Patent Application
20100203272
This application claims the priority of German Patent Application, Serial No. 10 2009 007 901.7, filed Feb. 6, 2009, pursuant to 35 U.S.C. 119(a)-(d), the contents of which are incorporated herein by reference in its entirety as if fully set forth herein.
The present invention relates to a method for producing a motor vehicle component, which has a tubular body made of metal with an interior reinforcement, and a motor vehicle component of this type.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Lightweight components intended reduce the weight of a motor vehicle by as much as possible have become increasingly important in the construction of motor vehicles. Such lightweight components must be amenable to a continuous, dimensionally-stable series production and must have high stiffness and structural stability in order to withstand the high static and, in particular, dynamic loading which motor vehicle components are subjected during operation. Motor vehicle components are predominantly manufactured from sheet steel or structural sheet steel or steel tubes. Weight can be reduced by employing structural components that have thinner walls compared to conventional motor vehicle components. Components with thinner walls, however, may not be able to attain the desired stiffness and stability values. It has therefore been proposed, for example in DE 199 59 814 B4 or U.S. Pat. No. 4,978,562, to fill vehicle components with foam and to thereby provide these components with an interior coating.
U.S. Pat. No. 7,083,751 B2 discloses a method for producing a motor vehicle component having a tubular body made of metal with an interior reinforcement. The tubular body is filled with two granular components and subsequently heated, whereby the granular material subsequently hardens due to the melting and expansion of the granular components, thereby forming the interior reinforcement.
DE 196 35 734 A1 discloses a reinforced formed part and a method for producing a formed part, wherein the formed part includes an outer hollow formed part in which a foam filling is introduced. The foam filling hereby at least partially contacts and at least partially fills the outer formed part.
DE 600 18 612 T2 discloses a method for forming a reinforced structural component. An outer structural component is here paired with an inner structural component by insertion into an opening. The periphery of the inner structural component is already coated with structural foam. The produced assembly is reformed by hydroforming and subsequently heated to cause expansion of the structural foam between the outer and the inner structural components.
The aforedescribed solutions are quite acceptable. All the aforedescribed methods are intended to increase the stiffness and stability of the components by way of interior reinforcement. In addition to cold-foaming, possibilities are discussed for subsequently activating the form by applying heat after the component is formed and structured.
However, it would still be desirable and advantageous to obviate prior art shortcomings by providing a method by which a motor vehicle component with a tubular body having an interior reinforcement can be produced more economically and cost-effectively.
According to one aspect of the present invention, a method for producing a motor vehicle component having a thin-walled tubular body made of metal, includes the steps of filling the tubular body with a granular material, heating the filled tubular body concurrent with a tempering process of the tubular body to cause the granular material to melt, and cooling the filled tubular body to cause the granular material in the filled tubular body to solidify and harden, and form an interior reinforcement of the tubular body.
This approach is cost effective and economical. The method allows the manufacture of lightweight motor vehicle components with a thin wall outer skin made of steel and an interior reinforcement which is also lightweight. Overall, the invention provides potentially large weight reductions. The produced motor vehicle components additionally have high fatigue strength and buckling resistance with a component-specific deformation characteristic and small risk of fracture.
Embodiments of the invention may include one or more of the following features.
The granular material may be melted in the tubular body by applying heat to the filled tubular body in the course of a tempering process, where the tubular body is heated to a temperature above 900° C. and subsequently cooled down.
The granular material may be introduced into a tubular body made of metal as a loose bulk material. The pourable granular material is easily distributed in the tubular body. The ends of the tubular body may be closed off during the filling operation or after the tubular body has been filled with granular material. The tube ends can be flattened. Alternatively, the tube ends can be closed off with plugs. Bores can be introduced in the flattened tube ends, which can later be used to attach the motor vehicle component to the structure of a vehicle with screw. When plugs are used to close the tube ends, the plugs can already have threaded bores, for example formed in blind holes, by which the motor vehicle components can be screwed together.
The tubular bodies as well as the flattened tube ends and/or the plugs can also be provided with additional support elements or attachment parts.
The interior reinforcement formed by the hardened melt can completely fill the tubular body. However, the interior reinforcement may fill the tubular body only partially, in particular by forming an interior layer contacting the inner wall of the tube body which can optionally be attached to the inner wall by an adhesive. Advantageously, the tubular body may be moved, in particular rotated about its longitudinal axis, while the granular material hardens, to produce a uniform distribution of the melt on the inner wall of the tubular body.
Advantageously, a thin-walled tubular body made of steel, in particular made of high-strength steel, may be used.
The granular material may be composed of plastic, lightweight metal, in particular aluminum, or cellulose. Other granular materials which can form a melt and have sufficiently high rigidity after solidification or hardening can also be employed.
According to another aspect of the present invention, a motor vehicle component includes a tubular body made of metal and having flattened sections, and an interior reinforcement made of a granular material. The interior reinforcement is produced by filling the tubular body with a granular material, heating the filled tubular body concurrent with a tempering process of the tubular body to cause the granular material to melt, and solidifying and hardening the granular material in the filled tubular body.
According to yet another aspect of the present invention, a motor vehicle component includes a tubular body made of metal and having tube ends, a plug inserted in each of the tube ends, wherein each plug has a blind hole with an internal thread and closes off a respective tube end, and an interior reinforcement made of a granular material. The interior reinforcement is produced by filling the tubular body with a granular material, heating the filled tubular body concurrent with a tempering process of the tubular body to cause the granular material to melt, and solidifying and hardening the granular material in the filled tubular body.
Examples of such motor vehicle components are door reinforcements, side impact supports, bumper cross beams, and bumper-, A-, B- or C-column reinforcements as well as rocker panel reinforcements.
According to the invention, the tubular body has flattened end sections, in which bores may be inserted to provide a screw connection. The end sections may also be provided with supports or attachment parts. The interior reinforcement provides the thin wall tubular component, which is preferably made of high-strength steel, with increased rigidity and dimensional stability. A further weight reduction can thus be attained. The motor vehicle component has nevertheless excellent deformation characteristics and is flexible in the event of a crash and has a small risk of fracture, in particular of the reinforcement.
According to another embodiment of the motor vehicle component, the tube ends of the tubular body may be closed off by blind holes having an internal thread. The motor vehicle component can be attached with screws engaging in the threaded bores.
Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:
Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.
Turning now to the drawing, and in particular to
In the embodiment depicted in
The tubular body 1 filled with granular material 2 is subjected to heat treatment in the course of a tempering process, whereby the granular material 2 melts and subsequently hardens during cool-down to form an interior reinforcement 11.
In the exemplary embodiment of a motor vehicle component 12 illustrated in
In the motor vehicle component 13 according to
While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 007 901.7 | Feb 2009 | DE | national |
