Device for setting connecting elements

Abstract

This invention relates to a device (10) for setting connecting elements (100, 300), the connecting elements having a head-side drive structure. The device includes a feed device (12) for applying axial force, a rotating spindle (14, 40, 68, 82, 140), and a drive head (20, 42, 60, 70, 80, 142, 242) connected to the rotating spindle. The drive head has a drive structure (22, 44) arranged circumferentially along the setting direction (S) on the end side, interlocking to rotate the connecting elements (100, 300). The drive head (20, 42, 60, 70, 80, 142, 242) has an axial sleeve. The device also includes a suction unit (18) by means of which air can be suctioned out from the end side of the drive head (20, 42, 60, 70, 80, 142, 242). The device also includes insertion elements (24, 50, 72, 150) having suction surfaces (26, 54) at their ends, the suction surfaces circumferentially defining a suction cross-section (30). The insertion elements (24, 50, 72, 150) are designed such that the suction surfaces (26, 54) can move axially relative to the drive heads (20, 42, 60, 20, 70, 80, 142, 242), and that negative pressure can be released from the insertion elements (24, 50, 72, 150). The side of the insertion element (24, 50, 72, 150) away from the setting direction (S) is transferred to the suction surface (26, 54) of the insertion element (24, 50, 72, 150). Before the connecting element (100, 300) is sucked in, the suction surface (26, 54) is located at a first end position, which is spaced a certain distance from the end edge region of the sleeve along the setting direction (S), and moves to a second position in the opposite direction to the setting direction (S) during the setting process.

Description

TECHNICAL FIELD

[0001] The invention relates to a device for setting a connection element. BACKGROUND

[0002] According to the known manner, the device for setting a connection element having a head-side drive structure comprises a feed device for exerting an axial force. The feed device exerts a pressing force on a rotating spindle and a drive head connected thereto for moving it in a setting direction. In particular, according to the device of the invention, the force exerted on the rotating spindle, and thus on the connection element, is greater than 1.5 kN. The drive head has drive structures arranged on the end side in the circumferential direction in the setting direction for rotating the connection element in an interlocking manner. Furthermore, the drive head has an axial sleeve through which the connection element is sucked into position.

[0003] For example, EP 2 632 629 B1 discloses that the connection element can be temporarily held on the rotating spindle by means of negative pressure.

[0004] In the case of a connection element having a small drive structure and a coating, coating material resulting from wear of the coating can deposit on the drive structure, thereby causing the drive structure surface to be uneven, so that the drive structure of the connection element and the drive structure of the drive head no longer reliably engage with each other. When the connection element is held in position by means of negative pressure, this means that a sufficient negative pressure cannot be reliably achieved. As a result, a part that does not have the required high quality of manufacture or that cannot be processed must be rejected or will lead to a processing error.

[0005] DE 10 2018 103 991 A1 proposes to identify the position of the drive element in the setting device. SUMMARY

[0006] It is an object of the invention to provide a device for setting a connection element, which reliably holds the connection element on the drive head of the device and allows higher tolerances or surface irregularities when processing connection elements having a coating, thereby providing greater availability in industrial equipment manufacturing, i.e. reducing processing errors.

[0007] According to the invention, the device comprises an insertion element having a suction surface on its end side, which can abut against the head of the connection element and which circumferentially delimits a suction cross section, the insertion element being designed such that the suction surface is movable in the axial direction relative to the drive head.

[0008] Furthermore, the insertion element is designed such that negative pressure can be transmitted from a side of the insertion element facing away from the setting direction to the suction surface of the insertion element, which is located in a first end position at a distance from the end edge region of the sleeve adjacent to the suction surface in the setting direction, before the connection element is sucked in.

[0009] In this way, even if the coating of the connection element, in particular the coating in the drive structure, has inhomogeneities, the connection element can be reliably sucked to the insertion element and thus to the drive head.

[0010] This design ensures that the connection element is reliably held in the drive head, since the suction surface only comes into contact with the non-drive structure region of the connection element that is adjacent to the drive structure. The non-drive structure region of the connection element usually only has slight or no inhomogeneities caused by the coating.

[0011] Furthermore, the suction surface can be moved axially relative to the drive head such that the drive structure of the drive head is fully engaged to the connection element. This is achieved, in particular, when the connection element is placed on the component, preferably by applying a pressing force to the suction surface in an axial direction opposite the setting direction.

[0012] The connection element is thus reliably held in place in the insertion element until the connection element is placed behind the upper component, where it is introduced into the component under the action of rotational and axial forces.

[0013] The suction pressure with which the connection element is sucked to the insertion element and thus to the drive head is, in particular, at least 0.3 bar. The underpressure is thus preferably -0.3 bar to -0.85 bar.

[0014] Preferably, the drive head can have a surface, in particular a flat surface, for transmitting the axial force required for the welding process of the friction element to the connection element. Alternatively, the axial force can also be applied by the insertion element.

[0015] According to a further embodiment of the application, the drive structure of the drive head can be a drive structure for an external drive, the suction surface then being located radially inside the drive structure.

[0016] Alternatively, the drive structure on the end side of the drive head can be a drive structure for an internal drive, in which case the suction surface can be adjacent to or located radially outside the drive structure.

[0017] Preferably, the insertion element can comprise a sleeve which is designed to be movable relative to the drive head in the axial direction. The sleeve has a first contact surface, while the drive head has a second contact surface. The second contact surface is arranged in correspondence with the first contact surface such that, when the suction surface is in a predefined end position relative to the drive head, in particular slightly bulging in the setting direction, the contact surfaces interact in a sealing manner such that the underpressure can be transmitted through the sleeve.

[0018] This can preferably be achieved in that the contact surface of the sleeve is designed as a collar and the contact surface of the drive head is designed as a shoulder, the collar and the shoulder extending transversely to the setting direction. On the one hand, a sealing arrangement can be formed by the contact surfaces of the collar and the shoulder lying on top of one another, and on the other hand, a stop is formed between the collar and the shoulder to limit the axial movement between the sleeve and the drive head in the setting direction and thus to provide a predefined end position.

[0019] Preferably, the insertion element can be designed in such a way that the sleeve is pressed against the shoulder of the drive head in the setting direction by means of the spring pretension. In this way, the contact surfaces of the collar and the shoulder are actively pressed against one another, thus improving the sealing effect. Furthermore, this arrangement ensures that the suction surface is reliably held in the predefined end position relative to the drive head for the suction process under the action of the spring pretension of the sleeve, even if, for example, the setting direction is opposite to the direction of gravity.

[0020] As a result, the sleeve can have a greater radial play relative to the drive head, which in turn can improve the reliability of the axial movement, since the contact surfaces between the collar and the shoulder achieve a reliable, full seal in the axial direction.

[0021] The spring pretension is preferably generated by a spring device, which comprises at least one spring, which is supported on a spring support, which is fixedly arranged relative to the drive head.

[0022] In particular, the spring device can comprise a set of disc springs or a coil spring.

[0023] The spring support can be provided by a rotary spindle, in which case the drive head is screwed to the rotary spindle.

[0024] The spring support can also be provided by an insertion bushing, which is fixedly embedded in the drive head, for example, by an interference fit. The insertion sleeve can also be connected to the drive head in a transition fit, in particular an H7 / m6 fit.

[0025] Preferably, the drive head and the insertion bushing are matched to one another in such a way that the insertion bushing is supported by the friction spindle connected to the drive head during the joining process, and the insertion sleeve is supported on the shoulder in the drive head in the setting direction. This allows a plug-in connection from the drive head to the friction spindle, so that the sleeve with the loaded spring in the drive head can be replaced as a unit, and the machining forces are still transmitted from the spindle to the drive head.

[0026] The pretension is preferably selected in such a way that the pressing force from the shoulder to the collar is sufficient to achieve the required negative pressure, but is always less than the minimum axial force occurring during the joining process. To ensure that the drive head transmits the axial machining forces, forces of less than 1 kN, in particular between 5 N and 100 N, are usually used to achieve the required negative pressure.

[0027] The insertion element and its sleeve and the drive head are matched in such a way that the drive head, which has a pressure surface for transmitting the machining force, transmits more than 90% of the machining force via the pressure surface during the setting process.

[0028] According to a further preferred embodiment, the sleeve can have a stop element opposite the setting direction, which can abut against the rotary spindle and / or the insertion sleeve.

[0029] Hereby, the entire machining force or a partial machining force can be transmitted to the suction surface of the sleeve. The suction surface thus also serves as a pressure surface for transmitting the entire machining force or a partial machining force required for the joining process.

[0030] The length of the drive head and the sleeve and the axial distance by which the sleeve can be moved axially are matched to one another in such a way that, when the sleeve is in the stop position opposite the setting direction, the drive structure of the connecting element and the drive structure of the drive head engage with one another, and an axial machining force can be transmitted via the sleeve.

[0031] The stop element opposite the setting direction can be designed as a sleeve section which is designed to have a larger diameter than the end-side diameter of the suction surface, which transitions from the larger diameter to the smaller diameter in a stepped manner, thereby forming a shoulder structure. A spring is inserted in particular in the sleeve section with the larger diameter, which bears on the shoulder in the setting direction and on the spring support element in the direction opposite the setting direction.

[0032] According to a further embodiment, the stop element opposite the setting direction can be designed as a sleeve section which has the same diameter as the end-side diameter. A collar structure is provided on the sleeve, around which the spring bears, the sleeve preferably passing through the spring.

[0033] According to a particularly preferred embodiment, the contact surface opposite the setting direction is designed discontinuously, since the sleeve has a radial recess at the sleeve end facing the spring support element. Hereby, it can be ensured that dirt which penetrates into the insertion element does not deposit on the stop surface. Hereby, it can also be ensured that the coordination between the sleeve length and the axial moveable amount is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0034] Further advantages, features and possibilities of application of the present application result from the following description of embodiments shown in the drawings.

[0035] In the drawings:

[0036] Figure 1 is a sectional view according to a first embodiment of the application;

[0037] Figure 2a is a sectional view at the drive head;

[0038] Figure 2b is a sectional view at the drive head; Figure 2aSimilar sectional view, wherein the connecting element is pressed against the component layer;

[0039] Figure 3a Sectional view of the drive head through the drive structure in the suction position;

[0040] Figure 3b is Figure 3a in Figure 2b the working position;

[0041] Figure 4 is a schematic view of another embodiment according to the application;

[0042] Figure 5 is a sectional view of another embodiment according to the application;

[0043] Figure 6 is a sectional view of another embodiment of the sleeve;

[0044] Figure 7 is a sectional view of another embodiment of the sleeve;

[0045] Figure 8 is a sectional view of another embodiment of the drive head according to the application;

[0046] Figure 9a is a sectional view of another embodiment for machining a connecting element with an internal drive;

[0047] Figure 9b is a schematic view of the sleeve relative to the drive head along the setting direction of the corresponding protrusion, and

[0048] Figure 9c is Figure 9a sectional view along C-C. DETAILED DESCRIPTION

[0049] Figure 1For the device 10 for setting the connecting element 100 according to the application, which has a head-side drive structure, the device 10 comprises a feed device 12 for exerting an axial force, a rotary spindle 14 and a drive head 20 connected to the rotary spindle 14, which has a drive structure 22 arranged on the end side in the setting direction S, which rotates the connecting element 100 in an interlocking manner. The device 10 further comprises a suction unit 18, by means of which air can be sucked off on the end side of the drive head 20. As a result, the connecting element 100 can be sucked onto the end side of the drive head 20. After the connecting element 100 has been sucked onto the drive head, it is moved downwards in the setting direction S under the effect of the pressing force generated by the feed device 12 and the rotation of the rotary spindle 14 and is introduced into the component assembly 110, 112, as a result of which the connecting element 100 is passed through the upper component layer 110 and is further friction-welded to the lower component layer 112 by means of the frictional energy of the introduction. In the case shown here, the feed device 12 is moved relative to a counter holder 120, on which the component layers 110 and 112 are located during the connection process. A pressing holder for clamping the component layers 110, 112 can also generally be provided, which is not explicitly shown.

[0050] According to the application, an insertion element 24 is provided, which has a suction face 26 on its end side, which delimits a suction cross section 30 in the peripheral direction, the insertion element 24 being designed such that the suction face 26 can be moved in the axial direction relative to the drive head 20.

[0051] The negative pressure can be transmitted from the side of the insertion element 24 facing away from the setting direction S to the suction face 26 of the insertion element 24, which is located in a first end position before the connecting element 100 is sucked in, which is spaced apart from the end-side edge region of the sleeve by a distance in the setting direction S. During the setting process, the insertion element 24 is moved in the direction opposite to the setting direction S by a dimension E to a second position spaced apart from the first position.

[0052] Figures 2 to 9c describe different variants of the drive head 20 corresponding to different embodiments of the insertion element 24.

[0053] Figure 2a Sectional view of the first embodiment of the setting device according to the application at the drive head 42.

[0054] The setting device of this embodiment comprises a rotary spindle 40, which rotates the connecting element 100 and transmits the pressing force required for the connection to be generated.

[0055] In the present embodiment, the drive head 42 is screwed to the rotary spindle 40. The drive head 42 and the rotary spindle 40 are provided with a central passage 46 through which a suction effect can be generated at the end side of the drive head 42 by means of a suction unit 18, for example a suction pump or a Venturi nozzle.

[0056] An insertion element 50 is embedded in the drive head 42, which insertion element 50 comprises a sleeve 52 which has an annular suction face 54 at its end face side, the insertion element 50 transmitting the suction pressure to the connection element 100 which abuts against the suction face 54. The insertion element 50 also comprises a spring 56, in particular a helical spring, which is arranged between the rotary spindle 40 and the sleeve 52 such that the sleeve 52 is pre-tensioned in the setting direction S.

[0057] The sleeve 52 and the recess in the drive head 42 are matched to one another such that the sleeve 52 is movably supported in the axial direction and forms a first stop which sets the maximum length A of the sleeve 52 protruding against the pressing face 48.

[0058] By setting the protruding length A in the suction position, the suction face 54 can abut well against the head surface of the connection element 100, since an inclination of the connection element 100 due to a coating deposit of the drive of the connection element 100 can be avoided.

[0059] Furthermore, the end of the sleeve 52 opposite the setting direction S is aligned with the drive head 42 and the rotary spindle 40 such that the sleeve 52 abuts against the rotary spindle 40 when the suction face 54 is at the same level as the pressing face 48 of the drive head 42.

[0060] The stop is designed such that the distance B in the suction position is at least as great as the protruding length A. Thereby it can be ensured that a large part of the pressing force is transmitted to the connection element 100 by means of the drive head 42.

[0061] If the distance B is equal to the protruding length A, a part of the pressing force can also be transmitted from the rotary spindle 40 to the connection element 100 by means of the sleeve 52.

[0062] Figure 2b In order to transmit the pressing force to the connection element 100 when the connection element 100 is pressed against the component layer 110, 112 Figure 2a The setting of the application shown here. At this time, the sleeve 52 is moved against the spring force of the spring 56 until the suction face of the sleeve 52 is flush with the pressing face 48 of the drive head 42. If the pressing force is not transmitted by means of the sleeve 52, the sleeve 52 and the recess in the drive head 42 are matched such that the sleeve 52 does not abut against the rotary spindle in the pressing state.

[0063] In contrast, when the suction face 54 of the sleeve 52 is flush with the pressing face 48 of the drive head 42, in the arrangement of the sleeve 52 against the rotating spindle 40, part of the pressing force can also be transmitted via the suction face, in total a greater force transmission area can be achieved. Thereby the indentation in the head of the connection element 100 can be reduced, whereby in particular the coating of the connection element provided for protection against corrosion can be protected. In this case the advancement amount C corresponds to the protrusion length A.

[0064] Figure 3a is a sectional view through the drive head 42 in the sucked-in contact position. This figure clearly shows that there is a clear distance D between the drive structure 44 of the drive head 42 and the driver of the connection element 100, so that excess coating deposited on the drive structure does not influence the position of the connection element 100 relative to the drive head 42.

[0065] Figure 3b is a sectional view through the drive head 42 in the sucked-in contact position. This figure clearly shows that there is a clear distance D between the drive structure 44 of the drive head 42 and the driver of the connection element 100, so that excess coating deposited on the drive structure does not influence the position of the connection element 100 relative to the drive head 42. Figure 3a In Figure 2b is a detailed view of the working position shown. It can be clearly seen that in the working position the drive structure 44 of the drive head 42 and the driver of the connection element 100 are engaged interlockingly with one another. The distance D is significantly smaller than the distance in Figure 3a .

[0066] Figure 4 is a further embodiment according to the application, the insertion element is designed as an axially elastic, circumferentially closed element, in particular as an O-ring 62, the elastic element being inserted at the end sides into the drive head 60.

[0067] The elasticity of the elastic element and the cross section of the element are matched to one another in such a way that when the cross section is enlarged, the suction face is spaced apart from the pressing face of the drive head 60 in the setting direction by a defined distance, and when the connection element 100 is pressed by the machining force, the insertion element is compressed so that the pressing face of the drive head 60 rests against the head of the connection element 100, at which point the insertion element is at the same level as the pressing face.

[0068] The defined distance is selected in such a way that the drive structure of the drive head 60 and the connection element 100 hardly engage interlockingly with one another, as is also shown in Figure 3a , 3b .

[0069] The Shore hardness of the elastic element is preferably between 50 and 120 Shore A.

[0070] The advantage of this embodiment is that the insertion element does not have to comprise any moving parts, the axial displacement of the suction face being achieved only by elastic deformation of the insertion element.

[0071] Figure 5For a sectional view according to a further embodiment of the application, the drive head 70 is screwed to the rotary spindle 68. An insertion element 72 comprising a sleeve 74 and a coil spring 76 is axially movably embedded in the drive head 70. The design with respect to the axial stop corresponds essentially to the embodiment shown in Fig. 2. In contrast to Fig. 2, a significantly greater width of the suction face 26 is chosen, the suction face 26 being designed as an annular face, so that the machining force is essentially transmitted to the connection element 100 by the insertion element 72, i.e. in particular by the sleeve 74. In this embodiment, the length of the sleeve and the distance of the head abutment region of the drive head 70 are identical. As described in Fig. 2, the coil spring 76 ensures that the sleeve 74 is axially positioned in the suction position when the sleeve 74 is not subjected to external loads.

[0072] Figure 6 A further embodiment is shown, which has a stop in the form of a continuous sleeve 84 at the rotary spindle 82, the sleeve 84 having a collar 88 extending radially outwards. A spring 86 is located at the upper end of the sleeve 84 and bears against the rotary spindle 82 and the collar 88. The collar 88 forms a stop face on the drive head 80 on its side facing away from the spring, which determines the protruding length C in the suction state.

[0073] Figure 7 A particularly preferred design of the sleeve 90 is shown, which can be applied with minor modifications in any of the embodiments shown in the above-mentioned figures, i.e. with a recess 96, in particular a circumferential recess 96, at the sleeve end 92 facing the rotary spindle. This arrangement makes it possible for dirt sucked in by the sleeve in the suction action not to deposit between the sleeve 90 and the friction spindle, but rather to enter the intermediate space formed by the recess 96. This largely prevents a build-up of dirt between the sleeve 90 and the rotary spindle, which would result in a displacement of the stop in the axial direction.

[0074] Figure 8 A further embodiment of the application is shown, which differs from the above-described examples in two respects. Firstly, the sleeve 152 exerts a stop only on the spring 156. Secondly, the drive head 142 has a stop face acting on the insertion element 150, so that the drive head 142 and the insertion element 150 can be assembled and disassembled together as a component of the rotary spindle 140.

[0075] The stop face is preferably an end face of the insertion bushing 144, which is pressed in particular with an interference fit into the drive head 142. The drive head 142 also has a locking device, which can be connected to a locking device of the rotary spindle 140, so that a rotary movement can be transmitted, the front end of the rotary spindle 140 abutting against the insertion bushing 144. The insertion bushing 144 preferably abuts against a shoulder of the drive head 142 in the direction of installation. This arrangement makes it possible for the machining force to be transmitted to the drive head 142 in a form-locked manner.

[0076] In this way a quick-change device can be produced which allows the insertion element 150 to be easily replaced in the event of wear or damage.

[0077] The spring 156 can be dimensioned such that the sleeve 152 fully compresses the spring 156 when the suction face is at the same level as the drive head 142, so that the machining force is transmitted via the sleeve 152 to the connection element 100. Alternatively, the spring is not yet fully compressed, so that only the spring force acts via the sleeve 152 on the connection element 100.

[0078] The design of the insertion element 150 can be combined with the insertion element 150 shown in the other embodiments as required.

[0079] Figure 9a A further alternative embodiment is shown for machining a connection element 300 with an internal drive. In this embodiment, the compression region and the suction face are located outside the internal drive, and the machining force is transmitted via a sleeve 252. Correspondingly, the sleeve 252 abuts against the rotary spindle receiving element 246 when the drive head 242 is fully engaged with the drive of the connection element 300. As before, the protrusion in the suction position is produced by a spring 256, in particular a helical spring.

[0080] A plurality of suction channels 248 are provided in the drive head 242, which each incorporate a suction channel 258 in the sleeve 252, so that the connection element 300 can be sucked into the correct position.

[0081] Figure 9c For a more detailed cross-sectional view.

[0082] Figure 9b The corresponding protrusion length A of the sleeve 252 relative to the drive head 242 in the setting direction is shown. In this way, the internal drive of the connection element 300 is not yet fully engaged when the connection element is sucked into the correct position.

[0083] Figure 9c For Figure 9a Cross-sectional view along C-C. The suction channels 258 of the sleeve 252 are distributed in a circular ring along the compression face of the sleeve 252. The drive head 242 is centrally located in the sleeve 252, which can be moved axially relative to the drive head 242.

Claims

1. An apparatus (10) for setting connecting elements (100, 300) having a head-side drive structure, comprising a feed device (12) for applying an axial force, a rotary spindle (14, 40, 68, 82, 140) and a drive head (20, 42, 60, 70, 80, 142, 242) connected to the rotary spindle, the drive head having drive structures (22, 44) arranged in the end in the setting direction (S) in a circumferential manner for rotating the connecting elements (100, 300) in an interlocking manner, the drive head (20, 42, 60, 70, 80, 142, 242) having an axial sleeve; the apparatus further comprising a suction unit (18) by means of which air can be sucked off on the end side of the drive head (20, 42, 60, 70, 80, 142, 242), characterized in that An insertion element (24, 50, 72, 150) is also provided, which has a suction face (26, 54) on the end side, which circumferentially delimits a suction cross section (30), which is designed such that the suction face (26, 54) can be moved in the axial direction relative to the drive head (20, 42, 60, 70, 80, 142, 242) and such that a negative pressure can be transmitted from the side of the insertion element (24, 50, 72, 150) facing away from the setting direction (S) to the suction face (26, 54) of the insertion element (24, 50, 72, 150), which is located in a first end position spaced apart from the end-side edge region of the sleeve in the setting direction (S) before the connection element (100, 300) is sucked in and which is moved in the setting direction (S) to a second position during the setting.

2. The apparatus of claim 1, wherein, The insertion element (24, 50, 72, 150) comprises a sleeve (52, 74, 84, 90, 152, 252) having a first contact face, the drive head (42, 70, 80, 142, 242) having a second contact face which is designed in correspondence to the first contact face such that the contact faces interact in a sealing manner to enable the transmission of a negative pressure through the sleeve (52, 74, 84, 90, 152, 252) when the suction face is in a predefined end position relative to the drive head (42, 70, 80, 142, 242).

3. The apparatus of claim 2, wherein, The contact face of the sleeve (52, 74, 84, 90, 152, 252) is designed as a collar and the contact face of the drive head (42, 70, 80, 142, 242) is designed as a shoulder, the collar and the shoulder extending transversely to the setting direction.

4. The apparatus of claim 3, wherein, The sleeve (52, 74, 84, 90, 152, 252) is pressed against the shoulder of the drive head (42, 70, 80, 142, 242) in the setting direction by a spring pretension.

5. The apparatus of any one of claims 1 to 4, wherein, The end position is spaced apart from the end side of the drive head by 0.1 mm to 4 mm.

6. The apparatus of claim 4, wherein, The spring pretension is generated by at least one spring (56, 76, 86, 156, 256) which is indirectly supported on a spring support element which is fixed relative to the drive head or directly on the drive head.

7. The apparatus of claim 6, wherein, The spring is an elastic element.

8. The apparatus of claim 6, wherein, The spring is a rubber element.

9. The apparatus of claim 6, wherein, The spring is designed as an O-ring.

10. The apparatus of claim 6, wherein, The spring support element is formed by a rotary spindle (14, 40, 68, 82) which is screwed to the drive head (42, 60, 70, 80).

11. The apparatus of claim 6, wherein, The spring support element is formed by an insertion bushing (144) which is fixedly embedded in the drive head (142).

12. The apparatus of claim 11, wherein, The insertion bushing (144) serves as a bearing for the rotary spindle and is supported in the setting direction on a shoulder in the drive head (142).

13. The apparatus of any one of claims 4 and 6-12, wherein, The spring pretension exerts a force of 5 N to 100 N on the sleeve (52, 74, 84, 90, 152, 252).

14. The apparatus of any of claims 2-4 and 6-12, wherein, The sleeve (52, 74, 84, 90, 152, 252) has an inner diameter of 1.0 mm to 10 mm and a wall thickness of 0.5 mm to 5 mm.

15. The apparatus of claim 11, wherein, The sleeve (52, 74, 84, 90, 252) has a stop facing away from the installation direction, which bears against the rotary spindle (14, 40, 82, 140) or an insertion bushing (144), whereby the entire machining force or part of the machining force is transmitted to the sleeve end side.

16. The apparatus of claim 15, wherein, The stop is designed as a sleeve section having a larger diameter than the end side diameter, and the spring (56, 76) is located in the sleeve (52, 74).

17. The apparatus of claim 15, wherein, The stop is designed as a sleeve section having the same diameter as the end side diameter, and the spring (86) is supported on a collar arranged around the sleeve (84).

18. The apparatus of claim 16 or 17, wherein, The sleeve end (92) facing the rotary spindle is designed discontinuously with at least one recess (96) for accommodating dirt.

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