chuck

Abstract

The invention relates to a chuck, by means of which a workpiece is individually supported for machining by means of a tool and is oriented coaxially to a centering axis, which serves as a reference for machining the workpiece by means of the tool, the chuck having a chuck body, at least four jaws which are supported radially movably at the chuck body, which are arranged in pairs in the X or Y axis and by means of which the workpiece is oriented in alignment with the centering axis and is held during machining, and a pulling piston which is supported linearly movably in or at the chuck body, which is coupled in transmission with the respective jaw in such a way that the jaw is fed or moved away from the workpiece radially in the direction of the workpiece to be clamped during linear movement of the pulling piston, which is arranged coaxially to the centering axis in the interior of the chuck body and is actuated axially by one or more drive devices. Each drive device has a linearly movable piston rod or threaded spindle, the respective longitudinal axis of which is arranged perpendicular to the centering axis.

Description

Technical Field

[0001] The present invention relates to a chuck (also known as a spannfutter) according to the invention, by which a workpiece is individually supported for machining by a machine tool and is coaxially oriented with a centering axis that serves as a reference reference for machining the workpiece by the machine tool. Background Technology

[0002] For example, such a clamping device known under the technical term "clamp" can be found in DE 10 2015 204 502 B4. A wiggle and a drive are disposed between the gripper base and a mechanically operable drive unit, each being drively connected to one of the wiggle components.

[0003] The drive element is driven by a pressure piston that can move axially via a connecting ring, so that the operating force of the pressure piston acts on the drive element. The axial movement of the drive element and the connecting component generates a feed motion for the radial orientation of the gripper, since the gripper is connected to the drive element and is movably supported in a guide groove.

[0004] Since clamping a workpiece using two pairs of radially opposed jaws is a mechanical overdeterminacy, compensation is necessary during the movement of the jaws, drive mechanism, connecting components, and workpiece. Specifically, if one of the jaws in a pair contacts the workpiece to be clamped earlier, its feed motion should stop to ensure that the jaws extending perpendicularly to that pair can traverse the remaining distance between the jaws and the workpiece surface. A corresponding clamping force should only be generated when all four jaws are in contact with the workpiece surface. Therefore, the clearance serves as compensation for the jaws as they move towards the workpiece. In particular, when the workpiece has a rectangular outer contour, resulting in varying side lengths, compensation is needed for these different distances between the radially opposed jaw pairs.

[0005] However, due to the required clearance, there is often significant inaccuracy in the clamping position, resulting in errors in workpiece positioning. This, in turn, leads to machining errors in the workpiece itself, as the clamping repeatability of a large number of identical workpieces cannot be guaranteed.

[0006] However, this potential for movement in the clamping action is often associated with significant tolerance deviations, making it impossible to accurately predict or predetermine the required clamping force. The presence of movement gaps between components arranged in the force flow results in relative movement between these components.

[0007] The patent applicant recognized these drawbacks and eliminated them through its own development, as described in EP 3 623085 A1. The chuck shown there has a disc body with a rocker arm positioned between two adjacent jaws. This rocker arm compensates for the movement between the two jaws, particularly when one jaw makes contact with the workpiece to be clamped in space or time before the other. The axial feed motion of the drive is transmitted to the corresponding jaws via corresponding helical teeth, ramps, or gripping hooks. However, the workpiece to be clamped may have a rectangular or other cross-sectional profile, such that the two opposing jaws make contact with the workpiece before the jaws arranged perpendicular to the two opposing jaws. Alternatively, the workpiece may not initially be coaxially oriented with a centering axis used as a reference, and the workpiece is positioned by the feed motion of four jaws driven synchronously to each other.

[0008] In the arrangement according to the aforementioned patent application, a disadvantage is that the drive unit is coaxially oriented with the longitudinal axis of the chuck, thus requiring significant structural space, which is directly located within the machine tool's working area. The chuck is typically fixed to the pallet or worktable, and the workpiece to be machined is pre-assembled in the chuck. The chuck's positioning relative to the machine tool's reference datum is precisely preset and can be correspondingly repeatably precise during chuck loading and unloading. Therefore, once the workpiece is coaxially oriented with the longitudinal axis of the chuck by the four jaws, it is also coaxially oriented with the machine tool's centering axis, which typically corresponds to the longitudinal axis of the chuck. However, the pressure piston is positioned directly below the machining plane.

[0009] However, what is often required is that the space in the working area of ​​the machine tool is not available for this arrangement of the drive unit.

[0010] Furthermore, in the prior art, the compensating motion between two adjacent grippers, which is set in the form of compensating motion, cannot be directly transmitted to other grippers. Summary of the Invention

[0011] Therefore, the object of the present invention is to further improve the type of chuck mentioned at the beginning, such that, on the one hand, the compensating motion between two adjacent and mutually perpendicular jaws is compensated independently of their feed motion and their action contact with the workpiece to be clamped, and on the other hand, the structural height dimension of such chuck is designed to be as small as possible.

[0012] This task is solved according to the present invention.

[0013] Further advantageous improvements to the invention are derived herein.

[0014] By equipping each drive unit with a linearly movable piston rod or threaded spindle, the corresponding longitudinal axis of which is arranged perpendicular to the centering axis, an extremely low structural height is achieved for this type of chuck. This is because the drive unit extends substantially within the plane formed by the chuck body, thus the structural height parallel to the centering axis is unaffected by the spatial extension of the drive unit. In other words, the length of the corresponding drive unit has no impact on the structural height of the chuck, even if the length of the drive unit is designed to protrude beyond the outer edge of the chuck body.

[0015] The spatial extension of the drive unit and the required axial movement thus extend in the horizontal plane, so that the structural height of the chuck is advantageously unaffected by the arrangement of the drive unit, since the drive unit can protrude beyond the outer side of the drive unit, and therefore no structural space parallel to the longitudinal axis of the chuck is required.

[0016] Due to structural measures, the axial movement of the drive unit is redirected or transmitted to the grippers in such a way that the axial movement moves synchronously radially toward the workpiece to be clamped, and the clamping process can be introduced simultaneously for all existing grippers. Specifically, the grippers are connected to at least one drive unit via helical teeth or wedge-shaped hooks. Therefore, the axial movement of the drive unit is converted within the disc body into the radial feed and clamping motion of the chuck.

[0017] If multiple drive mechanisms exist for the corresponding movements of the grippers, these drive mechanisms are coordinated with each other by means of a synchronizing ring to ensure that not only the operating force of the drive mechanisms but also their movement speed is perfectly matched, thus directly affecting all existing grippers. The synchronizing ring is rotatably supported within the disc body about its longitudinal axis, thereby converting the axial movement of the drive mechanisms into the rotational movement of the synchronizing ring.

[0018] To achieve a common connection between the respective drive unit and the synchronizing ring, a tooth is provided on the outer side of the synchronizing ring for each drive unit. This tooth engages with the tooth associated with the respective drive unit, thereby providing a form-fitting functional connection between the respective drive unit and the synchronizing ring. The existing drive unit and synchronizing ring thus form a transmission mechanism for synchronizing feed force, feed speed, and coordinating the required clamping force.

[0019] Furthermore, it is often necessary to coordinate the clamping movements of the jaws. That is, if clamping a workpiece whose cross-sectional shape is not rotationally symmetrical (and thus, for example, a rectangular workpiece), two of the opposing jaws will contact the outer side of the workpiece before the two jaws perpendicular to them. Therefore, the feed movement of the first pair of jaws must be stopped, more precisely, until the second pair of jaws contacts the workpiece. This compensating movement can be achieved by connecting two adjacent jaws via a rocker arm. The rocker arm is here oscillatingly supported on the disc about a support pin. Once one of the two jaws contacts the workpiece, a torque is generated that acts on one side of the rocker arm, causing it to oscillate inwards towards the disc. Thus, the jaw not yet positioned on the workpiece can move further radially and thus feed, while the already positioned jaw does not apply clamping force to the workpiece. Only when all jaws are simultaneously positioned on the outer side of the workpiece, i.e., in active contact with it, is a clamping force built up due to further axial movement of the drive mechanism, which is further transmitted from the jaws to the workpiece to be held.

[0020] With the aid of the compensating movement of the grippers or the rocker arm connecting the grippers, the workpiece to be clamped can be precisely coaxially oriented with the longitudinal axis of the disc body. This longitudinal axis of the disc body can be considered as the centering axis for machining the workpiece, as it serves as a reference datum for the machining machine. That is, the control program stored in the machine tool knows the position and orientation of the centering axis, and thus can perform the corresponding working steps with respect to the clamped workpiece. Attached Figure Description

[0021] The accompanying drawings illustrate an embodiment of a clamp with two drive variants, which are described in more detail below. Specifically:

[0022] Figure 1 A perspective view shows a chuck with two mechanical drives, fixed to a tool table associated with a machine tool. The chuck includes four jaws through which the workpiece to be machined is held coaxially with a centering axis.

[0023] Figure 2a The cross-sectional view shows the jaws in the open state according to... Figure 1 The clamp plate,

[0024] Figure 2b The following is shown as the basis for the clamping state of the grippers. Figure 2a The clamp plate,

[0025] Figure 3a The following is shown: The gripper is in the open state. Figure 1 The clamping disc has two drive mechanisms arranged perpendicular to the centering axis, and the four jaws move synchronously through the drive mechanisms.

[0026] Figure 3b The following is shown as the basis for the clamping state of the grippers. Figure 3a The clamp plate,

[0027] Figure 4a The section line parallel to the X-axis is shown according to... Figure 1 The clamp plate,

[0028] Figure 4b The section line parallel to the Y-axis is shown according to... Figure 1 The clamp plate,

[0029] Figure 5 A top view showing the plane formed by the X and Y axes. Figure 1 The cutting plane,

[0030] Figure 6a The perspective view shows the open state according to Figure 1 The clamp plate,

[0031] Figure 6b The basis shown is that it is in a clamping state. Figure 6a The clamp plate,

[0032] Figure 7a The following is shown based on the horizontal state of the rocker component. Figure 6a A clamping plate with a compensating rocker arm.

[0033] Figure 7b The basis for showing the oscillating state of the rocker component. Figure 6b A clamping plate with a compensating rocker arm.

[0034] Figure 8 The exploded diagram shows the following based on Figure 1 The clamp, and

[0035] Figure 9 Showing according to Figure 1 The chuck has an electric motor as a drive device for manipulating the grippers. Detailed Implementation

[0036] exist Figure 1The diagram shows a chuck 1, which holds a workpiece 2 at a machine tool table 3' associated with a machine tool 3. The workpiece 2 can have any outer contour, particularly a rotationally symmetric, rectangular, or elliptical contour. That is, the workpiece 2 is to be machined by the machine tool 3. To achieve the most repeatable, accurate, and centered clamping position for workpieces 2 with identical structures, a centering axis 4 is defined, which in the illustrated embodiment coincides with the longitudinal axis of the chuck 1. The centering axis 4 serves as a reference datum for the machine tool 3, allowing all machining steps to be performed on the workpiece 2 from the centering axis 4. The position of the chuck 1 at the machine tool table 3' remains constant, thus the position of the chuck's centering axis 4 relative to the machine tool 3 remains constant, and if workpieces 2 with identical structures are replaced, the corresponding axes of symmetry of these workpieces extend coaxially with the centering axis 4.

[0037] Therefore, each of the workpieces 2 to be clamped should be held so that the axis of symmetry of the workpiece 2 to be processed is aligned with or coaxially oriented with the centering axis 4.

[0038] To enable the workpiece 2 to be clamped in such a centered manner, the chuck 1 is composed of a disc body 5, into which, in the illustrated embodiment, four guide grooves 20 are machined in. The guide grooves 20 are oriented toward and thus extend radially towards the centering axis 4. Furthermore, the guide grooves 20 are open upwards, allowing the jaws 6, 7, 8, or 9 to be inserted into them respectively. Each of the four jaws 6, 7, 8, 9 is movably supported in its corresponding guide groove 20, allowing each of the jaws 6, 7, 8, 9 to be fed toward or moved away from the centering axis 4. Between the guide grooves 20, the surface of the disc body 5 serves as a mounting portion 5' for the workpiece 2 to be clamped.

[0039] according to Figure 2a and 2b Different functional layers I, II, III and IV are provided inside the disk body 5, which are described in more detail below.

[0040] Functional level I is formed by a synchronization ring 21 arranged centered around the centering axis 4. The synchronization ring 21 is connected to the corresponding drive devices 12, 13 in a form-fitting manner and is rotatably supported in the disc body 5.

[0041] The third functional layer III is formed by a compensating pendulum support in the form of a swing element 18.

[0042] First, it should be done through Figure 3a 3b and 4 explain the movement of the four grippers 6, 7, 8 and 9 controlled by two drive mechanisms 12 and 13.

[0043] Since the drive units 12 and 13 are parallel to each other and arranged opposite each other about the centering axis 4, it is technically necessary to operate the drive units 12 and 13 in opposite directions in order to achieve synchronous movement of the grippers 6, 7 or 8, 9 that are connected in pairs at the drive units.

[0044] Drive units 12 and 13 are designed here as a first drive variant as hydraulically or pneumatically operated pressure pistons with corresponding lifting and pressing spaces (or stroke and pressure spaces, i.e., Hub- und Druckraum) 28, in which corresponding media can be alternately pressed in or out through corresponding valve openings A, B. The lifting-pressing space 28 is separated by a pressure plate 29, and its axial movement generates a pulling force indicated by reference numeral 30. The operation of drive units 12 and 13 is well known, thus technically possible on the premise that the operation associated with the corresponding movements of drive units 12 and 13 occurs through the pressing in and pressing out of the provided media.

[0045] Therefore, in Figure 1 The movement of the feed grippers 6, 7, 8, and 9 can be understood from 2a, 2b, 3a, and 3b. Grippers 6, 7, 8, and 9, embedded in the guide groove 20, are connected to the drive piston 10 via a wedge-shaped hook 40. A transfer plate 11 with outwardly pointing teeth 22 is fixed to the drive piston 10. These teeth are interconnected with the piston rod 26 via a connecting member 27, which is associated with the corresponding drive device 12 or 13. If the hydraulic piston, as a major component of the drive device 12 or 13, is thus operated in a corresponding manner through valve openings A and B, and the corresponding lifting and squeezing space 28 is filled with a medium or emptied, the piston rod 26 initially moves linearly in the corresponding predetermined direction. Since the connecting rod 26 is connected to the connecting component 27, and the helical tooth portion of the connecting component 27 is connected not only to the synchronizing ring 21 but also to the wedge hook connecting portion 40, the corresponding sliders 14 to 17 move radially along the centering axis 4 due to the pulling force 30 acting on the downwardly moving pulling piston 45.

[0046] Furthermore, the piston rod 26 has a longitudinal axis 26', which is oriented perpendicular to the centering axis 4. Preferably, the mounting portion 5' is perpendicular to the centering axis 4, and the longitudinal axis 26' extends parallel to the mounting portion 5'.

[0047] Since the grippers 6, 7, 8, and 9 are held radially in the guide grooves 20, and due to the helical teeth between the guide grooves and the sliders 14 to 17, a radial feed motion is generated along the centering axis 4, or the four grippers 6, 7, 8, and 9 move outward from the centering axis 4. According to FIG4, the drive piston 10 is pulled downward by the pulling force 30 by the drive devices 12 and 13, thereby causing the four grippers 6, 7, 8, and 9 to move radially in their respective guide grooves 20, corresponding to the above explanation.

[0048] If two or more drive units 12 and 13 are provided, it is advantageous for the movement of drive units 12 and 13 to be synchronized for mutual synchronization. This motion coordination between the two drive units 12 and 13 is achieved through a synchronization ring 21. Figure 5 The diagram shows the synchronizing ring 21, which has two guide grooves 41 and 42 that respectively form-fit the engaging sliders 32 and 33. Sliders 32 and 33 are associated with a connecting member 27, which is fixedly connected to the corresponding drive unit 12 or 13. Therefore, the connecting member 27 moves together with the corresponding drive unit 12 or 13, and the synchronizing ring 21 is thus a transmission mechanism for motion compensation between the two drive units 12 and 13. If one of the drive units 12 or 13 moves faster or slower due to the filling of the lifting-compression space 28, the synchronizing ring 21 compensates for this difference in speed or force between the drive units 12 and 13. Therefore, the drive piston 31 is driven by the two drive units 12 and 13 and the synchronizing ring 21 via helical teeth 22 and 23.

[0049] In addition, from Figure 7a As shown in Figure 7b, there are four compensating pendulum support members 18 inside the drive piston 10. The corresponding pendulum members 18 are rotatably or swingably connected to the drive piston 10 via support pins 19, and two corresponding adjacent grippers 6,7 or 8,9 are connected to one of the two free ends of the pendulum member 18 via sliders 14,15,16 or 17. Therefore, the drive piston 10 and the sliders 14,15,16,17 form a structural unit.

[0050] according to Figure 6a and 6bWhen two opposing jaws 6,8 or 7,9 make contact with the workpiece 2 before the two adjacent jaws 7,9 or 6,8, motion compensation should be performed. In the case of a rectangular workpiece 2, i.e., with different side lengths, the contact points of the four jaws 6,7,8,9 occur in pairs at different times. Once the first pair of jaws 6,8 makes contact with the workpiece 2, the operating force continues to be maintained or sustained by the drive devices 12,13, while the other two jaws 7 and 9 are still spaced from the surface of the workpiece 2 to be clamped, motion compensation should be achieved by the rocker arm 18. Here, the rocker arm 18 swings around the support pin 19, so that the motion stops at the jaws 6,8 placed on the workpiece 2, and the other two jaws 7,9 continue to feed along the direction of the workpiece 2. The actual clamping process is only achieved when all four jaws 6, 7, 8 and 9 are in active contact with the workpiece 2, because the oscillating motion of the rocker 18 has ended, and the workpiece 2 is held by the clamping force generated by the helical teeth between the drive unit 12, 13 and the jaws 6, 7, 8 and 9.

[0051] Due to the aforementioned compensating movement achieved between two adjacent grippers 6, 7, 8, and 9 via the corresponding rocker element 18, synchronous movement is achieved during the feeding of grippers 6 to 9. This allows not only workpieces 2 to have different side lengths, but also ensures that workpieces 2, initially asymmetrically positioned on the mounting surface 5' of the disk body 5, can be coaxially oriented with the centering axis 4. That is, the four grippers 6, 7, 8, and 9 push workpiece 2 to the center of the disk body 5, thereby causing the axis of symmetry of workpiece 2 to move and be oriented coaxially with the centering axis 4.

[0052] from Figure 7a Figures 7b to 8 show the mechanical connections between grippers 6, 7, 8, and 9, drive units 12 and 13, and the rocker arm 18. That is, once according to... Figure 7b When the rocker arm 18 swings in one direction around the support pin 19, one of the sliders 14, 15, 16 or 17 moves downstream parallel to the centering axis 5, and the corresponding feed motion of the jaws 6, 7, 8 or 9 fixed at the slider ends during this process of the rocker arm 18. The clamping force is only generated after all four jaws 6, 7, 8, 9 are against the outside of the workpiece 2 to be clamped.

[0053] The four functional levels I, II, III, and IV can be distinguished from each other as follows. Functional level I includes the operative connection of the drive between the synchronization ring 21 and the corresponding drive devices 12 and 13. Sliders 32 and 33, which are inserted into the connecting member 27, are shaped to connect with the synchronization ring 21. This operative connection ensures that not only the operating force of the drive devices 12 and 13 but also the speed of movement of the drive devices are perfectly matched.

[0054] Functional level II is formed by an integrally machined helical tooth 22 at the connecting member 27, which is operatively connected to the synchronizing ring 21. Due to the opposing linear movements of the drive units 12 and 13, the teeth 22 engaged in the helical tooth 22 at the corresponding connecting member 27 with the drive piston 10 or the transmission plate 11 create an operative connection for the axial upward or downward movement of the drive piston 10. The drive piston 10 is here locked to prevent twisting in the guide grooves 43 and 44.

[0055] Functional level III relates to a compensation mechanism in the form of a rocker arm 18 and its associated components located inside the drive piston 10. The free ends of the rocker arm 18 are connected to the free ends of sliders 14 to 17 via transmission pins 34 and 35, respectively, which are rotatably mounted around heads 36 and 35 at the rocker arm 18. There are a total of four rocker arms 18, each rotatably or swingably supported in the drive piston 10 via support pins 19. Slider arms 14, 15, 16, and 17 are fixed at both ends of the rocker arm 18. By swinging the rocker arm 18 to one side, sliders 14, 15, 16, and 17 move axially up and down. The connection between the rocker arm 18 and sliders 14, 15 or 16 and 17 produces paired, synchronized up and down movements of sliders 14, 15, 16, and 17. Therefore, opposing sliders 14 and 16 or 15 and 17 move synchronously. Thus, the structural unit for driving piston 10 is formed by pull piston 45, rocker element 18, support pin 19, and sliders 14, 15, 16, and 17.

[0056] Functional level IV is formed by the operation of grippers 6, 7, 8, and 9, which are interconnected via wedge-shaped hooks 40, and sliders 14, 15, 16, and 17. The axial movement of sliders 14, 15, 16, and 17 generates radial, feedable, or movable-away movement of grippers 6, 7, 8, and 9 about the centering axis 4.

[0057] Another drive variant for the motion of grippers 6, 7, 8, and 9 can be found in... Figure 9 As can be seen from the figure, the pressure piston is replaced by an electric motor 54. The driving device is identified by reference numerals 52 and 53. The corresponding electric motor 54 can move in two angular directions, namely clockwise and counterclockwise.

[0058] A corresponding electric motor 54 is movable via a threaded spindle 55, which is rotatably held in a spindle bearing 57 in a manner rotatable about its longitudinal axis 55'. The spindle bearing 57 is housed within a disc body 5. Therefore, the threaded spindle 55 can only rotate about its longitudinal axis 55'. A connecting member 56 is provided on the outer side of the threaded spindle 55, which converts the rotational motion of the threaded spindle 55 into linear motion. The connecting member 56 is axially movably supported in the disc body 5, and the rotational motion of the threaded spindle 55 is converted into the axial motion of the connecting member 56 in a known manner. Corresponding teeth 31 are machined into the connecting member 56, which are mechanically connected to a synchronizing ring or drive piston 10.

[0059] Therefore, once the electric motor 54 is switched to the preset direction of rotation, the threaded spindle 55 rotates around its longitudinal axis 55', thereby converting the connecting component 56 into linear motion. The feed force and motion processes of other mechanisms inside the disc 5 correspond accordingly. Figures 1 to 8 .

[0060] Both drive variants share the characteristic that the piston rod 26 and the threaded spindle 55 extend or are oriented perpendicular to the centering axis 4. This ensures that, in order to generate and transmit the required kinetic force, there is no need for structural space that would significantly increase the structural height of the disc 5 by extending parallel to the centering axis.

Claims

1. A chuck (1) by which a workpiece (2) is individually supported for machining by a machine tool (3) and coaxially oriented with a centering axis (4) serving as a reference datum for machining the workpiece (2) by the machine tool (3), the chuck having: -Disc body (5); - At least four grippers (6,7,8,9) radially movable and supported at the disc body (5), the grippers being arranged in pairs along the X or Y axis, and the workpiece (2) being oriented by the grippers and aligned with the centering axis (4) and held during the machining process; and A pull piston (45) linearly supported in the disc (5) is drivenly connected to corresponding grippers (6,7,8,9) such that the grippers (6,7,8,9) synchronously feed radially along the direction of the workpiece (2) to be clamped or move away from the workpiece during the linear movement of the pull piston (45). -in, The pull piston (45) is arranged coaxially with the centering axis (4) inside the disc body (5) and is axially operated by a plurality of drive devices (12, 13, 52, 53). Its features are, Each drive unit (12, 13, 52, 53) has a linearly movable piston rod (26) or threaded spindle (55), the corresponding longitudinal axis (26' or 55') of which is arranged perpendicular to the centering axis (4). A synchronizing ring (21) is rotatably supported inside the disc body (5), the synchronizing ring (21) having at least two guide grooves (41, 42), and a connecting member (27) fixed at each drive unit (12, 13, 52, 53), and a slider (32, 33) molded at each connecting member (27), the slider engaging in or being embedded in the guide grooves (41, 42) of the synchronizing ring (21).

2. The clamping disc according to claim 1, characterized in that, A structural unit is arranged inside the disc body (5), the structural unit consisting of a slider (14,15,16,17) associated with and connected to one of the grippers (6,7,8,9) and a rocker (18), the rocker being oscillatingly supported on the disc body (5) around a support pin (19), and two adjacent sliders (14,15 or 16,17) connected to the grippers being mutually connected by the rocker.

3. The clamping disc according to claim 1 or 2, characterized in that, The two drive units (12, 13 or 52, 53) in the drive unit are arranged parallel to each other and spaced apart from the centering axis (4) on the outside of the disc (5) or inside the disc.

4. The clamping disc according to claim 1 or 2, characterized in that, Each slider (14, 15, 16, 17) connected to the gripper is drivenly connected to one of the grippers (6, 7, 8, 9).

5. The clamping disc according to claim 1 or 2, characterized in that, The sliders (32, 33) of the synchronization ring (21) are movably supported in the disk body (5) coaxially with the centering axis (4) relative to the disk body.

6. The clamping disc according to claim 1 or 2, characterized in that, The drive unit (12, 13) is designed as a hydraulically operated pressure piston with a piston rod (26), or the drive unit (52, 53) is designed as an electric motor (54) and a threaded spindle (55) connected to the electric motor, with the piston rod and the threaded spindle respectively fixed at the connecting part (27).

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