Method and mold for foam molding

Abstract

To provide a molding method of a foamed molding and a mold thereof, capable of preventing voids from being formed around a through hole formed in a foamed molding.SOLUTION: A mold 2 used in a molding method of a foamed molding 1 is provided with a through hole molding part 31, 41 by a part of an upper die 4 and a part of a lower die 3 for forming a through hole 13 of a foamed molding 1. A branched groove 32 that branches into a plurality of branches and is connected with a mold cavity 20 is formed at the through hole molding part 31. An air vent port 42 communicating the branch groove 32 and an outside of the mold 2 is formed at the upper die 4. In a filling step of the molding method, an expandable raw material 100 is expanded and fluidized in the mold cavity 20 and an air in the mold cavity 20 is discharged to an outside of the mold 2 from the air vent port 42 via the branched groove 32.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a molding method and a molding die for a foamed molded article. [Background technology]

[0002] Foam molded articles are, for example, foamed polyurethanes and are used to form seats for various vehicles. A molding die consisting of an upper die and a lower die that form a cavity is used to mold the foam molded article. A foamable raw material is injected into the lower die and foams to fill the cavity, thereby forming the foam molded article.

[0003] Also, when the foamable raw material is filled into the cavity, some measures are taken to vent the gas in the cavity to the outside of the mold. For example, in the foam molding device and molding method of Patent Document 1, a groove for forming ribbon-shaped flash is provided on the mating surface between the first and second dies of the foam molding mold, a gas vent is provided in the groove, and a pressure reducing means is connected to the gas vent. Then, when the foamable raw material is filled into the cavity, the gas in the cavity is vented to the outside by the pressure reducing means through the gas vent and the groove. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-19718 A Summary of the Invention [Problem to be solved by the invention]

[0005] When forming a through hole in a foam molded body, at least one of the upper and lower molds is formed with a through hole molding section for molding the through hole. The foamable raw material injected into the cavity flows by dividing into two parts around the through hole molding section and then merges. At this time, the air remaining in the cavity is collected toward the joining section of the foamable raw material in the cavity as the foamable raw material fills each part of the cavity. If there is no appropriate air vent near this joining section, there is a risk of a cavity being formed in the foam molded body due to air accumulation.

[0006] In the conventional molding method for a foam molded product as disclosed in Patent Document 1 and the like, no ingenuity is given to how to provide a gas vent in the foam molding die when a through hole is formed in the foam molded product. Therefore, further ingenuity is required to prevent the formation of a cavity due to air accumulation around the through hole when the through hole is formed in the foam molded product.

[0007] The present invention has been made in consideration of such problems, and aims to provide a molding method and mold for a foamed molded body that can prevent the formation of cavities around through holes formed in the foamed molded body. [Means for solving the problem]

[0008] One aspect of the present invention is Formed into a shape having at least three corners and at least three sides A method for molding a foamed molded article having a through hole using a molding die, comprising the steps of: the molding die includes an upper die, a lower die that forms a cavity between the upper die and the lower die, and a through hole molding portion that is formed by a part of the upper die and a part of the lower die and that mates with each other while penetrating the cavity to mold the through hole; A branch groove is formed in the through hole forming portion, the branch groove being branched into a plurality of grooves and connected to the cavity, the branch groove is formed in the through hole forming portion so as to be connected to portions corresponding to the plurality of side portions, except for portions corresponding to the corner portions, an air vent hole communicating the branch groove with an outside of the molding die is formed in at least one of the upper die and the lower die; The air vent port is provided at a position where a plurality of branched portions of the branch groove join together, a cavity forming step of injecting a foamable raw material into the lower mold and closing the upper mold against the lower mold to form the cavity; a filling step of foaming and flowing the foamable raw material in the cavity, and filling the cavity with the foamable raw material while discharging air in the cavity through the branch groove and from the air vent hole to the outside of the molding die.

[0009] Another aspect of the present invention is Formed into a shape having at least three corners and at least three sides A mold for molding a foamed molded article having a through hole, the molding die includes an upper die, a lower die that forms a cavity between the upper die and the lower die, and a through hole molding portion that is formed by a part of the upper die and a part of the lower die and that mates with each other while penetrating the cavity to mold the through hole; A branch groove is formed in the through hole forming portion, the branch groove being branched into a plurality of grooves and connected to the cavity, the branch groove is formed in the through hole forming portion so as to be connected to portions corresponding to the plurality of side portions, except for portions corresponding to the corner portions, An air vent hole is formed in the branch groove, which connects the cavity with the outside of the mold. And, The air vent hole is provided at a position where a plurality of branched portions of the branched groove join together. The foam molding is performed in a mold. Effect of the Invention

[0010] (Method of molding foamed product) In the molding method for a foam molded article according to one embodiment of the present invention, a molding die for molding a foam molded article having a through hole is devised. Specifically, in the molding die, a branch groove that branches into a plurality of grooves and connects to the cavity is formed in a through hole molding section for molding the through hole, and an air vent hole that connects to the branch groove is formed in at least one of the upper and lower dies.

[0011] Then, a mold is used to perform a cavity forming step and a filling step to form a foamed molded article. In particular, in the filling step, when the foamable raw material is filled into the cavity, air in the cavity is discharged from the air vent port to the outside of the mold via the branch groove. At this time, since the branch groove is formed to branch into a plurality of grooves at the through-hole molding part, even if the position where the foamable raw material that branches into both sides and flows around the through-hole molding part meets around the through-hole molding part in the cavity shifts, the air in the cavity can be discharged from any of the branched parts of the branch groove to the air vent port.

[0012] Therefore, according to the method for molding a foam molded article of the one aspect, it is possible to prevent the formation of cavities around the through holes formed in the foam molded article.

[0013] (Mold for foam molding) The molding die for the foam molded body of the other embodiment has a through-hole molding part, a branch groove, and an air vent port, similar to the molding die used in the molding method for the foam molded body. In particular, the branch groove is formed by branching into a plurality of parts at the through-hole molding part. With this configuration, even if the foamable raw material that branches off to flow on both sides around the through-hole molding part and merges at a different position in the cavity around the through-hole molding part during molding of the foam molded body, air in the cavity can be discharged from any of the branching parts of the branch groove to the air vent port.

[0014] Therefore, according to the molding die for a foam molded body of the other embodiment, it is possible to prevent the formation of cavities around the through-holes formed in the foam molded body. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram showing a foam molded article as viewed from the front. [Diagram 2] FIG. 2 is an explanatory diagram showing the foam molded article by a cross section taken along line II-II of FIG. [Diagram 3]FIG. 3 is an explanatory diagram showing the foam molded article by a cross section taken along line III-III in FIG. [Figure 4] FIG. 4 is an explanatory diagram showing a mold for forming a foam molded article, in a cross section corresponding to the cross section II-II in FIG. [Diagram 5] FIG. 5 is an explanatory diagram showing a mold for forming a foam molded article, in a cross section corresponding to the cross section taken along line III-III in FIG. [Figure 6] FIG. 6 is an explanatory diagram showing a mold for forming a foam molded article, in a cross section corresponding to the cross section II-II in FIG. [Figure 7] FIG. 7 is an explanatory view showing the periphery of a branched groove in the through-hole forming portion of the lower part of the forming die. [Figure 8] FIG. 8 is an explanatory diagram showing, in an enlarged scale, a part of FIG. 4, the periphery of the branch grooves and the air vent hole of the mold for forming the foam molded article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A preferred embodiment of the above-mentioned molding method and molding die for the foamed molded article will now be described. In the method for molding a foam molded body according to one embodiment, a removing step may be performed after the filling step, in which burrs formed by solidification of the foamable raw material that has entered the branch grooves are removed from the foam molded body. This configuration can prevent the deterioration of the appearance of the foam molded body due to burrs. Furthermore, when a separate member such as a reinforcing material is disposed on the foam molded body after molding, the burrs can be prevented from interfering with the separate member.

[0017] In the molding method for a foam molded product of the one embodiment and the molding die for a foam molded product of the other embodiment, the through hole is formed in a shape having at least three corners and at least three sides, and the branch groove is formed in a state of connecting to the portions of the through hole molding part corresponding to the plurality of sides, except for the portions corresponding to the corners. R .this By having the configurationIn addition, burrs formed when the foaming material enters the branch grooves and solidifies are located on the sides of the through holes, not on the corners of the through holes, so that the burrs can be easily removed from the foaming material.

[0018] In the molding die for a foam molded body of the other embodiment, the through-hole molding portion may be formed by a part of the upper die and a part of the lower die, the branch groove may be formed in the through-hole molding portion in the lower die, and the air vent may be formed in the through-hole molding portion in the upper die. In this case, by forming the branch groove in the lower die, even if burrs formed by the foamable raw material entering the branch grooves remain in the lower die after molding of the foam molded body, the molding die can be opened and the burrs can be easily removed from the lower die. Also, by forming the air vent in the upper die, when the foamable raw material is injected into the lower die, it is possible to prevent the foamable raw material from entering the air vent port before the air is released through the air vent port.

[0019] In addition, at least the portion of the through hole molding part in the lower mold where the branch grooves are formed may be made of a resin material. Resin materials have the characteristic of being easier to process than metal materials. Therefore, the branch grooves can be easily formed by forming them in the through hole molding part made of a resin material. In some cases, it is also easy to reform the branch grooves formed in the through hole molding part into branch grooves of different shapes as appropriate.

[0020] Next, preferred embodiments of the molding method and mold for the foamed molded article described above will be described with reference to the drawings. <Embodiment> In the method for molding a foam molded article 1 of this embodiment, as shown in Figures 1 to 5, a foam molded article 1 having a through hole 13 is molded using a molding die 2. The molding die 2 has an upper die 4, a lower die 3 which forms a cavity 20 between itself and the upper die 4, and through hole molding parts 31, 41 formed by a part of the upper die 4 and a part of the lower die 3. The through hole molding parts 31, 41 are configured to mate with each other while penetrating the cavity 20 in order to mold the through hole 13.

[0021] As shown in Figs. 6 to 8, the through-hole molding portion 31 is formed with a branched groove 32 that branches into a plurality of grooves and is connected to the cavity 20. The upper mold 4 is formed with an air vent port 42 that connects the branched groove 32 to the outside of the molding die 2. When molding the foam molded body 1, a cavity forming step and a filling step are performed. In the cavity forming step, the foamable raw material 100 is injected into the lower mold 3, and the upper mold 4 is closed relative to the lower mold 3 to form the cavity 20. In the filling step, the foamable raw material 100 is foamed and flowed in the cavity 20, and the foamable raw material 100 is filled into the cavity 20 while air A in the cavity 20 is discharged from the air vent port 42 to the outside of the molding die 2 via the branched grooves 32.

[0022] The molding method for the foamed molded article 1 and the molding die 2 of this embodiment will be described in detail below. (Foam Molded Body 1) As shown in Figures 1 to 3, a foam molded body 1 constitutes the backrest of an automobile seat. An automobile seat is composed of a seat portion and a backrest. The foam molded body 1 constituting the backrest has a shape in which a main backrest portion 11 and a center armrest portion 12 having a through hole 13 for accommodating an armrest are connected in the left-right direction W.

[0023] The upper part of the foam molded body 1 is formed with a folded portion 14 that is folded from a front side 101 located at the front side of the vehicle to a back side 102 located at the rear side of the vehicle. The folded portion 14 is formed in a state facing the back side 102 of the main body part of the foam molded body 1. The folded portion 14 is formed continuous with the main seat back portion 11 and the center armrest portion 12. A through hole 13 is formed in a state penetrating the center armrest portion 12 from the front side 101 to the back side 102. An attachment hole 16 for attaching a headrest is formed in the upper side H1 of the foam molded body 1.

[0024] As shown in Fig. 1, the through hole 13 in this embodiment is formed in a quadrangle shape having four corners 135 and four sides 131, 132, 133, 134. The four corners 135 of the through hole 13 are located on both sides W1, W2 in the left-right direction W of the side 131 on the upper side H1 and on both sides W1, W2 in the left-right direction W of the side 134 on the lower side H2. The burrs 15 due to the branch grooves 32 are formed around the corners 135 on the inner side W2 in the left-right direction W of the side 134 on the lower side H2. An inner wall surface 130 constituting the through hole 13 is formed in the center armrest portion 12 of the foam molded body 1.

[0025] The upper side H1 of the foam molded body 1 refers to the upper side H1 in the up-down direction H when the backrest is mounted in the vehicle. The lower side H2 of the foam molded body 1 refers to the lower side H2 in the up-down direction H when the backrest is mounted in the vehicle. The up-down direction H does not have to be parallel to the vertical direction, and may be inclined at an angle close to the vertical direction. The left-right direction W of the foam molded body 1 refers to the left-right direction W when the backrest is mounted in the vehicle.

[0026] (Mold 2) 4 and 5, the molding die 2 has a structure in which an upper die 4 opens and closes relative to a lower die 3. A cavity 20 for molding the foam molded body 1 is formed in the space surrounded by the lower die 3 and the upper die 4. A part of the cavity 20 in the lower die 3 mainly molds a front side 101 of the foam molded body 1, and a part of the cavity 20 in the upper die 4 mainly molds a back side 102 of the foam molded body 1 and an inside 103 of the folded-back shape portion 14. The inside 103 of the folded-back shape portion 14 refers to the side of the folded-back shape portion 14 that faces the back side 102 of the main body of the foam molded body 1.

[0027] 6, the upper mold 4 is provided with a core mold section 40 for molding a portion of the back side 102 of the foam molded body 1 and a portion of the inside 103 of the folded-back portion 14 of the foam molded body 1. In addition, by moving the core mold section 40 in the upper mold 4, the foam molded body 1 can be easily removed from the molding die 2 after molding.

[0028] The core mold section 40 is disposed in the center of the upper mold 4, and the remaining section 43 of the upper mold 4 is disposed around the core mold section 40. In Fig. 6, the upper mold 4 is shown by a two-dot chain line when it is in a closed position 401 where it is closed to the lower mold 3, and is shown by a solid line when it is in an open position 402 where it is opened from the lower mold 3. The rotation axis of the upper mold 4 relative to the lower mold 3 is indicated by reference symbol 21.

[0029] 4 and 5, by forming through-hole molding portions 31, 41 in lower mold 3 and upper mold 4, cavity 20 is formed in a frame shape divided into four directions, an upper side H1, both sides W1, W2 in the left-right direction W, and a lower side H2. Cavity 20 has a main cavity portion 200 for molding main backrest portion 11 of foam molded body 1, an upper auxiliary cavity portion 201 for molding upper portion 121 of center armrest portion 12 of foam molded body 1, an outer auxiliary cavity portion 202 for molding outer portion 122 of center armrest portion 12 of foam molded body 1, and a lower auxiliary cavity portion 204 for molding lower portion 124 of center armrest portion 12 of foam molded body 1.

[0030] 4 and 5, the through hole forming portions 31, 41 in this embodiment are formed by a main through hole forming portion 31 for forming an inner wall surface 130 of the through hole 13, which is formed in the lower mold 3, and an auxiliary through hole forming portion 41 formed in the core mold portion 40 of the upper mold 4 and fitted to the inside of the main through hole forming portion 31. As shown in Fig. 7, the branch grooves 32 are formed in the main through hole forming portion 31 so as to be connected to portions corresponding to the multiple sides 133, 134 of the through hole 13, except for a portion corresponding to a corner 135 of the through hole 13.

[0031] The branch groove 32 is formed around the portion of the main through hole molding portion 31 of the lower mold 3 that molds the side portion 134 of the lower side H2 of the through hole 13. As a result, even if the foamable raw material 100 enters the branch groove 32 and solidifies to leave a burr 15 on the lower mold 3 after molding the foam molded body 1, the molding mold 2 can be opened and the burr 15 can be easily removed from the lower mold 3. The branch groove 32 of this embodiment is formed by branching into a portion that molds the side portion 134 of the lower side H2 of the through hole 13 in the main through hole molding portion 31 and a portion that molds the side portion 133 of the inner side W2 in the left-right direction W of the through hole 13. More specifically, the branch groove 32 is formed by branching into a total of three portions, two portions of the portion that molds the side portion 134 of the lower side H2 of the through hole 13 in the main through hole molding portion 31 and one portion that molds the position of the lower side H1 of the side portion 133 of the inner side W2 in the left-right direction W of the through hole 13.

[0032] In this embodiment, the branched groove 32 is branched in three directions and formed in a T-shape. Alternatively, the branched groove 32 may be branched in two or four directions, etc., and formed in a U-shape, a cross shape, etc. The position, shape, etc. of the branched groove 32 may be appropriately changed depending on the foam molded product 1 to be molded.

[0033] The branch grooves 32 are not formed in the main through hole molding part 31 in a portion that molds a corner 135 on the inside W2 in the left-right direction W of a side 134 on the lower side H2 of the through hole 13. With this configuration, burrs 15 formed when the foamable raw material 100 gets into the branch grooves 32 are not formed at the corners 135 of the through hole 13, and the burrs 15 can be easily removed from the foam molded article 1.

[0034] As shown in Figure 7, the branch groove 32 is formed at a position connected to the cavity 20 that molds the foamed molded body 1, taking into consideration the way in which the foamable raw material 100 flows within the cavity 20, so that air A remaining in the cavity 20 can be expelled to the outside when the foamable raw material 100A flowing through the main cavity section 200 and the foamable raw material 100B flowing from the outer sub-cavity section 202 to the lower sub-cavity section 204 join together.

[0035] 4, 5 and 8, the air vent hole 42 is formed in the auxiliary through-hole molding portion 41 of the core mold portion 40. This makes it possible to prevent the foamable raw material 100 from entering the air vent hole 42 before the air A is released when the foamable raw material 100 is injected into the lower mold 3. The air vent hole 42 is provided at the branching position 322 of the multiple branching portions 321 in the branch groove 32, in other words, at the position where the multiple branching portions 321 join together.

[0036] The lower die 3 and the upper die 4 are made of a metal material such as an aluminum material, except for the surface layer of the main through hole forming portion 31 in the lower die 3. The surface layer of the main through hole forming portion 31 in the lower die 3 is made of a resin material. Resin materials are softer and easier to process than metal materials. Therefore, the branch grooves 32 can be easily formed by forming them on the main through hole forming portion 31 made of a resin material. In addition, even if the main through hole forming portion 31 and the auxiliary through hole forming portion 41 come into contact with each other when the molding die 2 is closed, damage to the main through hole forming portion 31 and the auxiliary through hole forming portion 41 can be suppressed.

[0037] Furthermore, since the surface layer of main through hole molding portion 31 is made of a resin material, in some cases it becomes easy to reform branch grooves 32 formed in main through hole molding portion 31 into different branch grooves 32 as appropriate. Note that only the surface layer of main through hole molding portion 31 around the portion where branch grooves 32 are formed may be made of a resin material, or other portions of lower mold 3 other than the surface layer of main through hole molding portion 31 may also be made of a resin material.

[0038] (Other configurations) The main through hole molding portion 31 which forms the inner wall surface 130 of the through hole 13 may be formed separately as appropriate in the lower mold 3 and the core mold portion 40 of the upper mold 4. The main through hole molding portion 31 may be formed in the core mold portion 40. The branch groove 32 may be formed in the sub through hole molding portion 41. The air vent port 42 may be formed in either one or both of the main through hole molding portion 31 and the sub through hole molding portion 41.

[0039] A cloth-like reinforcing material (backing material) such as felt may be provided on the back side 102 and the inside 103 of the foam molded body 1. By using the reinforcing material, the foam molded body 1 is prevented from coming into direct contact with the seat frame, thereby preventing the generation of abnormal noise. The reinforcing material may be placed on the molding surface of the cavity 20 in the core mold part 40 of the upper mold 4 when molding the foam molded body 1, and may be integrated with the foamable raw material 100 when the foamable raw material 100 is foamed.

[0040] (Method of molding foamed molded product 1 and its effects) Next, there will be described a method for molding the foam molded product 1 using the molding die 2, and its functions and effects. The method for molding the foam molded product 1 includes a cavity forming step, a filling step, a removal step, and a removal step.

[0041] As shown in Fig. 6, in the cavity forming step, the foamable raw material 100 is injected into the lower mold 3 with the upper mold 4 open. In addition, before the foamable raw material 100 is injected, a reinforcing material to be integrated with the back side 102 and the inner side 103 of the foamed molded body 1 after molding may be placed in the core mold section 40. The foamable raw material 100 is injected into a plurality of locations in the lower mold 3 so that the foamable raw material 100 is filled evenly inside the cavity 20. For example, the foamable raw material 100 is injected into the portion of the cavity 20 that molds the main backrest portion 11, the portion that molds the periphery of the through-hole 13 of the center armrest portion 12, and the like.

[0042] Next, the upper die 4 is closed on the lower die 3, and the cavity 20 is formed by the lower die 3 and the upper die 4. Then, in the filling step, as shown in Figures 4 and 5, the foamable raw material 100 injected into the cavity 20 foams and flows through the portion of the cavity 20 that molds the main backrest portion 11, and sequentially flows into the portion of the cavity 20 that molds the periphery of the through hole 13 of the center armrest portion 12. In other words, in the portion that molds the periphery of the through hole 13 of the center armrest portion 12, the foamable raw material 100 flows around the through hole molding portions 31, 41, splitting into both sides W1, W2 in the left-right direction W and upper and lower parts H1, H2 in the up-down direction H.

[0043] In the process in which the foamable raw material 100 flows and fills the cavity 20, the air A in the cavity 20 is discharged to the outside of the molding die 2 through the air vent 42. The air A in the cavity 20 also contains gas generated when the foamable raw material 100 foams.

[0044] As shown in Figure 7, the foamable raw material 100A flowing through the portion of the cavity 20 that molds the side portion 133 on the inner side W2 in the left-right direction W of the through hole 13 in the center armrest portion 12 (part of the main cavity portion 200) and the foamable raw material 100B flowing through the portion of the cavity 20 that molds the side portion 134 on the lower side H2 of the through hole 13 in the center armrest portion 12 (lower secondary cavity portion 204) join together near the portion that molds the side portion 134 on the lower side H2 of the through hole 13.

[0045] At this time, as shown in Fig. 8, air A in cavity 20 is discharged to the outside of molding die 2 from air vent port 42 via branch groove 32. Here, branch groove 32 is formed in main through-hole forming portion 31 of lower die 3, branching into a portion that forms side portion 134 on lower side H2 of through hole 13 and a portion that forms side portion 133 on inner side W2 in the left-right direction W of through hole 13. Therefore, even if the positions at which foamable raw materials 100A, 100B join around through-hole forming portions 31, 41 in cavity 20 vary, air A in cavity 20 can be discharged from any branch portion 321 of branch groove 32 to air vent port 42.

[0046] This makes it difficult for the foamable raw materials 100A, 100B to clog the air vent 42, and allows more appropriate air venting within the cavity 20. As a result, in the foamed molded product 1 molded within the cavity 20, air A remaining within the cavity 20 is eliminated, making it difficult for air pockets to occur.

[0047] Next, in the removal process, when the upper mold 4 is opened relative to the lower mold 3, the core mold portion 40 moves from the initial position 403 to a movable position 404 and is separated from the remaining portion 43 of the upper mold 4, and the foamed molded body 1 arranged in the core mold portion 40 of the upper mold 4 is removed.

[0048] Then, in the removal step, as shown in Figures 1 to 3 and 8, burrs 15 formed by the solidification of the expandable raw material 100 that has entered the branch grooves 32 are removed from the foam molded body 1. Burrs formed by the solidification of the expandable raw material 100 that has entered the gap between the mating surfaces of the lower mold 3 and the upper mold 4 are also removed. By removing the burrs 15, it is possible to prevent the appearance of the foam molded body 1 from being deteriorated by the burrs 15.

[0049] In this way, according to the molding method of the foam molded body 1 of this embodiment, air pockets are less likely to form around the through holes 13 formed in the foam molded body 1, and the formation of cavities in the foam molded body 1 can be prevented.

[0050] The present invention is not limited to the embodiments, and further different embodiments can be configured without departing from the spirit of the present invention. In addition, the present invention includes various modifications, modifications within the scope of the equivalents, and the like. [Explanation of symbols]

[0051] 1. Foam molding 100 Effervescent ingredients 13 Through hole 131 Upper edge 132 Outer Edge 133 Inner Edge 134 Lower edge 135 Corner 14 Folded section 15. Bali 2 Molding mold 20 Cavity 3 Lower mold 31 Main through hole molding part 32 Branch groove 4 Upper mold 40 Core mold section 41 Sub through hole molding part 42 Air vent

Claims

1. A method for molding a foamed molded body having a through hole formed into a shape having at least three corners and at least three sides, using a molding die, comprising: the molding die includes an upper die, a lower die that forms a cavity between the upper die and the lower die, and a through hole molding portion that is formed by a part of the upper die and a part of the lower die and that mates with each other while penetrating the cavity to mold the through hole; A branch groove is formed in the through hole forming portion, the branch groove being branched into a plurality of grooves and connected to the cavity, the branch groove is formed in the through hole forming portion so as to be connected to portions corresponding to the plurality of side portions, except for portions corresponding to the corner portions, an air vent hole communicating the branch groove with an outside of the molding die is formed in at least one of the upper die and the lower die; The air vent port is provided at a position where a plurality of branched portions of the branch groove join together, a cavity forming step of injecting a foamable raw material into the lower mold and closing the upper mold against the lower mold to form the cavity; a filling step of foaming and flowing the foamable raw material in the cavity, and filling the cavity with the foamable raw material while discharging air in the cavity through the branch groove and from the air vent hole to the outside of the molding die.

2. The method for molding a foam molded body according to claim 1 , further comprising the step of: after the filling step, performing a removing step of removing flash formed by solidification of the foamable raw material that has entered the branch grooves from the foam molded body.

3. A mold for molding a foamed molded body having a through hole formed in a shape having at least three corners and at least three sides, the molding die includes an upper die, a lower die that forms a cavity between the upper die and the lower die, and a through hole molding portion that is formed by a part of the upper die and a part of the lower die and that mates with each other while penetrating the cavity to mold the through hole; A branch groove is formed in the through hole forming portion, the branch groove being branched into a plurality of grooves and connected to the cavity, the branch groove is formed in the through hole forming portion so as to be connected to portions corresponding to the plurality of side portions, except for portions corresponding to the corner portions, an air vent hole communicating the cavity with the outside of the mold is formed in the branch groove; The air vent port is provided at a position where a plurality of branched portions of the branched groove join together.

4. the through hole forming portion is formed by a part of the upper mold and a part of the lower mold, the branch groove is formed in the through hole forming portion of the lower die, The mold for forming a foam molded product according to claim 3 , wherein the air vent hole is formed in the through-hole molding portion of the upper mold.

5. The molding die for foam molded products according to claim 4 , wherein at least a portion of the through hole molding portion in the lower die where the branched grooves are formed is made of a resin material.

Images