Method for producing sheet metal components and device therefor

Abstract

The present invention relates to a method for producing a dimensionally stable sheet metal component, wherein the method includes preforming a metal sheet into a sheet metal preform comprising at least one base region, a frame region, a transitional region between the base region and the frame region, optionally a flange region and a transitional region between the frame region and the flange region, wherein at least one of the regions comprises excess material at least in portions. The sheet metal preform is cut at least in portions to form a cut sheet metal preform with a sheet metal preform The sheet metal preform is one of swagged and calibrated which has been cut at least in portions to form a substantially finished formed sheet metal component.

Claims

1. A method for producing a sheet metal component using a preform tool, a cutting tool and a calibrating tool, wherein the method comprises the following steps: preforming, in the preform tool, a metal sheet into a sheet metal preform comprising at least one base region, a frame region, and a first transitional region between the base region and the frame region, wherein at least one of the regions comprises excess material at least in portions; subsequent to the preforming, cutting, in the cutting tool, the sheet metal preform at least in portions to form a cut sheet metal preform with a sheet metal preform edge, the cut sheet metal preform having a cut developed length resulting from the cutting: and subsequent to the cutting, calibrating, in the calibrating tool, the sheet metal preform to form a substantially finished formed sheet metal component having a calibrated developed length resulting from the calibrating; wherein the cut length is longer than the calibrated length; wherein the cut developed length at least for a portion in cross section which is between 0.5% and 4% longer in relation to the calibrated developed length of the finished formed sheet metal component.

2. The method as claimed in claim 1, wherein a material flow is specifically controlled at least in portions during the preforming of the metal sheet into the sheet metal preform.

3. The method as claimed in claim 2, wherein after the completion of the preforming of the metal sheet into the sheet metal preform, material stockpiles are provided as excess material at least in portions.

4. The method as claimed in claim 3, wherein the material stockpiles are specifically introduced via the preform tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention shall be explained more closely with the aid of drawings. The same parts are given the same reference numbers. Specifically, there are shown:

(2) FIG. 1 is a cross section through a flat metal sheet;

(3) FIGS. 2a, b is an exemplary embodiment of a preform tool according to the invention to carry out an exemplary embodiment of a sheet metal preform according to the invention;

(4) FIGS. 3a, b is an exemplary embodiment of a cutting tool according to the invention to carry out an exemplary embodiment of a cut sheet metal preform according to the invention;

(5) FIGS. 4a, b is an exemplary embodiment of a calibrating tool according to the invention to carry out an exemplary embodiment of calibrating according to the invention;

(6) FIG. 5 is an exemplary embodiment of a first finished sheet metal component; and

(7) FIG. 6 is an exemplary embodiment of a second finished sheet metal component.

DETAILED DESCRIPTION

(8) FIG. 1 shows for example a flat metal sheet (1) in cross section, which is unwound from a coil, not shown, and cut to length, and which is provided in particular as a defined blank cutout to the further process. Preferably, the metal sheet (1) is made from a steel material, preferably from a high-strength steel material. Alternatively, aluminum materials or other metals may also be used. The metal sheet may also be provided as a tailored product.

(9) According to the invention, it is provided that the metal sheet (1) is at first formed with customary methods such that the geometry of the sheet metal preform (2) is provided with a material excess, for example in the form of at least one material stockpile (4) in the base region (2.1) for the further processes. The material excess may also alternatively or cumulatively be provided in the frame region (2.2), in the flange region (2.3) and/or in the transitional regions (2.4, 2.5) between base region (2.1), frame region (2.2) and flange region (2.3), not shown here. The sheet metal preform (2) may preferably be produced by classic deep drawing. The sheet metal preform (2) is produced for example in a preform tool (5), whereby the flat metal sheet (1) is placed in the opened preform tool (5) with suitable means, not shown here, and then a preforming stamp (5.1), a preforming die (5.2) and at least one blank holder (5.3) act on the metal sheet (1). The movement and/or travel of the components of the preform tool (5) is shown symbolically by the double arrows (5.11, 5.31). After the inserting of the metal sheet (1), the blank holder (5.3) clamps the metal sheet (1). After this, the preforming stamp (5.1) travels in the direction UT and forms the metal sheet (1) into a sheet metal preform (2). The blank holder (5.3) may be distanced or subjected to a force. The preforming die (5.2) may comprise at least one drawing bead and/or drawing step (5.4) at least in portions, which positively supports in particular the ironing during the deep drawing to form the sheet metal preform (2) and ensures an adequate development in the transverse extension (Q″) and/or longitudinal extension (A″) on the sheet metal preform (2), as well as avoidance of unwanted folding. For the controlled formation of the material stockpile (4), for example, the preforming stamp (5.1), possibly in combination with an inner hold-down device (not shown here), is designed to introduce material stockpiles (4) during the preforming of the metal sheet (1) to form the sheet metal preform (2). Thanks to the introducing or providing of the formation of the material stockpile (4) during the production of the sheet metal preform (2), besides the overdimensioning of the sheet metal preform (2) it is also possible to take into account the material excess needed for the swaging/calibrating in the form of material stockpiles (4) in the preform tool (5). The production of the sheet metal preform (2) is not limited to one preform tool (5), but instead depending on the complexity of the sheet metal component (3) to be produced it can be done in two or more stages or preform tools (not shown here). FIG. 2a) shows the preform tool (5) at the so-called bottom dead center. After the forming, the sheet metal preform (2) is removed from the preform tool (5), which comprises a spring back on account of an unavoidable inhomogeneous stress state introduced into the sheet metal preform (2) (FIG. 2b). In the design of the preform tool (5) compensatory measures may already be adopted in order to obtain a sheet metal preform (2) corresponding as much as possible to the final geometry. Fluctuations in the spring back are evened out in the swaging/calibrating process, so that no expensive correction grinding is required here. The same holds for fluctuations which may result from batch changes and/or wear on the preforming tools and/or the tribological properties of tools and material. The sheet metal preform (2) has for example a transverse extension (Q″) and a longitudinal extension (A″), the longitudinal extension (A″) being for example a multiple higher than the transverse extension (Q″) and being represented symbolically in the plane of the drawing.

(10) The removed sheet metal preform (2) is placed in a cutting tool (6), comprising a hold-down device (6.1) and a die (6.2). The hold-down device (6.1) and the die (6.2) are preferably designed to clamp or fix the sheet metal preform (2) between them and in particular with no further plastic shaping. The contour of the hold-down device (6.1) and the die (6.2), which contact at least in portions the base region (2.1) and frame region (2.2) of the sheet metal preform (2), correspond substantially to the contour of the preforming stamp (5.1) and the preforming die (5.2). In this way, it can be ensured that the measures implemented in the sheet metal preform (2) for the swaging/calibrating are not influenced in a negative manner in the cutting tool. Alternatively, additional plastic forming can be integrated in the cutting tool through appropriate measures, such as embossing, etc. Furthermore, the cutting tool (6) comprises cutting elements (6.3, 6.4, 6.5, 6.6) which are movable relative to the hold-down device (6.1) and/or die (6.2). The movement and/or travel of the components of the cutting tool (6) is shown symbolically by the double arrows (6.11, 6.31, 6.41, 6.51, 6.61). The sheet metal preform (2) is cut in such a way that the developed length (L) of the cut sheet metal preform (2′) in cross section is between 0.5% and 4% longer than the developed length (L′) of the finished formed sheet metal component (3). In particular, the cut sheet metal preform (2′) comprises a longer flange region (2′.3, M) than the flange region (3.3, M′) of the finished formed sheet metal component (3). At least a portion of the flange region (2′.3) is then cut off in the cutting tool (6) in a cutting or stamping process, in order to produce in this way a repeatable cross sectional development or a sheet metal preform edge (2′.31) for the following swaging/calibrating process. Four movable cutting elements (6.3, 6.4, 6.5, 6.6) are represented, which may be individually designed as cutting blades (6.3, 6.5) and movable backstops (6.4, 6.6). The number of cutting elements is not fixed at four, but instead only one cutting element can also be provided for each side, which can act in a cutting manner from above or from below on the flange region (2.3) of the sheet metal preform (2). The cut sheet metal preform (2′) has a transverse extension (Q) in cross section and possibly a longitudinal extension (A) which is smaller as compared to the transverse extension (Q″) and possibly the longitudinal extension (A″) of the sheet metal preform (2).

(11) The cut sheet metal preform (2′) removed from the cutting tool (6) still comprises a spring back, such as before it was inserted, and it is placed in a calibrating tool (7), which comprises a calibrating stamp (7.1) and a calibrating die (7.2). FIG. 4a) shows the calibrating tool (7) at the bottom dead center. Furthermore, the calibrating tool (7) comprises in particular a blocking element (7.3), which acts as an abutment on the encircling edge (2′.31) of the cut sheet metal preform (2′), in order to bring about the final geometry of the finished formed sheet metal component (FIG. 4b) close to the final form by means of compressive stress superpositioning during the swaging/calibrating. The movement and/or travel of the components of the calibrating tool (7) is shown symbolically by the double arrows (7.11, 7.21, 7.31). From the cut sheet metal preform (2′), comprising in cross section a developed length (L) between 0.5% and 4% longer than the developed length (L′) of the finished formed sheet metal component (3) and the cut sheet metal preform (2′) comprising a longer flange region (2′.3, M) than the flange region (3.3, M′) of the finished formed sheet metal component (3), a highly dimensionally accurate and flanged sheet metal component (3) is produced in the calibrating tool (7).

(12) Besides the in longitudinal extension (A′) and transverse extension (Q′), which is for example smaller by a multiple than the longitudinal extension (A′), with a base region (3.1) and a frame region (3.2) formed substantially in a same plane, comprising substantially the same height (T) on both sides FIG. 4b), offset sheet metal components (3′) can also be designed with a base region (3′.1) on different levels and with different heights (T, T.sub.1, T.sub.2) of the frame regions (3.2, 3′.2), especially in longitudinal extension (A′) on both sides (FIG. 5). Other forms, such as C-shaped sheet metal components (3″) in their longitudinal extension (A′), can also be produced in dimensionally accurate manner, especially with a flange region (3.3) (FIG. 6).

(13) In all embodiments, according to the invention the region (2.2, 2.5, 2.3) bordering directly on the sheet metal preform edge (2′.31) of the sheet metal preform (2′) which has been cut at least in portions comprises a positive dimensional deviation (M) at least for a region in the cross section with respect to the developed length (M′) of the corresponding region (3.2, 3.5, 3.3) of the finished formed sheet metal component (3, 3′, 3″) for the swaging and/or calibrating. In particular, the positive dimensional deviation (M) in the above embodiments corresponds for example in cross section (Q) to a longer flange region (2′.3) of the cut sheet metal preform (2′) with respect to the developed length (M′) of the flange region (3.3) of the finished formed sheet metal component (3, 3′, 3″).

(14) The invention is not limited to the embodiments shown. Other component shapes are likewise possible and will require suitably adapted tool contours.

LIST OF REFERENCE NUMBERS

(15) 1 Flat metal sheet 2 Sheet metal preform 2.1 Base region of the sheet metal preform and the cut sheet metal preform 2.2 Frame region of the sheet metal preform and the cut sheet metal preform 2.3 Flange region of the sheet metal preform 2.4 Transitional region between base region and frame region of the sheet metal preform and the cut sheet metal preform 2.5 Transitional region between frame region and flange region of the sheet metal preform and the cut sheet metal preform 2′ Cut sheet metal preform 2′.3 Cut flange region 2′.31 Sheet metal preform edge of the cut sheet metal preform 3, 3′, 3″ Finished formed sheet metal component 3.1 Base region of the finished formed sheet metal component 3′.1 Offset base region of the finished formed sheet metal component 3.2 Frame region of the finished formed sheet metal component 3.3 Flange region of the finished formed sheet metal component 3.4 Transitional region between base region and frame region of the finished formed sheet metal component 3.5 Transitional region between frame region and flange region of the finished formed sheet metal component 4 Material stockpile as swaging addition 5 Preform tool 5.1 Preforming stamp 5.11 Direction of movement of the preforming stamp 5.2 Preforming die 5.3 Blank holder 5.31 Direction of movement of the blank holder 5.4 Braking bead/braking bulge on the preforming die 6 Cutting tool 6.1 Hold-down device 6.11 Direction of movement of the hold-down device 6.2 Die 6.3-6.6 Cutting elements, cutting blades and backstops 6.31-6.61 Direction of movement of the cutting elements 7 Calibrating tool 7.1 Calibrating stamp 7.11 Direction of movement of the calibrating stamp 7.2 Calibrating die 7.21 Direction of movement of the calibrating die 7.3 Blocking element 7.31 Direction of movement of the blocking element A Longitudinal extension of the cut sheet metal preform A′ Longitudinal extension of the finished formed sheet metal component A″ Longitudinal extension of the sheet metal preform L Developed length in cross section of the cut sheet metal preform L′ Developed length in cross section of the finished formed sheet metal component M Positive dimensional deviation in the flange region of the cut sheet metal preform M′ Swaged/calibrated flange region Q Transverse extension of the cut sheet metal preform Q′ Transverse extension of the finished formed sheet metal component Q″ Transverse extension of the sheet metal preform T, T.sub.1, T.sub.2 Height of the frame region