Method for Designing a Forming Element for a Forming Tool and a Forming Element Produced by Way of Such a Method

Abstract

A method for designing a first forming element for a forming tool that is intended for forming workpieces is provided. The forming tool includes the first forming element and at least one second forming element. The method includes the steps of: providing first data, characterizing an element geometry of the first forming element; providing second data, characterizing the second forming element; by way of an electronic computing device, carrying out a forming simulation on the basis of the first and second data, where a forming of a workpiece that is brought about by way of the forming elements is simulated by way of the forming simulation and a forming geometry of the workpiece; comparing the forming geometry with a predetermined target geometry; and if a difference determined by the comparison between the forming geometry and the target geometry exceeds a predetermined threshold, changing at least the first data.

Claims

1. A method for designing a first forming element for a forming tool that is intended for forming workpieces and includes the first forming element and at least one second forming element, the method comprising the acts of: (A1) providing first data, which characterize an element geometry of the first forming element; (A2) providing second data, which characterize the second forming element; (A3) by way of an electronic computing device, carrying out a forming simulation on the basis of the first and second data, a forming of a workpiece that is brought about by way of the forming elements being simulated by way of the forming simulation and a forming geometry of the workpiece resulting from the forming simulation being calculated; (A4) comparing the forming geometry with a predetermined target geometry; and (A5) if a difference determined by the comparison between the forming geometry and the target geometry exceeds a predetermined threshold, changing at least the first data.

2. The method according to claim 1, wherein after act A5, acts A1 to A4 are carried out once again, the first data changed in act A5 being used as the first data.

3. The method according to claim 2, wherein after the repetition of acts A1 to A4, act A5 is carried out once again.

4. The method according to claim 1, wherein a difference between a surface of the forming geometry and a surface of the target geometry is used as the predetermined threshold.

5. The method according to claim 3, wherein a difference between a surface of the forming geometry and a surface of the target geometry is used as the predetermined threshold.

6. The method according to claim 1, wherein the target geometry characterizes a visible side and/or a side of the workpiece different from the visible side.

7. The method according to claim 5, wherein the target geometry characterizes a visible side and/or a side of the workpiece different from the visible side.

8. The method according to claim 1, wherein when changing the first data, a surface is locally modified in an area of allowance, so that the target geometry is locally modified.

9. The method according to claim 2, wherein when changing the first data, a surface is locally modified in an area of allowance, so that the target geometry is locally modified.

10. The method according to claim 8, wherein a strip of allowance is added in the local modification.

11. The method according to claim 9, wherein a strip of allowance is added in the local modification.

12. The method according to claim 8, wherein a transitional area, in which the area of allowance and the remaining surface merge with one another, is formed continuously.

13. The method according to claim 10, wherein a transitional area, in which the area of allowance and the remaining surface merge with one another, is formed continuously.

14. The method according to claim 1, wherein a punch is used as the first forming element and a die is used as the second forming element.

15. A forming element for a forming tool, the forming element being produced by way of a method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a schematic sectional representation for a first forming element and a second forming element, and also a workpiece.

[0038] FIG. 2 is a flow diagram to illustrate a method for designing the first forming element.

[0039] FIG. 3 is a schematic sectional representation for the first forming element and the second forming element and also the workpiece, the forming geometry of which deviates from a target geometry.

[0040] FIG. 4 is a schematic sectional representation for the first forming element and the second forming element and also the workpiece, the forming geometry of which corresponds at least substantially to the target geometry.

[0041] FIG. 5 is a further flow diagram to illustrate the method for designing the first forming element in a further embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0042] In the figures, elements that are the same or functionally the same are provided with the same designations.

[0043] FIG. 1 shows in a schematic representation a first forming element 1 and a second forming element 2, and also a workpiece 3. The first forming element 1 and the second forming element 2 are movable in relation to one another, so that the workpiece 3 arranged between the two forming elements 1, 2 and held there is deformable during a relative movement of the two forming elements 1, 2. For example, the first forming element 1 may be a punch of a deep-drawing machine, while the second forming element 2 may be a die of the deep-drawing machine. This means that the first forming element 1 or the punch and the second forming element 2 or the die may be integral parts of a forming tool 4, in particular of the deep-drawing machine.

[0044] In a forming operation, in particular a deep-drawing operation, the workpiece or sheet 3 that is usually held between the two forming elements 1, 2 by way of a workpiece holder or sheet holder is given a shape or geometry that corresponds at least substantially to a geometry or part of the geometry of the second forming element 2. Here, the workpiece 3, which for example is metal and/or comprises plastic, primarily comes into direct contact with the first forming element 1. It is particularly preferred if there is only particularly little direct contact or in particular no direct contact at all between the workpiece 3 and the second forming element 2or at least a concave part of the second forming element 2during a forming operation. This is so because it ensures in a particularly advantageous way that a force with which the two forming elements 1, 2 are moved toward one another does not increase abruptly. This ensures that the forming tool 4 or the deep-drawing machine is subjected to particularly little wear, since mechanical loading of the machine can be kept particularly low in an advantageous way.

[0045] In vehicle construction, in particular in the construction of production motor vehicles, such a forming tool 4 may be used in order to produce particularly easily an outer skin of a motor vehicle comprising more than one outer skin component. There is often the need to give the individual outer skin components at least one bend with a particularly small radius or at least one edge in their free-form surfaces. On the one hand, such edges perform a design function, for example if the edges are respectively formed as a character edge. Such character edges have a decisive influence on an appearance or a design of a motor vehicle and it is desired that these character edges are formed particularly sharply. Apart from that, such edges in free-form surfaces of the outer skin components also perform at least one technical function, for example to direct precipitated water on the outer skin of the motor vehicle along a specific path, so that the precipitated water does not undesirably penetrate into an interior space of the motor vehicle. In addition, these edges give the respective outer skin component a greater resistance to bending, so that the outer skin can be formed particularly stiffly.

[0046] If the workpiece 3 is formed as intended by way of the forming elements, it is provided that a distance between the two forming elements 1, 2 in an end position of the forming tool 4 or of the two forming elements 1, 2 and an original component thickness correspond at least substantially. In FIG. 1, it can be seen outside an area 5 that a thickness reduction with respect to the original component thickness to a component thickness 6 has taken place during the forming or deep drawing of the workpiece 3 as a result of a shaping of the machine tool 4. Correspondingly, the depicted forming elements in FIG. 1 have assumed the end position during the forming of the component or workpiece 3. In the area 5, the decrease of the component thickness is particularly pronounced, since at this point the first forming element 1 or the punch has a radius 7, by way of which the workpiece 3 or the outer skin component is to be provided with an edge. A created radius 8, which extends along a visible component side 9, is much greater because of the component thickness than the radius 7, which is impressed in the workpiece 3 or the outer skin component by way of the first forming element 1. The created radius 8 is also greater here than a concave radius of the second forming element 2 or of the die, which is a result of the already described thinning of the material of the workpiece 3.

[0047] The radius 8 created during the deep drawing or by way of the deep drawing on the visible component side 9 can scarcely be set exactly. This has the consequence that the bend with the particularly small radius or an edge cannot be produced sufficiently accurately or sufficiently in accordance with a design specification in series production of the corresponding outer skin component.

[0048] In order therefore to be able to process the workpiece 3 by way of such forming in such a way that the finished outer skin component has a particularly sharp edge, for example a character edge, there is proposed a method for designing the first forming element 1, in particular for creating a geometry thereof, which is explained more specifically below.

[0049] FIG. 2 shows a flow diagram to illustrate the method. In a first step (or act) S1, an element geometry of the first forming element 1 is provided. Ideally, a first set of geometrical data of the first forming element 1 that can be processed or further processed by way of electronic data processing is available. This set of geometrical data may be formed for example as a CAD data record (CAD: computer-aided design), an FE or FEM mesh (FEM: finite element method, a numerical method for considering the investigation of strength and/or deformation of solid bodies of a geometrically complex form).

[0050] This means that step S1 comprises providing first data, which characterize the element geometry of the first forming element 1.

[0051] A second step (or act) S2 comprises providing second data, which characterize the second forming element 2. For example, an element geometry of the second forming element 2 may be provided as a further, second set of data formed as a set of geometrical data. In other words, the second step S2 may comprise providing second data, characterizing an element geometry of the second forming element 2. In particular, the first step S1 and the second step S2 may proceed simultaneously.

[0052] The first data and the second data are provided for an electronic computing device, for example are entered into this electronic computing device. The electronic computing device may be in particular an electronic data processing unit, for example a computer unit. Further data may be introduced into the forming simulation. These further data may include an original geometry of the component to be formed, a sheet or workpiece holder, data of a material of the workpiece to be formed, process parameters, such as process forces, process kinematics, etc., data of a punch insert and/or die insert, etc. By way of the electronic computing device, in a third step (or act) S3 a forming simulation is carried out on the basis of the first data and the second data. With the aid of the forming simulation, a forming of the workpiece 3 that is brought about during the forming operation by the forming elements 1, 2 is simulated, so that in this way a forming geometry 10 (see FIG. 3) of the workpiece 3 resulting from the forming process is calculated. Such a forming simulation may be performed for example using software, in particular FEM software that is run on the computer unit.

[0053] A fourth step (or act) S4 comprises comparing the forming geometry 10 that is created and provided in step S3 with a predeterminable target geometry 11 (see FIG. 3). The predeterminable target geometry 11 may be a further set of geometrical data, for example a die geometry, a die mesh, a component null geometry, etc., which contains information on the geometry of the outer skin component to be produced. In other words, the target geometry 11 is a preset geometry of the outer skin component that can only be accomplished in the case of the actually produced outer skin component under theoretical-ideal conditions. The target geometry 11 characterizes a visible side of the workpiece 3 or of the outer skin component. To put it another way, the visible component side 9 to be aimed for is modeled when creating or predetermining the target geometry 11, for example by way of CAD. This means that in step S4 a comparison result between the target geometry 11 and the forming geometry 10 created by way of the forming simulation of the outer skin component is produced and provided.

[0054] In a fifth step (or act) S5, the comparison result created in step S4 is evaluated. At least the first data are changed if the comparison result indicates that a difference between the forming geometry 10 and the target geometry 11 exceeds a predeterminable threshold. Such a case is illustrated by way of FIG. 3. Shown there in a schematic representation are the forming elements 1, 2 and also the workpiece 3, the forming geometry 10 of which deviates decisively from the target geometry 11. Accordingly represented in FIG. 3 is a formed workpiece 3, the forming geometry 10 of which is so different from the target geometry 11 that the predeterminable threshold is exceeded. Changing of the first data or of the first set of data of the first forming element 1 should be understood as meaning an adaptation of the element geometry of the first forming element 1 in order when actually producing the outer skin component or when actually forming the workpiece 3 to be able to form the radius 8 in such a way that it corresponds at least substantially to the target geometry 11. Accordingly, after step S5, that is to say after changing the first data, actual production 14 of the first forming element 1 may be continued on the basis of the changed first data.

[0055] If after carrying out step S4 it is alternatively found that the target geometry 11 and the forming geometry 10 closely coincide, in particular are congruent, the method for designing the first forming element 1 may be ended already after the comparison for the first time and the actual production 14 of the first forming element 1 may be continued on the basis of the unchanged first data directly after step S4.

[0056] The method described up to here, in particular for making the forming geometry 10 correspond as exactly as possible to the target geometry 11, is suitable for being carried out once again, in that at least steps S1 to S4 are carried out once again after the fifth step S5, the first data changed in step S5 being used as the first data. Such a rerun of steps S1 to S4 is particularly meaningful especially whenever the difference between the forming geometry 10 and the target geometry 11 previously determined by the comparison has exceeded the predeterminable threshold. In this way, a particularly small difference can be accomplished between the forming geometry 10 and the target geometry 11 in a renewed comparison in the repeated step S4, so that then the predeterminable threshold is not exceeded once again. This rerun is illustrated in FIG. 1 by dashed arrows, which extend from step S5 and lead to the first step S1 or to the second step S2.

[0057] This method may also be carried out iteratively, in that, after the repetition of steps S1 to S4, step S5 is carried out once again. Such an iteration of the method steps S1 to S5 allows the predeterminable threshold to be arranged particularly close to the target geometry. In other words, when the method is carried out iteratively, a particularly exact approximation of the forming geometry 10 to the target geometry 11 is achievable, so that the difference can be particularly small in the comparison in step S4. To put it another way, the method can be carried out iteratively until the predeterminable threshold is no longer exceeded, it being possible for this predeterminable threshold to be aligned particularly closely to the target geometry 11.

[0058] A difference between a surface 12 of the forming geometry 10 and a surface 13 of the target geometry 11 may be used for example as the threshold. In particular, the surface 12 may extend along the visible component side 9 or form it. And a visible component side 9 should be understood as meaning a side of the outer skin component that is facing away from the interior space of the motor vehicle and is facing a viewer located outside the motor vehicle.

[0059] When changing the first data, a surface, in particular a forming surface 15, of the first forming element 1 is locally modified in an area of allowance 16 (see FIG. 4). For example, in order to modify the forming surface 15 locally, a strip of allowance 17 may be added to the element geometry of the first forming element 1, as indicated by means of the dashed arrow in FIG. 5, which shows a further flow diagram to illustrate the method for designing the first forming element in a further embodiment. In this case, a geometry of the strip of allowance 17 or of the local modification becomes an integral part of the element geometry of the first forming element 1. However, it is also contemplated that the element geometry of the first forming element 1 remains unchanged, so that the first data, the second data and geometrical data of the local modification or of the strip of allowance 17 are provided for the electronic computing unit.

[0060] In any event, the first data initially provided in step S1 are changed before they are then provided in step S3. This takes place for example in that data of the local modification, for example dimensions, positional information, etc., of the strip of allowance 17 are added to the data of the element geometry of the first forming element 1, so that the strip of allowance 17 is created in the area of allowance 16. As a consequence, the subsequent forming simulation is based on a virtual first forming element 1, which comprises the strip of allowance 17 or the local modification.

[0061] Shown in a schematic representation in FIG. 4 are the first forming element 1 and the second forming element 2 and also the workpiece 3, the forming geometry 10 of which corresponds at least substantially to the target geometry 11. This means that the local modification or the strip of allowance 17 has had the effect that the workpiece 3 has at least substantially assumed the target geometry 11, in particular in the area 5. In other words, the forming geometry 10 shown in FIG. 4 corresponds at least substantially to the target geometry 11.

[0062] The local modification or the strip of allowance 17 may together with a main forming body 18 form the first forming element 1. In particular, the local modification or the strip of allowance and the main forming body 18 may be formed together as one piece. However, it is also contemplated that the main forming body 18 and the strip of allowance 17 or the local modification are produced separately from one another, in order then to be connected to one another in a frictionally engaging, interlocking and/or material-bonding manner. This would allow for example the provision of a particularly flexibly usable first forming element 1, in the case of which different local modifications or strips of allowance 17 can be applied as and when required. To put it another way, in this case it is avoidable to produce the forming element 1 as a whole once again just when there is a changed strip of allowance 17. Instead, it is possible with particularly little effort to produce only the changed strip of allowance 17 or the changed local modification and to connect it correspondingly to the main forming body 18.

[0063] With a transitional area 19 formed continuously between the local modification or the strip of allowance 17 and the remaining forming surface 15 adjacent thereto and differing therefrom, it is ensured that the workpiece 3 processed or formed by way of the first forming element 1 is not subjected to any spatially particularly confined loading, for example with a notch effect. This is so because then the workpiece would be weakened in certain places and possibly suffer surface defects. The continuousness may take the form of the continuousness of a curvature or the continuousness of a tangent.

[0064] It should be understood that in FIG. 1, FIG. 3 and FIG. 4 a section through an edge or character edge 20 that extends at least substantially perpendicular to the plane of the drawing is depicted.

LIST OF DESIGNATIONS

[0065] 1 first forming element [0066] 2 second forming element [0067] 3 workpiece [0068] 4 forming tool [0069] 5 area [0070] 6 component thickness [0071] 7 radius [0072] 8 radius [0073] 9 visible component side [0074] 10 forming geometry [0075] 11 target geometry [0076] 12 surface [0077] 13 surface [0078] 14 production [0079] 15 forming surface [0080] 16 area of allowance [0081] 17 strip of allowance [0082] 18 main forming body [0083] 19 transitional area [0084] 20 character edge [0085] S1 step [0086] S2 step [0087] S3 step [0088] S4 step [0089] S5 step

[0090] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.