Foamed structure and resin panel

A resin panel according to an embodiment includes a core material, a reinforcing material, a skin material covering the core material and the reinforcing material, and a fastened member. A reinforcing material has a first plate provided on a front surface of the core material, a second plate provided on a back surface of the core material, and a connecting plate connecting the first plate and the second plate. The fastened member is attached to the skin material by a fastening member penetrating the skin material and the first plate or the second plate of the reinforcing material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. national phase application under 35 U.S.C. § 371 of International Patent Application No. PCT/JP2017/005414, filed Feb. 15, 2017, and claims benefit of priority to Japanese Patent Application No. 2016-025826, filed Feb. 15, 2016, Japanese Patent Application No. 2016-034016, filed Feb. 25, 2016 and Japanese Patent Application No. 2016-190646, filed Sep. 29, 2016. The entire contents of these applications are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The present invention relates to a foamed structure and a resin panel.

BACKGROUND

Conventionally, a resin panel has been widely used for an automobile, a building material, sports and leisure, and the like. The resin panel is a laminate including a foamed structure including one or a plurality of foams made of a foamed resin covered with a skin material sheet. This resin panel is also called a sandwich panel.

Conventionally, a member (fastened member) such as a hinge may be attached to a skin material of the resin panel using a fastening means such as a rivet. For example, a parcel board attached with a hinge part as a fastened member is described in JP-A-2000-062537. The hinge part of this parcel board is a portion which contains two upper and lower sewn nonwoven fabrics and can be bent.

The foamed structure in which a metallic reinforcing material is inserted is known as a conventional resin panel (for example, JP-A-2014-128938 and JP-A-2015-164763). For example, JP-A-2014-128938 describes the foamed structure in which a first core material and a second core material, which are obtained by cutting a foam provided with a linear groove portion at the groove portion, are respectively fitted into a reinforcing material from one side and the other side of the reinforcing material.

SUMMARY

Conventionally, a member (fastened member) such as a hinge is attached to the resin panel using the fastening means such as the rivet. In this case, the fastened member is fastened by utilizing a hole opened in a resin sheet on the front side or the back side. In that case, a thickness of the resin sheet must be increased in order to support a load applied to the fastened member. This has been a factor inhibiting a weight reduction.

Therefore, in one aspect of the present disclosure, it is an object to make the resin panel lighter in weight than the conventional one, and to make it possible to firmly attach the fastened member to the panel.

In the conventional foamed structure, when the core material is constituted by the first core material and the second core material which are divided with the reinforcing material as a boundary, a dimensional error of the core material in the foamed structure may occur. This error is due to an assembling error (a positional deviation) when the first core material and the second core material are assembled to the reinforcing material. When the dimensional error of the core material in the foamed structure is large, an adverse effect such as poor appearance of the resin panel occurs due to the dimensional error of the core material.

Therefore, in another aspect of the present disclosure, it is an object to improve dimensional accuracy of the foam in the foamed structure having the reinforcing material attached to the foam.

Conventionally, when a skin material is molded on a surface of the foamed structure including the reinforcing material interposed between two foams, the reinforcing material may relatively move with respect to the foam in a molding step. Then, defect that the skin material cannot be molded, or poor appearance of the skin material after molding occurs.

From such a viewpoint, in still another aspect of the present disclosure, it is an object to reliably inhibit relative movement of the reinforcing material with respect to the foam in the foamed structure including the reinforcing material interposed between two foams.

SUMMARY

An aspect of the present disclosure is a resin panel including: a core material; a reinforcing material having a first plate provided on a front surface of the core material, a second plate provided on a back surface of the core material, and a connecting plate connecting the first plate and the second plate; a skin material covering the core material and the reinforcing material; and a fastened member which is attached to the skin material by a fastening member penetrating the skin material and the first plate or the second plate of the reinforcing material.

Another aspect of the present disclosure is a foamed structure including: a reinforcing material including a first plate and a second plate which extend linearly while facing each other and a connecting plate which connects the first plate and the second plate; and a foam having a linear accommodating portion for accommodating the reinforcing material, and a first foamed portion and a second foamed portion formed with the accommodating portion interposed therebetween. The accommodating portion has: a connecting portion for connecting the first foamed portion and the second foamed portion; and a projecting portion projecting from at least one foamed portion among the first foamed portion and the second foamed portion toward the other foamed portion, and at least a part of the projecting portion is interposed between the first plate and the second plate of the reinforcing material.

Still another aspect of the present disclosure includes a reinforcing material having a pair of elongated plate-shaped portions facing each other with a predetermined amount of gap interposed therebetween, and a foam. The foam is formed on a front surface or a back surface and includes an accommodating portion in which the reinforcing material is disposed, and a fitting portion projecting from at least one end of both ends of the reinforcing material into the gap of the reinforcing material and fitted with the reinforcing material. A thickness of the fitting portion in a direction in which the pair of plate-shaped portions is facing each other increases from a tip end of a portion of the reinforcing material projecting into the gap toward the one end of the reinforcing material.

According to one aspect of the present disclosure, it is possible to make the resin panel lighter than the conventional one and to firmly attach the fastened member to the panel.

According to another aspect of the present disclosure, it is possible to improve the dimensional accuracy of the foam when the reinforcing material is attached to the foam in the foamed structure.

According to still another aspect of the present disclosure, in a foamed structure in which a reinforcing material is interposed between two foams, it is possible to reliably inhibit relative movement of the reinforcing material with respect to the foam.

DETAILED DESCRIPTION

(1) First Embodiment

A resin board which is a first embodiment of a resin panel of the present invention will be described below.

FIG. 1is a perspective view of a resin container100including a resin board1of the first embodiment. As shown inFIG. 1, the resin container100includes a container body10and the resin board1serving as a lid of the container body10. The resin board1has hinge members5L and5R. The resin board1and the container body10are connected by the hinge members5L and5R so that a storage space10aof the container body10can be opened and closed by the resin board1. That is, the resin board1is rotatable around the hinge members5L and5R with respect to the container body10. The hinge members5L and5R are connected to a hinge attaching surface12of the container body10by rivets. The hinge members5L and5R of the present embodiment are examples of members to be fastened.

(1-1) Structure of Resin Board

Next, a structure of the resin board1of the present embodiment will be described with reference toFIGS. 2 to 5.

FIG. 2is a plan view of the resin board1of the first embodiment.

FIG. 3is an enlarged cross-sectional view taken along a line A-A ofFIG. 2.

FIG. 4is a view for explaining an example of attaching a reinforcing material3to a core material23in the resin board1of the first embodiment.

FIG. 5is a plan view showing a part of the resin board1of the embodiment to which the reinforcing material3is attached.

As shown inFIG. 1andFIG. 2, the resin board1has a substantially rectangular parallelepiped shape and has a resin laminate2and the hinge members5L and5R (hereinafter, individually or collectively also referred to as “hinge member5”). As will be described below, the reinforcing material3is incorporated in the resin laminate2. The hinge members5L and5R are fastened together with the reinforcing material3in the vicinity of an outer edge of the resin laminate2by rivets R (at four places for each hinge member in an example shown inFIG. 2).

Referring toFIG. 3, the resin laminate2has a sandwich structure including the core material23sandwiched by a first resin sheet21and a second resin sheet22which are resin sheets of a thermoplastic resin respectively constituting a front surface and a back surface thereof. The first resin sheet21and the second resin sheet22cover the core material23and the reinforcing material3and constitute the skin material of the resin board1.

Resin materials of the first resin sheet21and the second resin sheet22are not limited. The resin material may be a foamed resin or a non-foamed resin. However, in order to ensure stiffness of the resin board1, these resin sheets are preferably formed of the non-foamed resin. For example, in consideration of moldability, in skin material sheets SA and SB, polystyrene (PS) and styrene ethylene butylene styrene block copolymer resin (SEBS) may be mixed in polypropylene (PP) as a main material.

A volume ratio of the core material23to the resin board1is large. Therefore, the core material23is preferably made of the foamed resin foamed by using a foaming agent for weight reduction. For example, the resin material of the core material23includes a material containing the foaming agent added to any one of polyolefin such as polypropylene or polyethylene and an acrylic derivative such as polyamide, polystyrene, or polyvinyl chloride, or a mixture of two or more thereof. The core material23is molded, for example, by a bead method in-mold foam molding method.

As the foaming agent, any of a physical foaming agent, a chemical foaming agent, and a mixture thereof may be used. As the physical foaming agent, an inorganic physical foaming agent such as air, carbonic acid gas, nitrogen gas, water, or the like, and an organic physical foaming agent such as butane, pentane, hexane, dichloromethane, or dichloroethane, and further a supercritical fluid thereof can be used.

An expansion ratio of the core material23is in a range of 1.5 to 15 times. A typical expansion ratio is 4 times. The expansion ratio is preferably 2.5 to 10 times. Note that the expansion ratio is a value obtained by dividing a density of a mixed resin before foaming by an apparent density of the foamed resin after foaming.

The first resin sheet21, the second resin sheet22, and the core material23may be molded using the resin material mixed with a glass filler in order to increase stiffness and strength.

For example, the glass filler includes glass fiber cloth such as glass fiber, glass cloth or glass nonwoven fabric, glass bead, glass flake, glass powder, milled glass and the like. Examples of glass types include E glass, C glass, A glass, S glass, D glass, NE glass, T glass, quartz, low dielectric constant glass, and high dielectric constant glass.

Not limited to the glass filler, inorganic fillers such as talc, calcium carbonate, Wollastonite, magnesium-based material, carbon fiber, or the like may be mixed in order to increase the stiffness.

As shown inFIG. 3, in the resin board1of the present embodiment, the reinforcing material3is attached to the core material23. The reinforcing material3includes a first plate31provided on the front surface of the core material23, a second plate32provided on the back surface of the core material23, and a connecting plate33connecting the first plate31and the second plate32. The reinforcing material3has a U-shaped cross-section. The first plate31of the reinforcing material3has a front side plate surface311in contact with the first resin sheet21and a back side plate surface312in contact with the core material23. The second plate32of the reinforcing material3has a front side plate surface321in contact with the core material23and a back side plate surface322in contact with the second resin sheet22. The connecting plate33has an inner plate surface331in contact with a side wall surface of the core material23and an outer plate surface332forming an end surface of the reinforcing material3.

A material of the reinforcing material3is not particularly limited. However, the material of the reinforcing material3is preferably made of a metal such as aluminum or a hard plastic in order to ensure strength of the resin board1. The reinforcing material3is molded by, for example, extrusion molding.

As shown inFIG. 3, attaching openings RH (openings through which the rivets R pass) are provided in the hinge members5L and5R. The rivet R (an example of a fastening member) is fastened to the resin laminate2through the opening RH. That is, in the resin board1of the present embodiment, the hinge members5L and5R are attached to a front side of the resin board1by the rivet R penetrating the first resin sheet21which is the skin material and the first plate31of the reinforcing material3. When fastening the rivet R, holes are drilled for the rivet R to penetrate the first resin sheet21and the reinforcing material3at a fastening position on the first resin sheet21. The rivet R is inserted into the holes.

In the reinforcing material3, a plate thickness t1of the first plate31which the rivet R penetrates is preferably less than a plate thickness t2of the connecting plate33. This is due to the following reasons. Firstly, by reducing the plate thickness t1of the first plate31, it is possible to easily perform an operation of drilling the hole for fastening the rivet R, and to reduce the weight. Secondly, the connecting plate33is a portion to which a load is greatly applied when the hinge member5operates. Therefore, it is preferable to increase the plate thickness t2of the connecting plate33in order to increase strength of the connecting plate33.

In the resin board1of the present embodiment, even when the plate thickness t1of the first plate31and further a thickness of the second plate32are made relatively small, it is possible to ensure necessary stiffness and strength. This is due to the following reasons. Firstly, as will be described below, when manufacturing the resin board1, the core material23and the reinforcing material3are welded to molten resin to be the first resin sheet21and the second resin sheet22. Therefore, the first resin sheet21, the core material23, and the reinforcing material3have an integral structure in the reinforcing material3and its surroundings. Secondly, as shown inFIG. 3, the reinforcing material3has a form of sandwiching the core material23. Therefore, the resin board1is configured to favorably obtain the necessary stiffness and strength in any direction of opening and closing of the hinge member5.

The necessary stiffness and strength can be ensured by the reinforcing material3. Therefore, the first resin sheet21and the second resin sheet22can be thinned.

As shown inFIG. 4, in the resin board1of the present embodiment, a recess231aand a recess232aare respectively formed on an outer edge of a front surface231and an outer edge of a back surface232of the core material23. As shown in order of Steps S10and S11inFIG. 4, the reinforcing material3is attached to the core material23by inserting the reinforcing material3having the U-shaped cross-section from the outside into the recess231aand the recess232a. In a state where the reinforcing material3is attached to the core material23, the first plate31of the reinforcing material3is placed in the recess231aof the core material23, and the second plate32of the reinforcing material3is placed in the recess232aof the core material23. The inner plate surface331of the connecting plate33of the reinforcing material3is in contact with a side wall surface235bof the core material23. In the drawing shown in Step S11, positions (two positions) of the openings RH for fastening the rivets R are indicated by dotted lines.

In the state where the reinforcing material3is attached to the core material23, recessed amounts of the recesses231aand232aare preferably set so that the front surface231of the core material23and the front side plate surface311of the first plate31of the reinforcing material3are flush with each other, and the back surface232of the core material23and the back side plate surface322of the second plate32of the reinforcing material3are flush with each other. Thus, the front surface and the back surface of the resin board1are both flat. Therefore, an appearance of the resin board1is not impaired.

As shown inFIG. 4, a depth of the recess231awith reference to a side wall surface235aof the core material23is defined as L1, a width in an attachment direction of the recess231aof the reinforcing material3is defined as L2, and a width in the attachment direction of the first plate31of the reinforcing material3is defined as L3. Here, when the reinforcing material3is engaged with the recess231awithout any gap, L3=L2+t2(t2is the plate thickness of the connecting plate33of the reinforcing material3as shown inFIG. 3) is satisfied. In this case, the core material is preferably set so that L1>L3is satisfied. In other words, it is preferable to set the core material23so that L1>L2+t2is satisfied. That is, as shown inFIG. 5, in a state where the reinforcing material3is attached to the core material23, it is preferable that the outer plate surface332of the reinforcing material3is located inside a reference line EL defined by the side wall surface235a(that is, the outer edge of the core material23) of the core material23in a plan view.

Note that the reference line EL means an imaginary line defined by the outermost peripheral edge of the core material23. For example, as shown inFIG. 4, in the core material23of the present embodiment, the side wall surface235bof a portion where the recesses231aand232aare formed is located inside the side wall surface235aof a portion where the recesses231aand232aare not formed. The reference line EL is determined by the imaginary line of the side wall surface235awhich is the outermost peripheral edge of the core material23as viewed in a plan view.

It will be further described that L1>L3is preferable with reference toFIGS. 6Ato6C.

FIGS. 6A to 6Cshow three patterns regarding a relationship between the depth L1of the recess231aand the width L3in the attachment direction of the first plate31of the reinforcing material3with reference to the side wall surface235a.FIG. 6Ais an example of the present embodiment. This is the case of L1>L3as shown inFIG. 5.FIG. 6BandFIG. 6Care different from the example of the present embodiment. These figures are reference examples respectively showing a case of L1=L3and a case of L1<L3.

As will be described below, the core material23to which the reinforcing material3is attached is welded to a molten resin sheet when clamping split mold blocks. At this time, as shown inFIG. 6A, in the case where the first plate31and the second plate32of the reinforcing material3are disposed inside the reference line EL defined by the outer edge of the core material23when the core material23is viewed in a plan view (that is, in the case of L1>L3), when a longitudinal direction of the core material23is aligned with the vertical direction for welding with the molten resin sheet (that is, when it is arranged DOWN inFIG. 6Ais vertically downward), a side wall of the recess231aof the core material23supports the connecting plate33of the reinforcing material3. From this fact, it is difficult for the reinforcing material3to fall off from the core material23. Therefore, it is possible to reduce a possibility that the reinforcing material3falls off from the core material23and damages the mold.

As shown inFIG. 6A, when L1>L3, the outer plate surface332of the reinforcing material3is separated inward from the side wall surface235aof the core material23. Therefore, at the time of manufacturing the resin board1to be described below, even when the core material23is slightly displaced from a molten resin sheet P so that the inner plate surface331of the reinforcing material3slightly approaches a pinch-off part of the split mold block, there is a low possibility that the split mold blocks pinch the reinforcing material3when clamping the split mold blocks.

As shown inFIG. 6B, when L1=L3, the side wall of the recess231aof the core material23supports the connecting plate33of the reinforcing material3. This point is the same as in the case ofFIG. 6A. However, since the outer plate surface332of the reinforcing material3is not inside the reference line EL, a holding force of the reinforcing material3by the core material23is not sufficient as compared with that in the case ofFIG. 6A.

As shown inFIG. 6C, when L1<L3, the outer plate surface332of the connecting plate33of the reinforcing material3is outside the reference line EL. Therefore, the connecting plate33is not supported by the side wall of the recess231aof the core material23, and the holding force of the reinforcing material3by the core material23is small. Therefore, there is a possibility that the reinforcing material3falls off from the core material23and damages the mold.

As shown inFIGS. 6B and 6C, when L1<L3(in particular when L1<L3), the core material23is displaced from the molten resin sheet P at the time of manufacturing the resin board1to be described below, so that the inner plate surface331of the reinforcing material3approaches the pinch-off part of the split mold block. As a result, there is a possibility that the split mold blocks pinch the reinforcing material3when clamping the split mold blocks.

From the above, it is understood that it is preferable to set L1>L3.

(1-2) Method of Manufacturing Resin Board

Next, a method of manufacturing the resin board1of the present embodiment will be described with reference toFIGS. 7 to 11.FIGS. 7 to 11are views for respectively explaining the method of manufacturing the resin board of the first embodiment in order.

First, as shown inFIG. 7, the molten resin sheets P and P are extruded vertically downward from an extruding machine (not shown) and supplied between forming surfaces51aand52aof a pair of split mold blocks51and52. At this point, the pair of split mold blocks51and52is in an open position.

Each of the split mold blocks51and52is provided with a vacuum device (not shown) for sucking air in an enclosed space. The vacuum device includes a vacuum chamber and a communication path for communicating the vacuum chamber and the forming surface.

Next, as shown inFIG. 8, sliding portions511and521around the forming surfaces51aand52aare projected, so that end surfaces thereof are brought into contact with the molten resin sheets P and P. Thus, the enclosed space is formed between the molten resin sheets P and P and the forming surfaces51aand52aof the pair of split mold blocks51and52. Then, air in the enclosed space is sucked through a communication path provided between the vacuum chamber and the forming surfaces51aand52a. By this suction, the two molten resin sheets P and P are respectively pressed against the forming surfaces51aand52aof the pair of split mold blocks51and52, and are shaped (formed) so as to conform to a shape along the forming surfaces51aand52a, that is, a substantially outer shape of the resin board1, as shown inFIG. 9.

Next, as shown inFIG. 10, the core material23to which the reinforcing material3is attached is held by a manipulator90. Then, the core material23is positioned between the pair of split mold blocks51and52by using the manipulator90. Then, the core material23is welded so as to be pressed against the molten resin sheet P formed on any one of the forming surfaces51aand52a. At this time, as shown inFIG. 5, the outer plate surface332of the reinforcing material3is formed inside the reference line EL defined by the outer edge of the core material23. Therefore, there is a low possibility that the reinforcing material3falls off from the core material23.

After welding the core material23to any molten resin sheet P, the split mold blocks51and52are clamped as shown inFIG. 11. By this clamping, both the surfaces (the front surface231and the back surface232) of the core material23, and the first plate31and the second plate32of the reinforcing material3are welded to the molten resin sheets P and P. Thus, the core material23, the reinforcing material3, and the first resin sheet21and the second resin sheet22as the skin material are integrally joined around the reinforcing material3. Further, peripheral edge of the pair of molten resin sheets P and P is welded in the pinch-off part (not shown) of the pair of split mold blocks51and52. In this way, a parting line is formed.

Finally, the pair of split mold blocks51and52is again moved to the open position, and the molded resin board1is separated from the forming surfaces51aand52a. Then, burrs formed around the parting line are cut and removed by a cutter or the like. Thus, the resin board1is completed.

As described above, according to the resin board1of the present embodiment, the reinforcing material3placed on the front surface and the back surface of the core material23is covered with the skin material made of the first resin sheet21and the second resin sheet22, and the hinge members5L and5R are attached to the skin material by the rivets R penetrating the skin material and the first plate31of the reinforcing material3. Therefore, as compared with a conventional case where the hinge members are attached by the rivets by drilling only the skin material, in the resin board1of the present embodiment, the load of the hinge member can be supported by the reinforcing material3. Therefore, the skin material can be thinned. For example, while the thickness of the conventional resin sheet was 2 mm, the thickness of the resin sheet of the resin board1of the present embodiment could be 1 mm.

As described above, according to the resin board1of the present embodiment, the weight can be reduced as compared with the conventional one, and the fastened member such as a hinge can be firmly attached.

Since the reinforcing material3only needs to be provided only at an attaching position of the hinge member, a size occupied in the entire resin board1can be relatively small.

(2) Second Embodiment

The resin board which is a second embodiment of the resin panel of the present invention will be described with reference toFIG. 12andFIG. 13below.

FIG. 12is a view for explaining an example of attaching the reinforcing material to the core material in the resin board of the second embodiment.FIG. 13is a view for explaining an example of attaching the reinforcing material to the core material in the resin board according to a modification of the second embodiment. Each ofFIG. 12andFIG. 13corresponds toFIG. 4.

In the present embodiment, a mode of attaching the core material and the reinforcing material is different from that in the first embodiment. It should be noted that redundant descriptions of the same contents as those of the first embodiment will be omitted.

Referring first toFIG. 12, a reinforcing material3A of the present embodiment includes a first plate31A provided on a front surface231A of a core material23A, a second plate32A provided on a back surface232A of the core material23A, and a connecting plate33A connecting the first plate31A and the second plate32A. A cross-section of the reinforcing material3A has a substantially H-shape. The connecting plate33A connects central portions of the first plate31A and the second plate32A.

A recess231Aa and a recess232Aa are respectively formed on an outer edge of the front surface231A and an outer edge of the back surface232A of the core material23A. A cutout237A into which the connecting plate33A of the reinforcing material3A is inserted is formed between the recess231Aa and the recess232Aa. The cutout237A is formed by cutting with a cutter or the like after molding the core material23. As shown in order of Steps S20and S21inFIG. 12, the reinforcing material3A is attached to the core material23A by inserting the connecting plate33A of the reinforcing material3A having an H-shaped cross-section into the cutout237A. In a state where the reinforcing material3A is attached to the core material23A, the first plate31A of the reinforcing material3A is placed in the recess231Aa of the core material23A. Then, the second plate32A of the reinforcing material3A is placed in the recess232Aa of the core material23A.

In the reinforcing material3A shown inFIG. 12, four openings RH (shown by dashed lines) of the hinge members5L and5R for fastening the rivets R are formed in the first plate31A provided on the front side of the core material23A. It is not necessary to form holes for fastening the rivets R in the second plate32A provided on the back side of the core material23A. Therefore, the second plate32A is made smaller in width than the first plate31A in order to reduce the weight.

In a state where the reinforcing material3A is attached to the core material23A, recessed amounts of the recesses231Aa and232Aa are preferably set so that the front surface231A of the core material23A and the front side plate surface311A of the first plate31A of the reinforcing material3A are flush with each other, and the back surface232A of the core material23A and the back side plate surface322A of the second plate32A of the reinforcing material3A are flush with each other. Thus, the front surface and the back surface of the resin board are both flat. Therefore, the appearance of the resin board is not impaired.

As shown inFIG. 12, when the depth of the recess231Aa with reference to the side wall surface235A of the core material23A is L1and the width in the attaching direction of the first plate31A of the reinforcing material3A is L3, the depth and the width are preferably set to satisfy L1>L3. That is, as shown inFIG. 12, in a state where the reinforcing material3A is attached to the core material23A, an end surface3Ae of the reinforcing material3A is preferably located on the inner side of the side wall surface235A of the core material23A (outer edge of the core material23) in a plan view. In this way, the reinforcing material3A enters the inner side of the side wall surface235A of the core material23A. Therefore, it is possible to reduce a possibility that the reinforcing material3A falls off from the core material23A and damages the mold during manufacture.

The end surface3Ae of the reinforcing material3A is separated inward from the side wall surface235A of the core material23A. Therefore, even when the reinforcing material3A is slightly deviated to the outer side after it is attached to the core material23A, it is possible to reduce the possibility that the split mold blocks pinch the reinforcing material3A when clamping the split mold blocks during manufacturing the resin board of the present embodiment.

In the first embodiment, the inner plate surface331of the connecting plate33of the reinforcing material3is configured to contact the side wall surface235bof the core material23. Therefore, in order to dispose the reinforcing material3inner side than the side wall surface235a, it is necessary to dispose the side wall surface235b(the side wall surface of the portion of the recesses231aand232a) inner side than the side wall surface235ain the core material23. Therefore, in a portion of the inside of the skin material (a portion outside the reinforcing material3when the resin board1is viewed in a plan view; a portion between the outer plate surface332and the reference line EL inFIG. 5), a space in which the core material23is not present is formed. In contrast, in the present embodiment, the connecting plate33A of the reinforcing material3A is configured to be inserted into the cutout237A. Therefore, the side wall surface235A of the core material23A can be flush with these recesses regardless of whether the side wall surface is at a position of the recesses231Aa and232Aa. Therefore, even when the reinforcing material3A is disposed largely separated from and inside the side wall surface235a, it is possible to inhibit a local reduction in strength and stiffness of the resin panel due to formation of the space in which the core material is not present.

In the example shown inFIG. 12, in a state where the reinforcing material3A is attached to the core material23A, the openings RH for rivets are located on both sides across the connecting plate33A by two. However, a structure of the reinforcing material3A or a position of the cutout237A can be appropriately changed according to the fastening position of the rivet. For example, in an example shown inFIG. 13, in a state where the reinforcing material3A is attached to the core material23A, four rivet openings RH are located on one side of the connecting plate33A. In this case, the position of the connecting plate33A of the reinforcing material3A is set according to the position of the cutout237A.

The first and second embodiments of the present invention have been described in detail above. However, the resin panel of the present invention is not limited to the above embodiment. Of course, various improvements or modifications may be made without departing from the scope of the present invention.

FIGS. 14A and 14Brespectively show resin boards according to modifications of the embodiments.FIG. 14Ais a perspective view showing a part of the modification of the core material23of the resin board according to the first embodiment.FIG. 14Bis a perspective view showing a part of the modification of the core material23A of the resin board according to the second embodiment.

The core material23shown inFIG. 14Ais the modification in the case where the reinforcing material3having the U-shaped cross-section is attached as in the first embodiment described above. The core material23shown inFIG. 14Ais different from the core material23shown inFIG. 4in that a semicircular cutout C is formed at a position corresponding to the rivet opening RH in the recess231a. By forming the cutout C at the position corresponding to the rivet opening RH, the core material23is not drilled when the resin laminate is drilled after molding. Therefore, the resin board1is not contaminated with cutting scraps of the core material23.

The core material23A shown inFIG. 14Bis the modification in the case where the reinforcing material3A having the H-shaped cross-section is attached as in the second embodiment described above. In the core material23A shown inFIG. 14B, recesses D (four places) are formed at positions corresponding to the rivet openings RH in the recess231Aa. This point is different from the core material23A shown inFIG. 13. As in the case ofFIG. 14A, when the resin laminate is drilled after molding, a cut amount of the core material23by drilling is reduced due to the recesses D. Therefore, a possibility of contamination of the resin board1with the cutting scraps of the core material23is reduced. In place of the recess D, a through-hole may be provided in the core material23at a position corresponding to the opening RH. However, in that case, left and right molds contact each other during mold clamping. Therefore, it is not preferable to provide the through-hole in this way in promoting wear of the mold. Therefore, in the case ofFIG. 14B, the recess D is set in place of the through-hole.

In each of the embodiments described above, it is not always necessary that both the front surface and the back surface of the core material are respectively flush with the front side plate surface and the back side plate surface of the reinforcing material. Either one of the front side and the back side may be flush with each other depending on the intended use. For example, when only the front side is visible in a usual use state of the resin board, only the front side may be set to be flush with each other.

In the above-described embodiments, the case where the hinge members5L and5R are attached to the front side surface (the front surface of the first resin sheet21) of the resin laminate2has been described. However, the position of the hinge member is not limited thereto. The hinge members5L and5R may be attached to the back side (the back surface of the second resin sheet22) of the resin laminate2. The surface to which the hinge member is attached is appropriately determined according to the function of the resin board.

In the embodiment described above, the plate thickness of the first plate (31and31A) of the reinforcing material and the plate thickness of the second plate (32and32A) may be different. For example, the hole may not be formed in the second plate (32and32A) not fastened by the rivets. Therefore, the plate thickness can be determined independently of the plate thickness of the first plate (31and31A).

In the embodiment described above, a hinge is cited as an example of the fastened member. However, the fastened member is not limited to this example. The fastened member may be any member as long as it can be attached using the fastening means. For example, the fastened member may be a metallic or resin bracket used for various purposes.

(3-1) Resin Panel of Third Embodiment

FIG. 15is a perspective view of a resin panel600according to a third embodiment and an enlarged cut-away view of a part of the resin panel600.

As shown inFIG. 15, the outer shape of the resin panel600according to the present embodiment has a sandwich structure in which a foamed structure61is sandwiched by the skin material sheets SA and SB which are the resin sheets of the thermoplastic resin respectively constituting the front surface and the back surface. As shown inFIG. 15, in the resin panel600of the present embodiment, a pair of left and right raised portions125L and125R rising from a flat portion is formed.

In the resin panel600of the present embodiment, the resin material of the skin material sheets SA and SB is not limited. The resin material may be a foamed resin or a non-foamed resin. The skin material sheets SA and SB are preferably formed of the non-foamed resin in order to ensure the stiffness of the resin panel600. For example, in consideration of moldability, the resin material of the skin material sheets SA and SB may be the resin material obtained by mixing polystyrene (PS) and styrene ethylene butylene styrene block copolymer resin (SEBS) in polypropylene (PP) which is a main material.

For the purpose of increasing the stiffness and strength, the skin material sheets SA and SB and a foam62may be molded using the resin material mixed with the glass filler. As the glass filler, the same glass filler as the glass filler mentioned in the first embodiment may be used.

(3-2) Foamed Structure of The Present Embodiment

Next, the foamed structure61of the present embodiment will be described with reference toFIGS. 16 to 24.

FIG. 16Ais a perspective view of the foam62, which is a main part of the foamed structure61of the present embodiment, as seen from the front side.FIG. 16Bis a perspective view of the foam62as seen from the back side.FIG. 17is a perspective view of the reinforcing material63incorporated in the foam62.FIG. 18is a plan view of the foam62.FIG. 19is an enlarged view of a CL portion of the foam62shown inFIG. 18.FIG. 20is an arrow view as seen from an arrow A inFIG. 19.FIGS. 21 to 24are respectively cross-sectional views taken along lines B-B, C-C, D-D and E-E shown inFIG. 18.

Referring first toFIG. 16A, the foamed structure61has the foam62and a reinforcing material63locally attached to the foam62to ensure the stiffness and strength.

An overall shape of the foamed structure61is a shape obtained by removing the skin material sheets SA and SB from the resin panel600shown inFIG. 15. Therefore, the foamed structure61has the same shape as the whole shape of the resin panel600inFIG. 15. That is, the foamed structure61includes a flat portion623having a front surface62T and a back surface62B which are flat surfaces, and a pair of left and right raised portions25L and25R (hereinafter collectively or individually also referred to as “raised portion25”) rising from the front surface62T.

A thickness of the flat portion623of the foam62is appropriately determined in order to ensure a target thickness as the resin panel600and further a target stiffness and strength of the resin panel600. This thickness is not particularly limited.

The foam62is molded using, for example, the thermoplastic resin. The resin material is not limited. For example, the resin material includes a polyolefin such as polypropylene or polyethylene and an acrylic derivative such as polyamide, polystyrene or polyvinyl chloride, or a mixture of two or more kinds. The foam62occupies a large proportion of a volume of the foamed structure61. Therefore, the foam62is made of the foamed resin foamed by using a foaming agent for weight reduction. The expansion ratio of the foamed resin to be the foam62is, for example, in a range of 10 to 60 times, typically 30 times. Note that the expansion ratio is the value obtained by dividing the density of the mixed resin before foaming by the apparent density of the foamed resin after foaming.

In the foamed structure61, the reinforcing material63is attached to an accommodating portion620of the foam62.

As shown inFIG. 17, the reinforcing material63includes a first plate631and a second plate632which extend linearly while facing each other, and a connecting plate633connecting the first plate631and the second plate632. In an example shown inFIG. 17, the reinforcing material63has the H-shaped cross-section. In a state where the reinforcing material63is attached to the foam62, surfaces of the first plate631and the second plate632of the reinforcing material63opposite to surfaces to which the connecting plate633is connected respectively constitute part of the front surface62T and the back surface62B of the foam62.

Projections6311projecting toward the second plate632are provided at both ends of the first plate631. Projections6321projecting toward the first plate631are provided at both ends of the second plate632.

A material of the reinforcing material63is not particularly limited. However, the material of the reinforcing material63is preferably made of a metal such as aluminum or a hard plastic in order to ensure the strength of the resin panel600. The reinforcing material63is molded by, for example, extrusion molding.

As shown inFIGS. 16A and 18, the foam62includes the linear accommodating portion620for accommodating the reinforcing material63, and a first foamed portion621and a second foamed portion622formed sandwiching the accommodating portion620.

As shown inFIGS. 18 and 20, the accommodating portion620is formed through from a first opening200L provided on a first side surface24L on the left side of the foam62to a second opening200R provided on a second side surface24R on the right side of the foam62. The first opening200L and the second opening200R (hereinafter collectively or individually also referred to as “opening200”) are provided in order to insert the reinforcing material63from the first side surface24L or the second side surface24R into the accommodating portion620.

As shown inFIG. 16A, in an example of the present embodiment, the pair of raised portions25L and25R is formed near both ends of the linear accommodating portion620. In other words, the accommodating portion620and the raised portions25L and25R overlap each other in a plan view of the foam62. The raised portions25L and25R are respectively formed corresponding to the raised portions125L and125R of the resin panel600.

As shown inFIG. 18, the accommodating portion620for accommodating the reinforcing material63has a symmetrical structure.

Projecting portions201and202for restricting movement of the reinforcing material63in a direction perpendicular to the front surface62T and the back surface62B of the foam62are formed in a central portion of the accommodating portion620. A through-hole205penetrating the front surface62T and the back surface62B of the foam62is provided between the projecting portions201and202. A through-hole206L and a through-hole206R (hereinafter collectively or individually also referred to as “through-hole206”) are respectively provided on the first side surface24L and the second side surface24R at both ends in a longitudinal direction of the projecting portions201and202(that is, adjacent to one end and the other end of the projecting portions201and202). Connecting portions203L and203R (hereinafter collectively or individually also referred to as “connecting portion203”) and projections204L and204R (hereinafter collectively or individually also referred to as “projection204”) are formed near the both ends of the accommodating portion620.

As shown inFIG. 20andFIG. 23, in a portion where the first foamed portion621and the second foamed portion622are not connected (that is, in a portion where the through-holes206L,205and206R are provided in the longitudinal direction of the accommodating portion620inFIG. 18), the projecting portion201projects from the first foamed portion621toward the second foamed portion622and the projecting portion202projects from the second foamed portion622toward the first foamed portion621. The projecting portion201and the projecting portion202are facing each other across the through-hole205.

As shown inFIG. 23, when the reinforcing material63is inserted into the accommodating portion620, the connecting plate633of the reinforcing material63is disposed in the through-hole205.

As shown inFIG. 23, a thickness of the projecting portions201and202of the accommodating portion620is less than that of the first foamed portion621and the second foamed portion622. Thus, a groove g1and a groove g2are respectively formed on the front surface62T side and the back surface62B side with the through-hole205therebetween. The groove g1on the front surface62T side and the groove g2on the back surface62B side are respectively grooves in which the first plate631and the second plate632of the reinforcing material63are arranged. Preferably, a width of the groove g1on the front surface62T side and a width of the groove g2on the back surface62B side are respectively equal to or slightly more than that of the first plate631and the second plate632of the reinforcing material63. Thus, when the reinforcing material63is attached to the foam62, the movement in the width direction of the reinforcing material63is restricted.

The depth of the groove g1on the front surface62T side is preferably equal to the thickness including the projection6311of the first plate631of the reinforcing material63. The depth of the groove g2on the back surface62B side is preferably equal to the thickness including the projection6312of the second plate632of the reinforcing material63. Thus, when the reinforcing material63is accommodated in the accommodating portion620, the first foamed portion621, the accommodating portion620, and the second foamed portion622are flush with each other on the front surface62T side and the back surface62B side. Therefore, the appearance is good when the resin panel600is completed.

As shown inFIG. 23, in a state where the reinforcing material63is accommodated in the accommodating portion620, the projecting portion201and the projecting portion202is interposed between the first plate631and the second plate632of the reinforcing material63in a thickness direction of the foam62. Therefore, after the reinforcing material63is attached to the foam62, the movement of the reinforcing material63in the direction perpendicular to the front surface62T and the back surface62B of the foam62is restricted by the projecting portions201and202. Therefore, the reinforcing material63does not fall off in the direction.

In a state where the reinforcing material63is accommodated in the accommodating portion620, a tip end of the projection6311of the first plate631and a tip end of the projection6312of the second plate632of the reinforcing material63are respectively in contact with the projecting portion201and the projecting portion202. Therefore, gaps are respectively formed between a main body (a portion other than the projection6311) of the first plate631and a surface of the projecting portion201, and between a main body (a portion other than the projection6321) of the second plate632and a surface of the projecting portion202.

As shown inFIG. 19,FIG. 20, andFIG. 24, in the accommodating portion620, on the first side surface24L and the second side surface24R, the projection204for restricting the movement in the longitudinal direction of the reinforcing material63after the reinforcing material63is accommodated in the accommodating portion620. That is, as shown inFIG. 24, in a state where the reinforcing material63is accommodated in the accommodating portion620, the second plate632of the reinforcing material63contacts the projection204. Thus, the movement of the reinforcing material63to the outside (the right side inFIG. 24) is restricted.

In the example of the present embodiment, the projection204is formed near an opening of the opening200.

As shown inFIG. 19,FIG. 21, andFIG. 24, the accommodating portion620has the connecting portion203connecting the first foamed portion621and the second foamed portion622. The connecting portion203is provided so as not to make the first foamed portion621and the second foamed portion622separate from each other with the reinforcing material63interposed therebetween, and is provided to maintain an integral structure of the foam62before and after the reinforcing material63is accommodated in the accommodating portion620. The connecting portion203is formed in the accommodating portion620. Therefore, before and after the reinforcing material63is accommodated in the foam62, there is no positional displacement between the first foamed portion621and the second foamed portion622with the reinforcing material63as a boundary. Therefore, dimensional accuracy of the foam62is high.

In the foam62of the present embodiment, the accommodating portion620and the raised portion25overlap each other in a plan view of the foam62. Therefore, as shown inFIG. 24, the connecting portion203and the raised portion25have an integral structure. The connecting portion203is formed near the both ends in the longitudinal direction of the accommodating portion620(that is, near the opening200), and supports both ends of the second plate632of the reinforcing material63. This makes it possible to stably accommodate the reinforcing material63in the accommodating portion620. That is, inFIG. 24, the reinforcing material63can be supported by the projecting portions201and202and the connecting portion203(at different positions in the longitudinal direction of the accommodating portion620) in both an upward direction and a downward direction inFIG. 24. Therefore, after the reinforcing material63is accommodated in the accommodating portion620, the reinforcing material63can be stably supported.

As shown inFIGS. 19 and 22, a through-hole206is formed in the accommodating portion620. The through-hole206is adjacent to one end in the longitudinal direction of the projecting portions201and202and penetrates the front surface62T and the back surface62B of the foam62. In an example of the accommodating portion620of the present embodiment, the through-hole206is formed between both ends in the longitudinal direction of the projecting portions201and202and the connecting portion203. By providing the through-hole206adjacent to the one end in the longitudinal direction of the projecting portions201and202, it is easy to insert the reinforcing material63into the projecting portions201and202from the first opening200L or the second opening200R as described below.

(3-3) Method of Molding Foam

Next, a method of molding the foam62of the present embodiment will be described with reference toFIGS. 25A and 25B.FIGS. 25A and 25Bare views for explaining steps of molding the foam62of the embodiment.

The foam62is molded by the bead method in-mold foam molding method using a molding apparatus650shown inFIGS. 25A and 25B. As shown in Step S30ofFIG. 25A, the molding apparatus650is provided with molds651and652facing each other. The molds651and652respectively constitute parts of empty chambers53and54. Cooling pipes41and42are arranged in the empty chambers53and54.

InFIG. 25A, when the molds651and652are closed from a state shown in Step S30, an enclosed space650ais formed by the molds651and652as shown in Step S31. With the molds651and652closed, foamed beads are filled through feeders43and44.

An amount of the foamed beads to be filled is, for example, 105 to 110% of the volume of the enclosed space650a. Next, as shown in Step S32ofFIG. 25B, steam (for example, a steam pressure of 3.0 to 3.5 kgf/cm2) is injected into the empty chambers53and54from steam injection ports55and56, for example, for 10 to 30 seconds. The steam enters gaps between cells in the foamed beads from fine pores formed in the mold and fuses the beads to each other. Then, as shown in Step S33ofFIG. 25B, cooling water is injected into the cooling pipes41and42from cooling water inlets57and58and sprayed onto the molds651and652. In this way, the molds651and652and the foam62are cooled to solidify the foam62. Then, as shown in Step S34ofFIG. 25B, the mold is opened and the foam62is taken out. The foam62is then placed in a room, for example, at 50 to 70° C. for 12 to 24 hours, thereby promoting curing and inhibiting sink marks and deformation of the foam62.

As shown inFIGS. 18 and 19, the through-hole206is provided between the projecting portions201and202and the connecting portion203in the longitudinal direction of the accommodating portion620. This is also to enable opening and closing of the molds651and652. If the projecting portions201and202are extended to the outside of the state shown inFIGS. 18 and 19and a part of the projecting portions201and202overlap the connecting portion203in a plan view of the foam62, a part of the projecting portions201and202is an undercut. As a result, the mold cannot be opened or closed (an opening and closing direction of the mold is a direction perpendicular to a paper surface inFIG. 18).

(3-4) Method of Assembling Foamed Structure

Next, a method of assembling the foamed structure61of the present embodiment will be described with reference toFIGS. 26A and 26B.FIGS. 26A and 26Bare views for explaining a procedure for assembling the foamed structure61by attaching (inserting) the reinforcing material63to the foam62of the present embodiment.

As shown inFIG. 26A, to the foam62to which the reinforcing material63is not attached (Step S1), the reinforcing material63is inserted toward end portions of the projecting portions201and202from the first opening200L of the first side surface24L or the second opening200R of the second side surface24R so that the tip end of the reinforcing material63is obliquely downward (Step S2).

As described above, a through-hole206is formed adjacent to the one end in the longitudinal direction of the projecting portions201and202and penetrates the front surface62T and the back surface62B of the foam62. Therefore, in Step S2, the tip end of the reinforcing material63is inserted into the through-hole206, and the first plate631and the second plate632of the reinforcing material63can be respectively smoothly introduced into the groove g1(seeFIG. 23) on the front surface62T side and the groove g2(seeFIG. 23) on the back surface62B side, which are formed by the projecting portions201and202. After the first plate631and the second plate632of the reinforcing material63are respectively introduced into the grooves g1and g2, the reinforcing material63is further pushed in an insertion direction. At this time, as described above, the gaps are respectively formed between the main body (the portion other than the projection6311) of the first plate631and the surface of the projecting portion201, and between the main body (the portion other than the projection6321) of the second plate632and the surface of the projecting portion202. Therefore, an insertion resistance is small. As a result, the reinforcing material63can be pushed into the accommodating portion620with a relatively small pushing force.

Finally, the tip end of the reinforcing material63contacts the projection204. Then, as shown in Step S3ofFIG. 26B, both ends of the reinforcing material63are set between the projections204at both ends of the accommodating portion620. In this way, the reinforcing material63is accommodated in the accommodating portion620.

Note that a length of the through-hole206in the longitudinal direction of the accommodating portion620may be appropriately set from a viewpoint of ease of insertion of the reinforcing material63.

(3-5) Method of Molding Resin Panel

Next, referring toFIGS. 27 and 28, an apparatus and a method for molding the resin panel600of the present embodiment using the mold will be described.

Referring toFIG. 27, a clamping machine70has a pair of split mold blocks71A and71B to be moved between the open position and the closed position in a direction substantially perpendicular to the molten resin sheets P and P extruded vertically downward from the extruding machine (not shown). The pair of split mold blocks71A and71B is arranged in a state where the corresponding forming surfaces72A and72B face each other. The forming surface72A has a shape corresponding to the front surface62T of the foam62.

Pinch-off parts74A and74B are respectively formed near the upper and lower ends of the forming surfaces72A and72B respectively corresponding to the pair of split mold blocks71A and71B. The pinch-off parts74A and74B are respectively annularly formed around the forming surfaces72A and72B, and project toward the split mold blocks71B and71A facing each other. Thus, when clamping the pair of split mold blocks71A and71B, apex portions of the respective pinch-off parts74A and74B are brought into contact with each other so that parting lines PL are formed on the peripheral edges of the molten resin sheets P and P.

In the pair of split mold blocks71A and71B, sliding portions75A and75B are provided so as to project from the forming surfaces72A and72B around the forming surfaces72A and72B. The sliding portions75A and75B are provided so that their end surfaces are brought into contact with the molten resin sheets P and P in a state of projecting from the forming surfaces72A and72B, and thus an enclosed space is formed between the molten resin sheets P and P and the forming surfaces72A and72B of the pair of split mold blocks71A and71B.

The vacuum chamber (not shown) is incorporated in the pair of split mold blocks71A and71B. The vacuum chamber is connected to a vacuum pump and a vacuum tank (none of which are shown). A communication path (not shown) for vacuum suction is provided between the vacuum chamber and the forming surfaces72A and72B.

The pair of split mold blocks71A and71B is driven by a mold driving device (not shown) so as to be movable between the open position and the closed position. In the open position, two continuous molten resin sheets P and P can be disposed with a space from each other between the pair of split mold blocks71A and71B. The two molten resin sheets P and P are the skin material sheets SA and SB in the resin panel600after molding. In the closed position, the pinch-off parts74A and74B of the pair of split mold blocks71A and71B are in contact with each other.

Next, a method of molding the resin panel600will be described.

First, as shown inFIG. 27, the molten resin sheets P and P are extruded vertically downward from the extruding machine and supplied to between the forming surfaces72A and72B of the pair of split mold blocks71A and71B. At this point, the pair of split mold blocks71A and71B is in the open position.

Next, the sliding portions75A and75B around the forming surfaces72A,72B are projected, so that their end surfaces are brought into contact with the molten resin sheets P and P. Thus, the enclosed space is formed between the molten resin sheets P and P and the forming surfaces72A and72B of the pair of split mold blocks71A and71B. Then, air in the enclosed space is sucked through the communication path provided between the vacuum chamber and the forming surfaces72A and72B. By this suction, the two molten resin sheets P and P are respectively pressed against the forming surfaces72A and72B of the pair of split mold blocks71A and71B. As shown inFIG. 28, the molten resin sheets are shaped (formed) into a shape along the forming surfaces72A and72B, that is, a substantially outer shape of the resin panel600.

Next, using the manipulator (not shown), the foamed structure61is positioned between the pair of split mold blocks71A and71B. Then, as shown inFIG. 28, the foamed structure61is inserted from the side so as to be pressed against one of the split mold blocks (the split mold block71B inFIG. 28). Thus, the foamed structure61is welded to one molten resin sheet P.

Thereafter, the pair of split mold blocks71A and71B moves from the open position to the closed position, to be clamped. Thus, the foamed structure61which has been welded to the one molten resin sheet P (the right side in the drawing) is also welded to the other molten resin sheet P (the left side in the drawing). Further, the peripheral edge of the pair of molten resin sheets P and P is welded at the pinch-off parts74A and74B of the pair of split mold blocks71A and71B. Thus, the parting lines PL are formed.

Finally, by moving the pair of split mold blocks71A and71B to the open position again, the molded resin panel600separates from the forming surfaces72A and72B. Then, the burrs formed around the parting lines PL are cut and removed by the cutter or the like. Thus, the resin panel600in which the skin material sheet SA, the foamed structure61, and the resin sheet SB are laminated is completed.

The third embodiment of the present invention has been described in detail above. However, the foamed structure and the resin panel of the present invention are not limited to the above embodiment. Of course, various improvements or modifications can be made without departing from the scope of the present invention.

A modification of the third embodiment will be described below.

In the above-described embodiment, a case where the first opening200L of the first side surface24L and the second opening200R of the second side surface24R are formed at the both ends of the accommodating portion620has been described. However, the present invention is not limited to this, as long as either one of the first opening200L or the second opening200R is formed, it is easy to insert the reinforcing material63into the accommodating portion620.

The both ends of the accommodating portion620may not be open. For example, by setting an opening amount in the longitudinal direction of the accommodating portion620to be long in one of the through-holes206L and206R adjacent to one end of the projecting portions201and202, the reinforcing material63can be inserted into the projecting portions201and202from either one of the through-holes206L and206R.

In the above-described embodiment, an example in which the connecting portion203and the projection204have an integral structure has been described. However, the present invention is not limited to this, and the connecting portion203and the projection204may be separate bodies. For example, in a plan view ofFIG. 19, a through-hole penetrating the front surface62T and the back surface62B may be formed between the connecting portion203and the projection204.

Note that, as in the above-described embodiment, by having the integral structure of the connecting portion203and the projection204, a structure in which the end surface of the reinforcing material63is supported by both the first foamed portion621and the second foamed portion622is obtained. Therefore, it is possible to stably accommodate the reinforcing material63.

In the above-described embodiment, a case where the projections204L and204R are respectively formed near the first opening200L and the second opening200R has been described. However, the present invention is not limited to this, and at least one of the projections204L and204R may be provided inside the position shown inFIG. 19(that is, on the projecting portions201and202side) in the longitudinal direction of the accommodating portion620. In that case, a length in the longitudinal direction of the reinforcing material63is set so that the second plate632of the reinforcing material63is in contact with the projection204L and/or the projection204R.

In the above-described embodiment, a case where the reinforcing material63having the H-shaped cross-section is attached to the foam has been described. However, a shape of the reinforcing material is not limited thereto.

FIGS. 29A and 29Bshow a foam62A according to a modification of the embodiment.FIG. 29Ashows a plan view corresponding toFIG. 19.FIG. 29Bshows a cross-sectional view taken along a line F-F inFIG. 29A.

As shown inFIG. 29B, in the reinforcing material63A according to the modification, the first plate631A and the second plate632A which are linearly extended while facing each other are connected by a connecting plate633A. As a result, its cross-section is in a U shape.

As shown inFIGS. 29A and 29B, a projecting portion201A projects from the first foamed portion621toward the second foamed portion622in a portion where the first foamed portion621and the second foamed portion622are not connected (that is, a portion where through-holes205A and206are provided in the longitudinal direction of the projecting portion201A inFIG. 29A). In this modification, there is no projecting portion projecting from the second foamed portion622toward the first foamed portion621.

As shown inFIG. 29B, the thickness of the projecting portion201A is less than the thickness of the first foamed portion621. Thus, a groove g1A and a groove g2A are formed on the front surface62T side and the back surface62B side. The first plate631A and the second plate632A of the reinforcing material63A are respectively arranged in the groove g1A on the front surface62T side and the groove g2A on the back surface62B side.

Even with such a structure, in a state where the reinforcing material63A is accommodated in the foam62A, the projecting portion201A is in a state of being interposed between the first plate631A and the second plate632A of the reinforcing material63A in the thickness direction of the foam62A. Therefore, after the reinforcing material63A is attached to the foam62A, the movement of the reinforcing material63A in the direction perpendicular to the front surface62T and the back surface62B of the foamed body62A is restricted by the projecting portion201A. Therefore, the reinforcing material63A does not fall off in the direction. Furthermore, as in the above-described embodiment, the connecting portion203connecting the first foamed portion621and the second foamed portion622is provided. Therefore, there is no positional displacement between the first foamed portion621and the second foamed portion622with the reinforcing material63A as the boundary before and after the reinforcing material63A is accommodated in the foam62A. As a result, the dimensional accuracy of the foam62A is high.

In the foamed structure61of the above-described embodiment, the raised portions25L and25R are formed according to the shape of the resin panel600. However, the shape of the foamed structure is not limited to this example but is appropriately designed according to the shape of the resin panel. For example, the foamed structure may be made of only a flat portion. Even when the foamed structure is made of only the flat portion, as long as the first foamed portion621and the second foamed portion622are connected by the connecting portion203, there is no positional displacement between the first foamed portion621and the second foamed portion622with the reinforcing material63as the boundary. As a result, an effect that the dimensional accuracy of the foam62is high is obtained.

When at least a part of the accommodating portion620of the reinforcing material63overlaps the raised portion25in a plan view of the foam62like the foamed structure61of the above-described embodiment, it is difficult to adopt a conventional method, that is, a method of assembling the separate first foamed portion621and the second foamed portion622to the reinforcing material63from both sides thereof. Therefore, it is forced to adopt another method which causes deterioration of shape accuracy and/or cost increase, such as forming the raised portion25separately from the flat portion623. In contrast, by applying the present invention to the foamed structure61, there is an advantage that it is possible to set the accommodating portion620of the reinforcing material63at a position where at least a part of the accommodating portion620of the reinforcing material63overlaps the raised portion25in a plan view of the foam62.

Even in the foamed structure having the raised portion, the position of the reinforcing material can be set to a desired position. For example, in a plan view of the foam, at least a part of the accommodating portion of the reinforcing material may not necessarily overlap the projecting portion. In other words, by applying the present invention, it is possible to set the reinforcing material to the desired position in the foamed structure having the flat portion and the raised portion. Therefore, design freedom is improved.

In the above-described embodiment, a case where the projecting portion201and the projecting portion202are formed at a portion where the first foamed portion621and the second foamed portion622of the foam62are not connected has been described. However, the present invention is not limited to this, for example, as shown in a plan view ofFIG. 19, both of the projecting portions201and202and the connecting portion203, which are separated from each other with the through-hole206interposed therebetween, may be overlapped with each other in a plan view. For example, when a plate thickness of the foam62is large, it is possible to form a connecting portion at a portion near the front surface or the back surface, and further, a projecting portion at a center in a plate thickness direction.

Hereinafter, a resin panel81according to a fourth embodiment of the present invention and an interior material810installed in the resin panel81will be described. The interior material810for the resin panel81is an example of the foamed structure of the present invention.

First, structures of the resin panel81and the interior material810of the present embodiment will be described with reference toFIGS. 30 to 33.FIG. 30is a perspective view of a back side of the resin panel81of the present embodiment.FIG. 31is a perspective view of a back side of the interior material810of the present embodiment.FIG. 32is a perspective view of a front side of the interior material810of the present embodiment.FIG. 33is a perspective view of a reinforcing material83incorporated in the interior material810.

As shown inFIGS. 30 and 31, a surface of the resin panel81according to the present embodiment is made of a skin material sheet S of the thermoplastic resin. The interior material810is installed in the resin panel81. That is, the resin panel81has a structure including the interior material810covered with the skin material sheet S of the thermoplastic resin.

As shown inFIG. 30, an exemplary resin panel81in the present embodiment has a form including a raised portion812formed on a substantially rectangular parallelepiped base portion811on the back side.

In the resin panel81of the embodiment, the resin material of the skin material sheet S to be the skin material sheet is not limited. However, in order to ensure the stiffness of the resin panel81, the resin panel81is preferably formed of the non-foamed resin. For example, in consideration of moldability, the resin material of the skin material sheet S may be the resin material obtained by mixing polystyrene (PS) and styrene ethylene butylene styrene block copolymer resin (SEBS) in polypropylene (PP) which is the main material.

As shown inFIGS. 31 and 32, the interior material810is a complex structure including a foam82including foamed portions821to823corresponding to a base portion811of the resin panel81, and a foamed portion825corresponding to the raised portion812of the resin panel81, and two reinforcing materials83fitted into the foam82. The reinforcing materials83are respectively interposed between the foamed portion821and the foamed portion822and between the foamed portion822and the foamed portion823.

As shown inFIG. 31, the foamed portion825rising from a back surface of the foamed portions821to823is formed on a back surface82bof the foam82. As shown inFIG. 32, a front surface82aof the foam82is a substantially flat surface.

As shown inFIG. 33, the reinforcing material83includes a pair of elongated first plate-shaped portion831and a second plate-shaped portion832facing each other with a predetermined amount of gap interposed therebetween, and the connecting plate33connecting the first plate-shaped portion831and the second plate-shaped portion832. In an example shown inFIG. 33, the reinforcing material83has an H-shaped cross-section (H-shaped reinforcement).

Projections8311projecting toward the second plate-shaped portion832are provided at both ends of the first plate-shaped portion831. Projections8321projecting toward the first plate-shaped portion831are provided at both ends of the second plate-shaped portion832.

A material of the reinforcing material83is not particularly limited. However, the reinforcing material83is preferably made of a metal such as aluminum or a hard plastic in order to secure the strength of the resin panel81. The reinforcing material83is molded by, for example, extrusion molding.

A cross-sectional shape of the reinforcing material83is not limited to an illustrated shape. For example, the cross-sectional shape may be C shape, U shape, square pipe shape, circular pipe shape or the like. Any shape may be used as long as it can be fitted into and integrated with each foam.

In the resin panel81of the embodiment, the foamed portions821to823and825are molded using, for example, the thermoplastic resin. The resin material is not limited. For example, the resin materials include a polyolefin such as polypropylene or polyethylene, an acrylic derivative such as polyamide, polystyrene or polyvinyl chloride, or a mixture of two or more kinds. The expansion ratio of the foamed portions821to823,825is not particularly limited. The expansion ratio is, for example, in a range of 1.5 to 60 times, typically 20 or 30 times, preferably 10 to 45 times, more preferably 15 to 35 times.

Examples of the foaming agent which can be used for the foamed portions821to823,825in the resin panel81of the embodiment include known physical foaming agents, known chemical foaming agents, and mixtures thereof. Examples of applicable physical foaming agents include inorganic physical foaming agents such as air, carbonic acid gas or nitrogen gas, and organic physical foaming agents such as butane, pentane, hexane, dichloromethane, dichloroethane or the like. Examples of chemical foaming agents include organic foaming agents such as azodicarbonamide (ADCA), N, N′-dinitrosopentamethylenetetramine, 4,4′-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3′-disulfonylhydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine or azobisisobutyronitrile, and inorganic foaming agents such as mixtures of polycarboxylic acid such as citric acid, oxalic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, cyclohexane-1,2-dicarboxylic acid, camphoric acid, ethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid or nitriloic acid and inorganic carbonate compound such as sodium hydrogencarbonate, aluminum sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium hydrogencarbonate, or ammonium carbonate, or polycarboxylate such as citrate dihydrogen sodium hydrogen or potassium oxalate and the like.

For the purpose of increasing the stiffness and strength, the skin material sheet S and the foamed portions821to823,825may be molded using the resin material mixed with the glass filler. As the glass filler, the same glass filler as the glass filler mentioned in the first embodiment may be used.

(4-2) Detailed Structure of Interior Material810

Next, a detailed structure of the interior material810of the present embodiment will be described with reference toFIGS. 34 to 38.

(4-2-1) Structure of Foam82

First, a structure of the foam82will be described with reference toFIGS. 34 to 38.

FIG. 34is a perspective view of the front side of the foam82of the present embodiment.FIGS. 35A and 35Bare respectively enlarged views of a G1portion and a G2portion ofFIG. 34.FIG. 36is a plan view of the G1portion and the G2portion of the foam82of the present embodiment.FIG. 37Ais a cross-sectional view taken along a line A-A or a line D-D shown inFIG. 36.FIGS. 37B and 37Care respectively cross-sectional views taken along a line B-B and a line E-E shown inFIG. 36.FIGS. 38A and 38Bare respectively cross-sectional views taken along a line C-C and a line F-F shown inFIG. 36.

The foam82is molded, for example, by the bead method in-mold foam molding method. As an example of molding by the bead method in-mold foam molding method, see for example JP-A-2014-128938.

As shown inFIG. 34, linear accommodating portions901,902are formed on the front surface of the foam82through from one end to the other end. In an example of the present embodiment, both of the accommodating portions901,902have the same shape. The accommodating portion901is formed between the foamed portion821and the foamed portion822. The accommodating portion902is formed between the foamed portion822and the foamed portion823. Each accommodating portion is provided for disposing the reinforcing material83(H-shaped reinforcement) shown inFIG. 4in the foam82.

Referring toFIGS. 35A, 35B and 36, in the foam82, fitting portions913and923fitted with one end in the longitudinal direction of the reinforcing material83and fitting portions917and927fitted with the other end in the longitudinal direction of the reinforcing material83are formed in the G1portion and the G2portion near both ends of the accommodating portion901. Stoppers915,925,919and929are formed in the G1portion and the G2portion of the foam82in order to reliably inhibit the reinforcing material83from falling off from the foam82in its longitudinal direction.

InFIG. 36, a bottom face930of the accommodating portion901is a surface on which the reinforcing material83is placed. The bottom face930is a surface which is in contact with the second plate-shaped portion832of the reinforcing material83.

A more detailed description will be made below with reference to the cross-sectional views ofFIGS. 37A to 37C and 38A and 38B. InFIGS. 37A to 37C and 38Aand B, the position of the reinforcing material83when the reinforcing material83is incorporated in the foam82is indicated by imaginary lines. In the following description, the accommodating portion901will be referred to. The accommodating portion902has the same shape as the accommodating portion901.

As shown in an A-A cross-section and a D-D cross-section ofFIG. 37A, the accommodating portion901of the foam82is formed with side surfaces911and921facing each other and a bottom face930. The side surface911is interposed between the bottom face930and a front surface821aof the foamed portion821. The side surface921is interposed between the bottom face930and a front surface822aof the foamed portion822.

In a state where the reinforcing material83is fitted with the foam82, the second plate-shaped portion832of the reinforcing material83is in contact with the bottom face930. Both side surfaces of the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83are in contact with the side surfaces911and921.

In a state where the reinforcing material83is in contact with the bottom face930of the accommodating portion901, a depth of the accommodating portion901is preferably set such that the front surfaces821aand822aof the foamed portions821and822and a top surface of the first plate-shaped portion831of the reinforcing material83are substantially flush with each other. However, the depth of the accommodating portion901is not limited thereto.

As shown inFIG. 35Aand a cross-section B-B ofFIG. 37B, the fitting portions913and923are formed to project from the side surfaces911and921of the accommodating portion901to directions opposite to each other. The fitting portions913and923are located in a gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83, and thus they are fitted with one end in the longitudinal direction of the reinforcing material83.

As shown inFIG. 35Band a cross-section E-E ofFIG. 37C, the fitting portions917and927are formed to project from the side surfaces911and921of the accommodating portion901to the directions opposite to each other. The fitting portions917and927are located in the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83, and thus they are fitted with the other end in the longitudinal direction of the reinforcing material83.

As shown in a cross-section C-C ofFIG. 38A, the fitting portion913is a plate-shaped portion formed in the longitudinal direction of the reinforcing material83. The fitting portion913projects from one end of the reinforcing material83into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83, to be fitted with the reinforcing material83.

A front surface913aof the fitting portion913is substantially parallel to the longitudinal direction of the reinforcing material83, that is, substantially parallel to the top surface of the first plate-shaped portion831and the bottom face of the second plate-shaped portion832. A back surface913bof the fitting portion913is inclined from a tip end surface913tof the portion projecting into the gap of the reinforcing material83toward the one end of the reinforcing material83. Therefore, a thickness of the fitting portion913in a direction in which the first plate-shaped portion831and the second plate-shaped portion832are facing each other is increased, from the tip end surface913tof the portion projecting into the gap of the reinforcing material83to the one end of the reinforcing material83.

As shown in a cross-section F-F ofFIG. 38B, the fitting portion917is a plate-shaped portion formed in the longitudinal direction of the reinforcing material83. The fitting portion917projects from the one end of the reinforcing material83into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83, to be fitted with the reinforcing material83.

The front surface917aand the back surface917bof the fitting portion917are substantially parallel to the longitudinal direction of the reinforcing material83, that is, substantially parallel to the top surface of the first plate-shaped portion831and the bottom face of the second plate-shaped portion832. That is, the fitting portion917is formed so that its thickness is substantially constant in a direction from the tip end surface917tof the portion projecting into the gap of the reinforcing material83toward the one end of the reinforcing material83.

As shown in the cross-section C-C ofFIG. 38A, the stopper915has a wall surface915wfacing one end of the reinforcing material83at an end opposite to the tip end surface913tof the fitting portion913. Although not shown, the stopper925also has a similar wall surface.

As shown in the cross-section F-F ofFIG. 38B, the stopper919has a wall surface919wfacing the one end of the reinforcing material83at the end opposite to the tip end surface917tof the fitting portion917. Although not shown, the stopper929also has a similar wall surface.

A cross-sectional shape of the fitting portion923and the stopper925is the same as the cross-section taken along the line C-C inFIG. 38A. A cross-sectional shape of the fitting portion927and the stopper929is the same as the cross-section taken along the line F-FFIG. 38B.

(4-2-2) Assembly of Interior Material810

Next, a method of assembling the interior material810based on the above-described foam82will be described with reference toFIGS. 39A and 39B.

FIGS. 39A and 39Bare views for explaining a method of assembling the interior material810of the present embodiment.FIGS. 39A and 39Bshow a procedure for fitting the reinforcing material83into the foam82in this order.

To assemble the interior material810, the foam82is molded first. Thereafter, the foam82is disposed so that the front surface of the foam82faces upward.

Then, as shown inFIG. 39A, the reinforcing material83is inclined so that one end of the reinforcing material83is obliquely downward. In this way, the reinforcing material83is pressed against the foam82so that the fitting portions917and927of the foam82are inserted into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83at the one end of the reinforcing material83. Thus, the one end of the reinforcing material83is fitted into the fitting portions917and927of the foam82.

Next, as shown inFIG. 39B, at the other end not fitted of the reinforcing material83, the reinforcing material83is positioned so that the fitting portions913and923of the foam82are inserted into a gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83. Thus, the other end of the reinforcing material83is fitted with the fitting portions913and923of the foam82.

As shown in the cross-section C-C ofFIG. 38A, in a state where the other end of the reinforcing material83is fitted into the fitting portions913and923of the foam82, the fitting portions913and923are in a state of projecting into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83.

At this time, the thickness of the fitting portion913in the direction in which the first plate-shaped portion831and the second plate-shaped portion832are facing each other is increased, from the tip end surface913tof the portion projecting into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83to the one end of the reinforcing material83. The same applies to the fitting portion923. Therefore, the second plate-shaped portion832of the reinforcing material83is sandwiched between the back surface913bof the fitting portion913and the bottom face930(seeFIG. 37A) of the accommodating portion901, and between the back surface (not shown) of the fitting portion923and the bottom face930of the accommodating portion901. From this fact, the reinforcing material83is positioned in its longitudinal direction.

Furthermore, in the foam82of the present embodiment, the stoppers915,925,919and929reliably inhibit the reinforcing material83from falling off from the foam82. In particular, as shown in the cross-section F-F ofFIG. 38B, the fitting portion917does not sandwich the second plate-shaped portion832with the bottom face930. However, even when the reinforcing material83moves toward the fitting portion917, the reinforcing material83does not fall off from the foam82by the stopper919.

FIGS. 39A and 39Bshows a case where the reinforcing material83is disposed in the accommodating portion901. Similarly, the reinforcing material83is also disposed on the accommodating portion902. As a result, the two reinforcing materials83are fitted into the foam82. In this way, the interior material810is completed.

In the above-described method of assembling the interior material810, the fitting portions917and927of the foam82are first inserted into the one end of the reinforcing material83. Thereafter, the fitting portions913and923of the foam member82are inserted into the other end of the reinforcing material83. However, this order may be interchanged.

A fitting method of the reinforcing material83of the present embodiment is suitable when the foamed portion825(seeFIG. 2) raised on the back surface82bof the foam82is formed. That is, when there is a raised portion on at least one of the front surface and the back surface of the foam, the thickness of the raised portion is relatively large. Therefore, if a method of splitting the foam at the raised portion and then fitting the reinforcing material is adopted, the raised portion having a large thickness is divided into two portions. Therefore, it is inevitable that the stiffness of the raised portion is locally reduced. In contrast, in the present embodiment, the reinforcing material83can be fitted without splitting the foam82at the foamed portion825which is the raised portion. Therefore, it is possible to avoid a local stiffness reduction in the foamed portion825.

(4-3) Method of Molding Resin Panel81

Next, referring toFIGS. 40 and 41, a method of molding the resin panel81including the interior material810covered with the skin material sheet S using the mold will be described.FIGS. 40 and 41are views for explaining steps of molding the skin material sheet S of the resin panel81of the present embodiment.

Referring toFIG. 40, a clamping machine870has a pair of split mold blocks871A and871B to be moved between the open position and the closed position in the direction substantially perpendicular to the molten resin sheets P and P extruded vertically downward from the extruding machine (not shown). The pair of split mold blocks871A and871B is arranged in a state where the corresponding forming surfaces872A and872B face each other. The forming surface872A has a shape corresponding to the front surface and the back surface of the foam82.

Pinch-off parts874A and874B are respectively formed near the upper and lower ends of the forming surfaces872A and872B respectively corresponding to the pair of split mold blocks871A and871B. The pinch-off parts874A and874B are respectively annularly formed around the forming surfaces872A and872B, and project toward the split mold blocks871B and871A facing each other. Thus, when clamping the pair of split mold blocks871A and871B, the apex portions of the respective pinch-off parts874A and874B are brought into contact with each other so that the parting lines are formed on the peripheral edges of the molten resin sheets P and P.

In the pair of split mold blocks871A and871B, sliding portions875A and875B are provided so as to project from the forming surfaces872A and872B around the forming surfaces872A and872B. The sliding portions875A and875B are provided so that their end surfaces are brought into contact with the molten resin sheets P and P in a state of projecting from the forming surfaces872A and872B, and thus an enclosed space is formed between the molten resin sheets P and P and the forming surfaces872A and872B of the pair of split mold blocks871A and871B.

The vacuum chamber (not shown) is incorporated in the pair of split mold blocks871A and871B. The vacuum chamber is connected to a vacuum pump and a vacuum tank (none of which are shown). A communication path (not shown) for vacuum suction is provided between the vacuum chamber and the forming surfaces872A and872B.

The pair of split mold blocks871A and871B is driven by a mold driving device (not shown) so as to be movable between the open position and the closed position. In the open position, two continuous molten resin sheets P and P can be disposed with a space from each other between the pair of split mold blocks871A and871B. The two molten resin sheets P and P is the skin material sheet S in the resin panel81after molding. In the closed position, the pinch-off parts874A and874B of the pair of split mold blocks871A and871B are in contact with each other.

Next, a method of molding the resin panel81will be described.

First, as shown inFIG. 40, the molten resin sheets P and P are extruded vertically downward from the extruding machine and supplied to between the forming surfaces872A and872B of the pair of split mold blocks871A and871B. At this point, the pair of split mold blocks871A and871B is in the open position.

Next, the sliding portions875A and875B around the forming surfaces872A and872B are projected, so that their end surfaces are brought into contact with the molten resin sheets P and P. Thus, the enclosed space is formed between the molten resin sheets P and P and the forming surfaces872A and872B of the pair of split mold blocks871A and871B. Then, air in the enclosed space is sucked through the communication path provided between the vacuum chamber and the forming surfaces872A and872B. By this suction, the two molten resin sheets P and P are respectively pressed against the forming surfaces872A and872B of the pair of split mold blocks871A and871B. As a result, as shown inFIG. 41, the two molten resin sheets P and P are shaped (formed) into a shape along the forming surfaces872A and872B, that is, a substantially outer shape of the resin panel81.

Next, using the manipulator (not shown), the interior material810assembled as described above is positioned between the pair of split mold blocks871A and871B. Then, as shown inFIG. 41, the interior material810is inserted from the side so as to be pressed against one of the split mold blocks (the split mold block871B inFIG. 41). Thus, the interior material810is welded to one molten resin sheet P.

At this time, as described above, the reinforcing material83is positioned in its longitudinal direction in the interior material810. Therefore, even when the interior material810is disposed so that the longitudinal direction of the reinforcing material83is in the vertical direction, it is possible to inhibit the reinforcing material83from falling off from the interior material810.

Thereafter, the pair of split mold blocks871A and871B is moved from the open position to the closed position, to be clamped. Thus, the interior material810which has been welded to the one molten resin sheet P (the right side in the drawing) is also welded to the other molten resin sheet P (the left side in the drawing). Further, the peripheral edge of the pair of molten resin sheets P and P is welded at the pinch-off parts874A and874B of the pair of split mold blocks871A and871B, and the parting lines PL are formed.

Finally, the pair of split mold blocks871A and871B is moved to the open position again to separate the molded resin panel81from the forming surfaces872A and872B. In this way, the burrs formed around the parting line PL are cut and removed by the cutter or the like. Thus, the resin panel81having a structure in which the interior material810is covered with the skin material sheet S is completed.

In the above-described method of molding the resin panel81, a case where the molten resin sheet P is pressed against the forming surfaces872A and872B of the pair of split mold blocks871A and871B by suction has been described. However, the present invention is not limited thereto, and a fluid such as air may be blown onto the molten resin sheet P to press the molten resin sheet P against the forming surfaces872A and872B of the pair of split mold blocks871A and871B (blow molding).

The fourth embodiment of the present invention has been described in detail above. However, the resin panel and the foamed structure of the present invention are not limited to the above embodiment. Of course, various improvements or modifications can be made without departing from the scope of the present invention.

In the fitting portion913shown in the cross-section C-C ofFIG. 38A, a case where the back surface913bis inclined from the tip end surface913tof the portion projecting into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83to the one end of the reinforcing material83has been exemplified. However, the present invention is not limited to this, and it is sufficient that the thickness of the fitting portion is increased from the tip end surface913tof the portion projecting into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83to the one end of the reinforcing material83. The inclined surface is not limited to the back surface913b.

For example, like a fitting portion913A of a modification shown inFIG. 42A, both of the front surface913aand a back surface913Ab may be inclined from the tip end surface913At of the portion projecting into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83to the one end of the reinforcing material83. Like a fitting portion913B of a modification shown inFIG. 42B, the front surface913Ba may be inclined from the tip end surface913Bt of the portion projecting into the gap between the first plate-shaped portion831and the second plate-shaped portion832of the reinforcing material83to the one end of the reinforcing material83.

In the above-described embodiment, as shown inFIGS. 35A, 35B, 38A and 38B, a case where the fitting portion and the stopper are connected has been described. However, the present invention is not limited to this, but the fitting portion and the stopper may be formed separately from each other. In that case, inFIGS. 35A and 35B, for example, a position where the fitting portions913and923project from the side surface of the accommodating portion901may be located closer to a center of the accommodating portion901.

In the above-described embodiment, a case where the stoppers915,919,925and929are formed in the foam82has been described. However, at least one of the stoppers may not be provided. Or, no stopper may be provided. Even when the stopper is not provided, the reinforcing material83is positioned as long as the reinforcing material83is held by the fitting portion. Therefore, a possibility that the reinforcing material83falls off from the foam82is extremely low.

In the above-described embodiment, as described inFIGS. 35A, 35B and 36, a case where fitting portions are provided on both end sides of the accommodating portion901has been described. However, the present invention is not limited to this, and the fitting portion may be provided only on one end side of the accommodating portion901. Even in that case, when the reinforcing material83is held by the fitting portion on the one end side of the accommodating portion901, the reinforcing material83can be positioned.

In the above-described embodiment, the front surface and/or the back surface of one of the pair of fitting portions (for example, the fitting portion913and the fitting portion923) facing each other across the bottom face930may be an inclined surface. Or, the front surface and/or the back surface of both of the fitting portions may be inclined surfaces.

The reinforcing material83may be fitted into the foam82by inserting two foamed portions obtained by splitting the molded foam from one side and the other side of the reinforcing material83. A foam according to such a modification is shown inFIGS. 43A and 43B.FIGS. 43A and 43Bare views for explaining the foam according to the modification.FIG. 43Ashows a part of a plan view of the foam, andFIG. 43Bshows a cross-section H-H ofFIG. 43A. InFIG. 43B, the reinforcing material83disposed after splitting is indicated by imaginary lines.

In the modification shown inFIGS. 43A and 43B, the accommodating portion901has a projecting portion941projecting from the end portion of the foamed portion821, a projecting portion942projecting from the end portion of the foamed portion822, and a thin portion943interposed between the projecting portion941and the projecting portion942. After the foam is molded, the foam is split at the thin portion943. The projecting portion941is inserted into one side of the reinforcing material83in the longitudinal direction of the reinforcing material83. The projecting portion942is inserted into the other side of the reinforcing material83in the longitudinal direction of the reinforcing material83. As a result, the reinforcing material83is fitted into the foam82.

It goes without saying that the shape of the fitting portion is appropriately changed according to the cross-sectional shape of the reinforcing material. That is, when the cross-sectional shape of the reinforcing material is the C shape, the U shape, the square pipe shape, the circular pipe shape or the like, the shape of the fitting portion can be set so that the thickness of the fitting portion is larger or so that a surface pressure between the fitting portion and the reinforcing material is higher from the tip end surface of the portion located in the gap in the reinforcing material of the fitting portion to the one end of the reinforcing material.