Clamping device for clamping a workpiece

Abstract

The invention relates to a clamping device (100) for clamping a workpiece (200) with a threaded spindle (110) extending along a spindle longitudinal axis (310) and comprising a first threaded section (112) with a first thread pitch and a second threaded section (114) with a second thread pitch that differs from the first thread pitch, wherein a first spindle nut (130) engages with the first threaded section (112) and wherein a second spindle nut (140) engages with the second threaded section (114), as well as with a guide rail (160) extending parallel to the spindle longitudinal axis (310) and on which the threaded spindle (110) is rotatably mounted, wherein the first spindle nut (130) is linearly movable and rotationally fixed on the guide rail (160), with a clamping arm (150),which is pivotably mounted about a second pivot axis (302) on the second spindle nut (140) and with a connecting device which is pivotably mounted about a first pivot axis (301) on the first spindle nut (130) and pivotably mounted about a third pivot axis (303) on the clamping arm (150), wherein the first, second and third pivot axes (301; 302; 303) are aligned parallel to each other and wherein the third pivot axis (303) is spaced apart from the second pivot axis (302).

Description

[0001] The invention relates to a clamping device for clamping a workpiece.

[0002] In workpiece manufacturing, toggle clamps are known as clamping devices for clamping workpieces for safe machining. Toggle clamps offer the advantage of being able to clamp quickly and over a wide angle range. Furthermore, high clamping forces can be achieved with toggle clamps.

[0003] The state of the art includes various clamping devices, including toggle clamps.

[0004] For example, DE 10 2021 000 171 B3 describes a toggle clamping device using a threaded spindle driven by an electric motor. The spindle, in turn, drives a joint nut, which is connected via a guide carriage moving in a guide groove to a toggle joint assembly coupled to a pivoting workpiece clamping arm. However, the clamping device only has a joint nut, which is moved along the threaded spindle with a threaded section of constant pitch.

[0005] The documents JP 2006-116670 A, CN 1 12 404 874 A, and CN 1 13 263 341 A also disclose clamping devices using a toggle lever mechanism in conjunction with a threaded spindle. Although the devices in the documents CN 1 12 404 874 A and CN 1 13 263 341 A generally use threaded spindles with sections of different pitches, only one threaded spindle or a section of the threaded spindle with one pitch is always engaged for the clamping process of the toggle lever mechanism itself.

[0006] In comparison, the prior art also shows various devices that use threaded spindles with multiple threaded sections of different pitches to move device elements, with several of these threaded sections participating in the clamping or movement process. For example, the document DE 43 28 844 A1 discloses an injection molding machine with a mold clamping unit whose tool carrier plate is driven by a ball screw nut with a toggle lever system mounted on a threaded spindle. The threaded spindle has two threaded sections with different pitches, with the threaded section with the larger pitch being used to apply the closing movement, and the threaded section with the smaller pitch being used to increase the clamping force.

[0007] Document CN 1 10 316 676 A discloses a device for gripping and sorting books for use in libraries, the device providing a gripping mechanism which also uses a threaded spindle with two different thread sections of different pitch.

[0008] In addition, publication CN 2 04 321 688 U shows a differential clamping element, whereby the clamping process is also realized here by a threaded element with two thread sections of different pitch.

[0009] The object of the present invention is to provide a clamping device with which workpieces can be securely clamped during a large number of clamping operations.

[0010] This task is solved by a clamping device for clamping a workpiece with the following features: A clamping device according to the invention for clamping a workpiece comprises a threaded spindle which runs along a spindle longitudinal axis and which has a first threaded section with a first thread pitch and a second threaded section with a second thread pitch which is designed differently from the first thread pitch, wherein a first spindle nut engages with the first threaded section and wherein a second spindle nut engages with the second threaded section, as well as a guide rail which extends parallel to the spindle longitudinal axis and on which the threaded spindle is rotatably mounted, wherein the first spindle nut is mounted on the guide rail for linear movement and in a rotationally fixed manner, a clamping arm which is mounted on the second spindle nut for pivot movement about a second pivot axis, and a connecting device,which is pivotally mounted on the first spindle nut about a first pivot axis and pivotally mounted on the clamping arm about a third pivot axis, wherein the first, second and third pivot axes are aligned parallel to one another and wherein the third pivot axis is arranged at a distance from the second pivot axis.

[0011] The first spindle nut and the second spindle nut each have an internal thread corresponding to the respective threaded section. Since the first thread pitch and the second thread pitch are designed differently from one another, it is not possible to engage the first spindle nut with the second threaded section. Furthermore, it is not possible to engage the second spindle nut with the first threaded section. Thus, when the first threaded section and the second threaded section are adjacent to one another, it is not possible for the first spindle nut to transition to the second threaded section. Furthermore, it is not possible for the second spindle nut to transition to the first threaded section.

[0012] The threaded spindle can be mounted directly on the guide rail. For this purpose, a pivot bearing can be formed on the guide rail, which is designed to rotatably support the threaded spindle about the spindle's longitudinal axis, also referred to as the rotational axis. The pivot bearing also ensures a fixed coupling between the threaded spindle and the guide rail, so that the threaded spindle has a single rotational degree of freedom relative to the guide rail and no translational degree of freedom. Alternatively, the pivot bearing can be formed on another component of the clamping device, for example, a drive device for the clamping device, and this other component can be coupled directly or indirectly to the guide rail.Here, too, it is to be provided that the first spindle nut has no rotational degree of freedom relative to the guide rail and has only a single translational degree of freedom with the linear mobility along the spindle longitudinal axis.

[0013] The second spindle nut is also secured against rotation with respect to the guide rail. This is achieved in particular by the connecting device connecting the first spindle nut to the second spindle nut preventing rotation of the second spindle nut relative to the first spindle nut with respect to the spindle's longitudinal axis.

[0014] The clamping arm is mounted on the second spindle nut, pivoting between an open position and a clamping position about the second pivot axis. In the open position, the clamping arm is spaced from the workpiece. This allows a workpiece to be clamped to be positioned beneath the clamping arm, or a previously clamped workpiece to be removed from the clamping device. In the clamping position, the clamping arm is pressed onto the workpiece, clamping it, for example, against a base.

[0015] Since the first threaded section and the second threaded section are both part of the same threaded spindle, when the threaded spindle rotates about the spindle's longitudinal axis, the first spindle nut is moved along the first threaded section and the second spindle nut is moved along the second threaded section. As a result, the connecting device, which is mounted on the first spindle nut and on the clamping arm, is pivoted simultaneously about the first pivot axis and the third pivot axis. In the process, the distance between the first pivot axis and the third pivot axis is changed perpendicular to the spindle's longitudinal axis. If the first spindle nut and the second spindle nut are brought closer together, the connecting device is aligned more and more perpendicular to the spindle's longitudinal axis. As a result, the distance between the first pivot axis and the third pivot axis is increased perpendicular to the spindle's longitudinal axis.This in turn pivots the clamping arm, which is coupled to the connecting device, about the second pivot axis. If the distance between the first pivot axis and the third pivot axis is increased, the clamping arm is increasingly aligned perpendicular to the longitudinal spindle axis. This means that the connecting device and the clamping arm are increasingly parallelized. The first spindle nut is preferably arranged above the second spindle nut. In this way, when the first spindle nut is lowered, the connecting device and the clamping arm are aligned perpendicular to the longitudinal spindle axis, while when the first spindle nut is raised, the connecting device and the clamping arm are aligned along the longitudinal spindle axis.

[0016] By moving the second spindle nut along the second threaded section, the clamping arm, which is mounted on the second spindle nut, moves along the spindle's longitudinal axis. Consequently, when the second spindle nut is moved upwards, the clamping arm also moves upwards, and when the second spindle nut is moved downwards, it also moves downwards. "Up" refers to the direction away from the workpiece to be clamped, and "down" refers to the direction toward the workpiece to be clamped.

[0017] Since the first threaded section and the second threaded section have different thread pitches, the first spindle nut and the second spindle nut are moved different distances along the spindle's longitudinal axis when the threaded spindle rotates.

[0018] The first thread section can also differ from the second thread section in terms of the thread direction (right-hand thread, left-hand thread).

[0019] If the first threaded section and the second threaded section have the same thread direction, the first spindle nut and the second spindle nut are moved in the same direction, i.e., either both move upwards at the same time or downwards at the same time. If the first threaded section and the second threaded section have different thread directions, the first spindle nut and the second spindle nut are moved in opposite directions, i.e., either the first spindle nut is moved upwards while the second spindle nut is moved downwards, or the first spindle nut is moved downwards while the second spindle nut is moved upwards.

[0020] Further features developing the invention are the subject of the dependent claims with the features listed below: Preferably, a drive device is provided with which the threaded spindle can be driven.

[0021] Preferably, the drive device comprises an electric motor and a current monitor for monitoring the torque applied by the electric motor. The current monitor can, for example, be part of a control device associated with the electric motor, which, among other things, controls the motor torque. This control device, in turn, can be part of a higher-level control system that enables automated operation of the clamping device.

[0022] Preferably, the first threaded section has a greater pitch than the second threaded section. Upon rotation of the threaded spindle, the first spindle nut therefore travels a first distance that is greater than a second distance traveled by the second spindle nut during this rotation. In this way, the clamping arm can cover a large pivoting angle range due to the movement of the first spindle nut and the gear action of the connecting device, while it is only displaced a short distance along the spindle's longitudinal axis due to the shorter second distance traveled by the second spindle nut.

[0023] Furthermore, it is preferably provided that the first threaded section and the second threaded section have the same thread direction. By displacing the second spindle nut downwards and thus the clamping arm also downwards, i.e., in the direction of the workpiece to be clamped, the clamping force applied to the workpiece is increased. A small thread pitch is advantageous for this purpose, as a high clamping force can be generated with a low drive torque applied to the threaded spindle. With regard to the first threaded section, a large thread pitch is advantageous, as this allows the clamping arm to be pivoted quickly.

[0024] If the first threaded section has a larger thread pitch than the second threaded section, it is preferably provided that the first threaded section is longer than the second threaded section.

[0025] Preferably, the second threaded section is self-locking. This means that no torque is required to maintain the set position, particularly the clamping position. If a drive device is provided, this no longer requires any drive power to maintain a position, particularly the clamping position.

[0026] It is preferably provided that the first threaded section has a pitch in the centimeter range, preferably in a range of 1 to 100 cm, particularly preferably in a range of 2 to 50 cm.

[0027] It is preferably provided that the second threaded section has a pitch in the centimeter range, preferably in a range of 1 to 100 cm, particularly preferably in a range of 2 to 50 cm.

[0028] Preferably, the guide rail has a groove in which a guide section of the first spindle nut is received for linear movement. The guide section is linearly movable relative to the spindle's longitudinal axis.

[0029] Furthermore, it is preferably provided that the groove has an undercut, which, together with the guide section, is formed in such a way that the guide section is prevented from sliding out of the guide rail in a spatial direction transverse to the spindle's longitudinal axis. It is particularly preferably provided that a profiling of the guide section in a cross-sectional plane oriented perpendicular to the spindle's longitudinal axis corresponds to a profiling of the groove formed in the guide rail. Purely by way of example, the groove is designed as a T-slot or dovetail slot.

[0030] Preferably, the first threaded section and the second threaded section are separated from each other by a threadless shoulder of the threaded spindle. This prevents the first spindle nut and / or the second spindle nut from moving into the other threaded section at the end of the associated threaded section and jamming the respective spindle nut in the non-associated threaded section.

[0031] Preferably, the clamping arm further comprises a first arm section and a second arm section, between which a recess is arranged extending through the clamping arm, wherein the first arm section and the second arm section preferably at least partially enclose the second spindle nut. This allows the required installation space and material expenditure to be reduced.

[0032] It is preferably provided that the connecting device has a first coupling arm and a second coupling arm, wherein preferably the first coupling arm and the second coupling arm are aligned parallel to one another, wherein preferably the first coupling arm and the second coupling arm enclose the tensioning arm.

[0033] Preferably, an adjustment device is provided with which the threaded spindle and preferably the guide rail are height-adjustable relative to a base plate along the longitudinal axis of the spindle, so that in the clamping position, the connecting device and / or the clamping arm is / are aligned perpendicular to the longitudinal axis of the spindle. In this way, the clamping device can be adapted to workpieces with different heights, i.e., extensions along the longitudinal axis of the spindle.

[0034] It is expedient if the first spindle nut is designed such that the third pivot axis is located in a pivot plane oriented transversely to the spindle longitudinal axis, which is arranged at a distance from the first spindle nut in the direction of the second spindle nut. Since the first spindle nut engages with the first threaded portion not just at one point, but over an engagement length extending along the spindle longitudinal axis, the aforementioned distance refers to the center point of this engagement length. It is preferably provided that a distance between a first end face of the first spindle nut, which is arranged opposite the second spindle nut, and the pivot plane is dimensioned such that the pivot plane in the clamping position also includes the first pivot axis and the second pivot axis.

[0035] Furthermore, it is preferably provided that the first pivot axis and / or the third pivot axis are spaced from the spindle longitudinal axis.

[0036] The invention is explained in more detail below with reference to the accompanying drawing, which shows Fig. 1 a clamping device in a clamping position in an isometric view obliquely from above, Fig. 2 which in Fig. 1 clamping device shown in the clamping position in a side view, Fig. 3 which in the Fig. 1 and Fig. 2 shown clamping device in an open position in a side view, Fig. 4 which in the Fig. 1 to 3 shown clamping device in a half-open position in a side view, Fig. 5 which in the Fig. 1 to 4 shown clamping device in a further clamping position 330, and Fig. 6 a detail of the Fig. 1 to 5 shown clamping device.

[0037] Fig. 1 shows a clamping device 100 in an isometric view obliquely from above. The clamping device 100 has a threaded spindle 110 that runs along a spindle longitudinal axis 310. The threaded spindle 110 has a first threaded portion 112 and a second threaded portion 114. The threaded spindle 110 further has a thread-free shoulder 116 that is arranged between the first threaded portion 112 and the second threaded portion 114. The shoulder 116 is in the Fig. 1 is obscured by the first spindle nut 130. The threaded spindle 110 is designed to be rotatable about the spindle longitudinal axis 310. Preferably, a drive device 120 is provided which is coupled to the threaded spindle 110 and with which the threaded spindle 110 can be driven. The clamping device 100 further comprises a first spindle nut 130 and a second spindle nut 140. Purely by way of example, the first spindle nut 130 is arranged with respect to the spindle longitudinal axis 310 and the Fig. 1 shown view above the second spindle nut 140.

[0038] Also purely exemplary is the first threaded section 112 in relation to the spindle longitudinal axis 310 and the Fig. 1, is arranged above the second threaded portion 114. The first spindle nut 130 is engaged with the first threaded portion 112. The second spindle nut 140 is engaged with the second threaded portion 114. The clamping device 100 further comprises a clamping arm 150. The clamping device 100 further comprises a connecting device. Preferably, the connecting device comprises a first coupling arm 172 and a second coupling arm 174. The second coupling arm 174 is in the Fig. 1 shown view, but is shown in the Fig. 2 to 4 are visible. The first coupling arm 172 and the second coupling arm 174 are located on the outside of the clamping arm 150 on opposite sides thereof and thus enclose it.

[0039] The clamping arm 150 is pivotally connected to the connecting device about a first pivot axis 301 and is thus preferably pivotally connected to the first coupling arm 172 and the second coupling arm 174 about the first pivot axis 301. The clamping arm 150 preferably has a first arm portion 154 and a second arm portion 156. A recess 158 is preferably located between the first arm portion 154 and the second arm portion 156. The second spindle nut 140 is preferably arranged at least partially in the recess 158, so that the first arm portion 154 and the second arm portion 156 at least partially enclose the second spindle nut 140.

[0040] The clamping arm 150 is pivotally connected to the second spindle nut 140 about a second pivot axis 302. Preferably, the second pivot axis 302 intersects the spindle longitudinal axis 310. Thus, particularly in the clamping position 330, a clamping force transmitted by the clamping arm 150 to the second spindle nut 140 can be prevented from leading to tilting or canting of the second spindle nut 140 relative to the second threaded portion 114. Preferably, the first spindle nut 130 is pivotally connected to the connecting device about a third pivot axis 303. Preferably, the first coupling arm 172 and the second coupling arm 174 are pivotally connected to the first spindle nut 130 about the third pivot axis 303. Preferably, the first pivot axis 301 and the third pivot axis 303 are arranged on opposite sides with respect to the spindle longitudinal axis 310.The first pivot axis 301, second pivot axis 302, and third pivot axis 303 are purely geometric axes. To ensure the respective pivoting capabilities, corresponding physical axes are provided, which, however, are not provided with reference symbols.

[0041] In the Fig. 1, the clamping device 100 is in a clamping position 330. In the clamping position 330, the clamping arm 150 presses onto a workpiece 200. Preferably, the clamping arm 150 presses onto the workpiece 200 from above, i.e. onto an upper side of the workpiece 200. The workpiece 200 preferably rests with an underside on a base plate 190, against which the workpiece 200 is clamped with the clamping arm 150. It is preferably provided that a distance between a first end face of the first spindle nut 130, which is arranged opposite the second spindle nut 140, and a pivot plane, which is oriented transversely to the spindle longitudinal axis 310, is dimensioned such that the pivot plane in the clamping position 330 includes the first pivot axis 301, the second pivot axis 302 and the third pivot axis 303.To make this possible, it is preferably provided that the pivot plane and thus the third pivot axis 303 is arranged at a distance from the first spindle nut 130 in the direction of the second spindle nut 140. Since the first spindle nut 130 engages with the first threaded portion 112 not just at one point, but over an engagement length extending along the spindle longitudinal axis 310, a distance 340, with which the aforementioned spacing between the pivot plane and the second spindle nut 140 is quantified, is related to the center of this engagement length. Preferably, the first spindle nut 130 and the second spindle nut 140 are designed such that the first spindle nut 130 engages the second spindle nut 140 as in . Fig. 2 shown can be driven behind.

[0042] Preferably, the clamping arm 150 is designed to introduce a clamping force into the workpiece 200 in the clamping position 330 in a substantially point-like manner. For this purpose, the clamping arm 150 preferably has a clamping finger 152 with which the clamping arm 150 contacts the workpiece 200 in the clamping position 330. The clamping finger 152 is preferably L-shaped. In this context, "substantially point-like" means that the clamping force is introduced only via a single contact surface that is small compared to the surface of the workpiece 200 facing the clamping arm 150. In this way, the clamping force can be reliably introduced into the workpiece 200 regardless of the orientation of the clamping arm 150 to the relevant surface of the workpiece 200. Preferably, the workpiece 200 to be clamped is aligned such that the surface of the clamping arm 150 that contacts the workpiece 200 is aligned parallel to the relevant surface of the workpiece 200.If the workpiece 200 to be clamped has a non-planar, e.g. round, contour on the part of the surface facing the clamping arm 150 and / or on the part of the surface facing the base against which the workpiece 150 is clamped, corresponding counterparts can be introduced between the part of the surface facing the clamping arm 150 and / or the part of the surface facing the base and the workpiece 150, which have a planar surface on the outside.

[0043] To ensure the pivotability of the clamping arm 150 about the first pivot axis 301, it is preferably provided that the first arm section 154 is pivotally connected to the first coupling arm 172 by a first axis (not provided with a reference symbol), and that the second arm section 156 is pivotally connected to the second coupling arm 174 by a second axis (not provided with a reference symbol). Alternatively, it is provided that the first arm section 154 and the second arm section 156 are pivotally connected to the first coupling arm 172 and the second coupling arm 174 via a common axis. Preferably, the separate axes do not extend through the recess 158.In this way, the first pivot axis 301 can be arranged close to the second spindle nut 140 and thus close to the second pivot axis 302, without the separate axes colliding with the second spindle nut 140 when the clamping arm 150 is pivoted relative to the second spindle nut 140 about the second pivot axis.

[0044] The clamping device 100 also has a guide rail 160, with which the first spindle nut 130 is guided along the spindle longitudinal axis 310. The first spindle nut 130 is mounted in the guide rail 160 for linear movement and rotation therewith. The guide rail 160 preferably has a groove 162 in which a guide section 132 of the first spindle nut 130 is received. The groove 162 preferably has an undercut into which the guide section 132 projects. In this way, the guide section 132 can be prevented from sliding out of the guide rail 160 in a spatial direction transverse to the spindle longitudinal axis 310. Particularly preferably, it is provided that a profiling of the guide section 132 in a cross-sectional plane oriented normal to the spindle longitudinal axis 310 corresponds to a profiling of the groove 162 formed in the guide rail 160. Purely exemplary, in Fig. 1 the groove 162 is shown as a T-slot.

[0045] Preferably, the clamping device 100 comprises an adjusting device 180 on which the drive device 120 and the guide rail 160 are mounted. The adjusting device 180 is configured to adjust the position of the drive device 120 and the guide rail 160 and thus of the threaded spindle 110 and the components arranged directly or indirectly thereon, in particular of the clamping arm 150, in relation to the spindle longitudinal axis 310 in accordance with the extension of the workpiece 200 along the spindle longitudinal axis 310. Preferably, the adjusting device 180 is adjusted to the workpiece 200 to be clamped in such a way that in the Fig. 1 and Fig. 2, the clamping arm 150 and the first coupling arm 172 and the second coupling arm 174 are aligned perpendicular to the spindle longitudinal axis 310 (see also Fig. 2).

[0046] Preferably, the adjustment device 180 is mounted on the base plate 190.

[0047] Fig. 2 shows the Fig. 1 shows a side view of the clamping device 100. As in Fig. 1, the clamping device 100 is located in the Fig. 2 shown view in the clamping position 330. In Fig. 2 it can be seen that it is preferably provided that the adjusting device 180 has an upper plate 184, a lower plate 186 and a plurality of adjusting cylinders 182 arranged between the upper plate 184 and the lower plate 186. In the Fig. 2 to 4, three adjustment cylinders 182 are shown purely by way of example. The adjustment cylinders 182 are configured to adjust the distance between the upper platen 184 and the lower platen 186 along the spindle's longitudinal axis 310. For this purpose, the adjustment cylinders 182 can be extended to increase the distance between the upper platen 184 and the lower platen 176, so that workpieces 200 can be clamped that have a large extension along the spindle's longitudinal axis 310. Furthermore, the adjustment cylinders 182 can be retracted to reduce the distance between the upper platen 184 and the lower platen 176, so that workpieces 200 can be clamped that have a small extension along the spindle's longitudinal axis 310. Alternatively or in addition to the adjustment cylinders 182, further adjustment components can be provided, for example, scissor-type or telescopic joints.

[0048] Fig. 3 shows the Fig. 1 and Fig. 2 in an open position 320. In the open position 320, the first spindle nut 130 and the second spindle nut 140 are each located at the upper end of their associated threaded section 112, 114. At the same time, the connecting device and accordingly the first coupling arm 172 and the second coupling arm 174 are pivoted downwards to their maximum extent about the third pivot axis 303, so that the distance between the third pivot axis 303 and the first pivot axis 301 is minimized. As a result, the clamping arm 150 is pivoted upwards to its maximum extent with respect to the second pivot axis 302. At the same time, the clamping arm 150 as a whole is moved upwards to its maximum extent, since the second spindle nut 140 and thus the second pivot axis 302 as such have moved upwards to their maximum extent. In the open position 320, the workpiece 200 can be positioned with respect to the clamping device 100 in order to then clamp it, or removed from the clamping device 100.

[0049] Fig. 4 shows the Fig. 1 and Fig. 2 shown clamping device 100 in an exemplary half-open position 322. In the Fig. In the half-open position 322 shown in Figure 4, the first spindle nut 130 and the second spindle nut 140 are each located substantially in the center of their respective associated threaded portions 112, 114. Accordingly, the connecting device and the clamping arm 150 are each located in a pivot position which lies between the pivot positions corresponding to the open position and the pivot positions corresponding to the clamping position.

[0050] If, for example, no adjustment device 180 is provided and a workpiece 200 is provided which extends further along the spindle longitudinal axis 310 than the workpiece 200 shown in the Fig. 1 to 4 shown workpiece 200, the Fig. 4 can be used as the clamping position 330. In such a clamping position 330, as shown in Fig. 5, the connecting device and the clamping arm 150 - as in connection with Fig. 4 - unlike the one described in the Fig. 1 and Fig. 2 shown clamping position 330 is not aligned perpendicular to the spindle longitudinal axis 310. In order for the clamping finger 152 to still rest on the workpiece 200 in this pivoting position of the clamping arm 150 without said workpiece colliding with the remaining part of the clamping arm 150, the workpiece 200 must be moved further away from the clamping device 100 than in the Fig. 1 to 4. Overall, this results in a less secure clamping of the workpiece 200 than in the configurations shown in the Fig. 1 and Fig. 2 shown configuration.

[0051] Fig. 6 shows a detail of the Fig.1 to 5. Preferably, the drive device 120 comprises an electric motor 122 coupled to the threaded spindle 110. Thus, the threaded spindle 110 can be driven in rotation by the electric motor 122. The drive device 120 further comprises a current monitor 124, which monitors the torque applied by the electric motor 122.

Claims

[1] Clamping device (100) for clamping a workpiece (200) with a threaded spindle (110) which runs along a spindle longitudinal axis (310) and which has a first threaded portion (112) with a first thread pitch and a second threaded portion (114) with a second thread pitch which is designed differently from the first thread pitch, wherein a first spindle nut (130) is in engagement with the first threaded portion (112) and wherein a second spindle nut (140) is in engagement with the second threaded portion (114), and with a guide rail (160) which extends parallel to the spindle longitudinal axis (310) and on which the threaded spindle (110) is rotatably mounted, wherein the first spindle nut (130) is mounted on the guide rail (160) in a linearly movable and rotationally fixed manner, with a clamping arm (150) which is pivotally movable about a second pivot axis (302) on the second Spindle nut (140) is mounted and provided with a connecting device,which is pivotally mounted about a first pivot axis (301) on the first spindle nut (130) and pivotally mounted about a third pivot axis (303) on the clamping arm (150), wherein the first, second and third pivot axes (301; 302; 303) are aligned parallel to one another and wherein the third pivot axis (303) is arranged at a distance from the second pivot axis (302). [2] Clamping device (100) according to claim 1, characterized by that a drive device (120) is provided with which the threaded spindle (110) can be driven. [3] Clamping device (100) according to claim 2, characterized by that the drive device (120) has an electric motor (122) and a current monitor (124) for monitoring the torque applied by the electric motor (122). [4] Clamping device (100) according to one of the preceding claims, characterized bythat the first threaded section (112) has a greater pitch than the second threaded section (114). [5] Clamping device (100) according to one of the preceding claims, characterized by that the first threaded portion (112) and the second threaded portion (114) have the same thread direction. [6] Clamping device (100) according to one of the preceding claims, characterized by that the guide rail (160) has a groove (162) in which a guide section (132) of the first spindle nut (130) is received in a linearly movable manner. [7] Clamping device (100) according to one of the preceding claims, characterized by that the first threaded section (112) and the second threaded section (114) are separated from one another by means of a thread-free shoulder (116) of the threaded spindle (110). [8] Clamping device (100) according to one of the preceding claims, characterized bythat the clamping arm (150) further comprises a first arm portion (154) and a second arm portion (156), between which a recess (158) passing through the clamping arm (150) is arranged, wherein preferably the first arm portion (154) and the second arm portion (156) at least partially enclose the second spindle nut (140). [9] Clamping device (100) according to one of the preceding claims, characterized by that the connecting device has a first coupling arm (172) and a second coupling arm (174), wherein preferably the first coupling arm (172) and the second coupling arm (174) are aligned parallel to one another, wherein preferably the first coupling arm (172) and the second coupling arm (174) enclose the tensioning arm (150). [10] Clamping device (100) according to one of the preceding claims, characterized bythat an adjusting device (180) is provided with which the threaded spindle (110) and preferably the guide rail (160) is / are adjustable in height relative to a base plate (190) along the spindle longitudinal axis (310), so that in the clamping position (330) the connecting device and / or the clamping arm (150) is / are aligned perpendicular to the spindle longitudinal axis (310). [11] Clamping device (100) according to one of the preceding claims, characterized by that the first spindle nut (130) is designed such that the third pivot axis (303) is located in a pivot plane oriented transversely to the spindle longitudinal axis (310), which is arranged at a distance from the first spindle nut (130) in the direction of the second spindle nut (140).

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