Fluid-carrying component

Abstract

Fluid-carrying component (2) which is constructed in one piece in layers, has an overhang caused by a cavity and at least one support structure (10, 18) arranged below the overhang, which remains in the component (2) and extends in the direction of construction towards the overhang, further comprising a first hollow body (4) and a second hollow body (6) which merge into each other at least partially in an intersection area (8), wherein the support structure (10, 18) extends at least partially into the intersection area (8), wherein the at least one support structure (10, 18) has at least one first section (12, 20) with a first width (S1) measured transversely to the direction of construction and a second section (14, 22) with a second width (S2) measured transversely to the direction of construction directly at the overhang, where the second width (S2) exceeds the first width (S1) and where the ratio between a local overhang radius (R) and the second width (S2) is in a range of 0.75 - 2.25.

Description

TECHNICAL AREA

[0001] The invention relates to a fluid-carrying component that is constructed layer by layer in one piece. BACKGROUND OF THE INVENTION

[0002] Considerable effort is often made to reduce the weight of vehicle components, and especially aircraft components, to enable more economical vehicle operation by saving fuel. This extends to all types of components that can be integrated into a vehicle, including, for example, fluid-carrying piping systems or other hydraulic components.

[0003] For example, a method for manufacturing a hydraulic control block in metallic lightweight construction is known from DE 10 2006 062 373 A1, in which a system of circuit elements with load-adapted walls is designed, which are connected directly or with other elements to form a coherent structure and are all produced by an additive manufacturing process.

[0004] Furthermore, methods for manufacturing fluid-carrying components by layer-by-layer construction are known from DE 10 2012 008 369 A1 and DE 10 2012 008 371 A1.

[0005] WO 2012 / 131481 A1 relates to a component manufactured by additive manufacturing based on metal powder, wherein a metal powder forming a metal powder bed resting on a base element is selectively melted layer by layer, for example by selective laser melting, selective electron beam melting or selective ion beam melting.

[0006] US 2006 / 0003095 A1 describes devices and methods for producing deposits with a larger angle or overhang on a structure. Nozzles for applying powder to a target or structure for subsequent laser processing preferably have a larger powder entry angle than previously common. Furthermore, there is a method for temporarily supporting an overhang by using weaker material beneath the overhang. The weaker material can be removed after the overhang has been fabricated and cured.

[0007] EP 2 022 622 A1 relates to a method for manufacturing a component from solid freeform material, comprising the step of constructing an integral support around the component during its manufacture.

[0008] DE 10 2012 013 318 A1 describes a method for producing a three-dimensional object by solidifying build-up material layer by layer at the locations corresponding to the cross-section of the object to be produced in the respective layer by introducing energy using electromagnetic radiation.

[0009] The production of fluid-carrying piping systems using additive manufacturing processes such as SLM, SLS, or EBM results in perceptible surface roughness, even in overhang areas. This roughness arises from the selective melting of powder material during manufacturing, leading to a local increase in density. These locally denser areas in overhangs are supported only by an underlying powder bed, allowing the molten material to partially sink into the powder bed. This causes loose powder particles to adhere to these areas. For components with overhangs that are subjected to mechanical stress, particularly internal pressure, these manufacturing-related geometric deviations can lead to local stress concentrations, potentially resulting in local fatigue of the component.

[0010] It is known to improve surface roughness after additive manufacturing using mechanical and / or chemical abrasive processes. Another possibility is to support the locally melted areas during additive manufacturing. This includes temporary support structures that are removed after additive manufacturing. A further known support mechanism involves integrating webs that remain in the component after its production. However, this reduces the fluid-carrying cross-section and increases the structural stiffness in intersection areas. In components subjected to internal pressure, this generally leads to expansion restrictions between pipe connections in the relevant intersection area, which can result in stress concentrations. SUMMARY OF THE INVENTION

[0011] One object of the invention is to propose a fluid-carrying component that allows for the least possible influence of support structures on the component, wherein the manufactured component should have at least the same mechanical and physical properties as a component manufactured in other ways.

[0012] The problem is solved by a component having the features of independent claim 1. Advantageous embodiments and further developments are described in the dependent claims.

[0013] For better understanding of the invention, a method for manufacturing a fluid-carrying component with at least one overhang is also proposed, comprising one or more processing steps for the layer-by-layer construction of the component. The processing steps include at least the application of a layer section with predetermined dimensions of a particulate material in a predetermined area on a base layer and the heating of the layer section by means of a heat source such that the particles of the material bond together within predetermined dimensions.In this process, at least one support structure is constructed below a planned overhang, extending in the direction of construction towards the overhang, wherein the at least one support structure has at least a first section with a first width measured transversely to the direction of construction and a second section with a second width measured transversely to the direction of construction directly at the overhang, wherein the ratio between a local overhang radius and the second width is in a range of 0.75 - 2.25.

[0014] The base layer can be understood as a layer that is present before each subsequent layer is applied. At the beginning of the process, the base layer can, for example, be implemented as a supporting structure made of several layers of meltable or sinterable material. All subsequent material layers applied on top of this form the base layer for each subsequent layer.

[0015] An overhang is defined as a portion of a layer segment under which the directly underlying layer segment does not extend and consequently does not support the layer segment above it—provided there is no underlying support structure. In the direction of construction, this results in an offset extending over a free area. A first layer segment may, for example, have a recess over which a second layer segment partially extends. The overhang radius is considered a radius of curvature of the overhang, which could be, for instance, a concave slab curvature radius present in the area of ​​the support structure within the interior space of the component created by the layered construction.

[0016] The support structure is defined by its profile cross-section. The actual support structure preferably follows the continuous course of overhangs perpendicular to the assembly direction within the component, thus forming a predominantly web-like structure. It is of course possible that, depending on the size or number of overhangs, multiple support structures may be advantageous to improve manufacturing quality.

[0017] The first width can be significantly smaller than the second width and is preferably selected based on the properties of the powdered material and tailored to the manufacturing process. This ensures that the first support structure section is as fine as possible, providing sufficient inherent stability during assembly and preventing damage or destruction during the process. The second section, on the other hand, depends solely on a characteristic geometric dimension of the overhang, for which the overhang radius is particularly suitable.

[0018] As defined above, the second width, measured at a point directly adjacent to the overhang, is to be selected from a range that has a ratio to the local overhang radius, which is to be selected from a range of 0.75 - 2.25: RS2=0.75…2.25

[0019] "R" is to be understood as the local overhang radius, while "S2" represents the second width, as used in the subsequent figure description. If the component is, for example, a pipeline whose intended flow direction is approximately perpendicular to the installation direction, the pipeline radius corresponds to the local overhang radius.

[0020] The method for manufacturing fluid-carrying components thus makes it possible to achieve the least possible influence on the flow cross-section, while simultaneously minimizing expansion restrictions through the most slender possible design of the support structure. This is particularly advantageous for support structures projecting into a so-called intersection zone, where a first hollow body and a second hollow body merge into each other, at least partially.

[0021] In summary, a key aspect of the invention lies in supporting a fluid-carrying component with an overhang caused by a cavity during the additive manufacturing process. This overhang is supported by a support structure remaining within the component. The support structure extends in the build direction from a partially closed layer located beneath the overhang, opposite to the build direction, to the overhang being supported. By using a first width and a second width in the support structure, the fluid-mechanical influence on the fluid-carrying component can be reduced, as only a small section directly in contact with the overhang needs to have the larger second width. The first section with the first width serves to provide sufficient support for the second section during the manufacturing process and should be as narrow as possible.The resulting influence on the expansion behavior of the component to be manufactured is therefore particularly low.

[0022] The support structure can have a transition zone between the first section of first width and the second section of second width, in which the width increases successively in the build-up direction from a transition point, i.e., from the first width to the second width. This increase in width in the build-up direction is preferably implemented taking into account a limited build-up angle of the transition zone, according to the properties of the powdered material and the manufacturing process.

[0023] In an advantageous embodiment, the support structure has a transition zone from the first width to the second width, wherein two successive layers are dimensioned such that a local initial build-up angle of 50° is not exceeded. The connecting line of layer edges of successive layers thus results in an angle measurable with respect to the build-up direction, which can be considered the build-up angle. The transition zone can therefore have flanks that exhibit a local angle of at most 45° with respect to the build-up direction. Consequently, a relatively rapid widening of the support structure can occur, thus minimizing the influence on the strain behavior.The initial build-up angle can actually be slightly greater than 45°, depending on the specific material properties of the powdered material, so that high surface roughness in this area can be avoided and increased material stresses do not result in the transition area or directly between the support structure and the overhangs to be supported.

[0024] In a particularly advantageous embodiment, the first angle of inclination increases successively in the transition area, resulting in a rounded support structure with a particularly favorable distribution of mechanical stresses. For example, the design of the edge surfaces of the transition area can be equipped with a constant curvature that merges tangentially into the edge surface of the first section and exhibits a particularly small angle to the tangent directly adjacent to the overhangs to be supported. This allows for a particularly advantageous reduction of stress concentrations.

[0025] Furthermore, it is particularly advantageous if the support structure has a rib-like section whose width is constant and corresponds to the first width. The first width could be at least 0.2 mm. This results in a particularly low impact on the flow cross-section of the relevant section of the component being manufactured.

[0026] In an advantageous embodiment of the method, a first hollow body and a second hollow body are constructed, which at least partially merge into one another in an intersection area. At least the first section of the support structure has an end surface projecting into the intersection area, forming an angle other than 0° to the construction direction. This angle could result from the material properties of the particulate material and, for example, be in a range of up to 60°, and preferably always at least 45°. The particular advantage lies in the increased strain compatibility between the intersecting hollow bodies. As a consequence, stress concentrations in this intersection area are significantly reduced, and the load-bearing capacity of the component in the area of ​​the interconnected hollow bodies is increased.

[0027] This is particularly advantageous when a first hollow body extends perpendicular to the assembly direction and a second hollow body extends at least partially parallel to the assembly direction. This can therefore apply in particular to the inlets of pipe connections or the like into a collection chamber, a distributor, or a larger pipeline.

[0028] In an advantageous embodiment of the invention, the particulate material is a metallic material. This allows the production of components with high strength and, in particular, compressive strength, for example, for use in hydraulic systems. To achieve a particularly low weight, lightweight metal alloys such as AlSi10Mg or TiAl6V4 are suitable. Subsequent heat treatment to homogenize the metal microstructure further improves the material properties significantly.

[0029] Additionally, the particulate material can be a ceramic material, for example zirconium oxide (ZrO2) or aluminum oxide (Al2O3). The compressive strength is comparable to that of components made from metallic particles, with the advantages of the ceramic material lying particularly in its significantly reduced weight.

[0030] In an advantageous embodiment, after completion of the layer-by-layer build-up, the manufactured component is heat-treated in a heat treatment device. This allows the microstructure of the manufactured component to be influenced so that it is uniform over the entire spatial extent of the component, thus eliminating stresses that arose during the manufacturing process. This can include, for example, heating to a target temperature, maintaining a target temperature, and controlled temperature reduction.

[0031] In an advantageous embodiment, the manufactured body undergoes machining on its outer surface. In particular, machining connecting surfaces, which are implemented in the form of flanges, can ensure the dimensional accuracy of the entire component. For example, the machining can include grinding, drilling, polishing, or other common machining methods.

[0032] The fluid-carrying component according to the invention can be manufactured by the method described above. The component is built up in one piece, layer by layer, has an overhang and at least one support structure arranged below the overhang, which extends in the build direction to the overhang, wherein the at least one support structure has at least a first section with a first width measured transversely to the build direction and a second section with a second width measured transversely to the build direction directly at the overhang, wherein the second width exceeds the first width and wherein the quotient of a local overhang radius and the second width lies in the range of 0.75 - 2.25.

[0033] In an advantageous embodiment, the support structure is designed such that the first section is web-like and has a constant first width. In a further advantageous embodiment, the first width is at least 0.2 mm.

[0034] As previously described, the component has a first hollow body and a second hollow body which merge into each other at least partially in an intersection area, with the support structure projecting at least partially into the intersection area.

[0035] Furthermore, at least the first section of the support structure can have an end surface projecting into the intersection area, which forms a non-zero angle, and preferably an angle of 50° or less, with an intersection plane. The intersection plane can thus be considered, for example, as an opening plane of the first or second hollow body, which is an intersection surface between the first and the second hollow body. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further features, advantages, and applications of the present invention will become apparent from the following description of the exemplary embodiments and the figures. All features described and / or illustrated, individually and in any combination, constitute the subject matter of the invention, irrespective of their composition in the individual claims or their cross-references. In the figures, the same reference numerals denote identical or similar objects. Fig. Figure 1 shows a component manufactured using an additive manufacturing process, comprising two hollow bodies and an intersection area. Fig. Figure 2 shows the support structure in a detailed profile view. Fig. Figure 3 shows a support structure in an intersection area with a second construction angle. DETAILED DESCRIPTION OF EXEMPLARY EXECUTION FORMS

[0037] Fig. Figure 1 shows a fluid-carrying component 2, manufactured using an additive manufacturing process, in a side sectional view. The component 2 includes, by way of example, a first hollow body 4 as a subsection of the component 2, which has a closed flow cross-section whose flow direction is at least partially perpendicular to a build direction. This direction is opposite to the direction of the acceleration due to gravity, which is denoted by "G".

[0038] A second hollow body 6, as a further subsection of component 2, which also has a closed flow cross-section, extends transversely to the assembly direction and merges with the first hollow body 4 in an intersection area 8. Due to the flow cross-section running transversely to the assembly direction, circumferential edges of the powdered material initially move away from each other during assembly, in order to then converge again from about half the height in the case of a circular cross-section.

[0039] To merge the circumferential contour of a flow cross-section in the build-up direction, the clear distance between two opposing edges is reduced layer by layer, with an overhang becoming increasingly pronounced under each layer up to an upper apex of the second hollow body 6. In the area with the strongest overhangs, a support structure 10 is built up, which prevents locally melted material from sinking into the underlying powder bed.

[0040] The support structure has a first section 12, to which a second section 14 is attached, which runs flush into an upper apex of the second cavity 6, as further shown by Fig. 2 shown.

[0041] In Fig. Figure 2 shows a lateral sectional view of the support structure 10 in the second hollow body 6. This structure is characterized by the fact that the first section 12 is designed as a web and is produced parallel to the build direction with an unchanged layer width. Thus, a web with a first width s1 is produced, which should be selected to be as small as possible in order to minimize its influence on the flow behavior in the resulting component 2 and its expansion behavior, particularly in transition regions between different cavities. For metallic or ceramic powder materials, narrow first sections 12 with a width of approximately 0.2 mm are quite conceivable.

[0042] The second section 14 is located in an area where the flowable cross-section of the second hollow body 6 is closed, so that the second section 14 connects directly to the top surface of the flowable cross-section. The largest local overhangs are expected there, so support is provided there.

[0043] This second section 14 is characterized by its maximum second width S2, which exceeds the first width S1 of the first section 12. A transition zone 16 is formed in which there is a continuous transition from the first width S1 to the maximum second width S2, thus providing a sufficient support area for an upper cross-sectional region of the second cavity 6 through which the flow passes. The maximum width S2 of the second section 14 depends on the prominence of the overhang, which in the illustrated case can be characterized as a local overhang radius R, a radius of curvature in the area of ​​the support structure. In this case, the overhang radius corresponds to the radius of the circular cross-sectional area of ​​the second cavity 6.

[0044] The maximum second width S2 depends on the overhang radius. The quotient of the overhang radius R and the second width S2 lies in a range of 0.75 to 2.25, as shown in the preceding equation: RS2=0.75…2.25 steund prefers 0.75 to 2.25 times the radius R, with the second width S2 in the example shown being closer to the lower limit of this range.

[0045] The transition area 16 between the first width s1 and the maximum second width S2 further exhibits a first build-up angle α of 40° or more to the build-up direction in a perpendicular cross-sectional surface of the component 2, so that the second section 14 has a profile that widens wedge-shaped in the build-up direction, the flanks of which have an angle of 50° or less, preferably 45°, to the horizontal. The support structure 10 thus only has a wide bearing surface for supporting the material at its upper end.

[0046] As shown in the detailed illustrations I and II, which refer to a section A between the location of maximum second width S2 and an inner surface 17, in addition to a purely wedge-shaped design (I), a gentler taper can also be chosen, as shown with tangents T1 and T2 that become shallower in the construction direction. This allows notch stresses to be reduced.

[0047] If, during the manufacture of a fluid-carrying component 2, two hollow bodies 4 and 6 are joined together, the process can be carried out as described in Fig. As already shown in Figure 1, a support structure 10 is arranged there, which is adapted to minimize the change in the strain properties. A modification is shown in Figure 1. Fig. 3 in the form of a support structure 18 in a three-dimensional sectional view, wherein a section shown on the right in the drawing plane passes through the extension plane of the support structure 18.

[0048] To minimize the influence on the expansion behavior, the support structure 18 has an end surface 19 projecting into the intersection area 8, which forms an angle of 50° or less to the assembly direction. This requires a second assembly angle β, which consequently results in a support structure 18 positioned in the flow direction within the first hollow body 6, and which also has a second section 22 at its upper end in the assembly direction, the width of which exceeds that of an underlying first section 20.

[0049] The stiffness of the support structure is thus significantly reduced in a transition zone to the first, larger hollow body 4. Accordingly, the support structure is not limited by the cross-sectional area located in the intersection zone 8, but rather it extends continuously into this zone by means of the second angle of inclination β. It should be noted here that the support structure 18 does not necessarily have to extend linearly into the intersection zone 8, but can also have a non-zero curvature or a curvature profile in order to optimize the strain or load distribution.

[0050] It should be further noted that "having" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. It should also be noted that features described with reference to one of the above embodiments may also be used in combination with other features of other embodiments described above. Reference numerals in the claims are not to be considered as a limitation.

Claims

[1] Fluid-carrying component (2) which is constructed in one piece in layers, has an overhang caused by a cavity and at least one support structure (10, 18) arranged below the overhang, which remains in the component (2) and extends in the direction of construction towards the overhang, further comprising a first hollow body (4) and a second hollow body (6) which merge into each other at least partially in an intersection area (8), wherein the support structure (10, 18) extends at least partially into the intersection area (8), wherein the at least one support structure (10, 18) has at least one first section (12, 20) with a first width (S1) measured transversely to the direction of construction and a second section (14, 22) with a second width (S2) measured transversely to the direction of construction directly at the overhang, where the second width (S2) exceeds the first width (S1) and where the ratio between a local overhang radius (R) and the second width (S2) is in a range of 0.75 - 2.

25. [2] Fluid-carrying component (2) according to claim 1, wherein the support structure (10, 18) is constructed such that the first section (12, 20) is web-like and has a constant first width (S1). [3] Fluid-carrying component (2) according to claim 2, wherein the first width (S1) is at least 0.2 mm. [4] Fluid-carrying component (2) according to one of claims 1 to 3, wherein at least the first section (12, 20) of the support structure (10, 18) has an end surface (19) projecting into the intersection area (8) which forms a non-zero angle to an intersection plane.

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