This invention relates to a method of reinforcing a hollow section having a closed periphery.
A method or device of this general type is known from German document DE 100 29 467 C1. In the known method, an opening is created on a finish-formed hollow section, after which a reinforcing component is introduced into the hollow section interior through the opening produced. The reinforcing component is then welded to the opening edge on the one hand and to the hollow section wall opposite the opening on the other hand. The known method involves some effort. Thus, the reinforcing component must be aligned exactly relative to the hollow section, then inserted and held in its position during the joining operation.
The object of the invention is to develop a method of the type mentioned in which the hollow section is reinforced as easily as possible. Furthermore, a device with which the reinforcement is achieved is to be shown. The object is achieved according to the invention by the claimed method and by the claimed device.
Thanks to the invention, no additional component is necessary in order to provide the reinforcing component. On the contrary, the reinforcing component is formed from the material of the hollow section itself, to be precise by the wall piece which is cut out for forming the opening. However, this wall piece is only cut out up to a peripheral region, so that the reinforcing component formed by said wall piece does not fall into the hollow section interior and is advantageously held in a defined position by the hollow section itself after the perforating punch plunges into the hollow section interior, during which the wall piece is bent into the latter. All holding and clamping devices for the reinforcing component with regard to the subsequent joining operation can therefore be dispensed with. The reinforcing component, that is to say the wall piece, is introduced into the hollow section interior in an extremely simple manner by bending over the wall piece by means of the perforating punch, which has to plunge into the hollow section interior anyway in order to perforate or cut out the wall piece. To this end, it is merely necessary to specifically design the end face of the punch, so that the punch does not cut out the complete periphery of the wall piece, a bending contour formed on it carrying out the bending operation during the plunging of the punch. Since the reinforcing component according to the invention, with one end, is already connected in one piece to the hollow section, the effort involved for joining it there to the hollow section can be dispensed with. In this case, only one joining device is required, by means of which the free end of the wall piece, which projects into the hollow section interior, can be joined to the opposite hollow section wall. It may be noted at this point that the method according to the invention can only fulfill its function when the distance between the opening on the hollow section and the opposite hollow section wall is equal to or less than the length of the cut-out wall piece. That is to say that the free end of the wall piece must come into contact with said hollow section wall at least in a right-angled bent form. In the method according to the invention, hollow sections can therefore be specifically reinforced locally and can thus be adapted individually to different loading profiles. On the whole, the local rigidity of hollow sections, in particular of components formed by internal high pressure, can be increased by the invention without additional use of material. The finish-formed and reinforced component is in this case more rigid at the same weight. In addition, the net output is increased by the integration in the internal high pressure forming process. Additional production steps can be dispensed with, as can additional components.
In an especially preferred development of the invention, the wall piece is oversize with regard to its length relative to the width of the hollow section. The wall strip projecting here is bent over inside the hollow section by means of a punch plunging into the opening and is brought to bear against the hollow section wall in such a way as to conform to the contour, after which this wall strip is joined to the hollow section wall. On account of the essentially larger dimensions of available joining area compared with point or linear contact by the wall strip, firstly the joining operation is facilitated and the hold, resulting from the joining operation, between the reinforcing component and the hollow section is considerably increased when the available joining area is fully utilized. Furthermore, to carry out the joining, joining methods may also be used which would not have been advisable with the reinforcing component only in abutting contact with the hollow section wall on account of a lack of functionality. To this end, the end face of the perforating punch is to be designed with a cutout which extends from the bending contour in the direction of the cutting edge and has in its depth at most the wall thickness of the wall piece and corresponds in its contour essentially to the wall strip which is to be bent over, so that the latter can be readily folded by the perforating punch and pressed against the hollow section wall. This is expressed in the preferred development of the device according to the invention.
In a further, especially preferred configuration of the invention, the joining operation is effected by means of press joining. In this special joining method, the wall strip can be fastened to the hollow section wall especially simply and quickly, the hold of the wall strip on the hollow section wall being especially good on account of the virtually permanent mechanical clamping.
In a further, especially preferred configuration of the device according to the invention, the press-joining device contains a joining punch which is movably guided in a passage of the perforating punch, said passage opening out at the cutout at the end face. Furthermore, the press-joining device contains a die which is formed with a recess and bears against the outside of the hollow section, the recess having undercut contours and being in alignment with the passage of the joining punch. Due to the step of integrating the joining punch in the perforating punch, not only construction space but also a further work station are saved. Associated therewith, the process time for producing and for reinforcing the hollow section having a closed periphery is considerably reduced, since the transfer path into the joining station otherwise necessary is dispensed with. Furthermore, production tolerances which arise during the transfer from one work station to the other are prevented. Furthermore, the wall strip of the wall piece remains exactly positioned for the press-joining method, since the perforating punch holds the wall strip on the hollow section wall during the entire press-joining method.
A further preferred configuration of the device according to the invention relates to the integration of the perforating punch in an internal high pressure forming tool, in the impression of which the hollow section is accommodated. As a result, the reinforcing component can already be produced during the shaping of the hollow section by means of internal high pressure by virtue of the fact that the perforating punch cuts out the wall piece in the hollow section body being shaped or already finish-formed, in which case sufficiently sound sealing of the perforating punch in the opening must be assumed so that a pressure drop does not occur which would disturb the process for shaping the hollow section and would no longer provide for conformity to contour of the hollow section during a plurality of successive perforations for producing a plurality of spaced-apart reinforcing components. With the integration of the perforating punch and thus the production of the reinforcing component in the internal high pressure forming tool, the entire process for producing the hollow section is simplified in such a way as to save construction space and the production time is reduced. Relatively sharp-edged transitions between the hollow section and the reinforcing component bent into the hollow section interior can be produced by the internal high pressure, a factor which, depending on the intended use, may be necessary for optical reasons for as highly precise an outer contour of the hollow section as possible.
In a further, especially preferred configuration of the invention, the hollow section is formed by internal high pressure, wherein, following the forming in the internal high pressure tool, the opening is formed at existing internal high pressure, the wall piece is bent into the hollow section, and the wall strip is bent over and press-joined to the opposite hollow section wall. To this end, the press-joining device is integrated in the internal high pressure forming tool. As an addition to the above embodiments, the wall strip of the cut-out wall piece is also bent over and press-joined to the hollow section wall, so that the coupling of the production of the hollow section with the forming and fastening of the reinforcing component on the hollow section firstly provides for a highly compact type of construction of the device and minimizes the process time of the method for reinforcing the hollow section and for forming the hollow section.
In the event that only the free end of the reinforcing component comes into contact with the hollow section wall, so that no wall strip can be formed, the reinforcing component, with its free end, is advantageously welded in the form of a fillet weld to the hollow section wall by means of a welding device, which forms the joining device, as a preferred development of the invention.
The invention is explained in more detail below with reference to several exemplary embodiments shown in the drawings.
A hollow section 1 which has a closed periphery and is to be locally reinforced is shown in
After the wall piece 7 has been cut out, the perforating punch is moved still further toward the hollow section 1, as a result of which the perforating punch 3 plunges into the hollow section interior 8. In the process, the perforating punch 3, with its bending contour 6, bends the wall piece 7, hanging in one piece on the opening edge 9, into the hollow section interior 8, as a result of which the opening 2 is formed, which, however, is closed here by the perforating punch 3 until it is retracted from the hollow section 1. As a result, the perforating punch 3 forms the means for introducing the reinforcing component into the interior 8 of the hollow section 1. The wall piece 7, with its free end 10, after sweeping a bending angle which is less than 90°, comes into contact with the opposite hollow section wall 11 on account of the oversize of the wall piece 7.
The perforating punch travels further until it runs against the hollow section wall 11, as a result of which the wall piece 7 bends in at the locations at which the wall piece 7 projects relative to the width of the hollow section 1. The wall strip 12, forming in the process, of the wall piece 7 is brought to bear against the hollow section wall 11 by the end face 4 of the perforating punch 3 in such a way as to conform to the contour, the rest of the wall piece 7 now running from the opening edge 9 at a 90° angle toward the hollow section wall 11. In order to avoid a situation in which the wall strip 12 tears when being bent over and the hollow section wall 11 is crushed in a damaging manner, the perforating punch 3, at its end face 4, has a cutout 13 which starts from the bending contour 6 and is designed in its shape and dimensions in such a way that the wall strip 12 is accommodated when being bent over and when being brought to bear. In this case, the cutout 13 has a depth which corresponds to the wall thickness of the wall strip 12.
Finally, the wall strip 12 is joined to the hollow section wall 11. A plurality of variants of joining methods are conceivable here. For example, the wall strip 12 according to
To carry out the press-joining method, the perforating punch 3 has an axial passage 15 which opens out at the cutout 13 at the end face. A joining punch 16 according to
FIGS. 7 to 9 show a further exemplary embodiment of the invention. In deviation from the preceding exemplary embodiment, the perforating punch 22, compared with the perforating punch 3, does not have the cutout 13. Furthermore, a wall piece 23 whose length is just less than the width of the hollow section 24 is cut out here. The wall piece 23 is now cut out according to
In the above embodiments of the invention, it is in each case conceivable for the hollow section to be subjected to internal high pressure forming. For reasons of economy in relation to the method, it is favorable here to integrate the perforating punch 3 or 22 and also the press-joining device in the internal high pressure forming tool. The die 18 of the press-joining device may in this case be formed by the impression of the forming tool in which the hollow section 1 or 24 is accommodated.
Number | Date | Country | Kind |
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103 57 343.7 | Dec 2003 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP04/12691 | 11/10/2004 | WO | 5/15/2007 |