DE102016206804A1 - 3D printing process for the additive production of metal components - Google Patents

Abstract

A 3D printing process for the additive production of metal components (1) with stratified depositing and liquefying a metal modeling material, with layerwise hardening of the liquefied metal modeling material to form the metal component (1) and for forming support structures (3), which for static support of the Metal component (1) are formed during the additive manufacturing, and with Wegschmelzen (M3) of the support structures (3) with microwave radiation (5a).

Description

The present invention relates to a 3D printing method for the additive production of metal components. In particular, the present invention is concerned with the removal of support structures during the additive fabrication of metal components.

In generative or additive manufacturing processes, also commonly referred to as "3D printing process", starting from a digitized geometric model of an object, one or more starting materials are sequentially stacked and cured in layers. 3D printing offers exceptional design freedom and, among other things, makes it possible to produce objects with manageable costs, which would not be possible or could only be produced with considerable effort using conventional methods. For this reason, 3D printing processes are currently widely used in industrial design, in the automotive industry, the aerospace industry or in general in industrial product development, in which a resource-efficient process chain for small and large-scale mass production of individualized components is used.

Thus, for example, in Selective Laser Melting (SLM), a component is built up in layers from a modeling material, in particular a metal, by applying the modeling material in powder form to a substrate and deliberately liquified by local laser irradiation, resulting in a solid, coherent component after cooling , The surrounding powder can in principle serve the static support of the previously constructed part of the component. Depending on the complexity of the component to be produced, however, additional support structures or support structures are often printed. For example, protruding or exposed component areas, hollow structures or the like can be supported until complete curing of the component. After curing of the component, these support structures are typically laboriously removed by hand, z. B. by grinding, breaking, filing, etc., which is both time-consuming and costly.

In addition to laser beams, common 3D printing methods sometimes use electron beams or other particle beams for the local introduction of energy. More recently, first approaches to 3D printing are pursued, in which metal powder is melted and / or sintered by means of microwave radiation. For example, the document teaches WO 2012/127456 A1 additive processes which take advantage of the localized microwave heating (LMH) effect to layer metal components from a metal powder. Here, the metal powder is locally very limited melted in areas with dimensions significantly smaller than the wavelength of the microwave radiation used.

Against this background, the present invention has the object to find simple and precise solutions to remove support structures of additively manufactured metal components.

According to the invention, this object is achieved by a method having the features of patent claim 1.

Accordingly, a 3D printing method for additive manufacturing of metal components is provided. The 3D printing process involves layer-by-layer deposition and liquefaction of a metal modeling material. The 3D printing process further comprises layer-by-layer curing of the liquefied metal modeling material to form the metal component and to form support structures configured to statically support the metal component during additive manufacturing. The 3D printing process further comprises melting away the support structures with microwave radiation.

The idea underlying the present invention is to use microwave radiation to remove support structures. In the additively produced, metallic (ie conductive) component and the support structures, electric currents are induced by the microwaves, at least in the area of the surface, which can lead to a heating of the component or the support structures. The present invention takes advantage of the finding that support structures are typically formed with much lower material thicknesses (eg, the thickness of a wall or the diameter of a strut, support, etc.) than the actual metal component. For example, in many applications, the minimum wall thickness of metal components is well above about 1 mm, which is many times greater than the thickness of the respective support structures, which may be, for example, in the range of 1 to about 100 microns. With a corresponding configuration of the microwave radiation used, it is possible in particular to heat only the relatively delicate support structures so strongly that they melt away. This creates the considerable advantage that support structures can be removed automatically, quickly and without manual work. In particular, support structures can be removed precisely even on manually difficult to reach places.

3D printing methods are particularly advantageous because they allow the production of three-dimensional components in original molding processes, without special, on the outer shape of the Components need matched production tools. This enables highly efficient, material-saving and time-saving production processes for components and components. Particularly advantageous are such 3D printing process for structural components in the aerospace sector, since there are used many different, tailored to specific applications components that in such 3D printing process with low cost, low production lead time and low complexity in the for the Manufacture required manufacturing equipment can be produced.

For the purposes of the present application, 3D printing methods encompass all additive or additive manufacturing methods in which, on the basis of geometric models, objects of predefined form from informal materials such as liquids and powders or semi-finished products such as strip or wire-shaped material by means of chemical and / or physical Processes are produced in a special generative manufacturing system. In the context of the present application, 3D printing processes use additive processes in which the starting material is built up sequentially in layers in predetermined forms. In particular, 3D printing processes include stereolithography (SLA), selective laser sintering (SLS), selective laser melting (SLM), selective electron beam sintering (SEBS) ) and Selective Electron Beam Melting (SEBM).

Advantageous embodiments and further developments will become apparent from the other dependent claims and from the description with reference to the figures.

According to a development, the melting away of the support structures can take place after complete curing of the metal component. In other developments, however, all support structures or at least a portion of the support structures can also already be removed during the curing of the metal component. For example, support structures can be successively removed from already hardened portions of the metal component.

According to a development, the microwave radiation can be irradiated locally directed to the support structures. In principle, it is possible to apply more or less large portions of the metal component or the entire metal component with microwave radiation. However, in particular, the locally limited irradiation of directional microwaves can be advantageous. Hereby, electrical currents can be specifically induced in the areas where support structures are to be removed. In particular, support structures can be directly and exclusively irradiated in order to melt them piece by piece without possibly influencing neighboring component areas by the microwave radiation. Depending on the application and depending on the desired geometric configuration of the support structures used, it will be apparent to those skilled in the art how exactly the microwave irradiation should be formed. For example, in certain applications, several hundred very thin pillars may be provided which open to networks o. Ä. are connected to fix the actual metal component. In this case, for example, entire areas of these pillars can be irradiated together with microwaves.

According to a development, the support structures can be formed with material thicknesses smaller than about 100 micrometers. Depending on the material thickness of the metal component to be produced, typical support structures can therefore be made particularly thin. For example, the metal component may provide material thicknesses of at least 1 mm, while the support structures have substantially smaller cross-sections or diameters, e.g. B. 50 microns or smaller.

According to a development, the layered depositing and liquefying of the metal modeling material may comprise irradiating the metal modeling material with a microwave radiation. The microwave radiation can be irradiated locally. Accordingly, not only the support structures with microwave radiation are melted away in this development, but also the metal modeling material itself is melted with microwave radiation and liquefied. Basically, in this case a single microwave source can be used for both processes, provided that this is correspondingly flexible to meet both the geometric requirements, as well as a suitably prepared microwave radiation in the necessary wavelength ranges or frequency ranges, with the required power and Einstrahlcharakteristik, etc. to provide. In this case, the use of microwaves can in particular supplement or replace conventional additive methods based on laser beams and / or particle beams.

According to a development, the layered depositing and liquefying can comprise irradiation of the metal modeling material with a laser beam or an electron beam. In particular, layer-by-layer deposition and liquefaction may be a method of the group of selective laser sintering, selective laser melting, stereolithography, selective electron beam sintering, and the like selective electron beam melting or the like.

According to a development, the metal modeling material can be deposited in powder form.

According to a development, the metal modeling material may be selected from the group of metallic materials, metallic material combinations and metallic alloys.

According to a development, the metal modeling material may be selected from the group of aluminum, titanium, steel or an alloy thereof. However, the method is also suitable for a wide variety of electrically conductive materials, in particular those materials which have a high specific resistance.

The above embodiments and developments can, if appropriate, combine with each other as desired. Further possible refinements, developments and implementations of the invention also include combinations, not explicitly mentioned, of features of the invention described above or below with regard to the exemplary embodiments. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

The present invention will be explained in more detail with reference to the exemplary embodiments given in the schematic figures. It shows:

1a schematic cross-sectional view of a 3D printing device for performing a 3D printing method according to an embodiment of the invention;

1b schematic cross-sectional view of a 3D printing device for performing a 3D printing method according to an alternative embodiment of the invention;

1c schematic cross-sectional views of the 3D printing device off 1a or 1b while performing the 3D printing process; and

2 a schematic flow diagram of the 3D printing process, which from the 3D printing devices 1a - 1c is carried out.

The accompanying figures are intended to convey a further understanding of the embodiments of the invention. They illustrate embodiments and, together with the description, serve to explain principles and concepts of the invention. Other embodiments and many of the stated advantages will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale to each other.

In the figures of the drawing are the same, functionally identical and same-acting elements, features and components - unless otherwise stated - each provided with the same reference numerals.

The 1a and 1b each show a schematic cross-sectional view of a 3D printing device 100 for performing a 3D printing method M according to embodiments of the invention. This shows 1a a 3D printing device 100 , which is a laser beam 6 used for the basic 3D printing process. The 3D printing device 100 in 1b In contrast, uses microwave radiation 5b , A schematic flow diagram of such 3D printing methods M is shown in FIG 2 shown. 1c forms a specific method step of these methods M.

The 3D printing processes M are used for the additive production of metal components 1 , For this purpose, such a 3D printing method M comprises, under M1, layer-by-layer deposition and liquefaction of a metal modeling material. The 3D printing process M further includes, under M2, layer-by-layer curing of the liquefied metal modeling material 2 for the formation of the metal component 1 and for the formation of support structures 3 , The support structures serve for the static support of the metal component 1 during the 3D printing process. For example, component areas, hollow structures or general protruding or freestanding areas exposed in this way can be stabilized until they have cured completely or at least sufficiently. The metal modeling material 2 may be selected from the group of metallic materials, metallic material combinations and metallic alloys. In particular, the metal modeling material may be 2 For example, titanium, aluminum and / or an alloy or material combination of these act. For example, the metal modeling material 2 be an aluminum-silicon powder, for. B. AlSi10Mg, or a more advanced material or a material mixture such as Scalmalloy ^® or the like. Basically, the support structures of the same basic material as the metal component 1 be made yourself. In principle, however, it is also provided, the support structures or at least a portion of the support structures of a different material than the metal component 1 to manufacture. For this purpose, the 3D printing device 100 For example, be designed as a multi-component printing device. The following is simplified here the basic term metal modeling material 2 used. It will be clear to the person skilled in the art that a metal modeling material 2 within the meaning of the invention may also represent a combination of several materials. The metal modeling material 2 itself can be provided in powder form and stored.

Basically, the present invention provides a variety of possibilities, the metal modeling material 2 to liquefy, at which heat targeted locally deposited metal modeling material 2 can be initiated. This is how the 3D printing device is based 100 in 1a and the associated method M, for example, on the use of a laser beam 6 , which can generate heat very targeted and controlled. The 3D printing method M according to 1a Thus, for example, it may be selected from the group of selective laser sintering, selective laser melting and stereolithography, or the like. In the following, a corresponding 3D printing method M is used in conjunction with 1a in connection with selective laser melting (SLM), in which the metal modeling material 2 in powder form on a work platform 9 is applied and targeted by local laser irradiation with a laser beam 6 is liquefied, resulting in a solid, coherent metal component after cooling 1 results. Alternatively or in addition to a laser beam 6 However, a 3D printing method M according to the invention, but also particle beams, for. As an electron beam, and / or microwave radiation 5b for liquefying the metal modeling material 2 use. 1b shows an exemplary embodiment in which a (second) microwave source 4b microwave radiation 5b generated and locally directed to the metal modeling material 2 radiates, whereby this is locally melted.

The 3D printing device 100 in 1a sees an energy source in the form of a laser 12 For example, an Nd: YAG laser, a CO ₂ laser or the like. The laser 12 sends in 1a a laser beam 6 location-selective to a particular part of a powder surface of the powdered metal modeling material 2 which is in a working chamber 10 on a work platform 9 rests. For this purpose, an optical deflection device or a scanner module such as a movable or tiltable mirror 7 be provided, which the laser beam 6 depending on its tilted position on a specific part of the powder surface of the metal modeling material 2 distracting. At the point of impact of the laser beam 6 becomes the metal modeling material 2 heated, so that the powder particles are locally melted and form an agglomerate on cooling. Depending on an example, by a CAD system ("computer-aided design") provided and optionally processed digital production model rasterizes the laser beam 6 the powder surface off. After selective melting and local agglomeration of the powder particles in the surface layer of the metal modeling material 2 can excess, non-agglomerated metal modeling material 2 to be singled out. Then the work platform becomes 9 by means of a lowering piston 11 lowered (see arrow in 1c ) and with the help of a powder feed 8th or any other suitable device, new metal modeling material 2 from a reservoir into the working chamber 10 transferred. The metal modeling material 2 can accelerate the melting process by infrared light to just below the melting temperature of the metal modeling material 2 preheated working temperature lying. In this way, a three-dimensional sintered or "printed" metal component is created in an iterative generative construction process 1 from agglomerated metal modeling material 2 , The surrounding powdered metal modeling material 2 can support the hitherto constructed part of the metal component 1 serve. Through the continuous downward movement of the work platform 9 The metal component is created 1 in layered model generation.

In the 1a and 1b 3D printing methods shown M are fundamentally characterized in that the support structures 3 with microwave radiation 5a in a melting process 13 be melted away. This is in 2 under M3 as a separate process step, which also in 1c is shown exposed. The melting away of the support structures 3 can in particular after complete curing of the metal component 1 respectively. For this purpose, the microwave radiation 5a from a first microwave source 4a locally focused on the support structures 3 be irradiated. The present invention makes use of such support structures 3 typically much thinner, ie with lower material thicknesses, than the metal component 1 can be trained themselves. For example, the support structures 3 with material thicknesses smaller than 100 microns, z. B. 50 microns or 10 microns can be formed. In the metal support structures 3 Now, due to the microwave radiation, at least in the area of the surface, electrical currents are induced, which leads to a heating up and finally to a melting away of the support structures 3 being able to lead. With a suitable choice of microwave radiation 5a can such thin support structures 3 be removed quickly, easily and precisely even on hard to reach places. For example, occurs in a rod-shaped support structure 3 with a cross-sectional area of 0.0075 mm ² and a length of 10 cm with a microwave power of 1000 W, a power loss of about 13 W. In the case of a support structure 3 made of aluminum (specific heat 0.9 j / gK, density 2.7 g / cm ³ ) is required to reach the Melting temperature of about 660 ° C, an amount of energy of 1.2 J. At a power of 13 W would a single such support structure 3 therefore melt away in fractions of a second.

In the case of the embodiment according to 1b can be the first microwave source 4a , which melt away the support structures 3 is used, and the second microwave source 4b used to liquefy the metal modeling material 2 used to be different sources or the same source. In many applications, it will sometimes be advantageous, the first microwave source due to the different requirements for the microwave radiation and in particular due to geometric conditions 4a and the second microwave source 4b form as separate microwave sources.

Possibly. However, it is also intended to produce microwaves for both purposes with only a single source and to apply accordingly.

The described methods can generally be used in all areas of the transport industry, for example for road vehicles, for rail vehicles or for watercraft, but also in engineering and mechanical engineering.

In the foregoing detailed description, various features have been summarized to improve the stringency of the illustration in one or more examples. It should be understood, however, that the above description is merely illustrative and not restrictive in nature. It serves to cover all alternatives, modifications and equivalents of the various features and embodiments. Many other examples will be immediately and immediately apparent to one of ordinary skill in the art, given the skill of the art in light of the above description.

The exemplary embodiments have been selected and described in order to represent the principles underlying the invention and their possible applications in practice in the best possible way. As a result, those skilled in the art can optimally modify and utilize the invention and its various embodiments with respect to the intended use. In the claims as well as the description, the terms "including" and "having" are used as neutral language terms for the corresponding terms "comprising". Furthermore, a use of the terms "a", "an" and "an" a plurality of features and components described in such a way should not be excluded in principle.

LIST OF REFERENCE NUMBERS

1

metal component

2

Metal modeling

3

Metal supporting structure

4a

first microwave radiator

4b

second microwave radiator

5a, 5b

microwave radiation

6

laser beam

7

mirror

8th

powder feed

9

work platform

10

working chamber

11

lowering slider

12

laser

13

smelting process

100

3D printing device

M

3D printing process

M1

step

M2

step

M3

step

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2012/127456 A1 [0004]

Claims (9)

3D printing process (M) for the additive production of metal components ( 1 ), with stratified deposition and liquefaction (M1) of a metal modeling material ( 2 ); Layer-wise curing (M2) of the liquefied metal modeling material ( 2 ) for forming the metal component ( 1 ) and to form support structures ( 3 ), which for static support of the metal component ( 1 ) are formed during additive manufacturing; and melting away (M3) of the support structures ( 3 ) with microwave radiation ( 5a ). 3D printing method (M) according to claim 1, wherein the melting away (M3) of the supporting structures ( 3 ) after complete curing of the metal component ( 1 ) he follows. 3D printing method (M) according to claim 1 or 2, wherein the microwave radiation ( 5a ) locally directed to the support structures ( 3 ) is irradiated. 3D printing method (M) according to one of the preceding claims, wherein the support structures ( 3 ) are formed with material thicknesses smaller than 100 microns. A 3D printing method (M) according to any one of the preceding claims, wherein the layering and liquefying (M1) of the metal modeling material (M1) 2 ) Irradiation of the metal modeling material ( 2 ) with microwave radiation ( 5b ), which is irradiated locally. A 3D printing method (M) according to any one of the preceding claims, wherein the layering and liquefying (M1) irradiation of the metal modeling material ( 2 ) with a laser beam ( 6 ) or an electron beam. A 3D printing method (M) according to any one of the preceding claims, wherein the metal modeling material (M) 2 ) is deposited in powder form. A 3D printing method (M) according to any one of the preceding claims, wherein the metal modeling material (M) 2 ) is selected from the group of metallic materials, metallic material combinations and metallic alloys. A 3D printing method (M) according to claim 8, wherein the metal modeling material (M) 2 ) is selected from the group of aluminum, titanium, steel or an alloy thereof.

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