Tool holder with grooved ring

Abstract

The invention relates to a tool holder (10) for clamping a tool (11) using a collet (62). The tool holder (10) has a base body (12) comprising a machine connection part (14) that provides an interface to a spindle mount of a machine spindle. A receiving chamber (15) is provided in the base body (12) in which a clamping rotor (29) is arranged. The clamping rotor (29) is supported axially parallel to a central axis (A) of the base body (12) between a first axial bearing surface (22) of the base body (12) and a second axial bearing surface (46) on a bearing ring (43). The bearing ring (43) is held in the receiving chamber (15) by means of a groove ring (53) inserted into a retaining groove (23). The bearing ring (43) has an outer ring surface (44) for contact with the base body (12) and an inner ring surface (45) for contact with the clamping rotor (29).The bearing ring (43) allows the clamping rotor (29) to be positioned very precisely in the radial direction relative to the base body (12) and thus very precisely coaxially with the central axis (A) of the base body (12). The bearing ring (43) is, in particular, threadless and also secured to the base body (12) without threads.

Description

[0001] The invention relates to a tool holder designed to clamp a tool. The tool holder and the tool clamped therein are preferably driven to rotate about a central axis of the tool holder, which ideally also represents the central axis of the tool. The tool can be a cutting tool, such as a milling cutter or a drill.

[0002] A tool holder of this type is known, for example, from DE 10 2018 111 044 A1. The tool holder has a base body with a machine connection part that provides an interface to a machine spindle mount. A receiving chamber is provided in the base body. A clamping rotor can be inserted into this receiving chamber and secured by means of a tube-like bearing seat element. The bearing seat element is screwed into an internal thread of the base body via an external thread. It is located within the receiving chamber. A collet can be drawn into the receiving chamber with the aid of the clamping rotor. The tool to be clamped can be clamped radially to the central axis and held by means of the collet.

[0003] DE 10 2018 133 474 A1 describes a collet for receiving a tool shank, which has a locking element in a through-hole and a preloading device that holds the tool shank and the locking element in contact.

[0004] This solution has proven itself in practice and offers high clamping reliability. It also allows for high feed rates and high material removal rates when using the tool.

[0005] The object of the present invention is to further optimize the known tool holder, in particular to reduce the axial length of the tool holder and to improve the positioning accuracy of the tool to be clamped in the radial direction radial to the central axis of the tool holder.

[0006] This problem is solved by a tool holder having the features of claim 1.

[0007] The tool holder according to the present invention is designed for clamping a tool. With the tool mounted and clamped, the tool holder can be moved, positioned, and, in particular, rotated about a spindle axis of the machine spindle by means of a machine spindle of a machine (for example, a machine tool). The tool is, in particular, a cutting tool, such as a milling cutter or a drill.

[0008] The toolholder has a base body. Attached to the base body is a machine connection part, designed for the detachable mounting of the toolholder in the machine spindle or a machine spindle mount. The machine connection part can form a standardized interface, for example, a hollow taper shank (HSK) or a steep taper shank (SK), or another standardized design. The machine connection part is, in effect, the interface between the toolholder and the machine spindle mount of the machine.

[0009] The base body defines a central axis, with the machine connection extending as closely as possible coaxially to this central axis. This allows the central axis of the tool holder to be aligned with the spindle axis of the machine spindle when the tool holder is mounted on the machine spindle. The rotation of the machine spindle about its spindle axis thus results in a rotation of the tool holder and any tool held within it about its central axis.

[0010] Unless explicitly stated otherwise, the following directional terms are used in this description: An axial direction is understood to be a direction parallel to the central axis. A radial direction is oriented radially to the central axis. A circumferential direction describes the direction along a circular path around the central axis.

[0011] The base body has a receiving space. This receiving space is accessible from a front side facing away from the machine connection part via an access opening. The access opening is located on an end face of the base body. A first axial bearing surface of the base body adjoins the receiving space. The first axial bearing surface faces the access opening and is positioned at a distance from it. The first axial bearing surface can extend in a plane that is oriented perpendicular to the central axis. The first axial bearing surface can be completely closed in a circumferential ring shape.

[0012] Adjacent to the access opening, the base body has a locking groove. This locking groove can be completely closed in the circumferential direction. Alternatively, it can have an open, arc-shaped profile in the circumferential direction. In cross-section, the locking groove is, for example, rectangular. The locking groove is open towards the receiving space. A grooved ring can be inserted into the locking groove via the access opening and the receiving space.

[0013] Adjacent to the receiving space, the base body has a circumferential inner surface arranged axially between the locking groove and the first axial bearing surface. This circumferential inner surface is, in particular, a preferably cylindrical surface arranged as closely as possible to the central axis. The circumferential inner surface can adjoin the locking groove directly in the axial direction and is preferably arranged at a distance from the first axial bearing surface. The circumferential inner surface is preferably a flat surface in the axial and / or circumferential direction.

[0014] The toolholder has a clamping rotor located within the holding area. To clamp a tool, the clamping rotor can be rotated around its central axis relative to the base body using an operating device, such as a rotary mechanism, located on the base body. Without actuation of the operating or rotary mechanism, the clamping rotor is held or fixed in its current rotational position relative to the base body, thus preventing unintentional relative rotation of the clamping rotor with respect to the base body when the toolholder is used in a machine spindle. The coupling between the operating or rotary mechanism and the clamping rotor can be achieved by means of a gearbox that provides sufficient resistance against unintentional release of the clamping rotor relative to the base body (for example, a worm gear or spindle gear).

[0015] The clamping rotor has a clamping thread. This thread is designed to engage with the collet thread of a collet. The clamping thread is specifically an internal thread. By rotating the clamping rotor around its central axis relative to the base body (for example, using the rotary device), a threaded connection between the clamping thread and the collet thread can be established or released.

[0016] The clamping rotor also has a pipe section. This pipe section is positioned at a distance from the clamping thread, particularly in the axial direction. The pipe section has an outer surface facing away from the central axis.

[0017] The tool clamp also has a bearing ring that can be detachably mounted on the base body. The bearing ring has an inner surface facing the central axis and an outer surface facing away from both the central axis and the inner surface. The inner and outer surfaces are preferably coaxial with the central axis and preferably coaxial with each other. In a preferred embodiment, the outer and inner surfaces are flat in the axial and / or circumferential direction.

[0018] A perfectly coaxial arrangement without any deviation is technically unattainable. In particular, coaxial arrangements can exhibit deviations relative to the central axis of a maximum of 10 µm, or preferably a maximum of 7.0 µm, or even more preferably a maximum of 5.0 µm, and still allow for sufficiently accurate clamping of a tool.

[0019] The bearing ring also has a second axial bearing surface, which faces the first axial bearing surface and thus away from the access opening. The second axial bearing surface preferably extends in a plane perpendicular to the central axis. The second axial bearing surface can be a connecting surface between the inner and outer surfaces of the ring, or at least a section thereof. The second axial bearing surface is preferably completely closed in the circumferential direction.

[0020] The clamping rotor is supported in the axial direction indirectly or directly on the first axial bearing surface and the second axial bearing surface and is thus secured in the axial direction against an undesired relative movement to the base body.

[0021] The bearing ring is, in particular, threadless. In the axial direction, the bearing ring is supported on one side indirectly or directly by the clamping rotor and on the other side by the grooved ring, which is inserted into the retaining groove.

[0022] The bearing ring and the grooved ring allow for a very compact design of the tool holder in the axial direction.

[0023] The inner surface of the ring can form a two-dimensional, planar contact with the outer surface of the clamping rotor's tube section, while the outer surface of the ring forms a two-dimensional, planar contact with the circumferential inner surface of the base body. This allows the bearing ring to be positioned very precisely in the radial direction, which in turn ensures that the clamping rotor's tube section is aligned very accurately in the radial direction relative to the central axis. Compared to a screwed-in bearing element, this results in high radial positioning accuracy for the clamping rotor and, consequently, for the tool being clamped.

[0024] When manufacturing a threaded connection, a relative position between the connected parts can arise in the radial direction due to the interlocking threads. This relative alignment is highly dependent on the accuracy of the thread production. High-precision thread manufacturing is complex. In contrast, the bearing ring offers the possibility of providing flat surfaces (inner and outer ring surfaces) in both the circumferential and axial directions. Each of these surfaces, together with a corresponding flat surface (in particular, the inner circumferential surface on the pipe body or the outer surface on the pipe section), allows for a fit with minimal play and thus very high positioning accuracy. A collet chuck inserted or screwed into the pipe section can therefore be aligned and positioned very precisely in the radial direction.This positioning accuracy does not require high-precision manufacturing of the clamping thread and the collet thread.

[0025] It is preferred that the inner circumferential surface and the outer ring surface form a first pair of mating surfaces and the inner ring surface and the outer tube surface form a second pair of mating surfaces, wherein the mating surface pairs are each designed as a low-clearance fit or as a zero-clearance fit. The mating surfaces of the two mating surface pairs are threadless and preferably flat surfaces viewed in the circumferential and axial directions.

[0026] As explained, a rotary device can be present on the base body, which may, for example, have an externally accessible tool interface or another suitable operating element. The rotary device can be actuated via the tool interface, so that the rotary device can also be referred to as an operating device. The rotary device has a coupling device (e.g., a gearbox) that is coupled to the clamping rotor. The coupling device is designed to be self-locking. When the tool interface is actuated, the clamping rotor rotates around its central axis relative to the base body. This relative rotational position between the clamping rotor and the base body is maintained when the tool interface, and thus the rotary device, is not actuated, i.e., even when the tool holder is in use with the clamped tool (e.g., in the ready-to-use state inserted into the machine spindle).

[0027] In a preferred embodiment, the tool holder has a thrust bearing arrangement. The thrust bearing arrangement is configured to support the clamping rotor axially against the first thrust bearing surface and / or the second thrust bearing surface. In a preferred embodiment, the thrust bearing arrangement includes a rolling bearing located between the first thrust bearing surface and the clamping rotor, so that the clamping rotor can be indirectly supported against the first thrust bearing surface via the rolling bearing. Alternatively or additionally, a support ring of the thrust bearing arrangement can be provided between the first thrust bearing surface and / or the second thrust bearing surface on the one hand and the clamping rotor on the other.

[0028] The at least one support ring can be in direct contact with the clamping rotor. The contact between the clamping rotor and the rolling bearing on the one hand, and the second axial bearing surface on the other, can be improved via the at least one support ring, and in particular the contact area in the radial direction can be increased.

[0029] The base body may have an annular support surface adjacent to the receiving space. This annular support surface can be arranged around the central axis, for example, as coaxially as possible, and be closed in a ring shape in the circumferential direction. The annular support surface faces the access opening and preferably extends in a plane that is perpendicular to the central axis.

[0030] The ring support surface can be located adjacent to the inner circumferential surface of the base body. The inner circumferential surface is situated between the ring support surface and the retaining groove. The bearing ring can be supported axially against the ring support surface.

[0031] In a preferred embodiment, the ring support surface has an inner diameter that is at least as large as the outer diameter of the first axial bearing surface. Preferably, the inner diameter of the retaining groove is at least as large as the outer diameter of the ring support surface.

[0032] The tool holder preferably has a front section with a clamping channel. The clamping channel is bounded by a conical inner clamping surface of the front section. The inner clamping surface completely encloses the central axis in the circumferential direction. When the collet is clamped into the clamping rotor, the inner clamping surface on the clamping channel of the front section forces the collet radially inwards to clamp and fix a tool positioned therein within the collet.

[0033] The front part can be detachably attached to the base body, for example, via a threaded connection or another suitable connection. When the front part is connected to the base body, the clamping channel is located adjacent to the access opening. The front part is specifically not designed to secure or axially support the clamping rotor, the bearing ring, or any other component of the tool holder located within the receiving space of the base body.

[0034] The front part can be arranged on the base body such that the relative position in the radial direction between the collet with the tool to be clamped and the base body is defined mainly or exclusively by the bearing ring and the clamping rotor, and in particular by the tubular section of the clamping rotor. For example, the front part can be slightly movable in the radial direction relative to the base body, for example by providing a corresponding radial clearance in the connection between the front part and the base body.

[0035] Advantageous embodiments of the invention are described in the dependent claims, the description, and the drawing. Preferred embodiments of the invention are explained in detail below with reference to the accompanying drawing. The drawing shows: Fig. 1 a side view of an exemplary embodiment of a tool holder, Fig. 2 of the tool holders made of Fig. 1 in a perspective exploded view, Fig. 3 of the tool holders according to Fig. 1 and Fig. 2 in a partially cut side view in exploded view, Fig. 4 of the tool holders according to the Fig. 1 to 3 in a longitudinal section along a central axis of the tool holder, Fig. 5 a partial representation of the front area of ​​the tool holder according to the Fig. 1 to 4 in a longitudinal section along the central axis, Fig. 6. A highly schematic diagram illustrating the structure and function of the tool holder according to the Fig. 1 to 5 and Fig. 7 and Fig. 8 a modified embodiment of a bearing ring for a tool holder according to the Fig. 1 to 6.

[0036] In the Fig. Figures 1 to 4 show an exemplary embodiment of a tool holder 10 in different representations. The tool holder 10 is designed to clamp a tool 11. In its ready-for-use state, the tool 11 is clamped in a force-fit direction radially to a central axis A.

[0037] The following descriptions of the embodiments shown in the figures also apply: A direction parallel to the central axis A is called the axial direction. A radial direction is aligned radially to the central axis A. A circumferential direction describes the direction along a circular path around the central axis.

[0038] The tool holder 10 has a base body 12. The base body 12 has a machine connection part 14 on its rear side 13. The machine connection part 14 provides an interface for the tool holder 10, enabling it to be mounted in a spindle holder of a machine spindle and driven by the spindle. The machine connection part 14 has a shape that corresponds to a standardized interface to a machine spindle, for example, a tool taper, which is illustrated here as an example of a steep shank taper (SK). Alternatively, a hollow shank taper (HSK) or another standardized interface could be used as the machine connection part 14 instead of a steep shank taper.

[0039] The base body 12 contains a receiving chamber 15. The receiving chamber 15 can have a cylindrical and / or conical shape, at least in sections, and different diameters can result in a stepped shape of the recess, as is the case in the present embodiment. The receiving chamber 15 is accessible from the outside at a front face 16 opposite the rear face 13 of the base body 12 by means of an access opening 17. In the embodiment, the access opening 17 is circular and enclosed in a circumferential direction around the central axis A by a tubular section 18 of the base body 12. The tubular section 18 is hollow and, for example, arranged as coaxially as possible with the central axis A.

[0040] In the axial direction, at a distance from the access opening 17, the base body 12 has a first axial bearing surface 22 adjacent to the receiving space 15. In the exemplary embodiment, the first axial bearing surface extends in a plane that is oriented perpendicular to the central axis A. The first axial bearing surface 22 faces the access opening 17. In the exemplary embodiment, the first axial bearing surface 22 is designed as an annular surface and is planar in both the radial and circumferential directions. A diameter D1 of the access opening 17 is at least as large as or larger than an outer diameter D2 of the first axial bearing surface 22.

[0041] Adjacent to the access opening, the base body 12 has a locking groove 23. The locking groove 23 is, for example, designed as an annular groove and completely encloses the central axis A in the circumferential direction. Preferably, the locking groove 23 is arranged as closely as possible to the central axis A. The locking groove 23 is open in the radial direction, i.e., towards the central axis A and the receiving space 15. The cross-section of the locking groove 23 can be rectangular or square. The locking groove 23 is, for example, arranged in the tube section 18 of the base body 12.

[0042] Between the first axial bearing surface 22 and the retaining groove 23, a circumferential inner surface 24 is provided on the base body 12, adjacent to the receiving space 15. The circumferential inner surface 24 is arranged as precisely as possible coaxially with the central axis A and can preferably be designed as a cylindrical surface. The circumferential inner surface 24 is, for example, a flat surface in both the axial and circumferential directions. The circumferential inner surface 24 can be directly adjacent to the retaining groove 23 or arranged at a distance from it. In the exemplary embodiment, the circumferential inner surface 24 is arranged on the tube section 18 of the base body 12.

[0043] Between the circumferential inner surface 24 and the first axial bearing surface 22, the base body 12 has an annular support surface 25. The annular support surface 25 faces the access opening 17 and extends, for example, in a plane that is perpendicular to the central axis A. The annular support surface can be directly adjacent to the circumferential inner surface 24. In the exemplary embodiment, the annular support surface 25 is arranged in the tube section 18 of the base body 12.

[0044] In this embodiment, the diameter of the circumferential inner surface 24 corresponds to the diameter D1 of the access opening 17. The outer diameter of the ring support surface 25 can be equal to or smaller than the diameter of the ring support surface 25. The inner diameter D3 of the ring support surface 25 is smaller than the diameter of the circumferential inner surface 24 and, for example, also smaller than the diameter D1 of the access opening 17. The outer diameter of the ring support surface 25 can be equal to or smaller than the diameter of the ring support surface 25. The inner diameter D3 of the ring support surface 25 is smaller than the diameter of the circumferential inner surface 24 and, for example, also smaller than the diameter D1 of the access opening 17.

[0045] The receiving space 15 is designed to accommodate a clamping rotor 29 within the receiving space 15 of the base body 12. The clamping rotor 29 has a clamping thread 30. The clamping thread 30 is designed as an internal thread and can be arranged in a tubular end piece 31 of the clamping body. A central part 32 of the clamping rotor 29 connects to the tubular end piece 31. On the side of the central part 32 opposite the end piece 31, the clamping rotor 29 has a tubular section 33 with an outer surface 34. In this embodiment, the outer surface 34 is cylindrical and thus extends in a planar manner in both the axial and circumferential directions. The outer surface 34 is arranged as closely as possible to the central axis A.

[0046] By means of a rotary device 35 (see in particular Fig. 6) The clamping rotor 29 can be rotated relative to the base body 12 about the central axis A. The rotating device 35 can also be referred to as the operating device, by means of which the clamping rotor 29 can be actuated or rotated relative to the base body 12. For this purpose, the rotating device 35 has an operating element 36 arranged on the base body 12 and accessible from the outside. The operating element 36 can have a standardized interface to allow it to be actuated and, for example, rotated with a tool. The operating element 36 can therefore have a tool interface for a standard tool, such as a wrench, a screwdriver, a hex key, a Torx key, etc. For example, the operating element 36 can have an internal hexagon, an external hexagon, an internal Torx, or another known standardized tool interface.

[0047] The rotary device 35 also has a coupling device 37 and, in particular, a coupling gear for coupling the operating element 36 to the clamping rotor 29 and, for example, to the central part 32. The coupling device 37 can, for example, be a worm gear or have a worm gear. In the exemplary embodiment, the coupling device 37 has a worm shaft 38 rotatable about its longitudinal axis by the operating element 36, which engages with a worm wheel 39 arranged about the central axis A and non-rotatably connected to the clamping rotor 29. The worm wheel 39 can be an integral or monolithic part of the clamping rotor 29. For example, the worm shaft 38 extends perpendicularly to and at a distance from the central axis A. A schematic representation of the rotary device 35 is shown in Fig. 6 shown schematically.

[0048] Preferably, the coupling device 37 (for example, the worm gear) is designed to provide sufficient resistance. Without actuation of the operating element 36, this prevents relative rotation of the clamping rotor 29 relative to the base body 12 under the forces, torques, and vibrations occurring during operation. Forces acting on the clamping rotor during normal use of the tool holder 10 therefore do not result in relative rotation with respect to the base body 12. Such relative rotation can only be achieved via the rotary device 35 and, for example, the operating element 36.

[0049] The clamping rotor 29 has an inner rotor space 40 which, in the exemplary embodiment, completely extends through the clamping rotor 29 in the axial direction. At least the inner rotor space 40 is accessible from the side of the clamping rotor 29 associated with the access opening 17 and is bounded at least at one point by the clamping thread 30.

[0050] The tool holder 10 has a bearing ring 43 for axial support of the clamping rotor 29. The bearing ring has an outer ring surface 44 facing away from the central axis A and an inner ring surface 45 facing the central axis A. The outer ring surface 44 and the inner ring surface 45 can overlap completely or partially in the axial direction and, in one embodiment, are arranged as closely as possible to each other and as closely as possible to the central axis A. The axial extent of the outer ring surface 44 and the inner ring surface 45 can differ, with the axial extent of the outer ring surface 44 being smaller than the axial extent of the inner ring surface 45. The outer ring surface 44 and the inner ring surface 45 are planar in both the axial and circumferential directions.

[0051] The outer diameter of the ring's outer surface 44 and the diameter of the circumferential inner surface 24 are selected such that the ring's outer surface 44 and the circumferential inner surface 24 form a first pair of mating surfaces. The diameter of the ring's inner surface 45 and the diameter of the tube's outer surface 34 are selected such that the ring's inner surface 45 and the tube's outer surface 34 form a second pair of mating surfaces.

[0052] The bearing ring 43 can be pressed into the base body 12. The first pair of mating surfaces, consisting of the outer ring surface 44 and the inner circumferential surface 24, therefore forms a backlash-free press fit. Additionally, the second pair of mating surfaces, consisting of the inner ring surface 45 and the outer tube surface 34, can also form a backlash-free fit.

[0053] As can be seen particularly in the detailed presentation in Fig. As can be seen in Figure 5, the bearing ring 43 is arranged, for example, between the tube section 18 of the base body 12 and the tube section 33 of the clamping rotor 29. The bearing ring 43 rests with its outer ring surface 44 against the circumferential inner surface 24 and with its inner ring surface 45 against the outer tube surface 34. The two pairs of mating surfaces 44, 24 and 45, 34 ensure a very precise radial alignment of the tube section 33, and thus of the clamping rotor 29, relative to the central axis A.

[0054] The bearing ring 43 is threadless and is arranged, for example, without a threaded connection in the receiving space 15 of the base body 12.

[0055] A second axial bearing surface 46 is provided on the bearing ring 43. The second axial bearing surface 46 faces the first axial bearing surface 22. In the exemplary embodiment, the second axial bearing surface 46 extends in a plane that is oriented perpendicular to the central axis A. The second axial bearing surface 46 can be formed by an end face or an end face section of the bearing ring 43 that connects the outer ring surface 44 with the inner ring surface 45.

[0056] The clamping rotor 29 is held axially between the first axial bearing surface 22 of the base body 12 and the second axial bearing surface 46 of the bearing ring 43 and secured against unwanted axial movement. For this purpose, the clamping rotor 29 can be supported directly or indirectly by the axial bearing surfaces 22 and 46.

[0057] In the illustrated embodiment, the tool holder 10 has a thrust bearing arrangement 50 for supporting the clamping rotor 29. In this embodiment, the thrust bearing arrangement 50 has a rolling bearing 51, which can be, for example, a cylindrical roller bearing or a needle roller bearing. The rolling bearing 51 is supported, for example, directly on the first thrust bearing surface 22. The clamping rotor 29, and, for example, its central part 32, are supported on the rolling bearing 51 via a support ring 52. In this embodiment, the rolling bearing 51 and the support ring 52 surround the end piece 31 of the clamping rotor 29 in the circumferential direction around the central axis A.

[0058] The axial bearing arrangement 50 can also have a further support ring 52, by means of which the clamping rotor 29 and, for example, the central part 32 are supported on the second axial bearing surface 46 of the bearing ring 43.

[0059] The contact area and force transmission between the central part 32 of the clamping rotor 29 and the rolling bearing 51 and / or the relevant axial bearing surface 22 or 46 can be improved by the inclusion of at least one optional support ring 52.

[0060] In the axial direction towards the access opening 17, the bearing ring 43 is held or secured in the exemplary embodiment by a grooved ring 53. The grooved ring 53 can, for example, be a snap ring. In the exemplary embodiment, the grooved ring 53 has a rectangular ring cross-section and extends circumferentially around the central axis A in a circular arc. Two ring ends 54 of the grooved ring 53 are arranged at a distance from each other, so that the grooved ring 53 has an opening between the ring ends 54.

[0061] The grooved ring 53 is elastically deformable, so that its ring ends 54 can, starting from a starting position ( Fig. 2) can be moved towards each other to change the diameter of the grooved ring 53 due to elastic deformation. The outer diameter of the grooved ring 53 can be reduced by elastic deformation so that it can be moved through the access opening 17 into the receiving chamber 15 and inserted into the retaining groove 23.

[0062] In the assembled state, the ring ends 54 are arranged at a distance from each other within the retaining groove 23. The grooved ring 53 is elastically deformed in the assembled state and is thereby pressed against the bottom of the retaining groove 23. The pressing force between the grooved ring 53 and the base body 12 within the retaining groove 23 can be so great that, under the forces occurring during the intended use of the tool holder 10, a relative rotation of the grooved ring 53 about the central axis A relative to the base body 12 is prevented.

[0063] In the embodiment illustrated here, the bearing ring 43 is supported axially on the side opposite the grooved ring 53 against the ring support surface 25 of the base body 12. This allows the bearing ring 43 to be mounted axially without play or securely between the ring support surface 25 and the grooved ring 53, without transmitting excessive axial force to the axial bearing arrangement 50 or the clamping rotor 29.

[0064] The described arrangement allows the base body 12 to be designed to be compact and short in the axial direction. A threaded connection for securing the clamping rotor 29 in the receiving space 15 is unnecessary. The mating surfaces formed with the bearing ring 43 enable very precise radial alignment of the clamping rotor 29 relative to the base body 12 and thus relative to the central axis A defined by the base body 12.

[0065] In the illustrated embodiment, the tool holder 10 has a front part 57. The front part 57 is designed to be detachably attached to the base body 12 and, for example, to the pipe section 18, at least in the first assembly step. For this purpose, the front part 57 can, for example, have an internal thread 58 that can form a threaded connection with an external thread 59 of the base body 12 and, in particular, of the pipe section 18. Alternatively to the threaded connection, other positive-locking and / or force-locking connection devices could also be used. In addition to or as an alternative to creating the detachable connection, the front part 57 can be bonded to the base body 12 and, for example, to the pipe section 18 by means of a material bond or adhesive bond. The threaded connection can, in particular, also be bonded.

[0066] When the front part 57 is connected to the base body 12, the tube section 18 projects into the front part 57. The front part 57 does not, for example, have a holding or securing function to support or secure a component (such as a clamping rotor 29 or a bearing ring 43) located in the receiving space 15 of the base body 12 in the axial direction. The front part 57 serves exclusively to generate a clamping force for clamping the tool 11 (as will be explained in more detail below).

[0067] The front part 57 is completely penetrated in the axial direction by a clamping channel 60. The clamping channel 60 is bounded, at least in sections, by an internal clamping surface 61. The internal clamping surface 61 is conical. Its diameter increases from an end of the clamping channel 60 associated with the base body 12 to an opposite front end of the clamping channel 60. The clamping channel 60 thus widens conically towards the front, away from the base body 12. The clamping channel 60 is open towards the receiving space 15.

[0068] The clamping channel 60 and the rotor interior 40 are aligned with each other when the front part 57 and the base body 12 are connected. After the front part 57 has been attached to the base body 12, the clamping channel 60 can be machined by grinding or another high-precision process so that the clamping channel 60 is aligned as closely as possible to the central axis A.

[0069] To clamp the tool 11 into the tool holder 10, the tool holder 10 has a collet 62. The collet 62 is in the Fig. 4 and Fig. Figure 6 shows a schematic representation. The collet 62 has a collet thread 63, which is designed to create a threaded connection with the clamping thread 30 of the clamping rotor 29. The collet thread 63 can be arranged at a cylindrical or tubular end of the collet 62.

[0070] Adjoining the end opposite the collet thread 63, the collet 62 has a conical outer surface 64. The outer surface 64 is designed to interact with the inner clamping surface 61 to deform the collet 62 radially inwards, at least in an axial section. For this purpose, the collet 62 has one, and preferably several, axially extending slots 65. The slots 65 are arranged in the region of the conical outer surface 64 to separate finger-like clamping elements 66 from one another in the circumferential direction around the central axis A. The slots 65 extend from a front end of the collet 62 into the collet 62, but do not penetrate the collet 62 completely in the axial direction. Inside, the collet 62 has an internal chamber 67, which is accessible from the outside on the side opposite the collet thread 63, so that a tool 11 can be inserted.a tool shank of the tool 11 can be inserted into the collet interior 67, and is arranged there within the clamping elements 66 ( . Fig. 4).

[0071] To clamp a tool 11 using any embodiment of the tool holder 10, the following procedure is taken:

[0072] The shank of a tool 11 is inserted into the collet chuck chamber 67. The collet chuck 62 is inserted through the clamping channel 60 into the rotor chamber 40 of the clamping rotor 29, so that the collet chuck thread 63 and the clamping thread 30 are axially aligned and ready for screwing. The clamping rotor 29 can then be rotated relative to the base body 12 by means of the rotary device 35, whereby the collet chuck 62 is drawn further axially into the clamping channel 60 and the rotor chamber 40. The inner clamping surface 61 exerts a radial force on the outer surface 64 of the collet chuck, causing the clamping elements 66 to be forced radially inwards. This movement is made possible by the clearance provided by the slots 65. This causes the part of the tool 11 (for example, the tool shank) arranged in the collet chuck interior 67 to be subjected to a clamping force and clamped firmly in the collet chuck 62.The collet 62 in turn is held in the tool holder 10 by the threaded connection between the collet thread 63 and the clamping thread 30.

[0073] Because the rotary device 35 is self-locking, accidental detachment of the tool 11 from the tool holder 10 is prevented when using the tool 11 (for example, when machining a workpiece). The tool 11 can be driven by the machine spindle of a machine via the tool holder 10, rotating around the central axis A, for example, to machine a workpiece. The tool 11 can be, for example, a milling cutter or a drill bit.

[0074] The removal of a tool 11 can in turn be carried out by actuating the rotary device 35 in order to loosen the threaded connection between the clamping thread 30 and the collet thread 63 and to remove the collet 62 from the base body 12.

[0075] In the Fig. 7 and Fig.Figure 8 illustrates a modified embodiment of a bearing ring 43. In this bearing ring 43, the outer ring surface 44 and the inner ring surface 45 are not arranged as concentrically as possible to each other, but rather offset from each other by an eccentricity E.

[0076] The outer ring surface 44 has a radius R1, while the inner ring surface 45 has a radius R2. On an end face 70 facing away from the second axial bearing surface 46, the bearing ring 43 can have several, and for example two, holes 71, which are arranged diametrically opposite each other at the point of maximum eccentricity E. The holes 71 can serve for inserting a tool and for rotating the bearing ring 43 relative to the base body 12. Instead of the holes 71, other elements could also be present on the end face 70, against which a tool can engage to rotate the bearing ring 43 relative to the base body 12.

[0077] Due to the eccentric arrangement of the outer ring surface 44 relative to the inner ring surface 45, it is possible to align the inner ring surface 45 as coaxially as possible around the central axis A of the base body 12, even if the circumferential inner surface 24 is positioned outside a predetermined tolerance around the central axis A. In contrast to the embodiments described above, an eccentricity between the outer ring surface 44 and the inner ring surface 45 is thus deliberately provided on the bearing ring 43, so that the position of the inner ring surface 45 relative to the central axis A defined by the base body 12 can be adjusted after the bearing ring 43 has been positioned in the receiving space 15. Apart from the eccentricity E of the bearing ring 43, the tool holder 10 can be constructed and used analogously to any of the embodiments described above.

[0078] The invention relates to a tool holder 10 for clamping a tool 11 using a collet 62. The tool holder 10 has a base body 12 comprising a machine connection part 14, which forms an interface to a spindle mount of a machine spindle. A receiving chamber 15 is provided in the base body 12, in which a clamping rotor 29 is arranged. The clamping rotor 29 is supported axially parallel to a central axis A of the base body 12 between a first axial bearing surface 22 of the base body 12 and a second axial bearing surface 46 located on a bearing ring 43. The bearing ring 43 is held in the receiving chamber 15 by means of a groove ring 53 inserted into a retaining groove 23. The bearing ring 43 has an outer ring surface 44 for bearing against the base body 12 and an inner ring surface 45 for bearing against the clamping rotor 29.The bearing ring 43 allows the clamping rotor 29 to be positioned very precisely in the radial direction relative to the base body 12, and thus very precisely around the central axis A of the base body 12 (minimal deviation from the ideal coaxial arrangement). The bearing ring 43 is threadless and also secured to the base body 12 without threads. Reference symbol list: 10 tool holders 11 tools 12 basic shapes 13 Back side of the base body 14 Machine connection part 15 Recording room 16 Front of the base body 17 Access opening 18 pipe section 22 first axial bearing surface 23 locking groove 24 Perimeter inner surface 25 ring support surface 29 Tension rotor 30 clamping threads 31 End piece of the clamping body 32 central part of the clamping body 33 Pipe section 34 Pipe outer surface 35 Rotary device 36 Control element 37 Coupling device 38 worm shaft 39 worm gear 40 Rotor interior 43 Bearing ring 44 Ring outer surface 45 ring inner surface 46 second axial bearing surface 50 axial bearing arrangement 51 rolling bearings 52 Support ring 53 Grooved ring 54 wrestlers 57 Front part 58 internal threads 59 external threads 60 clamping channel 61 Internal clamping surface 62 Collet 63 collet threads 64 Clamping jaw outer surface 65 slots 66 clamping elements 67 Collet chuck interior 70 End face of the bearing ring 71 holes A central axis D1 Diameter of the access opening D2 Outer diameter of the first axial bearing surface D3 Inner diameter of the ring support surface E eccentricity R1 Radius of the outer ring surface R2 radius of the inner ring surface

Claims

[1] Tool holder (10) for clamping a tool (11), wherein the tool holder (10) comprises: - having a base body (12) extending along a central axis (A): ◯ a machine connecting part (14) which is designed to arrange the tool holder (10) in a receptacle of a machine spindle, ◯ a receiving space (15) which has an access opening (17) on a front side (16) facing away from the machine connection part (14), ◯ a first axial bearing surface (22) which is adjacent to the receiving space (15) and at a distance from the access opening (17), ◯ a locking groove (23) arranged between the access opening (17) and the first axial bearing surface (22), and ◯ a circumferential inner surface (24) which is arranged between the locking groove (23) and the first axial bearing surface (22), - a clamping rotor (29) arranged in the receiving space (15) with a clamping thread (30) which is configured to make a threaded connection with a collet thread (63) of a collet (62), and with a pipe section (33) extending around the central axis (A), - a bearing ring (43) arranged on the base body (12), which has an outer ring surface (44) for contact with the inner circumferential surface (24), an inner ring surface (45) for contact with an outer pipe surface (34) of the pipe section (33) and a second axial bearing surface (46) which faces the first axial bearing surface (22), wherein the clamping rotor (29) is supported indirectly or directly on the first axial bearing surface (22) and the second axial bearing surface (46), - a grooved ring (53) which is inserted into the locking groove (23) and against which the bearing ring (43) is supported. [2] Tool holder (10) according to claim 1, wherein the circumferential inner surface (24) and the ring outer surface (44) form a first pair of mating surfaces and the ring inner surface (45) and the tube outer surface (34) form a second pair of mating surfaces. [3] Tool holder (10) according to claim 1 or 2, wherein the bearing ring (43) is designed without threads. [4] Tool holder (10) according to one of the preceding claims, further comprising a rotary device (35) arranged on the base body (12) which is coupled to the clamping rotor (29) to rotate the clamping rotor (29) about the central axis (A) relative to the base body (12). [5] Tool holder (10) according to one of the preceding claims, further comprising an axial bearing arrangement (50) which is configured for axial support of the clamping rotor (29) on the first axial bearing surface (22) and / or the second axial bearing surface (46). [6] Tool holder (10) according to claim 5, wherein the axial bearing arrangement (50) has a rolling bearing (51) arranged between the first axial bearing surface (22) and the clamping rotor (29). [7] Tool holder (10) according to claim 5 or 6, wherein the axial bearing arrangement (50) has a support ring (52) arranged between the clamping rotor (29) and the first axial bearing surface (22). [8] Tool holder (10) according to claim 7, wherein the axial bearing arrangement (50) has a further support ring (52) which is arranged between the clamping rotor (29) and the second axial bearing surface (46). [9] Tool holder (10) according to one of the preceding claims, wherein the base body (12) has an annular support surface (25) adjacent to the receiving space (15), which faces the access opening (17) and on which the bearing ring (43) is supported. [10] Tool holder (10) according to claim 9, wherein an inner diameter of the ring support surface (25) is at least as large as an outer diameter of the first axial bearing surface (22). [11] Tool holder (10) according to one of the preceding claims, further comprising a front part (57) which has a clamping channel (60) bounded by a conical inner clamping surface (61). [12] Tool holder (10) according to claim 11, wherein the front part (57) and the base body (12) are arranged to be detachably connected to each other, in particular by means of a threaded connection. [13] Tool holder (10) according to claim 11 or 12, wherein the clamping channel (60) is arranged adjacent to the access opening (17). [14] Tool holder (10) according to one of claims 11 to 13, wherein, when a threaded connection is produced between the clamping thread (30) and the collet thread (63) of the collet (62), an outer collet surface (64) is pressed against the inner clamping surface (61) of the front part (57).

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