Patent Publication Number: US-2023158642-A1

Title: Clamping device and workpiece holding device with a clamping device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part application of U.S. Patent Application Ser. No. 17/619,042 filed on Dec. 14, 2021, which is a U.S. National Stage of PCT Application No. PCT/EP2020/066101 filed on Jun. 10, 2020, which claims priority to German Patent Application No. 10 2019 116 262.9 filed on Jun. 14, 2019 and entitled “CLAMPING DEVICE AND WORKPIECE HOLDING DEVICE WITH A CLAMPING DEVICE”, the contents each of which are incorporated herein by reference thereto. 
     This application also claims priority under 35 U.S.C. § 119 to the following German Patent Application No. 20 2022 101 810.3, filed on Apr. 5, 2022, the entire contents of which are incorporated herein by reference thereto. 
    
    
     BACKGROUND 
     The invention refers to a clamping device for clamping a support body. The support body can comprise a holding device for holding a workpiece. With such clamping devices workpieces held on the support body can be clamped in a machine tool with high position accuracy. Particularly, clamping devices can be present in different machining stations or in different machine tools such that a uniform clamping is allowed in all stations or machine tools. 
     Such a clamping device is, e.g. known from WO 03/039807 A. The clamping device has a base body having an abutment surface and receptacle holes for clamping bolts of the support body. A clamping body having a clamping end and an operating end is assigned to each receptacle hole. The clamping end of each clamping body can act on a clamping bolt arranged in a receptacle hole and thus clamp the support body on the base body. 
     In an embodiment of the clamping device known from WO 03/039807 A1 the clamping bodies are arranged in pairs respectively and are moved along a common axis in a movement direction between a clamping position and a release position. All of the clamping bodies are supported in a manner to be movable relative to each other in this movement direction. In other embodiments the clamping bodies are arranged such that their longitudinal axis intersect in a common center point. A common hydraulic cylinder or a common rotor with multiple curved surfaces can act on or can move the clamping bodies. 
     The known clamping device has proven itself. Starting from the prior art it can be considered as object of the present invention to improve the clamping accuracy and to concurrently guarantee a simple configuration of the clamping device. 
     The invention also relates to a clamping plate for receiving at least one workpiece clamping device. 
     DE 101 55 077 B4 describes a clamping device which has a vice. The vice is formed to clamp workpieces, for example, between two jaws that can move against each other. On its lower surface, the vice has clamping bolts by means of which it can be fastened to a clamping plate with repeat accuracy. The clamping plate is also referred to as a “reference plane plate”. The clamping plate has openings into which clamping bolts are held by means of a tightening device arranged in the clamping plate. The clamping bolts are both pulled axially into the openings and pressed against the opening wall to find a precise contact there. The reference plane plate has three or four openings to accommodate workpiece clamping devices with three or four clamping bolts. The tightening device has slides which are movable radially to the openings and can be actuated via a wedge-slide mechanism by means of a screw. 
     U.S. Pat. No. 5,167,405 also discloses a workpiece clamping device and an associated clamping plate with slides for tightening clamping bolts which project away from the lower surface of the workpiece clamping device and are received by openings in the clamping plate. The slides are actuated by a central eccentric shaft arranged in the clamping plate. 
     It is also known from DE 10 2017 122 112 A1 to provide a workpiece clamping device for clamping workpieces, the two clamping jaws of which are individually supported on separate linear guides spaced apart from one another. A threaded spindle mounted centrally in a bearing device engages with both clamping jaws. The two linear guides and the bearing device are in turn mounted on a clamping plate, referred to here as the base plate. 
     BRIEF SUMMARY 
     This object is solved by a clamping device as well as a workpiece holding device with a clamping device. Disclosed is a clamping device for clamping of a support body, including: a base body that comprises an abutment surface on a clamping side of the base body, the abutment surface having multiple receptacle holes that open toward the clamping side, the multiple receptacle holes each being configured for location of one of a plurality of clamping bolts of support body; multiple clamping bodies that are linearly movably supported in or on the base body along a longitudinal axis of the base body, the multiple clamping bodies can be moved between a clamping position and a release position by means of an operating device; and wherein longitudinal axes of the multiple clamping bodies define multiple points of intersection with respect to each other. 
     The clamping device according to the invention is configured for clamping a support body. It has a base body having a clamping side. The base body comprises an abutment surface on the clamping side. The abutment surface is configured to abut against a counter abutment surface of the support body, if the support body is clamped on the base body. The abutment surface can be continuously or can be defined by multiple surface sections arranged distant from one another. The abutment surface is preferably orientated parallel to a plane that is spanned by a first direction and a second direction. 
     On the clamping side the base body further comprises multiple receptacle holes that are open toward the clamping side. The receptacle holes can open into the abutment surface or can be arranged with distance to the abutment surface. Each receptacle hole is configured to at least partly locate a clamping bolt of the support body therein. Preferably the receptacle holes extend parallel to each other in a direction orthogonal to the abutment surface. 
     Multiple clamping bodies are arranged in or on the base body. Preferably exactly one clamping body is assigned to each receptacle hole. The clamping bodies are supported in a linearly movable manner along their longitudinal axes. The clamping device has an operating device that is configured to move all of the clamping bodies between a clamping position and a release position. Each clamping body has a clamping end that is assigned to one of the receptacle holes and that projects in the assigned receptacle hole in the clamping position. In the release position each clamping body is farther away from the center axis of the receptacle hole and the clamping end does not project or project less into the receptacle hole than in the clamping position. 
     The longitudinal axes of the clamping bodies of a common clamping body group define multiple intersection points, particularly at least three and preferably four intersection points. Due to this arrangement of the longitudinal axes of the clamping bodies, such that multiple intersection points are defined, a very accurate positioning can be achieved. Remaining inaccuracies in a rotary degree of freedom around an axis orientated orthogonal to the abutment surface can be eliminated. In the prior art longitudinal axes are either identical or intersect in one single intersection point. If all of the longitudinal axes intersect in one common point, a positioning inaccuracy around an axis extending through the intersection point of all of the longitudinal axes of the clamping bodies remains depending on the manufacturing accuracy. 
     The clamping bodies can form multiple clamping body groups. The longitudinal axes of the clamping bodies of a common clamping body group can define one intersection point respectively. In the case of two clamping body groups, for example, a first intersection point and a second intersection point are defined. The first intersection point and the second intersection point are preferably arranged along a straight line extending in a first direction. 
     The longitudinal axis of a clamping body of one clamping body group preferably defines a third intersection point together with a longitudinal axis of a clamping body of another clamping body group. The longitudinal axes of two other clamping bodies of these clamping body groups can define a fourth intersection point. The third intersection point and the fourth intersection point can be located on a common straight line that is preferably orientated in the second direction. 
     It is advantageous, if multiple clamping body groups are present having two clamping bodies respectively. For example, a first clamping body group having a first clamping body and a second clamping body can be present as well as a second clamping body group having a third clamping body and a fourth clamping body. It is particularly advantageous, if the longitudinal axis of the clamping bodies define at least four intersection points. Preferably these four intersection points represent the corners of a polygon that particularly has the form of a rhombus. 
     In a preferred embodiment each clamping body has an operating end opposite its clamping end that is assigned to an operating body of the operating device and preferably abuts against this operating body. The at least one operating body of the operating device is preferably supported in a linearly movable manner in the first direction. It is configured to act on the operating ends of multiple clamping bodies of a common clamping body group. Preferably the clamping body group comprises exactly two clamping bodies. Further preferably multiple clamping body groups and particularly exactly two clamping body groups are provided to each of which one operating body is assigned. By displacing of the operating body the clamping bodies of the assigned clamping body group can be displaced as well in order to switch them between the release position and the clamping position. The longitudinal axes of the clamping bodies of a common clamping body group are particularly neither arranged parallel to each other, nor congruent. They stand obliquely to each other and obliquely to the first direction and/or obliquely to the second direction. Particularly two operating bodies are present that are movably supported in first direction. 
     By means of the operating body, the clamping bodies can be moved between the release position and the clamping position. In the clamping position each clamping body is configured to act on a clamping bolt arranged in a receptacle hole, particularly with a force that comprises force components orthogonal to the abutment surface in the first direction and the second direction. 
     Due to this oblique orientation of the longitudinal axes of the clamping bodies, a simple possibility is provided to apply the clamping bolts with force components that act in two spatial directions, according to the example in the first direction and the second direction. In doing so, the support body can be exactly positioned relative to the base body in the first direction and the second direction in which the abutment surface extends. 
     The operating device operates preferably mechanically and is particularly free of fluidic force transmission units. Preferably the coupling between the at least one operating body and the assigned clamping bodies is a coupling that only transmits pressing or thrust forces and thus no coupling that transmits traction forces. This means the operating body can act on the assigned clamping bodies of a common clamping body group in a pushing manner, particularly for switching the clamping bodies in the respective clamping position, but can however transmit no traction force for counter movement. Particularly the operating body is configured to push the assigned clamping bodies from the release position into the clamping position without traction coupling to the clamping bodies that would allow pulling them from the clamping position back into the release position. Thereby a very simple mechanical configuration of the operating device is obtained. 
     Due to the mechanical operating device, each clamping body is moved in a path-controlled manner in the respective clamping position. It can be guaranteed that the movement paths of the clamping bodies of a common clamping body group have equal amounts. In addition, it can also be guaranteed that the movement paths of all clamping bodies into the respective clamping position have equal amounts. This increases the precision during clamping. By operating the clamping bodies by means of at least one linearly movable operating body and by providing one or more clamping body groups, the receptacle holes can also be arranged with large distance in the first direction and/or the second direction from each other without problems. The operating device is preferably self-locking. Thereby an unintentional disengaging or releasing of the clamping bodies or movement of the clamping bodies out of their clamping positions is avoided. 
     Preferably an operating body directly abuts on the operating ends of the clamping bodies of the assigned clamping body group. 
     The operating device preferably comprises one drive source, e.g. a drive element that can be operated by an operating person or a robot, wherein the drive source can move all of the clamping bodies from a release position into the respective clamping position during operation. For example, a wedge gear coupling exists between this drive source and the clamping bodies. 
     It is further advantageous, if at least one of the receptacle holes is arranged with distance in the first direction from one of the other receptacle holes and/or at least one of the receptacle holes is arranged with distance in the second direction from one of the other receptacle holes. Preferably the receptacle holes define the corners of a polygon. The number of receptacle holes is preferably an even number. Preferably four receptacle holes are provided. 
     It is in addition advantageous, if at least one longitudinal axis of a clamping body and particularly all of the longitudinal axes of all of the clamping bodies are orientated obliquely to the first direction and obliquely to the second direction. In doing so, a force can be applied to the clamping bolts via all of the clamping bodies having a force component in the first direction as well as in the second direction. 
     It is in addition advantageous, if the at least one operating body comprises a front end assigned to the operating ends of the clamping bodies of the assigned clamping body group. On the front end at least one slant is provided that extends obliquely to the first direction and/or to the second direction. Due to this slant, a wedge surface gear coupling can be obtained between the operating body and the clamping bodies being in contact with the operating body. The abutment between the at least one slant and the respective operating end of a clamping body is preferably two-dimensional, but can as an alternative also be line-shaped or point-shaped. 
     It is advantageous, if the operating device comprises a main body that is configured for acting on the at least one operating body. Particularly the main body is arranged in a displaceable or linear movable manner. Preferably the main body is linearly movably arranged in the second direction. 
     The main body can have at least one main body surface that extends obliquely to the first direction and/or the second direction. Against this main body surface the at least one operating body can abut preferably two-dimensionally or as an alternative in a line-shaped or point-shaped manner. 
     Preferably one single main body is provided for operation or displacement of all present operating bodies. The switching movement of all clamping bodies between the release position and the clamping position can be initiated by means of the main body. 
     The main body, the at least one operating body and the clamping bodies are thus linearly displaceably supported either in the first direction or in the second direction or obliquely to the first direction and the second direction. This operating device can be very simply integrated in a plate-shaped base body and can be realized in a flat and space-saving manner. 
     The clamping device comprises another inventive aspect that it can be realized independent from the orientation and arrangement of the clamping bodies, the at least one operating body and the main body described above. Thereby at least one guide channel is provided in the base body, wherein a clamping body is arranged in each guide channel. The at least one operating body and/or the main body can be arranged in addition also in one further guide channel respectively. 
     Each guide channel has two opposed channel walls facing one another. Preferably the channel walls are formed by opposite groove side walls that are connected with each other inside the base body via a groove bottom. The groove is open opposite the groove bottom and preferably closed by a cover that can be releasably attached on the base body. A guide wall section is present in each channel wall. The clamping body or the operating body or the main body abuts only against the guide channel in the area of the two opposite guide channel walls and is apart therefrom arranged with distance to the channel walls. Preferably also a distance exists between the bottom and/or the cover and the body arranged in the guide channel, i.e. the clamping body or the operating body or the main body. In doing so, the friction between the guide channel and the body respectively displaceably arranged therein can be adjusted in a defined manner or minimized. Preferably the contour of the guide channel matches the outer contour of the body (i.e. clamping body or operating body or main body) displaceably supported therein only in the areas of the guide wall sections. Outside of the guide wall sections the guide channel can have an arbitrary contour and the channel walls can be orientated parallel to each other outside the guide wall sections, for example, and can extend parallel to a common center plane that extends along the center of the guide channel respectively. 
     Preferably the guide wall sections can be configured in a trough-shaped manner. The concave-curved trough can have a radius matching the outer radius of an outer surface area of the movably supported clamping body or operating body or main body. 
     Preferably the clamping bodies and/or operating body and/or main body have a cylindrical section between their opposite ends that abuts against the guide wall sections. 
     In all embodiments of the clamping device described above it can be advantageous, if a biasing arrangement is present. The biasing arrangement can bias or urge the clamping bodies in their respective release positions. In their initial position in which they are not subject to an action of an operating body the clamping bodies are therefore in their release position. Preferably the biasing arrangement has one biasing element and particularly exactly one biasing element for each clamping body group. In a preferred embodiment the biasing element is supported directly on the clamping bodies of the clamping body group and is particularly not directly attached to the base body or supported on the base body. In an embodiment the biasing element effects a traction force between the clamping bodies of the clamping body group toward the respective operating body. For example, the biasing element can be a tension spring. Particularly the operating device is, apart therefrom, free of biasing elements that exclusively engage on the clamping bodies or are arranged on the clamping bodies. 
     A workpiece holding device according to the invention comprises a clamping device according to one of the embodiments described above. In addition, a support body having a holding side and an attachment side is provided. The attachment side is preferably facing away from the holding side or provided opposite to the holding side on the support body. For example, the support body can be configured as support plate. On the attachment side a counter abutment surface is provided. The counter abutment surface is configured to abut against the abutment surface of the base body, if the connection between the support body and the clamping device is established. Multiple clamping bolts project from the support body on the attachment side. Preferably the clamping bolts extend parallel to each other. The number of clamping bolts correspond particularly to the number of receptacle holes. If the connection is established, one clamping bolt projects into one receptacle hole respectively. The arrangement pattern or the distances between the clamping bolts therefore correspond to the arrangement pattern or the distances between the receptacle holes. 
     Particularly each clamping bolt has an impingement surface that can be provided by a cone shell surface, for example. The at least one impingement surface extends obliquely to the extension direction of the respective clamping bolt. If the clamping bolt is arranged in the assigned receptacle hole, the impingement surface extends obliquely to the first direction and obliquely to the second direction and obliquely to the extension direction of the clamping bolt. If the assigned clamping body acts on the impingement surface during clamping of the support body on the base body, force components are created in all three spatial directions. The counter abutment surface is pulled against the abutment surface orthogonal to the first direction and orthogonal to the second direction. Concurrently, the clamping bolt is pushed in the first direction and the second direction by the clamping body. The clamping bolts are thus subject to a traction force parallel to their extension direction and are concurrently pushed away from each other in the first direction and the second direction, such that a precise positioning and orientation of the support body on the base body occurs. 
     An object of the present disclosure is to have all clamping slides act on the clamping bolts with essentially the same forces. 
     Disclosed is a clamping plate for receiving at least one workpiece clamping device or a workpiece, the clamping plate including: a support surface for the at least one workpiece clamping device or the workpiece, the support surface is penetrated by a plurality of openings for receiving clamping bolts of the at least one workpiece clamping device, clamping slides being arranged in the clamping plate, the clamping slides each project with one end into one of the plurality of openings in a clamping position and are located outside the one of the plurality of openings in a release position, a clamping wedge, which is movably arranged in the clamping plate and is operatively connected to the clamping slides via at least one spring means. 
     The clamping plate according to the present disclosure serves to receive at least one workpiece clamping device, for example in the form of a vice which has a flat base surface from which a plurality of clamping bolts project away. The clamping plate according to the present disclosure can also be used for directly receiving a workpiece to whose base surface clamping bolts have been attached in a preparatory operation. The following description of the clamping plate and the workpiece clamping device to be mounted with it applies equally to clamping plates which directly receive a workpiece provided with clamping bolts. 
     The clamping plate has a support surface for this or a similar workpiece clamping device, with several openings being provided in the support surface for receiving the clamping bolts of the workpiece clamping device. A tightening device is provided in the clamping plate, which serves to fix and position the clamping bolts in the openings. For this purpose, the tightening device has several clamping slides, whereby, at least preferably, exactly one clamping slide is assigned to each opening. The clamping slides are each movable radially relative to their openings between a clamping position and a release position. In the clamping position, they are located with a preferably wedge-shaped end inside the opening, while in a release position they are located completely outside the opening. The clamping slides are configured to press the clamping bolts against the opposite bore wall, which is preferably formed as a reference surface. As a result of the wedge shape of the end of the clamping slide that enters the opening, the clamping bolt is simultaneously pulled down in the axial direction so that the lower surface of the workpiece clamping device is pressed against the support surface of the clamping plate. 
     A clamping wedge being also a part of the tightening device and used to actuate the clamping slides of the tightening device is arranged in the clamping plate so that it can move, preferably linearly, and to which the clamping slides are operationally connected via at least one spring means. The spring means is preferably a hard spring which transmits the necessary actuating force for the clamping slide from the clamping wedge to the clamping slide when deformed by a few hundredths of a millimeter. Preferably, the spring is a non-linear spring with a digressive characteristic. 
     The spring means is used to transmit the actuating force from the clamping wedge to the clamping slide. Each clamping slide can be assigned a spring acting much more weakly in the opposite direction, by means of which the clamping slide is preloaded to its release position. This makes it easier to release the workpiece clamping device from the clamping plate. 
     The clamping wedge preferably has clamping surfaces arranged diametrically opposite each other, the distance between which varies along its direction of movement. The surfaces can be flat surfaces or curved surfaces. The clamping wedge serves to urge two force transmission elements away from each other when it is moved in the clamping direction. The force transmission elements can be formed by the spring means by means of which the clamping force is transmitted from the clamping wedge to the clamping slides. 
     The spring means can be formed as a body resilient in several radial directions. Preferably, it is resilient in the longitudinal directions of the two clamping slides in contact with it and also in the direction away from the wedge (radially to the clamping rod). The body forming the spring means can, for example, be a hollow body, in particular an annular body such as a hollow cylinder or other rotationally symmetrical body. The axis of symmetry of this body is preferably oriented transverse to its displacement and force transmission direction. 
     This can have a constant or also varying wall thickness. Further preferably, a stop means is provided in the spring means, which can preferably be formed as a rigid body, for example as a bolt or also a ball. The stop means is arranged with clearance in the spring means, whereby the spring means and the stop means can, for example, jointly define an annular gap. The width of this annular gap is preferably large enough for the spring means to have sufficient spring travel for its function. The spring travel is preferably greater than the tolerance to be compensated. On the other hand, the gap width is preferably so small that the spring means finds firm contact with the stop means before it is overloaded. 
     The stop means, i.e. a bolt for example, can be arranged stationary in the clamping plate. Alternatively, the bolt can be arranged movably, for example floating, in the clamping plate. 
     During clamping, the corresponding clamping bolts are subjected to a clamping force which comprises both an axial component, which pulls the clamping bolt into the opening, and a radial component, as a result of which the clamping bolt laterally resiliently contacts a point on the bore wall locally. By simultaneously actuating the tightening devices for all clamping bolts, it is ensured that the clamping bolts are tightened at the same time and the workpiece clamping device is thus positioned in the desired position. 
     Several such clamping plates can also be provided and arranged in a fixed spatial relationship to one another in a machine tool. Such an arrangement comprises at least two clamping plates according to the present disclosure with their own tightening devices. These have actuating rods coupled to one another or a common actuating rod. By this measure, the tightening devices of two or more clamping plates can be actuated together and simultaneously from one operating position. 
     If the tightening devices are actuated in series, incorrect positioning could otherwise occur. In any case, however, the concept according to the present disclosure saves operating effort and makes it possible to actuate several clamping plates from one side. This is particularly advantageous when mounting the clamping plates in enclosed working areas of machine tools where access to the clamping devices is restricted, for example, is only possible from one side. 
     In a preferred embodiment, the common actuating rod or the two actuating rods in contact with each other directly or with the aid of an intermediate piece are arranged in the clamping plates so as to be axially movable. The tightening and loosening of the tightening devices are then effected by axial movement of the actuating rod(s). 
     The actuating rods, which are in direct contact with each other at the end faces or with the interposition of an intermediate piece and are thus coupled in terms of movement, are preferably arranged in alignment with each other. In this way, the actuating movement of an actuating rod of one clamping plate is transmitted to the actuating rod of another clamping plate. 
     Each clamping plate preferably has a through opening in which the actuating rod is axially movably arranged. The through opening is preferably arranged parallel to a flat upper surface formed on the clamping plate. The clamping movement of the actuating rod can thus be introduced into the actuating rod from one of the side surfaces of the clamping plate. 
     Preferably, the through opening has an anchoring structure at its two ends, which is formed by an internal thread, for example. This is suitable for receiving and anchoring a spring means to preload the actuating rod in one direction, preferably in the release direction. At the other end of the through opening, an adjusting means, for example in the form of a screw, can be provided on the internal thread or other anchoring structure. By turning the screw, the actuating rod can be moved axially and thus tightening or loosening of the tightening device can be effected. 
     The actuating rod preferably has a wedge structure engages with at least one slide belonging to the tightening device. The wedge structure can be formed by an inclined surface formed on the actuating rod itself or also by an inclined surface provided on a wedge which is held on the actuating rod in an axially non-displaceable manner. The inclined surface is inclined against the longitudinal direction of the actuating rod. 
     The slide engages with at least one, preferably two clamping slides, each of which is assigned to one of the openings and arranged radially to it. In the clamping position, the clamping slide projects into the opening. In the release position, it is retracted from the opening. Preferably, a spring means is provided which preloads the clamping slide radially outwards with respect to the opening. The slide and the clamping slide preferably form a reduction gear, i.e. a stroke of the slide is translated into a stroke of the clamping slide that is at most as great as the stroke of the slide. Preferably, at least the actuating rod, the slide and the clamping slide form a reduction gear. 
     The slide and the clamping slides are preferably arranged in pockets of trapezoidal, rectangular or square cross-section, which are closed on one flat side of the clamping plate by one or more covers. This not only has manufacturing advantages, but also the additional benefit that the clamping plates can be provided with a continuous actuating rod which can be inserted into the aligned through-holes for assembly. The actuating rod can be inserted by first removing at least the slides from the clamping devices. After the actuating rod has been inserted, the slides can be inserted into their pockets and secured therein by fitting the cover. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantageous embodiments of the invention are derived from the dependent claims, the description and the drawings. In the following preferred embodiments of the invention are described in detail based on the attached drawings. The drawings show: 
         FIG.  1    a schematic side view of an embodiment of a workpiece holding device comprising a support plate having a holding device for a workpiece, as well as a clamping device for the support plate, 
         FIG.  2    a sectional illustration of a part of the clamping device of  FIG.  1    showing a clamping body and an assigned receptacle hole with a clamping bolt arranged therein, wherein the clamping body is in a release position, 
         FIG.  3    the illustration of  FIG.  2   , wherein the clamping body is in a clamping position, 
         FIG.  4    a schematic illustration of the clamping device of  FIG.  1    in a section transverse through the receptacle holes, 
         FIG.  5    a schematic illustration of the force components introduced from a clamping body into a clamping bolt in a first direction and a second direction, 
         FIG.  6    a schematic illustration of the orientation of the longitudinal axes of the clamping bodies and the definition of multiple intersection points by the longitudinal axes of the clamping bodies and 
         FIG.  7    a schematic illustration in part of the base body and the clamping device of  FIGS.  1  and  4    in a cross-section through a guide channel for a clamping body. 
         FIG.  8 A  illustrates a simplified perspective view of a workpiece clamping device and an associated clamping plate, 
         FIG.  9    illustrates a vertical section of the workpiece clamping device and the clamping plate, 
         FIG.  10    illustrates a tightening device of the clamping plates shown in  FIGS.  1  and  2    in a schematic representation, 
         FIG.  11    illustrates a clamping plate with several opening groups, 
         FIG.  12    illustrates an arrangement consisting of several clamping plates, each with several opening groups. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    schematically shows an embodiment of a workpiece holding device  10  having a clamping device  11  and a support body  12 . The support body  12  has a holding side  13  and an attachment side  14  facing away from the holding side  13 . The support body  12  can be configured as support plate, wherein the holding side  13  and the attachment side  14  are formed by opposite sides of the support plate. The support body  12  comprises a holding device  15  for holding a workpiece  16  on the holding side  13 . The holding device  15  can comprise clamping jaws  17 , for example, in order to hold the workpiece  16  in a clamping manner on the support body  12 . 
     On the attachment side  14  the support body  12  has multiple clamping bolts  18  that project from the support body  12 . In the embodiment the clamping bolts  18  are orientated parallel to one another and extend in an axial direction A with reference to the support body  12 . Each clamping bolt  18  can comprise at least one cylindrical section. At an end distant to the support body  12  each clamping bolt  18  has a chamfer or a conically tapering end section  19 . Thereby the introduction of the clamping bolt  18  in an assigned receptacle hole  20  of the clamping device  11  is simplified. On the free end each clamping bolt  18  can have a face cavity  21  in the face. 
     In addition each clamping bolt  18  comprises at least one impingement surface  22 . The impingement surface  22  extends obliquely inclined to the axial direction A. In the illustrated embodiment each clamping bolt  18  has exactly one impingement surface  22  that is formed by the outer surface of a conical section  23  of clamping bolt  18 . The conical section  23  expands in axial direction A away from the support body  12  toward the free end of clamping bolt  18 . The conical section  23  is arranged with distance to the support body  12  and the end section  19  according to the example. A tapering section  24  of clamping bolt  18  can be provided between conical section  23  and support body  12 . The tapering section  24  can also be formed by the outer surface of a cone. A cylindrical section can be provided between tapering section  24  and conical section  23 . As an alternative, tapering section  24  and conical section  23  can also directly transition into one another. Thereby a constriction is formed on clamping bolt  18  with distance from end section  19  and with distance from support body  12 . 
     The clamping device  11  has a base body  28 . The base body  28  has an abutment surface  30  on a clamping side  29 . The abutment surface  30  is configured to abut against a counter abutment surface  31  provided on the support body  12 , if support body  12  is arranged or clamped by means of the clamping bolts  18  on the clamping device  11  or base body  28 . Preferably the abutment surface  30  extends in a plane that is spanned by a first direction x and a second direction y. The first direction x and second direction y are related to a coordinate system of clamping device  11  or base body  28 . In this coordinate system the third direction z is orientated orthogonal to the first direction x and second direction y. If the connection between support body  12  and clamping device  11  is established, clamping bolts  18  approximately extend in third direction z. 
     Counter abutment surface  31  extends preferably in a plane orientated orthogonal to axial direction A. Abutment surface  30  and counter abutment surface  31  are configured for two-dimensional abutment against one another. As an alternative to this configuration it is also possible to configure base body  28  and/or support body  12  in a manner such that instead of a two-dimensional abutment, a line-like or point-shaped contact is formed on several locations and for example at least one or exactly three contact locations arranged with distance to one another, if the connection between support body  12  and clamping device  11  is established. The abutment surface  30  or the counter abutment surface  31  could comprise, for example, three convex, particularly dome-shaped elevations against which the respective other surface (i.e. counter abutment surface  31  or abutment surface  30 ) abuts in a point-shaped manner. 
     For each present clamping bolt  18  one assigned receptacle hole  20  is provided in the base body  28  that is open toward the clamping side  29 . In the embodiment the receptacle holes  20  open out into the abutment surface  30 . The receptacle holes  20  are configured as blind holes in the embodiment and are closed on the bottom side of base body  28  opposite the clamping side  29  by means of one hole bottom  32  respectively. As an option, an elastically deformable element  33  is arranged on the hole bottom  32  projecting into the receptacle hole and applying a force in the third direction z onto an assigned clamping bolt  18 , if clamping bolt  18  is completely arranged in receptacle hole  20  and counter abutment surface  31  abuts against abutment surface  30 . The force in the third direction z can be created by elastical deformation of element  33 . The elastically deformable element  33  can thereby engage into the face cavity  21  of the assigned clamping bolt  18 . Due to this force, release of the clamping connection between support body  12  and clamping device  11  can be simplified. 
     In the embodiment clamping device  11  has four receptacle holes  20 . The receptacle holes  20  form corner points of a rectangle according to the example ( FIGS.  4  and  6   ). Accordingly, four clamping bolts  18  are provided on support body  12 , the arrangement and distance of which corresponds to the arrangement and distance of the receptacle holes  20 . 
     Clamping device  11  has multiple clamping bodies  36  that are arranged in a linearly movable manner on and according to the example, in base body  28 . Each clamping body  36  is movably supported in a guided manner in a guide channel  37 . The guide channels  37  are introduced into base body  28 , preferably by milling. Each guide channel  37  for a clamping body  36  opens out into a receptacle hole  20 . 
     In the embodiment the guide channels  37  are groove-shaped and have two opposite channel walls  38  that are connected with one another via a channel bottom  39  ( FIG.  7   ). On the side opposite the channel bottom  39  the guide channel  37  is open to the clamping side  29  and according to the example, closed by means of a cover  40 . Cover  40  is arranged such that it does not project beyond the plane in third direction z in which the abutment surface  30  or counter abutment surface  31  extends, if the connection with support body  12  is established. Preferably the outer surface of cover  40  accessible on the clamping side  29  is arranged with distance to abutment surface  30 . As an alternative to this, outer surface of cover  40  accessible from the clamping side  29  can form a section of the abutment surface  30 . Cover  40  is preferably arranged in a cover holding cavity  41  adjoining the clamping side  29 . The cover holding cavity  41  forms a depression or cavity in base body  28  and comprises support surfaces for cover  40  in order to be able to attach cover  40  on base body  28 , for example by means of a screw connection. 
     Each channel wall  38  has a guide wall section  42 . Outside of the respective guide wall section  42  the channel wall  38  extends in a plane, according to the example, that is orientated parallel to the third direction z in the embodiment. Preferably a contact between clamping body  36  and channel wall  38  does not exist outside of the respective guide wall section  42 . Preferably no contact exists between clamping body  36  and channel bottom  39  and/or cover  40  outside of guide wall sections  42 . 
     The guide wall sections  42  are configured in a trough-shaped manner according to the embodiment. Accordingly, the areas of the guided clamping body  36  in abutment with the guide wall sections  42  are curved in a convex manner. With view onto channel wall  38 , each guide wall section  42  can be curved in a concave manner with a radius corresponding to the outer radius of a cylindrical or in part cylindrical section of clamping body  36 . By means of the two opposite guide wall sections  42 , clamping body  36  can thus be movably arranged in a guided manner inside guide channel  37  in the guide wall sections  42 . 
     The guide wall sections  42  are preferably directly formed by an area or the material of base body  28 . 
     It is noted here that the arrangement of clamping body  36  in guide channels  37 , as described above based on  FIG.  7   , can be realized independent from other configuration features of clamping device  11 . 
     In the embodiment illustrated here exactly one clamping body  36  is assigned to each present receptacle hole  20  ( FIG.  4   ). The provided clamping body  36  form multiple clamping body groups, wherein in the embodiment a first clamping body group  50  and a second clamping body group  51  are present. Each clamping body group  50 ,  51  has exactly two clamping bodies  36  in the embodiment. A first clamping body  36   a  and a second clamping body  36   b  are part of first clamping body group  50  and a third clamping body  36   c  and a fourth clamping body  36   d  are part of the second clamping body group  51 . First clamping body  36   a  has a first longitudinal axis L 1  and is movably arranged in the assigned guide channel  37  along its first longitudinal axis L 1 . Second clamping body  36   b  has a second longitudinal axis L 2  and is movably supported in the assigned guide channel  37  along the second longitudinal axis L 2 . Third clamping body  36   c  has a third longitudinal axis L 3  and is movably supported in the assigned guide channel  37  along the third longitudinal axis L 3 . Fourth clamping body  36   d  has a fourth longitudinal axis L 4  and is movably supported in the assigned guide channel  37  along the fourth longitudinal axis L 4 . If in the following longitudinal axis L of a clamping body  36  is mentioned, this means the respective longitudinal axis L 1  or L 2  or L 3  or L 4  of first or second or third or fourth clamping body. 
     Each clamping body  36  can be moved between a release position F ( FIGS.  1  and  2   ) and a clamping position S ( FIGS.  3 - 5   ) by means of an operating device  52  of clamping device  11 . In the clamping position S the clamping body  36  engages in the assigned receptacle hole  20  and can act on a clamping bolt  18  arranged there in order to immovably clamp support body  12  with workpiece  16  on base body  28  of clamping device  11 . For this each clamping body  36  has a clamping end  53  assigned to the receptacle hole  20  in the embodiment. The clamping body  36  has a clamping surface  54  extending obliquely to the longitudinal axis L of clamping body  36  in the clamping end  53 . The clamping surface  54  is in addition inclined with regard to a third direction z and extends preferably parallel to the second direction y. Clamping surface  54  can have approximately the same inclination with regard to third direction z as impingement surface  22  with regard to axial direction A. In doing so, a two-dimensional or line-shaped contact can be established between clamping surface  54  of clamping body  36  and impingement surface  22  of clamping bolt  18 . 
     As apparent from  FIG.  3   , by means of the surfaces  22 ,  54  orientated obliquely to third direction z, a traction force FZ can be created on clamping bolt  18  that in turn provides for pressing of abutment surface  30  and counter abutment surface  31  against one another. Therefore, a very precise positioning of support body  12  on base body  28  of clamping device  11  in this third direction z is guaranteed. 
     It is also apparent from  FIGS.  4  and  5    that clamping body  36  in addition applies a longitudinal force FL onto the assigned clamping bolt  18  in the clamping position S that is orientated along or parallel to the respective longitudinal axis L. As illustrated in  FIG.  4   , all of the longitudinal axes L, i.e. first longitudinal axis L 1 , second longitudinal axis L 2 , third longitudinal axis L 3  and fourth longitudinal axis L 4  extend obliquely inclined with regard to first direction x and second direction y respectively. In doing so, longitudinal force FL comprises a first force component FX in first direction x and a second force component FY in second direction y ( FIG.  5   ). Thus, each clamping bolt  18  is subject to a traction force FZ in third direction z, as well as a first force component FX in first direction x and a second force component FY in second direction y, due to the engagement of a clamping body  36  being in clamping position S. Clamping bolts  18  are thus urged away from each other in first direction x, as well as in second direction y, if the clamping bodies  36  are in the clamping position S. Thereby a very accurate positioning of support body  12  with workpiece  16  in first direction x and second direction y on base body  28  of clamping device  11  is guaranteed. 
     The positioning is further improved and more accurate in that the longitudinal axes L of clamping bodies  36  define multiple points of intersection arranged with distance from one another, as schematically illustrated in  FIG.  6   . First longitudinal axis L 1  of clamping body  36   a  and second longitudinal axis L 2  of clamping body  36   b , that both belong to first clamping body group  50 , form a first intersection point P 1 . Third longitudinal axis L 3  of third clamping body  36   c  and fourth longitudinal axis L 4  of fourth clamping body  36   d  that both belong to the second clamping body group  51  define a second intersection point P 2 . In the embodiment described here the first intersection point P 1  and the second intersection point P 2  are arranged on a common first straight line G 1  extending parallel to the first direction x. 
     In the embodiment first longitudinal axis L 1  of first clamping body  36   a  and third longitudinal axis L 3  of third clamping body  36   c  define a third intersection point P 3 . Second longitudinal axis L 2  of second clamping body  36   b  and fourth longitudinal axis L 4  of fourth clamping body  36   d  define a fourth intersection point P 4 . Third intersection point P 3  and fourth intersection point P 4  are thus defined by longitudinal axes L 1  and L 3  or L 2  and L 4  that are part of clamping bodies  36   a  and  36   c  or  36   b  and  36   d  of different clamping body groups  50  or  51 . According to the example, third intersection point P 3  and fourth intersection point P 4  are arranged on a common second straight line G 2  extending in the second direction y. 
     In the embodiment the four intersection points P 1  to P 4  form the corner points of a rhombus in a plane parallel to the abutment surface  30 . The distance between the first intersection point P 1  and the second intersection point P 2  is preferably different from the distance between the third intersection point P 3  and fourth intersection point P 4 . 
     In the embodiment the two straight lines G 1  and G 2  intersect in a center point that also is the intersection point of the straight lines that connect the receptacle holes  20 . 
     Due to the definition of multiple intersection points P 1  to P 4  by longitudinal axes L 1  to L 4  of clamping bodies  36 , also a rotational degree of freedom around an axis extending in third direction z is very well eliminated and the positioning accuracy of support body  12  relative to base body  28  is further increased. 
     The arrangement and orientation of the longitudinal axes L of clamping body  36  and the definition of intersection points P 1  to P 4  can be realized independent from other configurations of a clamping device  11  or workpiece holding device  10 . 
     An embodiment of the operating device  52  is illustrated in  FIG.  4   . The operating device  52  has preferably one single drive source in order to switch all of the clamping bodies  36  between the release position F and the clamping position S. Thus, all of the clamping bodies  36  are in the release position F, if one of the clamping bodies  36  is in the release position F and vice versa all of the clamping bodies  36  are in the clamping position S, if one of the clamping bodies  36  is in the clamping position S. In the embodiment an operating screw  57  serves as a drive source that is rotatably supported in a nut  58 . The nut  58  is seated in a torque-proof manner on base body  28 . By rotation of the operating screw  57 , the operating screw  57  can thus be displaced along its rotation axis that extends in second direction y in the embodiment. By means of the operating screw  57 , a main body  59  being in abutment therewith can be displaced linearly parallel to its extension and according to the example, in second direction y. Thereby an abutment contact exists between main body  59  and operating screw  57 . 
     The operating screw  57  can be rotated by means of a tool, for example. The tool can be handled by an operating person. The tool can also be provided on a robot arm or another machine device. 
     On its end opposite the operating screw  57  the main body  59  has at least one and in the embodiment two main body surfaces  60  orientated obliquely to the second direction y and obliquely to the first direction x. The main body tapers in a wedge-shaped manner toward its end due to the two main body surfaces. The main body surfaces  60  are respectively configured as abutment surface for one operating body end surface  61  of an operating body  62 . According to the example, the inclination and orientation of the operating body end surface  61  of a respective operating body  62  is orientated parallel to the main body surface  60  against which the operating body end surface  61  abuts. Each operating body end surface  61  is thus orientated obliquely to the first direction x and obliquely to the second direction y. The main body surfaces  60  and the operating body end surfaces  61  are preferably planar surfaces and extend parallel to the third direction z according to the example. 
     The operating device  52  comprises one operating body  62  for each present clamping body group  50 ,  51 . Thus, in the embodiment two separate operating bodies  62  are provided. According to the example, each operating body  62  is linearly displaceably supported. The two operating bodies  62  are linearly displaceably supported in first direction x in the embodiment. As particularly apparent from  FIG.  4   , the operating bodies  62  can be arranged along a common axis. On their one end they comprise the operating body end surface  61  and on an opposite front end with view in first direction x they comprise at least one slant  63 . For each clamping body  36  of the assigned clamping body group  50 ,  51  one slant  63  is provided. Thus, each operating body  62  has two slants  63  in the embodiment. The slants  63  of an operating body  62  are orientated obliquely to the first direction x and the second direction y respectively and are preferably configured as planar surfaces that extend parallel to the third direction z. Due to the two slants  63 , the operating body  62  tapers in a wedge-shaped manner toward the free end that is assigned to the clamping bodies  36 . 
     Each clamping body  36  has a clamping body end surface  65  on its operating end  64  opposite the clamping end  53  configured for abutment with the assigned slant  63 . The clamping body end surface  65  is respectively inclined with regard to the first direction x and inclined with regard to the second direction y and is according to the example, orientated parallel to the third direction z and corresponds in its inclination and orientation to the assigned slant  63 . 
     The operating device  52  thus forms a wedge surface gear between main body  59  and operating body  62 , as well as between operating bodies  62  and clamping bodies  36 . The connection between main body  59  and operating body  62  is exclusively an abutment contact and cannot transmit traction forces. The connection between the operating body  62  and the clamping bodies  36  is an abutment contact and cannot transmit traction forces. 
     The operating device  52  is configured without fluidic force transmission. It does not contain fluid components such as pistons or cylinders. The operating device  52  operates exclusively mechanically according to the example. 
     The clamping device  11  has in addition a biasing arrangement  70 . The biasing arrangement  70  is configured to bias or urge clamping bodies  36  in their release position F. For this, clamping bodies  36  can be subject to an elastical force that pulls or pushes clamping bodies  36  along their respective longitudinal axis L away from the assigned receptacle hole  20  toward the release position F. 
     In the embodiment illustrated here one biasing element  71  of biasing arrangement  70  is assigned to each clamping body group  50 ,  51 . Two biasing elements  71  are thus sufficient. In the embodiment the biasing elements  71  are not directly supported on base body  28 , but connect the clamping bodies  36  of a common clamping body group  50  or  51  directly. A first biasing element  71  connects first clamping body  36   a  with second clamping body  36   b  and a second biasing element  71  connects third clamping body  36   c  with fourth clamping body  36   d . The biasing elements  71  effect a traction force and are attached to the clamping bodies  36  in the area of the operating end. Due to the traction force of biasing elements  71 , the clamping body end surfaces  65  of clamping bodies  36  of a common clamping body group  50  or  51  are urged against the respectively assigned slant  63  of operating body  62  that is assigned to the clamping body group  50  or  51 . This in turn results in that the operating body end surfaces  61  of operating bodies  62  are urged against the respectively assigned main body surface  60  of main body  59  in order to support the force acting on the operating bodies  62  by means of the biasing elements  71 . Main body  59  supports the impinging force on operating screw  57 . Operating screw  57  supports the force on base body  28  via nut  58 . The thread connection between operating screw  57  and nut  58  is self-locking such that the force applied to the operating screw  57  in second direction y cannot result in that the operating screw  57  moves in second direction y. Between main body  59  and operating body  62  on one hand and between operating body  62  and clamping bodies  36  on the other hand, an abutment contact is continuously established in the embodiment. 
     As an alternative to the embodiment illustrated in  FIG.  4   , a separate biasing element  71  could be assigned to each clamping body  36  that is supported on base body  28 . In the illustrated embodiment the biasing element  71  can be tension springs, e.g. helical springs, that are arranged in cavities of clamping bodies  36  that are open toward the respective operating end  64 . The cavities are not illustrated for sake of clarity in  FIG.  4   . 
     The operating device  52  operates as follows: 
     In a retracted position of main body  59  the operating bodies  62  are sufficiently close adjacent to one another in first direction x that the clamping bodies  36  being in abutment therewith are urged in the release position F by means of biasing arrangement  70  and release the receptacle holes  20  for insertion of clamping bolts  18 . After arrangement of clamping bolts  18  in the receptacle holes  20 , main body  59  can be moved in second direction y by operating screw  57  and displace the two operating bodies  62  from each other. This in turn results in that the clamping bodies  36  being in abutment against slants  63  are moved along their respective longitudinal axis in the assigned receptacle hole  20  and into the clamping position S. Due to the inclination of screw thread between operating screw  57  and nut  58  the operating device  52  is configured in a self-locking manner. Independent from a force acting on the linearly displaceably supported main body  59  in second direction y, the operating screw  57  remains in its axial position relative to nut  58  and thus maintains clamping position S. This is because an annulation of this clamping position is mechanically blocked by means of the mechanical abutment between clamping bodies  36  against operating bodies  62  and the operating bodies  62  against main body  59 . 
     Release of the clamping connection is carried out in that operating screw  57  is rotated in release direction, whereby main body  59  can be moved in second direction y, such that approaching of the two operating bodies  62  in first direction x is possible. Main body  59  is at least partly removed out of the interstice between the two operating bodies  62  so-to-speak. In doing so, operating bodies  62  are moved in first direction x toward one another, which is effectuated by the force of the biasing arrangement  70  and according to the example, the two biasing elements  71 . This in turn results in that each clamping body  36  is moved away along its respective longitudinal axis L from the assigned receptacle hole  20  and can take its release position F. 
     In the release position F clamping bolts  18  are not held on base body  28  by the clamping bodies  36 . The optionally provided elastically deformable elements  33  have the effect that clamping bolts  18  are at least slightly urged out of the receptacle holes  20  in order to simplify removal of support body  12  from clamping device  11 . 
     With regard to  FIG.  7   , the guide of clamping bodies  36  in guide channels  37  has been explained. In addition or as an alternative to this guidance of clamping bodies  36 , also the at least one operating body  62  and/or the main body  59  can be guided in this manner. It is therefore also possible to provide a guide channel  37  for each present operating body  62  or for main body  59  that is provided according to the example, as it has been described and explained for clamping body or clamping bodies  36  based on  FIG.  7   . 
     The invention refers to a clamping device  11  and is configured for releasably clamping a support body  12  on which a workpiece  16  can be arranged. The clamping device  11  has a base body  28  with receptacle holes  20  for location of one clamping bolt  18  of support body  12  respectively. Each clamping body  36  is linearly movable along its longitudinal axis L between a clamping position S and a release position F. The movement from the release position F into the clamping position S and/or vice versa from the clamping position S into the release position F can be carried out by means of an operating device  52 . Each clamping body  36  has a clamping end  53  that projects into an assigned receptacle hole  20  in the clamping position S. The longitudinal axes of clamping bodies  36  define multiple points of intersection in a common projection plane parallel to which the longitudinal axes L extend. In a preferred embodiment at least three or four points of intersections are defined. Particularly four clamping bodies  36  with respectively one longitudinal axis L can be provided, wherein four points of intersections are defined in that two of the provided longitudinal axes L 1 , L 2  or L 3 , L 4  or L 1 , L 3  or L 2 , L 4  intersect in each case. 
     Referring now to  FIGS.  8 A- 12    an embodiment of the present disclosure is illustrated. 
       FIG.  8 A  illustrates a device  110  for holding a workpiece clamping device  111  or for directly holding a workpiece. The device  110  comprises at least one clamping plate  112 , which can be arranged in a machine tool, for example, in order to support the workpiece clamping device  111  in a predetermined nominal position. Optionally, one or more further clamping plates  113 ,  123 ,  123 ′ ( FIG.  11   ,  FIG.  12   ) may be provided. The clamping plates  112 ,  113 ,  123 ,  123 ′ can be of substantially the same design as one another, so that the following description of the clamping plate  112  applies correspondingly to the clamping plate  113  and in a transferred manner also to the multi-nested clamping plates  123 ,  23 ′. 
     The clamping plate  112  has several, for example four, openings  114 ,  115 ,  116 ,  117 , which serve to receive clamping bolts  118  of the workpiece clamping device  111  or a workpiece.  FIG.  9    shows an example of such a clamping bolt  118  engaging in the opening  114 . Several clamping bolts project away from the lower surface of the guide body  119 , the arrangement of which corresponds to the arrangement of the openings  114  to  117 . 
     The workpiece clamping device  111  has a guide body  119  on which at least one or two clamping jaws  120 ,  121  are movably mounted in order to grip and firmly hold a workpiece between them. 
       FIG.  10    illustrates the clamping plate  112  and its tightening device  124 . This comprises an actuating rod  125  arranged axially displaceably in a through bore  127  passing through the clamping plate  112  parallel to its upper surface  126 . The actuating rod  125  is, for example, a round rod which, for actuating the tightening device, has two opposing lateral recesses or which supports a wedge  136  with two inclined surfaces  128 ,  129 . Alternatively, the inclined surfaces  128 ,  129  may be formed directly on the actuating rod  125 , as illustrated in  FIG.  12   . The inclined surfaces can be formed as flat wedge surfaces. However, it is also possible to form the inclined surfaces  128 ,  129  as curved surfaces, as can be seen from  FIGS.  11  and  12   . 
     The wedge  136  is operatively connected to clamping slides  132 ,  133 ,  134 ,  135  via spring means  130 ,  131  to urge them apart. The spring means  131 ,  132  are arranged on both sides of the wedge  136  and are in contact with its inclined surfaces  128 ,  129  on the one hand and with end surfaces of the clamping slides  131 - 135  on the other. The spring means  130 ,  131  are movable in pockets of the clamping plate  112  transversely to the actuating rod  125 . 
     The spring means  130 ,  131  are preferably of identical design. In the above example, they are formed by hollow bodies, e.g. in the form of circular rings of hollow cylindrical shape which spring in the radial direction. They are preferably made of steel and can spring in the radial direction by a few hundredths of a millimeter without being damaged. A somewhat larger spring stroke of one or a few 10ths of a millimeter may also be provided. The spring means  130 ,  131  may have a cylindrical outer surface. Alternatively, if the wedge  136  is formed as a rotary member, they may have a double-curved outer surface. 
     Each annular spring means  130 ,  131  encloses an inner space in which a stop means  130 ′,  131 ′ is arranged. These stop means are formed, for example, by cylindrical bolts which are arranged in the respective spring means  130 ,  131  with a clearance of preferably a few tenths of a millimeter. The stop means  130 ′,  131 ′ can be arranged in the clamping plate  112  in a fixed position or also movable in radial direction in order not to hinder a movement of the respective spring means  130 ,  131  as a whole, but only to limit its radial deformation. 
     The clamping slides  132  to  135  are each individually assigned to the openings  114  to  117 . The clamping slide  132  is located in a channel in which it can move radially to the opening  114  in such a way that it either projects into the opening  114  in a clamping position or stands outside it in a release position. The same applies to the opening  115  and the clamping slide  133 , the opening  116  and the clamping slide  134  as well as the opening  117  and the clamping slide  135 . The clamping slides  132 , and  134  as well as the clamping slides  133  and  135  are each connected in pairs to one another by a tension spring  137 ,  138  or are preloaded to their rest position outside the respective opening  114  to  117  by another spring means, not illustrated. 
     With their ends facing away from the openings  114  to  117 , the clamping slides  132  to  135  are in contact with, for example, the cylindrical outer surface of the respective spring means  130 ,  131 . This forms a sliding gear in which a displacement of the actuating rod  125  in  FIG.  10    upwards forces the spring means  130 ,  131  apart, whereby the spring means  130 ,  131  in turn force the clamping slides  132 ,  134  or  133 ,  135  apart, so that their ends penetrate the bores  114  to  117 .  FIG.  9    illustrates this using the example of the slide  132 , the opening-side end of which then moves into the hole  114  and penetrates there into a groove of the clamping bolt  118  with a trapezoidal cross section. Thereby, by interaction of the end of the clamping slide  132  with one of the groove flanks, the clamping bolt  118  is drawn vertically into the opening  114 , whereby the base surface of the guide body  119  is attracted to the upper surface  126 . In addition, the clamping bolt  118  undergoes a slight lateral elastic deformation so that its head  118   a  bears against the bore wall of the opening  114  at a point opposite the clamping slide  132 . This spreads the clamping bolts in the openings  114  to  117  away from each other, causing the guide body  119  to find its desired position, i.e. its zero position. 
     The movement of the actuating rod is transmitted to the clamping slides  132  to  135  by the spring means  130 ,  131 . The wedge  136 , the spring means  130 ,  131  and the clamping slide form a reduction gear. In other words, the distance covered by each clamping slide  132  to  135  during clamping is at most as great as the distance covered by the actuating rod  125 , but preferably less. This is achieved by appropriate inclination of the clamping surfaces  128 ,  129  and by appropriate adjustment of the wedge angle between the end faces of the clamping slides  131 / 134 ,  133 / 135 , which rest against the respective spring means  120 ,  121 . 
     The through opening of the clamping plate  112  has an internal thread  139 ,  140  on each side. An abutment  141  is fixed in the internal thread  139 , for example in the form of a screw, which is supported on the end face of the actuating rod  125  via a compression spring  142 . An actuating screw, which is screwed into the internal thread  140 , engages the other end face of the actuating rod  125 . By turning the actuating screw  143 , the axial position of the actuating rod  125  can be adjusted specifically in order to actuate the clamping slides  132  to  135  by means of the wedge  136  and via the spring means  130 ,  131 . 
     The clamping plate described in this respect works as follows: 
     To connect the workpiece clamping device  111  to the clamping plate  112 , the workpiece clamping device  112  is first placed on the clamping plate  112  in such a way that the clamping bolts  118  move into the openings  114 ,  115 ,  116 ,  117  and the guide body  119  (or a workpiece provided directly with pins  118 ) rests on the upper surface  126 . Initially, the clamping slides  132  to  135  are in the release position. To tighten the workpiece clamping device  111 , the screw  143  is now actuated in such a way that the wedge  136  forces the spring means  130 ,  131  apart, which in turn force the clamping slides  132  to  135  apart so that they move into the tightening position according to  FIG.  9    and tighten the clamping bolts  118 . The spring means  130 ,  131  compensate for any tolerances of the clamping bolts  118  and also of the clamping slides  132  to  135 , which are guided in their channels with little clearance. The spring means  130 ,  131  distribute the force emanating from the wedge  136  largely evenly over all the clamping slides  132  to  135 . This is further assisted if the wedge  136  is held with some lateral clearance on the actuating rod  125 . For this purpose, the actuating rod may have a reduced-diameter or flattened section over which the wedge  136  engages. For example, the wedge  136  may be U-shaped for this purpose to sit on the actuating rod  125  like a rider. 
     When the tightening device is tightened, the spring means  130 ,  131  move radially outwards with respect to the actuating rod  125 . The spring means  130 ,  131  thereby entrain the stop means  130 ′,  131 ′ in their interior in the same direction. As the actuating force increases, the spring means  130 ,  131  begin to deform slightly from their circular shape in the relaxed state. They can come into contact with the respective stop means  130 ′,  131 ′ at one or more points and can be supported there, so that no further deformation occurs. The spring means  130 ,  131  thus have a stroke limitation. The maximum spring travel is defined by the annular gap formed between the respective stop means  130 ′,  131 ′ and the spring means  130 ,  131 . The spring force of the spring means  130 ′,  131 ′ can depend non-linearly on the radial deformation. In particular, the spring characteristic can be progressive or digressive. 
     The embodiment example described above has a tightening device  124  for four openings  114 ,  115 ,  116 ,  117 . However, several such tightening devices  124 ,  124 ′ can also be provided in the clamping plate, as illustrated in the embodiments of  FIGS.  11  and  12   .  FIG.  11    essentially illustrates a clamping plate  123  with a duplication of the tightening devices and the corresponding openings  114  to  117  and  114 ′ to  117 ′. The above description applies accordingly to the formation of the associated tightening device  124 . It further applies accordingly to the tightening device  124 ′, which is actuated by the same actuating rod  125  extended here. The clamping plate  123  can be further enlarged by further doubling of the clamping system, which in turn can be lined up with one another as  FIG.  12    illustrates with the aid of the clamping plates  123 ′,  123 ″. The previous description applies accordingly to the tightening devices, each of which being associated with four clamping openings  114 ′,  115 ′,  116 ′,  117 ′. 
     The clamping plate  112  according to the invention has a tightening device  124  for tightening clamping bolts  118 . The clamping plate  112  has a plurality of clamping openings  114 ,  115 ,  116 ,  117 , with which a tightening device  124  is associated for clamping bolts seated in the openings  114  to  117 . The tightening device  124  comprises clamping slides  132  to  135 , which are movable radially to the respective openings  114  to  117  with little clearance in corresponding channels of the clamping plate  112 . A movably arranged wedge  136 , which acts on the clamping slides  132  to  135  via slightly resilient rollers, rings or other resiliently formed bodies, serves to move the clamping slides  132  to  135 . A stop means  130 ′,  131 ′, for example in the form of a bolt, which passes through the spring means  130 ,  131 , serves to limit the deformation of the corresponding spring means  130  to  131 . The bolt is preferably oriented at right angles to the upper surface  126  serving as a support surface. A gap formed between the spring means and the stop means limits the spring stroke of the spring means. This allows the spring means to compensate for existing manufacturing tolerances or other tolerances in the tightening device or on the clamping bolts on the one hand and to transmit the required clamping forces on the other. 
     LIST OF REFERENCE SIGNS 
     
         
           10  workpiece holding device 
           11  clamping device 
           12  support body 
           13  holding side 
           14  attachment side 
           15  holding device 
           16  Workpiece 
           17  clamping jaw 
           18  clamping bolt 
           19  conical end section 
           20  receptacle hole 
           21  face cavity 
           22  impingement surface 
           23  conical section 
           24  tapering section 
           28  base body 
           29  clamping side 
           30  abutment surface 
           31  counter abutment surface 
           32  hole bottom 
           33  elastically deformable element 
           36  clamping body 
           36   a  first clamping body 
           36   b  second clamping body 
           36   c  third clamping body 
           36   d  fourth clamping body 
           37  guide channel 
           38  channel wall 
           39  channel bottom 
           40  Cover 
           41  cover holding cavity 
           42  guide wall section 
           43  guide insert 
           50  first clamping body group 
           51  second clamping body group 
           52  operating device 
           53  clamping end 
           54  clamping surface 
           57  operating screw 
           58  Nut 
           59  main body 
           60  main body surface 
           61  operating body end surface 
           62  operating body 
           63  Slant 
           64  operating end 
           65  clamping body end surface 
           70  biasing arrangement 
           71  biasing element 
         A axial direction 
         F release position 
         FZ traction force 
         FL longitudinal force 
         FX first force component 
         FY second force component 
         G 1  first straight line 
         G 2  second straight line 
         L 1  first longitudinal axis 
         L 2  second longitudinal axis 
         L 3  third longitudinal axis 
         L 4  fourth longitudinal axis 
         P 1  first intersection point 
         P 2  second intersection point 
         P 3  third intersection point 
         P 4  fourth intersection point 
         S clamping position 
         x first direction 
         y second direction 
         z third direction
         110  Device     111  Workpiece clamping device     112 ,  113  Clamping plates     114 - 117  Openings     118  Clamping bolt     119  Guide body     120 ,  121  Clamping jaws     123  Clamping plate     124  Tightening device     125  Actuating rod     126  Upper surface     127  Through opening     128 ,  129  Inclined surfaces     130 ,  131  Spring means     130 ′,  131 ′ Stop means     132 - 135  Clamping slides     136  Wedge     137 ,  138  Spring means     139 ,  140  Internal thread/anchoring structure     141  Abutment     142  Compression spring     143  Actuating screw