EP1534443B1 - Method for the production of structure components from an extruded profile - Google Patents

Description

The invention relates to a method for the production of structural components from an extruded profile, in particular consisting of aluminum (A1), magnesium (Mg), or their alloys, which after emerging from the die of the extruder for the purpose of its formation as a straight or arcuate or rounded Profile is guided by one or more guide tools, after which an end portion is separated with a cutting tool and fed to one or more other processing stations in succession.

Such a method is known in the art, e.g. in the field of car manufacturing, known. The space frame concept known in the automotive industry uses such extruded aluminum profiles both as straight profiles and in the form of rounded profiles. A manufacturing method for this purpose is described, for example, in European Patent EP 0706843 B1.

With the increasing importance of lightweight construction in the construction of motor vehicles, in addition to aluminum profiles, those made of magnesium or alloys of the two materials, eg AlMgSi, AlZnMg, MgAl3Zn1 (AZ 31) or MgMn2 (AM 503) are increasingly used. In the production of structural components of the materials mentioned occur significant problems that have to do in particular with the production-related cross-sectional deformations in bent extrusions and their springback, which is difficult to control and therefore causes additional costs in further processing, eg if an automated production is desired. In subsequent machining operations, such as cutting or joining, residual stresses of such extruded sections are often released, which are difficult to control and make the compliance with the required accuracy in question.

We are therefore looking for a new manufacturing concept in which starting from the extrusion process structural components with particularly high accuracy in terms of the dimension of the profile cross-section and possibly their curvature can be produced while reducing the cost or reasonable low cost increase.

In order to meet the technical requirements has already been proposed to perform a calibration of the contour and the cross section by hydroforming (IHU) of the extruded. The disadvantage here, however, the extremely high tooling costs.

On the other hand, it is difficult or even impossible, but at least associated with unreasonably high cost, extrusion profiles with the required accuracy for the final product directly, i. to produce as a direct result of the extrusion process.

Even after the known method of direct rounding of the extruded profile at the exit from the die by exerting a controlled transverse force to bend the profile to achieve the required contour fidelity, especially in three-dimensional profiles with variable curvature hardly surmountable technical difficulties. In contrast, there is an essential proposal according to the present invention is that after severing a portion of the extruded profile by means of a separating tool, the separated end portion while maintaining the heat of the hot strand in the hot state by means of gripping tools is fed to a hot forming process. With this step it is achieved that the heat of the hot strand is maintained for the downstream hot forming process, as a result of this hot forming process ready to install components can be produced. In this case, depending on the material suitable working window with respect to the forming temperature with optimum formability for aluminum or magnesium or aluminum / magnesium alloys without additional energy consumption or without great energy expenditure, for example by cooling the workpiece can be realized.

In the interest of producing salable products, instead of a complex forming process, for example in the design of hydroforming, preferably economically favorable hot forming processes such as forging or embossing come into question.

A particular advantage of the method according to the invention is that it offers the possibility of accepting lower accuracy requirements with regard to the contour of the extruded profile, since the hot forming step can be used simultaneously for calibrating in order to obtain the exact shape of the finished structural component.

An additional advantage of the method according to the invention is that by including the Process step of the hot forming an increase in the value added is made possible by the fact that in the same process step further design features of the final product can be realized as the introduction of holes, the production of small formations or the like.

Due to the lower accuracy requirements of the extrusion, the extrusion rate can be increased, making a more economical use of the associated in their purchase at high cost extrusion line is possible.

In the production of structural components of magnesium or magnesium alloys, it is expedient for the preservation of the structure that the manufacturing chain is completely or partially covered in inert gas, namely from the extruder to the hot forming process. In this context, it has already been proposed to also perform the casting process upstream of the extruder in an inert atmosphere.

According to a further proposed invention, it is provided that Al and Mg semi-finished parts are joined together by means of friction stir welding to form new structural components. This can conveniently be done in a welding and machining center, which is followed by the subsequent to the hot forming process hot curing.

Alternatively, the joining of Al and Mg components by gluing in question. It should be noted that the adhesive components after the hot forming process be applied so that the final strength is achieved in the subsequent hot curing.

A possible embodiment of the forming process is that the extruded profiles in an hydroforming step (hydroforming) are further processed. However, the associated high tool costs often speak against the use of the desirable because of its accuracy in itself IHU process. For calibrating Al components, the hydroforming is, as usual, always designed as cold forming; By contrast, Mg components are advantageously a hot forming process. In this way, the formation of an unfavorable hexagonal metal lattice structure is avoided for the first time.

As a much cheaper forming process, forging is to be considered; Also possible is an embossing step designed as hot forming, which has a higher accuracy compared to forging. A sequential sequence of both methods may possibly be advantageous.

In order, for example, to obtain structural components produced by forging in a hot forming process with a desired high dimensional accuracy, it is advantageous according to the invention that the hot forming process also comprises a calibration step which, for example, follows the forging.

All process steps have in common that they require an exact temperature control for their optimization. Based on the heat of the hot strand from the extruder, it is about this, for the subsequent Take advantage of hot forming process, ie for the hot working to ensure that temperature range within which an optimal deformation result is to be expected in adaptation to the processed material.

In this sense, it is provided according to a further proposal according to the invention, that in the hot forming process, the hot working temperature or before other processing stations, the processing temperature is set by cooling the workpiece to the optimum temperature for the respective alloy of the workpiece to be produced.

For the production of Mg structural components, this advantageously means the setting of a hot working temperature of 180 ° C to 400 ° C, preferably 225 ° to 280 ° C.

In the case of a so-called hardenable aluminum wrought alloy (Al-Mg-Si alloys), a suitable temperature for hot forming after extrusion is below 200 ° C. Here, the cooling of the extruded profile has expediently be carried out so abruptly that it does not come to Mg ₂ Si precipitates in a temperature range of 520 ° C to 200 ° C. The subsequent hot forming step is then carried out in the shortest possible time to take advantage of the full formability of this material here too; before it comes to material hardening by Mg ₂ Si precipitates.

For the production of Al structural components, it is advantageous according to the invention, the hot working temperature between 300 ° C and 600 ° C, preferably between 400 ° C. and to adjust to 520 ° C; If an embossing step is provided, it is expedient to set the forming temperature at the upper limit of the stated temperature range, ie near 600 ° C.

In the context of the invention, in the processing of Al and Mg structural components to the hot forming process further processing stations can follow, preferably the hot curing in the heating furnace and then various mechanical processing stations, the workpiece can be cooled before hot curing in an upstream cooling zone. The cooling zone can also be provided before the hot forming process. This applies in particular to the processing of hardenable Al wrought alloys. As already stated above, this involves the avoidance of undesired microstructural hardening by Mg ₂ Si precipitates.

In order to realize an optimized linking of the entire finished process, extensive automation is already advantageous, due to the high process temperatures. In particular, one can thereby avoid the intermediate storage of semi-finished parts.

This purpose is served by further embodiments of the invention, according to which the workpiece is transferred between the processing stations of gripping tools in the manner of handling robots and, furthermore, that guiding and separating tools are likewise designed in each case in the form of robots, namely as guiding and separating robots. While the guide robots are supported spatially fixed outside the strand to take over deformation forces, the separation robot allow their Movement with the strand by being fixed on the emerging strand in the region of the separation point, at least as long as the separation device of the separation robot works.

The guide robots have a guide device, which is movable in a plane perpendicular to the pressing plane and / or rotatable about its longitudinal axis. It serves to deform the extruded profile within a plane of constant or variable radius and to twist the profile about its longitudinal axis.

It is also advantageous that the cycle times with which the process and processing steps follow one another, are significantly adapted to the respective extrusion rate. Accordingly, it is contemplated by the invention that for the production of Al structural components after extrusion, multiplication, e.g. a doubling of the production chain required for Mg structural components is established. This results as a result of significantly higher extrusion rates for aluminum components (up to 25 m / min) compared to magnesium components (up to 1.5 m / min).

In the production of structural components of rounded extruded sections, which occur particularly frequently in the body shop, the invention provides that at least one guide robot depending on the pressing path of the extruded and the respective curvature path-controlled, the Preßweg attached directly to the exiting strand by means of a guide robot Sensor device can be measured.

The extruded profile is thereby deformed by the guide robot and expediently supported by a handling robot, to be finally cut to length by a separation robot. With simple geometry of the component, a run-out table can be sufficient for support.

In the minimal equipment can be required for the manufacturing process according to the invention in addition to the separation robot and a handling robot that receives the separated component and the hot forming process, possibly only a guide robot that takes over the rounding of the straight emerging from the extruder extrusion and this supports the same time. Under certain geometric conditions, both straight and curved components can be produced. For particularly complex components, e.g. rounded with variable radii and also be deformed by twisting, at least two guide robots are appropriate.

Robot technology requires a particularly great effort for the production of spatially rounded extruded profiles with variable curvature. When realizing such contours, at least two spatial axes and the angle of rotation must be numerically controlled in addition to a displacement sensor. In this case, the three-dimensionally curved extruded profile can no longer be placed on a run-off table, but must be supported in the space of two or more handling robots so that an undesirable deformation of the still soft extrusion is avoided.

Fig. 1

zeigt ein Blockdiagramm zu einer Fertigungskette für ein Al-Strukturbauteil;

Fig.. 2

zeigt ein Blockdiagramm zu einer Fertigungskette für ein Mg-Strukturbauteil.

Two exemplary embodiments of the production chain proposed according to the invention are described below.

Fig. 1

shows a block diagram of a manufacturing chain for an Al structural component;

Fig. 2

shows a block diagram of a production chain for a Mg structural component.

As far as the two production chains according to FIGS. 1 and 2 agree, the same reference numerals are used.

According to FIG. 1, an extrusion press 1, one or more guide robots 2 are connected downstream, which are controlled by means of a travel control 4. The guide robots 2 have guide means, e.g. in the form of roller cages which guide or support the extruded extruded from the extruder 1 and - in the case of a rounded profile - deform with constant or variable curvature in a plane or in space. For this purpose, it is necessary to measure the path of the extruder leaving the press exactly what is done advantageously with a non-contact path sensor of a path control 4, and to measure the curvature, which is preferably done by three non-contact optical sensors, the transversely to Profile are arranged movably on rails.

Depending on the complexity of the contour of the extruded profile and depending on its dimensional stability in the hot state, up to three handling robots 3 may be required, which take the profile without the exercise of deformation forces, and finally to a Subsequent separating robot 5 pass, which is provided with a cutting tool, for example in the form of a circular saw, which cuts the extrusion during a brief interruption of the extrusion process. Alternatively, it is possible to use a flying saw, which cuts through the extrusion without interruption of the extrusion process by being moved together with the separation robot to which it is attached, with the extrusion.

In the case of a three-dimensional contour of the rounded extruded profile a plurality of moving handling robot 3 are required, which are controlled so that they can be returned upon reaching an end position in a starting position, so that preferably always attack two handling robot 3 on the extrusion profile, while a third handling robot is implemented. In the case of three-dimensionally rounded or curved components, it may be advantageous, instead of a guide robot 3 with a roller cage, through which the emerging strand moves, to use at least two guide robots, which are provided with a gripper system which is capable of firmly fastening the extruded profile to be able to transfer moments to this, so that the respective desired three-dimensional contour of the extruded profile consisting of curvatures and rotations can be achieved. In this case, the guide robots 2 also take over the task of a handling robot 3.

The separated extruded profile is taken over by a handling robot 3, which either directly to the hot forming process 8 or upstream of this Cooling zone 9 feeds (Fig. 1). After passing through the hot forming process 8, for example in a forging die, the finished-shaped structural component is in turn subjected to the process step of hot curing 10 via handling robot 3 or another transport device, before it is fed to a downstream processing center, for example by means of further handling robots 3.

If the Al structural component according to FIG. 1 is to be connected to further Mg modules, this is done either by gluing 7 before hot hardening 10 or in a welding and machining center 11 for friction stir welding of Al-Mg modules. Further machining can be done in a conventional machining center 12. Only then can the finished structural component be delivered to the dispatch 13.

The dashed line in FIG. 1 cooling zone 9 is only required for special materials in which a rugged cooling before the hot forming process 8 is essential, as is the case, for example, on hardenable aluminum wrought alloys (Al-Mg-Si alloys). In these alloys, it is important to avoid hardening by Mg ₂ Si precipitates in a temperature range of 520 ° to 200 ° C.

Fig. 2 relates to the production of structural components of Mg or Mg alloys. There is an indicated by a dashed frame 14 inert gas atmosphere required to ensure the unchanged microstructure of the processed material. The inert gas atmosphere includes all manufacturing steps from the exit from the extruder 1 to the entrance to the hot forming process 8.

The hot forming process 8 may be followed by a cooling zone 9, which serves to accelerate the process, i. a faster supply of the extruded to the subsequent curing in the heating furnace 10 allows. Such a cooling zone 9 is of course also in connection with the process control of FIG. 1 conceivable. If necessary. the component can be connected by gluing 7 with other components or modules before hot curing 10.

Claims (19)

1. A method for manufacturing structural components from an extruded section, especially consisting of Al, Mg or their alloys, which after its exit from the die of the extrusion press (1), is guided by one or a plurality of guide tools (2) for the purpose of forming it into a straight, an arc-shaped or a rounded section, respectively, after which an end section is separated by a separating tool and is fed successively to one or a plurality of processing stations, characterized in that, after the separating step, the separated end section is fed in the hot state by means of gripping tools to a hot-forming process (8) retaining the heat of the hot section.
2. The method according to claim 1, characterised in that, for manufacturing Mg structural components, the production chain is completely or partly enveloped by protective gas.
3. The method according to claim 1, characterised in that, for the manufacturing of workpieces made of Al and Mg structural components, these are joined together by means of friction stir welding (11) or adhesion (7).
4. The method according to claim 1, characterised in that the hot-forming process (8) is configured as internal high-pressure forming, forging or embossing.
5. The method according to claim 1, characterised in that the hot-forming process (8) comprises a calibration step.
6. The method according to claim 1, characterised in that before the hot-forming process (8), the hot-forming temperature or before either processing stations, the processing temperature is adjusted to the optimum process temperature by cooling the workpiece.
7. The method according to claim 6, characterised in that, for the manufacture of Mg structural components, the hot-forming temperature is between 180 °C and 400°C, preferably 225 °C to 280 °C.
8. The method according to claim 6, characterised in that, for the manufacture of Al structural components, the hot-forming temperature is between 300°C and 600 °C, preferably 400 °C to 520 °C.
9. The method according to claim 1, characterised in that as further processing stations the hot-forming process (8) is followed by artificial ageing (10) and then by mechanical processing, wherein the component is cooled in a preceding cooling zone (9) before the artificial ageing (10).
10. The method according to claim 1, characterised in that the workpiece is transferred between the processing stations by gripping tools in the form of handling robots (3) which follow the extruded section.
11. The method according to claim 1, characterised in that guide and separating tools are each constructed in the fashion of robots, namely as guiding (2) and separating robots (5).
12. The method according to claim 11, characterised in that guiding robots (2) are each supported in a spatially fixed position outside the extruded section and are provided with a guiding device which is moveable in a plane perpendicular to the pressing plane and/or is rotatable about its axis of rotation.
13. The method according to claim 11, characterised in that separating robots (5) are each connected firmly to the extruded section in the range of a separating point, at least while the separating device is operating.
14. The method according to claim 1, characterised in that, for the manufacture of structural components having a variable curvature, at least one guiding robot (2) gripping the extruded section is path-controlled depending on the pressing path and on the curvature trend of the extruded section.
15. The method according to claim 14, characterised in that the pressing distance is measured directly on the emerging strand by means of a sensor device attached to the guiding robot (2).
16. The method according to claim 15, characterised in that the extruded section is guided to its forming by several reversibly controlled guiding robots (2).
17. The method according to claim 1, characterised in that the cycle times with which the process and processing steps fellow one another are substantially matched to the extrusion speed.
18. The method according to claim 17, characterised in that, for the manufacture of Al structural components, at least one doubling of the production chain required for Mg structural components is installed after the extrusion press.
19. The method according to claim 16, characterised in that the extruded section is deformed by at least one guiding robot (2) wherein at least two handling robots (3) can be alternately returned to the beginning of the strand and support the emerging extruded section.

Images