METHOD FOR PRODUCING A METAL COMPONENT

Abstract

A process for the manufacture of a metal component, wherein, in a first step, a raw metal component (A) with auxiliary structures (E) is produced by additive manufacture by applying metal powder to a building board (D) in an installation space, the metal powder being made into the raw metal component (A) by selective laser or electron beam melting, wherein the raw metal component (A) is attached to the building board (D) by means of anchor structures (B), wherein, in a second step, the raw metal component (A) attached to the building board (D) with the anchor structures (B) is subsequently removed from the installation space and then the raw metal component (A) attached to the building board (D) by means of anchor structures (B) is subjected to a chemical, electrochemical or chemical and electrochemical post-treatment to remove the auxiliary structures, whereupon the anchor structures (B) are mechanically removed in a third step.

Claims

1. A process for the manufacture of a metal component, wherein, in a first step, a raw metal component (A) with auxiliary structures (E) is produced by additive manufacture by applying metal powder to a building board (D) in an installation space, the metal powder being made into the raw metal component (A) by selective laser or electron beam melting, wherein the raw metal component (A) is attached to the building board (D) by means of anchor structures (B), wherein, in a second step, the raw metal component (A) attached to the building board (D) with the anchor structures (B) is subsequently removed from the installation space and then the raw metal component (A) attached to the building board (D) by means of anchor structures (B) is subjected to a chemical, electrochemical or chemical and electrochemical post-treatment to remove the auxiliary structures, whereupon the anchor structures (B) are mechanically removed in a third step.

2. A process according to claim 1, wherein the anchor structures (B) are manufactured by selective laser or electron beam melting.

3. A process according to claim 1, wherein the building board (D) is metallic and is electrically contacted.

4. A process according to claim 1, wherein the building board (D) is provided with a protective layer after the first step and before the second step.

5. A process according to claim 4, wherein the protective layer is applied by painting.

6. A process according to claim 1, wherein the building board (D) is covered with a housing after the first step and before the second step.

7. A process according to claim 1, wherein at least one metal layer (C) is applied beforehand to the building board (D), at least in the area in which auxiliary structures (B) contact the building board (D), in that powder is made into the metal layer (C) by selective laser or electron beam melting.

8. A process according to claim 1, wherein the anchor structures (B) are mechanically removed in the third step in such a way that the finished metal component and the building board (D) remain behind separately.

9. A process according to claim 1, wherein the raw metal component (A) with auxiliary structures (E) is produced by additive manufacture in the first step by applying metal powder to a building board (D) in an installation space, the metal powder being made into the raw metal component (A) by selective laser or electron beam melting, wherein the raw metal component (A) is attached to the building board (D) by means of anchor structures (B) and to the base of the raw metal component (A), wherein the anchor structures (B) are mechanically removed in the third step and the finished metal component and the building board (D) remain behind while being connected to the base of the component.

10. A process according to claim 5, wherein the protective layer is applied by immersion painting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0036] Advantageous embodiments, details and concrete examples of the invention are explained in detail below.

[0037] FIG. 1 schematically shows the structure of a component to be reworked on the building board.

[0038] FIG. 1 schematically shows an additively manufactured raw component A, which would have to be reworked within the meaning of the invention. The raw component A (made of material 1) is attached to the building board D (made of material 2) by means of anchor structures B (also made of material 1). In addition, at least one or several protective layers (again made of material 1) is/are also provided. Auxiliary structures E (also made of material 1) for mechanically supporting the raw component A can also be seen in FIG. 1.

[0039] In the first step, the raw metal component A with auxiliary structures E is produced by additive manufacturing by applying metal powder to a building board D in an installation space, the powder being made into the raw metal component A by selective laser or electron beam melting, wherein the raw metal component A is attached to the building board D by means of anchor structures B. This intermediate product can be seen in FIG. 1.

[0040] Subsequently, in the second step, the raw metal component A attached to the building board D by means of anchor structures B is removed from the installation space, and then the raw metal component A attached to the building board D by means of anchor structures B is subjected to a chemical or electrochemical or chemically/electrochemically combined post-treatment for removing the auxiliary structures E. In the final step, the anchor structures are removed mechanically so that the finished component, but also the building board D (separate from each other), remain behind.

[0041] One aspect of the invention thus relates to the post-processing of additively manufactured components directly on the building board. For this purpose, components are generated on a building board in an additive process (selective laser or electron beam melting from the powder bed). They are kept on the building board by solid anchor structures (e.g., support pillars). In addition to the anchor structures, there are grid-like auxiliary structures, which are mandatory for the construction process, on the building board, the component or, respectively, between the building board and the component. They are removed in a chemical or electrochemical process so that only the component, the building board and the anchor structures (support pillars) remain.

[0042] Depending on the process conditions, the building board should be protected from the process media. Under certain circumstances, the building board should indeed be available again after the process for another construction job. In this regard, there are three different cases: [0043] The building board is made of the same material as the component. The material removal from the building board during the chemical or electrochemical post-treatment is usually much less than that of the auxiliary structures. In most cases, this material removal can be accepted, and the building board can optionally be reused for the next construction job after minor preparative operations after the anchor structures have been detached. [0044] The building board is made of a different material than the component and is more inert relative to the process media than the component and the support structures. In this case, no further preparatory operations are required. The removal on the building board during the chemical or electrochemical post-treatment is negligible, and said board can be used for further construction jobs after the anchor structures have been detached. [0045] The building board is made of a different material than the component and is attacked more strongly by the process media than the component and the support structures. In this case, it is advantageous if the building board is protected during preparatory operations.

[0046] One way to protect the building board is to paint it. Immersion painting can be fully automated and provides reproducible qualities. However, the spots on the building board underneath the support structures are problematic. They are difficult to reach with most lacquers, which are rather viscous, whereas aqueous electrolytes and process media get into the perforated support structures and attack the building board there.

[0047] To prevent this, one or several layers of the same material as the component must be melted onto the building board underneath the support structures during 3D printing. This layer must be thicker than the removal that is to be expected. The building board with the component and the support structures on it can be immersion-painted as described above in order to protect the remaining surfaces of the building board.

[0048] In addition to additively manufactured anchor structures, the component can also be constructed with the aid of external anchor structures. Then, the component must be hung up separately with the anchor structures so that it will not fall into the process tank or, respectively, so that an electrical contact is ensured. If the support structures are removed purely chemically, it is also possible not to hang up the part separately. A sieve or net would catch said part.

[0049] Upon removal of the support structures, the components can be polished directly on the building board. In doing so, the building board again serves as a goods support. In case of mechanical polishing methods such as, e.g., sandblasting, or other mechanical reworking operations such as, e.g., milling, the anchor structures must be designed appropriately so as to be mechanically resilient.

[0050] If the parts are to be polished chemically or electrochemically, the anchor structures serve as goods supports or electrical contacts, respectively. In this case, they have to be mechanically resilient to a lesser degree.

Example 1

[0051] First, a raw metal component with auxiliary structures is additively manufactured on a building board. The raw metal component to be processed is composed of the component itself (stainless steel 316L), anchor structures (stainless steel 316L), auxiliary structures in the form of support structures (stainless steel 316L), a protective layer (stainless steel 316L) and a building board made of tool steel. The building board is first screwed on the rear side and contacted. The building board is immersion-coated so that it is completely covered, but the component itself does not come into contact with the lacquer. Thereupon, the auxiliary structure (support structure) is chemically removed with an aqueous solution consisting of 60% by volume of water, 40% by volume of H.sub.2SO.sub.4 and 100 g/l NH.sub.4HF.sub.2 in a solution at 30 to 80° C. for 60 to 240 minutes. Furthermore, the component is polished chemically or, respectively, electrochemically on the board. The anchor structures are severed, and their remains are mechanically removed from the component.

Example 2

[0052] First, a raw metal component with auxiliary structures is additively manufactured on a building board. The raw metal component to be processed is composed of the component itself (Ti6Al4V), anchor structures (Ti6Al4V), auxiliary structures in the form of support structures (Ti6Al4V), a protective layer (Ti6Al4V) and a building board made of stainless steel. The building board is first screwed on the rear side and contacted. The building board is immersion-coated so that it is completely covered, but the component itself does not come into contact with the lacquer. Thereupon, the auxiliary structure (support structure) is electrochemically treated/removed in a solution of 60% by volume of water, 40% by volume of H.sub.2SO.sub.4 and 33.3 g/l NH.sub.4HF.sub.2 by applying for a period of 30 to 240 minutes alternately a voltage of 5 V for 1 to 4 seconds and of 25 V for 1 second at 20° C. Furthermore, the part is polished electrochemically. The anchor structures are severed, and their remains are mechanically removed from the component.

Example 3

[0053] First, a raw metal component with auxiliary structures is additively manufactured on a building board. The raw metal component to be processed is composed of the component itself (Ti6Al4V), anchor structures (Ti6Al4V), auxiliary structures in the form of support structures (Ti6Al4V), a protective layer (Ti6Al4V) and a building board (Ti6Al4V). The building board is screwed on the rear side and contacted. In this case, it is not necessary to paint the building board. The auxiliary structure (support structure) is electrochemically treated/removed in a solution of 60% by volume of water, 40% by volume of H.sub.2SO.sub.4 and 33.3 g/l NH.sub.4HF.sub.2 by applying for a period of 30 to 240 minutes alternately a voltage of 5 V for 1 to 4 seconds and of 25 V for 1 second at 20° C. Furthermore, the component is polished by vibratory grinding. The anchor structures are severed, and their remains are mechanically removed from the component.