Mold apparatus with cooling structure for casting system

Abstract

The present invention provides a cooling structure that can improve the heat dissipation capacity of molds used in casting, such as die casting. [Solution] The casting system has a mold 2 in which a cavity is defined into which molten metal is poured and a casting is formed. The apparatus 1 has a pool structure 2b which is recessed from the outside of the mold toward the cavity side 2a. The apparatus has an embedded member 3 which is placed inside the pool structure and has an outer shape which is generally complementary to the inner shape, and defines a surface channel 5 through which a cooling medium can flow between the inner surface of the pool structure and the surface opposite it. Inside the embedded member there is an internal channel 6 which sends the cooling medium from the outside of the embedded member to the surface channel. The internal channel has an inlet 8 for the cooling medium to flow into it and an outlet 9 for the cooling medium to flow out from the surface channel, and is configured to cool by circulating the cooling medium through the surface channel.

Description

Technical Field

[0001] The present invention relates to a mold of a casting system using a die-casting method or the like, and more particularly to a cooling structure in the mold of the casting system.

Background Art

[0002] Regarding a structure in which cooling water is circulated inside a mold used in a casting system by a casting method such as a die-casting method for casting a molded product made of a metal (such as an aluminum alloy) having a complex shape to cool the temperature of the mold, various configurations have been proposed. For example, in Patent Document 1, a hollow pipe is inserted into a straight hole drilled linearly from the outside to the inside of the mold, and the inner wall of the hole, the hollow pipe, and a heat transfer member are connected via a heat transfer member. A cooling hole structure is configured such that a cooling medium passes through the inside of the hollow pipe, reaches the tip of the hole, and then flows out of the mold through the space between the hole and the hollow pipe. A structure in which a plurality of such cooling hole structures are provided in the mold has been proposed (see FIG. 5).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in casting processes such as die casting, the casting cycle time has been shortened to improve productivity. Furthermore, in the case of large body parts such as Gigacast, the amount of material to be cast increases, leading to increased heat input, and the complex shape makes cooling the mold more difficult. Consequently, as the mold deheating time decreases and the mold temperature rises, defects such as seizing / galling in the cast material and heat cracks due to thermal fatigue of the mold can occur. Therefore, it is desirable to be able to cool the mold more effectively. In this regard, in the case of a cooling structure such as the linear cooling holes 20 drilled in the mold 2 as shown in Figure 5, even if one tries to increase the number of cooling holes to increase the cooling capacity, cracks are more likely to occur between the holes, and the number of parts such as sealing parts 21 to prevent cooling water leakage increases, resulting in poor maintainability. Therefore, there is a limit to the number of cooling holes that can be formed in the mold, and thus a limit to the heat deheating capacity.

[0005] In view of the above circumstances, the main object of the present invention is to provide a cooling structure that can improve the heat dissipation capacity of a mold used in casting by die casting or the like.

[0006] In this regard, by creating a recessed shape on the opposite side of the mold (the outside of the mold) from the cavity side (the side where the molded object is formed) into which the molten metal is injected, the thickness of the mold can be reduced. Furthermore, if the cooling medium flows in and out of the recessed space (referred to as the pool structure) along the mold surface within the pool structure, the heat from the mold will be transferred sequentially to the cooling medium that comes into contact with the mold surface, and it is expected that the deheating of the mold will be achieved more effectively. To this end, it is preferable to form a flow path for the cooling medium to flow quickly along the mold surface within the pool structure. This finding is utilized in the present invention. [Means for solving the problem]

[0007] According to one aspect of the present invention, the above problem is solved by a casting system having a mold in which a cavity is defined into which molten metal is poured and a casting is formed, In the aforementioned mold, a pool structure is formed that is recessed from the outside toward the cavity side. The embedded member is placed within the pool structure, has an outer shape that is generally complementary to the inner shape of the pool structure, and defines a surface channel through which a cooling medium can flow between the inner surface of the pool structure and the surface opposite it. An internal channel is formed inside the embedded member to deliver a cooling medium from outside the embedded member to the surface channel. An inlet for introducing a cooling medium into the internal flow path and an outlet for releasing the cooling medium from the surface flow path are provided. This is achieved by a device configured to cool by circulating a cooling medium through the aforementioned surface channel.

[0008] In the above configuration, the "mold" may be a mold used in a casting system that forms a casting shaped like a cavity from molten metal using any casting method such as vacuum die casting or die casting, and may be made of a material commonly used in this field, such as SKD steel. The cavity side is the side into which the molten metal is injected, and the outside is the side opposite the cavity side. In this mold, in the present invention, as a structure for cooling, first, a pool structure is formed that is recessed from the outside of the mold toward the cavity side, that is, a shape that is like the outside of the mold has been hollowed out. Such a pool structure is not the conventional structure of straight-lined cooling holes, but rather the outside of the mold may be recessed toward the cavity side in an arbitrary shape over a wider area so that the mold as a whole becomes thinner. Within the pool structure, as described above, an embedded member is formed with an outer shape that is generally complementary to the inner shape of the pool structure, defining a surface channel through which a cooling medium can flow between the inner surface of the pool structure and the surface opposite it. Inside the embedded member, an internal channel is formed to deliver the cooling medium from the outside to the surface channel, and an inlet for the cooling medium to flow into the internal channel and an outlet for the cooling medium to flow out from the surface channel are provided in any manner. Thus, in the above configuration, the cooling medium flows through the internal passage to the surface channel, thereby cooling the mold. The cooling medium may typically be water. The embedded member may be made of any material that can withstand the heat transmitted from the mold, and may typically be made of ABS resin, various engineering plastics, or super engineering plastics. Alternatively, the embedded member may be made of metal. The thickness of the surface channel (the distance between the inner surface of the pool structure and the surface of the embedded member) may be determined experimentally (for example, it may be 1 mm to 5 mm, but is not limited thereto).

[0009] According to the above structure, as already mentioned, the cooling medium flows through the surface channel formed between the surface of the mold and the surface of the embedded member in the pool structure. As a result, new cooling medium comes into sequential contact with the surface of the mold pool structure, and heat from the mold is successively transferred to the cooling medium, which is expected to lead to better deheating of the mold.

[0010] In the mold configuration of the present invention described above, preferably, the shape of the pool structure may be shaped to generally conform to the shape of the cavity. This is expected to create surface channels for the cooling medium along the shape of the cavity, allowing heat to be absorbed more effectively from the cavity to the cooling medium overall. The shape of the pool structure may be shaped such that the thickness of the wall portion between the inner surface of the pool structure and the cavity surface is as generally equal as possible overall, so that heat is transferred to the cooling medium evenly from as much of the cavity surface as possible. In this case, the thickness of the wall portion between the inner surface of the pool structure and the cavity surface is preferably thick enough not to cause the mold to crack, and is also a thickness that allows for better heat transfer, and may be determined experimentally (for example, the thickness of the wall portion may be 10 to 15 mm, but is not limited thereto).

[0011] In the mold pool structure of the present invention described above, if there are recessed areas compared to the surrounding area, the cooling medium tends to accumulate in such recessed areas. Therefore, in order to prevent the accumulation of the cooling medium, ejection holes for the cooling medium from the internal flow path may be formed on the surface of the embedded member facing the recessed area in the pool structure. With this configuration, the cooling medium is sprayed onto the recessed area, generating a flow of the cooling medium and preventing its accumulation.

[0012] Furthermore, in the mold pool structure of the present invention described above, if there is a part that needs to be cooled more strongly than the surrounding area, a cooling medium ejection hole from the internal flow channel may be formed on the surface of the embedded member facing the part that needs to be cooled more strongly. With this configuration, the cooling medium at a lower temperature from the internal flow channel is directly sprayed onto the part that needs to be cooled more strongly, so that heat can be removed more effectively from the part that needs to be cooled more strongly.

[0013] The embedded member in the mold of the present invention described above has an outer shape that is generally complementary to the inner shape of the pool structure, and has an internal flow channel formed inside, so it can be suitably formed by a 3D printer. Accordingly, in the method for forming the embedded member of the mold described above, the embedded member may be formed by a 3D printer. As for the 3D printer, when the embedded member is manufactured from resin, a resin-based 3D printer is used at low cost, but a metal-based 3D printer may also be used. The embedded member may also be manufactured by cutting or electrical discharge machining, and in that case as well, it falls within the scope of the present invention.

[0014] An inlet for introducing the cooling medium into the internal flow path and an outlet for releasing the cooling medium from the surface flow path may be provided in any manner in the embedded member or between the mold and the embedded member. In this regard, in the present invention, a pair of inlets and outlets may be provided, and the structure may be such that the space between the inlet and outlet is branched into multiple flow paths inside the embedded member. Accordingly, only one sealing structure for the cooling medium around the inlet and outlet is needed for each of the inlets and outlets, which is advantageous in that the number of sealing structures is reduced compared to the conventional method of providing a sealing structure at the inlet and outlet of each individual cooling hole. [Effects of the Invention]

[0015] Thus, in the structure of the apparatus comprising the mold and the embedded member of the present invention, the cooling medium discharged from the internal passage of the embedded member circulates over substantially the entire surface of the mold pool structure defining the cavity. As a result, the mold is cooled overall by the cooling medium, and it is expected that the mold's heat dissipation capacity will be improved compared to conventional methods. The configuration of the present invention may be applied to various casting systems.

[0016] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic cross-sectional view of a device (mold device) consisting of a mold and an embedded member according to this embodiment. [Figure 2] Figure 2(A) is a schematic cross-sectional view of the mold in the mold apparatus of this embodiment. Figure 2(B) is a schematic perspective view of the embedded member in the mold apparatus of this embodiment. [Figure 3] Figures 3(A) to 3(C) are schematic cross-sectional views of a portion of the mold, magnified. (A) shows the case where the mold wall thickness is appropriate, (B) shows the case where the mold wall thickness is too thick, and (C) shows the case where the mold wall thickness is too thin. [Figure 4] Figures 4(A) and 4(B) are schematic cross-sectional views of the vicinity of a recessed area in the mold pool structure. (A) shows the case where no cooling medium ejection holes are formed on the surface of the embedded member facing the recessed area, and (B) shows the case where cooling medium ejection holes are formed on the surface of the embedded member facing the recessed area. Figure 3(C) is a schematic cross-sectional view of the vicinity of a part of the mold that is to be strongly cooled. Cooling medium ejection holes are formed on the surface of the embedded member facing the part that is to be strongly cooled. [Figure 5] Figure 5 is a schematic cross-sectional view of a mold in which conventional linear cooling holes are formed. [Explanation of symbols]

[0018] 1... Mold device, 2... Mold, 2a... Cavity side surface, 2b... Pool structure, 2c... Inner surface of the pool structure, 3... Embedded member, 3a... Outer surface of the embedded member, 5... Surface passage, 6... Internal passage, 6a... Ejection hole, 7... Cooling plate, 7a... Fastening bolt, 8... Inlet, 8a... Cooling medium inlet, 9... Outlet, 9a... Cooling medium outlet, 10... Seal structure, 20... Cooling hole (prior art), 21... Seal structure (prior art)

Best Mode for Carrying Out the Invention

[0019] Configuration of the mold apparatus The configuration according to this embodiment is applied to a mold device composed of a mold used in a casting system for forming a casting in the shape of a cavity from molten metal using an arbitrary casting method such as the vacuum die-casting method or the die-casting method, and its cooling structure. As shown in FIGS. 1, 2(A), and (B), in the mold device 1 according to this embodiment, there are a mold 2 that defines a cavity into which molten metal is injected, and an embedded member 3 disposed inside a pool structure 2b formed in a shape that is recessed from the outside of the mold toward the cavity side on the outside of the mold 2 (the side opposite to the surface 2a on the cavity side).

[0020] The mold 2 may be a mold formed of a material commonly used in this field, such as SKD steel material used in a casting method such as the die-casting method. On the outside of such a mold 2, in the case of this embodiment, for its cooling, a pool structure 2b having a shape like cutting out the thick part of the mold from the outside of the mold as described above is formed. The pool structure 2b may be formed as a depression that widely cuts out the entire outside of the mold 2 as shown in the drawing. Further, preferably, the surface 2c of the pool structure 2b may be formed in a shape that resembles the surface shape on the cavity side, that is, the surface shape of the casting. This pool structure 2b can be formed, for example, by cutting or electrical discharge machining on the outside of the mold 2.

[0021] The embedded member 3 may be positioned inside the pool structure 2b of the mold 2, fixed to a cooling plate 7 with fastening bolts 7a or the like, as shown in the figure, so as to seal the pool structure 2b from the outside of the pool structure 2b. In the embedded member 3, the outer surface 3a facing the surface 2c of the pool structure 2b is shaped to be generally complementary to the inner shape of the pool structure 2b, and is formed so as to define a surface channel 5 through which the cooling medium can flow between it and the inner surface 2c of the pool structure. In addition, an internal passage 6 is formed inside the embedded member 3, which allows the cooling medium flowing in from outside the embedded member 3 to flow out through an ejection hole 6a to the surface channel 5. The internal passage 6 of the embedded member 3 communicates with a receiving inlet 8a for the cooling medium via an inlet 8 formed on the surface in contact with the cooling plate 7, and as a result, the cooling medium received at the receiving inlet 8a flows through the internal passage 6 along the arrow in the figure, flows out through the ejection hole 6a to the surface channel 5, and flows over the inner surface 2c of the pool structure 2b. Furthermore, the internal passage 6 may branch into multiple inlets 8, and ejection holes 6a may be formed in each branched internal passage on the outer surface 3a of the embedded member 3. The embedded member 3 may also be provided with an outlet 9 that receives the cooling medium from the surface passage 5 and discharges it to the outside of the embedded member 3. The outlet 9 may be connected to a cooling medium outlet 9a formed in the cooling plate 7. In addition, any type of seal structure 10 may be applied to the inlet 8 and outlet 9 to prevent leakage of the cooling medium to the contact surface between the embedded member 3 and the cooling plate 7. In the configuration of this embodiment, there may be only one inlet 8 and one outlet 9, which is advantageous in that the number of seal structures 10 can be reduced compared to a conventional mold with multiple cooling holes (Figure 5). However, there may be multiple inlets 8 and outlets 9, and such cases also fall within the scope of this embodiment.

[0022] As described above, the cooling medium flows through the surface channel 5 defined between the surface 2c of the pool structure 2b of the mold 2 and the outer surface 3a of the embedded member 3. This allows new, low-temperature cooling medium to come into contact with a wide area of ​​the mold 2 sequentially, and is expected to achieve heat removal from a wide area of ​​the mold 2. In particular, if the inner surface 2 of the pool structure 2b is formed to resemble the shape of the cavity, heat is transferred more evenly from the cavity surface to the cooling medium flowing through the surface channel 5, resulting in better cooling of the mold 2.

[0023] In the mold apparatus 1 of the above embodiment, the wall thickness of the mold 2 may be adjusted to be substantially uniform along the shape of the cavity, thereby enabling more uniform cooling. In this regard, as schematically depicted in Figures 3(A) to (C), if the wall thickness δ of the mold 2 is too thick, as in Figure 3(B), good heat removal will not be achieved, and if the wall thickness δ of the mold 2 is too thin, as in Figure 3(C), cracks Cr are likely to occur in the mold 2. Therefore, it is preferable to set the wall thickness δ of the mold 2 to a thickness that allows for good heat removal and has sufficient strength to prevent cracking, as in Figure 3(A). In some examples, the wall thickness δ of the mold 2 may be 10 to 15 mm, but is not limited thereto.

[0024] The thickness of the surface channel 5, that is, the distance between the inner surface 2c of the pool structure 2b and the surface 3a of the embedded member 3, may be adjusted as appropriate through experiments, etc., so that the cooling medium flows smoothly and a flow rate that allows for good heat removal from the mold is obtained. In some examples, the thickness of the surface channel 5 may be, for example, 1 mm to 5 mm, but is not limited thereto. In order to suppress uneven heat removal from the mold, it is preferable that the shape of the surface 3a of the embedded member 3 is shaped to be as complementary as possible to the inner shape of the pool structure 2b, as shown in Figures 1 and 2(B). The cooling medium may typically be water.

[0025] As mentioned in the summary of the invention, the embedded member 3 may be made of any material capable of withstanding the heat transmitted from the mold 2. Typically, the mold 2 reaches 400-500°C, and since a cooling medium is interposed between the mold 2 and the embedded member 3, the temperature of the embedded member 3 is expected to be around several tens of degrees to 150°C. Any material that can withstand such a temperature environment may be used for the embedded member 3. Typically, the embedded member 3 may be made of materials such as ABS resin, various engineering plastics, or super engineering plastics. Alternatively, the embedded member may be made of metal.

[0026] Position of ejection holes in embedded members In the configuration of this embodiment described above, the cooling medium ejection holes 6a from the embedded member 3 may be provided at any point on the outer surface of the embedded member 3 facing the inner surface 2c of the pool structure 2b. In this regard, if there is a recessed portion 2x on the inner surface 2c of the pool structure 2b, as shown in Figure 4(A), stagnation (retention of the cooling medium) may occur in the flow of the cooling medium at that portion, potentially leading to a decrease in cooling performance due to the cooling medium not being replaced. Therefore, in this embodiment, in order to prevent the retention of the cooling medium at the recessed portion 2x, the ejection holes 6a may be provided facing the recessed portion 2x, as shown in Figure 4(B). This is expected to cause the cooling medium to be sprayed onto the recessed portion 2x, generating a flow of the cooling medium, sequentially replacing the cooling medium, and achieving good cooling. Furthermore, on the inner surface 2c of the pool structure 2b, if there are areas 2z that require particularly strong cooling, as shown in Figure 4(C), a discharge hole 6a may be provided opposite to those areas. This is expected to ensure that, during the flow of the cooling medium, fresh, low-temperature cooling medium is constantly sprayed onto the areas 2z that require particularly strong cooling, thereby achieving better heat removal.

[0027] Manufacturing of embedded components The embedded member 3 of this embodiment may be manufactured by any method. In this regard, the embedded member 3 has a somewhat complex structure in which its outer shape is substantially complementary to the pool structure 2b of the mold 2, and an internal passage is also formed. Therefore, a 3D printer is advantageous in the manufacture of the embedded member 3. When the embedded member 3 is manufactured from resin, it is advantageous in that the manufacture of the embedded member 3 can be achieved at a relatively low cost.

[0028] In the apparatus of this embodiment, the cooling medium is normally continuously circulated while the casting process is being carried out.

[0029] While the above description is made in relation to embodiments of the present invention, many modifications and changes are readily possible for those skilled in the art, and it will be clear that the present invention is not limited to the embodiments illustrated above, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A casting system having a mold in which a cavity is defined into which molten metal is poured and a casting is formed, In the aforementioned mold, a pool structure is formed that is recessed from the outside toward the cavity side. The embedded member is placed within the pool structure, has an outer shape that is generally complementary to the inner shape of the pool structure, and defines a surface channel through which a cooling medium can flow between the inner surface of the pool structure and the surface opposite it. An internal channel is formed inside the embedded member to deliver a cooling medium from outside the embedded member to the surface channel. An inlet for introducing a cooling medium into the internal flow path and an outlet for releasing the cooling medium from the surface flow path are provided. An apparatus configured to be cooled by circulating a cooling medium through the aforementioned surface channel.

2. The apparatus according to claim 1, wherein the shape of the pool structure is shaped to generally conform to the shape of the cavity side.

3. The apparatus according to claim 1, wherein, in the pool structure, a cooling medium ejection hole from the internal flow path is formed on the surface of the embedded member facing a recessed portion compared to the surrounding area.

4. The apparatus according to claim 1, wherein, in the pool structure, a cooling medium ejection hole from the internal flow path is formed on the surface of the embedded member facing a part that is to be cooled more strongly than the surrounding area.

5. A method for forming the embedded member of any device according to claim 1 to 4, wherein the embedded member is formed by a 3D printer.

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