Clamping system with self-locking for hollow shafts

Abstract

The invention relates to a clamping system with self-locking for a hollow shaft adapter.

Description

BACKGROUND

[0001] Clamping systems with a hollow shaft and a complementary shaped centering mount, such as according to ISO 12164 or ISO 26623, have proven to exist on the market for many years.

[0002] Among others, they are used for driven or stationary tool holders. The centering mount and the clamping system are then integrated in the spindle of the driven tool holder or in the housing of the tool holder. The hollow shaft is part of an adapter that carries a drill, a turning tool or other tools.

[0003] Known clamping systems for clamping such a hollow shaft comprise a collet consisting of a plurality of clamping segments. The clamping segments are arranged around a tensioning screw. The axial movement of the tensioning screw relative to the clamping segments forces them radially outward. This first leads to a fit that cooperates with the shape of the hollow shaft at the front end of the clamping segments. Further movement of the tensioning screw generates an axial clamping force, which the clamping segments exert on the hollow shaft of the adapter, so that the adapter is pulled into the centering mount. An example of such a clamping system is known from EP 2 164 662.

[0004] Such a clamping system is not self-locking. Therefore, in order to maintain the clamping force, an actuating force must constantly act on the clamping system during operation of the tool holder. Otherwise, the clamping system would loosen.

[0005] This is difficult to achieve, especially for hydraulic clamping systems in a rotating shaft of a driven tool holder. If the actuating force, and thus the clamping force, is applied by means of a spring arranged in the tool holder, this means a higher requirement for the installation space. In addition, the force required to release the clamping system is greater, as the force of the stretched spring must also be overcome.

[0006] A clamping device with self-locking is known from EP 1 924 379 B1. The clamping process is carried out by a clamping head 6, which cooperates with a clamping jaw 5 in a manner known per se. A tensioning screw 4 is mounted in front of the clamping head 6, which is moved axially by an actuating device in order to clamp or release the clamping device. Between the tensioning screw 4 and the clamping chuck 6, a two-part draw clamp 7 and a clamping sleeve 11 are provided. During tensioning, the offset 15 of the tensioning screw 4 abuts the inner collar of the draw clamp 7, so that the movement of the tensioning screw 4 is directly transmitted to the tensioning head 6 by the draw clamp 7. After a certain distance of travel of the tensioning screw, the two halves of the draw clamp 7 are deflected radially outward. This cancels the form-fit cooperation between the half shells of the draw clamp 7 and the tensioning screw.

[0007] In further progress of the clamping process, the draw clamp 7 is only slightly dragged in the axial direction, but is wedged between the conical head 12 of the tensioning screw 4 and the clamping sleeve 11, which is mounted in a manner fixed to the housing, until the desired self-locking is achieved.

[0008] The device is complex in its construction; in addition to the clamping chuck and the tensioning bolt, it also requires a two-part drawbench and a clamping sleeve 11. Furthermore, it requires a relatively large tensioning bolt stroke, requires a large amount of installation space and is expensive to manufacture.

[0009] Another clamping device with self-locking is known from DE 196 18 610 Al in the field of machine tools. The self-locking occurs at the front end of the clamping section. This self-locking is, however, not sufficient. Therefore, additional securing means are required. This additional securing means comprises a compression spring which presses a wedge-shaped section against the conical / conical portion of the tensioning bolt, so that the spring force of this compression spring generates a frictional connection to the mandrel via the wedge-shaped section. This frictional connection prevents the unintentional opening of the clamping sleeve. This solution also requires a large amount of installation space and is expensive to manufacture. Furthermore, in addition to the frictional force, the force of the compression spring must also be overcome in order to release the clamping system. This means high forces, which in turn require large cylinder assemblies, which is also disadvantageous. SUMMARY

[0010] It is an object of the present application to provide a clamping system with self-locking, which has a very compact, simple and robust construction. This compact design is particularly important in the case of little space. This is the case, for example, on a turret of a rotary center. Here, the clamping system must be able to be mounted flexibly in various positions and directions of the upright and driven tool holder. The installation space is therefore severely limited by, for example, the permissible pivot diameter, the width of the screwing surface and the interface to the rotary center.

[0011] According to the invention, in a clamping device for a hollow shaft, in particular for a hollow shaft cone having a circular or polygonal outer contour, the clamping device comprising one or more clamping segments and a tensioning screw cooperating with the clamping segments, wherein each clamping segment has a front clamping jaw on its outer side at the front end and a front lug on its inner side cooperating with the tensioning screw, wherein each clamping segment has a rear clamping jaw on its outer side at the rear end and a rear lug on its inner side cooperating with the tensioning screw, wherein in the clamped position the front clamping jaw of each clamping segment engages into a clamping groove of the hollow shaft and the rear clamping jaw is pressed against the cone, wherein in the open position one or more front clamping jaws do not engage into the clamping groove of the hollow shaft, wherein the tensioning screw moves the one or more clamping segments by axial displacement from the clamped position into the open position and from the open position into the clamped position, wherein the one or more clamping segments perform a first pivoting movement in the transition from the open position into the clamped position in order to engage the front clamping jaw of the clamping segment in a form-fit manner in the clamping groove and to form a joint for a subsequent second pivoting movement of the one or more clamping segments, wherein during the second pivoting movement the rear lug of the one or more clamping segments slides over a third cone portion of the tensioning screw and presses the rear clamping jaw of the clamping segment against the cone of the adjacent component / spindle and axially clamps the one or more clamping segments, the above object is achieved in that during a further axial movement of the tensioning screw after the second pivoting movement the rear lug of the one or more clamping segments slides over a second cone portion of the tensioning screw in order to produce a self-locking between the clamping segment and the tensioning screw.

[0012] By the mutually matched movement processes according to the invention, a form-fit connection between the front clamping jaw of the clamping segment and the clamping groove of the hollow shaft is achieved in the first pivoting movement. From that time on, this form-fit connection at the front end of the clamping segment serves as a pivot point / bearing for the one or more clamping segments. Subsequently, in the second pivoting movement, the rear end of the clamping segment is pressed radially outward against the cone of the adjacent component or spindle, thereby producing an axial clamping force. In the further movement of the tensioning screw that follows, the axial clamping force is further increased. At the same time, a self-locking effect is produced between the rear lug of the clamping segment and the second cone portion of the tensioning screw. The self-locking occurs at the rear end of the tensioning screw. In addition, this also has the positive effect that the tensioning screw is clamped and fixed at the front end and at the rear end.

[0013] According to the invention, for producing an operationally reliable self-locking effect, no additional components of the clamping system are required. Rather, the desired self-locking effect is achieved by the design of the tensioning bolt according to the invention and the matching of the same with the clamping segments and the cone. The effect resulting therefrom is that the solution according to the invention is highly compact and also highly advantageous in terms of production and costs. A further advantage is that the actuation forces for clamping and releasing are relatively small and do not differ greatly in magnitude. Naturally, the actuation force required for clamping is somewhat greater than the actuation force required for releasing.

[0014] If the clamping system is operated automatically by means of an actuator such as a hydraulic actuating cylinder assembly, the approximately equal forces for clamping and releasing are a particular advantage. The size of such an actuator is usually determined by the maximum actuation force.

[0015] A further advantage of the clamping system according to the invention is that, after the second pivoting movement, the axial tensioning of the clamping segments increases if the rear lugs of the one or more clamping segments slide over the second cone portion of the tensioning bolt, so that the hollow shaft is pulled into the adjacent component or main shaft with greater force (booster function).

[0016] In addition, in the clamping system according to the invention, the tensioning bolt is centred at its front end by the front lugs of the clamping segments in the clamping grooves of the hollow shaft and at its rear end by the rear lugs of the clamping segments in the cone. Thus, the clamping system has no or only very small unbalance. This improves the machining quality of the workpiece being machined using a tool clamped in the hollow shaft, and, in the case of a driven tool, allows machining at very high spindle speeds.

[0017] A further advantage of the clamping system according to the invention is that the shape of the front lugs and the clamping grooves can be designed relatively freely. It can be used with systems including: ISO 12164 (HSK) or ISO 26623 (CAT) Coromant (Capto).

[0018] In an advantageous embodiment of the invention, the first cylindrical portion, the first cone portion, the second cylindrical portion, the second cone portion, the third cone portion and the third cylindrical portion are formed in this order on the tensioning bolt starting from its front end VE. During the first pivoting movement, the front lugs slide over the first cone portion. During the second pivoting movement, the rear lugs slide over the third cone portion. During the pivoting movement resulting from the further axial movement of the tensioning bolt, the rear lugs slide over the second cone portion and the self-locking effect is established.

[0019] Self-locking means that, once the clamping system has been tensioned, no further actuation force needs to be applied to the tensioning bolt, which remains in its position due to the self-locking effect and still exerts a sufficiently large clamping force.

[0020] In other words: If the tensioning bolt is hydraulically actuated, the cylinder assembly actuating the tensioning bolt can be de-pressurized after tensioning without affecting the tension of the clamping system or adapter according to the invention.

[0021] This is a great advantage, especially if the clamping system is installed on a rotating main shaft and the main shaft is rotated during machining. In this case, it is not necessary to continuously apply an actuating force to maintain the clamping force as with other systems; rather, the clamping force remains in the clamping system due to the self-locking.

[0022] It is also not necessary to integrate a spring that rotates with the main shaft and permanently applies an actuating force. The disadvantage of this solution is that the spring causes an imbalance and, in addition to the frictional force, the force of the spring must 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 cone is an inner cone and can be integrated directly into the housing, an adjacent component or the main shaft. Alternatively, a threaded ring can also be provided in which the cone is incorporated. This threaded ring is then screwed into the housing, an adjacent component or the main shaft. Of course, the connection is not necessarily a threaded connection between the threaded ring and the housing. Other connections can also be used to radially center the cone and axially hold it in place in the direction of the clamping force, for example a hole-cylinder pairing that is paired with a securing ring for axial positioning.

[0024] It has proven advantageous if the angle of inclination of the second cone portion is less than 5° or less than the inverse tangent of the friction coefficient µ resulting from the pairing of the clamping segment and the contact surface of the tensioning bolt. This provides self-locking in a simple and very safe manner. Of course, when determining the friction coefficient and the angle of inclination of the second cone portion, it is also advisable to take into account the influence of the fluid (e.g. oil or cooling lubricant), the surface finish, the material pairing, possible coatings and additional protection measures against loosening caused by vibrations. If this is also taken into account, self-locking can be ensured under all conditions occurring during operation.

[0025] In many cases, it has proven sufficient or advantageous if the angle of inclination of the second cone portion is in the range between 3° and 5°. 4° has proven to be a very good value.

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

[0027] Using the tensioning bolt according to the invention, the second and third conical portions are configured to transition to each other without a change in diameter and without a cylindrical intermediate portion. This minimizes the clamping stroke required for the tensioning bolt. The transition between the two conical portions is uninterrupted.

[0028] The front lug of the clamping section has a first contact surface (starting from the front end) that matches the inclination angle of the first conical portion of the tensioning bolt and a second contact surface that matches the cylindrical portion. This ideally controls the first pivoting movement, during which the front jaws of the clamping section enter the clamping groove of the hollow shaft.

[0029] In this connection, "matching" means that the contact surface between the lug of the clamping section and the tensioning bolt is as large as possible at different positions of the tensioning bolt relative to the clamping section, without high-load edge support, in order to reduce surface pressure and wear. Therefore, the tilt angles are essentially the same.

[0030] However, for example, the contact surface can also be slightly raised or barrel-shaped to prevent edge bracing that might result from the pivoting movement of the clamping section. Similarly, the cylindrical portion of the tensioning bolt can be designed to be slightly barrel-shaped.

[0031] To increase the self-locking effect of the clamping system according to the invention, it may be advantageous to design the first cylindrical portion as a cone with a small negative tilt angle α.

[0032] The tilt angle α of the first cylindrical section can be positive or negative. Although this results in a linguistic “imprecision,” when the first cylindrical section has a small tilt angle, it is strictly speaking also referred to as the fourth conical section.

[0033] The tilt angle α can be equal to or less than 4°. For a negative tilt angle α, it is less than the tilt angle of the second conical portion on the tensioning bolt. A positive tilt angle α can increase the clamping stroke, and like the second conical portion, the tilt angle can be less than the arctan of the coefficient of friction µ.

[0034] In the case of a negative tilt angle α, the cone at the front end of the tensioning bolt (= the first cylindrical portion) is oriented in the same direction as the cone in the threaded ring; it is opposite to the second and third conical portions of the tensioning bolt. Figure 8 The negative tilt angle α is shown in the figure.

[0035] Therefore, in the case of a negative tilt angle α, the cone at the front end of the tension bolt (= the first cylindrical part) and the cone in the threaded ring point in opposite directions; for example, for HSK, a positive tilt angle can be useful to increase the clamping stroke because the clamping groove there is designed to be wedge-shaped.

[0036] Self-locking means that by design measures the tensioning bolt is prevented from moving from the clamping position to the open position due to unbalance, vibrations, pressure surges of the cooling lubricant or other external forces that can act on it during operation. This would be a movement in the direction of the centring mount.

[0037] Due to the optional negative inclination angle a, the radial force acting from the front lug of the clamping segment on the first cylinder part generates an axial force on the tensioning bolt in the direction of the clamping position.

[0038] In a further advantageous embodiment, the rear lug of the clamping segment has a third contact surface matching the inclination angle of the third cone part and a fourth contact surface at its rear end matching the second cone part.

[0039] This means that initially the second pivoting movement is controlled by the third cone part of the tensioning bolt.

[0040] Subsequently, after having achieved most of the radial travel and a certain, still often insufficient, clamping force, a further tensioning takes place between the tensioning bolt and the rear lug of the clamping segment and between the rear jaw of the clamping segment and the fifth contact surface of the cone in the threaded ring or the spindle housing. The rear lug of the clamping segment slides over the second cone part. The inclination angle of the second cone part is significantly smaller than the inclination angle of the third cone part. This reduces the deceleration ratio between the axial movement of the tensioning bolt and the pivoting movement of the clamping segment at its rear end; i.e. the same axial movement of the tensioning bolt leads to a smaller radial movement of the clamping segment. As a result, the axial clamping force of the clamping segment and thus the axial force or clamping force acting on the hollow shaft increases (assuming constant axial force of the tensioning bolt) (booster function). In other words, although the displacement force acting on the tensioning bolt is relatively small, the required clamping force is achieved, so that the clamping segment pulls the adapter into the centring mount with great force.

[0041] Due to the small inclination angle of the second cone part, a relatively large radial force is generated, which is safely transmitted via the large contact surface between the second cone part of the tensioning bolt and the fourth contact surface on the rear lug of the clamping segment and does not overload the assembly.

[0042] This makes the solution according to the application very robust, which wears little or not at all, and the surface pressure between the lugs and the second cone part of the tensioning bolt remains within permissible values.

[0043] The inclination angle of the fifth contact surface on the rear jaw of the clamping segment and the cone in the threaded ring or the housing preferably is in the range of 20° to 45°. An inclination angle in the range of 25° to 40°, in particular 30° or 35°, has proven to be very suitable.

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

[0045] In the case of incorrect clamping, if the front lugs of the clamping segment slide over the first conical portion and the front clamping jaw cannot enter the clamping groove of the hollow shaft due to incorrect positioning of the hollow shaft, the clamping segment can be moved backwards together with the tensioning bolt against the force of the spring (see Figure 9 and 10 ) and is also decoupled in some way from the force on the tensioning bolt.

[0046] If the adapter is not in the correct position relative to the centring mount or the tensioning bolt at the start of the clamping process, which is of course undesirable, this prevents damage to the clamping system. The clamping system according to the application is therefore also fault-tolerant and a fault does not lead to complete loss of the clamping system.

[0047] Further advantages and advantageous embodiments of the application can be seen in the following figures, the description of the figures. All features disclosed in the figures, the description of the figures, are essential to the application, whether alone or in any combination with one another. BRIEF DESCRIPTION OF DRAWINGS

[0048] Reference is made to Figures 1 to 5 a first exemplary embodiment of the application in various positions is shown in longitudinal section;

[0049] Figure 6 a further exemplary embodiment of the application is shown;

[0050] Figure 7 a longitudinal section of a tensioning bolt according to the application is shown;

[0051] Figure 8 a longitudinal section of a clamping segment according to the application is shown;

[0052] Figure 9 and 10 incorrect clamping of the adapter at different positions is shown;

[0053] Figure 11 a further exemplary embodiment of the application is shown; and

[0054] Figure 12 a further exemplary embodiment of the front of a clamping segment according to the application is shown in longitudinal section. DETAILED DESCRIPTION

[0055] The adapter 1 to be clamped is inserted manually or automatically into the centring mount 3.

[0056] In connection with the present application, the term "adapter" is used as a general term for all components or assemblies that can be tensioned in the centering mount 3 by means of the clamping system according to the application. This can be tools, tool holders (drill chucks), devices or pallets for clamping workpieces and others.

[0057] Figure 1 A first exemplary embodiment of the clamping system with self-locking in the open or released position is shown.

[0058] Figure 5 The same clamping system in the clamped position with self-locking is shown.

[0059] Figures 2 to 4 Intermediate positions of the clamping system are shown with which the operation of the clamping system is explained. When releasing the clamping system, the Figure 5 Starting from the clamped position with self-locking shown, the Figures 4 to 1 the positions shown, i.e. in the reverse order to the clamping.

[0060] In all figures, the same reference signs are used for the same components. For the sake of clarity, not all reference signs are marked on each figure.

[0061] Figure 1 An adapter 1 to be clamped is shown. It is not part of the clamping system according to the application, but is tensioned in the centering mount 3 by the clamping system.

[0062] In the exemplary embodiment shown in Figures 1 to 5 The centering mount 3 is a separate assembly that is inserted into the main shaft 37.

[0063] The adapter 1 comprises a hollow shaft 5 that cooperates with the clamping device according to the application. For this purpose, the hollow shaft 5 has a clamping groove 7 and an end face 9.

[0064] The hollow shaft 5 is usually immersed in the centering mount 3, since the hollow shaft 5 of the adapter 1 and the centering mount 3 in the machine tool cooperate in a gapless manner axially and radially. The requirements for the concentricity and axial run-out of the adapter 1 and the torque that can be transmitted between the centering mount 3 and the hollow shaft 5 become more and more stringent. 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 centering effect are also possible. For example, if several clamping systems according to the application are used in a workpiece clamping device to clamp a workpiece in this device, a centering mount is not necessary.

[0065] In the drawings, as an example, a "polygonal conical interface with flanged contact surface" according to ISO 26623 (Capto) is used as centering mount 3. As shown, the centering mount 3 can be an additional or separate component that is accommodated by or in an adjacent component (housing, rotating main shaft, stationary workpiece clamping device, etc.).

[0066] However, the centering mount 3 can also be integrated in one of the "adjacent components". In this case, the adjacent component and the centering mount are designed as one piece. A respective exemplary embodiment is shown in Figure 6 . This design requires less radial installation space. Therefore, it is typically used for rotating or driven main shafts. Figure 6 The related drawings description also describes the design implications.

[0067] The following Figures 1 to 5 illustrates and explains the different stages of the tensioning process.

[0068] First, Figure 7 a tensioning bolt 13 according to the invention is shown. In this exemplary embodiment, a piston 15 that is part of a cylinder assembly is connected to the tensioning bolt 13. In this drawing, the functional surfaces according to the invention are clearly visible and labeled with reference numerals.

[0069] These reference numerals are:

[0070] 101 : first cylindrical portion;

[0071] 103 : first conical portion;

[0072] 105 : second cylindrical portion;

[0073] 107 : second conical portion;

[0074] 109 : third conical portion; and

[0075] 111 : third cylindrical portion.

[0076] Between the second cylindrical portion 105 and the second conical portion 107, a diameter change can exist.

[0077] Also shown are a front end VE and a rear end HE. "Front" is the area of the centering mount 3 (see Figure 1 ) that is located at the front end VE; this is the "front". The third cylindrical portion 111 (see Figure 7 and 1 ) is located at the rear end HE of the tensioning bolt 13 in the terminology of the drawings description; this is the "rear".

[0078] Figure 7The functional surfaces 101 to 111 of the tensioning bolt 13 shown act together with corresponding contact surfaces on the "inner side" of the clamping segment. They are as follows Figure 8 are shown and designated as follows:

[0079] The first contact surface 121 and the second contact surface 123 form the front lug 27.

[0080] The third contact surface 129 and the fourth contact surface 131 form the rear lug 29.

[0081] In this sense, the (here, two-part) transition 125 is not a functional surface. It creates the gap required for the second conical portion 107 of the tensioning bolt 13.

[0082] The front clamping jaw 31 and the rear clamping jaw 41 are formed on the outer side of the clamping segment 25. The rear clamping jaw 41 is essentially formed as a fifth contact surface 133 which is frustoconical or conical in shape and can also be concave in shape. The shape of the front clamping jaw 31 matches the shape of the clamping groove 7 in the hollow shaft 5. For example, from the already mentioned ISO standards, radius-shaped and bevel-shaped designs are known. In particular, a good form-fit fit and the lowest possible surface pressure between the front clamping jaw 31 and the clamping groove 7 should be achieved if the clamping system is tensioned.

[0083] Back to Figure 1 : For the sake of clarity, the reference signs 101 to 133 are not shown in Figures 1 to 5 . However, these reference signs are used in the description of the figures.

[0084] When the adapter 1 is inserted into the centering mount 3, the hollow shaft 5 is moved into a defined position in the direction of the stop disc 11. The stop disc 11 is attached to the tensioning bolt 13 or integrated into the tensioning bolt 13 (one-piece design). Figure 6 and Figure 11 show an example embodiment of the one-piece design.

[0085] The stop disc 11 can represent a depth stop for the adapter 1 or the hollow shaft 5 and ensures that the adapter 1 is in a defined position in the axial direction before the clamping process begins. This is achieved by bringing the base 19 of the hollow shaft 5 into contact with the stop disc 11. The relationship of the clamping groove 7 of the hollow shaft 5 and the front clamping jaw 31 of the clamping segment 25 or segments 25 is important for automatic clamping. Only when this relationship is correct can the front clamping jaw 31 enter the clamping groove 7 of the hollow shaft 5. For this purpose, it can be useful to adjust the stop disc to a defined position by using a thread for adjustment or by machining the front of the stop disc to the desired size for achieving this position.

[0086] For centering mounts with a hollow shaft cone and a flange contact surface, the defined position is at approximately 1.5 mm to 0.5 mm between the end face of the centering mount 3 and the flat surface 9 of the adapter 1, typically at approximately 1 mm of flange contact surface distance. The size of the distance depends on the type of adapter.

[0087] The stop disc 11 at the end of the tension bolt 13 has a large outer diameter. The "base" 19 of the hollow shaft is in contact with the stop disc 11. This improves the flange contact surface of the adapter 1 and reduces the risk of tilting of the adapter 1 relative to the centering mount 3.

[0088] At this point, i.e. before starting the clamping process, the tension bolt 13 must be precisely positioned in its axial position. Only then does the stop disc 11 have a precise position in the axial direction and only then can the defined position of the adapter 1 described above be ensured.

[0089] In the exemplary embodiment, the axial position of the tension bolt 13 is determined by its actuation device. In the drawing, as an example, the actuation device is a piston-cylinder combination (also referred to as "cylinder assembly"), the piston 15 of which is connected to the tension bolt 13 and the stop disc 11.

[0090] As Figure 1 is shown, the tension bolt 13 and the stop disc 11 have a defined axial position if the piston 15 is in contact with its front end stop 23.

[0091] The double-acting piston 15, which actuates the tension bolt 13, is guided into the cylinder 21 in a fluid-tight manner. Depending on which cylinder chamber 21.1 or 21.2 is filled with pressurized fluid, the piston 15 in the cylinder 21 moves in one direction or the other. In the axial position of the piston 15 at the front end stop 23 shown, the cylinder chamber 21.2 has its maximum volume; the volume of the cylinder chamber 21.1 is minimal. Figure 1

[0092] 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 can be interconnected or can exist as individual clamping segments 25.

[0093] At the front end VE, the first contact surface 121 and the second contact surface 123 form a front lug 27. At the rear end HE, the third contact surface 129 and the fourth contact surface 131 form a rear lug 29.

[0094] The lugs 27 inside the clamping segments 25 are formed to abut against the second cylindrical portion 105 (diameter dl) of the tension bolt 13 in the position of the tension bolt 13 shown. Figure 1 ​​

[0095] The lugs 29 inside the clamping segments 25 are formed to abut against the third cylindrical portion 111 (diameter d2) of the tensioning bolt 13 in the position of the tensioning bolt 13 shown. Figure 1 The lugs 29 inside the clamping segments 25 are formed to abut against the third cylindrical portion 111 (diameter d2) of the tensioning bolt 13 in the position of the tensioning bolt 13 shown.

[0096] In the cylindrical portions 101, 105 and 111, the tensioning bolt 13 is cylindrical. However, a slightly conical, concave or convex design is also possible.

[0097] In this exemplary embodiment, the outer diameter of the collet or clamping segments 25 in the area of the front jaw 31 is very small and in this position of the tensioning bolt 13, so that the hollow shaft 5 can be pushed through the envelope circle diameter of the front stop disk 11 and the subsequent front jaw 31.

[0098] In the rear part of the clamping system according to the application, the threaded ring 33 is screwed into the surrounding housing / adjacent component or main shaft housing 37. A cone 43 is formed on the threaded ring 33, which cooperates with the rear jaw 41 or the fifth contact surface 133 of the tensioning bolt 13. If the rear lugs 29 of one or more clamping segments 25 move radially outward from the third or fourth contact surface 129, 131 of the tensioning bolt 13, the cone 43 deflects this movement at the rear end HE of the one or more clamping segments 25 into an axial movement of the clamping segments 25. In other words, in the position shown in Figure 1 If the tensioning bolt 13 moves to the right, the clamping segments 25 move to the right, i.e. in the direction of the rear end HE. The form fit between the front jaw 31 and the clamping groove 7 of the hollow shaft 5 pulls the adapter 1 into the centring mount 3. The clamping system is tensioned.

[0099] The inner diameter of the threaded ring 33 or the cone 43 is advantageously selected in such a way that the threaded ring 33 can also be slid over the envelope circle diameter of the front jaw. This must be possible at least in the position of the tensioning bolt 13 shown. This simplifies the assembly and disassembly of the clamping system in the housing or main shaft 37. Figure 1 This is possible in the position of the tensioning bolt 13 shown. This simplifies the assembly and disassembly of the clamping system in the housing or main shaft 37.

[0100] The envelope circle diameter of the rear jaw 41 or the envelope circle diameter of the fifth contact surface 133 is larger than the inner diameter of the cone 43 in each position.

[0101] If the threaded ring 33 cannot be used (for example for reasons of space), the cone 43 is integrated directly into the adjacent component (for example the main shaft housing 37). The clamping segments 25 are then mounted from the "rear".

[0102] In order to ensure that the collet or its clamping segments 25 always form the smallest envelope circle diameter in this position, the clamping segments 25 must be pretensioned. This can be done by means of a tension spring 39 at the rear end HE of the collet or clamping segments 25 or as shown in the exemplary embodiment in the form of a spring ring 35, which is integrated into the rear jaw 41. Figures 1 to 6The arrangement of the tension spring 39 approximately in the center of the longitudinal extension of the clamping segments 25 is achieved. It is also possible to connect the clamping segments 25 to each other in a spring-elastic manner to form a one-piece chuck (without separate spring elements) (not shown).

[0103] The purpose of these embodiments is to press the clamping segments 25 together around and with the tensioning bolt 13 via pretension. It is advantageous to arrange the tension spring 39 approximately in the center of the longitudinal extension of the clamping segments 25 so that the clamping segments 25 are not tilted and do not contact the tensioning bolt 13 uniformly at the front and rear of the lugs 27 and 29.

[0104] The pressure spring 45 in the rear region is supported on the end face of the pressure spring sleeve 49 and, in the state shown in the figure, presses against the optional intermediate disc 47. The intermediate disc 47 in turn abuts the shoulder of the threaded ring 33 in a form-fit manner. It is also possible to omit the intermediate disc 47 so that the compression spring 45 rests directly against the shoulder of the threaded ring 33.

[0105] The intermediate disc 47 or the compression spring 45 can also rest against a shoulder of an adjacent component or the spindle housing 37. Given such a contact, the compression spring 45 cannot be moved further in the direction of the front end VE than Figure 1 The clamping segments 25 shown can be further pretensioned.

[0106] As described above, the clamping segments 25 are pressed inwards by the tension spring 39 and abut the tensioning bolt 13 with the front lug 27 and the rear lug 29.

[0107] In the axial direction, the position of the clamping segments 25 is determined by the (inner) cone 43 of the threaded ring 33, by the intermediate disc 47 pretensioned by the compression spring 45 or the compression spring 45 and the tensioning bolt 13.

[0108] In order to produce a slight pretension in the axial direction and not to allow free vibrations, it is advantageous for the clamping segments 25 to abut at least one of the lugs 27, 29, the first cone portion 103 or the third cone portion 109 and to achieve a slight tensioning relative to the pretensioned intermediate disc 47.

[0109] If the chuck consists of a plurality of clamping segments 25 that are separated from one another, it is useful to manufacture them in such a way that the distance between the clamping segments 25 is almost zero at the location where the clamping segments 25 form the smallest diameter. When the clamping segments 25 are moved apart, they are thus distributed approximately uniformly in the circumference by the tension spring 39. This ensures that no or only very small imbalances occur when the clamping system is clamped; no additional separating units are required to distribute the clamping segments 25 uniformly in the circumference. If additional separating units are still required, however (for example, for machine tool spindles that are driven at maximum speed), the separation can be produced, for example, by additional connecting rods or grooves and corresponding counter guides on or between the clamping segments as part of the intermediate plate 47.

[0110] In the specific design of Figures 1 to 5 the compression spring 45 is accommodated in a compression spring sleeve 49. The compression spring sleeve 49 is accommodated in an offset 51 of a stepped bore 53 in the spindle 37 or an adjacent component.

[0111] The offset 51 forms a longitudinal stop for the threaded ring 33 via the compression spring sleeve 49. At the same time, the compression spring sleeve 49 remains in place.

[0112] In the exemplary embodiment shown in Figure 6 the longitudinal stop is implemented via a flange on the threaded ring 33. The shape of the flange can be polygonal. The aim is to ensure that the gas cylinder 21 has as large a diameter as possible in the case of hydraulic actuation. The actuation force provided by the piston 15 is then at its maximum, in particular.

[0113] The gas cylinder 21 is arranged behind the compression spring sleeve 49. The compression spring sleeve 49 also serves as a front end stop 23 for the piston 15. The tensioning bolt 13 can also be moved in the axial direction in other ways in order to clamp or release the clamping system (for example, via an eccentric, a wedge, etc.).

[0114] In connection with the gas cylinder assembly, the necessary seals for sealing the piston rod (= rear end of the tensioning bolt) in the piston 15 and in the compression spring sleeve 49 are shown.

[0115] In this embodiment, the piston 15 is connected to or designed as one piece with the tensioning bolt 13, for example. However, depending on the design, a multipart design is also useful. It is therefore essential that the piston 15 and the tensioning bolt 13 are connected to one another in the axial direction.

[0116] Figures 1 to 7 It is also shown that the tensioning bolt 13 is pierced in the axial direction. An axial bore 55 (see Figure 7This is for the passage of fluid (cooling lubricant (KSS)) or fluid-air mixture (minimum amount lubrication). In this case, fluid is supplied from adjacent components (housing, spindle 37, etc.) via the connection point to the tension bolt 13 via the actuation unit (cylinder 21 and piston 15).

[0117] The stop disc 11 at the front end VE of the tension bolt 13 has one or more through holes. This is where fluid is passed to the subsequent component (in this case, adapter 1) to which fluid is to be supplied.

[0118] This transfer design can be sealed, channelized, or, as shown in this article, neither sealed nor channelized.

[0119] Reference Figures 2 to 5 The clamping mechanism of the self-locking clamping system according to the present invention will now be described.

[0120] Figure 2 It shows that it is in the same position as Figure 1 The clamping system is shown in the open position, slightly to the right of the position where the tensioning bolt 13 has been moved. This can be seen, for example, in the gap between the end stop 23 and the piston 15. The tensioning bolt 13 has traveled the same path. The clamping segments 25 contact the first conical portion 103 of the tensioning bolt 13 via their front lugs 27. That is, the front ends of the clamping segments 25 move radially outward. The clamping segments 25 still abut the third cylindrical portion 111 with their rear lugs 29. Therefore, the axial movement of the tensioning bolt 13 causes a first tilting movement of the clamping segments 25. The pivot point of the tilting movement is located at the rear lug 29. This increases the envelope diameter of the front jaw 31.

[0121] The inclination angle of the first conical portion 103 is 30° to 60°, preferably 45°. The clamping sections 25 are formed in the region of the front lug 27 in such a way that, at the contact points with the first conical portion 103, they have at least two points of support over a wide range and cannot tilt. In this case, the first contact surface 121 (see...) Figure 8 The shape can be conical or even a slightly raised conical profile to prevent purely edge support.

[0122] The front jaw 31 of the clamping section 25 has not yet come into contact with the clamping groove 7 in the hollow shaft 5.

[0123] The hollow shaft 5 is kept in contact with the stop disc 11 of the tensioning bolt 13 by a machine operator, but preferably by a handling device (not shown), such as a handling robot. This means that the adapter 1 and the hollow shaft 5 are also moved together with the tensioning bolt 13 into the centring mount until the hollow shaft 5 rests on the cone portion of the centring mount 3. It cannot then move further in axial direction initially. This first axial retraction movement reduces the distance between the flat surface 9 of the adapter 1 and the contact surface of the centring mount 3 to a few 1 / 10 mm.

[0124] However, the design also allows the adapter 1 to be held in the Figure 1 starting position shown. Even so, there is sufficient clamping space between the front jaw 31 and the clamping groove 7 of the hollow shaft 5 for the first path portion described here. This allows the front jaw 31 of the clamping segment 25 to enter the clamping groove 7 unhindered.

[0125] During this first partial movement, the intermediate disc 47 is pressed against the end face of the threaded ring 33 by the compression spring 45 and thus remains axially stationary. If there were no intermediate disc 47, the front end of the compression spring would remain in contact with the threaded ring 33.

[0126] In Figure 3 , the clamping system shown is in a position in which the tensioning bolt 13 has been moved slightly further to the right compared to Figure 2 position 2.

[0127] In this position, the front lugs 27 continue to move outwards over the first cone portion 103 until they reach the first cylindrical portion 101 of the tensioning bolt 13. At the same time, the front jaw 31 of the clamping segment 25 has moved outwards into the clamping groove 7; this forms a form-fit, force-transmitting cooperation between the front jaw 31 and the clamping groove 7.

[0128] In parallel with this, at this stage of the clamping process, the rear lugs 29 of the clamping segment 25 also move outwards over the third cone portion 109. This results in a first "large" radial travel of the rear end of the clamping segment 25.

[0129] Preferably, the third cone portion 109 has an inclination angle of 45° and can be in the range between 30° and 60°. Preferably, the inclination angles of the first cone portion 103 and the third cone portion 109 are identical. An inclination angle of 45° is also valid for the first cone portion 103.

[0130] The fifth contact surface 133 of the rear jaw 41 or clamping segment 25 is in contact with the taper 43 of the threaded ring 33 at all times. The taper 43 of the threaded ring 33 has its largest diameter in the rear end direction. The taper portions 103, 107 and 109 have their largest diameters in the front end direction. In other words, the taper 43 of the threaded ring 33 and the taper portions 103, 107 and 109 are oppositely oriented.

[0131] Therefore, the radial movement of the rear lug 29 over the third taper portion 109 results in a large first clamping stroke of the clamping segment 25 and, thus, also of the adapter 1 in axial direction. This is achieved by the interaction of the inner taper 43 of the threaded ring 33 with the fifth contact surface 133 of the clamping segment 25 and the interaction of the rear lug 29 with the third taper portion 109.

[0132] The inclination angle of the taper 43 in the threaded ring 33 with respect to the central axis is preferably 30° to 35°. An inclination angle of 20° to 60° is possible. By varying the inclination angle, the force-movement conversion can be optimized.

[0133] At an inclination angle of the taper 43 of 30°, the change in diameter in the region of the third taper portion 109 of the tensioning bolt 13 and, in the later phase of the clamping process, of the second taper portion 107 translates into an increase of the factor of the axial displacement of the clamping segment 25 of approximately 1.7. Smaller inclination angles increase this factor; however, this is at the expense of a reduction of the clamping force and an increase of the surface pressure between the clamping segment 25 and the tensioning bolt 13. Increasing the slope leads to a reduction of the factor.

[0134] The spacing between the front lug 27 and the rear lug 29 is matched such that, at the end of the travel of the rear lug 29 over the third taper portion 109, the front lug 27 is located on the first cylindrical body portion 101 of the tensioning bolt 13. As a result, the front jaw 31 of the clamping segment 25 is radially locked in the circumferential clamping groove 7.

[0135] If the adapter 1 has already been held in its initial axial position by the operator or, generally, by a handling system (e.g., a robot), it is now pulled into the centring mount 3. At this stage, the handling system is no longer required to hold the adapter.

[0136] When the clamping segment 25 moves axially back due to the retraction movement of the tensioning bolt 13 and the clamping stroke of the adapter 1 triggered thereby, the stop disc 47 is pressed back against the force of the pre-tensioned compression spring 45: that is, the stop disc no longer presses against the threaded ring 33, as Figure 3 is clearly visible in Fig. 6.

[0137] In Figure 4In the next step shown, the third path portion, generates the required (axial) clamping force between the hollow shaft 5 and the centering mount 3. In addition, a self-locking of the clamping system is also generated.

[0138] When the tensioning bolt 13 continues to move axially rearward, the front lobe 27 moves over the first cylindrical region 101 of the tensioning bolt 13. The second and third cone portions 107, 109 of the tensioning bolt 13 are further pulled into the clamping segment 25.

[0139] Depending on the design of the clamping groove 7, the first cylindrical region 101 can also be formed as a cone with a positive inclination angle a of less than or equal to 4° to further improve the relationship between the travel of the tensioning bolt 13 and the axial clamping travel of the clamping segment 25. However, it is also possible to form the first cylindrical portion 101 as a cone with a negative inclination angle a of less than or equal to 2° to increase the self-locking in the later course of the clamping process.

[0140] In the region of the front jaw 31, in the exemplary embodiment shown, there is a cylindrical first cylindrical portion between the jaw 31 and the clamping groove 7, there is first an axial movement up to the clamping position, whereupon there is no longer an axial displacement. The front region of the clamping segment 25 (front lobe 27, front jaw 31) is now considered a joint.

[0141] With continued movement of the tensioning bolt 13, the rear lobe 29 of the clamping segment 25 is no longer pushed outward by the third cone portion 109, but rather by the second cone portion 107.

[0142] The second cone portion 107 has a much smaller inclination angle than the third cone portion 109. The second cone portion 107 ideally has an inclination angle of less than the arctangent (µ). “µ” is the friction coefficient of the material pairing of the clamping segment 25 and the tensioning bolt 13. In many cases (and under normal friction conditions), an inclination angle of 3° to 4° works well. This region can or must be functionally adapted by using a (DLC) coating or targeted lubrication.

[0143] The bevel on the second cone portion causes the rear lobe 29 of the clamping segment 25 to move further radially outward.

[0144] The wedge action between the rear jaw 41 or the fifth contact surface 133 and the cone 43 of the threaded ring 33 first results in an axial movement up to the clamping position and then in a clamping force acting in the axial direction in the clamping segment 25, which is absorbed via the front jaw 31 and the clamping groove 7 and introduced into the hollow shaft 5 or the adapter 1. Such a high clamping force generates the required axial tensioning between the hollow shaft 7 and the centering mount 3.

[0145] Figure 5A clamping system according to the application is shown in a clamped position with self-locking.

[0146] The actuation unit, here a cylinder assembly with a piston 15 and a cylinder 21, has established the necessary actuation force and can now become powerless. In the case of a cylinder assembly, the fluid pressure can be reduced or de-pressurized.

[0147] The clamping segment 25 is connected to the adapter 1 or its hollow shaft 5 in a form-fit manner via the front clamping jaw 31 in the clamping groove 7.

[0148] At the same time, the front lugs 27 abut the first cylindrical portion 101 of the tensioning bolt 13. Thus, in the radial direction, the front region of the clamping segment 25 is supported.

[0149] The rear clamping jaw 41 of the clamping segment 25 abuts the inner cone 43 of the threaded ring 33. At the same time, the rear lugs 29 of the collet segment 25 abut the second conical portion 107 of the tensioning bolt 13.

[0150] As already explained in connection with Figure 4 This results in a large axial clamping force in the clamping segment 25. Thus, the clamping segment 25 is loaded in tension; that is, the rear region of the clamping segment 25 pulls the front region of the clamping segment 25 and, via the form-fit in the clamping groove 7, thus also the adapter 1. The desired axial tensioning with high clamping force occurs between the hollow shaft 5 and the centering mount 3.

[0151] In this example, since the interface between adapter and centering mount takes on a conical and even non-circular design (ISO 26623, Capto), there is a tensioning of the assembly in the axial direction, the radial direction and the rotational direction. This is also used for its pre-tensioning for systems with flange contact surfaces (e.g. ISO 26623 and ISO 12164).

[0152] However, in addition, the inclination angle of the cone 43 also results in large radial forces acting on the rear clamping jaw 41, which the rear clamping jaw 41 transmits via the rear lugs 29 to the second conical portion 107 of the tensioning bolt 13.

[0153] According to the application, since the inclination angle of the second conical portion 107 is chosen to be very small, the radial forces transmitted by the rear lugs 29 to the second conical portion 107 of the tensioning bolt 13 result in the tensioning bolt 13 being locked in this position. Without an external force, the tensioning bolt 13 cannot change its position relative to the clamping segment 25 and the adapter 1. This means that the clamping system according to the application is self-locking in the clamped position.

[0154] This means that the cylinder assembly can be de-pressurized after the clamping process has been completed; likewise, no spring is required to continuously exert an actuating force on the tensioning bolt 13 in the direction of the clamping position.

[0155] This is very advantageous because no pressurized hydraulic fluid needs to be supplied to the cylinder assembly when the spindle 37 is driven and rotated.

[0156] The supply of pressurized hydraulic fluid to the cylinder assembly while the spindle 37 is rotating is technically demanding and requires a great deal of installation space.

[0157] Due to the self-locking design in the region of the second conical portion, the initial clamping force remains constant even if the actuating force of the cylinder assembly drops to zero.

[0158] Due to the force amplification of the clamping system according to the invention, the clamping force is 3 to 4 times greater than the actuating force exerted by the cylinder assembly in the tensioning direction.

[0159] Figure 6 Another exemplary embodiment, which functionally corresponds to the first exemplary embodiment, is shown. One difference is that the centering mount 3 is not designed as a separate component; rather, the centering mount 3 is integrated into the spindle housing 37.

[0160] In this exemplary embodiment, the entire clamping system is designed compactly so that the clamping system can be installed through the inner diameter of the centering mount 3, i.e., from the front. This makes it possible to design the centering mount as a one-piece with the surrounding components of the tool holder and to dispense with a two-piece construction.

[0161] Figure 9 and Figure 10 An "incorrect clamping" of the adapter 1 is shown. The advantageous features of the clamping system according to the invention are explained on the basis of these figures, i.e., in this case, the ability to deflect rearward, thereby preventing damage to the clamping system.

[0162] In Figure 9 , the adapter 1 has not been pushed far enough into the centering mount 3 so that the front clamping jaws 31 cannot enter the clamping recess of the hollow shaft 5; their radial outward movement is impeded by the hollow shaft 5.

[0163] The front lugs 27 therefore do not reach onto the first cylindrical portion 101 of the tensioning bolt 13. They remain on the first conical portion 103 and follow the axial movement of the tensioning bolt 13. As a result, the clamping segment 25 presses with force against the intermediate disk 47 so that the clamping segment 25 compresses the compression spring 45. As a result, in the case of incorrect clamping, the clamping segment 25 can deflect rearward and is not damaged.

[0164] For the sake of clarity, Figure 10There are no attached figure labels. Figure 10 In the middle, tension bolt 13 and Figure 9 Instead of moving further backward, the clamping section 25 is driven under the force of the compression spring 45 until the front jaw 31 at the end of the hollow shaft 5 or the insertion ramp on the hollow shaft 5 moves radially outward again, so that the clamping section 25 slides from the first conical portion 103 onto the first cylindrical portion 101. Once the above process is completed, the clamping section 25 is independent of the movement of the tension bolt 13 and can slide freely on the cylindrical portion 101. The pressure of the compression spring 45 (with or without the intermediate disc 47) pushes the clamping section 25 in the direction of the adapter 1 and pushes the adapter 1 out of the centering mount 3.

[0165] This is achieved through the spring force of the compression spring 45. Other systems do not have this integrated emergency function. This emergency function is a significant advantage because in other systems, these parts cannot adequately avoid these forces and may be destroyed or severely damaged by the forces present in the system.

[0166] In addition, the integrated emergency functions can effectively prevent dangers and damages in the following error examples:

[0167] Assumption: Adapter 1 is pulled into the centering mount 3, even though the clamping section 25 is not in the correct position, i.e., not in the clamping groove 7. This would result in the system appearing properly tensioned even without tension and the adapter potentially falling out due to processing forces. The structure according to the invention also prevents this!

[0168] The pop-out mechanism also prevents adapter 1 from remaining unclamped in the centering mount 3 and prevents the flange contact surfaces of 1 and 3 from contacting each other.

[0169] This emergency ejection is particularly important because it provides direct feedback in automated operation on whether clamping has been performed correctly. This is typically achieved through a so-called "flange contact surface check," which checks whether the flat surface 9 of the adapter 1 and the flat surface of the centering mount 3 are in contact.

[0170] Figure 11 Another exemplary embodiment is shown in cross-section with adapter 1 absent. The lower half shows the released state, and the upper half shows the closed state. This exemplary embodiment largely corresponds in its design and function to... Figures 1 to 5 This is a first example, and thus reference can be made in this regard to the description of the first exemplary embodiment. Only the reference numerals necessary to explain additional details and functions are shown in the drawings.

[0171] The change here essentially involves the type of pre-tensioning of the clamping segments 25 in the released state. This ensures, as in the first exemplary embodiment, that the clamping segments 25 abut with their inner sides on the outer diameter of the tensioning bolt 13. Here, however, the clamping segments 25 are loaded by the compression force of the spring 45, so that the support takes place.

[0172] In one aspect, the compression spring 45 in the rear region is supported on the end face of the compression spring sleeve 49 and, in the state shown in the figures, presses against the intermediate disc 47. In turn, the intermediate disc 47 in this exemplary embodiment does not abut the threaded ring 33 in the open state; rather, the intermediate disc 47 is guided in the compression spring sleeve 49 and always presses against the clamping segments 25. In this exemplary embodiment, the intermediate disc 47 has an inner diameter which is greater than the inner diameter of the threaded ring 33 in the first exemplary embodiment shown. This allows the stop disc 11 to be connected in one piece with the tensioning bolt 13, since the stop disc 11 is now assembled through the hole in the intermediate disc 47. Figures 1 to 6

[0173] In detail Y, the rear end of the clamping segment 25 is shown enlarged. As can be seen from this figure, the clamping segment 25 has a protrusion 30 which extends axially in the region of the rear lugs 29. This protrusion 30 does not come into contact with the compression spring 45 and the intermediate disc 47 in the installed state shown. It serves to shorten the installation length, since the intermediate disc 47 is arranged above the protrusion 30, and at the same time the intermediate disc 47 is an assembly aid for the clamping segments 25, since these are pre-centered via the inner diameter during the assembly process.

[0174] As can be seen from detail Z, the intermediate disc 47 is formed as a truncated cone on its side facing the clamping segments (see angle β in detail Z). The resulting truncated conical surface has the reference 142. This inclined position results in a displacement of the contact surface between the clamping segment 25 and the intermediate disc 47 to the outer diameter of the intermediate disc 47 and the radially outermost point of the rear clamping jaw 41 (see detail Z). This results in a maximum lever arm from the contact surface to the pivot point at the contact point between the rear lug 29 and the tensioning bolt 13. The clamping segment 25 is simultaneously pressed against the cone 43. Due to the total torque generated around the contact point, the clamping segment 25 is always pivoted such that the front lug 27 is also pressed against the tensioning bolt 13. This applies not only to the end position of the tensioning bolt 13 shown, but also to all intermediate positions not shown. Figure 11

[0175] The angle β of the truncated conical surface 142 is chosen to be slightly greater than the pivoting angle of the clamping segment 25 between the tensioned state and the released state, so that the clamping segment 25 is in contact with the radially outermost point of the rear clamping jaw 41 in any position.

[0176] ​​Alternatively or additionally, the rear end of the clamping segment 25 can also be slightly inclined in the area of the rear jaw 41 (see angle beta of detail Y). The bevel 141 has the same effect on its side facing the clamping segment 25 as the truncated cone design 142 of the intermediate disc 47. Generally, this can eliminate the need for the tension spring 39 of the first exemplary embodiment. Since the bevel 141 of the jaw 41 and the truncated cone design 142 of the intermediate disc 47 have the same function, the angle beta is used in the description of both examples.

[0177] An offset 48 / diameter change is formed in the tension bolt 13, which serves as a (rear) stop for the clamping segments 25. From Figure 11 It is clear from the figure that the offset 48 works together with the rear lugs 29. The offset 48 ensures that the clamping segments 25 cannot be displaced in the axial direction relative to each other when opened. For example, if the adapter 1 is accidentally inserted into the centring mount 3 "at an angle" and thus comes into contact with individual or multiple clamping segments 25, these are not accidentally pushed backwards; on the contrary, they remain in the intended position. In order to avoid tensioning of the system, the offset 48 is moved a few 1 / 10 mm backwards and generally does not come into contact with the clamping segments 25.

[0178] Figure 12 The front end of another exemplary embodiment of the clamping segment 25 is shown. This is the design of the clamping segment 25 of the adapter 1 for a clamping groove 7 with a circular-arc cross section. Such a clamping groove is present, for example, in a clamping system according to ISO 26623 (Coromant Capto).

[0179] The front jaw 31 comprises a bevel 31.1 which is adapted to the insertion bevel of the adapter 1 (not shown). In the case of incorrect clamping, the clamping segments 25, after being clamped backwards by the tension bolt 13, have come to rest against the insertion bevel of the adapter 1 and can be deflected radially outwards until they can be slid from the first conical portion (103) onto the first cylindrical portion (101). As a result, in order to achieve this function, it is not necessary to pull the entire jaw 31 axially out of the adapter 1. This has the advantage that the spring travel of the spring 45 can be chosen to be smaller than Figure 10 the exemplary embodiment shown. However, the spring 45 can spring out of the adapter 1. This reduces the required spring length and thus also the overall installation length.

[0180] Where the front jaw 31 has its maximum diameter (see 31.2), the front jaw 31 is cylindrical. This short cylindrical portion 31.2 is followed by a radius 31.3.

[0181] The cylindrical portion 31.2 prevents unintentional radial jamming of the clamping segments 25 between the groove base of the clamping groove 7 and the surface 101 of the tensioning bolt 13. Typically, the outer diameter of the radius 31.3 is rotated by 1 / 10 mm to create the cylindrical portion 31.2.

[0182] The radius 31.3 is chosen in such a way that it always corresponds to the smallest possible radius of the clamping groove 7 of the adapter 1. This brings the contact point of the clamping segment(s) 25 with the clamping groove 7 as close as possible to the smallest diameter of the clamping groove 7. This reduces the lever force acting on the clamping segment 25 and improves the flow of forces.

[0183] The area 31.4 is designed to utilize the free space in the inner contour of the adapter 1 in an ideal manner and deflects the flow of forces slowly over the bevel at an angle γ, which is preferably between 10° and 20°, and the adjacent radii R1 and R2. This reduces local tension peaks, increases the fatigue strength of the clamping segment 25 and significantly reduces the risk of spontaneous component failure due to axial clamping forces.

[0184] The bevels 125.1 and 125.2 on the inner side of the clamping segment 25 are designed to maximize the cross section in the clamping segment 25 without abutting the tensioning bolt 13 in the open position (see Figure 11 , below the center line) or interfering with the folding of the clamping segment 25 into the open position. This also reduces the tension in the clamping segment 25 and increases the fatigue strength of the clamping segment 25.

Claims

1. A clamping device for a hollow shaft (5), comprising one or more clamping sections (25) and a tensioning bolt (13) cooperating with said clamping sections (25), wherein, Each clamping segment (25) has a front jaw (31) on its outer side at the front end (VE) and a front lug (27) on the inner side of each clamping segment that mates with the tensioning bolt (13). Each clamping segment (25) has a rear jaw (41) on its outer side at the rear end (HE) and a rear lug (29) on the inner side of each clamping segment that mates with the tensioning bolt (13). In the clamped position, the front jaw (31) of each clamping segment (25) engages with the clamping of the hollow shaft (5). In the groove (7) and the rear jaw (41) is pressed against the cone (43) of the adjacent component or spindle (37), wherein, in the open position, one or more front jaws (31) are not engaged in the clamping groove (7) of the hollow shaft (5), wherein the tensioning bolt (13) causes one or more clamping segments (25) to move from the clamping position to the open position and from the open position to the clamping position by axial displacement, wherein one or more clamping segments (25) are in the groove (7) and the rear jaw (41) is pressed against the cone (43) of the adjacent component or spindle (37), wherein, in the open position, one or more front jaws (31) are not engaged in the clamping groove (7) of the hollow shaft (5), wherein, the tensioning bolt (13) causes one or more clamping segments (25) to move from the clamping position to the open position and from the open position to the clamping position by axial displacement, wherein, one or more clamping segments (25) are in the groove (7) and the rear jaw (41) is pressed against the cone (43) of the adjacent component or spindle (37), wherein, in the open position, one or more front jaws (31) are not engaged in the clamping groove (7) of the hollow shaft (5), wherein, in the open position, one or more clamping segments (25) are ... A first pivoting motion is performed during the transition from the open position to the clamping position, such that the front jaws (31) of the clamping segment (25) engage in a form-fitting manner in the clamping groove (7) and form a joint for a subsequent second pivoting motion of one or more of the clamping segments (25), wherein, during the second pivoting motion, the rear lugs (29) of one or more of the clamping segments (25) slide on the third conical portion (109) of the tensioning bolt (13) and hold the clamping segment (25) in place. The rear jaw (41) of the clamping bolt (13) presses against the cone (43) of the adjacent component or spindle (37) and axially clamps one or more of the clamping segments (25), characterized in that, during a further axial movement of the tension bolt (13) after the second pivoting movement, the rear lug (29) of one or more of the clamping segments (25) slides on the second cone portion (107) of the tension bolt (13) to create a self-locking effect between the clamping segments (25) and the tension bolt (13).

2. The clamping device according to claim 1, characterized in that, 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 formed sequentially on the tensioning bolt (13) starting from the front end (VE).

3. The clamping device according to claim 2, characterized in that, The tilt angle of the second conical portion (107) is less than 5° or less than the arctangent of the paired friction coefficient of the contact surfaces of the clamping section (25) and the tensioning bolt (13).

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

5. The clamping device according to claim 2 or 3, characterized in that, The tilt angle of the first conical portion (103) and / or the tilt angle of the third conical portion (109) are in the range of 30° to 60°.

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

7. The clamping device according to any one of claims 1 to 3, characterized in that, The second conical portion (107) and the third conical portion (109) transition to each other without a change in diameter and without a cylindrical intermediate portion.

8. The clamping device according to claim 2 or 3, characterized in that, The front lug (27) of one or more of the clamping segments (25) has a first contact surface (121) that matches the inclination angle of the first conical portion (103) and a second contact surface (123) that matches the first cylindrical portion (101) starting from the front end (VE).

9. The clamping device according to any one of claims 1 to 3, characterized in that, The rear lug (29) of one or more of the clamping sections (25) has a third contact surface (129) that matches the tilt angle of the third conical portion (109).

10. The clamping device according to any one of claims 1 to 3, characterized in that, The rear lug (29) of one or more of the clamping sections (25) has a fourth contact surface (131) that matches the tilt angle of the second conical portion (107).

11. The clamping device according to any one of claims 1 to 3, characterized in that, The rear gripper (41) has a fifth contact surface (133), and the fifth contact surface (133) matches the tilt angle of the cone (43) of the adjacent component or spindle (37).

12. The clamping device according to claim 11, characterized in that, The tilt angle of the cone (43) of the adjacent component or spindle (37) and / or the tilt angle of the fifth contact surface (133) of the clamping section (25) are in the range of 20° to 45°.

13. The clamping device according to claim 11, characterized in that, The tilt angle of the cone (43) of the adjacent component or spindle (37) and / or the tilt angle of the fifth contact surface (133) of the clamping section (25) is 30° or 35°.

14. The clamping device according to claim 2 or 3, characterized in that, One or more of the clamping segments (25) are supported by their rear ends on a spring-loaded intermediate disk (47) or directly on a compression spring (45) such that the clamping segments (25) can be deflected in the axial direction if the clamping segments (25) cannot slide from the first conical portion (103) onto the first cylindrical portion (101).

15. The clamping device according to any one of claims 1 to 3, characterized in that, A stop disc (11) is provided at the front end (VE) of the tensioning bolt (13).

16. The clamping device according to claim 2 or 3, characterized in that, The first cylindrical portion (101) has a negative tilt angle α, the magnitude of which is equal to or less than 4°.

17. The clamping device according to claim 14, characterized in that, The intermediate disk (47) is formed as a truncated cone (142) on the side facing the clamping section (25).

18. The clamping device according to claim 14, characterized in that, The clamping section (25) has a ramp (141) in at least a portion of its rear end.

19. The clamping device according to any one of claims 1 to 3, characterized in that, A shoulder (48) is formed on the tensioning bolt (13), which serves as a stop for the clamping section (25).

20. The clamping device according to any one of claims 1 to 3, characterized in that, The cone (43) of the adjacent component or the spindle (37) is either integrated into the adjacent component or the spindle (37) or designed as a separate component.

21. The clamping device according to any one of claims 1 to 3, characterized in that, The clamping device is part of a driven or fixed tool holder.

22. The clamping device according to any one of claims 1 to 3, characterized in that, The clamping device is used on the turret of the lathe.

23. The clamping device according to any one of claims 1 to 3, characterized in that, The hollow shaft (5) is a hollow shaft cone with a circular or polygonal outer contour.

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