WO2003000441A1

WO2003000441A1 - Method for producing a structural part of a motor vehicle body and corresponding structural part

Info

Publication number: WO2003000441A1
Application number: PCT/AT2002/000185
Authority: WO
Inventors: Franz Trubert; Michael Seifert; Harry KÖDER
Original assignee: Magna Ihv Gesellschaft Für
Priority date: 2001-06-26
Filing date: 2002-06-26
Publication date: 2003-01-03
Also published as: DE10130794A1

Abstract

The invention relates to a structural part of a motor vehicle body, having a long, tubular and spatially curved form and a flange for applying additional parts. The aim of the invention is to produce and assemble the entire vehicle in such a way that it weighs little, and involves minimum cost and effort. To this end, the structural part (1) consists of a closed, continuous extruded profile (20) which is subjected to a pre-deformation process, followed by a deformation process according to the internal high pressure moulding method (Innenhochdruckverfahren: IHU). The part is first placed in an intermediate mould and the flange is oriented, the end form is obtained using the internal high pressure moulding method, and the flange (6) is fixed according to the requested dimensions in relation to the course and direction (38), along the structural part (1). The invention also relates to a structural part produced according to said method.

Description

METHOD FOR PRODUCING A STRUCTURAL PART OF A MOTOR VEHICLE BODY AND STRUCTURAL PART

The invention relates to a method for producing a tubular and spatially curved structural part from an extruded profile with a projecting flange extending in the longitudinal direction, and also relates to a structural part of a motor vehicle body produced by this method. The structural part is of a long, tubular and spatially curved shape with a flange for attaching add-on elements. It can be a longitudinal or cross member, a sill or longitudinal roof spar, or an A pillar, a B pillar, a C pillar, or a combination of these. The pillars can extend over the entire height of the vehicle, or only over part of it.

In motor vehicle construction, the aim is not only low weight while meeting all static and dynamic strength requirements, but also a minimum of costs and labor in the production of the structural parts and in the assembly of the entire vehicle, which requires excellent dimensional accuracy of the individual structural parts. DE 195 06 160 discloses a subassembly which is composed of a plurality of structural parts which are optimized for cross-section and are individually shaped by internal high-pressure deformation of aluminum tube profiles, which may be extruded. These parts are then put together, which is labor intensive and imprecise. One of the structural parts - it is a longitudinal member - has a longitudinally extending flange that protrudes from the profile at a constant angle. It cannot be seen that this side member is bent or even twisted. But that would be necessary for the soft and round contours common today in motor vehicles and the strongly inclined and curved window surfaces.

From DE 36 10 769 AI it is also known to use an extruded aluminum profile to form roof spars, the cross-section of which has a constant cross section over the length and has moldings for receiving the roof panel or glazing and seals which are glued in later. Mentioned is the possibility of pulling down the roof spars in the front and rear areas, where they form window spars. For this, however, the profile must be bent, which can only be done with very large bending radii due to the shape of the cross section. But even then, the dimensional accuracy of the formations required for later assembly is not guaranteed.

Finally, WO 97/30882 discloses a vehicle frame made of bent steel profiles of constant cross-section, in which the A-pillar, longitudinal roof spar and C-pillar are formed by a single tubular structural part. To save weight here simply shaped thin-walled, flangeless profiles made of hardenable steel. The possibility of using hydroforming is mentioned in the margin.

It is therefore an object of the invention to provide a method for producing such structural parts, which offers the highest accuracy and freedom of shape design with minimal overall costs. The structural part should be designed in such a way that the process is easier to carry out and all strength requirements can be met with a low weight.

According to the invention, the method consists in first bending the extruded profile so that its shape at least approximates the desired curvatures of the final shape of the structural part. This bending can be in the plane or already spatial. Then a deformation is carried out in which the cross section of the extruded pro flies (20; 40) is changed and the flange is straightened. Only by straightening the flange in the tool (which can include positioning, changing the standoff angle and eliminating shafts created during the previous bending) can the problem arising from the task be solved.

In the case of structural parts of at least locally strongly curved and twisted shape, such as are found in motor vehicles with modern lines, the deformation is preferably divided into two steps. In a pre-forming process, the raw part is brought into a preform suitable for the following hydroforming process and the flange is straightened. Then the final deformation after the hydroforming process made, the positioning of the flange, preferably in the parting plane between the upper and lower tool, is taken into account (claim 2). Overall, very complex and strength-optimized shapes can be produced that can be connected to the surrounding body parts with a minimum of effort thanks to the integral flange that is adjusted in terms of direction and position.

In places where no flange is required or where it is in the way with very tight radii of curvature, the flange can be interrupted in places before bending (claim 3).

The basic steps of the method according to the invention can be supplemented by intermediate steps and the hydroforming process can also be carried out in several steps. For example, a further bending can also take place during the pre-deformation (claim 4), for example in the third dimension, if the previous bending process took place in the plane.

Furthermore, the flange can be clamped for straightening between an upper and a lower pre-forming tool by compressing them, the angle at which the flange protrudes being changed in places (claim 5). Or, the flange for straightening between an upper and a lower pre-forming tool can be positioned with regard to position and angle by an additional slide (claim 6). There are also different procedures for internal high pressure deformation itself. In one variant, when the bent and pre-deformed extruded profile is inserted into the mold for the internal high-pressure deformation, the flange is inserted into a groove in the tool (claim 7). The tool consists of at least an upper part and a lower part, which are closed before the hydraulic pressure is applied. Naturally, the groove will be provided in the lower tool. It can go inwards normally from a flat or non-flat separating surface or also at an angle, depending on the shape given during bending, the desired course of the flange and the geometric requirements when inserting.

In another variant, when the bent and preformed extruded profile is inserted into the mold for the deformation according to the internal high-pressure process, the flange is inserted into a recess in the separating surface of one of the two halves of the tool (claim 8), so that the flange when the tool is closed is squeezed.

This means that when the tool is closed, the flange can not only be positioned precisely, but also any undulating bulging during bending can be leveled out again. With certain materials and with sufficient mechanical pressure between the two mold halves, the flange can also be hardened. However, it is also possible to change the angular position of the flange at this stage. Depending on the cross-sectional course of the structural part, it can be advantageous if the flange in the groove of the tool (claim 9) or in the separating surface between the two tool halves (claim 10) has some play so that it can shift during the deformation; namely when the hydroforming completely fills the mold and the flange is pushed a little further into the groove.

In a further embodiment of the inventive concept, the cross section of the extruded profile has an inwardly extending bladder and the flange has a root, and before bending, the root of the flange is inserted into the bladder (claim 11), preferably in the longitudinal direction of the structural part (claim 12 ). If necessary, the flange is first interrupted in places and only then is the raw part bent. In the subsequent deformation according to the internal high-pressure process, the bladder is compressed and the root of the flange is thus firmly connected to the bladder (claim 13).

The invention also relates to a structural part of a motor vehicle body of long, tubular and spatially curved shape with a flange for connection to other parts of the vehicle body, which consists of a closed extruded profile with a longitudinally extending projecting flange. The structural part should meet all requirements in terms of shape, strength and accuracy.

According to the invention, the structural part has a cross-section which is variable over its length, thanks to the deformation in the internal high-pressure process, and the flange is in the course and direction of its protrusion over the length of the Structural part variable and dimensionally fixed (claim 14). As a result, the flange is dimensionally stable and the protrusion angle can be used during assembly without rework. This saves a significant amount of time. When bending, there is either no flange at all (this is the variant with the flange inserted), which allows small bending radii, or if it is present and on the concave side of the bend, its deformation can be straightened out of the plane.

If the flange also accompanies the profile along its length, it can be interrupted in places (claim 15), for example if the structural part is a longitudinal roof spar, for example in the middle for connecting a B-pillar by means of welding. The flange can even be disengaged in zones of strong bending (claim 16).

In a first basic embodiment, the cross section of the extruded profile, which is used in the manufacture, is approximately square, the flange protrudes in the synimetral of a square side, and the square side has inclined sides on both sides of the flange, so that it forms an obtuse angle with the flange ( Claim 17). It is therefore an extruded profile that is already manufactured with a flange. The symmetry facilitates the subsequent insertion into the tool for internal hydroforming and three-dimensional bending. The direction of the flange results in minimal deformation of the flange from its plane during bending, especially if it lies in the bending pressure zone. In some cases it is advantageous if the cross-section of the extruded profile, which is used in the manufacture, is essentially circular (claim 18), so it can also be elliptical or drop-shaped. If it is in particular teardrop-shaped, the flange is arranged on the peripheral part with the smallest radius of curvature (claim 19). This again makes three-dimensional bending and insertion into the tool for hydroforming easier.

In a second basic embodiment, the flange is inserted into the extruded profile and is only defined in the internal high-pressure process when it is deformed (claim 20). Due to the later insertion of the flange, it does not hinder the bending, or it cannot be damaged in the process, and the protrusion angle can easily be varied over the length of the structural part according to requirements.

In a preferred embodiment, the extruded profile, which is assumed during production, consists in cross-section of an outer wall and of a bladder which extends into the inside, the outer wall being interrupted and its spaced-apart interrupting edges being connected by the bladder, and that Flange consists of a flange part and a root part, the root part being in the bladder (claim 21). Despite the interrupted outer wall, the bladder complements the profile to a closed profile, even strengthening it without being a hindrance to bending. After bending, the root part is either inserted in the transverse direction or inserted in the longitudinal direction of the profile. In both cases, the angular position of the 5 flange has not yet been finally determined, it will only be deformed when later

A particularly useful design is achieved if the cross-section of the root part of the flange is poligonal and the bubble is round (claim

10 22). The thickened root part is pushed lengthways into the bladder and remains pivotable through a considerable angle. This makes it easier to insert it into the tool for hydroforming and has a very special effect: When molding with hydroforming, the bladder is compressed so that it adheres to the

15 poligonal root part creates and defines this.

In principle, the structural part according to the invention is not bound to a specific material as long as it has the required properties. If it consists of a light metal extruded profile, its advantages are particularly clear through the adaptation of the cross section to the load.

The invention is described and explained below with the aid of figures. The figures show: 5

Fig. 1: an embodiment of an inventive

Structural part in side view, Fig. 2: the same part in front view, Fig. 3: a) to f) cross sections through the same at different 0 locations,

4: detail IV in FIG. 1, enlarged, 5 shows a cross section to a first procedure according to the method according to the invention through the starting prof

6: the first step of a second procedure, FIG. 7: the second step of a second procedure, FIG. 8: the third step of a second procedure, FIG. 9: a variant of FIG. 6,

10: a cross section through another initial profile for FIG. 1, FIG. 11: a cross section for FIG. 6 after processing.

1 and 2 show, for example, a structural part of a motor vehicle body, denoted overall by 1, consisting of the upper part of an A-pillar 2, a longitudinal roof beam 3 and an upper part of a C-pillar 4, which are made from a continuous closed profile. At the transition from the A-pillar 2 to the longitudinal roof spar 3 there is a point 7 of greater curvature. It can be seen in FIG. 2 that the structural part 1 is also bent into the third dimension, in particular the C-pillar 4 ends in a foot 5 which is strongly S-shaped bent inwards. The structural part 1 has a flange 6 essentially over its entire length. The flange 6 is interrupted at 8 in order later to facilitate the welding on of a B-pillar 9, indicated by dashed lines in FIG.

FIG. 3 shows various cross sections through the structural part 1 at locations which are designated with the lower case letters a to f in FIG. 1. In section a, the cross section of the profile is still approximately symmetrical and the flange 6 protrudes at the angle of the synimetral 23. In section b, the cross section has already changed considerably and the flange 6 'is inclined at an angle 11 with respect to its direction in section a. In section c is the Flange 6 "is inclined in the opposite direction by an angle 12. The section d shows the cross section where, because of the B-pillar 9, the flange 6 is interrupted, for example cut out. The sections e and f show that the Location and direction of the flange 6 '", 6""each is different.

4, the curved zone 7 of FIG. 1 can be seen in more detail. The flange 6 is here provided with notches 14 so that trapezoidal tabs 15 remain between them. This notching is done before bending the still undeformed profile of constant cross-section because it enables small bending radii.

5 shows a diagram of a first procedure for a first embodiment with an extruded profile of approximately square cross-section as the starting material. The profile has three straight square sides 21 which merge into one another via fillets 22 and a flange 6 on an additional square side as an integral part of the profile. It lies in the symmetry 23 and projects outwards. On both sides of the flange 6, roof-like inclined sides 24 are provided, each enclosing an obtuse angle 25 with the flange 6. They facilitate insertion into the tool.

This profile is first cut to length and, if necessary, unlatched at points of great curvature or the flange is removed at certain points, then it is bent and already lies in a tool that can be a tool for both pre-forming and internal high-pressure forming , With simple form of the Pre-deformation is not necessary for the structural part. Then the illustrated tool consists of a lower tool 30, which has an engraving 31 starting from a separating surface 32. The separating surface 32 is the surface that comes into contact either with the workpiece or with the upper tool 33 during the internal high-pressure deformation. The engraving is the part of the form on which the profile is brought into contact by the effect of the internal high pressure. This also applies to the upper tool 33 with the engraving 34 and the separating surface 35.

The separating surface 32 of the lower tool 30 has a recess 36 in which the flange 6 of the profile can be accommodated. This depression is somewhat shallower than the thickness of the flange 6. As a result, the closing pressure of the upper tool 33 is applied to the flange 6 when the tool is closed. As a result, any unevenness in the flange 6 is first straightened, the flange is further clamped firmly in the tool and, if desired, and if the profile is made of light metal, the flange 6 can even be hardened by cold working. The clamping of the flange 6 has the purpose of preventing its displacement during the hydroforming.

To this extent, flat parting surfaces 32, 35 of a flat depression 36 were assumed. But that is not necessary. In particular not for the recess 36. If it and the corresponding part 37 of the upper tool 33 are inclined by an angle 38, the flange 6 is bent when the tool is closed, so that it is inclined by the angle 38 to the symmetrical 23. As a result, the flange can be changed in position and direction before the actual internal high-pressure deformation. Then However, the depression must be somewhat deeper than the thickness of the flange so that the latter can be pushed a little further into the depression due to the internal pressure.

The approximately square cross-section facilitates three-dimensional bending, simplifies welding butts if necessary and gives full contact surfaces for the later attachment of plate-shaped parts of the structure. The inclination makes it easier to insert it into the tool for internal high pressure forming.

A second procedure for a first embodiment with an extruded profile of approximately circular cross-section as the starting material will now be described with reference to FIGS. 6, 7, 8. It consists of two work steps, a pre-deformation and a final deformation using high pressure.

6 shows the preliminary deformation. The starting point is an extruded profile 40, which consists of a circular part 41 and a flange 46, which lies on average on a beam from the center 43. It is already bent and inserted into the preforming tool, which consists of a lower tool 50 and an upper tool 51 and moves downwards according to the directional arrow 55. Furthermore, a slide 52 can be present, which is moved in the horizontal direction to the profile 40 when the upper tool 51 is completely lowered in accordance with the arrow 56. The upper tool is drawn in two positions. First, before it is completely closed, see the contour 53, it grips the edge of the flange 46 and bends it further downwards into the Direction 46 *. If such a change of direction of the flange is not necessary, the profile 40 is inserted in such a way that the flange 46 already lies flat on the lower tool 50. Then, when the upper tool 51 is completely lowered, the flange 46 is only directed in order to level waves that have arisen when lying down. The slide 52 is then moved to the left in the image and the intermediate stage shown in FIG. 6 occurs, in which the flange is directed and the profile is in an optimal shape for the later internal high pressure deformation.

In Fig. 7, the intermediate profile is designated 40 *. It consists of the already deformed closed part 41 * and the directed or brought into position flange 46 *. Fig. 7 is only a section at one point of the entire structural part, the profile of which varies over its length.

In Fig. 8 the tool for internal high pressure deformation is designated 60 (lower tool) and 61 (upper tool). When the upper tool 61 is lifted off, the intermediate product from the preliminary deformation (profile 41 * with flange 46 *) is inserted into the lower tool 60. It should be noted that the workpiece is now inserted rotated by 180 ° in order to ensure the correct support and filling of the shape during the deformation. The upper tool 61 is now lowered, the recess 62 for the flange 46 * in the upper tool being somewhat higher than the flange 46 * thick. As soon as the tool is closed, the workpiece is sealed and a very high pressure liquid is applied from the inside. As a result, the closed part of the profile 41 * is pressed outwards into the engraving of the two tools 60, 61, which is indicated by dashed lines and is designated by 41 **. Because the closed part of the If the profile at the connection of the flange 46 * is also deformed outwards, the flange 46 * can shift outwards into the recess 62.

9 shows an additional possibility for deforming the flange 46 of the profile 40. The profile is located between a lower tool 70 and an upper tool 71, which can be both a preform and an internal high-pressure deformation tool. In order to additionally deform the flange, a slide 73 is provided which is moved in the direction of arrow 74, presses the flange 46 into a recess 72 and thus deforms it.

10 and 11 show another embodiment of a structural part according to the invention. 10 shows this after bending, but before the internal high pressure deformation. It is also an extruded profile 140, which consists of an essentially or approximately circular outer wall 141 with a part 142 having a smaller radius of curvature and an inwardly directed bladder 145. The profile is thus approximately teardrop-shaped and has a symmetry, designated 143, in which a flange could also connect as an integrating part of the profile. Here, however, the outer wall 141 is cut open at the point 142 with the smallest curvature, so that on both sides of the symmetrical break edges 144 and 144 'are formed, which are spaced apart from one another. They are connected by the bladder 145 projecting into the interior of the outer wall 141, the inner wall of which is circular. A flange 146 with its root part 147 is now inserted into this bladder 145. The root part 147 is polygonal in cross-section, in the exemplary embodiment shown it has three edges 148. The flange 146 itself projects with considerable play between the interrupting edges 144, 144 ', so that it can be pivoted in both directions by an angle 149 to the symmetry. In the cross section shown, the flange 146 with its root part 147 is inserted into the bladder 145 in the longitudinal direction of the profile, normal to the image plane in FIG. 6, which can take place before or after the profile is bent, depending on the circumstances and the choice of material.

In FIG. 10, the lower tool 150 of a tool for internal high pressure deformation is already drawn. It has a separating surface 152 and an engraving 151. A groove 153 is machined into the engraving 151, into which the flange 146, which is not yet fixed in its direction, is inserted when the workpiece is inserted. The groove 153 can thus have an arbitrary course and angle 149 over the length of the engraving 151. When the workpiece is inserted, the tool for internal high pressure deformation can be closed.

11 shows this closed tool after the internal high pressure deformation. The upper tool 155 with the engraving 156 and the parting surface 157 is still clamped with the lower tool 150. It can be seen that the internal pressure inside the profile 140 ', which has already been deformed, has placed it against the engravings 151, 156 of the two tools and has assumed its final cross section. The internal pressure also has a very special effect: it has the bladder 145 pressed against the root part 147, so that the polygonally deformed bladder 145 'has firmly applied to the edges 148 of the root part 147 and has thus fixed the flange 146 in the position determined by the groove 153 in FIG. 6.

So far, two different profiles and two different methods of fixing the flange have been described. It is noteworthy that both different methods of fixing the flange can be combined with both profile types.

Claims

Patent claims

1. A method for producing a tubular and spatially curved structural part (1) from an extruded profile (20; 40; 140) with a longitudinally extending projecting flange (6; 46; 146), in the following steps: a) the cut extruded profile (20; 40; 140) is bent so that its shape at least approximates the desired curvatures of the final shape of the structural part, b) a deformation is then carried out in which the cross section of the extruded profile (20; 40; 140) changes and the flange ( 6; 46; 146) is directed.

2. The method as claimed in claim 1, characterized in that the deformation (step b in FIG. 1) is divided into two steps: b1) a preliminary deformation in which the extruded profile is brought into a preform (50, 51) suitable for the following internal high-pressure process and the flange (6; 46; 146) is straightened, and b2) an end fitting according to the internal high-pressure process, the flange (6; 46; 146) in the parting plane between the upper and lower tool (30,33; 60,61; 150) comes to rest.

3. The method according to claim 1, wherein the extruded profile (20; 40) in cross section has a projecting flange (6; 46; 146), characterized in that before bending from the flange (6; 46; 146) there are interruptions (14 ) are cut out.

4. The method according to claim 1, characterized in that a further bending takes place during the deformation.

5. The method according to claim 2, characterized in that the flange (6; 46; 146) for straightening between an upper and a lower pre-forming tool (50,51) is clamped by compressing them, the angle at which the flange protrudes , is changed in places.

6. The method according to claim 2, characterized in that the flange for straightening between an upper and a lower pre-forming tool (50,51; 70,71) is machined with an additional slide (73).

7. The method according to claim 1, characterized in that when inserting the bent and optionally pre-formed extruded profile (20; 40; 140) in the mold (30.31; 60.61; 150.155) for the internal high pressure - deformation of the flange (6; 146) is inserted into a groove (153) of the tool (150).

8. The method according to claim 2, characterized in that when inserting the bent and pre-formed extruded profile (20; 40) in 5 the shape for the deformation according to the internal high pressure method of the flange (6; 46) is inserted into a recess (36; 62) in the separating surface (32) of one of the two halves (30, 33) of the tool.

9. The method according to claim 7, characterized in that the

10 Flange (146) in the groove (153) of the tool (150, 155) has some play so that it can shift during the deformation.

10. The method according to claim 8, characterized in that the flange (6; 46) in the recesses (36; 62) of the tool (30,33;

15 60.61) has some play so that it can shift when deformed.

11. The method according to claim 1, characterized in that in cross section the extruded profile (140) has an inwardly extending bubble (145) and the flange (146) has a root (147) and that the root (147) before bending of the flange is inserted into the bladder (145).

12. The method according to claim 1 1, characterized in that the 5 insertion of the root (147) of the flange into the bladder (145) in the longitudinal direction of the structural part (1).

13. The method according to claim 1 1, characterized in that in the subsequent deformation after the high pressure process, the 0 bubble (145) compressed and the root (147) of the flange (146) is firmly connected to the bladder (145) in the desired angular position.

14. Structural part of a motor vehicle body long, tubular and spatially curved shape with a flange for attaching add-on elements, which consists of a closed extruded profile with a longitudinally extending projecting flange, characterized in that the structural part (1) has a variable length Has a cross-section, and that the flange (6; 46; 146) is variable and dimensionally stable in the course and direction (38; 49) of its protrusion over the length of the structural part (1).

15. Structural part according to claim 14, characterized in that the flange (6; 46; 146) has interruptions (8; 14) in places.

16. Structural part according to claim 15, characterized in that the flange (6; 46; 146) has notches (14) in zones of strong bending.

17. Structural part according to claim 16, characterized in that the cross section of the extruded profile (20) is approximately square, the flange (6) protrudes in the symmetry (23) of a square side, and the square side has inclined sides (24) on both sides of the flange, so that it forms an obtuse angle (25) with the flange (6).

18. Structural part according to claim 14, characterized in that the cross section of the extruded profile (40; 140), which is assumed in the manufacture, is substantially circular.

19. Structural part according to claim 18, characterized in that the cross section (140) is drop-shaped, the flange (146) on the

Circumferential part (142) is arranged with the smallest radius of curvature.

20. Structural part according to claim 19, characterized in that the flange (146) is inserted into the extruded profile (140) and is fixed by deformation according to the internal high-pressure process.

21. Structural part according to claim 20, characterized in that in cross section the extruded profile (140), which is used in the manufacture, consists of an outer wall (141) and an inner bladder (145), the outer wall ( 141) interrupted and their spaced apart interrupt edges (148) are connected by the bladder (145), and that the flange has a root part (147) which is located in the bladder (145).

22. Structural part according to claim 21, characterized in that the cross section of the root part (147) is poligonal and that of the bladder (145) is round.