C-shaped tool holder, setting tool with the c-shaped tool holder and method for setting an offset difference

Abstract

A C-shaped tool holder (1) with a frame structure (10) defining a frame plane (R) comprises a first leg (20) and a second leg (30) arranged opposite the first leg (20), each having a connecting end and a working end (22, 32). The tool holder (1) also includes a connecting piece (40) connecting the first (20) and second leg (30) at their respective connecting ends. The working end (22) of the first leg (20) serves to attach a punch (24) with an associated drive unit, which defines a direction of movement of the punch (24) towards the working end (32) of the second leg (30), and the working end (32) of the second leg (30) serves to attach a die boss (34).A displacement difference (Δz) due to a gravity-induced displacement between the working end (22) of the first leg (20) and the working end (32) of the second leg (30) perpendicular to the frame plane (R) can be minimized by at least one compensating element (50) arranged on one or more of the following elements: the first leg (20), the second leg (30), or the connecting piece (40). Furthermore, the intersection point (S) of a first straight line (G1), corresponding to the direction of movement of the punch (24) towards the working end (32) of the second leg (30), and a second straight line (G2), extending from the working end of the second leg (30) towards the working end of the first leg (20), can be set to a working point by the at least one compensating element (50).

Description

1. Field of the invention

[0001] The present invention relates to a C-shaped tool holder, a setting device with the C-shaped tool holder and a method for setting an offset difference of the C-shaped tool holder. 2. Background of the invention

[0002] The use of C-shaped tool holders is well known in the art, for example in setting tools. Typically, such a C-shaped tool holder has a frame structure that defines a frame plane and comprises two legs connected by a joint. At the free ends of the legs, a punch with a drive unit and a die dome are arranged in a setting tool.

[0003] Increasing demands on such C-shaped toolholders regarding accuracy and the centricity or concentricity of the joint to be produced are narrowing the tolerances for process-induced deformations. One such process-induced deformation is, for example, the bending of the C-shaped toolholder during the setting process.

[0004] For centricity, the absolute deformation of the C-shaped tool holder is not relevant, but rather that the C-shaped tool holder deforms in such a way that the punch and die meet centrically or concentrically at the working or joining point. In other words, both legs of the C-shaped tool holder must deform equally. The working or joining point is the point of contact between the punch and die and the intervening components, where the component thicknesses are negligible compared to the total stroke of the setting tool.

[0005] An example of reducing such process-induced deformations can be found in DE 10 2007 020 166 A1. This patent describes a tool holder with mechanical means, which is used, for example, in systems for forming joining processes, in particular clinching and self-piercing riveting, as well as thermal joining processes such as resistance spot welding, handling processes, embossing processes, screwing and press-fitting processes. The tool holder has a tool holding area that holds a tool which, during operation, is pressed against a workpiece or the like with an operating force under elastic deformation of the tool holder's truss structure.Increased operational flexibility is achieved by providing mechanical means, particularly detachable ones, to the toolholder, acting within or on a deformation zone. These means influence predetermined mechanical properties, especially deformation properties, of the toolholder in a predetermined manner during deformation. Accordingly, these mechanical means counteract process-induced deformation of the toolholder, i.e., bending of the C-shaped toolholder.

[0006] In modern applications, C-shaped tool holders are frequently used in conjunction with multi-axis robots. For this purpose, the C-shaped tool holder has a mounting area for a connecting unit for attachment to the multi-axis robot, either centrally located in the area of ​​the connecting piece or adjacent to it on the first leg (i.e., at the top). Therefore, in the corresponding joining tasks, the C-shaped tool holder is often not exclusively vertically oriented, but also inclined or horizontally.

[0007] Particularly in the horizontal tool position, the C-shaped tool holder deforms due to its own weight and the weight of the drive, which significantly affects the concentricity of the connection. Furthermore, various other disturbances, such as play in the guides, manufacturing tolerances, and the material thickness of the C-shaped tool holder, can lead to deviations from an ideal working or joining point. This must also be taken into account due to the increasing demands placed on setting tools.

[0008] Furthermore, it should be considered that standardized components are typically used within a modular system to meet the requirements for costs, delivery times, and development effort. Within such a modular system for a typical setting tool, there is often only one ideal combination for each variant of the C-shaped tool holder with a die dome and a punch with a drive unit. In other words, each C-shaped tool holder has an ideal working or joining point for a given connection and drive weight. The further the actual working or joining point deviates from the ideal working or joining point, the greater the eccentricity of the connection. Therefore, all other combinations within the modular system typically exhibit an eccentricity.

[0009] The higher the requirements for centricity, the fewer combinations can be achieved with the modular system.

[0010] For tools where the standard modular system is insufficient to meet the centricity requirements, customized solutions are developed. These include, on the one hand, the production of stiffer C-shaped toolholders, which feature a wider frame structure. However, this results in higher costs, increased weight, and a consequently larger interference contour. Alternatively, this problem can be solved by a special connection to, for example, a multi-axis robot. This, too, leads to higher costs and increased weight, making it viable only for certain combinations.

[0011] In summary, a disadvantage of the well-known C-shaped toolholders is that the centricity requirements limit the possible combinations of punch, drive unit, and die, necessitating the use of custom designs. This results in high design and manufacturing costs, long delivery times, increased storage costs, the need for corresponding spare parts inventory, and increased effort in maintaining parts master data.

[0012] Improved centricity can usually only be achieved by increasing the width of the C-shaped toolholder. This leads to higher manufacturing costs due to the required raw material and machining time, a larger interference contour of the C-shaped toolholder, a higher dead weight, and thus also a higher overall weight. The higher overall weight may necessitate switching to a larger robot class when connecting an exemplary setting device to a multi-axis robot, which further increases costs. Furthermore, the additional dead weight results in greater deformation, which counteracts the advantage of increased stiffness. Document EP 1 119 439 A1 discloses a C-shaped toolholder with a frame structure according to the preamble of claim 1.

[0013] The object of the present invention is therefore to provide an alternative solution for a C-shaped tool holder that reliably meets the requirements for the centricity of the connection, even in a horizontal tool position, in combination with various drive units, and thus overcomes the disadvantages mentioned above. Similarly, it is an object to provide a suitable setting device and a method for adjusting the offset difference of the C-shaped tool holder. 3. Summary of the invention

[0014] The above problem is solved by a C-shaped tool holder according to independent claim 1, a setting device with the C-shaped tool holder according to independent claim 10, and a method for adjusting an offset difference of the C-shaped tool holder according to independent claim 12. Advantageous embodiments and further developments will become apparent from the following description, the drawings, and the pending claims.

[0015] A C-shaped tool holder according to the invention, with a frame structure defining a frame plane, comprises a first leg and a second leg arranged opposite the first leg, each leg having a connecting end and a working end, a connecting piece by which the first and second legs are connected to each other at their respective connecting ends, wherein the working end of the first leg serves to attach a punch with an associated drive unit, which defines a direction of movement of the punch in the direction of the working end of the second leg, and the working end of the second leg serves to attach a die dome, wherein an offset difference due to a gravity-induced offset between the working end of the first and the working end of the second leg perpendicular to the frame plane can be minimized by at least one compensating element.which is arranged on one or more of the following elements: the first leg, the second leg or the connecting piece, and an intersection of a first straight line corresponding to the direction of movement of the punch towards the working end of the second leg, and a second straight line extending from the working end of the second leg towards the working end of the first leg, is adjustable to a working point by the at least one compensating element.

[0016] The following section discusses the C-shaped tool holder when used in a setting device. Preferably, the C-shaped tool holder has a truss-like frame structure. Due to its use in a setting device, a punch with an associated drive unit is preferably attached to the working end of the first leg, and a die dome is attached to the working end of the second leg. The C-shaped tool holder can be connected to a multi-axis robot, for example, via a central mounting area for a connection unit. The connection unit is therefore located centrally on the connecting piece.

[0017] Initially, a vertical tool position is assumed. In this vertical position, the frame plane runs parallel to gravity. In other words, the first line, which corresponds to the direction of movement of the punch towards the working end of the second arm, and the second line are coincident. The first and second lines therefore run along a first axis, namely the x-axis of a Cartesian coordinate system. The y-axis extends parallel to the first and second arms. The x- and y-axes thus define the frame plane as determined by the frame structure.

[0018] If the corresponding setting device is now arranged in a horizontal position, the weight of the drive unit on the first leg causes the working end of the first leg to be displaced from the frame plane due to gravity, i.e., along the z-axis. The decisive factor here is the lever arm of the first leg in the y-direction, i.e., the length of the first leg or the distance between the working end of the first leg and the connecting unit along the y-axis. This applies analogously to the working end of the second leg with the die dome.

[0019] Due to the lower weight of the die dome compared to the drive unit, the gravity-induced offset for the working end of the second leg is smaller than the gravity-induced offset of the first leg. In other words, and considering only this effect, the first and second lines are parallel to each other, but no longer coincide. Thus, a gravity-induced offset difference arises between the working end of the first and the working end of the second leg, which must be compensated for.

[0020] Additionally, the lever arms of the first and second legs resulting from the exemplary central connection along the x-axis must be taken into account. These lever arms cause an angular offset in addition to the gravity-induced displacement, resulting in the first and second lines no longer being parallel to each other, but intersecting at a single point. However, this point of intersection does not necessarily correspond to the operating point of the setting device, so a corresponding adjustment or correction is also required here.

[0021] To compensate for these effects, at least one compensating element is provided. In the present example, this element is attached to the first leg due to the larger gravity-induced offset. This attachment is preferably detachable, for example, by means of screws, pins, clamps, or clips. The detachable attachment allows for adjustments to account for the changed gravity-induced offset when using a different punch with a drive unit and / or a different die head. Furthermore, the C-shaped tool holder preferably has two compensating elements, preferably on opposite sides of the same element, in this case, the first leg. In this way, the deformation of the first leg is adapted to the deformation of the second leg so that the first and second lines meet or intersect at the operating point.

[0022] In an exemplary connection of the tool holder to the multi-axis robot in the area of ​​the first leg, i.e., in the case of an upper connection, it is preferred that the at least one compensating element is arranged at least on the connecting piece. This is due to the altered lever arms along the x-axis and the y-axis of the first and second legs resulting from the different connection, and the consequent change in the deformation of the first and second legs. For further details, please refer to the detailed description.

[0023] A general advantage of this approach is that the eccentricity of a standardized modular tool in the form of a C-shaped tool holder can be subsequently adjusted. Therefore, the at least one compensating element can preferably be variably attached to one of the elements: first leg, second leg, or connecting piece. Advantageously, this method can also be used to compensate for play in the hold-down device of the exemplary setting tool.

[0024] This adjustability also allows the centricity to be individually set for a wide variety of die head and C-shaped tool holder combinations. This continues to allow the use of a modular system, enabling additional combinations of punch with drive unit and die head compared to the prior art.

[0025] Furthermore, the C-shaped toolholders need to be less rigid, and their weight can be reduced. This also means that the width of the C-shaped toolholders can be reduced, thereby also reducing the interference contour. This has a further positive effect on manufacturing costs, as these are also reduced with a smaller width of the C-shaped toolholder.

[0026] According to a preferred embodiment of the C-shaped tool holder, the at least one compensating element has a first axial area moment of inertia and a second axial area moment of inertia in its cross-section, which is greater than the first axial area moment of inertia. The at least one compensating element is arranged such that the second axial area moment of inertia acts perpendicular to the frame plane. The axial area moment of inertia accounts for the cross-sectional dependence of the deflection of the at least one compensating element under load. The deflection of the at least one compensating element is smaller the larger the axial area moment of inertia. For this reason, the at least one compensating element is arranged on one of the elements—first leg, second leg, or connecting piece—such that gravity causes the smaller deflection.Thus, the larger axial area moment of inertia acts perpendicular to the frame plane. For better understanding, this approach is explained using a compensating element with a rectangular cross-section. This element has a height h in cross-section that is greater than its width b.

[0027] In a first case, this rectangular compensating element is arranged on the first leg such that its height h extends parallel to the x-axis of the input-defined Cartesian coordinate system and thus to the frame plane. Accordingly, its width b extends parallel to the z-axis, i.e., out of the frame plane. The axial area moment of inertia of the compensating element when bent about an axis parallel to the x-axis, i.e., when subjected to gravity-induced bending, is therefore calculated as follows: h ⋅ b 3 12 .

[0028] In the second case, the compensating element is positioned on the first leg such that the width b extends parallel to the x-axis, causing the height h to extend parallel to the z-axis out of the frame plane. The axial area moment of inertia for bending about an axis parallel to the x-axis, i.e., for gravity-induced bending, is then calculated as follows: b ⋅ h 3 12 .

[0029] Since the height h is greater than the width b, the larger axial moment of inertia acts perpendicular to the frame plane only in this second case. In the first case, the larger moment of inertia acts in the frame plane, namely when the frame is bent about an axis parallel to the z-axis.

[0030] As a result of this preferred orientation of the compensating element, the at least one compensating element stiffens, for example, the first leg in such a way that the offset difference between the first and second leg is minimized and the intersection point between the first and second lines corresponds to the working point of the exemplary setting device.

[0031] Preferably, the compensating element has a profile shape with one of the following cross-sectional forms: rectangle, semicircle, layer of circles, triangle, T-shape, double-T-shape, L-shape, U-shape, trapezoid, or a combination thereof. These shapes exhibit a particularly high axial moment of inertia in one direction. Therefore, the invention can be implemented particularly advantageously with these shapes.

[0032] In a further advantageous embodiment of the C-shaped tool holder, the at least one compensating element has at least two attachment points, preferably at least four, six, eight, or ten attachment points, and particularly preferably a plurality of attachment points. Especially when using a plurality of attachment points, starting with four, two attachment points are preferably located directly next to each other, for example, at each end of the at least one compensating element. Furthermore, the use of two attachment points directly next to each other counteracts any bending of the C-shaped tool holder induced by operating forces.

[0033] It is also preferred that the compensating element has the form of a hollow or shell profile and that two T-nuts are provided between the compensating element and the first leg, the second leg, or the connecting piece. On the one hand, the T-nuts prevent the at least one compensating element from deforming and thus losing its beneficial properties. On the other hand, the area moment of inertia can be further influenced by the dimensions of the T-nuts. Reference is made to Steiner's theorem in this regard. This will also be clarified later with reference to the detailed description and the figures.

[0034] A setting device according to the invention comprises a C-shaped tool holder according to the invention, wherein a punch with an associated drive unit is attached to the working end of the first leg and a die dome is attached to the working end of the second leg. A corresponding setting device has already been discussed in detail within the context of the discussion of the C-shaped tool holder according to the invention. To avoid unnecessary repetition, reference is therefore made to the corresponding explanations regarding the technical effects and advantages.

[0035] Advantageously, the setting tool is attached to a multi-axis robot via the C-shaped tool holder. This allows the setting tool to be used in different orientations, for example, in an automated production line.

[0036] A method according to the invention for adjusting an offset difference between a first and a second leg of a C-shaped tool holder according to the invention comprises the following steps: arranging the C-shaped tool holder such that a frame plane is oriented perpendicular to gravity, then determining a first offset of the first leg with respect to the frame plane and determining a second offset of the second leg with respect to the frame plane, subsequently attaching at least one compensating element to one or more of the first leg, the second leg, or the connecting piece, and minimizing an offset difference between the working end of the first leg and the working end of the second leg. Reference is also made to the above descriptions of the C-shaped tool holder according to the invention with regard to the method according to the invention, in particular with regard to the resulting technical effects and advantages.

[0037] In an advantageous embodiment, the method comprises the further step of setting the intersection point of a first straight line, corresponding to the direction of movement of the punch towards the working end of the second leg, and a second straight line, extending from the working end of the second leg towards the working end of the first leg, through the at least one compensating element, at a working point. This step takes into account not only the gravity-induced offset difference but also the existing angular offset.

[0038] It is also preferred that the at least one compensating element has in cross-section a first axial area moment of inertia and a second axial area moment of inertia that is greater than the first axial area moment of inertia, and that the fastening step is carried out such that the compensating element is arranged so that the second axial area moment of inertia acts perpendicular to the frame plane. This procedure stiffens the corresponding element on which the at least one compensating element is arranged, thereby compensating for the offset difference and aligning the intersection of the first and second lines with the operating point. In this respect, reference is made to the corresponding discussion above of the preferred embodiment of the C-shaped tool holder and the associated example of the compensating element with a rectangular cross-section.

[0039] Furthermore, it is advantageous that the at least one compensating element is attached to one or more of the following elements via at least two attachment points: the first leg, the second leg, or the connecting piece. When using a plurality of attachment points, starting with four, any operational force-induced bending of the C-shaped tool holder can additionally be taken into account and preferably minimized.

[0040] In a further preferred embodiment of the method, the at least one compensating element is detachably attached to the first leg, the second leg, or the connecting piece, preferably by means of screws, pins, clips, or clamps. This detachable attachment allows the C-shaped tool holder to be adapted to various punches with drive units and die domes, as it enables adjustment to the respective weight. Thus, the modular design principle remains applicable.

[0041] Finally, the at least one compensating element advantageously has the form of a hollow or shell profile, and at least two T-nuts are provided between the compensating element and the first leg, the second leg, or the connecting piece. As shown above, the T-nuts prevent the at least one compensating element from deforming during fastening and thus losing its beneficial properties. Furthermore, the area moment of inertia can be further influenced by the dimensions of the T-nuts. 4. Brief summary of the drawings

[0042] The present invention is described in detail below with reference to the drawings. Identical reference numerals in the drawings denote identical components and / or elements. The drawings show: Figure 1: A schematic view of various connection options for a C-shaped tool holder to a multi-axis robot; Figure 2: A schematic view of a special solution for connecting a C-shaped tool holder to a multi-axis robot; Figure 3: A diagram illustrating the gravity-induced deformation of a C-shaped tool holder; Figure 4: A schematic representation illustrating the gravity-induced offset when the C-shaped tool holder is in a horizontal position; Figure 5: A schematic representation illustrating the angular offset when the C-shaped tool holder is in a horizontal position; Figure 6: A schematic view of a first embodiment of a C-shaped tool holder according to the invention using the central connection and with a compensating element arranged on the first leg; Figure 7: A view of the upper region of the C-shaped tool holder according to the invention. Figure 4with alternative attachment points of the at least one compensating element, Figure 8 a perspective view of the at least one compensating element, Figure 9 preferred profile shapes for the at least one compensating element in cross-section, Figure 10 the C-shaped tool holder according to Figure 6 In an exploded view, Figure 11 shows a view of the upper area of ​​the C-shaped tool holder according to Figure 6 with further alternative attachment points of the at least one compensating element, Figure 12 a sectional view along line AA from Figure 11 Figure 13 shows a schematic view of a second embodiment of the C-shaped tool holder using the upper connection and with a compensating element arranged on the connecting piece and on the first leg, and Figure 14 shows a schematic flow diagram of an embodiment of a method according to the invention for adjusting the offset difference. 5. Detailed description of preferred embodiments

[0043] The following and with reference to Figure 1 A section of a C-shaped tool holder 1 is shown first to illustrate the possible attachment positions on a multi-axis robot. The C-shaped tool holder 1 has a truss-like frame structure 10. Furthermore, the C-shaped tool holder 1 comprises a first leg 20 and a second leg 30 arranged opposite the first leg 20. The first leg 20 has a working end 22 and a connecting end. Similarly, the second leg 30 comprises a working end 32 and a connecting end. At the connecting ends, the first leg 20 and the second leg 30 are connected to each other via a connecting piece 40. In the Figure 1 The illustrations shown include the connecting piece 40 as well as the area of ​​the first leg 20 with the connecting end.

[0044] For a better understanding of the following explanations, a vertical tool position is assumed, as described in Figure 1 As indicated, in this vertical tool position, the frame plane R runs parallel to gravity. In other words, a first straight line G1, which corresponds to a direction of movement of a punch towards the working end of the second leg 30, and the second straight line G2 are coincident. The first G1 and the second G2 therefore run 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 y-axes thus span the frame plane R defined by the frame structure 10 (see also Figures 4 and 5 ).

[0045] As in Figure 1The C-shaped tool holder 1 comprises a central mounting area 12 in the region of the connecting piece and an upper mounting area 14 in the region of the first leg 20. The upper mounting area 14 in the region of the first leg 20 is preferably oriented such that it forms an angle of 45° with the x-axis, and therefore also with the y-axis. A connection unit 3 for linking to the multi-axis robot is mounted on one of the mounting areas 12, 14.

[0046] From left to right shows Figure 1A centrally mounted attachment unit 3, whose attachment surface to the multi-axis robot runs parallel to both the x- and z-axes of the Cartesian coordinate system. In the other three illustrations, the attachment unit 3 is mounted on the upper mounting area 14, with the attachment surface oriented differently in each case. Thus, the attachment surface can be, as in the left illustration of Figure 1 , initially parallel to the x- and z-axes. Alternatively, the connection surface can run parallel to the y- and z-axes. This is shown in the third illustration from left to right in Figure 1shown. In other words, and with reference to these two orientations of the attachment surface, there is an angle of 45° between the upper mounting area 14 and the attachment surface. Finally, and with reference to the last illustration, the attachment surface, like the upper mounting area 14, can form a 45° angle with both the x- and y-axes and extend parallel to the z-axis.

[0047] Figure 2 Figure 3 shows a special solution for a connection unit 3. In this case, the connection is not only made on the outer part of the C-shaped tool holder 1, but extends over the width of the C-shaped tool holder 1 in the area of ​​the connecting piece 40.

[0048] Now, referring to the Figures 3-5 First, the behavior of a C-shaped tool holder 1 when used in a horizontal orientation is explained in order to illustrate the underlying problem.

[0049] This shows Figure 3 The top view schematically shows the C-shaped tool holder 1 with the punch with drive unit 24 on the first leg 20 and the die dome 34 on the second leg 30. In this example, the connection to the multi-axis robot is made centrally at the C-shaped tool holder 1.

[0050] Due to the weight, especially of the punch 24 with drive unit and the die dome 34, these bend in relation to Figure 3 downwards, as indicated by the corresponding arrows. Likewise, the resulting first G1 and second G2 lines for the deformed state have been drawn for clarification. As can be seen, the first line G1 corresponds to the direction of movement of the punch 24 towards the die dome 34. The second line G2 runs from the working end of the second leg 30 towards the working end 22 of the first leg 20. For simplification, in Figure 3Assuming that the second straight line G2 continues to run parallel to the x-axis of the reference system, i.e., the Cartesian coordinate system introduced at the beginning.

[0051] Above and below the die dome 34, the permissible eccentricity range is shown within the drawn lines. The intersection of the first straight line with this permissible range provides an overview of the theoretically possible combinations of C-shaped tool holder 1 and die dome 34 size with a constant punch 24 and drive unit.

[0052] The aspects underlying this deformation / bending are now discussed with reference to the schematic diagrams. Figures 4 and 5 discussed.

[0053] Both figures schematically show the C-shaped tool holder 1, in which the connecting unit 3 is centrally attached to the connecting piece 40. For orientation, the Cartesian coordinate system with x, y and z axes, which is used as the reference system in the application, is shown.

[0054] The frame plane R defined by the frame structure 10 thus lies in the x, y plane, as shown at the beginning. Due to the horizontal arrangement of the C-shaped tool holder 1, the frame plane R therefore runs parallel to the ground.

[0055] At the working end 22 of the first leg 20, the punch 24 with drive unit is provided. This is designated as the first mass m1. At the working end 32 of the second leg 30, the die dome 34 is provided. This is designated as the second mass m2. The first mass m1 is larger than the mass m2, so the resulting first force F1 at the working end 22 of the first leg 20 is also greater than the resulting second force F2 at the working end 32 of the second leg 30. This is illustrated both by the arrows at the forces F1 and F2 and by the dimensions of the boxes symbolizing the masses.

[0056] The distance to the connection unit 3 is relevant for the behavior of each leg 20, 30 at the working end 22, 32, as this represents the attachment point. Schematically, each leg 20, 30 is therefore divided into a first lever arm parallel to the x-axis and a second lever arm parallel to the y-axis. The first leg 20 thus has the lever arm ax in the x-direction, i.e., parallel to the x-axis, and the lever arm ay in the y-direction, i.e., parallel to the y-axis. Similarly, the second leg 30 comprises the lever arm bx in the x-direction, i.e., parallel to the x-axis, and the lever arm by in the y-direction, i.e., parallel to the y-axis.

[0057] Figure 4This serves to illustrate a first problem with the horizontal arrangement of the C-shaped tool holder 1, namely a possible difference in the offset of the working ends 22, 32 perpendicular to the frame plane R, i.e., parallel to the z-axis. The lever arm in the y-direction, i.e., ay and by, is decisive for this offset. Since the lever arms ay and by are equal in the example shown, the different masses m1 and m2, and thus the different magnitudes of the acting first F1 and second forces F2, cause an offset difference Δz in the z-direction, i.e., parallel to the z-axis, between the first leg 20 and the second leg 30. Therefore, the first line G1 and the second line G2 are no longer concentrically or centrally aligned with each other. Rather, an eccentricity exists.

[0058] A corresponding deflection w can generally be calculated using formula (1): w = F l 3 3 E I calculate where F is the force, l is the length of the lever arm, E is the modulus of elasticity and I is the area moment of inertia of the leg cross-section.

[0059] The second problem is addressed in Figure 5 This is further clarified. In addition to the offset difference Δz, an angular offset ϕ also occurs. This angular offset results from the lever arm ax of the first leg 20 in the x-direction and the lever arm bx of the second leg 30 in the x-direction. The corresponding angles of the first leg 20 and the second leg 30 are labeled ϕa and ϕb, respectively. The angular offset ϕa of the first leg 20 and the angular offset ϕb of the second leg 30 ensure that the first line G1 and the second line G2 intersect at point S. However, this point does not necessarily coincide with the operating point of the setting device. A deviation between point S and the operating point also leads to an eccentricity that must be compensated for.

[0060] In addition to the deflection of legs 20, 30, an inclination can also be observed, resulting in an angular offset. The inclination ϕ can generally be calculated using formula (2): φ = F l 2 2 E I calculate where F is the force, l is the length of the lever arm, E is the modulus of elasticity and I is the area moment of inertia of the leg cross-section.

[0061] Therefore, to achieve optimal operation, both the offset difference Δz and the angular offset must be minimized. Furthermore, the intersection point S of the first line G1 and the second line G2 must be adjusted so that the two lines meet at the working point; that is, the intersection point S must correspond to the working point.

[0062] In order for the offset or offset difference Δz to be equal to or at least approximately zero, the deflections of the first leg 20 and the second leg 30 must be equalized. Consequently, the condition that the deflection of the first leg 20 and the deflection of the second leg 30 are approximately equal must be fulfilled as far as possible.

[0063] The deflection of the first leg 20, subsequently denoted by wa, and the deflection of the second leg 30, subsequently denoted by wb, each consist of a component in the x-direction and a component in the y-direction, equivalent to the lever arms. From this, by applying superposition, formula (3) follows: w a = F 1 a y 3 3 E I a + F 1 a x 3 3 E I a ≅ F 2 b y 3 3 E I b + F 2 b x 3 3 E I b = w b

[0064] The inclination ϕ of the first and second legs 20, 30 with respect to the x-direction causes, as explained above, the first line G 1 and the second line G 2 to intersect at point S. Although the angular offset is negligibly small compared to the deflections, it is important for the point of intersection S.

[0065] To solve this, shows Figure 6A first embodiment of a C-shaped tool holder 1 according to the invention. This holder has two compensating elements 50 which are detachably attached to opposite sides of the first leg 20 by means of pins 54. All detachable connection types that can be produced with hand tools are suitable for attaching the compensating elements 50 to the C-shaped tool holder 1 or to the corresponding frame structure 10. These include, in particular, screwing, pinning, clamping, and clipping. For the sake of completeness, it should be noted that the compensating element 50 does not necessarily have to be straight, but can also be curved, arcuate, or bent.

[0066] In the illustrated example, the compensating element 50 consists of a U-shaped profile with ten openings 52. Two openings 52 are located directly adjacent to each other at a first axial end, while the remaining eight openings 52 are spaced apart from these, beginning at the second axial end. Although two openings 52 are arranged side by side at the first axial end in this example, using only one opening 52 at each end is sufficient to achieve the desired function. The frame structure 10 of the C-shaped tool holder 1 has corresponding openings 16. This is illustrated, for example, in Figure 10 clearly.

[0067] The area moments of inertia of the first leg 20 and the second leg 30 are generally not constant over the length of the first leg 20 and the second leg 30. However, by using the compensating element 50, the respective area moment of inertia is increased and the deflection is thereby reduced until the first line G 1 and the second line G 2 intersect at the operating point, so that the operating point and the intersection point S coincide.

[0068] In Figure 6 The pins 54 are arranged in the two openings 52 at the first axial end of the compensating element 50, as well as in the penultimate pair of openings in the series of eight openings 52, starting at the second axial end of the compensating element 50. In contrast, the pins 54 are in Figure 7in the last pair of the series of eight openings 52. In this respect, it should be further emphasized that the use of two immediately adjacent pins also reduces the risk of the C-shaped tool holder 1 bending due to process-related forces during operation.

[0069] The effect of the compensating element 50 is influenced, in addition to the shape of the compensating element, by the position of the pins 54. This is described with reference to Figure 8 explained.

[0070] The maximum effective length Lmax of the compensating element 50 is therefore determined by the distance between the openings 52 at the axial ends. The effective length Leff is determined by the distance between the two pins 54 furthest apart. When using the middle mounting area 12, the minimum effective length Leff should preferably be at least one-third of the lever arm ay of the first leg 20 in the y-direction; that is, when using the middle mounting area 12, Leff ≥ 1 / 3 ay. When using the upper mounting area 14, the compensating element 50 is preferably arranged on the connecting piece 40 as shown in Figure 13 as shown. In this case, the effective length Leff must be at least one quarter of the sum of the lever arm of the first leg 20 and the second leg 30 in the x-direction, i.e., Leff ≥ 1 / 4 (ax + bx).

[0071] Figure 9Figure 50 shows preferred cross-sectional views of preferred embodiments of the compensating element. From top to bottom and left to right, these are a solid rectangle, a hollow rectangle or box profile, a U-shape, a solid circular layer, a hollow circular layer, a hollow circular layer open at the bottom, a solid trapezoidal shape, a T-shape, or a double-T-shape. The term "circular layer" refers to a cross-sectional shape that, analogous to a spherical disk or spherical layer, represents a portion of a circle cut off by two parallel lines. The use of an L-shape, a triangle, a solid or hollow semicircle, or the like is also possible.

[0072] Thus, the problems initially identified can be addressed by appropriately selecting the cross-sectional shape of the compensating element 50. Different area moments of inertia offer a way to adjust the centricity.

[0073] Preferably, the compensating element 50 therefore has in cross-section a first axial area moment of inertia and a second axial area moment of inertia that is greater than the first axial area moment of inertia. The at least one compensating element 50 is also arranged such that the second axial area moment of inertia acts perpendicular to the frame plane R. The axial area moment of inertia takes into account the cross-sectional dependence of the deflection of the at least one compensating element 50 under load. The deflection of the at least one compensating element 50 is smaller the larger the axial area moment of inertia. For this reason, in the present embodiment, the at least one compensating element 50 is preferably arranged on the first leg 20 such that gravity causes the smaller deflection. Thus, the larger axial area moment of inertia acts perpendicular to the frame plane R.For better understanding, this is explained using a rectangular cross-section compensating element 50. This element has a height h in cross-section that is greater than its width b.

[0074] If this rectangular compensating element 50 is arranged on the first leg such that the height h extends parallel to the x-axis and the width b parallel to the z-axis, i.e., out of the frame plane, then the axial area moment of inertia of the compensating element 50 in the event of a bending about an axis parallel to the x-axis, i.e., in the event of a gravity-induced bending, is calculated as follows: h ⋅ b 3 12 .

[0075] However, if the compensating element 50 is arranged on the first leg 20 such that the width b extends parallel to the x-axis and the height h parallel to the z-axis out of the frame plane, then the axial area moment of inertia in the event of a bending about an axis parallel to the x-axis, i.e., in the event of a gravity-induced bending, is calculated as b ⋅ h 3 12 .

[0076] Since the height h is greater than the width b, the larger axial area moment of inertia acts perpendicular to the frame plane R only in the latter case. Thus, the compensating element 50 and its cross-sectional shape are used particularly effectively. In the first case, the larger area moment of inertia acts in the frame plane R, namely during bending about an axis parallel to the z-axis.

[0077] The selected effective length L eff of the compensating element 50 as well as the mounting position offer further adjustment options and depend on the weight forces and the respective lengths of the lever arms measured from the connection, i.e. top or middle, to the point of force application, i.e. the drive end 22, 32.

[0078] For further optimization, shows Figure 10 The additional use of T-nuts 56, which are used particularly with hollow and shell profiles. These prevent deformation due to excessive tightening or fastening torque when attaching the compensating element 50.

[0079] A further advantage of using the T-nuts 56 is discussed below, because the distance of the compensating element 50 from the frame plane R of the C-shaped tool holder 1 can be varied with the T-nuts 56. For this purpose, T-nuts 56 are used that have different extensions parallel to the z-axis, which increases the Steiner term (Steiner's theorem) and thus the area moment of inertia. This will be discussed below with reference to the Figures 10-12 clarifies, whereby Figure 12 the cross-section of the first leg 20 with two laterally attached compensating elements 50.

[0080] In the prior art, stiffening elements such as profiles, springs, and dampers are installed symmetrically to the frame plane R in a C-shaped tool holder, thereby minimizing the bending of the tool holder induced by operating forces. For an example, reference is made to DE 10 2007 020 166 A1, discussed in the introductory section.

[0081] However, this approach is not suitable for the gravity-induced bending of the C-shaped tool holder 1 addressed in the present application. This is because the compensating elements 50 must be positioned laterally on the C-shaped tool holder 1 in order to counteract the force of gravity acting perpendicular to the frame plane R in the horizontal position.

[0082] This requirement becomes clear when calculating the area moment of inertia of the balancing element 50 with respect to the x-axis, which lies in the frame plane R. The total area moment of inertia IP,x,ges of the balancing element 50 is increased by the Steiner term, i.e., by the square of the distance of the centroid SF of the balancing element 50 from the frame plane R in the z-direction, multiplied by the cross-sectional area of ​​the balancing element AP. This is shown in the following formula (4). I P , x , ges . = I P , x + l P , z 2 × A P

[0083] Here, IP,x,ges represents the total area moment of inertia of the balancing element 50, IP,x is the area moment of inertia of the balancing element 50 with respect to or about the x-axis, lP,z is the distance of the centroid SF of the balancing element 50 from the reference axis, i.e., the x-axis, and AP is the cross-sectional area of ​​the balancing element 50. For the sake of completeness, in Figure 12 The width bc of the first leg 20 as well as the cross-sectional area AC of the upper leg 20 and the bending moment M about the x-axis are also shown.

[0084] The greater the distance from the frame plane R, the greater the Steiner term. For sufficient resistance to gravity, the following inequality according to formula (5) should preferably be observed: l P , z > 0 preferably l P , z > 1 2 b C and especially preferred l P , z > 5 8 b C

[0085] For the sake of completeness, it should be noted that the distance influences the resulting interference contour when choosing the distance in the z-direction. Therefore, a compromise should be chosen.

[0086] Figure 13 Figure 1 shows the attachment of a compensating element 50 when using the upper mounting option 14 for the connecting unit 3. Here, the compensating element 50 was attached specifically along the connecting piece 40. The decisive factor for the orientation of the compensating element 50 is the bending moment, i.e., the acting gravitational force multiplied by the lever arm, which is the distance between the point of force application and the connecting unit 3.

[0087] For the sake of completeness, it should be emphasized that the compensating element(s) 50 can also be attached to the outer edge surfaces or the inner edge surfaces of the C-shaped tool holder 1.

[0088] Now, referring to Figure 14An embodiment of a method for setting an offset difference Δz_ between the first leg 20 and the second leg 30 of the C-shaped tool holder 1 is described. In a first step A, the C-shaped tool holder 1 is arranged such that the frame plane R is oriented perpendicular to gravity. Then, in step B, a first offset of the first leg 20 relative to the frame plane R is determined, and in step C, a second offset of the second leg 30 relative to the frame plane R is determined. Steps B and C can be performed sequentially or simultaneously, and the order of steps B and C is arbitrary.

[0089] After the respective offset has been determined, in step D at least one compensating element 50 is attached to one or more of the first leg 20, the second leg 30, or the connecting piece 40. This minimizes an offset difference Δz_ between the working end 22 of the first leg 20 and the working end 32 of the second leg 30 (step E).

[0090] In addition, in step F an intersection point S of a first straight line G 1, which corresponds to a direction of movement of the punch in the direction of the working end 32 of the second leg 30, and a second straight line G 2, which runs from the working end 32 of the second leg 30 in the direction of the working end 22 of the first leg 20, is set, through which at least one compensating element 50 is set to a working point. 6. List of reference symbols

[0091] 1 Tool holder 3 Connection unit 10 Frame structure 12 Rear mounting option for the connection unit 3 14 Upper mounting option for connection unit 3 16 Openings in the frame structure for mounting the compensating element 50 20 first leg 22 working end of the first leg 24 punch with drive unit 30 Second leg 32 End of work of the second leg 34 Matrix dome 40 connector 50 Compensating element 52 Openings in the compensating element 54 Pins 56 T-nuts AC Cross-sectional area of ​​the first leg 20 AP Cross-sectional area of ​​the compensating element 50 ax Lever arm of the first leg 20 in x-direction ay Lever arm of the first leg 20 in y-direction b C Width of the first leg 20 bx Lever arm of the second leg 30 in x-direction by Lever arm of the second leg 30 in y-direction F 1 First force F 2 Second force G 1 First line G 2 Second line L eff Effective length of the compensating element 50 L max Maximum length of the compensating element 50 l P,z Distance of the centroid from the x-axis m 1 First mass m 2 Second mass M Bending moment about the x-axis R Frame plane S Intersection point SF Centroid of the compensating element 50 Δz Offset difference between first leg 20 and second leg 30 ϕ a Angle of first leg 20 ϕ b Angle of second leg 30

Claims

1. A C-shaped tool holder (1) with a frame structure (10) defining a frame plane (R) comprising a) a first leg (20) and a second leg (30) that is arranged opposite to the first leg (20), each leg having a connecting end and an operating end (22, 32), b) a connecting piece (40) by means of which the first leg (20) and the second leg (30) are connected with each other at the respective connecting end, wherein c) the operating end (22) of the first leg (20) serves for fastening a punch (24) with an associated drive unit defining a movement direction of the punch (24) in the direction of the operating end (32) of the second leg (30), and the operating end (32) of the second leg (30) serves for fastening a die dome (34) wherein d) an offset difference (Δz) due to a gravity-caused offset between the operating end (22) of the first (20) and the operating end (32) of the second leg (30) perpendicular to the frame plane (R) is minimizable by at least one compensating element (50) which is arranged at one or more of the following elements: the first leg (20), the second leg (30) or the connecting piece (40), characterized by e) an intersecting point (S) of a first straight line (G1) corresponding to the movement direction of the punch (24) in the direction of the operating end (32) of the second leg (30), and a second straight line (G2) extending from the operating end of the second leg (30) in the direction of the operating end of the first leg (20), is settable to an operating point by means of the at least one compensating element (50).

2. The C-shaped tool holder (1) according to claim 1, wherein in cross section, the at least one compensating element (50) has 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 (50) is arranged so that the second axial geometrical moment of inertia acts perpendicularly to the frame plane (R).

3. The C-shaped tool holder (1) according to one of the preceding claims, wherein the compensating element (50) 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 (1) according to one of the preceding claims, wherein the at least one compensating element (50) comprises 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 (1) according to one of the preceding claims, wherein the compensating element (50) has the shape of a hollow profile or bowl profile and furthermore, two slot nuts (56) are present between the compensating element (50) and the first leg (20), the second leg (30) or the connecting piece (40).

6. The C-shaped tool holder (1) according to one of the preceding claims, wherein the compensating element (50) is releasably fastened to the corresponding one of the legs (20, 30) or the connecting piece (40), preferably by means of screws, pins (54), clamps or clips.

7. The C-shaped tool holder (1) according to one of the preceding claims comprising two compensating elements (50).

8. The C-shaped tool holder (1) according to one of the preceding claims comprising a framework like frame structure (10).

9. The C-shaped tool holder (1) according to one of the preceding claims comprising at the operating end (22) of the first leg (20) a punch (24) with an associated drive unit and at the operating end (32) of the second leg (30) a die dome (30).

10. A setting device with a C-shaped tool holder (1) according to one of the preceding claims, wherein at the operating end (22) of the first leg (20), a punch (24) with an associated drive unit and at the operating end (32) of the second leg (30), a die dome (34) 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 (1).

12. A method for setting an offset difference (Δz) between a first (20) and a second leg (30) of a C-shaped tool holder (1) according to one of the claims 1 to 9, comprising the steps: a. arranging (A) the C-shaped tool holder (1) in a way that a frame plane (R) is aligned perpendicular to gravity, after that, b. determining (B) a first offset of the first leg (20) with respect to the frame plane (R) and c. determining (C) a second offset of the second leg (30) with respect to the frame plane (R), after that, d. fastening (D) at least one compensating element (50) to one or more of the following: the first leg (20), the second leg (30) or the connecting piece (40), and e. minimizing (E) an offset difference (Δz) between the operating end (22) of the first (20) and the operating end (32) of the second leg (30).

13. The method according to claim 12, with the further step: f. setting (F) an intersecting point (S) of a first straight line (G1), which corresponds to a direction of movement of the punch (24) in the direction of the operating end (32) of the second leg (30), and of a second straight line (G2), 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), by means of the at least one compensating element (50) to an operating point.

14. The method according to one of the claims 12 or 13, wherein in cross section, the at least one compensating element (50) comprises 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 step of fastening (D) takes place such that the compensating element (50) is arranged in a way that the second axial geometrical moment of inertia acts perpendicularly to the frame plane (R).

15. The method according to one of the claims 12 to 14, wherein the at least one compensating element (50) is fastened via at least two fastening points to the first leg (20), the second leg (30) or the connecting piece (40).

16. The method according to one of the claims 12 to 15, wherein the at least one compensating element (50) is releasably fastened to the first leg (20), the second leg (30) or the connecting piece (40), preferably by means of screws, pins (54), clamps or clips.

17. The method according to one of the claims 12 to 16, wherein the at least one compensating element (50) has the shape of a hollow profile or a bowl profile and at least two slot nuts (56) are present between the compensating element (50) and the first leg (20), the second leg (30) or the connecting piece (40).

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