DE102021207020A1 - Process for the production of sheet metal components obtained by forming - Google Patents

Abstract

In the method for producing sheet metal components obtained by forming, in particular deep-drawing, a predetermined path is covered locally in a defined manner on at least one surface of a plate-shaped metallic semi-finished product (1) with at least one conditioning tool (3, 4, 5) and/or a predetermined compressive force is applied to predetermined ones Positions (2.1) or (2.2) are exerted in the pressing direction, so that at these positions of the plate-shaped semi-finished product (1) for a locally defined conditioning (2.3) or (2.4) a local deformation, which is in particular a bending deformation, a locally defined work hardening of the respective semi-finished product material and/or a change in the thickness of the plate-shaped semi-finished product (1) is brought about. The specified positions of the locally defined conditioning, taking into account the locally defined changes in properties to be achieved during forming or loads occurring during operation of the component, are determined by means of the empirical knowledge of experts, by empirical test implementation, by mathematical simulation calculations and/or by virtual forecast models.

Description

The invention relates to a method for producing sheet metal components obtained by forming, in particular deep drawing. In principle, it can be used for the optimized production of deep-drawn components. This is particularly the case for components that have a critical geometry (high degree of deformation during a forming process), have weak points due to local expansion, or multi-stage forming processes have to be carried out to produce them. The areas of application range from the white goods industry to the automotive industry. In the automotive industry, the improvement in crash properties that can be achieved is of particular interest. So the two goals are improved formability during manufacture (Theme A) and more favorable performance properties during use (Theme B).

Regarding topic A: A limitation in deep drawing is the well-known local thinning with the subsequent formation of cracks in certain component areas that are particularly severely deformed during deep drawing. The causes for this are the local loads occurring during the forming process, which exceed the material strength at the point of failure. These loads vary in magnitude locally in the sheet metal and over time during deep-drawing in different areas of the respective component. Likewise, the material properties vary locally and over time, since the sheet thickness decreases or increases during deep-drawing and thus the local load capacity decreases/increases; In both cases, the strain hardening increases and the local load-bearing capacity is increased. If the load exceeds the local material strength, there is a local "weak point". In deep drawing, the complexity of the three-dimensional components and the process stability are limited by these local weak points. That is why there are component geometries that can only be produced one after the other using multi-stage procedures with differently designed tools or cannot be produced at all using sheet metal forming.

On topic B: One limit when using deep-drawn sheet metal components lies in the local properties. The place in the three-dimensional component with the highest load in the life cycle - also referred to as "hotspot" in the following - determines the sheet thickness and material strength of the semi-finished product to be selected. The changes during deep drawing (local change in sheet thickness and strain hardening) must be taken into account and usually lead to the minimum values for sheet thickness and strength in the semi-finished product having to be increased in order to avoid failure in the area of the "weak points" during deep drawing and to to make the "hotspots" resilient to others. However, the possibilities of locally using the strain hardening that occurs during deep drawing and improving the "hotspots" have so far been limited. For example, deforming components are used to absorb forces in vehicle structures during a crash. They are to be designed with regard to their energy absorption over the deformation path. The possibilities of influencing this behavior in a targeted and precise manner in the deep-drawing process are very limited with the possibilities of classic deep-drawing processes.

The simplest solution to the problems described here is the use of more expensive semi-finished products (sheet metal), which have a greater initial sheet thickness and/or better properties; e.g. higher strength and ductility, which increases the intrinsic mass and the costs of the respective components.

Furthermore, circuit boards with variably designed properties over the geometry are already being used in the industrial environment to expand process limits (topic A) or to improve component properties (problem B). These so-called tailored blanks are characterized, for example, by a variable sheet thickness or heat treatment based on the geometry. However, these are subject to process-specific limits with regard to the properties themselves, which can be variably designed, as well as the possible geometric design freedom over the blank used as a semi-finished product. For example, circuit boards with certain required properties cannot be manufactured.

Another well-known solution to the problem is the multi-stage deep drawing of shaped sheet metal parts. If the ability to change shape in the first pull is exhausted, the shaping takes place in the further pull in further individual successive stages. The multi-stage forming process is realized with interlinked individual presses, correspondingly larger presses with several die stages or progressive dies. All solutions are characterized by multiple press and tool technology and are therefore expensive.

To solve these problems, the so-called BiDirectionalDrawing (BDD), as described in DE 10 2008 062 850 B4 has been described, used. The known method is used to expand the process limits. In this case, before the actual deep-drawing process is carried out, the improvement in properties should be introduced locally. The fixtures that are actually present are used for this purpose and tools, which are also used for deep-drawing, are used to bring about deformations in the boundary area between deep-drawing tools and fixing elements for a plate-shaped semi-finished product, which also lead to strain hardening there. Such influences can therefore only occur in areas of a component before the actual deep-drawing process is carried out, which are predetermined by the design and the arrangement of the tools in a deep-drawing system. In addition, the press technology must have kinematics that are hardly available on the market today. This means the integration of complex servo axes in existing systems or new press developments, which are cost-intensive with large forces and strokes.

The local properties in the component can be changed by alternating bending with several tool axes. Only the usual deep-drawing tools are used to create locally defined properties. Accordingly, only the areas in the component that can be reached by the deep-drawing tool during the bending process can be influenced. The locally defined influencing of the properties of a metal sheet is therefore limited, since certain areas of a metal sheet to be deformed are not accessible and therefore also cannot be influenced, since this is not possible with the deep-drawing tools used hitherto.

It is therefore the object of the invention to specify ways of improving the locally defined influencing of the deep-drawing behavior and/or the strength, in particular the strength in hotspot areas, whereby the requirements for the thickness of a plate-shaped semi-finished product used and the basic strength of the respective component material are reduced and thus the Component costs and weight can be reduced.

According to the invention, this object is achieved with a method having the features of claim 1. Advantageous refinements and developments of the invention can be implemented with features identified in the dependent claims.

In the method, at least one conditioning tool is used to cover at least one surface of a plate-shaped metallic semi-finished product in a locally defined manner at predetermined positions and/or to apply a predetermined compressive force in a pressing direction, so that at these positions of the plate-shaped semi-finished product for a locally defined conditioning a local deformation, which is in particular a bending deformation, a locally defined strain hardening of the respective semi-finished material and/or a change in the thickness of the plate-shaped semi-finished product is effected, with the specified positions of the local deformation taking into account the locally defined property changes to be achieved during the deformation or during operation of the Component occurring loads are determined by the experience of experts, by empirical test implementation, by mathematical simulation calculation and / or by virtual forecast models.

Following the locally defined conditioning at the specified positions, the component can be brought into its final shape with one- or multi-stage forming, in particular single or multiple deep-drawing, with the changes in strength and/or thickness that have been achieved. This can be achieved with commonly used forming presses and tools.

At the specified positions, a movement of the at least one conditioning tool with alternating bending stress on the plate-shaped semi-finished product with a specified frequency, number of movements, distances covered during forming and/or respective amplitudes or compressive forces can also be carried out with alternating time-dependent variable path and/or compressive force specifications with the at least one conditioning tool are carried out. When carrying out this bending deformation, a maximum distance of 30 mm, preferably 10 mm, should be covered on the plate-shaped semi-finished product.

The respective predefined path and/or the predefined compressive force on the predefined positions can/can be applied to the at least one surface at the respective predefined positions in such a way that the change in the thickness of the plate-shaped semi-finished product and/or the work hardening is carried out according to a predefined contour will.

Predetermined positions should be determined, which are arranged discretely from one another or form a line of a contour. In this case, linear contours can be formed which at least partially enclose a region of the plate-shaped semi-finished product that is unaffected by the effect of compressive force. This can also be achieved with conditioning tools that have flat surfaces.

The conditioning can advantageously be carried out in such a way that the plate-shaped semi-finished product preferably has a largely flat surface after the locally defined conditioning and before the start of further forming. The maximum deviation in flatness can be the above-mentioned 30 mm.

The conditioning can be carried out in a separate device, the separate device being different from the press used for forming after conditioning. In this case, the separate device can be constructed, constructed and manufactured in a considerably simpler manner than a forming press. It should only make it possible to carry out deformations in a wide variety of positions, which can be selected as flexibly as possible, on a plate-shaped semi-finished product with one or more conditioning tools. This can be achieved, for example, with a corresponding two-dimensional relative movement of the conditioning tool(s) and the plate-shaped semi-finished product. After conditioning, the conditioned semi-finished product can be fully formed in a forming tool in one or more stages.

In the case of a simultaneous, locally defined conditioning along at least one open line and at least one closed contour, at least one conditioning tool can be used that has a three-dimensionally contoured surface in combination with stamping pins that are adapted to the three-dimensionally contoured surface and penetrate through the matrices, or a stamping pin that also penetrates through the matrices has three-dimensional geometry of stamps, so that the plate-shaped semi-finished product at different predetermined positions corresponding to the three-dimensionally contoured surface of the respective die in combination with the stamp pins adapted to the three-dimensionally shaped surface and penetrating through the dies at the corresponding predetermined positions on the stamps or the through the matrices urgent three-dimensional geometry of stamps is deformed by their movement to a range of the corresponding predetermined positions To achieve change in the thickness of the plate-shaped semi-finished product and / or the strength of the semi-finished material.

Partial tools can, however, also be integrated into a press and conditioning can then first be carried out with the press and the partial tools, followed by forming. In this case, the use of a separate device, in which only conditioning is then carried out, can be dispensed with.

Stamp or pin-shaped part tools can be used as the part tool. These should be convexly curved on the surface that is brought into contact with the plate-shaped semi-finished product and have a minimum radius with which the formation of notches on the surface of the semi-finished product can be avoided.

Interlocking conditioning tools can also be used to implement the locally defined conditioning along at least one open polyline and at least one closed contour on a conditioning tool and thus in a movement sequence.

The locally defined conditioning can be carried out along at least one open polyline and/or at least one closed contour with a selectively acting conditioning tool with conditioning carried out several times in succession at discrete positions on the surface of the respective plate-shaped semi-finished product in order to change the thickness in the area of the corresponding predetermined positions of the plate-shaped semi-finished product and/or the strength of the semi-finished product material.

At least one selectively acting conditioning tool in combination with a movement unit and a shelf can also be moved over the plate-shaped semi-finished product to the corresponding discrete positions, or the plate-shaped semi-finished product can be moved with a corresponding movement unit, so that in the area of the corresponding positions along at least one open Polyline and / or at least one closed contour a change in the thickness of the plate-shaped semi-finished product and / or the strength of the semi-finished material is / are achieved.

In any embodiment of the invention, discrete positions may correspond to the predetermined positions. However, this does not necessarily have to be the case if it can be guaranteed that the desired influencing of the thickness of the plate-shaped semi-finished product and/or the strength of the semi-finished product material can be locally defined by the action of a conditioning tool or a sub-tool at the specified positions.

If one or more conditioning tool(s) act only on one surface of a plate-shaped semi-finished product and the surface arranged opposite lies on a flat surface, essentially only its thickness can be changed locally in a defined manner at the specified positions, so that plastic deformation of the semi-finished product Material distribution can be achieved with which certain areas of a plate-shaped semi-finished product have a larger volume of material in a correspondingly limited area, which represents a "material reservoir" for the actual deep-drawing in areas of a semi-finished product. Greater deformation is possible in these areas than in other areas, so that an excessive reduction in material thickness during deep-drawing, which can lead to the formation of cracks, can be avoided.

If there is an alternating compressive force effect, in particular with alternating bending stress at predetermined positions, improved strain hardening can be achieved in the areas of a plate-shaped semi-finished product that are affected in this way before deep-drawing.

As already mentioned, the respective predetermined positions can be determined on the basis of empirical knowledge gained by the personnel who have carried out deep-drawing processes.

However, the positions can also be determined empirically with several tests, in which the effect of specific measures of a locally defined effect of conditioning tools can be taken into account.

A determination by means of simulation calculation can also be achieved alone or in addition to these two procedures. This will be discussed in more detail later.

If alternating bending stress is carried out at the specified positions, this can be carried out with a specified frequency, number and/or amplitude in order to achieve the respectively desired change in thickness and in particular the desired degree of strain hardening.

The respective predefined positions can be determined in such a way that the positions are arranged discretely with respect to one another or form a line of a contour. A line can have areas that are convex and/or concave in relation to a possibly fictitious reference point that is arranged on one side of a contour. If a line encloses an area of the plate-shaped semi-finished product, the centroid can be regarded as a reference point.

A surface area of the respective plate-shaped semi-finished product can be at least partially surrounded by a linear contour. In this case, for example, interruptions can be formed in a linear contour. If conditioning tools act on individual positions that are arranged discretely with respect to one another, punctiform deformations can also be formed following a corresponding contour, which can also be arranged in a line.

The core of the invention is the method for generating local properties on the sheet metal blank (conditioning) and the associated technical implementation. The actual influencing of the variable local properties, in particular sheet thickness and / or strain hardening, is achieved by locally defined forming (preferably alternating bending around a defined geometry ) reached. The locally defined deformation at the specified positions can be achieved by means of alternating relative movements between different tool axes, similar to BiDirectionalDrawing. The difference to this is that the respective plate-shaped semi-finished product can remain almost flat and, before deep-drawing, has approximately the same geometry on the circumference (i.e. little spatial expansion as in multi-stage forming, in which a pronounced three-dimensional geometry is usually already realized in the first stage ) can be met. In addition, areas in which a defined improvement in properties has been achieved can be designed independently of the tool geometry of the respective forming machine, e.g. in a deep-drawing press.

The conditioning of the plate-shaped semi-finished product can take place on the one hand outside the deep-drawing press in a separate machine (conditioning unit). A conditioning unit can be formed with at least one conditioning tool, which can be moved in at least two controllable axes with a short stroke for alternate bending, and has at least one clamping axis. Conditioning units can be positioned, for example, after the press for cutting the outer contour of a plate-shaped semi-finished product or in front of a deep-drawing press and the plate-shaped semi-finished products can be cycled through the stations with a corresponding automation. The plate-shaped semi-finished products can be chosen if required wise pass through several conditioning units or the conditioning tools on a conditioning unit are changed during conditioning.

On the other hand, the local properties can be influenced using a preliminary stage in or on a deep-drawing press. A preliminary stage, which can be arranged in or on the deep-drawing press, should also have two additional controllable axes for alternating bending. Clamping can also be carried out separately in the conditioning unit or using a press ram.

In the following, options for producing the required distribution of properties (conditioning) on the respective sheet-like semi-finished product are described. In principle, two variants of conditioning and the respective technical implementation can be distinguished. The variants essentially differ in terms of their flexibility and the time required for conditioning.

The influencing of the local properties of a plate-shaped semi-finished product can be achieved in different ways, which will be explained below.

Variant 1.1: Conditioning with a flat line-shaped conditioning tool

A flat linear conditioning tool is used to influence the required locally defined properties. In this example, the conditioning tool consists of two die parts and two punch parts. As with BiDirectionalDrawing (BDD method), the plate-shaped semi-finished product is clamped between an upper and lower die and the upper and lower punch, and a relative movement is then carried out between the dies and punches. The local property (thickness of the plate-shaped semi-finished product and/or strain hardening) is influenced in a locally defined manner at the respective contact point by the relative movement.

The difference to the BDD method described in this variant lies in the geometry of the two stamps and the two matrices. Since conditioning should only take place at the predetermined positions, which preferably follow linear contours, a tool geometry without continuous linear contour formation and conditioning can be used, for example.

With this variant, both a separate conditioning unit and a conditioning unit integrated as a preliminary stage in the deep-drawing press can be used.

With the help of this variant, a maximum of one contour can be influenced along a closed polyline. With this variant, the influencing of further contours can only be influenced by means of a second conditioning tool in a second conditioning unit or a further conditioning stage in a deep-drawing tool. These deficits can be compensated for using variant 1.2 described below.

Variant 1.2: Conditioning with (conditioning) near-contour conditioning tool

This variant basically works the same as variant 1.1. The only difference lies in the conditioning tool geometry. The conditioning tool according to variant 1.1 is limited to the conditioning of a property along a maximum of one closed polyline (contour). With this variant, the required property(s) can be influenced at several positions at the same time. This solution assumes a three-dimensional geometry of the conditioning tool (see 3 ) ahead. The stamp pins above/below grip through bores through the respective die geometry. The plate-shaped semi-finished product can thus be clamped between the sheet metal holders and the stamp of the conditioning tool (see variant 1.1). Subsequently, the stamp, for example, performs an alternating movement in two directions of an axis. The dies hold the plate-shaped semi-finished product clamped.

Alternating bending around the three-dimensional geometry of the conditioning tool can also be used to influence locally defined properties that contain, for example, two closed polylines of a contour using a conditioning tool. The conditioning tool can in turn be used either in a conditioning unit outside of the deep-drawing tool or as a preliminary stage in the deep-drawing tool.

Variant 2: Flexible conditioning

This variant is characterized by a geometrically very flexible conditioning outside of a forming tool. In this variant, a conditioning unit consists of a conditioning tool, an additional option for positioning the conditioning tool, for example implemented with tripods, and a stationary support. The tripods position the conditioning tools (above/below) mainly in the x and y plane over the surface of a plate-shaped semi-finished product in relation to specified positions and the respective required property is locally defined and influenced by alternating bending stress at the respective positions ( 4 ). There is also the possibility of inverting the system so that the plate-shaped semi-finished product is moved and the respective conditioning tool is held in a fixed position.

With the help of a conditioning unit described in this way, it is possible to influence at least one property with a different amount in a locally defined manner at different positions of a plate-shaped semi-finished product. The conditioning tool used for this consists, like the conditioning tools that can be used in variants 1.1 and 1.2, of two punch and two die components. The geometric flexibility of the process can be achieved through the "punctiform" design of the tool contact surfaces.

To influence the required properties, for example, the plate-shaped semi-finished product or the respective conditioning tool would be positioned at all positions marked with a cross (see 5 ) in order to influence the locally defined desired property(s) accordingly.

The properties of the almost flat, plate-shaped semi-finished products can be adapted locally and precisely defined for the respective sheet metal component to be produced by forming/deep drawing and the associated material. This means that the process limits can be expanded or the properties of the component can be set in a targeted, locally defined manner.

Possible procedures for determining predetermined positions for influencing at least one property of a deep-drawn sheet metal component are to be discussed in more detail below.

The aim of the invention is to design the local properties of a blank as a semi-finished product before forming/deep-drawing. The starting point is the property requirement either for the forming process - topic A - or for the finished component - topic B. The calculation of the areas with adapted properties is derived from the numerical simulation of deep drawing (A) or the component loads in use (B).

Various conditioning parameters have to be determined during process development: • General: shape of the contact surfaces of the conditioning tool • Number, amplitude and frequency of alternating bending for conditioning • Clamping force between the upper and lower die elements for conditioning • (General: Time courses of path and force of the components of a conditioning unit that move relative to each other for the conditioning)

1. 1. Initiale Definition der lokalen Eigenschaften innerhalb der Außenkontur eines plattenförmigen Halbzeugs (Konditionierung)
2. 2. Durchführung einer Prozesssimulation (Tiefziehen) mit plattenförmigem Halbzeug mit lokalen Eigenschaften (Thema A)
3. 3. Durchführung einer Simulation der Bauteillasten im Gebrauch des Blechbauteils (Thema B)
4. 4. Ermittlung der Zielgrößen aus den Ergebnissen der Simulation (Thema A) oder (Thema B)
5. 5. Abgleich mit vorgegebenen Zielgrößen
6. 6. Anpassung der lokalen Eigenschaften innerhalb der Außenkontur eines plattenförmigen Halbzeugs (Konditionierung) auf Basis von Schritt 5
7. 7. Wiederholung von Schritt 2 bis 6 bis vorgegebene Zielgröße oder ein Abbruchkriterium erreicht ist

In principle, the same procedure can be followed when carrying out all process variants. Initial local properties are defined on the respective plate-shaped semi-finished product, a target criterion based on the elastic-plastic simulation of deep drawing (A) or the simulation of the component loads to be considered in use (B) is defined and an optimization is carried out until the target criterion in influencing the respective property(s) has been achieved. The steps for calculating the property requirements can be broken down as follows (Step 3 is only carried out in the case of topic (B) if a load occurring during operation of a formed or deep-drawn sheet metal component is also to be taken into account):

1. 1. Initial definition of the local properties within the outer contour of a plate-shaped semi-finished product (conditioning)
2. 2. Carrying out a process simulation (deep drawing) with plate-shaped semi-finished products with local properties (topic A)
3. 3. Performing a simulation of the part loads in use of the sheet metal part (Topic B)
4. 4. Determination of the target values from the results of the simulation (topic A) or (topic B)
5. 5. Comparison with specified target values
6. 6. Adaptation of the local properties within the outer contour of a plate-shaped semi-finished product (conditioning) based on step 5
7. 7. Repeat steps 2 to 6 until the specified target value or a termination criterion is reached

For example, to solve topic A, the minimum sheet thickness after deep-drawing can be defined as a target value locally, in the area of a hotspot, or globally on the entire sheet metal component. For example, strain hardening on the plate-shaped semi-finished product can be defined as a local property. The location and amount of the property distribution on the plate-shaped semi-finished product are adjusted during optimization until the target value on the sheet metal component is met. Proceed in the same way to solve topic B. However, local or global target values are specified with regard to the reaction to the expected operating load. For example, this can be the deformation or the stress distribution in the sheet metal part.

The conditioning parameters for setting the locally defined properties can be determined, for example, using a numerical simulation calculation of the conditioning process and an optimization loop. The result of the elastic-plastic simulation reflects the required properties on the plate-shaped semi-finished product. In an optimization, the conditioning parameters are adjusted until the required locally defined property has been achieved with certain goals, such as the shortest process time.

To determine the property requirement, the definition of the local property(s) on the panel-shaped semi-finished product is crucial. In principle, the discretization (9) used for process simulation of the plate-shaped semi-finished product with finite elements (FE) can be used to determine the locally defined properties ( 6 ).

1. 1. Die Anzahl an zu bestimmenden Parametern wächst mit der Anzahl der Elemente (pro Element wird ein Parameter benötigt). Die Diskretisierung kleiner Blechbauteile mit geringer Komplexität kann bereits mehrere tausend Elemente umfassen und führt dementsprechend auf Optimierungsprobleme mit einer hohen Anzahl an Parametern.
2. 2. Das Ergebnis der Berechnung des Eigenschaftsbedarfs kann Unstetigkeiten der Eigenschaft und lokal hohe Gradienten hinsichtlich der Eigenschaft des plattenförmigen Halbzeugs aufweisen. Es können sich zum Beispiel zwei benachbarte Elemente im Betrag der jeweiligen Eigenschaft maximal unterscheiden. Dieser Zustand ist nicht nur meist physikalisch inkorrekt, sondern auch in der Realität nicht realisierbar, da hinsichtlich der Lokalität Grenzen gesetzt sind.

The simplest way of defining the respective property is to assign the amount of the property to be determined to each element on the panel-shaped semi-finished product. However, this method has two disadvantages:

1. 1. The number of parameters to be determined increases with the number of elements (one parameter is required per element). The discretization of small sheet metal components with low complexity can already include several thousand elements and accordingly leads to optimization problems with a large number of parameters.
2. 2. The result of the calculation of the property requirement can show discontinuities in the property and locally high gradients with regard to the property of the sheet-like semi-finished product. For example, two adjacent elements can differ at most in the amount of the respective property. This state is not only physically incorrect in most cases, but also cannot be realized in reality, since there are limits with regard to locality.

A possibility to qualitatively describe the local properties (f(x,y)) on the plate-shaped semi-finished product is a sum of n radial basis functions (RBF) kernels: $$ƒ\left(x,y\right)=〉w_i\text{ex}\left(g_{x,i}{\left(x-x_{a,i}\right)}^2+g_{y,i}{\left(y-y_{a,i}\right)}^2\right)$$

Starting from its center (P _i (x _σ,i |y _σ,i )), an RBF nucleus decays in the x and y directions. The local area of influence on the property in the x and y direction of the respective core can be influenced with the parameters y _x,i and y _ψ,i

For the global description of the respective local property on the plate-shaped semi-finished product, for example, n RBF cores, defined via the respective centers 10, can be distributed within the outer contour of the plate-shaped semi-finished product at regular intervals (see 9 ) will.

Then, during the optimization, the n weights (w _i ) can be determined for each of the n cores. Thus, the respective property for all (finite) elements 9 for the (FEM) simulation can be described with π parameters in a locally defined manner and the number of parameters can be significantly reduced.

• • Form der Kontaktflächen
• • Koordinaten (x_K und y_K) 8 der jeweiligen vorgegebenen Positionen pro Konditioniervorgang
• • Anzahl, Amplitude und Frequenz der Wechselbiegungen pro Konditioniervorgang an bzw. im Bereich der jeweiligen vorgegebenen Positionen
• • Klemmkraft zwischen den oberen und unteren Konditionierwerkzeugelementen pro Konditioniervorgang
• • (Allgemein: Zeitliche Verläufe von Weg und Druckkraft der sich relativ zueinander bewegenden Komponenten pro Konditioniervorgang)

The conditioning parameters for variant 2 are made up as follows:

• • Shape of the contact surfaces
• • Coordinates (x _K and y _K ) 8 of the respective predetermined positions per conditioning process
• • Number, amplitude and frequency of the alternating bends per conditioning process at or in the area of the respective specified positions
• • Clamping force between the upper and lower conditioning tool elements per conditioning operation
• • (General: Temporal courses of path and compressive force of the components moving relative to each other per conditioning process)

Basically, sharp transitions in the properties to be adjusted should be avoided to ensure formability and avoid cracking. Accordingly, convex surfaces of the contact areas, such as a hemispherical shape, are ideal for influencing the property(s). In principle, however, the surface of the contact surface(s) of a conditioning tool can have any shape.

All centers of the RBF cores that have a weight w _i > a defined limit value (ε) are used for the coordinates of the respective predetermined positions of the conditioning processes. The remaining conditioning parameters can be calculated using an elastic-plastic simulation of the conditioning process. The result of the simulation represents the required property. In an optimization, the conditioning parameters can be adjusted until the required locally defined property has been achieved with certain goals, eg the shortest process time.

The conditioning tool can then be positioned in relation to the respective predetermined position and the desired property can be set with the determined conditioning parameters until the required conditioning is achieved on a contour.

The figures are intended to illustrate options for carrying out the method by way of example. Features can be combined with each other independently of the respective example or representation.

• 1 ein Beispiel eines plattenförmigen Halbzeugs, bei dem an vorgegebenen Positionen eine Beeinflussung einer lokalen Eigenschaft erfolgt ist;
• 2a ein Beispiel eines plattenförmigen Halbzeugs mit einem entsprechend an Aktivflächen konturierten ebenen Konditionierwerkzeug;
• 2b eine Schnittdarstellung eines Beispiels eines plattenförmigen Halbzeugs mit einem entsprechend an Aktivflächen konturierten ebenen Konditionierwerkzeug;
• 3a ein Beispiel eines plattenförmigen Halbzeugs mit einem entsprechend an Aktivflächen dreidimensional konturierten Konditionierwerkzeug;
• 3b eine Schnittdarstellung eines Beispiels eines plattenförmigen Halbzeugs mit einem endsprechend an Aktivflächen dreidimensional konturierten Konditionierwerkzeug;
• 3c eine dreidimensionale Darstellung der unteren Hälfte eines dreidimensional konturierten Konditionierwerkzeugs;
• 4 eine schematische Darstellung eines Tripods und Schnittdarstellung eines Beispiels eines plattenförmigen Halbzeugs mit einem punktuell wirksamen Konditionierungswerkzeug;
• 5 ein Beispiel eines plattenförmigen Halbzeugs mit vorgegebenen Positionen einer lokalen Eigenschaft und Positionen zur Konditionierung eines plattenförmigen Halbzeugs nach Variante 2;
• 6 ein Beispiel eines plattenförmigen Halbzeugs mit vorgegebenen Positionen einer lokalen Eigenschaft mit schematischer, beispielhafter Darstellung einer für die FE erzeugten Diskretisierung und beispielhafter Positionen von RBF-Zentren.

show:

• 1 an example of a plate-shaped semi-finished product in which an influencing of a local property has taken place at predetermined positions;
• 2a an example of a plate-shaped semi-finished product with a planar conditioning tool contoured accordingly on active surfaces;
• 2 B a sectional view of an example of a plate-shaped semi-finished product with a planar conditioning tool contoured accordingly on active surfaces;
• 3a an example of a plate-shaped semi-finished product with a three-dimensionally contoured conditioning tool corresponding to active surfaces;
• 3b a sectional view of an example of a plate-shaped semi-finished product with a conditioning tool correspondingly three-dimensionally contoured on active surfaces;
• 3c a three-dimensional representation of the lower half of a three-dimensional contoured conditioning tool;
• 4 a schematic representation of a tripod and sectional representation of an example of a plate-shaped semi-finished product with a selectively effective conditioning tool;
• 5 an example of a plate-shaped semi-finished product with predetermined positions of a local property and positions for conditioning a plate-shaped semi-finished product according to variant 2;
• 6 an example of a plate-shaped semi-finished product with predetermined positions of a local property with a schematic, exemplary representation of a discretization generated for the FE and exemplary positions of RBF centers.

In 1 an example of a plate-shaped semi-finished product 1 is shown, in which an influencing (conditioning) of at least one desired property corresponding to a contour 2.3 and 2.4 has been carried out at predetermined positions 2.1 and 2.2. Areas of the plate-shaped semi-finished product 1 that follow a contour 2.1 and 2.2 are to be influenced by means of the effect of compressive force and by paths covered with conditioning tools during alternating bending. how 1 As can be seen, different surface areas with different contours 2.1 and 2.2 can be influenced in order to take into account the conditions during the deep-drawing process and/or the loads to be expected locally on a finished sheet metal component. The contour 2.3 or 2.4 formed in each case has a transition area at its edges. The contour 2.1 is a contour formed along at least one open polyline, and the contour 2.2 is a closed contour around a surface area.

In the 2a and 2 B shows schematically how the stamps 3.1 and 3.2 can act as part of a conditioning tool 3 (cf. variant 1.1) on a surface of a plate-shaped semi-finished product 1 in order to achieve a desired property change at predetermined positions. The plate-shaped semi-finished product 1 is fixed at its outer edges by means of two matrices 3.3 and 3.4 of a conditioning tool 3 and can be influenced locally in a defined manner with the area arranged in between by means of compressive force and movement of one or more stamp(s) 3.1 and/or 3.3 be deformed.

That in the 3a until 3c The conditioning tool shown (cf. Variant 1.2) is constructed in such a way that a plate-shaped semi-finished product 1 is held fixed between one of the stamp pins 4.5 in the stamps 4.1 and 4.2. The locally defined influence can be achieved using the three-dimensionally contoured surfaces 4.6 of the matrices 4.3 and 4.4 in combination with the stamp pins 4.5 integrated into the stamps 4.1 and 4.2. The pin-shaped partial tools 4.5 can be moved together by moving the respective punch 4.1 or 4.2 in the direction of a surface of the plate-shaped semi-finished product 1 and in the opposite direction thereto. The pin-shaped stamping pins 4.5 as a type of sub-tool are arranged in relation to one another, to the three-dimensional surface contour of the matrices 4.3 and 4.4 and in relation to the surface of the plate-shaped semi-finished product 1 that deformations can be carried out at or in the area of predetermined positions. The height profiles of the three-dimensional surface contouring 4.6 can be different in order to be able to achieve different deformations. The pin-shaped sub-tools 4.5 have a constant length, with which the same path can then be covered during conditioning.

In 4 shows a conditioning unit with a conditioning tool (cf. variant 2) and an exemplary movement unit 7 with a tripod for moving the conditioning tool over the plate-shaped semi-finished product 1, in which a plate-shaped semi-finished product 1 rests on a support 6 and between two stamps 5.1 and 5.2 and two Matrices 5.3 and 5.4 is arranged. The conditioning tool 5, consisting of the punches 5.1 and 5.2 and the dies 5.3 and 5.4, is each supported on a tripod and can be moved over the plate-shaped semi-finished product 1 in order to exert alternating bending stress or for a locally defined deformation in order to apply corresponding compressive forces to the respective surface of the plate-shaped semi-finished product 1 to be able to exercise.

The conditioning tool, between which the plate-shaped semi-finished product 1 is arranged, is formed with two punches 5.1 and 5.2, which are arranged between two dies 5.3 and 5.4. The stamps 5.1 and 5.2 each have a three-dimensionally shaped surface that is convex in the direction of the plate-shaped semi-finished product 1 as an active surface, with which compressive forces can be exerted on the respective surface of the plate-shaped semi-finished product 1.

In 5 an example of a plate-shaped semi-finished product 1 is shown, in which a local property is to be generated at predetermined positions 2.1 and 2.2. The positions 8 are those points at which the conditioning tool 5 can be positioned according to variant 2 in order to deform the plate-shaped semi-finished product 1 locally by means of the effect of pressure and movement of the punches 5.1 and 5.2 and dies 5.3 and 5.4.

In 6 is intended to clarify how a surface of a plate-shaped semi-finished product 1 can be divided into individual discrete elements 9 for carrying out an FEM calculation in order to determine predetermined positions for changing local properties. An alternative to this is shown by the centers of the RBF cores 10 on the surface of a plate-shaped semi-finished product 1, which can be defined in a two-dimensional equidistant pattern, for example, in order to be able to determine predetermined positions at which a specific influencing is to be carried out before deep-drawing.

With conditioning tools like those in the 2 until 4 are shown, a plate-shaped semi-finished product 1 can be processed as shown in 1 is shown. In this case, the contours 2.3 and/or 2.4 can also be formed by selective compressive force action. The active surfaces of stamps 5.1 and 5.2 act on the surface of the plate-shaped semi-finished product 1 discretely from one another but in a line arrangement, as is shown with the cross representations at discrete positions 8 in 5 is illustrated.

Reference List

1

plate-shaped semi-finished product

2.1

predetermined position

2.2

predetermined position

2.3

contour

2.4

contour

3

Conditioning tool according to variant 1.1 consisting of at least:

3.1

Rubber stamp

3.2

Rubber stamp

3.3

die

3.4

die

4

Conditioning tool according to variant 1.2 consisting of at least:

4.1

Rubber stamp

4.2

Rubber stamp

4.3

die

4.4

die

4.5

stamp pen

4.6

surface contouring

5

Conditioning tool according to variant 2 consisting of at least:

5.1

Rubber stamp

5.2

Rubber stamp

5.3

die

5.4

die

6

edition

7

movement unit

8th

discreet position

9

discrete element

10

Center RBF core

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102008062850 B4 [0007]

Claims (13)

Process for the production of sheet metal components obtained by forming, in particular deep drawing, in which on at least one surface of a plate-shaped metallic semi-finished product (1) a predetermined path is covered locally in a defined manner with at least one conditioning tool (3) and/or a predetermined compressive force is exerted at predetermined positions (2.1) or (2.2) in the pressing direction, so that at these positions of the plate-shaped semi-finished product (1) for a locally defined conditioning (2.3) or (2.4) a local deformation, which is in particular a bending deformation, causes a locally defined strain hardening of the respective semi-finished product material and/or a change in the thickness of the plate-shaped semi-finished product (1); in which the specified positions of the locally defined conditioning, taking into account the locally defined property changes to be achieved during forming or the loads occurring during operation of the component, are determined by means of the empirical knowledge of experts, by empirical test implementation, by mathematical simulation calculations and/or by virtual forecast models. procedure after claim 1 , characterized in that following the locally defined conditioning at the specified positions with the changes in strength and/or thickness achieved, the component is brought into its final shape with one- or multi-stage forming, in particular one or multiple deep-drawing. Method according to one of the preceding claims, characterized in that at the predetermined positions (2.1) or (2.2) with flat stamps (3.1) and (3.2) and/or flat matrices (3.3) and (3.4) of at least one conditioning tool (3 ) a movement with alternating bending stress of the plate-shaped semi-finished product (1), preferably with alternating time-dependent variable path and/or compressive force specifications is carried out. Method according to one of the preceding claims, characterized in that the predetermined path and/or the predetermined compressive force is applied to the at least one surface at the respective predetermined positions in such a way that the change in the thickness of the plate-shaped semi-finished product (1) and/or the strain hardening is carried out according to a predetermined contour (2.1) or (2.2). Method according to one of the preceding claims, characterized in that predetermined positions are determined which are arranged discretely in relation to one another or form a line of a contour (2.4). Method according to the preceding claim, characterized in that linear contours (2.3) or (2.4) are formed by means of conditioning tools (3) with a flat surface, which at least partially enclose a region of the plate-shaped semi-finished product (1) unaffected by the effect of compressive force. Method according to one of the preceding claims, characterized in that the conditioning is carried out in such a way that the plate-shaped semi-finished product (1) following the locally defined conditioning and before the start of further forming at least one largely flat surface, except for surface areas in which only one change in the thickness of the plate-shaped semi-finished product (1) has been achieved with the conditioning. Method according to one of the preceding claims, characterized in that the conditioning is carried out in a separate device, the separate device being different from the press which is used for forming after the conditioning. Method according to one of the preceding claims, characterized in that with a simultaneous locally defined conditioning along at least one open polyline (2.1) and at least one closed contour (2.2) at least one conditioning tool (4) is used which has a three-dimensionally contoured surface (4.6) of the matrices (4.3) or (4.4) in combination with stamping pins (4.5) adapted to the three-dimensionally contoured surface or a three-dimensional geometry of the stamps (4.1) and (4.2) also penetrating through the matrices (4.3) or (4.4), so that the plate-shaped semi-finished product (1) at different predetermined positions corresponding to the three-dimensionally contoured surface of the die (4.3) and (4.4) in combination with the three-dimensional nal shaped surface adapted stamp pins (4.5) at the corresponding predetermined positions on the stamps (4.1) and (4.2) or the three-dimensional geometry of the stamps (4.1) and (4.2) predetermined by the matrices (4.3) or (4.4) at their in Surfaces pointing in the direction of the plate-shaped semi-finished product (1) are deformed by their movement in order to achieve a change in the thickness of the plate-shaped semi-finished product (1) and/or the strength of the semi-finished product in the area of the corresponding predetermined positions. Method according to one of the two preceding claims, characterized in that tool parts are integrated into a press and conditioning is carried out first with the press and the tool parts and then forming is carried out. Method according to one of the two preceding claims, characterized in that interlocking tools are used to implement the locally defined conditioning along at least one open polyline (2.1) and at least one closed contour (2.2) on a conditioning tool (4) and thus in a movement sequence. Method according to one of the preceding claims, characterized in that the locally defined conditioning along at least one open line (2.1) and/or at least one closed contour (2.2) with at least one selectively acting conditioning tool (5) with conditioning carried out several times in succession at discrete positions (8) the surface of the respective plate-shaped semi-finished product (1) is carried out, so that a change in the thickness of the plate-shaped semi-finished product (1) and/or the strength of the semi-finished product material is/are achieved in the area of the corresponding predetermined positions. Method according to the preceding claim, characterized in that the conditioning tool(s) (5), which acts selectively, in combination with a moving unit (7) and a shelf (6) via the plate-shaped semi-finished product (1) to the corresponding discrete positions (8) is/are moved or the panel-shaped semi-finished product (1) is moved with a corresponding movement unit (7) so that in the area of the corresponding discretely arranged positions (8) along at least one open polyline (2.1) and/or at least a closed contour (2.2) a change in the thickness of the plate-shaped semi-finished product (1) and/or the strength of the semi-finished product material is/are achieved.

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