Method for producing a component with a cavity

The invention is in the field of mechanical engineering and is concerned with the production of electrically conductive, hollow components. It can be used with particular advantage in the field of electrical engineering. An important

Application is in the production of cooled passive electrical components such as electrical conductors and especially windings. For example, such windings can be used during manufacture

Converter-fed electric motors are used. If hollow conductors can be used in the production of such windings, efficient cooling is possible, which makes it possible to achieve very high current densities. However, the application of the invention is not limited to drives or, for example, generators, but other elements such as choke coils for high-frequency circuits can also be implemented. A special feature when using hollow, electrically conductive components is the possibility of implementing internal cooling for them. However, the production of such components is complex, especially if a small size and / or a small wall cross-section is to be achieved.

From EP 0 091 352 B1 a production method for a straight metallic semiconductor is known in which a substrate is coated with several metal layers and the substrate is dissolved on it, so that the remaining coating forms the waveguide.

A method for producing a light guide is known from EP 0 216 421 A1, in which a substrate is first coated as a core and then removed from the coating. For this purpose, the substrate is stretched in its longitudinal direction and its cross-sectional dimensions are reduced in the transverse direction.

From EP 0 129 453 B1 a method for producing a metallic waveguide is known, in which a core is first coated with a brass layer and then with a silver and a copper layer, whereupon the core and the brass layer are dissolved.

The formation of a high-frequency module with waveguides on or in a semiconductor wafer is known from US 2004/0036569 A1.

From DE 35 08 794 C2 the production of an injection molded body in an injection mold is known, the mold being coated and the coating being transferred to the casting.

Against the background of the prior art, the present invention is based on the object of creating a method for producing electrically conductive components with a cavity that allows the production of complex shapes with little effort and expense.

The object is achieved with the features of the invention according to claim 1 by a method for producing an electrically conductive component ge. Claims 2 to 12 present advantageous embodiments of the method.

The invention also relates to a method for producing a releasable substrate for use in a method according to the invention.

The invention thus relates to a method for producing an electrically conductive component with a cavity.

The object is achieved in that a viable, fluid-tight layer of an electrically conductive material, in particular in a layer thickness of more than 3 micrometers, in particular more than 20 micrometers, is applied to a dissolvable substrate in such a way that the substrate is fluid-tight from the Layer is covered and that then the substrate is dissolved and at least partially removed.

By applying the electrically conductive material to a substrate, the thickness and the material structure of the applied layer can be designed within wide limits. Layer thicknesses can be achieved that, for example, cannot be achieved or can only be achieved with great difficulty using conventional metal casting processes. By applying the layer to the surface of a substrate, complex shapes with undercuts can also be achieved using simple application processes. The geometric design of the cavity or cavities in a component formed with such a layer can be designed in a simple manner through the shape of the substrate. The process creates a fluid-tight layer that forms a closed outer wall of the component being created, so that it can be effectively cooled by means of a fluid in its cavity. The use of the cavity in the component is not limited to cooling, but any type of material and heat transport such as heating, temperature compensation or the conduction of the fluid as material transport can be implemented using a fluid provided in the cavity .

It can also be provided that the stable, fluid-tight layer is formed in a layer thickness of less than 20 mm, in particular less than 5 mm.

With the method presented, thin wall thicknesses of the components in particular can be easily achieved.

It can also be provided that the substrate is strand-shaped and that the layer is applied to the surface (s) of the substrate on all sides in such a way that the surface of the substrate is covered in a fluid-tight manner.

In this way, wire-like, hollow components can be produced particularly easily in the process.

The various technologies that can be used to apply layers to substrates can be used to form thin layers in the desired material structures, so that the necessary wall thickness for the component is only limited by the requirements for current-carrying capacity and fluid-tightness, as well as mechanical load-bearing capacity .

The substrate can be formed, for example, as a strand with any cross section and covered on all sides with a fluid-tight layer by the coating process. Before coating, the substrate can already be placed in the geometry of the final coil / helix and then coated. The production of the pre-geometry can take place analogously to a winding process, the pre-geometry then having to be able to be elastically expanded or pulled apart in such a way that the turns do not touch and can be coated. Likewise, a pre-geometry can be produced by forming processes of semi-finished products or a process Similar to FDM (Fused Deposition Molding) in which the substrate material is brought into the shape of the desired coil or an approximate shape through a nozzle and the individual turns are not fused together. In addition, the preform produced in this way can already be pressed from the substrate or reshaped into the desired final contour by subsequent reshaping, which results in high utilization of the available space for the coil when using simple pre-geometries for the substrate. After the substrate has been dissolved, a tubular component is left over. The cross section of the substrate can, for example, be circular or oval or also rectangular, square, triangular or polygonal. If, for example, the component is to be manufactured or further processed in the form of a winding, cross-sections that allow a high winding density are ideal. After its production, the component can be further shaped, for example by bending or winding, either before removing the substrate or after removing the substrate. However, it can also be provided that the substrate is already produced in an intended complex shape, so that the three-dimensional shape of the component used later is already predetermined by the coating of the substrate. for example by bending or winding. However, it can also be provided that the substrate is already produced in an intended complex shape, so that the three-dimensional shape of the component used later is already predetermined by the coating of the substrate. for example by bending or winding. However, it can also be provided that the substrate is already produced in an intended complex shape, so that the three-dimensional shape of the component used later is already predetermined by the coating of the substrate.

In the production of a strand-like component, an endless manufacturing process can also be provided in that a substrate is continuously moved through a coating device and coated there. After passing through the coating device, the coated substrate can run into a further processing station in which the substrate is dissolved. In a subsequent station, for example, the strangför-shaped body, which is then tubular, can be wound.

It can be provided in one embodiment of the invention that the load-bearing layer is applied to the substrate by applying particles. Such particles can be, for example, micro- or nanoparticles or also individual atoms or clusters of atoms or material droplets, which are applied to the surface of the substrate using various methods which are described in more detail below.

In one embodiment of the method it can be provided that the substrate consists at least partially of an electrically conductive material, in particular a metal or an electrically conductive plastic or of an electrically insulating material such as ceramic, glass or plastic filled with conductive particles.

An at least partially electrically conductive design of the substrate enables coating processes such as a galvanic coating process, which can also be carried out without external current.

Other coating processes that require the generation of a current or the application of a voltage to the substrate can also be made possible by the electrically conductive configuration of the substrate.

In one embodiment of the method according to the invention, it can also be provided, for example, that the substrate consists at least partially of an electrically insulating material, in particular a plastic, a wax, a ceramic or a thermoplastic material.

It is therefore possible to choose freely from common, easily processable materials for the design of the substrate.

For this purpose it can be provided, for example, that the substrate is coated with an electrically conductive Vorbeschich processing substance, in particular with a metal, in particular in the form of micro or nanoparticles or a conductive plastic or carbon, in particular in the form of graphite or carbon, before the load-bearing layer is applied Carbon nanotubes is pre-coated.

With such a pre-coating, a conductivity of the surface is established, so that all electrical or electrically assisted coating processes are facilitated or made possible.

However, it can also be provided that the substrate is coated with micro- or nanoparticles, which are not necessarily electrically conductive, before the load-bearing layer is applied. This enables adhesion of the subsequently applied stable layer and / or improved growth of such a layer.

This also facilitates coating processes for the substrate other than electrical or electrically assisted.

A suitable precoating can also have the effect that the separation of the layer produced from the substrate is facilitated in a later step.

It can also be provided that the substrate is chemically etched before the load-bearing layer is applied.

For example, it can be provided for the coating according to the invention that the load-bearing layer is applied to the substrate by a galvanic, in particular electrochemical or external currentless method.

The advantages of the procedure outlined above are as follows:

• Various metals and alloys can be used

• Different metals / alloys possible in layers

• Layer thickness controllable via the process parameters time, temperature, voltage, current, concentration, etc.

• Use of chemically pure metals

• Structure of defect-free / low-defect layers

• Coating of complex structures + homogeneous coating (wall thickness)

Another possible use is that the waveguide that is present after the coating process can easily be reshaped with the substrate that is still present on the inside, without destroying the hollow geometry. This makes it possible to twist / twist several conductors and only then bring the substrate out of the waveguide. This creates a conductor for very high frequencies with low losses due to the skin effect, which enables very high current densities due to the possible internal cooling.

Alternatively, it can also be provided that the load-bearing layer is applied to the substrate using a PVD coating process.

Such PVD processes (Physical Vapor Deposition process) can include, for example, the following processes: thermal evaporation of substances with subsequent precipitation, electron beam evaporation, laser beam evaporation, arc evaporation, molecular beam epitaxy. There is also a coating method known as sputtering, in which the starting material is atomized by ion bombardment and converted into the gas phase. In addition, ion beam-assisted deposition, ion plating and the ICBD process (ionized cluster beam deposition process) can also be used.

Basically, it should be noted that several layers can also be applied one after the other, which later form the wall of the hollow component to be produced. For example, it is conceivable that a first layer ensures electrical conductivity and mechanical stability, while a layer applied to this ensures fluid tightness, or vice versa.

In principle, provision can also be made for the stable layer to be applied to the substrate using a CVD coating process.

The CVD processes (Chemical Vapor Deposition process) are chemical vapor deposition processes in which substances from the gas phase are deposited on the substrate and there with the surface or the materials on the surface, for example pre-coatings chemically to form a layer react.

To produce special shapes of the components produced, it can be provided, for example, that the load-bearing layer is applied to the substrate in such a way that it surrounds the substrate in a fluid-tight manner on all sides.

The fluid tightness on all sides can be understood to mean that the substrate is actually completely closed off and sealed by the coating. However, it can also be provided, in particular in the case of strand-like substrates, that the outer surfaces of the substrate are completely sealed in a fluid-tight manner, while at least one or more end faces of the substrate remain uncoated. However, it can also be provided that the substrate is first coated in a fluid-tight manner on all sides and that parts of the coating are then removed in a subsequent processing step in order to first produce the cavity in the component produced by removing the substrate and later by filling in a fluid to be able to use.

Furthermore, as a coating method, it can be provided that the load-bearing layer is applied to the substrate by a plasma spraying method or by immersing the substrate in a molten metal.

In principle it can be provided that the substrate is deformed before the application of the load-bearing conductive layer or that the substrate is deformed together with the layer after application of the load-bearing conductive layer. This can be useful in particular when the substrate has the shape of a helix or a spiral.

For example, it can be provided that a helical or spiral-shaped substrate is produced and this is pulled apart in the longitudinal direction of the helix / spiral before the coating is applied from an electrically conductive material and then provided with the coating of an electrically conductive material, in particular in the extracted form becomes. In addition, in the extracted state, an electrically insulating coating can be applied to the conductive coating, for example made of a lacquer or plastic or a metal oxide. Thereafter, the substrate can be compressed with the coating in the longitudinal direction, or, if the extraction has taken place at least partially elastic and the substrate is elastic, a transition into a shape that is at least partially contracted in the longitudinal direction of the helix can also take place through relaxation of the substrate. Such a procedure can be useful, for example, if the distance between individual turns of the substrate in the de-energized state is small, for example smaller than 2 mm or smaller than 1 mm.

Electrical contacting of neighboring windings can thus be prevented.

In one implementation of the method it can be provided, for example, that after the application of the load-bearing layer, the substrate is deformed, in particular bent, together with it, and that the substrate is then at least partially removed. Before the deformation, the stable electrically conductive layer can also be provided with an electrically insulating cover layer, for example by dipping, spraying, brushing, spraying or powder coating or by applying a reaction layer, in particular an oxide layer, for example by chemical treatment with a reactant.

Due to the deformation of the component together with the substrate, especially when the component is designed as a strand-shaped hollow electrical conductor, for example, when the cross-sections of the construction are bent, part can be kept particularly stable.

It can also be provided that after the application of the coating, the semi-finished product consisting of substrate and coating is deformed into a coil geometry and then pressed in order to calibrate a coil body to an available installation space and to achieve a flat contact from turn to turn of the coil body .

It can further be provided that several electrically conductive components formed as strand-shaped conductors are twisted together with the substrate together with the substrate in order to achieve a reduction in the skin effect, in particular insulation of the conductors / electrically conductive components from one another before or after Twisting takes place.

To remove the substrate from the load-bearing layer, it can be provided that the substrate is detached from the load-bearing layer and at least partially removed by burning out, dissolving in a solvent, mechanical comminution, chemical decomposition, melting, evaporation or sublimation.

This can take place after the substrate has been completely coated in a subsequent process step, or with the continuous production of an endless component, for example a pipe, in a process step that is passed through continuously after the coating. The substrate can also be removed before or after deformation, for example bending, of the component to produce the final shape.

In a particular method for producing a substrate for use in one of the above-mentioned methods, it can be provided that the substrate is cast in a mold which is coated with a material which adheres to the surface of the substrate and which is designed in this way that it enables or facilitates the deposition and / or adhesion of the load-bearing layer on the substrate.

In principle, the substrate can be produced as a core in an upstream casting process in simple or complex shapes, using the processes known from foundry technology.

The coating of the casting mold used for the substrate in the above-mentioned type enables this coating to be transferred to the surface of the substrate and facilitates the subsequent coating process.

The invention is shown below with reference to figures of a drawing and is explained below. It shows

Figure 1 is a strand-shaped substrate in a perspective view,

Figure 2 schematically the process of coating,

FIG. 3 is a perspective view of a coated substrate,

FIG. 4 shows the component produced after removing the substrate in a perspective view,

FIG. 5 shows a winding of a tubular construction produced according to the invention,

FIG. 6 shows a component which has been bent before removing the substrate, and also

FIGS. 7 and 8 show a helical substrate in the extracted and compressed state.

FIG. 1 shows a cylindrical, strand-shaped substrate 1 which is coated in the context of the method according to the invention. The substrate 1 is a simple example which can be used for the production of a hollow winding wire with a hollow cylindrical cross section.

In FIG. 2, the substrate 1 is shown, with arrows 2, 3, 4 indicating that particles, for example atoms, micro- or nanoparticles or droplets, are applied to the surface of the substrate 1 from the outside. For this purpose, the substrate can optionally have a pre-coating, which can be electrically conductive, for example, in order to be able to use coating processes that require the application of a voltage or that function, for example, as a galvanic coating without external voltage.

In FIG. 3, the substrate 1 is shown with a load-bearing layer 5 applied. The representation is schematic and the thickness of the layer 5 and the ratio of the layer thickness to the diameter of the substrate are only exemplary. In many cases the thickness of the layer / coating 5 will be smaller in relation to the diameter of the substrate 1.

In FIG. 4, the end product is shown in the form of a hollow tube 5, the substrate 1 being separated from the layer / coating 5 by liquefaction, burning out or other removal.

In FIG. 5, a helical winding 6 is shown, which consists of a bent tube 7. This can be produced in the curved shape as shown in FIG. 5 by means of a substrate of the same shape with a metal layer applied to it. However, it is also possible to first use an elongated, straight, strand-like substrate, to coat it and thereby produce a straight tube. This can, as shown for example in FIG. 6, be bent together with the coated substrate. After the substrate has been brought into the desired shape together with the coating, the substrate can be removed. Such a deformation of the tubular component produced together with the substrate still located therein has the advantage that, during the deformation, the cross-section is retained in the substrate by means of support and buckling of the tubular component can be avoided. FIG. 6 optionally shows an insulating coating 8 of the electrically conductive layer 5 in dashed form.

However, it is also conceivable to first remove the substrate from the component and then to deform the hollow component.

FIG. 7 shows a substrate in the form of a helix shown schematically in a side view, in which the individual windings 9, 10 lie close together in the relaxed state. FIG. 7 shows that the substrate is pulled apart along the longitudinal axis 11 of the helix by tensile forces 12, 13 before coating. The substrate can be an elastic materi al, for example an elastic polymer.

In FIG. 8, the coil is shown after the coating, the coating being indicated schematically by the dashed lines 14. The coating can consist of the electrically conductive, stable metal layer, which later forms the conductive component. However, the coating can also include an electrically insulating cover layer made of a plastic or an oxide or some other material. FIG. 8 shows a state that is compressed in the longitudinal direction of the helix, which either occurs after the tensile forces 12, 13 have ceased to exist by relaxation of the substrate material or is actively achieved by the application of compression forces 15, 16 in the longitudinal direction of the helix.

In the following, two exemplary embodiments are described using specific materials.

Embodiment 1:

A wax that is suitable for the production of complex structures by casting is mixed with a graphite. As a result, an electrical conductivity is achieved in the mixture, which can be controlled by the proportion of gra phits mixed in (for example 1/1000 l / ohm * cm). The resistor is chosen so that it is sufficiently small for the galvanic deposition of a copper jacket on the substrate. The type of addition of graphite can also influence the surface structure of the wax-like substrate. By designing the surface structure of the substrate, for example setting a certain roughness or unevenness, this shape is transferred to the inner surface of the component formed by the applied layer,

A copper sulphate solution can be used for the electroplating and the component is cathodically polarized. The deposition parameters allow the layer thickness of the copper cladding to be varied in a wide range between a few micrometers and a few millimeters.

After the copper has been deposited, the wax of the substrate is melted out at 120 ° C and thus removed.

Embodiment 2:

A complex geometric shape of a substrate can first be produced from a tool using a wax injection molding process or a forming process. In addition to the use of injection molding processes, machining processes are also conceivable as an alternative or in addition.

The resulting substrate can be provided with a thin layer of platinum or palladium in the sputtering process in order to produce electrical conductivity on the surface of the substrate. The substrate can then be galvanically coated with copper. In a subsequent step, the wax / substrate can then be melted out of the component by heating.

The invention makes it possible to produce complex-shaped metallic components with an internal cavity, for example in the form of a longitudinal channel and variably adjustable wall thickness. The metallic coating can be done with pure metals such as copper or aluminum with the highest purity, so that the best electrical conductivity can be achieved. Such materials cannot simply be processed in casting processes or forming processes without risking damage to the structure, which, among other things, can lead to leaks.

By means of the method, tools coated with metal can be produced from profile wires, which are cut to the correct size in a subsequent process step and shaped into the desired geometry, for example a coil.

Particularly in the production of internally cooled electrical conductors, coils or windings can be produced which enable a significantly increased current density compared to coils / windings of the prior art. This enables, for example, mechanical drives with increased torque density.

Claims

1. A method for producing an electrically conductive component (5) with a cavity, characterized in that on a dissolvable substrate (1) a stable, fluid-tight layer (5) made of an electrically conductive material, in particular in a layer thickness of more than 3 micrometers - More than 20 micrometers in particular are applied in such a way that the substrate (1) is covered in a fluid-tight manner by the layer (5) and that the substrate (1) is then dissolved and at least partially removed.

2. The method according to claim 1, characterized in that the load-bearing, fluid-tight layer (5) is formed in a layer thickness of less than 20 mm, in particular less than 5 mm.

3. The method according to claim 1 or 2, characterized in that the substrate is strand-shaped and that the layer (5) is applied on all sides to the jacket surface (s) of the substrate (1), such that the jacket surface) of the substrate is fluid-tight are covered.

4. The method according to any one of claims 1 to 3, characterized in that the load-bearing layer (5) is applied to the substrate (1) by applying particles.

5. The method according to any one of claims 1 to 4, characterized in that the substrate (1) at least partially consists of an electrically conductive material, in particular a metal or an electrically conductive plastic or of an electrically insulating material filled with conductive particles .

6. The method according to any one of claims 1 to 5, characterized in that the substrate (1) consists at least partially of an electrically insulating material, in particular a plastic, a wax, a ceramic or a thermoplastic material.

7. The method according to any one of claims 1 to 6, characterized in that the substrate (1) prior to the application of the load-bearing layer with an electrically conductive precoating material, in particular with a metal, in particular in the form of micro- or nanoparticles or a conductive plastic or Carbon, in particular in the form of graphite or carbon nanotubes, is pre-coated.

8. The method according to any one of claims 1 to 7, characterized in that the load-bearing layer (5) is applied to the substrate (1) by a galvanic, in particular electrochemical or external currentless method, a PVD coating method or a CVD coating method.

9. The method according to any one of claims 1 to 8, characterized in that the load-bearing layer (5) is applied to the substrate (1) by a plasma spraying process or by immersing the substrate in a molten metal.

10. The method according to any one of claims 1 to 9, characterized in that the load-bearing layer (5) is applied to the substrate (1) in such a way that it surrounds the substrate in a fluid-tight manner on all sides.

11. The method according to any one of claims 1 to 10, characterized in that the substrate (1) by burning out, dissolving in a solvent tel, mechanical crushing, chemical decomposition, melting, evaporation fen or sublimation of the load-bearing layer (5) dissolved and is at least partially removed.

12. The method according to any one of claims 1 to 11, characterized in that the substrate (1) after the application of the load-bearing layer (5) is deformed together with this, in particular bent, and that the substrate is then at least partially removed.

13. The method according to any one of claims 1 to 12, in which a helical substrate is produced and this is pulled apart in the longitudinal direction of the helix and then provided with the Beschich device before the application of the coating.

14. The method according to any one of claims 1 to 13, in which, after the coating has been applied to the substrate, the semifinished product composed of substrate and coating is deformed or processed by means of forming.

15. The method according to any one of claims 1 to 14, in which, after application of the coating, the semi-finished product consisting of substrate (1) and coating (5) is deformed into a coil geometry and then pressed in order to calibrate a coil body to an available installation space and to achieve a flat contact from turn to turn of the coil former.

16. The method according to one or more of claims 1 to 15, in which a plurality of electrically conductive components designed as strand-shaped conductors are twisted together with the substrate in order to achieve a reduction in the skin effect, in particular an insulation of the conductors / electrically conductive components against each other before or after twisting.

17. A method for producing a substrate for use in a method according to any one of claims 1 to 16, characterized in that the substrate (1) is cast in a mold which is coated with a material which adheres to the surface of the substrate and which is such that it enables or facilitates the deposition and / or adhesion of the load-bearing layer (5) on the substrate (1).