DE19753658A1 - Producing a component with a layer of ductile material, and resultant component - Google Patents

Abstract

A layer of ductile material is formed by means of a pressure generated by a metal foam used in the role of a pressure medium. The apparatus incorporates a forming tool (1, 2) with a cavity (3), and means for generating or releasing a metal foam pressure medium. The tool can be brought into a loading state in which the material layer (8) to be shaped during a subsequent forming step can be introduced into the cavity (3). The resulting component comprises a layer of ductile material and a section consisting of metal foam.

Description

The invention relates to a component with a Ma formed from a ductile material Teriallage, a method of manufacturing a component that one from a ductile Material formed mate formed in at least one forming step riallage and a device for producing such a component.

For the production of thin-walled bodies with a complex external geometry, it is known corresponding starting sheet metal layers by a possibly multi-stage deep drawing process to reshape. With such a deep-drawing process, at least one process is carried out stamp on one, placed on a lower die and, if necessary, fixed in the edge area tensioned material layer lowered. As an alternative to such a reshaping The lower die and forming die are more tube-like, particularly in the manufacture Components known, these inside a corresponding mold space by pressure to transform liquid. For this purpose, the preferably tubular, for. T. featured shaped semi-finished products placed in a mold with the inner contour to be imaged, the tubular semi-finished product is closed and pressurized via a pressure source liquid filled, the tubular starting semifinished product gradually expanding and attaches to the inner wall of the mold. If necessary, can rend this forming process material continuously in the mold be pushed, which occurs during the forming process in the material tensions can be influenced in a targeted manner.

Such components produced by hydroforming (hydroforming) are used for example as exhaust pipes in vehicle construction. Besides one it is also such internal high pressure forming of tubular starting semi-finished products possible, for example a plate-shaped starting material on a lower die hang up and instead of the order usually used in deep drawing stamp the plate-shaped starting material also by ste under pressure pushing liquid against a mold wall. By such a forming Comparatively large components such as Ka can be moved Manufacture body elements. Such body elements usually have one  comparatively low inherent rigidity and only form in connection with more Ren appropriately trained body elements a stable structure.

The invention has for its object a component with at least one from one ductile material to create material layer that is characterized by a high egg distinguished rigidity with a comparatively low weight and possibly a can have complex outer geometry. The invention is also the object based, a method and an apparatus for producing such a structure partly to create.

With regard to a method for producing a component of the aforementioned This object is achieved according to the invention by a method with those in the patent solved claim 1 specified features.

This advantageously makes it possible to create a high-strength workpiece fen, which is preferably characterized by a smooth, thin-walled outer shell, and that because of the load-bearing, damping, formed by the metal foam Material section has special mechanical properties. Since the um The used pressure medium becomes part of the workpiece ches removal of the liquid or gaseous pressure medium.

According to a preferred embodiment of the method, the material layer due to the pressurized metal foam and the blowing agent even pushed against a mold wall. Due to the through the metal foam Filigree forming geometries can be achieved. The layer of material pushed through the metal foam against the mold wall subsides thereby at least in sections with permanent plastic deformation to the Molded wall. This can also lead to an adhesive bond between the metal foam and the material layer come along an inner wall of the same.

Only after completion of the metal foam caused by the pressurized The forming process of the material layer hardens the metal foam. The curing process  of the metal foam can in particular by controlled cooling of the mold wall can be influenced.

The pressure prevailing in the metal foam is preferably only reduced when when the forming process is largely completed. The pressure drop will achieved by cooling the metal foam. By lowering the temperature release of the blowing agent is restricted. In addition is it is possible to fill the space filled with the metal foam, for example by going back pull a piston element to enlarge, or vice versa by Druckbe to reduce impact of such a piston element.

One for forming the material layer from a sheet or tubular exit Material advantageous embodiment of the method is given in that Reshaping the material layer this is introduced into a mold space such that the Material layer in the mold space a first mold space partition between a mold wall and the material layer as well as one from the first mold space partition through the Material layer separate second mold space partition defined, in the context of Forming step in the second mold space partition of the metal foam as Um Form pressure medium is introduced and the material layer against the mold wall urges. The forming process is carried out due to the heating of the material layer supports the metal foam. The molding space advantageously remains closed until the metal foam has hardened completely. Only after the Me has hardened tall foam the mold space is opened and after opening the mold space the formed by the metal foam pressure medium material layer with the inside shaped metal foam section taken.

Appropriate material combinations make it possible to move between the metal foam pressure medium and the material layer formed through this an intimate Connection, in particular to achieve welding. It is also possible to ins especially through an appropriate coating of the intended for forming to achieve a solid connection with the metal foam, without, however, changing the structure of the deformed material layer becomes.  

An advantageous embodiment of the method is given in that the Metal foam printing medium is formed by a metal alloy by a Foaming agent is foamed. This propellant is advantageously in front Foaming of the metal alloy contained in the chemi substances formed. That prepared in the metal alloy matrix Blowing agent is used in a conventional manner by heating the metal matrix onto a Temperature released above a melting point of the metal alloy. That for Formation of the metal foam provided starting material can preferably se are formed by a metal powder compact, which as such in the form space is introduced and heated therein, for example by an arc becomes.

When forming comparatively thick layers of material, according to one particular preferred embodiment of the method, the Ma intended for forming Teriallage heated in advance. This supports the forming process and a too ra cooling of the metal coming into contact with the material layer foam pressure medium avoided.

During the forming process, at least that of the metal is preferably removed Foam pressure medium mold space partition to be filled gas-tight. Around an intimate contact of the material layer to be formed with the corresponding one To enable the mold cavity wall can be made from the metal foam pressure medium facing mold space partition, preferably controlled gas can be removed.

Advantageously, at least that of the metal foam printing medium filling mold space partition as part of a preparatory process step flushed with an inert gas. This makes it possible to form the metal Foam printing medium intended starting material significantly above its egg heat the melting point without removing parts of the starting material react with any air-oxygen trapped in the mold space.  

The foaming of the metal foam printing medium is advantageously such timed that metal foam is generated until that through the metal material layer pressed against the mold wall further increases the Metal foam volume hindered, so that the forming pressure is further increased becomes. It is made possible by a time-controlled process of metal foam formation in an advantageous manner, the pressure build-up in the metal foam pressure medium to control.

Especially when manufacturing smaller workpieces, it is also possible to open the workpiece foaming process and in particular occur during the forming process the maximum pressure due to the amount of foam in the mold space to control the material. It is also possible to mix the ratio between rule metal alloy and the chemical provided for the formation of the blowing agent to adjust the substance with the aim of the degree of shaping of the ductile Controlling the material position and the entire forming process as required.

To control, in particular increase the forming pressure, it is also possible to the forming pressure applied to the material layer via the metal foam for example by pressing in an auxiliary pressure stamp to change the volume of the space covered by the metal foam.

The material layer provided for forming advantageously consists of egg Nem metal sheet, in particular a relatively thin aluminum sheet or from one AL-coated metal or non-metal. The metal foam print medium will also advantageously formed by an aluminum alloy.

Regarding a device for producing a component with a pressure deformed material layer is the task specified at the beginning by a pre direction solved with the features specified in claim 25.

Advantageous developments of this device are the subject of the associated Subclaims.  

With regard to a component, the invention specified at the outset is based on the invention lying task by a component with those specified in claim 31 Features resolved.

Such a component is characterized by a comparatively high surface area goodness and a damping core also through a high section modulus, a ho hes energy absorption capacity and a high specific rigidity.

According to a preferred embodiment of the component, the pressure is reversed formed material layer from an aluminum material. Especially when used An aluminum material for forming the material layer is also the metal foam made of an aluminum material. A particularly stable embodiment of the component is achieved in that the material layer and that of the metal foam formed material section are adhesively connected. Such a GE connection can be achieved, for example, that on the metal Foam-facing side of the material layer, an adhesive layer is formed, which rend is locally melted by the metal foam and thereby a metallic connection between the material layer and the metal foam section creates.

According to a particularly preferred embodiment of the component, the mate is Rial layer formed from an initially tubular starting material or semi-finished product. This makes it possible to prevent any contact of the metal foam printing medium with the To prevent mold cavity wall of a corresponding mold.

Further details of the invention will become apparent from the following description of a preferred embodiment of a device according to the invention in conjunction with the drawing. The only figure shows:
a simplified longitudinal sectional view through a device according to the invention with a material layer accommodated therein and formed by a metal foam pressure medium.

The molding tool shown comprises at least one upper mold part 1 and at least one lower mold part 2 for forming a mold space 3 that can be divided along a mold division plane. Both the upper mold part 1 and the lower mold part 2 are provided with a heating device 4 for heating the mold space walls delimiting the mold space 3 . In the case of complex workpiece geometries, it is possible to form the mold space 3 by means of a mold which is divided several times.

At least one degassing channel 5 is formed in the upper part 1 of the mold space, via which a controlled degassing of the mold space 3 can take place. A degassing channel 6 is also formed in the lower mold part 2 , likewise for controlled degassing of the mold space 3 . A vacuum pump device can advantageously be connected to the degassing channel.

In the area of the tool parting plane or tool closing surfaces, in the embodiment shown here, a pusher device 7 is provided, via which an end section of an output semifinished product 8 inserted into the mold space 3 can be pushed towards the center of the mold space 3 in a controlled manner. The pusher 7 comprises a piston element 9 , the tool is largely displaceable from the mold space 3 in the area of the tool division plane of the molding. It is also possible to achieve additional pressure build-up in the mold by using liquid or gaseous fluids.

The delivery device 7 or the piston element 9 are also provided with a degassing channel 10 , through which a mold space partition filled by the metal foam can be degassed in a controlled manner as part of the metal foam formation process.

In the embodiment of a device according to the invention shown here schematically, the tall foam pressure medium provided for shaping the starting semifinished product 8 is formed by a preformed, compacted starting material 11 , which can first be introduced into the mold space 3 via the piston element 9 , preferably centered approximately centrally.

In the illustrated embodiment of the apparatus for converting a ur nally tubular starting semi-finished product of the molding is tool a corresponding Nachschiebeeinrichtung 7 provided on both sides, each of said Nachschiebeeinrichtungen 7 carries a preformed compact formed from a metal powder and a propellant.

The production of a metal foam composite workpiece with the preceding be written device is as follows:

First, the upper mold part 1 is removed from the lower mold part 2 and the preformed, compacted starting material 11 provided for the formation of a metal foam printing medium in the form of a cylindrical rod (shown interrupted in the figure) (or also in the form of several, e.g. two cylindrical rods) in accordingly speaking, 9 centrally formed recesses in the two piston elements. The piston elements 9 are retracted so far that they do not prevent the now following insertion of an output semifinished product 8 formed, for example, from an aluminum extrusion into the lower mold part 2 .

Now the piston elements 9 are axially displaced until they position the starting semifinished product 8 in the lower mold part 2 in its starting position. The upper mold part 1 is then lowered onto the lower mold part 2 with the application of a predetermined closing force Fs. The mold space 3 provided for shaping the component to be formed is now closed.

The starting semifinished product arranged in the molding space 3 now forms an annular space-shaped molding space partition in the embodiment shown here, separated from the starting material 11 by the starting semifinishing product 8 , and a second molding space partition provided for filling by the metal foam pressure medium.

By appropriate heating of the starting material 11 , for example by heating the mold by means of the heating device 4 , the metal foam formation process is started. Here, the metal contained in the starting material 11 is melted and the blowing agent contained in the metallic matrix is released. The metal foam, which is now continuously formed, initially fills the entire interior space formed in the starting semifinished product 8 . The foaming of the metal foam continues until the starting semifinished product 8 initially hinders a further increase in the volume of the metal foam. Since the blowing agent continues to decompose in the following, there is an all-round foaming pressure on the wall of the starting semifinished product 8 , which deforms under this foaming pressure and bears against the mold space walls forming the mold space 3 . This process is further promoted by the heat occurring during the foaming process, the gas produced, in particular propellant gas, and possibly also by venting or applying negative pressure by suction.

The pressure built up in the metal foam pressure medium and the shaping process effected by it can be controlled via the amount of the starting material 11 provided for foaming, the blowing agent fraction, the level of the temperature, the temperature control and the cooling conditions. During the inflation or reshaping of the starting semi-finished product 8 , a controlled degassing takes place via the degassing channels 5 and 6 , possibly by generating a negative pressure, in the mold space partition which is not detected by the metal foam pressure medium and is continuously reduced in volume.

While the starting semifinished product 8 expands in the molding space 3 as a result of the forming pressure applied via the metal foam, the starting semifinished product 8 can optionally be compressed or pushed with respect to its axial length by means of piston elements provided in pairs, whereby the expansion of the starting semifinished product 8 or the plastic deformation of the starting semi-finished product 8 is supported as a whole. At the latest when a maximum forming pressure built up by the metal foam is reached, the material layer originally formed by the starting semifinished product 8 lies essentially over the entire surface of the inner wall of the molding space 3 . Now the molding tool or the upper mold part and the lower mold part is cooled, the metal foam hardening. After the metal foam has hardened, the hardened metal foam can be degassed via pressure medium, for example through degassing ducts passed through the piston elements 9 , and, if this has not already been done by cooling the metal foam, can be relaxed to ambient pressure.

After completion of a corresponding metal foam degassing the mold is opened by moving the upper mold part 1 is removed again from the lower mold component. 2 The workpiece shaped according to the inner contour of the molding space 3 and stiffened on the inside by the metal foam can now be removed from the molding space 3 . Subsequently, the molding tool is again equipped with a compacted starting material 11 provided for the formation of metal foam and with the starting semi-finished product 8 provided for forming the material layer forming an outer surface of the workpiece, and a further pressure forming process can begin.

The workpiece produced as described above can, if necessary, be reworked.

Although the invention has been described using a preferred exemplary embodiment ben, in which a tubular starting semifinished product through a metal foam pressure medium was formed, it is also possible, for example, plates shaped or, if necessary, already roughly pre-formed by a deep-drawing process or bending Starting material layers through the metal foam pressure medium against an equivalent Press the appropriate mold wall and reshape it accordingly. The metal Foam printing medium can also be stacked between at least two Material layers are introduced to produce a sandwich component with through Forming resulting shape contours.

As an alternative to the discontinuous forming process described above it is also possible to use the metal foam printing medium for continuous forming in particular to use tubular starting semi-finished products. It is also possible, the starting material intended to form the metal foam printing medium directly on the starting semi-finished product intended for forming in the form of a provide appropriate coating with possibly several layers, so that immediate bar through the appropriately prepared starting semifinished product also for education  of the metal foam printing medium provided in a correspond of the mold is introduced.

The component formed is then, for example, a tubular body with high rigidity. By forming zones of different foam density, it is possible to create a To create a component with a bone structure. The foam density is preferably in Edge area of the component is higher than in the areas located further inside. The Foam density preferably changes continuously. The density distribution of the foam can be controlled in particular by the cooling process.

In the event that the foam-forming material in the form of a coating on the is prepared for the intended material layer, it is possible to load this Layering, if necessary, from several layers with different foam properties to build. This makes it possible, especially in the edge area, to be extremely inert to develop a capable zone of high foam density.

In connection with, for example, an externally supplied, preferably gaseous Shell-like components or hollow bodies can also be used against the forming pressure medium that form a pressure-formed material layer and an adjacent one Have zone of metal foam.

The material layer formed in the context of the metal foam pressure forming process does not necessarily have to bil the outer layer of a corresponding workpiece the.

The adhesion of the metal foam section to that formed by the metal foam The material layer can be coated with the metal foam facing side surface of the material layer are influenced. The metal Foam pressure medium does not necessarily have to be formed in the molding space.

Claims (35)

1. Method for producing a component, the one from a ductile material formed material layer and formed in at least one forming step has a section formed from a metal foam, wherein within the Forming step the material layer through a over the metal foam as Um Form printing medium applied forming pressure is formed. 2. The method according to claim 1, characterized in that the material layer by the forming pressure in and through the metal foam against one Form wall is pushed. 3. The method according to claim 2, characterized in that the material layer itself at least in sections with permanent plastic deformation on the mold wall creates. 4. The method according to any one of claims 1 to 3, characterized in that the Metal foam hardens after the forming process of the material layer. 5. The method according to any one of claims 1 to 4, characterized in that the Metal foam and the material layer as part of the forming process or subsequent hardening process enter into a connection. 6. The method according to any one of claims 1 to 5, characterized in that the abge pressure prevailing in the metal foam following the forming process is lowered. 7. The method according to any one of claims 1 to 6, characterized in that Reshaping the material layer this is introduced into a mold space such that the Material layer in the mold space a first mold space partition between a mold wall and the material layer as well as a second ge from the first mold space partition separated mold space partition defined, in the context of the forming step in the  second mold space partition of the metal foam introduced as a forming pressure medium and this pushes the material layer against the mold wall. 8. The method according to claim 7, characterized in that the metal foam in hardens the mold space. 9. The method according to claim 8, characterized in that the molding space after Hardening of the metal foam is opened. 10. The method according to claim 9, characterized in that after opening of the molding space the material layer formed by the metal foam pressure medium with a metal foam section formed thereon. 11. The method according to any one of claims 1 to 10, characterized in that the metal foam printing medium is formed by a metal alloy, which by a blowing agent is foamed. 12. The method according to any one of claims 1 to 11, characterized in that the blowing agent is formed from agents that are in before foaming of the metal alloy the metal alloy matrix are included. 13. The method according to any one of claims 1 to 12, characterized in that by means prepared in the metal alloy matrix by heating the metal mass trix to a temperature above a melting point of the metal alloy Blowing agent arises or becomes effective. 14. The method according to any one of claims 1 to 13, characterized in that the material layer intended for forming is heated in advance. 15. The method according to at least one of claims 7 to 14, characterized records that at least one of the mold space partitions sealed gas-tight becomes.   16. The method according to at least one of claims 1 to 15, characterized records that at least one of the mold space partitions in preparation tendency process step is flushed with an inert gas. 17. The method according to at least one of claims 1 to 16, characterized records that the foaming of the metal foam printing medium takes place until the material layer hinders a further increase in the volume of metal foam. 18. The method according to at least one of claims 1 to 17, characterized records that the pressure build-up in the metal foam pressure medium over time Chen course of metal foam formation is controlled. 19. The method according to at least one of claims 1 to 18, characterized shows that the foaming process over the amount of foam-forming material than being controlled. 20. The method according to at least one of claims 1 to 19, characterized records that the foaming process over a foam intended Amount of propellant or is controlled via the proportion of propellant. 21. The method according to at least one of claims 1 to 20, characterized records that the foaming process by the temperature control, in particular is controlled by the cooling conditions. 22. The method according to at least one of claims 1 to 21, characterized records that the pressure in the metal foam medium by an additional pressure medium is increased. 23. The method according to at least one of claims 1 to 22, characterized records that the material layer is formed from a preferably thin metal sheet is, the foam-forming material in the form of a coating of the material layer is prepared.   24. The method according to at least one of claims 1 to 23, characterized records that the metal foam pressure medium gebil by an aluminum alloy det. 25. Device for producing a component which comprises metal foam and a material layer ( 12 ) which is pressure-deformed by the metal foam, comprising:
a molding tool for forming a molding space ( 3 ), the molding tool being able to be brought into a loading position, for introducing a starting material ( 8 ) provided for forming the material layer, and a metal foam releasing device for producing or releasing a metal foam pressure medium for shaping the Starting material ( 8 ) in the molding space ( 3 ). 26. The apparatus according to claim 25, characterized in that the molding has at least a first molded part and an at least second molded part, where a tool parting area is defined between these two molded parts. 27. The apparatus according to claim 26, characterized in that the first molded part forms an upper mold part ( 1 ), and that the second molded part forms a lower mold part ( 2 ), and that both molded parts ( 1 , 2 ) are provided with a heating device ( 4 ) to heat the molded parts ( 1 , 2 ). 28. The device according to any one of claims 25 to 26, characterized in that a Nachschieb- or compression device ( 7 ) is provided for compression or re-conveying the metal foam pressure medium and / or the starting material layer ( 8 ). 29. The device according to claim 28, characterized in that the feed or compression device ( 7 ) is hen in the area of the tool parting surface. 30. Device according to one of claims 25 to 29, characterized in that a degassing device ( 10 ) is provided for degassing the mold space partition filled with the metal foam pressure medium. 31. Component consisting of a material layer formed from a ductile material and a material section formed from metal foam, the material layer by an applied over the metal foam as a forming pressure medium form printing from a starting material layer is pressure-formed. 32. Component according to claim 31, characterized in that the material layer an aluminum material. 33. Component according to claim 31 or 32, characterized in that the metal foam consists of an aluminum alloy. 34. Component according to at least one of claims 31 to 33, characterized net that the material layer and the material section formed from the metal foam are bonded together. 35. Component according to at least one of claims 31 to 34, characterized net that the material layer from a tubular or plate-shaped Semi-finished or starting material is formed.