EP1954420B1 - Method and device for the coreless forming of hollow profiles - Google Patents

Description

The invention relates to a method for producing a hollow profile from a board, in which the board between two the desired profile shape and having relatively movable die halves is inserted and by a closing movement of the die halves the board is formed into a slotted hollow profile, wherein the deformation of the board is carried out with coreless die halves, as well as an apparatus for producing hollow profiles, which has two relatively mutually displaceable Gesenkformhälften and optionally a base plate, wherein the Gesenkformhälften have the desired profile shape of the hollow profile to be formed.

In the automotive industry increasingly complex hollow sections are used to meet the requirements in terms of strength and weight in so-called space frame structures. In addition to the transformation of longitudinally welded pipes in load-oriented designed, closed hollow sections, various methods for the production of hollow sections are known from the prior art. A particularly flexible and yet economical production of hollow profiles designed for load-bearing purposes makes it possible to obtain a German published patent application referring back to the applicant DE 198 27 798 A1 known "roll-in" method. In this method, a sheet metal blank is deformed in a slot space in which this with its longitudinal edges in each case in semi-cylindrical mold gaps of two mirror mold mutually arranged mold halves are inserted and the emerging from the mold gaps in the apex of the forming tool longitudinal edges are welded together. During welding, these are held in position by the mold halves. A disadvantage of the method mentioned is that, on the one hand, a mold having splitting tool, ie a tool with an inner mandrel or inner mandrel halves, is correspondingly complex and thus entails relatively high investment costs. In addition, there are always damage to the surfaces of the dies or the mandrel halves due to their relative movement to the board. The surface defects then lead to further errors in the subsequent processes, such as jamming of the sheet metal blank in the mold gap.

In addition, from the generic German patent specification DE 966 111 a device for bending of metal strip to pipes of large diameter known, which consists of two mutually perpendicular coreless press jaws with semicircular cross-section which embrace the longitudinal sides of the metal strip over its entire length in the starting position with their lower edges and when merging the metal strip to a Round tube. During this forming process, the metal strip is firmly clamped along the central longitudinal axis via a clamping device. In the known round bending of metal strip to pipes without internal mandrel required for welding butt joint of the opposite longitudinal edges of the formed sheet to achieve a constant weld is not guaranteed, so that a secure longitudinal seam welding of the hollow sections is not guaranteed. Furthermore The tubes thus produced must be subjected to an additional calibration.

Proceeding from this, the present invention thus has the object to provide a generic method and a generic device available, with which or with which low cost equipment with high process reliability hollow profiles can be made from a board, which are properly longitudinally welded, if necessary can.

According to a first teaching of the present invention, the above-described object of a generic method for producing a hollow profile is achieved in that the forming is carried out with coreless die halves and a Vorangleiten the edges of the board during the closing movement of the die to form a slotted hollow profile is prevented whereby the board is set in the circumferential direction under pressure upon continuation of the closing movement of the die-half molds and applies with yielding to the mold halves. Suitable board materials are all easily deformable metals, in particular steel or a steel alloy.

It has surprisingly been found that can be dispensed with molding of the reshaped board in form of gaps, which are formed by a die core and the outer mold halves, without the quality of the produced slotted hollow profile suffers. Characterized in that the advancement of the edges of the board or the edges is initially prevented parallel to the longitudinal axis or bending axis of the hollow profile to be formed in the mold halves, the board is placed in continuation of the closing movement of the mold halves in the circumferential direction under pressure. This directed in the circumferential direction pressure can Give board only by applying to the outer mold halves. When creating the die halves, therefore, the shape of the hollow profile to be produced is taken only by the profile shape of the die halves without the inner mandrel or die core. Since the board can freely deform in the interior of the die halves due to the omission of the mold gap, the risk of jamming of the board, for example due to surface defects of the die cores, eliminated and the process reliability for the production of the hollow profile significantly improved. At the same time, for example, by a sword or other means for preventing the Voranleitens the edges of the board a precise slot in the hollow profile between the bent edges of the board generated, which allows a process-reliable longitudinal seam welding.

According to a first advantageous embodiment of the method according to the invention, at least one sword protruding into the coreless hollow space is used to prevent the edges of the board from advancing. During the closing movement of the tool, as already stated, the edges of the board slide along the inner die half surface until they strike the sword projecting into the coreless mold cavity. The sword then ensures, in the case of further closing of the tool, for the construction of the directed in the circumferential direction pressure within the board, which leads to the expansion of the circumference of the board and thus the exact application of the board to the inner mold cavity of the two die halves. At the same time can be ensured by the sword in a simple manner that the slot formed by the opposite edges of the board has a substantially constant width.

The sword can, for example, extend over the entire longitudinal axis of the later hollow profile. But it is also possible to use a sword, which extends only in some areas in the mold cavity.

According to a further developed embodiment of the method according to the invention for producing a hollow profile, a sword arranged between the die halves or in a die half is used. While the sword disposed between the die halves allows it to be easily removed after forming, a sword disposed in a die half opens up the use of die and bend presses without much rebuilding.

Preferably, the hollow profile is calibrated out during the closing process of the die halves, i. the pressure in the circumferential direction increased so much that a dimensionally accurate deformation of the board is caused in accordance with the mold cavity formed by the die halves. Subsequent processing to achieve the dimensional accuracy is so far no longer necessary in these hollow sections.

The Auskalibrieren can, according to an embodiment of the method, also be performed without a sword. This exploits that the opposing edges of the board at the end of the forming process can be supported against each other, so as to build up pressure in the circumferential direction.

If the edges of the board are pre-bent in the direction of deformation, the forming process can be initiated in a defined manner so that the process reliability during forming is further increased.

The method according to the invention for producing a hollow profile is furthermore advantageously configured by securing the circuit board against displacement in the direction of the bending axis. By this measure, resulting in the direction of the bending axis forces, for example, in the longitudinal direction of the hollow profile unevenly distributed forming forces due to different diameters along the longitudinal axis of the hollow profile produced, be collected and a displacement of the board during Umformformgangs be prevented. For this purpose, for example, a stop in the direction of the bending axis preventing stop can be used. A complex "clamping" of the board in one place is not necessary.

If the hollow profile after removal of the sword, especially longitudinally welded in the same device, a closed hollow profile can be made economically available with a few steps.

Preferably, "tailored tubes" are produced by the forming process. "Tailored Tubes" are specially adapted to the load situation, closed hollow profiles, which have different material thicknesses and material grades. The field of application of the "tailored tubes" is particularly in the automotive industry, to take into account the different loads in different areas of a space-frame structure and at the same time to ensure a minimum weight.

The method according to the invention can be carried out particularly economically by using a deep-drawing press, a press bending press or a rolling-in device. Deep-drawing and die-bending presses can be easily adapted by incorporating the die-forming halves enabling the method, in order to enable the method according to the invention to be carried out. A curling device, which, as already stated in the introduction, from the German patent application DE 198 27 798 A1 can be easily used using a coreless die and preferably at the same time allows for direct longitudinal seam welding of the profile. For carrying out the method according to the invention therefore relatively low investment costs are required.

According to a second teaching of the present invention, the above-described object is achieved by a generic device characterized in that the die halves are coreless and means are provided which are suitable for preventing closing the Gesenkformhälften a leading the edges of the board to form a slotted hollow profile , whereby the board is placed in continuation of the closing movement of the Gesenkformhälfen in the circumferential direction under pressure and rests under yielding to the Gesenkformhäften.

As already stated above, the advantages of the device according to the invention are that the inventive method can be carried out, which has a higher process reliability than the previously used method. In addition, due to the use of coreless die halves, a corresponding apparatus requires correspondingly less investment cost than previously used Devices with complex inner spines or mandrel halves.

The formation of a slot with a constant width between the perpendicular to the direction of movement of the mold halves extending edges of the board is, according to a next advantageous embodiment of the device according to the invention, ensured in a simple manner that a protruding into the interior of the mold halves sword is provided. The thickness of the sword in the area of the contact points of the perpendicular to the direction of movement of the mold halves extending edges of the board determines the thickness of the slot between these edges and ensures, with a perpendicular to the faces of the edges of the surface of the sword, to form an ideal butt joint for welding the both edges together. Preferably, the sword extends at least partially parallel to the bending axis of the hollow profile to be formed.

According to the invention, the sword is arranged between the die halves or in one of the die halves. In the case of the sword arranged in one of the die halves, this embodiment of the device according to the invention makes it possible to use deep-drawing presses or die-bending presses for producing the hollow profiles. On the other hand, a sword arranged between the die halves offers the possibility of easily removing it after forming and longitudinally welding the hollow profile without any further intermediate step.

Preferably, according to a next further developed embodiment of the device according to the invention, means for carrying out a longitudinal seam welding are provided, which enable an integrated longitudinal seam welding after completion of the forming process.

Fig. 1a) und b)

in einer schematischen Schnittansicht senkrecht zur Biegeachse ein erstes Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung zu zwei verschiedenen Zeitpunkten während der Durchführung des erfindungsgemäßen Verfahrens sowie

Fig. 2a) bis f)

in einer schematischen Schnittansicht eine Simulation eines zweiten Ausführungsbeispiels des erfindungsgemäßen Herstellverfahrens zu sechs verschiedenen Zeitpunkten.

There are now a variety of ways to further develop the method of the invention and the inventive device for producing a hollow profile and to design. Reference is made on the one hand to the claims subordinate to claims 1 and 11 claims and the description of two embodiments in conjunction with the drawings. The drawing shows in

Fig. 1a) and b)

in a schematic sectional view perpendicular to the bending axis, a first embodiment of a device according to the invention at two different times during the implementation of the method and method

Fig. 2a) to f)

in a schematic sectional view of a simulation of a second embodiment of the manufacturing method according to the invention at six different times.

Fig. 1a 1 shows a schematic sectional view of a first exemplary embodiment of a device according to the invention for producing a hollow profile 1, which has a base plate 2 and two coreless die halves 3, 4 arranged displaceably relative to one another includes having the desired profile shape of the hollow profile to be produced. The board 5 has in the deformation direction pre-bent edges 6, 7, which extend parallel to the bending axis 14. In addition, in the Fig. 1a ) still a projecting into the mold cavity 12 sword 8, which is arranged between the two mold halves 3, 4.

In the present embodiment, the sword 8 runs parallel to the bending axis 14 over the entire length of the die. However, it is also possible to use a sword 8 which is interrupted several times or only protrudes into the mold cavity 12 at some points.

When carrying out the method according to the invention, the die halves 3, 4 are moved towards one another according to the movement arrows 10, 11, so that the blank 5 arranged in the interior of the mold cavity 12 is shaped in accordance with the die halves.

The Fig. 1b ) shows the embodiment of the device according to the invention after completion of the forming process. The board is now to a still open hollow section 5, for example in the form of a tube, formed around the bending axis 14. The sword 8 required for the forming process is pulled out by a movement of the sword holder 9 perpendicular to the longitudinal axis of the hollow section 5 from the hollow section 5 corresponding to the direction of movement 13, so that the hollow profile or tube 5 can now be welded longitudinally. Although the embodiment shows a particularly simple hollow profile in the form of a tube. However, it is conceivable, many developable in a plane profile shapes with the device according to the invention or with the produce process according to the invention. Thus, for example, an oval-conical profile can be produced with even proportions. In principle, after the sword has been pulled, further reshaping of the edges and / or subsequent longitudinal seam welding, for example using a laser, can follow. Preferably, this is also carried out integrated in the device according to the invention.

The Fig. 2a) to 2f ) show now in individual steps a simulation of a second embodiment of the inventive method for producing a hollow profile, again based on the production of a hollow section 5 in the form of a tube in a sectional view at different times. First, the board 5, which preferably has pre-bent in the deformation direction, edges 6, 7, inserted into a device 1 according to the invention for the production of hollow profiles according to the second embodiment. The device 1 comprises a swaging mold half 4, which has a sword 8 extending in the longitudinal direction of the entire swaging mold half 4 or parallel to the bending axis 14.

Now, if the Gesenkformhälften 3, 4 moves towards each other, so the pre-bent edge 7 of the board abuts against the sword 8 and the leading edge of this edge 7 of the board is prevented. The opposite edge 6 of the board, however, can deform freely until this, as in Fig. 2b ), also hits against the projecting into the mold cavity 12 sword 8. During the further travel of the die halves 3, 4 pressure builds up in the inserted board in the circumferential direction, through which the board is forced to an ever greater extent. Finally, the board bumps, like in Fig. 2e ), against the die-forming halves 3, 4, so that a further closing movement increases the pressure present in the circumferential direction in the blank in such a way that the calibrated hollow profile is calibrated out.

Surprisingly, the board 5 needs between the forming steps, shown in Fig. 2b ) and 2e ), no additional guidance, for example, by an internal die core or Gesenkformspalte or a firm clamping to ensure a reliable process forming the desired hollow section 5. This is all the more surprising as the experts had previously assumed that for perfect forming of a hollow profile in a die at least one die core is necessary or the hollow profile must be clamped firmly at least along an axis parallel to the bending axis.

The cross-sectional shape of a slotted hollow profile 5 produced according to the second exemplary embodiment just described shows the Fig. 2f ) after molding from the device according to the invention 1. Clearly, the slot 15 of the hollow profile can be seen. The fact that the Auskalibrierung can already be performed within the device 1, the hollow profile produced is very accurate and can be particularly well welded longitudinally. The method according to the invention and the device according to the invention are thus ideally suited for the production of "tailored tubes".

Claims (14)

1. Method for the production of a hollow section from a blank (5), wherein the blank (5) is introduced between two halves (3, 4) of a die which have the desired section shape and can be displaced relative to one another and the blank (5) is formed into a slotted hollow section by a closing movement of the halves (3, 4) of the die, wherein the forming of the blank (5) is carried out with coreless halves (3, 4) of the die characterised in that the edges (6, 7) of the blank (5) are prevented from sliding ahead during the closing movement of the die to produce a slotted hollow section, thus the blank (5) is pressurized in the peripheral direction as the closing movement of the die halves continues and by yielding aligns to the two halves (3,4) of the die.
2. Method for the production of a hollow section according to Claim 1, characterised in that to prevent the edges (6, 7) of the blank (5) from sliding ahead, at least one tongue (8) is used which projects into the coreless form cavity (12).
3. Method for the production of a hollow section according to Claim 1 or 2, characterised in that a tongue (8) is used which is positioned between the halves (3, 4) of the die or in one half (3, 4) of the die.
4. Method for the production of a hollow section according to any one of Claims 1 to 3, characterised in that the hollow section is fully calibrated during the closing procedure of the halves (3, 4) of the die.
5. Method for the production of a hollow section according to Claim 4, characterised in that the hollow section is fully calibrated without the tongue (8).
6. Method for the production of a hollow section according to any one of Claims 1 to 5, characterised in that the edges (6, 7) of the blank (5) are pre-bent in the deformation direction.
7. Method for the production of a hollow section according to any one of Claims 1 to 6, characterised in that the blank (5) is secured against displacement in the direction of the bending axis (14).
8. Method for the production of a hollow section according to Claim 3, characterised in that after the tongue (8) has been removed, the hollow section is straight bead welded, in particular in the same device.
9. Method for the production of a hollow section according to any one of Claims 1 to 8, characterised in that "tailored tubes" are produced.
10. Method for the production of a hollow section according to any one of Claims 1 to 9, characterised in that a deep drawing press, a press brake or a rolling device is used.
11. Device for the production of hollow sections, in particular for carrying out a method according to Claims 1 to 10, which device has two halves (3, 4) of a die which are positioned displaceably relative to one another and optionally a base plate (2), the halves (3, 4) of the die having the desired section shape, characterised in that the halves (3, 4) of the die do not have a core and means (8) are provided which, when the halves (3, 4) of the die are closing, are capable of preventing the edges (6, 7) of the blank (5) from sliding ahead to produce a slotted hollow section (5) thus the blank (5) is pressurized in the peripheral direction as the closing movement of the die halves continues and by yielding aligns to the two halves (3,4) of the die.
12. Device for the production of hollow sections according to Claim 11, characterised in that a tongue (8) is provided which projects into the coreless form cavity (12) of the halves (3, 4) of the die.
13. Device for the production of hollow sections according to Claim 12, characterised in that the tongue (8) is positioned between the halves (3, 4) of the die or in one half (4) of the die.
14. Device for the production of hollow sections according to any one of Claims 11 to 13, characterised in that means for carrying out a straight bead welding procedure are provided.

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