Coupling arrangement, coupling element

Abstract

Coupling arrangement (1) with two coupling elements (2, 3), each defining a longitudinal axis (X1, X2), and Clamping devices for axially clamping the coupling elements (2, 3) against each other, wherein a plurality of positive locking elements (8) are provided on mutually facing end faces (6, 7) of the coupling elements (2, 3), which project from the respective end face (6, 7) and are each arranged in a ring shape along a partial circle around the longitudinal axis (X1, X2) of the respective coupling element (2, 3), so that the positive locking elements (8) of one coupling element (2, 3) can be brought into engagement in the circumferential direction between the positive locking elements (8) of the other coupling element (2, 3) in order to couple the two coupling elements (2, 3) coaxially and rotationally fixedly to each other, characterized in that that the positive locking elements (8) have a contour corresponding to a partial section of a sphere.

Description

[0001] The present invention relates to a coupling arrangement with two coupling elements, each defining a longitudinal axis, and clamping means for axially clamping the coupling elements against each other, wherein a plurality of positive locking elements are provided on mutually facing end faces of the coupling elements, which project from the respective end face and are each arranged in a ring shape along a partial circle around the longitudinal axis of the respective coupling element, so that the positive locking elements of one coupling element can be brought into engagement in the circumferential direction between the positive locking elements of the other coupling element in order to couple the two coupling elements coaxially and rotationally fixed to each other.

[0002] Furthermore, the invention relates to a coupling element, in particular for a coupling arrangement according to the invention, wherein the coupling element defines a longitudinal axis and wherein a plurality of positive locking elements are provided on an end face of the coupling element, which project from the end face and are arranged in a ring shape along a partial circle around the longitudinal axis, so that the positive locking elements can be brought into engagement between positive locking elements of a corresponding coupling element in order to couple the coupling element with the corresponding coupling element coaxially and rotationally fixed.

[0003] Coupling devices for the rotationally fixed connection of two elements are used in many industrial sectors. For example, tools required for machining a workpiece in a machine tool, such as milling or drilling tools, are inserted into tool holders and fixed within them. These tool holders are then rotationally fixed to a driven spindle of the machine tool. Another application of such tool holders is in lathe tool holders, which are used on machine tools, especially lathes, and have mounting devices for holding a cutting insert, particularly an indexable insert. Such lathe tool holders are often rotationally fixed to a turret of a lathe.

[0004] For such tasks, it is generally necessary that the two elements to be coupled are positioned precisely and without play relative to each other, while simultaneously enabling the transmission of high torques. At the same time, rapid component replacement and thus quick coupling and uncoupling are desired to minimize downtime, for example, during machine reconfiguration.

[0005] For example, coupling arrangements based on a so-called Hirth coupling are known. Such coupling arrangements comprise two coupling elements, each of which has a plurality of positive-locking elements on its facing end faces. Specifically, these positive-locking elements are designed as teeth with a V-shaped cross-section, extending over an annular section around a longitudinal axis of the respective coupling element. The teeth run radially and taper inwards, so that their distance decreases radially inwards. By axially clamping the two coupling elements against each other using suitable clamping devices, the two coupling elements can be coaxially coupled in a rotationally fixed manner. The teeth of one coupling element are in engagement with the teeth of the other coupling element.The radial orientation of the teeth ensures that the two coupling elements are centered relative to each other. Torque transmission occurs via the contacting tooth flanks.

[0006] Although such a coupling arrangement has generally proven successful in practice, the fact that manufacturing the positive locking elements on the coupling elements is associated with considerable production effort is considered a disadvantage in some quarters. Furthermore, in the presence of contamination, a defined and backlash-free engagement of the positive locking elements of one coupling element with the corresponding positive locking elements of the other coupling element is not readily achievable.

[0007] The object of the present invention is therefore to provide an alternative coupling arrangement and a coupling element for the rotationally fixed coupling of two coupling elements, which in particular avoid the aforementioned disadvantages and allow for a simple, quick and safe coupling of the coupling elements.

[0008] This problem is solved in a coupling arrangement of the type mentioned above by the fact that the positive locking elements have a contour corresponding to a partial section of a sphere.

[0009] Similarly, the problem underlying the invention is solved in a coupling element of the type mentioned at the outset by the fact that the positive locking elements have a contour corresponding to a partial section of a sphere.

[0010] The invention is based on the fundamental idea of ​​designing the positive locking elements of both coupling elements in such a way that the positive locking elements engage with each other only via a substantially point-like contact. This is achieved by the spherical contour of the positive locking elements. As is known, for example, from deep groove ball bearings, adjacent spheres are able to transmit high point loads without plastic deformation. The purely point-like contact of the positive locking elements with each other results in open gaps between the two coupling elements into which any contaminants can escape.

[0011] Because the positive locking elements of both coupling elements are arranged distributed along a partial circle, a majority of the positive locking elements of one coupling element are always engaged between the positive locking elements of the other coupling element, thus positioning the two coupling elements relative to each other precisely and without play. Due to the different angular positions of the positive locking elements along the partial circle, the two coupling elements cannot be displaced radially relative to each other when the positive locking elements are engaged. Simultaneously, the coupling elements are centered relative to each other, so that their longitudinal axes are coaxial when coupled.Furthermore, the positive locking elements of one coupling element are in contact with two adjacent positive locking elements of the other coupling element, so that the coupling elements are also axially defined relative to each other when the positive locking elements are engaged.

[0012] Furthermore, the interlocking positive locking elements arranged circumferentially along the pitch circle ensure a uniform transmission of torque across multiple positive locking elements. Axial clamping of the two coupling elements against each other prevents them from axially separating and thus rotating. This creates a rotationally rigid coupling between the two coupling elements.

[0013] In a further embodiment of the present invention, the positive locking elements of each coupling element are arranged uniformly distributed in the circumferential direction along the respective partial circle. A uniform distribution of the positive locking elements in the circumferential direction results in a torque transmission that is symmetrical about the respective longitudinal axis.

[0014] Preferably, the gaps formed between the positive locking elements of at least one coupling element are smaller than the areas filled by the positive locking elements. This ensures that each positive locking element of one coupling element rests against two adjacent positive locking elements of the other coupling element, thus achieving a backlash-free coupling between the two coupling elements.

[0015] The pitch circles of the two coupling elements can have the same diameter. This results in the positive locking elements engaging with each other in such a way that the forces occurring at the contact points have only one component tangential to the pitch circle and one component in the axial direction.

[0016] Alternatively, the pitch circles of the two coupling elements can have different diameters. Pitch circles with different diameters result in the force transmitted via the point contact of the positive locking elements having a circumferential, an axial, and a radial force component.

[0017] In a further embodiment of this design, at least one coupling element has at least 6, preferably at least 10 and / or at most 28, preferably at most 20, positive locking elements. Such a number of positive locking elements distributed circumferentially has proven advantageous with regard to uniform torque transmission and, at the same time, precise positioning of the coupling elements relative to one another. With a correspondingly high number of positive locking elements, the transmission of high torques is still possible even if individual positive locking elements are damaged or missing and therefore do not engage. This increases the reliability of the coupling arrangement.

[0018] Preferably, the same number of positive locking elements are provided on each of the two coupling elements. This design ensures that each positive locking element contributes to torque transmission and allows for a number of relative rotational positions of the two coupling elements about their longitudinal axis that corresponds to the number of positive locking elements. In principle, it is also conceivable to provide a different number of positive locking elements on each coupling element.

[0019] Furthermore, the spherical contour of the positive locking elements of both coupling elements can have the same diameter. Thus, it is intended that both coupling elements have positive locking elements with an identical contour. This ensures uniform force transmission. Additionally, positive locking elements with the same diameter contour lead to optimal force transmission and therefore optimal material utilization during torque transmission. In principle, it is also conceivable that the spherical contour of the positive locking elements of the two coupling elements has different diameters. In this case, the gaps between two adjacent positive locking elements of the two coupling elements are of different sizes.

[0020] In a further embodiment of the invention, at least one coupling element and the associated positive locking elements are formed in one piece. A one-piece design offers the advantage of avoiding complex assembly during the manufacture of the coupling element. However, manufacturing such positive locking elements with a spherical contour is difficult. For example, production can be carried out using an additive manufacturing process, in particular selective laser melting. Choosing an additive manufacturing process allows different areas within a workpiece to be provided with different material compositions and / or properties. Thus, in this case, the positive locking elements could be made of a harder material than other areas of the coupling element.

[0021] Furthermore, the positive locking elements of at least one coupling element, preferably of both coupling elements, can be formed by balls which are arranged in corresponding recesses formed in the end face and partially project from the end face. Preferably, locking means are provided on the respective coupling element to prevent the balls from falling out of the recesses. The use of balls designed as separate components allows for simple manufacturing of the coupling elements, since only recesses, which are preferably substantially cylindrical, need to be made in the respective end face for the balls. The balls can be manufactured as separate components and subsequently easily inserted into the corresponding recesses.Furthermore, designing the coupling elements and the balls as separate components offers the advantage that the balls can be made of a harder material than the coupling element and thus withstand higher surface pressure. Appropriate locking mechanisms prevent the balls from unintentionally falling out of the recesses. For example, the recesses can be tapered towards the end face. Such tapers can be created by bending over a collar or burr surrounding the recesses after the balls have been inserted.

[0022] In a preferred embodiment of the invention, the spheres project from the end face by at least 10%, preferably at least 20%, and / or at most 40%, preferably at most 30% of their diameter. Such a dimension ensures a clean fit of the positive locking elements with a favorable position of the point contact on the sphere surface and thus a favorable direction of action of the forces transmitted by or acting upon the positive locking elements.

[0023] Preferably, the balls are made of a metallic material, in particular a bearing steel or a hard metal, or of a ceramic material, or of ruby ​​or sapphire. Bearing steel is a chromium-containing steel with a relatively high carbon content in the range of 0.8 to 1.1%, which can be hardened accordingly. Bearing steels can also contain molybdenum and manganese as alloying elements to increase hardness and strength. Thus, the balls are able to withstand high point loads without plastic deformation. Ceramic materials, as well as ruby ​​or sapphire, are also hard materials that are generally well-suited for absorbing high point loads.

[0024] For axially clamping the coupling elements against each other, the clamping devices can include a threaded union nut that can be screwed onto a corresponding mating thread of one coupling element and brought into contact with a shoulder formed on the other coupling element. A union nut offers a simple way to axially couple and clamp components together, as it can be actuated manually or with a tool from the outside. For manual actuation, the union nut can be provided with a profile or knurling on the outside, allowing a higher torque to be applied by the hand gripping the union nut than would be possible with a smooth surface.

[0025] The clamping devices can further comprise at least one clamping screw by means of which the two coupling elements can be screwed together to axially clamp them against each other. The clamping screw can extend in the direction of the longitudinal axis of a coupling element. This allows for a central and space-saving connection between the two coupling elements. A centrally arranged clamping screw ensures that the axial clamping force acts along the axis of symmetry of the torque transmission via the positive locking elements. This prevents tilting and uneven stress on the positive locking elements.

[0026] In a further embodiment of the invention, at least one coupling element can have a central through-bore. Thus, in addition to the purely mechanical coupling of the two coupling elements to each other, the coupling of a fluid connection, for example a coolant line, can also be realized.

[0027] Furthermore, a coupling element can have a longitudinally extending projection which can be inserted into a corresponding opening, in particular a bore, of the other coupling element. Such a projection provides additional guidance between the two coupling elements.

[0028] In a further embodiment of the invention, sealing means are also provided to seal the projection of one coupling element against the corresponding opening of the other coupling element. Specifically, the sealing means can comprise a sealing ring which is arranged in an annular groove of a coupling element. By means of such sealing means, in particular an annular sealing ring, the projection of one coupling element can be sealed fluid-tight against the corresponding opening of the other coupling element.

[0029] According to a further embodiment of the invention, a groove extending transversely to the longitudinal direction, with a V-shaped cross-section in particular, can be formed in the projection, and the other coupling element can have a threaded bore extending obliquely to the longitudinal axis for a clamping screw, wherein the threaded bore and the groove are designed such that a clamping screw screwed into the threaded bore can engage with a groove wall in order to axially clamp the two coupling parts against each other. This embodiment is based on the consideration of arranging an inclined surface in the projection, which in this case is formed by a groove wall against which a clamping screw presses in order to axially clamp the two coupling elements against each other.The inclined surface ensures that the force exerted by the clamping screw on the groove wall has an axial component, so that an axial force acts on the positive locking elements of the two coupling elements, thus preventing the two coupling elements from rotating relative to each other.

[0030] Preferably, the threaded bore is inclined at an angle of at least 20° and / or at most 40°, preferably exactly 30°, to the longitudinal axis of the respective coupling element. Such an angle results in a relatively high axial component with respect to the direction of action of the force exerted by the clamping screw on the groove wall, thereby achieving efficient axial clamping of the two coupling elements against each other.

[0031] In a manner known per se, one of the two coupling elements can be designed as a tool holder. Tools are subjected to high forces and torques during the machining of workpieces, so the coupling arrangement according to the invention provides an efficient and quick way to attach or detach tool holders from a machine in a rotationally fixed and backlash-free manner, despite possible contamination.

[0032] The coupling element, designed as a tool holder, can have a receptacle for a tool, particularly a tool shank, in the end region opposite the end face equipped with the positive locking elements. Such a receptacle can be designed as a receiving bore in which an inserted tool shank is fixed by friction and / or positive locking. For example, the tool holder can be designed as a hydraulic expansion chuck. In this case, the receptacle is surrounded by an annular pressure chamber or several pressure chamber sections distributed around the circumference. A thin wall is formed between the receptacle and the pressure chamber, which can be deformed radially inwards by an increase in pressure within the pressure chamber to fix a tool inserted into the receptacle by friction. Alternatively, the tool holder can be designed as a heat-shrink chuck.In this case, the diameter of the mounting bore is slightly smaller than the diameter of the tool shank to be inserted. When the tool holder is heated, the diameter of the mounting bore increases, and the tool shank can be inserted into the holder with minimal effort. Subsequent cooling causes the tool shank to be clamped securely in the holder.

[0033] Alternatively, the coupling element, designed as a tool holder, can have a receiving means for a tool, in particular for a cutting insert, preferably for an indexable insert. Cutting inserts are used, for example, to perform surface machining operations in lathes with a stationary tool and a rotating workpiece, so that considerable forces act on the corresponding cutting insert. The coupling arrangement according to the invention provides a simple way to quickly exchange such cutting insert or turning tool holders and at the same time to transmit high forces and torques without backlash.

[0034] For further details of the invention, reference is made to the dependent claims and to the exemplary embodiment described below with reference to the drawing.

[0035] The drawing shows: Fig. 1 a first embodiment of a coupling arrangement according to the present invention in a longitudinal sectional view; Fig. 2 a second embodiment of a coupling arrangement according to the present invention in a longitudinal sectional view; Fig. 3 a coupling element in a third embodiment of a coupling arrangement according to the present invention in perspective view; Fig. 4 a fourth embodiment of a coupling arrangement according to the present invention in a longitudinal sectional view; Fig. 5 a coupling element of the coupling arrangement made of Fig. 4 in perspective view; Fig. 6 the other coupling element of the coupling assembly Fig. 4 in perspective view; Fig. 7 the coupling element from Fig. 6 in a different perspective view.

[0036] The Fig. Figure 1 shows a coupling arrangement 1 according to the present invention, which has two coupling elements 2, 3, each defining a longitudinal axis X1, X2 and being coaxially coupled to each other in a rotationally fixed manner.

[0037] The one in Fig. The coupling element 2, located on the left, is designed as a tool holder and has a receptacle 4 in its left-facing end region for a tool, in particular for a tool shank. A central through-bore 5 adjoins the receptacle 4 and extends completely through the coupling element 2 in the axial direction. The coupling element 3 on the right is designed as an extension of a spindle shaft of a machine tool and also has a central through-bore 5.

[0038] On each of the two opposing end faces 6, 7 of the coupling elements 2, 3, twelve positive locking elements 8 are provided, projecting from the respective end face 6, 7. These are formed by balls 9 of the same diameter, which are arranged in corresponding recesses 10 formed in the respective end face 6, 7 and project from the respective end face 6, 7 by approximately 25% of their diameter. The balls 9 are made of a bearing steel and are secured against falling out of the recesses 10 by appropriate locking means, in this case a tapered section of the recesses 10.

[0039] The recesses 10 and the spheres 9 are each arranged in a ring shape along partial circles of the same diameter around the longitudinal axis X1, X2 of the respective coupling element 2, 3, with even distribution. The gaps formed between the spheres 9 are smaller than the areas filled by the spheres 9.

[0040] In the Fig. In the state shown in Figure 1, the balls 9 of the coupling element 2 are engaged circumferentially between the balls 9 of the coupling element 3 in order to couple the two coupling elements 2, 3 together in a rotationally fixed manner. The arrangement is such that the balls 9 of one coupling element bear against two adjacent balls 9 of the other coupling element at a single point.

[0041] The coupling arrangement 1 further comprises clamping means for axially clamping the coupling elements 2, 3 against each other. In this case, these clamping means include a union nut 11 with an internal thread 12, which is screwed onto a corresponding mating thread 13 of the coupling element 3. A shoulder 14 is formed on the coupling element 2, against which the union nut 11 rests in order to axially clamp the coupling elements 2, 3 against each other.

[0042] To guide a fluid, for example a cooling lubricant, the coupling element 2 has a longitudinally extending projection 15, which is inserted into a corresponding bore 16 of the coupling element 3. Sealing means are provided to seal the projection 15 of the coupling element 2 against the corresponding bore 16 of the coupling element 3. The sealing means comprise a sealing ring 17, which is arranged in an annular groove in the bore 16 of the coupling element 3.

[0043] In the Fig. Figure 2 shows a further embodiment of a coupling arrangement 1 according to the present invention. This has two coupling elements 2, 3 which are connected by corresponding positive locking elements 4, in the same manner as in the Fig. The embodiments shown in 1 are designed and are coupled together in a rotationally fixed manner. From the embodiment shown in the Fig. In the embodiment shown in 1, the coupling arrangement 1 differs from the Fig. 2 by the fact that the clamping devices do not have a union nut 11, but a central clamping screw 19, by means of which the two coupling elements 2, 3 are screwed together.

[0044] Specifically, the clamping screw 19 is screwed into a threaded bore 20 formed in the coupling element 2. The screw head 21 of the clamping screw 19, which in this case is designed as a socket head cap screw, rests against a corresponding contact surface 22 of the coupling element 3.

[0045] In the Fig. 3 is a coupling element 2 designed as a tool holder according to the present invention. This has, in the same way as the one in the Fig. 1 and Fig. The coupling elements 2 shown comprise a total of twelve positive locking elements 8 arranged along a partial circle around a longitudinal axis X1 of the coupling element 2 and designed as spheres 9, which project from an end face 6.

[0046] A drawbar 23 projects from the end face 3, which is designed for axially clamping the coupling element 2 against a corresponding coupling element. This drawbar 23 is designed in this case similarly to a steep taper according to ISO 7388-1.

[0047] In the Fig. 4, Fig. 5, Fig. 6 to Fig. Figure 7 shows a further coupling arrangement 1 designed as a lathe tool holder with an interchangeable head according to the present invention. The coupling arrangement 1 is designed as a lathe tool holder with an interchangeable head. Fig. The coupling element 2 shown on the left is designed as an interchangeable head for receiving a tool, in particular a cutting insert. The coupling element 3 shown on the right has a central through-bore 24 into which several threaded bores 25, extending perpendicular to the longitudinal axis X2 and axially and serving as coolant connections, open.

[0048] In the same way as with the coupling arrangements 1 from the Fig. 1 and Fig. In the two coupling elements 2, 3, each has a plurality, in this case fourteen, of positive locking elements 8 on their opposing end faces 6, 7. These positive locking elements project from the respective end faces 6, 7 and are arranged in a ring shape along a partial circle around the longitudinal axis X1, X2 of the respective coupling element 2, 3. As in the previously described embodiments, the positive locking elements 8 are formed by balls 9, which are also made of a bearing steel and are arranged in corresponding recesses 10 formed in the respective end faces 6, 7.

[0049] The coupling element 2 has a projection 15 which can be inserted into a corresponding bore 16 of the coupling element 3, or - as shown in Fig. 4 is shown - it is inserted. In the projection 15 of the coupling element 2 is - as shown in the Fig. 6 and Fig. As can be seen in Figure 7, a groove 26 extending transversely to the longitudinal direction X1 is formed. This groove has a V-shaped cross-section, with the groove in the Fig. 4 The groove wall 27 shown on the right is oriented at an angle of 30° to the end face 6.

[0050] The coupling element 3 has a threaded bore 28 for a clamping screw 19, which also extends at an angle of 30° to the longitudinal axis. The clamping screw 19, designed as a hexagon socket screw, has a threaded section 29 on the outside of the coupling element 3 and a shaft 30 located inside the coupling element 3, wherein the end face of the shaft 3, which faces inwards into the coupling element 3, presses against the groove wall 27 in order to clamp the coupling elements 2, 3 axially against each other.

[0051] Should the two coupling elements 2, 3, starting from the one in the Fig. 5 and Fig. To couple the two coupling elements 2, 3 in the separated state shown in Figure 6 in a coaxially rotationally fixed manner, the two coupling elements 2, 3 must first be positioned such that their end faces 6, 7 are facing each other. The projection 15 is then inserted into the bore 16 until the positive locking elements 8 of the two coupling elements 2, 3 engage with each other. This positions the two coupling elements 2, 3 precisely and without any play relative to each other. By screwing the clamping screw 19 into the threaded bore 28, the end face of the shaft 30 comes into contact with the groove wall 27 of the groove 26 formed in the projection 15. The axial force component exerted by the clamping screw 19 on the groove wall 27 clamps the two coupling elements 2, 3 axially against each other.

[0052] The in the Fig. 1 and Fig. The embodiments shown in Figure 2 are coupled in the same way, but instead of the clamping screw 19, which presses against the groove wall 27, the two coupling elements 2, 3 are screwed together. In the embodiment shown in the Fig. In the embodiment shown in 1, the union nut 11 is used for this purpose, in which the Fig. In the embodiment shown in 2, the clamping screw 19.

[0053] Such a connection via interlocking positive locking elements 8 of the two coupling elements 2, 3 enables backlash-free torque transmission with simultaneous precise centering of the coupling elements 2, 3 relative to each other through the point-like contact of the spherical surfaces of the positive locking elements 8. Reference symbol list 1 Coupling arrangement 2 coupling element 3 coupling element 4 recording 5 through holes 6 Front surface 7 Front surface 8 Positive locking element 9 balls 10 Exclusion 11 Union nut 12 internal threads 13 external threads Paragraph 14 15 lead 16 bore 17 Sealing ring 18 ring-shaped circumferential grooves 19 Tensioning screw 20 threaded holes 21 screw head 22 Plant area 23 drawbars 24 central through-holes 25 threaded holes 26 Nut 27 Groove wall 28 threaded holes 29 Thread section 30 shaft X1 Longitudinal axis X2 Longitudinal axis

Claims

[1] Coupling arrangement (1) with two coupling elements (2, 3), each defining a longitudinal axis (X1, X2), and Clamping devices for axially clamping the coupling elements (2, 3) against each other, wherein a plurality of positive locking elements (8) are provided on mutually facing end faces (6, 7) of the coupling elements (2, 3), which project from the respective end face (6, 7) and are each arranged in a ring shape along a partial circle around the longitudinal axis (X1, X2) of the respective coupling element (2, 3), so that the positive locking elements (8) of one coupling element (2, 3) can be brought into engagement in the circumferential direction between the positive locking elements (8) of the other coupling element (2, 3) in order to couple the two coupling elements (2, 3) coaxially and rotationally fixed to one another, characterized by , that the positive locking elements (8) have a contour corresponding to a partial section of a sphere. [2] Coupling arrangement (1) according to claim 1, characterized by , that the positive locking elements (8) of each coupling element (2, 3) are arranged evenly distributed in the circumferential direction along the respective partial circle. [3] Coupling arrangement (1) according to claim 1 or claim 2, characterized by , that the gaps formed between the positive locking elements (8) of at least one coupling element (2, 3) are smaller than the areas which are filled by the positive locking elements (8). [4] Coupling arrangement (1) according to one of the preceding claims, characterized by , that the pitch circles of the two coupling elements (2, 3) have the same diameter. [5] Coupling arrangement (1) according to any one of claims 1 to 3, characterized by , that the pitch circles of the two coupling elements (2, 3) have different diameters. [6] Coupling arrangement (1) according to one of the preceding claims, characterized by, that at least one coupling element (2, 3) has at least 6, preferably at least 10 and / or at most 28, preferably 20 positive locking elements (8). [7] Coupling arrangement (1) according to any one of the preceding claims, characterized by , that the same number of positive locking elements (8) are provided on each of the coupling elements (2, 3). [8] Coupling arrangement (1) according to one of the preceding claims, wherein the spherical contour of the positive locking elements (8) of the two coupling elements (2, 3) has the same diameter. [9] Coupling arrangement (1) according to any one of the preceding claims, characterized by , that at least one coupling element and the associated positive locking elements (8) are formed in one piece. [10] Coupling arrangement (1) according to any one of claims 1 to 8, characterized by, that the positive locking elements (8) of at least one coupling element (2, 3) are formed by balls (9) which are arranged in corresponding recesses (10) formed in the end face (6, 7) and partially project from the end face (6, 7), wherein locking means are preferably provided on the respective coupling element (2, 3) to prevent the balls (9) from falling out of the recesses (10). [11] Coupling arrangement (1) according to claim 10, characterized by that the spheres (9) protrude from the end face (6, 7) by at least 10%, preferably at least 20%, and / or at most 40%, preferably at most 30% of their diameter. [12] Coupling arrangement (1) according to claim 10 or 11, characterized by , that the balls (9) are made of a metallic material, in particular a bearing steel or a hard metal, or of a ceramic material or of ruby ​​or sapphire. [13] Coupling arrangement (1) according to any one of the preceding claims, characterized by , that the clamping means comprise a union nut (11) with a thread which can be screwed onto a corresponding mating thread of a coupling element (3) and can be brought into contact with a shoulder (14) formed on the other coupling element (2) in order to clamp the coupling elements (2, 3) against each other. [14] Coupling arrangement (1) according to any one of claims 1 to 12, characterized by , that the clamping means comprise at least one clamping screw (19) by means of which the two coupling elements (2, 3) can be screwed together in order to clamp the coupling elements (2, 3) axially against each other. [15] Coupling arrangement (1) according to claim 14, characterized by , that the clamping screw (19) extends in the direction of the longitudinal axis (X1) of a coupling element (2, 3). [16] Coupling arrangement (1) according to any one of the preceding claims, characterized by, that a coupling element (2) has a longitudinally extending projection (15) which can be inserted into a corresponding opening, in particular a bore (16) of the other coupling element. [17] Coupling arrangement (1) according to claim 16, characterized by , that sealing means are also provided to seal the projection (15) of one coupling element (2) against the corresponding opening of the other coupling element (3). [18] Coupling arrangement (1) according to claim 17, characterized by , that the sealing means comprise a sealing ring (17) which is arranged in an annular circumferential groove (18) of a coupling element (3). [19] Coupling arrangement (1) according to one of claims 15 to 17 and claim 13, characterized by, that in the projection (15) a groove (26) extending transversely to the longitudinal direction with a particularly V-shaped cross-section is formed and the other coupling element (3) has a threaded bore (28) extending obliquely to the longitudinal axis (X2) for a clamping screw (19), wherein the threaded bore (28) and the groove (26) are designed such that a clamping screw (19) screwed into the threaded bore (28) can be brought into engagement with a groove wall (27) in order to clamp the two coupling parts axially against each other. [20] Coupling arrangement (1) according to claim 19, characterized by , that the threaded bore (28) is inclined at an angle of at least 20° and / or at most 40°, preferably at exactly 30° to the longitudinal axis (X2) of the coupling element concerned. [21] Coupling arrangement (1) according to any one of the preceding claims, characterized by , that at least one coupling element (2, 3) has a central through-hole (5). [22] Coupling arrangement (1) according to one of the preceding claims, characterized by , that one of the two coupling elements (2) is designed as a tool holder. [23] Coupling arrangement (1) according to claim 22, characterized by , that the coupling element (2) designed as a tool holder has a receptacle (4) for a tool, in particular for a tool shank, in the end area which is opposite the end face (6) provided with the positive locking elements (8). [24] Coupling arrangement (1) according to claim 22, characterized by , that the coupling element (2) designed as a tool holder has a receiving means for a tool, in particular for a cutting insert, preferably for an indexable cutting insert. [25] Coupling element (2), in particular for a coupling arrangement (1) according to one of the preceding claims, wherein the coupling element (2) defines a longitudinal axis (X1) and wherein a plurality of positive locking elements (8) are provided on an end face (6) of the coupling element (2), which project from the end face (6) and are arranged in a ring shape along a partial circle around the longitudinal axis (X1), so that the positive locking elements (8) can be brought into engagement between positive locking elements (8) of a corresponding coupling element in order to couple the coupling element (2) to the corresponding coupling element coaxially and rotationally fixedly, characterized by , that the positive locking elements (8) have a contour corresponding to a partial section of a sphere.

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