Such a method is known in the prior art.
For example, DE 698 06 887 T2 discloses a method for forming a semi-finished product, wherein the semi-finished product is formed such that a thickness of the deformed semi-finished product at first decreases abruptly and then increases abruptly toward one margin of the semi-finished product.
Furthermore, DE 39 91 692 T1 and DE 10 2006 005 964 B3 each disclose a method for forming a semi-finished product, wherein the semi-finished product is formed such that a thickness of the deformed semi-finished product increases abruptly toward one margin of the semi-finished product.
Furthermore, DE 199 57 076 B4 discloses a method for perforating and forming a semi-finished product, wherein the semi-finished product in one step of the method is perforated and formed such that a thickness of the perforated and deformed semi-finished product increases abruptly toward one margin of the semi-finished product.
The cold and hot forming of high-strength steels is a major contribution to lightweight steel construction. The process chain includes, beside the actual cold or hot forming and press hardening of the component, also at least a trimming of the component and a perforating, which in the case of high material strength is done with special tools or in a laser cell. In the case of mechanical trimming or perforations, the cut quality in regard to the cut surface is oftentimes poor.
The trimming and perforation processes known in the prior art usually have the drawback that edges of the cuts and perforations are sensitive to cracks or have poor resistance to crack formation and crack propagation. This is explained, for example, in that the edges of the cuts have microscopically tiny notches. It is especially disadvantageous that the fatigue strength of components with microscopically tiny notches is relatively low under oscillatory loading. Furthermore, it is a drawback for the trimming and perforation processes known in the prior art that, owing to a limited thickness of the metal sheets, screw or rivet connections based on perforations have a greatly limited resistance to being pulled out. Hence, only slight forces can be transmitted to attachment parts.
Problems of edge cracking also occur in multi-staged forming processes known in the prior art, especially when trimming is done in the meantime. Although a multi-staged (e.g., two-staged) trimming can produce better edge qualities, the preconsolidation may nevertheless have negative effects on the fatigue strength of the edges.
One problem which the present invention proposes to solve is to provide a simple and economical method for forming a semi-finished product, wherein the deformed semi-finished product has improved mechanical properties over the prior art.
This problem is solved in that, in a solid-stock forming step, a forming region of the semi-finished product is formed such that a thickness of the deformed forming region increases continuously toward one margin of the semi-finished product.
The method according to the invention for forming a semi-finished product has the advantage over the prior art that, thanks to the continuously increasing thickness of the deformed forming region toward the margin of the semi-finished product, the mechanical properties of the deformed semi-finished product can be adjusted in an especially targeted manner. In particular, with the method according to the invention it is advantageously possible to reduce the edge crack vulnerability of the deformed semi-finished product as compared to the prior art or to increase the resistance to crack formation and crack propagation of the semi-finished product as compared to the prior art. This is accomplished in particular because the forming region of the semi-finished product is deformed in the solid-stock forming step so that a cut surface or a surface resulting from a perforation is avoided at the margin.
Furthermore, it is advantageously possible with the method according to the invention to increase the load bearing ability of the deformed semi-finished product as compared to the prior art. This is accomplished in particular in that the thickness of the semi-finished product in the area of the deformed forming region can be adjusted specifically with the method according to the invention. In this way, in particular, it is advantageously possible to attune the thickness of the deformed forming region or a variation in thickness of the deformed forming region substantially parallel to a principal plane of extension of the semi-finished product to the stress distribution presumably occurring during use of a component produced with the aid of the present invention in the area of the margin.
Thus, with the method according to the invention the edge geometry and the edge configuration can be designed such that the edge crack vulnerability is lessened and the carrying capacity is increased by making use of specific material for perforation, notching and/or edging of structural parts or sheet blanks.
With the method according to the invention, the sheet metal thickness of the edges can be increased in the desired places during the fabrication of a structural part by local material accumulation at the outer or inner edges (recesses and/or holes) of the structural part or its sheet blank. The spatial extension of the thickening is directly dependent on the excess material provided and the shaping method.
In particular, a gradual dissipation of stresses generated at the margin of the structural part in use is made possible in that the material accumulation or the thickening or the deformed forming region is configured to be reduced progressively into the surface of the structural part or away from the margin and in the direction of the center of mass of the semi-finished product.
A further benefit of the method according to the invention is that thanks to the specifically deformed forming region a calibration of the structural part produced with the method according to the invention is made possible.
According to the invention, the semi-finished product preferably consists of a high-strength steel, especially preferably of a high-strength lightweight steel.
Preferably, the forming region comprises a partial region of the semi-finished product, preferably a margin region of the semi-finished product. Furthermore, the deformed forming region preferably comprises the forming region deformed by plastic deformation (solid-stock forming).
Furthermore, the thickness is preferably an elongation of the semi-finished product substantially perpendicular to a principal plane of extension of the semi-finished product. Moreover, the thickness of the provided semi-finished product is preferably substantially constant. Moreover, the thickness of a formed semi-finished product is substantially constant, wherein the thickness is preferably an elongation of the semi-finished product substantially perpendicular to a principal surface of extension. The principal surface of extension in the provided semi-finished product runs along the principal plane of extension and in the formed and deformed semi-finished product at least partly outside the principal plane of extension.
Moreover, the margin is preferably a boundary surface, especially preferably an edge, of the deformed semi-finished product. Preferably, the margin is formed straight, convex and/or concave curved in the principal plane of extension.
Preferably the method according to the invention is carried out within a method for the fabrication of high-strength structural components with edge and/or hole reinforcements.
Advantageous embodiments and modifications of the invention can be found in the dependent claims, as well as the description, making reference to the drawings.
According to one preferred embodiment of the present invention it is proposed that the semi-finished product is secured in a fixation step. This advantageously makes it possible for the semi-finished product not to slip during a step of the method following the fixation step and at the same time, if need be, the semi-finished product is formed only outside of a fixation region of the semi-finished product during a subsequent forming of the forming region of the semi-finished product.
According to one preferred embodiment of the present invention it is proposed that the fixation step is carried out at least partly at a time after the provision step, while the solid-stock forming step is carried out at least partly at a time after the fixation step. Thus, it advantageously becomes possible to at first form the semi-finished product and then to deform it.
According to one preferred embodiment of the present invention it is proposed that the solid-stock forming step and the fixation step are carried out at least partly at the same time. This advantageously makes it possible that the semi-finished product can be secured and formed substantially within a single step of the method. This enables a reduction of the fabrication time as compared to a consecutive performing of the securing and the solid-stock forming steps and thus enables an especially economical method.
According to one preferred embodiment of the present invention it is proposed that the semi-finished product is formed in a forming step. In this way, it is advantageously possible to form the semi-finished product prior to the deforming and thus to achieve more complex geometrical shapes of a deformed semi-finished product.
According to one preferred embodiment of the present invention it is proposed that the forming step is carried out at least partly at a time after the provision step, while the solid-stock forming step is carried out at least partly at a time after the forming step. This advantageously makes possible a forming and then a deforming of the provided semi-finished product.
According to one preferred embodiment of the present invention it is proposed that the forming step is carried out at least partly at a time after the fixation step, while the solid-stock forming step is carried out at least partly at a time after the forming step. This advantageously makes it possible that the semi-finished product can be at first secured, then formed, and after the forming to be directly deformed. This advantageously avoids a further step of the method or a renewed securing (renewed fixation step) for the formed semi-finished product and thus saves time in the fabrication process.
According to one preferred embodiment of the present invention it is proposed that the fixation step and the forming step are carried out at least partly at the same time. This advantageously makes it possible that the semi-finished product can be secured and formed substantially within a single step of the method. This makes possible a reduction of the fabrication time as compared to a consecutive performing of the securing and forming steps and thus enables an especially economical method.
According to one preferred embodiment of the present invention it is proposed that the semi-finished product, preferably a fixation region of the formed semi-finished product, is secured in a renewed fixation step. Especially preferably, it is proposed that the renewed fixation step is carried out at a time after the forming step and at a time before the solid-stock forming step. The renewed fixation step advantageously makes it possible for the semi-finished product to be at least partly secured for the solid-stock forming step and thus only the forming region of the semi-finished product is deformed in the solid-stock forming step. This makes possible a plastic deforming of the forming region, without producing mechanical stresses during the solid-stock forming step resulting in a plastic deformation of the fixation region in the fixation region of the semi-finished product or introducing such stresses into the fixation region. Hence, the method according to the invention is especially advantageous as compared to the multistaged fabrication methods known in the prior art for components free of edge trimming, in which a minimum shape blank is provided, which contains a material reserve by way of additional length portions in all cross section areas and which is subjected to a compressive stress over the entire sheet blank, resulting in a slight material thickening at the flat areas of the component so produced.
According to one preferred embodiment of the present invention it is proposed that a compressive stress superimposing created in the solid-stock forming step is utilized for the calibration of the deformed semi-finished product and the rebounding of the structural part is minimized.
According to one preferred embodiment of the present invention it is proposed that the forming region of the semi-finished product is deformed in the solid-stock forming step such that the center of mass of the forming region after the solid-stock forming step is situated further in the direction of the margin than before the solid-stock forming step. This advantageously makes possible a redistribution of material of the semi-finished product from the interior of the semi-finished product toward the margin or edge.
According to one preferred embodiment of the present invention it is proposed that the forming region of the semi-finished product is deformed in the solid-stock forming step such that the center of mass of the forming region is situated further in the direction of the margin prior to the solid-stock forming step than after the solid-stock forming step. Thus, in advantageous manner, a redistribution of the material of the semi-finished product from a cut edge or from a drop-off region and toward the interior of the semi-finished product becomes possible.
According to one preferred embodiment of the present invention it is proposed that the solid-stock forming step involves a cold forming step, a warm forming step, or a hot forming step. This advantageously makes it possible that the semi-finished product can be deformed by means of cold forming, warm forming or hot forming and thus the mechanical properties of a structural part fabricated from the semi-finished product can be specifically influenced. Especially in the case of hot forming, the flow of the material prior to the hardening exhibits a greater internal homogeneity, since the method according to the invention includes at least partly a solid-stock forming. Preferably, it is also provided that the hot forming step comprises a tailored tempering step. Thanks to the combination of hot forming and tailored tempering it is advantageously possible that the solid-stock formed material can be not primarily hardened but instead recrystallization annealed at the edge or at the margin. Thus, for example, it is also proposed that the solid-stock forming step involves a recrystallization annealing step, wherein the semi-finished product, preferably the deformed forming region, is at least partly recrystallization annealed.
According to one preferred embodiment of the present invention it is proposed that the formed semi-finished product is removed from the device, preferably at a time after the forming step. According to a preferred embodiment of the present invention, it is proposed that the deformed semi-finished product is removed from the device preferably at a time after the solid-stock forming step.
A further subject matter of the present invention is a device for forming a semi-finished product, especially as by a method according to the invention, wherein the device comprises a molding tool, wherein the molding tool is designed such that a forming region of the semi-finished product can be deformed such that a thickness of the deformed forming region increases continuously toward one margin of the semi-finished product. The benefits of the method according to the invention also apply accordingly for the device according to the invention.
According to one preferred embodiment of the present invention it is proposed that the molding tool comprises a first molding tool punch and a second molding tool punch. Preferably, the first molding tool punch and the second molding tool punch are designed such that the geometrical shape or a spatial extension of the deformed forming region can be determined. Especially preferably, it is proposed that the first molding tool punch and the second molding tool punch are designed such that the spatial arrangement of the deformed forming region can be determined relative to a non-deformed region of the semi-finished product. In other words, it is preferably proposed that the thickening side can be selected by the design of the molding tools (inside/outside/middle).
According to one preferred embodiment of the present invention it is proposed that the device comprises a fixation tool, wherein the fixation tool is designed such that the semi-finished product can be secured.
A further benefit of the method according to the invention and the device according to the invention is that the stiffness of the structural part fabricated from the semi-finished product and especially of course the edge in particular is enhanced. A further benefit is that the specifically deformed forming region or the thickening makes possible the application of further shaping methods, such as thread forming or edge widening. Additional positive effects also result from the avoidance of edge crack vulnerability. For example, this enhances both the fatigue strength of the structural part and the drawability of deep-drawn parts at the limit values. Furthermore, the margin or edge is formed on hardened and preferably polished tool geometries, so that micro notching is reduced and higher (smoother and more defined) stresses are made possible.
Furthermore, the specific adjustment of the deformed forming region or the concentrated thickening at the margin or at outer edges makes it possible to increase the stiffness of the structural part produced with the method according to the invention and thus, for example, reduce the length of flanges or to omit them entirely. This can save on structural space and also make possible an especially weight-saving design. Furthermore, with the method according to the invention it is possible partially to avoid the use of shims or the welding of thickening areas at inner edges. Furthermore, it is preferably proposed that the solid-stock forming step or the thickening is carried out either before the formation of the structural part (e.g., on a sheet blank) or before the forming, i.e., in time prior to the forming step, during the formation of the structural part or during the forming, i.e., at a time during the forming step, or after the formation of the structural part or after the forming, i.e., at a time after the forming step.
Further details, features and benefits of the invention will emerge from the drawings, as well as from the following description of preferred embodiments with the aid of the drawings. The drawings only illustrate exemplary embodiments of the invention, not limiting the idea of the invention.
In the different figures, the same parts are always given the same reference number and therefore as a rule are only named or mentioned once.
In addition to the method steps shown in
In
According to the invention, preferably the molding tool 201 comprises a first molding tool punch 205 and a second molding tool punch 207. The first molding tool punch 205 and the second molding tool punch 207 here are designed so as to move against each other. Furthermore, the first molding tool punch 205 and the second molding tool punch 207 are designed so that the formed forming region 5 can be received at least partly by the first molding tool punch 205 and the second molding tool punch 207.
For example, it is provided according to the invention that the fixation tool 203 is designed so that the semi-finished product 1 can be secured. The fixation tool 203 here preferably comprises a first fixation tool punch 209 and a second fixation tool punch 211. The first fixation tool punch 209 and the second fixation tool punch 211 are designed so as to move against each other. Furthermore, the first fixation tool punch 209 and the second fixation tool punch 211 are designed so that the semi-finished product 1 can be received at least partly between the first fixation tool punch 209 and a second fixation tool punch 211.
In the following, a method according to the invention shall be described as an example with the aid of
For example, it is provided that the semi-finished product 1 formed in the forming step is removed from a first device unit of the device 200 represented in
Next, for example in another fixation step, the semi-finished product 1 is secured between the first molding tool punch 205 and the base of the molding tool 201.
Finally,
A thickening of the semi-finished product 1 or the sheet blank is advantageously possible in this case, since the semi-finished product 1 is pressed by the first molding tool punch 205 against the base of the molding tool 201 such that the semi-finished product 1 cannot slip during the solid-stock forming step 102.
As represented for example in
For example, it is provided according to the invention that the device 200 is designed as a combination tool and comprises the first device unit and the second device unit. Hence, it is advantageously possible for the thickening to be done in a combination tool. Moreover, it is preferably provided that the method according to the invention is done in a device 200 or in a tool together with a semi-finished product trimming or sheet blank trimming (but for the beveling in a different place). Preferably, it is provided that the semi-finished product trimming is done on a side of the semi-finished product 1 facing away from the margin 7.
In the following, a method according to the invention shall be described as an example with the aid of
In the following, a method according to the invention shall be described as an example with the aid of
In the following, a method according to the invention shall be described as an example with the aid of
Hence, with the sample embodiment represented in
In the following, a method according to the invention shall be described as an example with the aid of
In the following, a method according to the invention shall be described as an example with the aid of
Finally, the formed semi-finished product 1 represented in
1 Semi-finished product
3 Thickness
5 Forming region
7 Margin
100 Principal plane of extension
101 Provision step
102 Solid-stock forming step
200 Device
201 Molding tool
203 Fixation tool
205 First molding tool punch
207 Second molding tool punch
209 First fixation tool punch
211 Second fixation tool punch
213 Forming tool
215 Recess
Number | Date | Country | Kind |
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10 2016 205 492.9 | Apr 2016 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/057496 | 3/30/2017 | WO | 00 |