Method for producing a workpiece using a beam-melting method, and workpiece

Abstract

The invention relates to a method for producing a workpiece using a beam-melting method, comprising the following steps: applying (10) a layer of melting material; carrying out a first exposure (12) of the layer of melting material, controlled by first control data which define a first ply (41) of the workpiece; after the first exposure, applying (14) a further layer of melting material; carrying out an exposure (16) of the further layer of melting material, controlled by second control data which define a second ply (42) of the workpiece, wherein the first control data are defined in such a way that the first ply (41) of the workpiece has a first structuring (31) in a first region (21) and a second structuring (32) in a second region (22); and wherein the second control data are defined in such a way that the second ply (42) of the workpiece has the second structuring (32) or a third structuring (33) in the first region (21), and the first structuring (31) or the third structuring (33) in the second region (22), wherein the first region (21) is different from the second region (22), and wherein the first structuring (31) is different from the second structuring (32), or wherein the third structuring (33) is different from the first structuring (31) and the second structuring (32).

Description

[0001] Method for producing a workpiece using a beam melting process and workpiece

[0002] Description

[0003] The present invention relates to the production of workpieces using a beam melting process, such as the SLM process or selective laser melting, and further to workpieces produced by such a process, which may be implemented, for example, as heat exchangers or other elements with repeating structures.

[0004] DE102021201532A1 discloses a heat exchanger with a first number of channels for a first fluid, extending along a first flow direction of the first fluid and in a first transverse direction, wherein the first transverse direction varies along the first flow direction, a second number of channels for a second fluid, extending along a second flow direction of the second fluid and in a second transverse direction, wherein the second transverse direction varies along the second flow direction, and a wall structure configured such that the first number of channels and the second number of channels are in thermal interaction.and that at a first point in the heat exchanger, with respect to the first or second flow direction, the first transverse direction or the second transverse direction is different from a first or second transverse direction at a second point in the heat exchanger with respect to the first or second flow direction.

[0005] Such a heat exchanger is manufactured, for example, using the selective laser melting (SLM) process. Selective laser melting, also known as laser beam melting or powder bed fusion (PBF-LB / M), is an additive manufacturing process belonging to the group of beam melting processes. Similar processes include electron beam melting and selective laser sintering.

[0006] The air-to-air heat exchanger described in DE102021201532A1 can be manufactured using the jet melting process.

[0007] In the selective laser melting (SLM) process, the material to be processed is applied in powder form as a thin layer onto a base plate. The powdered material is locally and completely melted by laser radiation, forming a solid layer after solidification. The base plate is then lowered by the thickness of one layer, and more powder is applied. This cycle is repeated until all layers have been melted. The finished component is cleaned of excess powder, machined as needed, or used immediately.

[0008] The typical layer thicknesses for building the component range from 15 to 500 pm. The data for guiding the laser beam, or the control data, are generated from a 3D CAD model using software. In the first calculation step, the component is divided into individual layers. In the second calculation step, the paths (vectors) that the laser beam traces are generated for each layer. To prevent contamination of the material with oxygen, the process preferably takes place under a protective gas atmosphere of argon or nitrogen.

[0009] Components manufactured by selective laser melting are characterized by high specific densities (< 99%). This ensures that the mechanical properties of the additively manufactured component largely correspond to those of the base material. However, it is also possible to manufacture components with selective densities in a targeted manner, for example, according to bionic principles or to ensure a specific modulus of elasticity. Compared to conventional processes, such as casting, laser melting is distinguished by the fact that tools or molds are not required, thus achieving formless manufacturing and reducing time to market. Another advantage is the high degree of geometric freedom, which enables the production of component shapes that are impossible or only achievable with great difficulty using mold-based processes.Regarding the exposure strategy, the higher the laser power, the greater the resulting surface roughness of the component. Segmented exposure specifically targets the outer areas of the component, overhangs, and high-density areas.

[0010] Laser melting processes have various names, such as “Selective Laser Melting (SLM)” or “Laser Powder Bed Fusion (LPBF)”, “Direct Metal Laser Sintering (DM LS)”, “Laser Cusing”, “Laser Metal Fusion”, “Direct Metal Printing” or “Laser-Based Powder Bed Fusion of Metals (PBF-LBM)”.

[0011] The air-to-air heat exchanger described in DE102021201532A1 has a typical main operating direction or flow direction, defined by the fact that the first fluid moves through the workpiece in the direction of flow, while the second fluid moves through the component or workpiece in the opposite direction to the main operating direction, following a counterflow principle. A typical manufacturing process using a beam melting process involves applying the material layer by layer, with each layer having the same structure throughout. To achieve the characteristic "rotations" of the structures described in DE102021201532A1, the structure is slightly modified from layer to layer, resulting in alternating horizontal and vertically separated channel arrays. This leads to a particularly high heat exchanger efficiency.In this process, the layer structures change in a sequence of layers with a period, where one period comprises, for example, 150 layers. After one period, the layer to be exposed is the same as the layer at the beginning of the period, and, for example, nine layers can be specified along a period spanning 360°, exposed at angles of 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, and 360° of the period.

[0012] Significant efficiency losses have resulted from manufacturing air-to-air heat exchangers in such a way that the normal vector of a layer of powdered melting material is parallel to or identical with the main flow direction or the main functional direction of the heat exchanger. Since the heat exchangers have a considerable shape, such as a cube with an edge length of 20 cm, a large number of layers are required to create this structure, which also has a considerable lateral extent, meaning a considerable surface area for a single layer.It has been found that, especially with fine structuring, the thermal stress from layer to layer becomes so great that when a layer has been exposed which includes a structuring that extends over a large section of the layer and perhaps even over the entire layer in one or both dimensions, a high stress is created which causes the layer to become misshapen as it cools or to remain under stress and later crack.Furthermore, it has been shown that the immediate application of another layer with a relatively similar structure, as occurs in the heat exchanger with "rotating" walls, again introduces energy at the same location, which then again affects a wall structure that extends over a large area of ​​the layer, so that a large amount of energy is again generated at almost the same location, which will again lead to significant stresses during cooling.

[0013] This results in the individual layers either warping against each other during cooling or even during melting, or developing such high stresses against each other that cracks occur at some point during the manufacturing process, causing a short circuit between the channels for one fluid and the channels for the other fluid, leading to a significant reduction in the efficiency of the heat exchanger or rendering it completely unusable.

[0014] One way to address this situation is to increase the structural thickness. However, this has disadvantages in terms of volume, material consumption, and the efficiency of the heat exchange process. Furthermore, increased material or layer thicknesses increase the overall weight of the heat exchanger, which is already quite heavy, especially when made from sintered metal powder.

[0015] DE 10 2007 014 683 A1 discloses a method for producing a three-dimensional object by successively strengthening layers of a layer material on an area corresponding to the cross-section of the object in the respective layer, wherein at least a sub-area of ​​a layer is strengthened in such a way that a pattern with a plurality of substantially parallel strengthening lines (V, S) is created, and at least a sub-area of ​​a subsequent layer is irradiated in such a way that a pattern with a plurality of substantially parallel strengthening lines (V, S) is created, which are rotated relative to the strengthening lines of the pattern of the preceding layer by an angle (a) that varies between 180°, 90° and 45°. In particular, a laser beam is guided over the layer in a filling area within a contour that defines the outline of the object in a plurality of parallel vectors, thereby solidifying the powder.In a variation, instead of exposing the entire layer with continuous stripes, only certain areas are exposed, with the stripes of adjacent areas already having an angle, usually 90°. For example, exposure in the manner of a checkerboard pattern is conceivable. In the subsequent layer, the direction of all stripes for each area is rotated by an angle.

[0016] WO 2004 / 056 509 A1 discloses an arrangement and a method for producing three-dimensional bodies by successively fusing selected areas of a powder bed, wherein these parts correspond to successive cross-sections of the three-dimensional body, the method comprising the following process steps: applying layers of powder to a worktable, supplying energy from a radiation gun according to an operating scheme determined for the powder layer to the selected area within the powder layer, fusing the area of ​​the powder layer selected according to the operating scheme to form a cross-section of the three-dimensional body, wherein a three-dimensional body is formed by successively fusing cross-sections formed successively from successively applied layers of powder.

[0017] The object of the present invention is to create an improved concept for manufacturing a workpiece.

[0018] This problem is solved by a method for producing a workpiece using a beam melting process according to claim 1 or a workpiece according to claim 23.

[0019] The present invention is based on the realization that it is necessary to depart from the typical manufacturing method in which the main functional direction coincides with the melting direction, thus achieving structures within a layer that are uniform across the entire layer. Instead, in order to reduce the structuring lengths within a layer, at least on average, a "diagonal" manufacturing process is employed. In this process, the main functional direction of the workpiece deviates from the normal vector of a layer of melt material by an angle that is at least greater than 2° and preferably less than 30°.While in the known method, which results in problematic production yields, the angle between the normal vector and the main functional direction is 0°, in the present invention this angle is at least 2° and preferably less than 30°. Particularly preferably the angle has values ​​greater than 2° and less than 10°. Furthermore, angles between 3° and 6° have proven particularly successful, and angles between 3.8° and 4.8°, and especially at 4.3°, have proven particularly advantageous.

[0020] Even if the slant angle is only small, such a small angular deviation, especially with layer dimensions of, for example, 20 cm x 20 cm, and due to the relatively small layer thicknesses of between 50 and 100 pm per layer, means that the number of exposures required to create the necessary structure extending perpendicular to the main functional direction is no longer a specific number n of layer-wise manufacturing or exposure processes, but rather a significantly higher number of exposure processes, for example, 100 or 200 layers more. In return, each individual layer has a smaller average dimension. This, in turn, leads to a decrease in stresses in the material during cooling due to the reduced expansion, so that no stress cracks or similar issues, such as significant deformation, occur.According to the invention, in the novel manufacturing of a workpiece using a beam melting process according to the prior art, one layer after the other is applied and exposed. However, the control data are defined such that the layers, as exposed, are no longer homogeneous but heterogeneous. This is expressed by the fact that the first layer of the workpiece has a first structure in a first region and a second structure in a second region, and that a second layer of the workpiece has the second structure or a further structure in the first region and the first structure or yet another structure in the second region. The regions within a layer differ, but are essentially the same from layer to layer, and the structures differ from one another.

[0021] While in the state of the art a layer as it is exposed typically has a single structure, according to the invention this homogeneity is “broken up” by producing the workpiece “obliquely”, i.e. the control data in a layer define structures in a certain area that differ from the structure in another area of ​​the same layer, which, however, due to the periodic structure of the workpiece in one area, take place in a later layer.

[0022] In other words, in the inclined manufacturing process according to the invention, a layer contains structurings of several imaginary layers in different areas, whereby these imaginary layers would occur in the classical non-inclined manufacturing process.

[0023] This results in inhomogeneous structures, meaning that, on average, structures no longer extend across the entire layer thickness, but only over a smaller area. Consequently, a certain number of additional layers are required compared to conventional manufacturing methods. However, this apparent disadvantage is readily offset by the significant increase in yield, and the production of certain workpieces with such structures using a beam melting process is only made possible by the inclined manufacturing method according to the invention.

[0024] This applies particularly to structures that are similar along the main functional direction, i.e., that repeat within a specific period. In exemplary embodiments, the structurings—that is, the first, the second, possibly the third, and further structurings—represent functional structures of the workpiece, such as wall structures of fluid channels for liquids or gases, which define the workpiece or are formed within it. Such functional structures define the functionality of the workpiece and are not merely present due to a specific manufacturing process.

[0025] This contrasts with the structuring that occurs when infill areas—that is, areas intended to be completely solidified or filled with material—are exposed to light, for example, in the form of a checkerboard or homogeneous parallel lines whose angles change from layer to layer. This results in solid areas created by successive layers having less internal stress overall. For such a workpiece, its functionality does not depend on the structures created by the production of the solid areas; rather, the functional structure is the solid area itself. This known procedure is only useful for solid areas. For delicate objects, such as those with the wall structures of channels, this procedure does not achieve a significant improvement. However, the procedure according to the invention achieves a significant improvement in this regard.

[0026] Heat exchangers are particularly preferred as specific workpieces, although any other workpieces can also be manufactured according to the invention.

[0027] Improved efficiency is achieved by providing a wall structure in a heat exchanger, also known as a fractal heat exchanger, with a first number of channels for a first fluid extending along a first flow direction of the first fluid and in a first transverse direction, and with a second number of channels for a second fluid extending along a second flow direction of the second fluid and in a second transverse direction. This wall structure is designed such that, with respect to the first number of channels for the first fluid, it varies transversely along the flow direction, and / or that, with respect to the second number of channels, the wall structure varies in the second transverse direction, which is perpendicular to the second flow direction of the second fluid, along the second flow direction.

[0028] In particular, the wall structure ensures that the first and second sets of channels are in thermal interaction with each other. Furthermore, the wall structure is designed such that at a first location in the heat exchanger, the first or second transverse direction differs from the corresponding first or second transverse direction at a second location in the heat exchanger with respect to the first or second flow direction. In other words, the channel extent varies along the flow direction, preferably continuously, so that in preferred embodiments, no sharp edges occur along the flow direction that could lead to flow turbulence.

[0029] Preferably, the wall structure is designed such that the transverse direction of the channels changes from one point to another from, for example, a horizontal direction to a vertical direction, and then returns to the horizontal direction, before changing again to a vertical direction, and so on. Depending on the embodiment, this is achieved by a vector describing the transverse direction continuously "rotating," i.e., gradually increasing in angle from a horizontal direction along the flow direction, for example, from an angle of 45° to an angle of 90°, whereby the transverse direction is then vertical, i.e., perpendicular to the transverse direction at the beginning of the heat exchanger or at the previous point with respect to the flow direction of the heat exchanger, and so on.

[0030] Furthermore, the heat exchanger is preferably designed such that the number of channels for the first fluid extends over a relatively large, and preferably the entire width of a cuboid heat exchanger, or around the entire or a large part of the circumference of a cylindrical heat exchanger, and that this also applies to the second number of channels for the second fluid, so that the channels have a relatively small height but a large width in the transverse or circumferential direction. This results in low flow resistance. On the other hand, the wall structure is also designed such that when the channels have changed their transverse direction by, for example, 90°, the channels extend over the entire height of, for example, a cuboid or cylindrical volume, so that again the channels are relatively narrow, but relatively long in the transverse direction at the second point, although the width is again small.Such particularly flat but wide channels are especially favorable for heat exchange via the adjacent wall structure, but offer only low flow resistance due to their high other dimensions.

[0031] The wall structure is preferably designed such that the first number of channels and the second number of channels extend completely through the volume in the first and second transverse directions at the first location, and that the first number of channels and the second number of channels extend completely through the volume in the first and second transverse directions at the second location, wherein the first and second transverse directions at the first location differ from the first and second transverse directions at the second location. At the first location, the two transverse directions can be vertical, and at the second location, they can be horizontal in the case of a cuboid volume.In the case of a cylindrical volume, the two transverse directions can be vertical at the first point and circumferential at the second, such that each channel has a radius and is circular in the case of a full cylinder or circular sector in the case of a cylindrical sector. In the case of a spherical volume, the first two transverse directions correspond to the longitudes of the sphere at the first point and to the latitudes of the sphere at the second point. By bending a cuboid volume along the horizontal direction, a cylindrical volume is formed, and by bending the cylindrical volume along the vertical direction, a circular volume is formed. The volume comprises at least 5 first and 5 second channels, and in preferred embodiments at least 50 first and 50 second channels, and in particularly preferred embodiments at least 100 first and 100 second channels.However, all channels have a small flow resistance because they always extend through the entire volume again, i.e., at the first point, at the second points, and along the flow direction at further first and second points, the number of which depends on the number of periods.

[0032] The continuous division and merging of the channels in a preferred embodiment also provides a further valuable contribution to highly efficient heat transfer between the first and the second fluid.

[0033] In preferred embodiments, a multitude of partition sections are provided in the channels at the transition from a horizontal transverse direction to a vertical transverse direction. This effectively divides the relatively wide channel, which has low flow resistance, into several sub-channels. This ensures that wall structures are present in as many areas as possible within the channels to achieve efficient heat transfer from the first to the second set of channels. Despite the relatively long length of the channels in one direction, only very small areas are reached where the fluid flowing in the channels is not in contact with a wall structure or is relatively far removed from one.The individual sub-channels are then rejoined after their creation by the dividing sections, but now into channels with a different transverse direction, e.g., a vertical one. This ensures that the fluid is only exposed to a wall structure in a relatively short flow segment via the dividing sections to transfer energy, before being rejoined into a larger channel, thus keeping flow resistance low. Furthermore, the dividing sections significantly increase the stability of the heat exchanger, allowing it to withstand high pressures without significant deformation. This is due to the additional support provided by the dividing and merging sections.

[0034] This large, now vertical, channel is then further subdivided, and the individual sub-channels are later merged along the fluid flow direction into another large, but now horizontal, channel. Thus, at the beginning of the heat exchanger, i.e., when fluid enters the heat exchanger, there is a certain number of channels, preferably intertwined with those of the other number of channels carrying the other fluid that is to release heat, or from which the heat transfer is to take place. However, along the heat exchanger, due to the constant division and merging of the channels in the individual sections, all the individual channels of the first number of channels are, in effect, "short-circuited."This also applies to the second set of channels, which are all "short-circuited" with each other, so that optimal heat transfer with low flow resistance takes place via the wall structure, distributed as evenly as possible over the entire, e.g., cuboid or cylindrical volume of the heat exchanger, from one set of channels to the other set of channels.

[0035] This is not the case with a conventional plate heat exchanger, for example. In such a system, all channels are separated from each other along their entire length across the heat exchanger, even if they are carrying the same fluid, such as exhaust air fluid or supply air fluid.

[0036] Preferably, all channels of the first fluid along the heat exchanger are continuously short-circuited together, but not yet brought into direct contact with the channels of the second number of channels in which the other fluid, for example the exhaust air fluid, flows.

[0037] Depending on the embodiment, the heat exchanger is designed as an elongated, for example cuboid or rectangular, heat exchanger, so that the flow direction is from a first end of the heat exchanger to a second end of the heat exchanger, and the transverse direction is perpendicular to this flow direction. In other embodiments, the heat exchanger is designed as a rotationally symmetrical heat exchanger or as a heat exchanger in which the flow direction is radial, i.e., from the outside to the inside in a cylindrical body, whereby in such a case the primary inlet is located on the outside of the cylinder and the primary outlet is located on the inside of the cylinder, and the secondary inlet and the secondary outlet are also located on the outside or inside of the cylinder.

[0038] In preferred embodiments of the present invention, the first number of channels and the second number of channels are arranged in a nested arrangement such that exactly one or at least one channel of the second number of channels is always located between any two channels of the first number of channels, regardless of whether the first location of the heat exchanger, the second location of the heat exchanger, or any location between the first and second locations of the heat exchanger is considered. Preferably, the heat exchanger is further configured as a counterflow heat exchanger, such that at every location of the heat exchanger, the first flow direction of the fluid in the first number of channels is oriented opposite to the second flow direction, i.e., the flow direction of the second fluid in the second number of channels. Depending on the implementation, the fluid can be a liquid, such as water, or a gas, such as air.

[0039] The heat exchanger is designed as a counterflow heat exchanger by connecting the primary inlet and primary outlet on the one hand, and the secondary inlet and secondary outlet on the other, accordingly, with appropriate gas connections or air connections in the case of an air-to-air heat exchanger, or with appropriate air connections for a gas chiller if the heat exchanger is used as a recuperator in a gas chiller.

[0040] In preferred embodiments of the present invention, the wall structure is designed such that areas of the wall structure can be understood as spirals which, compared to a true round spiral, are "cut" to fit into a rectangular overall pattern. Nevertheless, in a finished heat exchanger, these individual "areas" are not materially separated from one another, but are formed in one piece, as can be achieved, for example, by certain three-dimensional printing processes, or gas-tightly connected by a bonding agent, as can be achieved, for example, by gluing, soldering, etc.

[0041] Overall, the heat exchanger, which is also called a fractal heat exchanger due to its structure, provides a transparent and logically coherent implementation, which is further characterized by low flow resistance and high efficiency due to an optimally uniform distribution of the heat transfer effect over the entire volume of the heat exchanger.

[0042] Preferred embodiments of the present invention are explained in detail below with reference to the accompanying drawings. These show:

[0043] Fig. 1 shows a schematic representation of the process for manufacturing a workpiece;

[0044] Fig. 2a shows a side view of a workpiece produced using the conventional manufacturing process;

[0045] Fig. 2b shows a schematic representation of the workpiece with an inclined manufacturing process according to a first variant;

[0046] Fig. 2c shows a schematic representation of the workpiece according to a second variant in the inclined manufacturing process;

[0047] Fig. 3a-i schematic views of the layers at specific angles of a period and corresponding sequence of structurings;

[0048] Fig. 4a-i shows a preferred embodiment of a sequence of layers according to the angles shown in Fig. 3a-i for the heat exchanger as a preferred workpiece;

[0049] Fig. 5a-i shows a schematic representation of the layers of the workpiece according to the invention in the implementation of a heat exchanger perpendicular to the main functional direction or flow direction;

[0050] Fig. 6 shows an overview of the individual layers within a period T with 360°;

[0051] Fig. 7 shows a top view of a workpiece after a specific layer;

[0052] Fig. 8 is a section view of Fig. 7 showing different structures within the same layer; Fig. 9a is a schematic representation of a heat exchanger as an implementation of the workpiece;

[0053] Fig. 9b shows another representation of the workpiece from Fig. 9a; and

[0054] Fig. 10 shows a preferred embodiment for generating the control data for each layer.

[0055] Fig. 1 shows a schematic representation of a process for manufacturing a workpiece using a laser beam melting process. In step 10, a layer of melting material is applied. In step 12, the layer of melting material is exposed for the first time, controlled by initial control data that defines a first layer 41 of the workpiece. After the first exposure, either immediately or after the intermediate production of various other layers, another layer is applied in step 14. Then, in step 16, the next layer of melting material is exposed, controlled by second control data that defines a second layer 42 of the workpiece.

[0056] The first control data are defined such that the first layer 41 of the workpiece has a first area 21 and a second area 22, wherein a first structuring 31 is defined in the first area 21, while the second structuring 32 is defined in the second area 22.

[0057] Furthermore, the second control data are defined such that the second layer 42 of the workpiece has in the first region 21 the second structuring 32 or a third structuring not shown in Fig. 1 and in the second region 22 has the first structuring 31 or the third structuring not shown in Fig. 1, wherein the first region 21 is different from the second region 22 in a layer 41 to 49, but is essentially the same within the layer, and wherein the first structuring 31 is different from the second structuring or the third structuring 33 is different from the first structuring 31 and the second structuring 32.

[0058] Fig. 2a shows a side view of a workpiece with the individual schematically represented layers or plies, one of which is, for example, 80 µm thick. Figs. 2b and 2c show different embodiments of the present invention with the same workpiece being manufactured, but now in an oblique arrangement. It is already evident from Figs. 2b and 2c that more webs or plies are required to manufacture the same workpiece in an oblique arrangement, but that the proportion of webs extending over the entire dimension in Figs. 2b and 2c is significantly lower than in the manufacturing process shown in Fig. 2a, assuming the workpiece has, for example, one or more vertical walls extending from top to bottom.

[0059] Thus, to produce the same wall in Fig. 2b, six more strips are required, although the individual strips are significantly shorter overall than the strips in Fig. 2a, which are all the same length and extend over the entire length of the workpiece.

[0060] In Fig. 2c, the layer normal vector 41 is shown, which differs from the flow / function direction vector 42. The deviation represents precisely the skew angle 43 by which the main flow or function direction deviates from the manufacturing normal vector geometry.

[0061] According to the invention, the inclined arrangement shown in Figs. 2b and 2c alone achieves a significant average reduction in structure lengths across an entire layer, albeit at the expense of more webs. However, this is negligible compared to the gain obtained through the substantial reduction in production rejects.

[0062] Fig. 2b differs from Fig. 2c in that a vertical wall is assumed as the boundary structure in Fig. 2b, while a sloping wall is used on the left and right sides in Fig. 2c. Both implementations are possible and can be chosen depending on the embodiment. Depending on the embodiment, the procedure according to Fig. 2c is easier to obtain for generating the control data because fewer modifications are required compared to the control data provided for the straight structure of Fig. 2a.

[0063] The slant angles 43 are preferably selected such that, with a structure width of 80 pm, approximately 200 additional layers are required, meaning that one side of the heat exchanger is "raised" by approximately 16 mm relative to the other side, as shown in 44a in Fig. 2b. This means that, when manufacturing a workpiece according to the inventive method, 200 additional layers are required compared to a straight manufacturing process where there is an angle of 0° between the flow / function direction vector and the layer normal vector. It should be noted that the layer thicknesses can range from 50 to 150 pm, and that the number of additional layers can range from 100 to 400 layers to achieve good and economically viable results.

[0064] With reference to Figs. 4a to 4i, a preferred embodiment for manufacturing the heat exchanger is shown below as an example of a workpiece, with Figs. 4a to 4i being compared with the corresponding Figs. 5a to 5i, which are “mapped” in Fig. 6.

[0065] The first structuring 31 in Fig. 4a is found in the upper left and lower right, and this structuring corresponds to the structuring in Fig. 5a for the case in the upper left of Fig. 4a and Fig. 5e for the case in the lower right.

[0066] In contrast, the diamond-shaped structure and the square structure of Fig. 5b correspond to the second structuring 32, as shown in Fig. 5b and 5d, respectively. The third structuring 33, with its essentially vertical channels (instead of the horizontal channels in the first structuring 31), corresponds to the structuring in Fig. 5c and Fig. 5g.

[0067] Fig. 4a shows a layer as defined by the control data, while Fig. 5a shows a layer of the workpiece when cut perpendicular to the flow / function direction.

[0068] Figures 4b to 4i show the change of the layer in 45° increments over a 360° period. It should be noted that between the layer of Figure 4a and Figure 4b, a significant number of other layers, not shown in the figures, must be exposed to create a continuous transition from the first structuring layer 31 in the upper left of Figure 4a to the second structuring layer 32, which is located in the upper left of Figure 4b. In the area where the second structuring layer 32 was located at the top edge of the image in Figure 4a, the first structuring layer 31 is now located in Figure 4b.

[0069] Figures 3a to 3i illustrate a general change in structuring, for example, between three different structurings, from region to region in 45° increments. In particular, in the example shown in Figure 3a, the layer is divided into nine regions: a first region 21, a second region 22, a third region 23, a fourth region 24, a fifth region 25, a sixth region 26, a seventh region 27, an eighth region 28, and a ninth region 29. Further divisions with more or fewer regions can also be implemented. The structurings in the individual regions 21 to 23 are shown as the first structuring 31, the second structuring 32, and the third structuring 33, and as circled numbers in Figure 3a.

[0070] It can be seen that the structuring in the first area along Fig. 3a to 3i changes from the first structuring to the second structuring, to the third structuring, to the second structuring, to the first structuring, to the second structuring, to the third structuring, to the second structuring and to the first structuring.

[0071] Accordingly, the change takes place, for example, in the sixth middle area from structuring 1 to structuring 2, to structuring 3, to structuring 2, to structuring 1, to structuring 2, to structuring 3, to structuring 2 and to structuring 1.

[0072] In the embodiment shown in Figs. 4a to 4i, this would be the central area with the first structuring in Fig. 4a, which is also the first structuring in Fig. 4e, for example, but is the second structuring in Fig. 4f, for example, which in the top view of Figs. 4a to 4i is a rhombus shape or a square shape, while the first structuring represents a shape with essentially horizontal channels and the third structuring represents a shape with essentially vertical channels.

[0073] In Figures 3a to 3i and 4a to 4i, it should be noted that a double inclined arrangement is present, such that inclination has been carried out in both the x and y directions, meaning that the normal vector deviates from the function direction vector in both directions. In alternative embodiments, a significant yield improvement is achieved even with inclination in only one direction. In this case, with inclination in the y direction, a change in structure would only occur along the y-direction, while the structure would remain the same along the x-direction. However, the "double" inclination, as shown in Figures 4a to 4i, leads to an even better yield than the simple inclination, which can also be implemented.

[0074] It should be noted that the first area, or the "center" of the first area (e.g., the upper left corner of Figures 4a to 4i), exhibits the same structure as Figures 5a to 5i. To further illustrate this, the pivot points 301 and 302 are also shown in Figures 4a to 4i. They are located at the same positions as in Figures 5a to 5i. Several other preferred embodiments are described below with reference to Figures 3a to 3i. In particular, the control data are further defined such that the first layer 41 of the workpiece has the third structure in the third area 23, while the second control data for the subsequent layer are defined such that the second layer has either the second structure or the first structure in the third area. Specifically, the second structure is provided in the second layer 42 in the third area 23.However, in the third layer 43 the first structuring is provided in the third area, while in the fourth layer 44 the second structuring is provided in the third area, as is also the case in the sixth layer 46 in Fig. 3f and the eighth layer 48, while in layers 45, 49 and 41 the third structuring is provided in the third area 23.

[0075] From the definition in Fig. 3a, it can be seen that the second region 22 is arranged between the third region 23 and the first region 21, while the fourth region 24 is arranged between the first region 21 and the fifth region 25. Furthermore, the sixth region 26 is arranged between the fourth region 24 and the seventh region 27, while the ninth region 29 and the third region 23 enclose the seventh region 27. Similarly, the eighth region 28 is arranged between the fifth region 25 and the ninth region 29, as illustrated in the example with nine regions and three different structurings.

[0076] Other embodiments of workpieces with multiple areas and multiple structurings or fewer than three structurings can also be produced.

[0077] Furthermore, layers 41 to 49 in Figures 3a to 3i and 4a to 4i represent only sections of an entire layer of a workpiece. As will be explained further with reference to Figures 7 and 8, the layers typically have a larger extent, thus allowing not only a change along the length or width from the first structuring to the second structuring and then to the third structuring, but also back to the second structuring and the first structuring, depending on the size of the workpiece, the length of the period, and especially the size of the skew angle. If the skew angle is chosen to be smaller, the change from one structuring to the next occurs more slowly, i.e., over a larger horizontal or vertical area.vertical distance, whereas when the slant angle is set larger, the change from one structuring to the next structuring within a layer takes place faster, i.e. over a smaller horizontal or vertical distance.

[0078] In the embodiment shown in Figs. 3a to 3i, the first control data are further defined such that the first layer of the heat exchanger in the fourth region 24 has the second structure, and the second control data are further defined such that the second layer of the heat exchanger in the fourth region has the third structure, as for example for layers 42, 46, or the second structure as exemplified by layers 43, 45, 47, 49, or the first structure as exemplified by layers 44, 48. Furthermore, the fourth region 24, as shown in Fig. 3a, is located next to the first region 21.

[0079] Furthermore, in exemplary embodiments, the first control data are defined such that the first layer of the workpiece has the third structure in a fifth area 25, and that the second layer of the heat exchanger in the fifth area 25 has the second structure as the second layer, using layers 42, 44, 46, 48 as an example, or has the first structure as the second layer, using layers 43, 47 as an example, or again has the third structure as the third layer, using layers 45 or 49 as an example. Furthermore, the fourth area 24 lies between the fifth area 25 and the first area 21.

[0080] In preferred embodiments, the first structuring defines first channels extending in a first direction, such as horizontally or from the bottom left to the top right, as illustrated with reference to Fig. 8. Furthermore, the second structuring defines quadrilaterals with equal or different side lengths, while the third structuring defines second channels extending in a second direction, different from the first direction, and arranged, for example, vertically or from the top left to the bottom right, as shown in Fig. 8.

[0081] In particular, the second channels are arranged essentially at right angles to the first channels or at an angle between 80° and 100°.

[0082] Furthermore, in preferred embodiments, the changes in the structuring are not abrupt but fluid, such that within the first layer or the second layer the first structuring gradually transitions into the second structuring or the second structuring gradually transitions into the third structuring, as is shown in particular in Figs. 4a to 4i, where the second structuring 32 gradually develops from the first structuring 31, and then the third structuring 33 gradually develops from the second structuring 32.

[0083] In particular, preferred embodiments include transition areas between the respective areas, which ensure a seamless gradual transition between the individual structures.

[0084] According to the invention, as is particularly illustrated in Fig. 6, a structural period is gradually reached via a sequence of layers, which is characterized, firstly, by an identical structure perpendicular to the functional plane as shown in Figs. 5a to 5i. Perpendicular to the layer plane, there is also a sequence of layers that define the same structural period, but these layers do not have an identical structure; rather, they have several specific structures. Nevertheless, the sequence includes a layer located at the beginning of the structural period that corresponds to a layer located at the end of the structural period.

[0085] In particular, in one embodiment there are more than 100 layers between the initial layer and the final layer, eight of which are shown in Figures 3a to 3i and 4a to 4i, with an angle between two successive layers of the figures preferably being 45° and in particular between 40° and 50°.

[0086] The sequences of the structuring present in the individual areas are shown in Figs. 3a to 3i. Preferably, with regard to the dimensions of the workpiece, a periodic structure is between 8 and 12 mm long and comprises between 80 and 150 layers, wherein a layer thickness is preferably between 60 and 120 pm and is particularly preferred to be around 80 pm.

[0087] Fig. 7 shows a cross-section through a workpiece, preferably designed as a heat exchanger. In particular, the various structuring patterns above the layer, which alternate along the layer, are shown in Fig. 7, as explained, for example, with reference to Figs. 3a to 3i. Fig. 8 shows a more detailed view with a first structuring pattern 31 with channels extending from the lower left to the upper right, a second structuring pattern 32 arranged next to it with essentially rectangular structures, and a third structuring pattern 33 with channels extending from the upper left to the lower right. It is further shown in Fig. 7 or 8 that the structure is symmetrical, such that at the edges the first structuring pattern 31 transitions into the second structuring pattern from top to bottom and then into the third structuring pattern 33, as shown in the lower region of Fig. 8.Figure 8 shows the third structure 33 transitioning from left to right into the second structure 32 and then back into the first structure 31. For structural reasons, a symmetry line was chosen in Figure 8 that divides the representation in Figure 8 approximately into a vertical and a horizontal center. Such a symmetry line is also shown in Figure 7.

[0088] Fig. 10 shows a preferred embodiment for generating the input data or control data for each layer from the "even" input data provided in step 90, i.e., input data to produce according to Fig. 2a. In step 91, this even input data is converted into "oblique" input data according to the invention, in order to then generate the control data for each layer from the "oblique" input data obtained in step 91 in step 92. The control data output in step 92 for each layer is then fed into steps 12 and 16, respectively, which have been illustrated with reference to Fig. 1.

[0089] In particular, when converting the straight input data into the oblique input data in step 91 of Fig. 10, a mathematical function is used which depends on the respective point in the x, y direction and the oblique angle, so that for each three-dimensional point in a layer a certain structure value is calculated which indicates whether the laser beam should expose at this point in the corresponding layer or not.

[0090] Fig. 5a shows a cross-sectional view or a "starting view" of a heat exchanger having a first set of channels 101a, 101b, 101c for a first fluid, extending along a first flow direction of the first fluid and further extending in a first transverse direction. The first flow direction is either in or out of the plane of the drawing. The first transverse direction extends parallel to the wall structure 200a, 200b, 200c, 200d, and 200e. The first flow direction is therefore either the direction in the z-direction of the coordinate system in Fig. 5a or opposite to the z-direction if the first flow direction is directed out of the plane of the drawing and the positive z-direction is directed into the plane of the drawing, as shown on the coordinate system. The first transverse direction is preferably the x-direction, but could also be the y-direction.

[0091] The second set of channels comprises channels 102a, 102b, and 102c, and this second set of channels is for a second fluid. These channels extend along a second flow direction of the second fluid and in a second transverse direction. The second transverse direction is preferably the same as the first transverse direction if the channels are parallel and nested. However, alternative implementations with non-constant wall thickness or multiple walls between the channels are also possible. In such cases, the first transverse direction would extend in an xy direction, e.g., at +30°, and the second set of channels would extend at a transverse angle of -30°, for example. However, a parallel and symmetrical orientation of the channels, as shown in Fig.Figure 5a shows a preferred configuration in which the channels are nested such that a channel of a different number is always arranged between two channels of one number. In particular, exactly one channel of one number is always arranged between exactly two channels of the other number, as is shown, for example, in Figure 5a, where channel 102b is arranged between channels 101a and 101b.

[0092] According to the invention, the first transverse direction varies along the first flow direction, and the second transverse direction also varies along the second flow direction, as can be seen from the combined view of Figures 5a to 5i, which show cross-sections through the heat exchanger at various locations, as clearly illustrated in Figure 6 using an example section. This section is represented in Figures 5a to 5i by the four adjacent individual areas, which are shown, for example, at 301, 302, 303, and 304 in Figure 5b. Furthermore, points 301, 302 and 303, 304 in Figures 5a to 5i are marked around which arrows are shown to symbolize an axis of rotation of a respective spiral around which individual wall structure areas extend along the length of the heat exchanger in the respective flow direction or against the respective flow direction. The arrows in Fig. 5b and in the other Figs. 5a to 5b.Figure 5i, drawn around the "pivot points" of the individual sub-sections 301, 302, 303, 304, represents the direction of rotation of the wall section along the flow direction of the first or second fluid, and thus represents the direction of rotation of the corresponding spiral in the positive direction, as for example in the spiral through section 302, or in the negative direction, as for the spiral of section 301. It should be noted, however, that nothing actually "rotates" in the finished heat exchanger. The direction of rotation merely illustrates how the wall structure is formed along the flow direction in a preferred embodiment.

[0093] The wall structure 200a to 200e is designed such that at the first location (Fig. 5a) of the heat exchanger, with respect to the first or second flow direction, a first transverse direction or a second transverse direction exists, which are aligned along the x-direction or the y-direction. Preferably, in this embodiment, the two transverse directions at the first location are the same, i.e., for example, in the x-directions of Fig. 5a.

[0094] At a second location in the heat exchanger with respect to the first and second flow directions, as shown in Fig. 5c, the first and second transverse directions are now oriented in the y direction instead of the x-direction. The channels no longer extend horizontally as in Fig. 5a, but vertically as in Fig. 5c. The wall structures 200a to 200e of Fig. 5a have now transformed into a vertical wall structure 202a, 202b, 202c, 202d. Nevertheless, the two fluid regions “1” for the first set of channels and “2” for the second set of channels are completely separated from each other and are configured as shown in Fig. 5c. The channels of the first number of channels are formed on the left with respect to wall structure 202a and between wall structure 202b and 202c and on the right with respect to wall structure 202d, while the second number of channels are formed between wall structure 202c and 202d and between wall structure 202a, 202b.It should be noted that Figures 5a to 5i only show a section of the heat exchanger, which can be much larger, for example with 10 to 100 channels per number of channels or with an even greater number and a length or radius as required for the respective application.

[0095] Fig. 5b shows the transition between the formation of horizontal channels and the formation of vertical channels, i.e., between the cross-section of Fig. 5a and the cross-section of Fig. 5c. For this purpose, the individual sections 301, 302, 303, 304 are rotated from their position in Fig. 5a, for example, in the respective direction of rotation, while the sections remain in constant contact. This means that elements 301 and 302 are both rotated upwards from Fig. 5a, and elements 303 and 304 are rotated downwards from Fig. 5a. This means that channel 102b of the second set of channels is "divided" into sub-channels 103a, 103b, with the now diamond-shaped wall structure shown in Fig. 5a forming division sections to create the two sub-channels 103a, 103b from the continuous horizontal channel 102b. Similarly, for example, the channel 101a above it is shown in Fig.5a is divided into sub-channels 104a, 104b, 104, again by the fact that the individual wall structure areas of Fig. 5b "change" along the length of the heat exchanger. Comparing Fig. 5b and Fig. 5c, it can be seen that the already adjacent sub-channels for the second fluid, which are labeled "2" in Fig. 5b, and the respective sub-areas for the first fluid, which are labeled "1" in Fig. 5b, now merge into one another. This is achieved by "rotating" the individual wall structure areas 301 to 304 accordingly until a completely vertical orientation of the wall structure is achieved, as shown at 202a to 202d in Fig. 5c.

[0096] By further “rotating” the areas 301 to 304 and of course all the other, no longer individually designated, sub-areas of the wall structure around the corresponding axes of rotation represented by thicker dots, a situation is achieved as shown in Fig. 5d, where the vertical channels are now again divided into vertical sub-channels by partitioning structures, which then merge horizontally again in Fig. 5e, so that horizontal sub-channels have been achieved again.

[0097] However, a comparison of Figures 5e and 5a now reveals that the "occupancy" of the individual channels has changed. Where the first fluid was present in Figure 5a, the second fluid is now present in Figure 5e, and vice versa. In wall structure areas 200a and 200b in Figure 5e, there is now a channel of the second number of channels, whereas between these structure areas in Figure 5a, there was a channel of the first number of channels.

[0098] The further development of the heat exchanger along the first and second flow directions is shown in Fig. 5f. Thus, the corresponding vertical channels are again divided into individual vertical sub-channels, so that vertical sub-channels already "touch" but are not yet merged. This merging takes place in the transition from Fig. 5f to Fig. 5g, whereby, analogous to what was shown in Fig. 5e, the "occupancy" of the individual structures is now the opposite of the occupancy in Fig. 5c. For example, between structures 202d and 202c in Fig. 5g, there is a channel of the first number of channels for the first fluid, as represented by "1", while between these two structures in Fig. 5c, there was a channel of the second number of channels for the second fluid.

[0099] The vertical channels of Fig. 5f are again divided into individual vertical sub-sections, as shown in Fig. 5g, whereby sub-sections of the same fluid region now already touch horizontally but are not yet merged. This merging then takes place again at the transition between Fig. 5g and Fig. 5i, and the "occupancy" of the individual sections is now exactly the same as in Fig. 5a.

[0100] The heat exchanger therefore has a period T in the first and second flow directions in preferred embodiments of the present invention. The starting situation is shown in Fig. 5a, where the period begins. Figs. 5b to 5i each indicate one-eighth of the period. When a period is designated as 360°, an angle of 45°, or one-eighth of the period, is "swept" from each partial image to the next. A perspective view of the heat exchanger is shown in Figs. 9a and 9b, where the "frame" 600 for the heat exchanger can be the wall region of the heat exchanger. However, it is shown in Figs. 9a and 9b that the frame is open at the top (and bottom) by openings, which are closed in an actual embodiment. Depending on the implementation, the heat exchanger in Figs. 9a and 9b can also function without the frame 600 as a section within a significantly larger heat exchanger structure.

[0101] Fig. 9a shows the same wall structures as Fig. 5a. Furthermore, the individual horizontal channels, each containing the corresponding fluid, are shown. In particular, the channels labeled "1" contain the first fluid, and the channels labeled "2" contain the second fluid. The flow direction is into or out of the plane shown in Fig. 9a. Preferably, the heat exchanger is used as a counterflow heat exchanger, so that in the channels labeled "1", the fluid flows into the plane of the drawing, and in the channels labeled "2", the fluid flows out of the plane of the drawing. Furthermore, in the embodiment shown in Fig. 9a, the corresponding arrangement of the vertical channels is shown through the openings depicted above in frame 600. Thus, the position of the heat exchanger shown at 602 in or against the corresponding flow direction corresponds to the position in Fig.5c, i.e., after a quarter period or after a 90° rotation. Accordingly, the location shown at 604 reflects the situation of Fig. 5g. Between positions 602 and 604 in the flow direction of the heat exchanger is position 603, where, as shown in Fig. 5e, the channels are again horizontally configured, as in the front of Fig. 9a, but with varying heights for the individual structures 200a to 200e. It should be noted, however, that the structures 200a to 200e do not extend continuously, but vary as shown in Figs. 5a to 5i. However, at position 603, the same horizontally oriented walls are again present as at the front in Fig. 9a, i.e., at position 601. Due to the continuous change in the wall structure, the second fluid, and not the first fluid, flows between 200a and 200b at position 603.

[0102] An entire period is represented by the workpiece shown in Figs. 9a and 9b, since horizontal channels are again present on the rear cross-sectional side, labeled 605 in Fig. 9a, which are again filled with the first and second fluids in the same way as shown at the front in Fig. 9a. Vertical channels have the advantage that the removal of condensing fluid, such as condensate, can be easily achieved. Since there are two areas within a period that run vertically through the entire heat exchanger from top to bottom, condensate, which will typically condense as small drops at the dividing sections, will simply flow downwards.The wall structure is preferably designed such that the first or second set of channels has one or more vertical sections extending from top to bottom through the heat exchanger in the direction of operation, and a condensate drain is provided below one or more vertical sections to remove any condensate present in them. This drain includes, in one implementation, a water collection device, such as a drip tray at the bottom of the heat exchanger, preferably for each of the two pressure zones, and a pump or other water removal device. This allows for easy handling and early removal of the condensate, thus preventing ice formation in the heat exchanger or other problems related to condensate.

[0103] Another aspect of the present invention is that, due to the fact that vertical and horizontal channels (in the transverse direction, i.e., perpendicular to the flow direction) alternate regularly, the number of channels along the flow direction can be easily changed. In the extreme case, in the collection area consisting of a single first channel and a single second channel, after a period of, for example, 90°, i.e., when a transition from horizontal to vertical channels has occurred, the number of horizontal and / or vertical channels is changed, i.e., increased by one or more channels.

[0104] Although it is explained below that the wall structure of the heat exchanger can be created with individual areas that have a spiral or screw shape along the flow direction or that "develop" in a certain shape along the flow direction, it should be noted that a preferred manufacturing method for the heat exchanger is by means of rapid prototyping or by means of 3D printing.

[0105] Figures 4a to 4i show elements 301, 302, 303, and 304. The development of these elements along the flow direction is shown in three dimensions in Figure 6, where the cross-sections corresponding to a specific position along the flow direction of the heat exchanger are indicated. One period T corresponds to the development shown in Figures 5a to 5i, and this period can be followed by another period of the same duration, or by a different implementation of the heat exchanger, again with a specific period, but, for example, with a larger or smaller number of horizontal and / or vertical channels.

[0106] It should be noted that the implementation of the present invention can be scaled to any desired size depending on the embodiment, since the actual length in millimeters, for example of a period, can be set as desired. A period length of less than 10 cm, and preferably less than 2 cm, is preferred to obtain a small-scale structure, which is also characterized in particular by the fact that the wall structure is relatively thin in order to achieve good heat transfer from the first fluid to the second fluid. However, it should be noted that the thermal conductivity of the wall structure alone is not as critical as, for example, in a plate heat exchanger, because the channels are constantly being divided and rejoined, and the position of the channels is continuously changing.Due to the large surface area of ​​the wall structure in contact with the fluid and the relatively homogeneous contact between the wall structure and the fluid throughout the volume, good heat transfer from the fluid to the wall structure is achieved. This efficient heat transfer is independent of whether the wall structure itself has a particularly good heat transfer coefficient, such as metal, or whether, for reasons of efficient and economical manufacturing, the wall structure is made of plastic, which has a lower heat transfer coefficient than, for example, aluminum. Because of the wall structure, the contribution of the actual material coefficient is reduced compared to the heat transfer, thus achieving good efficiency with a manageable volume.

[0107] Fig. 3b shows a top view of the four individual areas 301, 302, 303, 304, where the corresponding rotations and angles in Figs. 1a to 2d correspond to the respective rotation angles between 0° and 360° of the top view of Fig. 3b. Fig. 4a shows one half of the representation of Fig. 3b, and Fig. 4b shows a perspective view of the top view of Fig. 4a and again one half of Fig. 3a.

[0108] Figures 5a to 5d show the formation of a single structure from the four structures in Figure 3a and the two structures in Figure 4b, respectively. The starting point is a circular shape, as shown in the top view in Figure 5a. The circular shape developed as a spiral is shown in perspective in Figure 5b. Since the individual elements are rectangular, the circular shape is "cut" into a rectangular shape, starting from Figure 5a. This rectangular shape, when "unwound" as a screw in analogy to Figure 5b, then yields the perspective shape shown in Figure 5d. Figure 3a shows four such spirals or helical structures, as depicted in Figure 5d. Therefore, Figure 1a, for example, represents a cross-sectional view of a heat exchanger composed of many such superimposed or connected structures from Figure 5d.

[0109] These structures show that there are only soft transitions, so that despite the constant division of the flow in a relatively large channel, a low flow resistance is still obtained, preferably with a gas flow in the heat exchanger that is as unturbulent as possible.

[0110] With regard to the dimensioning of the wall structure, it is designed to have a thickness between 0.01 mm and 1 mm between a channel of the first number of channels and an adjacent channel of the second number of channels, or to comprise a proportion of 5 to 40 percent of the volume of the heat exchanger and preferably a proportion of 15 to 20 percent of the volume of the heat exchanger.

[0111] In exemplary embodiments, the heat exchanger is designed to have at least two periods. Preferably, many more periods are used, in the range of 10,000 to 10 million per liter of the heat exchanger volume. Particularly preferred dimensions are in the range of 100,000 to 300,000 periods per liter of volume.

[0112] In implementations, the number of channels can be set to high levels, such as more than one million, or between 100,000 and 2 million. The number of periods can be set within the above range, or between 5 and 8 if particularly low flow resistance is desired.

[0113] Although the heat exchanger described above has been described as an air-to-air or gas-to-gas heat exchanger, it can also be operated as a liquid-to-gas or liquid-to-liquid heat exchanger. When operating as a liquid heat exchanger, the structures through which the respective liquid flows are dimensioned differently depending on the viscosity of the liquid. However, due to the size-independent shape of the wall structure according to the invention, this can be easily adapted to the specific application. Furthermore, the heat exchanger according to the invention can also be used in any application where a highly efficient heat exchanger is required, such as in the described application as a recuperator in the form of a gas chiller, or as a heat exchanger in an air heat recovery unit, or in any other application where, for example,Plate heat exchangers or other heat exchangers can be used in counterflow or parallel flow.

[0114] An exemplary implementation of the workpiece as a heat exchanger, as it can be produced using the manufacturing technique according to the invention, is described below. It should be noted that the inclined manufacturing process will be evident in the workpiece, particularly since the individual layers produced successively are recognizable due to the melting process and the subsequent cooling process. However, if the workpiece or heat exchanger were cut at an angle, i.e., perpendicular to the main functional direction or flow direction, the cuts would exhibit a structuring pattern with essentially only a single structure per cut, but these patterns would intersect several successively produced layers.

[0115] A heat exchanger according to the invention is preferably defined by example as follows.

[0116] 1. Heat exchanger with the following features: a first number of channels (101a, 101b, 101c) for a first fluid, extending along a first flow direction of the first fluid and in a first transverse direction, the first transverse direction varying along the first flow direction; a second number of channels (102a, 102b, 102c) for a second fluid, extending along a second flow direction of the second fluid and in a second transverse direction, the second transverse direction varying along the second flow direction; a wall structure (200a-200e, 202a-202d) configured such that the first number of channels and the second number of channels are in thermal interaction,and that at a first location of the heat exchanger, with respect to the first or second flow direction, the first transverse direction or the second transverse direction is different from a first or second transverse direction at a second location of the heat exchanger with respect to the first or second flow direction. 2. Heat exchanger according to Example 1, in which the first number of channels is arranged interleaved with the second number of channels, such that a channel (102b) of the second number of channels is arranged between two channels of the first number of channels (101a, 101b), or in which the wall structure (200a-200e, 202a-202d) is designed such that the first transverse direction and the second transverse direction are the same at the first location of the heat exchanger.and that the first transverse direction and the second transverse direction at the second position of the heat exchanger are the same and different from the first transverse direction and the second transverse direction at the first position of the heat exchanger.

[0117] 3. Heat exchanger according to Example 1 or 2, which is designed as a counterflow heat exchanger, wherein the first number of channels and the second number of channels are designed such that the first flow direction is opposite to the second flow direction.

[0118] 4. Heat exchanger according to one of the preceding examples, comprising a volume in which at least 5 first channels and at least 5 second channels are arranged, wherein the wall structure (200a-200e, 202a-202d) is configured to fluidically connect the first number of channels to one another, and to fluidly connect the second number of channels to one another, and to fluidically separate the channels of the first number of channels from the channels of the second number of channels, and wherein the wall structure (200a-200e, 202a-202d) is configured such that the first number of channels and the second number of channels extend completely through the volume at the first position in the first and second transverse directions, and that the first number of channels and the second number of channels extend completely through the volume at the second position in the first and second transverse directions.wherein the first and second transverse directions at the first position differ from the first and second transverse directions at the second position. 5. Heat exchanger according to one of the preceding examples, wherein the wall structure (200a-200e, 202a-202d) is configured such that the first transverse direction at the first position is at an angle between 60° and 120° to the first transverse direction at the second position, or that the second transverse direction at the first position is at an angle between 60° and 120° to the second transverse direction at the second position, and that the first position is spaced from the second position by a distance between 0.5 mm and 2 cm.

[0119] 6. Heat exchanger according to one of the preceding examples, wherein the wall structure (200a-200e, 202a-202d) has parallel areas at the first location that separate the first number of channels and the second number of channels along the first or second transverse direction, and wherein the wall structure (200a-200e, 202a-202d) has parallel areas at the second location that separate the first number of channels and the second number of channels along the different first or second transverse direction.

[0120] 7. Heat exchanger according to one of the preceding examples, wherein the wall structure (200a-200e, 202a-202d) has flow-dividing sections (301 , 302, 303, 304) for the first number of channels along the first transverse direction to divide a first channel of the first number of channels into several first sub-channels, and to divide a second channel of the first number of channels into several second sub-channels.

[0121] 8. Heat exchanger according to one of the preceding examples, wherein the wall structure (200a-200e, 202a-202d) has flow merging sections to merge a partial channel with one or more other partial channels in which either the first or the second fluid flows, to form a channel of the first or second number of channels at the first or second position.

[0122] 9. Heat exchanger according to Example 7 or Example 8, wherein the wall structure (200a-200e, 202a-202d) is designed such that the flow division sections for dividing the first number of channels represent the flow merging sections for merging partial channels into one channel of the second number of channels.

[0123] 10. Heat exchanger according to one of the preceding examples, wherein the wall structure (200a-200e, 202a-202d) is designed such that between the first location where the channels of the first number of channels and the second number of channels have a horizontal transverse direction and the second location where the channels of the first number of channels and the second number of channels have a vertical transverse direction, the wall structure (200a-200e, 202a-202d) is diamond-shaped, so that a partial channel formed by a flow-dividing section borders another partial channel, through which the same fluid flows, both vertically and horizontally.

[0124] 11. Heat exchanger according to one of Examples 7 to 10, wherein the wall structure (200a- 200e, 202a-202d) is designed to divide a channel of the first number of channels or of the second number of channels into several sub-channels, each having a square shape or a rhombus shape with sides of different lengths.

[0125] 12. Heat exchanger according to any of Examples 7 to 11, wherein a flow-dividing section or a flow-merging section has gradually increasing elevations in the direction of flow of a lower wall of a channel of the first or second number of channels or a gradually increasing depression in the direction of flow of an upper wall of the channel of the first or second number of channels, wherein an elevation and a depression meet in a middle region between starting points of the elevation or depression to cut the channel into the sub-channels.

[0126] 13. Heat exchanger according to one of Examples 7 to 12, wherein the flow-division sections of the first number of channels are arranged offset from flow-division sections of the second number of channels, such that, with respect to the first transverse direction, a flow-division section of a channel of the first number of channels is arranged between two flow-division sections of a channel of the second number of channels.

[0127] 14. Heat exchanger according to one of Examples 8 to 13, wherein the stream merging sections of the first number of channels are arranged offset from stream merging sections of the second number of channels, such that with respect to the first transverse direction a stream merging section of a channel of the first number of channels is arranged between two stream merging sections of a channel of the second number of channels.

[0128] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, such that a block or component of a device can also be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device. Some or all of the process steps can be performed by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some or more of the key process steps can be performed by such an apparatus.

Claims

Patent claims 1. Method for producing a workpiece using a beam melting process, comprising the following steps: Application (10) of a layer of remelt material; initial exposure (12) of the layer of remelt material controlled by initial control data that define a first layer (41) of the workpiece; after the initial exposure, application (14) of a further layer of remelt material; Exposure (16) of the further layer of remelt material controlled by second control data defining a second layer (42) of the workpiece, wherein the first control data are defined such that the first layer (41) of the workpiece has a first structure (31) in a first region (21) and a second structure (32) in a second region (22); and wherein the second control data are defined such that the second layer (42) of the workpiece has the second structure (32) or a third structure (33) in the first region (21) and has the first structure (31) or the third structure (33) in the second region (22), wherein the first region (21) is different from the second region (22), and wherein the first structure (31) is different from the second structure (32), or wherein the third structure (33) is different from both the first structure (31) and the second structure (32).

2. Method according to claim 1, wherein the first control data are defined such that the first layer (41) of the workpiece has the second structuring (32) or the third structuring (33) in a third area (23), and wherein the second control data are defined such that the second layer (42) has the second structuring (32) or the first structuring (31) in the third area (23), wherein the second area (22) lies between the first area (21) and the third area (23).

3. Method according to claim 1 or 2, wherein the first control data are defined such that the first layer (41) in a fourth area (24) has the second structuring (32), and wherein the second control data are defined such that the second layer (42) of the workpiece in the fourth area (24) has the third structuring (33) or the second structuring (32) or the first structuring (31), wherein the fourth area (24) is adjacent to the first area (21).

4. Method according to one of the preceding claims, wherein the first control data are defined such that the first layer (41) of the workpiece has the third structuring (33) in a fifth area (25), and wherein the second control data are defined such that the second layer (42) of the workpiece has the second structuring (32) or the first structuring (31) in the fifth area (25), wherein the fourth area (24) lies between the fifth area (25) and the first area (21).

5. Method according to any of the preceding claims, wherein the first structuring (31) defines first channels extending in a first direction, wherein the second structuring (32) defines quadrilaterals with equal or different side lengths, and wherein the third structuring (33) defines second channels extending in a second direction that differs from the first direction.

6. The method of claim 5, wherein the second channels have an angle to the first channels between 80° and 100°.

7. Method according to any of the preceding claims, wherein the first control data or the second control data are defined such that within the first layer (41) or the second layer (42) the first structuring (31) gradually transitions into the second structuring (32) or the second structuring (32) gradually transitions into the third structuring (33).

8. Method according to one of the preceding claims, wherein the first or second control data are defined such that in the first layer (41) the first structuring (31) transitions into the second structuring (32) in a first transition area located between the first area (21) and the second area (22), and the second structuring (32) in a second transition area, which lies between the second area (22) and the third area (23), transitions into the third structuring (33).

9. Method according to one of the preceding claims, wherein control data comprising the first control data and the second control data define the workpiece via a sequence of layers, wherein a layer (49) at the end of a structural period has the same configuration as a layer (41) at the beginning of the structural period, wherein the first layer is located in a manufacturing direction ahead of the second layer, and the second layer is located in a manufacturing direction ahead of the layer (49) located at the end of the structural period.

10. Method according to any one of claims 1 to 9, wherein a sequence of layers of the workpiece comprises a start layer (41) at the beginning of a structural period and a finish layer (49) at the end of the structural period and between the start layer and the finish layer a second layer (42), a third layer (43), a fourth layer (44), a fifth layer (45), a sixth layer (46), a seventh layer (47) and an eighth layer (48), wherein a period angle between any two adjacent layers (41 - 49) is between 40° and 50°.

11. Method according to claim 10, wherein in the first region (21) a sequence of structurings over the sequence of layers is as follows: 1 , 2, 3, 2, 1 , 2, 3, 2, 1 , or wherein in the second area (22) an order of structurings over the sequence of layers is as follows: 2, 3, 2, 1 , 2, 3, 2, 1 , 2, or wherein in a third area (23) a sequence of structurings over the sequence of layers is as follows: 3, 2, 1, 2, 3, 2, 1, 2, 3, or wherein in a fourth area (24) an order of structurings over the sequence of layers is as follows: 2, 1 , 2, 3, 2, 1 , 2, 3, 2, or wherein in a fifth area (25) an order of structurings over the sequence of layers is as follows: 3, 2, 1 , 2, 3, 2, 1 , 2, 3, or wherein in a sixth area (26) an order of structurings over the sequence of layers is as follows: 1 , 2, 3, 2, 1 , 2, 3, 2, 1 , or wherein in a seventh area (27) an order of structurings over the sequence of layers is as follows: 2, 3, 2, 1, 2, 3, 2, 1, 2, or wherein in an eighth area (28) an order of structurings over the sequence of layers is as follows: 2, 1 , 2, 3, 2, 1 , 2, 3, 2 or wherein in a ninth area (29) an order of structurings over the sequence of layers is as follows: 1 , 2, 3, 2, 1 , 2, 3, 2, 1 , wherein the sixth area (26) lies between the fourth area (24) and the seventh area (27), or wherein the eighth area (28) lies between the fifth area (25) and the ninth area (29), or wherein the sixth area (26) lies between the second area (22) and the eighth area (28), or wherein the seventh area (27) lies between the third area (23) and the ninth area (29), and wherein '1' represents the first structuring (31), '2' represents the second structuring (32), and '3' represents the third structuring (33).

12. Method according to any one of claims 9 to 11, wherein a structure period is between 8 mm and 12 mm long and comprises between 80 and 150 layers, or a layer thickness is between 60 pm and 100 pm.

13. Method according to one of the preceding claims, wherein the workpiece is a heat exchanger with a main fluid flow direction, wherein the position and the further position have a normal vector which forms an acute angle with respect to the main fluid flow direction which is less than 30° and greater than 2°.

14. Method according to claim 13, wherein the position and the further position are each a two-dimensional position, and wherein the control data are configured to define the layers in two dimensions obliquely to the main fluid flow direction, wherein in both dimensions an angle greater than 2° is arranged between the main fluid flow direction and the normal vector.

15. The method of claim 14, wherein the workpiece has a length and a width dimension each greater than 100 mm, or wherein the workpiece has a plurality of cells greater than 300, or wherein the workpiece has a plurality of cells wherein a cell size is less than 1 mm 2 is.

16. The method of claim 13, further comprising the following steps: Providing (90) input data for the workpiece, wherein the input data are designed such that the normal vector or the main fluid flow direction is parallel; Revising (91) the input data to obtain revised input data in which the normal vector to the main fluid flow direction has an acute angle; and Generating (92) the first tax data and the second tax data from the revised data.

17. A method according to any of the preceding claims, wherein the workpiece is a heat exchanger and the first structuring (31), the second structuring (32) and the third structuring (33) in a respective region (21 - 29) define the following over a plurality of successively applied layers: a first number of channels (101a, 101b, 101c) for a first fluid, extending along a first flow direction of the first fluid and in a first transverse direction, wherein the first transverse direction varies along the first flow direction; a second number of channels (102a, 102b, 102c) for a second fluid, extending along a second flow direction of the second fluid and in a second transverse direction, wherein the second transverse direction varies along the second flow direction;a wall structure (200a-200e, 202a-202d) configured such that the first number of channels and the second number of channels are in thermal interaction, and that at a first location of the heat exchanger with respect to the first or second flow direction, the first transverse direction or the second transverse direction is different from a first or second transverse direction at a second location of the heat exchanger with respect to the first or second flow direction.

18. The method of claim 17, wherein the heat exchanger has a volume in which at least 5 first channels and at least 5 second channels are arranged, wherein the wall structure (200a-200e, 202a-202d) is configured to fluidically connect the first number of channels to one another, and to fluidly connect the second number of channels to one another, and to fluidically separate the channels of the first number of channels from the channels of the second number of channels, and wherein the wall structure (200a-200e, 202a-202d) is configured such that the first number of channels and the second number of channels extend completely through the volume at the first position in the first and second transverse directions, and that the first number of channels and the second number of channels extend completely through the volume at the second position in the first and second transverse directions. where the first and second transverse directions differ at the first position from the first and second transverse directions at the second position.

19. Method according to claim 17 or 18, wherein the wall structure (200a-200e, 202a-202d) has flow-dividing sections (301, 302, 303, 304) for the first number of channels along the first transverse direction to divide a first channel of the first number of channels into several first sub-channels, and to divide a second channel of the first number of channels into several second sub-channels, or wherein the wall structure (200a-200e, 202a-202d) has flow-merging sections to merge a sub-channel with one or more other sub-channels in which either the first or the second fluid flows, to form a channel of the first or second number of channels at the first or second location.

20. Method according to claim 19, wherein the wall structure (200a-200e, 202a-202d) is configured such that the current dividing sections for dividing the first number of channels are the current merging sections for merging partial channels into a channel of the second number of channels.

21. Method according to one of claims 17 to 20, wherein the wall structure (200a-200e, 202a-202d) is designed such that between the first location where the channels of the first number of channels and the second number of channels have a horizontal transverse direction and the second location where the channels of the first number of channels and the second number of channels have a vertical transverse direction, the wall structure (200a-200e, 202a-202d) is diamond-shaped, so that a partial channel formed by a flow-dividing section borders another partial channel, through which the same fluid flows, both vertically and horizontally.

22. Method according to any one of claims 1 to 21, wherein at least one structuring from the group comprising the first structuring (31), the second structuring (32) and the third structuring (33) represents a useful structure of the workpiece, such as a number of fluid channels in the workpiece, wherein the first structuring (31), the second structuring (32) and the third structuring (33) are all different from each other.

23. Workpiece with the following features: a sequence of superimposed layers (41 - 49) of molten and cooled remelted material, wherein a first layer (41) of the sequence of superimposed layers has a first structuring (31) in a first region (21) and a second structuring (32) in a second region (22), and wherein the second layer (42) of the sequence of layers has the second structuring (32) in the first region (21) and the first structuring (31) or a third structuring (33) in the second region (22), wherein the first region (21) is different from the second region, and wherein the first structuring (31) is different from the second structuring, or the third structuring (33) is different from the first structuring (31) and the second structuring (32).

24. Workpiece according to claim 23, wherein the first layer (41) of the workpiece has the second structuring (32) or the third structuring (33) in a third region (23), and the second layer (42) has the second structuring (32) or the first structuring (31) in the third region (23), wherein the second region (22) is located between the first region (21) and the third region (23).

25. Workpiece according to claim 23 or 24, wherein the first layer (41) in a fourth region (24) has the second structuring (32), the second layer (42) of the workpiece in the fourth region (24) has the third structuring (33) or the second structuring (32) or the first structuring (31), wherein the fourth region (24) is adjacent to the first region (21).

26. Workpiece according to one of claims 23 to 25, wherein the first layer (41) of the workpiece has the third structuring (33) in a fifth region (25), and wherein the second layer (42) of the workpiece has the second structuring (32) or the first structuring (31) in the fifth region (25), wherein the fourth region (24) lies between the fifth region (25) and the first region (21).

27. Workpiece according to one of claims 23 to 26, wherein the first structuring (31) defines first channels extending in a first direction, wherein the second structuring (32) defines quadrilaterals with equal or different side lengths, and wherein the third structuring (33) defines second channels extending in a second direction that differs from the first direction.

28. Workpiece according to one of claims 23 to 27, wherein the workpiece has a sequence of layers, wherein a layer (49) at the end of a structural period has the same configuration as a layer (41) at the beginning of the structural period, wherein the first layer is located in a manufacturing direction in front of the second layer, and the second layer is located in the manufacturing direction in front of the layer (49) located at the end of the structural period.

29. Workpiece according to one of claims 23 to 28, wherein a sequence of layers of the workpiece comprises a start layer (41) at the beginning of a structural period and a finish layer (49) at the end of the structural period and between the start layer and the finish layer a second layer (42), a third layer (43), a fourth layer (44), a fifth layer (45), a sixth layer (46), a seventh layer (47) and an eighth layer (48), wherein a period angle between any two adjacent layers (41 - 49) is between 40° and 50°.

30. Workpiece according to claim 29, wherein in the first region (21) a sequence of structurings over the sequence of layers is as follows: 1 , 2, 3, 2, 1 , 2, 3, 2, 1 , or wherein in the second area (22) an order of structurings over the sequence of layers is as follows: 2, 3, 2, 1 , 2, 3, 2, 1 , 2, or wherein in a third area (23) a sequence of structurings over the sequence of layers is as follows: 3, 2, 1, 2, 3, 2, 1, 2, 3, or wherein in a fourth area (24) an order of structurings over the sequence of layers is as follows: 2, 1 , 2, 3, 2, 1 , 2, 3, 2, or wherein in a fifth area (25) an order of structurings over the sequence of layers is as follows: 3, 2, 1 , 2, 3, 2, 1 , 2, 3, or wherein in a sixth area (26) an order of structurings over the sequence of layers is as follows: 1 , 2, 3, 2, 1 , 2, 3, 2, 1 , or wherein in a seventh area (27) an order of structurings over the sequence of layers is as follows: 2, 3, 2, 1, 2, 3, 2, 1, 2, or wherein in an eighth area (28) an order of structurings over the sequence of layers is as follows: 2, 1 , 2, 3, 2, 1 , 2, 3, 2 or wherein in a ninth area (29) an order of structurings over the sequence of layers is as follows: 1, 2, 3, 2, 1, 2, 3, 2, 1, wherein the sixth area (26) lies between the fourth area (24) and the seventh area (27), or wherein the eighth area (28) lies between the fifth area (25) and the ninth area (29), or wherein the sixth area (26) lies between the second area (22) and the eighth area (28), or wherein the seventh area (27) lies between the third area (23) and the ninth area (29), and where “1” represents the first structuring (31), where “2” represents the second structuring (32) and where “3” represents the third structuring (33).

31. Method according to any one of claims 23 to 30, wherein at least one structuring from the group comprising the first structuring (31), the second structuring (32) and the third structuring (33) represents a useful structure of the workpiece, such as a number of fluid channels in the workpiece, wherein the first structuring (31), the second structuring (32) and the third structuring (33) are all different from each other.

Images