Self-locking clamp system for a hollow shaft

Abstract

A self-locking clamping system for hollow shaft adapters was proposed.

Description

Technical Field

[0001] For example, clamping systems with a hollow shaft and a centering mount of complementary shape according to ISO 12164 or ISO 26623 have been proven to be on the market for many years.

Background Art

[0002] Among other things, they are used in driven or fixed tool holders. And the centering mount and the clamping system are integrated into the spindle of the drive tool holder or the housing of the tool holder. The hollow shaft is part of an adapter that carries a drill, a lathe tool or other tool.

[0003] Known clamping systems for clamping such a hollow shaft comprise a collet consisting of a number of clamping segments. The clamping segments are arranged around a tension bolt. The axial movement of the tension bolt relative to the clamping segments forces them radially outwards. This initially results in a secure clamping fit with the hollow shaft at the front end of the clamping segments. Further movement of the tension bolt generates an axial clamping force that acts on the hollow shaft of the adapter and causes the adapter to be pulled into the centering mount. An example of such a clamping system is known from European Patent EP 2 164 662.

[0004] Such a clamping system is not self-locking. As a result, in order to maintain the clamping force, the actuating force must always act on the clamping system during operation of the tool holder. Otherwise, the clamping system will become disengaged.

[0005] This is very difficult to achieve, especially in the hydraulic clamping system of the rotating spindle of a drive tool holder. When the actuating force and thus the clamping force are applied by a spring arranged on the tool holder, this represents an increase in the requirements for the installation space. Furthermore, since the force of the tension spring must also be overcome, the force required to release the clamping system becomes greater.

[0006] A clamping device with a self-locking mechanism is known from European Patent EP 1 924 379 B1. The clamping process is carried out by a clamping head 6 that cooperates with the clamping jaws 5 in a manner known per se. A tension bolt 4 is attached in front of the clamping head 6, and this tension bolt is axially moved by an actuating device in order to clamp or release the clamping device. Between the tension bolt 4 and the clamping chuck 6, a two-piece draw tong 7 and a clamping sleeve 11 are provided. During tension application, the offset 15 of the tension bolt 4 contacts the inner collar of the tension tong 7, so that the movement of the tension bolt 4 is transmitted directly to the tension head 6 via the tension tong 7. After the tension bolt has moved a certain distance, half of the extension tong 7 deflects radially outwards. This cancels out the reliable locking fit between the half-shell of the draw tong 7 and the tension bolt.

[0007] In a further process of the clamping process, the draw tong 7 is only slightly dragged along axially, but instead is wedged between the conical head 12 of the tension bolt 4, which is attached in such a way as to be fixed to the housing until the desired self-locking is achieved, and the clamping sleeve 11.

[0008] Such a device has a complex structure and requires, in addition to the clamping chuck and the tension bolt, a two-piece draw tong and a clamping sleeve 11. Furthermore, it requires a relatively large movement of the tension bolt, requires a large amount of installation space, and is costly to manufacture.

[0009] In the field of machine tools, another clamping device with self-locking is known from German Patent DE 196 18 610 A1. The self-locking occurs at the front end of the clamping segment. However, such self-locking is not sufficient. Therefore, an additional fixing device is required. Such an additional fixing device is provided with a compression spring, and this compression spring presses the wedge-shaped segment against the conical / conical part of the tension bolt. As a result, the spring force of such a compression spring causes a frictional connection to the spindle via the wedge-shaped segment. Such a frictional connection counteracts an unintentional opening of the clamping set. Also, such a solution requires a large amount of installation space and increases the manufacturing cost. Furthermore, in addition to the frictional force, the force of the compression spring also has to be overcome in order to release the clamping system. This means a high force, which in turn requires a large cylinder assembly, which is also disadvantageous. SUMMARY OF THE INVENTION

[0010] The object of the present invention is to provide a clamping system that is self-locking and has a very compact, simple and robust structure. Such a compact design is particularly important when there is little space available. This is the case, for example, for turrets with a center of rotation. Here, the clamping system must be flexibly attachable to various positions and orientations of the upright and drive tool holders. As a result, the installation space is severely restricted, for example, by the allowable pivot diameter, the width of the threading surface, and the interface to the center of rotation.

[0011] According to the present invention, such an object is achieved by a clamping device for a hollow shaft taper, in particular a hollow shaft having a circular or polygonal outer contour, comprising one or more clamping segments and a tension bolt cooperating with the clamping segments. Each clamping segment has a front clamping claw at its front end on its outer side and a front lug cooperating with the tension bolt on its inner side. Each clamping segment has a rear clamping claw at its rear end on its outer side and a rear lug cooperating with the tension bolt on its inner side. In the clamping position, the front clamping claws of each clamping segment fit into the clamping grooves of the hollow shaft, and the rear clamping claws are pressed against the conical part of an adjacent part or spindle. In the open position, the front clamping claws do not fit into the clamping grooves of the hollow shaft, and by axial displacement, the tension bolt moves the clamping segments from the clamping position. The clamping segments perform a first rotational movement during the transition from the open position to the open position. The front clamping claws of the clamping segments fit into the clamping grooves so as to be securely locked, and form a joint for the subsequent second rotational movement of the clamping segments. During the second rotational movement, the rear projection of the clamping segment slides on the third conical part of the tension bolt, pressing the rear clamping claws of the clamping segment against the conical part of an adjacent part or spindle to axially clamp the clamping segment. During the further axial movement of the tension bolt following the second rotational movement, the rear projection of the clamping segment slides on the second conical part of the tension bolt, resulting in a self-locking effect between the clamping segment and the tension bolt at the rear end of the tension bolt.

[0012] The mutually coordinated movement sequences according to the invention achieve a secure clamping connection between the pre-clamping jaws of the clamping segment and the clamping groove of the hollow shaft in the first pivoting movement. Subsequently, such a secure locking connection at the front end of the clamping segment functions as a pivot point / bearing for the clamping segment or the plurality of segments. Subsequently, in the second pivoting movement, the rear end of the clamping segment is pressed radially outwards against the conical part of the adjacent part or the spindle, thereby accumulating an axial clamping force. In the subsequent further movement of the tension bolt, the axial clamping force further increases. At the same time, a self-locking effect occurs between the rear lug of the clamping segment and the second conical part of the tension bolt. Even if no self-locking occurs at the rear end of the tension bolt, there is a positive effect of clamping and fixing the tension bolt at the front and rear ends.

[0013] According to the invention, no additional parts of the clamping system are required to create a reliable self-locking effect in operation. Rather, the desired self-locking effect is achieved by designing the tension bolt according to the invention and coordinating it with the clamping segment and the conical part. As a result, the solution according to the invention is very compact and very advantageous in terms of production and cost. Another advantage is that the operating forces for clamping and releasing are relatively small and there is not much difference in size. Of course, the operating force required for clamping is somewhat greater than the operating force required for release.

[0014] When the clamping system is automatically actuated with the aid of an actuator such as a hydraulically actuated cylinder assembly, the approximately equal forces for clamping and releasing are a particular advantage. The dimensions of such an actuator are usually determined by the maximum operating force.

[0015] Another advantage of the clamping system according to the invention is that, after the second pivoting movement, when the trailing edge of the clamping segment slides on the second conical portion of the tension bolt, the axial tension of the clamping segment increases such that the hollow shaft is pulled on the adjacent component or spindle with a greater force (booster function).

[0016] Furthermore, in the clamping system according to the invention, the tension bolt is centered at its front end by the leading edge of the clamping segment in the clamping groove of the hollow shaft and at its rear end by the trailing edge of the clamping segment on the conical portion. As a result, the clamping system has no imbalance at all or, if any, only a very small imbalance. Thereby, the machining quality of the workpiece machined with the tool clamped to the hollow shaft is improved, and in the case of a driven tool, machining at a very high spindle speed becomes possible.

[0017] Another advantage of the clamping system according to the invention is that the leading edge and the shape of the clamping groove can be designed relatively freely. It can be used in systems such as ISO 12164 (HSK) or ISO 26623 (Colomant Capto).

[0018] In an advantageous embodiment of the invention, the first cylindrical portion, the first conical portion, the second cylindrical portion, the second conical portion, the third conical portion and the third cylindrical portion are continuously formed on the tension bolt starting from its front end FE. During the first pivoting movement, the leading edge slides on the first conical portion. During the second pivoting movement, the trailing edge slides on the third conical portion. During the subsequent rotational movement caused by a further axial movement of the tension bolt, the trailing edge slides on the second conical portion and a self-locking effect is built up.

[0019] Self-locking means that once the clamping system is tensioned, it is not necessary to apply any further actuating force to the tension bolt, and the tension bolt remains in its position due to the self-locking effect and a sufficiently large clamping force is still applied.

[0020] In other words, when the tension bolt is hydraulically actuated, the cylinder assembly that actuates the tension bolt can be depressurized after tensioning without affecting the tension of the clamping system or adapter according to the present invention.

[0021] This is a particular advantage when the clamping system is installed on a rotating spindle and the spindle rotates during machining. In this case, unlike other systems, there is no need to continuously apply an actuating force to maintain the clamping force. Rather, due to self-locking, the clamping force is maintained in the clamping system.

[0022] Also, there is no need to integrate a spring that rotates with the spindle and permanently applies an actuating force. The drawback of this solution is that the spring can cause imbalances, and in addition to the frictional force, the spring force also has to be overcome to release the clamping system. This means a high actuating force, which in turn requires a large cylinder assembly, which is also disadvantageous.

[0023] The conical part is an internal conical part and can be directly incorporated into either the housing, an adjacent part or the spindle. Alternatively, it is also possible to provide a threaded ring with the conical part incorporated therein. Such a threaded ring is then screwed into the housing, an adjacent part or the spindle. Of course, the connection does not have to be a threaded connection between the ring and the housing. Other connections can also be used to center the conical part radially and hold the position in the direction of the clamping force, such as a pairing of a bore and a cylinder with a fixing ring for axial positioning.

[0024] If the inclination angle of the second conical part is 5° or less than the arctangent of the coefficient of friction μ generated by the mating of the contact surfaces of the clamp segment and the tension bolt, it has been proven to be advantageous. This provides self-locking in a simple and very safe way. Of course, when determining the coefficient of friction and thus the inclination angle of the second conical part, it is also desirable to take into account the influence of fluids such as oil or coolant lubricant, surface finish, material pairing, possible coatings, and additional safeguards against loosening due to vibration. Considering such situations, self-locking can be ensured under all conditions occurring during operation.

[0025] In many cases, if it is proven that an inclination angle of 4° in the range of 3° to 5° of the second conical part is a very good value, it is sufficient or has been proven to be advantageous.

[0026] In contrast, the inclination angles of the first conical part and the third conical part are much larger. They are in the range of 30° to 60°, and preferably, both inclination angles are equal to 45°.

[0027] In the tension bolt according to the present invention, it is provided that the second conical part and the third conical part are joined to each other without a change in diameter and without an intermediate cylindrical part. Thereby, the necessary clamp movement of the tension bolt is minimized. The transition between the two conical parts is made without interruption.

[0028] The front lag of the clamp segment has a first contact surface adapted to the inclination angle of the first conical part of the tension bolt (starting from the front end) and a second contact surface adapted to the cylindrical part. This optimally controls the first pivot movement while the front clamp claws of the clamp segment enter the clamp groove of the hollow shaft.

[0029] "Alignment" in this connection means that the contact surface between the lag of the clamp segment and the tension bolt at various positions of the tension bolt with respect to the clamp segment is as large as possible, and no high-load edge support occurs in order to reduce surface pressure and wear. Therefore, the inclination angles are almost the same.

[0030] However, for example, in order to prevent edge support that may occur from the rotational movement of the clamp segment, it is also possible that the shape of the contact surface is slightly crowned or barrel-shaped. Similarly, the cylindrical portion of the tension bolt may be designed to be slightly barrel-shaped.

[0031] In order to increase the self-locking effect of the clamp system according to the present invention, it may be advantageous to design the first cylindrical portion as a conical portion having a small negative inclination angle α.

[0032] The inclination angle α of the first cylindrical portion can be positive or negative. Despite the resulting linguistic "inaccuracy", the first cylindrical portion is also referred to when it has a small inclination angle, and thus, strictly speaking, it is the fourth conical portion.

[0033] The magnitude of the inclination angle α can be 4° or less. In the case of a negative inclination angle α, it is below the inclination angle of the second conical portion of the tension bolt. The positive inclination angle α can increase the clamping movement and, like the second conical portion, can have an inclination angle smaller than the arctangent (inverse tangent) of the coefficient of friction μ.

[0034] In the case of a negative inclination angle α, the conical portion at the front end (= the first cylindrical portion) of the tension bolt faces the same direction as the conical portion of the threaded ring and faces the opposite direction to the second and third conical portions of the tension bolt. In FIG. 8, a negative inclination angle α is illustrated.

[0035] Therefore, for a negative tilt angle α, the conical part at the front end of the tension bolt (= the first cylindrical part) and the conical part of the threaded ring are directed in opposite directions; the positive tilt angle, since the gripper groove there is designed in a wedge shape, can be useful, for example, in HSK, to increase the clamping movement.

[0036] Self-locking means preventing, by design means, the tension bolt from moving from the clamped position to the open position due to imbalances, vibrations, pressure surges of the cooling lubricant, and other external forces that may act during operation. This would be a movement in the direction of the centering mount.

[0037] For any negative tilt angle α, the radial force acting from the front lag of the clamping segment of the first cylindrical part causes an axial force on the tension bolt in the direction of the clamped position.

[0038] In a further advantageous embodiment, the rear lag of the clamping segment has a third contact surface adapted to the tilt angle of the third conical part and a fourth contact surface at their rear ends adapted to the second conical part.

[0039] This means that initially the second pivot movement is controlled by the third conical part of the tension bolt.

[0040] Subsequently, after most of the radial stroke and a certain (usually still insufficient) clamping force have been achieved, further tensioning is performed between the clamping bolt and the trailing lug of the clamping segment, and between the trailing clamping claw of the clamping segment and the conical portion of the threaded ring or spindle housing. The trailing lug of the clamping segment slides on the second conical portion. The inclination angle of the second conical portion is significantly smaller than the inclination angle of the third conical portion. This reduces the reduction ratio between the axial movement of the tensioning bolts and the rotational movement of the clamping segments at their rear ends. That is, the same axial movement of the tensioning bolts results in a smaller radial movement of the clamping segments. As a result, the axial clamping force of the clamping segments, and thus the axial or clamping force acting on the hollow shaft, increases (assuming a constant axial force of the tensioning bolts) (booster function). In other words, the required clamping force is achieved such that the clamping segments pull the adapter into the centering mount with a large force, even though the displacement force acting on the tensioning bolts is relatively small.

[0041] Due to the small inclination angle of the second conical portion, a relatively large radial force is generated, which is transmitted safely and without overloading the components through a large contact surface between the second conical surface of the tensioning bolt and the fourth contact surface of the trailing lug of the clamping segment.

[0042] In particular, this makes the solution according to the invention highly durable, with little or no wear, and the surface pressure between the lug and the second conical portion of the tensioning bolt remaining within the allowable value.

[0043] The inclination angle between the conical portion of the threaded ring or housing and the fifth contact surface of the trailing clamping claw of the clamping segment that corresponds and conforms to it is preferably in the range of 20° to 45°. An inclination angle in the range of 25° to 40°, particularly 30° or 35°, has proven to be very suitable.

[0044] In a further advantageous embodiment, the clamping segment is supported at the rear end directly against a spring-loaded intermediate disk or against a compression spring so that it can be deflected axially during the clamping process.

[0045] In case of an incorrect clamp, if the front lug of the clamping segment slides at the first conical part and the front clamping claw does not enter the clamping groove of the hollow shaft because the position of the hollow shaft is incorrect, when contacting the hollow shaft, the clamping segment may move backward together with the tension bolt against the force of the spring (see FIGS. 9 and 10), and there is also a way to disconnect from the force of the tension bolt.

[0046] This is of course to prevent damage to the clamping system if the adapter is not in the correct position relative to the centering mount or the tension bolt at the start of the clamping process. Therefore, the clamping system according to the invention is a fail-safe technology, and an incorrect operation does not lead to a total loss of the clamping system.

[0047] Further advantages and advantageous embodiments of the invention can be seen in the following drawings, their descriptions and the claims. All features disclosed in the drawings, their descriptions and the claims may be essential to the invention, individually and in any combination with each other.

Brief Description of the Drawings

[0048]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

DETAILED DESCRIPTION OF THE INVENTION

[0049] The adapter 1 to be clamped is inserted manually or automatically into the centering mount 3.

[0050] For the purposes of the present invention, the term "adapter" is used as a general term for all components or assemblies that can be tensioned at the centering mount 3 with the aid of the clamping system according to the present invention. This can include tools, tool holders (drill chucks), devices or pallets for clamping workpieces, and many others.

[0051] FIG. 1 shows a first exemplary embodiment of a clamping system according to the present invention, in an open position or with self-locking in the open position. FIG. 5 shows the same clamping system in the clamped position with self-locking.

[0052] Figures 2 to 4 show the intermediate positions of the clamping device and explain the operation of the clamping device. When the clamping system is released from the clamping position in the self-lock shown in Figure 5, it passes through the positions shown in Figures 4 to 1, that is, in the reverse order to the case of clamping.

[0053] In all the figures, the same reference numerals are used for the same components. For clarity, not all reference numerals are given in each figure.

[0054] Figure 1 shows the adapter 1 to be clamped. It is not part of the clamping system according to the present invention. Rather, tension is applied thereto by the centering mount 3.

[0055] In the exemplary embodiment shown in Figures 1 to 5, the centering mount 3 is a separate part inserted into the spindle 37.

[0056] The adapter 1 includes a hollow shaft 5 that cooperates with the clamping device according to the present invention. For this purpose, the hollow shaft 5 has a clamping groove 7 and an end face 9.

[0057] The hollow shaft 5 is usually embedded in the centering mount 3. Because in a machine tool, the hollow shaft 5 of the adapter 1 and the centering mount 3 cooperate axially and radially without clearance. The requirements for the concentricity and axial runout of the adapter 1, as well as the torque that can be transmitted between the centering mount 3 and the hollow shaft 5, are becoming increasingly strict. The hollow shaft 5 and the centering mount 3 can be designed, for example, in accordance with ISO 12164 or ISO 26623. However, other designs without a centering effect are also possible. The centering mount is not necessary, for example, when a plurality of clamping systems according to the present invention are used in a workpiece clamping device to clamp a workpiece with the device.

[0058] In the figure, as the centering mount 3, the "polygonal taper interface with a flange contact surface" according to ISO26623 (Capto) is used as an example. As shown in the figure, the centering mount 3 can be an additional or separate component that is accommodated by or within adjacent components (such as a housing, a rotating spindle, a fixed work clamping device, etc.).

[0059] However, the centering mount 3 can also be integrated with any of the "adjacent components". In this case, the adjacent component and the centering mount are designed as a single unit. A corresponding exemplary embodiment of the embodiment is shown in FIG. 6. This design requires less radial installation space. Therefore, it is often used for rotating or passive spindles. The description of the figure related to FIG. 6 also explains the meaning in terms of design.

[0060] The following FIGS. 1 to 5 illustrate and explain the tensioning process at various stages.

[0061] First, FIG. 7 shows the tension bolt 13 according to the present invention. In this exemplary embodiment, a piston 15 that is part of the cylinder assembly is connected to the tension bolt 13. In this figure, the functional surfaces according to the present invention are clearly visible and marked with reference numerals.

[0062] These are: 101: The first cylindrical part; 103: The first conical part; 105: The second cylindrical part; 107: The second conical part; 109: The third conical part; 111: The third cylindrical part.

[0063] There may be a diameter change between the second cylindrical part 105 and the second conical part 107.

[0064] The front end FE and the rear end RE are also shown. "Front" is the area of the centering mount 3 (see Fig. 1), and the third cylindrical part 111 (see Figs. 7 and 1) is located at the rear end RE of the tension bolt 13 in the terms of the figure description and is "rear".

[0065] The functional surfaces 101 to 111 of the tension bolt 13 shown in Fig. 7 act together with the corresponding contact surfaces on the "inside" of the clamp segment. These are shown in Fig. 8 and are designated as follows.

[0066] The first contact surface 121 and the second contact surface 123 form the front lug 27.

[0067] The third contact surface 129 and the fourth contact surface 131 form the rear lug 29.

[0068] One (here, two parts) transition part 125 is not a functional surface in this sense. It creates the necessary clearance for the second conical part 107 of the tension bolt 13.

[0069] On the outside of the clamp segment 25, a front clamp claw 31 and a rear clamp claw 41 are formed. The rear clamp claw 41 is substantially formed as a fifth contact surface 133 in the shape of a frustum of a cone or a cone, and may also be concave. The shape of the front clamp claw 31 is adapted to the shape of the clamp groove 7 in the hollow shaft 5. From the ISO standards already mentioned, for example, the designs of a radius shape and a chamfer shape are known. In particular, good positive block fitting and as low a surface pressure as possible between the front clamp claw 31 and the clamp groove 7 should be achieved when the clamping system is tensioned.

[0070] Returning to Fig. 1. For clarity, reference numerals 101 to 133 are not shown in Figs. 1 to 5. Nevertheless, such reference numerals are used in the figure description.

[0071] When the adapter 1 is inserted into the centering mount 3, the hollow shaft 5 is moved to a position defined in the direction of the stop disk 11. The stop disk 11 is attached to the tension bolt 13 or integrated with the tension bolt 13 (one-piece design). FIGS. 6 and 11 show exemplary embodiments of a two-piece design.

[0072] The stop disk 11 represents a depth stop, and thus, in other words, ensures that the adapter 1 takes a defined position axially with respect to the adapter 1 or the hollow shaft 5 before the clamping process starts. This is done by bringing the base 19 of the hollow shaft 5 into contact with the stop disk 11. The relationship between the clamping groove 7 of the hollow shaft 5 and the pre-clamping claw 31 of the clamping segment 25 is important for automatic clamping, and only when this relationship is correct can the pre-clamping claw 31 enter the clamping groove 7 of the hollow shaft 5. For this purpose, it may be useful to adjust the stop disk to a defined position by using threads for adjustment or by machining the front part of the stop disk to a desired dimension to achieve the position.

[0073] In the case of a centering mount having a tapered and flange contact surface of the hollow shaft, the defined position is approximately 1.5 - 0.5 mm, and usually, there is an approximately 1 mm flange contact surface distance between the end face of the centering mount 3 and the flat surface 9 of the adapter 1. The size of the distance varies depending on the type of adapter.

[0074] The stop disk 11 at the end of the tension bolt 13 has a large outer diameter. The "base" 19 of the hollow shaft contacts the stop disk 11. Thereby, the flange contact surface of the adapter 1 is improved, and the risk of the adapter 1 tilting with respect to the centering mount 3 is reduced.

[0075] At this point (i.e., before the start of the clamping process), the tension bolt 13 must be accurately positioned in its axial position. Then, the stop disk 11 only has an accurate axial position, and thereafter, only the defined position of the above-mentioned adapter 1 can be ensured.

[0076] In this exemplary embodiment, the axial position of the tension bolt 13 is determined by its actuating means. In the figure, the actuating means is, by way of example, a combination of a piston and a cylinder (also referred to as a "cylinder assembly"), and its piston 15 is connected to the tension bolt 13 and the stop disk 11.

[0077] As shown in FIG. 1, when the piston 15 is in contact with its front-end stop 23, the tension bolt 13 and the stop disk 11 have a defined axial position.

[0078] The double-acting piston 15 for actuating the tension bolt 13 is guided in the cylinder 21 in a liquid-tight manner. Depending on which cylinder 21.1 or 21.2 is filled with pressurized fluid, the piston 15 in the cylinder 21 moves in one direction or the other. At the axial position of the piston 15 at the front-end stop 23 shown in FIG. 1, the cylinder chamber 21.2 has its maximum volume and the volume of the cylinder chamber 21.1 is minimum.

[0079] The clamping system according to the invention comprises a collet consisting of one or more clamping segments 25. The clamping segments 25 are arranged around the tension bolt 13 in a manner known per se. The clamping segments 25 may be interconnected or may exist as individual clamping segments 25.

[0080] At the front end FE, the first contact surface 121 and the second contact surface 123 form the front lug 27. At the rear end RE, the third contact surface 129 and the fourth contact surface 131 form the rear lug 29.

[0081] The front lug 27 inside the clamp segment 25 is formed so as to contact the second cylindrical portion 105 (diameter d1) of the tension bolt 13 at the position of the tension bolt 13 shown in FIG. 1.

[0082] The lug 29 inside the clamp segment 25 is formed so as to contact the third cylindrical portion 111 (diameter d2) of the tension bolt 13 at the position of the tension bolt 13 shown in FIG. 1.

[0083] In the cylindrical portions 101, 105, and 111, the tension bolt 13 is cylindrical, but a slightly tapered, concave, or convex design is also possible.

[0084] In the region of the front clamp claw 31, the outer diameter of the collet or the clamp segment 25 is very small in this exemplary embodiment, and at this position of the tension bolt 13, the hollow shaft 5 can be pushed onto the front stop disk 11 to exceed the envelope circle diameter of the subsequent front clamp claw 31.

[0085] At the rear part of the clamping system according to the present invention, the threaded ring 33 is screwed into the surrounding housing / adjacent components or the spindle housing 37. An inner conical portion 43 is formed on the threaded ring 33, and this inner conical portion cooperates with the rear clamp claw 41 or the fifth contact surface 133 of the tension bolt 13. When the rear lug 29 of the clamp segment or the plurality of segments 25 is radially outwardly moved from the third or fourth contact surfaces 129, 131 of the tension bolt 13, the inner conical portion 43 deflects such movement at the rear end RE of the clamp segment or the plurality of segments 25 into the axial movement of the clamp segment 25. In other words, in FIG. 1, when the tension bolt 13 is moved to the right, the clamp segment 25 moves to the right, that is, in the direction of the rear end RE. Due to the reliable locking fit between the front clamp claw 31 and the clamp groove 7 of the hollow shaft 5, the adapter 1 is drawn into the centering mount 3. The clamping system is under tension.

[0086] The inner diameter of the threaded ring 33 or the inner conical portion 43 is advantageously selected such that the threaded ring 33 can also slide along the envelope circle diameter of the front clamping claws. This must be possible at least at the position of the tension bolt 13 shown in FIG. 1, thereby facilitating the assembly and disassembly of the clamping system of the housing or the spindle 37.

[0087] The envelope circle diameter of the rear clamping claws 41 or the envelope circle diameter of the fifth contact surface 133 is larger than the inner diameter of the inner conical portion 43 at each position.

[0088] If, for example, due to space reasons, the threaded ring 33 cannot be used, the inner conical portion 43 is directly integrated into an adjacent component (for example, the spindle housing 37). And the clamping segment 25 is attached from the "rear".

[0089] To ensure that the collet or its clamping segment 25 always forms the minimum envelope circle diameter at this position, the clamping segment 25 must be pretensioned. This can be done by means of a tension spring 39 at the rear end RE of the collet or the clamping segment 25, or as shown in FIGS. 1 to 6, which is arranged approximately centrally with respect to the longitudinal extension of the clamping segment 25. It is also possible to connect the clamping segments 25 to each other in a spring-elastic manner to form an integral collet (without separate spring elements) (not shown).

[0090] The purpose of these embodiments is to press the clamping segments 25 together via pretensioning at the center around the tension bolt 13. It is advantageous to arrange the tension spring 39 approximately centrally on the longitudinal extension of the clamping segment 25 so that the clamping segment 25 cannot tilt and come into contact with the tension bolt 13 evenly before and after with the lugs 27 and 29.

[0091] The compression spring 45 in the rear area is supported on one hand by the end face of the compression spring sleeve 49 and is pressed against an optional intermediate disk 47 in the state shown in the figure. The intermediate disk 47, in turn, contacts the shoulder of the threaded ring 33 in a secure clamped state. Also, the intermediate disk 47 can be omitted so that the compression spring 45 directly hits the shoulder of the threaded ring 33. Also, the intermediate disk 47 or the compression spring 45 can contact the adjacent parts or the shoulder of the spindle housing 37. When such contact is provided, the compression spring 45 cannot move the clamp segment 25 further in the direction of the front end FE shown in FIG. 1 and can still apply pretension.

[0092] As already explained, the clamp segment 25 is pushed inward by the tension spring 39 and brings the tension bolt 13 into contact with the front lag 27 and the rear lag 29.

[0093] In the axial direction, the position of the clamp segment 25 is determined by the (inner) inner conical portion 43 of the threaded ring 33, the compression spring 45 or the intermediate disk 47 pretensioned by the compression spring 45, and the tension bolt 13.

[0094] In order to cause a slight pretension in the axial direction and not to cause free vibration, it may be advantageous to bring the clamp segment 25 into contact with at least one of the lags 27, 29 at the first conical portion 103 or the third conical portion 109 and obtain a slight tension with respect to the pretensioned intermediate disk 47.

[0095] When the collet consists of a plurality of clamp segments 25 separated from each other, it is useful to manufacture them such that the distance between the individual clamp segments 25 at the position where they form the minimum diameter is approximately zero. When the clamp segments 25 are separated, they are distributed approximately equally circumferentially via the tension spring 39. This ensures that when the clamping system is clamped, no or very little imbalance occurs, and no additional separation unit for evenly distributing the clamp segments 25 circumferentially is required. Nevertheless, if this is necessary (for example, in the case of a machine tool spindle driven at high speed), separation can be created as part of the intermediate disk 47, for example, by additionally connecting bars or grooves with corresponding counter-guides above or between the clamp segments.

[0096] In the specific design of FIGS. 1 to 5, the compression spring 45 is received in the compression spring sleeve 49. The compression spring sleeve 49 is received in the stepped bore 53 of the spindle 37 or the offset 51 of the adjacent part.

[0097] The offset 51 forms a longitudinal stop of the threaded ring 33 via the compression spring sleeve 49. At the same time, the compression spring sleeve 49 is held in place.

[0098] In the exemplary embodiment shown in FIG. 6, the longitudinal stop is implemented via the flange of the threaded ring 33. The flange may have a polygonal shape. The aim in each case is to ensure that as many diameters as possible are available for the cylinder 21 in the case of hydraulic actuation. And specifically, the actuating force provided by the piston 15 is maximum.

[0099] The cylinder 21 is arranged behind the compression spring sleeve 49. The compression spring sleeve 49 also serves as the front end stop 23 of the piston 15. The tension bolt 13 can also be axially moved in other ways to clamp or release the clamping system (for example, via an eccentric, a wedge, etc.).

[0100] In connection with the cylinder assembly, the necessary seals of the piston 15 and the compression spring sleeve 49 for sealing the piston rod (= the rear end of the tension bolt) are shown.

[0101] In this embodiment, the piston 15 is integrally connected or designed with, for example, the tension bolt 13. However, depending on the design, a multi-part design may also be useful. Then, the piston 15 and the tension bolt 13 are only axially connected to each other.

[0102] Figures 1 to 7 further show that the tension bolt 13 is axially inserted. The axial bore 55 (see Figure 7) of the tension bolt 13 is used as a passage for a fluid (cooling lubricant (KSS)) or a fluid-air mixture (minimum quantity lubrication). In this case, the fluid is supplied from an adjacent component (housing, spindle 37, etc.) through the working unit (cylinder 21 and piston 15) to the tension bolt 13 via a connection point.

[0103] The stop disk 11 at the front end FE of the tension bolt 13 has one or more through holes. This is where the fluid is transferred to the next component to which the fluid is to be supplied (adapter 1 in this example).

[0104] Such a transfer design can be done here as shown, without sealing, channeling, or both sealing and channeling.

[0105] With reference to Figures 2 to 5, the clamp of the self-lock clamp system according to the present invention will be described.

[0106] Figure 2 shows the clamping system in a position where the tension bolt 13 has been moved slightly to the right compared to the open position shown in Figure 1, which can be seen, for example, in the gap between the front end stop 23 and the piston 15. The tension bolt 13 has moved along the same path. The clamp segment 25 contacts the first conical portions 103 of the tension bolt 13 and their front lugs 27. That is, the clamp segment 25 is moved radially outward together with its front end. The clamp segment 25 still contacts the rear lug 29 of the third cylindrical portion 111. Therefore, the axial movement of the tension bolt 13 causes a first tilting movement of the clamp segment 25. The pivot point of the tilting movement is arranged at the rear lug 29. This increases the envelope circle diameter of the front clamp claw 31.

[0107] The first conical portions 103 have an inclination angle of 30° to 60°, preferably 45°. The clamp segment 25 has at least two-point support over a wide range in the region of the front lug 27 at the contact point with the first conical portions 103 and is formed so as not to be tiltable. In this case, the shape of the first contact surface 121 (see Figure 8) may be conical or slightly crowned conical in order to prevent pure edge support.

[0108] The front clamp claws 31 of the clamp segment 25 do not yet contact the clamp groove 7 of the hollow shaft 5.

[0109] The hollow shaft 5 is held in contact with the stop disk 11 of the tension bolt 13 by the operator of the machine, but preferably by a handling device (not shown) such as a handling robot. This means that the adapter 1 and, together with it, the hollow shaft 5 also move with the tension bolt 13 to the centering mount until the hollow shaft 5 is stationary with respect to the conical portion of the centering mount 3. And initially, it can no longer move axially. Such a first axial retraction movement reduces the distance between the flat surface 9 of the adapter 1 and the contact surface of the centering mount 3 to a few 1 / 10 mm.

[0110] However, instead of this, it is also possible to hold the adapter 1 at the starting position shown in FIG. 1. Even in this case, there is sufficient catch space between the front clamp claw 31 and the clamp groove 7 of the hollow shaft 5 for the first path described here. As a result, the front clamp claw 31 of the clamp segment 25 can enter the clamp groove 7 without being obstructive.

[0111] During such a first partial movement, the intermediate disk 47 is pressed against the end face of the threaded ring 33 by the compression spring 45 and thus remains axially stationary. If there is no intermediate disk 47, the front end of the compression spring remains in contact with the threaded ring 33.

[0112] In FIG. 3, the clamping system is shown in a position where the tension bolt 13 has moved slightly further to the right compared to the position 2 shown in FIG. 2.

[0113] In such a position, the front lug 27 continues to move outwardly along the first conical portion 103 until it reaches the first cylindrical portion 101 of the tension bolt 13. At the same time, the front clamp claw 31 of the clamp segment 25 moves outwardly into the clamp groove 7, thereby forming a reliable clamp fit capable of transmitting an axial force between the front clamp claw 31 and the clamp groove 7.

[0114] In parallel with this, at this stage of the clamping process, the rear lug 29 of the clamp segment 25 also moves outwardly along the third conical portion 109. This results in a first "large" radial stroke at the rear end of the clamp segment 25.

[0115] The third conical portion 109 preferably has an inclination angle of 45° and may be in the range of 30° to 60°. It is preferable that the inclination angles of the first conical portion 103 and the third conical portion 109 are the same. An inclination angle of 45° has also been proven to be effective for the first conical portion 103.

[0116] The rear clamping claw 41, i.e., the fifth contact surface 133 of the clamp segment 25, is always in contact with the inner conical portion 43 of the threaded ring 33. The inner conical portion 43 of the threaded ring 33 has its maximum diameter in the direction of the rear end. The conical portions 103, 107, and 109 have their maximum diameters in the direction of the front end. In other words, the inner conical portion 43 of the threaded ring 33 and the conical portions 103, 107, and 109 are oppositely oriented.

[0117] Therefore, due to the radial movement of the rear lug 29 of the third conical portion 109, a large first clamping stroke in the axial direction of the clamp segment 25, and thus the adapter 1, occurs. This is brought about by the interaction between the inner conical portion 43 of the threaded ring 33 and the fifth contact surface 133 of the clamp segment 25, and also by the interaction between the third conical portion 109 of the rear lug 29.

[0118] The inclination angle of the inner conical portion 43 in the threaded ring 33 with respect to the central axis is preferably 30° to 35°. An inclination angle from 20° to 60° is possible. By changing the inclination angle, the force-displacement conversion can be optimized.

[0119] At an inclination angle of 30° with respect to the inner conical portion 43, the conversion of the diameter change to the axial displacement of the clamp segment 25 in the region of the third conical portion 109 and (in the stage after the clamping process) the second conical portion 107 of the tension bolt 13 increases by about 1.7 times. A smaller inclination angle increases this coefficient, but at the expense of a decrease in the clamping force and an increase in the surface pressure between the clamp segment 25 and the tension bolt 13. Increasing the gradient decreases the coefficient.

[0120] The distance between the front lug 27 and the rear lug 29 is aligned such that at the end of the movement of the third conical portion 109 of the rear lug 29, the front lug 27 is located on the first cylindrical portion 101 of the tension bolt 13. As a result, the front clamping claw 31 of the clamp segment 25 is radially locked in the circumferential clamping groove 7.

[0121] If the adapter 1 is held in its initial axial position by an operator or, in principle, by a handling system (e.g., a robot), it is then pulled towards the centering mount 3 here. At this stage, the handling system for holding the adapter is no longer necessary.

[0122] When the clamping segment 25 moves axially rearward due to the retracted movement of the tension bolt 13 and the resulting clamping stroke of the adapter 1 triggered thereby, the intermediate disk 47 is pushed rearward against the force of the pre-tensioned compression spring 45. That is, as can be clearly seen in Figure 3, the stop disk is no longer pushed against the threaded ring 33.

[0123] In the next step shown in Figure 4, in a third path, the (axial) clamping force required for the tension between the hollow shaft 5 and the centering mount 3 is generated. Furthermore, self-locking of the clamping system occurs.

[0124] As the tension bolt 13 continues to move axially rearward, the front lug 27 moves the first cylindrical portion 101 of the tension bolt 13. The second and third conical portions 107, 109 of the tension bolt 13 are further drawn into the clamping segment 25.

[0125] Depending on the design of the clamping groove 7, the first cylindrical portion 101 can also be formed as a conical portion with a positive inclination angle α of an amount of 4° or less in order to further improve the relationship between the movement of the tension bolt 13 and the axial clamping movement of the clamping segment 25. However, it is also possible to form the first cylindrical portion 101 as a conical portion with a negative inclination angle α of an amount of 2° or less in order to increase self-locking in the later process of the clamping process.

[0126] In the region of the front clamping claw 31, in the illustrated exemplary embodiment, when there is a cylindrical first cylindrical portion between the front clamping claw 31 and the clamping groove 7, first there is an axial movement to the clamping position and no further axial displacement. The front region (front lug 27, front clamping claw 31) of the clamping segment 25 is regarded here as a joint.

[0127] As the tension bolt 13 continues to move, the rear lug 29 of the clamping segment 25 is no longer pushed outward by the third conical portion 109 and is pushed by the second conical portion 107.

[0128] The second conical portion 107 has a much smaller inclination angle than the third conical portion 109. The second conical portion 107 ideally has an inclination angle less than arctan(μ). "μ" is the coefficient of friction of the material pair formation between the clamping segment 25 and the tension bolt 13. In many cases (and under normal friction conditions), an inclination angle of 3° - 4° functions well. By using a (DLC) coating or targeted lubrication, such regions can or must be functionally adapted.

[0129] The inclination of the second conical portion moves the rear lug 29 of the clamping segment 25 further radially outward.

[0130] The wedging action between the rear clamping claw 41, or the fifth contact surface 133 and the inner conical portion 43 of the threaded ring 33, first results in an axial movement to the clamping position and then leads to a clamping force acting axially in the clamping segment 25, which is absorbed via the front clamping claw 31 and the clamping groove 7 and introduced into the hollow shaft 5 or the adapter 1. Such a high clamping force results in the desired axial tension between the hollow shaft 7 and the centering mount 3.

[0131] Figure 5 shows the clamping system according to the invention in a self-locking clamping position.

[0132] The actuating unit (here, a cylinder assembly having a piston 15 and a cylinder 21) can build up the necessary actuating force and disable it. In the case of a cylinder assembly, it is possible to lower the fluid pressure or reduce the pressure.

[0133] The clamping segment 25 is positively connected to the adapter 1 or its hollow shaft 5 via the front clamping claw 31 of the clamping groove 7 in a positive locking manner.

[0134] At the same time, the front lug 27 contacts the first cylindrical portion 101 of the tension bolt 13. In the radial direction, the front region of the clamping segment 25 is thus supported.

[0135] The rear clamping claw 41 of the clamping segment 25 contacts the inner conical portion 43 of the threaded ring 33. At the same time, the rear lug 29 of the collet segment 25 contacts the second conical portion 107 of the tension bolt 13.

[0136] As already explained in connection with FIG. 4, this results in a large axial clamping force on the clamping segment 25. Thus, the clamping segment 25 is loaded in a tensioned state. That is, the rear region of the clamping segment 25 tensions the front region of the clamping segment 25 via a secure clamping fit of the clamping groove 7 and thus is also pulled on the adapter 1. A desired axial tension is generated with a high clamping force between the hollow shaft 5 and the centering mount 3.

[0137] In this example, due to the conical interface between the adapter and the centering mount and even a non-circular design (ISO 26623, Capto), tensions in the axial, radial, and rotational direction components are applied. The same applies when pretensioning a system with a flange contact surface (such as ISO 26623 or ISO 12164).

[0138] However, further, due to the inclination angle of the inner cone 43, a large radial force acts on the rear clamping claw 41 and transmits them to the second conical portion 107 of the tension bolt 13 via the rear lug 29.

[0139] Since the inclination angle of the second conical portion 107 is selected to be very small according to the present invention, the tension bolt 13 is fixed in such a position by the radial force transmitted to the second conical portion 107 of the tension bolt 13 by the rear lug 29. Without an external force, the tension bolt 13 cannot change its position relative to the clamp segment 25 and the adapter 1. This means that the clamping system according to the present invention is self-locking at the clamping position.

[0140] This means that the cylinder assembly can be depressurized after the clamping process is completed, and similarly, no spring is required to continuously apply an actuating force to the tension bolt 13 in the direction of the clamping position.

[0141] This is very advantageous because it is not necessary to supply pressurized hydraulic fluid to the cylinder assembly while the spindle 37 is being driven and rotating.

[0142] Supplying pressurized hydraulic oil to the cylinder assembly while the spindle 37 is rotating is very technically demanding and requires a lot of installation space.

[0143] Due to the self-locking design in the region of the second conical portion, the clamping force is maintained even if the actuating force of the cylinder assembly drops to zero.

[0144] Due to the force amplification of the clamping system according to the present invention, the clamping force is 3 to 4 times greater than the actuating force applied by the cylinder assembly in the tension direction.

[0145] Figure 6 shows a further exemplary embodiment that functionally corresponds to the first exemplary embodiment. One difference is that the centering mount 3 is not designed as a separate component, but rather it is integrated into the spindle housing 37. In this exemplary embodiment, the entire clamping system is designed to be compact so that it can be attached via the inner diameter of the centering mount 3, i.e., from the front side. This makes it possible to design the centering mount integrally with the components around the tool holder, eliminating the need for a two-piece structure.

[0146] Figures 9 and 10 show the "incorrect clamping" of the adapter 1. Based on such figures, it is explained that in such cases, which are advantageous features of the clamping system according to the present invention, it can deflect backward, thus preventing damage to the clamping system.

[0147] In Figure 9, since the adapter 1 is not fully pushed into the centering mount 3, the front clamping claw 31 cannot enter the clamping groove of the hollow shaft 5, and the movement radially outward is blocked by the hollow shaft 5.

[0148] As a result, the front lugs 27 do not reach the first cylindrical portion 101 of the tension bolt 13. They remain at the first conical portion 103 and follow the axial movement of the tension bolt 13. As a result, the clamping segment 25 presses strongly against the intermediate disk 47 so as to compress the compression spring 45. As a result, the clamping segment 25 can deflect backward in the case of incorrect clamping and is not damaged.

[0149] For clarity, reference numerals are not given in FIG. 10. In FIG. 10, the tension bolt 13 is moved further rearward compared to FIG. 9, and against the force of the compression spring 45, the front clamping claw 31 at the end of the hollow shaft 5 or the chamfer of the insertion surface of the hollow shaft 5 moves radially outward again until the clamping segment 25 is driven until the clamping segment 25 slides from the first conical portion 103 to the first cylindrical portion 101. Once this is done, the clamping segment 25 can freely slide in the first cylindrical portion 101 regardless of the movement of the tension bolt 13. The pressurization of the compression spring 45 (regardless of the presence or absence of the intermediate disk 47) pushes the clamping segment 25 in the direction of the adapter 1 and pushes the adapter 1 out of the centering mount 3.

[0150] This is done via the spring force of the compression spring 45. Other systems do not have such an incorporated emergency function. Such an emergency function is a great advantage in that, like other systems, the segment cannot sufficiently avoid the force and is either destroyed or significantly damaged by the forces present in the system.

[0151] The incorporated emergency function can effectively prevent danger and damage, especially in the case of error examples described below.

[0152] Assumption: The adapter 1 is pulled by the centering mount 3 even though the clamping segment 25 is not in the correct position, i.e., not in the clamping groove 7. This would make the system appear to be properly tensioned even though there is no tension and the adapter could potentially fall off due to machining forces. This is also prevented by the structure according to the invention in this case.

[0153] Also, discharge prevents the adapter 1 from remaining unclamped in the centering mount 3 and touching the flange contact surfaces of 1 and 3.

[0154] Such emergency discharges are particularly important because they provide direct feedback in the automatic operation as to whether the clamp has been properly performed. This is often achieved by a so-called "flange contact surface check" which checks whether the flat surface 9 of the adapter 1 is in contact with the flat surface of the centering mount 3.

[0155] FIG. 11 shows in part another exemplary embodiment and does not include the adapter 1. The lower half shows the open state and the upper half shows the closed state. This exemplary embodiment corresponds very closely to the first example of FIGS. 1 to 5 with reference to the description of the first exemplary embodiment in terms of its design and functionality. Only the reference numerals necessary to explain additional details and functions are entered.

[0156] The modification substantially involves the type of pre-tension of the clamp segment 25 in the open state. This ensures that the clamp segment 25 contacts inside their outer diameter of the tension bolt 13 (as in the first exemplary embodiment). However, here, the clamp segment 25 is loaded by the compressive force of the spring 45 in such a way that the described support occurs.

[0157] On the other hand, the compression spring 45 in the rear region is supported on the end face of the compression spring sleeve 49 and pressed against the intermediate disk 47 in the state shown in the figure. Next, the intermediate disk 47 according to this exemplary embodiment does not contact the threaded ring 33 in the open state. Rather, it is guided by the compression spring sleeve 49 and always presses the clamp segment 25. The inner diameter of the intermediate disk 47 is larger with this exemplary embodiment than in the first exemplary embodiment shown in FIGS. 1 to 6. Thereby, the stop disk 11 fits through the bore of the intermediate disk 47 here, so that it can be integrally connected to the tension bolt 13.

[0158] In detail in Y, the rear end of the clamp segment 25 is shown enlarged. As can be seen from this explanatory drawing, the clamp segment 25 has a protrusion 30 that extends axially in the region of the rear lug 29. Such a protrusion 30 has no contact with the compression spring 45 and the intermediate disk 47 in the illustrated installed state. It acts to shorten the installation length because the intermediate disk 47 is disposed above the protrusion 30 and thus the intermediate disk 47 is an assembly aid for the clamp segment 25 as they are pre-inserted through the inner diameter during assembly.

[0159] As can be seen from detail Z, the intermediate disk 47 is formed as a frustum of a cone on its side facing the clamp segment (see the angle β in detail Z). The resulting frustum of the cone has the reference numeral 142. Due to such an inclined position, the contact surface between the clamp segment 25 and the intermediate disk 47 is displaced up to the outer diameter of the intermediate disk 47 and the radially outermost point of the rear clamp claw 41 (see detail Z). Thereby, at the contact point between the rear lug 29 and the tension bolt 13, the lever arm from the contact surface to the pivot point becomes maximum. The clamp segment 25 is simultaneously pressed against the inner conical portion 43. Due to the total torque resulting around the contact point, the clamp segment 25 is always pivotally moved so as to press the front lug 27 also against the tension bolt 13. This applies not only to the end position of the tension bolt 13 shown in FIG. 11 but also to all intermediate positions not shown.

[0160] The angle β of the frustum of the cone 142 is selected to be slightly larger than the pivot angle of the clamp segment 25 between the tensioned state and the open state such that the clamp segment 25 contacts the radially outermost point of the rear clamp claw 41 at any position.

[0161] As an alternative or in addition, it is also possible to slightly chamfer the rear end of the clamping segment 25 in the region of the rear clamping jaw 41 (see angle β in detail Y). The chamfer 141 has the same effect as the frustum 142 of the intermediate disk 47 on its side facing the clamping segment 25. In many cases, this can eliminate the tension spring 39 of the first exemplary embodiment. Since the chamfer 141 of the rear clamping jaw 41 and the frustum 142 of the intermediate disk 47 have the same function, the angle β is used in the description of both examples.

[0162] An offset 48 / diameter change is formed on the tension bolt 13, which functions as a (rear) stop for the clamping segment 25. As can be clearly seen in FIG. 11, the offset 48 acts on the rear lug 29. The offset 48 ensures that the clamping segments 25 cannot be displaced axially relative to each other when the clamping segment 25 is open. For example, if the adapter 1 is inserted "obliquely" into the centering mount 3 inaccurately and thus contacts the individual clamping segments 25, they cannot be pushed back inaccurately, but rather they remain in their intended positions. To avoid tensioning of the system, the offset 48 is displaced a fraction of a millimeter rearward and usually has no contact with the clamping segment 25.

[0163] FIG. 12 shows the front end of another exemplary embodiment of the clamping segment 25. This is the design of the clamping segment 25 for the adapter 1, which has a clamping groove 7 with a circular arc-shaped cross-section. Such a clamping groove exists, for example, in a clamping system according to ISO 26623 (Coromant Capto).

[0164] The front clamping claw 31 is provided with a chamfered portion 31.1 that conforms to a chamfered portion (not shown) of the insertion chamfer of the adapter 1. In the case of an incorrect clamp, after the clamp segment 25 has been pulled rearward by the tension bolt 13, it already contacts such a chamfered portion 31.1 against the insertion chamfer of the adapter 1 and can be deflected radially outward until they can slide from the first conical portion (103) to the first cylindrical portion (101). As a result, for such a function, it is not necessary to axially pull out the entire front clamping claw 31 from the adapter 1. This has the advantage that the spring movement amount of the spring 45 can be selected to be smaller than that in the exemplary embodiment shown in FIG. 10. Nevertheless, the spring 45 can discharge the adapter 1. This shortens the required spring length, and as a result, the overall mounting length is also shortened.

[0165] The front clamping claw 31 is cylindrical where it has a maximum diameter (see 31.2). After such a short cylindrical portion 31.2, a radius 31.3 follows.

[0166] The cylindrical portion 31.2 prevents unintentional radial jamming of the clamp segment 25 between the groove base of the clamp groove 7 and the surface 101 of the tension bolt 13. Typically, the outer diameter of the radius 31.3 is turned by 1 / 10 mm to produce the cylindrical portion 31.2.

[0167] The radius 31.3 is selected to always correspond to the possible minimum radius of the clamp groove 7 of the adapter 1. This brings the contact point of the clamp segment 25 with respect to the clamp groove 7 as close as possible to the minimum diameter of the clamp groove 7. Thereby, the lever force acting on the clamp segment 25 is reduced and the force flow is improved.

[0168] Area 31.4 is designed to optimally utilize the free space of the inner contour of the adapter 1 and gently deflect the force flow at an angle γ, preferably between 10 and 20°, and at the chamfer with adjacent radii R1 and R2. This reduces the peaks of local tension, increases the fatigue strength of the clamp segment 25, and significantly reduces the risk of spontaneous component breakage due to the axial clamping force.

[0169] The chamfers 125.1 and 125.2 on the inside of the clamp segment 25 are designed to maximize the cross-section in the clamp segment 25 without contacting the tension bolt 13 in the open position (see Fig. 11 below the center line) or preventing the collapse of the clamp segment 25 into the open position. This also reduces the tension in the clamp segment 25 and increases the fatigue strength of the clamp segment 25.

Claims

Claim 1 A clamping device for a hollow shaft (5), wherein a taper of the hollow shaft having a circular or polygonal outer contour is provided with one or more clamping segments (25) and tension bolts (13) cooperating with the clamping segments (25), the clamping segments (25) having, on the outside at the front end (FE), front clamping claws (31) and, on the inside cooperating with the tension bolts (13), front lugs (27), the clamping segments (25) having, on the outside at the rear end (RE), rear clamping claws (41) and, on the inside cooperating with the tension bolts (13), rear lugs (29), in the clamping position, the front clamping claws (31) of the clamping segments (25) fitting into a clamping groove (7) of the hollow shaft (5), the rear clamping claws (41) being pressed against an inner conical portion (43), in the open position, the front clamping claws (31) either fitting or not fitting in the clamping groove (7) of the hollow shaft (5), and by axial displacement, the tension bolts (13) moving the clamping segments (25) from the clamping position to the open position and from the open position to the clamping position, the clamping segments (25) performing a first pivotal movement during the movement from the open position to the clamping position, whereby the front clamping claws (31) of the clamping segments (25) fit into the clamping groove (7) in a reliable locking manner, forming a joint by a second pivotal movement of the clamping segments (25) after the first pivotal movement, during the second pivotal movement, the rear lugs (29) of the clamping segments (25) sliding on a third conical portion (109) of the tension bolts (13) and pressing the rear clamping claws (41) of the clamping segments (25) against the inner conical portion (43) of an adjacent part or a spindle (37), axially clamping the clamping segments (25), and during further axial movement of the tension bolts (13) following the second pivotal movement, the rear lugs (29) of the clamping segments (25) sliding on a second conical portion (107) of the tension bolts (13), whereby a self-locking effect occurs between the clamping segments (25) and the tension bolts (13). A clamping device characterized by this. Claim 2 The first cylindrical portion (101), the first conical portion (103), the second cylindrical portion (105), the second conical portion (107), the third conical portion (109), and the third cylindrical portion (111) are continuously formed on the tension bolt (13) starting from the front end of the tension bolt (13). The clamping device according to claim 1, characterized in that.

3. The inclination angle of the second conical portion (107) is 5° or less than the friction angle defined as the arctangent of the reciprocal of the coefficient of friction (μ) of the pair of contact surfaces between the clamping segment (25) and the tension bolt (13). The clamping device according to claim 1 or 2, characterized in that.

4. The inclination angle of the second conical portion (107) is in the range of 3° to 5°. The clamping device according to any one of claims 1 to 3, characterized in that.

5. The inclination angle of the first conical portion (103) and / or the inclination angle of the third conical portion (109) is in the range of 30° to 60°. The clamping device according to any one of claims 2, 3, and 4, which quotes claim 2.

6. The inclination angle of the first conical portion (103) and / or the inclination angle of the third conical portion (109) is 45°. The clamping device according to claim 5, characterized in that.

7. The second conical portion (107) and the third conical portion (109) are directly connected to each other. The clamping device according to any one of claims 1 to 6, characterized in that.

8. Starting from the front end (FE), the front lug (27) of the clamping segment (25) has a first contact surface (121) that conforms to the inclination angle of the first conical portion (103) and a second contact surface (123) that conforms to the first cylindrical portion (101). The clamping device according to any one of claims 2, 3, 4, 5, and 7, which quotes claim 2.

9. The rear lug (29) of the clamping segment (25) has a third contact surface (129) that conforms to the inclination angle of the third conical portion (109). The clamping device according to any one of claims 1 to 8, characterized in that.

10. The rear lug (29) of the clamping segment (25) has a fourth contact surface (131) that conforms to the inclination angle of the second conical portion (107). The clamping device according to any one of claims 1 to 9, characterized in that.

11. The rear clamping claw (41) has a fifth contact surface (133), and the fifth contact surface (133) conforms to the inclination angle of the inner conical portion (43). The clamping device according to any one of claims 1 to 10, characterized in that.

12. The inclination angle of the inner conical portion (43) and / or the inclination angle of the fifth contact surface (133) of the clamp segment (25) is in the range of 20° to 45°. The clamping device according to claim 11, characterized in that.

13. When the clamp segments (25) cannot slide from the first conical portion (103) to the first cylindrical portion (101), they can be deflected axially. The spring-type intermediate disk (47) or directly against the compression spring, and is supported at the rear end. The clamping device according to any one of claims 2, 2 cited, claims 3 to 5, 7, and 9 to 12.

14. A stop disk (11) is provided at the front end of the tension bolt (13). The clamping device according to any one of claims 1 to 13, characterized in that.

15. The first cylindrical portion (101) has a small negative inclination angle α. The clamping device according to any one of claims 2, 2 cited, claims 3 to 5, 7, 9 to 12, and 14.

16. The intermediate disk (47) is formed into a truncated cone (142) on the side facing the clamp segment (25). The clamping device according to claim 13, characterized in that.

17. The clamp segment (25) has a chamfered portion (141) at the rear end in at least a part of the region. The clamping device according to any one of claims 13 to 16, characterized in that.

18. An offset (48) that functions as a stop for the clamp segment (25) is formed on the tension bolt (13). The clamping device according to any one of claims 1 to 17, characterized in that.

19. The inner conical portion (43) is integrated with the adjacent part or the spindle (37), or is designed as a separate component. The clamping device according to any one of claims 1 to 18, characterized in that.

20. The clamping device is a part of a driven or fixed tool holder. The clamping device according to any one of claims 1 to 19, characterized in that.

21. 21. The clamping device according to claim 1, wherein the clamping device is used in a turret of a lathe.

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