Rotational molding

Abstract

To make it possible to mold a plurality of molded products at one time with a mold having simple mold structure.SOLUTION: A rotational molding mold 10 used for rotational molding and capable of molding a plurality of molded products includes: a frame 20 with a plurality of mounting frames 21; and a plurality of molding molds 30 each having a molding part 32 for molding the molded product, each mounted so that the molding part 32 faces an interior space of the rotational molding mold 10. Furthermore, the rotational molding mold includes: a part other than the molding part 32 of an inner surface of each molding mold 30 facing the interior space of the rotational molding mold 10; and insulation parts 42, 44 covering an inner surface 23 of each mounting frame 21 facing the interior space of the rotational molding mold 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a rotational molding die capable of molding multiple molded articles. [Background technology]

[0002] Patent Document 1 discloses an injection molding die that can mold multiple molded products at once. This die adjusts the runner length with a separate adjustment mechanism to balance the resin filling of each cavity and ensure uniform quality of the molded products molded in each cavity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-62399 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned mold has a complicated structure due to the adjustment mechanism, and therefore the manufacturing cost of the mold is high. In addition, the adjustment work using the adjustment mechanism is time-consuming. Therefore, a technology that enables molding of multiple molded products at once with a mold of a simple mold structure is desired. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms. A rotational molding die used for rotational molding, capable of molding a plurality of molded articles, comprising: A frame body having a plurality of mounting frames; a plurality of molding dies each having a molding portion for molding a molded product, the molding portion being arranged so as to face an internal space of the rotational molding die, and the plurality of molding dies being attached to the plurality of mounting frames; A heat insulating portion disposed in the internal space; Equipped with The molding portion is a portion having a surface shape corresponding to a surface shape of the molded product, The heat insulating portion is a portion of an inner surface of each mold facing the internal space other than the molding portion, and , covering the inner surface of each mounting frame facing the internal space; The rotational molding die is configured such that, when heated to a temperature equal to or higher than the melting temperature of a molding material, the heat insulating portion has a surface temperature lower than the melting temperature.

[0006] (1) According to one aspect of the present disclosure, there is provided a rotational molding die for use in rotational molding, capable of molding a plurality of molded articles, comprising a frame having a plurality of mounting frames, and a plurality of molding dies having molding portions for molding the molded articles, each of which is mounted such that the molding portions face the internal space of the rotational molding die. This type of rotational molding die is a die with a simple mold structure, including a frame body having multiple mounting frames and multiple molding dies mounted on the multiple mounting frames. When rotational molding is performed using this type of rotational molding die, molded products can be molded at the molding parts of each mold. Therefore, this rotational molding die makes it possible to produce multiple molded products at once using a die with a simple mold structure. Furthermore, rotational molding makes it easy to achieve uniform quality of molded products. (2) The rotational molding die of the above-described embodiment may further include a heat insulating portion that covers the inner surfaces of each molding die that face the internal space other than the molding portion, and the inner surfaces of each mounting frame that face the internal space. According to this form of rotational molding die, during rotational molding, the molding material is prevented from melting and adhering to the inner surfaces of the mounting frames and to the inner surfaces of the molds other than the molding parts, so that unnecessary molding is not performed in the parts other than the molding parts. This makes it possible to omit post-processing steps such as cutting off the unnecessary parts molded around each molded product. (3) The multiple molding dies of the rotational molding die of the above embodiment may be composed of one type of molding die, or two or more different types of molding dies. With this type of rotational molding die, when the multiple molding dies are composed of one type of molding die, multiple molded products of one type can be molded simultaneously, and when the multiple molding dies are composed of two or more different types of molding dies, multiple different types of molded products can be molded simultaneously. The present disclosure can be realized in various forms, such as not only the rotational molding die of the above-mentioned form, but also a rotational molding device including this rotational molding die. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a rotational molding die as a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic cross section taken along line II-II of FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing the cross section taken along line III-III in FIG. [Figure 4] 1A to 1C are explanatory diagrams showing the assembly procedure of a rotational molding die. [Diagram 5] FIG. 11 is a perspective view showing a schematic configuration of a rotational molding die as a second embodiment. [Figure 6] 11 is an explanatory diagram showing the assembly procedure of an upper mold frame with a casting mold already attached. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. First embodiment: Fig. 1 is a perspective view showing a schematic configuration of a rotational molding die 10 according to a first embodiment. Fig. 2 is a cross-sectional view showing a schematic cross section taken along line II-II in Fig. 1, and Fig. 3 is a cross-sectional view showing a schematic cross section taken along line III-III in Fig. 1.

[0009] The rotational molding die 10 comprises a frame 20 having six mounting frames 21, and six panel-shaped molding dies 30 mounted on the six mounting frames 21. The frame 20 has a structure in which the six mounting frames 21 are arranged in a rectangular parallelepiped shape so that the contour of a solid body formed by the six mounting frames 21 is roughly rectangular. Each mounting frame 21 is provided with a mounting groove 22 into which an end of the molding die 30 is fitted. The rotational molding die 10 has a structure in which the contour is roughly rectangular and has a hollow shape, as the end of the molding die 30 is mounted in the mounting groove 22 of each mounting frame 21.

[0010] The frame 20 is composed of a lower formwork 210 and an upper formwork 220. The lower formwork 210 is composed of five mounting frames 21 corresponding to the four side surfaces excluding the top surface and the bottom surface of the six rectangular parallelepiped mounting frames 21. The upper formwork 220 is composed of one mounting frame 21 corresponding to the top surface of the rectangular parallelepiped of the six mounting frames 21. The upper formwork 220 is fastened to the top of the lower formwork 210 to form the frame 20 having a rectangular parallelepiped outline.

[0011] Each mounting frame 21 of the lower mold frame 210 is composed of four columnar frame components 211 surrounding the rectangular forming mold 30. Each frame component 211 has a groove 213 that constitutes the mounting groove 22 on the surface surrounding the forming mold 30. Similarly, the mounting frame 21 of the upper mold frame 220 is composed of four columnar frame components 221 surrounding the forming mold 30. Each frame component 221 has a groove 223 that constitutes the mounting groove 22 on the surface surrounding the forming mold 30.

[0012] The four frame components 211 at the top of the lower formwork 210 are provided with flanges 212, and the flanges 212 are provided with fastening holes 214 for fastening the upper formwork 220. The four frame components 221 of the upper formwork 220 are provided with flanges 222, and the flanges 222 are provided with fastening holes 224 for fastening the lower formwork 210. The lower formwork 210 and the upper formwork 220 are fastened together by fastening bolts and fastening nuts (not shown) that are inserted into the fastening holes 214 and the fastening holes 224 facing them.

[0013] The molding die 30 mounted on each mounting frame 21 has a molding portion 32 on the inner surface facing the internal space of the rotational molding die 10. The molding portion 32 is a portion having a surface shape corresponding to the surface shape of the molded product MP to be molded.

[0014] The inner surface 23 of the mounting frame 21 facing the internal space of the rotational molding die 10 is provided with a heat insulating part 42 so as to cover the surface. Also, a heat insulating part 44 is provided on the part of the molding die 30 other than the molding part 32 so as to cover the part. The heat insulating part 42 can be formed by attaching a heat insulating material or painting a heat insulating agent. Similarly, the heat insulating part 44 can be formed by attaching a heat insulating material or painting a heat insulating agent. The heat insulating parts 42, 44 are such that the surface temperature is lower than the melting temperature of the molding material when heated to a temperature higher than the melting temperature of the molding material. As the heat insulating material or heat insulating agent, a material having a heat resistance higher than the heating temperature of the mold, for example, super engineering plastics such as PTFE, PEEK, PI, silicon resin, ceramic, etc., can be used.

[0015] 4 is an explanatory diagram showing the assembly procedure of the rotational molding die 10. As described below, the rotational molding die 10 is constructed by constructing a lower frame 210 with a molding die already attached and an upper frame 220 with a molding die already attached, filling the lower frame 210 with a molding material, and fastening the lower frame 210 and the upper frame 220 together.

[0016] The lower formwork 210 is composed of three divided lower formwork portions 210a, 210b, and 210c. The first lower formwork portion 210a is a portion composed of five frame components 211, excluding four frame components 211 provided with upper flanges 212 and three frame components 211 on one side, among the twelve frame components 211 that constitute the cubic outline of the lower formwork 210. The second lower formwork portion 210b is a portion composed of three frame components 211 on one side that are excluded from the first lower formwork portion 210a. The third lower formwork portion 210c is a portion composed of four frame components 211 provided with upper flanges 212 that are excluded from the first lower formwork portion 210a and the second lower formwork portion 210b.

[0017] The first lower mold portion 210a can accommodate four molding dies 30 by inserting the molding dies 30 into three molding die insertion positions formed by three frame components 211 aligned in the vertical direction, and by inserting the molding dies 30 into one molding die insertion position formed by two frame components 211 aligned in the horizontal direction.

[0018] Similarly to the first lower formwork part 210a, the second lower formwork part 210b can accommodate one molding die 30 by inserting the molding die 30 into one molding die insertion position defined by two frame components 211 arranged along the vertical direction.

[0019] Then, the second lower frame part 210b, on which the molding die has been attached, is fitted and fastened to the first lower frame part 210a, on which the molding die has been attached, from the side where the end of the molding die 30 is exposed, and the third lower frame part 210c is fitted and fastened to the first lower frame part 210a, on which the molding die has been attached, from above where the end of the molding die 30 is exposed, thereby forming the lower frame 210 on which the molding die has been attached. Note that the lower frame parts can be fastened to each other using fastening members (not shown), for example, snap locks.

[0020] The upper formwork 220 is composed of two divided upper formwork portions 220a and 220b. The first upper formwork portion 220a is a portion composed of three frame constituent portions 221 excluding one frame constituent portion 221 out of the four frame constituent portions 221 on which the flanges 222 of the upper formwork 220 are provided. The second upper formwork portion 220b is a portion composed of the frame constituent portion 211 on which the one flange 222 is provided, excluded from the first upper formwork portion 220a.

[0021] First upper mold portion 220a can accommodate one molding die 30 by inserting molding die 30 into one molding die insertion position formed by three frame components 221.

[0022] Then, the second upper form part 220b is fitted into the first upper form part 220a to which the casting mold has already been attached from the side where the edge of the casting mold 30 is exposed, and fastened to form the upper form part 220 to which the casting mold has already been attached. Note that the upper form parts can also be fastened to each other using fastening members (not shown), such as snap locks, in the same manner as the lower form parts are fastened to each other.

[0023] The rotational molding die 10 can be constructed by placing the upper frame 220 with a molding die attached on top of the lower frame 210 with a molding die attached as described above so that the fastening holes 214 of the lower frame 210 and the fastening holes 224 of the upper frame 220 face each other, and fastening them together using fastening bolts and fastening nuts not shown.

[0024] The rotational molding die 10 having the above-mentioned configuration is rotated by a rotation device while being heated by a heating device (not shown), whereby the molding material filled in the internal space of the rotational molding die 10 is melted and adhered to the molding parts 32 of each molding die 30, thereby forming a solid molded product MP having a surface shape corresponding to the molding parts 32 of each molding die 30. As the molding material, various thermoplastic resin materials such as PP and PE can be used as the resin material constituting the molded product MP to be molded.

[0025] When rotational molding is performed using the rotational molding die 10 described above, a molded product MP can be molded using each of the attached molding dies 30, so that it is possible to produce multiple molded products MP at once. In addition, the rotational molding die 10 is a die with a simple mold structure that includes a frame 20 having multiple mounting frames 22, and multiple molding dies 30 attached to the multiple mounting frames 22. Therefore, the rotational molding die 10 can have a simpler and cheaper structure than the injection molding die described in the prior art, and can produce multiple molded products at once, making it possible to produce molded products at low cost.

[0026] Furthermore, rotational molding can produce multiple molded products MP using multiple molds 30 in a controlled environment with simple adjustments such as rotation speed and heating temperature, making it easy to achieve uniform quality.

[0027] Furthermore, since the rotational molding die 10 can be constructed by mounting a molding die 30 on each of a number of mounting frames 21, the molded product to be produced can be easily changed by changing the molding die to be mounted.

[0028] Also, a heat insulating section 42 is provided so as to cover the inner surface 23 of each mounting frame 21 facing the internal space of the rotational molding die 10, and a heat insulating section 44 is provided so as to cover the portions of each molding die 30 other than the molding portion 32. Therefore, during rotational molding, it is possible to prevent the molten molding material from adhering to the portions where the heat insulating sections 42 and 44 are provided, and to prevent wasteful molding from occurring in the portions other than the molding portion 32. This makes it possible to omit post-processing steps such as cutting off wasteful portions generated around the molded product.

[0029] B. Second embodiment: 5 is a perspective view showing a schematic configuration of a rotational molding die 10B as a second embodiment. The rotational molding die 10B includes a frame 20B having eight mounting frames 21B, and eight panel-shaped molding dies 30B mounted on the eight mounting frames 21B. The frame 20B has a structure in which the eight mounting frames 21B are arranged in an octahedral state so that the contour of a solid formed by the eight mounting frames 21B is roughly an octahedron. Each mounting frame 21B is provided with a mounting groove 22B into which the molding die 30B is fitted.

[0030] The frame body 20B is composed of a lower formwork 210B and an upper formwork 220B. The upper formwork 220B is composed of four mounting frames 21B corresponding to the four side surfaces on the upper side of the eight octahedral mounting frames 21B. Like the upper formwork 220B, the lower formwork 210B is also composed of four mounting frames 21B corresponding to the four side surfaces on the lower side of the eight octahedral mounting frames 21B. The upper formwork 220B is fastened to the top of the lower formwork 210B to form a frame body 20B having an octahedral outline.

[0031] Each mounting frame 21B of the upper mold frame 220B is composed of three columnar frame components 221B surrounding the triangular forming mold 30B. Similarly, each mounting frame 21B of the lower mold frame 210B is composed of three columnar frame components 211B surrounding the forming mold 30B.

[0032] Four frame components 221B at the bottom of the upper frame 220B on the side of the lower frame 210B are provided with flanges 222B, and fastening holes 224B are provided in the flanges 222B. Four frame components 211B at the top of the lower frame 220B on the side of the upper frame 220B are provided with flanges 212B, and fastening holes 214B are provided in the flanges 212B for fastening to the upper frame 220B. The lower frame 210B and the upper frame 220B are fastened together by fastening bolts and fastening nuts (not shown) that are inserted into the fastening holes 214B and the fastening holes 224B facing the fastening holes 214B.

[0033] The molding die 30B mounted on each mounting frame 21B has a molding portion 32B on the inner surface facing the internal space of the rotational molding die 10B. The shape of the molding portion 32B is a portion having a surface shape corresponding to the surface shape of the molded product to be molded, and may be the same as or different from the molding portion 32 of the molding die 30 of the first embodiment.

[0034] Although not shown in the figure, in the rotational molding die 10B, similar to the rotational molding die 10, an insulating portion is provided to cover the surface of the mounting frame 21B facing the internal space of the rotational molding die 10B and the portions other than the molding portion 32B of the molding die 30B.

[0035] 6 is an explanatory diagram showing the assembly procedure of the upper mold 220B with the casting mold already attached. The upper mold 220B is composed of one divided first upper mold part 220Ba and four second upper mold parts 220Bb. The first upper mold part 220Ba is a part composed of five frame components 221B excluding the four frame components 221B provided with the lower flanges 222B out of the eight frame components 221B that constitute the quadrangular pyramid-shaped outline of the upper mold 220B. The second upper mold part 220b is the part of the frame component 221B provided with the lower flanges 222B.

[0036] The upper mold 220B with the casting mold attached can be configured by inserting the casting mold 30B into the four casting mold insertion positions formed by the four frame components 221B of the first upper mold part 220Ba, and fitting and fastening the four second upper mold parts 220Bb into the first upper mold part 220Ba with the casting mold attached. Note that the upper mold parts can be fastened together using fastening members (not shown), such as snap locks.

[0037] Although not shown, the lower mold frame 210B to which the casting molds have already been attached can be configured in the same manner as the upper mold frame 220B.

[0038] The rotational molding die 10B of the second embodiment described above is also capable of producing multiple molded products at one time, similar to the rotational molding die 10 of the first embodiment. In addition, since the rotational molding die 10B can be fitted with more molding dies than the rotational molding die 10, it is possible to produce more molded products at one time. In addition, it can be made to have a simpler and cheaper structure than other dies such as injection molding, and since it is possible to produce multiple molded products at one time, it is possible to produce molded products at low cost. In addition, it is easy to achieve uniformity in the quality of the multiple molded products produced. In addition, it is easy to change the molded product to be produced. In addition, since it is possible to prevent unnecessary molding in parts other than the molding part 32B, it is possible to omit post-processing steps such as cutting off unnecessary parts generated around the molded product.

[0039] C. Other embodiments: (C1) The rotational molding die 10 of the first embodiment is an example of a die having a structure in which a rectangular molding die 30 is attached to six mounting frames 21 arranged in a rectangular parallelepiped shape on a frame body 20, and the rotational molding die 10B of the second embodiment is an example of a die having a structure in which a triangular molding die 30B is attached to eight mounting frames 21B arranged in an octahedral shape on a frame body 20B. However, the present invention is not limited to this, and a die having a structure in which a plurality of molding dies are attached to a plurality of mounting frames arranged in various polyhedral shapes on a frame body may be used. In addition, it is not necessary to be limited to a die using a frame body having a structure in which one mounting frame is arranged along each face of a polyhedron, and it is sufficient if the die uses a frame body having a plurality of mounting frames and a molding die is attached to each mounting frame to form a hollow shape.

[0040] (C2) In the above embodiment, an example was described in which a heat insulating part was provided to cover the surface of the mounting frame facing the internal space of the rotational molding die and the parts of the molding die other than the molding part, but the heat insulating part can be omitted. If the heat insulating part is omitted, there is a possibility that unnecessary parts will be molded around the molded product, and a process to remove the unnecessary parts that are generated may be necessary, but apart from this point, the same effect as in the embodiment can be obtained.

[0041] (C3) In the above embodiment, the multiple molds mounted are described as molds having molding parts of the same shape. However, this is not limited to this. For example, in the rotational molding die 10 of the first embodiment, as the six molds mounted, three molds having two different types of molding parts may be used, two molds having three different types of molding parts may be used, or one mold having six different types of molding parts may be used. Also, among the three different types of molds, three of one type, two of the other type, and one of the remaining type may be used. In other words, the multiple molds mounted may be composed of one type of mold, or two or more different types of molds. When the multiple molds are composed of one type of mold, multiple molded products of one type can be molded simultaneously, and when the multiple molds are composed of two or more different types of molds, multiple molded products of different types can be molded simultaneously. This makes it possible to produce a wide variety of products in small quantities while suppressing increases in costs. Furthermore, during the development process, it is possible to respond to design changes in a short period of time, thereby making it possible to suppress increases in costs and shorten development time.

[0042] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0043] Reference Signs List 10...Rotational molding die, 10B...Rotational molding die, 20...Frame body, 20B...Frame body, 21...Mounting frame, 21B...Mounting frame, 22...Mounting groove, 22B...Mounting groove, 23...Surface, 30...Mold, 30B...Mold, 32...Molding portion, 32B...Molding portion, 42...Insulating portion, 44...Insulating portion, 210...Lower form, 210B...Lower form, 210a...First lower form part, 210b...Second lower form part, 210c...Third lower form part, 211...Frame component, 211B...Frame Constituent part, 212... flange, 212B... flange, 213... groove, 214... fastening hole, 214B... fastening hole, 220... upper formwork, 220B... upper formwork, 220a... first upper formwork part, 220b... second upper formwork part, 220Ba... first upper formwork part, 220Bb... second upper formwork part, 221... frame constituent part, 221B... frame constituent part, 222... flange, 222B... flange, 223... groove, 224... fastening hole, 224B... fastening hole, MP... molded product

Claims

1. A rotational molding die used for rotational molding, capable of molding a plurality of molded articles, comprising: A frame body having a plurality of mounting frames; a plurality of molding dies each having a molding portion for molding a molded product, the molding portion being arranged so as to face an internal space of the rotational molding die, and the plurality of molding dies being attached to the plurality of mounting frames; A heat insulating portion disposed in the internal space; Equipped with The molding portion is a portion having a surface shape corresponding to a surface shape of the molded product, the heat insulating portion covers a portion of an inner surface of each molding die facing the internal space other than the molding portion and an inner surface of each mounting frame facing the internal space; The rotational molding die is configured such that, when heated to a temperature equal to or higher than the melting temperature of a molding material, the heat insulating portion has a surface temperature lower than the melting temperature.

2. 2. The rotational molding die according to claim 1, The plurality of molds may be one type of mold or two or more different types of molds.

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