C-SHAPED TOOL HOLDER, SETTING DEVICE WITH THE C-SHAPED TOOL HOLDER AND METHOD FOR SETTING AN OFFSET DIFFERENCE OF THE C-SHAPED TOOL HOLDER

Abstract

A C-shaped tool holder has a first leg and a second leg that is arranged opposite to the first leg, a connecting piece by which the first leg and second leg are connected with each other at a respective connecting end. An operating end of the first leg serves for fastening a punch in the direction of the operating end of the second leg, and an operating end of the second leg serves for fastening a die dome wherein an offset difference due to a gravity-caused offset between the operating ends of the first and second legs can be minimized by at least one compensating element which is arranged at one or more of the following elements: the first leg, the second leg or the connecting piece.

Claims

1. A C-shaped tool holder with a frame structure defining a frame plane comprising a) a first leg and a second leg that is arranged opposite to the first leg, each leg including a connecting end and an operating end, b) a connecting piece by means of which the first leg and the second leg are connected with each other at the respective connecting end, wherein c) the operating end of the first leg serves for fastening a punch with an associated drive unit defining a movement direction of the punch in the direction of the operating end of the second leg, and the operating end of the second leg serves for fastening a die dome wherein d) an offset difference due to a gravity-caused offset between the operating end of the first and the operating end of the second leg perpendicular to the frame plane can be minimized by at least one compensating element which is arranged at one or more of the following elements: the first leg, the second leg or the connecting piece, and e) an intersecting point of a first straight line corresponding to the movement direction of the punch in the direction of the operating end of the second leg, and a second straight line extending from the operating end of the second leg in the direction of the operating end of the first leg, is settable to an operating point by means of the at least one compensating element.

2. The C-shaped tool holder according to claim 1, wherein the at least one compensating element has in cross section a first axial geometrical moment of inertia and a second axial geometrical moment of inertia that is larger than the first axial geometrical moment of inertia, and the at least one compensating element is arranged so that the second axial geometrical moment of inertia acts perpendicularly to the frame plane.

3. The C-shaped tool holder according to claim 1, wherein the compensating element has a profile shape having one of the following shapes in cross section: rectangle, semi-circle, circular layer, triangle, T-shape, double-T-shape, L-shape, U-shape, trapezoid or a combination thereof.

4. The C-shaped tool holder according to claim 1, wherein the at least one compensating element includes at least two fastening points, preferably at least four, six, eight or ten fastening points and particularly preferred a plurality of fastening points.

5. The C-shaped tool holder according to claim 1, wherein the compensating element has the shape of a hollow profile or bowl profile and furthermore, two slot nuts are present between the compensating element and the first leg, the second leg or the connecting piece.

6. The C-shaped tool holder according to claim 1, wherein the compensating element is releasably fastened to the corresponding one of the legs or the connecting piece.

7. The C-shaped tool holder according to claim 1 comprising two compensating elements.

8. The C-shaped tool holder according to claim 1 comprising a framework like frame structure.

9. The C-shaped tool holder according to claim 1 comprising at the operating end of the first leg a punch with an associated drive unit and at the operating end of the second leg a die dome.

10. A setting device with a C-shaped tool holder according to claim 1, wherein at the operating end of the first leg, a punch with an associated drive unit and at the operating end of the second leg, a die dome is fastened.

11. The setting device according to claim 10, wherein the setting device is fastened to a multi-axle robot by means of the C-shaped tool holder.

12. A method for setting an offset difference between a first and a second leg of a C-shaped tool holder according to claim 1, comprising the steps: a. arranging the C-shaped tool holder in a way that a frame plane is aligned perpendicular to gravity, after that, b. determining a first offset of the first leg with respect to the frame plane and c. determining a second offset of the second leg with respect to the frame plane, after that, d. fastening at least one compensating element to one or more of the following: the first leg, the second leg or the connecting piece, and e. minimizing an offset difference between the operating end of the first and the operating end of the second leg.

13. The method according to claim 12, with the further step: f. setting an intersecting point of a first straight line, which corresponds to a direction of movement of the punch in the direction of the operating end of the second leg, and of a second straight line, which extends from the operating end of the second leg in the direction of the operating end of the first leg, by means of the at least one compensating element to an operating point.

14. The method according to claim 12, wherein in cross section, the at least one compensating element comprises a first axial geometrical moment of inertia and a second axial geometrical moment of inertia that is bigger than the first axial geometrical moment of inertia, and the step of fastening takes place such that the compensating element is arranged in a way that the second axial geometrical moment of inertia acts perpendicularly to the frame plane.

15. The method according to claim 12, wherein the at least one compensating element is fastened via at least two fastening points to the first leg, the second leg or the connecting piece.

16. The method according to claim 12, wherein the at least one compensating element is releasably fastened to the first leg, the second leg or the connecting piece.

17. The method according to claim 12, wherein the at least one compensating element has the shape of a hollow profile or a bowl profile and at least two slot nuts are present between the compensating element and the first leg, the second leg or the connecting piece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the following, the present disclosure will be described in detail based on the drawings. In the drawings, the same reference signs denote the same components and/or elements. They show:

[0044] FIGS. 1A, 1B, 1C and 1D schematic views of different binding possibilities of a C-shaped tool holder to a multi-axle robot,

[0045] FIG. 2 a schematic view of a special solution for binding a C-shaped tool holder to a multi-axle robot,

[0046] FIG. 3 an illustration for clarifying the gravity-caused deformation of a C-shaped tool holder,

[0047] FIG. 4 a schematic view for clarifying the gravity-caused offset in case of a horizontal position of the C-shaped tool holder,

[0048] FIG. 5 a schematic view for clarifying the angular offset in case of a horizontal position of the C-shaped tool holder,

[0049] FIG. 6 a schematic view of a first embodiment of a C-shaped tool holder when using a central binding as well as with a compensating element arranged to the first leg,

[0050] FIG. 7 a view of the upper portion of the C-shaped tool holder according to FIG. 4 with alternative fastening points of the at least one compensating element,

[0051] FIG. 8 a perspective view of the at least one compensating element,

[0052] FIG. 9 shapes of profiles for the at least one compensating element in cross section,

[0053] FIG. 10 the C-shaped tool holder according to FIG. 6 in an exploded view,

[0054] FIG. 11 a view of the upper portion of the C-shaped tool holder according to FIG. 6 with further alternative fastening points of the at least one compensating element,

[0055] FIG. 12 a sectional view along the line A-A of FIG. 11,

[0056] FIG. 13 a schematic view of a second embodiment of the C-shaped tool holder when using the upper binding as well as with a compensating element arranged at the connecting piece and at the first leg, and

[0057] FIG. 14 a schematic flow chart of an embodiment of a method for setting the offset difference.

DETAILED DESCRIPTION

[0058] In the following and with respect to FIGS. 1a, 1b, 1c and 1d, firstly, a section of a C-shaped tool holder 1 is shown in order to clarify the possible binding positions to a multi-axle robot. The C-shaped tool holder 1 has a framework-like frame structure 10. Furthermore, the C-shaped tool holder 1 comprises a first leg 20 and a second leg 30 arranged opposite to the first leg 20. The first leg 20 comprises an operating end 22 and a connecting end. In the same way, the second leg 30 comprises an operating end 32 and a connecting end. The first 20 and the second leg 30 are connected with each other at the connecting ends by means of a connecting piece 40. In the illustrations shown in FIGS. 1a-1d, the section comprises the connecting piece 40 as well as the portion of the first leg 20 with the connecting end.

[0059] For the better understanding of the further explanations, a vertical tool position is assumed, as is indicated in FIGS. 1a-1d. In this vertical tool position, the frame plane R extends parallel to gravity. In other words, a first straight line G.sub.1, which corresponds to a direction of movement of a punch in the direction of the operating end of the second leg 30, and the second straight line G.sub.2 are congruent. The first G.sub.1 and the second straight line G.sub.2 therefore exemplary extend along a first axis, namely the x-axis of a Cartesian coordinate system. The y-axis extends parallel to the first 20 and the second leg 30. The x and the y-axis therefore constitute the frame plane R which is defined by the frame structure 10 (also compare FIGS. 4 and 5).

[0060] As can be seen in FIGS. 1a-1d, the C-shaped tool holder 1 comprises a central fastening portion 12 in the portion of the connecting piece as well as an upper fastening portion 14 in the portion of the first leg 20. The upper fastening portion 14 in the portion of the first leg 20 may be aligned in a way that it includes an angle of 450 with the x-axis and therefore also with the y-axis. In use, a binding unit 3 for binding with the multi-axle robot is mounted to one of the fastening portions 12, 14.

[0061] From left to right, figure T a show a centrally mounted binding unit 3, whose binding surface to the multi-axle robot extends parallel to the x-axis as well as parallel to the z-axis of the Cartesian coordinate system. In the further three illustrations of FIGS. 1b-1d, the binding unit 3 is mounted at the upper fastening portion 14, with each binding surface being aligned differently. That means that the binding surface, as shown in FIG. 1a, can firstly extend parallel to the x and the z-axis. Alternatively, the binding surface can extend parallel to the y and to the z-axis. This is shown in FIG. 1c. In other words, and with respect to these two alignments of the binding surface, there is an angle of 45 between the upper fastening portion 14 and the binding surface. Finally, and with respect to FIG. 1d, the binding surface, just as the upper fastening portion 14, can enclose an angle of 45 both with the x as well as with the y-axis and can extend parallel to the z-axis.

[0062] FIG. 2 shows a special solution of a binding unit 3. Here, the binding does not only take place at the outer part of the C-shaped tool holder 1 but extends in the portion of the connecting piece 40 over the width of the C-shaped tool holder 1.

[0063] Now, with respect to FIGS. 3-5, the behavior of a C-shaped tool holder 1 when being used in a horizontal alignment is first of all explained in order to demonstrate the underlying problem.

[0064] For this purpose, the upper view of FIG. 3 schematically shows the C-shaped tool holder 1 with the punch with drive unit 24 at the first leg 20 and the die dome 34 at the second leg 30. In this example, the binding to the multi-axle robot takes place centrally at the C-shaped tool holder 1.

[0065] Due to the weight, which may be of the punch 24, with drive unit as well as of the die dome 34, same bend down with respect to FIG. 3, which is highlighted by means of the corresponding arrows. Likewise, for clarification, the resulting first G.sub.1 and second straight line G.sub.2 were drawn-in for showing the deformed state. As can be seen, the first straight line G.sub.1 corresponds to the movement direction of the punch 24 in the direction of the die dome 34. The second straight line G.sub.2 extends from the operating end of the second leg 30 in the direction of the operating end 22 of the first leg 20. For reasons of simplicity, it was assumed in FIG. 3 that the second straight line G.sub.2 continues to extend parallel to the x-axis of the reference system, i.e. of the Cartesian coordinate system mentioned at the beginning.

[0066] The portion of permitted eccentricity is shown above and below the die dome 34 by means of the drawn-in lines. The intersecting point of the first straight line with this permitted portion provides an overview of the theoretically possible combinations of C-shaped tool holder 1 and size of the die dome 34 with the same punch 24 with drive unit.

[0067] The underlying aspects of this deformation/Underlying aspects caused by bending are now discussed with respect to the schematic FIGS. 4 and 5.

[0068] Both figures schematically show the C-shaped tool holder 1 where the binding unit 3 is bound centrally to the connecting piece 40. For orientation, the Cartesian coordinate system with x, y and z-axis is drawn in which is used in the application as the reference system.

[0069] The frame plane R which is defined by the frame structure 10 thus lies in the x, y-level, as shown at the beginning. Due to the horizontal arrangement of the C-shaped tool holder 1, the frame plane R therefore extends parallel to the ground.

[0070] The punch 24 with drive unit is provided at the operating end 22 of the first leg 20. It is marked as first mass m.sub.1. The die dome 34 is provided at the operating end 32 of the second leg 30. It is marked as second mass m.sub.2. The first mass m.sub.1 is bigger than the mass m.sub.2, so that the resulting first force F.sub.1 at the operating end 22 of the first leg 20 is larger than the resulting second force F.sub.2 at the operating end 32 of the second leg 30. This is illustrated both with the arrows at the forces F.sub.1, F.sub.2 as well as by the dimensioning of the boxes symbolizing the masses.

[0071] The distance to the binding unit 3 is relevant for the behavior of each leg 20, 30 at the operating end 22, 32, as the binding unit 3 depicts the fastening point. Schematically, each leg 20, 30 therefore turns into a first cantilever parallel to the x-axis and a second cantilever parallel to the y-axis. Thus, the first leg 20 comprises the cantilever a.sub.x in the x-direction or parallel to the x-axis, respectively, and the cantilever a.sub.y in the y-direction or parallel to the y-axis, respectively. In the same way, the second leg 30 comprises the cantilever b.sub.x in x-direction or parallel to the x-axis, respectively, and the cantilever b.sub.y in y-direction or parallel to the y-axis, respectively.

[0072] FIG. 4 serves for showing a first problem in case of a horizontal arrangement of the C-shaped tool holder 1, that is a possible difference regarding the offset of the operating ends 22, 32 perpendicular to the frame plane R, i.e. parallel to the z-axis. For this offset, the cantilever in y-direction, i.e. a.sub.y and by is relevant. As in the illustrated example, the cantilevers a.sub.y and b.sub.y are the same, the different masses m.sub.1 and m.sub.2 and thus the differently sized acting first F.sub.1 and second forces F.sub.2 cause an offset difference .sub.z in z-direction or parallel to the z-axis, respectively, between the first leg 20 and the second leg 30. Thus, the first straight line G.sub.1 and the second straight line G.sub.2 are no longer aligned concentrically or centrically with each other. Rather, an eccentricity is present.

[0073] A corresponding deflection w can generally be calculated with the formula (1):

[00003]$w=\frac{F{l}^3}{3\mathrm{EI}}$

with F being the force, 1 being the length of the cantilever, E being the elasticity module and I being the geometrical moment of inertia of the leg cross section.

[0074] The second problem is made clear in FIG. 5, because apart from the offset difference .sub.z, an angular offset p occurs at the same time. This angular offset results from the cantilever a.sub.x of the first leg 20 in x-direction and the cantilever b.sub.x of the second leg 30 in x-direction. The corresponding angles of the first 20 and the second leg 30 are marked with Pa and .sub.b. The angular offset P.sub.a of the first leg 20 and the angular offset P.sub.b of the second leg 30 cause the first straight line G.sub.1 and the second straight line G.sub.2 to meet at the intersecting point S, which, however, does not have to be the same as the operating point of the setting device. A deflection between intersecting point S and operating point does, however, lead to an eccentricity that has to be compensated.

[0075] Beside the deflection of the legs 20, 30, an inclination can therefore be observed at the same time, which results in an angular offset. The inclination can generally be calculated with the formula (2)

[00004]$=\frac{F{l}^2}{2\mathrm{EI}}$

with F being the force, 1 being the length of the cantilever, E being the elasticity module and I being the geometrical moment of inertia of the leg cross section.

[0076] Therefore, both the offset difference .sub.z should be minimized as well as the angular offset should be considered in order to realize an optimal working. Furthermore, the intersecting point S of the first straight line G.sub.1 and the second straight line G.sub.2 are set in a way that the two straight lines meet at the operating point, i.e. the intersecting point S corresponds to the operating point.

[0077] The deflections of the first 20 and of the second leg 30 are adjusted so that the offset or the offset difference .sub.z, respectively, is the same or at least close to 0. Consequently, the requirement that the deflection of the first leg 20 and the deflection of the second leg 30 is approximately the same is fulfilled as far as possible.

[0078] The deflection of the first leg 20, that is marked with w.sub.a in the following, and the deflection of the second leg 30, that is marked with w.sub.b in the following, are each constituted of a component in x-direction and a component in y-direction, equivalent to the cantilevers. This results in formula (3) due to the application of the superposition:

[00005]$w_a=\frac{F_1{a}_y^3}{3{\mathrm{EI}}_a}+\frac{F_1{a}_x^3}{3{\mathrm{EI}}_a}\frac{F_2{b}_y^3}{3{\mathrm{EI}}_b}+\frac{F_2{b}_x^3}{3{\mathrm{EI}}_b}=w_b.$

[0079] The inclination of the first and the second leg 20, 30 with respect to the x-direction causes, as explained above, the first straight line G.sub.1 and the second straight line G.sub.2 to meet at the intersecting point S. The angular offset is negligibly small regarding the deflections, it is, however, important for the intersecting point S.

[0080] In order to solve this, FIG. 6 shows a first embodiment of a C-shaped tool holder 1. It comprises two compensating elements 50 which are releasably arranged by means of pins 54 at opposite sides of the first leg 20. For the fastening of the compensating elements 50 to the C-shaped tool holder 1 or the corresponding frame structure 10, respectively, all releasable kinds of connections which can be produced with hand-held tools are suitable. These may include screwing, pinning, clamping and clipping. For the sake of completeness, it is pointed out that the compensating element 50 does not necessarily have to extend in a straight manner but may also extend in a bent way, arc-shaped or curved manner.

[0081] In the illustrated example, the compensating element 50 consists of a U-shaped profile having ten openings 52. Two openings 52 are provided directly next to one another at a first axial end while the remaining eight openings 52 are provided at a distance to that and starting at the second axial end. Even if in the present example, two openings 52 are arranged next to one another at the first axial end, the use of one opening 52 each is sufficient for realizing the function. The frame structure 10 of the C-shaped tool holder 1 comprises corresponding openings 16. This is for example shown in FIG. 10.

[0082] The geometrical moments of inertia of the first 20 and the second leg 30 are normally not constant over the length of the first 20 and the second leg 30. By using the compensating element 50, the respective geometrical moment of inertia is, however, increased and the deflection is reduced by that until the first G.sub.1 and the second straight line G.sub.2 meet at the operating point so that the operating point and the intersecting point S coincide.

[0083] In FIG. 6, the pins 54 in the two openings 52 are arranged at the first axial end of the compensating element 50 as well as in the second to last pair from the row of eight openings 52, starting at the second axial end of the compensating element 50. Compared to that, the pins 54 in FIG. 7 are arranged in the last pair from the row of eight openings 52. In this regard, it is additionally emphasized that the use of two directly neighboring pins also reduces the danger of a bending up of the C-shaped tool holder 1 by process-caused acting forces during operation.

[0084] Beside the shape of the compensating element, the effect of the compensating element 50 is influenced by the position of the pins 54. This is explained with respect to FIG. 8.

[0085] A maximal effective length L.sub.max of the compensating element 50 is thus determined by the distance of the openings 52 at the axial ends. The effective length L.sub.eff is determined by the distance of the two pins 54 that are furthest from one another. The minimum length, which should be chosen as the effective length L.sub.eff, may correspond to at least one third of the cantilever a.sub.y of the first leg 20 in y-direction when using the central fastening portion 12, i.e. when using the central fastening portion 12, L.sub.eff a.sub.y applies. When using the upper fastening portion 14, the compensating element 50 may be arranged at the connecting piece 40, as is shown in FIG. 13. In this case, regarding the effective length L.sub.eff, same corresponds to at least one fourth of the sum of the cantilever of the first leg 20 and the second leg 30 in x-direction, i.e. L.sub.eff (a.sub.x+b.sub.x).

[0086] FIG. 9 shows cross-sectional views of the embodiments of the compensating element 50. In this case, this is, from top to bottom and from left to right, a full or solid rectangular, a hollow rectangular or box profile, a U-shape, a full or solid circular layer, a hollow circular layer, a hollow circular layer having an open bottom, a full or solid trapezoidal shape, a T-shape or a double T-shape. The term circular layer means cross-sectional shape which, analogously to a ball disc or ball layer, constitutes a part of a circle which is cut out from two parallel straight lines. Likewise, the use of an L-shape, a triangular, a massive or hollow semi-circle or the like is possible.

[0087] By doing so, the problems described at the beginning can be considered by suitably choosing the cross-sectional shape of the compensating element 50, because different geometrical moments of inertia offer a possibility of setting the centricity.

[0088] The compensating element 50 therefore may have a first axial geometrical moment of inertia and a second axial geometrical moment of inertia in cross section that is larger than the first axial geometrical moment of inertia. The at least one compensating element 50 is furthermore arranged so that the second axial geometrical moment of inertia acts perpendicularly to the frame plane R. With the axial geometrical moment of inertia, the cross-sectional dependency of the deflection of the at least one compensating element 50 under load is considered. In this context, the deflection of the at least one compensating element 50 is the smaller the bigger the axial geometrical moment of inertia is. For this reason, in the present embodiment, the at least one compensating element 50 may be arranged at the first leg 20 in a way that the gravity causes the smaller deflection. Thus, the bigger axial geometrical moment of inertia acts perpendicularly to the frame plane R. For the better comprehensibility, this is explained by means of a compensating element 50 that is rectangular in cross section. Same has a height h in cross section that is larger than its width b.

[0089] When this rectangular compensating element 50 is arranged at the first leg in a way that the height h extends parallel to the x-axis and the width b extends parallel to the z-axis, i.e. out of the frame plane, the axial geometrical moment of inertia of the compensating element 50 in case of a deflection around an axis parallel to the x-axis, i.e. in case of a gravity-induced deflection, is calculated as follows:

[00006]$\frac{h.Math.b^3}{12}.$

[0090] However, if the compensating element 50 is arranged at the first leg 20 in a way that the width b extends parallel to the x-axis and the height h extends parallel to the z-axis out of the frame plane, the axial geometrical moment of inertia in case of a deflection around an axis parallel to the x-axis, i.e. in case of a gravity-induced deflection, is calculated as follows:

[00007]$\frac{b.Math.h^3}{12}.$

[0091] As the height h is larger than the width b, only in the latter case does the larger axial geometrical moment of inertia act perpendicularly to the frame plane R. Thus, the compensating element 50 and its cross-sectional shape may be used effectively as in the first case, the larger geometrical moment of inertia acts in the frame plane R, namely in case of a deflection around an axis parallel to the z-axis.

[0092] The selected effective length L.sub.eff of the compensating element 50 as well as the assembly position offer further setting possibilities and depend on the weight forces and the respective lengths of the cantilevers measured from the binding, i.e. on top or centrally, to the point of force application, i.e. the drive end 22, 32.

[0093] For a further optimization, FIG. 10 shows the additional use of slot nuts 56 which may be used with hollow or bowl profiles. They prevent a deformation as a result of a too high tightening or fastening torque when the compensating element 50 is fastened.

[0094] A further advantage of the use of the slot nuts 56 is discussed in the following because with the slot nuts 56, the distance of the compensating element 50 to the frame plane R of the C-shaped tool holder 1 can be varied. For this purpose, slot nuts 56 are used which have different extensions parallel to the z-axis, so that the Steiner proportion (parallel axis theorem) and thus the geometrical moment of inertia is increased. This is clarified in the following with reference to FIGS. 10-12, with FIG. 12 showing the cross section of the first leg 20 with two laterally attached compensating elements 50.

[0095] In the state of the art, stiffening elements such as profiles, springs and absorbers are installed symmetrically to the frame plane R in a C-shaped tool holder so as to minimize the operating force-induced bending open of the tool holder. For this purpose, exemplary reference is made to DE 10 2007 020 166 A1 that is discussed in the introductory part.

[0096] This approach is, however, not suitable for the gravity-induced deflection of the C-shaped tool holder 1 addressed in the present application, as for this purpose, the compensating elements 50 would have to be positioned laterally at the C-shaped tool holder 1 in order to counteract the gravity acting in the horizontal position transverse to the frame plane R.

[0097] This requirement becomes apparent when calculating the geometrical moment of inertia of the compensating element 50 with respect to the x-axis which lies in the frame plane R. The overall geometrical moment of inertia I.sub.P,x,ges. of the compensating element 50 increases by the Steiner proportion, i.e. by the distance of the centroid of the area SF of the compensating element 50 from the frame plane R in z-direction to the square multiplied with the cross-sectional surface of the compensating element A.sub.P. This is illustrated in the following formula (4)

I.sub.P,x,ges.=I.sub.P,x+l.sub.P,z.sup.2A.sub.P.

[0098] Here, I.sub.P,x,ges. constitutes the complete geometrical moment of inertia of the compensating element 50, I.sub.P,x. is the geometrical moment of inertia of the compensating element 50 with respect to or around the x-axis, I.sub.P,z is the distance of the centroid of the area S.sub.F of the compensating element 50 to the reference axis, i.e. to the x-axis and A.sub.P is the cross-sectional surface of the compensating element 50. For the purpose of completeness, the width b.sub.C of the first leg 20 as well as the cross-sectional surface A.sub.C of the upper leg 20 and the bending torque M around the x-axis is also drawn into FIG. 12.

[0099] The larger the distance to the frame plane R is chosen, the larger is the Steiner proportion. The following inequality according to formula (5) may be adhered to for a sufficient resistance against gravity:

l.sub.P,z>0

which may be

[00008]$l_{P,z}>\frac{1}{2}{b}_C$$\mathrm{and}$$l_{P,z}>\frac{5}{8}{b}_C$

[0100] When choosing the distance in z-direction, it should be considered for the purpose of completeness that the distance influences the arising interfering contour. Therefore, a middle course should be chosen.

[0101] FIG. 13 shows the attachment of a compensating element 50 when using the above fastening possibility 14 for the binding unit 3. Here, the compensating element 50 may be arranged along the connecting piece 40. The bending torque, that is the acting gravity multiplied with the cantilever, i.e. the distance between force application point and binding unit 3, is decisive for the alignment of the compensating element 50.

[0102] For the sake of completeness, it should be emphasized that a fastening of the fastening element(s) 50 may also take place at the outer edge surfaces or the inner edge surfaces of the C-shaped tool holder 1.

[0103] Now, with reference to FIG. 14, an embodiment of a method for setting an offset difference .sub.z between the first 20 and the second leg 30 of the C-shaped tool holder 1 is explained. In a first step A, an arranging of the C-shaped tool holder 1 takes place in a way that the frame plane R is aligned perpendicular to gravity. After that, a detecting of a first offset of the first leg 20 with regard to the frame plane R takes place in step B, and a detecting of a second offset of the second leg 30 with regard to the frame plane R takes place in step C. Steps B and C can be carried out subsequently or at the same time, with a sequence of step B and C being random.

[0104] As soon as the respective offset has been detected, at least one compensating element 50 is fastened to one or more of the first leg 20, the second leg 30 or the connecting piece 40 in step D. An offset difference .sub.z between the operating end 22 of the first leg 20 and the operating end 32 of the second leg 30 is minimized by that (step E).

[0105] In addition, a setting of a intersecting point S of a first straight line G.sub.1 which corresponds to a movement direction of the punch in the direction of the operating end 32 of the second leg 30, and a second straight line G.sub.2 which extends from the operating end 32 of the second leg 30 in the direction of the operating end 22 of the first leg 20, takes place in step F by the at least one compensating element 50 to an operating point.