Abstract
The disclosure relates to a downholding press for producing a semi-finished product from sheet-metal material having thickness-reduced regions, wherein the semi-finished product after forming has regions with mutually dissimilar wall thicknesses and the downholding press has an upper tool and a lower tool as well as a downholding element, and a convexity on the sheet-metal material is generated between the upper tool and the lower tool such that the sheet-metal material is reduced in thickness in regions by elongation, wherein a blocking cam is configured on the downholding element in such a manner that a follow-on of the sheet-metal material is impeded.
Claims
1. A downholding press for producing a semi-finished product from sheet-metal material having thickness-reduced regions, wherein the semi-finished product after forming has regions with mutually dissimilar wall thicknesses, the downholding press comprising: an upper tool; and a lower tool; and a downholding element, wherein the upper tool and the lower tool are configured to generate a convexity on the sheet-metal material between the upper tool and the lower tool such that the sheet-metal material is reduced in thickness in regions by elongation, and wherein a blocking cam is configured on the downholding element to suppress a follow-on of the sheet-metal material.
2. A downholding press according to claim 1, wherein the blocking cam is configured on the downholding element so as to project in relation to the downholding element, and/or a further blocking cam is configured on the lower tool so as to project in relation to the lower tool.
3. A downholding press according to claim 1, wherein a blocking seam is configured on or in a bearing face (10) that lies opposite the downholding element, and the blocking cam of the downholding element in the converging of the downholding press engages in the blocking seam.
4. A downholding press according to claim 1, further comprising: two further blocking cams configured on a bearing face that lies opposite the downholding element, wherein the blocking cam of the downholding element in the converging of the downholding press engages between the two further blocking cams while enclosing the sheet-metal material.
5. A downholding press according to claim 3, wherein the blocking cam and the blocking seam have mutually complementary geometries.
6. A downholding press according to claim 1, wherein the blocking cam runs along a straight line or an arcuate line.
7. A downholding press according to claim 1, wherein the blocking cam of the downholding element in a press stroke direction projects to come to bear on the sheet-metal material ahead of the upper tool.
8. A downholding press according to claim 1, wherein the blocking cam in cross section has a rounded contour, or the blocking cam in cross section has an angular contour.
9. A method of producing a sheet-metal formed part having mutually dissimilar wall thicknesses, the method comprising: providing a sheet-metal material having a wall thickness; preforming the sheet-metal material to a semi-finished product as a preform by way of a downholding press, wherein at least one convexity is generated in an internal region of the sheet-metal material such that the material is elongated and has a reduced wall thickness, wherein a downholding element is disposed externally on the internal region, said downholding element having at least one blocking cam such that the sheet-metal material is jammed by the downholding element and does not continue to flow in from the outside; flattening and/or spreading the perform, wherein the sheet-metal material is singularized to a blank before, during, or after said preforming; and forming the blank to the sheet-metal formed part.
10. A method according to claim 9, wherein the at least one convexity comprises two convexities that are oriented in opposite directions in relation to the original plane of the sheet-metal material, or two convexities that are oriented in the same direction, or an undulated shape having a plurality of undulations.
11. A method according to claim 9, wherein the convexity extends across the entire width of the sheet-metal material, or the convexity extends across a partial width of the sheet-metal material.
12. A method according to claim 9, wherein the blocking cam engages in the sheet-metal material by a penetration depth which is smaller than or equal to 10% of the wall thickness of the sheet-metal material.
13. A downholding press according to claim 4, wherein the blocking cam and a space between the two further blocking cams have mutually complementary geometries.
14. A method according to claim 9, further comprising: trimming and/or perforating the blank.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] For an understanding of embodiments of the disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:
[0037] FIG. 1 shows the forming process according to the disclosure;
[0038] FIG. 2 shows a downholding press according to the disclosure;
[0039] FIG. 3 shows a downholding press according to the disclosure, having two downholding elements, in which downholding press two regions of a sheet-metal material are simultaneously reduced in thickness;
[0040] FIGS. 4a to 4c show the production process on a downholding press according to FIG. 2;
[0041] FIG. 5 shows an embodiment of a downholding press to that of FIG. 1; and
[0042] FIGS. 6a to 6c show mutually dissimilar contours of the blocking cam and blocking seam;
[0043] FIG. 7 shows blocking cams when engaged on a sheet-metal blank;
[0044] FIG. 8 shows a downholding press according to the disclosure;
[0045] FIG. 9 shows a detailed view of FIG. 8;
[0046] FIGS. 10a and 10b show a preform produced according to the disclosure, as well as the preform after a flattening procedure has been carried out;
[0047] FIGS. 11a and 11b show an integral support produced according to the disclosure, having two intermediate regions having a reduced wall thickness; and
[0048] FIGS. 12a to 12c show respective downholding elements in plan view.
DETAILED DESCRIPTION
[0049] FIG. 1 shows a sheet-metal material 1, in relation to the image plane above in a lateral view and to the image plane below in a perspective view. Said sheet-metal material 1 having a consistent wall thickness W in a first method step is placed into a downholding press 2, wherein the downholding press 2 on two mutually opposite sides has in each case one downholding element 3. By impinging the downholding elements 3 with an increased downholding pressure in relation to a counter bearing, a convexity 4 which leads to an extension in length of the original length L of the sheet-metal material 1 is generated on the sheet-metal material 1 between the upper tool 11 and the lower tool 9 in a further closing. It can be readily seen in the lower image plane that the convexity 4 is configured so as to extend across the entire width B of the sheet-metal material 1. Said convexity 4 can also be configured so as to be only partially across the width B. The material flowing into the length modification requires a reduction in the wall thickness W1 in the region of the convexity 4 in relation to the original wall thickness W, consequently of the initial wall thickness.
[0050] In a further method step, a compression forming tool 5 is shown here in which the produced preform 6 is flattened and thus a blank 7 having a central elongated region 16 having a reduced wall thickness W1 is produced. Said blank 7 has a length L1, wherein the length L1 is longer than the length L, and the wall thickness W1 in the elongated region is smaller than the wall thickness W of the original sheet-metal blank 1, said wall thickness W still being present in the respective peripheral region, or in the non-preformed regions of the blank 7, respectively. The flattening is performed as crash forming such that no further centering or adjustment is required. In the shaping to be produced later in a forming tool (not illustrated in more detail here) self-centering in the forming tool can be performed by virtue of the transition in thickness, or else by virtue of the convexity (preform), from the elongated regions having a reduced wall thickness W1 to regions having a regular wall thickness W.
[0051] FIG. 2 now shows a downholding press 2 according to the disclosure, in which two blocking cams 8 are disposed in the downholding element 3 per se. A bearing face 10 that lies opposite the downholding element 3 is provided in the lower tool 9, said bearing face 10 likewise having a blocking cam 8. In the closing of the downholding press 2 in the press stroke direction 12 the region of the sheet-metal material 14 initially comes to bear between the blocking cams 8 and is jammed here. Subsequently, a convexity 4 is generated by a respective shape-imparting geometry between the upper tool 11 and the lower tool 9. The sheet-metal material 14 herein in the region of the convexity 4 to be produced is elongated and the wall thickness W1 is reduced herein. A semi-finished product 13 thus produced is likewise illustrated in FIG. 2, or is identified by the reference sign 6 as a preform in FIG. 1, respectively.
[0052] FIG. 3 shows an embodiment, analogous to the construction of FIG. 2, wherein two convexities 4 are simultaneously produced on a sheet-metal material 14 here. A total of four downholding elements 3 are thus configured on the upper tool 11 illustrated here, each having a respective blocking contour. The sheet-metal material 14 in FIG. 1 is identified by the reference sign 1.
[0053] FIGS. 4a to 4c show the production process according to the disclosure on a downholding press according to FIG. 3. A sheet-metal material 14 which has a consistent wall thickness W is first provided. Said sheet-metal material 14 is placed into the downholding press 2 according to FIG. 3. A semi-finished product 13 having two convexities 4, as is shown in FIG. 4b, is subsequently produced. Blocking geometries 15 generated in the peripheral region of the convexity 4 are in each case shown enlarged. Furthermore, a thickness transition region 22 is also present toward the convexity 4 here. In a subsequent flattening or spreading, respectively, of the semi-finished product 13 a blank 7 which has a length L1 which is larger than the length L of the sheet-metal material 14 is then produced, said blank 7 also having regions having mutually dissimilar wall thicknesses. The wall thickness W1 is smaller or thinner, respectively, in relation to the wall thickness W of the sheet-metal material 14. On account thereof, elongated regions 16 having a smaller wall thickness W1 are produced.
[0054] FIG. 5 shows a further embodiment of the downholding press 2 according to the disclosure. The downholding element 3 here is disposed so as to be separate from the upper tool 11 and the lower tool 9. A bearing face 10 on the opposite side of the downholding element 3 is likewise disposed on a separate tool. This offers the advantage that the downholding element 3 in the press stroke direction 12 can be repositioned separately from the upper tool 11. On account thereof, the degrees of freedom in the production of an elongated semi-finished product 13 as a preform are enhanced.
[0055] FIGS. 6a to 6c show mutually dissimilar embodiments of the blocking cam 8 according to the disclosure on a downholding element 3. According to FIG. 6a, the blocking cam 8 is configured so as to project in the press stroke direction 12 in relation to the downholding element 3, or to a surface 18 of the downholding element 3, respectively. The blocking cam 8 here comes to bear on a planar bearing face 10, for example of the lower tool 9, while enclosing a sheet-metal material (not illustrated in more detail). The blocking cam 8 consequently is impressed into the sheet-metal material at least in regions and prevents a continuing flow of the sheet-metal material in the elongation direction 19. The elongation direction 19 here is illustrated toward the right in relation to the image plane.
[0056] FIG. 6b shows a further embodiment. The blocking cam 8 here is likewise configured so as to project in relation to the surface 18 of the downholding element 3. A blocking seam 17 is configured so as to be depressed in relation to a bearing face 10. The blocking cam 8 in the closed state, as is illustrated in FIG. 6b, thus engages in the blocking seam 17 and forms a mold cavity 20 lying therebetween, in which the sheet-metal material is enclosed. The corner or edge, respectively, that is oriented in the elongation direction 19 is configured as a rounded edge 21. A constriction of the sheet-metal material 14 is avoided on account thereof.
[0057] FIG. 6c shows a further embodiment. The blocking cam 8 and the bearing face 10 here are configured as an undulated region. The bearing face 10 per se is likewise configured by two blocking cams 8. Clamping is performed on account of this contour, but there is simultaneously no risk of excessive elongating or kinking arising in the region of a corner.
[0058] FIG. 7 shows a schematic illustration of a downholding press 2 according to the disclosure. Part of a sheet-metal blank 1 is placed herein, and blocking cams 8 emanating from above and below are disposed. The blocking cams 8 in each case by way of a height 23 or penetration depth, respectively, engage in the sheet-metal blank 1. The height 23 herein is smaller than or equal to 10% of the wall thickness W of the sheet-metal blank 1. Sheet-metal blanks having a wall thickness from 1 to 8 mm can be processed by way of the method according to the disclosure. Sheet-metal blanks having a wall thickness from 1 to 3 mm are processed. Despite the minor penetration depth of the blocking cams 8, a sufficient holding force is however generated, such that a successive feed or a continuing flow, respectively, from the outside is suppressed. Sheet-metal blanks, having a wall thickness of more than 3 mm, can thus also be partially reduced in thickness, for example.
[0059] FIG. 8 shows a downholding press 2 according to the disclosure. The downholding press 2 has an upper tool 11 as well as a lower tool 9. Downholding elements 3, also referred to as sheet-metal holders, are disposed on the outside. The blocking cams 8, for example according to FIG. 7, are in each case configured on the left and the right in relation to the image plane. This can be seen in an enlarged illustration in FIG. 9. When a sheet-metal blank 1 is placed therein and the lower tool 9 is still opened in the press stroke direction 12, as is not illustrated here, the sheet-metal blank 1 bears between the upper tool 11 and the downholding element 3. The undulated shape illustrated here of the upper tool 11 for producing convexities on the sheet-metal blank 1 herein do not yet engage in the as yet flat sheet-metal blank 1. If the lower tool 9 is now closed in the press stroke direction 12, the undulated geometry 24 illustrated in FIG. 8 is generated. A successive feed of the sheet-metal blank 1 from the outside is completely suppressed by the blocking cams 8. This means that the region obtained between the blocking cams 8 illustrated on the left side and the right side in FIG. 8 is elongated and on account thereof reduced in thickness by generating the undulated geometry 24 and the convexities associated therewith.
[0060] The preform thus produced is illustrated in FIG. 10. Undulated convexities 4 are produced such that a reduced wall thickness W1 is produced here. In each case one embossing 25 by virtue of the blocking cams 8 is present on the left and the right side. This embossing 25 can however be neglected, or concavities or embossings 25 will hardly remain in the case of the flattened blank 7 in FIG. 10b. The original wall thickness W is in each case present outside the embossings 25.
[0061] FIGS. 11a and 11b show a component produced according to the disclosure in the form of an integral support, or of a spring bridge 26, which is used in the case of an axle subframe. The spring bridge is illustrated in a perspective view and in a lateral view. This component in cross section is configured so as to be hat-shaped.
[0062] Two intermediate portions 27 are configured in the spring bridge 26, wherein the reduced wall thickness is produced in the intermediate portions 27. The original wall thickness is present in a respective end portion 28 as well as in a central portion 29. An elongation by way of blocking cams 8 is carried out herein in a downholding press 2 according to the disclosure, wherein blocking cams 8 are in each case disposed to the left side and to the right side of the intermediate portion 27 such that the wall thickness here is elongated by the convexity and thus reduced in thickness.
[0063] FIGS. 12a to 12c show a respective downholding element 3 in plan view, having blocking cams 8 that run in a linear manner. The blocking cams 8 which, for example in FIG. 7, are shown in cross section are illustrated in a plan view here. In the longitudinal direction 30 of the blocking cams 8 the latter according to FIG. 12a extend in a linear manner as a straight line. The line extends across a depth or width 31, respectively, of the downholding element 3. According to FIG. 12b, the lines can also be configured so as to be undulating or meandering. The effective length of the blocking cam 8 is enlarged on account thereof, and the holding force is in turn increased on account thereof. According to FIG. 12c, it would also be conceivable for the blocking cam 8 in the longitudinal direction 30 thereof to be configured only in portions.
[0064] The foregoing description of some embodiments of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings. The specifically described embodiments explain the principles and practical applications to enable one ordinarily skilled in the art to utilize various embodiments and with various modifications as are suited to the particular use contemplated. It should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the disclosure.
