Method and device for producing sheet-metal components

Abstract

A method for producing dimensionally highly accurate sheet-metal components is provided. A blank is formed to a preformed part, wherein the preformed part in the cross section at least in regions has an excess developed length. The preformed part is calibrated in regions to a calibrated part while at least in regions using the excess developed length of the cross section of the preformed part, wherein the preformed edges of the preformed part during the calibrating are at least in regions disposed so as to be free of any form-fit. The calibrated part is trimmed at least in regions after the calibrating, in order for the sheet-metal component (60) to be produced. A device for producing dimensionally highly accurate sheet-metal components is moreover described.

Claims

1. A method for producing sheet-metal components, the method comprising: forming a blank to a preformed part wherein the preformed part in a cross section at least in regions has an excess developed length; calibrating, including a compressing at least in a vertical wall region of the preformed part to a calibrated part while at least in part using the excess developed length of the cross section of the preformed part for building up additional compressive stresses, wherein preformed edges of the preformed part during the calibrating are at least in regions disposed so as to be free of any form-fit; and trimming at least in regions the calibrated part after the calibrating, in order for the sheet-metal component to be produced, wherein the method, from forming the blank until trimming the calibrated part after calibrating, is carried out without any trimming, wherein regions that are at least in regions calibrated are removed by the trimming of the calibrated part after the calibrating.

2. The method as claimed in claim 1, wherein the calibrated part has a flange region, and the trimming of the calibrated part comprises a partial removal of the flange region.

3. The method as claimed in claim 1 wherein an undesirable material flow in a direction of the preformed edges of the preformed part during the calibrating is at least in regions reduced or suppressed by means of a decelerating effect on at least one of the sheet-metal upper side and the sheet-metal lower side.

4. The method as claimed in claim 3, wherein the material flow when forming the blank to the preformed part is at least in regions decelerated.

5. The method as claimed in claim 4, wherein at least one of a draw bead, at least one draw shoulder and multi-stage forming are used when forming the blank to the preformed part.

6. The method as claimed in claim 1, wherein the forming of the blank to the preformed part already comprises compensation measures aimed at producing a geometry of the preformed part that has a resemblance to the final geometry.

7. The method as claimed in claim 6, wherein the excess developed length is in at least one of a base region of the preformed part, in the vertical wall region of the preformed part, in an optional flange region of the preformed part and in at least one transition regions therebetween.

8. The method as claimed in claim 1, wherein the sheet-metal component, when viewed in the cross section, is at least in portions configured so as to be hat-shaped.

9. The method as claimed in claim 1, wherein the sheet-metal component along a main extent thereof has cross-sectional variations.

10. A device for producing sheet-metal components, for carrying out a method as claimed in claim 1, having forming means for forming a blank to a preformed part in such a manner that the preformed part in the cross section at least in regions has an excess developed length; calibrating means for at least in regions calibrating, including a compressing at least in a vertical wall region of the preformed part to a calibrated part while at least in part using the excess developed length of the cross section of the preformed part for building up additional compressive stresses in such a manner that the preformed edges of the preformed part during the calibrating are at least in regions disposed so as to be free of any form-fit; and trimming means for at least in regions trimming the calibrated part after the calibrating, in order for the sheet-metal component to be produced, wherein the trimming means comprises at least one trimming tool for trimming the calibrated part after the calibrating.

11. The device as claimed in claim 10, wherein the forming means comprise a preforming tool having a preforming ram, and a preforming die.

12. The device as claimed in claim 10, wherein the calibrating means comprise at least one calibrating tool having at least one calibrating ram and at least one calibrating die.

13. The device as claimed in claim 11 wherein the performing tool includes a sheet-metal holder.

14. The device as claimed in claim 13 wherein the performing tool includes at least one draw shoulder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is to be explained in more detail hereunder by means of exemplary embodiments in conjunction with the drawing in which:

(2) FIG. 1 shows an exemplary embodiment of a preforming tool for carrying out a forming step;

(3) FIG. 2 shows an exemplary embodiment of a preformed part springing back after the preforming;

(4) FIGS. 3a,b show an exemplary embodiment of a calibrating tool for carrying out a calibrating step;

(5) FIGS. 4a,b show further exemplary embodiments of calibrating tools for carrying out a calibrating step;

(6) FIG. 5 shows an exemplary embodiment of a calibrated part; and

(7) FIG. 6 shows an exemplary embodiment of a sheet-metal component after the trimming.

DETAILED DESCRIPTION

(8) First, FIG. 1 shows an exemplary embodiment of a preforming tool 1 in order for a forming step according to one exemplary embodiment of a method according to the invention to be carried out. The preforming tool 1 comprises a preforming ram 2 and a preforming die 4. Moreover, an optional blank holder 6 which can be disposed, for example, on the slide cushion or springs is illustrated. The preforming tool 1 moreover has sheet-metal holders 8 having draw beads 8a. Moreover, draw shoulders 9 are provided. The blank in FIG. 1 has already been formed to the preformed part 10 by deep-drawing.

(9) The blank herein has been formed in such a manner that the geometry of the preformed part 10, having a material reserve included in the base region and/or in the wall region and/or in the flange region and/or in a transition regions between the base region and the wall region and/or the wall region and the flange region, corresponds to the geometry at least required for the subsequent calibrating step.

(10) The preformed part 10 thus established is distinguished in that the developed length of the preformed part 10 in the cross section at least in regions is larger than required for the subsequent calibrating. Commonplace auxiliary means such as the draw beads 8a or the draw shoulders 9 are thus also possible in the production of the preformed part 10. In the case of particularly critical components, it is also conceivable for the preformed part 10 to be implemented in a plurality of forming stages. The previously existing limits in the production of a suitable preformed part 10 are significantly extended in this way. It is also conceivable for the preformed part to be produced in a plurality of forming stages of different combinations of drawing, bending, embossing, edge-bending, etc.

(11) The preformed part 10, as a result of the inhomogeneous stress state, will spring back when retrieved from the preforming tool 1, as is illustrated in FIG. 2. The retrieved preformed part 10 (formed part) is then received in a calibrating tool 20 which reproduces the desired final geometry plus the material addition in the region of the preformed edge, as is illustrated in FIGS. 3a, 3b. The calibrating tool 20 comprises a calibrating ram 22, a calibrating die 24, and blank holders, or sheet-metal holders 26, respectively, suspended from above.

(12) Alternative exemplary embodiments of calibrating tools 30, 40 for carrying out the calibrating step are illustrated in FIGS. 4a, b. The calibrating tool 30 is embodied as a two-part tool having a calibrating ram 32 and a calibrating die 34. A blank holder can be dispensed with in this case. The calibrating tool 40 comprises a calibrating ram 42, a calibrating die 44, blank holders 46 suspended above. The flange region of the preformed part 10′ in this case formed without a shoulder.

(13) The preformed part 10, 10′ (formed part) during the calibrating procedure is fixed in the calibrating tools 20, 30, 40 described such that a flow of the material in the direction of the preformed edge is suppressed during the calibrating. However, the preformed edges of the preformed part 10, 10′ are at least in regions disposed so as to be free of any form-fit during the calibrating in said tools 20, 30, 40. The preformed part 10, 10′ is thus completely or at least in portions calibrated without the preformed edge being prevented in a form-fitting manner from yielding. An undesirable outward material flow in the direction of the preformed edge herein is achieved only by way of the decelerating effect on the sheet-metal upper side and the sheet-metal lower side, but not by way of a decelerating effect on the preformed edge.

(14) No trimming of the preformed part 10, 10′, or of the calibrated part, respectively, has taken place up to this point in time. In the case of the calibrated part being created, this means that the trimming waste to be later removed by means of trimming (for example by means of edge trimming) is first at least in part conjointly calibrated in the calibrating tool 20, 30, 40. A dimensionally accurate calibrated part which is then finally trimmed in order to thus achieve the final sheet-metal component is achieved in this manner.

(15) Compensation measures such as, for example, over-bending of the walls, can already be taken in the design of the preforming tool 1 so as to obtain a preformed part 10, 10′ which already corresponds as well as possible to the final geometry. Variations in the spring-back of the preformed part 10, 10′ are largely equalized when calibrating, so that no complex correction loops are required here either. The same applies to variations which result from batch change and/or wear of the preforming tools and/or the tribological properties of tools and material.

(16) An exemplary embodiment of a calibrated part 50 which has been produced from the preformed part 10 is illustrated in FIG. 5. The region to be severed is indicated in an exemplary manner by the dashed lines 52. The trimming performed after the calibrating can be carried out in one or a plurality of steps and has in particular the advantage that the trimming tools do not have to be adapted to the component sprung-back, as is current practice, but can instead be embodied so as to be close to the nominal geometry. However, in principle it is likewise conceivable for the edge-trimming to be integrated into the calibrating tool 20, 30, 40 when the lower terminal position is reached (not illustrated here).

(17) A sheet-metal component 60 having the final dimension, which has been produced from the calibrated part 50 by edge-trimming, is illustrated in FIG. 6.

(18) Summarizing, the following advantages can in particular be derived from the various exemplary design embodiments of the method described and of the device described.

(19) In terms of the blank to be initially provided, a simplified contour of the cutting blades and less wear can result. Moreover, simplified nesting can result since only one blade contour is usually required.

(20) In terms of the forming of the preformed part 10, 10′, complex components which to some extent are capable of being implemented only by way of forming with auxiliary means such as sheet-metal holders 8, draw beads 8a, draw shoulders 9 and/or by way of multi-stage forming, can in particular be produced. Moreover, the solidification of modern multiphase steels can be exploited herein. This in turn can to reduced sheet-metal thicknesses and thus to a reduced component weight, in particular in comparison with a process management using embossing and raising, at comparable component performances. Finally, regions at risk of edge fissures can be reduced or avoided.

(21) In terms of the calibrating it can be advantageously achieved, in particular independently of the batch and by way of a reliable process, that the position of the preformed edges in the calibrating tool 20, 30, 40 that is closed until shortly prior to the beginning of the compressing and/or calibrating process does not have any influence on the calibrating effect. This means that the preformed part 10, 10′ can be designed in an optimal manner without considering the final sheet-metal component edge for the calibrating step. A classic compensation by means of over-bending or truing can likewise be dispensed with, wherein the classic compensation can in principle also be combined with the method described. It can likewise be advantageous that high surface pressures in the region of the preformed edges that are supported on the tool can no longer be formed by the disposal of the preformed edges in the calibrating tool that is at least in regions free of any form-fit during the compressing and/or calibrating process, and the service life of the calibrating tool can thus be increased.

(22) In terms of the edge-trimming of the calibrated part 50 to the final dimension, known trimming methods that have been tested in volume production can be used and be optionally combined with protrusions and/or perforations required.