Method for manufacturing components layer by layer, manufacturing apparatus and computer program product

Abstract

The invention relates to a method for manufacturing components (5) layer by layer on a building platform (3) by local solidification of powdered material (9) in each layer (S) by means of at least one energy beam (8a, 8b), comprising the following steps: providing geometry data containing information about the geometry of individual layers (S) of the component (5) that is to be additively produced; and defining an irradiation pattern for the layers (S) by a computer-assisted manufacturing method, wherein: the irradiation pattern comprises, for each layer, a contour region (K) and an extensive region (F) preferably lying inside the contour region (K); the contour region (K) of each layer (S) consists of multiple irradiation vectors (V) lying next to one another; and the vectors (V) lying next to one another in the contour region (K) are exposed with different energy input parameters, such as line energy, energy output, exposure speed, energy beam diameter, power density and / or distance from the adjacent vector (V) in the contour region (K).

Description

[0001] Method for layer-by-layer production of components, production device and computer program product

[0002] Technical area

[0003] The invention relates to a method for the layer-by-layer production of components on a construction platform by local solidification of powdered material in a respective layer, a production device for producing at least one component layer-by-layer from a plurality of powder material layers of a powder material arranged in a layer sequence chronologically successively in a work area of ​​the production device by locally selective solidification of the powder material arranged in the work area and a computer program product.

[0004] Background of the Revelation

[0005] In additive manufacturing, e.g., selective laser sintering or selective laser melting, a powdered material, e.g., a metal or ceramic powder, is irradiated with electromagnetic radiation. Thin powder layers are successively applied in a chamber on a build platform to form three-dimensional components by irradiating the respective powder layers with an irradiation beam, e.g., a laser beam. Corresponding devices are referred to as additive manufacturing devices, 3D printing systems, selective laser sintering machines, or selective laser melting machines, and the like. For the functioning of such a device, see, for example, EP 2 732 890 A2.

[0006] In recent years, the additive manufacturing of components has also gained importance in industrial settings. Additive manufacturing in a powder bed (Powder Bed Fusion, PBF), in which thin layers of powder, e.g., made of metal, ceramic, or thermoplastic powder, are gradually applied and locally solidified with one or more beams to successively build up the component, is particularly suitable for the production of complex and delicate components. Machines suitable for performing a PBF process are referred to below as PBF machines. Lasers and electron beam systems are typically used as beam sources. When a laser source is used, the process is also referred to as Powder Bed Fusion - Laser Based (PBF-LB). The beam can sinter or melt the powder to solidify it, thereby bonding it to previously solidified component layers.Depending on the beam source, sintering is referred to as selective laser sintering or electron beam sintering, while melting is referred to as selective laser melting or electron beam melting. Powder-bed-based additive manufacturing of metal powder using a laser beam is also known as laser metal fusion.

[0007] Since the component is produced layer by layer, such an additive manufacturing process is relatively time-consuming. To reduce production time, multiple energy beams—for example, 2, 3, 4, 8, 12, or 16—are used instead of a single energy beam. A manufacturing device used in this process typically has at least one scanner device configured to shift the energy beams.

[0008] By using multiple energy beams, it is possible for a first energy beam to produce a first component in a work area of ​​the manufacturing device, while at the same time a second energy beam produces a second component in the work area.

[0009] With the layer-by-layer production of components through the local solidification of powdered material using high-energy beams (usually laser beams or electron beams), three-dimensional components can be manufactured comparatively easily and quickly. Geometric limitations of conventional manufacturing processes such as milling or injection molding can be overcome. Layer-by-layer production is often used for prototypes or for components that are only produced in small quantities. However, additive manufacturing is also already being used in series production. To accelerate the additive manufacturing of components, it is known to use several high-energy beams simultaneously to process the individual layers. The high-energy beams are directed onto the build platform using scanners; in the case of laser beams, the scanner can, for example, comprise a mirror that can be adjusted using piezo actuators.If several high-energy beams are used simultaneously, the processing task must be distributed among them.

[0010] US 2020 / 0238623 A1 describes a method for balancing capacity utilization and minimizing production time in additive manufacturing. A build platform on which multiple components are to be manufactured is processed with multiple lasers that have overlapping scan fields that can be reached by each laser. The allocation of regions to be manufactured to the lasers is iteratively optimized to achieve the shortest possible production time.

[0011] From WO 2016 / 075026 A1, it is known to assign a separate scanner to each section of a construction field, or to mount or design the scanners in such a way that they can also at least partially expose construction field sections that are actually assigned to another scanner, in order to assist this other scanner in exposing the construction field assigned to it. It is proposed to separately record and store the irradiation times or irradiation areas of each scanner, compare them with each other, and determine the distribution of the scanners' scan fields for the next layer or a next layer section in such a way that the irradiation times or irradiation areas for the scanners are as closely aligned as possible.

[0012] By dynamically adjusting the scan fields, high scanner utilization can be achieved and rapid processing of the layers and loading of the build platform as a whole can be achieved. However, a disadvantage is that the spatial deployment of the different high-energy beams on the build field or on the build platform can vary from layer to layer depending on the geometry and placement of the component(s) on the build field or on the build platform. In particular, high-energy beams can vary from layer to layer in a given component, or even multiple high-energy beams can be used for partial areas of the same component in the same layer, which can influence and, in particular, impair the quality of the manufactured components. With this approach, the quality of the manufactured components is therefore difficult to control.

[0013] If several components are to be manufactured in parallel on a build platform, the components are usually placed so that as many components as possible can be arranged on the build platform.

[0014] In methods for planning a locally selective irradiation of a work area with an energy beam in order to produce a component layer by layer from a plurality of powder material layers arranged sequentially in a layer sequence in the work area, a displacement of the energy beam along a contour line of the component to be produced in the respective powder material layer is typically specified for at least one powder material layer of the plurality of powder material layers. Such a displacement along the contour line, also referred to as contour tracking, requires a comparatively long, continuous irradiation, which can have negative effects on the buildability of overhang areas, particularly in overhang areas.Especially with flat overhang angles, especially less than 45° to the working area, process results that can be improved are obtained or even with a comparatively high probability of producing scrap.

[0015] Object of the invention

[0016] The object of the invention is to provide a method for the layered production of components on a construction platform, a production device for producing at least one component layer by layer from a plurality of powder material layers arranged in a sequence of layers in a work area of ​​the production device by locally selective solidification of the powder material arranged in the work area, and / or a computer program product with which the components can be produced quickly and with good quality in a simple manner. Summary of the Disclosure

[0017] The object is achieved by providing the present technical teaching, in particular the teaching of the independent claims as well as the preferred embodiments disclosed in the dependent claims and the description.

[0018] The object is achieved in particular by a method for the layer-by-layer production of components on a construction platform by local solidification of powdered material in a respective layer by means of at least one energy beam, comprising the following steps: providing geometric data with geometric information of individual layers of the component to be additively manufactured, defining an irradiation pattern for the layers by means of a computer-aided manufacturing process, wherein the irradiation pattern comprises a contour region and a surface region, preferably located within the contour region, in each layer, wherein the contour region of a respective layer consists of several adjacent vectors to be irradiated, and wherein the vectors adjacent to one another in the contour region are provided with different energy input parameters, such as line energy, energy output, exposure speed, energy beam diameter,Power density and / or distance to the neighboring vector in the contour area,

[0019] In particular, this prevents overheating of the powder material in the area of ​​the contour line or contour region. This results in improved buildability, particularly in overhang areas, especially in overhang areas with shallow overhang angles, especially less than 45° to a plane defined by the working area. In particular, heat dissipation in an overhang area is lower than in a core area due to the non-solidified powder material located at least partially underneath, so that overheating phenomena, particularly splashes, of a melt pool can easily occur in the overhang area, which can have a detrimental effect on component quality.The improved buildability, especially in overhang areas, also advantageously eliminates the need for support structures, saving both the powder material otherwise required for the construction of support structures and the processing time associated with the removal of support structures. This makes the process very cost-effective overall.

[0020] In the context of the present technical teaching, a contour line is understood to mean in particular an imaginary boundary line of the component to be produced in a respective powder material layer, that is to say in particular an imaginary boundary line or border of a cross-sectional area of ​​the component to be produced lying in the powder material layer.

[0021] Advantageously, the vectors lying next to each other in the contour area are illuminated in the direction of the component surface with decreasing beam diameter of the at least one energy beam.

[0022] Alternatively or additionally, the beam diameter of at least one energy beam decreases linearly in the contour area.

[0023] In one embodiment, the vectors in the contour area run parallel to the component surface.

[0024] Preferably, the vectors lying next to each other in the contour area are illuminated in the direction of the component surface with decreasing energy output of the at least one energy beam.

[0025] Advantageously, the vectors lying next to each other in the contour area are exposed in the direction of the component surface with increasing exposure speed of the at least one energy beam.

[0026] In one embodiment, the contour area of ​​a respective layer is exposed to exactly one energy beam.

[0027] Alternatively or additionally, the contour area has a width of 200 μm to 10 mm. In a further embodiment, the vectors superimposed in the contour area are exposed with different energy input parameters, such as line energy, energy output, exposure speed, energy beam diameter, power density, and / or distance to the neighboring vector in the contour area. "Superimposed" means that the vectors are located in different layers, i.e., in the previous layer or the subsequent layer. This is particularly common when a horizontal surface is to be printed on powder.

[0028] The object is also achieved by providing a manufacturing device for producing at least one component layer by layer from a plurality of powder material layers arranged sequentially in a layer sequence in a work area of ​​the manufacturing device, by locally selective solidification of the powder material arranged in the work area. The manufacturing device comprises at least one laser source configured to generate at least one energy beam, at least one scanner unit configured to displace the at least one energy beam in the work area, an application device for applying a powder material layer to the work area, and a control unit configured to carry out a method according to one of claims 1 to 9.

[0029] The object is further achieved by providing a computer program product which, when used on a manufacturing device for layer-by-layer production of components on a construction platform, carries out a method according to one of claims 1 to 9 by locally solidifying powdered material in a respective layer.

[0030] Further advantages of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further-described features can be used individually or in combinations according to the invention. The embodiments shown and described are not to be understood as an exhaustive list, but rather as examples for describing the invention. Brief Description of the Drawings

[0031] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure:

[0032] Fig. 1 shows a schematic longitudinal section of a manufacturing device for the layer-by-layer production of three-dimensional components for the invention;

[0033] Fig. 2 shows a schematic representation of a first embodiment of a method for layer-by-layer production of components on a construction platform by local solidification of powdered material in a respective layer by means of at least one energy beam; and

[0034] Fig. 3 shows a schematic representation of a second embodiment of a method for the layer-by-layer production of components on a construction platform by local solidification of powdered material in a respective layer by means of at least one energy beam.

[0035] Detailed description

[0036] The following is a detailed description of exemplary embodiments of the present disclosure. The exemplary embodiments described therein and illustrated in the drawings are intended to teach the principles of the present disclosure and to enable one of ordinary skill in the art to implement and use the present disclosure in many different environments and for many different applications. Therefore, the exemplary embodiments are not intended as a limiting description of the scope of patent protection and should not be viewed as such. Rather, the scope of patent protection is to be defined by the appended claims. Fig. 1 shows a schematic sectional view of a manufacturing device 1 for the layer-by-layer production of a plurality of components 5 on a build platform 3 for the invention.In particular, a method according to the invention for layered production of components 5 can be run on the production device 1, or a method according to the invention for planning layered production of components 5 can be run on a construction platform 3. For this purpose, a corresponding computer program product can be installed and used on the production device 1.

[0037] The manufacturing device 1 comprises a build chamber 2, in which an inert atmosphere (e.g., an N2 atmosphere or a noble gas atmosphere) is typically established. A build platform 3 is movable relative to a floor 4 of the build chamber 2 in a Z direction (height direction). The build platform 3 has a flat upper surface 3a aligned in the xy plane, on which several components 5 are manufactured.

[0038] For this purpose, a powdered material 9 (here a metal powder) is applied layer by layer to the build platform 3 using an application device or feeder 6. Using several scanners or scanner units 7a, 7b, several (high-)energy beams 8a, 8b (here laser beams) are directed at an uppermost layer 9a of the powdered material 9, which melt the powdered material 7 in selected regions of the uppermost layer 9a and fuse it to the build platform 3 and later to already manufactured parts of the components 5. This advances the production of the components 5. After the uppermost layer 9a has been completely processed, the build platform 3 is lowered by one layer height in the Z direction, a next layer of powdered material 9 is applied and processed with the high-energy beams 8a, 8b, and so on until the loading of the build platform 3 is completely processed.

[0039] The high-energy beams 8a, 8b are generated here with a common laser source 11, with an original laser beam being split between the two scanners 7a, 7b or the two high-energy beams 8a, 8b by means of a beam splitter 12. Alternatively, separate radiation sources can be provided for each high-energy beam (not shown in detail). The production device 1 has an electronic control device 13, which in particular controls the scanners 7a, 7b, the feeder 6, and the movement of the build platform 3 during the production of the components 5. The control device 13 is also programmed here to plan the arrangement of the components 5 to be used (to be manufactured) on the build platform 3 before production begins.

[0040] Fig. 2 shows a schematic representation of a first embodiment of a method for the layer-by-layer production of components 5 on a construction platform 3 by local solidification of powdered material 9 in a respective layer S by means of at least one energy beam 8a, 8b.

[0041] As can be seen from Fig. 2, a rectangular component 5 is built in this layer S on the rectangular build platform 3. In this embodiment, only contour-parallel vectors V are used for both the vectors V in the contour region K and the vectors V in the surface region F. This means that all vectors V run parallel to the component surface. In this embodiment, the contour region K consists of three adjacent vectors V. "Adjacent" here means parallel to one another.

[0042] Fig. 3 shows a schematic representation of a second embodiment of a method for the layer-by-layer production of components 5 on a construction platform 3 by local solidification of powdered material 9 in a respective layer S by means of at least one energy beam 8a, 8b.

[0043] As can be seen from Fig. 3, a rectangular component 5 is built in this layer S on the rectangular build platform 3. In this embodiment, contour-parallel vectors V are used for the vectors V in the contour region K, and parallel vectors that are not parallel to the component surface are used for the surface region F. Other exposure strategies are also conceivable for the surface region F. In this embodiment, the contour region K consists of three adjacent vectors V. "Adjacent" here means "parallel" to one another.

[0044] 1 manufacturing device

[0045] 2 construction chamber

[0046] 3 Construction platform

[0047] 3a Top of the build platform

[0048] 4 Floor of the build chamber

[0049] 5 Component

[0050] 6 Application device or feeder

[0051] 7a, 7b Scanner (unit)

[0052] 8a, 8b (High-)energy beams (here: laser beams)

[0053] 9 powdered material

[0054] 9a top layer of the powdered material

[0055] 11 Laser source

[0056] 12 beam splitters

[0057] 13 Control device

[0058] F Surface area

[0059] K Contour area

[0060] S layer / powder material layer

[0061] V Vector

[0062] X direction (in plane of the build platform)

[0063] Y direction (in plane of the build platform)

[0064] Z direction (perpendicular to the build platform), height direction

Claims

Claims 1. A method for the layer-by-layer production of components (5) on a construction platform (3) by local solidification of powdered material (9) in a respective layer (S) by means of at least one energy beam (8a, 8b), comprising the following steps: Providing geometry data with geometry information of individual layers (S) of the component to be additively manufactured (5), Defining an irradiation pattern for the layers (S) by means of a computer-aided manufacturing process, wherein the irradiation pattern comprises, layer by layer, a contour region (K) and a surface region (F), preferably located within the contour region (K), wherein the contour region (K) of a respective layer (S) consists of several adjacent vectors (V) to be irradiated, and wherein the vectors (V) lying next to one another in the contour region (K) are exposed with different energy input parameters, such as line energy, energy power, exposure speed, energy beam diameter, power density and / or distance to the adjacent vector (V) in the contour region (K).

2. Method according to claim 1, wherein the vectors (V) lying next to one another in the contour region (K) are exposed in the direction of the component surface with decreasing beam diameter of the at least one energy beam (8a, 8b).

3. Method according to claim 2, wherein the beam diameter of the at least one energy beam (8a, 8b) decreases linearly in the contour region (K).

4. Method according to one of claims 1 to 3, wherein the vectors (V) in the contour region (K) run parallel to the component surface.

5. Method according to one of claims 1 to 4, wherein the vectors (V) lying next to one another in the contour area (K) are aligned in the direction of the component surface with decreasing energy output of the at least one energy beam (8a, 8b).

6. Method according to one of claims 1 to 5, wherein the vectors (V) lying next to one another in the contour region (K) are exposed in the direction of the component surface with increasing exposure speed of the at least one energy beam (8a, 8b).

7. Method according to one of claims 1 to 6, wherein the contour region (K) of a respective layer (S) is exposed to exactly one energy beam (8a, 8b).

8. Method according to one of claims 1 to 7, wherein the contour region (K) has a width of 200 μm to 10 mm.

9. Method according to one of claims 1 to 8, wherein the vectors (V) lying one above the other in the contour area (K) are exposed with different energy input parameters, such as line energy, energy power, exposure speed, energy beam diameter, power density and / or distance to the adjacent vector (V) in the contour area (K).

10. Manufacturing device (1) for producing at least one component (5) layer by layer from a plurality of powder material layers (S) of a powder material (9) arranged in a layer sequence in a working area of ​​the manufacturing device (1) by locally selective solidification of the powder material (9) arranged in the working area, comprising at least one laser source (11) which is designed to generate at least one energy beam (8a, 8b), at least one scanner unit (7a, 7b) which is designed to displace the at least one energy beam (8a, 8b) in the working area, an application device (6) for applying a powder material layer to the working area, and a control unit (13) which is configured to carry out a method according to one of claims 1 to 9.

11. Computer program product which, when used on a system (1) for the layer-by-layer production of components (5) on a construction platform (3) by locally solidifying powdered material (9) in a respective layer, carries out a method according to one of claims 1 to 9.

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