DE102022207112A1 - Process for the additive manufacturing of a component using a metal-plastic powder mixture - Google Patents

Abstract

The proposed solution relates in particular to a method for the additive manufacturing of a component (B), in which a powdery printing material is applied in layers. A metal-plastic powder mixture with a metal component (10) and a plastic component (11) is used as the printing material. After the metal-plastic powder mixture has been applied, a plastic portion of the metal-plastic powder mixture is evaporated at least locally by heat input, before an at least locally remaining metal portion (10) of the applied metal-plastic powder mixture - to form a section with a solid metal structure ( 4, 4A-4E) for the component to be manufactured (B) - is connected by heat input.

Description

The proposed solution relates in particular to a method for the additive manufacturing of a component.

It is widely known to use powdered printing material in the additive manufacturing of a component and to build the component in layers. The powdered printing material is applied in layers on a printing platform of a 3D printing device. Typically, it is not without difficulties to additively manufacture a component that should consist of both a plastic material and a metal. What plays a particular role here is that the melting points of plastic and metal are comparatively far apart. In order to form a solid body or a solid body section for the metal component to be produced, metallic printing material is melted or sintered. However, the temperatures required for this then sometimes considerably exceed the melting temperature of the plastic, so that plastic material that has already been applied may be destroyed.

The present solution is therefore based on the task of providing improvements for the additive manufacturing of a component made of metal and plastic.

This object is achieved both with a method of claim 1 or 14 and by a 3D printing device of claim 15 or a use of claim 17.

According to a first aspect of the proposed solution, it is intended to use a metal-plastic powder mixture with a metal component and a plastic component as the printing material. After the metal-plastic powder mixture has been applied, the plastic component is at least locally evaporated by heat input (and thus locally removed) before an at least locally remaining metal component of the applied metal-plastic powder mixture is connected by heat input.

A basic idea of the proposed solution is the approach of using a metal-plastic powder mixture to apply metal components and plastic components together in a printing process, but then subsequently removing a plastic component by evaporation, so that remaining metal (to form a section with solid metal structure for the component to be manufactured), i.e., for example melted or sintered. By evaporating the plastic portion, the metal portion can be exposed in a localized manner. In other words, through, for example, locally limited, targeted evaporation of the plastic portion of the applied metal-plastic powder mixture, only metal-containing powder without plastic will be made available, so that, for example, in a subsequent process step, the metal portion that only remains locally can be melted or sintered, without plastic being melted or sintered.

In principle, an at least local, in particular only local, i.e. locally limited, evaporation of the plastic component can only take place after several (at least two) layers of the metal-plastic powder mixture have been applied, and in particular in several applied layers. In such an embodiment variant, a plastic portion is therefore only evaporated after several layers of metal-plastic powder mixture have been applied. The plastic component can also evaporate in layers, i.e. H. Layer by layer, or over several layers.

In at least one embodiment variant, it is provided that before the at least locally remaining metal portion is connected to that region (one or more layers) of the applied metal-plastic powder mixture in which the plastic portion was evaporated in a first process step to form a metal structure, at least an additional layer of the metal-plastic powder mixture is applied. The application of at least one additional layer of the metal-plastic powder mixture can serve to compensate for shrinkage. As a result of the evaporation of the plastic content - possibly in a defined and locally limited area and in comparison to adjacent areas - less material is present. By applying one or more additional layers of the metal-plastic powder mixture, a corresponding reduction in the layer thickness can be compensated for. In this context, it can also be provided that the connection of the metal component takes place in a subsequent second process step, only after the plastic component has also previously been evaporated in the at least one additional layer applied. In this way, the metal portion of the additional layer can also be connected in the second process step. For example, a metal portion of one or more applied additional layers can also be melted or sintered in order to create a larger metal structure. The at least one (additional) additional layer applied can be dimensioned in terms of the volume of its metal content in such a way that that the volume of the evaporated plastic material is equalized.

For example, a first laser radiation of a first wavelength is used to evaporate the plastic portion, while a second laser radiation of a second wavelength is used to connect the metal portion, the second wavelength being smaller than the first wavelength. This takes advantage of the fact that, depending on the wavelength, a plastic material and a metal typically absorb laser radiation to different degrees. For example, a plastic material, in particular a polymer, absorbs laser radiation of a lower wavelength (for example ≤ 1 µm) significantly worse than a metal. At the same time, laser radiation with a longer wavelength (for example ≥ 6 µm or ≥ 8 µm) is reflected by a metal and therefore not absorbed, while a plastic material, in particular a polymer, absorbs such laser radiation, optionally through additives provided herein. For example, with the help of a first laser radiation that is generated by a first laser, for example a CO ₂ laser, with a longer wavelength, plastic material can be vaporized in a targeted manner, while the corresponding first laser radiation hardly or significantly reduces the metal content of the applied metal-plastic powder mixture unaffected. Furthermore, laser radiation of a lower wavelength, for example green or blue laser radiation generated by a second laser, which is not absorbed by a plastic material but is absorbed by the metal, can be used to achieve a connection of the metal portion by melting or sintering.

In one embodiment variant, a plastic material is provided for the plastic portion of the metal-plastic powder mixture, which incinerates while including an adjacent metal melt. For example, a polymer is provided as a plastic material, optionally by adding appropriate additives, which is ashed under the effect of the high temperatures of an adjacent molten metal to produce a metal structure based on the metal content in an area adjacent to the molten metal, thus over an ash area adjacent to the molten metal thermal insulation of the molten metal from adjacent, already printed areas of the component is achieved.

In principle, the metal-plastic powder mixture can have metal-plastic particles, in particular consist of metal-plastic particles. Here, at least a portion of the metal portion of the metal-plastic powder mixture is formed by a plurality of metal cores of the metal-plastic particles, while at least a portion of the plastic portion of the metal-plastic powder mixture is formed by plastic jackets, each of which encloses a metal core. A large number of metal-plastic particles are therefore provided, each of which has a metal core with an enveloping plastic jacket. The use of corresponding metal-plastic particles facilitates the application of printing material containing metal and plastic in a single printing process, with the proposed solution and the different further treatment of the plastic portion on the one hand and the metal portion on the other hand being used in subsequent process steps to create desired plastic and metal structures for the component to be manufactured can be formed.

In one embodiment variant, a metal structure for the component to be produced is formed with the connected metal portion and it is additionally provided not to evaporate, at least locally, a plastic portion of the applied metal-plastic powder mixture, but to connect it, in particular by melting, sintering or polymerization. In such an embodiment variant, it is therefore provided not only to form an at least locally coherent metal structure from the originally powdery metal portion for the component to be produced, but also to form a plastic structure in which no connection of the powdery metal portion occurs. This includes, for example, a variant in which metal cores of applied metal-plastic powder mixture are embedded unconnected in the plastic structure and only melted, sintered or polymerized plastic material is present between the metal cores. Metal cores are then embedded in the plastic structure, but are not connected to each other. A plastic structure of the component can be formed, for example, by a hardened polymer matrix

A targeted connection of the powdery plastic component to form a solid plastic structure can be carried out using appropriate laser radiation, as explained above. In addition to melting or sintering, (further) polymerization can also be provided, especially in the case of a metal-plastic powder mixture that already contains a polymer. Polymerization here is understood in particular to mean that polymerization is stimulated by laser light in such a way that a molecular weight of the resulting polymer is greater than the molecular weight of the starting materials, which are due, for example, to plastic jackets of the metal-plastic particles that have been applied and therefore printed in layers. For polymerization, the plastic portion can be formed by a thermoplastic polymer, in which shorter polymer chains are linked to form longer ones. An activation of the The mechanism can either be carried out directly by the energy introduced with the laser radiation or by at least one additive contained in the plastic component, which is activated by the laser radiation and acts as a linker. Thermoset polymers can also be used, particularly in conjunction with photoactivators, such as those used in resins for stereolithography 3D printing (SLA).

In both cases, the additives for linking can be activated thermally or via a photoreaction.

In one embodiment variant, anchor structures are formed for the component to be produced by connected metal components applied metal-plastic powder mixture, which are embedded in the finished component in a plastic section - formed by connected plastic components. The anchor structures are connected to a subsequently created metal structure made of further metal components that are also interconnected, so that the metal structure and the anchor structures form a metallic solid body anchored in plastic material. For example, an anchor structure on the finished component engages behind a section made of plastic material in order to produce the metal structure without distortion during the manufacturing process and to keep it positioned and locked in the plastic material as intended. By first forming anchor structures, onto which a metal structure is then melted, for example, distortion during production can be minimized or even completely avoided. The dimensions of the anchor structures initially produced are smaller than the metal structure to be produced, which is additionally fixed in a form-fitting manner via the anchor structures in the plastic material.

For example, at least one metal insert, at least one conductor track or at least one circuit can be formed with connected, originally powdery metal components in the component to be produced. In the course of the proposed solution, corresponding components made of a plastic, in particular a polymer, can be printed comparatively easily with corresponding metallic components. The 3D printing process, which has been improved in accordance with the proposed solution, allows components with metallic components to be produced, in particular with comparatively complex geometries, without the need for special tools, in particular casting molds.

The above-explained use of laser radiation of different wavelengths for the connection of printed plastic material and printed metal is obviously independent of the initially described evaporation of an applied plastic component to create an area in which only a powdery metal component is present, which can then be melted or sintered without plastic material, for example can. Accordingly, a further independent aspect of the proposed solution provides a method for the additive manufacturing of a component, in which a plastic material and a metal are used to build up the component in layers and for the formation of a plastic structure (and therefore a first solid body section) from applied plastic material first laser radiation of a first wavelength is used, while a second laser radiation of a second wavelength, which is smaller than the first wavelength, is used to form a metal structure (and thus a second solid section) from applied metal.

According to the second aspect of the proposed solution, it is not immediately mandatory that the plastic material and the metal are applied via a metal-plastic powder mixture, each of which comprises metal cores encased in a plastic jacket. However, this is generally considered advantageous in order to be able to take advantage of the advantages of the first aspect of the proposed solution explained above.

The proposed solution further includes a 3D printing device for the additive manufacturing of a component, which is suitable for carrying out one of the proposed methods. In particular, a proposed 3D printing device can be set up to use a metal-plastic powder mixture with a metal component and a plastic component as a printing material and can also be set up to at least locally produce a plastic component of the metal-plastic material after the metal-plastic powder mixture has been applied by applying heat. To evaporate the powder mixture before an at least locally remaining (not evaporated) metal portion of the applied metal-plastic powder mixture is connected to the 3D printing device by heat input (for example in a subsequent process step and using a different laser than for the evaporation of the plastic portion). is, in particular melted or sintered.

Furthermore, it is considered fundamentally advantageous to use a metal-plastic powder mixture in an additive manufacturing process, which has metal-plastic particles, each with a metal core and a plastic jacket surrounding the metal core, in particular made of ent speaking metal-plastic particles. In practice, a corresponding metal-plastic powder mixture has not yet been used in the additive manufacturing of a component.

In particular, it is considered advantageous in this context if the plastic jacket is formed by a polymer. The use of a polymer is particularly suitable in view of the different absorption abilities of a metal depending on a wavelength of laser radiation generated and hitting the respective material. Laser radiation of a specific wavelength or a specific wavelength range can be used to specifically heat the polymer portion or the metal portion of the applied powder.

The attached figures illustrate exemplary possible embodiment variants of the proposed solution.

• 1 mehrere Schichten additiv aufgebrachten Metall-Kunststoff-Pulvergemischs mit Metall-Kunststoff-Partikeln;
• 2 ein Absorption-Wellenlängen-Diagramm für unterschiedliche Werkstoffe unter Hervorhebung zweier Laser und deren Wellenlänge für unterschiedliche Materialien eines Metall-Kunststoff-Pulvergemischs;
• 3A bis 3F unterschiedliche Phasen bei einer Ausführungsvariante eines vorgeschlagenen Verfahrens, bei dem unter Nutzung der beiden unterschiedlichen Laser der 2 in einer 3D-Druckervorrichtung Kunststoffstrukturen und Metallstrukturen für ein herzustellendes Bauteil erzeugt werden;
• 4 ein hergestelltes Bauteil, bei dem eine oberflächenseitig zugängliche Metallstruktur über Ankerstrukturen in einer Polymermatrix verankert ist.

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• 1 several layers of additively applied metal-plastic powder mixture with metal-plastic particles;
• 2 an absorption wavelength diagram for different materials highlighting two lasers and their wavelength for different materials of a metal-plastic powder mixture;
• 3A until 3F different phases in an embodiment variant of a proposed method in which using the two different lasers 2 Plastic structures and metal structures are produced in a 3D printer device for a component to be produced;
• 4 a manufactured component in which a surface-accessible metal structure is anchored in a polymer matrix via anchor structures.

The 1 shows schematically printed layers S1, S2 and S3 for a component to be manufactured additively during a 3D printing process. A metal-plastic powder mixture consisting of metal-plastic particles 1 is used to produce the layers S1, S2 and S3. The metal-plastic particles 1 of the powder mixture each have a metal core 10 which is completely covered by a plastic jacket 11. The one in particular in the sectional view of the 1 The apparent circular cross section of a metal-plastic particle 1 and a resulting spherical shape, for example, are merely exemplary. Of course, another cross-sectional shape can also be provided.

With the metal-plastic particles 1, both a metal component via the metal cores 10 and a plastic component via the plastic jackets 11 are applied to a printing platform of the 3D printer device in a printing process in each layer S1, S2 and S3. Consequently, a plastic material is printed on the plastic jackets 11 at the same time as the metal cores 10. The plastic material for the plastic jackets 11 can be formed, for example, by a polymer. In the following we will also speak of a polymer jacket 11.

As shown in diagram D 2 is illustrated in which an absorption capacity is plotted over a wavelength for different materials, different materials absorb (laser) light to different extents depending on the wavelength. This is used for selective heat input into the different materials of the metal-plastic particles 1. For example, a first laser LP is provided, for example in the form of a CO ₂ laser, which generates laser radiation with a higher wavelength in the range of 8-12 μm. Due to the comparatively low absorption capacity of a metal in this wavelength range, such as stainless steel or structural steel, but the high absorption capacity of a polymer, the first laser LP can be used for the targeted introduction of heat into a polymer. The laser radiation from the first laser LP with a wavelength in the range of, for example, 10 μm is reflected by the metal and therefore not absorbed, while it is absorbed by the polymer material in the polymer jackets 11. In principle, a corresponding absorption capacity of the polymer can also be adjusted using additives added to the polymer material.

A second laser LM in turn generates laser radiation of a lower wavelength, in the present case for example in the range of 0.4-0.6 µm. For example, the second laser LM is a laser for generating green or blue laser light. Laser radiation of this smaller wavelength is well absorbed by a metal and is therefore suitable for heating it. However, the polymer material of the polymer jackets 11 is transparent to laser light of this wavelength. Using the different lasers LP and LM, metal cores 10 and polymer jackets 11 of already applied metal-plastic powder mixtures can be selectively connected in a 3D printer device, in the present case in particular melted or sintered (or in the case of the polymer material also (further) polymerized).

The 3A until 3E show an exemplary process of a proposed method for making a difference in a component B to be manufactured To form solid body sections made of polymer material on the one hand and metal on the other hand using the metal-plastic particles 1. This means that after applying a layer S1, S2 or S3 or several layers S1, S2 and S3 of the powder containing the metal-plastic particles 1 in accordance with 1 in a first process step according to 3A with one or more lasers LP specifically acting on part of the polymer jackets 11. Here, the respective laser LP can be operated with different power or a single laser LP can always generate laser radiation of identical wavelength for heat input into the polymer material of the polymer jackets 11, but with different power, depending on how the polymer material is to be processed in a specific area . For example, in the 3A a subdivision of the component section shown is provided into three areas or groups G1, G2, G3.

In a first area G1, the laser LP is operated with lower power in order to melt, sinter or (further) polymerize polymer material of the polymer jackets 11, so that the individual polymer jackets 11 connect to one another and form a closed polymer structure 3 according to the 3B form. After hardening or cooling, the metal cores 10 are then embedded in a resulting polymer matrix of the polymer structure 3 without being connected to one another (and therefore without the formation of an electrically conductive path).

For the area G2 adjacent to the area G1, polymer material of the polymer jackets 11 is evaporated in layers using the laser LP. For this purpose, the laser LP is operated with greater power than for producing the polymer structure 3 in the area G1. The evaporation of the polymer jackets 11 in the area G2 ultimately leads according to the 3D This means that in this area G2 only the metal cores 10 are present without plastic.

However, due to the evaporation of the polymer jackets 11, the volume of the corresponding layers S1, S2 and S3 is reduced by the volume of the polymer jackets 11 and the printing material therefore shrinks locally. In order to compensate for the shrinkage, the 3C In the area G2, in which the polymer jackets 11 were previously evaporated, one or more additional layers 100 with additional metal-plastic particles 1 are applied. The shrinkage is therefore compensated for by one or more additional layers. The polymer jackets 11 of the additional layers 100 are evaporated again in the area G2 using the laser LP, so that only metal cores 10 are then present again in the area G2. The (optional) application of the additional layers 100 thus compensates for the shrinkage that occurred due to the evaporation of the polymer jackets 11, with only metal cores 10 or metal powder formed with the metal cores 10 being present in the area G2.

Then according to the 3E With the help of the other, second reader LM, the loose metal powder formed by the exposed metal cores 10 is sintered or fused. The laser radiation generated by the second laser LM is transparent to the polymer material, so that deeper layers are not damaged by transmission. According to the 3F A metal structure 4 is thus formed in the area G2, which - after appropriate cooling - forms a solid section made of metal in the component to be produced. In the present case, this solid section is present adjacent to a solid section made of polymer material in the area G1.

In principle, a variant is also conceivable in which the polymer material used is of such a type that it ashes in the environment of the molten metal generated using the laser LM and then the ash generated in this way provides thermal insulation from the molten metal. In this way, for example, a previously produced section of plastic material or a corresponding plastic structure 3 can be formed in the area G1, which ashes at least locally under the influence of the subsequently produced molten metal in order to form thermal insulation from the molten metal for the metal structure 4 to be produced.

With the metal structure 3 produced, a metal insert, a conductor track or a circuit, for example, can be defined in the finished component B.

In the 4 A finished component B can be seen, in which a produced metal structure 4E is present in a polymer matrix of a polymer structure 3. In this polymer structure 3, the metal structure 4E - which is accessible on an upper side as an example - is anchored in a form-fitting manner in the polymer material of the polymer structure 3 via additional anchor structures 4A, 4B, 4C and 4D made of metal. Corresponding anchor structures 4A to 4D are produced by molten metal in comparatively small areas, in particular smaller areas than the metal structure 4E, in order to avoid deformation of the component B due to distortion. On the initially created anchors or anchor structures 4A to 4D (in the 3 exemplarily T-shaped in cross section), the metal structure 4E is then melted in the further printing process using the second laser LM. The metal structure 4E can, for example, form a conductor track in the finished component B.

In principle, the different lasers LM and LP can generate laser radiation at different times for the selective further processing of the metal and plastic components in the printing material containing the metal-plastic particles 1 and thus in different process phases and in particular a connection of the respective plastic jackets 11 or metal cores 10 each other in layers.

However, a corresponding connection can also be provided across several layers.

Reference symbol list

1

powder

10

metal core

100

Additional layers

11

Polymer jacket

3

Polymer structure/polymer section

4, 4E

Metal structure

4A-4D

Anchor structure

D

Absorption diagram

G1, G2, G3

Area

LM, LP

Laser

S1, S2, S3

layer

Claims (18)

Method for the additive manufacturing of a component (B), in which a powdery printing material is applied in layers, characterized in that a metal-plastic powder mixture with a metal component (10) and a plastic component (11) is used as the printing material and after application of the Metal-plastic powder mixture is evaporated at least locally by heat input, before an at least locally remaining metal portion (10) of the applied metal-plastic powder mixture is connected by heat input. Procedure according to Claim 1 , characterized in that the metal portion (10) remaining at least locally after the plastic portion (11) has evaporated is melted or sintered. Procedure according to Claim 1 or 2 , characterized in that at least local evaporation of the plastic portion (11) takes place after the application of several layers (S1, S2, S3) of the metal-plastic powder mixture and in several applied layers (S1, S2, S3). Procedure according to one of the Claims 1 until 3 , characterized in that before the at least locally remaining metal portion (10) is connected to that area (G2) of the applied metal-plastic powder mixture in which the plastic portion (119) was evaporated in a first process step, at least one additional layer (100) of the metal-plastic powder mixture is applied. Procedure according to Claim 4 , characterized in that the connection of the metal portion (10) takes place in a subsequent second process step after the plastic portion (11) has also previously been evaporated in the at least one applied additional layer (100), so that the metal portion (11) of the additional layer (100) is connected in the second process step. Method according to one of the preceding claims, characterized in that a first laser radiation of a first wavelength is used for the evaporation of the plastic portion (11) and a second laser radiation of a second wavelength is used to connect the metal portion (10), the second wavelength being smaller than is the first wavelength. Method according to one of the preceding claims, characterized in that a plastic material is provided for the plastic portion (11) of the metal-plastic powder mixture, which incinerates under the influence of an adjacent metal melt. Method according to one of the preceding claims, characterized in that the metal-plastic powder mixture has metal-plastic particles (1) and in the metal-plastic powder mixture at least part of the metal content is represented by a plurality of metal cores (10) of the metal Plastic particles (1) are formed, each of which is covered by a plastic jacket (11), which forms part of the plastic portion. Method according to one of the preceding claims, characterized in that a metal structure (4, 4E; 4A-4D) for the component (B) to be produced is formed with the connected metal portion (11) and is additionally provided, at least locally, with a plastic portion (11). of the applied metal-plastic powder mixture not to evaporate but to combine, in particular by melting, sintering or polymerization. Procedure according to the Claims 8 and 9 , characterized in that plastic jackets (11) of several metal-plastic particles (1) of the applied metal-plastic powder mixture are connected to one another, so that a plastic section (3) for the component (B) to be produced is embedded therein but is not connected to one another Metal particles (10) is formed. Procedure according to the Claims 6 and 10 , characterized in that a plastic section (3) is first formed before a section with a metal structure (4, 4E; 4A-4D) is formed to produce a molten metal, under the influence of the molten metal, the plastic material in an area adjacent to the molten metal Area of the plastic section ashed. Procedure according to one of the Claims 8 until 10 , characterized in that for the component (B) to be produced, anchor structures (4A-4D) are formed by connected metal parts (10) applied metal-plastic powder mixture, which are embedded in a plastic section (3) formed by connected plastic parts (11). , and these anchor structures (4A-4D) are connected to a subsequently created metal structure (4E) made of further, also interconnected metal parts (10). Method according to one of the preceding claims, characterized in that at least one metal insert, at least one conductor track or at least one circuit is formed with connected metal parts (10) in the component (B) to be produced. Method for the additive manufacturing of a component (B), in which a plastic material and a metal are used to build up the component in layers, in particular a method according to one of the preceding claims, characterized in that for the formation of a plastic structure (3) from applied plastic material first laser radiation of a first wavelength is used and a second laser radiation of a second wavelength is used to form a metal structure (4; 4A-4E) from applied metal, the second wavelength being smaller than the first wavelength. 3D printing device for the additive manufacturing of a component (B), the 3D printing device being set up to apply a powdery printing material in layers, characterized in that the 3D printing device is designed to use a metal-plastic powder mixture with a metal portion (10) and a Plastic portion (11) is set up as a printing material and is further set up, after applying the metal-plastic powder mixture, to evaporate at least locally a plastic portion (11) of the metal-plastic powder mixture by applying heat before using the 3D printing device to evaporate at least one that remains at least locally Metal portion (10) of the applied metal-plastic powder mixture is connected by heat input. 3D printing facility Claim 15 , characterized in that the 3D printing device comprises a first laser (LP) for the at least local evaporation of the plastic portion (11) and a second laser (LM) for connecting the metal portion (10). Use of a metal-plastic powder mixture in an additive manufacturing process, which has metal-plastic particles (1), each with a metal core (10) and a plastic jacket (11) surrounding the metal core (10). Use after Claim 17 , characterized in that the plastic jacket (11) is formed by a polymer.