Sheet-metal elements made of flexibly rolled material strip

Abstract

The invention relates to sheet-metal elements made of flexibly rolled material strip having different thicknesses in the longitudinal direction of the strip. A solution according to the invention consists in a sheet-metal element reshaped about the longitudinal direction of the strip or reshaped transverse to the longitudinal direction of the strip from a flexibly rolled material strip having different thicknesses in the longitudinal direction of the strip to form a tube or profile body having an out-of-round cross-section and variable wall thickness over the length or over the circumference.

Description

[0001] The invention relates to sheet-metal elements made of flexibly rolled material strip having different thicknesses in the longitudinal direction of the strip. BACKGROUND OF THE INVENTION [0002] Flexibly rolled material strip is produced by rolling starting material having an initially constant thickness with variable roller gap thickness. Such rolling methods to produce flexibly rolled material strip and reshaping methods to produce sheet-metal elements therefrom are known from the prior art. [0003] DE-PS 104 875 describes how a strip-shaped or flat piece of sheet-metal is brought to different wall thicknesses by rolling out, and from the piece of sheet-metal having variable wall thicknesses thus obtained, a tube having different wall thickness in the longitudinal direction is bent round and soldered along the slit. [0004] From EP 0 788 849 A1 it is known to first roll a metal sheet such that parallel indentations are formed transverse to the direction of rolling, wherein the ...

AI Technical Summary

Benefits of technology

[0012] The out-of-round profile cross-section can mean uniform or symmetrical cross-sections, for example, polygonal or oval cross-sections, or also completely asymmetric cross-sections. The alternatives of a longitudinally welded closed profile or a profile which is open in cross-section are included here. The sheet-metal elements according to the first solution especially under axial loading show regionally different deformation behavior while the sheet-metal elements according to the second solution can especially exhibit different behavior under bending in different planes. Both can be specifically used for the purposes of saving weight and pre-defined deformation in longitudinal vehicle supporting members or in lateral supporting members (side impact protection).

[0018] In order to further increase the saving in weight and the differentiated deformation behavior, it can be advantageous if the sheet-metal elements are provided with punched holes in their wall surface, these preferably being produced on the flexible material strip before the reshaping to form the sheet-metal element. On the other hand, in order to increase the strength, it can be advantageous if the wall surfaces are provided with structures, for instance, indentations in a uniform grid arrangement, and this can also favorably influence the self-oscillation behavior of the sheet-metal elements.

[0023] In the sheet-metal elements hereby defined the regions of greater wall thickness running parallel to one another can also serve to increase the strength with a simultaneous saving in weight as a result of the interposed regions of smaller wall thickness. The regions of smaller wall thickness can also be used as predefined deformation regions in the event of the strength limit being exceeded. In the aforesaid spatially deformed sheet-metal elements the self-osciallaiton behavior can especially be influenced with a simultaneous saving of material.

[0027] Sheet-metal elements according to the invention as profile bodies having variable wall thickness in the longitudinal direction can especially be used as vehicle supporting members having defined graded loading or deformation behavior in the longitudinal direction in motor vehicles. In this case, a bending strength which differs over length is also appropriate when different bending loads act on the supporting members, such as a compressive or buckling strength which differs over the length for supporting members exposed to axial forces in the case of a crash. In addition, sheet-metal elements with said properties can also be used as impact absorbers having defined graded deformation behavior in the longitudinal direction. A design based on controlled axial shortening in the case of a crash is hereby made possible.

[0028] According to another proposal, sheet-metal elements according to the invention as profile bodies having variable wall thickness in the circumferential direction can also be used as vehicle supporting members having defined graded deformation behavior or buckling behavior over the circumference. In this case, a higher geometrical moment of inertia is to be provided in the main bending plane of the supporting member while a lower geometrical moment of inertia can be provided in the bending planes exposed to lower loading in order to save material.

[0030] Flat sheet-metal elements according to the invention can also be used as bodywork outer panels, where cross-pieces having greater wall strength can also take on the function of beads or grooves with regard to increased form stability. In this case, even a specific reinforcement of the structure can be brought about for the case of a side-on crash.

Problems solved by technology

When manufacturing sheet-metal elements from material having uniform wall thickness, the areas exposed to lower loading are thus over-dimensioned and result in excessive weight of the component.

This is especially undesirable in vehicle construction.

Images