Cooling medium distributor and manufacturing process for such a

Abstract

The invention relates to an additively manufactured cooling medium distributor (1) for cooling a device (9) by distributing a cooling medium (2), wherein the cooling medium consists of at least one main cooling medium flow (4), which can be divided into at least two secondary cooling medium flows (3), wherein the main cooling medium flow (4) is divided into at least two secondary cooling medium flows (3) by external flow guide elements (5), in which fluid-mechanical, internal guide elements (6) with a length l generate a laminar flow (7) within the secondary cooling medium flows (3), which open into at least one interface region (8) of the device (9) to be cooled. The invention further relates to an additive manufacturing process for producing a cooling medium distributor (1).

Description

[0001] The invention relates to an additively producible cooling medium distributor for cooling a device by distributing a cooling medium according to claim 1. Furthermore, the invention relates to a method for producing such a cooling medium distributor according to claim 11.

[0002] Die casting is a casting process in which molten material is poured into a mold cavity under high pressure and high speed conditions, cooled, and thus formed. In conventional die casting molds, oil and / or water channels are installed in die casting tools at relatively irregular distances from the mold surface to be cooled. This means that the amount of heat transport determines the quality of the cooling homogeneity. This is exacerbated by the fact that the cooling channels are connected in series. This sometimes makes it difficult to control or regulate the temperature homogeneously according to the appearance of the product, especially when delicate geometries are involved. For example, due to the geometry, hotspots can occur during the solidification process, leading to burning of auxiliary materials on the surface and shrinkage cavities inside the component.

[0003] However, providing die-casting molds for the production of more delicate components with delicate cooling channels in accordance with the more delicate geometry would not appear to be expedient even in the optimal design, since these cooling channels, as already mentioned, are connected in series and are thus supplied with coolant one after the other.

[0004] A parallel coolant supply would rather ensure greater heat dissipation and optimize the cooling process. However, paralleling the coolant supply via branching without increasing the volume flow would result in a decrease in the flow velocity due to surface roughness. This would result in excessive heating of the temperature control medium, which would lead to either evaporation of the water or cracking of the oil. Furthermore, such a branching would significantly increase the likelihood of turbulent flow.

[0005] To address this problem, DE102012019828 proposes a temperature control device for primary or forming machines in which a multi-channel flow measuring device ensures optimization of the coolant supply to the device to be cooled.

[0006] US 8474516 describes a device for cooling a heat-generating device, in particular a heat exchanger with twisted microchannels for use in large-area cooling plates.

[0007] To achieve optimal cooling media supply, US2019360759 discloses a heat sink with permeable membrane microchannels. According to this publication, the high pressure drop associated with flow through the comparatively small channels is counteracted by designing the microchannels in membrane form.

[0008] The object of the invention is therefore to overcome the disadvantages of the prior art. This is achieved by means of an additively manufactured cooling medium distributor for cooling a device by distributing a cooling medium, wherein the cooling medium consists of at least one main cooling medium stream that can be divided into at least two secondary cooling medium streams. The main cooling medium stream is branched into at least two secondary cooling medium streams by means of external flow guide elements. Fluid-mechanical, internal guide elements with a length l generate a laminar flow within the secondary cooling medium streams, which flow into at least one interface region of the device to be cooled.

[0009] An additive manufacturing process is a manufacturing process in which a layered build-up leads to the creation of the desired component. The cooling medium can be any liquid and / or gaseous media, preferably coolants, that are suitable for heat exchange with the environment.

[0010] A cooling medium distributor is a device that can distribute or divide a cooling medium or reunite it.

[0011] A cooling medium secondary flow is a coolant flow that is carried away from or departs from a cooling medium main flow.

[0012] A flow guide element is a component which, due to its geometric shape, is suitable for influencing or possibly changing the flow of a medium in terms of fluid mechanics.

[0013] Laminar flow is a flow in which a medium, a liquid and / or a gas spreads without turbulence or cross-flow.

[0014] The interface area can be defined as the transition between the cooling medium distributor and the device to be cooled. Such an interface area can be designed, for example, as a flange connection.

[0015] The division of a cooling medium flow by such a cooling medium distributor with subsequent laminarization of the flow has the advantage that the flow velocity does not decrease during the division.

[0016] For example, if cooling medium side streams A, B, and C are identical, the total flow resistance of a hypothetical cooling medium main stream decreases. With Δp as the pressure difference and ρ as the density of the coolant main stream, as well as ξ as the flow resistance and w m2 as flow velocity is Δp=ρ⋅ξ⋅Wm22 to: 1ξTotal=3ξA ξTotal=19:ξA

[0017] If the pressure drop remains the same and the flow resistance is only one-ninth, the volume flow must triple. Due to the quadratic relationship, a factor of 9 is achieved, and the pressure drop remains the same. Consequently, a larger volume flow can be directed through the area to be cooled.

[0018] Preferably, the fluid-mechanical inner guide elements are designed as parallel grids with a length l and a diameter d.

[0019] Through the use of an additive manufacturing process, such a grating can have a defined length l that runs parallel to the coolant flow. Using an additive melting process, such a grating can be generated relatively cost-effectively, for example, by laser beam melting, as an internal structure within a coolant distributor. A minimum length exists for the grating, which ensures the transition from turbulent to laminar flow.

[0020] Preferably, the ratio between diameter d and length l of the fluid-mechanical inner guide elements is 1:8, particularly preferably 1:10.

[0021] At least partial laminarization of the flowing medium occurs with a grid length of five times the flow diameter. This neutralizes turbulence caused by inflow effects. From a ratio of 1:8, complete laminarization of the flowing medium occurs. From a grid length of ten times the flow diameter, a coolant flow is generated that remains stably laminar over longer distances. It has been shown that placing a temperature control unit between the device to be cooled and the coolant distributor is particularly beneficial for design simplicity.

[0022] However, another design variant allows for a temperature control unit to be installed between the device to be cooled and the cooling medium distributor. This is more complex in terms of construction, but a more compact design.

[0023] This can be used to supply coolant to die-casting and injection-molding machines, for example. However, its use in metal forming technology for cooling press tools can also ensure optimized cooling of these tools.

[0024] Using the additive manufacturing process described, cooling medium distribution units in particular can be manufactured even in the micrometer range, which means they can also be used as cooling medium distributors in the field of computer cooling.

[0025] Such additively manufactured structures can be generated with layer thicknesses < 40 µm.

[0026] Of course, a cooling medium can also be divided upstream of a temperature control unit using a cooling medium distributor, in order to then cool the cooling medium down within a temperature control unit and then feed it into the device to be cooled.

[0027] According to a further preferred embodiment, the surface roughness of the inside of the cooling medium distributor exposed to the cooling medium side streams is between R a 0.2 and 200 preferably R a 0.2 and 2. The surface roughness of the inside of the cooling medium distributor is the decisive parameter for the dimensioning of the grid in the longitudinal direction. Using a conventional machine for the additive generation of such a cooling medium distributor, it is then possible to find an optimal ratio between the length of the cooling medium distributor and the surface roughness, depending on the geometry of the cooling medium distributor. For example, with a surface roughness of R a 0.2 six times the diameter of the inside of a branch of the cooling medium distributor.

[0028] It was found that the higher the surface roughness of the inside of the cooling medium distributor was estimated, the longer the length of the laminarization element increased.

[0029] According to another preferred embodiment, the outer flow guide elements are tubular. While the grid-shaped guide elements inside should correspond to the previously defined designs in terms of their dimensions and design, the outer flow guide elements can be designed as conventional tubular structures, which contributes in particular to reducing manufacturing costs. The outer flow guide elements are defined as those areas and surfaces of the cooling medium distributor that are not in contact with the cooling medium, but rather form the outer casing of the laminarization element and ultimately ensure the low-loss transport of the cooling medium.

[0030] Taking additive manufacturing into account, the outer geometry of the outer flow guide elements is hexagonal in the area of ​​the fluid-mechanical inner guide elements. This has the advantage that the inner flow guide elements with a hexagonal structure utilize the available cross-section most efficiently.

[0031] Another advantageous design is one in which the main cooling medium flow is divided into three secondary cooling medium flows by the tubular outer flow guide elements. This has the advantage of creating a particularly preferred ratio between the structural volume and the flow-through internal surface.

[0032] In order to achieve an optimal cooling medium flow, the internal structure of the cooling medium distributor should achieve or enable a Reynolds number below 4000, preferably below 2300, due to its geometry.

[0033] The problem mentioned at the beginning is also solved by an additive manufacturing process for producing a coolant distributor of the type described above. Possible additive manufacturing processes are BJT (free jet binder deposition), DED (directed energy deposition), MEX (material extrusion), MJT (free jet material deposition), PBF (powder-based melting), SHT (layer lamination), VPP (bath-based photopolymerization). The use of an additive manufacturing process has the advantage that "internal" geometries can be created easily and at a comparatively low cost. When using a powder-based melting process, for example, a powder bed is melted by laser according to the geometry of the coolant distributor in such a way that the melted areas combine to form a coolant distributor as described above, thus creating a coolant distributor layer by layer.

[0034] The invention is explained in more detail below using examples and accompanying figures. This serves solely to illustrate the invention without limiting its generality. Fig. Figure 1 shows an overview of the functionality of the cooling medium distributor as an intermediary between the device to be cooled and a heat exchanger unit (temperature control unit). Fig. 2 shows the external view of a cooling medium distributor according to the invention with laminarization area next to the associated connecting piece that reunites the cooling medium flow. Fig. 3 illustrates a sectional drawing of the cooling medium distributor in the area of ​​the grid structures designed as flow guide elements. Out of Fig. Figure 4 shows a schematic diagram of the coolant flow through the areas designated by the outer guide elements with turbulent flow of the coolant distributor and the subsequent transfer into the laminarization area.

[0035] It describes Fig. 1 a basic diagram of the use of the cooling medium distributor (1) which distributes the cooling medium main flow (4) from a temperature control device (11) through the cooling medium distributor (1) into several cooling medium secondary flows (3) in an interface area (8) in a device (9) to be cooled and there directs the thermal energy by convective energy transfer into a return flow, which in turn is returned to the temperature control device (11).

[0036] Fig. Figure 2 shows an exemplary external appearance of the cooling medium distributor (1) as well as another connection piece for the previously described cooling medium return. The main cooling medium flow is branched by external tubular flow guide elements (5).

[0037] In Fig. Figure 3 shows an exemplary sectional view of the inner guide elements (6) used to laminarize the cooling medium. As a special design variant, the guide elements (6) designed as a grid (10) are hexagonal. Starting from an interface area (8), a main cooling medium flow is divided into three cooling medium secondary flows by the outer tubular flow guide elements (5) and guided through the grid-shaped guide elements (6).

[0038] Fig.Figure 4 shows a cooling medium (2) which, after flowing through an interface region (8), is divided from a main cooling medium flow (4) into several secondary cooling medium flows (3) by external flow guide elements (5). Initially, the flow describes a turbulent flow, which in turn is converted into a laminar flow (7) by the internal guide elements (6) designed as a grid (10). The medium flows through the inner surfaces of the inner guide elements with a specific surface roughness (12). Position number list 1 cooling medium distributor 2 Cooling medium 3 cooling media side streams 4 Cooling medium main flow 5 Outer flow guide elements 6 Inner guiding elements 7 Laminar flow 8 Interface area 9 Device to be cooled 10 grids 11 Temperature control device 12 Surface roughness exposed to the cooling medium QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102012019828

[0005] US 8474516

[0006] US 2019360759

[0007]

Claims

[1] Additively producible cooling medium distributor (1) for cooling a device (9) by distributing a cooling medium (2), wherein the cooling medium consists of at least one cooling medium main flow (4) which can be divided into at least two cooling medium secondary flows (3), wherein a branching of the cooling medium main flow (4) into at least two cooling medium secondary flows (3) takes place by external flow guide elements (5), characterized by that fluid-mechanical, inner guide elements (6) with a length l generate a laminar flow (7) within the cooling medium secondary flows (3), which flow into at least one interface region (8) of the device (9) to be cooled. [2] Cooling medium distributor (1) according to the preceding claim characterized by that the fluid-mechanical inner guide elements (6) are designed as parallel grids (10) with a length l and a diameter d. [3] Cooling medium distributor (1) according to one of the preceding claims characterized bythat the ratio between diameter d and length l of the fluid-mechanical inner guide elements (6) is 1:8, preferably 1:10: [4] Cooling medium distributor (1) according to one of the preceding claims characterized by that a cooling medium distributor (1) is arranged between the device to be cooled (9) and the temperature control device (11). [5] Cooling medium distributor (1) according to one of the preceding claims 1-3 characterized by that a temperature control device (11) is arranged between the device to be cooled (9) and the cooling medium distributor (1). [6] Cooling medium distributor (1) according to one of the preceding claims characterized by that the surface roughness (12) exposed to the cooling medium side streams (3) is between R a 0.2 and 200 preferably between R a 0.2 and 2. [7] Cooling medium distributor (1) according to one of the preceding claims characterized by that the outer flow guide elements (5) are tubular. [8] Cooling medium distributor (1) according to one of the preceding claims characterized by that the outer geometry of the outer flow guide elements (5) in the region of the fluid-mechanical inner guide elements (6) is hexagonal. [9] Cooling medium distributor (1) according to one of the preceding claims characterized by that the cooling medium main flow (4) is divided into three cooling medium secondary flows (3). [10] Cooling medium distributor according to one of the preceding claims characterized by that the Reynolds number resulting for the cooling media side streams (4) is below 4000, preferably below 2300, due to the surface roughness. [11] Additive manufacturing method for producing a cooling medium distributor (1) according to one of the preceding claims.

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