Clamping device with hydraulic clamping

Abstract

Clamping device (1, 10) for clamping a workpiece (50) or a tool (55) and in particular for coupling the workpiece (50) or the tool (55) to a machine spindle, comprising a) at least one clamping bushing (18, 32) rotating around a central axis (M) with at least one clamping surface (11, 37) for the workpiece (50) or tool (55) and b) at least one clamping element (2, 36), c) wherein the clamping sleeve (18, 32) has at least one support surface (15A) on a side facing away from the clamping surface (11, 37), which is formed along a helix or as a threaded section with a predetermined pitch (P SG ) runs around the central axis and is simultaneously inclined at an angle of inclination (α) to a direction (Z) axial to the central axis (M) or to an imaginary cylindrical surface running around the central axis (M), d) wherein the clamping body (2, 36) has at least one support surface (14A) on one side facing the clamping sleeve (18, 32), which is formed along a helix or as a threaded section with a predetermined pitch (P SG ) runs around the central axis (M) and is simultaneously inclined at an angle (α) to a direction (Z) axial to the central axis (M), e) wherein the clamping body (2, 36) and / or the clamping sleeve (18, 32) comprises one or more hydraulic chambers (3) formed inside the clamping body (2, 36) or the clamping sleeve (18, 32) and filled with a hydraulic medium, f) further comprising at least one displacement element (12, 13) to bring the opposing support surfaces (14A, 15A) of the clamping body (2, 36) and the clamping sleeve (18, 32) into contact with each other by an axial displacement movement along an axial displacement path (ΔZ) in the axial direction (Z) and / or to move them sliding against each other, whereby the diameter of the clamping surface (11, 37) can be changed or is changed in a direction (R) radial to the central axis (A) or whereby, with the clamping surface (11, 37) already in contact with the workpiece (50) or tool (55), a radial mechanical clamping force (F) is exerted R ) between clamping sleeve (18, 32) on the one hand and workpiece (50) or tool (55) on the other hand can be generated or is generated, g) further comprising at least one pressure generator (16) to pressurize the hydraulic medium in at least one of the hydraulic chambers (3) at a hydraulic pressure (p H) to act upon, which, with overlapping support surfaces (14A, 15A) of clamping body (2, 36) and clamping sleeve (18, 32), exerts a radial hydraulic pressing force (F) H ) on the overlapping support surfaces (14A, 15A) of clamping body (2, 36) and clamping sleeve (18, 32) is generated by the radial hydraulic pressing force (F H ) with the clamping surface (11, 37) already in contact with the workpiece (50) or tool (55), a radial hydraulic clamping force (F) H ) between clamping sleeve (18, 32) on the one hand and workpiece (50) or tool (55) on the other hand can be generated or is generated.

Description

[0001] The invention relates to a clamping device, such as a clamping mandrel or a chuck, for clamping workpieces or tools and a method for clamping a workpiece or tool with such a clamping device, in particular for a machine spindle.

[0002] Clamping devices, clamping tools, or clamping systems for clamping workpieces or tools and coupling them to machine spindles for rotation and, if necessary, infeed during material processing, especially machining, are known in a wide variety of designs. The machine spindle is a machine component that can be rotated or turned by a rotary drive and is usually adjustable in speed and often also movable in space for infeed movements; its specific shape can vary considerably. The clamping device is usually coupled to the machine spindle but can also be an integral part of it.

[0003] From the EMUGE clamping technology catalog 135, "Top-Class Clamping Tools," published in September 2005 by the EMUGE FRAN-KEN group of companies, various clamping systems are presented in an overview on pages 10 to 17 and then in detail on pages 18 to 190 in specific solutions, particularly for the automotive industry. During clamping, the play between a clamping sleeve or bushing and the workpiece or tool is eliminated, and a radial clamping force is generated.

[0004] In the system designated SP, shown on page 12 of the catalog, a longitudinally meandering clamping sleeve expands radially under axial force to clamp the workpiece or tool. In the clamping system designated SZ, also shown on page 12 of the catalog, a slotted collet is moved axially relative to the base body by axial force and expanded radially via opposing conical surfaces. A special diaphragm clamping system, SM, is described on page 14.

[0005] Another clamping system, designated SG, is described on page 13 of the catalog and features a slotted clamping sleeve with a special saw thread, which is screwed onto a corresponding saw thread on the base body. The wedge-shaped contact surfaces of the two saw threads, arranged at a predetermined flank angle, are axially movable relative to each other when an axial force is applied. During such axial movement, the clamping sleeve expands radially due to the flank angle, clamping the workpiece. The applied axial force is distributed across the saw thread surfaces, which are inclined relative to each other at the flank angle, into an axial force component and an outward-acting radial force component. The axial force component increases the transmissible torque and the clamping stiffness.

[0006] In addition to the mechanical clamping systems SP, SZ, SG, and SM, page 13 of the catalog also describes a hydraulic clamping system SH, which is particularly suitable for clamping long, thin-walled workpieces and multiple identical workpieces. These are closed systems filled with hydraulic oil, which is pressurized by a piston. The resulting pressure expands the thin-walled expansion zone of an expansion sleeve radially, clamping the workpiece(s).

[0007] From DE 10 2013 103 168 B3, a tool holder for a tool rotatable about a rotary axis, in particular in the form of a drill, a milling cutter, a reamer, or a cutter head, is known. To enable clamping of the tool in a manner that particularly favorably influences its vibration behavior without compromising machining precision, the tool holder has a base body for coupling the tool holder to the spindle of a machine tool and a clamping section, designed as a sleeve and made of a single material or at least integrally connected to it, for thermally or hydraulically clamping a tool shank or cutter head. The radially pressed clamping surfaces are cylindrical and may also have open grooves for adjusting the clamping force.The known toolholder further comprises at least one integrally formed section with one or more cavities located entirely within the section. These cavities form an enclave within the formed section, meaning they are completely sealed off from their surroundings, particularly to the outside. These cavities exhibit excellent damping properties and allow for constructive balancing. The cavities have a defined geometric shape and extend radially and along the axis of rotation of the toolholder by more than 1 / 10 of a millimeter, preferably more than one millimeter. For vibration damping, the cavities each form, in particular, an annular channel that runs concentrically to the axis of rotation entirely within the section, or an annular channel that is completely closed in the circumferential direction.In another embodiment, the tool holder has several cavities extending parallel to the axis of rotation or along a helical path around the axis of rotation, thus preventing excessive heat transfer during shrink-fitting. The cavities have a round, rectangular, or hexagonal cross-section in a plane perpendicular to the axis of rotation.

[0008] In a further embodiment, according to DE 10 2013 103 168 B3, a tool holder for clamping a tool shank is proposed, comprising a base body for coupling the tool holder to the spindle of a machine tool and an associated sleeve section for securing or shrinking in a tool shank, and at least one integrally formed section in which an external connecting channel is formed. This channel extends from the outer circumference of the tool holder into the interior of the section and widens to form at least one cavity that lies entirely within the interior of the section, so that an adjacent section, such as a cover of a bushing or a base body welded to the sleeve section, does not participate in the formation of the cavity. A relatively large, fluid-filled cavity is formed, which can be pressurized hydraulically from the outside via a small opening using a pressure transmitter.Preferably, several cavities are arranged in a radial direction, progressing from the inside out, and simultaneously several cavities are arranged in a row along the axis of rotation to generate a distributed pressure effect. A network of fluidically communicating cavities can be pressurized as needed. The pressure transmitter can, for example, be a screw actuated via an internal hexagon socket, which is screwed into a connecting section with an internal thread leading to the external connection channel. The screw-in depth determines the pressure that influences the clamping force available for the tool. The cavities are dimensioned and arranged such that they generate radially inward-acting pressure forces when pressurized accordingly. These pressure forces reinforce or replace the clamping force applied by the shrink-fit process.

[0009] According to DE 10 2013 103 168 B3, this tool holder can be manufactured in particular by having a first section of the tool holder made of forged or cast metal and a second section of the tool holder made of a layered metal material, wherein the first section is preferably the base body and the second section is preferably the clamping section. The clamping section can also be constructed from individual metal layers that are produced successively as a layered metal material. In this process, individual metal layers, zones, or points are successively melted, welded, or sintered together, usually with a laser.

[0010] EP 2 347 842 A2 describes an expansion clamping device, in particular an expansion chuck or expansion mandrel, comprising a base body and an expansion sleeve which is inserted into or surrounds the base body, forming a closed pressure chamber. The pressure chamber can be pressurized with a hydraulic fluid, causing elastic deformation of the expansion sleeve, to achieve a clamping effect. The expansion sleeve is brazed to the base body at least at one axial end region.

[0011] EP 2 103 369 B1 discloses an expansion chuck with a chuck body at the axial end of which a thin-walled expansion sleeve is formed. The expansion sleeve is connected to a hydraulic channel which opens into a pressure chamber at one end and is closed at the other end by an actuating screw, pressing on a piston inserted into the central hydraulic channel. A collet or clamping sleeve is inserted into a conical receptacle of the expansion sleeve. The collet has a conical shape on its outer circumference corresponding to the receptacle and is elastically deformable in the radial direction. By screwing a cap nut onto the chuck body, the collet is pressed axially onto the receptacle, whereby the conical outer surface of the collet and the conical inner surface of the receptacle engage and interact in such a way that the axial movement of the collet is converted into a radial deformation of the sleeve.By appropriately positioning the clamping sleeve axially, the diameter of the through-bore of the clamping sleeve can be adjusted using the union nut, so that tool shanks of different diameters can be clamped.

[0012] WO 2015 / 166068 A1 discloses a tool with a base body that has a receptacle for another tool and / or a shank for attachment to another tool or to a machine tool, and which is provided with a channel through which coolant can flow. The tool is manufactured using a laser sintering process. This process, also known as selective laser sintering, allows a coolant channel to be incorporated into the base body of a tool. In a laser sintering process, metallic substances in powder form are used, which are subjected to a sintering process using a laser. This results in a metallic body. If steel powder is used as the starting material, a steel body is produced.

[0013] DE 21 48 654 A discloses a clamping device comprising an inner member with a plurality of circumferentially distributed and axially extending rows of teeth on its outer surface, and a member surrounding the inner member arranged concentrically to it, which has a plurality of circumferentially distributed and axially extending rows of teeth on its inner surface, wherein these teeth can engage with the teeth of the inner member, wherein furthermore one of the inner or outer members has a series of circumferentially distributed and axially extending slots in it, which divide it into a plurality of segments that can bend radially when the engaging teeth on the inner and outer members are moved axially against each other.The clamping device is further characterized by the following features: A pressure-medium actuation system is provided, which causes a mutual axial movement of the inner and outer links while the teeth are engaged, in order to bring one of the aforementioned inner and outer links radially into contact with the object to be clamped. The pressure-medium actuation system has sealed chambers that hold a certain quantity of a substantially incompressible fluid, the fluid substantially filling the chambers. Furthermore, a pressure transmitter is provided, which, in conjunction with the chambers, selectively pressurizes the fluid in the chambers.And that a pressure sensor is provided which, in conjunction with the chambers and in cooperation with one of the inner or outer links, transmits the force exerted by the fluid to the said link in order to displace it axially relative to the other link.

[0014] The object of the invention is to provide a new clamping device and a new clamping method.

[0015] This task is solved in particular by the features of the independent claims. Embodiments and variants arise especially from the dependent claims, and furthermore from the following description, in particular the embodiments and configurations described therein.

[0016] The features and combinations of features described herein according to the underlying invention are not limited by the combination(s) of features selected in the claims and the selected cross-references. Any feature of a claim category may also be claimed in another claim category. Furthermore, any feature in the claims may be claimed, even independently of the respective claim-specific cross-reference, for example, in any combination with one or more other features of the claims or the following description.Furthermore, each feature disclosed in the following description and / or the attached drawings, and / or described or disclosed in connection with the drawings, may be claimed on its own, independently or separately from the context in which it appears, alone or in any combination with one or more other features described or disclosed in the claims, the description, and / or the drawings, in particular to the extent that the respective feature contributes at least to solving the underlying problem. In particular, each of the embodiments or exemplary embodiments described below and their features may also be claimed separately and / or in any combination.

[0017] In one embodiment according to the invention, a clamping device for clamping (or: for clamping or mounting) a (rotating or non-rotating) workpiece or a tool, and in particular also for coupling the workpiece or the tool to a (rotating or non-rotating) machine spindle, in particular of a machine tool, is proposed, which has the features of claim 1 or the following features: a) at least one clamping sleeve (or clamping sleeve) rotating around a central axis with at least one clamping surface for the workpiece or tool (or: with at least one clamping surface for interaction, in particular frictional contact, with at least one counter clamping surface on the workpiece or tool), and b) at least one clamping body (or: clamping element), c) wherein the clamping sleeve has at least one support surface on a side facing away from its at least one clamping surface, which runs along a helix (or: as or like a threaded section) with a predetermined pitch around the central axis and is at the same time inclined at an angle to a direction axial to the central axis, d) wherein the clamping body has at least one support surface on a side facing the clamping sleeve, which runs along a helix (or: as or like a threaded section) with a predetermined pitch around the central axis and is at the same time inclined at an angle to a direction axial to the central axis, e) wherein or such that the opposing support surfaces of the clamping body and the clamping sleeve can be brought into contact with each other by means of at least one displacement element by means of an axial displacement movement along an axial displacement path in the axial direction and / or can be moved sliding against each other, whereby the diameter of the clamping surface can be changed or is changed in a direction radial to the central axis or whereby, when the clamping surface of the clamping sleeve is already in contact with the workpiece or tool, a radial clamping force can be generated or is generated at the clamping surface between the clamping sleeve on the one hand and the workpiece or tool on the other hand, f) wherein the clamping body and / or the clamping sleeve further comprises one or more hydraulic chambers formed inside the clamping body or the clamping sleeve and filled with a hydraulic medium, g) wherein the hydraulic medium in at least one of the hydraulic chambers can be or is subjected to a hydraulic pressure by means of at least one pressure generator, which hydraulic pressure generates a hydraulic radial pressing force on the opposing support surfaces of the clamping body and clamping sleeve when the clamping surface of the clamping body and clamping sleeve is in contact with each other, wherein, in turn, a radial hydraulic clamping force can be or is generated between the clamping sleeve on the one hand and the workpiece or tool on the other, by means of this hydraulic radial pressing force when the clamping surface of the clamping sleeve is already in contact with the workpiece or tool.

[0018] In other alternative definitions to the definition "inclined in a direction axial to the central axis", the support surfaces can also be inclined radially inwards or outwards to an imaginary or geometric cylindrical surface running around the central axis as a cylinder axis, or in every section along a section plane containing the central axis (longitudinal section) they can be inclined in a direction parallel to the central axis.

[0019] The support surfaces are preferably flat and inclined at a constant angle of inclination, in particular wedge-shaped or sawtooth-shaped and preferably on a helical conical surface, but can also have a varying inclination at a varying angle of inclination, in particular with a certain slight curvature.

[0020] In one embodiment, a mechanical clamping force is generated, and a hydraulic clamping force is generated in addition to the mechanical clamping force. Generally, the hydraulic clamping force is in the same direction as the mechanical clamping force.

[0021] The clamping device can also clamp purely mechanically or purely hydraulically.

[0022] A combination of both clamping principles is preferred. Hydraulic clamping can advantageously compensate for tolerances on a tool shank or workpiece that cannot be compensated for with a mechanical clamping principle. Mechanical clamping using the sliding element can also generate an axial clamping force, thereby achieving greater clamping stiffness.

[0023] In a preferred embodiment, the hydraulic clamping force is adjustable or set to at least 2 times, at least 5 times, or at least 20 times the mechanical clamping force.

[0024] In one embodiment, corresponding support surfaces of the clamping body and clamping sleeve can be brought into an engagement position, or screwed in, by a twisting movement adapted to their pitch, in which the support surfaces are at least partially opposite each other and / or in contact.

[0025] From this engagement position, the axial displacement movement can now be carried out to generate the radial mechanical clamping force, and subsequently the chamber(s) can be pressurized with hydraulic pressure by means of the pressure generator to generate the hydraulic clamping force.

[0026] In a preferred embodiment, intermediate webs (or separating webs) are arranged between the hydraulic chambers. The axial dimension or thickness of the intermediate webs is, in particular, smaller, preferably at least by a factor of 4, than an axial dimension or length of the chambers. In particular, the intermediate webs are arranged below the support surface(s) at an axial distance corresponding to a multiple, in particular double, slope of the support surface(s).

[0027] By incorporating one or more webs, the wall, which transmits the force generated by expansion to the clamping sleeve, can be divided into different sections, each transmitting varying force levels. The wall can thus be designed so that a lower force is transmitted in certain areas where expansion is restricted, and a higher force in areas where expansion is unrestricted. Furthermore, the webs allow the hydraulic chambers to be more robust, particularly against alternating loads during operation, ensuring a consistent pressure build-up. If necessary, the web-equipped chambers can withstand higher hydraulic pressures than those known in the prior art. This allows for a higher clamping pressure to be provided for the workpiece in specific sections.

[0028] In an advantageous embodiment, a membrane-like wall (or expansion membrane) of the clamping body or clamping sleeve is formed between the chamber(s) and the support surface(s), which is deformable or expandable in the radial direction by the hydraulic pressure on the support surface(s).

[0029] The membrane-like wall is preferably supported on the intermediate struts.

[0030] The wall can be designed separately from the webs and only rest on the webs, so that the wall is supported on the webs at least in the radial direction, preferably in such a way that the wall is movable relative to the webs.

[0031] The wall can also be connected to the intermediate webs, in particular welded, soldered or glued to the webs.

[0032] If the webs are connected to the wall in one or more connection areas, expansion in these connection areas can be reduced or completely prevented. This makes it particularly advantageous to create specific spatially or area-limited expansion zones or zones of differing pressure on the outside of the wall.

[0033] In one embodiment, at least one of the intermediate webs is formed in a ring-like shape around the entire circumference, in particular extending perpendicular to the central axis.

[0034] In a further embodiment, at least one of the intermediate webs is twisted or helical, in particular extending around the central axis, in particular at a twist angle between 40° and 80°, in particular between 50° and 70°.

[0035] Several such twisted intermediate webs can also be provided, arranged in particular at the same twist angle, for example like a multi-start thread, or at different twist angles, especially opposite to each other, for example in a crossed configuration. Here, for example, no hydraulic medium can be provided between one pair of webs, and hydraulic medium can be provided between the next pair of webs following the first pair in the axial direction. In this way, expansion zones can be created that are separated from each other by non-expanding zones.

[0036] In at least one embodiment, at least one of the intermediate webs extends only over part of the circumference.

[0037] The intermediate web(s) are arranged or formed in particular on a cylindrical surface, especially a cylindrical surface, of the clamping body or clamping sleeve.

[0038] In one embodiment, at least two or more intermediate webs are arranged intersecting or forming intersections, or in a diamond or honeycomb pattern. This is particularly stable.

[0039] In one embodiment, at least one of the chambers is enclosed in a ring-like fashion around its entire circumference, in particular perpendicular to the central axis.

[0040] In another embodiment, at least one of the chambers is designed to be helical or screw-shaped, in particular extending around the central axis.

[0041] In another embodiment, at least one of the chambers extends only over part of the circumference and / or is cushion-shaped and / or diamond- or honeycomb-shaped.

[0042] Regarding the geometric dimensions of the hydraulic chambers, at least one or a combination of the following features can be selected: a) the chambers have a radial dimension or height, in particular of the same size, which is in particular larger, preferably by at least a factor of 2.5, than the radial thickness of the membrane-like wall, b) at least the axially inner chambers have the same axial dimensions, c) The axially outer chambers have a smaller axial dimension than the axial dimension of the axially inner chambers, d) the axial dimensions of the chambers are larger than the slope of the support surface(s), but smaller than twice the slope.

[0043] In one embodiment of the hydraulic system, at least one or more of the chambers are fluidically connected to the at least one pressure generator via at least one hydraulic channel. Furthermore, preferably at least two of the chambers are designed to communicate fluidly with each other, in particular through intermediate channels or openings, especially in or between the intermediate webs.

[0044] The number and size of the chambers allow you to adjust how many expansion zones are provided on the support surfaces and thus on the clamping surface. Smaller expansion zones can be advantageous, for example, when clamping workpieces or tools with high surface roughness, as the clamping force is then applied with a correspondingly finer force distribution, thus compensating for surface roughness and achieving uniform clamping. Relatively large expansion zones can be advantageous when a high clamping force is required. Fluidically communicating chambers facilitate and improve pressure build-up within the chambers and allow for pressure equalization between the individual chambers, which stabilizes the clamping force.Alternatively or additionally, it is possible to fluidically separate certain or all chambers from each other, so that not all, but only a certain number of the chambers are pressurized.

[0045] In one embodiment, at least one cross-section perpendicular to the axial direction and / or a longitudinal section parallel to or in this axial direction of one or more chambers is larger than that of the web(s).

[0046] A method for clamping a workpiece or tool with a clamping device according to one of the embodiments of the invention comprises in particular the following method steps: a) Moving the corresponding support surfaces of the clamping body and clamping sleeve into each other by means of a rotational movement adapted to their pitch into an engagement position in which the support surfaces are at least partially opposite each other and / or in contact, b) Generating an axial displacement movement from this engagement position to generate the radial mechanical clamping force, c) Subsequently, applying hydraulic pressure to the chamber(s) using the pressure generator to generate the hydraulic clamping force.

[0047] In one embodiment, fluidically tight chambers are created by integrally forming the clamping body with the webs, and the force from these chambers can be advantageously transmitted to the clamping sleeve. Furthermore, integrally forming the clamping body with the webs enables a particularly stable and robust structure for the clamping body.

[0048] In embodiments, individual components of the clamping device, preferably the clamping body, are manufactured entirely or at least in part using additive manufacturing processes, primarily in a metallic material such as a metal or a metal alloy, i.e. in a primary forming process or by primary forming.

[0049] In particular, one of the manufacturing processes or a combination of manufacturing processes known from the article C. Körner - Additive manufacturing of metallic components by selective electron beam melting - a review, International Materials Reviews, 61:5, 2016, pages 361-377, or from the article Lawrence E. Murr Fabrication of Metal and Alloy Components by Additive Manufacturing: Examples of 3D Materials Science, Journal of Materials Research and Technology, Elsevier, 2012, pages 42-54, or known 3D printing processes, in particular a selective laser sintering process or a selective laser melting process or a laser cladding process, can be used.

[0050] In one embodiment, during the manufacturing of the webs, as well as other components of the clamping body that can be produced using the primary forming process, metal powder is deposited in the primary forming process, for example, in a laser sintering process. This powder is then solidified with precise positioning by laser radiation. For example, in laser cladding, metal powder with grain sizes of approximately 1 / 100 mm can be used. With such a powder, powder layers with a minimum thickness of 1 / 10 mm can be achieved in laser cladding.

[0051] Besides the solidified metal powder, loose, free-flowing, or unsolidified metal powder often remains on and in the component and should be removed, especially from the chambers. For this purpose, it is advantageous to provide openings or gaps between and / or in the webs through which the metal powder can trickle out of the chambers or through which it can be removed, in particular by suction or shaking.In a non-concentric configuration, i.e., a twisted, helical, or spiral configuration, it can be advantageous if the webs themselves are continuous, meaning free of openings, but terminate at a distance from an axially rearward wall (i.e., at one of the machine-side connecting surfaces), or, in the case of a chuck, from the machine-side side (end face), and / or from an axially forward wall (i.e., at one of the machine-side connecting surfaces opposite the machine-side connecting surface). This allows metal powder to escape along the twisted webs and through the openings between the webs and the axially forward and / or axially rearward walls after the hollow chambers, which are essentially fluidically sealed, have been machined.The term "axially front" or "front axial end of the clamping device" refers in particular to the machine-side end of the clamping device, for example encompassing the machine-side clamping surface, whereas "axially rear" or "rear axial end of the clamping device" refers to the end of the clamping device that forms the clamping side, or the end from which or on which the tool or workpiece can be clamped.

[0052] In one embodiment, when producing the clamping element, a blank, preferably substantially conical or cylindrical, which is produced in particular by forging and / or machining, can be provided, which has a radially outer surface or radially inner surface, and then the web(s) on the surface are produced by the primary forming process.

[0053] A particularly simple manufacturing method is achieved if, in a first step, a blank is provided, which is produced in a first process step by forging and / or machining. This blank can be provided with a surface that can form the base or basic structure on which further structures are built up by primary forming or other processes.

[0054] Advantageously, a wall is produced on the clamping body, in particular by a primary forming process, preferably in such a way that the web(s) are materially bonded and / or, in particular, integrally bonded to the wall, in particular in such a way that the web(s) form chamber walls of the chamber(s) with the wall.

[0055] Such a wall can be, in particular, the aforementioned membrane-like wall or expansion membrane. If the wall is produced in a material-bonded or one-piece manner with the rib(s) by, in particular, the same primary forming process or in the same primary forming step, a high strength of the connection between the rib and the wall is ensured, and thin-walled walls can also be produced.

[0056] If the chambers are produced entirely within a single layer of material in a primary forming process, then various cross-sections of the chambers or webs can be manufactured with great flexibility. In other words, hollow chambers of different shapes can be produced with great flexibility.

[0057] The bridges can also be produced by material removal such as die-sinking EDM, milling or turning.

[0058] The chamber(s) has(s) a rectangular cross-section in axial section. A rectangular cross-section of the chambers allows for advantageous pressure distribution, particularly when the long side of the rectangular cross-section is oriented essentially parallel to the wall of the clamping body.

[0059] A cylindrical clamping element in conjunction with a hollow cylindrical clamping sleeve offers the advantage, compared to a conical design of the clamping element and / or clamping sleeve, that the usable dimensions of the inner or outer diameter of the clamping sleeve are not predetermined by the conical shape of the clamping element, but rather that the inner or outer diameter can be flexibly adapted to the clamping task. Furthermore, compared to the conical shape, it is possible for the hydraulic force-generating elements to provide the clamping force exclusively, without the need for mechanical force-generating elements to provide a primary clamping force. Alternatively, the clamping element and / or the clamping sleeve can be conical or tapered.

[0060] Problems associated with purely mechanical clamping, such as in sawtooth threads, are avoided according to the invention; in particular, stick-slip (i.e., friction in the thread and static friction) as well as the breakaway torque are reduced, and only a small mechanical clamping force is necessary, while the essential part of the clamping force is supplied by the hydraulics.

[0061] The invention will be further explained below with reference to exemplary embodiments. Reference is also made to the drawings, in which the following are schematically depicted: Fig. 1 a clamping device according to the state of the art in a longitudinal section; Fig. 2. Schematically, the principle of mechanical tension in a sectional view; Fig. 3 a clamping device according to a first embodiment of the invention in a partially cut side view; Fig. 4 an enlarged section of the clamping device according to Fig. 3; Fig. 5 a clamping device according to a second embodiment of the invention in a partially cut side view; Fig. 6 a clamping device according to a third embodiment of the invention in a partially cut side view; Fig. 7 a clamping device according to a fourth embodiment of the invention in a partially cut side view; Fig. 8 a clamping device according to a fifth embodiment of the invention in a partially cut side view; Fig. 9 a slotted clamping sleeve in a first embodiment in a perspective view; Fig. 10 a slotted clamping sleeve in a second embodiment in a perspective view; Fig. 11 a developed partial wall of a slotted clamping sleeve in a top view and Fig. 12 a clamping device with a slotted clamping sleeve in a cross-section.

[0062] Corresponding parts and sizes are in the Fig. Numbers 1 to 12 are labelled with the same reference symbols.

[0063] Fig. Figure 1 shows a longitudinal section of a clamping device 1 as known from the prior art. The clamping device 1 is designed for clamping (or: force-fit holding) a workpiece 50 indicated by dotted lines, in particular for the purpose of coupling the workpiece 50 to a machine spindle (not shown), or a rotating or non-rotating part of a machining or machine tool, for or during the machining of the workpiece 50.

[0064] The clamping device 1 comprises, within a clamping area 40 in which the clamping forces for clamping the workpiece 50 are provided or generated, a clamping sleeve 18 with a clamping surface 11 radially directed outwards in the R-direction or arranged on an outer surface, cylindrical surface, or outer wall, which bears against a counter-clamping surface 51 of the workpiece 50 for force-fit connection or clamping, and a clamping element 2 for clamping the clamping sleeve 18 by exerting a clamping force on the clamping surface 11 and the counter-clamping surface 51. The sleeve-shaped clamping sleeve 18 is arranged around or surrounding the clamping element 2 with respect to a common central axis M of the clamping device 1 and coaxially with the clamping element 2. Generally, the clamping sleeve 18 is slotted or provided with expansion slots to facilitate expansion.

[0065] Furthermore, the clamping device 1 comprises a shaft part 17 for connecting or coupling to a machine spindle (not shown) in a manner known per se.

[0066] The clamping force is generated by means of at least one support element 14 on an outer surface or lateral surface or outer wall of the clamping body 7 and at least one corresponding or cooperating support element 15 on an inner surface or radially inwardly directed inner wall of the clamping sleeve 18.

[0067] The support elements 14 and 15 are inclined in a wedge or sawtooth shape to the central axis M of the clamping device 1 or of the clamping body 7 and the clamping sleeve 8.

[0068] A mechanical clamping element 12 can be axially or linearly displaced in a clamping movement direction ES parallel to the central axis M in the Z-direction, for example via a threaded pin 13, so that, through surface contact or after a stop of an end face shear surface 19 with an end face of the clamping sleeve 18, it also displaces the clamping sleeve 18 linearly in the clamping movement direction ES. The clamping element 12 and the threaded pin 13 together form an example of a displacement element.

[0069] The workpiece 50, arranged around the clamping sleeve 18, is held axially in position by a stop on a ring body 5. If the clamping sleeve 18 is now moved linearly in the clamping direction ES, the support element(s) 15 of the clamping sleeve 18 slides on the support element(s) 14 of the clamping body 2. This causes the clamping sleeve 18 to expand to a degree at which its clamping surface 11 abuts the counter clamping surface 51 of the workpiece 50, and a defined clamping force is then generated on the clamping surfaces 11 and 51 via a radial pressing force on the support elements 14 and 15.

[0070] Alternatively, the clamping body 2 can also be moved axially relative to the clamping sleeve 18 by means of the clamping element 12.

[0071] The function of the support elements 14 and 15 is explained below using the following examples: Fig. 2 explained further.

[0072] Fig. Figure 2 shows in a longitudinal section in the axial direction the principle of tension or support, in particular in the manner of a sawtooth thread or with a design according to Fig. 1, which principle is also transferable or applicable to all embodiments according to the invention. In the example of the Fig. 2 A workpiece 50 is clamped by radially clamping it from the inside using a clamping sleeve 18 with the radial clamping force F. R The clamping force, which acts radially outwards in the direction of the radial component or coordinate R, is applied analogously to a clamping mandrel. The reverse clamping from the outside inwards by a clamping sleeve that encloses the workpiece or tool from the outside is of course also possible, especially as a chuck.

[0073] The clamping sleeve 18 is operated by means of an insertion force F ES, which acts in the Z-direction or axially to the central axis M, is moved axially and thereby simultaneously deformed or tensioned radially outwards. For this purpose, in longitudinal section, one or more wedge-shaped support surfaces 15A of one or more support elements 15 of the clamping sleeve 18, which are directed at an angle of inclination α to the axial direction or parallel to the central axis M, are supported on one or more support surfaces 14A of one or more support elements 14 of the clamping body 2, which are inclined at the angle of inclination α, and slide along this or these at the angle of inclination α.In a rest or released state, the radially or approximately radially extending end surface(s) 15B of the support element(s) 15 can abut the end surface(s) 14B of the adjacent support element(s) 14, and the support surfaces 14A and 15A can also be slightly spaced apart, i.e., not lying on top of each other or arranged with play relative to each other. In the illustrated state, however, the end surfaces 15B are separated from the corresponding end surfaces 14B by the action of the clamping force F. ESThe support element(s) 15 are displaced relative to each other by a displacement ΔZ in the Z-direction and, due to the inclination by the angle of inclination α, are moved or forced radially outwards on the support element(s) 14 by the radial path (or: deflection) ΔR, where the radial path ΔR is related to the axial path ΔZ depending on the angle of inclination α according to ΔR = ΔZ tan α. This radial movement or deflection or extension outwards by the radial path ΔR causes the entire clamping sleeve 18 to be tensioned, deflected, or extended outwards by ΔR and thereby exerts the radial pressing force F. RThe force is transmitted via the outwardly facing support surface(s) 14A of the clamping body 2 to the inwardly facing support surface(s) 15A of the clamping sleeve 18, which ultimately acts outwards as a clamping force on the workpiece 50 at the opposing clamping surfaces 11 and 51. This clamping force arises physically as a result of the deformation and elastic restoring forces between the clamping sleeve 18 and the workpiece 50, and according to the law of action = reaction. Simultaneously, an axial force component F is generated. A exerted, which increases the transmissible torque and stiffness.

[0074] In order to enable the clamping sleeve 18 to be easily mounted on the clamping body 2 without deformation or a two- or multi-part construction, and to allow the support elements 15 to be positioned over the support elements 14 in the Z-direction, in a preferred embodiment the support elements 15 and 14 with their respective support surfaces 15A and 14A are each designed or arranged in the form of a thread or along a helix or screw line, the pitch of which P SG the spacing of the support elements 14 or 15 in the longitudinal section of the Fig. 2 corresponds. A helical arrangement of several support elements 14 or 15 in succession is possible. Preferably, however, continuous support elements 15 and 14 or support surfaces 15A and 14A are provided, or support elements 15 and 14 uninterrupted along the thread or helix. Thus, a continuous helical arrangement with pitch P is preferred. SGformed and inclined support surface 15A of a corresponding continuous support element 15 on the clamping sleeve 18 at the angle of inclination α and a continuous helical with the pitch P SG A support surface 14A of a corresponding continuous support element 14 is formed on the clamping body 2 and inclined at an angle α. This allows the support elements 14 and 15, the clamping sleeve 18, and the clamping body 2 to be screwed or screwed into one another by a screwing or turning motion, similar to an internal and external thread. After screwing in, the two support threads or surfaces 14A and 15A initially rest loosely against each other without a significant pressing force. Now, the insertion force F is applied. ESexerted, which axially displaces the two support surfaces 14A and 15A in the Z-direction in an axial displacement movement against each other, thereby initially bringing them into contact with each other and then, due to the inclination of the support surfaces 14A and 15A, exerts a radial pressing force F R This results in the support surfaces 14A and 15A being pressed against each other, and consequently in a radial clamping force being exerted outwards on the workpiece 50. Due to the wedge-shaped or sawtooth-like form of the support surface(s) 14A and 15A, such a thread is also called a sawtooth thread. However, different shapes are also possible, in particular curved support elements 14 and 15 or support surfaces 14A and 15A with multiple flat surfaces.

[0075] In the based on Fig. 1 and Fig. In the embodiments shown and described in Figure 2, the workpiece 50 is clamped from the inside, i.e., the clamping device protrudes through the workpiece 50. Such a clamping device is also called a mandrel clamping device. Alternatively, a workpiece or tool can also be clamped from the outside, i.e., the clamping device surrounds the workpiece or tool. Such a clamping device is also called a chuck clamping device. Here, the clamping surfaces and support elements are compared to a mandrel clamping device according to Figure 2. Fig. 1 and Fig. 2 in their order in radial direction reversed, i.e. the order from outside to inside now becomes the order from inside to outside.

[0076] According to the invention, a clamping device, such as those used, for example, in Fig. 1 and Fig. The clamping device described in section 2, or the EMUGE embodiment SG described above, is improved and further developed by additionally, or preferably primarily, providing hydraulic clamping by means of hydraulically actuated chambers. For this purpose, hydraulic chambers filled with a hydraulic medium such as hydraulic oil are provided in the clamping body 2 or in the clamping sleeve 18 near the support surfaces 14A or 15A. The hydraulic chambers are filled with hydraulic medium and pressurized with hydraulic pressure, which generates an additional hydraulic pressing force on the support surfaces and thereby an additional hydraulic clamping force on the clamping surface and counter-clamping surface.

[0077] Fig. Figure 3 shows an embodiment of a clamping device 10 with such hydraulic chambers 3, here in the clamping body 2, in a partially cut-away side view. Fig. Figure 4 shows an enlarged section of the partially cut part of the Fig. 3, in which chambers 3 are visible.

[0078] The clamping device 10 has a clamping element 2 in a clamping range 40, which is as described in Fig. 1 and Fig. 2 is arranged within a clamping sleeve 18, preferably around a common central axis M. A workpiece 50 is arranged on a (here outer) clamping surface 11 of the clamping sleeve 18 with its counter clamping surface 51. On the inner side facing away from the clamping surface 11, the clamping sleeve 18 again has the support element(s) 14.

[0079] Unlike Fig. 1 are now in the embodiment according to the invention according to Fig. 3 and Fig. 4 inside the clamping body 2 hydraulic chambers 3 are provided, which are filled with hydraulic fluid or a liquid hydraulic medium such as hydraulic oil, which is under a hydraulic pressure p Hstands.

[0080] The chambers 3 are each surrounded by a pressure opposite to the hydraulic pressure p. H and surrounded by the hydraulic medium pressure-tight wall 6.

[0081] In the axial or Z direction parallel to the central axis A, intermediate webs or separating webs 7 are arranged between the chambers, which have an axial dimension or thickness d.

[0082] In the embodiment according to Fig. 4. Do all chambers 3 have the same radial dimension or height b?

[0083] In the radial direction R outwards, the chambers 3 are arranged at a relatively small radial distance e from the support element(s) 14, i.e., their radially innermost point, so that a comparatively thin, membrane-like wall 8 is formed with the intervening region of the clamping body 2, on which the support element(s) 14 are arranged. The dimension e is chosen to be approximately equal to the dimension b. The pressure increase in the chambers 3 pushes the thin wall 8 outwards in the radial direction R. The intermediate webs 7 support the wall 8.

[0084] The inner three chambers 3 preferably have the same axial dimension or length a1 and the two outer chambers 3 preferably have a smaller axial dimension a2 < a1.

[0085] The axial thickness d of the intermediate webs 7 is smaller, in particular by a factor of at least 4, preferably at least 5, than the axial dimensions a1 of the chambers 3. Furthermore, the axial thickness d of the intermediate webs 7 is generally smaller, in particular significantly smaller, than the slope P. SG , chosen, for example, by a factor of 2 to 10 smaller. In absolute terms, d can be chosen, for example, between 1 and 3 mm.

[0086] Both axial dimensions a1 and a2 are larger than the slope P SG , but less than 2 P SG , so that a chamber 3 extends completely below the support surface 14A of a saw tooth or support element 14 or threaded section in longitudinal section and also projects into the area below the adjacent saw teeth or support elements 14 or threaded sections in longitudinal section.

[0087] Below every second support surface 14A lies an intermediate web 7, which simultaneously forms a non-hydraulic mechanical support and tension, in which the wall region 8 deforms less. The remaining edge at the end of the region with the support element(s) 14 has the axial dimension c and also deforms less.

[0088] More generally, the intermediate webs 7 below the support surface(s) 14A are arranged at an axial distance which is a multiple or an integer multiple, in particular twice, of the slope P SG which corresponds to the support surface(s) 14A.

[0089] In the Fig. 3 and Fig. In the case shown in Figure 4, five expansion zones arranged around the central axis M are preferably created on the wall 8, wherein the first and last expansion zones in the axial direction have a smaller width than the three expansion zones located between them. The individual expansion zones are bounded by the areas in which the webs 7 are arranged, the webs 7 reducing or preventing the expansion of the wall 8 where the webs 7 are connected to the wall 8.

[0090] The dimensions mentioned can be selected as indicated in all embodiments, but they can also be chosen differently and in variations from each other, depending on the desired clamping force and the workpiece or tool to be clamped. Furthermore, the chambers 3 can also have cross-sections other than the rectangular ones shown, for example, round, oval, or dumbbell-shaped cross-sections.

[0091] In a preferred embodiment, the hydraulic chambers 3 are fluidically connected via at least one hydraulic channel 17 to at least one pressure generator 16, for example, provided on an annular body 5. The channel 17 and the chambers 3 are fluidically sealed from the environment or form a closed hydraulic system, so that the adjustment of the hydraulic pressure p HThe operation of the pressure generator 16 in the chambers 3 is essentially leak-free. The pressure generator 16 can, in particular, be a threaded screw which, when screwed in, reduces the fluid volume of the channel 17 and thereby increases the hydraulic pressure in the channel 17 and the connected chambers 3, and can reduce it again by unscrewing it. Alternatively, an actively controllable pressure generator can be provided, for example, an adjustable pressure piston or the like. The chambers 3 can be designed to communicate fluidically with each other, at least partially or all, via intermediate channels or openings, in particular in or between the partitions or intermediate webs 7, or in the form of one or more circumferential chambers 3, or each chamber can be connected individually to the channel 17 and / or the pressure generator 16.

[0092] The Fig. 5, Fig. 6 and Fig. Figure 7 shows various embodiments for the design of the hydraulic chambers 3 and the intermediate webs 7. The intermediate webs 7 can preferably run on, be arranged on, or be formed on a shell 19, in particular a cylindrical shell, of the clamping body 2.

[0093] In the exemplary embodiment of the Fig. 5. Several, for example three, intermediate webs 7 are provided, each in the form of a helical line or a type of thread or twisted at a helix angle or twist angle β to the central axis M around the central axis M and preferably arranged or formed on a cylindrical surface 19 of the clamping body 2. The webs 7 are thus formed in particular like or similar to a multi-start, e.g. three-start, thread.

[0094] The membrane-like wall 8 with the support elements 14 is attached or connected or arranged and supported on the webs 7. Individual hydraulic chambers 3 are formed between the webs 7, which are open between the ends 23 of the respective intermediate webs 7 or are provided with openings 20, so that the fluid hydraulic medium can enter each of the chambers 3 or the chambers 3 are in fluidic communication or flow connection with each other.

[0095] Preferred values ​​for the helix angle β are between 40° and 80°, particularly between 50° and 70°. The helix angle β can also vary along the length of the webs 7. Advantageously, the helix angle β is adapted to the helix angle of the support surfaces or support elements, so that the helix angle of the webs corresponds to the helix angle P. SG agrees.

[0096] Furthermore, only one continuous helical web 7 may be provided, in particular in the form of a single thread, so that an opening 20 is arranged only at the beginning and at the end of the continuous and also twisted or helical chamber 3 lying in the space between the web 7.

[0097] These embodiments with helical or twisted webs 7 have the advantage that line contact is possible and, above all, that the webs can follow the threads or helical shapes of the support surfaces or support elements, thus achieving a comparatively stable structure with uniform force distribution. In multi-start embodiments with several, i.e., two or more, webs running side by side, a more uniform force distribution around the circumference is achieved.

[0098] In the embodiment according to Fig. The intermediate webs 7 between the hydraulic chambers 3 are essentially ring-shaped or closed and arranged perpendicular to the central axis M. The chambers 3 are thus hollow cylinder segments around the central axis M. Openings 24 are provided in the intermediate webs 7 for filling the chambers 3, through which the individual chambers 3 communicate fluidically with each other. The openings 24 are particularly small in relation to the length of the webs 7. The advantage of such ring-shaped hydraulic chambers 3 is that they are circumferential and easy to manufacture.

[0099] The webs 7 again support the membrane-shaped wall 8, in this embodiment in the same axial position over the entire circumference.

[0100] Fig. Figure 7 shows a further embodiment with intersecting webs 7 and 7'. First intermediate webs 7 are provided, which are again twisted or arranged along a helix at an angle of inclination or twist angle β to the central axis M. Furthermore, second intermediate webs 7' are provided, which are connected to the first intermediate webs 7 at intersection or connection points and project from the first intermediate webs 7, inclined opposite to the central axis M to the first intermediate webs 7. The webs 7 and 7' preferably intersect at an acute angle of 180° - β - γ or at an obtuse angle of β + γ. Preferred values ​​for the angle of inclination or twist β or the angle of inclination or twist γ are each between 40° and 80°, particularly between 50° and 70°. In particular, β = γ.

[0101] Openings 20 are formed between the ends of the first and second intermediate webs 7, through which the hydraulic chambers 3, bounded by two webs 7 on one side and two webs 7' on the other, are fluidically connected. Such a net-like or crossed arrangement of the webs results in particularly stable support of the tensioning membrane or wall 8 with the support elements 14.

[0102] By means of the structures according to Fig. 7. It is also possible to create cushion-shaped expansion zones. Cushion-shaped in this case means that not one expansion zone is provided completely circumferentially, but rather that several expansion zones can be provided one after the other circumferentially. The expansion zones created by the honeycomb or net-like structure of the webs 7 and 7' appear particularly on the wall 8 as rhombus- or honeycomb-shaped expansion zones, and many point contacts are realized. Other shapes such as cylindrical segments or oval shapes, etc., are also possible.

[0103] The slope of the webs 7 and the chambers is preferably a multiple of P SG However, to achieve good distribution on the support surfaces, this depends on the deformation of the workpiece and can be adjusted differently: For example, a groove or recess can also be provided in the workpiece in areas that are not to be deformed or are only slightly deformable, so that no tension is achieved there by the clamping sleeve or the hydraulic expansion does not lead to a pressing force there.

[0104] In Fig. Figure 8 shows an embodiment of a clamping device for a tool 55, in which the clamping device 10 is designed as a chuck. An outer clamping surface 56 of the tool 55 is clamped in an inner clamping surface 37 of a clamping sleeve 32. The clamping sleeve 32 is mechanically preloaded by means of cooperating support elements 34 on the clamping sleeve 32 and support elements 35 on a clamping body 36 surrounding the clamping sleeve 32, preferably coaxially to the central axis M, in order to generate a mechanical radial clamping force F. R, which then points inwards. Furthermore, hydraulic chambers 3 are provided in the clamping body 33, which are again separated from each other by webs 7 and which are pressurized with a hydraulic pressure p. H The hydraulic channel 17 and the hydraulic pressure transmitter 16 can be actuated. This presses the thin wall 38 between the chambers 3 and the support elements 35 of the clamping body 36 inwards, ultimately generating the hydraulic clamping force F. H on the clamping surfaces 37 of the clamping sleeve 32 and 56 of the tool 55. The arrangement of the chambers 3 and the intermediate webs 7 can also be in various variants analogous to the Fig. 5 to 7, wherein the webs 7 and 7' are then provided on the inside and not on the outside of the clamping body 36. The end walls of the clamping body 2 are in Fig. 5, Fig. 6 and 7 are designated as 21 and 22. A stop surface of a clamping element 12 preferably rests against the clamping sleeve 18. This clamping element can be axially displaced in the clamping movement direction ES by means of an actuating element, for example a threaded pin 13, thereby exerting an axial force on the clamping sleeve 18. This force allows the support elements 15 of the clamping sleeve 18 to be axially displaced relative to the support elements 14 of the clamping body 2, as already shown in the Fig. 1 and Fig. 2 explained. This results in the radial pressing force F R between the support elements 14 and 15, and this in turn generates a radial non-hydraulic or purely mechanical clamping force on the clamping surfaces 11 and 51.

[0105] The hydraulic pressure p HIn all embodiments, the hydraulic chambers 3 generate a pressure on the wall 8 or 38 with the support elements 14 or 34, which ultimately leads to a hydraulic clamping pressure or a hydraulic clamping force on the clamping surfaces 11 and 51 between the clamping sleeve 18 and the workpiece 50 or tool 55.

[0106] The radial pressing force F R , which is generated by the mechanical insertion movement and the corresponding radial material stress and deformation of the clamping sleeve 18, is controlled by the hydraulic radial force F H due to the hydraulic pressure p H in chambers 3 supplemented or (vectorally) superimposed, so that a resulting radial clamping force F R + F H This results in a radial clamping force F. R + F HThis corresponds to a tension on the workpiece or tool both through mechanical preload due to the insertion movement ES and through hydraulic tension by means of hydraulic pressure p. H in the hydraulic chambers 3 and the resulting hydraulic clamping force F H results.

[0107] In general, the insertion movements are used to generate the radial mechanical clamping force F. R and the hydraulic pressure p H so coordinated that the hydraulic clamping force F H is greater than the mechanical clamping force F R In particular, F H > 2F R , preferably F H > 4F R The hydraulic clamping force F H but it can also be significantly higher than the mechanical clamping force F R , for example, up to a factor of 100. A typical value for the hydraulic clamping force F HThis would be approximately 20% of the required holding force. Therefore, in this embodiment, only a slight mechanical preload is provided via the support elements 14 and 15 or 34 and 35, and the essential or main clamping force is generated hydraulically. Consequently, an axial stop for the workpiece, as required in the prior art according to [reference to prior art], is no longer strictly necessary. Fig. 1.

[0108] The web 7 is preferably located in the rear area of ​​the sawtooth of the clamping body 2 so that the deformability / radial path is ideal and the webs end at the free surface (see Fig. 8).

[0109] In Fig. Figures 9 to 11 show slotted clamping bushings 18 as part of or for use in a clamping device according to the invention, which has a slotted wall with individual slots 60, in particular extending substantially axially to a central axis of the clamping bushing 18.

[0110] In Fig. 9 Each slot 60 has in particular a narrower slot 61 and a wider slot (or: widening) 62, wherein the wider slot 62 forms a closed end of the slot 60 and the first slot 61 terminates or opens openly at an end face 18A or 18B of the clamping sleeve 18 or has an open end there.

[0111] In the embodiment according to Fig. 9 the slots 60 are formed alternately or opening at opposite end faces 18A and 18B or, in other words, the closed ends of the slots 62 each point in opposite axial directions.

[0112] Preferably, the slots 60 are evenly spaced or arranged at the same division angles to each other, whereby, for example, a division angle of 60° is possible with six slots or a division angle of 30° with twelve slots. The division angles can also be different in all embodiments.

[0113] Furthermore, the slots 60 can also each extend axially starting from the same end face 18A, so that their closed ends each point in the same axial direction.

[0114] Finally, in all embodiments it is also possible that the slots 60 do not have a widening 62, but have essentially the same width throughout or a smaller or differently shaped widening at their closed end.

[0115] Through the slots 60, in particular those according to Fig. 9. The meandering wall of the clamping sleeve 18 achieved makes a particularly uniform radial clamping of the clamping sleeve 18 possible.

[0116] On the inner wall, the clamping sleeve 18 again has the support elements 15, which run in particular along a thread or a helical line and, as in Fig. 9 can be identified, each being at least partially interrupted by the slots 60.

[0117] In Fig. 10 is starting from a clamping sleeve according to Fig. 9. In addition, a slot 70, closed on both sides, is arranged between each pair of slots 60 open on one side, wherein the slot 60 can in particular be wider than the narrower slot 61 of the slots 60 and in particular can be approximately as wide as the widening 62 of the slots 60. The angular distances of the slots 61 to each other and of the slots 70 to each other are in particular again uniformly distributed and all slots 60 and 70 again run axially or parallel to the central axis of the clamping sleeve 18.

[0118] Fig. 11 now shows similarly to Fig. 10, but only in a jacket winding representation, an embodiment with slots 80 open on one side, which again have a narrower slot 81 opening at an end face and have a closed end arranged in the axial direction opposite to a widened slot 82, wherein in contrast to Fig. 9 and Fig. 10. These one-sided closed slots 80 each open onto the same end face of the clamping sleeve 18, or rather, their closed ends each point in the same axial direction. Between the slots 80, slots 70 closed at both ends are arranged again, similar to in Fig. 10.

[0119] It is also possible for three adjacent slots, in particular two slots 70 and an intermediate slot 80, especially in the area of ​​its widened slot 82, to be connected to each other by a transverse slot 90, which forms a kind of T-connection. The slot 90 thus runs circumferentially around the central axis of the clamping sleeve 18.

[0120] Also in Fig. 11. The slots 80 can be formed without widening 82, and of course the angular distances that are in Fig. 11, which are represented as planar distances in the winding, may be the same or different.

[0121] In Fig. Figure 12 shows a cross-section of a slotted clamping sleeve 18 mounted on the clamping body 2. Several hydraulic chambers 3 are shown, which are designed in the form of axially extending hollow cylinder segments and are shown in cross-section. Fig. 12 are thus represented as ring segments. Between the hydraulic chambers 3, webs 7 are again formed, which now, as in Fig.As can be seen in Figure 12, the outer area of ​​the clamping body 12, which forms the support elements 14, is supported directly below the slots 60. As a result, when the hydraulic chambers 3 are pressurized, the slotted clamping sleeve 18 is stretched radially least in its most flexible area of ​​the slots 60; instead, mainly the wall areas of the clamping sleeve 18 located between the slots 60 are stretched outwards to come into contact with the workpiece and clamp it.

[0122] The underlying principle of this embodiment is therefore to support a slotted clamping sleeve with the webs or support webs at least partially where the slots are formed. Thus, if the slots have a different shape or do not run axially, the support web will at least partially follow this shape. Numerous variations of the slot shapes and the support webs that at least partially follow them are conceivable. For example, the slots of the clamping sleeve can also be arranged according to DE 20 2011 050 998 U1 or DE 20 2011 051 001 U1.

[0123] In all embodiments, hydraulic chambers 3 can be provided either in the clamping body or in the clamping sleeve or in both.

[0124] Preferably, the clamping device, in particular the clamping body, is manufactured using a 3D printing process. Reference symbol list 1 clamping device 2 clamping bodies 3 hydraulic chambers 4 5 Ring body 6 wall 7 clamping elements 8 wall 10 Clamping device 11 Clamping surface 12 clamping element 13 Threaded pin 14 Support element 14A Support surface 15 support element 15A Support surface 16 printing presses 17 shaft section 18 cocking rifle 18A, 18B Front 19 Surface area 20 openings 21, 22 Front wall 24 openings 30 chucks 31 mechanical clamping element 32 Tensioning bushing 34 Support element 35 Support element 36 clamping elements 37 clamping surface 38 wall 50 workpieces 51 Counter-tensioning surface 55 tools M Central axis ES clamping movement direction R Radial direction Z axial direction a1, a2 length b height c axial distance d thickness e radial distance ES insertion movement direction F ES Clamping force F R radial mechanical pressing / clamping force F H radial hydraulic pressing / clamping force P SG gradient P H hydraulic pressure ΔZ displacement ΔR radial path α Angle of inclination β Twist angle

Claims

[1] Clamping device (1, 10) for clamping a workpiece (50) or a tool (55) and in particular for coupling the workpiece (50) or the tool (55) to a machine spindle, comprising a) at least one clamping bushing (18, 32) rotating around a central axis (M) with at least one clamping surface (11, 37) for the workpiece (50) or tool (55) and b) at least one clamping element (2, 36), c) wherein the clamping sleeve (18, 32) has at least one support surface (15A) on a side facing away from the clamping surface (11, 37), which is formed along a helix or as a threaded section with a predetermined pitch (P SG ) runs around the central axis and is simultaneously inclined at an angle of inclination (α) to a direction (Z) axial to the central axis (M) or to an imaginary cylindrical surface running around the central axis (M), d) wherein the clamping body (2, 36) has at least one support surface (14A) on one side facing the clamping sleeve (18, 32), which is formed along a helix or as a threaded section with a predetermined pitch (P SG ) runs around the central axis (M) and is simultaneously inclined at an angle (α) to a direction (Z) axial to the central axis (M), e) wherein the clamping body (2, 36) and / or the clamping sleeve (18, 32) comprises one or more hydraulic chambers (3) formed inside the clamping body (2, 36) or the clamping sleeve (18, 32) and filled with a hydraulic medium, f) further comprising at least one displacement element (12, 13) to bring the opposing support surfaces (14A, 15A) of the clamping body (2, 36) and the clamping sleeve (18, 32) into contact with each other by an axial displacement movement along an axial displacement path (ΔZ) in the axial direction (Z) and / or to move them sliding against each other, whereby the diameter of the clamping surface (11, 37) can be changed or is changed in a direction (R) radial to the central axis (A) or whereby, with the clamping surface (11, 37) already in contact with the workpiece (50) or tool (55), a radial mechanical clamping force (F) is exerted R ) between clamping sleeve (18, 32) on the one hand and workpiece (50) or tool (55) on the other hand can be generated or is generated, g) further comprising at least one pressure generator (16) to pressurize the hydraulic medium in at least one of the hydraulic chambers (3) at a hydraulic pressure (p H) to act upon, which, with overlapping support surfaces (14A, 15A) of clamping body (2, 36) and clamping sleeve (18, 32), exerts a radial hydraulic pressing force (F) H ) on the overlapping support surfaces (14A, 15A) of clamping body (2, 36) and clamping sleeve (18, 32) is generated by the radial hydraulic pressing force (F H ) with the clamping surface (11, 37) already in contact with the workpiece (50) or tool (55), a radial hydraulic clamping force (F) H ) between clamping sleeve (18, 32) on the one hand and workpiece (50) or tool (55) on the other hand can be generated or is generated. [2] Clamping device (1, 10) according to claim 1, wherein the hydraulic clamping force (F H ) in addition to the mechanical clamping force (F R ) is generated and preferably in the same direction as the mechanical clamping force (F R ) is and / or where the hydraulic clamping force (F H) in amount to at least 2 times or at least 5 times or at least 20 times the mechanical clamping force (F) R ) adjustable or set. [3] Clamping device (1, 10) according to claim 1 or claim 2, in which corresponding support surfaces (14A, 15A) of clamping body (2, 36) and clamping sleeve (18, 32) are formed by a slope (P) on their SG ) adapted screw-in movement into each other can be brought into an engagement position or can be screwed in or screwed in, in which the support surfaces (14A, 15A) are at least partially opposite each other and / or are brought into contact, in particular wherein from this engagement position the axial displacement movement to generate the radial mechanical clamping force (F R ) and subsequently the chamber(s) (3) is subjected to the hydraulic pressure (p H ) by means of the pressure generator (16) to generate the hydraulic clamping force (F H ). [4] Clamping device (1, 10) according to one of the preceding claims, in which intermediate webs (7, 7') are arranged between the chambers (3), wherein in particular the axial dimension (d) of the intermediate webs (7, 7') is smaller, in particular at least by a factor of 4, than an axial dimension (a1) of the chambers (3) and / or wherein in particular the intermediate webs (7, 7') are arranged below the support surface(s) (14A, 15A) at an axial distance which corresponds to a multiple, in particular double, slope (P SG ) corresponds to the support surface(s) (14A, 15A). [5] Clamping device (1, 10) according to one of the preceding claims, in which a diaphragm-like wall (8) of the clamping body (2, 36) or the clamping sleeve (18, 32) is formed between the chamber(s) (3) and the support surface(s) (14A, 15A), which is connected to the support surface(s) (14A, 15A) by the hydraulic pressure (p H) is deformable or expandable in the radial direction, wherein in particular the membrane-like wall (8) of the clamping body (2, 36) or the clamping sleeve (18, 32) is supported on the intermediate webs (7, 7') or connected to the intermediate webs (7, 7'). [6] Clamping device (1, 10) according to claim 4 or claim 5, wherein a) at least one of the intermediate webs (7, 7') extends in a ring-like manner around the entire circumference, in particular perpendicular to the central axis (M), or b) at least one or more of the intermediate webs (7, 7') are spirally or helically shaped, in particular around the central axis (M), in particular at the same twist angle or at different twist angles, in particular opposite to each other, which is or are, for example, between 40° and 80°, in particular between 50° and 70°, c) at least one of the intermediate bridges (7, 7') extends only over part of the circumference or d) at least one of the intermediate webs (7, 7') runs, is arranged, or is formed on a lateral surface, in particular a cylindrical lateral surface (19), of the clamping body (2, 36) or the clamping sleeve (18, 32). and / or e) in which at least two intermediate webs (7, 7') intersect or form intersection points or are arranged in a diamond or honeycomb shape. [7] Clamping device (1, 10) according to one of the preceding claims, wherein at least one of the chamber(s) (3) a) runs in a ring-like shape around the entire circumference, in particular perpendicular to the central axis (M), or b) spiral or helical, especially around the central axis (M), or c) extends only over part of the circumference and / or is cushion-shaped and / or diamond- or honeycomb-shaped. [8] Clamping device (1, 10) according to one of the preceding claims comprising at least one or a combination of the following features: a) the chambers (3) have a radial dimension or height (b), in particular of the same size, which is in particular larger, preferably by at least a factor of 2.5, than a radial thickness (e) of the membrane-like wall (8), b) at least the axially inner chambers (3) have the same axial dimension (a1) c) the axially outer chambers (3) have a smaller axial dimension (a2) than the axial dimension (a1) of the axially inner chambers (3), d) the axial dimensions (a1, a2) of the chambers (3) are larger than the slope (P SG ) of the support surface(s) (14A, 15A), but less than twice the slope (P SG ), e) the chamber(s) (3) has or have a rectangular cross-section in an axial section. [9] Clamping device (1, 10) according to one of the preceding claims comprising at least one or a combination of the following features:, a) at least one or more of the chambers (3) is or are fluidically connected to the at least one pressure generator (16) via at least one hydraulic channel (17), b) at least two of the chambers (3) are designed to communicate fluidically with each other, in particular through intermediate channels or openings, especially in or between the intermediate webs (7, 7'). [10] Method for clamping a workpiece (50) or tool (55) with a clamping device (1, 10) according to one of the preceding claims, wherein a) the corresponding support surfaces (14A, 15A) of clamping body (2, 36) and clamping sleeve (18, 32) by a slope (P) on their SG) adapted twisting motion into each other into an engagement position in which the support surfaces (14A, 15A) are at least partially opposite each other and / or in contact, b) from this engagement position an axial displacement movement to generate the radial mechanical clamping force (F R ) is c) then the chamber(s) (3) with the hydraulic pressure (p H ) by means of the pressure generator (16) to generate the hydraulic clamping force (F H ) will be charged.

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