Rib structure and mounting structure

Abstract

To provide a novel rib structure that can exert excellent reinforcing effect while securing light weight, and a fitting structure in which the rib structure is attached to a body to be reinforced.SOLUTION: A rib structure 1 is used for reinforcing a body to be reinforced. The rib structure 1 includes a rib body 2. The rib body 2 is made of foaming resin. The thickness of the rib body 2 can be increased by foaming compared to a resin structure made of non-foaming resin of the same weight, and its strength can be improved. Further the rib body 2 has fixing surfaces 5 extending along a surface to be fixed of the body to be reinforced. Thus the rib structure 1 can be appropriately fixed onto the body to be reinforced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a rib structure and a mounting structure in which the rib structure is mounted on an object to be reinforced. [Background technology]

[0002] Recently, in the mobility field, such as automobiles, railways, and airplanes, as well as in the fields of building materials, infrastructure, and residential applications, there has been an increasing trend to replace relatively large steel or aluminum parts and metal casings with plastic parts and casings in order to realize a decarbonized society. It is expected that, in the future, methods for forming relatively large plastic parts and casings will be shaped by vacuum forming or heat pressing of plastic sheets. This is because forming methods such as vacuum forming and heat pressing have fewer limitations on mold size and equipment load than injection molding, making them suitable for producing plastic molded products of a single thickness.

[0003] For example, when a resin sheet is made of a thermoplastic resin, the resin sheet is formed relatively thin to ensure the formability of the sheet, and therefore, when the resin sheet becomes relatively large, it becomes difficult for the resin sheet to stand on its own, so that reinforcement by attaching a rib structure has been considered.

[0004] Japanese Patent No. 4208236 (Patent Document 1) discloses an automotive interior part consisting of a foamed resin base material formed by press-molding a foamed resin sheet into a predetermined shape, and resin ribs of a predetermined pattern integrated onto the back surface of the foamed resin base material.

[0005] Japanese Patent No. 3644933 (Patent Document 2) discloses a foam with a reinforced skin layer, which has a foam and a non-foamed reinforcing skin layer integrally molded with the foam.

[0006] Japanese Patent No. 6861001 (Patent Document 3) discloses a polyamide resin foam molded article whose mechanical properties are resistant to deterioration even in high-temperature environments and which has an excellent balance between sound absorption and heat dissipation.

[0007] "Development of a unique injection foam molding technology, 'RIC-FOAM'" (Non-Patent Document 1) discloses a foam molding technique that uses nitrogen, carbon dioxide, etc. as a foaming agent, and enables fine foam molding at lower gas pressures compared to conventional physical foam molding methods that use supercritical fluids. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4208236 [Patent Document 2] Patent No. 3644933 [Patent Document 3] Patent No. 6861001 [Non-patent literature]

[0009] [Non-Patent Document 1] Maxell Holdings, Ltd., "Development of proprietary injection foam molding technology 'RIC-FOAM'," online, October 19, 2017, Internet<URL:https: / / www.maxell.co.jp / news / pdf / maxellnews_20171019r.pdf> Summary of the Invention [Problem to be solved by the invention]

[0010] However, none of Patent Documents 1 to 3 and Non-Patent Document 1 discloses a rib structure made of foamed resin for reinforcing an object to be reinforced.

[0011] Therefore, an object of the present disclosure is to provide a new rib structure that can exhibit excellent reinforcing effects while ensuring light weight, and a mounting structure in which the rib structure is attached to an object to be reinforced. [Means for solving the problem]

[0012] In order to solve the above problems, the present disclosure provides the following solution. That is, the rib structure according to the present disclosure may be a rib structure for reinforcing an object to be reinforced. The rib structure may include a rib body having an attachment surface to be attached to the object to be reinforced. The rib body may be made of a foamed resin. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a new rib structure that can exhibit excellent reinforcing effects while ensuring light weight, and a mounting structure in which the rib structure is attached to an object to be reinforced. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an external perspective view showing the structure of a rib structure according to an embodiment. [Figure 2] FIG. 2 is a side view of the rib structure shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the rib structure shown in FIG. 1 taken along the line AA'. [Figure 4] FIG. 4 is a side view showing the structure of the mounting structure according to the embodiment. [Figure 5] 5A to 5C are cross-sectional views showing a method for manufacturing the rib structure shown in FIG. [Figure 6] 6A to 6C are cross-sectional views showing a method for manufacturing the rib structure shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] The rib structure according to the present disclosure may be a rib structure for reinforcing an object to be reinforced. The rib structure may include a rib body having a fastening surface to be fastened to the object to be reinforced. The rib body may be made of a foamed resin.

[0016] The rib body made of foamed resin can be thicker than a resin structure made of non-foamed resin of the same weight, thereby improving the rigidity of the rib body. This allows the rib structure to exhibit excellent reinforcing effect while maintaining light weight. Furthermore, the rib structure has a fixing surface, which allows it to be properly fixed to the object to be reinforced.

[0017] The rib main body may include a semi-cylindrical portion and a flange extending radially outward from a side edge of the semi-cylindrical portion. The flange may have a fixing surface that is fixed to the object to be reinforced. The fixing surface provided on the flange allows the rib to be properly fixed to the object to be reinforced, and the hollow space between the inner surface of the semi-cylindrical portion and the object to be reinforced allows for weight reduction. Furthermore, when an external force is applied to the object to be reinforced, the semi-cylindrical portion bends, preventing the fixing surface from peeling off from the object to be reinforced, thereby maintaining the reinforcing effect.

[0018] The fixing surface may have protrusions that protrude toward the object to be reinforced. When the fixing surface of the rib structure is welded to the object to be reinforced, the protrusions on the fixing surface also melt. This reduces or eliminates the protrusion height, making it possible to confirm that the rib structure has been sufficiently fixed to the object to be reinforced.

[0019] The rib body may have a porosity of 30 to 80% and a thickness a that is 1.5 to 6 times the average thickness t of the object to be reinforced. By appropriately setting the porosity and thickness of the rib body in this way, it is possible to achieve a superior reinforcing effect while maintaining light weight.

[0020] The rib body may be made of either an engineering plastic or a super engineering plastic, which can improve the heat resistance and strength of the rib structure and provide an even more excellent reinforcing effect.

[0021] The mounting structure according to the present disclosure may include a rib structure and a reinforced body having a surface to which the rib structure is attached. The rib structure may be attached to the reinforced body by fixing the fixing surface of the rib structure to the surface to which the rib structure is attached. As described above, the rib structure exhibits an excellent reinforcing effect while ensuring light weight. This allows the mounting structure, including the reinforced body, to be lighter and stronger as a whole.

[0022] The object to be reinforced may be made of foamed resin, which allows the weight of the reinforcing body to be reduced, the load on the rib structure reinforcing the object to be reinforced to be reduced, and the weight of the mounting structure to be reduced.

[0023] Hereinafter, an embodiment of a rib structure 1 and a mounting structure 10 including the rib structure 1 of the present disclosure will be specifically described with reference to Figures 1 to 4. Note that identical or corresponding components in the figures are given the same reference numerals, and the same description will not be repeated. Note that, to make the description easier to understand, the drawings referred to below show simplified or schematic configurations, and some components are omitted.

[0024] As shown in FIGS. 1 to 3, the rib structure 1 has a rib body 2 and a protrusion 6.

[0025] The rib main body 2 is made of foamed resin obtained by foaming a thermoplastic resin. The resin material for the rib main body 2 can be selected from various resin materials such as general-purpose plastics, engineering plastics, and super-engineering plastics. However, from the viewpoint of improving heat resistance and strength and widening the range of applications, it is preferable to use engineering plastics and super-engineering plastics.

[0026] The engineering plastic that can be used in the present disclosure contains at least one resin selected from the group consisting of polyamide (PA), polycarbonate (PC), polyacetal (POM), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), glass fiber reinforced polyethylene terephthalate (GF-PET), ultra-high molecular weight polyethylene (UHPE), and syndiotactic polystyrene (SPS).

[0027] The super engineering plastic that can be used in the present disclosure contains at least one resin selected from the group consisting of polyphenylene sulfide (PPS), polysulfone (PSF), polyethersulfone (PES), polyarylate (PAR), polyamideimide (PAI), thermoplastic polyimide (PI), polyetherimide (PEI), and liquid crystal polymer (LCP).

[0028] The resin material of the rib body 2 may be any of various alloys or copolymers of the above-mentioned engineering plastics and super engineering plastics, and may contain an organic or inorganic filler. In particular, from the viewpoints of formability, cost, and low-temperature impact resistance, it is preferable to contain polycarbonate, and from the viewpoints of strength, cost, and foamability, it is preferable to contain polyphenylene sulfide.

[0029] As described above, the rib body 2 is made of foamed resin. The rib body 2 has a thickness 1.5 to 7 times the thickness of the pre-foamed molded body 200 (see FIG. 5). The foaming method can be selected from, for example, chemical foaming, physical foaming, and bead foaming, but physical foaming is preferred. This is because physical foaming has a low environmental impact. Among these, foam molding methods using a supercritical fluid such as carbon dioxide or nitrogen as a foaming agent are preferred, from the viewpoint of being able to foam engineering plastics and super-engineering plastics with excellent heat resistance or strength. Furthermore, it is more preferable to use "RIC-FOAM" (Non-Patent Document 1 mentioned above), a physical foam molding method that places a low load on the equipment and allows low-pressure foaming. A method for manufacturing the rib structure 1 will be described later with reference to FIGS. 5 and 6.

[0030] In this way, the thickness of the rib main body 2 can be increased without changing the weight, and the rigidity of the rib main body can be improved. This allows the rib structure 1 to exhibit an excellent reinforcing effect while maintaining its light weight. Furthermore, by forming the rib main body 2 from at least one of an engineering plastic and a super engineering plastic, the heat resistance and strength of the rib structure 1 can be improved, and an even more excellent reinforcing effect can be exhibited.

[0031] The average cell diameter of the closed cells formed in the rib main body 2 is preferably 100 μm or less, from the viewpoint of maintaining the strength of the rib main body 2. The foam structure of the rib main body 2 is preferably closed-cell. The rib main body 2 has a porosity of 30 to 80%. If the foam structure is an interconnected porous structure or if the porosity is too high, the strength of the rib main body 2 may decrease. Therefore, from the viewpoint of maintaining the closed cells of the rib main body 2 and ensuring both lightness and rigidity, the expansion ratio (specific gravity reduction rate) of the rib main body 2 is preferably 1.2 times (17%) or more, preferably 1.5 times (33%) or more, more preferably 2.0 times (50%) or more, and is preferably 6 times (83%) or less, preferably 5 times (80%) or less, more preferably 3.5 times (71%) or less. The porosity is preferably 30% or more, preferably 50% or more, and 80% or less, preferably 70% or less. Here, the expansion ratio refers to the increase in thickness of the rib main body 2 due to the core back. That is, the expansion ratio is calculated by the formula {thickness a of the rib main body 2 / thickness of the provisionally formed body 20}. The porosity is calculated by dividing the increase in thickness of the rib main body 2 due to the core back by the thickness a of the rib main body 2. That is, the porosity is calculated by the formula {(thickness a of the rib main body 2-thickness of the provisionally formed body 20 / thickness a of the rib main body 2) × 100(%)}. As shown in FIG. 3, the thickness a of the rib main body 2 is the larger of thickness a1 and thickness a2. The thickness a1 is the thickness of the rib main body 2 at the center of the width w of the rib main body 2, and the thickness a2 is the larger of the thicknesses at both ends in the width direction of the rib main body 2 (in this embodiment, the tip ends of each flange 4 provided at both ends of the semi-cylindrical portion 3). The thickness of the provisionally formed body 20 is the thickness of the provisionally formed body before foaming, which corresponds to the position of thickness a.

[0032] As shown in FIGS. 1 to 3, the rib main body 2 has a semi-cylindrical portion 3 , a flange 4 and a fixing surface 5 .

[0033] The semi-cylindrical portion 3 is formed in a shape obtained by cutting a cylinder in the axial direction. In other words, the semi-cylindrical portion 3 is formed in a C-shape in cross section. The shape of the semi-cylindrical portion 3 is not limited to a shape obtained by cutting a cylinder, but may also be a shape obtained by cutting an elliptical cylinder or a polygonal cylinder in the axial direction, that is, a U-shape, a V-shape, or a U-shape in cross section.

[0034] The flanges 4 extend radially outward from both side edges of the semi-cylindrical portion 3. That is, the rib body 2 has two flanges 4 extending radially outward from the side edges of the semi-cylindrical portion 3. The flanges 4 may be formed to extend from the entire side edges of the semi-cylindrical portion 3, or may be formed to extend from only a portion of the side edges of the semi-cylindrical portion 3. The flanges 4 have a fixing surface 5.

[0035] The fixing surface 5 is formed on the lower surface of the flange 4, i.e., on the surface opposite the position of the semi-cylindrical portion 3 (lower in FIGS. 2 and 3 ). When the rib structure 1 is attached to the object to be reinforced 11 (described later), the fixing surface 5 faces the fixing surface 12 of the object to be reinforced 11 (see FIG. 4 ). The fixing surface 5 extends along the fixing surface 12 of the object to be reinforced 11. This allows the rib structure 1 to be properly fixed to the object to be reinforced 11. The rib main body 2, including the semi-cylindrical portion 3 and the flange 4, can be formed to fit along the fixing surface 12 of the object to be reinforced 11. The fixing surface 5 may be the entire lower surface of the flange 4, or a part of the flange 4. In this way, by providing the flanges 4 on both side edges of the semi-cylindrical portion 3 and forming the fixing surface 5 on each flange 4, a hollow portion is formed between the inner surface of the semi-cylindrical portion 3 and the object to be reinforced 11. This allows the rib main body 2 to be lightweight. Furthermore, after the fixing surface 5 of each flange 4 is fixed to the fixing surface 12 of the reinforced body 11, when an external force is applied to the reinforced body 11, the hollow semi-cylindrical portion 3 bends, thereby preventing each fixing surface 5 from peeling off from the fixing surface 12 of the reinforced body 11, and maintaining the reinforcing effect of the rib structure 1.

[0036] The protrusions 6 are formed to protrude from the fixing surface 5. When the rib structure 1 is fixed to the reinforced object 11, the protrusions 6 protrude from the fixing surface 5 toward the reinforced object 11. The protrusions 6 are formed in a polygonal pyramid shape, such as a substantially conical or elliptical conical shape, a substantially triangular or square pyramid shape, tapering toward the tip. That is, the protrusions 6 preferably have a tapered shape. The protrusions 6 may be molded integrally with the rib main body 2, as in the manufacturing method described below, or may be attached to the fixing surface 5 after the rib main body 2 is molded. When the protrusions 6 are molded integrally with the rib main body 2, the resin material of the protrusions 6 is the same as that of the rib main body 2. However, when the protrusions 6 are attached to the rib main body 2, the resin material of the protrusions 6 may be the same as that of the rib main body 2 or a resin material that melts more easily than that of the rib main body 2. That is, the protrusions 6 may have a lower melting point than the rib main body 2.

[0037] The rib main body 2 is not limited to the above configuration. For example, the semi-cylindrical portion 3 may be formed in a semi-columnar shape, and the rib main body 2 may be formed without a hollow portion inside the semi-cylindrical portion 3. Alternatively, the rib main body 2 may be formed so that a part of the outer circumferential surface of a cylinder is cut out in the axial direction to form a flat portion, and the rib main body 2 has a semi-cylindrical shape or a sector shape in cross section. In this case, the flat portion becomes the fixing surface 5.

[0038] As shown in FIG. 4, the mounting structure 10 includes a rib structure 1 and an object to be reinforced 11. The resin material of the object to be reinforced 11 is the same as the resin material of the rib structure 1 described above, and therefore a detailed description thereof will be omitted. The object to be reinforced 11 may be made of a foamed resin like the rib structure 1, or may be made of a foamed resin. When the object to be reinforced 11 is made of a foamed resin, the weight of the object to be reinforced 11 can be reduced, and the load on the rib structure 1 that reinforces the object to be reinforced 11 can be reduced. Furthermore, the weight of the mounting structure 10 can be further reduced.

[0039] The object 11 to be reinforced is, for example, a shaped sheet. The object 11 to be reinforced is used, for example, as interior and exterior materials for various vehicles such as automobiles, trains, and aircraft, as exterior materials for tooling machines such as robots, or as building wall components. Therefore, the rib structure 1 is used to reinforce these objects 11 to be reinforced. The object 11 to be reinforced has a surface 12 to be fixed. The surface 12 to be fixed is fixed to the fixing surface 5 of the rib structure 1. The surface 12 to be fixed may be curved or bent depending on the above-mentioned application.

[0040] Here, the relationship between the thickness of the rib structure 1 and the thickness of the object to be reinforced 11 will be described. As shown in FIG. 4, the object to be reinforced 11 has an average thickness t of, for example, 1 to 5 mm. As shown in FIG. 3, the rib main body 2 has a thickness a that is 1.5 to 6 times the average thickness t of the object to be reinforced 11. If the thickness of the rib structure 1 is too small relative to the thickness of the object to be reinforced 11, the rigidity of the rib structure 1 will be relatively reduced, resulting in a reduced reinforcing effect. On the other hand, if the thickness of the rib structure 1 is too large, the weight will increase and foam cells will break during production, which may reduce the strength of the rib structure 1. Therefore, from the perspective of achieving better lightness and strength, the thickness a of the rib structure 1 should be at least 1.5 times, preferably at least 2.0 times, and at most 6.0 times, preferably at most 3.0 times the average thickness t of the object to be reinforced 11.

[0041] Next, a method for attaching the rib structure 1 to the object to be reinforced 11 will be described.

[0042] The rib structure 1 is attached to the object to be reinforced 11 by thermal welding. That is, the fixing surface 5 of the rib main body 2 is heated to melt it, and the melted fixing surface 5 is pressed against the surface 12 of the object to be reinforced 11. The molten fixing surface 5 is then cooled and solidified in this state, thereby attaching the rib structure 1 to the object to be reinforced 11. At this time, the protrusions 6 also melt, and their protruding height decreases when the rib main body 2 is pressed against the surface 12, or the protrusions 6 melt and become zero. This reduces or eliminates the protruding height of the protrusions 6, which interferes with sufficient contact between the fixing surface 5 and the surface 12, and it can be confirmed that the rib structure 1 and the object to be reinforced 11 have been sufficiently fixed. In other words, by controlling the relative movement between the rib structure 1 and the object to be reinforced 11 due to the reduction in the protruding height of the protrusions 6, the adhesion between the rib structure 1 and the object to be reinforced 11 can be stabilized and the rate of defective adhesion can be reduced. Note that, from the viewpoint of reducing the burden on the environment, a method of attaching the rib structure 1 to the object to be reinforced 11 is preferably a method of attaching the rib structure 1 by thermal welding, but is not particularly limited to this, and other methods may be used, such as a method of dissolving the fixing surface 5 with a solvent, a method of adhering the fixing surface 5 to the object to be reinforced 12 using an adhesive, or a method of melting the fixing surface 5 by ultrasonic melting. Furthermore, if no protrusions 6 are provided on the fixing surface 5, it is preferable that the fixing surface 5 of the rib main body 2 and the object to be reinforced 11 object to be reinforced surface 12 are spot welded. By attaching the rib structure 1 to the object to be reinforced 11 in this manner, the mounting structure 10 can be formed.

[0043] In this manner, the mounting structure 10 in which the rib structure 1 is attached to c11 exhibits excellent reinforcing effects while maintaining light weight, thereby improving the overall lightness and strength of the structure including the reinforced object.

[0044] Next, a method for manufacturing the rib structure 1 will be described with reference to Figs. 5 and 6. Note that this method for manufacturing the rib structure 1 is one example and can be modified in various ways, and is not limited to this. That is, the rib structure 1 described below is manufactured by injection molding. However, the rib structure 1 may also be molded into the shape of the rib structure 1 described above by shaping a foamed resin sheet made by extrusion molding using vacuum molding or the like.

[0045] First, a foam injection molding machine (not shown) and a mold 100 shown in Fig. 5 are prepared, and the mold 100 is attached to the injection port of the foam injection molding machine. The mold 100 has a fixed mold 101, a movable mold 102, mold parts 103, and a coil spring 104.

[0046] The above-mentioned resin material, such as polycarbonate resin, is placed in the screw cylinder of a foam injection molding machine and heated to produce a molten resin. Then, a physical foaming agent, such as nitrogen at a pressure of 15 MPa, is introduced into the screw cylinder and mixed with the molten resin. The molten resin containing the dissolved physical foaming agent is then injected from an injection port, filling a cavity surrounded by a fixed mold 101 and a movable mold 102, as shown in FIG. 5 . A pressure retention step is then performed to form a temporary molded body 200 of the rib structure 1. At this time, the temporary molded body is still in a molten state. A mold part 103 having a hole 103a for forming the protrusion 6 is pressed against the lower surface of the fixed mold 101 from below by a coil spring 104.

[0047] Furthermore, as shown in FIG. 6 , the movable mold 102 is moved downward at any timing by the core back so as to open from the fixed mold 101. The distance of this downward movement, i.e., the amount of opening, is, for example, 3 mm. At this time, the mold part 9 remains pressed against the lower surface of the fixed mold 101 by the elastic force of the coil spring 104. Therefore, even if the movable mold 102 is moved downward, the molten resin does not leak. Then, by operating the core back as described above, the expanded portion 201 expands. The expanded portion 201 is illustrated for convenience in order to clearly explain the amount of expansion of the temporary molded body 200 due to the core back. In reality, the temporary molded body 200 and the expanded portion 201 foam together, forming a single resin molded body including the protrusions 6. The rib structure 1 can be manufactured by removing this resin molded body from the mold 100.

[0048] Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0049] (Example) In order to confirm the reinforcing effect of the rib structure, the following strength test was carried out. That is, a mounting structure in which the rib structure was attached to a reinforced object (shaped sheet) was fixed with a jig, and the tip collapse rate (%) of the reinforced object was measured to confirm the reinforcing effect of the rib structure. As will be described in detail later, the smaller the tip collapse rate, the higher the reinforcing effect, and the larger the tip collapse rate, the lower the reinforcing effect.

[0050] [Table 1]

[0051] Mounting structures for specimens 1 to 16 shown in Table 1 were fabricated. Specimens 1 to 10 are examples, and specimens 11 to 16 are comparative examples. In Table 1, "PC" in the "resin material" section represents polycarbonate resin, "PP talc" represents talc-reinforced polypropylene resin, and "PPS / GF" represents glass fiber-reinforced PPS resin. The "initial thickness" of the "rib body" refers to the thickness of the pre-foamed molded body described above, and "thickness a" refers to the thickness a of the rib body after foam molding. The "initial thickness" refers to "thickness a," i.e., the thickness of the pre-foamed molded body at the larger of the "thickness a1" and "thickness a2" described above. Furthermore, "a / t" refers to the thickness ratio between the rib body and the reinforced body. The "tip collapse rate" and "reinforcement effect" will be described in detail later.

[0052] As specimen 1, a mounting structure was prepared by attaching a rib structure to a reinforced object. The reinforced object was a non-foamed shaped sheet made of a polycarbonate resin (Teijin Panlite L-1250Y) with an average thickness t of 3 mm, a width of 1,000 mm, and a length of 700 mm. The shaped sheet was curved by a thermal bending process. The rib structure was molded by the above-mentioned injection molding method and, as in the above-mentioned embodiment, was composed of a rib main body consisting of a semi-cylindrical portion and a flange, and protrusions. The rib main body had a thickness a of 6 mm, and the preliminary molded body of this rib main body before foaming had an initial thickness of 3 mm. The foaming ratio of the rib main body was 2 times. In other words, the thickness of the rib main body was doubled without increasing its weight. Furthermore, when the cross section of the rib main body was observed using a scanning electron microscope (SEM), the foam cells within the rib main body were found to be closed cells. The cell diameter of the foam cells was 10 to 60 μm, and the average cell diameter was 30 μm.

[0053] The rib structure of specimen 1 was welded to the reinforced body by ultrasonic welding. A welding horn was made to fit the curved shape of the reinforced body, and one rib structure was welded to the surface of the reinforced body in three separate steps. By repeating this process, five rib structures were welded to the surface of the reinforced body at equal intervals across a width of 1,000 mm.

[0054] Only one end of the mounting structure of specimen 1 thus formed was fixed and supported horizontally with a jig, and the extent to which the tip of the reinforced object moved vertically downward at the other end of the mounting structure, i.e., the free end of the mounting structure, was measured, i.e., the tip collapse rate. Here, the tip collapse rate refers to the tip collapse rate of each specimen, where the rib body and the reinforced object were made of the same resin material, and the tip collapse amount of a specimen to which no rib structure was attached was set at 100. Specifically, in Table 1, among specimens 1 to 4 and specimens 11 to 12, which were made of the same resin material, PC resin, the tip collapse rate of specimen 11, to which no rib body was attached, was 100%, and the tip collapse rate of specimen 1 was 20% of that of specimen 11. In other words, it can be said that the smaller the tip collapse rate, the higher the reinforcement effect. Here, when the tip collapse rate was 20% or less, the reinforcing effect was evaluated as "A" as being high, when it was between 20% and 30% the reinforcing effect was evaluated as "B" as being somewhat high, when it was between 30% and 40% the reinforcing effect was evaluated as "C", when it was between 40% and 50% the reinforcing effect was evaluated as "D", and when it was more than 50% the reinforcing effect was evaluated as being almost nonexistent and "E". In addition, when the rib main body was not attached as in test specimen 11, only the reinforced body was supported horizontally by a jig.

[0055] Comparing specimen 1 and specimen 11 in this way, it is clear that a significant reinforcing effect was achieved by attaching the rib structure to the object to be reinforced.

[0056] Specimen 12 was a mounting structure in which a non-foamed rib body with a thickness a of 3 mm was attached to the object to be reinforced. In other words, the rib body of specimen 12 had the same weight as the rib body of specimen 1, but half the thickness. The tip collapse rate of specimen 12 was 55% (reinforcement effect E). In this way, by constructing the rib body from foamed resin, the tip collapse rate of specimen 1 was reduced by more than half, even though the weight was the same, and an excellent reinforcing effect was achieved.

[0057] Specimen 2 was the same as Specimen 1 except for the foaming ratio and thickness a of the rib body. That is, the rib body of Specimen 2 had a thickness a of 9 mm and the same weight as the rib body of Specimen 1. The tip collapse rate of Specimen 2 was 10% (reinforcement effect A), which was smaller than that of Specimen 1. In this way, by increasing the thickness a of the rib body through foaming and increasing the thickness ratio a / t, it was possible to improve the reinforcing effect without increasing the weight of the rib structure.

[0058] Specimen 3 was the same as Specimen 1 and Specimen 2, except for the foaming ratio and thickness a of the rib body. That is, the rib body of Specimen 3 had a thickness a of 4.5 mm and the same weight as the rib bodies of Specimen 1 and Specimen 2. The tip collapse rate of Specimen 3 was 29% (reinforcement effect B). Thus, although Specimen 3 had a slightly lower thickness ratio a / t than Specimen 1 and Specimen 2, resulting in a slightly lower reinforcing effect, it was able to demonstrate a better reinforcing effect than Specimen 12.

[0059] Specimen 4 was the same as specimens 1 to 3 except for the foaming ratio and thickness a of the rib body. That is, the rib body of specimen 3 had a thickness a of 4 mm and the same weight as the rib bodies of specimens 1 to 3. The tip collapse rate of specimen 4 was 35% (reinforcement effect C). Thus, specimen 4 had a better reinforcing effect than specimen 12 because the rib body was made of foamed resin, but the thickness ratio a / t was slightly lower than specimens 1 to 3, so the reinforcing effect was slightly reduced.

[0060] Next, specimens 5 to 7 and specimens 13 to 14, each of which had the same resin material, "PP talc," were compared. For specimen 5, talc-reinforced polypropylene resin (Idemitsu Lion Composite 4700G) was used as the resin material for the rib body and the reinforced body, and the rib structure was fabricated in the same manner as specimen 1. The foam cells within the rib body were closed cells, with an average cell diameter of 30 μm and a porosity of 67%. The thickness ratio a / t of specimen 5 was 3.0, and the tip collapse rate was 25% (reinforcement effect A) compared to specimen 13, which did not have a rib structure attached.

[0061] Specimen 14 differs from specimen 5 in that its rib body is made of non-foamed resin and, because it is non-foamed, has a thickness a of 3 mm; otherwise, it has the same configuration as specimen 5. The tip collapse rate of specimen 14 was 68% (reinforcement effect E) compared to specimen 13, which was significantly greater than the tip collapse rate of specimen 5. Thus, even when a resin reinforced with a filler such as talc was used as the resin material, by constructing the rib body from reinforced resin, it was possible to achieve an excellent reinforcing effect without increasing the weight of the rib structure.

[0062] Specimen 6 had the same structure as Specimen 5, except that the expansion ratio was increased by 5 times. Specimen 6 had a thickness ratio a / t of 5.0 and a tip collapse rate of 18% (reinforcement effect A). The foam cells of Specimen 6 were closed cells, with an average cell diameter of 50 μm and a porosity of 80%. In this way, by increasing the thickness ratio a / t, the reinforcing effect could be improved without increasing the weight of the rib structure.

[0063] Specimen 7 had the same structure as specimens 5 and 6, except that the foaming ratio was increased to 7 times and the reinforced body was made of foamed resin. Specimen 6 had a thickness ratio a / t of 6.7 and a tip collapse rate of 43%. Although the reinforcement effect was improved compared to specimen 14 by using a foamed resin for the rib body, the reinforcement effect was reduced compared to specimens 5 and 6 despite its increased thickness. This is thought to be due to the relatively high porosity of specimen 7, at 85%. Furthermore, because the reinforced body of specimen 7 was made of foamed resin, it was lighter than specimens 5 and 6. Furthermore, considering the relationship between the thickness ratio a / t and the tip collapse rate for specimens 1 to 10, it is inferred that the reinforcement effect will also be reduced if the thickness ratio a / t exceeds at least 6.0 for specimens 1 to 4, 9, and 10, which used PC resin as the resin material, and specimen 8, which used PPS / GF as the resin material.

[0064] Next, specimen 8 was compared with specimens 15 and 16, each of which had the same resin material, "PPS / GF." For specimen 8, glass fiber reinforced polyphenylene sulfide PPS (Z230 manufactured by DIC) was used as the resin material for the rib body and the reinforced body, and the rib structure was fabricated in the same manner as specimen 1 (although the resin temperature and mold temperature during injection molding were different). The expansion ratio of the rib body was 1.5 times. The foam cells within the rib body were closed cells, with an average cell diameter of 35 μm. The thickness ratio a / t of specimen 8 was 1.5, and the tip collapse rate was 20% (reinforcement effect A) compared to specimen 15, which did not have a rib structure, demonstrating an excellent reinforcement effect.

[0065] Specimen 9 differs from Specimen 1 in that it uses foamed PC resin as the resin material for the reinforced body, but otherwise has the same structure as Specimen 1. This reinforced body was produced by melting and kneading molten resin and nitrogen in a screw cylinder similar to the injection molding method described above, and then extruding the molten resin mixed with nitrogen into a sheet shape through a die attached to the tip of the screw cylinder while foaming. The foaming ratio of the reinforced body was 2 times, and the tip collapse rate was 18% compared to Specimen 11 (reinforcement effect A). Because the thickness of the reinforced body before foaming was 1.5 mm, the average thickness t of the reinforced body was the same as Specimen 1, but the weight was smaller than that of Specimen 1. In this way, by using foamed resin for the reinforced body, the weight could be reduced without reducing the thickness of the reinforced body, and the reinforcing effect of the rib structure could be improved.

[0066] Specimen 10 differs from Specimen 9 in the configuration and manufacturing method of the rib body. Specifically, the rib body of Specimen 10 was formed by vacuum forming a foamed PC resin sheet made by extrusion molding, to obtain a rib body with a semi-cylindrical portion and a flange. The expansion ratio of the rib body was 2 times, and the thickness a was 5 mm (thickness ratio a / t was 1.7). With this manufacturing method, it is difficult to provide protrusions. Therefore, the rib structure and the reinforced body were welded by spot welding. The tip collapse rate of Specimen 10 was 20% (reinforcement effect A) compared to Specimen 11.

[0067] In this way, by making the rib body out of foamed resin, it was possible to improve the reinforcing effect while maintaining light weight. Furthermore, according to the results of each test specimen that received a reinforcing effect rating of "B," it was found that the reinforcing effect could be further improved if the void ratio of the rib body was 30 to 80% and the thickness a of the rib body was 1.5 to 6 times the average thickness t of the reinforced object. Furthermore, according to the results of each test specimen that received a reinforcing effect rating of "A," it was found that the reinforcing effect could be further improved if the void ratio of the rib body was 30 to 70% and the thickness a of the rib body was 1.5 to 3.0 times the average thickness t of the reinforced object.

[0068] 1 rib structure, 2 rib main body, 3 semi-cylindrical portion, 4 flange, 5 fixing surface, 10 mounting structure, 11 reinforced body, 12 fixing surface, 100 mold, 101 fixed mold, 102 movable mold, 103 mold part, 104 coil spring, thickness a, average thickness t

Claims

1. A rib structure for reinforcing a reinforced object, the rib structure includes a rib body made of foamed resin, the rib body includes a semi-cylindrical portion and a flange extending radially outward from a side edge of the semi-cylindrical portion; the flange has a fastening surface formed on a surface opposite to the position of the semi-cylindrical portion and fastened to the reinforced body, When the rib structure is attached to the body to be reinforced, a hollow portion is formed between the inner surface of the semi-cylindrical portion and the body to be reinforced, The rib structure, wherein the rib body is made of either an engineering plastic or a super engineering plastic.

2. The rib structure according to claim 1, The semi-cylindrical portion has a shape obtained by cutting out a cylinder in the axial direction.

3. The rib structure according to claim 1 or 2, A rib structure, wherein the fixing surface has a protrusion that protrudes toward the object to be reinforced.

4. The rib structure according to claim 1, The rib body has a thickness a that is 1.5 to 6 times the average thickness t of the reinforced body, a thickness a of the rib body being the largest of a thickness a1 of the rib body at the center in the width direction of the rib body and a2 of the rib body at both end portions in the width direction of the rib body.

5. A mounting structure comprising: The rib structure according to any one of claims 1 to 4, a reinforced body having a surface to which the rib structure is fixed, A mounting structure in which the rib structure is attached to the body to be reinforced by fixing the fixing surface of the rib structure to the fixing surface of the body to be reinforced.

6. 6. The mounting structure according to claim 5, The mounting structure is made of foamed resin.

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