Gripping device and clamping unit

Abstract

Clamping unit (50), in particular for a gripping device (10) or for a linear unit, with a clamping element (52) for fixing the clamping unit (50) against a guide (12), wherein an actuating element (56) is provided which can be actuated in a base housing (54) along a longitudinal axis (58) and which is coupled to the clamping element (52) in such a way that the axial movement of the actuating element (56) along a longitudinal axis is reduced into an axial movement of the clamping element (52) along the longitudinal axis, wherein the actuating element (56) has at least one wedge surface (70) extending obliquely to the longitudinal axis, wherein at least one actuating body (72) cooperating with the wedge surface (70) is provided, which changes its radial position during an axial movement of the actuating element (56) and thereby actuates the clamping element (52) via a deflection mechanism, and wherein the clamping element (52) has a wedge surface (70) extending obliquely to the longitudinal axis (58),The inclined surface (74) has an acute angle (α) between the wedge surface (70) and the actuating body (72) such that the clamping element (52) is moved axially when the actuating body (72) moves radially.

Description

[0001] The invention relates to a clamping unit and a gripping device, the clamping unit having at least one base jaw movable along a guide in the direction of travel. Such gripping devices are known in various forms and serve to grip or clamp objects to be handled or processed. The gripping devices may have only one base jaw, which then presses the object against a fixed stop. It is also conceivable that the gripping device has two or more base jaws that can be moved towards or away from each other for gripping or clamping. The invention also relates to a clamping unit, in particular for such a gripping device.

[0002] A known gripping device with two jaws that can be moved towards and away from each other is known, for example, from DE 196 50 431 B4.

[0003] US 2011 / 0 241 365 A1 discloses a gripper and, in particular, a device for locking the jaws of the gripper to a guide rod.

[0004] From DE 296 13 345 U1 a braking and / or clamping device for guides is known.

[0005] EP 2 253 424 A1 describes a device for increasing the clamping force of a clamping device that restricts the rotation of a rotating shaft of a rotary indexing table.

[0006] US 2 397 414 A discloses a friction clutch

[0007] DE 10 2015 210 131 A1 discloses an actuating device for a friction clutch.

[0008] From US 7 490 881 B2 a gripper with linearly movable jaws that open and close on a workpiece, as well as grippers whose components are manufactured by extrusion.

[0009] The object of the invention is to improve existing gripping devices by making the base jaws lockable in a specific position.

[0010] The aforementioned problem is solved by a clamping unit, particularly for a gripping device, which has the features of claim 1. The clamping unit according to the invention can, however, be used with other handling components, such as linear units. The clamping unit has a clamping element for fixing the clamping unit against the guide, wherein an actuator is provided which can be actuated in a base housing along a longitudinal axis and which is coupled to the clamping element in such a way that the axial movement of the actuator along a longitudinal axis is converted into an axial movement of the clamping element. The force multiplication factor from actuator to clamping element can be in the range of 2 to 5 and particularly in the range of 3.5. The clamping unit is preferably arranged on a base jaw of a gripping device.It is also conceivable that the clamping unit can be arranged on moving components of other automation components, such as linear axes or swivel units, that are guided along a guide. The moving component could then be, for example, a slide or a rotary table. The actuation direction of the actuator and the direction of movement of the clamping element are preferably perpendicular or tangential to the direction of travel of the moving component of the automation component to be clamped.

[0011] Advantageously, the clamping unit includes a drive unit for axially actuating the actuator. The drive unit can be designed, in particular, as a pressurizable piston. It is also conceivable that the drive unit is mechanically actuated via an electromagnet, an electric motor, or in some other way.

[0012] The drive unit advantageously comprises a piston that is actuated on one side by compression springs and can also be pressurized on the other by a fluid, in particular compressed air or hydraulic fluid. The compression springs are preferably arranged such that they force the piston, the actuator, and thus also the clamping element into the locked position, in which the clamping element acts against the guide. This has the advantage that when no fluid is pressurizing the chamber, the compression springs force the clamping element into the locked position, thereby locking the base jaw or another moving component. This is particularly advantageous when switching off or in the event of an emergency stop of the handling component or its drive.

[0013] The actuator is designed to have at least one wedge-shaped surface extending obliquely to its longitudinal axis, and to have at least one actuating element that interacts with the wedge-shaped surface. The arrangement is such that the actuating element changes its radial position during axial movement of the actuator, thereby actuating the clamping element. The actuator may preferably have two wedge-shaped surfaces arranged symmetrically to each other with respect to its longitudinal axis, each wedge-shaped surface interacting with its own actuating element.

[0014] The arrangement is further such that the clamping element features an inclined surface, angled to the longitudinal axis and forming an acute angle with the wedge surface, for the bearing of the actuating body. This surface is designed so that radial movement of the actuating body results in axial movement of the clamping element. The acute angle between the wedge surface and the inclined surface determines the reduction ratio of the deflection mechanism. The more acute the angle, the greater the reduction. This arrangement allows for the conversion of the actuator's movement into a clamping element movement within a relatively small installation space. Both the actuator's and the clamping element's movements are axial, i.e., along the longitudinal axis. Additionally, the base housing may include a bearing surface which, together with the inclined surface, forms a receptacle for the actuating body.The actuating element can then be securely trapped between the wedge surface of the actuating element, the inclined surface of the clamping element and the contact surface of the base housing.

[0015] The actuating element can be designed, for example, as one or more cylindrical pins or as one or more ball elements. The inclined surface on the clamping element side and the contact surface on the base housing side can form an angle, the bisector of which is advantageously perpendicular to the longitudinal axis. The angle is preferably in the range of 90°.

[0016] Another deflection mechanism can be provided by designing the actuating body as the center bearing of a toggle lever mechanism, so that a radial movement of the actuating body results in an axial movement of the clamping element, i.e., along the longitudinal axis. This has the advantage that the actuating body does not need to be designed as a separate element, but rather as the center bearing of a toggle lever mechanism.

[0017] The toggle lever mechanism can have a first lever arm and a second lever arm, wherein the first and second lever arms enclose a lever angle, wherein the lever arms are connected to each other in the center bearing via a pivot axis, and wherein the free end of one lever arm is pivotably arranged on the base body and the free end of the other lever arm is pivotably arranged on the clamping element. The lever angle is preferably designed as an acute or obtuse angle, wherein the actuating element, or its wedge surface, engages the center bearing on the side facing away from the lever angle.

[0018] It is advantageous if the pivot axes at the free ends of the lever arms and in the center bearing are arranged parallel to each other. It is further advantageous that the opposite pivot axes of the lever arms lie in a plane parallel to the longitudinal axis. This results in a very compact deflection mechanism with no loose parts. Nevertheless, a high reduction ratio can be provided, enabling the transmission of high forces when the actuator is operated.

[0019] The aforementioned problem is solved by a clamping unit, particularly for a gripping device, with features of claim 7. However, the clamping unit according to the invention can also be used with other handling components, such as linear units. The clamping unit has a clamping element for fixing the clamping unit against the guide, wherein an actuator is provided that can be actuated in a base housing along a longitudinal axis and is coupled to the clamping element in such a way that the axial movement of the actuator is converted into an axial movement of the clamping element. It is provided that the actuator has at least one wedge surface extending obliquely to the longitudinal axis and that at least one actuating element is provided that interacts with the wedge surface.The arrangement is such that, during axial movement of the actuator, the actuating body changes its radial position, thereby actuating the clamping element via a deflection mechanism. The actuating body is designed as the center bearing of a toggle lever mechanism, so that a radial movement of the actuating body results in an axial movement of the clamping element, i.e., along its longitudinal axis.

[0020] This problem is also solved by a gripping device with the features of claim 10. Accordingly, a clamping unit according to the invention with an actuable clamping element is provided on the base jaw, with which the base jaw can be fixed against the guide. By providing a clamping element on the base jaw, it can be ensured that the base jaw can be actively fixed in a specific position on the guide. Fixing can occur, in particular, when a predetermined position is reached. However, fixing can also occur if a drive that drives the base jaw fails or is switched off. This prevents any unintended further movement of the base jaw.

[0021] Advantageously, the guide can be designed as a guide rod, with the clamping element then acting against the surface of the guide rod. The guide rod can, in particular, have a round cross-section or a polygonal, preferably rectangular or hexagonal, cross-section. The base jaw can provide a guide receptacle designed to complement the guide rod, which slides along the guide during operation. The guide receptacle can preferably extend through the entire longitudinal direction of the base jaw.

[0022] In a further advantageous embodiment of the invention, the base jaw has a cylindrical chamber which is divided into two pressure chambers by a stationary piston. Depending on the pressure applied to one or the other pressure chamber, the jaw can therefore be actively moved in one direction or the other along the direction of travel. The stationary piston can be attached to a base housing of the gripping device by means of piston rods, on which connections for a fluid for pressurizing the pressure chambers can also be provided.

[0023] Advantageously, the guides can be designed as guide rods, running parallel to the piston rods and arranged on the base housing.

[0024] The design includes two base jaws that can move towards and away from each other. Each base jaw can be fitted with a rack in the direction of travel, and a meshing pinion can be positioned between the racks. This arrangement enables motion coupling and thus synchronization of the movement of the two base jaws.

[0025] Further details and advantageous embodiments of the invention can be found in the following description, which describes and explains various embodiments of the invention in more detail.

[0026] They show: Fig. 1 a perspective view of a gripping device according to the invention; Fig. 2 the gripping device according to Fig. 1 in side view; Fig. 3 the gripping device according to Fig. 2 along line III; Fig. 4 a cross-section through the gripping device along line IV in Fig. 5; Fig. 5 a longitudinal section through the gripping device along line V in Fig. 4; Fig. 6 a clamping unit according to the invention in perspective view; Fig. 7 a longitudinal section through the clamping unit according to Fig. 6 in release position; Fig. 8 the cut according to Fig. 7 in fixed position and Fig. 9 a longitudinal section through an alternative embodiment of the clamping unit according to Fig. 6.

[0027] In the Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. Figure 5 shows a gripping device 10 according to the invention, comprising two base jaws 16, 18 that can be moved towards and away from each other and which can be moved along two guides 12 in the direction of travel 14. The base jaws 16, 18 are located on a base body 20, which has end plates 22 extending transversely to the direction of travel 14 at its free end. The base body 20 has a central element 24 between the end plates 22.

[0028] As can be seen in particular from the section according to Fig. As is clearly shown in Figure 5, the guides 12 between the end plates 22 are implemented as hollow guide rods, which also extend through the central part 24. The base jaws 16, 18 also show, as is also shown in Figure 5. Fig. As can be clearly seen in Figure 5, guide recesses 26 are shown, through which the guides 12 extend. The base jaws 16, 18 are therefore arranged to slide over the guide recesses 26 on the guides 12 in the direction of travel 14.

[0029] As can be seen from the cross-section according to Fig. As is clearly shown in Figure 3, the base jaws 16, 18 each have a cylinder chamber, which is each divided into two pressure chambers 32, 34 by a piston 30. The pressure chambers 32, 34 are controlled by, also in Fig. Three clearly identifiable pressure lines 36 are each synchronously and alternately pressurized with compressed air, causing the base jaws 16, 18 to move towards or away from each other. The pressure lines 36 are designed as hollow rods extending in the direction of travel 14 and connected to compressed air connections 38 provided in the central element 24. The pistons 30 are fixedly arranged on the base body 20 via the pressure lines 36 and the central element 24. The base jaws 16, 18 can therefore be set in motion by pressurizing the corresponding connections 38.

[0030] To synchronize the movement of the two base jaws 16, 18, as in Fig. As shown in Figure 5, a rack 40 extending in the direction of travel 14 is arranged on each base jaw 16, 18. The racks 40 have teeth on their facing sides that mesh with a pinion 42 rotatably mounted on the central element 24. This ensures highly precise synchronous movement of the two base jaws 16, 18. The racks 40 are housed in sleeves 44 arranged on the central element 24, which engage with the respective base jaw 16, 18 when the base jaws 16, 18 are moved.

[0031] As from the Fig. 3 and Fig. As becomes clear in Figure 5, each base jaw 16, 18 has a clamping unit 50 which is located in the Fig. 6, Fig. 7, Fig. 8 to Fig. 9 is shown as a single part.

[0032] Each clamping unit 50 has an actuable clamping element 52, which, in the installed state, as shown in Fig. 5 shown, to fix the respective base jaw 16, 18 against the respective guide 12.

[0033] The clamping unit 50, as shown in the Fig. 7, Fig. 8 to Fig. As can be clearly seen in Figure 9, a basic housing 54 is provided in which an actuator 56 can be actuated along a longitudinal axis 58. A drive unit 59 is provided for actuating the actuator, which can, for example, be designed as a piston 62. Alternatively, it is conceivable that other drives, such as electric motors, could be used.

[0034] The actuator 56 is according to Fig. 7 and Fig. 8 is arranged at the free end of a piston rod 60 of the piston 62. The piston 62 is displaceable in a pressure chamber 64 in the longitudinal direction 58. The piston 62 is actuated on one side by means of compression springs 66. On the other hand, the pressure chamber 64 is supplied via a fluid connection 68, which is in Fig. As shown in Figure 6, it can be actuated by hydraulic oil or compressed air. Various sealing elements 88 are provided for a fluid-tight seal of the pressure chamber 64. The base housing 54 comprises a base plate 54.1 and a cover element 54.2, in which the compression springs 66 are housed and in which the piston 62 is slidably mounted.

[0035] As from the Fig. 7, Fig. 8 and Fig. As can be clearly seen in Figure 9, the actuator 56 has two wedge surfaces 70 extending obliquely to the longitudinal axis 58, enclosing a wedge angle γ of approximately 30°. Two actuating elements 72 in the form of cylindrical pins are provided between the clamping element 52 and the wedge surfaces 70. The actuating elements 72 are arranged such that when the actuator 56 moves axially in the direction of the longitudinal axis 58, the actuating elements 72 move radially, i.e., transversely to the longitudinal axis 58.

[0036] The clamping element 52 is provided with inclined surfaces 74 that interact with the actuating elements 72. These inclined surfaces 74 form an acute angle α with the wedge surfaces 70 on the actuating element side. Depending on the choice of this angle α, a corresponding reduction ratio results between the axial movement of the actuating element 56 and the axial movement of the clamping element 52. Thus, if the actuating elements 72 are displaced radially outwards due to the movement of the actuating element 56, the inclined surfaces 74 also result in a movement of the wedge element 52 in the direction of the longitudinal axis.

[0037] The clamping element 52 is guided on the base housing 54 via a support element 76, such that the clamping element 52 only has freedom of movement in the direction of the longitudinal axis 54. For secure reception of the actuating elements 72, the base housing 54 and its support element 76 have contact surfaces 78. The contact surfaces 78 form an angle of approximately 90° with the inclined surfaces 74. The bisector of this angle runs essentially perpendicular to the longitudinal axis 58. As can be seen from the Fig. 7 and Fig. As can be clearly seen in Figure 8, the actuating elements 72 are therefore securely trapped between the wedge surfaces 56 on the actuator side, the contact surfaces 78 on the base housing side and the inclined surfaces 74 on the clamping element side.

[0038] Is the actuator removed from the in Fig. 4 shown release position by depressurizing the pressure chamber 74 due to the compression springs 58 into the Fig. When the locking position shown in section 8 is actuated, the actuating elements 72 are forced radially outwards, whereby, as shown in Fig. As shown in Figure 8, the clamping element 52 is actuated into the locking position along the longitudinal axis 58. Due to the selected reduction ratio between the movement of the actuator 56 and the movement of the clamping element 52, a comparatively high locking force can be provided.

[0039] Starting from the Fig. When pressure chamber 64 is pressurized, the piston 62 moves against the force of the compression springs 66 into its release position. This allows the actuating elements 72 to move radially inwards, causing the clamping element 52 to engage the Fig. The release position shown in section 7 is occupied.

[0040] To ensure that the clamping element 52 is securely attached to the base body 54, through-bolts 80 are provided for the clamping element 52. These bolts are screwed into corresponding threads provided on the support element 76 and the base housing 54, respectively. To safely move the clamping element 52 from the fixed position to the release position, it is pressed towards the support element 76 by means of coil springs 82, which bear against the heads of the fastening bolts 80. Furthermore, guide sections 84 and 86, which interact with each other, are provided on the clamping element 52 and the support element 76.

[0041] In the Fig. Figure 9, in which the base housing support element 76 and the actuator 56 which can be displaced along the longitudinal axis 58 are shown, shows an alternative deflection mechanism which deflects the movement of the actuator 56 into a movement of the clamping element 52.

[0042] The wedge surfaces 70 of the actuator 56 act against actuating bodies which are designed as center bearings 90 of a toggle lever mechanism 92, so that a radial movement of the center bearings 90 results in an axial movement of the clamping element 52 in the direction of the longitudinal axis 58.

[0043] The toggle lever mechanism 92 has a first lever arm 94 and a second lever arm 96. The first lever arm 94 and the second lever arm 96 form a lever angle β. The lever arms 94 and 96 are coupled via a pivot axis 98 located in the center bearing 90. The free ends of the lever arms 94 are pivotally mounted on the support element 76 via pivot axes 98. The free ends of the lever arms 96 are pivotally mounted on the clamping element 52 via pivot axes 102. The respective pivot axes 100 and 102 are located in a plane parallel to the longitudinal axis 58.

[0044] The described mechanism consequently moves the respective center bearings 90 radially outwards when the actuator 56 is axially moved into the fixed position, thereby increasing both the lever angle β and the distance between the respective pivot axes 102 and 100. This moves the clamping element 52 into the fixed position. The reduction ratio of the movement of the actuator 56 to the movement of the clamping element 52 depends on the angle of the wedge surfaces 70 and on the distances of the pivot axes 100 and 102 to the pivot axes 98 of the center bearings 90. A suitable reduction ratio of the movement of the actuator 56 to the movement of the clamping element 52 can be provided with comparatively little effort using the described deflection mechanism. Unlike the embodiment according to the Fig. 7 and Fig. No loose components are provided here.

[0045] As described at the outset, the invention is not limited to providing clamping units 50 on gripping devices. It is also conceivable that the clamping units according to the invention can be used on other moving parts of automation components, such as linear axes or swivel units.

Claims

[1] Clamping unit (50), in particular for a gripping device (10) or for a linear unit, with a clamping element (52) for fixing the clamping unit (50) against a guide (12), wherein an actuating element (56) is provided which can be actuated in a base housing (54) along a longitudinal axis (58) and which is coupled to the clamping element (52) in such a way that the axial movement of the actuating element (56) along a longitudinal axis is reduced into an axial movement of the clamping element (52) along the longitudinal axis, wherein the actuating element (56) has at least one wedge surface (70) extending obliquely to the longitudinal axis, wherein at least one actuating body (72) cooperating with the wedge surface (70) is provided which changes its radial position during an axial movement of the actuating element (56) and thereby actuates the clamping element (52) via a deflection mechanism, and wherein the clamping element (52) has a wedge surface (70) extending obliquely to the longitudinal axis (58),The inclined surface (74) has an acute angle (α) between the wedge surface (70) and the actuating body (72) such that the clamping element (52) is moved axially when the actuating body (72) moves radially. [2] Clamping unit (50) according to claim 1, characterized by , that a drive unit (59) is provided for axial actuation of the actuator (56). [3] Clamping unit (50) according to claim 2, characterized by , that the drive unit (59) comprises a piston (62) which is actuated on the one hand by means of compression springs (66) and on the other hand can be pressurized by means of a fluid. [4] Clamping unit (50) according to claim 1, 2 or 3, characterized by , that the clamping element (52) is pressed against the base housing (54) by means of spring elements (82). [5] Clamping unit (50) according to claim 1, characterized by, that a contact surface (78) is provided on the base housing (54) which together with the inclined surface (74) forms a receptacle for the actuating body (72). [6] Clamping unit (50) according to claim 5, characterized by , that the inclined surface (74) and the contact surface (78) enclose an angle, wherein the angle bisector of the angle is perpendicular to the longitudinal axis (58). [7] Clamping unit (50), in particular for a gripping device (10) or for a linear unit, with a clamping element (52) for fixing the clamping unit (50) against a guide (12), wherein an actuating element (56) is provided which can be actuated in a base housing (54) along a longitudinal axis (58) and which is coupled to the clamping element (52) in such a way that the axial movement of the actuating element (56) along a longitudinal axis is reduced into an axial movement of the clamping element (52) along the longitudinal axis, wherein the actuating element (56) has at least one wedge surface (70) extending obliquely to the longitudinal axis, wherein at least one actuating body (72) cooperating with the wedge surface (70) is provided, which changes its radial position during an axial movement of the actuating element (56) and thereby actuates the clamping element (52) via a deflection mechanism, wherein the actuating body (72) serves as the center bearing (90) of a toggle lever mechanism (92) is trainedso that a movement of the center bearing (90) in the radial direction results in a movement of the clamping element (52) in the axial direction. [8] Clamping unit (50) according to claim 7, characterized by , that the toggle lever mechanism (92) has a first lever arm (94) and a second lever arm (96), wherein the first and second lever arms (94, 96) enclose a lever angle (β) and are pivotably connected to each other in the center bearing (90) via a pivot axis (98), and wherein the free end of one lever arm (94) is pivotably arranged on the base housing (54) in a pivot axis (100) and the free end of the other lever arm (96) is pivotably arranged on the clamping element (52) in a pivot axis (102). [9] Clamping unit (50) according to claim 8, characterized by, that the pivot axes (98, 100, 102) are arranged parallel to each other and / or that the pivot axes (100, 102) of the lever arms (94, 96) facing away from each other lie in a plane parallel to the longitudinal axis (58). [10] Gripping device (10) with at least one base jaw (16, 18) movable along a guide (12) in the direction of travel (14), characterized by , that a clamping unit (50) according to one of the preceding claims 1 to 10 is provided on the base jaw (16, 18) with an actuable clamping element (52) with which the base jaw (16, 18) can be fixed against the guide (12). characterized by , that two base jaws (16, 18) are provided which can be moved towards and away from each other. [11] Gripping device (10) according to claim 10, characterized by, that a rack (40) is provided on each base jaw (16, 18) in the direction of travel, and that a pinion (42) meshing between the racks (40) is provided. [12] Gripping device according to claim 10 or 11, characterized by , that the guide (12) is designed as a guide rod and that the clamping element (52) acts against the surface of the guide rod. [13] Gripping device according to claim 10, 11 or 12, characterized by , that the base jaw (16, 18) has a cylinder chamber which is divided into two pressure chambers (32, 34) by a fixed piston (30).

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