Clamping device for clamping an object
Patent Information
- Application Number
- EP2024731819
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-07-21
- Filing Date
- 2024-06-01
- Publication Date
- 2025-08-06
AI Technical Summary
Existing swivel tensioners are complex to set up and require significant space for swivel movement, limiting their use due to the need for precise alignment and potential collisions.
A clamping device with a clamping arm that replaces the swivel movement with linear horizontal and vertical movements, using a clamping piston and exit piston driven by pressure media, allowing for a more straightforward and space-efficient tensioning process.
The device achieves efficient tensioning and loosening of objects with a simplified movement sequence, reducing the risk of collisions and improving usability by converting vertical piston movement into linear horizontal and vertical arm movements.
Smart Images
Figure EP2024065132_30012025_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] Clamping device for clamping an object
[0003] Technical field of
[0004] The invention relates to a clamping device for clamping an object (e.g. workpiece or tool).
[0005] So-called swing clamps are known from the prior art (e.g. DE 10 2016 010 657A1, DE 10 2020 115 803 A1), which make it possible to clamp a workpiece by means of a clamping arm, wherein the clamping arm can be pivoted horizontally and retracted vertically. Such swing clamps can be driven hydraulically by means of a clamping piston that can be moved vertically within a clamping cylinder. The vertical movement of the clamping piston within the clamping cylinder is converted by a link control into a combined movement of the clamping arm, wherein the combined movement consists of a vertical movement for clamping or releasing and a horizontal pivoting movement of the clamping arm. In the released state, the clamping arm is pivoted sideways in a horizontal direction so that the workpiece to be clamped can be inserted.During a clamping process, the clamping arm is first pivoted horizontally over the workpiece. The clamping arm then moves vertically toward the workpiece until the workpiece is finally clamped. When releasing from the clamped position, this combined vertical and pivoting movement occurs in reverse.
[0006] One of the disadvantages of this well-known swing clamp is the relatively complicated link control for converting the vertical movement of the clamping piston into the combined vertical and swivel movement of the clamping arm.
[0007] A further disadvantage of the known swing clamps is that the pivoting movement of the clamping arm requires space, so that the use of the known swing clamps is only possible if the clamping arm can be pivoted in without collision at the installation site. Furthermore, for the general technical background of the invention, reference should also be made to DE 10 2016 203 353 A1, DE 36 10 060 A1, DE 39 36 122 CI, DD 250 486 A1, and DE 41 39 317 A1.
[0008] Description of the invention
[0009] The invention is therefore based on the object of creating an improved clamping device.
[0010] This object is achieved by a clamping device according to the invention according to the main claim.
[0011] The clamping device according to the invention, in accordance with known swing clamps, comprises a clamping arm that serves to clamp an object (e.g., a workpiece or tool), in particular by means of a clamping iron that is replaceably mounted or integrally formed at the end of the clamping arm. The clamping arm can therefore be retracted vertically during a clamping process and extended vertically to release the clamping device.
[0012] It should be noted that the clamping device according to the invention is preferably designed to clamp a workpiece. However, within the scope of the invention, it is also possible for the object to be clamped to be a tool. For example, forming tools must be clamped on a press, for which the clamping device according to the invention can be used. Thus, the invention is not limited to a workpiece or a tool with regard to the object to be clamped.
[0013] Furthermore, the clamping device according to the invention, in accordance with the known swing clamps described above, has a vertically oriented clamping cylinder in which a clamping piston can be displaced in the vertical direction, wherein the clamping piston can be driven by a pressure medium (e.g. hydraulic oil, compressed air). During a clamping process, the clamping piston is then pulled downwards in the clamping cylinder in the vertical direction. When the clamping device is released, the clamping piston can then be moved upwards again in the vertical direction in the clamping cylinder. The clamping piston is mechanically connected to the clamping arm, so that the vertical movement of the clamping piston in the clamping cylinder is transferred to the clamping arm.
[0014] The clamping device according to the invention is distinguished from the known swing clamps described above by at least one horizontally oriented extension cylinder, wherein an extension piston is displaceable horizontally in the extension cylinder to extend the clamping arm horizontally when the clamping device is tightened or to retract it horizontally when the clamping device is released. The extension piston in the extension cylinder can also be driven by a pressure medium (e.g., hydraulic oil, compressed air).
[0015] Within the scope of the invention, the rotary horizontal pivoting movement of the clamping arm known from conventional swing clamps is replaced by a linear horizontal movement of the clamping arm.
[0016] The clamping device according to the invention therefore preferably enables a linear horizontal movement and a linear vertical movement. The linear horizontal movement serves to extend or retract the clamping arm. The linear vertical movement, on the other hand, serves to tighten or loosen the clamping device.
[0017] The directional terms "horizontal" and "vertical" used in the context of the invention each refer to a mounting plane of the clamping device. This means that the clamping piston in the clamping device is preferably displaceable in the vertical direction at right angles to the mounting plane, while the extension piston in the extension cylinder is preferably displaceable parallel to the mounting plane.
[0018] It should also be noted that the vertical and horizontal directions do not necessarily have to be exactly perpendicular to each other. Rather, it is also possible that the horizontal direction is not exactly perpendicular to the vertical direction. However, it should be noted that the horizontal direction generally runs perpendicular to the vertical direction.
[0019] In a preferred embodiment of the invention, the clamping device is designed such that when the clamping device is clamped, the clamping arm is first extended horizontally and only then is the clamping arm retracted vertically. When the clamping device is released, the clamping arm is therefore preferably retracted so that the object to be clamped (e.g. workpiece, tool) can then be easily placed in position. During a clamping process, the object to be clamped (e.g. workpiece, tool) is therefore first placed next to the clamping device. The clamping arm is then extended horizontally and only then is the clamping arm retracted vertically to clamp the object.
[0020] In addition, the clamping device is preferably designed such that when the clamping device is released, the clamping arm is first extended in the vertical direction and only then is the clamping arm retracted in the horizontal direction.
[0021] The invention therefore provides for a specific sequence of horizontal movement and vertical movement of the clamping arm when clamping and / or releasing the clamping device.
[0022] It has already been mentioned above that the clamping device is preferably designed such that when the clamping device is tightened, the clamping arm is first extended horizontally and only then is the clamping arm retracted vertically. For this purpose, the clamping piston can be frictionally fixed in the clamping cylinder at its upper stop by a self-locking clamping of the clamping piston in the clamping cylinder. The self-locking clamping of the clamping piston in the clamping cylinder therefore initially holds the clamping piston in the released position. The vertical retraction of the clamping arm when tightening the clamping device only begins once the self-locking clamping of the clamping piston in the clamping cylinder has been overcome. When the clamping device is tightened, the pressure of the pressure medium acting on the top side of the clamping piston generates a downward force on the clamping piston.However, this force on the clamping piston only causes the clamping piston to move downwards in the clamping cylinder once the self-locking clamping of the clamping piston is released. In the meantime, the pressure medium can then drive the extension piston to extend the clamping arm horizontally. This ensures that when the clamping device is tightened, the extension piston is extended horizontally first, and only then is the clamping arm retracted vertically.
[0023] The self-locking clamping of the clamping piston in the clamping cylinder preferably exists between an outer cone on the top side of the clamping piston and an inner cone on the top side of the clamping cylinder, wherein the outer cone and the inner cone taper upwards in the vertical direction. The inner cone of the clamping cylinder then forms, together with the outer cone of the clamping piston, the self-locking clamping of the clamping piston at the upper stop of the clamping piston. During a vertical upward movement of the clamping piston in the clamping cylinder, the outer cone on the clamping piston abuts the inner cone in the clamping cylinder at the upper stop of the clamping piston, which then leads to the self-locking clamping. In the preferred embodiment of the invention, the inner cone of the clamping cylinder and the outer cone of the clamping piston have the same cone angle.It should be noted that the cone angle is sufficiently small to ensure self-locking clamping of the clamping piston at the upper stop of the clamping piston.
[0024] It should also be mentioned that the outer cone for the self-locking clamping can be formed directly onto the clamping piston. In the preferred embodiment of the invention, however, the outer cone is formed onto a separate conical ring which surrounds the clamping piston or an upwardly projecting piston rod of the clamping piston as a separate component. This offers the advantage that the conical ring with the outer cone can be made of a different material than the clamping piston, in particular of a material with a higher coefficient of friction in order to achieve the self-locking clamping. For example, the conical ring with the outer cone can be made of an elastomer, while the clamping piston itself is made of steel. It should also be mentioned that the outer cone can have a continuous axial groove in the axial direction in order to guide the pressure medium through the axial groove in the axial direction. This axial groove then preferably runs in the outer surface of the conical ring.
[0025] In the preferred embodiment of the invention, the clamping device has a first pressure medium inlet for supplying the pressure medium (e.g., hydraulic oil, compressed air) for clamping the clamping device. The first pressure medium inlet is connected to both the clamping cylinder and the extension cylinder. Thus, the clamping cylinder and the extension cylinder are preferably driven jointly by the pressure medium for clamping.
[0026] Furthermore, the clamping device preferably has a second pressure medium inlet for supplying the pressure medium (e.g., hydraulic oil, compressed air) for releasing the clamping device, wherein the second pressure medium inlet is connected to both the clamping cylinder and the extension cylinder. Thus, even when releasing the clamping device, the clamping cylinder and the extension cylinder are preferably driven jointly.
[0027] The clamping cylinder preferably has an upper pressure chamber on the top side of the clamping piston for clamping the clamping device, wherein the upper pressure chamber of the clamping cylinder is connected to the first pressure medium connection. In addition, the clamping cylinder preferably has a lower pressure chamber on the underside of the clamping piston for releasing the clamping device, wherein the lower pressure chamber of the clamping cylinder is connected to the second pressure medium inlet. It should also be mentioned that the clamping piston preferably has an axially through bore in order to guide the pressure medium from the lower pressure chamber of the clamping cylinder into the extension cylinder when the clamping device is released, so that the lower pressure chamber of the clamping cylinder and the extension cylinder are simultaneously pressurized with the pressure medium for releasing the clamping device. To release the clamping device, the pressure medium (e.g.The pressure medium (e.g., hydraulic oil, compressed air) is initially introduced into the lower pressure chamber of the clamping cylinder via the second pressure medium inlet, thereby pushing the clamping piston upwards. The pressure medium can then flow from the lower pressure chamber of the clamping cylinder to the extension cylinder via the axially through bore in the clamping piston to retract the extension piston, as described below.
[0028] The extension cylinder preferably has an inner pressure chamber for extending the clamping arm in the horizontal direction, which is surrounded by an outer pressure chamber that serves to retract the clamping arm in the horizontal direction. The through axial bore in the clamping piston of the clamping cylinder is then preferably connected to the outer pressure chamber of the extension cylinder, so that when the clamping device is released, the lower pressure chamber of the clamping cylinder and the outer pressure chamber of the extension cylinder are simultaneously pressurized. The first pressure medium inlet for clamping the clamping device, on the other hand, is preferably connected to the inner pressure chamber of the extension cylinder via a pressure medium line, so that when the clamping device is clamped, the upper pressure chamber of the clamping cylinder and the inner pressure chamber of the extension cylinder are simultaneously pressurized with the pressure medium.
[0029] It should also be mentioned that the clamping device can have an anti-twist device that prevents the extension piston from rotating in the extension cylinder. For this purpose, a longitudinal groove that runs horizontally can be arranged in the outer surface of the extension piston. A guide ball then preferably engages in this longitudinal groove in the outer surface of the extension piston. The guide ball is fixedly arranged in the axial and circumferential directions in the extension cylinder and engages in the longitudinal groove in the extension piston, thereby preventing rotation of the extension piston relative to the extension cylinder. The guide ball engages in the longitudinal groove in the extension cylinder with a specific engagement depth, wherein the engagement depth of the guide ball is predetermined by a screw, wherein the screw is preferably sealed with a sealing ring (e.g. Usit ring).It should also be mentioned that the clamping device preferably has a clamping cylinder housing containing the clamping cylinder and the clamping piston. In addition, the clamping device preferably has an extending cylinder housing containing the extending cylinder and the extending piston. The extending cylinder housing preferably has a shaft that projects downwards from the extending cylinder housing and protrudes into the clamping cylinder of the clamping cylinder housing. On its inner side, the shaft preferably has an internal thread. The clamping piston, on the other hand, preferably has a piston rod that projects upwards from the clamping piston, protrudes into the shaft of the extending cylinder housing, and has an external thread.The upwardly projecting piston rod of the clamping piston is then preferably screwed with its external thread to the internal thread of the shaft of the extending cylinder housing, so that the clamping piston moves the extending cylinder housing vertically when clamping and releasing the clamping device. The clamping piston can have a recess on its underside for a wrench, particularly in the form of a hexagon socket, to screw the clamping piston into the internal thread in the shaft. The screw connection between the shaft of the extending cylinder housing and the piston rod of the clamping piston thus mechanically connects the extending cylinder housing to the clamping piston.
[0030] It should also be mentioned that the extending cylinder is preferably closed laterally on the side opposite the clamping arm by a housing cover. On the side facing the housing cover, the extending piston preferably has a horizontal blind bore which forms the internal pressure chamber of the extending cylinder. A pin is preferably formed on the inside of the housing cover and projects horizontally into the blind bore in the extending piston. This pin preferably has an axial channel which opens into the blind bore in order to introduce the pressure medium into the blind bore for extending the clamping arm. The aforementioned first pressure medium inlet for clamping the clamping device is therefore preferably connected to the blind bore via the axial channel in the pin in order to extend the clamping arm horizontally.
[0031] It was already mentioned at the beginning that the clamping device according to the invention is preferably designed such that when the clamping device is tightened, the clamping arm is first extended in the horizontal direction and only then is the clamping arm retracted in the vertical direction. One technical possibility for implementing this sequence of different movements consists in the self-locking clamping of the clamping piston in the clamping cylinder as described above. Alternatively, there is the possibility that the clamping piston is fixed in its released position by a locking connection in the clamping cylinder. This locking connection between the clamping piston and the clamping cylinder is then only released during clamping when the pressure of the pressure medium in the clamping cylinder exceeds a certain limit, so that when the clamping device is tightened, the clamping arm is first extended in the horizontal direction and only then is the clamping arm retracted in the vertical direction.For example, this locking connection can comprise a locking groove in the cylinder surface of the clamping cylinder and a spring ring in the outer surface of the clamping piston.
[0032] In addition to the self-locking clamping of the clamping piston in the clamping cylinder described above and the alternatively possible locking connection, a third variant of the invention offers the possibility of the clamping piston being pressed vertically into its released position by a spring, in particular by a helical spring which presses the clamping piston upwards into its released position. In its released upper position, the clamping piston offers the pressure medium a significantly smaller contact surface than in its tensioned lower position, so that the clamping piston is held in its released position as long as the force acting on the clamping piston by the pressure medium is smaller than the force acting on the clamping piston by the spring, so that when the clamping device is tensioned, the clamping arm is first extended horizontally and only then is the clamping arm retracted vertically.For example, the tensioning piston can have an annular sealing edge which, in the released position of the tensioning piston, limits the smaller contact surface for the pressure medium.
[0033] As already mentioned at the beginning, a specific sequence of the horizontal movement of the extending piston on the one hand and the vertical movement of the clamping piston on the other hand should be observed when releasing the clamping device. For example, when releasing the clamping device, the clamping arm should first be extended vertically, after which the clamping arm should then be retracted horizontally. To achieve this sequence of the two movements, the extending piston preferably offers the pressure medium a smaller contact surface in its horizontally extended position than in its horizontally retracted position, so that when releasing the clamping device, the clamping arm is first extended vertically and only then is the clamping arm retracted horizontally.
[0034] The sequence of movements described above when releasing the clamping device can alternatively be achieved by frictionally fixing the extending piston in the horizontally extended position of the clamping piston by a self-locking clamp in the extending cylinder, as already described above with regard to the clamping piston in the clamping cylinder. When releasing the clamping device, the horizontal retraction of the clamping arm only begins once the self-locking clamp of the extending piston in the extending cylinder has been overcome, so that when releasing the clamping device, the clamping arm is first extended vertically and only then is the clamping arm retracted horizontally.
[0035] To achieve this self-locking clamping, the extending piston can have an outer cone, which, together with an inner cone in the extending cylinder, creates the self-locking clamping action. The outer cone and inner cone taper horizontally toward the end of the clamping arm. The inner cone of the extending cylinder, together with the outer cone of the extending piston, then creates the self-locking clamping action of the extending piston when the clamping arm is horizontally extended.
[0036] The inner cone of the extending cylinder and the outer cone of the extending piston preferably have the same cone angle. In any case, the cone angle should be sufficiently small to ensure self-locking of the extending piston when the clamping arm is in the horizontally extended position.
[0037] In general, it should be noted that the clamping arm is preferably removably secured to the end of the clamping arm using a fastening screw. However, it is also possible for the clamping arm to be formed integrally with the clamping arm. Furthermore, it should also be noted that the extension piston and the clamping arm can be formed integrally.
[0038] It should also be noted that hydraulic oil or compressed air, for example, can be used as a pressure medium.
[0039] Finally, it should also be mentioned that the vertical movement is not necessarily performed by a single clamping cylinder. Rather, within the scope of the invention, it is also possible for the vertical movement to be performed by several clamping cylinders working together. The same applies to the horizontal movement, which does not necessarily have to be performed by a single extension cylinder, but can also be performed by several extension cylinders working together.
[0040] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures.
[0041] Brief description of the drawings
[0042] Figure 1 shows a perspective view of a clamping device according to the invention.
[0043] Figure 2 shows a bottom view of the clamping device from Figure 1.
[0044] Figure 3 shows a top view of the clamping device according to Figures 1 and 2.
[0045] Figure 4A shows a sectional view through the clamping device according to the invention according to the section line AA in Figure 3, wherein the drawing shows a released state of the clamping device.
[0046] Figure 4B shows a detailed enlargement of Figure 4A in the area of the clamping piston.
[0047] Figure 4C shows a detailed enlargement of Figure 4A in the area of the extension piston.
[0048] Figure 4D shows a sectional view along section line AA in Figure 3 in a clamped state of the clamping device.
[0049] Figure 5A shows a sectional view along the section line BB in Figure 3 in a clamped state of the clamping device.
[0050] Figure 5B shows a detail enlargement from Figure 5A in the area of the clamping piston in a released state.
[0051] Figure 6 shows a sectional view along the section line CC in Figure 2 in a released state of the clamping device.
[0052] Figure 7 shows a modification with a locking connection between the clamping piston and the clamping cylinder.
[0053] Figure 8A shows a further modification with a coil spring acting on the tensioning piston. Figure 8B shows an enlarged detail of Figure 8A.
[0054] Figure 9A shows a modification in the area of the extension piston.
[0055] Figure 9B shows a detail enlargement of Figure 9A.
[0056] Figure 10 shows a further modification with a self-locking clamping of the extension piston in the extension cylinder.
[0057] Detailed information
[0058] In the following, the first embodiment of a clamping device 1 according to the invention, shown in Figures 1 to 6, is first described. The clamping device 1 serves to clamp a workpiece similarly to a known swing clamp, whereby the workpiece to be clamped is arranged laterally next to the clamping device 1 and is not shown for the sake of simplicity.
[0059] It should be noted here that the object to be clamped does not necessarily have to be a workpiece. For example, the clamping device 1 according to the invention can also be used to clamp a tool. For example, forming tools are clamped on a press, for which the clamping device 1 according to the invention can also be used.
[0060] The clamping device 1 initially comprises a clamping cylinder housing 2, wherein the clamping cylinder housing 2 is substantially cylindrical in the lower region and has a pressure medium inlet 3 for clamping the clamping device 1 and a pressure medium inlet 4 for releasing the clamping device 1. Hydraulic oil can be supplied as a pressure medium via the two pressure medium inlets 3, 4, as will be described in detail below.
[0061] In addition, the clamping device 1 has an extension cylinder housing 5 in the upper area, which is displaceable in the vertical direction relative to the clamping cylinder housing 2, as indicated by the vertically oriented double arrow.
[0062] A clamping arm 6 is extendable horizontally within the extension cylinder housing 5, as indicated by the horizontally oriented double arrow. A clamping iron 8 is screwed to the end of the clamping arm 6 by means of a fastening screw 7. When clamped, the clamping iron rests on the workpiece to be clamped.
[0063] The clamping cylinder housing 2 contains a clamping cylinder 9 in which a clamping piston 10 is displaceable in the vertical direction, as will be described in detail.
[0064] On its underside, the clamping cylinder housing 2 is closed by a screw base 11, which is screwed into the clamping cylinder 9 and closes the clamping cylinder 9 at the bottom. The screw base 11 is sealed against the inner wall of the clamping cylinder housing 2 by a seal 12. On its underside, the screw base 11 has two opposite blind holes 13, 14 into which a screwing tool can engage to screw in or unscrew the screw base 11.
[0065] It should also be mentioned that the clamping piston 10 in the clamping cylinder 9 is sealed by a seal 15.
[0066] The clamping cylinder 9 has a lower pressure chamber 16 on the underside of the clamping piston 10, which is connected to the pressure medium inlet 4 via a pressure medium line 17. To release the clamping device 1, a pressure medium (e.g., hydraulic oil) is supplied via the pressure medium inlet 4, which then flows into the lower pressure chamber 16 of the clamping cylinder 9 via the pressure medium line 17, thereby pushing the clamping piston 10 upward into its released position, as will be described in detail below.
[0067] In addition, the clamping cylinder 9 has an upper pressure chamber 18 on the upper side of the clamping piston 10 for clamping the clamping device 1. For this purpose, a pressure medium (e.g., hydraulic oil) is introduced into the upper pressure chamber 18 via the pressure medium inlet 3, a pressure medium line 19, and a pressure medium line 20, whereby the clamping piston 10 is pressed downward into its clamped position.
[0068] In its upper, released position, the clamping piston 10 is held by a self-locking clamp. During a clamping process, the downward movement of the clamping piston 10 therefore only begins when the holding force of the self-locking clamp of the clamping piston 10 in its upper, clamped position is overcome. To technically implement this self-locking clamp, the clamping piston 10 has an upwardly projecting piston rod 21 on its upper side (see Fig. 5B), which is surrounded at a shoulder by an annular conical ring 22. The conical ring 22 can be made of steel or of a material with a high coefficient of friction, for example an elastomer, in order to facilitate the self-locking clamping of the clamping piston 10 in the clamping cylinder 9. The clamping piston 10 itself, however, is made of steel. The conical ring 22 has an outer cone 23 on its outer surface, which tapers upwards, as can be seen in particular in Figure 5B.On the inner wall of the clamping cylinder 9, at the top of the clamping cylinder 9, there is a corresponding inner cone 24, which also tapers upwards, as can be seen in Figure 5B. The outer cone 23 has the same small cone angle a (cf. Figure 4B) as the inner cone 24. In the upper, released clamping position of the clamping piston 10 shown in Figure 4B, the above-mentioned self-locking clamping exists between the inner cone 24 of the clamping cylinder 9 on the one hand and the outer cone 23 of the conical ring 22 on the other hand.
[0069] Figure 4B also shows that several axial grooves 25 are located in the outer cone 23 of the conical ring 22. The axial grooves 25 allow the pressure medium (e.g., hydraulic oil) to flow downward from the pressure medium line 20 into the upper pressure chamber 18 when the clamping device 1 is clamped. The axial grooves 25 also allow the pressure medium to flow back when changing from the clamping position to the release position.
[0070] In the extension cylinder housing 5, the horizontally extendable clamping arm 6 forms an extension piston with an internal pressure chamber 26, which can be pressurized with the pressure medium (e.g. hydraulic oil) for the horizontal extension of the clamping arm 6, as will be described in detail.
[0071] In addition, the extension cylinder housing 5 contains an outer pressure chamber 27 (see Fig. 4D), which can be pressurized with the pressure medium (e.g., hydraulic oil) for horizontally retracting the clamping arm 6. For this purpose, the clamping piston 10 has a continuous axial bore 29 through which the pressure medium can flow from the lower pressure chamber 16 of the clamping cylinder 9 and a bore 30 in the extension cylinder housing 5 into the outer pressure chamber 27.
[0072] The pressure medium inlet 3 for clamping the clamping device 1 is connected via the pressure medium line 19, the pressure medium line 20, and another pressure medium line to an axial channel 31 in a pin 32, which is formed on the inside of a housing cover 28 and projects into the inner pressure chamber 26. Through this flow connection, the inner pressure chamber 26 in the clamping arm 6, which serves as an extending piston, can be pressurized with the pressure medium (e.g., hydraulic oil) in order to extend the clamping arm 6 in the horizontal direction.
[0073] The inner pressure chamber 26 and the outer pressure chamber 27 together form an extension cylinder in which the clamping arm 6 acting as an extension piston can be displaced in the horizontal direction.
[0074] An anti-twist device prevents rotation of the clamping arm 6. For this purpose, a longitudinal groove 33, into which a guide ball 34 projects, is located in the outer surface of the clamping arm 6 within the extension cylinder housing 5. The guide ball 34 is fixed in the axial and circumferential directions and engages in the longitudinal groove 33, thereby preventing rotation of the clamping arm 6. The engagement depth of the guide ball 34 is predetermined by a screw 35.
[0075] Furthermore, several seals 36, 37, 38 are arranged in the extension cylinder housing 5, as can be seen directly from the drawings.
[0076] A shaft 39 is formed on the underside of the extension cylinder housing 5, which projects downward into the clamping cylinder 9 and has an internal thread on its inside. The internal thread of the shaft 39 is screwed to an external thread on the outer surface of the piston rod 21, which projects upward from the clamping piston 10. This firmly connects the extension cylinder housing 5 to the clamping piston 10, so that the extension cylinder housing 5 follows every vertical movement of the clamping piston 10.
[0077] It should also be noted that the shaft 39 in the clamping cylinder housing 2 is sealed by a seal 40.
[0078] Furthermore, it should be mentioned that the clamping piston 10 has a hexagon socket 41 on its underside in order to be able to attach a screwing tool when the clamping piston 10 is to be screwed into the shaft 39.
[0079] In addition, the drawings show a vent line 42 in the extension cylinder housing 5 and a vent line 43 in the clamping cylinder housing 2.
[0080] The following describes a clamping process of the clamping device 1 according to the invention. It is assumed that the clamping device 1 is in the released state. On the one hand, this means that the clamping arm 6 is retracted horizontally. On the other hand, this means that the clamping piston 10, and thus also the extension cylinder housing 5 with the clamping arm 6, are at the stop in their upper position.
[0081] In this released position of the clamping device 1, the conical ring 22 with its outer cone 23 forms a self-locking clamp with the inner cone 24. This means that the clamping piston 10 is initially held in its upper, released position. This is advantageous because, during a clamping process, the clamping arm 6 should initially remain in its upper, released position until the clamping arm 6 is extended in the horizontal direction, after which the vertical clamping movement of the clamping arm 6 can begin. This self-locking clamping thus ensures the desired sequence of the initial horizontal extension movement of the clamping arm 6 and the subsequent vertical clamping movement of the clamping arm 6 during a clamping process.
[0082] A pressure medium (e.g. hydraulic oil) is then supplied via the pressure medium inlet 3, which flows via the pressure medium line 19 into the pressure medium line 20, whereby the pressure medium flow is then divided upwards and downwards.
[0083] Firstly, the pressure medium from the pressure medium line 20 and the axial groove 25 in the outer surface of the conical ring 22 enters the upper pressure chamber 18 of the clamping cylinder 9. However, the pressure of the pressure medium in the upper pressure chamber 18 is initially too low to overcome the self-locking clamping of the clamping piston 10 in its upper position. This means that the clamping piston 10 initially remains in its upper position.
[0084] Secondly, the pressure medium (e.g. hydraulic oil) flows upwards via the pressure medium line 22 into the inner pressure chamber 26 in the clamping arm 6, which serves as an extending piston. This initially extends the clamping arm 6 in a horizontal direction. Only when the clamping arm 6 is fully extended and the pressure medium pressure in the upper pressure chamber 18 of the clamping cylinder 9 continues to rise is the self-locking clamping of the clamping piston 10 in the clamping cylinder 9 overcome, so that the clamping piston 10 is moved downwards, taking the extending cylinder housing 5, along with the clamping arm 6 and the clamping iron 8, downwards with it. During this downward movement, the clamping iron 8 then eventually strikes the workpiece to be clamped, whereby the workpiece is clamped.
[0085] When clamping the clamping device 1, a specific sequence of movements is observed. First, the clamping arm 6 is fully extended in the horizontal direction. Only then does the actual vertical clamping movement begin, once the self-locking clamping of the clamping piston 10 in the clamping cylinder 9 has been overcome.
[0086] The following describes how to release the clamping device 1. It is assumed that the clamping device 1 is in the clamped state. This means that the clamping arm 6 is fully extended in the horizontal direction, while the extension cylinder housing 5 with the clamping arm 6 is largely retracted downward.
[0087] To release the clamping device 1, a pressure medium (e.g., hydraulic oil) is supplied via the pressure medium inlet 4. The pressure medium then flows via the pressure medium line 17 into the lower pressure chamber 16 of the clamping cylinder 9, causing the clamping piston 10 to move upward, thereby driving the extension cylinder housing 5 with the clamping arm 6 and the clamping iron 8 upward.
[0088] Furthermore, the pressure medium flows from the lower pressure chamber 16 of the clamping cylinder 9 through the axial bore 29 in the clamping piston 10 and thus enters the outer pressure chamber 27 of the extension cylinder. This causes the clamping arm 6 to retract horizontally.
[0089] The modified embodiment according to Figure 7 will now be described, which largely corresponds to the embodiment described above, so that in order to avoid repetition, reference is made to the above description, the same reference numerals being used for corresponding details.
[0090] A special feature of this embodiment is that the tensioning piston 10 is not held in its upper position by a self-locking clamp, but rather by a locking connection. For this purpose, the tensioning piston has an annular groove 44 on the outside into which a spring ring 45 is embedded. In the locked position shown in Figure 7, the spring ring 45 engages in an annular groove 46 in the tensioning cylinder housing 2. This forms a locking connection between the tensioning piston 10 and the tensioning cylinder housing 2. This locking connection is only released when the force acting on the tensioning piston 10 from the pressure medium in the upper pressure chamber 18 exceeds a certain limit value. This ensures that during a clamping process, the clamping arm 6 is extended horizontally first and only then is the tensioning piston 10 moved downwards with the extension cylinder housing 5.The locking connection thus ensures a specific sequence of horizontal and vertical movement during a clamping process. Figures 8A and 8B show a further modification of a clamping device 1 according to the invention, which also largely corresponds to the exemplary embodiments described above. To avoid repetition, reference is made to the above description, with the same reference numerals being used for corresponding details.
[0091] A special feature here is that a helical spring 47 is provided, which is supported on the one hand on the screw base 11 and on the other hand on the tensioning piston 10 and thus presses the tensioning piston 10 upwards.
[0092] Figure 8B also shows that the clamping piston 10 forms an annular sealing edge 48 on its upper side, which defines a relatively small annular effective surface 49 on the inside. In the upper position of the clamping piston 10, the effective surface 49 of the clamping piston 10 is therefore very small, so that a relatively high pressure of the pressure medium is required to generate a sufficiently large force to press the clamping piston 10 downwards. The helical spring 47 is therefore initially sufficient to hold the clamping piston 10 in its upper position, since the pressure medium only exerts a correspondingly small force via the small effective surface 49. This ensures that during a clamping process, the clamping arm 6 is initially extended completely in the horizontal direction.Only when this occurs does the pressure medium pressure on the top side of the clamping piston 10 rise to such an extent that a sufficiently large force can be generated across the relatively small effective area 49 to push the clamping piston 10 downward. If this occurs, the sealing edge 48 no longer acts, and the pressure medium then acts on the top side of the clamping piston 10 across the entire effective area, causing the clamping force to suddenly increase.
[0093] Figures 9A and 9B show a modification of the clamping device 1 according to the invention in the area of the extension cylinder. This modification also largely corresponds to the embodiments described above, so that, to avoid repetition, reference is made to the above description, with the same reference numerals being used for corresponding details.
[0094] The clamping device 1 is designed in such a way that when the clamping device 1 is released, the vertical extension movement of the clamping piston 10 with the extension cylinder housing 5 occurs first, and only then the horizontal retraction movement of the clamping arm 6. For this purpose, the clamping arm 6, which serves as the extension piston, has an annular shoulder that separates an outer annular active surface 50 from an inner annular active surface 51. It should be noted that the inner annular active surface 51 is significantly larger than the outer annular active surface 50. In the clamping position shown in the drawings, the clamping arm 6 is extended in the horizontal direction. This means that only the outer annular active surface 50 can be pressurized via the bore 30, while the inner annular active surface 51 is not exposed to any pressure medium.This means that in the clamping position, initially only a very low retraction force acts on the clamping arm 6, which serves as the extending piston. As a result, when the clamping device 1 is released, the vertical extension movement of the clamping piston 10 with the extending cylinder housing 5 occurs first, and only then is the clamping arm 6 retracted horizontally.
[0095] Figure 10 shows an enlarged detailed view of a further modification of a clamping device according to the invention in the area of the extension cylinder. This modification also partially corresponds to the embodiments described above, so that, to avoid repetition, reference is made to the above description, with the same reference numerals being used for corresponding details.
[0096] A special feature of this embodiment is that the clamping arm 6, which serves as the extending piston, is held in the clamped position by a self-locking clamp. For this purpose, the clamping arm 6 has an outer cone 52, while the extending cylinder has an inner cone 53. The outer cone 52 has the same cone angle as the inner cone 53, so that the outer cone 52, together with the inner cone 53, effects the self-locking clamping of the clamping arm 6 in the clamped position. This self-locking clamp ensures that when the clamping device 1 is released, the vertical extension movement of the extending cylinder housing 5 with the clamping arm 6 occurs first and only then is the clamping arm 6 retracted in the horizontal direction. The self-locking clamp therefore ensures the desired sequence of the vertical extension movement on the one hand and the horizontal retraction movement on the other hand when the clamping device 1 is released.
[0097] The invention is not limited to the preferred embodiments described above. Rather, a multitude of variants and modifications are possible, which also utilize the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, independently of the respective claims referred to, and in particular even without the features of the main claim. The invention thus encompasses various aspects of the invention that enjoy independent protection.
[0098] List of reference symbols
[0099] 1 clamping device
[0100] 2 clamping cylinder housings
[0101] 3 Pressure medium inlet for clamping the clamping device
[0102] 4 pressure medium inlets for releasing the clamping device
[0103] 5 extension cylinder housing
[0104] 6 clamping arm
[0105] 7 Clamping screw
[0106] 8 clamps
[0107] 9 clamping cylinders for clamping or releasing the clamping device
[0108] 10 clamping pistons
[0109] 11 Screw base in the base of the clamping cylinder housing
[0110] 12 Seal in the screw base
[0111] 13, 14 Blind holes in the screw base for engagement of a screwing tool for screwing in or unscrewing the screw base
[0112] 15 Seal in the tensioning piston
[0113] 16 Lower pressure chamber of the clamping cylinder for releasing the clamping device
[0114] 17 Pressure medium line from the pressure medium inlet for releasing the clamping device to the lower pressure chamber of the clamping cylinder
[0115] 18 Upper pressure chamber of the clamping cylinder for clamping the clamping device
[0116] 19 Pressure medium line from the pressure medium inlet for clamping the clamping device to the upper pressure chamber of the clamping cylinder
[0117] 20 Pressure medium line for clamping the clamping device to the upper pressure chamber of the
[0118] clamping cylinder
[0119] 21 Piston rod on the top of the tensioning piston
[0120] 22 Conical ring made of steel or a friction-increasing material (e.g. elastomer) for self-locking clamping of the clamping piston
[0121] 23 Outer cone of the cone ring
[0122] 24 Internal cone in the clamping cylinder for self-locking clamping of the clamping piston in the clamping cylinder
[0123] 25 Axial groove in the outer cone of the conical ring
[0124] 26 Inner pressure chamber of the extension cylinder for horizontal extension of the clamping arm
[0125] TI Outer pressure chamber of the extension cylinder for horizontal extension of the clamping arm
[0126] 28 Housing cover of the extension cylinder 29 Axial bore in the clamping piston for the passage of the pressure medium when releasing the clamping device
[0127] 30 Bore in the extension cylinder housing into the outer pressure chamber 27
[0128] 31 Axial channel in the pin
[0129] 32 pin on the inside of the housing cover
[0130] 33 Longitudinal groove in the extending piston to prevent rotation of the extending piston
[0131] 34 Guide ball to prevent rotation of the extension piston
[0132] 35 Screw for adjusting the engagement depth of the guide ball
[0133] 36-38 Seals on the extension piston
[0134] 39 Shaft on the underside of the extension cylinder housing
[0135] 40 Seal around the shaft
[0136] 41 Hexagon socket in the bottom of the clamping piston
[0137] 42 Vent line in the extension cylinder housing
[0138] 43 Ventilation line in the clamping cylinder housing
[0139] 44 Ring groove in the clamping piston
[0140] 45 spring ring
[0141] 46 Ring groove inside the clamping cylinder housing
[0142] 47 coil spring
[0143] 48 Sealing edge
[0144] 49 Effective surface on the top of the clamping piston
[0145] 50 Outer annular effective surface of the extending piston
[0146] 51 Inner annular effective surface of the extending piston
[0147] 52 Outer cone on the clamping arm
[0148] 53 Inner cone in the extension cylinder
Claims
CLAIMS 1. Clamping device (1) for clamping an object, in particular a workpiece or a tool, with a) a clamping arm (6) for clamping the object, in particular by means of a clamping iron (8) which is mounted on the end of the clamping arm (6), wherein the clamping arm (6) can be retracted in the clamping device (1) in the vertical direction for clamping the clamping device (1) and extended for releasing the clamping device (1), and b) a vertically oriented clamping cylinder (9) with a clamping piston (10) which can be displaced in the vertical direction in the clamping cylinder (9) and can be driven by a pressure medium for vertically retracting the clamping arm (6) when clamping the clamping device (1) and for vertically extending the clamping arm (6) when releasing the clamping device (1), characterized by c) at least one horizontally oriented extension cylinder (26, 27) with a in the extension cylinder (26,27) horizontally displaceable extension piston for extending the clamping arm (6) in the horizontal direction when clamping the clamping device (1) and for retracting the clamping arm (6) in the horizontal direction when releasing the clamping device (1).
2. Clamping device (1) according to claim 1, characterized in that a) the clamping device (1) is designed such that when the clamping device (1) is clamped, the clamping arm (6) is first extended in the horizontal direction and only then is the clamping arm (6) retracted in the vertical direction, and / or b) the clamping device (1) is designed such that when the clamping device (1) is released, the clamping arm (6) is first extended in the vertical direction and only then is the clamping arm (6) retracted in the horizontal direction.
3. Clamping device (1) according to one of the preceding claims, characterized in that a) the clamping piston (10) is frictionally fixed in the clamping cylinder (9) at its upper stop by a self-locking clamping of the clamping piston (10) in the clamping cylinder (9), and b) that when clamping the clamping device (1), the vertical retraction of the clamping arm (6) only begins when the self-locking clamping of the clamping piston (10) in the clamping cylinder (9) is overcome, c) that when the clamping device (1) is clamped, the pressure of the pressure medium acting on the upper side of the clamping piston (10) only releases the self-locking clamping of the clamping piston (10) when the pressure of the pressure medium acting on the clamping piston (10) exceeds a release pressure.
4. Clamping device (1) according to claim 3, characterized in that a) the clamping piston (10) has an outer cone (23) on its upper side which tapers towards the top, b) the clamping cylinder (9) has an inner cone (24) on its upper side which tapers towards the top, and c) the inner cone (24) of the clamping cylinder (9) together with the outer cone (23) of the chip piston effects the self-locking clamping of the clamping piston (10) on the upper stop of the clamping piston (10).
5. Clamping device (1) according to claim 4, characterized in that a) the inner cone (24) of the clamping cylinder (9) and the outer cone (23) of the clamping piston (10) have the same cone angle (a), and / or b) that the cone angle (a) is sufficiently small to effect the self-locking clamping of the clamping piston (10) at the upper stop of the clamping piston (10).
6. Clamping device (1) according to claim 4 or 5, characterized in that a) the outer cone (23) is not formed directly on the clamping piston (10), but on a conical ring (22) which surrounds the clamping piston (10) or an upwardly projecting piston rod (21) of the clamping piston (10) as a separate component, and / or b) the conical ring (22) is made of a different material than the clamping piston (10), in particular of a material with a higher coefficient of friction, and / or c) the conical ring (22) is made of an elastomer, while the clamping piston (10) is made of steel, and / or d) the outer cone (23) has an axial groove (25) extending through it in the axial direction in order to conduct the pressure medium through the axial groove (25) in the axial direction, and / or e) the axial groove (25) is formed in the outer surface of the conical ring (22) runs.
7. Clamping device (1) according to one of the preceding claims, characterized by a) a first pressure medium inlet (3) for supplying the pressure medium for tensioning the tensioning device (1), wherein the first pressure medium inlet (3) is connected both to the tensioning cylinder (9) and to the extension cylinder (26, 27), and b) a second pressure medium inlet (4) for supplying the pressure medium for releasing the tensioning device (1), wherein the second pressure medium inlet (4) is connected both to the tensioning cylinder (9) and to the extension cylinder (26, 27).
8. Clamping device (1) according to claim 7, characterized in that a) the clamping cylinder (9) has an upper pressure chamber (18) for clamping the clamping device (1) on the upper side of the clamping piston (10), b) the upper pressure chamber (18) of the clamping cylinder (9) is connected to the first pressure medium connection (3), c) that the clamping cylinder (9) has a lower pressure chamber (16) on the underside of the clamping piston (10) for releasing the clamping device (1), d) that the lower pressure chamber (16) of the clamping cylinder (9) is connected to the second pressure medium inlet (4) is connected, and e) that the clamping piston (10) has an axially through bore (29) in order to guide the pressure medium from the lower pressure chamber (16) of the clamping cylinder (9) into the extension cylinder (26, 27) when the clamping device (1) is released, so that the lower pressure chamber (16) of the clamping cylinder (9) and the extension cylinder (26, 27) are simultaneously pressurised with the pressure medium for releasing the clamping device (1).
9. Clamping device (1) according to claim 8, characterized in that a) the extending cylinder (26, 27) has an inner pressure chamber (26) for extending the clamping arm (6) in the horizontal direction, b) the extending cylinder (26, 27) has an outer pressure chamber (27) for retracting the clamping arm (6) in the horizontal direction, c) the through-bore (29) in the clamping piston (10) is connected to the outer pressure chamber (27) of the extending cylinder (26, 27), so that when the clamping device (1) is released, the lower pressure chamber (16) of the clamping cylinder (9) and the outer pressure chamber (27) of the extending cylinder (26, 27) are simultaneously pressurized with the pressure medium, and d) the first pressure medium inlet (3) for clamping the clamping device (1) is connected via a pressure medium line (19, 20, 31) is connected to the inner pressure chamber (26) of the extension cylinder (26, 27),so that when the clamping device (1) is tightened, the upper pressure chamber (18) of the clamping cylinder (9) and the inner pressure chamber (26) of the extension cylinder (26, 27) simultaneously, be subjected to pressure.
10. Clamping device (1) according to one of the preceding claims, characterized in that a) the clamping device (1) has an anti-rotation device (33-35) which prevents rotation of the extending piston (6) in the extending cylinder (26, 27), and b) the anti-rotation device (33-35) has a longitudinal groove (33) which is arranged in the outer surface of the extending piston (6) and runs in the horizontal direction, and c) the anti-rotation device (33-35) has a guide ball (34) which is arranged in the extending cylinder (26, 27) in a fixed position in the axial direction and in the circumferential direction and engages in the longitudinal groove (33) and thereby prevents rotation of the extending piston relative to the extending cylinder (26, 27), and d) the guide ball (34) engages with a specific engagement depth in the longitudinal groove (33) in the extending piston (6), wherein the guide ball (34) is preferably held in the longitudinal groove (33) with a screw (35),wherein the screw (35) is preferably sealed with a sealing ring, in particular with a Usit ring., 11. Clamping device (1) according to one of the preceding claims, characterized in that a) the clamping device (1) has a clamping cylinder housing (2) which encloses the clamping cylinder (9) and the clamping piston, b) that the clamping device (1) has an extension cylinder housing (5) which contains the extension cylinder (26, 27) and the extension piston, c) that the extension cylinder housing (5) has a shaft (39) which projects downwards from the extension cylinder housing (5) and projects into the clamping cylinder (9) of the clamping cylinder housing (2), d) that the shaft (39) has an internal thread, e) that the clamping piston (10) has a piston rod (21) which projects upwards from the clamping piston (10) and projects into the shaft (39), f) that the upwardly projecting piston rod (21) of the clamping piston (10) has an external thread, and g) that the upwardly projecting piston rod (21) of the clamping piston (10) is screwed with its external thread to the internal thread of the shaft (39), so that the clamping piston (10) carries the extension cylinder housing (5) in the vertical direction when clamping and releasing the clamping device (1), h) that the clamping piston (10) optionally has an engagement (41) for a wrench on its underside, in particular a hexagon socket (41), in order to clamp the clamping piston (10) in screw the internal thread into the shaft (39).
12. Clamping device (1) according to one of the preceding claims, characterized in that a) the extending cylinder (26, 27) is laterally closed by a housing cover (28) on the side opposite the clamping arm (6), b) the extending piston (6) has a horizontal blind bore (26) on the side facing the housing cover (28), which forms the inner pressure chamber (26) of the extending cylinder (26, 27), c) a pin (32) is formed on the inside of the housing cover (28) of the extending cylinder (26, 27), which pin projects horizontally into the blind bore (26) in the extending piston (6), and / or d) the pin (32) has an axial channel (31) which opens into the blind bore (26) in order to introduce the pressure medium into the blind bore (26) for extending the clamping arm (6).
13. Clamping device (1) according to one of the preceding claims, characterized in that a) the clamping piston (10) is fixed in its released position by a locking connection (44-46) in the clamping cylinder (9), and b) that the locking connection (44-46) is located between the clamping piston (10) and the clamping cylinder (9) only releases during clamping when the pressure of the pressure medium in the clamping cylinder (9) exceeds a certain limit value, so that when the clamping device (1) is clamped, the clamping arm (6) is first extended in the horizontal direction and only then is the clamping arm (6) retracted in the vertical direction, c) that the locking connection preferably comprises a locking groove (46) in the cylinder surface of the clamping cylinder (9) and a spring ring (45) in the outer surface of the clamping piston (10).
14. Clamping device (1) according to one of claims 1 to 3, characterized in that a) the clamping piston (10) is pressed into its released position in the vertical direction by a spring (47), in particular by a helical spring (47), and b) that the clamping piston (10) in its released position offers the pressure medium a substantially smaller contact surface (49) than in its tensioned position, so that the clamping piston (10) is held in its released position as long as the force acting on the tensioning piston (10) by the pressure medium is smaller than the force acting on the tensioning piston (10) by the spring acting force, so that when the clamping device (1) is clamped, the clamping arm (6) is first extended in the horizontal direction and only then is the clamping arm (6) retracted in the vertical direction, c) that the clamping piston (10) preferably has an annular sealing edge (48) which, in the released position of the clamping piston (10), limits the smaller contact surface (49) for the pressure medium.
15. Clamping device (1) according to one of the preceding claims, characterized in that the extending piston (6) in its horizontally extended position offers the pressure medium a smaller contact surface (50) than in its horizontally retracted position, so that when the clamping device (1) is released, the clamping arm (6) is first extended in the vertical direction and only then is the clamping arm (6) retracted in the horizontal direction.
16. Clamping device (1) according to one of the preceding claims, characterized in that a) the extending piston (6) is frictionally fixed in the horizontally extended position of the clamping arm (6) by a self-locking clamp in the extending cylinder (26, 27), and b) that when the clamping device (1) is released, the horizontal retraction of the clamping arm (6) only begins when the self-locking clamp of the extending piston (6) in the extending cylinder (26, 27) has been overcome, so that when the clamping device (1) is released, the clamping arm (6) is first extended in the vertical direction and only then is the clamping arm (6) retracted in the horizontal direction.
17. Clamping device (1) according to claim 16, characterized in that a) the extending piston (6) has an outer cone (52) which tapers in the horizontal direction towards the end of the clamping arm (6), b) the extending cylinder (26, 27) has an inner cone (53) which tapers in the horizontal direction towards the end of the clamping arm (6), and c) the inner cone (53) of the extending cylinder (26, 27) together with the outer cone (52) of the extending piston (6) effects the self-locking clamping of the extending piston (6) in the horizontally extended state of the clamping arm (6).
18. Clamping device (1) according to claim 17, characterized in that a) the inner cone (53) of the extending cylinder (26, 27) and the outer cone (52) of the extending piston (6) have the same cone angle, and / or b) that the cone angle is sufficiently small to ensure self-locking clamping of the extending piston (6) when the clamping arm (6) is in the horizontally extended state.
19. Clamping device (1) according to one of the preceding claims, characterized in that a) the clamping iron (8) is screwed to the end of the clamping arm (6) by means of a fastening screw (7), and / or b) the extending piston (6) and the clamping arm (6) are formed in one piece, and / or c) the pressure medium is a hydraulic oil or compressed air.