EP2707158B1 - Method for producing composite parts by means of a combination of deep drawing and impact extrusion - Google Patents

Description

The invention relates to methods for the production of composite parts by a combination of deep drawing and extrusion according to the preamble of claim 1 (see, for example DE 10 2009 032435 A1 ). The production of composite parts is becoming increasingly important due to the need to optimize the use of materials for the production of mass parts or even highly stressed components. On the one hand, high-quality materials are becoming more and more expensive or less available in production, on the other hand, there is a need to design components that are more load-resistant, also with regard to the materials used. It often happens that certain material properties of the materials used are required only in certain areas of the components, whereas other or not so high material properties are sufficient in other areas. It has long been customary for hardened components, for example, to undertake metallurgical processes in a targeted manner to cure materials only in, for example, abrasive areas and not to harden other areas. Similarly, for example, in the coating of components in which, for example, chemically stressed components are specifically provided only in the material properties affecting areas with a protective coating.

Such inhomogeneous over the component different material properties are increasingly required for metallic components that are made of solid blanks or sheets. So it is for example from the publication " Pressure Welding of Corrosion Resistant Metals by Cold Extrusion "from Journal of Materials Processing Technology 45 (1994), pages 275-280 known to produce bimetallic tubular, cup-shaped or solid components by cold mass forming. For this purpose, two different preformed solid or tubular blanks are brought into a predetermined position to each other and by forward or Reverse extrusion in a common die reshaped by the action of a punch. Due to the plastic deformation of the materials during extrusion, the two different materials combine with each other and are simultaneously brought into the new shape. However, the forming processes in this extrusion are quite complex and thus the flow processes of the two materials involved, so that only limited statements are possible on the exact distribution of the materials in the manufactured component and thus on the local material properties.

Object of the present invention is therefore to provide a forming process for the production of components with different material properties, with the due to the transformation of a secure warranty of local material properties is possible.

The solution of the object of the invention results in terms of the method of the features of claim 1. Further advantageous embodiments of the invention will become apparent from the dependent claims.

The method concerning the invention is based on a method for producing a composite part formed from core material and wrapping material by means of an extrusion process. Such a generic method is further developed in an inventive manner that in a first process step, the at least part of the procedurally formed composite part outside covering shell material is produced by a deep drawing of a sheet-shaped or tubular blank in which the core material as a stamp insert for deep drawing of Envelope material is used, wherein shell material and core material come into close surface contact with each other, and then the thus preformed intermediate form of the composite part of deep-drawn shell material and partially enclosed core material is subjected to a common extrusion process in which the final shape of the composite part is produced plastically reshaping. In the invention, it is a combination of deep drawing and extrusion molding to a novel process in which a sheet-like shell material is deep-drawn by means of a resting on the sheet-like shell material core material and then backfilled by extrusion. The Core material assumes the function of a conventional deep-drawing die for the deep-drawing of the shell material, wherein the shell material is formed in a flow press, equipped with a punch, a die and a hold-down, for example, to a cup-shaped or cup-shaped body, which at least partially covers the core material on the outside and thus at least in sections determined in particular the surface properties of the composite part. The transfer of the resulting composite part in the desired final contour is then carried out by extrusion of the thus produced intermediate stage of the composite part, for example by upsetting and / or pushing the intermediate stage of the composite part into or through the die. Due to the use of different materials for the sheet-like shell material and the core material, the method described for the production of components in which different requirements are placed on the local component properties. Examples of these requirements are a wear-resistant surface with low mass of the composite part or different thermal conductivities of core material and shell material. The sheet-like design of the shell material and the deep-drawing process achieve very homogeneous and uniform material properties of the formed shell material, since the layer of shell material on the core material remains essentially unchanged in terms of material thickness and material properties relative to the blank of the shell material. This ensures that the layer of the wrapping material which determines at least parts of the outer shape of the composite part has homogeneous properties in itself and this is not disturbed by flow processes during forming. At the same time formed by the deep-drawing machining by extrusion an intimate composite material between shell material and core material by a material and / or positive connection, possibly also a frictional connection, by a separation of shell material and core material of the later composite part is reliably prevented. This allows the material properties of shell material and core material on the later composite part set very specific and ensure that the combination properties of the composite part meet the requirements.
In a first advantageous embodiment, it is conceivable that the composite part is formed from at least one core material and at least one shell material.

Here, the material properties of the core material and shell material can be selected according to the subsequent requirements of the composite steel and combined with each other, which of course is also conceivable, for example, the shell material multilayer design and about a wear-free surface on the later outside of the composite part by a correspondingly wear-free layer ensure, whereas on the inside of the wrapping material facing the core material, a layer is provided, which connects particularly well with the core material. Likewise, the core material itself can consist of several layers or sections or else of an inhomogeneous distribution of different materials which have different material properties. Thus, for example, it would be conceivable to pre-bond a high-strength steel material with a high-strength steel material to a core material, which is then bonded to the shell material in the manner described.

Of particular importance here is that core material and shell material may at least partially have different properties. Thus, for example, the covering material can be formed particularly resistant to abrasion, for example of a steel material, whereas the core material is lightweight, for example, made of a light metal. In this way it can be ensured that the overall properties of the composite part have a high abrasion resistance in the outer region with a particularly low density and thus low weight in the core material. It goes without saying that very different combinations of different properties of core material and shell material are conceivable, depending on the intended use of the composite part and the available properties of core material and shell material.

Of particular importance is that the core material and / or the blank of the shell material may consist of a plastically deformable material, preferably a metallic material or a plastic. Of particular importance here is in particular the plastic deformation of the material of core material and shell material, since in this way the intimate composite material can be produced after extrusion. A focus of application of the method of the invention is certainly the use of metallic materials for shell material and core material, but it is also conceivable, for example plastically deformable plastics for wrapping material and / or core material. Also, other plastically deformable materials for use in the inventive method are conceivable.

In a further embodiment, it is advantageous if the sheet-like blank of the wrapping material is held during the deep-drawing process between a die and a preferably segmented hold-down. In this case, the deformation of the sheet-like blank by deep drawing is not significantly different from the known thermoforming sheet-like materials, which can be exercised by the example segmented hold down a targeted locally acting stress on the sheet-like blank of the shell material during deep drawing and thus a certain control of the flow of the sheet-shaped blank of the shell material is achieved.

Furthermore, it is conceivable that the core material and the sheet-like blank of the wrapping material are positioned relative to each other and to the die, that the core material presses the sheet-like blank of the wrapping material into the die and deep-draws the sheet-like blank to form a suitable deep-drawing gap. From this positioning of core material and sheet-like blank of the shell material to each other and to the die, the formation of the deep-drawing gap depends primarily and thus the formation of the material flow of the sheet-like blank during deep drawing. This can be achieved, for example, by a corresponding positioning aid or by handling devices which position the core material relative to the die.

Various embodiments of the extrusion molding process are conceivable for carrying out the extrusion molding, wherein the preformed intermediate form of the composite material of core material and deep-drawn shell material between the die, an upper punch pressing on the core material and an anvil in at least one forming process by backward extrusion and / or by forward extrusion and / or plastically deformed by transverse extrusion molding and / or by hollow extrusion molding (everting) to the desired final shape. Depending on the shape of the composite part to be produced and the starting shape of the core material, it is possible to use a single one of the abovementioned extrusion molding processes or else a combination of two or more such extrusion molding processes come, it is also conceivable to carry out the extrusion in several stages in succession.

For the secure connection of core material and shell material of the composite part, it is particularly advantageous if in or on the thermoformed shell material and / or the core material form elements or shapes, preferably undercuts, folds and / or openings or the like. Provided or generated during deep drawing of the shell material become, at which core material and shell material connect form-fitting with each other. In addition to the pure frictional connection of shell material and core material due to extrusion and due to different material elasticities of the composite material by a composite due to acting surface pressures and diffusion processes, by undercuts or Werkstückumfließungen (for which, for example, the shell material is to be provided with appropriate breakthroughs) to match the appropriate requirements be set. Thus, for example, the core material deformed during extruding flows into depressions, windows or similar openings of the wrapping material and thereby interlocks with the wrapping material in a form-fitting manner in addition to frictional engagement, if appropriate depressions, windows or similar openings are introduced in advance in the wrapping material or also produced in the thermoforming process become.

In a first advantageous embodiment, it is conceivable that a solid material section is used as the core material. Such a solid material portion, such as a cylindrically shaped aluminum solid material is combined, for example, with a sheet-like steel material as a shell material, in which the solid material forms the stamp for deep-drawing deformation of the shell material as a core material and by an upper punch the blank of the shell material into the die suppressed. In this thermoforming forming the massive core material will deform little to no, and thus be at least partially surrounded on the outside of the shell material. Due to their material properties, such as, for example, their elasticity and their surface properties, the covering material and this section of the core material will form a bond, which is then further solidified in the subsequent extrusion molding process. In this case, in a further embodiment after completion of the deep-drawing process, the resulting intermediate form the composite part are further deformed by extrusion at least in sections, wherein both a transformation of the core material and a simultaneous deformation of core material and shell material by the extrusion can be done depending on the type of extrusion process used. For example, it is conceivable to reform the core material only in the area not surrounded by the shell material, for example by backward extrusion, whereas forward extrusion of core material and shell material may reshape the entire intermediate form of the composite part together once again. Depending on this, the bond between shell material and core material will further solidify or change.

It is of particular importance for the extruding that the deep-drawn shell material can invest in the desired final shape non-positively and / or positively to the block-shaped core material in the extrusion. This alone makes it possible to achieve a secure bond between shell material and core material, which also ensures the hull material for a secure connection of shell material and core material without subsequent extrusion press processing.

For the implementation of both the deep drawing and extrusion molding, it is advantageous if the core material and the sheet-like blank of the shell material are at least partially covered with a coating of a lubricant. Both deep drawing and extrusion require lubrication of the materials to be processed. Conventionally, the workpieces are coated for this purpose in immersion baths over impregnated rollers or by spraying with a lubricant. In the process according to the invention, the blank of the shell material is only one-sided and the core material only partially coated with lubricant for the adjustment of the contact composite.

In another embodiment, it is also conceivable that the core material and the sheet-like blank of the shell material are covered with an adhesion-increasing coating, at least in the area of direct contact. Coatings of shell material and core material can be used to increase the bond (eg combination of aluminized steel sheet and aluminum core), which achieves particularly good adhesion of the shell material to the core material becomes. It would also be conceivable, for example, alternatively or in addition to an adhesion-increasing coating to perform an insulating or otherwise separating coating between shell material and core material, for example to influence a heat transfer or electrical contact between shell material and core material.

For the automatic production of corresponding composite parts, it is advantageous if the sheet-like blank of the shell material is supplied in a strip or occasionally the forming process. To integrate the deep-drawing process in the extrusion process (both methods are largely automated in industrial use) is a provision of the blank of the shell material in the form of platinum stacks or pre-cut (by shear cutting or laser cutting) tapes provided in which the blank on the section in function of Carrier tape remains. If the blank of the wrapping material is in the form of blanks or blanks, the blank of the wrapping material can be fed to the process periodically via guides, stops and slides. If the blank of the wrapping material provided in the form of ribbons, the trimmed sheet metal strip can be periodically pulled through between the die and downholder and separated by deep drawing. In order to remove burrs remaining on the blank, additional brushes or rotating grinding tools can be integrated here. For controlling the sheet feeder, a segmented hold-down can be used. The ejection of the finished composite part takes place as in conventional extrusion by means of an ejector. This can be used during the deep drawing operation as a counter punch, which prevents bulging of the shell material in the region of the bottom of the composite part.

In another advantageous embodiment, it is also conceivable that an accumulation of individual material elements, preferably of metallic chips or the like. Material elements is used as the core material. As a result, the production of massive composite parts from eg chips and sheets is possible. The sheet-like shell material is the outer shell of the new composite part, the highly compacted chips form the core material or the filling. Shell material and core material from eg pressed chips can consist of the same or different materials, the shell material determines the surface properties of the composite part. During the forming process, the core material of self-compacting chips serves as a deep-drawing die. The advantages of the composite parts produced by this method are in particular the combination of different materials. Thus, when using a steel sheet as the shell material and the use of chips of aluminum as the core material, a lightweight component having a solid surface can be produced. Such a composite part thus closes the gap between light but less strong aluminum parts and steel components. As an alternative to chips made of aluminum, copper shavings can also be introduced in order, for example, to increase the thermal conductivity. A mixture of aluminum and copper shavings is just as possible as a combination of other materials. A filling with non-metallic materials or a combination of metal shavings and non-metallic filler material is also conceivable with regard to an improvement of lightweight components. By means of this embodiment of the method according to the invention, it is possible to produce a new solid component from sheet-like casing material and chips as core material. The ecological aspect is to be emphasized above all when using swarf waste. Alternative processes such as the melting down of the aluminum shavings to produce new solid parts are associated with high (energy) expenditure. In terms of resource and energy-saving production, this process offers new opportunities for environmentally friendly production. In combination with thread rolling can be as in principle for the use of solid but lightweight core materials according to the invention, for example, lightweight screws produce that have a higher strength than aluminum screws, but a lower weight than steel screws. Compared to conventional titanium screws, an enormous cost saving is possible. Other possible composite parts which are mentioned by way of example only are, for example, pistons and shafts of all kinds, bolts, connecting elements for composite material (eg welded connection aluminum / steel) or else multifunctional components (eg mechanical and thermal function). The accumulation of individual material elements can have structured material elements such as chips of very different characteristics (eg, turnings, milling chips, drill chips, etc.) and / or rather shapeless material elements such as grains or the like. It is important in this case above all that these material elements are able to establish a mechanical connection to one another when the core material formed in this way is compressed.

A particularly advantageous embodiment can be achieved in that the accumulation of individual material elements is formed inhomogeneous, preferably having material elements of different properties. In this way, by using different material elements in the matrix of the core material, it is possible to create zones of identical or differing properties in a targeted manner, e.g. be matched to component loads and their attack zones. Thus, for example, in an area where the composite part is to have a high heat conduction, material elements made of copper are reinforced, whereas aluminum elements are provided in areas that are not so thermally relevant. In particular, the accumulation of individual material elements may form a lamination of individual material elements of different properties, preferably layered along the longitudinal axis of the core material. Such stratification is technically easy to implement and often sufficient to adapt the material properties of the core material to the stresses of the composite part.

It is particularly advantageous if the accumulation of individual material elements in the forming is enclosed by a hollow mold into which a punch pressing on the material elements dips in and which pre-compacts the accumulation of individual material elements on the sheet-like blank of the wrapping material. Such formation of the accumulation of individual material elements before forming can be effected, for example, by a ring which can simultaneously be used as a hold-down for deep-drawing the wrapping material and whose opening is e.g. filled with chips completely or partially. If now an auxiliary punch which fits into the opening of the mold is placed on this pile and the accumulation is compressed with the upper punch, the accumulation is precompressed and reduces its volume, the material elements such as e.g. the chips are connected together at the same time, e.g. weld or stick together locally or get caught.

In a further embodiment, the accumulation of individual material elements is precompressed by the upper punch until the sheet-like blank of the shell material has also largely deformed by deep drawing. The pressure on the blank of the wrapping material by the densifying as described above Accumulation of the material elements will lead to a thermoforming of the blank from reaching the necessary stresses in the blank, so that then the precompression of the accumulation of individual material elements and the deep drawing process will occur in parallel, the pre-compressed accumulation of individual material elements used as a stamp insert for the deep drawing of the shell material The pre-compaction then comes to an end with the completion of the deep-drawing process.

Subsequently, in a further refinement, after the completion of the deep-drawing process, the resulting intermediate shape of the composite part is further deformed at least in sections by extrusion. In this case, the final degree of compaction of the material elements compacted to the core material will depend on the degree of deformation during extrusion, so that after the pre-compression before and during deep drawing can achieve a further compression and thus improve the adhesion of the material elements to each other.

It is particularly advantageous if metal chips, preferably untreated or pretreated chips from cutting processes or already precompressed chip chips, are used as the accumulation of individual material elements. It is of course also possible to use other metallic or non-metallic material elements that are structured or not structured. Also mixtures of such material elements and material elements made of different materials are conceivable. Of importance is that the accumulation of individual material elements is compressed until the material elements form a permanently solid composite, in particular the material elements are welded or glued together. Depending on the material pairing, the composite of materials between chips and sheet metal, in addition to deformations of casing material and material elements, also occurs due to composite material due to micro-welding or diffusion processes due to the high local pressures during forming. Tests for composite extrusion of aluminum turnings in a steel bowl have shown that the filling of the composite is very good, the chips have joined into a single piece and do not come out by themselves.

Furthermore, it is conceivable that the compacted accumulation of individual material elements has a specifiable porosity or density. Thus, by the size and shape of the material elements prior to deformation, the packing density of the accumulation of individual material elements can be selectively controlled, whereby the porosity or density of the core material of the composite part is determined depending on the resulting degree of compaction.

In another embodiment, it is also conceivable that the porosity or density of the material elements compacted to the core material is changed by subsequent pore formation, preferably by foaming a pressed foam-forming material or melting meltable material elements. Thus, during or after the compaction of the core material, a further process step can follow, in which the compacted core material is foamed chemically or physically or certain with incorporated constituents are removed, for example, thermally or chemically. This allows a subsequent change in the porosity or density of the composite part, wherein in a further embodiment, the porosity or density of the material elements compacted to the core material can be influenced by the shaping and / or densification and / or mixing of the material elements, e.g. through the targeted addition of lightweight supplements. Also, the properties of the material elements compressed to the core material may be affected by materials of other properties, preferably other conductivity, specific gravity, damping or the like.

In a further embodiment, it is conceivable that functional components, preferably threaded components, wires, sensors or the like, are embedded in the material elements to be compacted for the core material, which form a close bond with the compacted material elements during compaction. The material elements such as the chips can adapt to the contour of the receiving container and also enclose internal geometries. It is thus possible to press in further components or materials (eg a copper core for heat dissipation). The functional component to be pressed in is thereby positioned, for example, on the blank of the wrapping material before the filling of the hollow part with the material elements. Pressing in insulated cables and / or sensors (eg in a steel capsule) is included This method is also possible. Furthermore, it is conceivable to press wire loops and then use them as integrated strain gauges to record component loads of the composite part. When using a perforated plate and corresponding ejector additional functional elements such as a hexagon screw (possibly with washer) to produce a composite part with thread can be introduced in one step. Similarly, the introduction of an internal thread when using a nut is possible, a laid on the mother Steel sheet prevents the penetration of chips.

Furthermore, it is conceivable that the material elements to be compacted to the core material are enclosed by cylindrically shaped hollow sheet metal blanks and / or cover-like blanks which are arranged and deformed between the accumulation of individual material elements and the surrounding hollow shape or on the upper punch side end of the core material. For large diameter of the sheet metal blank of the blank of the shell material known during deep drawing problems such as wrinkles and tears can occur. This can be counteracted by a rolled to an (overlapping) tube and coated outside sheet metal blank (alternatively: a piece of pipe) is placed on the blank of the shell material. This is followed by filling with chips and the usual forming process. In this variant, an adaptation of the stamp is required. In addition, after forward full extrusion and removal of the punch, a lid with corresponding radii can be positioned above the die. If the ejector moves upwards, the composite part produced is pressed against the cover and the sheet edges are bent inwards. The sheet thus completely encloses the core material. After removing the cover, the composite part can be ejected as usual.

A particularly preferred embodiment of the method according to the invention is shown in the drawing.

Figur 1

- eine erste Ausgestaltung des erfindungsgemäßen Verfahrens mit einem massiven Kernmaterial und einem blechförmigen Hüllmaterial als Stadienplan beim Tiefziehen eines stirnseitigen Napfes aus einem blechförmigen Rohling des Hüllmaterials und anschließendem Rückwärts-Fließpressen,

Figur 2

- ein Stadium einer Variante des Verfahrens gemäß Figur 1 mit einem Tiefziehen eines stirnseitigen Napfes und anschließendem Voll-Vorwärts-Fließpressen,

Figur 3

- eine Variante des Verfahrens gemäß Figur 1 mit einem Tiefziehen aus einem rohrförmigen Rohling des Hüllmaterials und anschließendem Vorwärts-Fließpressen in Form eines Stadienplans,

Figur 4

- eine weitere Ausgestaltung des erfindungsgemäßen Verfahrens mit einem aus einzelnen Materialelementen gehäuften Kernmaterial und einem blechförmigen Hüllmaterial als Stadienplan beim Tiefziehen eines stirnseitigen Napfes aus einem blechförmigen Rohling des Hüllmaterials und anschließendem Vorwärts-Fließpressen,

Figur 5

- eine Variante des Verfahrens gemäß Figur 4 mit einem Tiefziehen aus einem rohrförmigen und einem blechförmigen Rohling des Hüllmaterials und anschließendem Vorwärts-Fließpressen sowie rückseitigem Umbiegen in Form eines Stadienplans,

Figur 6

- eine Variante des Verfahrens gemäß Figur 4 mit Einlagern eines Einlageteils in die Anhäufung aus einzelnen Materialelementen,

Figur 7

- eine Variante des Verfahrens gemäß Figur 4 mit Einlagern eines Meßdrahtes in die Anhäufung aus einzelnen Materialelementen,

Figur 8

- eine Variante des Verfahrens gemäß Figur 4 mit Einlagern einer durch eine Öffnung in dem blechförmigen Hüllmaterial vorstehenden Schraube in die Anhäufung aus einzelnen Materialelementen,

Figur 9

- eine Variante des Verfahrens gemäß Figur 5 mit einem Tiefziehen aus mehreren scheibenförmigen Rohlingen des Hüllmaterials und gleichzeitigem Quer-Fließpressen,

Figur 10

- verschiedene Varianten der Formgebung des blechförmigen Hüllmaterials zur Bildung unterschiedliche geformter Verbundteile,

Figur 11

- eine Variante des Verfahrens gemäß Figur 4 mit Ausbildung einer seitlich hervorstehenden Lasche,

Figur 12

- eine Variante des Verfahrens gemäß Figur 4 mit Ausbildung eines umlaufenden Flansches.

Show it:

FIG. 1

- A first embodiment of the method according to the invention with a solid core material and a sheet-like shell material as a stage plan during deep drawing a frontal cup from a sheet-shaped blank of the wrapping material and subsequent backward extrusion,

FIG. 2

a stage of a variant of the method according to FIG. 1 with a deep-drawing of a front-side bowl and subsequent full-forward extrusion,

FIG. 3

- A variant of the method according to FIG. 1 with a deep drawing from a tubular blank of the wrapping material and subsequent forward extrusion in the form of a staged plan,

FIG. 4

a further embodiment of the method according to the invention with a core material heaped from individual material elements and a sheet-like shell material as a stage plan during deep-drawing of an end cup from a sheet-like blank of the shell material and subsequent forward extrusion;

FIG. 5

- A variant of the method according to FIG. 4 with a deep-drawing of a tubular and a sheet-like blank of the wrapping material and subsequent forward extrusion and back bending in the form of a staged plan,

FIG. 6

- A variant of the method according to FIG. 4 incorporating an insert into the aggregate of individual material elements,

FIG. 7

- A variant of the method according to FIG. 4 with insertion of a measuring wire into the aggregate of individual material elements,

FIG. 8

- A variant of the method according to FIG. 4 incorporating a screw projecting through an opening in the sheet-like wrapping material into the aggregate of individual material elements,

FIG. 9

- A variant of the method according to FIG. 5 with deep-drawing from several disc-shaped blanks of the wrapping material and simultaneous transverse extruding,

FIG. 10

various variants of the shaping of the sheet-like casing material to form different shaped composite parts,

FIG. 11

- A variant of the method according to FIG. 4 with the formation of a laterally protruding tab,

FIG. 12

- A variant of the method according to FIG. 4 with the formation of a circumferential flange.

In the FIG. 1 is a schematic representation of a first embodiment of the method according to the invention with a solid core material 3 and a sheet-like blank 1 of the shell material 2 as a stage plan during deep drawing of an end cup of a sheet-like blank 1 of the shell material 2 and subsequent backward extrusion shown. In this case, the device for carrying out the method is constructed in basically known manner, so that only the procedural features of the device should be mentioned here. The deep drawing of the blank 1 is effected by an upper punch 7, below which the solid core material 3 is arranged and initially rests on the blank 1. The blank 1 of the wrapping material 2 is held or clamped and guided between the upper side of a die 4 provided with a drawing opening 6 and a hold-down 5, wherein the hold-down 5 can be configured as a segmented hold-down 5 and one in the plane of the blank 1 can exert locally controlled pressure on the blank 1. Below and within the drawing opening 6, an ejector 8 can be seen, which forms an abutment in forming the composite part 18 to be produced and ejects the finished composite part 18 back up from the drawing opening 6.

In the upper left part of the figure FIG. 1 is the starting position before the start of the drawing operation of the sheet-shaped blank 1 of the enveloping material 2 to recognize, ie the solid core material 3 is without pressure on the blank 1 on. If the upper punch 7 and thus the solid core material 3 acting here as a stamp are pressed vertically from above into the die 4, the blank 1 is gradually pressed further and further into the drawing opening 6 of the die 4 and forms a bowl with a level bottom portion and an annular side wall. Due to the dimensions of core material 3 and shell material 2, which are in diameter in differ about twice the sheet thickness of the blank 1 (at a slightly lower drawing gap results in an ironing), the core material 3 will move exactly centered in the drawing opening 6 and as described the cup-shaped deformation of the shell material 2 result. The sheath material 2 is thereby deformed so that the side wall of the cup of the enveloping material 2 presses against the frontal surface of the core material 3 and rests tightly against this surface of the core material 3. This stage is in the lower left part of the figure FIG. 1 shown.

Following this drawing process, the composite of Kenmaterial 3 and wrapping material 2 thus produced is then further deformed by a backward extrusion. For this purpose, the bottom portion of the cup-shaped deformed envelope material 2 rests on the ejector 8 and can not be pushed further into the pull opening 6. If the upper punch 7 still continues to move downwards, the core material 3 pressurized by the upper punch 7 will swerve outwards and upwards, the core material 3 will virtually flow upwards past the upper punch 7, and an upper-side depression will be formed in the core material 3. In the area of the cup-shaped wrapping material 2, the core material 3 will likewise expand radially and thus further strengthen the bond with the wrapping material 2. Thus, the composite part 18 is finished and can be ejected after retraction of the upper punch 7 of the ejector 8 upwards.

In this case, the covering material 2 arranged locally around the lower end of the core material 3 around the core material 3 determines the surface properties of the composite part 18 in this area. For example, the covering material may be made of a hard and abrasion-resistant material, such as e.g. Steel are formed, whereas the core material consists of a lightweight aluminum. Thus, a lightweight composite part with locally high abrasion resistance can be generated.

In the FIG. 2 is only one stage of a variant of the method according to FIG. 1 shown with a deep-drawing of a front-side cup and subsequent full-forward extrusion. In this case, during deep drawing from a larger blank 1, a deeper cup or better already a kind of unilaterally closed sleeve deep-drawn, which is pressed completely through the opposite of the drawing opening 6 constricted extrusion opening 22 in the subsequent extrusion. In this case, the composite part 18 is once again reduced in diameter and stretched.

In the FIG. 3 is a variant of the method according to FIG. 1 with a thermoforming of a tubular blank 1 of the wrapping material 2 and subsequent forward extrusion in the form of a staged plan. This is instead of a flat sheet-metal blank as in FIG. 1 a tubular shell material 2 is pushed onto the core material 3 and in a manner not shown analogous to the procedure according to FIG. 1 deep-drawn and then extruded. The region of the resulting casing material 2 is arranged tapering down on a part of the outer circumference of the core material 3 of the composite part 18. In the FIG. 4 is another embodiment of the method according to the invention with a heaped from individual material elements not shown in more detail core material 3 and a sheet-like blank 1 of the shell material 2 as a stage plan during deep drawing a front cup from the sheet-like blank 1 of the shell material 2 and subsequent forward extrusion shown. The accumulation of the material elements can be formed, for example, from a heap of metal shavings, which are first filled loosely in a simultaneously taking over the function of the blank holder 5 hollow part 9 from above onto the blank 1. The material elements can be varied in many ways in the manner already described above in terms of shape, material, distribution and formation of the heap.

Above the core material 3 forming accumulation of the material elements, an auxiliary plunger 10 is placed and pressed into the opening of the hollow part 9, presses on the top of the upper punch 7 again. If now the upper punch 7 is pressed down as already described, the accumulation of the material elements forming the core material 3 is precompressed and thus the volume of such core material 3 is reduced significantly. Due to the compression of the core material 3 forming accumulation of the material elements, the deep-drawing limit of the blank 1 of the enveloping material 2 is exceeded from a certain degree of compaction by the pressure and the blank 1 of the enveloping material 2 begins as before figure 1 described to deform to a kind of bowl. This stage is in the third part of the FIG. 4 shown. Here, the core material 3 forming accumulation of the material elements is not only compressed, but it comes on the one hand to local welds, entanglements and other fasteners between the individual material elements and on the other hand, the material elements are pressed into the cup-shaped shell material 2 in and also set this. It thus forms a solid composite material between deformed shell material 2 and core material. 3

If the wrapping material 2 has been completely deformed in the intended manner, the upper punch 7 is moved upwards and the auxiliary punch and the hollow part 9 are removed. Subsequently, the upper punch moves down again and presses the composite of core material 3 and shell material 2 against the constriction of the extrusion opening and deforms this composite further by forward extrusion. In this case, core material 3 and shell material 2 are at least partially or even completely reformed (during full-forward extrusion) and with each other, whereby the composite between core material 3 and shell material 2 further promoted and the core material 3 is further compressed.

In the FIG. 5 is a variant of the method according to FIG. 4 with a thermoforming of a tubular and a sheet-like blank 1 of the wrapping material and subsequent forward extrusion and back bending in the form of a staged plan. The wrapping material 2 here consists of a tubular part 11 and a flat part 1, which are arranged adjacent to each other in the hollow part 9 and between the die 4 and hollow part 9. In this form is already in too FIG. 4 described manner, the accumulation of the material elements of the core material 3 filled and pressed again by means of auxiliary plunger 10 and upper punch 7 in the die 4. This forms as in the middle part of the figure FIG. 5 to recognize a kind of double-layered arrangement of the two envelope materials 2, 11, which surround the compressed core material 3 on the underside and radially along a certain length. By using the tubular wrapping material 11 larger sheathing over the simple deep drawing can be achieved. After the forward extrusion, in which the two-ply arrangement of the enveloping material 2 largely pressed into a single layer, the stage is reached, that in the fourth Partial figure can be seen from the left. In this case, a kind of collar of the formerly tubular wrapping material projects upwards beyond the core material 3 and can be used to largely enclose the core material 3. For this purpose, a cover 12 is placed over the upper punch-side opening of the drawing die 4 and pressed from below with an ejector the largely finished composite part 18 up against the lid part 12. As a result, the collar of the wrapping material 2 projecting upwards over the core material 3 bears against the inside of the cover part 12 and is pressed inwards, the core material completely or partially overlapping. The resulting composite part is thus largely completely enclosed by the enveloping material 2.

In the FIG. 6 is a variant of the method according to FIG. 4 to recognize with storage of an insert part in the accumulation of individual material elements. Here, for example, for reasons of improved heat conduction or the like. An additional insert part 14, for example, made of a highly thermally conductive copper material in the formed from an accumulation of material elements core material 3 is introduced by fitting it to the flat blank 1 of the shell material 2 and then, for example, from chips formed material elements are filled into the hollow part 9. The material elements of the core material completely surround the insert part 14 except for the end face resting on the blank 1. During the subsequent deep drawing and extruding, not only the already described close bond between core material 3 and shell material 2 will form, but also the insert part is firmly surrounded and fixed by the material elements of the core material 3.

The same idea as to FIG. 6 can also be described in a further variant of the method according to FIG. 4 be used for storing a measuring wire in the accumulation of individual material elements, wherein instead of the insert part as in FIG. 6 a measuring wire 15 such as a measuring wire to be used as a strain gauge to be inserted into the core material and is deformed with. If this measuring wire is insulated from the core material 3, the mechanical stress in the form of strains or changes in shape of the composite part 18 can be detected on the finished composite part, for example via the resistance change of the measuring wire 15.

Like in the FIG. 8 can also recognize a mechanical part such as a screw 16 in a variant of the method according to FIG. 4 by inserting a projecting through an opening 21 in the sheet-like shell material 2 above screw 16 in the accumulation of individual material elements. The screw is inserted with the threaded portion through a previously introduced opening 21 in the blank 1 of the enveloping material 2 and protrudes from the underside of the blank 1 out. Subsequently, the accumulation of individual material elements of the core material 3 is filled and compacted in the manner already described. After the extrusion, the threaded portion protrudes from the front side of the opening 21 of the shell material 2 of the composite part 18 and is safe and rotatably surrounded by the core material.

In the FIG. 9 is in a very schematic way a variant of the method according to FIG. 1 to recognize with a deep drawing of disc / platinum-shaped blanks of the shell material and simultaneous transverse extrusion, the main flow direction of the composite of core material 3 and shell material 2 extends transversely to the compression direction of the upper punch 7 and thereby radially outwardly projecting protuberances 17 are generated.

In addition to the use of simple flat blanks 1 of the wrapping material, it is also conceivable to use preformed blanks 1, as these in the FIG. 10 are shown for various variants of the shaping of the sheet-like shell material 2 to form differently shaped composite parts 18. Thus, for example, perforated, cross-shaped or segmentally trimmed blanks 1 can be used, which transform due to the deformation during deep drawing and extrusion in correspondingly complex shaped, three-dimensional composite parts and surround the core material 3.

This idea can also be used to form, for example, tab-shaped form elements 19 from the wrapping material 2, as these as a variant of the method according to FIG. 4 for the formation of a laterally protruding tab in the FIG. 11 can be seen. The per se round blank 1 is slotted for this, so that a tab 19 is formed. This tab 19 can now be bent out after the reshaping of the composite part 18 already described.

A similar variant of the method according to FIG. 4 can also be used for the formation of a circumferential flange, as in FIG. 12 roughly indicated. Here, as the method according to the FIG. 4 in the third forming stage, a region of the enveloping material 2 deforms outwardly like a flange 20, surrounding the core material 3 so as to protrude radially outwards.

Part number list

1

- blank wrapping material

2

- sheet-shaped wrapping material

3

- nuclear material

4

- Matrix

5

- Stripper plate

6

- Pull-through opening die

7

- Upper stamp

8th

- ejector

9

- hollow part

10

- auxiliary stamp

11

- tubular wrapping material

12

- Lid

13

- bend

14

- Deposit part

15

- Measuring wire

16

- screw

17

- protuberance

18

- composite part

19

- tab

20

- flange

21

- hole

22

- Extrusion opening

Claims (18)

1. Method for producing a composite part (18) made of core material (3) and shell material (2) by means of an impact extrusion process,
   characterized in that
   in a first process step, the covering material (2) covering at least a part of the outside surface of the composite part (18) which is produced according to the method is produced by a deep-drawing process from a sheet-like or tubular blank (1), in which the core material (3) is used as insert die for the deep-drawing process of the covering material (2), wherein covering material (2) and core material (3) come in close contact to each other at their surfaces, and afterwards the intermediate form of the composite part (18) produced respectively made from deep-drawn covering material (2) and partially covered core material (3) is subjected to a common impact extrusion process, in which the final shape of the composite part (18) is produced by plastic deformation.
2. The method as claimed in claim 1, characterized in that the composite part (18) is formed from at least one core material (3) and at least one covering material (2), the core material (3) and the covering material (2) preferably having at least partly different properties respectively.
3. The method as claimed in one of the claims 1 or 2, characterized in that the core material (3) has a, preferably nonhomogeneous distribution of different materials and/or the blank (1) of the covering material (2) has a layer-like distribution of different materials layers and/or the core material (3) and/or the blank (1) of the covering material (2) consists of a plastically deformable material, preferably a metallic material or a plastic.
4. The method according to one of the claims 1 to 3, characterized in that the sheet-like blank (1) of the covering material (2) is held during the deep-drawing process between a die (4) and a preferably segmented blank holder (5) and the core material (3) and the sheet-like blank (1) of the covering material (2) are preferably positioned relative to each other and to the die (4), so that the core material (4), forming an appropriate clearance deep-draws the sheet metal blank (1) of the covering material (2) into the die (4) and thereby deep-draws the sheet-like blank (1).
5. The method as claimed in one of the preceding claims, characterized in that the preformed intermediate form of the composite part (18) consists of core material (3) and deep-drawn covering material (2) is plastically deformed into the desired final shape between die (4), an upper punch (7) pressing onto the core material (3) and a pressure pad (8) by at least one forming process by backward extrusion and/or by forward extrusion and/or by lateral extrusion.
6. The method as claimed in one of the preceding claims, characterized in that shaping elements or shapings, preferably undercuts, folds and/or openings or the like are provided in or on the deep-drawn covering material (2) and/or the core material (3) on which core material (3) and covering material (2) are joined together in a form-fitting manner.
7. The method as claimed in one of the preceding claims, characterized in that after the completion of the deep-drawing process, the resultant intermediate form of the composite part (18) is further deformed at least in sections by an impact extrusion, and the deep-drawn covering material (2) becomes non-positive and/or interlocking and/or material-locking during extrusion to the block-shaped core material (3).
8. The method as claimed in one of the preceding claims, characterized in that the core material (3) and the sheet-like blank (1) of the covering material (2) are at least partially covered with a coating of a lubricant or are covered at least in the region of direct contact with one another with an adhesion-increasing coating.
9. The method as claimed in one of the preceding claims, characterized in that as core material (3) a solid material section is used.
10. The method as claimed in one of claims 1 to 8, characterized in that an accumulation of individual material elements, preferably metallic shavings or the like, preferably of untreated or pre-treated shavings from cutting processes or already pre-compressed shaving pellets is used.
11. The method as claimed in claim 10, characterized in that the accumulation of individual material elements is inhomogeneous, preferably has material elements of different properties, in particular a layering of individual material elements of different properties, preferably layered along the longitudinal axis of the core material (3).
12. The method as claimed in one of the claims 10 or 11, characterized in that the accumulation of individual material elements is enclosed during the forming by a hollow mold (9) into which an upper die (7) pressing onto the material elements is inserted which precompresses the accumulation of individual material elements (1) of the covering material (2), in particular precompresses for as long as the sheet-like blank (1) of the covering material (2) has also largely deformed by deep-drawing.
13. The method as claimed in claim 12, characterized in that the precompressed accumulation of individual material elements and the blank (1) of the covering material (2) are further deformed together during the deep-drawing of the covering material (2), wherein the precompressed accumulation of individual material elements is further compressed during this deep-drawing, wherein the precompressed accumulation of individual material elements is preferably used as a die insert for the deep-drawing of the covering material (2).
14. The method as claimed in claim 13, characterized in that, after completion of the deep-drawing process, the resultant intermediate form of the composite part (18) is further deformed at least in sections by means of an impact extrusion.
15. The method as claimed in one of the claims 10 to 14, characterized in that the compressed accumulation of individual material elements has a predeterminable porosity or density, in particular by subsequent pore formation, preferably by foaming an injection-molded foam-forming material or melting-out meltable material elements.
16. The method as claimed in claim 15, characterized in that the porosity or density of the material elements compacted to the core material (3) by the forming and/or the compression and/or the mixture of the material elements or the density of the material elements compacted to the core material (3) is influenced by admixture of light-weight additives.
17. The method as claimed in one of the claims 10 to 16, characterized in that the properties of the material elements compacted to the core material (3) are influenced by materials of other properties, preferably different conductivity, other specific weight, other damping or the like, and/or the material elements compacted to the core material (3) include functional elements, preferably threaded parts (16), wires (15), sensors or the like, which form a tight bond with the compacted material elements during the compaction process.
18. The method as claimed in one of the claims 10 to 17, characterized in that the material elements to be compacted to the core material (3) are enclosed by cylindrically constructed hollow sheet metal blanks (11) and/or lid-like sheet metal blanks which are arranged between the accumulation of individual material elements and the surrounding hollow mold (9) or at the end of the core material (3) directed to the upper punch and which are also deformed.

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