Method of additively manufacturing a structure on a pre-existing component out of the powder bed

Abstract

A method of additive manufacturing a structure on a pre-existing includes disposing the pre-existing component in a bed of powdery base material and levelling the component, such that a manufacturing plane of the component can be recoated with the base material and alternatingly recoating and irradiating the manufacturing plane with an energy beam in order to additively build up the structure, wherein the irradiation is carried out in that the manufacturing plane is scanned by the beam in a non-continuous way, wherein, for the irradiation according to a second vector for the structure, the beam is either only guided parallel with respect to a previous first vector, or the irradiation process is paused after the irradiation of the first vector for a time span between 1/10 second to 2 seconds until the irradiation is continued with the second vector.

Claims

1. A method of additive manufacturing a structure on a pre-existing component, comprising: disposing the pre-existing component in a bed of powdery base material and levelling the component, such that a manufacturing plane of the component can be recoated with the base material, alternatingly recoating and irradiating the manufacturing plane with an energy beam in order to additively build up the structure, wherein the irradiation is carried out in that the manufacturing plane is scanned by the beam in a non-continuous way, wherein, for the irradiation according to a second vector for the structure, the beam is either only guided parallel with respect to a previous first vector, or the irradiation process is paused after the irradiation of the first vector for a time span between 1/10 second to 2 seconds until the irradiation is continued with the second vector.

2. The method according to claim 1, wherein, for the irradiation according to the second vector for the structure, the beam is not guided in a direction anti-parallel to the first vector.

3. The method according to claim 1, wherein the beam is scanned over the manufacturing plane in a lined, non-meander-like fashion.

4. The method according to claim 1, wherein the pre-existing component comprises a crystalline structure, and wherein irradiation parameters are chosen such that the structure is established in a crystalline, columnar or dendritic crystalline texture, as well.

5. The method according to claim 1, wherein the additive manufacturing comprises a selective laser melting, selective laser sintering and/or electron beam melting method.

6. The method according to claim 1, wherein the additive manufacturing comprises a repair process, wherein the structure is a refurbishment structure.

7. An apparatus for the additive manufacture of a structure from a powder bed, comprising: a substrate and a radiation source capable of generating a beam pattern, the apparatus being configured such that a manufacturing plane on the substrate can selectively be irradiated with at least one energy beam in order to additively build up the structure on the substrate, wherein the substrate is displaceable with respect to the beam pattern only by mechanical means, or a gantry system, wherein the radiation source is configured to generate a row-type beam pattern of a plurality of energy beams such that the plurality of energy beams are parallel, and wherein the apparatus is set up to displace the substrate in a direction transverse to a row direction.

8. The method according to claim 4, wherein the pre-existing component comprises a single crystalline structure.

9. The method according to claim 4, wherein the irradiation parameters are chosen such that the structure is established in a single, crystalline, columnar or dendritic crystalline texture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features, expediencies and advantageous refinements become apparent from the following description of the exemplary embodiment in connection with the Figures.

(2) FIG. 1 shows a schematic perspective view of an additive manufacturing process of the prior art.

(3) FIG. 2 shows a schematic perspective view of an additive manufacture of a structure on top of a pre-existing component out of the powder bed according to the present invention.

(4) FIG. 3 shows a schematic perspective view of an apparatus according to the present invention.

(5) FIG. 4 shows a schematic flow chart of method steps of the present invention.

DETAILED DESCRIPTION OF INVENTION

(6) Like elements, elements of the same kind and identically acting elements may be provided with the same reference numerals in the Figures.

(7) FIG. 1 shows an article or a part 10. The part 10 is actually being manufactured additively out of the powder bed 3 in that said powder is solidified by an energy beam 4. The energy beam 4 may be a laser beam. The energy beam 4 is advantageously generated by a radiation source 21. By means of the scanner 11 or according optics, the energy beam may, e.g. be moved over the powder bed 3 in a meander-like fashion, as shown and indicated by the arrow in FIG. 1.

(8) The presented method as shown in FIG. 1 describes a conventional way of irradiating a powder bed. Each line, section or part of the trajectory of the beam 4 over the powder bed may be described by vectors which define or compose said meander. After a single layer of base material 3 has been solidified, a base or a support, carrying the part 10 is usually lowered by a distance corresponding to the layer thickness.

(9) According to this conventional approach, e.g. after having guided the energy beam 4 in the first horizontal line, the energy beam is only marginally guided downwards, in order to “meander back” towards the beginning or in a direction anti-parallel to the first vector. Thereby, parts of the first irradiated lines, or vector(s) become again exposed to the heat of the energy beam 4, i.e. for a second time in a short time span. Thus, a melt pool (not explicitly indicated in FIG. 1; cf. numeral MP in FIG. 2) is moved again towards regions which have recently been melted. This provides adverse structural defects or poor crystallinity for the structure to be established, as the structure may be remelted (again) after it has once been solidified. This particularly prevents the structure from being established according to the same crystallinity as an underlying layer, for example.

(10) FIG. 2 illustrates the situation comparable to the one as shown in FIG. 1 wherein, however, a structure 1 which has newly to be manufactured, on top of the pre-existing component 2, is established out of the powder bed 3 according to the inventive method. The component 2 and the structure 1 may then, when completely be manufactured, represent a refurbished article 10.

(11) After the pre-existing component 2 having been disposed or arranged in the powder bed 3 (cf. step a) in FIG. 4), the component 2, or as the case may be a manufacturing plane MP thereof, has to be leveled (cf. step b) in FIG. 4) such that the manufacturing plane of the component can be recoated with the base material 3 and/or irradiated with the energy beam 4 (cf. step c) in FIG. 4).

(12) According to the present invention, the irradiation is carried out in that the different vectors for the structure 1 are scanned by the laser beam 4 in a non-continuous and/or row-type fashion, e.g. according to the way of reading the lines of the book from left to right or vice versa.

(13) In the present embodiment, the energy beam 4 is advantageously guided from left to right over the powder bed 3, as indicated by the arrows or vectors in FIG. 2. The top line, stripe or trajectory represents vector V1.

(14) A subsequent vector according to which the base material 3 is to be irradiated or scanned afterwards is denoted with vector V2. In contrast to FIG. 1, after having scanned the first line or vector V1, irradiation is interrupted and the laser beam 4 is advantageously moved to the left side of the part in order to scan vector V2 in the same manner as vector V1. Therefore, the pre-existing component 2 or support carrying the same may be moved, e.g. to the left. Alternatively, an energy source 21 may be moved, e.g. to the right.

(15) In an alternative embodiment, e.g. vector V2 may be scanned from right to left, i.e. anti-parallel with respect to vector V1. However, in this case, the irradiation has to be timely paused for a time span of e.g. a tenth of a second to 2 seconds, such that heat, provided from the energy beam to the powder bed may already have been dissipated until the energy beam 4 and therewith a melt pool MP, which may extend over various vectors, is moved again through already solidified regions.

(16) Thus, the non-continuous, i.e. timely paused scan/irradiation direction of vectors provides as well for the inventive advantages, i.e. the establishment of the structure with a crystalline texture as the one of the pre-existing component.

(17) FIG. 3 shows an apparatus 20 according to the present invention. The apparatus 20 comprises a gantry system or radiation source 21. The radiation source 21 comprises a plurality of laser emitters and/or laser beams 4. The radiation source 21 is capable of providing a row-type beam pattern 22. The radiation source 21 may be or comprise a laser bar. Reference numeral 21 may be a gantry.

(18) The apparatus 20 further comprises a support or substrate 5. The substrate 5 is advantageously horizontally displaceable with respect to the beam pattern 22, viz. in a direction orthogonal to the row direction of the beam pattern 22. This is indicated by the arrow shown below in FIG. 3.

(19) It is further indicated in FIG. 3 that—for the manufacturing of the structure 1 or for refurbishing of part 10 along with the inventive advantages, the whole row of energy beams may be moved simultaneously and relatively to the support (either by movement of the support relative to the radiation source 21 or vice versa).

(20) Thereby, expensive optics or scanners for moving the energy beam, as is usual in SLM process, may be dispensed.

(21) The scope of protection of the invention is not limited to the examples given hereinabove. The invention is embodied in each novel characteristic and each combination of characteristics, which particularly includes every combination of any features which are stated in the claims, even if this feature or this combination of features is not explicitly stated in the claims or in the examples.