EP2727665B1 - Method for making a moulded part and use of the method for making a moulded part - Google Patents

Description

The present invention relates to manufacturing technology of structural components. In particular, the present invention relates to the construction of an aircraft structure. Furthermore, in particular, the present invention relates to a method for producing a molded component, the use of the method according to the invention for producing a molded component, a molded component and a means of transport, in particular an aircraft, comprising a molded component according to the invention.

Especially in the aircraft sector structural components for example, an aircraft skin are needed, which are on the one hand very easily formed, on the other hand, however, have the necessary structural capacity, which is required in an aircraft operation.

In this case, a conventional aircraft structure is usually designed as a structural structure which, for example in the case of the aircraft casing, has a large-area, thin-walled casing, which obtains the necessary stability through bracing elements, such as stringers, ribs and ribs. Here, usually the underlying structure is constructed in sections and the outer shell connected by suitable connection method with this structure. However, this requires, as the individual components are manufactured separately, a very high manufacturing accuracy in order to realize a final satisfactory assembly with a required accuracy.

DE 100 48 491 A1 describes a method for forming structures of aluminum alloys, wherein a component to be formed is elastically deformed and then heated.

EP 2 364 794 A1 describes a method for producing a metal component, wherein the processing temperature is between 325 and 350 ° C.

JP 2004 136306 A discloses a method and apparatus for molding magnesium alloy workpieces by hot pressing.

According to the invention, a method is now provided for producing a structural component, in particular for an aircraft envelope, which essentially forms such elements or sections in one piece and thus realizes a reduced production outlay.

Accordingly, a method for producing a molded component, a use of the method according to the invention for producing a molded component, a molded component as well as a transport means comprising a molded component according to the invention are provided according to the independent claims. Preferred embodiments will be apparent from the dependent claims.

According to an exemplary embodiment of the present invention, there is provided a method of manufacturing a mold member, comprising the steps of providing a metallic raw material, heating the raw material to a processing temperature, forming the raw material to obtain a mold member having a desired geometry using a mold, maintaining the processing temperature for a defined period of time after shaping to reduce stresses in the mold member, wherein the molding is formed as a plastic molding and wherein the processing temperature is between 220 ° C and 280 ° C.

According to a further exemplary embodiment, the molding tools are used both in the heated state and in the cold state, preferably room temperature. In particular, when using the molds in the unheated state, it is advantageous if the heat transfer from the mold to the raw material and vice versa is minimal. Preferably, the thermal conductivity of the mold is low, for example at a mold made of high-alloy steel, for example X5CrNi18-10, below 20 W / mK.

According to a further exemplary embodiment, the molds are kept closed after completion of the molding to reduce stresses in the mold component for a defined period of time. By low heat exchange between the molds and the raw material, the reduction of stresses for heated as well as cold molds can be realized.

According to a further exemplary embodiment, use of the method for producing a molded component, in particular for a means of transport, more particularly for an aircraft, is used.

According to a further exemplary embodiment of the present invention, a molding component, in particular for a means of transport, further, in particular for an aircraft, is provided, which was produced using the method according to the invention.

According to a further exemplary embodiment of the present invention, a means of transport, in particular aircraft, comprising a mold component according to the invention, is displayed.

Especially in the field of aircraft cockpit, the aircraft structure on the one hand has a strong-curved nature, on the other hand, just these parts are regularly exposed to increased stress, such as a bird strike. Especially due to the increased curve shape, a high-precision provision of individual elements of the aircraft structure is of particular importance.

According to the invention, a molding component is produced from a, in particular metallic, raw material. Here are specially AlMg or AlMgSc alloys proven their suitability many times. Aluminum alloys with scandium admixtures are in particular suitable for the production of mold components according to the invention.

Thus, according to the invention, a metallic raw material is provided which, after being heated to a processing temperature, is deformed using a mold such that the desired geometry of a later molded component is achieved. The molding of the raw material to obtain the molding member is formed here as a plastic molding. In other words, in the process of molding, the raw material is already deformed so that it would not go back to its original shape, such as a plate-like raw material, even if the manufacturing process was stopped. After a desired geometry of the later molded component has been produced as part of the step of forming the raw material, according to the invention, this mold is held for a defined period of time while maintaining the defined processing temperature. The defined processing temperature is less than 325 ° C, in particular in the range of 250 ° C. Maintaining the processing temperature for a defined period of time e.g. 30 minutes without further deformation serves to reduce stresses in the molded part.

In the research and development of the present invention, it has been found that the speed of molding has no significant influence on later stresses in the mold component, provided that a sufficient relaxation step is provided to maintain the working temperature for a defined period of time after shaping to degrade Stresses in the mold component, in particular without further change in the geometry of the mold component. Furthermore, in the research and development of the present invention, it has been found that, in fact, the process of cooling the mold component, in particular the temperature difference that occurs, is mainly for after-mold production predominant material stresses is responsible. Accordingly, a lower processing temperature also causes less total stress of the mold component. A particularly preferred temperature here is substantially 250 ° C. At the same time, molding at a reduced processing temperature of, for example, about 250 ° C allows the use of materials having a lower recovery temperature. Materials with such a reduced crystal recovery temperature in turn have an increased strength compared to. Materials with a higher crystal recovery temperature.

The use of a processing temperature lower than 325 ° C, for example, substantially in the range of 250 ° C, thus enables the production of molded parts with significantly reduced internal stresses and at the same time higher strength of the material than in a process with a processing temperature of 325 ° or more would be possible.

According to a preferred embodiment of the present invention, the method according to the invention may further comprise the steps of cooling the molding component and, in particular, reworking the molding component.

Cooling of the mold component can in this case still take place in the mold or outside of the mold or with removed mold, for example in air. Cooling in the mold on the one hand only allows the passive cooling of the mold component, on the other hand, other components may be provided, for example on the mold, which allow an active cooling or a controlled cooling. By means of a suitable cooling temperature profile, a preferred reduction of stresses in the molded component can subsequently be realized. Post-processing of the molded component may be necessary for obtaining the finished molded component, as will later be used, for example, in an aircraft structure.

According to a further preferred embodiment of the present invention, the post-processing of the mold component may include forming a support structure or strut structure, in particular by machining, e.g. Milling, be.

Thus, from a suitable raw material in a processing passage the desired final shape can be produced, wherein subsequently by removing material from the thickness of the molded component struts can be made comparable to stringers, ribs or ribs in the material from the solid. Such a structural structure or strut structure has due to the integral with the shell of a molded component an ideal connection.

The lower the processing temperature or the temperature increase between normal temperature (ambient temperature) and mold temperature, the lower are the stresses induced in the material of the mold component during a cooling process.

According to a further preferred embodiment of the present invention, after the step of reworking the molded component, no further processing step for reducing internal stresses, in particular no renewed heating, may be necessary.

Owing to the reductions in the internal stresses in the molded component due to a reduced processing temperature, it is possible to dispense with further relaxation steps in a suitable production method, in particular after the formation of the structural structure or bracing structure.

According to another preferred embodiment of the present invention, the defined period of time may not substantially exceed 30 minutes.

Such a period of time may be sufficient to break down stresses which occur essentially completely or significantly in the material due to relaxation.

According to a further preferred embodiment of the present invention, the raw material may already be provided preformed or preformed before heating.

By such preforming, it may further be possible to pre-shape the raw material or the blank to a certain extent to the desired geometry to be assumed later, so that in particular the steps of heating and forming the raw material can be simplified. Punctures in the raw material possibly occurring due to the preforming can likewise be degradable by the relaxation step.

According to a further preferred embodiment of the present invention, the raw material may be formed as a thick plate or as a solid material, in particular with a thickness in the range of 50 mm to 400 mm, 300 mm or 200 mm, more particularly 80 mm to 150 mm.

Such a configuration as a thick plate or solid material allows after forming a machining reworking for the production of a structural structure or bracing structure of the solid material. In the context of the present invention, a thick plate or solid material should therefore be understood as meaning any material with a thickness which is suitable for being able to form a suitable structural structure or bracing structure after the shaping step in the finishing step.

According to another preferred embodiment of the present invention, the raw material may be formed as a material selected from the group consisting of AISc alloy, MgSc alloy, AlMgSc alloy and Sc alloy.

According to a further preferred embodiment of the present invention, a mold component is provided, wherein the mold component may be formed as a cockpit mold component, a door mold component, in particular a door frame, a bow bulkhead mold component or a chassis mold component.

In particular, these types of molded components have in common that they are exposed to increased stress during operation of the aircraft and thus are particularly preferred to provide fixed. In general, the method can be usefully applied to all integral mold components that are exposed to high operating loads.

Fig. 1a

einen exemplarischen Aufbau eines Cockpitbereiches einer Flugzeugstruktur;

Fig. 1b-1j

exemplarische Ausgestaltungen von Formbauteilen für eine Flugzeugstruktur gemäß der vorliegenden Erfindung;

Fig. 2

eine exemplarische Ausgestaltung des Verfahrens zur Herstellung eines Formbauteils gemäß der vorliegenden Erfindung;

Fig. 3

eine exemplarische Darstellung der Reduzierung des Verzuges und damit der geometrischen Abweichung gegenüber der Zielgeometrie nach Abkühlung eines Formbauteils gemäß der vorliegenden Erfindung.

Hereinafter, reference will be made to embodiments of the invention with reference to the accompanying drawings. Show it:

Fig. 1a

an exemplary structure of a cockpit area of an aircraft structure;

Fig. 1b-1j

exemplary embodiments of mold components for an aircraft structure according to the present invention;

Fig. 2

an exemplary embodiment of the method for producing a molded component according to the present invention;

Fig. 3

an exemplary representation of the reduction of the delay and thus the geometric deviation from the target geometry after cooling of a mold component according to the present invention.

Further referring to Fig. 1a an exemplary construction of a cockpit area of an aircraft structure is shown.

Fig. 1a shows the front area of an aircraft structure, in particular the cockpit area, with window openings, the bow bulkhead, which must be able to withstand bird impact in particular, the chassis area and at least one entrance door with a corresponding door frame.

Traditionally, such structures have been formed by constructing a structural structure or strut structure having substantially the desired shape or geometry of the aircraft structure and subsequently sealing it by suitably shaped surface elements. Such surface elements are thus subsequently connected using suitable connection methods such as screwing, welding or riveting to the structural structure.

Due to the increased load on the front portion of an aircraft structure, a particularly preferred material is a metal or a metal alloy.

Fig. 1b now shows the structure of a front portion of an aircraft structure according to the present invention.

Individual elements such as the door frame, landing gear, cockpit and bow bulkhead are integrally manufactured as separate mold components according to the method of the present invention. In particular, the desired geometry, in particular outer geometry of the aircraft structure, is provided by the shaping of the raw material, after which a solid shaped component has arisen after the relaxation step and the cooling step, which is then further processed in a post-processing step, so that an internal structure or strut structure is formed becomes.

This forming, for example, by removal, for example by milling, of material from the solid of the cooled mold component can be realized. With a corresponding reworking is thus the weight of the individual Mold component significantly reduced by removal of unneeded material from the thickness of the blank, while at the same time the required structural structure or bracing structure can be formed by this removal.

Since the reworking takes place on an integral, one-piece, geometrically shaped shaped component, no further significant stresses or distortions of the molded component occur in this case, but this is strengthened by the formation of the bracing structure in its strength. The inventive method thus has its particular advantage in the simple construction of a non-orthogonal structural structure or strut structure and the subsequent receipt of a one-piece mold component, which may also have a significant curve, which could result in accuracy problems in conventional manufacturing processes of aircraft components.

Fig. 1c-1j show individual exemplary embodiments of mold components according to the present invention in detail.

Fig. 1c, d represent a part of a cockpit, especially with window openings. Fig. 1e, f show an exemplary embodiment of a door frame, while Fig. 1g, h represent an exemplary embodiment of a bow bulkhead. Especially at the bow bulkhead and subsequently at the chassis, as in Fig. 1i, j shown, the bracing structure or structural structure on one side, usually the inside, thus the side facing the aircraft interior, recognizable. The exact design of the structure of the structure here is due to the respective mold component, but is based essentially on known structural structures, in particular of aircraft.

Further referring to Fig. 2 An exemplary embodiment of a method for producing a molded component according to the present invention is illustrated.

The method 10 for producing a molded component begins by providing 12 a raw material. In this case, particular preference is given to metallic alloys, such as, for example, aluminum scandium or aluminum magnesium scandium. Essentially, however, any plastically deformable raw material which is deformable in a suitable thickness and post-processable to form a suitable bracing structure is suitable for carrying out the method according to the invention.

The optional pre-forming step 24 already allows the geometry to be adjusted prior to the actual heating and shaping of the raw material, which, among other things, makes it easier to handle the raw material. The preform is typically made by known forming methods such as roll forming or bending and ideally is designed so that the final component geometry is already achieved to a good approximation. The subsequent hot forming step can thus be done quickly and inexpensively.

Subsequently, the raw material is plastically deformed 16 to obtain a molded component having a desired geometry. The deformation may be done using conventional molds, for example, by forcing the raw material into a predetermined shape. Tensions occurring in the mold component are reduced by maintaining 18 the processing temperature for a defined period of time after molding.

According to the invention, while maintaining the processing temperature, the molds used are not removed, but rather the raw material is held in the shape of the desired geometry by the molds while maintaining the processing temperature. As a result of this relaxation step, stresses in the molded component are reduced, so that after removal of the molded component from the mold, a so-called return, ie an independent deformation of the molded component due to the absence of the shaping tool, is reduced or completely avoided. The relaxation step This is also done at the previously used processing temperature, for example, substantially 250 ° C for a defined period of time such as 30 minutes or less.

After the relaxation step 18, the mold component is cooled to ambient temperature 20, which on the one hand passively, for example, by simply removing the molds and cooling in air, or may take place as an active cooling, for example using temperature-controllable molds, which allow for air cooling accelerated or delayed cooling. Likewise, a controlled cooling with a desired cooling curve or Abkühlungstemperaturkurvenverlauf by controlling the temperature of the mold is conceivable.

After cooling 20 of the molded component, this is post-processed 22. During reworking by suitable methods, such as milling, a structural structure or bracing structure integrally formed on or in the mold component. This sloping material can be reused via known recycling processes.

Further referring to Fig. 3 For example, an exemplary embodiment of reducing stress in a mold component by warpage after cooling in accordance with the present invention is illustrated.

The distortion mentioned above represents a so-called springback or a change in geometry of a molded component. The change in geometry represents a deviation between the desired or required geometry, as can be produced using the molds during the molding of the raw material and ultimately after removal of the molded component the geometry adjusting the mold.

Such a change is exemplary in Fig. 3 shown. As indicated above, elevated temperatures occur at elevated cooling temperature or at an increased difference between processing temperature and temperature in the cooled state. According to Fig. 3 For example, the exemplary deviation from the target geometry for a 325 ° C forming process is 2.8mm, whereas for 250 ° C forming, there is a deviation of only 1.4mm, thus halving the deviation from 325 ° C. A molding at 300 ° C has the result of a deviation of example 1.9mm, while a molding at 275 ° C has a deviation of 1.6mm. In each case, the mean value of a series of measurements was used.

How so Fig. 3 can be clearly seen, results in reduced processing temperature, for example, 250 ° C compared to 325 ° C, a significant reduction of the Springback, which results from a disproportionate reduction of induced by the cooling process in the material stresses.

LIST OF REFERENCE NUMBERS

10

Process for producing a molded component

12

Providing a raw material

14

Heating the raw material

16

Shapes of the raw material

18

Maintaining the processing temperature / relaxation

20

Cooling of the molded component

22

Reworking of the molded part

24

Preforming of the raw material

Claims (8)

1. Method (10) for producing a molded component, comprising the steps

   - Providing (12) a metallic raw material of an aluminum magnesium scandium alloy (AIMgSc);

   - Heating (14) the raw material to a processing temperature;

   - Molding (16) of the raw material to obtain a molded component having a desired geometry using a mold tool;

   - Maintaining (18) the processing temperature for a defined period of time after molding to reduce stress in the molded component;

   - Cooling (20) the molded component; and

   - Reworking (22) of the molded component;

   wherein the processing temperature is between 220°C and 280°C;
   characterized in that
   the molding of the molding component is performed as a plastic molding;
   while maintaining (18) the processing temperature, the molded component is held in the mold tools for a defined period of time to relieve stresses in the molded component;
   the reworking of the molded component is a forming of a non-orthogonal framework structure;
   the raw material as a thick plate or rather is formed as a massive material.
2. The method of claim 1, wherein the reworking of the molded component is milling.
3. Method according to one of the preceding claims, wherein the processing temperature is less than 280°C, more particularly less than 260°C, more particularly in the range of 230°C to 270°C, more particularly in the range of 240°C to 260°C, more particularly, is substantially 250°C.
4. Method according to one of claims 1 to 3, wherein after cooling and / or reworking of the molded component no further processing step for the reduction of internal stresses takes place, in particular no reheating.
5. Method according to any one of claims 1 to 4, wherein the defined time does not exceed substantially 30 minutes.
6. A method according to any one of the preceding claims, wherein the raw material is already preformed or is preformed (24) before heating.
7. Method according to any one of the preceding claims, wherein the thickness of the thick plate or the massive material is from 50mm to 400mm, 300mm or 200mm, more particularly 80mm to 150mm.
8. Use of the method according to one of the preceding claims for producing a molded component, in particular for a means of transport, more particularly for an aircraft.

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