-releasing bar (17) by action on the clamping device (1) and without action of a dedicated clamping force generation unit (4) to permanently apply a force through an operation bar (12) to the operation stud (13) in a clamped state, wherein, preferably, the locking-releasing bar (17) is fixed to the spindle (1000) in regard of rotation and/or preferably does not interact with the clamping device (1) if no clamping or releasing is performed.

10. Spinning or positioning device (1000) according to claim 8, characterised in that the shaft (38) or the shaft assembly (35) is extractable from the spinning or positioning device (1000), wherein the clamping device (1) is connected to the locking/opening bar (17) and remains in the spinning or positioning device (1000) when the shaft is extracted, wherein the collet (10) remains in the shaft (38) and wherein, preferably, the shaft assembly (35) is extractable.

11. Spinning or positioning device (1000) according to claim 8, characterized in that the shaft (38) comprises a readjustment spring (14) by which an increased clamping due to the centrifugal load on the collet (10) under rotation and a resulting decreased pre-load between the operation stud (13) and the collet (10) is compensable by an axial adjustment of the operation bar (13) caused by the re-adjustment spring (14) in order to hold or restore the pre-load between the collet (10) and the operation rod (13), wherein, preferably, the readjustment spring (14) is arranged between the operation stud (13) and the spindle shaft (38) such that it is compressible with a releasing movement of the operation stud (13) or the collet (10) and preferably has the form of a coil spring.

12. Spinning or positioning device (1000) according to claim 8, characterised in that a fast gripping of a part (2) that is already inserted into a clamping recess (3) of the shaft (38) and that is not yet clamped is performable by a movement of the operation stud (13) that is effected by tension release of the readjustment spring (14) and a movement of the operation stud (13) by the readjustment spring (14).

13. Spinning or positioning device (1000) according to claim 8, characterised in that the locking-releasing bar (17) is supported by a bar bearing (174) between the locking-releasing bar (17) and the shaft (38), wherein, preferably, the bar bearing (174) is a gasstatic, gasdynamic, fluidstatic or fluiddynamic bearing.

14. Spinning or positioning device (1000) according to claim 8, characterised in that a stud sealing (133) is arranged between the operation stud (13) and the shaft (38) in order to seal a part of the spindle through bore (37) from the end of the clamping recess (3) of the shaft (38) in direction to the part to be clamped.

15. Method for clamping a part (2) that is to be clamped in a clamping recess (3), wherein locking of a clamping device (1) in the clamping recess (3) is achieved by moving an operation stud (13) with at least one external tapered section (131, 132) in clamping movement direction (CM) inside a collet (10) which radially moves outwards in order to clamp the part (2) that is to be clamped, characterised in that the collet (10) is reversibly self-locked by fixing the collet (10) or a part between the collet (10) and the operation stud (13) and the operation stud (13) to each other.

Description

[0082] The Figures show embodiments according to the state of the art and, as an example only, an embodiment according to the invention.

[0083] FIG. 1A shows a cross-section through a centreline plane of the spindle shaft of a first variant of a hollow shaft clamping mechanism according to the state of the art which comprises a clamping force generation unit that rotates along with the spindle shaft and which permanently exerts a tensile force to the clamping device that holds a part to be clamped,

[0084] FIG. 1B gives a detailed view of the hollow shaft clamping mechanism shown in FIG. 1A in a magnified view,

[0085] FIG. 2 shows a cross-section through a centreline plane of the spindle shaft of a second variant type of a hollow shaft clamping mechanism according to the state of the art which comprises a self-locking clamping force generation unit that rotates along with the spindle shaft and which permanently exerts a tensile force to the clamping device to keep a part clamped,

[0086] FIG. 3A shows a cross section plane through a centreline of a clamping device according to the invention,

[0087] FIG. 3B shows the clamping device as in FIG. 3A, but along with different details and information,

[0088] FIG. 3C shows a cross section through a centreline plane of a guide ring and

[0089] FIG. 3D represents a view of a guide ring for guiding collet segments of the clamping device of FIG. 3C.

[0090] FIG. 3A schematically shows a clamping device 1 according to the invention. Some features are similar to the features of the clamping systems 100 and 200 of FIGS. 1A, 1B and 2, respectively, and are generally marked with the same reference signs.

[0091] In FIG. 3A, a part 2 that is to be clamped is shown which has the form of a tool holder 20. It is clear that any other tool or part with the same interface geometry can be clamped by a hollow shank clamping mechanism according to the invention.

[0092] The part 2 that is to be clamped is partially shown with its insertion section 21 in a clamping recess 3 at an axial end of a shaft 38. The insertion section 21 protrudes in direction of a shaft 38. The shaft 38 is not shown completely in FIG. 3A, but, in reality, continues further to the right side in FIG. 3.

[0093] The outer contour of the insertion section 21 has the shape of a taper 24. The taper 24 is shown as fully engaged into a taper 34 at an inner contour of the clamping recess 3 and contains an interference fit between these tapers. An axial end face 22 of the part to be clamped is shown pressed against an axial end face 32 of the shaft 38.

[0094] Inside the clamping recess 3 a collet 10 is arranged. The collet 10 comprises at least one, preferably at least two single collet segments 11. The collet segments 11 are guided in a guide ring 19. The guide ring 19 can be screwed into the clamping recess 3 in the shaft 38. In this way, the collet segments 11 are guided relative to the shaft 38.

[0095] Each of the collet segments 11 comprises a first external protrusion 103 and a second external protrusion 104. A first external protrusion 103 is shown clipped into a tapered internal section 25 at the inner contour of the insertion section 21 of the part 2 to be clamped. A first external clamping taper 1031 of the collet 10 touches the tapered internal section 25 for transmitting clamping forces. The second external protrusion 104 is clipped into an internal recess 36 in an inner peripheral area of the shaft 38. The internal recess 36 has an internal tapered section 361. The internal tapered section 361 touches a second external clamping taper 1041 of the collet 10 for transmitting clamping forces.

[0096] Inside the collet 10, an operation stud 13 is arranged. By an axial operation movement of the operation stud 13, the collet 10 can be moved radially to the outside or to the inside. At its inside, the collet 10 has a first internal tapered section 101 which is arranged at the end of the inner periphery of the collet 10 in direction to the clamped part 2. Further, at its inside, the collet 10 has a second internal tapered section 102 which is arranged further in direction of a locking-releasing bar 17. Both of the internal tapered sections 101, 102 preferably have a half angle of less than 6 that is measured against the centre line 33. The operation stud comprises a first and a second tapered section 131 and 132. The first tapered section 131 is subdivided into a first and a second tapered subsection 1311 and 1312. During a clamping movement of the operation stud 13, the internal tapered sections 101, 102 are in contact with a second external tapered subsection 1312 of the first external tapered section 131 and a second external tapered section 132, respectively. The second tapered subsection 1312 and the second external tapered section 132 have a half angle of less than 6 measured against the centre line 33. When the operation stud 13 is moved to the right in FIG. 3, self-locking takes place because of the shallow taper angles of the tapered sections 1312, 132 and 101, 102. During the clamping travel in which the operation stud 13 is moved to the right in FIG. 3 the collet segments 11 are moved outwards. This causes the part 2 that is to be clamped to get pulled axially along the centre line into the clamping recess 3 by the internal tapered sections 25 and the first external clamping taper 1031 at the end of the collet segments 11 near the part 2 that is to be clamped, and by the internal tapered section 361 of the clamping recess and the second external clamping taper 1041 at the other end of the collet segments 11. The geometry of the collet 10, the internal recess in the clamped part 2 that is to be clamped with the tapered section 25 and the recess 36 in the shaft 38 cause a tensile force on the collet segments 11 and pull the axial end faces 22 and 32 of the clamped part 2 and the shaft 38 against each other. In this state, the collet segments 11 get stretched elastically. Due to the self-locking effect, this elastic deformation pre-loads the taper connection 24, 34 between the part 2 that is to be clamped and internal taper 34 in the shaft 38.

[0097] The operation stud 13 comprises a first tapered subsection 1311 which has a significantly steeper half angle than the second tapered section 1312. The external taper section 1311 can interact with the ends of the collet segments 11 close to the part 2 that is to be clamped. Because of the steeper taper angle of the first tapered subsection 1311, a fast gripping movement of the first protrusions 103 of the collet 10 takes place when the operation stud 13 is moved to the right in FIGS. 3A and 3B and when the first tapered subsection 1311 is engaged. During a releasing stroke of the operation stud 13 towards the clamped part 2, the end of the collet 10 that is closer to the part 2 that is to be clamped slides radially into a recess of the operation stud 13 which is partially bordered by the first external tapered subsection 1311. The end of the collet 10 towards the part 2 to be clamped is then radially retracted towards the centre line 33 and out of the internal tapered section 25 of the clamped part 2.

[0098] The operation stud 13 is arranged inside a shaft through bore 37. At its end opposite to the clamped part 2, the operation stud 13 is connected to a locking-releasing bar 17 via a rotary feedthrough 181. The operation stud 13 comprises a rotary feedthrough counter-part 135 which has the form of a tube. The feedthrough counter-part 135 is arranged into an axial bore of the operation stud 13. It allows a sealing function. Additionally, or alternatively, the feedthrough counter-part 135 allows a flexible behaviour in radial direction by sealing rings. The axial position of the tube is fixed. The outer periphery of the feedthrough counter-part 135 is designed as a journal gas bearing. The outer part of the air bearing is the rotary feedthrough 181. It comprises bearing gas supply bores 182 for supplying the bearing gas to the journal bearing.

[0099] The rotary feedthrough 181 enables a medium to flow through a supply channel 172 within the locking-releasing bar 17 into a clamping device channel 18. The clamping device 1 with clamping device channel 18 and locking-releasing bar 17 with the supply channel 172 can then change their relative angular position when a medium is flowing. The supply channel 172 extends through the complete axial length of the operation stud 13. The gas bearing as a combination of the feedthrough counter-part 135 and the rotary feedthrough 181 also has the function of a sealing against any fluid or gas in the channels 172 and 18.

[0100] The operation stud 13 further comprises a sealing 133 which interacts with an inner periphery of the shaft through bore 37. This sealing 133 seals the clamping recess 3 against the deeper parts of the shaft through bore 37.

[0101] In case that the part 2 is removed from the shaft 38, the shaft 38 can be retracted out of a spindle 1000 which is illustrated in FIG. 3B only. The operation stud 13 then remains attached to the locking-releasing bar 17 and inside the spindle 1000.

[0102] The operation stud 13 and the locking-releasing bar 17 are connected to each other such that the connection is disengaged when the locking-releasing bar 17 is not operated for locking or releasing the clamped part 2 by the clamping device 1.

[0103] The clamping device 1 further comprises a readjustment spring 14 which pre-loads the operation stud 13 with a force smaller than the force required to clamp the part 2 in direction of clamping. The readjustment spring 14 is arranged between a spring compression face 134 in the shaft through bore 37 of the shaft 38 and a snap ring 141 which is attached to the shaft 38. The readjustment spring 14 extends axially in the shaft 38.

[0104] In case that there is no part 2 clamped at the shaft 38, the collet segments 11 have a radial position maximum to the outside as the force of the readjustment spring 14 acts on the operation stud 13. To clamp a part 2, the operation rod 13 travels towards the external taper 24 which constitutes an interface between the part 2 and the internal shaft taper 34 where, in this case, the ends of the collet segments 11 towards the part 2 that is to be clamped slide into the recess at the first external tapered subsection 1311 of the operation stud 13. The ends of the collet segments 11 close to the part 2 that is to be clamped have a compression taper surface 1032 at their radially outer periphery. This compression taper surface 1032 can engage with an insertion section 21 of a part 2 to be clamped when the part is inserted into the clamping recess 3. Many, preferably all circumstances that cause the ends of the collet segments 11 towards the part 2 to be clamped not to slide into the recess 1311 of the operation stud 13 can be covered by this design. To allow insertion of the hollow shank of the part 2 that is to be clamped into the clamping recess 3, the insertion section 21 compresses the collet segments 11 at their end with the compression taper 1032 towards the part 2 to be clamped such that they slide into the inside of the hollow shank where they can clip into the internal tapered section 25.

[0105] When the shaft spins at higher speed, for example above 10,000 rpm, along with the mounted clamping device, centrifugal load can acts on the collet segments 11. In this case the axial force into the taper connections between the first external clamping taper 1031 of the collet 10 and the internal tapered section 25 of the part 2 as well as the second external clamping taper 1041 and the internal tapered section 361 of the clamping recess 3 increases. This again results in an increased axial clamping of the clamped part 2 to the shaft 38. On the other hand, however, the connections between the first internal tapered section 101 of the collet 10 and the second external tapered subsection 1312 of the operation stud 13 as well as the second internal tapered section 102 and the second external tapered section 132 of the operation stud lose on pre-load. In case the pre-load of the collet segments 11 due to their elastic deformation during clamping is not sufficient to maintain the clamping force adequately the readjustment spring 14 can come effective. It is strong enough to readjust the axial position of the operation stud 13 by pushing it further in direction away from the part 2 that is to be clamped. After stopping the spinning, a safe and pre-loaded clamping of the part 2 is maintained.

[0106] The operation stud 13 is guided inside the shaft through bore 37 at a guide surface 137 at the periphery of the operation stud 13. Slight eccentricities of the outer diameter of the operation stud 13 can cause a non-repeatable imbalance. Therefore, a very good alignment inside the shaft through bore 37 is preferred. A diametrical fit of, for example, 3-10 microns between the shaft through bore 37 and the guiding surface 137 is preferably designed.

[0107] FIG. 3B illustrates the clamping device 1 in a clamping recess 3 of a shaft 38. The shaft 38 is inserted into a simplified spindle 1000 for illustration purpose. FIG. 3B shows actuation and clamping angles at the operation stud 13. The first external tapered subsection 1311, which is to quickly retain the collet 10 into a recess 1313 of the operation stud 13 at the first external tapered subsection 131 and for gripping of the part 2 that is to be clamped, has a gripping angle GA relative to the central axis of the clamping recess 3. This gripping angle GA is preferably to be chosen from 20 to 45, which is measured form the taper surface to the centre line 33. The second external tapered subsection 1312 of the first tapered section 131 of the operation stud 13 has a first clamping angle CA1 relative to the central axis of the clamping recess 3. The first clamping angle CA1 is less than 6 which is also measured form the taper surface to the centre line 33. The second external tapered section 132 of the operation stud 13 at the side of the locking-releasing bar 12 has a second clamping angle CA2 relative to the centre line 33 of the clamping recess 3. The second clamping angle CA2 is preferably less than 6 which is also measured form the taper surface to the centre line 33.

[0108] The operating stud 13 and the collet 10 touch at the first external tapered subsection 1311 of the first external taper 131 of the stud 13 which is in contact with the first internal tapered section 101 of the collet 10. The second tapered section 132 of the stud 13 is in contact with the second internal tapered section 102 of the collet 10.

[0109] Regarding the operation stud 13, a releasing movement direction RM and a clamping movement direction CM are indicated with corresponding arrows in FIG. 3B.

[0110] Further, as an example for the conditions which are required to remove the shaft 38 from the spindle 1000, a maximum diameter D of the operation stud 13 is indicated. Along an exemplary travel PA which starts at the diameter D in axial direction of the shaft 38, the maximum diameter D is smaller than the inner diameter of the collet 10 and the shaft 38. Also, the guide surface 137 of the operation stud 13 has a smaller diameter than the parts of the shaft through bore 37 which are further away from the guide surface 137 with regard to the clamping end of the shaft 38. More generally spoken, the outer diameter of the parts inside the through bore 37, for example the operation stud 13, are, starting from the considered outer diameter in a direction away from the clamping stop 39 of the shaft 38, smaller than the inner diameter of the collet and the through bore 37. Preferably this is the case, if the collet segments 11 are fully engaged in the taper connection between the internal tapered section 361 of the clamping recess 3 of the shaft 38 and the second external clamping taper 1041 of the collet 10. Also, the outside of the shaft assembly 35, that might, additionally to the shaft and the collet, also contain other parts like bearings, does not have any larger diameters that prevent the shaft assembly 35 from being removed from of the spindle 1000. The shaft 38 or the shaft assembly 35 can be pulled out of the spindle 1000 without further action. The operation stud 13 remains attached to the locking-releasing bar 17 and inside the spindle 1000 in this case where. The collet 10 remains in the shaft 38.

[0111] FIGS. 3C and 3D show a guide ring 19 with guide slots 191. The guide ring 19 shall make sure that any side face of a single collet segment 11 does not move in any other plane than in the plane defined by the touching plane 194 which touches a side face in circumferential direction of a corresponding collet segment 11. The number of guide slots 191 corresponds with the number of collet segments 11 of the collet 10. The guide ring 19 comprises a centering protrusion 192 in order to centre the guide ring 19 in the clamping recess 3. The guide ring 19 comprises a thread 193 at its outer perimeter. By this thread 193 the guide ring 19 can be screwed into the clamping recess 3 which comprises a counter thread at its inner periphery.

LIST OF REFERENCE NUMERALS

[0112] 1 Clamping device [0113] 10 Collet [0114] 101 First internal tapered section of the collet [0115] 102 Second internal tapered section of the collet [0116] 103 First external protrusion of the collet for engaging the collet in the part that is to be clamped [0117] 1031 First external clamping taper of the collet [0118] 1032 Compression taper surface [0119] 104 Second external protrusion of the collet for engaging the collet in the shaft [0120] 1041 Second external clamping taper of the collet [0121] 11 Collet segment [0122] 111 Side faces of the collet segments in circumferential direction of the collet [0123] 12 Operation bar [0124] 121 Longitudinal bore in the operation bar [0125] 122 Operation bar head [0126] 13 Operation stud [0127] 1310 Contact zone [0128] 131 First external taper of the operation stud at the side of the part that is to be clamped [0129] 1311 First external tapered subsection of the first external taper of the operation stud [0130] 1312 Second external tapered subsection of the first external taper of the operation stud [0131] 1313 Recess in the operation stud [0132] 132 Second external taper of the operation stud at the side of the operation stud [0133] 133 Sealing ring [0134] 134 Spring compression face of the operation stud [0135] 135 Rotary feedthrough counter-part of the operation stud [0136] 136 Axial end face of the operation stud [0137] 137 Guide surface of the operation stud [0138] 14 Readjustment spring [0139] 141 Snap ring [0140] 15 Bush with tapered end [0141] 16 Support ring [0142] 17 Locking-releasing bar [0143] 171 Outside tapered section of the locking-releasing bar [0144] 172 Supply channel in the locking-releasing bar [0145] 173 Axial end face of the locking-releasing bar [0146] 174 Radial bar bearing [0147] 18 Clamping device channel [0148] 181 Rotary feedthrough [0149] 182 Bearing gas supply bore [0150] 19 Guide ring for guiding the collet segments in the touching plane [0151] 191 Guide slots [0152] 192 Centering protrusion [0153] 193 Thread at the outer periphery of the guide ring [0154] 194 Touching plane [0155] 2 Part that is to be clamped [0156] 20 Tool holder [0157] 21 Insertion section [0158] 22 Axial end face of the part to be clamped [0159] 23 Central axis of the part that is to be clamped [0160] 24 External taper [0161] 25 Internal tapered section [0162] 26 Internal axial end face [0163] 3 Clamping recess [0164] 31 Insertion section for the part to be clamped [0165] 32 Front axial connection face of the clamping recess [0166] 33 Centre line of the clamping recess [0167] 34 Internal taper in the shaft [0168] 35 Shaft assembly [0169] 36 Internal recess in an inner peripheral area of the clamping recess [0170] 361 Internal tapered section of the clamping recess [0171] 37 Shaft through bore [0172] 371 Axial face inside the shaft [0173] 38 Shaft [0174] 39 Axial Clamping stop [0175] 4 Clamping force generation unit [0176] 41 Disc-spring package [0177] 5 Locking unit [0178] 51 Split double tapered tube [0179] 511 Internal tapered section of the split double tapered tube [0180] 512 External tapered section of the split double tapered tube [0181] 513 Axial end face of the split double tapered tube [0182] 52 Inside tapered bush [0183] 100 First state of the art hollow shaft taper clamping mechanism (HSK type, German: Hohlschaftkegelspannmechanismus) [0184] 200 Second state of the art hollow shaft taper clamping mechanism (HSK type) [0185] 1000 Spindle [0186] D Maximum diameter [0187] PA Exemplary travel along a passing area for the maximum diameter of the operation stud in direction away from the clamping end of the shaft [0188] CA1 First clamping angle of the second external tapered subsection of the first external taper of the operation stud [0189] CA2 Second clamping angle of a second external taper of the operation stud [0190] GA Gripping angle of a first external tapered subsection of the external taper of the operation stud [0191] CM Clamping movement direction of the operation stud [0192] RM Releasing movement direction of the operation stud [0193] CF Clamping force [0194] RF Releasing Force