EP1186358A2 - Process and platelet for the production of a cold worked workpiece out of plate and use of a platelet - Google Patents

Abstract

A blank is produced from a base sheet of a first steel material. A section of the base sheet is replaced by a sheet metal blank (1,2), which has different thickness and/or material characteristics from the first base sheet. Thickness, geometry of the blank, and its position in the blank are determined by the material flow during subsequent cold forming of the blank into a component, e.g. a tube (R).

Description

The invention relates to a method and a circuit board for Manufacture of a component from sheet steel Cold forming and the use of a blank.

Usually used in the manufacture of components First of all, flat sheet metal blanks made of sheet steel manufactured, then in one or more Cold forming steps get their final shape. there become larger, especially from larger, from a single Manufactured components the thickness and the Properties of the steel material used by the Determines the area of the component in practical operation is exposed to the highest loads.

In practice it can be seen that the cold deformation of Steel sheets, for example, then cause difficulties leads when the component to be produced with a view on the deformation processes has a complex shape or the steel sheet admittedly its mechanical Resilience requirements met, but at the same time due to its material properties is difficult to deform. In addition, the deformation of a steel sheet by which with regard to its Required thickness can be difficult.

For example, in the manufacture of pipes that have an arcuate course, often not be prevented that on the one hand in the area of Excess of the outer curve of the respective pipe bend Material thinning and consequently to cracks and on the other hand, folds on the inner arch of the curvature due to excessive material accumulation. The There is a risk of wrinkling during bending reduced the use of special mandrels become. In addition, by actively pushing of the tube during the bending process Wall thickness reduction in the area of the outer arch in the limited dimensions are affected. Take both measures however, a high level of equipment is required.

Another example of components with regard to Cold forming are complex, difficult to control form deep-drawn bowls that have a square base. To prevent such deep-drawn parts from in the course of deep drawing for wrinkling in the area of Corners are targeted at the deep-drawing tool Brake beads introduced that are excessive Impede material flow. In other places where one Flow of the material to a greater extent is required the thermoforming tool is lubricated to at that location the friction between the material and the steel sheet decrease. The associated with these measures Effort is also substantial and contributes certain materials not to success.

Due to the material properties of the used Steel material caused problems with the Cold forming occurs, for example, in that Materials of a greater thickness or a special one high strength must be used to attach to the to meet the respective component requirements. Steel sheets obtained in this way can often be used bad or not at all due to cold forming in the bring the desired shape.

According to a method known from EP 0 906 799 A1 are on one for the manufacture of deep-drawn Body components certain board in certain Areas sheet metal blanks on a base plate welded. Through the welded sheet metal blanks the board is reinforced so that it comes out of the board manufactured component the put on this part mechanical requirements safely met. Around ensure that even the welded on Sheet metal cuts have sufficient ductility own, are on the surface of the sheet metal blanks Material accumulations formed.

The method known from EP 0 906 799 A1 enables it is to produce components that are reduced Weight have a high mechanical strength. In practice shows, however, that the deformation is such reinforced boards despite the special design of the reinforcement plate is difficult. this applies especially when the base plate is already on which the reinforcement plate is welded on, bad Has forming properties.

The object of the invention is based on the above-described prior art To create procedures which have an improved result cold forming or manufacturing makes certain component shapes possible in the first place.

Likewise, boards are to be created, one have improved formability. After all, should advantageous uses of such boards specified become.

• Erzeugen einer Platine aus einem ersten Grundblech, das aus einem ersten Stahlmaterial besteht;
• Ersetzen mindestens eines Abschnitts des Grundblechs durch einen Blechzuschnitt, welcher sich in seiner Dicke oder mindestens einer Materialeigenschaft von dem ersten Stahlblech unterscheidet, wobei die Dicke und / oder die abweichende Materialeigenschaft und die Geometrie des Blechzuschnitts sowie dessen Lage in der Platine bestimmt sind vom Materialfluß während der anschließend durchgeführten Kaltumformung;
• Kaltumformen der Platine zu dem Bauteil.

According to the invention, a method for producing cold-formed components from sheet steel that achieves the above-mentioned object comprises the following steps:

• Producing a circuit board from a first base plate made of a first steel material;
• Replacing at least a section of the base plate with a sheet metal blank which differs in thickness or at least one material property from the first steel sheet, the thickness and / or the different material property and the geometry of the sheet metal blank and its position in the board being determined by the material flow during the subsequent cold forming;
• Cold forming the board to the component.

Regarding a sheet steel plate for the The production of a component by cold forming The above object is achieved in that the relevant board comprises a base plate in which at least one section through a sheet metal blank is replaced by one in terms of its thickness and / or at least one material property of the Base plate of the board differentiating steel material is made, the geometry that Material properties, the thickness and / or the location of the Sheet metal cut through the during the cold forming of the Board incoming material flow are determined.

According to the invention, unlike in the beginning mentioned prior art, the location, shape and / or Material properties of the used in the board Sheet metal cutting not determined by the requirements, which in practical operation to that from the board generated component are made, but it is the im Material flow occurring during cold forming considered. It has surprisingly been found that itself through the targeted provided according to the invention Placement of sheet metal blanks in places where it in the course of cold forming to critical or insufficient material flows, produce components can be, which in the conventional way by a Did not allow cold forming.

According to the invention, the sheet metal blanks are for example placed in the board so that a Deformation reserve specifically available in the areas where there is a particularly high flow of Material is coming. Likewise, according to the invention Areas that are compressed during cold forming, see above be interpreted that material accumulations without the risk of wrinkles. In addition, it is at procedure according to the invention possible, sheet metal blanks in the board to place that targeted deformations be enforced by direct action of the tool used for shaping not reached can be.

The invention can also be used in such an advantageous manner Use cases where a circuit board comes from one difficult to deform but in terms of its mechanical properties optimal steel sheet for Production of a component is to be used. By the targeted placement of Sheet metal cuts in the areas on the deformation circuit boards can also have a significant influence difficult to deform sheet metal materials in complex shapes bring.

Due to the arrangement of the sheet metal blanks according to the invention in the base plate of the board can be different Forming errors can be counteracted in a targeted manner. This are in particular local overloads of the material, the non-onset of deformation due to local limited below the yield point of the material Tensions at the beginning of the forming process as well as the Cancellation of deformation due to a sudden Falling below the yield point during the Forming process. The invention thus provides a method available, which is safe manufacture too complex components. Furthermore it is due to the targeted placement of the sheet metal blanks possible, cold-formed components also with inclusion of materials that are difficult to manufacture or do not let it deform at all.

The required material properties, the thickness, the Geometry and / or the location of each Sheet metal cutting in the board can be done easily Determine the way in a first step one only sample board consisting of a base plate into the mold of the component to be manufactured, then on the the areas created from the component circuit board are found in which it is one of the Deformation that does not meet the requirements, and finally the insufficiently deformed areas a tracing of the forming process to those Areas of the sample board are assigned, in which the sheet metal blanks are to be used. Based on the results obtained on the sample board can Methods used according to the invention can Boards according to the invention in large quantities getting produced. Elaborate practical tests can thereby be avoided in that the deformation of the Sample board to the component, the finding of the Areas of insufficient deformation and traceability of the forming process as a simulation calculation after the Finite element method can be performed.

An alternative, supported by practical tests Possibility of determining the for the interpretation of the Sheet metal blanks required information is that the Provide the surface of the sample board with halftone dots is that then the pattern board to the component is deformed that when determining the insufficient deformed areas of the pattern board the halftone dots be determined in the insufficiently deformed Ranges lie, and that by comparing the Location of these grid points on the component with the location of the relevant halftone dots on the undeformed Sample board of the forming process traced and those areas of the pattern board are determined in which sheet metal blanks are to be used. The Assignment of the position of the grid points of the component to the The location of the grid points on the undeformed component can naturally computer-assisted.

Targeted deformation in the course of cold forming the circuit board at a certain point or a build-up of material to prevent wrinkles can be suppressed, this can be done according to the invention Procedure can be achieved in that the Cut sheet metal based on its position in the board has less formability than the surrounding Sheet material of the board. Such a and Sheet metal blank positioned in the board is impeded the material flow and in this way contributes to a directional deformation of the board.

In other cases, it is beneficial if the sheet metal blank a higher one in relation to its position in the circuit board Forming capacity as the surrounding material Circuit board. For example, such Places where there is cold forming too particularly strong flow of material comes targeted Prevent thinning. The danger of the emergence of Cracks are effectively suppressed in this way. In this context, it is particularly advantageous if the thickness of the sheet metal blank after cold forming in is essentially equal to the sheet thickness of the board. at this embodiment of the invention, the thickness and Material property of each in the board used sheet metal blank selected so that from the Board-shaped component has a uniform exterior Owns appearance.

Depending on the type of component that consists of a circuit board according to the invention is made, it is expedient if in the area which during the Cold forming essentially through tensile stresses is claimed, a sheet metal blank is arranged, whose thickness is greater than the thickness of the surrounding Steel sheet of the board. For example at the Production of curved tubes can be done by Arrangement of such a sheet metal blank on later outer arch the formation of cracks and to avoid large wall thinning. For the same purpose can in the area that during cold forming in is significantly stressed by tensile stress Sheet cut to be arranged, its yield point is higher than the yield point of the surrounding Steel sheet of the board.

Are used during cold forming in certain areas the board essentially compressive stresses caused so that there is a compression of material occurs, it is beneficial if one in this area Sheet metal blank is arranged, the yield point is lower than the yield point of the surrounding Steel sheet of the board. It is also supportive sheet metal blank used in the area concerned, whose thickness is less than the thickness of it surrounding steel sheet of the board.

The two configurations given above are favorable in those cases where the risk of Wrinkling in the compressed area at the Cold deformation is low or controlled. Is not this the case, the formation of wrinkles in the through Areas subjected to compressive stress be suppressed that in the areas concerned Sheet metal blank is arranged, the thickness of which is greater than the thickness of the steel sheet surrounding the board. Such a sheet metal blank prevents Throwing up the compressed sheet material effective. Especially when combining one Sheet metal cut with one in the area of the later Sheet metal sheet inserted in the outer sheet also higher sheet thickness and / or yield point can safely in the manufacture of pipes complex curvature curves can also be generated.

Fig. 1

eine Platine in Draufsicht;

Fig. la

einen Schnitt entlang der Linie X-X von Fig. 1;

Fig. 2

ein aus der in Fig. 1 gezeigten Platine gefertigtes Rohr in perspektivischer Ansicht.

The invention is explained in more detail below on the basis of a drawing illustrating an exemplary embodiment. Show it:

Fig. 1

a circuit board in plan view;

Fig. La

a section along the line XX of Fig. 1;

Fig. 2

a tube made of the circuit board shown in Fig. 1 in a perspective view.

The board P is essentially made of a base plate G. formed, which is made of a first steel material consists. Its material properties and thickness D are on adapted the loads to which that from the board P to manufacturing pipe R is exposed in practical operation. The tube R has, as Fig. 2 shows, in its middle Apply a curvature K.

In the area of the board P from which the tube R the inner curve I of the curvature K is formed is a Sheet metal blank 1 inserted into the board P. This is in in a manner known per se the shape of the sheet metal blank 1 adapted cut in the base plate G cut Service. The sheet metal blank is then 1 in inserted this section and its border area for example by laser welding with the Base plate G has been welded. In the same way is in that area of the board P from which the tube R the outer arc A of the curvature K is formed Sheet metal blank 2 inserted into the board P.

The sheet metal blank 1 is made of a steel material manufactured, which has a lower yield point, than the steel from which the base plate G of the board P has been manufactured. At the same time, the thickness D1 is the Sheet metal blank 1 larger than the thickness D of the base sheet G. The sheet metal blank 2 has a thickness D2, which is also greater than the thickness D of the base plate G.

In the manufacture of the tube R is first from the first steel material cut the base plate G. Then the sheet metal blanks 1 and 2 in the base plate G used. The board P thus formed is then first in a known manner to a straight line running pipe preformed and longitudinally welded.

In the last step, the curvature K of the tube R generated by the preformed straight tube in one suitable bending device by cold forming becomes. This prevents a material reservoir performing and when bending the tube under Tensile stress standing sheet metal blank 2 due to its Shape, its location in the board P, its Material properties and its thickness D2 that it in Area of the outer curve A of the curvature K to one excessive, the risk of cracking with material thinning. In the same The position of the sheet metal blank 1 in the circuit board is such P, its yield point and its thickness D1 are chosen such that the sheet metal blank 1 in the inner sheet I the formation of Prevents wrinkles without the use of Sheet metal cut 1 due to in the area of the inner curve I prevailing during bending and an upsetting of the sheet metal material there Compressive stresses could arise.

The location in the board P, the material properties, the Thickness and the geometry of the sheet metal blanks are 1.2 for example by simulation calculations according to the Finite element method has been determined. It is first cold forming from one the same material as the base plate G existing level, only virtually existing sample board up to reproduced in a fully formed, virtual tube been, the shape of the shape of the tube to be produced R corresponded. Then on the tube model thus formed the areas have been marked where there is a excessive weakening of the component (outer arch) or too Folds (inner arch) has come. The size, the type and the course of the deformation errors was also determined.

Then the deformation process is under Retention of the markings has been traced until the sample board is back on its level Initial state was. The situation was in this condition and shape of the areas in which the sheet metal blanks 1, 2 were recognizable by the markings. The required material properties and the thickness of the Sheet metal blanks 1,2 are then based on the Determined deformation errors determined virtual tube Service.

An alternative approach is for Design of the sheet metal blanks with necessary steps With the help of the grid technology have been determined. Is to a real one, made of the same material as that Base plate G existing, flat sample board in undeformed condition has been coated with halftone dots. The spatial coordinates of these grid points were determined and stored in a computer. Then the pattern board is in the shape of the tube R has been cold formed. With this deformation one went Shift the grid points according to the Material flow of the sample board. The coordinates of the halftone dots on the generated tube, which in the Areas with insufficient deformation (outer arch, Inner arches) were found. By the position of the relevant grid points and the associated location the sheet metal blanks 1, 2 in the flat sample board certainly. The required material properties and the thickness of the sheet metal blanks 1, 2 is then again based the pipe created from the sample board existing deformation errors have been determined.

REFERENCE NUMBERS

1

Sheet metal cutting ("patch")

2

Sheet metal cutting ("patch")

A

outside bend

D

Thickness of base plate G

D1

Thickness of the sheet metal blank 1

D2

Thickness of the sheet metal blank 2

G

base plate

I

inside bend

K

curvature

P

circuit board

R

pipe

Claims (16)

Process for the production of cold-formed components (R) from sheet steel comprising the following steps: Producing a circuit board (P) from a base plate (G) consisting of a first steel material; Replacing at least a section of the base plate (G) with a sheet metal blank (1, 2) which differs in thickness (D1, D2) and / or at least one material property from the first steel plate (G), the thickness (D1, D2 ) or the deviating material properties and the geometry of the sheet metal blank (1, 2) and its position in the blank (P) are determined by the material flow during the subsequent cold forming; Cold forming of the board (P) to the component (R). Method according to Claim 1, characterized in that for determining the material properties, the thickness, the geometry and / or the position of the sheet metal blank a sample board consisting only of a base plate is brought into the shape of the component to be produced, that areas are determined on the component produced from the sample circuit board in which there has been a deformation which does not meet the requirements, and that the insufficiently deformed areas are assigned to those areas of the pattern board in which the sheet metal blanks are to be inserted by tracing the forming process. A method according to claim 2, characterized in that the deformation of the sample board to the component, the determination of the areas of insufficient deformation and the tracing of the forming process are carried out as a simulation calculation according to the finite element method. A method according to claim 2, characterized in that the surface of the pattern board is provided with halftone dots and the spatial coordinates of the halftone dots are stored, that the sample board is then deformed into the component, that when determining the insufficiently deformed areas of the pattern board, the halftone dots are determined which lie in the insufficiently deformed areas, and that by comparing the position of these grid points on the component with the original position of the grid points concerned on the undeformed pattern board, the forming process is traced and those areas of the pattern board are determined in which the sheet metal blanks are to be inserted. Method according to one of the preceding claims,
characterized in that the sheet metal blank (1, 2), based on its position in the board (P), has a lower deformability than the surrounding base sheet (G) of the board (P). Method according to one of claims 1 to 4,
characterized in that the sheet metal blank (1, 2), based on its position in the board (P), has a higher forming capacity than the base sheet (G) of the board (P) surrounding it. Method according to one of the preceding claims,
characterized in that the thickness (D1, D2) of the sheet metal blank (1, 2) after the cold forming is essentially equal to the sheet thickness (D) of the base sheet (G) of the blank. Sheet steel plate for the production of a Component (R) by cold forming, comprising a Base plate (G) with at least one section is replaced by a sheet metal blank (1,2), which consists of one with regard to its thickness (D1, D2) and / or at least one material property from that Distinguishing base plate (G) of the board (P) Steel material is made and its geometry, Material property, thickness and / or location by the during cold forming of the blank (P) incoming material flow are determined. Blank according to claim 8, characterized in that in the area (A) of the blank (P), which is subjected to tensile stresses during cold forming, a sheet metal blank (2) is arranged, the thickness (D2) of which is greater than the thickness (D) of the surrounding base plate (G) of the board (P). Blank according to claim 8 or 9, characterized in that in the area (A) of the blank (P), which is subjected to tensile stresses during the cold forming, a sheet metal blank (2) is arranged, the yield point of which is higher than the yield point of the surrounding base plate (G) of the board (P). Blank according to one of claims 8 to 10, characterized in that in the area (I) of the blank (P), which is essentially stressed by compressive stresses during cold forming, a sheet metal blank (1) is arranged, the yield point of which is lower than that Yield point of the base plate (G) surrounding the plate (P). Blank according to one of claims 8 to 11, characterized in that in the area (I) of the blank (P), which is essentially stressed by compressive stresses during cold forming, a sheet metal blank (1) is arranged, the thickness (D1) of which is smaller is the thickness (D) of the base plate (G) of the board (P) surrounding it. Blank according to one of claims 8 to 11, characterized in that in the area (I) of the blank (P), which is essentially stressed by compressive stresses during cold forming, a sheet metal blank (1) is arranged, the thickness (D1) of which is greater is the thickness (D) of the base plate (G) of the board (P) surrounding it. Use of a circuit board (P) according to one of the claims 8 to 13 for the production of a tube (R). Use according to claim 14, characterized in that the tube (R) receives a curvature (K) in the course of the cold forming in the direction of its longitudinal extent. Use of a circuit board according to one of claims 8 to 13 for the production of a deep-drawn component with square base.

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