Method for clamping workpieces, embossing device and clamping device

Abstract

The inventive method for clamping workpieces (10) comprises a step for preparing the workpiece (10) by plastically forming a defined grid (R) with a grid row (22) having at least two recesses (23) and a contact surface (25) spaced apart from the grid row (22), and a step for clamping the workpiece, whereby a positive-locking / friction-locking connection is created between a clamping jaw and the workpiece. The pre-formed contact surface (25) serves as the clamping surface during clamping. The shape of the grid (R), in particular the contact surface (25), remains, at least substantially, undeformed during the clamping process. The invention also includes a corresponding embossing device (11) and a corresponding clamping device.

Description

[0001] The invention relates to a method for clamping workpieces, an embossing device for forming a grid and a clamping device for clamping the workpiece.

[0002] To machine workpieces in machine tools specifically designed for machining workpieces, the workpieces must be firmly clamped and held in suitable clamping positions. To achieve the most precise and reproducible machining results possible, it is desirable that the workpiece's clamping position can be reliably maintained in a specified clamping position, even after repeated clamping.

[0003] WO 99 / 52678 describes a clamping device for workpieces comprising a clamping element with a contact surface and a plurality of projections regularly arranged thereon. The projections can be brought into positive engagement with recesses formed in the surface of the workpiece. The recesses in the surface of the workpiece can be produced, for example, using a stamping process. The projections merge directly into the contact surface, so that when material accumulations are created around the edges of the recesses by the stamping process, the contact surfaces rest on the material accumulations and deform them during the clamping process. During the clamping process, the material accumulation can thus be deformed again, so that the clamping position can change slightly during the clamping process.

[0004] DE 10 2019 132276 describes a method for clamping workpieces, in which depressions are made in the workpiece before clamping using a plurality of stamping teeth in a grid, which serve as positioning and coupling elements when the workpiece is clamped in a corresponding clamping device. During the stamping process, a distance to the workpiece surface is left between the adjacent stamping teeth so that a raised deformation of the workpiece surface is possible between two adjacent depressions. Only when the workpiece is subsequently clamped are the raised deformations brought into a flat shape. The final clamping position is therefore only determined during clamping. However, due to the deformation of the workpiece surface after stamping, i.e. during clamping, the accuracy of the actual clamping position of the workpiece can deviate from the previously intended clamping position.In addition, the clamping position may continue to change after repeating several clamping operations, since further deformation of the workpiece surface cannot be ruled out, particularly when clamping with different clamping forces.

[0005] Based on this, it is the object of the invention to provide a clamping method with which the most accurate and reproducible positioning of the workpiece when clamping in the clamping device is possible.

[0006] The method according to the invention for clamping workpieces comprises a first step in which the workpiece is prepared by plastically forming a defined grid into the workpiece surface by means of an embossing device with at least one embossing jaw, comprising a grid row having at least two recesses and a contact surface spaced from the grid row. The embossing device has an embossing jaw with an embossed structure having at least one embossed row and at least one stop element spaced from the embossed row. The height of the stop element determines the depth of the recesses achievable during the embossing process relative to the contact surface. The stop element can be designed, for example, as at least one stop tooth, as a row of stop teeth, or as a stop rib.

[0007] The method according to the invention also comprises a second step in which the workpiece is clamped by means of a clamping device having at least one clamping jaw with a clamping structure adapted to the grid. During the clamping process, a positive / frictional connection is created between the clamping jaw and the workpiece, whereby the shape of the grid remains at least substantially undeformed.

[0008] The clamping position of the workpiece during embossing of the grid is determined longitudinally and transversely by the positioning of the recesses, and also in the depth direction by the depth of the recesses, which is clearly defined by the stop element. The embossing jaw can have a recess between the embossing row and the spaced stop element, so that deformations that may occur during the embossing process at the edges of the recesses between the recesses and the contact surface can be accommodated in the distance between the embossing row and the stop element.

[0009] A special feature of the clamping method according to the invention is that the clamping structure is adapted to the grid in such a way that the grid does not deform further after the preparation of the workpiece during clamping, which enables repeated clamping of the workpiece without the clamping position changing in the longitudinal, transverse and / or depth direction.

[0010] For this purpose, the clamping structure can comprise a positioning row with at least two positioning elements (retaining teeth) adapted to the recesses of the grid, as well as a clamping element spaced apart from the positioning row, which rests (exclusively) against the contact surface during the clamping process. A recess is preferably provided between the positioning row and the clamping element.

[0011] The stop element means that the stamping jaw does not need to be actuated with a specific force (force-controlled) during the stamping process to achieve the desired depth for the indentations. The depth of the indentations is determined in advance by the height of the stop element, regardless of the force applied during the stamping process. Particularly on workpieces with high material ductility, this allows the indentations to be stamped to a precise depth, even if the force applied during the stamping process is too high, for example, for the material used. This can save time when setting the parameters of the stamping device, especially when stamping workpieces with different material ductilities.

[0012] In particular, the clamping structure comprises at least one positioning row comprising at least two positioning elements and a clamping element spaced apart from the positioning row. During the clamping process, the positioning elements are brought into positive engagement with the recesses, and the clamping elements are brought into frictional engagement with the contact surface, without the grid being deformed during the clamping process. The workpiece surface remains at least substantially undeformed, particularly during clamping of the workpiece. It is preferred that all deformations of the workpiece surface occur during the embossing of the recesses, thereby improving the positioning and reproducibility of the clamping positioning of the workpiece.

[0013] Preferably, the height of the stop element limits the depth of the recesses that can be achieved when embossing the grid. The depth of the embossed recesses can thus be mechanically determined, essentially independent of the force applied during the embossing process.

[0014] The embossing device according to the invention serves to carry out the method described above, in particular to carry out the embossing step of the method described above.

[0015] The embossing device has at least one embossing jaw for forming a defined grid with a grid row comprising at least two recesses and a contact surface spaced from the grid row. The embossing jaw has an embossed structure with a base surface from which protrudes at least one embossing row and at least one stop element spaced from the embossing row. The height of the stop element determines the depth of the recesses achievable during the embossing process. Preferably, the height of the stop element above the base surface is less than that of the embossing row.

[0016] The stamping jaw can be a linearly movable stamp, a roller stamp, or the like. The stamping row preferably has at least two stamping teeth.

[0017] A recess is preferably provided between the embossing area and the stop element, into which the material can flow during the embossing process. This is particularly advantageous for materials with high ductility.

[0018] The embossing row and the stop element of the embossing jaw are particularly monolithic.

[0019] The embossing device, in particular, has an abutment for receiving the workpiece, wherein the abutment is arranged opposite the embossing jaw. During the embossing process, the workpiece can thus be arranged between the embossing jaws and the abutment. The abutment can itself be designed as an embossing jaw, so that the desired recesses can be applied to the workpiece on two opposite, mutually facing sides in a single operation. In particular, the abutment also has an embossed structure that is mirror-symmetrical to the embossed structure of the embossing jaw.

[0020] For stamping, the stamping jaw(s) is / are pressed against the workpiece, preferably by means of a force-generating device. The force-generating device is preferably configured to apply a force to the stamping jaw(s) on the workpiece. The force of the force-generating device is preferably dimensioned such that stamping of the workpiece is possible, whereby the force-generating device does not need to be actuated in a force-controlled manner. In this process, the stamping depth is not determined by the ductility of the workpiece material, but solely by the stop element.

[0021] The force generating device is preferably arranged between the embossing jaw and the abutment, wherein the embossing jaws and the abutment are movable towards and away from each other to form the recesses.

[0022] It is preferred that the embossing teeth have at least one tooth flank that is concavely curved, whereby a better penetration behavior of the embossing teeth into the surface of the workpiece can be achieved.

[0023] The embossing jaw, in particular, has a plurality of longitudinal edge regions, wherein an embossed structure is formed on at least one of the longitudinal edge regions. An embossed structure can also be formed on at least two or three, preferably on all, longitudinal edge regions of the embossing jaw. It is preferred that the embossed structure is formed on all longitudinal edge regions of the embossing jaw such that the embossing jaw can be turned three times. The embossing jaw can, for example, be turned about the longitudinal axis (the x-axis) and / or the transverse axis (the y-axis) and / or the depth axis (z-axis) of the embossing jaw. This makes it possible to turn the embossing jaw when the first embossed structure becomes worn and to continue using it until all embossed structures on the longitudinal edges are worn away.

[0024] In particular, a (flat) stop surface is formed at an upper end area of ​​the stop element, which determines the penetration depth of the embossing teeth into the workpiece surface. The flat design of the stop surfaces allows the force acting on the embossing jaws during embossing to be distributed evenly across the surface of the workpiece, so that the stop element rests (flat) against the workpiece surface when the maximum penetration depth of the embossing teeth is reached, and the stop element prevents the embossing teeth from penetrating further into the workpiece surface.

[0025] The stop surface of the stop teeth is preferably smaller than the cross-sectional area of ​​the embossing teeth at the level of the stop surface. If the embossing structure has a first and a second stop row, the combined stop surface of the stop elements of the two stop rows can be larger than the cross-sectional area of ​​the respective embossing teeth arranged between the stop rows at the level of the stop surface.

[0026] Preferably, the embossing teeth of the embossing row are arranged equidistant from one another along a longitudinal axis so that a uniform penetration behavior of the embossing teeth can be achieved.

[0027] It is preferred that the embossing structure has a first stop row consisting of at least two stop elements, spaced apart from the embossing row. Preferably, the embossing structure also has a second stop row consisting of at least two stop elements, likewise spaced apart from the embossing structure. The applied embossing force can thereby be better distributed during the embossing process if the stop elements bear against the contact surfaces of the workpiece surface. The stop elements of the first and / or second stop row are preferably arranged equidistant from one another and in the same grid as the embossing teeth. Thus, at least two stop elements can be assigned to each embossing tooth, with the embossing tooth being arranged between the two stop elements. This makes it possible to form the recess with the embossing tooth as orthogonally as possible to the embossing plane defined by the embossing jaw.

[0028] The first and / or second stop rows are arranged, in particular, at least substantially parallel to the embossing row and spaced apart from it. It is preferred that a recess be provided between each stop row and the embossing row, defining an area in which deformations can be targeted during the embossing process.

[0029] Embossing teeth and stop elements can be arranged alternately in the embossing row. This is particularly advantageous when the ductility of the different materials varies greatly, since increasing the number of stop elements increases the stop surface relative to the cross-sectional area of ​​the embossing teeth. This prevents the embossing teeth from penetrating too deeply into the surface of the workpiece, even with relatively high ductility. Alternatively, the embossing row can consist exclusively of embossing teeth.

[0030] The clamping device according to the invention for clamping a workpiece, in the surface of which a grid is formed by means of the embossing device of the above type, said grid comprising a grid row with at least two recesses and a contact surface spaced from the grid row, comprises at least one clamping jaw with a clamping structure adapted to the grid. The clamping device is designed to create a positive / frictional connection between the clamping jaw (29) and the workpiece (10) during the clamping process, wherein the shape of the grid (R) remains at least substantially undeformed.

[0031] The clamping structure preferably has at least two retaining teeth as positioning elements, which are designed such that they retract into the recesses during the clamping process. In particular, the clamping structure also has at least one clamping element that rests against the contact surface of the grid during the clamping process (without deforming it).

[0032] The clamping structure preferably also has a first and / or a second row of at least two clamping elements. The clamping structure is in particular adapted to the embossed structure; preferably, the clamping structure and the embossed structure are at least substantially identical. In this form, the stop surfaces of the stop elements serve as clamping surfaces of the clamping elements, with which the clamping jaw can be frictionally connected to the contact surfaces of the workpiece surface. Furthermore, the contact surface(s) with the associated clamping elements serve to position the workpiece in the depth direction (z-axis). The holding teeth serve to be positively connected to the recesses in the workpiece surface in order to position the workpiece in the longitudinal (x-axis) and transverse directions (y-axis).

[0033] Further details and advantages of the clamping method according to the invention can be found in the drawings, the description, and the dependent claims. They show: Fig. 1 a prepared workpiece after forming the grid in an embossing device according to the invention; Fig. 2 a embossing jaw belonging to an embossing device in perspective view; Fig. 3 a perspective section of the grid in the workpiece surface; Fig. 4 an example of an embossed structure during the embossing process with the workpiece in a schematic cross-sectional view; Fig. 5 an embossed structure during the embossing process during penetration into the workpiece in a schematic longitudinal section; Fig. 6 another example of an embossed structure during the embossing process during penetration into the workpiece in a schematic longitudinal section; Fig. 7 a plan view of the Fig. 5 Embossed structure shown in longitudinal section; Fig. 8 a plan view of the Fig. 4 embossed structure shown in longitudinal section; and Fig. 9 a relationship between penetration depth and applied force as a diagram.

[0034] Fig. 1 schematically shows a workpiece 10 in an embossing device 11 after the embossing process, the grid R. The embossing device 11 has an embossing jaw 12 with an embossed structure 13.

[0035] On an opposite side of the embossing jaw 12 is Fig. 1 an abutment 14 is arranged. The abutment 14 has in the Fig. 1 also has an embossed structure 13, so that during the embossing process, the workpiece 10 can imprint a predefined grid R on two opposite sides. Other abutments, such as clamping jaws with smooth clamping surfaces, are also possible.

[0036] The Fig. The embossing jaw 12 shown in Figure 1 has a base body 15 which is at least substantially cuboid-shaped. The base body 15 has four longitudinal edge regions 16, wherein Fig. 1 only two of the four longitudinal edge regions 16 are shown. The embossed structures 13 are formed in the longitudinal edge regions 16 of the base body 15.

[0037] In addition, Fig. 1 depicts a Cartesian coordinate system with x-, y-, and z-axes, which is defined by the embossing jaw 13. The x-axis corresponds to the longitudinal direction, the y-axis to the transverse direction, and the z-axis to the depth direction of the embossing jaw.

[0038] The design of the embossing structure 13 is described in detail below. The following description of the embossing jaw 12 applies to the present and all other embodiments for the abutment 14 designed as an embossing jaw or other embossing jaws and abutments accordingly.

[0039] In Fig. 2 shows the embossing jaw 12. The embossing jaw 12 has a base body 15 that extends along the longitudinal direction, which defines the x-axis. At the longitudinal edge areas 16, Fig. 2, the embossed structure 13 is formed. The embossed structure 13 can also be arranged only in one longitudinal edge region 16 of the base body 14.

[0040] However, it is preferred that the embossed structure 13 be provided on all longitudinal edge regions 16 of the embossing jaw 12, whereby the embossing jaw 12 can be used four times by turning it three times. If the embossed structure 13 becomes worn, for example due to wear, the embossing jaw 12 can be turned over and reused. This increases the service life of the embossing jaw 12.

[0041] The Fig. The embossing structure 13 shown in Figure 2 has an embossing row 17 with a plurality of embossing teeth 18, a first (lower) stop row 19 with a plurality of stop elements 20, and a second (upper) stop row 21 with a plurality of stop elements 20. The stop elements 20 are designed as individual stop teeth, each extending along a row. The embossing row 17 and the first and second stop rows 19, 21 extend along a longitudinal direction (x-axis) of the embossing jaw 12 and are arranged at a distance from one another.

[0042] In Fig. 2, the first and second stop rows 19, 21 have a plurality of individual stop teeth 20. Alternatively, it is also possible for the first and / or second stop row 19, 21 to have only one stop element 20 in the form of a stop rib 20, which extends longitudinally parallel to the embossed row 17 and is spaced apart from it.

[0043] During the stamping process, the stamping tooth 18 penetrates the workpiece surface 33, whereby the material of the workpiece 10 evades the stamping tooth 18 and deforms. An influenced zone 29 is formed, in which the material of the workpiece 10 is compacted and may also be hardened by deformation. In addition, a non-planar deformation 24 of the workpiece surface 33 may form around the created depression 23, for example in the form of a wall-like bulge or elevation or in another slight elevation of the workpiece surface opposite to the direction of penetration of the stamping tooth 18. This is Fig. 3-6 exaggeratedly illustrated.

[0044] Fig. Figure 3 illustrates a section of the grid R in the workpiece surface 33 of the workpiece 10 after the embossing process. A grid R with a grid row 22 is formed in the workpiece surface 33, which extends along a grid axis L and contains at least two recesses 23.

[0045] In the edge areas of the recesses 23, deformations 24 are depicted that can occur during the stamping process. Fig. 3 exaggerated deformations 24 are elevations which are wall-like in the edge area of ​​the depressions 23.

[0046] The Fig. The grid R shown in Figure 3 also comprises a plurality of contact surfaces 25, which are arranged flanking the recesses 23 arranged in the grid row 22 and spaced apart from them. The grid row 22 with the recesses 23 is arranged between the flanking contact surfaces 25.

[0047] Fig. Figure 4 shows an example of the embossed structure 13 in cross section during the embossing process. The workpiece surface 33 is Fig. 3 described grid R is embossed. At the edge areas of the recesses 23, wall-shaped deformations 24 are depicted, which can occur depending on the ductility of the material of the workpiece.

[0048] In addition to the embossing tooth 18 of the embossing row 17, the embossing structure 13 has a stop element 20 each, which is designed as a row of stop teeth. The stop elements 20 are each spaced apart from the embossing tooth 18. The stop teeth 20 have a flat stop surface 27 in the upper end region 26, which rests flat against the contact surface 25 of the workpiece 10 when the desired depth T of the recess 23 is reached. The stop teeth 20 thus limit the depth T of the recesses 23.

[0049] Between the embossing tooth 18 and the stop teeth 20, recesses 28 are provided, which specifically define an area around the recesses in which deformations 24 of the workpiece surface 33 can occur without negatively affecting the positioning accuracy of the workpiece 10 during clamping. The contact surface 25 is at least substantially flat. The contact surfaces 25 are spaced from the recess 23 transversely to the grid axis L in such a way that any deformations 24 occurring in the edge region of the recesses 23 are located outside the contact surface 25. The flatness of the contact surface 25 is thus not affected by the deformations 24.

[0050] The recesses 23 have a defined depth T with respect to the contact surfaces 25. After stamping, the contact surfaces 25 serve as clamping surfaces for the clamping device without the deformation area 25 being deformed during clamping. This precisely defines the clamping position, particularly in the transverse direction to the clamping jaw, and the clamping result is reproducible.

[0051] Fig. Figure 5 shows an example of the embossed structure 13 in longitudinal section during the embossing process. Fig. The example of the embossed structure 13 shown in Figure 4 has an embossed row 17 with a plurality of embossed teeth 18 as well as a first stop row 19 and a second stop row 33, each with a plurality of stop teeth as stop elements 20.

[0052] Between the respective embossing teeth 18, recesses 28 are provided in the embossing structure 13, which define a defined area for the deformations 24 occurring in the edge area of ​​the depressions 23. In the Fig. In the example shown in Figure 5, recesses 28 are also provided between the individual stop teeth 20.

[0053] The surface area of ​​the stop surface 27 is at least smaller than the surface area of ​​the cross-sectional area of ​​the embossing tooth 19 at the level of the stop teeth 20. In the Fig. 4 and Fig. In the example shown in Figure 5, the surface area of ​​the stop surfaces 27 of the two stop elements 20 taken together is greater than the surface area of ​​the cross-sectional area of ​​the embossing tooth 19 at the level of the stop teeth 20.

[0054] Fig. Figure 6 shows another example of the embossed structure 13 in longitudinal section during the embossing process. Fig. 6, stop elements are designed as webs flanking the embossing row 17. Recesses 28 are also provided between the individual embossing teeth 18.

[0055] In Fig. 7 is a schematic plan view of the Fig. 6 is depicted. Between the embossed row 17 and the first and second stop rows 19, 20 with the web-shaped stop elements 20, the recesses 28 are provided in this example, which create space for any deformations 24 of the workpiece surface 33.

[0056] Fig. 8 shows a schematic plan view of the Fig. 5 shown example of the embossed structure 13. In the Fig. In the example shown in Figure 8, the first stop row 19 and the second stop row 21 each have individual stop elements 20 designed as stop teeth.

[0057] Fig.Figure 9 shows the force F to be applied versus the penetration depth z during the stamping process. The upper curve 30 represents the curve for a relatively hard material such as steel, while the lower curve 31 represents the force for a relatively soft material such as aluminum. The constant force 32 applied by the force application device during the stamping process, with which the stamping jaw 12 is pressed against the abutment 14, is shown schematically in the diagram in dashed lines.

[0058] In the first area A, the stop teeth do not yet touch the surface of the workpiece 10. The force applied by the stamping device is greater than the force F required for deformation.

[0059] At point B, the stop teeth then contact the surface of the workpiece 10. The force curves 30, 31 exhibit a sudden increase in the required force F at point B. From point B onwards, the force applied by the embossing device in area C is now smaller than the required force. The stop surfaces 27 of the stop elements 20 now rest against the contact surface 25 of the workpiece surface 33, and further penetration and thus deformation of the workpiece surface 33 is no longer possible with the force applied by the force application device. The stop elements 20 thus determine the maximum possible penetration depth T of the recesses 23 of the grid R.

[0060] The inventive method for clamping workpieces 10 comprises a step for preparing the workpiece 10 by plastically forming a defined grid R with a grid row 22, which has at least two recesses 23, and a contact surface 25, which is spaced from the grid row 22, and a step for clamping the workpiece, wherein a positive / frictional connection is created between a clamping jaw and the workpiece. The previously created contact surface 25 serves as a clamping surface during clamping. The shape of the grid R, in particular of the contact surface 25, remains at least substantially undeformed during the clamping process. The invention also comprises a corresponding embossing device 11 and a corresponding clamping device. Reference symbol: 10 Workpiece 11 Embossing device 12 embossing jaws (embossing stamps) 13 Embossed structure 14 Abutment (second stamping jaw) 15 basic bodies 16 Longitudinal edge area of ​​the base body 17 minting series 18 embossing teeth 19 first row of stops 20 Stop element (stop tooth) 21 second row of stops 22 grid row 23 recesses 24 (wall-like) deformations in the edge area 25 contact surface 26 (upper) end area 27 Stop surface 28 recesses 29 Zone 30 upper curve 31 lower curve 32 constant force 33 Workpiece surface F Force L Grid axis R Grid T Depth (penetration depth) x Longitudinal direction (x-axis) y transverse direction (y-axis) z Depth direction (z-axis) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 99 / 52678

[0003] DE 10 2019 132276

[0004]

Claims

[1] Method for clamping workpieces (10), comprising: - preparing the workpiece (10) by means of an embossing device (11) with at least one embossing jaw (12) with an embossed structure (13) which has at least one embossed row (17) and at least one stop element (20) spaced from the embossed row (17), by plastically forming a defined grid (R) with a grid row which has at least two recesses (23) and a contact surface (25) which is spaced from the grid row (22), wherein the height (26) of the stop element (20) determines the depth (T) of the recesses (23) achieved during the stamping process relative to the contact surface (25); and - clamping the workpiece (10) by means of a clamping device with at least one clamping jaw with a clamping structure adapted to the grid (R), wherein during the clamping process a positive / frictional connection is created between the clamping jaw and the workpiece (10), wherein the shape of the grid (R) remains at least substantially undeformed. [2] Method according to claim 1, characterized by that the clamping structure has at least one positioning row of at least two positioning elements and at least one clamping element spaced from the positioning row, wherein during the clamping process the positioning elements are brought into positive connection with the recesses (23) and the clamping elements are brought into frictional connection with the contact surface (25) without deforming the grid (R) during the clamping process. [3] Embossing device (11) with at least one embossing jaw (12) for plastically forming a defined grid (R) with a grid row (22) which has at least two recesses (23) and a contact surface (25) which is spaced from the grid row (22), wherein the embossing jaw (12) has an embossed structure (13) with a base surface from which at least one embossed row (17) and at least one stop element (20) arranged at a distance from the embossed row (17) protrude, wherein the height (26) of the stop element (20) determines the depth (T) of the recesses (23) achieved during the embossing process relative to the contact surface (25). [4] Embossing device (11) according to claim 3, characterized by that the embossing row (17) has at least two embossing teeth (18). [5] Embossing device (11) according to claim 3 or 4, characterized by that a recess (28) is arranged between the embossed row (17) and the stop element (20). [6] Embossing device (11) according to one of claims 3 to 5, characterized by that the embossing row (17) and the stop element (20) of the embossing jaw (12) are monolithic. [7] Embossing device (11) according to one of claims 3 to 6, characterized byan abutment (14) which is arranged on an opposite side of the embossing jaw (12) in such a way that the workpiece (10) can be arranged between the embossing jaws (12) and the abutment (14) during the embossing process, wherein the abutment (14) preferably also has an embossed structure (13). [8] Embossing device (11) according to one of claims 4 to 7, characterized by that the embossing teeth (18) have at least one tooth flank which is concavely curved. [9] Embossing device (11) according to one of claims 3 to 8, characterized by that the embossing jaw (12) has a plurality of longitudinal edge regions (16), wherein an embossed structure (13) is formed on at least one of the longitudinal edge regions (16). [10] Embossing device (11) according to one of claims 4 to 9, characterized bythat a preferably flat stop surface (27) is formed on an upper end region (26) of the stop element (20), which determines the depth (T) of the embossing teeth (18) into the workpiece surface (33). [11] Embossing device (11) according to one of claims 4 to 10, characterized by that the embossing teeth (18) of the embossing row are arranged equidistant from one another along a longitudinal axis. [12] Embossing device (11) according to one of claims 3 to 11, characterized by that the embossed structure (13) has a first stop row (19) spaced from the embossed row and consisting of at least two stop elements (20). [13] Embossing device (11) according to one of claims 3 to 12, characterized by that the embossed structure (13) has a second stop row (21) spaced from the embossed row and consisting of at least two stop elements (20). [14] Embossing device (11) according to claim 12 and / or 13, characterized bythat the first stop row (19) and / or the second stop row (21) are arranged at least substantially parallel to the embossed row (17) and spaced therefrom. [15] Embossing device (11) according to one of claims 4 to 14, characterized by that embossing teeth (18) and stop elements (20) are formed alternately in the embossing row (17). [16] Embossing device (11) according to one of claims 4 to 14, characterized by that only embossing teeth (18) are formed in the embossing row. [17] Clamping device for clamping a workpiece (10), in the surface of which a defined grid (R) is formed by means of the embossing device (11) according to one of claims 3 to 15, which has a grid row (22) with at least two recesses (23) and a contact surface (25) which is spaced from the grid row (22), wherein the clamping device has at least one clamping jaw with a clamping structure adapted to the grid (R), wherein the clamping device is designed to produce a positive / frictional connection between the clamping jaw and the workpiece (10) during the clamping process, wherein the shape of the grid (R) remains at least substantially undeformed.

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