DE102010045281A1 - Method for reshaping metal sheet for housing structure of e.g. tailgate of passenger car, involves defining material stock and carrying out complete development in region of pre-tensioned workpiece before supplementary drawing step - Google Patents

Abstract

The method involves deforming workpiece (1) to form deep edges (14) or flanges between forming punch and die (3). The workpiece is pulled and/or stretched and pre-tensioned by die insert (5) in a supplementary drawing step (6). A material stock is defined in the supplementary drawing step. Complete development in the region of pre-tensioned workpiece is carried out spatially, using the die before supplementary drawing step. An independent claim is included for device for reshaping workpiece.

Description

The invention relates to a method for forming a workpiece, preferably a sheet, wherein, in particular for use in bodywork, the workpiece is deformed to produce deep-set edges, flanges or the like. Between a forming die and a die on at least one drawing stage and when passing through the edges / Flanges undergo considerable strains and compressions.

Furthermore, the invention relates to a corresponding device.

Basically, this is about the deformation of workpieces, in particular the deep drawing of sheets.

Especially in car body components are used, which have areas with particularly deeply set edges or flanges. For example, reference is made to car tailgates and provided there headlight openings with deeply flanged flanges. There are any other components in which correspondingly deeply set flanges are to be formed. By way of example only, reference is made here to the bodywork and the components to be processed there.

In the manufacture of sheet metal parts with deeply flanged flanges special problems occur. In addition the following:
When passing through the respective flange, large expansions and compressions occur. Therefore, the flange area is formed as deep as possible in the first forming operation (OP20). This is called tightening the flange. The thereby achievable board height is limited due to thinning and tearing in the material.

Subsequently, a cutting operation (OP30) is usually carried out in order to carry out the trimming within the contour of the board. Thereafter, in a far-reaching forming operation (OP40), the flange is passed through reshaping and thereby finished. Depending on the curvature of the flange contour, the flange material is stretched and / or compressed. The longer the flange is formed and the smaller the penetration radius, the stronger are expansions / compressions.

Excessive expansion in the flange area in OP40 exceeds the residual elasticity which the material can still withstand after tightening (OP20) the flange. In this case, it comes to tearing of the flange or at least to the formation of surface defects that are regularly on the visible surface of the respective component.

If the sheet is compressed too much in the flange area, buckling of the material occurs in the form of undulations in the flange area. In addition, the compressive stresses thus induced cause an increased springback behavior, resulting in a much poorer shape retention of the flange.

In the light of the above, it has hitherto been necessary to reduce the flange length on the component as much as possible in order to ensure the manufacturability of the component or of the flange.

In 1 the aforementioned production steps are indicated by the example of a sheet metal part, according to which the sheet is tightened according to OP20 to maximum depth and designed for trimming. According to OP30 is cropped. According to OP40 is folded or put through.

At this point, it should be pointed out once again that expansion and compression areas occur during the flange feed-through. The sheet material is stretched when passing through the flange, which arise when stretched too much tear, namely by insufficient residual elasticity. Consequently, the tightening depth and, correspondingly, the flange length must be reduced, namely until the residual ductility for OP40 is sufficient.

In the case of flange feedthrough, upsetting also occurs, resulting in a wavy flange or a finished part with increased springback behavior. Here too, it has hitherto been necessary to reduce the flange length, namely to reduce or even eliminate stresses or ripples.

In light of the above, the present invention has for its object to provide both a method and a device for forming a workpiece, after which in particular components can be produced for the body shop. In a method according to the invention and using the device according to the invention, it should be possible to manufacture areas with particularly deeply flanged flanges effortlessly and in perfect quality. It should be feasible considerable drawing depths.

The above object is achieved with respect to the method according to the invention by the features of patent claim 1. Thereafter, the inventive method is characterized in that the workpiece is preferably pulled or stretched and biased by a leading die insert on an additional drawing stage, wherein the additional drawing stage, a material supply is defined and wherein the complete Marked by the die in the region of the prestressed workpiece spatially in front of the additional drawing stage.

The inventive device is characterized by the features of claim 6, namely, characterized in that the die comprises a leading die insert, through which the workpiece via an additional drawing stage is pulled or stretched and prestressed, wherein by the additional drawing stage, a supply of material is definable and wherein the full expression by the die in the area of the prestressed workpiece takes place spatially in front of the additional drawing stage.

According to the invention, it has been recognized that the problems occurring in the prior art can be remedied by provision of a kind of material supply. More specifically, in OP20, an additional draw stage is created using a leading die insert. In a sophisticated manner, the scrap portion of the drawn part is stretched, so that the additional draw step defines a supply of material which, when fully formed by the die, is released during the molding of the part form by the die. By this measure, a significantly greater tightening depth can be realized than was previously possible in the prior art. In this case, the additional drawing stage and the material storage thus generated are of very particular importance.

As already mentioned above, the additional drawing stage is most advantageously located in a waste area of the workpiece, whereby the relevant waste area in the additional drawing stage is deformed or stretched. For material release, the die insert is displaced.

In principle, it is conceivable that the stored material is released before or during the full expression. A gradual release during the full expression is conceivable.

In a particularly advantageous manner, the material supply can be adjusted, namely by adjusting / adjusting the flow of Matrizeneinsatzes against the die. Here mechanical means can be used.

In a further advantageous manner, after the first forming operation according to OP20, a cutting operation (OP30) takes place, which in turn follows a final forming (OP40) by folding and passing through. Any further details in the process can be realized, using the teachings of the invention.

With regard to the device according to the invention, the matrix insert is of particular importance, by means of which the workpiece can be pulled or stretched and prestressed via an additional drawing step. The drawing step defines the stock of material, wherein the full expression by the die in the region of the prestressed workpiece takes place spatially in front of the additional drawing stage.

With respect to the Matrizeneinsatz it is particularly advantageous if it is movably mounted in the die, wherein the die insert is movable together with the die in the direction of deformation and movable against its gravity and possibly against the force of a pressure medium into the die, namely to release the material of the storage.

In a particularly advantageous manner, the forming punch is associated with a displacement bolt which acts against the die insert and optionally against the force of the pressure means of the die insert. The sheet to be deformed is finally clamped between the die insert and the displacer pin.

Therefore, it is advantageous if the Matrizeneinsatz is driven back not only on the displacer, but also, for example, plate holder and / or intermediate driver in the die. Other relevant embodiments can be found in the following description of the figures.

Also, the basic adjustability of the flow of Matrizeneinsatzes is of particular importance, for which purpose at least one spacer can be provided which acts between a shoulder of the Matrizeneinsatzes and a support in the die, or vice versa.

It should be noted at this point that the above statements refer to an arrangement according to which the die is equipped with a die insert. Accordingly, the forming punch on a Verdrängerbolzen. The arrangement can also be designed the other way round, namely with a forming punch insert formed in the forming punch and a displacement bolt arranged in the die. Also, the specific arrangement and the direction of movement of the tool parts does not matter, especially since not only vertical and horizontal arrangements, but also arrangements in any angular position are conceivable.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand to the independent claims 1 and 6 subordinate claims and on the other hand to the following explanation of a preferred embodiment of the invention with reference to the drawing. In connection with the explanation of the preferred embodiment of the invention, the individual process steps are also discussed. In the drawing show

1 3 shows a schematic representation of the three production steps OP20, OP30 and OP40 in the manufacture of a body component with a flange,

2 in a schematic view, cut, the working principle of the method according to the invention with reference to a device according to the invention,

3 in a schematic view, the implementation of the method according to the invention in a tool according to the invention, where only the essential components are shown there and

4 to 10 in schematic views of the functional sequence of the method according to the invention with reference to a device according to the invention.

1 shows the problem in the production of a subsequently always as a workpiece 1 designated body parts with strong flange 2 , The processing steps OP20, OP30 and OP40 take place until the workpiece 1 with pronounced flange 2 is made. For related problems in the prior art reference is made to avoid repetition on the general part of the description.

2 shows a schematic representation of the inventive solution both in relation to the inventive method and in relation to the device according to the invention. The device includes next to the female mold 3 and the shape stamp 4 a leading die insert 5 which generates an additional drawing stage 6 is being used. The additional draw level 6 serves as a stock of materials, with the drawing stage 6 in the waste sector 7 is produced. When forming the part form by the die 3 is the stock of material in the drawing stage 6 released by the die insert 5 moved upwards. By this measure according to the invention a significantly greater tightening depth can be realized, at least substantially greater than in the prior art known from practice.

The 3 to 10 show the functional sequence of the method according to the invention with reference to an embodiment of a device according to the invention shown in simplified form.

First of all, the tool is closed. The die insert is corresponding to the geometry to be formed 5 by a few millimeters to the final forming depth. At the time when the tensions in the frame become too large, the die insert becomes 5 over a the form stamp 4 associated displacement bolt 8th into the upper part of the tool or into the die 3 pushed back. In addition, a metal holder act 9 and an intermediate driver 10 on the die insert 5 , That when pushing back or retracting the die insert 5 released material is due to the further closing die 3 spent in the finished form.

In bottom dead center (UT) a shutdown of the sub-air force is required, thus no deformation of the workpiece 1 through the raised sheet metal holder 9 takes place.

During the upward movement of the tool, namely the die 3 moves up, pushes the die insert 5 by spring force and dead weight still on the workpiece 1 , To the workpiece 1 not to deform unintentionally, is to ensure that the displacement bolt 8th initially remains in its UT position. Should to the weight of the sheet holder 9 not sufficient, it may be necessary additional springs 11 provide that between the die 3 and the sheet holder 9 Act. The feathers 11 or corresponding pressure medium can the die 3 be assigned or integrated there.

In relation to 3 In addition, it should be noted that the displacement stroke over the driver angle between the intermediate driver 10 and the sheet holder 9 can be set.

For the sake of completeness, let's look at the under-air bolts 12 referenced, directly or indirectly, to the blank holder 9 Act.

4 shows detail "A" according to 3 , in which 4 clearly indicates that the matrix insert 5 by a few millimeters from the die 3 protrudes. The degree of protrusion can be achieved by spacers 13 adjust between the die insert 5 and the matrix 3 Act.

4 shows the initial contact between the die insert and the sheet on the downstroke. In addition, the shows 4 the provision of the displacement bolt 8th in the mold stamp 4 is integrated.

5 shows detail "A" 3 on the downhill. It can be clearly seen that the workpiece 1 over the die insert 5 and the shape stamp 4 stressed. From the date on which the workpiece 1 to the edge 14 of the stamp opening 15 applies, in accordance with the invention, the material supply by generating the additional drawing stage 6 generated.

Due to the further overvoltage and the possibility of releasing the waste area 7 can be achieved a larger expansion zone and thus a larger possible settlement.

6 shows detail "A" in the lowest position of the die insert 5 , The matrix insert 5 has taken his lowest position there. The material supply is due to the additional draw level 6 generated. Between the displacer 8th and the die insert 5 There is no direct contact, especially between these two tool elements, the workpiece 1 is positioned. From the time shown here is the Matrizeneinsatz 5 controlled back up again, namely to further deformation of the workpiece 1 the stock of material in the additional drawing stage area 6 release.

7 Detail "A" shows the material release in the area of the additional drawing stage 6 , The sheet holder 9 experiences another downhill stroke. Via cross driver or intermediate driver 10 becomes the displacer 8th pushed up. As a result, the release of the previously generated material supply takes place in the waste area 7 of the sheet 1 by the molding of the workpiece 1 through the matrix 3 actually needed.

8th shows detail "A", where the tool has reached the position of bottom dead center there. The part form or the workpiece 1 is pronounced. The displacer pin 8th is in its highest position. That through the additional drawing stage 6 provided material of the workpiece 1 is completely released in this position.

9 shows detail "A" in the upstroke, where there is the complete deformation of the workpiece 1 implied, could be the Matrizeneinsatz 5 move down unhindered. In that regard, be on the dashed lines 16 . 17 referenced, the extent that the possible position of the workpiece 1 suggest.

As shown in 9 raises the matrix 3 from the workpiece 1 from. The matrix insert 5 but still presses on the displacer 8th , Would be the blank holder at this time 9 move upwards, would the shaped workpiece 1 be deformed. Therefore, it is necessary that the sub-air is turned off to UT.

Is the force of the matrix insert 5 due to its own weight or the spring 18 greater than the weight of the blank holder 9 , it is necessary to use the metal holder 9 about additional springs 11 to hold in the lower position. In that regard, be on the following 10 directed. In this measure, the displacer would 8th be pressed down and would the blank holder 9 via the cross driver or intermediate driver 10 be raised, giving a double deformation of the workpiece 1 according to the dashed lines 16 . 17 out 9 would result. This is to be avoided according to the above statements.

10 shows the tool configuration on the upstroke, in which case, the weight of the blank holder 9 is too low, additional springs 11 for holding the sheet metal holder 9 are provided at bottom dead center.

According to the foregoing, it is necessary that the displacement bolt 8th remains in the position of the bottom dead center, so that an unwanted deformation of the workpiece 1 is excluded. Also, about the underair bolts 12 shut off to lifting the sheet holder 9 to prevent. Accordingly, the counterforce to Matrizeneinsatz 5 maintained.

With regard to further advantageous embodiments of the device according to the invention, reference is made to avoid repetition to the general part of the specification and to the appended claims.

Finally, it should be expressly understood that the above-described embodiment of the device according to the invention is only for the purpose of discussion of the claimed teaching, but this does not limit the embodiment.

LIST OF REFERENCE NUMBERS

1

workpiece

2

flange

3

die

4

forming punch

5

die insert

6

additional drawing stage, material supply

7

Waste area of the workpiece / sheet

8th

Verdrängerbolzen

9

blankholder

10

Intermediate driver, cross driver

11

Spring (in the die)

12

Under air bolt

13

spacer

14

edge

15

stamp opening

16

dashed line

17

dashed line

18

Spring (acts on die insert)

Claims (10)

A method for forming a workpiece, preferably a sheet, wherein in particular for use in the bodywork, the workpiece is deformed to produce deep-set edges, flanges or the like. Between a forming die and a die on at least one drawing stage and enforcing the edges / flanges considerable strains and Compressions undergone, characterized in that the workpiece is preferably pulled or stretched and biased by a leading die insert on an additional drawing stage, wherein a material supply is defined by the additional drawing stage and wherein the full expression by the die in the region of the prestressed workpiece spatially before the additional drawing stage takes place. A method according to claim 1, characterized in that the additional drawing stage is located in a waste area of the workpiece. A method according to claim 1 or 2, characterized in that before or during the full expression of the additional drawing stage and thus the material stored there is released. Method according to one of claims 1 to 3, characterized in that the material supply, possibly by the flow of Matrizeneinsatzes against the die, is adjustable. Method according to one of claims 1 to 4, characterized in that the deformation is followed by a cutting operation and that the cutting operation is followed by a final molding. Device for forming a workpiece ( 1 ), preferably a sheet ( 7 ), in particular for use in the body shop, the workpiece ( 1 ) for creating deep-set edges, flanges ( 2 ) or the like between a molding die ( 4 ) and a die ( 3 ) is deformable via at least one drawing stage and when passing through the edges / flanges ( 2 ) undergoes considerable stretching and compression, characterized in that the die ( 3 ) a leading die insert ( 5 ), through which the workpiece ( 1 ) via an additional draw stage ( 6 ) is tractable or stretchable and can be prestressed, wherein the additional drawing stage ( 6 ) a material supply is definable and whereby the complete expression by the matrix ( 3 ) in the region of the prestressed workpiece ( 1 ) spatially in front of the additional draw stage ( 6 ) he follows. Device according to claim 6, characterized in that the die insert ( 5 ) in the die ( 3 ) is movably mounted, wherein the die insert ( 5 ) together with the matrix ( 3 ) movable in the deformation direction and against the force of gravity and the force of a pressure medium in the die ( 3 ) is movable into it. Apparatus according to claim 6 or 7, characterized in that the forming punch ( 4 ) a displacement bolt ( 8th ) associated with the die insert ( 5 ) and possibly acts against the force of the pressure medium. Device according to one of claims 6 to 8, characterized in that the die insert ( 5 ) via the displacer ( 8th ) and / or via blank holder ( 9 ) and / or intermediate drivers ( 10 ) into the die ( 3 ) is zurückdrückbar. Device according to one of claims 6 to 9, characterized in that the flow of the Matrizeneinsatzes ( 5 ) by at least one spacer ( 13 ) which can be adjusted or tuned between a shoulder of the die insert ( 5 ) and a support in the die ( 3 ) acts.

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