Mold and manufacturing method of foam molding

Abstract

To provide a counterpart method for a problem of easily occurring of voids around an open hole of a foamed molding when a conventional mold is used.SOLUTION: A mold according to one embodiment of the present invention is provided with a hole molding part, in a cavity between an upper die and a lower die for molding a foamed molding, for molding an open hole in the foamed molding, and the hole molding part is provided with a parting face of the upper die and the lower die, wherein the mold includes a recess open to at least one of the parting face of the upper die and the lower die and a communication groove formed on the parting face of at least one of the upper die and the lower die and communicating the mold cavity and with the recess.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a mold and a method for manufacturing a foamed molded product.

Background Art

[0002] Conventionally, a mold for molding a foamed molded product having a through hole has been known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a conventional mold is used, there has been a problem that voids are likely to occur around the through hole of the foamed molded product. Therefore, a countermeasure has been demanded.

Means for Solving the Problems

[0005] One aspect of the invention is a mold in which a hole forming portion for forming a through hole in the foamed molded product is provided in a cavity between an upper mold and a lower mold for molding the foamed molded product, and a parting surface between the upper mold and the lower mold is provided on the hole forming portion, the mold comprising: a recess opening in at least one of the parting surfaces between the upper mold and the lower mold; and a communication groove formed in at least one of the parting surfaces between the upper mold and the lower mold and communicating the cavity and the recess.

Brief Description of the Drawings

[0006]

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MODE FOR CARRYING OUT THE INVENTION

[0007] [First Embodiment] FIG. 1 shows the mold 10 of this embodiment. The mold 10 is used to mold the foamed molded product 50 shown in FIG. 2. The foamed molded product 50 has a through hole 51. For example, the foamed molded product 50 has a flat shape such as a plate shape, and the through hole 51 extends in the thickness direction thereof. The foamed molded product 50 may be used, for example, in a vehicle such as a car or in a building. As an example of the foamed molded product 50, a tibia pad that is a shock absorber for the feet of passengers in a vehicle can be mentioned. The foamed molded product 50 is made of a polyurethane resin, for example, a semi-rigid urethane.

[0008] The uses, shapes, and materials of the foamed molded product 50 are not limited to the above examples. The foamed molded product 50 may have a closed-cell structure or an open-cell structure. The resin constituting the foamed molded product 50 may be a thermosetting resin or a thermoplastic resin. Examples include polyolefin resins (such as polyethylene resin and polypropylene resin) in addition to polyurethane resins. As the polyurethane resin constituting the foamed molded product 50, rigid urethane or flexible urethane may be used.

[0009] As shown in FIG. 1, the mold 10 is vertically divided into a pair of split molds 11, and can be changed between a mold-closed state (see FIG. 1) in which they are combined and a mold-open state (see FIG. 3) in which they are separated. In the mold 10, the foamed molded product 50 is foamed and molded in the cavity R between the pair of split molds 11 in the mold-closed state. Hereinafter, among the pair of split molds 11, the upper split mold 11 will be appropriately referred to as the upper mold 11A, and the lower split mold 11 will be appropriately referred to as the lower mold 11B.

[0010] As shown in FIG. 1, the mold 10 is provided with a hole forming portion 20 for forming the through hole 51 of the foamed molded product 50. In the example of the present embodiment, the hole forming portion 20 extends in a columnar shape in the direction facing each other between the upper mold 11A and the lower mold 11B in the cavity R of the mold 10 in the mold-closed state, and has a contact portion between the upper mold 11A and the lower mold 11B.

[0011] Specifically, as shown in FIG. 4, the hole forming portion 20 includes a protrusion 21 provided on at least one of the upper mold 11A and the lower mold 11 (that is, among the pair of split molds 11). The protrusion 21 is abutted against the other split mold 11 facing the split mold 11 on which the protrusion 21 is provided in the mold-closed state. And the contact surfaces thereof are the parting surface P which is the mating surface of the upper mold 11A and the lower mold 11B. In the example of the present embodiment, the protrusions 21 are provided on both the upper mold 11A and the lower mold 11B, and the protruding tip surfaces of these protrusions 21 that abut against each other are the parting surface P.

[0012] In the example of this embodiment, the parting surface P in the hole forming portion 20 is located on the upper mold 11A side (i.e., the upper portion of the hole forming portion 20) in the facing direction of the upper mold 11A and the lower mold 11B. In other words, in the example of this embodiment, the protruding length of the protrusion 21 in the hole forming portion 20 is longer for the lower mold 11B than for the upper mold 11A. Note that the parting surface P can also be provided at the center of the hole forming portion 20 or on the lower mold 11B side.

[0013] As shown in FIG. 3, the mold 10 is provided with a recess 22 that opens to the parting surface P of at least one of the upper mold 11A and the lower mold 11B. In the example of this embodiment, the recess 22 is formed in the upper mold 11A and not in the lower mold 11B. Therefore, the opening 23 of the recess 22 is provided only on the parting surface P of the upper mold 11A among the parting surfaces P of the hole forming portion 20. Also, in the example of this embodiment, the recess 22 has a dead end at the back side of the opening 23 and does not penetrate the upper mold 11A. As shown in FIG. 4, in the mold closed state, since the parting surfaces P of the upper mold 11A and the lower mold 11B are aligned, the recess 22 is blocked by the parting surface P of the lower mold 11B. Note that, for example, the parting surface P of the lower mold 11B is a flat surface.

[0014] As shown in FIG. 4, a communication groove 24 is formed in the parting surface P of at least one of the upper mold 11A and the lower mold 11B. The communication groove 24 communicates the cavity R and the recess 22. In the example of this embodiment, the communication groove 24 is open only on one side at the outer peripheral surface of the hole forming portion 20. Specifically, as shown in FIGS. 5A and 5B, only one communication groove 24 is provided, and one end (hereinafter referred to as the groove open end 24E) of the communication groove 24 that opens to the outer peripheral surface of the hole forming portion 20 is open only in one direction of the outer peripheral surface of the hole forming portion 20 and is provided only at one location.

[0015] In the example of this embodiment, the concave portion 22 extends in the axial direction of the hole forming portion 20 from the opening 23. For example, the concave portion 22 is deeper than the protruding length of the protruding portion 21 (that is, the inner surface of the concave portion 22 is at a position deeper than the position of the base of the protruding portion 21). Therefore, the protruding portion 21 provided with the concave portion 22 (the protruding portion 21 of the upper mold 11A in the example of this embodiment) is cylindrical.

[0016] In addition, in the example of this embodiment, the outer shape of the cross section of the hole forming portion 20 is circular (see Fig. 5A). For example, the opening 23 of the concave portion 22 is arranged at the center of the parting surface P, and in the example of this embodiment, it is formed in a circular shape concentric with the circle of the outer shape of the parting surface P. And the protruding portion 21 provided with the concave portion 22 is cylindrical. Also, in the example of this embodiment, the communication groove 24 extends linearly in the radial direction of the parting surface P. In this embodiment, the communication groove 24 is a square groove, but it may also be a round groove.

[0017] Next, an example of the manufacturing method of the foamed molded product 50 using the mold 10 of this embodiment will be described. First, as shown in Fig. 3, the foaming raw material G is supplied into the cavity R of the mold 10. For example, the foaming raw material G is supplied to the lower mold 11B, and in the example of this embodiment, it is supplied to the molding recess 11U that forms the lower part of the cavity R on the molding surface of the lower mold 11B. At this time, in the example of this embodiment, the foaming raw material G is supplied to a position on the opposite side (the left side in Figs. 1 and 3) of the hole forming portion 20 from the open side (the right side in Figs. 1 and 3) of the groove open end 24E of the communication groove 24 in the lower mold 11B. Therefore, the foaming raw material G is likely to accumulate on the opposite side of the hole forming portion 20 from the open side of the groove open end 24E of the communication groove 24 in the lower mold 11B. In the example shown in Fig. 3, the supply of the foaming raw material G is performed with the mold 10 in the open mold state, but it may also be performed from a supply port that opens to the inner surface of the mold 10 in the closed mold state.

[0018] Next, the foaming raw material G is foamed and cured in the cavity R of the mold 10 in the mold-closed state. Then, a foamed molded product 50 in which a through hole 51 is formed by the hole forming portion 20 is formed (see FIG. 6). Thereafter, the mold 10 is opened and the foamed molded product 50 is taken out. In this way, a foamed molded product 50 having a through hole 51 is obtained.

[0019] Here, as shown in FIG. 7, when the foaming raw material G supplied to the side opposite to the open side of the communication groove 24 with respect to the hole forming portion 20 (the left side in FIG. 7) foams and the foamed resin J reaches near the hole forming portion 20, the flow of the foamed resin J is divided and the foamed resin J wraps around the hole forming portion 20 toward the groove open end 24E side. In this case, as shown in FIG. 12, in a conventional mold 10V having a hole forming portion 20V that does not include the recess 22 or the communication groove 24, when the foamed resin J rejoins on the groove open end 24E side, there is a problem that a void V in which gas cannot escape and accumulates easily occurs around the hole forming portion 20V (particularly, on the side opposite to the side where the foaming raw material G is supplied to the hole forming portion 20V).

[0020] On the other hand, in the mold 10 of the present embodiment, a communication groove 24 that communicates the cavity R and the recess 22 is opened in the hole forming portion 20. Therefore, it is possible to allow the gas in the cavity R to flow into the communication groove 24 and escape into the recess 22. Specifically, when the foaming raw material G foams in the cavity R and the pressure in the cavity R rises, the gas in the cavity R flows into the recess 22 through the communication groove 24. Thereby, as shown in FIG. 8, it is possible to suppress the generation of voids V around the through hole 51 of the foamed molded product 50. Here, when the foaming raw material G foams in the cavity R and the foamed resin J rises, since the gas accumulates on the upper side, it is preferable that the groove open end 24E of the communication groove 24 is provided above the hole forming portion 20 as in the present embodiment. Further, since the outer shape of the cross section of the hole forming portion 20 is circular, the foamed resin easily wraps around the hole forming portion 20, and the generation of voids V around the through hole 51 can be further suppressed.

[0021] In this embodiment, the recess 22 is a dead end and does not penetrate the split mold 11 (upper mold 11A). Therefore, the inflow of the foaming raw material G from the communication groove 24 into the recess 22 can be restricted by the increase in the internal pressure of the recess 22 due to the inflow of the foaming gas into the recess 22. Note that, in this way, in order to restrict the inflow of the foaming raw material G, it is preferable to design the size of the opening of the groove opening end 24E of the communication groove 24 on the outer peripheral surface of the hole forming portion 20, the volume of the recess 22, etc. (for example, it is preferable to design based on simulations, experiments, etc.). Note that, even if the foaming resin J flows into the communication groove 24, after molding, the inflow portion may be cut from the foamed molded product 50 or removed from the recess 22 through the opening 23. Further, if the communication groove 24 is formed on the parting surface P as in this embodiment, the cleaning of the communication groove 24 can also be facilitated.

[0022] In this embodiment, since the communication groove 24 is formed on the parting surface P where the recess 22 opens, it becomes easy to form the communication groove 24 so as to communicate with the recess 22. Further, in this embodiment, since the recess 22 and the communication groove 24 are provided only in one split mold 11 (upper mold 11A), it becomes possible to facilitate the processing as compared with the case where they are provided in both split molds 11.

[0023] [Other Embodiments] As shown in FIG. 9, when the lower mold 11B has a configuration in which the depth of the molding recess 11U varies depending on the position and has a deep bottom portion 11F that is deeper than the surroundings, the foaming raw material G tends to accumulate in the deep bottom portion 11F. In this configuration, it is preferable to provide the communication groove 24 such that the groove opening end 24E is disposed at a portion of the hole forming portion 20 opposite to the deep bottom portion 11F. In the configuration having the deep bottom portion 11F, when the foaming raw material G accumulated in the deep bottom portion 11F foams, it may turn around the hole forming portion 20 and a void V may easily occur in a portion of the hole forming portion 20 opposite to the deep bottom portion 11F. Therefore, by disposing the communication groove 24 in this way, the generation of the void V can be suppressed.

[0024] In the above-described embodiment, the concave portion 22 was formed only in the upper mold 11A. However, the concave portion 22 (i.e., the opening 23) may be formed only in the lower mold 11B, or may be formed in both the upper mold 11A and the lower mold 11B (see Fig. 10).

[0025] In the above-described embodiment, the communication groove 24 was formed only in the upper mold 11A. However, the communication groove 24 may be formed only in the lower mold 11B, or may be formed in both the upper mold 11A and the lower mold 11B as long as it communicates the cavity R and the concave portion 22 (see Fig. 10).

[0026] In the above-described embodiment, at least a part of the concave portion 22 was formed in the protrusion 21 of the hole forming portion 20. However, as shown in Fig. 11, the concave portion 22 may not be formed in the protrusion 21. In the hole forming portion 20 shown in Fig. 11, the parting surface P is arranged at the base on the side of one split mold 11 (for example, the upper mold 11A), and the protrusion 21 is formed only in the other split mold 11 (for example, the lower mold 11B). Thus, the concave portion 22 may be formed in the split mold 11 in which the protrusion 21 is not provided as long as it has the opening 23 in the parting surface P.

[0027] In the above-described embodiment, only one communication groove 24 was provided. However, a plurality of communication grooves 24 may be provided in the circumferential direction of the hole forming portion 20. In this case, for example, it is preferable that the groove opening ends 24E of the communication grooves 24 are unevenly distributed on one side of the outer peripheral surface of the hole forming portion 20, and it is more preferable that they are unevenly distributed on one of the four sides around the hole forming portion 20.

[0028] In the above-described embodiment, instead of or in addition to the communication groove 24, communication holes that communicate the cavity R and the concave portion 22 may be formed in the hole forming portion 20 (protrusion 21). A plurality of such communication holes may be provided, and they may be provided at a plurality of positions in the circumferential direction of the hole forming portion 20 or at a plurality of positions in the axial direction of the hole forming portion 20 (they may be provided separately in the upper mold 11A and the lower mold 11B). When forming such communication holes in the protrusion 21, for example, the protrusion 21 may be axially dividable into a plurality of parts, and grooves may be provided on the dividing surfaces to form the communication holes.

[0029] In the above embodiment, the recess 22 may have a depth such that it fits within the protrusion 21.

[0030] The mold 10 may be configured such that a concave recess 22 that does not penetrate the split mold 11 (upper mold 11A or lower mold 11B) as in the above embodiment is provided, or a configuration in which a flow path that penetrates the split mold 11 extends from the opening 23. In the latter case, this flow path can be configured to be always open to the outside of the mold 10, or a valve can be provided at the outlet outside the mold 10 in this flow path so that the valve opens when the pressure in the flow path rises above a predetermined pressure.

[0031] In the above embodiment, at least one of the upper mold 11A and the lower mold 11B may be divided into a plurality of parts and composed of split molds.

[0032] In the conventional mold 10V shown in FIG. 12, by setting a cylindrical insert part that fits into the hole forming part 20V from the outside, a foamed molded product in which this insert part is fixed to the inner peripheral surface of the through hole 51 (see FIG. 2) can be manufactured. Even if voids V occur in this foamed molded product, it is possible to ensure the strength around the through hole 51 with the above insert part. On the other hand, in the foamed molded product 50 manufactured using the mold 10 of the above embodiment, the generation of voids V around the through hole 51 can be suppressed, so it is possible to reduce the man-hours for setting the above insert part.

[0033] <Addendum> Hereinafter, the feature groups extracted from the above embodiment will be described while indicating effects etc. as necessary.

[0034] For example, the following feature groups of the present disclosure relate to "a mold and a method for manufacturing a foam-molded product". Regarding the background art of "Conventionally, a mold for molding a foam-molded product having a through-hole is known (see, for example, JP-A-2022-26386 (FIG. 6C, etc.)).", it can be considered that it was conceived with the problem of "When a conventional mold is used, voids are likely to occur around the through-hole of the foam-molded product. Therefore, a countermeasure is required." Also, conventionally, the development of new technologies related to the method for manufacturing a foam-molded product and the mold for molding a foam-molded product has been demanded.

[0035] [Feature 1] A mold in which a hole forming portion for forming a through-hole in the foam-molded product is provided in a cavity between an upper mold and a lower mold for molding the foam-molded product, and a parting surface between the upper mold and the lower mold is provided on the hole forming portion, a recess opening in at least one of the parting surfaces between the upper mold and the lower mold; and a communication groove formed in at least one of the parting surfaces between the upper mold and the lower mold and communicating the cavity and the recess.

[0036] According to Feature 1, since the gas around the hole forming portion in the cavity can be discharged into the recess through the communication groove, the generation of voids around the through-hole of the foam-molded product can be suppressed. Note that if the communication groove communicates with the recess, the parting surface on which the communication groove is formed may be the same as or different from the parting surface on which the recess opens.

[0037] [Feature 2] The mold according to Feature 1, wherein the communication groove is formed in the parting surface on which the recess opens.

[0038] If the communication groove is formed in the parting surface on which the recess is formed, it becomes easy to form the communication groove so as to communicate with the recess.

[0039] [Feature 3] The mold according to Feature 1 or 2, wherein the concave portion has a concave shape that does not penetrate the upper mold or the lower mold.

[0040] [Feature 4] The mold according to Feature 1 or 2, wherein the inflow of the foaming raw material from the gas introduction groove to the concave portion is restricted by the increase in the internal pressure of the concave portion due to the inflow of the foaming gas into the concave portion.

[0041] In the molds of Features 3 and 4, the inflow of the foaming raw material from the communication groove to the concave portion can be restricted by the increase in the internal pressure of the concave portion due to the inflow of the foaming gas into the concave portion.

[0042] [Feature 5] The mold according to any one of Features 1 to 4, wherein the communication groove is open only in one direction around the outer surface of the hole forming portion.

[0043] According to Feature 5, it is possible to suppress the generation of voids around the through hole of the foam molded product while restricting the inflow of the foaming raw material from the communication groove to the concave portion.

[0044] [Feature 6] The mold according to any one of Features 1 to 5, wherein the parting surface of the hole forming portion is disposed in the upper portion of the hole forming portion.

[0045] [Feature 7] The mold according to any one of Features 1 to 6, wherein the outer shape of the cross section of the hole forming portion is circular.

[0046] According to Feature 7, the foaming resin can easily wrap around the hole forming portion.

[0047] [Feature 8] A manufacturing method for manufacturing the foam molded product using the mold according to any one of Features 1 to 7, A manufacturing method for a foam molded product, wherein a foaming raw material is supplied into the cavity in the lower mold.

[0048] [Feature 9] The communication groove is open only in one direction on the outer peripheral surface of the hole forming portion. The method for manufacturing a foamed molded product according to feature 8, wherein the foaming raw material is supplied to a position on the lower mold opposite to the open side of the communication groove with respect to the hole forming portion.

[0049] In the cavity of the mold, when the foaming raw material is supplied to one side with respect to the hole forming portion, the foaming raw material wraps around the hole forming portion while foaming, and gas tends to remain on the other side around the hole forming portion, and voids may easily occur. In the method for manufacturing a foamed molded product according to feature 9, by supplying the foaming raw material to a position on the mold opposite to the side where the communication groove is open with respect to the hole forming portion, the gas in the mold can be discharged to the concave portion through the communication groove, and the generation of voids around the through hole of the foamed molded product can be further suppressed.

[0050] Although specific examples of the technology included in the claims are disclosed in this specification and the drawings, the technology described in the claims is not limited to these specific examples, and includes those obtained by variously modifying and changing the specific examples, and also includes those obtained by extracting a part from the specific examples alone.

Explanation of Reference Numerals

[0051] 10 Mold 11 Split Mold 11A Upper Mold 11B Lower Mold 20 Hole Forming Portion 21 Protrusion 22 Concave Portion 23 Opening 24 Communication Groove 24E Groove Open End 50 Foamed Molded Product 51 Through Hole G Foaming Raw Material P Parting Surface R Cavity V Void

Claims

1. A mold provided with a hole forming portion for forming a through hole in the foamed molded product in a cavity between an upper mold and a lower mold for molding the foamed molded product, and a parting surface between the upper mold and the lower mold is provided on the hole forming portion, wherein a recess opening in at least one of the parting surfaces between the upper mold and the lower mold; a communication groove formed in at least one of the parting surfaces between the upper mold and the lower mold and communicating the cavity and the recess, is provided.

2. The mold according to claim 1, wherein the communication groove is formed in the parting surface in which the recess opens.

3. The mold according to claim 1, wherein the recess has a concave shape that does not penetrate the upper mold or the lower mold.

4. A manufacturing method for manufacturing the foamed molded product using the mold according to any one of claims 1 to 3, wherein a foaming raw material is supplied into the cavity in the lower mold.

5. The communication groove is open only in one direction on the outer peripheral surface of the hole forming portion, and the foaming raw material is supplied to the hole forming portion at a position opposite to the open side of the communication groove in the lower mold.

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