Cooling medium distributor and method for manufacturing same

Abstract

The invention relates to a cooling medium distributor (1), which can be produced by additive manufacturing, for cooling a device (9) by distributing a cooling medium (2), the cooling medium consisting at least one cooling medium main flow (4) that can be divided into at least two cooling medium bypass flows (3), wherein the cooling medium main flow (4) is branched into at least two cooling medium bypass flows (3) by outer flow guide elements (5), in which fluid-mechanical inner guide elements (6) having a length l, generate a laminar flow (7) within the cooling medium bypass flows (3), which each open into at least one interface region (8) of the device (9) to be cooled. The invention also relates to an additive manufacturing method for manufacturing a cooling medium distributor (1).

Description

[0001] Cooling medium distributor and manufacturing process for such a

[0002] The invention relates to an additively manufactured cooling medium distributor for cooling a device by distributing a cooling medium according to claim 1. The invention also relates to a method for manufacturing such a cooling medium distributor according to claim 11.

[0003] Die casting is a casting process in which a molten material is injected into a mold cavity under high-pressure and high-speed conditions, cooled, and thus shaped. In conventional die casting molds, oil and / or water channels are integrated into the die casting tool. These channels are positioned at relatively irregular distances from the mold surface to be cooled, so the amount of heat dissipation determines the homogeneity of the cooling process. This is exacerbated by the fact that the cooling channels are arranged in series. Consequently, it can sometimes be difficult to control or regulate the temperature homogeneously according to the desired appearance of the product, especially when dealing with intricate geometries. As a result, geometrically determined hotspots can occur during the solidification process, leading to surface burns and shrinkage cavities within the component.

[0004] However, equipping die-casting molds for the production of more delicate components with delicate cooling channels corresponding to the more delicate geometry would not be effective even in the optimal design, since these cooling channels, as already mentioned, are "connected in series" and thus supplied with coolant one after the other.

[0005] A parallel coolant supply would ensure simultaneous heat dissipation and optimize the cooling process. However, parallelizing the coolant supply by branching it would cause the flow velocity to decrease due to surface roughness. This would result in a reduction of the desired simultaneous heat removal, but at the expense of the overall heat removal rate. Furthermore, such branching would increase the turbulence of the flow, further reducing the flow velocity and convective heat removal. To address this issue, DE2012019828 proposes a temperature control device for primary or secondary forming machines, in which a multi-channel flow measurement device optimizes the coolant supply to the device being cooled.

[0006] US patent 8474516 describes a device for cooling a heat-generating device, in particular on a heat exchanger with coiled 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 the flow through the comparatively small channels is countered by designing the microchannels in membrane form.

[0008] DE102018119730 discloses a line for hydraulic fluids through which hydraulic fluid is guided by a hydraulic fluid control agent in order to prevent the dangers associated with parts that could vibrate loose.

[0009] The purpose of the invention is therefore to overcome the disadvantages of the prior art described above.

[0010] This is achieved by an additively manufactured cooling medium distributor for cooling a device by distributing a cooling medium, wherein the cooling medium consists of at least one cooling medium secondary stream, which can be divided into at least two cooling medium secondary streams, wherein the main cooling medium stream is divided into at least two cooling medium secondary streams by external flow guide elements, and fluid-mechanical, internal guide elements with a length I generate a laminar flow within the cooling medium secondary streams, which open into at least one interface area of ​​the device to be cooled.

[0011] An additive manufacturing process is a manufacturing process in which a layer-by-layer build-up leads to the production of the desired component. A cooling medium can be any liquid and / or gaseous media, preferably cooling agents, that are suitable for heat exchange with the environment. A cooling medium distributor is a device that distributes or distributes a cooling medium.

[0012] A coolant bypass flow is a coolant flow that is diverted from, or originates from, a main coolant flow. A flow guide element is a component whose geometric shape is suitable for influencing or potentially altering the flow of a medium through fluid mechanics.

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

[0014] The interface area can be defined as the transition between the cooling medium distributor and the device being cooled. Such an interface area can, for example, be implemented as a flange connection. Dividing the cooling medium flow by such a distributor, followed by laminarization, has the advantage that the flow velocity does not decrease during the division process.

[0015] For example, if cooling media bypass flows A, B and C are identical, the total flow resistance of a hypothetical

[0016] Main cooling media flow

[0017] With Ap as pressure difference and p as density of the main coolant flow as well as as flow resistance and as flow velocity to:

[0018] To ensure that the pressure drop remains constant and the flow resistance is only one-ninth, the volume flow rate must triple. Due to the quadratic relationship, this results in a factor of 9, and the pressure drop remains unchanged. Consequently, a larger volume flow rate can be passed through the area to be cooled.

[0019] Preferably, the fluid-mechanical inner guiding elements are designed as parallel grids with a length I and a diameter d.

[0020] Such a grid, through the use of an additive manufacturing process, can have a defined flowable area parallel to the

[0021] The cooling medium flow must have a length I. Such a grid can be generated relatively cost-effectively as an internal structure within a cooling medium distributor, for example, using laser beam melting, via an additive melting process. The grid has a minimum length that ensures the transition from turbulent to laminar flow.

[0022] Preferably, the ratio between diameter d and length I of the fluid-mechanical inner guiding elements is 1 :8, particularly preferably 1 :10.

[0023] Partial laminarization of the flowing medium occurs when the grid length is five times the flow diameter. This primarily neutralizes turbulence caused by inflow effects. Complete laminarization of the flowing medium occurs at a ratio of 1:8. At a grid length of ten times the flow diameter, a coolant flow is generated that remains stably laminar over longer distances.

[0024] According to another preferred embodiment, a cooling medium distributor is arranged between the device to be cooled and the temperature control unit.

[0025] A conventional design variant will rely on an arrangement in which a temperature control unit is placed between the cooling medium distribution unit and the device to be cooled.

[0026] This can be used, for example, to supply coolant to die-casting and injection molding machines. Furthermore, its use in metal forming technology for cooling press tools can optimize the cooling function of these tools.

[0027] The described additive manufacturing process allows for the production of cooling medium distribution units, even in the micrometer range, making them suitable for use as cooling medium distributors in computer cooling systems. Such additively manufactured structures can be produced with layer thicknesses of less than 40 pm.

[0028] Of course, a cooling medium can also be divided by means of a cooling medium distributor in front of a temperature control unit, in order to then cool the cooling medium within a temperature control unit, in order to then be directed into the device to be cooled.

[0029] According to another preferred embodiment, the surface roughness of the inside of the cooling medium distributor exposed to the cooling medium bypass currents is between R a 0.2 and 200.

[0030] The surface roughness of the inside of the cooling medium distributor is the decisive parameter for dimensioning the grid in the longitudinal direction. Using a conventional machine for the additive manufacturing of such a cooling medium distributor, an optimal ratio between the length of the cooling medium distributor and the surface roughness must then be found, depending on the geometry of the cooling medium distributor. Preferably, this ratio is, for example, at a surface roughness of R a 0.2 is six times the diameter of the inside of a branch of the cooling medium distribution.

[0031] It was found that the higher the surface roughness of the inside of the cooling medium distributor was estimated, the longer the laminarization element became.

[0032] In another preferred embodiment, the outer flow guide elements are tubular. While the internal grid-like guide elements should correspond to the previously specified embodiments in terms of their dimensions and design, the outer flow guide elements can be implemented as conventional tubular structures, which particularly contributes to reducing manufacturing costs. The outer flow guide elements are defined as those areas and surfaces of the cooling medium distributor that do not come into contact with the cooling medium, but rather form the outer casing of the laminar flow elements and ultimately ensure the loss-free transport of the cooling medium.

[0033] Considering additive manufacturing, the outer geometry of the outer flow guide elements in the area of ​​the fluid-mechanical inner guide elements is hexagonal. This has the advantage that the inner flow guide elements can be easily generated additively. Furthermore, the hexagonal geometry is preferable with regard to the ratio of installation volume to the flow-through inner surface area. An additional advantage is a design in which the main coolant flow is divided into three secondary coolant flows through the tubular outer flow guide elements. This has the advantage of creating a particularly favorable ratio between installation volume and flow-through inner surface area.

[0034] To obtain an optimal cooling medium flow, the internal structure of the cooling medium distributor should, due to its geometry, achieve or enable a Reynolds number below 4000, preferably below 2300.

[0035] The aforementioned task is also solved by an additive manufacturing process for the production of a cooling medium distributor of the type described above.

[0036] Additive manufacturing processes are used in this context

[0037] BJT (free-jet binder deposition), DED (directed energy deposition), MEX (material extrusion), MJT (free-jet material deposition), PBF (powder-based melting), SHT (layer lamination), and VPP (bath-based photopolymerization) are all considered. The use of an additive manufacturing process has the advantage that "internal" geometries can be produced easily and at a comparatively low cost. For example, when using a powder-based melting process, a powder bed is melted by a laser according to the geometry of the cooling medium distributor, such that the molten areas fuse together to form the cooling medium distributor described above, creating a cooling medium distributor layer by layer.

[0038] The invention is explained in more detail below with reference to examples and accompanying illustrations. This serves solely to illustrate the invention without limiting its generality.

[0039] FIG 1 shows an overview of the operation of the cooling medium distributor as an intermediary between the device to be cooled and a heat exchanger unit (temperature control unit).

[0040] FIG 2 shows the external view of a cooling medium distributor according to the invention with a laminarization area next to the associated connecting piece which reunites the cooling medium flow.

[0041] FIG 3 illustrates a sectional drawing of the cooling medium distributor in the area of ​​the grid structures designed as flow guide elements.

[0042] FIG 4 shows a schematic guide 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.

[0043] FIG 1 describes a basic scheme for the use of the cooling medium distributor (1) which distributes the main cooling medium flow (4) from a temperature control unit (11) through the cooling medium distributor (1) into several secondary cooling medium flows (3) in an interface area (8) into a device (9) to be cooled, where the heat energy is transferred via convective energy transfer into a return flow, which is then returned to the temperature control unit (11).

[0044] FIG 2 shows an exemplary external appearance of the cooling medium distributor (1) and a further connection piece for the previously described return of the cooling medium. The main cooling medium flow is branched by external tubular flow guide elements (5).

[0045] Figure 3 shows an exemplary sectional view of the inner guide elements (6) used for laminarizing the cooling medium. As a special embodiment, the guide elements (6), designed as a grid (10), are hexagonal in shape. Starting from an interface area (8), a main cooling medium flow is divided into three secondary cooling medium flows by the outer tubular flow guide elements (5) and directed through the grid-shaped guide elements (6).

[0046] FIG 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 means of external flow guide elements (5), and initially describes a turbulent flow, which in turn is converted into a laminar flow (7) by the inner 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).

[0047] List of position numbers

[0048] I Cooling medium distributor 2 Cooling medium

[0049] 3 cooling media bypass streams

[0050] 4 Main cooling medium flow

[0051] 5 external flow guide elements

[0052] 6 internal guide elements 7 laminar flow

[0053] 8 Interface area

[0054] 9 device to be cooled

[0055] 10 grids

[0056] II Temperature control unit 12 Surface roughness exposed to the cooling medium

Claims

Patent claims 1. 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 cooling medium secondary stream (3) and a cooling medium main stream (4), which can be divided into at least two cooling medium secondary streams (3), wherein the cooling medium main stream (4) is divided into at least two cooling medium secondary streams (3) by external flow guide elements (5), characterized in that fluid-mechanical, internal guide elements (6) with a length l generate a laminar flow (7) within the cooling medium secondary streams (3), which open into at least one interface area (8) of the device (9) to be cooled.

2. Cooling medium distributor (1) according to the preceding claim characterized in that the fluid-mechanical inner guide elements (6) are designed as parallel grids (10) with a length I and a diameter d.

3. Cooling medium distributor (1) according to one of the preceding claims characterized in that 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 in that a cooling medium distributor (1) is arranged between the device (9) to be cooled and the temperature control unit (11).

5. Cooling medium distributor (1) according to one of the preceding claims 1-3 characterized in that a temperature control device (11) is arranged between the device (9) to be cooled and the cooling medium distributor (1).

6. Cooling medium distributor (1) according to one of the preceding claims, characterized in that the surface roughness (12) exposed to the cooling medium by-flows (3) is between R a 0.2 and 200 preferably between Ra 0.2 and 2.

7. Cooling medium distributor (1 ) according to one of the preceding claims characterized in that the outer flow guide elements (5) are tubular in shape.

8. Cooling medium distributor (1) according to one of the preceding claims characterized in that the outer geometry of the outer flow guide elements (5) in the area of ​​the fluid-mechanical inner guide elements (6) is hexagonal.

9. Cooling medium distributor (1 ) according to one of the preceding claims characterized in that the main cooling medium flow (4) is divided into three secondary cooling medium flows (3).

10. Cooling medium distributor according to one of the preceding claims characterized in that the Reynolds number resulting for the cooling medium by-flows (4) is set below 4000, preferably below 2300, due to surface roughness.

11. Additive manufacturing process for the production of a cooling medium distributor (1) according to one of the preceding claims. II

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