DEEP-DRAWING DEVICE TO PREVENT WRINKLING DEFECTS IN THE PRODUCTION OF THIN-WALLED DEEP-DRAWN PARTS

Abstract

A deep-drawing device for the production of a thin-walled deep-drawn part from a sheet-metal blank includes a drawing die with a drawing edge and a sheet-metal holder, which together form a flange feed zone of the deep-drawing device, and a deep-drawing punch. The deep-drawn part includes a wall inclined toward a working direction. The deep-drawing device has at least sectional controlled wrinkle-generation elements in the flange feed zone.

Claims

1. A deep-drawing device for the production of a thin-walled deep-drawn part from a sheet-metal blank, the deep-drawing device comprising a drawing die with a drawing edge and a sheet-metal holder, which together form a flange feed zone of the deep-drawing device, and a deep-drawing punch; wherein the deep-drawn part comprises a wall inclined toward a working direction; and wherein the deep-drawing device comprises at least sectional controlled wrinkle-generation means in the flange feed zone.

2. The deep-drawing device according to claim 1, wherein the controlled wrinkle-generation means comprise a plurality of wave-like indentations along the drawing edge of the drawing die and/or a plurality of oblong, radially running recesses on a surface of the drawing die facing the sheet-metal holder or on a surface of the sheet-metal holder facing the drawing die, wherein the recesses extend up to the drawing edge.

3. The deep-drawing device according to claim 2, wherein the wave-like indentations and/or the oblong recesses are evenly spaced from each other.

4. The deep-drawing device according to claim 2, wherein the number of a plurality of wave-like indentations and/or oblong recesses across a wall segment with an enclosing angle of 90? is at least four.

5. The deep-drawing device according to claim 1, wherein the controlled wrinkle-generation means are arranged along the entire circumference of the flange feed zone.

6. The deep-drawing device according to claim 1, wherein the controlled wrinkle-generation means are arranged at least or only in sections of the flange feed zone which are curved by an axis parallel to the working direction.

7. The deep-drawing device according to claim 2, wherein the wave-like indentations are formed by a variation of the edge radius of the drawing edge.

8. The deep-drawing device according to claim 7, wherein the edge radius varies within a range between at least the thickness of the sheet used and 2.5 mm.

9. The deep-drawing device according to claim 8, wherein the edge radius varies within a range between 0.2 mm and 2.5 mm.

10. The deep-drawing device according to claim 7, wherein the wave-like indentations arranged in sections along the drawing edge form a uniform wavy line.

11. The deep-drawing device according to claim 2, wherein the oblong recesses form a uniformly wavy surface.

12. The deep-drawing device according to claim 1, wherein the inclined wall comprises an angle of at least 3 degrees.

13. The deep-drawing device according to claim 12, wherein the inclined wall comprises an angle of 5 to 15 degrees.

14. The deep-drawing device according to claim 1, wherein the deep-drawn part is a thin-walled container or hollow body with or without flange with a wall inclined toward the working direction and with a bottom.

15. A deep-drawing method for the production of a thin-walled deep-drawn part by means of the deep-drawing device according to claim 1, the method comprising: provision of the deep-drawing device which has controlled wrinkle-generation means; clamping of the sheet-metal blank in the deep-drawing device; deep drawing of the sheet-metal blank across the drawing edge, wherein wrinkles are introduced into the wall of the deep-drawn part in a controlled manner, at least in sections by means of the controlled wrinkle-generation means.

16. The deep-drawing method according to claim 15, wherein the method is a single or multiple-stage process comprising one or a plurality of forming stages, wherein at least one of the forming stages is carried out using the drawing die or the deep-drawing punch.

17. The deep-drawing method according to claim 16, wherein at least one forming stage compresses the wrinkles introduced in a controlled manner by means of double-sided tool contact.

18. A deep-drawn part produced by the deep-drawing device according to claim 1, wherein the deep-drawn part comprises an inclined wall, wherein the wall comprises a plurality of evenly arranged wrinkles in sections, which are orientated in the working direction.

19. A deep-drawn part produced by the deep-drawing method according claim 15, wherein the deep-drawn part comprises an inclined wall, wherein the wall comprises a plurality of evenly arranged wrinkles in sections, which are orientated in the working direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The invention will be explained in more detail below on the basis of exemplary embodiments in connection with the draw die(s). The figures show:

[0042] FIG. 1 a schematic illustration of a drawing device with wrinkle formation of the second type;

[0043] FIGS. 2A and 2B cut-out of an inclined wall under (FIG. 2A) with wrinkle formation of the second type under (FIG. 2B) with crack formation;

[0044] FIG. 3 drawing die with corrugated drawing edge, with FIG. 3A detailing the area A of FIG. 3;

[0045] FIG. 4 drawing die with corrugated drawing edge, with FIG. 4A detailing the area A of FIG. 4; and

[0046] FIG. 5 drawing die with radial recesses

EMBODIMENTS OF THE INVENTION

[0047] FIG. 1 shows a schematic illustration of a deep-drawing device with wrinkle formation of the second type. The deep-drawing device comprises a drawing die 2 with drawing edge 5, a sheet-metal holder 4 and a deep-drawing punch 3. The drawing die 2 with drawing edge 5 and the sheet-metal holder 4 define a flange feed zone of the deep-drawing device. A sheet-metal blank 7 made of a sheet metal or sheet foil is clamped between the sheet-metal holder 4 and the drawing die 2 and is deep-drawn into the desired shape using the deep-drawing punch 3 across the drawing edge 5. The deep-drawing device is designed for the production of a deep-drawn part 1 (see also FIGS. 2A and 2B) with (or without) a flange 11, a wall 12 inclined to the working direction A and a bottom 13. Such a deep-drawn part can be, for example, a conical container or a rectangular container with round corners. Particularly in the case of part shapes in which the wall (i.e., a wall of the deep-drawn part) is not vertical (i.e., parallel to the working direction A) but under an angle of inclination to the working direction A, so-called wrinkles of the second type can occur in the wall area 8 which can eventually lead to crack formation in the event of double-sided tool contact 8a (cf. FIGS. 2A and 2B).

[0048] In the present case, the working direction A refers to the direction in which the deep-drawing punch and the drawing die move relative to each other. This applies regardless of whether the die or the deep-drawing punch is static. In the case of rotationally symmetrical drawn parts, the working direction is parallel to the rotational axis.

[0049] FIG. 2B and FIG. 2A show this uncontrolled wrinkle formation of the second type and the crack formation in a wall of a conical container. This crack formation is also known as a wrinkling defect.

[0050] FIG. 3 and FIG. 4 now show a drawing die 2 of a deep-drawing device, by means of which a wrinkling defect can be efficiently prevented or at least significantly reduced. FIGS. 3A and 4A show an enlarged section of the drawing edge 5. The drawing die and/or its drawing edge is provided with controlled wrinkle-generation means.

[0051] The drawing die 2 shown is provided for the production of a conical container. For example, the drawing die can be used in the second drawing die stage to prevent a wrinkling defect in the conical container. The drawing die 2 comprises a circular drawing edge 5 on the inside. This drawing edge 5 is provided with controlled wrinkle-generation means in the form of a plurality of wave-like indentations 6, via which a wrinkle formation of the second type is not prevented, but the wrinkles of the second type are introduced into the wall of the deep-drawn part in a controlled manner at regular intervals. Since this prevents the wrinkle formation with narrow and irregular wrinkles, in the case of a subsequent double-sided tool contact, a wrinkling defect is prevented and/or significantly reduced, which occurs due to the squeezing of uncontrolled and therefore irregular, partially closely spaced wrinkles of the second type.

[0052] In the example shown, the drawing edge shown for such conical containers comprises a minimum edge radius of about 0.2 mm, but at least about the thickness of the sheet used. The plurality of wave-like indentations 6 of the shown sliding edge 5 are created by periodically changing the edge radius of the drawing edge 5. The edge radius in the embodiment shown varies between about 0.2 and 0.4 mm, resulting in a wave-like drawing edge with uniform amplitude and wavelength.

[0053] The drawing die in FIG. 4 differs from the drawing die in FIG. 3 in that its drawing edge 5 has a larger number of wavy indentations. The number of controlled wrinkle-generation meanse.g., in the form of wave-shaped indentations-across a wall segment with an enclosing angle of 90? is at least four (see FIG. 3). In the case of a rectangular moulded part, at least four of the controlled wrinkle-generation means would be arranged in each corner. The embodiment in FIG. 4 shows about 8 controlled wrinkle-generation means per 90? enclosing angle. The embodiment in FIG. 5 is about 10 per 90? enclosing angle.

[0054] FIG. 5 shows another way to control the wrinkle formation by designing the controlled wrinkle-generation means in the form of a plurality of radially arranged, oblong recesses 6a. The oblong recesses 6a extend in the flange feed zone partially across the surface of the drawing die 2, which is facing the sheet-metal holder 4, starting at the drawing edge 5 of the drawing die 2. Alternatively, the recesses 6a could also be arranged on a surface of the sheet-metal holder 4 facing the drawing die 2, wherein the recesses then start at the inner edge of the sheet-metal holder. These recesses 6a are also arranged regularly around the entire circumference of the flange feed zone. In the embodiment shown, they have a depth of about 0.1 mm. As a rule, the recesses 6a are inclined toward the surface of the drawing die 2 (or the sheet-metal holder 4) so that the recesses 6a taper radially toward the outside. Ideally, the recesses 6a reach up to the drawing edge 5 and/or are combined with indentations 6.

REFERENCE LIST

[0055] 1 deep-drawn part [0056] 11 flange [0057] 12 wall [0058] 13 bottom [0059] 2 drawing die [0060] 3 deep-drawing punch [0061] 4 sheet-metal holders [0062] 5 drawing edge [0063] 6 wave-like indentation [0064] 6a oblong recess [0065] 7 sheet-metal blank [0066] 8 wrinkle formation of the second type in the wall area [0067] 8a crack formation [0068] A working direction