Molded structure and method for manufacturing a molded structure

Abstract

To provide a molded structure and a method for manufacturing the molded structure in which the rigidity of a terminal part can be secured even when a number of heat treatments is reduced.SOLUTION: A molded structure has a resin reinforcement part 21 provided at an inner side 10B of a rising part 15 of a base material 10, wherein the resin reinforcement part 21 is made of thermoplastic resin, covers the entire inner side 10B, and reinforces the strength of the rising part 15, wherein the base material 10 comprises a body part 11 constituting the main part of a plate containing fibers and thermoplastic resin, and the rising part 15 formed by bending at least a portion of the peripheral edge of the plate and rising from the body part 11.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed herein relates to a molded structure and a method for manufacturing the molded structure. [Background technology]

[0002] A conventionally known method for manufacturing a molded structure is that described in Patent Document 1. Patent Document 1 describes a method for manufacturing a vehicle interior material (substrate) by heating and cooling a thermoforming fiberboard formed into a mat from a blend of resin fibers and plant fibers to produce a preboard, reheating the preboard to a temperature at which the resin melts, and then press-molding the preboard using upper and lower dies for cold press molding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-179716 Summary of the Invention [Problem to be solved by the invention]

[0004] In the manufacturing method of the molded structure disclosed in Patent Document 1, heat treatment is performed twice, once when preparing the pre-board and once when molding the substrate, which increases processing costs, lengthens cycle time, and increases manufacturing costs. Furthermore, during the heat treatment, the pre-board emits a distinctive odor and volatile organic compounds in the pre-board, which are unfriendly to the environment.

[0005] In order to solve such problems, it is conceivable to reduce the number of heat treatment times. However, when the process of reheating the prepreg during the press forming of the base material is omitted, there is a situation where the prepreg (base material) becomes hard and difficult to extend. And when cutting the terminal portion while bending such a prepreg that is hard to stretch during the formation of the base material, the shear blade for cutting provided in the mold slides on the surface of the prepreg and damages the prepreg, so there is a concern that the terminal portion of the completed base material becomes partially thin and the rigidity decreases.

[0006] The technology disclosed in this specification has been completed based on the above circumstances, and an object thereof is to provide a molding structure and a method for manufacturing the molding structure capable of ensuring the rigidity of the terminal portion even when the number of heat treatment times is reduced.

Means for Solving the Problems

[0007] The molding structure disclosed in this specification includes a main body portion composed of a main part of a plate-like body containing fibers and a thermoplastic resin, and at least a part of the peripheral edge portion of the plate-like body is bent to form a standing portion rising from the main body portion. On the inner surface of the standing portion of the base material, a resin reinforcing portion made of a thermoplastic resin is provided to cover the entire inner surface and reinforce the strength of the standing portion.

[0008] During the manufacture of the molding structure, for example, when at least a part of the peripheral edge portion of the plate-like body is bent by press forming or the like to form a standing portion, the periphery of the tip portion may be damaged by a shear blade provided in the mold for cutting the tip portion, and the plate thickness of the damaged portion may become thin. According to the above configuration, even in such a case, the rigidity of the standing portion can be ensured by the resin reinforcing portion. In particular, when the plate material to be molded is hard and difficult to deform, such as when heating before press forming is omitted for cost reduction or the like, it is easily damaged by the shear blade, so the effect of this configuration can be remarkable.

[0009] A recess that is recessed from the outer surface is provided on the outer surface of the boundary portion, which is the boundary between the main body portion and the upright portion, and the recess may be filled with a thermoplastic resin.

[0010] According to the above configuration, the strength of the boundary portion with a reduced plate thickness due to the recess can be improved by the thermoplastic resin filled in the recess. Further, the bent shape of the molded structure can be maintained by the thermoplastic resin filled in the recess. Furthermore, since the outer surface of the boundary portion is made of a thermoplastic resin, the accuracy of the curvature of the outer surface of the boundary portion (bent portion) can be improved.

[0011] The resin filled in the recess may be composed of the same thermoplastic resin as the resin constituting the resin reinforcing portion.

[0012] According to the above configuration, at the time of manufacturing the molded structure, the recess can be filled with the molten resin simultaneously with injecting the molten resin for molding the resin reinforcing portion.

[0013] The plate thickness of the upright portion may be formed thinner than the plate thickness of the main body portion.

[0014] According to the above configuration, by adjusting the thickness of the resin reinforcing portion that covers the inner surface of the upright portion, the total thickness of the upright portion and the resin reinforcing portion can be made equal to the thickness of the main body portion. Further, when the base material is press-molded, if the plate thickness of the portion that becomes the upright portion is thin, that portion is likely to bend, and damage by the shear blade can be reduced. Thus, the surface of the molded structure can be formed beautifully.

[0015] The molded structure is a seat back board that constitutes the back of a vehicle seat, and the boundary portion may be disposed at the upper end of the seat back board with the outer surface of the boundary portion facing the inside of the vehicle compartment in a state where the seat back board is attached to the vehicle.

[0016] In the seat back board of a vehicle seat, in order to ensure safety during a collision, the curvature of the bent portion (the boundary portion of the present invention) arranged at the upper end of the seat back board is strictly defined. In particular, when heating before press forming is omitted for cost reduction or the like, and the plate material to be formed is hard and difficult to deform, it is difficult to achieve the accuracy of the curvature of the bent portion, so the effect of this configuration can be remarkable.

[0017] A molded body formed of a thermoplastic resin is integrally provided, and the molded body may be composed of the same thermoplastic resin as the resin constituting the resin reinforcing portion.

[0018] According to the above configuration, at the time of manufacturing the molded structure, simultaneously with injecting the molten resin for molding the resin reinforcing portion, the molded body provided in the main body portion can be injection molded.

[0019] Further, the technology disclosed in this specification is a method for manufacturing a molded structure, including a pre-board forming step of thermally pressing a mat containing fibers and a thermoplastic resin with a press mold to form a pre-board, and pressing the pre-board with a molding die at a temperature at which the thermoplastic resin does not melt to form a main body portion composed of the main part of the plate-like body and a standing portion rising from the main body portion by bending at least a part of the peripheral edge portion of the plate-like body. A press molding step of molding a base material having the above, and a resin reinforcing portion molding step of injecting a thermoplastic resin onto the inner surface of the standing portion to cover the entire inner surface and reinforce the strength of the standing portion are sequentially executed.

[0020] According to the above manufacturing method, even when the pre-board is not heated during the press molding of the molded structure and the surface of the standing portion is scraped by the shear blade for terminal cutting provided on the molding die and the rigidity is impaired, the rigidity of the standing portion can be enhanced by the resin reinforcing portion.

[0021] In the pre-board forming step, a thin-walled portion that is made thin is formed at at least a part of the peripheral edge of the pre-board, and in the press forming step, the standing portion formed by raising the thin-walled portion from the main body portion by bending the thin-walled portion may be formed.

[0022] According to the above configuration, by adjusting the thickness of the resin reinforcing portion, the total thickness of the standing portion and the resin reinforcing portion can be made equal to the thickness of the main body portion. Further, since the thin-walled portion is easily bent, damage by a shear blade during press forming can be reduced. Thus, the surface of the formed structure can be beautifully formed.

[0023] In the pre-board forming step, by pressing the mat so as to have a stepped portion that forms a stepped shape on one surface, the thin-walled portion in which the outer peripheral edge portion of the stepped portion is made thin is formed, and in the press forming step, the thin-walled portion is bent at a position separated from the stepped portion so that the stepped portion is on the outside, thereby forming a recess that is constituted by a part of the stepped portion and the thin-walled portion and that is recessed from the outer surface at the boundary portion that is the boundary between the main body portion and the standing portion. Then, a resin filling step of filling the recess with a thermoplastic resin may be executed in a state where the mold is closed.

[0024] According to the above configuration, even when the pre-board is not heated during press forming of the formed structure, the peripheral edge portion (thin-walled portion) of the pre-board can be easily bent as compared with the case where the thin-walled portion is not formed, and a recess for filling the boundary portion with a thermoplastic resin can be formed. Further, by filling the recess with a thermoplastic resin, the strength of the boundary portion can be improved and the bent shape of the formed structure can be maintained. Furthermore, since the thermoplastic resin filled in the recess is injection-molded in the mold, the accuracy of the curvature of the outer surface of the boundary portion (bent portion) can be improved.

[0025] The resin filling step may be executed simultaneously with the resin reinforcing portion forming step, and the same thermoplastic resin that constitutes the resin reinforcing portion may be filled into the recess from the inside of the boundary portion.

[0026] According to the above manufacturing method, no trace of the injection port is formed on the outer periphery of the bent portion (the boundary portion between the main body portion and the standing portion) of the molded structure, and the outer periphery can be beautifully molded.

[0027] The method includes a molded body molding step of injection molding a molded body made of the same thermoplastic resin as the resin constituting the resin reinforcing portion, and the molded body molding step may be executed simultaneously with the resin reinforcing portion molding step.

[0028] According to the above manufacturing method, the molded body can be injection molded simultaneously with filling the recess.

Advantages of the Invention

[0029] According to the technology disclosed in this specification, it is possible to provide a molded structure and a method for manufacturing the molded structure capable of ensuring the rigidity of the terminal portion even when the number of heat treatment times is reduced.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiment for Carrying out the Invention

[0031] One embodiment will be described with reference to Figs. 1 to 13. The forming structure and the manufacturing method of the forming structure of the present embodiment are adopted for the seat back board 5 constituting the vehicle seat 1 such as an automobile. More specifically, as shown in Fig. 1, the vehicle seat 1 includes a seat cushion 2 and a seat back 3, and the seat back board 5 constitutes the back surface of the seat back 3. In some drawings, the X-axis, Y-axis, and Z-axis are shown, and each axis direction is drawn so as to be the direction shown in each drawing. Regarding the front and back directions, Fig. 2 is used as a reference, with the upper side of Fig. 2 being the front side and the lower side being the back side. Also, regarding the up and down directions, in Figs. 2 to 5, the Y direction is described as the up and down direction with reference to the seat back board 5, and in Figs. 6 to 12, the Z direction is described as the up and down direction with reference to the forming device 40. Furthermore, for a plurality of identical parts, one part may be labeled with a reference numeral, and the reference numeral may be omitted for other parts.

[0032] As shown in the perspective view of FIG. 2, the seat back board 5 generally has a substantially rectangular shallow dish shape. The seat back board 5 is configured to include a plate-like base material 10 and a resin part 20 (described later) provided at a predetermined part of the base material 10. Hereinafter, each part will be described in detail.

[0033] The base material 10 has a shape in which three sides of the peripheral edge of a flat substantially rectangular plate-like body are bent so as to rise obliquely toward the back side and the outside. Hereinafter, the flat central part of the base material 10, which is the main part of the seat back board 5, is referred to as the main body part 11, and the part that rises by being bent from the main body part 11 is referred to as the rising part 15.

[0034] The main body part 11 has a plate shape that is rectangular in plan view. The dimension of the main body part 11 in the vertical direction (Y direction) is made larger than the dimension in the horizontal direction (X direction). As described above, the rising part 15 is provided so as to rise from three sides of the peripheral edge of the main body part 11.

[0035] Specifically, as shown in FIG. 5, on three sides of the peripheral edge of the main body part 11, there is a thin part 13 that is thinner than the plate thickness of the main body part 11 due to a stepped part 12 provided so as to crush the surface 10A (the upper surface in FIG. 5) side of the base material 10. The thin part 13 is bent toward the back side at a position slightly separated from the main body part 11, thereby raising the rising part 15. That is, a stepped part is formed on the surface 10A side of the base material 10 at the boundary part (referred to as the boundary part 16) between the main body part 11 and the rising part 15. Hereinafter, the stepped part of the thin part 13 that extends along the main body part 11 is referred to as the connecting part 14. The rising part 15 rises obliquely downward in FIG. 5 from the main body part 11 via the connecting part 14.

[0036] As described above, the boundary portion 16 between the main body portion 11 and the standing portion 15 has a stepped outer surface (the surface 10A of the base material 10). In other words, on the outer surface of the boundary portion 16, a concave portion 17 is formed which is recessed in a concave shape from a virtual cross-sectional arc-shaped curved surface connecting the surface 10A of the main body portion 11 and the surface 10A of the standing portion 15. The concave portion 17 is a space portion formed between the stepped portion 12 and the connecting portion 14. This concave portion 17 extends over the entire boundary portion 16. That is, the concave portion 17 extends in a substantially U-shaped form in plan view along the boundary portion 16.

[0037] On the other hand, the back surface 10B (the lower surface in FIG. 5) of the connecting portion 14 is arranged slightly below the back surface 10B of the main body portion 11. That is, the inner surface of the boundary portion 16 is also stepped by the connecting portion 14. Note that the stepped portion 18 on the inner surface of the boundary portion 16 has a shallower step shape than the stepped portion 12 on the outer surface of the boundary portion 16.

[0038] The above-described base material 10 is supposed to contain fibers and a thermoplastic resin. As the fibers contained in the base material 10, for example, kenaf fibers are used, but the type of fibers is not limited to this. As the fibers used for the base material 10, wood fibers, thermoplastic resin fibers, glass fibers, carbon fibers, etc. may be used. Also, in the base material 10, the fibers are bound by a thermoplastic resin as a binder. Examples of the thermoplastic resin as a binder used for the base material 10 can include polyester-based resins such as polypropylene and polyethylene.

[0039] At a predetermined position of the base material 10, a resin portion 20 made of a thermoplastic resin is provided. The resin portion 20 includes a resin reinforcing portion 21 that covers the entire back surface 10B (inner surface) of the standing portion 15, a bent portion forming portion 22 that fills the above-described concave portion 17, a clip seat (an example of a molded body) 23 that is provided integrally with the main body portion 11 adjacent to the standing portion 15 on the back surface 10B of the main body portion 11, and ribs (first rib 24, second rib 25) described later provided on the back surface 10B of the base material 10 (see FIGS. 2 to 5).

[0040] Starting from the clip seat 23, the clip seat 23 is formed in a shape protruding from the back surface 10B of the main body portion 11 of the base material 10. The clip seat 23 has a semi-circular shape in plan view (see Fig. 3), and clips can be fitted into it from the center of the main body portion 11 towards the outside. The clip seat 23 is formed of, for example, polypropylene which is a thermoplastic resin.

[0041] As described above, the bending portion forming portion 22 extends in a substantially U-shaped form in plan view along the boundary portion 16 of the seat back board 5 in a manner of filling the inside of the recess 17 (see Fig. 2). As shown in Fig. 5, the bending portion forming portion 22 is filled in a state of bulging from the recess 17, and in this embodiment, the curvature of its outer surface is defined. The bending portion forming portion 22 is formed of, for example, polypropylene which is a thermoplastic resin.

[0042] As described above, the resin reinforcing portion 21 is provided so as to cover the entire back surface (an example of the inner surface) 10B of the standing portion 15. As shown in Fig. 5, this resin reinforcing portion 21 covers the connecting portion 14 on the back surface 10B of the base material 10, and its thickness is set so that the thickness combined with the plate thickness of the standing portion 15 is equal to the plate thickness of the main body portion 11. Due to this resin reinforcing portion 21, the strength of the standing portion 15 is enhanced. The resin reinforcing portion 21 is formed of, for example, polypropylene which is a thermoplastic resin.

[0043] As described above, a plurality of the first ribs 24 are provided in a form connecting between the resin reinforcing portion 21 and the end portion of the back surface 10B of the main body portion 11 (see Fig. 4). As will be described later, the first rib 24 is formed by cooling the molten resin filled in the first runner 64 provided in the mold 50 for flowing the molten resin (the trace of the first runner 64). The end portion of the first rib 24 on the main body portion 11 side is a portion continuous with the gate 42 of the injection device 41 described later.

[0044] One of the second ribs 25 is provided in a form that connects between the clip seat 23 and the end of the back surface 10B of the main body 11 (see FIG. 3). The second rib 25 is formed by cooling the molten resin filled in a second runner (not shown) provided in the mold 50 for allowing the molten resin to flow when forming the clip seat 23 (the trace of the second runner). The end side of the main body 11 of the second rib 25 is connected to the gate 42 of the injection device 41 described later.

[0045] These first rib 24 and second rib 25 are formed of, for example, polypropylene which is a thermoplastic resin.

[0046] The configuration of the seat back board 5 is as described above. Subsequently, a manufacturing apparatus for manufacturing the seat back board 5 will be described. The manufacturing apparatus for the seat back board 5 is roughly composed of a press mold 30 that presses and manufactures a pre-board 10P while heating a fiber mat 10F made of vegetable fiber and thermoplastic resin, and a molding device 40 that press-molds the pre-board 10P into a product shape.

[0047] The press mold 30 shown in FIG. 6 is configured to be able to close and open the mold with respect to each other by a drive device (for example, an electric motor, an air cylinder, a hydraulic cylinder, etc.) provided on one of the upper mold 31 and the lower mold 35. The press mold 30 (press plate, hot plate) has a built-in heating means such as a heater that generates heat by energization. Thereby, the press mold 30 is configured to be heatable to a predetermined temperature, and can heat and press the fiber mat 10F. Such a heater may be provided on only one of the upper mold 31 and the lower mold 35.

[0048] In this embodiment, protruding portions 32 that protrude toward the lower mold 35 are provided at the peripheral edges of three sides of the rectangular mold surface of the upper mold 31. On the other hand, the mold surface of the lower mold 35 is flat. With such a configuration, as will be described later, the peripheral edges of three sides of the rectangular pre-board 10P pressed by the press mold 30 are formed into thin-wall portions 13 that are thinner than the thick-wall portion 11P formed by the main body portion of the pre-board 10P (see FIG. 7).

[0049] As shown in FIG. 8, for example, the molding apparatus 40 includes an injection apparatus 41 and a molding die 50 (an upper die 51 and a lower die 61). The injection apparatus 41 is, for example, of a screw type and is provided in the lower die 61 in this embodiment.

[0050] The upper die 51 is a movable die that can be moved relative to the lower die 61 (fixed die) by a driving device (for example, an electric motor, an air cylinder, a hydraulic cylinder, etc.) not shown. By moving the upper die 51 closer to and away from the lower die 61 in the vertical direction, the upper die 51 and the lower die 61 can be closed and opened.

[0051] The lower die 61 has a shape in which the mold surface 62, which is the surface facing the upper die 51, protrudes toward the upper die 51. Further, the upper die 51 has a shape in which the mold surface 52, which is the surface facing the lower die 61, is recessed corresponding to the shape of the lower die 61.

[0052] As shown in FIG. 10 and the like, in the closed state where the upper die 51 and the lower die 61 are closed, the upper die 51 is disposed opposite to the lower die 61 with a distance equal to the plate thickness of the main body portion 11. Thereby, in the closed state, a base material molding space S1 for molding the base material 10 is formed between the upper die 51 and the lower die 61. Thus, when the pre-board 10P is pressed by the upper die 51 and the lower die 61, the pre-board 10P is shaped into a shape corresponding to the shape of the base material molding space S1, and the base material 10 having the main body portion 11 and the standing portion 15 described above is formed.

[0053] In this embodiment, the separation distance between the upper die 51 and the lower die 61 in the die-closed state of the portion corresponding to the main body portion 11 of the base material 10 is made equal to the separation distance of the portion corresponding to the standing portion 15. Further, the separation distance between the upper die 51 and the lower die 61 in the die-closed state is made smaller than the plate thickness of the thick portion 11P of the prepreg 10P and larger than the plate thickness of the thin portion 13. In this embodiment, the separation distance between the upper die 51 and the lower die 61 in the die-closed state is set to be 3 mm.

[0054] The peripheral end portion of the above-described base material forming space S1 is closed by overlapping an upper closing surface 52C that extends vertically downward from the mold surface 52 of the upper die 51 and a lower closing surface 62C that extends vertically downward from the mold surface 62 of the lower die 61. Further, at the lower end of the upper closing surface 52C, a shear blade (not shown) for cutting the prepreg 10P into a predetermined size when pressing the prepreg 10P (when closing the die) is provided. In the die-closing process of the upper die 51 and the lower die 61, the shear blade abuts against the upper surface of the prepreg 10P, presses and deforms the prepreg 10P downward, and cuts the terminal of the prepreg 10P as it slides along the lower closing surface 62C (see FIG. 10).

[0055] Note that a clip seat forming recess (not shown) for forming the above-described clip seat 23 is recessed in the mold surface 62 of the lower die 61 so as to open to the outside. Further, the lower die 61 is provided with a slide mechanism (not shown) for forming the clip seat 23.

[0056] Further, a first runner 64 that opens to the outside and a second runner (not shown) are formed in the mold surface 62 of the lower die 61.

[0057] The first runner 64 is provided in plural numbers in a form of being notched in a groove shape extending in a direction orthogonal to the circumferential direction of the mold surface 62 along an inclined surface 62B that obliquely extends downward from a portion of the mold surface 62 of the lower mold 61 that is close to an end of a horizontal surface 62A that protrudes upward and extends in the horizontal direction (see FIG. 8). A gate 42, which is an injection port through which resin from the injection device 41 is injected, is provided at the upper end portion (the end portion on the horizontal surface 62A side) of the first runner 64.

[0058] Also, a second runner (not shown) is formed in a shape of notching the horizontal surface 62A of the mold surface 62 of the lower mold 61 in a groove shape and extends in a direction orthogonal to the circumferential direction of the mold surface 62. This second runner is formed so as to connect a clip seat forming recess (not shown) provided in the lower mold 61 for forming the above-described clip seat 23 and the gate 42 of the injection device 41 provided at the end of the horizontal surface 62A.

[0059] Next, an example of a method for manufacturing the seat back board 5 that constitutes the vehicle seat 1 will be described. The method for manufacturing the seat back board 5 of the present embodiment includes a pre-board forming step of forming a pre-board 10P, a press forming step of pressing the pre-board 10P with an upper mold 51 and a lower mold 61 to form a base material 10, and a resin portion forming step (an example of a resin reinforcing portion forming step, a resin filling step, and a molded body forming step) of injecting molten resin into the first runner 64 and the second runner to form a resin reinforcing portion 21 on the back surface 10B of the standing upper portion 15, filling the recess 17, and forming the clip seat 23 in a form of being joined to the base material 10, which are executed in order.

[0060] <Pre-board Forming Step> In the pre-board forming process, as shown in FIGS. 6 and 7, a fiber mat 10F composed of fibers and a thermoplastic resin is heated and pressed by a press mold 30. As a result, the fiber mat 10F is compressed, and a flat plate-shaped thick portion 11P and a thin portion 13 provided at a part of the peripheral edge of the thick portion 11P and thinner than the thick portion 11P are formed. Also, the thermoplastic resin contained in the fiber mat 10F melts and mixes at the contact surfaces with each other. Then, the thermoplastic resin contained in the fiber mat 10F cools and solidifies, thereby forming the pre-board 10P. Thereafter, the pre-board 10P is cut into a predetermined dimension and shape as necessary.

[0061] <Press forming process> Next, the pre-board 10P at room temperature (in a non-heated state) is placed while being positioned with respect to the lower mold 61. The pre-board 10P is placed on the lower mold 61 such that the surface provided with a stepped portion 12P between the thick portion 11P and the thin portion 13 becomes the upper surface (surface 10A), and the flat surface becomes the lower surface (back surface 10B) (see FIG. 8). Also, it is placed on the lower mold 61 such that the stepped portion 12P is located slightly on the outer peripheral side (the left side in FIG. 8) from the horizontal plane 62A of the lower mold 61 (see FIG. 9).

[0062] Subsequently, by closing the mold of the forming mold 50, the pre-board 10P is shaped by the mold surfaces 52 and 62 of the upper mold 51 and the lower mold 61 (see FIGS. 9 and 10). More specifically, in the process where the upper mold 51 descends and gradually approaches the lower mold 61, as shown in FIG. 9, first, the lower end of the upper closing surface 52C of the upper mold 51 abuts near the end of the thin portion 13 of the pre-board 10P and presses it toward the lower mold 61, thereby pushing down the thin portion 13 of the pre-board 10P. At this time, since the pre-board 10P is not heated and is in a hard state that is difficult to extend, but the thin portion 13 has lower rigidity compared to the thick portion 11P, it can be pushed down without breaking. And after the thin portion 13 is sandwiched between the upper mold 51 and the lower mold 61, the upper closing surface 52C cuts the terminal of the thin portion 13 with a shear blade provided at its lower end while sliding with the lower closing surface 62C to form the base material forming space S1 (see FIG. 10).

[0063] In this mold-closed state, the thick plate-shaped portion 11P is press-formed into a predetermined shape. On the other hand, as shown in FIG. 10, the thin portion 13 abuts against the upper mold 51 at a position where the proximal end side thereof is separated from the main body portion 11 and is bent. That is, the thin portion 13 has a connecting portion 14 formed on the proximal end side, and the distal end side of the connecting portion 14 is bent obliquely downward in a shape that bends from the main body portion 11 via the connecting portion 14 while abutting against the mold surface 52 (inclined surface 52B) of the upper mold 51, forming a rising portion 15 that rises upward.

[0064] In this mold-closed state, the thin portion 13 rises from the main body portion 11 via the connecting portion 14 in a form having a space between it and the mold surface 62 (inclined surface 62B) of the lower mold 61. This space is a resin reinforcing portion molding space S2 for molding the resin reinforcing portion 21. Also in this mold-closed state, a substantially rhombus-shaped bending portion forming portion molding space S3 for molding the bending portion forming portion 22 is formed between the concave portion 17 of the base material 10 and the mold surface 52 of the upper mold 51.

[0065] Furthermore, in a state where the molding die 50 is mold-closed, a clip seat molding space (not shown) is formed between the clip seat molding recess (not shown) of the lower mold 61 described above and the base material 10.

[0066] Note that in the process in which the thin portion 13 of the pre-board 10P is pressed and bent as described above, since the shear blade provided at the lower end of the upper closing surface 52C of the upper mold 51 slidably contacts the surface 10A of the thin portion 13 so as to scrape it, the surface 10A of the thin portion 13 (pre-board 10P) may be damaged.

[0067] <Resin portion molding process> After the mold is closed, a resin part forming process (an example of a resin reinforcing part forming process, a resin filling process, and a molded body forming process) is carried out. In the resin part forming process, as shown in FIG. 11, in a state where the base material 10 is shaped by the mold surface 52 of the upper mold 51 and the mold surface 62 of the lower mold 61 (the mold closed state), the injection device 41 injects molten resin into each runner and fills each space. Specifically, the molten resin injected from the gate 42 into the first runner 64 is injected into the resin reinforcing part forming space S2, and the molten resin injected into the second runner is injected into the resin reinforcing part forming space S2 and the clip seat forming space.

[0068] At this time, even if the surface 10A of the standing part 15 of the base material 10 is scraped and damaged or deformed by the shear blade during press forming, the standing part 15 is pressed against the mold surface 52 of the upper mold 51 by the pressure of the molten resin filled in the resin reinforcing part forming space S2, and the shape is maintained and reinforced by the resin reinforcing part 21.

[0069] In addition, the molten resin injected into the resin reinforcing part forming space S2 soaks into the base material 10, becomes thin, and flows and is filled into the bent part forming part forming space S3 from the connecting part 14 which is thin. That is, the molten resin is supplied into the concave part 17 from the back surface 10B side of the base material 10, and the bent part forming part 22 is formed.

[0070] In this way, the first runner 64, the second runner, the resin reinforcing part forming space S2, the clip seat forming space, and the bent part forming part forming space S3 are filled with molten resin.

[0071] Thereafter, the molten resin filled in these is cooled, and the sheet backboard 5 composed of the base material 10 and the resin part 20 is completed. After the thermoplastic resin (resin part 20) contained in the sheet backboard 5 is cooled and solidified, the upper mold 51 and the lower mold 61 are opened, and the sheet backboard 5 is demolded (see FIG. 12). Thereby, the manufacture of the sheet backboard 5 is completed.

[0072] <Verification of the amount of thinning of the thin part and the change in the displacement amount of the sheet backboard> The standing upper part with the resin reinforcing part of the seat back board 5 of the above embodiment was pressed with a force of 70 N in the direction along the main body part 11 from the inner surface (back surface 10B), and the change in the displacement amount (mm / 70 N) of the standing upper part with the resin reinforcing part was measured when the crushing amount (thickness of the thin part) during pre-board forming was changed. The plate thickness of the standing upper part with the resin reinforcing part was adjusted to be the same as the plate thickness (3 mm) of the main body part. Also, the width dimension of the standing upper part was set to 10 mm. The measurement results are shown in the graph of Fig. 13.

[0073] As shown in the graph, in the case of a conventional seat back board without a thin part (a seat back board without a resin reinforcing part), the displacement amount was 1 mm / 70 N, whereas in the case of those with a thin part 13 provided (those with a resin reinforcing part 21 provided on the standing upper part 15), the displacement amount was generally 0.7 mm / 70 N or less. It became clear that the rigidity of the standing part was improved by making the standing upper part with the resin reinforcing part.

[0074] Also, as the crushing amount increases, the rigidity of the thin part 13 decreases and it becomes easier to bend, so damage by the shear blade is reduced. However, when the crushing amount is made larger than 2 mm (when the thin part is made 1 mm or less), the thin part 13 becomes too soft and may get caught on the shear blade and break relatively easily. Therefore, it is desirable that the crushing amount be 2 mm or less.

[0075] Subsequently, the functions and effects of this embodiment will be described. The seat back board 5 of this embodiment includes a main body part 11 composed of a plate-like main body part containing fibers and a thermoplastic resin, and a standing upper part 15 formed by bending at least a part of the peripheral edge of the plate-like body and rising from the main body part 11. On the inner surface (back surface 10B) of the standing upper part 15 of the base material 10, a resin reinforcing part 21 made of a thermoplastic resin and covering the entire inner surface to reinforce the strength of the standing upper part 15 is provided.

[0076] When manufacturing the seat back board 5, for example, when at least a part of the peripheral edge of the plate-like body is bent by press molding or the like to form the upright portion 15, the periphery of the tip portion may be damaged by the shear blade provided on the molding die 50 for cutting the tip portion, and the plate thickness of the damaged portion may become thin. According to the above configuration, even in such a case, the rigidity of the upright portion 15 can be ensured by the resin reinforcing portion 21. In particular, when the plate material to be molded is hard and difficult to deform, such as when heating before press molding is omitted for cost reduction or the like, it is likely to be damaged by the shear blade, so the effect of this configuration can be remarkable.

[0077] A recess 17 that departs from the outer surface (surface 10A) is provided on the outer surface of the boundary portion 16, which is the boundary between the main body portion 11 and the upright portion 15, and the recess 17 may be filled with a thermoplastic resin.

[0078] According to the above configuration, the strength of the boundary portion 16 with a reduced plate thickness due to the recess 17 can be improved by the thermoplastic resin filled in the recess 17. Also, the bent shape of the seat back board 5 can be maintained by the thermoplastic resin filled in the recess 17. Furthermore, since the outer surface of the boundary portion 16 is composed of the thermoplastic resin, the accuracy of the curvature of the outer surface of the boundary portion 16 (the bent portion) can be improved.

[0079] The resin filled in the recess 17 is composed of the same thermoplastic resin as the resin constituting the resin reinforcing portion 21.

[0080] According to the above configuration, when manufacturing the seat back board 5, the molten resin for forming the resin reinforcing portion 21 can be injected into the recess 17 at the same time as injecting the molten resin.

[0081] The thickness of the upright upper part 15 is formed to be thinner than the thickness of the main body part 11. According to such a configuration, by adjusting the thickness of the resin reinforcing part 21 that covers the inner surface of the upright upper part 15, the total thickness of the upright upper part 15 and the resin reinforcing part 21 can be made equal to the thickness of the main body part 11. Further, when the base material 10 is press-molded, if the thickness of the part that becomes the upright upper part 15 is thin, that part is likely to bend, and damage by the shear blade can be reduced. Thus, the surface 10A of the seat back board 5 (upright upper part 15) can be beautifully formed.

[0082] The boundary part 16 is arranged at the upper end of the seat back board 5 with the outer surface of the boundary part 16 facing the inside of the passenger compartment in a state where the seat back board 5 is attached to the vehicle.

[0083] In the seat back board 5 of the vehicle seat 1, in order to ensure safety during a collision, the curvature of the bent part (boundary part 16) arranged at the upper end of the seat back board 5 is strictly defined. In particular, when the plate material to be formed is hard and difficult to deform, such as when heating before press molding is omitted for cost reduction or the like, it is difficult to obtain the accuracy of the curvature of the bent part, so the effect of this configuration can be remarkable.

[0084] A clip seat 23 formed of a thermoplastic resin is integrally provided, and the clip seat 23 is composed of the same thermoplastic resin as the resin constituting the resin reinforcing part 21.

[0085] According to the above configuration, when manufacturing the seat back board 5, the clip seat 23 provided in the main body part 11 can be injection-molded simultaneously with injecting the molten resin for molding the resin reinforcing part 21.

[0086] Moreover, the manufacturing method of the seat back board 5 of the present embodiment includes a pre-board forming step of thermally pressing a fiber mat 10F containing fibers and a thermoplastic resin by a press mold 30 to form a pre-board 10P, and pressing the pre-board 10P by a molding die 50 at a temperature at which the thermoplastic resin does not melt to form a base material 10 having a main body portion 11 composed of a plate-like main body portion and a standing portion 15 rising from the main body portion 11 by bending at least a part of the peripheral edge portion of the plate-like body. And a resin reinforcing portion forming step of injecting a thermoplastic resin onto the inner surface of the standing portion 15 to form a resin reinforcing portion 21 that covers the entire inner surface and reinforces the strength of the standing portion 15 are executed in order.

[0087] According to the above manufacturing method, even when the pre-board 10P is not heated during the press molding of the seat back board 5 and the surface 10A of the standing portion 15 is scraped by a shear blade for terminal cutting provided on the molding die 50 and the rigidity is impaired, the resin reinforcing portion 21 can increase the rigidity of the standing portion 15.

[0088] In the pre-board forming step, a thin portion 13 having a reduced thickness may be formed at at least a part of the peripheral edge portion of the pre-board 10P, and in the press molding step, the standing portion 15 formed by raising the thin portion 13 from the main body portion 11 by bending the thin portion 13 may be formed.

[0089] According to the above configuration, by adjusting the thickness of the resin reinforcing portion 21, the total thickness of the standing portion 15 and the resin reinforcing portion 21 can be made equal to the thickness of the main body portion 11. Further, since the thin portion 13 is easily bent, damage by the shear blade during press molding can be reduced. Thus, the surface 10A of the seat back board 5 (standing portion 15) can be beautifully formed.

[0090] In the pre-board forming process, by pressing the fiber mat 10F so as to have a stepped portion 12 forming a step shape on one surface, a thin-walled portion 13 with a thin outer peripheral edge of the stepped portion 12 is formed. In the press forming process, by bending the stepped portion 12 so that the stepped portion 12 is on the outside at a position separated from the thin-walled portion 13, a concave portion 17 is formed on the outer surface of the boundary portion 16, which is the boundary between the main body portion 11 and the standing portion 15, and is composed of a part of the stepped portion 12 and the thin-walled portion 13 and recesses from the outer surface. Then, a resin filling process of filling the concave portion 17 with a thermoplastic resin is executed in a state where the mold 50 is closed.

[0091] According to the above configuration, even when the pre-board 10P is not heated during the press forming of the seat back board 5, compared with the case where the thin-walled portion 13 is not formed, the peripheral edge portion (thin-walled portion 13) of the pre-board 10P can be easily bent to form the concave portion 17 for filling the thermoplastic resin at the boundary portion 16. Further, by filling the thermoplastic resin into the concave portion 17, the strength of the boundary portion 16 can be improved, and the bent shape of the seat back board 5 can be maintained. Furthermore, since the thermoplastic resin filled in the concave portion 17 is injection molded in the mold 50, the accuracy of the curvature of the outer surface of the boundary portion 16 (bent portion) can be improved.

[0092] The resin filling process is executed simultaneously with the resin reinforcement portion forming process, and the same thermoplastic resin that constitutes the resin reinforcement portion 21 is filled into the concave portion 17 from the inside of the boundary portion 16.

[0093] According to the above manufacturing method, no trace of the gate 42 is formed on the outer periphery of the bent portion (the boundary portion between the main body portion 11 and the standing portion 15) of the seat back board 5, and the outer periphery can be beautifully formed.

[0094] The molded body forming process includes injection molding a clip seat 23 made of the same thermoplastic resin as the resin constituting the resin reinforcement portion 21, and the molded body forming process is executed simultaneously with the resin reinforcement portion forming process.

[0095] According to the above manufacturing method, the clip seat 23 can be injection molded simultaneously with filling the recess 17.

[0096] <Other Embodiments> The technology disclosed in this specification is not limited to the embodiments described by the above description and drawings. For example, the following embodiments are also included in the technical scope.

[0097] (1) In the above embodiment, the configuration of providing the standing upper part 15 on three sides of the rectangular main body part 11 is shown. However, the standing upper part may be provided over the entire outer peripheral edge of the main body part, or the configuration of being provided on one side or two sides is also included in the technical scope.

[0098] (2) In the above embodiment, the configuration of providing the recess 17 and the bending part forming part 22 on the seat back board 5 is shown. However, these do not necessarily have to be provided.

[0099] (3) In the above embodiment, the configuration of providing the clip seat 23 on the back surface 10B of the main body part 11 is shown. However, a molded body other than the clip seat may be provided. Also, the configuration where no molded body is provided is included in the technical scope.

[0100] (4) In the above embodiment, the form of configuring the bending part forming part 22 and the clip seat 23 with the same thermoplastic resin as the resin reinforcing part 21 is shown. However, these may be configured with different thermoplastic resins.

[0101] (5) The technology disclosed in this specification can also be applied to other than the seat back board 5.

Explanation of Reference Numerals

[0102] 5: Seat back board (molded structure), 10: Base material, 10B: Back surface (inner surface), 10F: Fiber mat (mat), 10P: Pre-board, 11: Main body part, 12: Step part, 13: Thin part, 14: Connecting part, 15: Upright upper part, 16: Boundary part, 17: Recessed part, 18: Step part, 20: Resin part, 21: Resin reinforcement part, 22: Bending part forming part, 23: Clip seat (molded body), 30: Press mold, 50: Mold, S1: Base material molding space, S2: Resin reinforcement part molding space, S3: Bending part forming part molding space

Claims

1. A main body portion composed of a plate-like main part including fibers and a thermoplastic resin, and an upright portion formed by bending at least a part of the peripheral edge of the plate-like body and rising from the main body portion. On the inner surface of the upright portion of the base material, a resin reinforcing portion made of a thermoplastic resin is provided to cover the entire inner surface and reinforce the strength of the upright portion. A recess that is recessed from the outer surface is provided on the outer surface of a boundary portion that is a boundary between the main body portion and the upright portion. A molded structure in which the recess is filled with a thermoplastic resin.

2. The molded structure according to claim 1, wherein the resin filled in the recess is composed of the same thermoplastic resin as the resin constituting the resin reinforcing portion.

3. The molded structure according to claim 1 or claim 2, wherein the plate thickness of the upright portion is formed thinner than the plate thickness of the main body portion.

4. The molded structure is a seat back board that constitutes the back surface of a vehicle seat. A boundary portion that is a boundary between the main body portion and the upright portion is arranged at the upper end of the seat back board with the outer surface of the boundary portion facing the inside of the vehicle compartment when the seat back board is attached to the vehicle. The molded structure according to any one of claims 1 to 3.

5. The molded structure according to any one of claims 1 to 4, wherein a molded body formed of a thermoplastic resin is integrally provided, and the molded body is composed of the same thermoplastic resin as the resin constituting the resin reinforcing portion.

6. A pre-board forming step of hot-pressing a mat containing fibers and a thermoplastic resin with a press mold to form a pre-board. A press molding step of pressing the pre-board with a molding die at a temperature at which the thermoplastic resin does not melt to form a base material having a main body portion composed of a plate-like main part and an upright portion rising from the main body portion by bending at least a part of the peripheral edge of the plate-like body. A resin reinforcing portion forming step of injecting a thermoplastic resin onto the inner surface of the upright portion to form a resin reinforcing portion that covers the entire inner surface and reinforces the strength of the upright portion. A manufacturing method of the molded structure that sequentially executes the steps.

7. In the pre-board forming step, a thin portion having a reduced thickness is formed at least in a part of the peripheral edge of the pre-board. The manufacturing method of the molded structure according to claim 6, wherein in the press molding step, the standing portion formed by raising the thin-walled portion from the main body portion by bending the thin-walled portion is molded.

8. In the pre-board molding step, by pressing the mat so as to have a stepped portion having a stepped shape on one surface, the thin-walled portion having a thin outer peripheral edge portion of the stepped portion is molded. In the press molding step, by bending the thin-walled portion at a position separated from the stepped portion so that the stepped portion is on the outside, a recess formed by the stepped portion and a part of the thin-walled portion is formed on the outer surface of the boundary portion which is the boundary between the main body portion and the standing portion and is recessed from the outer surface. Thereafter, the resin filling step of filling the recess with a thermoplastic resin is executed in a state where the mold is closed, according to the manufacturing method of the molded structure according to claim 7.

9. The resin filling step is executed simultaneously with the resin reinforcing portion molding step. The manufacturing method of the molded structure according to claim 8, wherein the same thermoplastic resin as the resin constituting the resin reinforcing portion is filled into the recess from the inside of the boundary portion.

10. Including a molded body molding step of injection molding a molded body made of the same thermoplastic resin as the resin constituting the resin reinforcing portion. The manufacturing method of the molded structure according to any one of claims 6 to 9, wherein the molded body molding step is executed simultaneously with the resin reinforcing portion molding step.

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