Method for producing foamable resin molded article

Abstract

This method for producing a foamable resin molded article includes: a preparation step for disposing an insert component in a cavity space of a mold; a molding step for filling the cavity space with a granular agent of a foamable resin and curing the foamable resin to mold a foamable resin intermediate; a demolding step for demolding the foamable resin intermediate from the mold; and a joining step for joining the insert component and the foamable resin intermediate.

Description

Method for manufacturing a foamed resin molded product

[0001] The technology of the present disclosure relates to a method for manufacturing a foamed resin molded product.

[0002] Resin molded products having insert parts are used in various applications. As a method for manufacturing such resin molded products, a method is known in which an insert part is placed in a mold, and after filling the cavity space of the mold with molten resin, the resin is cured. For example, Patent Document 1 discloses a method for manufacturing a resin molded part including a placement step of placing an insert part in a mold, a filling step of filling the mold with resin, an accumulation step of accumulating a pressing force in a pressing part, and a release step of releasing the pressing force when the resin is cured.

[0003] Further, resin molded products with high lightness using foamed resin are known. For example, Patent Document 2 discloses a method for molding a foamed molded body in which foamed resin particles are filled in the molding space of a mold and the foamed molded body is foamed in the molding space.

[0004] JP-A-2013-78892 JP-A-2014-69476

[0005] Here, in a resin molded product having an insert part, it may be required to increase the bonding strength between the insert part and the resin. For example, when a resin molded product having an insert part is used as a structural member and the insert part is used as a connection portion with another part, it is necessary to increase the bonding strength between the insert part and the resin. To increase the bonding strength between the insert part and the resin, for example, it is conceivable to roughen the surface of the insert part or to provide irregularities on the surface of the insert part to provide a mechanical bonding portion.

[0006] However, if a method for manufacturing a resin molded product having an insert component as described in Patent Document 1 is attempted using foamed resin granules as described in Patent Document 2, for example, roughening the surface of the insert component or creating irregularities on the surface of the insert component to provide mechanical bonding points may lead to a decrease in the fluidity of the foamed resin granules. A decrease in the fluidity of the foamed resin granules may result in incomplete filling of the mold with the foamed resin granules.

[0007] Therefore, the technology disclosed herein has been made in view of the above-mentioned problems, and the object of this disclosure is to provide an improved manufacturing method that can suppress the decrease in the fluidity of foamed resin granules and increase the bonding strength between the insert part and the resin.

[0008] To solve the above problems, according to one aspect of the technology of this disclosure, a method for manufacturing a foamed resin molded product is provided, which includes a preparation step of arranging an insert component in the cavity space of a mold; a molding step of filling the cavity space with foamed resin granules and curing the foamed resin to form a foamed resin intermediate; a demolding step of removing the foamed resin intermediate from the mold; and a joining step of joining the insert component and the foamed resin intermediate.

[0009] As described above, the object of this disclosure is to provide a method for manufacturing foamed resin molded articles that can suppress the decrease in the fluidity of the foamed resin granules and increase the bonding strength between the insert part and the resin.

[0010] This is a perspective view showing a front pillar using a fiber-reinforced resin molded product manufactured by the manufacturing method for fiber-reinforced resin molded products according to the first embodiment of this disclosure. This is a perspective view showing an insert part provided in a foamed resin molded product according to the same embodiment. This is a cross-sectional view of the front pillar shown in Figure 1 along the line I-I. This is a cross-sectional view of the front pillar shown in Figure 1 along the line II-II. This is an explanatory diagram showing the steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing a mold used in the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the preparation steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the molding steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the molding steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the demolding steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the joining steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the fiber-reinforced resin lamination steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing an example of the surface treatment steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the steps of the manufacturing method for foamed resin molded products according to the second embodiment of this disclosure. This is an explanatory diagram showing the preparation steps of the manufacturing method for foamed resin molded products according to the same embodiment. This is an explanatory diagram showing the molding process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the molding process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the joining process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the demolding process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is a perspective view showing an insert part used in the method for manufacturing a foamed resin molded product according to the third embodiment of this disclosure. This is an explanatory diagram showing the process of the method for manufacturing a foamed resin molded product according to the third embodiment of this disclosure. This is an explanatory diagram showing the preparation process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the preparation process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the molding process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the molding process and joining process of the method for manufacturing a foamed resin molded product according to the same embodiment. This is an explanatory diagram showing the demolding process of the method for manufacturing a foamed resin molded product according to the same embodiment.This is an explanatory diagram showing the fiber-reinforced resin lamination process in the manufacturing method of a foamed resin molded product according to the same embodiment.

[0011] Preferred embodiments of the technology of this disclosure will be described in detail below with reference to the attached drawings. In this specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0012] <<1. First Embodiment>> <1-1. Fiber-reinforced resin composite material> First, an example of a fiber-reinforced resin composite material including a foamed resin molded product obtained by the method for manufacturing a foamed resin molded product according to the first embodiment of this disclosure will be described.

[0013] Figures 1 to 4 are explanatory diagrams showing an example of a fiber-reinforced resin composite material, which is a structural component of a vehicle body. Figure 1 shows a perspective view of a front pillar as a structural component of a vehicle body. Figure 2 shows a perspective view of an insert part provided in a foamed resin molded product. Figure 3 shows a cross-sectional view from above of the I-I section of the front pillar shown in Figure 1. Figure 4 shows a cross-sectional view from above of the II-II section of the front pillar shown in Figure 1.

[0014] The front pillar 1 extends along the height direction of the vehicle body and is formed in a columnar shape. The front pillar 1 comprises a core material 3 having a first insert part 10a, a second insert part 10b, and a foamed resin that encloses the first insert part 10a and the second insert part 10b, and a fiber-reinforced resin layer 5 that covers the core material 3. The illustrated front pillar 1 has the first insert part 10a in the center in the height direction and the second insert part 10b in the lower part in the height direction. The front pillar 1 is made of a fiber-reinforced resin composite material, achieving high strength and lightweight. In particular, the core material 3 is made of foamed resin, resulting in excellent lightweight properties.

[0015] Core material 3 is a foamed resin molded product formed by molding foamed resin granules using a mold. The foamed resin granules are, for example, polymethacrylimide (PMI) resin granules, such as "Lohacell (registered trademark)," and are molded as a hard foam by filling a mold with them and allowing them to harden. The foamed resin may be a resin other than PMI resin, but polymethacrylimide (PMI) resin, in particular, has excellent mechanical strength, heat resistance, and heat processability.

[0016] The first insert part 10a and the second insert part 10b are metal parts such as steel or aluminum, and may be pre-formed processed products. The first insert part 10a and the second insert part 10b are each embedded in foamed resin so as not to fall out of the core material 3.

[0017] As shown in Figure 2, the first insert part 10a, located in the center of the front pillar 1 in the height direction, has a main body portion 11 and a flange portion 13. The main body portion 11 has an oval shape in plan and a predetermined thickness. The first insert part 10a has two bottomed screw holes 15 that extend in the thickness direction in the main body portion 11. The surface of the first insert part 10a through which the screw holes 15 open is exposed to the outside of the front pillar 1 via holes provided in the fiber-reinforced resin layer 5.

[0018] The flange portion 13 is provided on one end of the main body portion 11 in the thickness direction, has a rectangular planar shape, and protrudes from the main body portion 11 on both sides in a direction intersecting the thickness direction. The flange portion 13 is located on the central side of the core material 3 and embedded in the foamed resin, which prevents the first insert component 10a from falling out of the core material 3. Because the first insert component 10a has a simple shape with the flange portion 13 protruding from the rectangular main body portion 11, it does not hinder the fluidity of the foamed resin.

[0019] Furthermore, as shown in Figures 3 and 4, a bonding material 7 is provided between the side surface of the main body 11 and the core material 3, which is made of a foamed resin molded product. The bonding material 7 is not particularly limited and can be any resin adhesive such as epoxy resin. The bonding material 7 increases the bonding strength between the first insert part 10a and the foamed resin, making it less likely for the first insert part 10a to fall out of the core material 3.

[0020] The second insert component 10b, located at the lower part of the front pillar 1 in the height direction, has the same configuration as the first insert component 10a.

[0021] The fiber-reinforced resin layer 5 is formed using a fiber-reinforced resin, for example, in which carbon fibers are impregnated with a thermoplastic resin or thermosetting resin as a matrix resin. For example, the fiber-reinforced resin layer 5 is formed by winding continuous fibers around a molded core material 3 and curing them together with the matrix resin. Alternatively, the fiber-reinforced resin layer 5 may be formed by laminating and curing sheet-like fiber-reinforced resin sheets.

[0022] When the matrix resin is a thermoplastic resin, the main material may be one or more of the following: polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin (acrylonitrile-butadiene-styrene copolymer synthetic resin), polystyrene resin, AS resin (acrylonitrile-styrene copolymer synthetic resin), polyamide resin, polyacetal resin, polycarbonate resin, polyester resin, PPS (polyphenylene sulfide) resin, fluororesin, polyetherimide resin, polyetherketone resin, and polyimide resin. Alternatively, the thermoplastic resin may be a copolymer of the above resins. When a mixture of these thermoplastic resins is used as the matrix resin, a compatibilizer may be added. Furthermore, the thermoplastic resin may be given a flame retardant such as a brominated flame retardant, a silicon-based flame retardant, or red phosphorus.

[0023] Furthermore, if the matrix resin is a thermosetting resin, its main component may be one or more of the following: epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, polyurethane resin, or silicone resin. Additionally, appropriate curing agents and reaction accelerators may be added to the thermosetting resin.

[0024] The carbon fibers may include, for example, continuous fibers oriented in the longitudinal direction of the front pillar 1 (axial fibers) and continuous fibers oriented in a direction intersecting the longitudinal direction (cross fibers) in appropriate proportions. The amount of axial fibers can be adjusted to control the tensile stress generated by the load input during a side collision. The amount of cross fibers can be adjusted to control the stiffness against the input load during a side collision, thereby adjusting the amount of energy absorbed. In addition, the carbon fibers may also include short fibers in addition to continuous fibers, and may include other fibers other than carbon fibers as reinforcing fibers.

[0025] In this embodiment, at least the outer circumference of the front pillar 1 around the height axis is covered with a fiber-reinforced resin layer 5, and the fiber-reinforced resin layer 5 has holes that expose the first insert part 10a and the second insert part 10b, respectively. The first insert part 10a and the second insert part 10b are used, for example, as connecting parts for a door hinge. The insert parts may have other functions, such as increasing the strength of the foamed resin molded product.

[0026] In the front pillar 1 according to the first embodiment, the core material 3 is made of a foamed resin molded product in which a first insert part 10a and a second insert part 10b are embedded. The first insert part 10a and the second insert part 10b have flange portions 13 embedded in the foamed resin, making them less likely to fall out of the core material 3. Furthermore, the bonding strength between the first insert part 10a and the second insert part 10b and the foamed resin is increased by the bonding material 7, making them even less likely to fall out of the core material 3. Therefore, even when the load on the first insert part 10a and the second insert part 10b is large, such as in the connection part of a door hinge, it is possible to make a vehicle body structural member that is highly durable and lightweight.

[0027] <1-2. Manufacturing Method> Next, an example of a method for manufacturing a fiber-reinforced resin composite material, including a method for manufacturing a foamed resin molded product according to the first embodiment of this disclosure, will be described.

[0028] Figure 5 is an explanatory diagram showing the steps of the manufacturing method for this foamed resin molded product. Figures 6 to 11 are explanatory diagrams showing each step of the manufacturing method for the foamed resin molded product. Figures 7 to 11 show cross-sections of the front pillar 1 shown in Figure 1 where the first insert part 10a is provided.

[0029] (Preparation Process) First, as a preparation process, insert parts are placed in the cavity space of the mold. Figure 6 shows a set of molds 21a and 21b that, when combined, form a cavity space 23. As shown in Figure 6, the molding surface of the mold 21a is provided with convex support parts 25a and 25b on which the first insert part 10a and the second insert part 10b are respectively placed. The mold 21a also has an injection port 26 for pouring foaming resin granules into the cavity space 23 from outside the molds 21a and 21b to fill it. There may be one injection port 26 or multiple ports. Note that the upper part of the molds 21a and 21b shown in Figure 6 corresponds to the lower part of the front pillar 1 in the height direction shown in Figure 1.

[0030] Figure 7 is an explanatory diagram showing the preparation process. As shown in Figure 7, the first insert part 10a is supported by the support portion 25a of the mold 21a. The support portion 25a consists of a pair of protrusions 25aa and 25ab, and the flange portion 13 of the first insert part 10a is placed on the support portion 25a. The main body portion 11 of the first insert part 10a is positioned between the pair of protrusions 25aa and 25ab. The depth (height) of the space between the pair of protrusions 25aa and 25ab is equal to the height of the main body portion 11 of the first insert part 10a. Although not shown, the second insert part 10b is similarly supported by the support portion 25b of the mold 21a.

[0031] (Molding Process) Next, foaming resin granules are filled into the cavity space of the mold, and the foaming resin is cured to form a foaming resin intermediate. Figures 8 and 9 are explanatory diagrams showing the molding process. As shown in Figure 8, a set of molds 21a and 21b are combined to form a cavity space 23. Also, as shown in Figure 9, foaming resin granules 31 are poured in from the injection port 26 to fill the cavity space 23 with foaming resin granules 31. The foaming resin granules 31 flow through the cavity space 23 while foaming and filling it.

[0032] Furthermore, since the first insert component 10a and the second insert component 10b, as well as the support portion 25a that supports the first insert component 10a and the second insert component 10b, have a simple shape, the flow of the foamed resin granules 31 is less likely to be obstructed.

[0033] After filling the cavity space 23 with foamed resin granules 31, the molds 21a and 21b are cooled to cure the foamed resin and form a foamed resin intermediate 33. This forms a foamed resin intermediate 33 to which the flange portion 13 of the first insert part 10a is mechanically bonded. Although not shown, the flange portion of the second insert part 10b is similarly mechanically bonded to the foamed resin intermediate 33.

[0034] (Demolding Process) Next, the hardened foamed resin intermediate is removed from the mold. Figure 10 is an explanatory diagram showing the demolding process. As shown in Figure 10, the molds 21a and 21b are separated, and the foamed resin intermediate 33 is removed from the molds 21a and 21b. This creates a gap 9 in the foamed resin intermediate 33 where the support portion 25a of the mold 21a was located. Although not shown, a similar gap 9 is formed where the support portion 25b of the mold 21a was located.

[0035] (Joining Process) Next, the first insert component and the foamed resin intermediate are joined. Figure 11 is an explanatory diagram showing the joining process. As shown in Figure 11, a joining material 7 such as a resin adhesive is sealed into the gap 9 formed between the side surface of the main body 11 of the first insert component 10a and the foamed resin intermediate 33, and cured to join the first insert component 10a and the foamed resin intermediate 33. For example, an epoxy-based thermoplastic adhesive is applied to the gap 9 formed between the side surface of the main body 11 of the first insert component 10a and the foamed resin intermediate 33, and cooled to join the first insert component 10a and the foamed resin intermediate 33. However, the joining material 7 may be an adhesive other than the above, such as a thermosetting resin adhesive.

[0036] Although not shown in the diagram, the second insert component 10b and the foamed resin intermediate 33 are joined in a similar manner. This forms a core material (foamed resin molded product) 3 having the first insert component 10a and the second insert component 10b joined with high bonding strength.

[0037] (Fiber-reinforced resin lamination process) Next, a fiber-reinforced resin layer is laminated on the outer circumference of the core material. Figure 12 is an explanatory diagram showing the fiber-reinforced resin lamination process. As shown in Figure 12, a fiber-reinforced resin layer 5 is formed on the outer circumference of the core material 3, and an opening is made at the position where the first insert component 10a is exposed, exposing the surface of the first insert component 10a, which is provided with screw holes (not shown), to the outside. The method of forming the fiber-reinforced resin layer 5 and the method of providing an opening in the fiber-reinforced resin layer 5 are not particularly limited, and any method may be adopted.

[0038] As described above, the method for manufacturing a foamed resin molded product according to the first embodiment includes a preparation step of arranging the first insert part 10a and the second insert part 10b in the support parts 25a and 25b provided in the cavity space 23 of the molds 21a and 21b; a molding step of filling the cavity space 23 with foamed resin granules 31 and then curing it to form a foamed resin intermediate 33 in which parts of the first insert part 10a and the second insert part 10b are joined; a demolding step of removing the foamed resin intermediate 33 from the molds 21a and 21b; and a joining step of injecting a joining material 7 into the gap 9 in the foamed resin intermediate 33 where the support parts 25a and 25b were located, and curing the joining material 7 to join the first insert part 10a and the second insert part 10b to the foamed resin intermediate 33.

[0039] Therefore, in order to prevent a decrease in fluidity when filling the cavity space 23 of the molds 21a and 21b with foamed resin granules 31, the shapes of the first insert part 10a and the second insert part 10b, and the support parts 25a and 25b that support the first insert part 10a and the second insert part 10b, can be simplified, while firmly bonding the first insert part 10a and the second insert part 10b to the core material 3 made of foamed resin.

[0040] Furthermore, according to the manufacturing method of foamed resin molded products of this embodiment, by providing support portions 25a and 25b on the mold 21a, a gap 9 for injecting the bonding material 7 can be easily formed in the foamed resin intermediate 33 without any additional processing.

[0041] Also, in the method for manufacturing a foamed resin molded product according to the present embodiment, after the demolding step and before the joining step, a surface treatment step may be provided to roughen the surfaces of the first insert part 10a and the second insert part 10b facing the gap 9. The surface treatment step may be any treatment that increases the surface roughness. The surface treatment step may be, for example, a powder blast treatment that projects fine powder 37 onto the surface of the first insert part 10a to increase the surface roughness, as shown in FIG. 13, or a polishing treatment that polishes the surfaces of the first insert part 10a and the second insert part 10b with an end mill to increase the surface roughness.

[0042] By providing a surface treatment step before the joining step, the joining strength between the joining material 7 and the first insert part 10a and the second insert part 10b can be increased, and thus the joining strength between the first insert part 10a and the second insert part 10b and the core material 3 can be increased.

[0043] Also, in the method for manufacturing a foamed resin molded product according to the present embodiment, the joining material 7 may contain short fibers with a short fiber length. For example, the joining material 7 may contain carbon fibers or glass fibers with a short fiber length. By including short fibers with a short fiber length in the joining material 7, the short fibers can penetrate into the long fibers of the fiber-reinforced resin layer 5, thereby increasing the joining strength.

[0044] <<2. Second Embodiment>> Next, an example of a method for manufacturing a fiber-reinforced resin composite material including a method for manufacturing a foamed resin molded product according to the second embodiment of the present disclosure will be described. The foamed resin molded product obtained by the method for manufacturing a foamed resin molded product according to the second embodiment has the same appearance configuration as the foamed resin molded product obtained by the method for manufacturing a foamed resin molded product according to the first embodiment.

[0045] FIG. 14 is an explanatory diagram showing the steps of the method for manufacturing a foamed resin molded product according to the present embodiment. FIGS. 15 to 19 are explanatory diagrams showing each step of the method for manufacturing a foamed resin molded product. FIGS. 15 to 19 show a cross-section of the portion of the front pillar 1 shown in FIG. 1 where the first insert part 10a is provided.

[0046] (Preparation Step) First, as a preparation step, an insert part in which a thermoplastic resin having a higher melting point than the granular foamable resin is disposed on at least a part of the surface is placed in the cavity space of the mold. As shown in FIG. 6, a set of molds 21a and 21b that form the cavity space 23 by combination is prepared. FIG. 15 is an explanatory view showing the preparation step. As shown in FIG. 15, in the present embodiment, instead of the support parts (25a, 25b) of the mold 21a used in the manufacturing method according to the first embodiment, an engaging part 27 that engages with the two screw holes 15 of the first insert part 10a is provided on the molding surface of the mold 21a. The engaging part 27 is a part inserted and fixed in the mold 21a, and a part thereof is exposed on the outer surface of the mold 21a.

[0047] Further, on the side surface of the main body part 11 of the first insert part 10a having the main body part 11 and the flange part 13 used in the first embodiment, a thermoplastic resin 35 having a higher melting point than the granular foamable resin is disposed in advance. For example, the melting point of "Rohacell (registered trademark)", which is an example of the granular foamable resin, is about (180 to 230°C), and the thermoplastic resin 35 having a melting point higher than this melting point is laminated or attached to the side surface of the main body part 11 of the first insert part 10a. The thermoplastic resin 35 is not particularly limited as long as it has a higher melting point than the granular foamable resin, and any resin can be used.

[0048] Then, by engaging the screw hole 15 of the first insert part 10a in which the thermoplastic resin 35 is disposed on the side surface of the main body part 11 of the first insert part 10a with the engaging part 27 of the mold 21a, the first insert part 10a is placed in the cavity space. The height of the part of the engaging part 27 that protrudes from the molding surface of the mold 21a is made lower than the depth of the screw hole 15 of the first insert part 10a. Although not shown, similarly, the second insert part 10b is engaged with the engaging part of the mold 21a, and the second insert part 10b is placed in the cavity space.

[0049] (Molding Process) Next, foaming resin granules are filled into the cavity space of the mold, and the foaming resin is cured to form a foaming resin intermediate. Figures 16 and 17 are explanatory diagrams showing the molding process. As shown in Figure 16, a set of molds 21a and 21b are combined to form a cavity space 23. Also, as shown in Figure 17, foaming resin granules 31 are poured in from the injection port 26 to fill the cavity space 23 with foaming resin granules 31. The foaming resin granules 31 flow through the cavity space 23 while foaming and filling it.

[0050] After filling the cavity space 23 with foamed resin granules 31, the molds 21a and 21b are cooled to cure the foamed resin and form a foamed resin intermediate 33. This forms a foamed resin intermediate 33 to which the flange portion 13 of the first insert part 10a is mechanically bonded. Although not shown, the flange portion of the second insert part 10b is similarly mechanically bonded to the foamed resin intermediate 33.

[0051] (Joining Process) Next, the first insert component is heated to melt the thermoplastic resin and the foamed resin intermediate in contact with the thermoplastic resin. Then, the melted thermoplastic resin and the foamed resin intermediate in contact with the thermoplastic resin are cured to join the first insert component and the foamed resin intermediate. Figure 18 is an explanatory diagram showing the joining process. As shown in Figure 18, for example, the engaging portion 27 is heated from outside the mold 21a using an arbitrary heating device 38. As a result, the first insert component 10a is heated via the engaging portion 27, and the thermoplastic resin 35 in contact with the first insert component 10a and the foamed resin intermediate 33 in contact with the thermoplastic resin melt. After that, the heating device 38 is stopped, and the melted thermoplastic resin 35 and the foamed resin intermediate 33 in contact with the thermoplastic resin are cured. As a result, the first insert component 10a and the foamed resin intermediate 33 are joined. Although not shown, the second insert component 10b and the foamed resin intermediate 33 are joined in the same manner.

[0052] (Demolding Process) Next, the foamed resin intermediate is removed from the mold. Figure 19 is an explanatory diagram showing the demolding process. As shown in Figure 19, the molds 21a and 21b are separated, and the foamed resin intermediate 33 is removed from the molds 21a and 21b. This forms a core material (foamed resin molded product) 3 having a first insert part 10a and a second insert part 10b joined with high bonding strength.

[0053] (Fiber-reinforced resin lamination process) Next, a fiber-reinforced resin layer is laminated around the outer circumference of the core material in the same manner as in the first embodiment (see Figure 12).

[0054] As described above, the method for manufacturing a foamed resin molded product according to the second embodiment includes a preparation step of placing a first insert part 10a and a second insert part 10b, each having a thermoplastic resin 35 with a higher melting point than the foamed resin granules on at least a portion of its surface, in the engaging portion 27 provided in the cavity space 23 of the molds 21a and 21b; and filling the cavity space 23 with foamed resin granules 31 and then curing it to form a foamed resin molded product in which a portion of the first insert part 10a and the second insert part 10b are joined together. The process includes a molding step of forming a resin intermediate 33; a joining step of heating the first insert part 10a and the second insert part 10b to melt the thermoplastic resin 35 and the foamed resin intermediate 33 in contact with the thermoplastic resin 35, then curing the molten thermoplastic resin 35 and the foamed resin intermediate 33 in contact with the thermoplastic resin 35 to join the first insert part 10a and the second insert part 10b with the foamed resin intermediate 33; and a demolding step of removing the foamed resin intermediate 33 from the molds 21a and 21b.

[0055] Therefore, in order to prevent a decrease in fluidity when filling the cavity space 23 of the molds 21a and 21b with foamed resin granules 31, the shapes of the first insert part 10a and the second insert part 10b can be simplified while firmly bonding the first insert part 10a and the second insert part 10b to the core material 3 made of foamed resin.

[0056] Furthermore, according to the manufacturing method of foamed resin molded products according to this embodiment, the first insert part 10a and the second insert part 10b can be easily heated from outside the molds 21a and 21b while fixing them to the mold 21a by utilizing the screw holes 15 provided in the first insert part 10a and the second insert part 10b.

[0057] Furthermore, in the method for manufacturing a foamed resin molded product according to this embodiment, the thermoplastic resin 35 may contain short fibers with a short fiber length. For example, the thermoplastic resin 35 may contain short carbon fibers or glass fibers with a short fiber length. By including short fibers with a short fiber length in the thermoplastic resin 35, the short fibers can penetrate the long fibers of the fiber-reinforced resin layer 5, thereby increasing the bonding strength.

[0058] <<3. Third Embodiment>> Next, an example of a method for manufacturing a fiber-reinforced resin composite material, including a method for manufacturing a foamed resin molded product according to the third embodiment of this disclosure, will be described. Note that the foamed resin molded product obtained by the method for manufacturing a foamed resin molded product according to the second embodiment has the same external appearance as the foamed resin molded product obtained by the method for manufacturing a foamed resin molded product according to the first embodiment.

[0059] Figure 20 shows the configuration of an insert part 50 used in the manufacturing method of a foamed resin molded product according to this embodiment. The insert part 50 has a main body 51, a flange 53, and a screw hole 55, similar to the insert part used in the first embodiment. The insert part 50 used in this embodiment also has an internal passage 59 having a filling port 59a and three outlets 59b, 59c, and 59d. The filling port 59a opens on the surface on the main body 51 side. The outlet 59c opens on the surface on the flange 53 side. The outlets 59b and 59d open on both sides of the main body 51. The filling port 59a and the three outlets 59b, 59c, and 59d are each connected by the internal passage 59. Because the insert part 50 has a simple shape with a flange 13 protruding from a rectangular main body 11, it does not hinder the fluidity of the foamed resin.

[0060] Figure 21 is an explanatory diagram showing the steps of the manufacturing method for a foamed resin molded product according to this embodiment. Figures 22 to 28 are explanatory diagrams showing each step of the manufacturing method for a foamed resin molded product. Figures 22 to 28 show cross-sections of the front pillar 1 shown in Figure 1 where the first insert part 10a is provided.

[0061] (Preparation Step) First, as a preparation step, the insert component is held in the cavity space of the mold. As shown in Figure 6, a set of molds 21a and 21b are prepared, which, when combined, form a cavity space 23. In this embodiment, similar to the preparation step of the manufacturing method according to the second embodiment, the molding surface of the mold 21a is provided with locking parts (not shown) that engage with the two screw holes 55 of the insert component 50. Then, the insert component 50 is placed in the cavity space by engaging the screw holes 55 of the insert component 50 with the engaging parts of the mold 21a.

[0062] Figures 22 and 23 are explanatory diagrams showing the preparation process. As shown in Figures 22 and 23, in this embodiment, the mold 21a is provided with an opening 29 that aligns with the position of the filling port 59a of the insert component 50. Therefore, with the insert component 50 held in the mold 21a, the opening 29 of the mold 21a and the filling port 59a of the insert component 50 are in communication. The opening 29 of the mold 21a and the filling port 59a of the insert component 50 become injection ports for the foaming resin granules. Note that the molds 21a and 21b may also be provided with injection ports other than the opening 29.

[0063] (Molding and Joining Processes) Next, a molding process is carried out in which foaming resin granules are filled into the cavity space through the internal passage from the opening of the mold and the filling port of the insert part, and the foaming resin is cured to form a foaming resin intermediate, and a joining process is carried out in which the insert part is mechanically joined to the foaming resin intermediate. Figures 24 and 25 are explanatory diagrams showing the molding and joining processes. As shown in Figure 24, foaming resin granules 31 are filled into the cavity space 23 through the internal passage 59 from the opening 29 of the mold 21a and the filling port 59a of the insert part 50. The foaming resin granules 31 to be filled are injected into the cavity space 23 from the outlets 59b to 59d through the internal passage 59 from the filling port 59a. The foaming resin granules 31 flow through the cavity space 23 while foaming and are filled.

[0064] Figure 25 is an explanatory diagram showing how the molding process and the joining process are carried out simultaneously. As shown in Figure 25, the filled foamed resin is cured to form the foamed resin intermediate 33, and the insert part 50 is mechanically bonded to the foamed resin intermediate 33. In other words, by curing the filled foamed resin, the foamed resin filled in the internal passage 59 of the insert part 50 also hardens, and the insert part 50 becomes embedded in the foamed resin intermediate 33.

[0065] (Demolding process) Next, the foamed resin intermediate is removed from the mold. Figure 26 is an explanatory diagram showing the demolding process. As shown in Figure 26, the molds 21a and 21b are separated, and the foamed resin intermediate 33 is removed from the molds 21a and 21b. This forms a core material (foamed resin molded product) 3 having insert parts 50 joined with high bonding strength.

[0066] (Fiber-reinforced resin lamination process) Next, a fiber-reinforced resin layer is laminated on the outer circumference of the core material in the same manner as in the first embodiment. Figures 27 and 28 are explanatory diagrams showing the fiber-reinforced resin lamination process. Figure 27 is a cross-sectional view of the section where the internal passage 59 of the insert component 50 is located, and Figure 28 is a cross-sectional view of the section where the screw hole 55 of the insert component 50 is located. As shown in Figures 27 and 28, a fiber-reinforced resin layer 5 is formed on the outer circumference of the core material 3, and an opening is made where the insert component 50 is exposed, exposing the surface of the insert component 50 with the screw hole 55 to the outside.

[0067] As described above, the method for manufacturing a foamed resin molded product according to the third embodiment includes a preparation step of arranging an insert part 50 in an engaging portion provided in the cavity space 23 of the molds 21a and 21b, the insert part 50 having an internal passage 59 having a filling port 59a that opens to the outside of the mold 21a and at least one outlet 59b to 59d that opens into the cavity space 23; a molding and joining step of filling the cavity space 23 with foamed resin granules 31 from the filling port 59a through the internal passage 59, curing the foamed resin to form a foamed resin intermediate 33, and mechanically bonding the insert part 50 to the foamed resin intermediate 33; and a demolding step of removing the foamed resin intermediate 33 from the molds 21a and 21b.

[0068] Therefore, in order to prevent a decrease in fluidity when filling the cavity space 23 of the molds 21a and 21b with foamed resin granules 31, the shape of the insert part 50 can be simplified while mechanically bonding the insert part 50 firmly to the core material 3 made of foamed resin.

[0069] Furthermore, according to the manufacturing method of the foamed resin molded product of this embodiment, by pouring foamed resin granules 31 into the cavity space 23 of the molds 21a and 21b and curing the foamed resin, the insert part 50 can be bonded to the foamed resin intermediate 33 without requiring any additional steps.

[0070] Furthermore, according to the manufacturing method of foamed resin molded products according to this embodiment, the internal passage 59 of the insert part 50 serves as an injection port when pouring foamed resin granules 31 into the cavity space 23 of the molds 21a and 21b. As a result, the foamed resin granules 31 are filled into the insert part 50 in the final stage of injection of the foamed resin granules 31, making it easier to design the density and surface roughness of the foamed resin and increasing the bonding strength.

[0071] While preferred embodiments of the technology of this disclosure have been described in detail above with reference to the attached drawings, the technology of this disclosure is not limited to these examples. It is clear that a person with ordinary skill in the art to which this disclosure belongs can conceive of various modifications or alterations within the scope of the technical idea described in the claims, and these are also understood to be within the technical scope of this disclosure. Furthermore, embodiments and modifications combining the above embodiments and their variations also naturally fall within the technical scope of this disclosure.

[0072] For example, in the above embodiment, an example was described in which a foamed resin molded product having an insert component is used as the core material for a front pillar. However, a foamed resin molded product having an insert component is not limited to being used as the core material for a front pillar. For example, the foamed resin molded product may be used as the core material for other vehicle body structural components such as pillars, side rails, toe boards, floor panels, or cross members, or as the core material for any other fiber-reinforced resin composite material, or for any other purpose.

[0073] 1: Front pillar 3: Core material (foamed resin molded product) 5: Fiber-reinforced resin layer 7: Bonding material 9: Gap 10a: First insert part 10b: Second insert part 21a: Mold 21b: Mold 23: Cavity space 31: Foamed resin granules 33: Foamed resin intermediate 35: Thermoplastic resin 50: Insert part 59: Internal passage

Claims

1. A method for manufacturing a foamed resin molded product, comprising: a preparation step of arranging an insert component in the cavity space of a mold; a molding step of filling the cavity space with foamed resin granules and curing the foamed resin to form a foamed resin intermediate; a demolding step of removing the foamed resin intermediate from the mold; and a joining step of joining the insert component and the foamed resin intermediate.

2. A method for manufacturing a foamed resin molded product according to claim 1, comprising:

1. In the preparation step, the insert component is placed in a support provided in the cavity space; 2. In the molding step, the foamed resin granules are filled into the cavity space and then cured to form a foamed resin intermediate with a portion of the insert component joined to it; 3. In the demolding step, the foamed resin intermediate is removed from the mold; 4. In the joining step, a joining material is injected into the gap in the foamed resin intermediate where the support was located, and the joining material is cured to join the insert component and the foamed resin intermediate.

3. The method for manufacturing a foamed resin molded product according to claim 2, further comprising a surface treatment step of roughening the surface roughness of the insert part facing the gap before the joining step.

4. The method for manufacturing a foamed resin molded product according to claim 1, wherein in the preparation step, an insert component having a thermoplastic resin having a higher melting point than the foamed resin granules on at least a portion of its surface is placed in the cavity space; then, in the molding step, the foamed resin granules are filled into the cavity space and the foamed resin is cured to form the foamed resin intermediate; then, in the joining step, the insert component is heated to melt the thermoplastic resin and the foamed resin intermediate in contact with the thermoplastic resin, and then the molten thermoplastic resin and the foamed resin intermediate in contact with the thermoplastic resin are cured to join the insert component and the foamed resin intermediate; and then, in the demolding step, the foamed resin intermediate is removed from the mold.

5. A method for manufacturing a foamed resin molded product according to claim 1, wherein in the preparation step, the insert component having an internal passage having a filling port opening to the outside of the mold and at least one outlet opening into the cavity space is held in the cavity space; in the molding step, the foamed resin granules are filled into the cavity space from the filling port through the internal passage, the foamed resin is cured to form the foamed resin intermediate, and the bonding step of mechanically bonding the insert component to the foamed resin intermediate is performed simultaneously; and in the demolding step, the foamed resin intermediate is removed from the mold.

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