Clamping device and testing device

Abstract

Clamping device (1) for clamping or gripping an object, comprising - a base body (11) which has an interface (111) for connection with a working or testing machine, wherein the base body (11) extends along a central axis (MA) and has at least four pairs of opposing guides (112) which extend radially to the central axis (MA), - at least four clamping elements (12), one of which is at least partially inserted into a guide (112), wherein the guide (112) holds and guides the clamping element (12) with one linear degree of freedom radially to the central axis (MA), and the clamping element (12) has at least one coupling surface (121) which is oriented inclined to the central axis (MA), - at least two coupling elements (13a, 13b), each of which is kinematically coupled to two clamping elements (12) radially opposite each other to the central axis (MA), wherein the coupling element (13a, 13b) has two transmission elements (131) spaced apart from each other radially to the central axis (MA), which extend at least partially tangentially to the circumferential direction around the central axis (MA), wherein each transmission element (131) is in contact with or can be brought into contact with a coupling surface (121) of a clamping element (12), and wherein the two coupling elements (13a, 13b) are movably mounted independently of each other in a direction parallel to the central axis (MA) in or on the base body (11), - at least two activation elements (14a, 14b), each of which is connected to one of the coupling elements (13a, 13b), wherein the activation elements (14a, 14b) are arranged to be movable independently of each other relative to the base body (11) at least in one direction parallel to the central axis (MA), wherein when an activation element (14a, 14b) moves in the direction of the central axis (MA), the coupling element (13a, 13b) connected to it also moves in the direction of the central axis (MA), and the interaction of the two transmission elements (131) of the coupling element (13a, 13b) with each a coupling surface (121) of a clamping element (12) translates the movement of the coupling element (13a, 13b) into a movement of two clamping elements (12) opposite each other radially to the central axis (MA) in the direction radially to the central axis.

Description

[0001] The invention relates to a clamping device for clamping or gripping an object, comprising a base body which has an interface for connection with a working or testing device, wherein the base body extends along a central axis and has at least four pairs of opposite guides which extend radially to the central axis and at least four clamping elements, one of which is at least partially inserted into a guide, wherein the guide holds and guides the clamping element radially to the central axis with one linear degree of freedom and the clamping element has at least one coupling surface which is inclined to the central axis.The clamping device further comprises at least two coupling elements, each of which is kinematically coupled to two clamping elements radially opposite each other about the central axis, and at least two activation elements, each of which is connected to one of the coupling elements, wherein the activation elements are arranged to be movable independently of one another relative to the base body at least in one direction parallel to the central axis. The invention further relates to a test device with a clamping device and a method for measuring an object with a test device.

[0002] In various applications, an object is clamped in a clamping device such that its central axis is coaxial with the clamping device's axis of rotation. On lathes, a workpiece is clamped in a clamping device so that its central axis is coaxial with the lathe's axis of rotation. Furthermore, there are optical inspection or measuring devices where an object is first clamped in a fixture and then rotated along with the fixture. During this rotation, a camera captures multiple images of the object. These images are then computationally superimposed to create a three-dimensional model of the object.For these and other applications, it is crucial that the object's central axis and the axis of rotation of a clamping device are aligned coaxially with minimal deviation to achieve high-quality results. High-precision coaxial clamping is readily achievable with known methods for objects with a regular, symmetrical shape around their central axis. For example, chucks with three or four jaws exist that are well-suited for the precise clamping of cylindrical or square objects. However, these known chucks are only of limited use for precisely aligning and clamping irregularly shaped objects with their axis of rotation.

[0003] For the coaxial clamping of objects in a clamping device, a centering device can be integrated into the clamping device. This centering device first centers the object relative to the axis of rotation of the clamping device. Clamping jaws are then applied to the already centered object and tightened. Such a solution is described, for example, in DE 10 2006 027 988 B4. A disadvantage of this solution is that a clamping device with an additional centering device has a complex design and requires a large number of components.

[0004] For clamping objects with a rectangular cross-section, clamping devices exist in which four clamping jaws are kinematically coupled to one another in such a way that the central axis of an object is centered on the axis of rotation of the clamping device. Such a compensating clamping device is described, for example, in DE 10 2019 100 089 B3. This clamping device incorporates a compensating mechanism comprising several components that rotate around an axis parallel to the axis of rotation of the clamping device during clamping. The described clamping device comprises a large number of components and therefore requires a relatively large installation space.

[0005] German patent application DE 200 07 116 U1 describes a clamping device for workpieces. This clamping device is designed for clamping complexly shaped workpieces. The clamping device comprises two opposing clamping jaws and a reinforcing mechanism that increases the clamping force of the jaws on a clamped workpiece via a wedge effect. The clamping jaws are designed to bear against a regularly shaped section of the workpiece. A complexly shaped section of the workpiece is positioned in a receiving chamber below the clamping jaws and is not held directly by the clamping jaws.

[0006] The object of the invention is to propose solutions with which objects of irregular shape can be positioned and fixed in a simplified manner with their central axis coaxial to the axis of rotation of a device.

[0007] This problem of the invention is solved by a clamping device for clamping or gripping an object, comprising - a base body which has an interface for connection with a working or testing machine, wherein the base body extends along a central axis and has at least four pairs of opposing guides which extend radially to the central axis, - at least four clamping elements, one of which is at least partially inserted into a guide, the guide holding and guiding the clamping element radially to the central axis with one linear degree of freedom, and the clamping element having at least one coupling surface which is oriented inclined to the central axis, - at least two coupling elements, each of which is kinematically coupled to two clamping elements radially opposite each other to the central axis, wherein the coupling element has two transmission elements spaced apart from each other radially to the central axis, which extend at least partially tangentially to the circumferential direction around the central axis, wherein each transmission element is or can be brought into contact with a coupling surface of a clamping element, and wherein the two coupling elements are independently movable in a direction parallel to the central axis in or on the base body, - at least two activation elements, each of which is connected to one of the coupling elements, wherein the activation elements are arranged to be movable independently of each other relative to the base body at least in one direction parallel to the central axis, wherein, when an activation element moves in the direction of the central axis, the coupling element connected to it also moves in the direction of the central axis, and the interaction of the two transmission elements of the coupling element with each coupling surface of a clamping element translates the movement of the coupling element into a movement of two clamping elements radially opposite each other in the direction radial to the central axis.

[0008] The clamping device according to the invention serves to clamp or grip an object, wherein a central axis of the object is aligned essentially coaxially with the axis of rotation or central axis of the clamping device. The object can, for example, be a component that is to be machined or transferred to a subsequent machining step in a process. Alternatively, the object can also be a component that is to be inspected or measured. The object can have several sub-areas, at least the sub-area that is inserted into the clamping device having an irregular cross-section. An irregular cross-section is understood to be a cross-section that is not rotationally symmetrical about a central axis. For example, the irregular cross-section of a sub-area inserted into the clamping device can have a rectangular cross-section.Some objects manufactured by stamping, for example, have such a rectangular cross-section. The object's central axis is understood to be an axis along which the object extends. The object may be rotationally symmetrical about its central axis, at least in some areas. It is also possible that the object is not rotationally symmetrical about its central axis, at least in some areas.

[0009] The clamping device according to the invention comprises a base body which supports and accommodates the other components of the clamping device. A portion of this base body is formed by an interface designed for connection to a work or testing device. The base body extends along a central axis, which simultaneously forms the axis around which the clamping device rotates when connected to a work or testing device. The central axis can therefore also be referred to as the axis of rotation of the clamping device. The base body comprises four guides, two of which are arranged opposite each other in a radial direction to the central axis. The guides extend radially to the central axis. Furthermore, at least four clamping elements are provided, one of which is inserted into each of the guides in the base body.The guides and clamping elements interact in such a way that each clamping element has one linear degree of freedom for movement towards or away from the central axis. Each clamping element includes at least one coupling surface, which is designed for kinematic coupling with one of the coupling elements. The coupling surface is inclined to the central axis and oriented towards the linear degree of freedom of the guides. Furthermore, the clamping device includes at least two coupling elements. Each of these coupling elements is kinematically coupled via the coupling surface to two opposing clamping elements. This means that the movement of one coupling element is translated into the movement of two opposing clamping elements.Each coupling element has two transmission elements arranged radially to each other along the central axis, which can be brought into contact with a coupling surface of a clamping element. When an object is clamped in the clamping device, the transmission elements are each in contact with a coupling surface. When no object is clamped, a small gap may temporarily exist between a transmission element and a coupling surface. The two coupling elements are mounted in or on the base element, allowing independent linear movement in a direction parallel to the central axis. The clamping device further comprises at least two activation elements, each of which is connected to a coupling element. This connection can be rigid or movable. The two activation elements are also independently movable relative to the base body.Optionally, each activation element can be movably mounted parallel to the central axis in or on the base body. According to the invention, the activation elements are designed to initiate movement, which can be achieved, for example, by an actuator connected to an activation element. When movement is initiated in this way, an activation element is moved in the direction of the central axis. Through its connection with the coupling element, the coupling element is also moved in the direction of the central axis. The movement of the coupling element, in turn, is translated into a radial movement of these two opposing clamping elements via the interaction of the transmission elements, each with a coupling surface of two clamping elements arranged radially opposite each other in the direction of the central axis.The two coupling elements can be moved independently of each other, which, through the transmission mechanism, results in the independent movement of two opposing pairs of clamping elements. Because the two opposing pairs of clamping elements can be moved independently in a radial direction towards or away from the central axis, the clamping device according to the invention enables the clamping of objects with irregular cross-sections. It is possible for one pair of clamping elements to have a greater distance from each other in the radial direction to the central axis than the other pair when clamped. This makes it possible, in particular, to clamp an object with a rectangular cross-section. Furthermore, other cross-sectional shapes of an object can also be clamped centrally using the four clamping elements.For the synchronized movement of opposing clamping elements, a coupling element is provided for each. The two coupling elements are independently movable, as are the activation elements connected to the coupling elements. The activation elements can be moved independently by an operator, for example, manually and / or using an actuator. Alternatively, it is possible to move the activation elements together with the interposition of a compensating mechanism, whereby the clamping device can be operated for clamping by a single actuator, and the movement of all four clamping elements is kinematically coupled to each other. The various possibilities for moving the activation elements are described later for different embodiments.

[0010] The clamping device according to the invention has a simple and robust design and comprises fewer components compared to the prior art. The coupling elements are mounted in a simple manner so that they can move linearly along the central axis and are kinematically connected to two clamping elements each. Such a linear mounting of the coupling elements is easy to manufacture and results in the clamping device according to the invention having a low weight. Due to its simple design, the clamping device according to the invention can be manufactured in very small dimensions and is therefore particularly suitable for holding small, delicate objects. Because of its small footprint and low weight, the clamping device is particularly suitable for use in testing fixtures for the precise inspection of small objects.The ability to move the opposing pairs of clamping elements separately yet synchronously enables repeatable release of an object within the clamping device. Naturally, the clamping device according to the invention can also be dimensioned larger and used, for example, as a clamping device for a machine tool. Even in larger dimensions, the simple design with only a few components ensures easy and cost-effective manufacturing of the clamping device.

[0011] In one embodiment, the interface is designed as a cylindrical pin or cone extending along the central axis and is located on the side of the base body opposite the guides in the direction of the central axis. The interface is shaped such that it can be positively and / or force-fit connected to a corresponding mating interface on a testing machine, machine tool, or testing device.

[0012] Furthermore, the four guides are spaced 90° apart around the central axis in the circumferential direction. In this regular arrangement, each pair of clamping elements is positioned opposite the other at a 180° angle to the central axis. This arrangement is particularly advantageous for clamping objects with a rectangular cross-section.

[0013] In a further embodiment, the guide is formed, at least in part, by a groove in the base body, which transitions into a receiving space on its side facing radially towards the central axis. This receiving space is formed by a cavity that extends, at least in part, along the central axis inside the base body and is designed to receive an object placed between the clamping elements. Grooves can be easily machined into the base body, for example, by milling. A receiving space is preferably provided inside the base body, thus ensuring good force transmission from the clamping elements mounted in the grooves to the clamped object located in the receiving space.

[0014] In an advantageous embodiment, the receiving space has a round or rectangular cross-section. Preferably, the receiving space is regularly shaped circumferentially around the central axis to allow objects of varying orientations to be inserted between the four clamping elements. However, the receiving space can also be irregularly shaped and, for example, have the negative form of an object to be clamped.

[0015] In one embodiment, the guide has a cavity for receiving a clamping element, with at least one insertion element provided which engages in the cavity and is designed to engage the clamping element in order to fix the clamping element in a direction parallel to the central axis, the clamping element being movable radially to the central axis. In this embodiment, the guide is designed as a cavity or hollow space and can, for example, be formed by a groove. To secure the clamping element inserted into the cavity in the direction of the central axis, at least one insertion element is provided which engages in the cavity. Such an insertion element can, for example, be a cylindrical pin or a rib-like projection on a side wall of the cavity.Naturally, the guiding principle can also be reversed: the guide can be designed as a projection, in which case the clamping element has a cavity that is placed onto the projection-designed guide. In this case, the clamping element can be secured along the central axis by having an undercut in the projection-designed guide into which a portion of the clamping element is inserted.

[0016] Preferably, the guides are arranged on or in an end face of the base body in the direction of the central axis. Preferably, the guides are arranged on the end face of the base body opposite the interface in the direction of the central axis.

[0017] In a further embodiment, the guide has a cavity for receiving a clamping element, wherein the cavity is bounded on opposite sides circumferentially around the central axis by a guide edge that projects in the direction of the central axis beyond adjacent areas of the base body. In this embodiment, each guide is bounded on opposite sides circumferentially by a guide edge. This guide edge projects beyond an adjacent, preferably planar, surface of the base body. The projecting guide edge allows for a simple design of the clamping elements' mounting within the guide. For example, recesses can be provided by the guide edge or by both guide edges of a guide, which in turn serve to receive guide elements, such as insert elements.Furthermore, the provision of protruding guide edges allows easy access to the coupling surfaces of the clamping elements, which can also be made accessible through recesses in the guide edges.

[0018] Cleverly, the guide edge is provided with at least one recess extending tangentially to the circumferential direction of the central axis, into which a insertion element or a transmission element is inserted. Such a recess can be easily created from a direction tangential to the circumferential direction around the central axis, for example by drilling or milling. The recess can serve various purposes and, for example, act as a passage for a transmission element through the guide edge to the coupling surface on the clamping element.

[0019] In an advantageous embodiment, the clamping element is designed, at least in part, as a disc and is inserted into a cavity arranged in the guide in a sliding fit. "Disc-shaped" in this context means that the clamping element has two planar surfaces oriented parallel to each other. The area of ​​these surfaces is significantly larger than the other surfaces of the clamping element. Such a clamping element can be inserted into a guide designed as a groove in a sliding or clearance fit. Such a fit means that the clamping element can slide freely within the guide without any play allowing movement of the clamping element tangentially to the circumferential direction and the central axis.

[0020] Furthermore, the clamping element is designed to include a clamping surface oriented towards the central axis and extending parallel to it. This clamping surface may have different surface properties than the other surfaces of the clamping element. For example, the clamping surface may be ground and hardened to prevent wear and tear during repeated use of the clamping device, thus eliminating inaccuracies in clamping objects.

[0021] In one embodiment, the coupling surface in the clamping element is arranged in a recess that at least partially penetrates the clamping element tangentially to the circumferential direction around the central axis. Arranging the coupling surface in a recess results in a compact design of the clamping element. Alternatively, the coupling surface can also be arranged on an outer surface or a projecting area of ​​the clamping element.

[0022] In an advantageous embodiment, the recess is designed as an elongated hole, with two opposing coupling surfaces that are oriented parallel to each other and are planar, the coupling surfaces defining the longer side of the elongated hole. In this embodiment, the recess containing the coupling surface is designed as an elongated hole. This allows two coupling surfaces to be arranged opposite each other in a simple manner.

[0023] Preferably, the coupling surface is oriented at an acute angle to the central axis. An acute angle is defined as an angle between 1° and 89°. The angle at which the coupling surface is arranged is crucial for translating the movement of the coupling elements along the central axis into a movement of the clamping elements radially to the central axis. The more acute the angle, the greater the clamping force that can be achieved between two opposing clamping elements.

[0024] In one embodiment, the clamping element has at least one guide recess that penetrates the clamping element tangentially to the circumferential direction around the central axis, at least partially. A insertion element engages in the guide recess in a sliding fit. The guide recess serves as a counterpart to an insertion element. Preferably, the guide recess is designed as an elongated hole whose longer side is oriented radially to the central axis. An insertion element, fixedly arranged for guidance, penetrates the guide recess. The clamping element is movably guided by the insertion element inserted into the guide recess. Preferably, at least two guide recesses are provided per clamping element.Here too, the principle of guidance or support can be reversed: The clamping element can have at least one protruding area, for example in the form of a rib, which engages in a recess, for example a groove, in or on the guide. The mechanisms described serve to secure or fix clamping elements relative to the guide in the direction of the central axis.

[0025] In one embodiment, the coupling element is rigidly designed, particularly in that the coupling element comprises a one-piece base body into which the transmission elements are inserted. A one-piece base body has a compact and stable structure. The at least two transmission elements are firmly inserted into the base body. Alternatively, the base body can be constructed in multiple parts, or the transmission elements can be designed as sub-areas of the base body.

[0026] In an advantageous embodiment, the coupling element is designed in a forked shape in certain areas, comprising at least two supports spaced radially apart from each other and extending at least partially parallel to the central axis. A central section is arranged between the supports, connecting them, and each support carries a transmission element. A distance exists between the connection of the central section to the supports and the connection of the transmission elements to the supports. In this embodiment, the coupling element is designed in a forked shape. For this purpose, at least two supports oriented parallel to the central axis are provided, which are connected to each other by a central section. Each support carries a transmission element at its end furthest from the central section.Such a fork-shaped design ensures that each coupling element surrounds the recording space arranged around the central axis, but does not penetrate it, thus preventing any collision of the coupling elements with an object placed in the recording space.

[0027] Furthermore, it is provided that each support has at least one sliding surface oriented parallel to the central axis, and that the sliding surfaces are slidably mounted in a partial area of ​​the base body. In this embodiment, the coupling element is mounted in the base body via a sliding bearing. For this purpose, one or more sliding surfaces, preferably planar, are arranged on each of the supports. These sliding surfaces bear in a sliding fit against mating surfaces arranged in the base body. Due to the orientation of the sliding surfaces parallel to the central axis, they enable linear movement of the coupling element relative to the base body in the direction of the central axis, but prevent movement of the coupling element in a radial direction to the central axis.

[0028] Advantageously, the coupling element comprises four supports arranged in pairs tangentially to the circumferential direction around the central axis, with each pair of supports connected by a transmission element. In this embodiment, each coupling element has four supports, two of which together support a transmission element. By having a transmission element supported by two supports, precise and stable alignment of each transmission element relative to a coupling surface of a clamping element is ensured. Due to the paired arrangement of the supports, the individual supports can be smaller than if only one support were provided per transmission element.

[0029] In a further embodiment, the central section has an internal guide, wherein a guide pin is inserted in a sliding fit through the internal guide of the central sections of the two coupling elements and guides the two coupling elements towards each other in the direction of the central axis. In this embodiment, a guide pin aligns the two coupling elements with each other and guides them towards the central axis. Each of the two central sections of the coupling elements has an internal guide through which the guide pin is inserted. Preferably, each internal guide has an irregular cross-section in a plane perpendicular to the central axis, and the guide pin has a correspondingly negatively shaped irregular cross-section. When the guide pin is inserted through the internal guides, the guide with the guide pin prevents the coupling elements from rotating in an axis of rotation parallel to the central axis.Preferably, the guide pin is shaped like a sword. The guide pin can be rigidly connected to the base body or to a sliding element of a compensating mechanism, as will be described later.

[0030] In an advantageous embodiment, the coupling elements are designed to at least partially interpenetrate or surround each other. In this embodiment, the two coupling elements are arranged partially within one another or nested. This results in a compact design of the clamping device.

[0031] In a further embodiment, the coupling elements are designed to be essentially symmetrical about the central axis. The design of the coupling elements can be symmetrical about a plane that runs parallel to and through the central axis. Furthermore, the design can be completely symmetrical in the radial direction around the central axis. Since each coupling element is kinematically connected to two opposing clamping elements, a symmetrical design results in a uniform force flow to both coupled clamping elements. This uniform force flow, in turn, ensures high reproducibility of the position when clamping an object in the clamping device. Additionally, the entire clamping device can be designed to be space-saving and / or slim.

[0032] In one embodiment, the activation elements are arranged on the side of the coupling elements opposite the transmission elements in the direction of the central axis and extend away from the coupling elements in the direction of the central axis. In this embodiment, the activation elements are arranged or attached to the side of the coupling elements facing away from the transmission elements and thus from the clamping elements. The activation elements can be arranged such that they do not project beyond the coupling elements in a radial direction to the central axis and extend away from the coupling elements in the direction of the central axis. Alternatively, the activation elements can also be arranged at a different location and, for example, project outwards in a radial direction to the central axis beyond the coupling elements.

[0033] In a further embodiment, each activation element is connected to an actuator, and each activation element can be moved independently of the others in the direction of the central axis by an actuator. An actuator is understood to be an assembly that generates or transmits a movement to the activation element. The force or energy required to generate the movement can be applied manually by an operator or provided by a drive, for example, an electric motor. Each activation element is connected to a separate actuator, which allows the position of the two pairs of opposing clamping elements in their guides to be moved, changed, or adjusted independently of each other.In this embodiment, the force with which the opposing pairs of clamping elements clamp an object in the clamping device can be adjusted individually and independently. Alternatively, the clamping device can include a compensation mechanism that automatically distributes the movement generated by a single actuator to all four clamping elements. Such an embodiment with a compensation mechanism is described later.

[0034] In an advantageous embodiment, the actuator comprises a nut with an internal thread extending parallel to the central axis, mounted linearly immovably but rotatably about the central axis within the base body. The activation element has an external thread that engages with the internal thread of the nut. In this embodiment, the nut is rotated by an operator about the central axis to actuate the actuator. This rotational movement of the nut is translated into a linear movement of the activation element in the direction of the central axis via a combination of an internal thread in the nut and an external thread on the activation element. Of course, an actuator can also be constructed differently and, for example, include a hydraulic or pneumatic cylinder which, after actuation of a control element, moves the activation element along the central axis.

[0035] In a further embodiment, a compensating mechanism is provided which is connected to the activation elements. This compensating mechanism is designed to compensate for differences in the position of the coupling elements in the direction of the central axis, and thus for differences in the distance between clamping elements radially opposite each other. In this embodiment, a compensating mechanism is connected to the at least two activation elements. When clamping an object with an irregular cross-section, one pair of opposing clamping elements rests against the object in front of the other pair. After this initial contact, due to the kinematic coupling, one of the coupling elements, and thus at least one of the activation elements, can no longer be moved further in the direction of the central axis.The other pair of clamping elements, and thus the other coupling element with its associated activation element, must be moved further to clamp the object. The compensation mechanism ensures that, after the first pair of clamping elements makes contact, the second pair continues to move until it too makes contact with the object and clamps it. The compensation mechanism accomplishes this by transferring the movement from an actuator to the activation elements, compensating for differing positions of the coupling elements. An advantage of using a compensation mechanism is that the clamping force or pressure of all four clamping elements is essentially the same, which promotes centric clamping. Furthermore, the evenly distributed clamping pressure prevents the object from being deformed unevenly or irregularly during clamping.

[0036] It is cleverly designed that the compensating mechanism is arranged along the central axis on the side of the coupling elements opposite the clamping elements. This position of the compensating mechanism is particularly advantageous when an actuator is also arranged on the side of the coupling elements opposite the clamping elements. Preferably, the elements are arranged along the central axis in the following order: coupling elements, activation elements, compensating mechanism, and actuator.

[0037] Furthermore, the balancing mechanism is connected to an actuator via a sliding element, the sliding element being movable by the actuator in the direction of the central axis. The balancing mechanism comprises a sliding element that can be moved linearly by an actuator in the direction of the central axis.

[0038] Advantageously, the actuator comprises a nut with an internal thread extending parallel to the central axis, mounted linearly immovably but rotatably about the central axis within the base body. The sliding element includes a section with an external thread extending parallel to the central axis, the external thread engaging with the internal thread of the nut. In this embodiment, the actuator comprises a nut rotatably mounted in the base body, which, when a rotary movement is initiated via a thread, generates a linear movement of the sliding element along the central axis. Of course, it is also possible for the actuator to be designed differently and, for example, to incorporate a hydraulic or pneumatic cylinder for moving the sliding element.

[0039] In one embodiment, the sliding element has at least one sliding track formed by a recess in the sliding element, the sliding track extending perpendicular to the central axis. The sliding track in the sliding element serves as a bearing for other, movably arranged components of the compensating mechanism. The sliding track penetrates the sliding element in a first direction perpendicular to the central axis and extends in a second direction perpendicular to the central axis, with the first and second directions oriented perpendicular to each other. The sliding track can, for example, be designed as an elongated slot whose longer side extends along the second direction. Alternatively, the sliding track can also be formed by a projection arranged on an outer surface of the sliding element and extending perpendicular to the central axis.

[0040] Furthermore, the compensating mechanism is designed to have at least two transmission elements, each extending along a link axis. Each transmission element is rotatably connected at its first end to an activation element, and the transmission elements are rotatably connected to each other and linearly displaceable relative to the sliding element at their second ends, which are opposite the first end in the direction of the link axis. The transmission elements serve to movably connect the activation elements to the sliding element. Each transmission element extends along a link axis and has two opposite ends in this direction. Such a transmission element can, for example, be shaped like a chain link. A first end of each transmission element is rotatably connected to an activation element.The transmission element is rotatably connected to the activation element in a plane parallel to the central axis. Each transmission element is rotatably connected at one end to the other end of the other transmission element. This connection is designed such that the two transmission elements are rotatably mounted relative to each other in the same plane as the transmission elements are mounted relative to the activation element. Simultaneously, the two second ends of the transmission elements are linearly movable within the sliding track of the sliding element.

[0041] Advantageously, the link axes of the transmission elements are arranged at an acute angle to each other, allowing rotation about an axis perpendicular to the central axis. Through their connections to the activation element and to each other, the transmission elements are positioned in a plane parallel to the central axis and thus rotatable about at least one axis of rotation or axis perpendicular to the central axis. The link axes of the two transmission elements are arranged at an acute angle to each other. When compensating for different positions of the coupling elements, the two transmission elements therefore move in a common plane oriented parallel to the central axis.

[0042] In one embodiment, the transmission elements are designed as flat disks, each with a bore at its first and second end. The bores at the first end are each connected to an activation element via a bolt, and the bores at the second end are connected to each other via a bolt. The bolt connecting the two second ends engages in a sliding fit within the sliding track. In this embodiment, the rotatable bearing between the transmission elements and the activation elements is achieved through a combination of bores and bolts inserted therein. Preferably, bores are also provided in the activation elements, allowing bolts to pass through the bores in both the activation elements and the transmission elements. A sliding fit exists at least between the activation element and the transmission elements.The same applies to the connection of the two transmission elements via the bores at their distal ends; here, too, at least one connection between the bolt and bore is designed as a sliding fit. Alternatively, all connections can be designed as sliding fits, and the bolts can be secured against falling out by additional elements, for example, by one or more collars that project radially beyond the bolts. The bolt connecting the two distal ends of the transmission elements also engages in the sliding track of the sliding element, so that the two transmission elements are guided and supported relative to the sliding element.

[0043] In an advantageous embodiment, the balancing mechanism comprises four transmission elements, two of which are rotatably connected to each other. Two interconnected transmission elements are arranged on sides of the sliding element radially opposite each other to the central axis and are connected to activation elements. A total of at least four activation elements are provided, two of which are connected to a coupling element. In this embodiment, the balancing mechanism has two pairs of transmission elements, each pair connecting two activation elements to the sliding element. These pairs of transmission elements are preferably arranged symmetrically to the central plane of the sliding element. To ensure stable operation of the balancing mechanism, one pair of transmission elements is sufficient.Providing multiple pairs of transfer elements distributes forces and loads across several components, making the balancing mechanism more stable and less susceptible to damage. It is also possible to provide more than two pairs of transfer elements, each connected to two activation elements and the sliding element. Preferably, multiple pairs of transfer elements are arranged regularly in the circumferential direction around the central axis.

[0044] In a further embodiment, the sliding track is provided that it at least partially penetrates the sliding element radially to the central axis, and that two adjacent second ends of the transmission elements are connected to each other by a bolt. These two bolts project into the sliding track from sides radially opposite each other to the central axis and are mounted to be independently slidable within the sliding track. In this embodiment, two pairs of transmission elements are provided, each of which is connected via its second ends to a bolt that also projects into the sliding track. The two bolts projecting into the sliding track are guided linearly within it, allowing for independent movement. When the compensating mechanism is activated to compensate for different positions of the coupling elements, the two bolts projecting into the sliding track move along the sliding track in opposite directions.

[0045] Cleverly, the coupling elements, the activation elements and the compensation mechanism are arranged at least partially inside the base body.

[0046] In this way, the base body acts as a protective housing for the other components, protecting these components against contamination and damage.

[0047] In a further embodiment, the central section has an internal guide, wherein a guide pin is inserted in a sliding fit through the internal guide of the central sections of the two coupling elements and guides the two coupling elements towards each other in the direction of the central axis. The guide pin is connected to the sliding element and extends parallel to the central axis. In this embodiment, a guide comprising a guide pin and two internal guides arranged in the coupling elements is provided. The guide pin is rigidly connected to the sliding element and extends from the sliding element parallel to the central axis through both internal guides. Preferably, the guide pin is shaped like a sword. This guide is designed to prevent the two coupling elements from rotating relative to the sliding element.At the same time, however, this guide allows the two coupling elements to move independently of each other relative to the sliding element.

[0048] In one embodiment, the actuator is provided with a force-limiting unit that limits the force exerted by the actuator on the activation element or the compensating mechanism for moving the coupling element parallel to the central axis. Such a force-limiting unit ensures that, when the actuator is actuated, the force it generates, and thus also the clamping force between two opposing clamping elements on the object being clamped, is limited. This prevents damage to the object between the clamping elements and ensures reproducible, repeated clamping of the same object. Due to the force-limiting unit, the object is always clamped with the same clamping force, even with repeated clamping, thereby ensuring highly repeatable positioning of the object in the clamping device.The force limiting unit can, for example, be a slip clutch, which transmits force or torque only up to a certain limit and decouples the actuator from the connected components when the limit is exceeded. Such a slip clutch is known, for example, from torque wrenches or torque-limited drill chucks.

[0049] A testing machine for inspecting objects by recording force-displacement relationships is also disclosed. The testing machine comprises a test slide that is displaceable at least along one spatial axis. A clamping device according to one of the previously described embodiments is attached to the test slide via its interface. The central axis of the clamping device is oriented parallel to a spatial axis along which the test slide is displaceable, and the object to be tested can be clamped by at least two clamping elements of the clamping device. The disclosed testing machine is designed for recording force-displacement relationships when testing the properties of objects. The testing machine includes a driveable test slide and sensors to continuously record the movement and the forces acting on the test steps.The testing machine further comprises a clamping device according to one of the previously described embodiments, in which the object to be tested is clamped or can be clamped. The compact, simple design of the clamping device, as well as the secure, centric positioning of the object within it, ensure that the testing machine is easy to operate and delivers highly reproducible test results. The testing machine can be used, for example, to determine and evaluate the force-displacement relationship when pressing an object into a test standard. Alternatively, the clamping device can also be used in a machine tool, such as a lathe or milling machine. In this case, an object to be machined is clamped in the clamping device and machined by the machine tool while clamped.

[0050] The object of the invention is further solved by a testing device for the optical inspection or measurement of an object, wherein the testing device has at least one object holder rotatable about at least one axis of rotation, wherein the object holder comprises at least one clamping device according to one of the previously described embodiments, wherein the central axis of the clamping device is aligned coaxially to the axis of rotation, wherein a camera unit is provided which has at least one camera which can be aligned to an object clamped in the clamping device, wherein the camera transmits recorded images to a computing unit which is configured to calculate a volume model from several images and to inspect or measure the volume model according to at least one test procedure.

[0051] The testing device according to the invention is used to inspect or measure objects. This can be done, for example, in manufacturing, where a manufactured object is tested with the device for conformity with a test specification. The inspection is carried out optically and without contact, which has the advantage that the object is not touched and potentially unintentionally deformed or damaged. Therefore, the testing device according to the invention is particularly suitable for testing delicate, sensitive objects. The testing device comprises an object holder, which is provided for holding an object to be tested. This object holder is rotatable about a pivot axis and preferably movable automatically, for example by an electric motor. The object holder includes a clamping device according to the invention in one of the embodiments described above.The clamping device is connected via its interface to a complementary interface on or within the object holder. The central axis of the clamping device is aligned coaxially with the axis of rotation of the object holder. When the object holder rotates, the clamping device rotates around its central axis. The test device further comprises at least one camera unit, which is designed for the optical detection of an object clamped in the clamping device. The camera unit, in turn, comprises at least one camera that can be aligned with an object clamped in the clamping device. It is also possible to provide multiple cameras or a camera with different, interchangeable lenses. During operation of the test device, the camera captures several images of the object and transmits them to a processing unit.The processing unit calculates a volume model of the object from the images and data on the rotation of the object between the acquisition of the individual images. This volume model represents a virtual model of the object and can subsequently be inspected or measured in place of the real object. This inspection or measurement is carried out according to at least one test procedure. A test procedure can, for example, be a data set in which the target dimensions of the object to be measured are stored. The testing device measures the calculated volume model and checks the conformity of the actual dimensions with the stored target dimensions. An advantage of the testing device according to the invention is that objects with irregular cross-sections can be clamped in the clamping device in the object holder in a simple and highly reproducible manner.In this way, the testing device is easy to operate and delivers highly repeatable test or measurement results. The clamping device of the object holder ensures that the object is fixed coaxially to the axis of rotation of the object holder. Furthermore, the clamping force of the object in the clamping device can be easily adjusted, thus preventing damage or deformation of the object during clamping.

[0052] In one embodiment of the test device, the device rotates the object holder, along with the clamping device and the object clamped therein, around the axis of rotation. The camera captures multiple images of the object in different rotational positions around the axis and transmits them to the processing unit. During the test, the device rotates the object under test together with the object holder and the clamping device. The camera captures multiple images of the object in different rotational positions. A rotation angle sensor is provided in or on the object holder to determine the rotational positions and transmit them to the processing unit. The processing unit calculates a volume model based on multiple images, each linked to the corresponding rotational position at which the image was captured.The calculated volume model can then be displayed on a screen and measured.

[0053] The object of the invention is ultimately achieved by a method for measuring an object using a testing device according to one of the previously described embodiments, comprising the method steps A) Clamping an object to be measured between the clamping elements of the clamping device, B) Rotating the object around the axis of rotation, whereby the camera takes several pictures of the object held in the clamping device during the rotation, C) Transmission of images from the camera to the processing unit, D) Calculation of a volume model of the object based on the images by the computing unit, E) Measurement of the volume model, wherein the measurement is based on at least one test specification already stored or entered by an operator.

[0054] The method according to the invention serves to measure or test an object. A testing device according to one of the previously described embodiments is used to carry out the method. The use of a clamping device in a testing device and the use of the testing device to carry out the method are thus also disclosed.

[0055] In a first process step A), an object to be measured is clamped between the clamping elements in the clamping device. For this purpose, at least one actuator of the clamping device is actuated.

[0056] In a second process step B), the object is rotated around its axis of rotation by the testing device, whereby the camera takes several pictures of the clamped object in different rotational positions.

[0057] Subsequently, in a third process step C), the images captured in process step B) are transmitted to a processing unit. It is also possible to perform process steps B) and C) simultaneously or in parallel.

[0058] In a fourth process step D), a volume model of the object is calculated from the images and the associated rotational positions of the object recording.

[0059] In a fifth process step (E), the volume model is measured. This is based on at least one test procedure. The test procedure can consist of an operator entering corresponding commands for measuring the volume model at the test device. Alternatively, the test procedure can consist of a test plan already stored in the test device, which is executed automatically by the device without any further direct input from the operator. Testing according to a stored test plan is preferably used to test several objects of the same design in order to obtain reproducible measurement results.

[0060] The method according to the invention is easy to perform and, due to the use of the clamping device according to the invention, leads to repeatable and very accurate measurement results. In particular, the clamping device according to the invention facilitates process step A) of clamping the object in the test fixture.

[0061] Features, effects, and advantages disclosed in connection with the clamping device and the testing device are also deemed disclosed in connection with the method. Conversely, features, effects, and advantages disclosed in connection with the method are also deemed disclosed in connection with the clamping device and the testing device.

[0062] The figures schematically illustrate embodiments of the invention. Fig. 1 in a perspective view a first embodiment of a clamping device according to the invention, Fig. 2 in a perspective view the components of the first embodiment arranged within the base body Fig. 1, Fig. 3 in a perspective view the first embodiment Fig. 1 with partially hidden components, Fig. 4 in a perspective view a second embodiment of a clamping device according to the invention, Fig. 5 in a perspective view the components of the second embodiment arranged within the base body Fig. 4, Fig. 6 in a perspective view a partial area of ​​the components of the second embodiment arranged within the base body Fig. 4, Fig. 7 in a perspective view that is in Fig. 4, Fig. 5 and Fig. 6 second embodiment shown with a guide mandrel.

[0063] In the figures, identical elements are labelled with the same reference symbols. Generally, the described properties of an element in one figure also apply to the other figures. Directional terms such as "up" or "down" refer to the described figure and should be applied analogously to other figures.

[0064] Fig. Figure 1 shows a perspective view of a first embodiment of a clamping device 1 according to the invention. In the illustrated first embodiment, the two opposing pairs of clamping elements 12 are each movable in a radial direction to the central axis MA by a separate actuator A. The clamping device 1 is short in the direction of the central axis MA and, due to the small number of components, has a simple design and is therefore lightweight. The base body 11 extends along the central axis MA and supports or incorporates the other components. At the downward-facing end, an interface 111, designed as a cylindrical pin, is arranged for connection to a device, for example, a testing device. Four guides 112 are arranged on the upward-facing end face of the base body 11, extending radially to the central axis MA.Two of these guides 112 are arranged opposite each other with respect to the central axis MA. The guides 112 are offset from each other circumferentially by 90° around the central axis. A disc-shaped clamping element 12 is incorporated into each of the guides 112. The guides 112 are designed as grooves in the base body 11, which transition into the receiving space 113 in the center. The receiving space 113 is designed as a cavity intended to accommodate a portion of an object to be clamped. The receiving space 113 has a square cross-section in a top view from the direction of the central axis MA. The clamping elements 12 are mounted linearly movable radially to the central axis MA in the respective guides 112. This mounting is formed by the grooves, which represent cavities in the base body 11. Details of the clamping elements 12 and the guides 112 are given in [reference missing]. Fig. Figure 2 shows the clamping device 1 comprising two coupling elements 13a and 13b, each of which is kinematically coupled to two opposing clamping elements 12. This kinematic coupling is effected via two transmission elements 131 belonging to each coupling element 13a, 13b, which are operatively connected to a coupling surface 121 of a clamping element 12. Details of this operative connection are shown in Figure 2. Fig. 2 shown. The in Fig. The upper ends of the coupling elements 13a and 13b, as shown in Figure 1, are each arranged adjacent to a guide edge of a guide 112. The guide edge defines the cavity of the guide in which the clamping element 12 is movably inserted. The guide edge projects beyond adjacent areas of the base body 11, which are oriented perpendicular to the central axis MA. The projecting guide edge allows for the simple arrangement of recesses that extend tangentially to the circumferential direction around the central axis MA. These recesses can be used to guide a insertion element 1121 or a transmission element 131. In the illustrated embodiment, the guide edge of each guide 112 has recesses spaced apart from one another in the radial direction around the central axis for inserting and securing an insertion element 1121. The insertion elements 1121 are pressed into these recesses.The insertion elements 1121 and their connection with the clamping elements 12 are in . Fig. 2. Furthermore, the guide edge of each guide 112 has a recess for the passage of a transmission element 131 to the clamping element 12. This recess is formed by an elongated hole that penetrates both guide edges belonging to a guide 112 tangentially to the circumferential direction of the central axis, with the longer side of this elongated hole being oriented parallel to the central axis MA. In this way, this elongated hole guides the transmission element 131, which is connected to a coupling element 13a, 13b, in the direction of the central axis MA. In the illustrated embodiment, the disc-shaped clamping elements 12 are inserted into a guide 112 in a sliding fit. In the illustrated first embodiment, the clamping device comprises two actuators A, which are arranged partially inside the base body 11. These actuators A are operatively connected to the activation elements 14a, 14b arranged inside, which are in Fig. Figure 2 shows that each actuator A comprises a nut with an internal thread, rotatably mounted about the central axis MA. This nut has knurled edges on its outer circumference, allowing it to be easily rotated relative to the central axis MA using the fingers. The nut is linearly fixed in the base body 11 in the direction of the central axis MA. Rotation of the nut, through the interaction of its internal thread with an external thread on the activation element 14a, 14b, sets the activation element 14a, 14b, and thus the coupling element 13a, 13b, into a linear movement parallel to the central axis MA.In the illustrated embodiment, the two coupling elements 13a, 13b can each be moved independently of one another by a separate actuator A, thereby indirectly allowing the two opposing pairs of clamping elements 12 to be moved radially towards or away from the central axis by actuating the two actuators A.

[0065] Fig. Figure 2 shows in a perspective view the components of the first embodiment arranged within the base body 11. Fig. 1. In the representation in Fig. 2 are the base body 11 and the two actuators A, which are in Fig. The components shown in Figure 1 are not depicted. This makes the components inside the base body 11 easier to see. The four clamping elements 12 are arranged in pairs opposite each other. Each of these clamping elements 12 has three through-holes that completely penetrate the clamping element 12 tangentially to the circumferential direction around the central axis MA. The middle hole is designed as an elongated slot, the longer side of which is inclined, in particular at an acute angle, to the central axis MA. The inner surfaces of the elongated slot on the longer sides each form a coupling surface 121. Thus, in this embodiment, each clamping element comprises two parallel, opposing coupling surfaces 121. Two further recesses in each clamping element 12 each form a guide recess 122.These guide recesses 122 are each formed by elongated holes, the longer side of which is oriented radially and thus perpendicular to the central axis MA. The guide recesses 122 serve to guide the clamping element 12 radially to the central axis MA, but to fix it parallel to the central axis MA in the respective guide 112. For this purpose, two insertion elements 1121 are provided by each of the two guide edges opposite each other with respect to a clamping element 12, each of which also penetrates a guide recess 122. The insertion elements 1121 are designed as cylindrical pins and are fixed in each guide edge in a cylindrical bore by an interference fit. Each insertion element 1121 engages in a sliding fit in one of the guide recesses 122.This combination of insertion elements 1121 and guide recesses 122 allows the clamping elements 12 to move linearly in the longitudinal direction of the elongated guide recesses 122, and thus radially to the central axis MA, relative to the insertion elements 1121. However, this combination prevents movements in other directions or rotations of the clamping elements 12 relative to the base body 11. It is also possible to achieve radially movable mounting of the clamping elements 12 relative to the base body 11 in another way. The interaction between the recesses with the coupling surfaces 121 and the transmission elements 131 functions similarly: a transmission element 131, designed as a cylindrical pin, is fixedly inserted between each pair of opposing supports 132 of a coupling element 13a, 13b.Between the supports 132, the transmission element 131 is guided in a sliding fit into the central recess in the clamping element 12, which has the coupling surfaces 121. Thus, the transmission element 131 is displaceable within the central recess, parallel to the coupling surfaces 121. If a transmission element 131, guided by a coupling element 13a, 13b and / or a recess in the guide edges, is moved parallel to the central axis MA, the clamping element 12 slides along the transmission element 131 parallel to the coupling surfaces 121. In this way, the inclined coupling surfaces 121 translate the movement of the transmission element 131, oriented parallel to the central axis MA, into a movement of the clamping element 12 oriented radially to the central axis MA.In the illustrated embodiment, the coupling elements 13a and 13b are each rigidly designed and comprise a one-piece base body into which the transmission elements 131, designed as cylindrical pins, are press-fitted. In the illustrated embodiment, the two coupling elements 13a and 13b are essentially symmetrical about the central axis MA, but differ in their shape. The coupling elements 13a and 13b partially interpenetrate or surround each other and are therefore at least partially slidable into one another in the direction of the central axis MA. This allows the coupling elements 13a and 13b to move independently of each other in the direction of the central axis MA without collision occurring.The coupling elements 13a, 13b are fork-shaped in their upward-facing portion and, in the illustrated embodiment, each comprise four supports 132 extending in the direction of the central axis MA. These supports 132 are spaced apart from each other radially to the central axis MA and tangentially to the circumferential direction around the central axis MA. Each pair of supports 132, which are spaced apart tangentially to the circumferential direction around the central axis MA, carries a transmission element 131. On the side of the supports 132 opposite the transmission elements 131, they are connected by a central section 133, which is oriented perpendicular to the central axis MA. Several sliding surfaces 1321 are arranged on each of the supports 132, located on the outer circumference of each support 132.These sliding surfaces 1321 bear against partial areas of the base body 11 and, together with these, form a sliding bearing for the coupling elements 13a, 13b in the direction of the central axis in the base body 11. Such a sliding bearing is easy to implement and facilitates a compact design requiring little installation space. The distance between the supports 132 opposite each other in the direction radially to the central axis is the same for both coupling elements 13a, 13b. In the illustrated first embodiment, the two activation elements 14a, 14b are each formed by partial areas of the coupling elements 13a, 13b. Each activation element 14a, 14b is formed by a partial area of ​​a coupling element 13a, 13b projecting in a direction radial to the central axis MA, on which an external thread is arranged that extends along the central axis MA.In the assembled state of the clamping device 1, this external thread engages with an internal thread located in the nut of an actuator A. Rotating the nut moves the activation element 14a, 14b in a direction parallel to the central axis MA, and this movement is directly transmitted to the coupling element 13a, 13b. The activation elements 14a, 14b are connected to the transmission elements 131 in the direction of the central axis MA. Alternatively, the coupling elements 13a, 13b can also be composed of several individual parts. For a compact design with small dimensions, particularly for a clamping device 1 for small, delicate parts, the illustrated one-piece design is advantageous. If the clamping device 1 is to be dimensioned larger, a multi-part design of the coupling elements 13a, 13b is recommended.

[0066] Fig. Figure 3 shows the first embodiment in a perspective view. Fig. 1 with partially hidden components. Fig. Figure 3 serves to illustrate the functionality of actuators A. Fig. 3 is the first embodiment of a clamping device 1 made of Fig. 1 shown. However, the representation in Fig. Figure 3 shows the lower actuator A, as well as a coupling element 13a and an activation element 14a, hidden from view. This allows the remaining coupling element 13b and the remaining activation element 14b to be seen in their installed position inside the base body 11. Inside the base body 11 is a cavity in which the coupling elements 13a, 13b and the activation elements 14a, 14b have sufficient clearance to move in the direction of the central axis MA. The external thread of the activation element 14b projects radially outwards beyond the coupling element 13b in a direction relative to the central axis MA. During the assembly of the clamping device 1, an identical nut is installed below the knurled nut of the first actuator A, which engages with the external thread on the activation element 14b.The nuts of both actuators A are mounted immovably in the base body 11 in the direction of the central axis MA, but rotatably about the central axis MA. When the nut of an actuator A is rotated, it remains in its position in the base body 11, and the interaction of the threads generates a linear movement of the corresponding coupling element 13a, 13b in the direction of the central axis MA. In the illustrated embodiment, the actuators A are thus arranged radially outside, but parallel to the coupling elements 13a, 13b in the direction of the central axis MA. This results in a compact length of the clamping device 1 in the direction of the central axis MA, which is advantageous for good concentricity of the clamping device 1 and thus of an object clamped in the clamping device 1. For in connection with . Fig. The 3 undescribed components should be referred to the description. Fig. 1 and Fig. 2 referred.

[0067] Fig. Figure 4 shows a perspective view of a second embodiment of a clamping device 1 according to the invention. The illustrated second embodiment comprises a Fig. 4. A non-visible compensating mechanism 15, which couples the movements of opposing clamping elements 12 in a compensating manner. The second embodiment comprises only an actuator A, which serves to actuate the clamping device 1 when clamping or unclamping an object. The base body 11 of the second embodiment is identical in the area of ​​the guides 112 on the upward-facing end face and with regard to the shape and position of the interface 111 to that in Fig. The first embodiment shown in 1 is constructed as follows. Therefore, for these sub-areas of the base body 11, reference should be made to the description in [reference to relevant section]. Fig. Reference is made to Figure 1. The central part of the base body 11 comprises two openings which allow access to the actuator A inside the base body 11. In this embodiment as well, the actuator A comprises a nut with a knurled outer surface which has an internal thread that is in operative connection with a partial area of ​​the compensating mechanism 15.

[0068] Fig. Figure 5 shows in a perspective view the components of the second embodiment arranged within the base body 11. Fig. 4. In Fig. 5 is the one in Fig. The base body 11 shown in Figure 4 is not shown. The components arranged at least partially inside the base body 11 are partially identical to those in the first embodiment. The four clamping elements 12 with their recesses and bearings are identical to those in the first embodiment. Furthermore, the upper sections of the coupling elements 13a and 13b with the supports 132 and the transmission elements 131 are identical to those in the first embodiment.

[0069] For details as well as the function and storage of these components in the base body 11, please refer to the description of the first embodiment in Fig. 1 and Fig. Reference is made to Figure 2. In the second embodiment, the coupling element 13a is longer in the direction of the central axis MA than in the first embodiment. In the second embodiment, the two coupling elements 13a and 13b have essentially identical lengths in the direction of the central axis. This is necessary for the connection with the compensating mechanism 15 located below it. In the second embodiment, the two activation elements 14a and 14b are designed differently from the first embodiment and are located in a different position relative to the coupling elements 13a and 13b. In the second embodiment, the activation elements 14a and 14b are designed as sub-sections of the coupling elements 13a and 13b.The activation elements 14a, 14b are located on the side of the coupling elements 13a, 13b opposite the transmission elements 131, in the direction of the central axis MA, and extend away from the coupling elements 13a, 13b in the direction of the central axis MA. Each activation element 14a, 14b has two parallel, spaced-apart sub-areas. A transmission element 152 can be inserted into the space between these sub-areas. The shape of the activation elements 14a, 14b is shown in . Fig. 6 is more easily recognizable. The clamping device 1 according to the second embodiment comprises a compensating mechanism 15, which is connected on one side to the activation elements 14a, 14b and on the other side to an actuator A. The compensating mechanism 15 is designed to compensate for a difference in the position of the coupling elements 13a, 13b in the direction of the central axis MA. Such a difference in the position of the coupling elements 13a, 13b arises when the clamping elements 12 kinematically coupled to them bear against an object to be clamped with an irregular cross-section. For example, if an object with a rectangular cross-section is placed in the receiving space 113, then, when the clamping elements 12 move radially inwards towards the central axis MA, a pair of opposing clamping elements 12 bears against the object before the other pair of clamping elements 12 bears against the object.In this case, the pair of clamping elements 12 that is not yet in contact with the object can continue to move towards it until it too comes into contact with the clamping elements 12. During the period in which the first pair of clamping elements 12 is already in contact, but the second pair can still move inwards, the coupling element 13a, 13b, which is coupled to the still-moving clamping elements 12, continues to move along the central axis MA. Until the second pair of clamping elements 12 comes into contact with the object, the position of one coupling element 13a, 13b changes relative to the position of the other coupling element 13a, 13b. The compensating mechanism 15 is provided to allow the second pair of clamping elements 12 to continue moving towards the object after the first pair has come into contact with it.The compensating mechanism 15 enables the automatic, centered clamping of an object with an irregular cross-section between the four clamping elements 12 when a single actuator A is actuated. Particularly in the second embodiment with the compensating mechanism 15, the operation of the clamping device 1 is very simple and, due to the automatic centering, leads to reproducible results even when clamping the same object multiple times in the clamping device 1. The compensating mechanism is arranged in the direction of the central axis MA on the side of the coupling elements 13a, 13b opposite the clamping elements 12. The compensating mechanism 15 comprises a sliding element 151, which is connected to the actuator A below it. A portion of the sliding element 151 is designed as a threaded bolt with an external thread, extending along the central axis MA away from the coupling elements 13a, 13b.Actuator A comprises a nut with knurled outer circumference and an internal thread. The external thread of the threaded bolt engages with the internal thread of the nut. When the nut rotates about its central axis MA, this rotation is translated into movement of the sliding element 151 along the central axis MA by the interaction of the threads. For this purpose, the nut is rotatably mounted in the base body 11, but linearly immobile in the direction of the central axis MA. A sliding track 1511 is incorporated into the sliding element 151. This track is formed by a recess that penetrates the sliding element 151 in a direction perpendicular to the central axis MA. The sliding track 1511 is designed as an elongated slot, the longer side of which is oriented perpendicular to the central axis MA. In the illustrated embodiment, the sliding track 1511 completely penetrates the sliding element 151 and is thus accessible from two opposite sides.Alternatively, the sliding track 1511 may only partially penetrate the sliding element 151. The compensating mechanism 15 further comprises at least two transmission links 152, which movably connect the activation elements 14a, 14b to the sliding element 151. In the illustrated embodiment, the compensating mechanism 15 comprises a total of four transmission links 152, of which, however, only two are shown. In the illustrated embodiment, the transmission links 152 are designed as planar disks and shaped similarly to chain links. Each transmission link 152 extends longitudinally along a link axis. Each transmission link 152 has a bore at a first end and also a bore at a second end opposite the first end in the direction of the link axis. Each transmission link 152 is rotatably connected at its first end to an activation element 14a, 14b.This connection is made via a bolt 1521, which passes through the bore at the first end of each transmission element 152 and through corresponding bores in an activation element 14a, 14b. For example, the bolt 1521 can be interference-fitted with the bores in the activation element 14a, 14b and sliding-fitted with the bore at the first end of the transmission element 152. In this way, the transmission elements 152 are rotatably mounted in a plane parallel to the central axis MA relative to the activation element 14a, 14b and the coupling element 13a, 13b. The second ends of the transmission elements 152 are rotatably connected to each other via the bores located there by a bolt 1522. The bolt 1522 passes through the two bores in the second ends of the transmission elements 152 and also engages in the sliding track 1511 in the sliding element 151.A sliding fit exists between at least one bore in the second end of a transmission element 152 and the bolt 1522, allowing relative rotation of the components. Simultaneously, a sliding fit also exists between the outer circumference of the bolt 1522 and the inwardly facing surfaces of the sliding track 1511, enabling the bolt 1522 to be displaced along the sliding track 1511 in a direction perpendicular to the central axis MA. The link axes of the transmission elements 152 are arranged at an acute angle to each other in a plane parallel to the central axis MA and are rotatable about an axis perpendicular to the central axis MA. The details of the design of the compensating mechanism 15 can also be modified to achieve the same or a comparable effect. The activation elements 14a, 14b are each connected to a transmission element 152 rotatable in a plane parallel to the central axis MA.The ends of the transmission elements 152 opposite this connection are rotatably connected to each other, also in a plane parallel to the central axis MA. Additionally, the second ends of the transmission elements 152 are slidably mounted in a sliding element 151 in a direction perpendicular to the central axis MA. The sliding element 151, in turn, is arranged in the base body 11 so as to be linearly movable in the direction of the central axis MA. The compensation mechanism 15 functions as follows: First, a component with an irregular cross-section is inserted between the four clamping elements 12. Then, the actuator A is actuated, which moves the sliding element 151 away from the clamping elements 12 in the direction of the central axis MA.This linear movement of the sliding element of 151 is transmitted via the transmission elements 152 and the activation elements 14a, 14b to the coupling elements 13a, 13b, which consequently also move away from the clamping elements 12 in the direction of the central axis MA. Due to the climatic coupling of the coupling elements 13a, 13b with the clamping elements 12, the movement of the coupling elements 13a, 13b is translated into a movement of the clamping elements 12 radially towards the central axis MA. Because of the irregular cross-section, one pair of opposing clamping elements 12 rests against the object, while a gap remains between the clamping elements 12 of the other pair and the object. The coupling element 13a, 13b connected to the clamping elements 12 already resting against the object now remains in its position relative to the central axis MA.The other coupling element 13a, 13b is subsequently moved further away from the clamping elements 12 by the action of the compensating mechanism 15 due to the further movement of the sliding element 151, causing the second pair of clamping elements to move further towards the object. From the moment the first coupling element 13a, 13b stops moving further towards the central axis MA, the transmission links 152 rotate about their connection points with the activation elements 14a, 14b and about their connection point with each other. Simultaneously, the bolt 1522, which connects the second ends of the transmission links 152 to each other, moves within the sliding track 1511. As soon as the second pair of clamping elements 12 is also in contact with the object, the rotational movement of the transmission links 152 ends.A further movement of the sliding element 151 in the direction of the central axis MA is then transmitted via the compensation mechanism 15 back to both coupling elements 13a, 13b and thus to all four clamping elements 12. A slight further movement of the sliding element 151 in the direction of the central axis MA finally clamps the object securely through the interaction of the kinematically coupled components. In principle, it is sufficient to provide a total of two activation elements 14a, 14b and a total of two transmission elements 152 to implement a compensation mechanism 15 according to the presented operating principle. However, the illustrated second embodiment comprises a total of four activation elements 14a, 14b and four transmission elements 152. Details can be found in connection with [reference missing]. Fig. 6 described.

[0070] Fig. Figure 6 shows a perspective view of a partial area of ​​the components of the second embodiment arranged within the base body 11. Fig. 4 and Fig. 5. In Fig. 6 is the compensation mechanism 15 in a representation in Fig. 5 slightly altered perspectives are shown. Fig. Figure 6 shows that the coupling element 13a is connected to two activation elements 14a. The activation element 14a shown on the right is connected via two transmission elements 152 to one activation element 14b of the other coupling element 13b. The other coupling element 13b is also connected to two activation elements 14b, the rear one of which is hidden in the illustration. The activation element 14a on the left is likewise connected via two transmission elements 152 to the second activation element 14b of the other coupling element 13b. In the illustrated embodiment, the two coupling elements 13a and 13b are thus connected to each other via a total of four activation elements 14a and 14b and four transmission elements 152. The pairs of activation elements 14a and 14b and transmission elements 152 are arranged on sides of the sliding element 151 that are radially opposite each other to the central axis MA.This results in a symmetrical design of the compensating mechanism 15, which ensures particularly good force transmission. Furthermore, this symmetrical design significantly reduces the risk of jamming of the compensating mechanism 15. It is also possible to provide additional pairs of activation elements 14a, 14b and transmission elements 152, which are preferably arranged regularly in the circumferential direction around the central axis MA. When an object with an irregular cross-section is clamped between the four clamping elements 14, and the compensating mechanism 15 compensates for this irregular shape of the object as described above, the two bolts 1522, which engage in the sliding track 1511, move in opposite directions within the sliding track 1511.To prevent the sliding element of the 151 from rotating relative to the coupling elements 13a, 13b when clamping or unclamping an object in the clamping device 1, a guide mandrel F can be provided, which is shown in the illustrations in . Fig. 5 and Fig. 6 is not shown for the sake of clarity. Such a guide pin F is in Fig. 7 shown.

[0071] Fig. Figure 7 shows a perspective view of the in Fig. 4, Fig. 5 and Fig. The second embodiment shown in 6 with a guide pin F. The Fig. The embodiment shown in section 7 corresponds to the one in connection with Fig. 5 and Fig. The embodiment shown in Figure 6, however, additionally features a guide pin F, which is guided by two internal guides 1331 in the central sections 133 of the coupling elements 13a, 13b. For the aspects related to Fig. The description of the 7 undescribed components of the clamping device 1 refers to... Fig. 5 and Fig. 6 referred to. For the sake of clarity, some parts of the balancing mechanism 15, for example the transmission elements 152, are shown in Fig. 7 not shown. The embodiments in Fig. 7 or Fig. 5 and Fig. 6 can be freely combined with each other. Fig.A guide mandrel F is provided, which is rigidly connected to the sliding element 151 and extends upwards along the central axis MA towards the clamping elements 12. The guide mandrel F has an irregular shape in a cross-sectional plane perpendicular to the central axis MA. The guide mandrel F is shaped like a sword, which has a significantly greater width than thickness. The inner guides 1331 have a shape complementary or negative to the cross-section of the sword. The guide mandrel F extends through both inner guides 1331 and is mounted in them in a sliding fit. In this way, the two coupling elements 13a, 13b can be moved linearly relative to the guide mandrel F in the direction of the central axis MA. With this mounting, the two coupling elements 13a, 13b can be moved independently of each other.The irregular cross-sectional shape of the guide pin F and the internal guides 1331 prevents each coupling element 13a, 13b from rotating around the central axis MA. This ensures that the coupling elements 13a, 13b cannot rotate relative to the sliding element 151 connected to the guide pin F. This guarantees trouble-free operation of the entire compensating mechanism 15. Alternatively, several guide pins F can be provided, which can then have a regular cross-section, such as a circular one. With multiple guide pins F, several internal guides, complementary in shape to the guide pins, are also incorporated into the central sections 133. Reference symbol list: 1 clamping device 11 Basic bodies 111 Interface 113 Recording Room 112 Guided Tour 1121 Insert element 12 clamping elements 121 coupling area 122 Guide entry 13a, 13b Coupling element 131 Transmission element 132 carriers 1321 Sliding surface 133 Middle section 1331 Internal guide 14a, 14b Activation element 15 Compensation mechanism 151 sliding element 1511 sliding track 152 Transfer element 1521 bolts 1522 bolts A actor F Guide pin MA Central Axis

Claims

[1] Clamping device (1) for clamping or gripping an object, comprising - a base body (11) which has an interface (111) for connection with a working or testing machine, wherein the base body (11) extends along a central axis (MA) and has at least four pairs of opposing guides (112) which extend radially to the central axis (MA), - at least four clamping elements (12), one of which is at least partially inserted into a guide (112), wherein the guide (112) holds and guides the clamping element (12) with one linear degree of freedom radially to the central axis (MA), and the clamping element (12) has at least one coupling surface (121) which is oriented inclined to the central axis (MA), - at least two coupling elements (13a, 13b), each of which is kinematically coupled to two clamping elements (12) radially opposite each other to the central axis (MA), wherein the coupling element (13a, 13b) has two transmission elements (131) spaced apart from each other radially to the central axis (MA), which extend at least partially tangentially to the circumferential direction around the central axis (MA), wherein each transmission element (131) is in contact with or can be brought into contact with a coupling surface (121) of a clamping element (12), and wherein the two coupling elements (13a, 13b) are independently and movably mounted in or on the base body (11) in a direction parallel to the central axis (MA). - at least two activation elements (14a, 14b), each of which is connected to one of the coupling elements (13a, 13b), wherein the activation elements (14a, 14b) are arranged to be movable independently of each other relative to the base body (11) at least in one direction parallel to the central axis (MA), wherein when an activation element (14a, 14b) moves in the direction of the central axis (MA), the coupling element (13a, 13b) connected to it also moves in the direction of the central axis (MA), and the interaction of the two transmission elements (131) of the coupling element (13a, 13b) with each coupling surface (121) of a clamping element (12) translates the movement of the coupling element (13a, 13b) into a movement of two clamping elements (12) opposite each other radially to the central axis (MA) in the direction radially to the central axis. [2] Clamping device (1) according to claim 1, characterized by, that the guide (112) has a cavity for receiving a clamping element (12), wherein at least one insertion element (1121) is provided which engages in the cavity and is designed to engage with a clamping element (12) in order to fix the clamping element (12) in a direction parallel to the central axis (MA), wherein the clamping element (12) is movable radially to the central axis (MA) and / or the clamping element (12) is at least partially disk-shaped and is inserted into a cavity arranged in the guide (112) in a sliding fit and / or the coupling surface (121) in the clamping element (12) is arranged in a recess which at least partially penetrates the clamping element (12) tangentially to the circumferential direction around the central axis (MA). [3] Clamping device (1) according to one of the preceding claims, characterized by, that the coupling element (13a, 13b) is designed in a forked shape in some areas, wherein at least two supports (132) are provided spaced apart from each other radially to the central axis (MA), which extend at least in some areas parallel to the central axis (MA), wherein a central section (133) is arranged between the supports (132) and connects the supports (132) and each support (132) carries a transmission element (131), wherein there is a distance in between the connection of the central section (133) with the supports (132) and the connection of the transmission elements (131) with the supports (132). [4] Clamping device (1) according to one of the preceding claims, characterized bythat a compensation mechanism (15) is provided which is connected to the activation elements (14a, 14b), wherein the compensation mechanism (15) is provided to compensate for a difference in the position of the coupling elements (13a, 13b) in the direction of the central axis (MA) and thus a difference in the distance of clamping elements (12) opposite each other radially to the central axis (MA), in particular wherein the compensation mechanism (15) is connected to an actuator (A) via a sliding element (151), wherein the sliding element (151) is movable by the actuator (A) in the direction of the central axis (MA), preferably wherein the sliding element (151) has at least one sliding track (1511) which is formed by a recess in the sliding element (151), wherein the sliding track (1511) extends perpendicular to the central axis (MA). [5] Clamping device (1) according to claim 4, characterized by, that the compensating mechanism (15) has at least two transmission elements (152) which each extend along an element axis, wherein each transmission element (152) is rotatably connected at a first end to an activation element (14a, 14b) and the transmission elements (152) are rotatably connected to each other at a second end opposite the first end in the direction of the element axis and linearly displaceable relative to the sliding track (1511) to the sliding element (151). [6] Clamping device (1) according to claim 5, characterized by, that the transmission elements (152) are designed as planar disks and each have a bore at the first end and at the second end, and the bores at the first end are each connected to an activation element (14a, 14b) via a bolt (1521), and the bores at the second end are connected to each other via a bolt (1522), wherein the bolt (1522), which connects the two second ends together, is in a sliding fit in the sliding track (1511). [7] Clamping device (1) according to any one of claims 4 to 6, characterized by, that the central section (133) has an internal guide (1331), wherein a guide mandrel (F) is inserted in sliding fit through the internal guide (1331) of the central sections (133) of the two coupling elements (13a, 13b) and guides the two coupling elements (13a, 13b) towards each other in the direction of the central axis (MA), wherein the guide mandrel (F) is connected to the sliding element (151) and extends parallel to the central axis (MA). [8] Testing device for optical inspection or measurement of an object, wherein the testing device has at least one object holder rotatable about at least one axis of rotation, wherein the object holder comprises at least one clamping device (1) according to one of the preceding claims 1 to 7, wherein the central axis (MA) of the clamping device (1) is aligned coaxially to the axis of rotation, wherein at least one camera unit is provided which has at least one camera which can be aligned to an object clamped in the clamping device (1), wherein the camera transmits recorded images to a computing unit which is configured to calculate a volume model from several images and to inspect or measure the volume model according to at least one test procedure. [9] Test device according to the preceding claim, characterized by, that the testing device rotates the object holder with the clamping device (1) and the object clamped therein around the axis of rotation, wherein the camera takes several pictures of the object in different rotational positions around the axis and transmits them to the computing unit. [10] Method for measuring an object using a test device according to one of the preceding claims 8 or 9, comprising the method steps A) Clamping an object to be measured between the clamping elements (12) of the clamping device (1), B) Rotating the object mount about the axis of rotation, whereby the camera takes several pictures of the object mounted in the clamping device (1) during the rotation, C) Transmission of images from the camera to the processing unit, D) Calculation of a volume model of the object based on the images by the computing unit, E) Measurement of the volume model, wherein the measurement is based on at least one test specification already stored or entered by an operator.

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