EP2217393B1 - Production method of highly dimensionally accurate half shells - Google Patents

Abstract

The invention relates to a method for producing highly dimensionally accurate, deep-drawn half shells having a floor area (3) and a notch (2), wherein a preformed half shell (1) is first formed from a circuit board. The task of providing a method for producing highly dimensionally accurate half shells, with which highly dimensionally accurate half shells which can be easily welded to one another can be manufactured cost-effectively with minimal machined-based complexity, is achieved according to the invention in that due to the geometric shape the entire cross-section of the preformed half shell (1) has excess circuit board material, the entire cross-section is compressed by the excess material in the final shape thereof during reshaping of the preformed half shell (1) by way of at least one more pressing procedure into the finished half shell, and the finished half shell has an enlarged wall thickness substantially over the entire cross-section.

Description

The invention relates to a method for the production of highly dimensionally stable, deep-drawn half-shells with a bottom portion and a frame, wherein first of all a preformed half-shell is formed from a blank, which is subsequently formed into the finished half-shell.

Increasingly closed hollow sections are used in motor vehicles, which have specially adapted to the application cross sections and material thicknesses. So far, closed hollow sections are usually prepared by first a tube is formed, the pipe is subjected to corresponding bends and Vorverformungen and then takes a hydroforming of the pre-bent or pre-formed tube to the final shape of the closed hollow profile. On the one hand, not all components can be produced in this way, since during hydraulic forming local strains of the material are exceeded and thus cracking can occur. In addition, uncontrollable wrinkling may occur during hydroforming. In addition, the previously used process steps for producing an application-adapted, closed hollow profile are very complicated and therefore expensive. Although a closed hollow profile can in principle also be produced from two deep-drawn half shells. During the deep drawing of a board but tensions in the Board introduced, which lead to a springback of the half shell. The springback of the half shells complicates the exact positioning of the half shells in a die for welding the half shells to a closed hollow profile. Welding the edges of the half-shells in an I-shock was previously possible only with great effort during the positioning of the half-shells during welding due to the springback of the half-shells. For this reason, previously closed hollow sections, which consist of welded half-shells, have usually been welded to projecting flange areas. However, these closed hollow sections can not be used as closed hollow sections, which are made of a welded tube and have no protruding weld due to the protruding weld. In addition, the flanges increase the overall weight of the component.

An assembly of highly resilient half shells in a vehicle structure is very expensive due to the strong delay. Alternatively, these parts must be addressed, which is associated with higher costs.

A method for producing half-shells is disclosed in the published Japanese patent application JP 08/168830 known, in which a circuit board is first deep-drawn in a die and projecting flange arise. The flange areas are then simultaneously compressed and sheared off via a cutting and punching punch. The problem with the half-shells produced in this way is that they have irregularities at the edges and thus for welding in an I-joint not very well suited. In addition, the half shells usually still restoring forces, which complicate the welding.

From the published European patent application EP 1 792 671 A1 is a method for press-forming of half-shells known, which are then welded to a closed hollow profile. The object of said European patent application is to provide half-shells with thickened edge regions between the bottom region and the frame. For this reason, a preformed half-shell is initially produced from a circuit board, which provides excess material that is pressed from the bottom region into the edge regions between the frame and the bottom region of the half-shell during the forming into the final shape. In contrast, the present invention is concerned with the reduction of the springback of deep-drawn half shells.

Proceeding from this, the present invention has the object to provide a method for the production of highly dimensionally stable half shells, with which low equipment cost low dimensionally stable half shells can be produced that are easily welded together.

The above object is achieved according to the teachings of the present invention in that the entire cross-section of the preformed half shell due to its geometric shape has excess board material, by the excess material during the Forming the preformed half-shell in its final shape by at least one further pressing operation of the entire cross-section is compressed to the finished half-shell and the finished half-shell substantially over the entire cross section has a relation to the preformed half-shell increased wall thickness.

Due to the excess material it comes to the compression of the final shape in the finished die for upsetting the entire cross section, so that the excess material is distributed throughout the cross section. As a result, the entire cross section is compressed, which means that the introduced during pressing into the preformed half shell stresses in the frame in the vertical and in the region of the bottom are aligned in horizontal directions. The pressing process for the final shape leads to an increase in the wall thickness of the half shell. At the same time, the springback of the half-shell is eliminated, since the introduced compressions superimpose the restoring forces or transform stresses in a half-shell into a directed return spring. As a result, a finished molded half-shell with a particularly high dimensional stability is available. The high dimensional accuracy means that the half-shells produced by the method according to the invention can be welded in a simple manner, for example in flangeless half shells in an I-joint. High dimensional stability means reduced tolerances compared to conventional deep drawing.

In a particularly simple manner, according to a first embodiment of the present invention Excess board material in the bottom area are provided by the fact that the bottom portion of the preformed half-shell is concave, convex or wavy shaped.

If, in accordance with a next embodiment of the method according to the invention, the preformed half shell has flange regions and the frame is stretched over a flange deceleration, the springback of the preformed half shell can already be reduced.

Flange-free half-shells can be made available according to a further developed embodiment of the method according to the invention in that the flange areas are separated during and / or after the forming of the finished half-shell via cross slide or laser cutting or by other methods. Despite the preformed half shells with flange areas used, an economical method for the preferred production of high-dimensional, flange-less shells is thus provided.

According to a further embodiment of the method according to the invention, the strengths required, for example, for the use of the half shells in motor vehicle construction can be made available in that the board consists of steel or a steel alloy. At the same time good forming properties of the boards are provided.

Can be improved, the inventive method in that the deformation of the board in the preformed half-shell and the deformation of the preformed half-shell in the final shape in a single device, preferably in a single die with exchangeable bottom takes place, for example, which can be realized in a progressive compound tool. Not only investment costs can be saved with it, but usually also cycle times for the production of half-shells, since transport paths between different dies omitted. This leads to a particularly high efficiency of the method according to the invention.

Fig. 1

in einer schematischen Schnittansicht eine vorgeformte Halbschale gemäß einem ersten Ausführungsbeispiel des erfindungsgemäßen Verfahrens,

Fig. 2a) und b)

in einer schematischen Schnittansicht die beschnittene, vorgeformte Halbschale aus Fig. 1 während eines zweistufigen Umformens gemäß dem ersten Ausführungsbeispiel des erfindungsgemäßen Verfahrens,

Fig. 3

in einer schematischen Schnittansicht eine vorgeformte Halbschale gemäß einem zweiten Ausführungsbeispiel des erfindungsgemäßen Verfahrens,

Fig. 4a) und b)

in einer schematischen Schnittansicht die Umformung der vorgeformten Halbschale zur fertigen Halbschale gemäß dem zweiten Ausführungsbeispiel des erfindungsgemäßen Verfahrens,

Fig. 5

in einer schematischen Schnittansicht eine vorgeformte Halbschale gemäß einem dritten Ausführungsbeispiel des erfindungsgemäßen Verfahrens und

Fig. 6a) und b)

die Umformung der vorgeformten Halbschale zur Endform gemäß dem dritten Ausführungsbeispiel des erfindungsgemäßen Verfahrens.

There are now a multitude of possibilities for designing and developing the method according to the invention. Reference is made on the one hand to the claims subordinate to claim 1 and on the other hand to the description of three embodiments of the method according to the invention in conjunction with the drawing. The drawing shows in

Fig. 1

1 is a schematic sectional view of a preformed half shell according to a first exemplary embodiment of the method according to the invention,

Fig. 2a) and b)

in a schematic sectional view of the trimmed, preformed half shell Fig. 1 during a two-stage forming according to the first embodiment of the method according to the invention,

Fig. 3

1 is a schematic sectional view of a preformed half shell according to a second exemplary embodiment of the method according to the invention,

Fig. 4a) and b)

in a schematic sectional view, the deformation of the preformed half-shell to the finished half-shell according to the second embodiment of the method according to the invention,

Fig. 5

in a schematic sectional view of a preformed half-shell according to a third embodiment of the method according to the invention and

Fig. 6a) and b)

the deformation of the preformed half-shell to the final shape according to the third embodiment of the method according to the invention.

In Fig. 1 First, a preformed half-shell 1 is shown in a schematic sectional view. The half-shell has a frame 2 and a bottom portion 3. In Fig. 1 can be further seen that the bottom portion 3 is slightly curved and the additional flanges 4 are provided.

A first embodiment of the method according to the invention is now in the Fig. 2a) and 2b ) dargstellt. First, the figures show schematically a die 5 with a die 6, which together with the punch 7 the now flangeless half shell 1 can transform to the final shape. In Fig. 2a ) it can be seen that the punch 7 due to the preform of the half-shell 1 in the deformation of the half-shell 1, the bottom portion 3 and the frame 2 upsets. Due to the compression process, a material flow is generated, which is approximately those in Fig. 2a ) corresponds to arrows. On the one hand, the wall thickness of the finished half shell over the entire cross section is slightly increased by upsetting over the entire cross section. The increase in the wall thickness is not shown in the figures. On the other hand, this also means at the same time that stresses are generated in the horizontal direction in the bottom region 3 and in the vertical direction in the frame 2 during the deformation. The springback forces are thereby transformed into stresses which trigger a directed springback. These then lead to the finished molded half-shell 1 is highly dimensionally stable. The first preformed half-shell 1 initially has a convex bottom area 3 in order to provide additional board material for the compression.

Unlike the embodiment Fig. 1 represents the preformed half-shell 1 'of Fig. 3 the additional board material for compression available, because the preformed half-shell 1 'has a convex bottom portion 3' on. During the deformation, the excess material from the convex bottom portion is pressed into the side regions or in the frame region of the half-shell, so that in the frame 2 'perpendicular to the bottom region extending and in the bottom region horizontally extending voltages are introduced, which for Rückfederungsarmut the finished molded half-shell 1 'lead. In the Fig. 4a) and 4b ) can also be seen that the punch 7 'is particularly simple and has no elements for compression of the frame. The compression of the frame 2 'is achieved via the hold-down 8', which cause a compression due to the flow of material from the bottom portion 3 '.

In Fig. 5 Finally, in a schematic sectional view, a preformed half shell 1 "is shown, which according to a third embodiment of the method according to the invention also during the forming flange 4" has. The flange 4 "are held by downholders 8" during the forming according to a third embodiment of the method according to the invention, as shown in FIG Fig. 6a) and 6b ) is recognizable. The bottom portion 3 "is convexly preformed in the third embodiment, so that sufficient board material can be provided to compress the bottom portion 3" and the frame 2 "according to the invention.

Claims (6)

1. A method for producing highly dimensionally accurate, deep-drawn half shells (1; 1'; 1") with a bottom area and a wall, wherein a blank is initially shaped into a preformed half shell (1; 1'; 1") by means of deep-drawing and the preformed half shell is subsequently reshaped into the finished half shell,
   characterized in that
   the entire cross section of the preformed half shell (1; 1'; 1") features excess blank material due to its geometric shape, in that the entire cross section is compressed into the finished half shell by the excess material during the reshaping of the preformed half shell into its final shape by means of at least one additional pressing cycle, and in that the finished half shell has a wall thickness that is increased in comparison with that of the preformed half shell over essentially the entire cross section.
2. The method according to Claim 1,
   characterized in that
   the bottom area (3; 3'; 3") of the preformed half shell (1; 1'; 1") has a concave, convex or undulated shape.
3. The method according to Claim 1 or 2,
   characterized in that
   the preformed half shell (1; 1'; 1") features flange areas (4; 4") and the wall (2; 2'; 2") is ironed by means of a flange deceleration.
4. The method according to one of Claims 1 to 3,
   characterized in that
   the flange areas (4; 4") are removed by means of cross slides or laser trimming during and/or after the reshaping into the finished half shell (1; 1'; 1").
5. The method according to one of Claims 1 to 4,
   characterized in that
   the blank consist of steel or a steel alloy.
6. The method according to one of Claims 1 to 5,
   characterized in that
   the shaping of the blank into the preformed half shell and the reshaping of the preformed half shell into the final shape take place in a device, preferably in a die with exchangeable bottom.

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