Mold unit

Abstract

To provide a mold unit capable of extending the fatigue life of a lid used for temperature measurement.SOLUTION: A mold unit 1 according to the present disclosure includes a mold 2 having a through-hole penetrating from an outer surface to an inner surface defining a space into which a molten material is injected, a lid 3 formed of the same material as the mold and fixed to the mold by a welded portion 7 so as to close an end portion on the inner surface side of the through-hole in the through-hole 22, the thermocouple is provided with a thermocouple wire 4 fixed to the surface of the lid on the side of the outer surface of the mold in a state of being passed through the through-hole, a cylindrical member covering the thermocouple wire in a state of being passed through the through-hole, and a support member 6 supporting the cylindrical member. The tubular member is fixed between the lid and the support member, the through-hole and the lid are not in contact with each other in a region other than the welded portion, and the lid is provided with a concave portion having a concave curved bottom surface so that the lid is easily elastically deformed when the lid is thermally expanded or contracted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a mold unit. [Background technology]

[0002] Patent document 1 discloses a mold unit equipped with a lid made of the same material as the mold, which can accurately measure the temperature of the mold by measuring the temperature of the lid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-086213 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the mold unit disclosed in Patent Document 1, the lid undergoes thermal expansion due to contact with the molten metal and thermal contraction due to spraying of the mold release agent. At this time, there is a problem that the lid cracks early due to the stress amplitude caused by the thermal expansion and thermal contraction.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and provides a mold unit that can reduce the stress amplitude of a lid used for temperature measurement and extend the life of the lid. [Means for solving the problem]

[0006] A mold unit according to one aspect of the present disclosure includes: a mold having a through hole extending from an outer surface to an inner surface defining a space into which molten material is injected; a lid formed of the same material as the mold and fixed to the mold by a welded portion so as to close an end of the through hole on the inner surface side of the mold; a thermocouple wire having a folded portion, the tip of which is fixed to a surface of the lid on the outer surface side of the mold when the thermocouple wire is passed through the through hole; a cylindrical member that covers the thermocouple wire while being passed through the through hole; a support member for supporting the cylindrical member, the cylindrical member is fixed between the lid and the support member, the through hole and the lid are not in contact with each other in an area other than the welded portion, The lid has a recess with a concave curved bottom surface formed therein to facilitate elastic deformation of the lid during thermal expansion or contraction of the lid. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a mold unit that can reduce the stress amplitude of the lid used for temperature measurement and extend the life of the lid. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a top view of a mold unit according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of a mold unit according to an embodiment of the present disclosure. [Figure 3] 10 is a graph comparing the stress amplitude of a lid of a mold unit according to an embodiment of the present disclosure with the stress amplitude of a flat plate-shaped lid. [Figure 4] (a) Thermal stress analysis conditions for mold units according to examples and comparative examples of the present disclosure. (b) Top view of a mold and a lid in a thermal stress analysis model of a mold unit according to examples and comparative examples of the present disclosure. (c) Cross-sectional view of a mold and a lid in a thermal stress analysis model of a mold unit according to examples and comparative examples of the present disclosure. (d) Cross-sectional view of a mold and a lid in a thermal stress analysis model of a mold unit according to examples and comparative examples of the present disclosure. (e) Thermal stress analysis model of a lid according to examples of the present disclosure. (f) Thermal stress analysis model of a lid of a comparative example. [Figure 5] 10 shows the results of thermal stress analysis of the lid in the mold unit according to the example and comparative example of the present disclosure. [Figure 6] 10 shows the results of comparing the stress amplitude of the lid in the mold units according to the examples and comparative examples of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, specific embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified appropriately for clarity of explanation.

[0010] <Configuration of mold unit> 1 and 2 are a top view and a cross-sectional view of a mold unit according to an embodiment of the present disclosure, respectively;

[0011] The mold unit 1 includes a mold 2, a lid 3, a thermocouple wire 4, a cylindrical member 5, and a support member 6. The mold 2 and the lid 3 are welded together at a weld 7.

[0012] The mold 2 is a mold for casting, and forms a cavity that defines a space into which the molten material is poured. In FIG. 2, the surface composed of the mold 2, the lid 3, and the welded portion 7 (the upper surface in FIG. 2) is the inner surface of the mold 2, which forms the cavity. Meanwhile, the surface opposite the inner surface (the lower surface in FIG. 2) is the outer surface of the mold 2. The shape and size of the mold 2 are determined according to the shape and size of the desired casting. The material of the mold 2 is determined according to the temperature of the molten material, etc., and is, for example, a metal or alloy such as steel, iron, or cast iron.

[0013] The molten material poured into the cavity formed by the mold 2 is, for example, molten metal or alloy such as molten iron, molten steel, or molten aluminum, or molten resin such as polycarbonate, polyvinyl chloride, ABS resin, or acrylic resin.

[0014] The mold 2 also has a through-hole 21 that passes through the mold 2 in the vertical direction from the outer surface to the inner surface of the mold 2. The lid 3, the thermocouple wire 4, and the cylindrical member 5 that supports the thermocouple wire 4 are arranged in the through-hole 21.

[0015] Here, it is preferable that the through hole 21 has a stepped shape that is wider on the inner surface side of the mold 2, as shown in Fig. 2. By increasing the inner diameter of the through hole 21 on the inner surface side of the mold 2 and arranging the lid 3 in that position, the area of ​​the lid 3 that occupies the inner surface of the mold 2 can be increased, improving the temperature responsiveness of the thermocouple wire 4. Furthermore, by reducing the inner diameter on the outer surface side of the mold 2, the volume of the mold 2 can be secured, and the temperature change of the mold 2 during casting can be reduced. Note that, although the through hole 21 is cylindrical in Fig. 2, it may also be polygonal prism-shaped, and this is determined depending on the shapes of the lid 3 and the cylindrical member 5.

[0016] The lid 3 transfers heat from the molten material poured into the cavity formed by the mold 2 to the thermocouple wire 4. The lid 3 is disposed so as to close the inner surface side of the mold 2 in the through hole 21, is welded to the mold 2 via a weld 7, and is supported by a cylindrical member 5. The outer periphery on the inner surface side of the lid 3 and the mold 2 (the inner circumferential surface on the inner surface side of the through hole 21) are welded at the weld 7 (see FIGS. 1 and 2). The lid 3 is formed of the same material as the mold 2. The size of the lid 3 is determined depending on the size of the through hole 21, etc.

[0017] Here, an insulating space V is provided between the lid 3 and the mold 2 (see Figure 2). Specifically, the lid 3 and the mold 2 are welded via a welded portion 7, with the lid 3 and the mold 2 facing each other with the insulating space V in between. In other words, the lid 3 and the mold 2 are not in contact with each other except at the welded portion 7. This configuration prevents the heat transferred from the molten material to the lid 3 from escaping to the mold 2, making it possible to measure the temperature accurately using the thermocouple wire 4.

[0018] The lid 3 also has a recess 31 on the outer surface side of the mold 2 for mitigating the stress amplitude of the lid 3. The recess 31 is a bottomed recess that extends from the outer surface side toward the inner surface side of the mold 2 and has a bottom on the inner surface side. The bottom of the recess 31 is concavely curved toward the inner surface side of the mold 2. As a result, the lid 3 is not flat like the lid in Patent Document 1, but has a shape that gradually becomes thinner from the outer periphery toward the center (see FIG. 2). The use of such a recess 31 allows deformation (elastic deformation) due to expansion and contraction of the lid 3 (thin plate) during the casting cycle, mitigating the stress amplitude and thereby extending the life of the lid 3 (thin plate). The recess 31 also has corners 311.

[0019] Here, the flat-shaped lid disclosed in Patent Document 1 repeatedly generates internal stress due to thermal expansion caused by contact with the molten metal and thermal contraction caused by spraying of the mold release agent. As a result, the amplitude of the generated internal stress (stress amplitude) causes early cracking of the lid. Here, the stress amplitude can be calculated using the following formula (1) for the maximum stress value and the minimum stress value generated in the lid.

[0020] Stress amplitude [MPa] = (maximum stress value [MPa] - minimum stress value [MPa]) / 2 ... (Equation 1)

[0021] On the other hand, the lid 3 according to the embodiment of the present disclosure has a recess 31 for mitigating the stress amplitude of the lid 3. More specifically, the recess 31 has a shape that makes the lid 3 more susceptible to elastic deformation in the vertical direction (thickness direction of the lid) when the lid 3 thermally expands and contracts compared to a flat lid. When the lid 3 elastically deforms in the vertical direction, the maximum stress value generated inside the lid 3 decreases and the minimum stress value increases. As a result, the stress amplitude of the lid 3 is mitigated.

[0022] 3 is a graph comparing the stress amplitude of the lid of the mold unit according to the embodiment of the present disclosure with the stress amplitude of a flat lid. The lid 3 according to the embodiment of the present disclosure has a reduced maximum stress value and an increased minimum stress value compared to the flat lid, thereby mitigating the stress amplitude.

[0023] 2, the recess 31 is provided on the outer surface side of the mold 2, but the position and size of the recess 31 are determined depending on the purpose of mitigating the stress amplitude of the lid 3. However, in terms of the amount of deformation of the lid 3, the deformation direction, and the effect on the shape of the casting, it is preferable that the recess 31 be formed on the outer surface side of the mold 2 in the lid 3. By forming the recess 31 on the outer surface side of the mold 2 in the lid 3, when expansion and contraction occur in the lid 3, the lid 3 elastically deforms in the vertical direction, and as a result, the stress amplitude of the lid 3 is mitigated.

[0024] Furthermore, by providing the recess 31 in the lid 3, the thickness of the portion where the recess 31 is provided is reduced. Reducing the thickness of the lid 3 improves the temperature responsiveness of the thermocouple wire 4. However, if the thickness of the lid 3 is reduced throughout, the strength of the lid 3 may be reduced. To minimize the reduction in strength of the lid 3, the shape of the lid 3 is preferably thick at the periphery and thin only at the center, that is, a shape in which the recess 31 is provided in the center of the lid 3. In addition to the effect of reducing the stress amplitude of the lid 3 described above, the lid shape of the present disclosure in which the recess 31 is provided in the center of the lid 3 on the outer surface side of the mold 2 is more preferable.

[0025] Furthermore, the bottom surface of the recess 31 is preferably concavely curved toward the inner surface of the mold 2. By having the bottom surface of the recess 31 have a concavely curved shape, stress concentration occurring in the recess 31 when the lid 3 elastically deforms can be alleviated.

[0026] Moreover, it is preferable that the corners 311 of the recess 31 have an R-shape. By making the corners 311 R-shaped, it is possible to alleviate stress concentration that occurs at the corners 311 when the lid 3 is elastically deformed.

[0027] Furthermore, the depth of the recess 31 is preferably 10 to 25% of the thickness of the lid 3. If the depth of the recess 31 is shallower than 10% of the thickness of the lid 3, the amount of vertical elastic deformation of the lid 3 decreases, and the effect of mitigating the stress amplitude decreases. If the depth of the recess 31 is deeper than 25% of the thickness of the lid 3, the strength of the lid 3 decreases.

[0028] The thermocouple wire 4 measures the temperature of the lid 3. The thermocouple wire 4 is connected to the lid 3 via a folded portion 41 and is disposed inside the cylindrical member 5. The material of the thermocouple wire 4 is a metal such as a platinum-rhodium alloy, a nickel-chromium alloy, a nickel alloy, iron, or copper.

[0029] When the lid 3 has a recess 31 formed on the outer surface side of the mold 2 , the folded portion 41 of the thermocouple wire 4 may be disposed so as to come into contact with the bottom surface of the recess 31 .

[0030] The cylindrical member 5 supports the lid 3, and has the thermocouple wires 4 disposed therein. The cylindrical member 5 is supported by a support member 6. Although the cylindrical member 5 is shown in FIG. 2 as having a cylindrical shape, it may have a polygonal prism shape, and the size of the cylindrical member 5 is determined depending on the shape of the through-hole 21. The size of the cylindrical member 5 is determined depending on the size of the lid 3, the amount of molten material to be poured into the cavity of the mold 2, the size of the through-hole 21, etc.

[0031] The support member 6 supports the cylindrical member 5. Although the support member 6 is cylindrical in FIG. 2, it may be polygonal and its shape is determined according to the environment in which the support member 6 is placed. The size of the support member 6 is determined according to the size of the cylindrical member 5, etc.

[0032] As described above, the mold unit 1 according to the embodiment of the present disclosure has the lid 3 used for measuring the temperature of the mold 2 at the bottom of the mold 2, and the lid 3 is provided with a recess 31 for reducing the stress amplitude. This makes it possible to provide a mold unit that can reduce the stress amplitude of the lid 3 used for temperature measurement compared to the stress amplitude of the lid described in Patent Document 1. The present inventors have confirmed this through stress analysis using a model. The stress analysis performed by the present inventors will now be described. The following stress analysis was performed using predetermined software. [Example]

[0033] <Conditions for thermal stress analysis of mold unit> Next, the results of thermal stress analysis of the mold unit according to the embodiment of the present disclosure are shown. FIG. 4(a) shows the thermal stress analysis conditions for the mold unit according to the example and comparative example of the present disclosure. FIG. 4(b) is a top view of the mold and the lid in the thermal stress analysis model of the mold unit according to the example and comparative example of the present disclosure. FIG. 4(c) is a cross-sectional view of the mold and the lid in the thermal stress analysis model of the mold unit according to the example and comparative example of the present disclosure. FIG. 4(d) is a cross-sectional view of the mold and the lid in the thermal stress analysis model of the mold unit according to the example and comparative example of the present disclosure. FIG. 4(e) is a thermal stress analysis model of the lid according to the example of the present disclosure. FIG. 4(f) is a thermal stress analysis model of the lid of the comparative example.

[0034] As a thermal stress analysis model, a mold and a lid were arranged as shown in FIGS. 4(b) and 4(c), and a through-hole was provided below the lid to simulate the shape of the mold unit according to an embodiment of the present disclosure. Furthermore, as shown in FIG. 4(d), the upper peripheral edge of the lid was set as a tie joint to simulate the weld between the mold and the lid according to an embodiment of the present disclosure. On the other hand, the side surface of the lid other than the upper peripheral edge was set as a small slip, simulating the lack of contact between the mold and the lid according to an embodiment of the present disclosure except at the weld. Furthermore, the lid shape according to an embodiment of the present disclosure shown in FIG. 4(e) was set as Example 1, and the conventional shape shown in FIG. 4(f) was set as Comparative Example 1. Here, both the lids of Example 1 and Comparative Example 1 are circular plates with the same maximum thickness, but the lid of Example 1 has a recess in the center of the lower side of the disk. Additionally, the recess has a concave curved shape on the bottom surface and rounded corners.

[0035] <Thermal stress analysis results> Fig. 5 shows the results of thermal stress analysis of the lid in the mold unit according to the example of the present disclosure and the comparative example. Fig. 6 shows the results of comparing the stress amplitude of the lid in the mold unit according to the example of the present disclosure and the comparative example.

[0036] First, as shown in FIG. 5, the lids of Example 1 and Comparative Example 1 thermally expanded when the lid alone was set to 600°C. However, because the mold was set as a rigid body, the lids were unable to thermally expand in the left-right direction. At this time, if the thickness was uniform, as with the lid of Comparative Example 1, the lid could not deform. On the other hand, if the thickness of the central portion was reduced by providing a recess in the lower central portion, as with the lid of Example 1, the lid deformed upward.

[0037] Subsequently, both the lid of Example 1 and the lid of Comparative Example 1 shrunk horizontally as the lid temperature decreased. At this time, because the upper peripheral portion of the lid was fixed to the mold, only the lower side of the lid shrunk, resulting in the entire lid bulging upward and deforming. Here, during deformation, the lid of Example 1, which had a recess, deformed more than the lid of Comparative Example 1. This indicates that the recess formed in the lid promotes elastic deformation of the lid.

[0038] 6, the stress amplitude of the lid was 1,203 MPa in Example 1 and 1,231 MPa in Comparative Example 1. This indicates that the stress amplitude of the lid can be reduced by forming a recess in the lid. Note that 1,203 MPa and 1,231 MPa were calculated using the above formula 1.

[0039] As described above, the mold unit according to the embodiment of the present disclosure has a lid with a recessed portion, and the recessed portion promotes elastic deformation of the lid, thereby reducing the stress amplitude of the lid. This makes it possible to provide a mold unit that can reduce the stress amplitude of the lid used for temperature measurement and extend the life of the lid.

[0040] Next, a modified example will be described. In the above embodiment, an example was described in which the recess formed in the lid is a recess 31 (see Figure 2) whose bottom surface is concavely curved toward the inner surface of the mold 2, specifically, a recess 31 whose bottom surface has a shape that gradually becomes thinner from the outer periphery toward the center, but this is not limited to this. That is, the recesses formed in the lid may be of any size, shape, or number as long as they allow the lid to elastically deform when thermal expansion due to contact with the molten metal and thermal contraction due to spraying of the release agent are repeated, and the stress amplitude generated in the lid can be made smaller than the stress amplitude generated in the lid described in Patent Document 1. Furthermore, the location where the recesses are formed is not limited to the outer surface of the mold 2. It is difficult to specify the specific size, shape, number, etc. of such recesses 31 using specific numbers. However, for example, by using the predetermined software used in the stress analysis, it is possible to find the size, shape, number, and formation location of recesses that allow the lid to elastically deform when thermal expansion due to contact with the molten metal and thermal contraction due to spraying of the release agent are repeated, and that can make the stress amplitude generated in the lid smaller than the stress amplitude generated in the lid described in Patent Document 1. [Explanation of symbols]

[0041] 1 Mold unit 2. Mold 21 Through hole 3 Lid 31 Recess 311 Corner 4 Thermocouple wires 41 Folded section 5. Cylindrical member 6 Support member 7 Welded parts

Claims

1. a mold having a through hole extending from an outer surface to an inner surface defining a space into which molten material is injected; a lid formed of the same material as the mold and fixed to the mold by a welded portion so as to close an end of the through hole on the inner surface side of the mold; a thermocouple wire having a folded portion, the tip of which is fixed to a surface of the lid on the outer surface side of the mold when the thermocouple wire is passed through the through hole; a cylindrical member that covers the thermocouple wire while being passed through the through hole; a support member for supporting the cylindrical member, the cylindrical member is fixed between the lid and the support member, the through hole and the lid are not in contact with each other in an area other than the welded portion, The lid has a recess with a concave curved bottom surface formed thereon to facilitate elastic deformation of the lid during thermal expansion or thermal contraction of the lid. Mold unit.

2. The recess has rounded corners. The mold unit according to claim 1 .

3. The stress amplitude of the lid is smaller than the stress amplitude of a flat lid. The mold unit according to claim 1 .

4. The recess is formed on the lid on the outer surface side of the mold. The mold unit according to claim 1 .

5. The depth of the recess is 10 to 25% of the thickness of the lid. The mold unit according to claim 1 or 2.

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