Resin structure

Abstract

Resin structure (1), comprising: a resin element (10) having a through-hole that penetrates in an orthogonal direction perpendicular to a horizontal direction; and a collar (20) that is fitted into the through-hole, wherein the resin element (10) is formed by laminating several base materials in the orthogonal direction which are made of a resin containing reinforcing fibers, characterized in that the resin element (10) exhibits: an outer resin section (11) in which the reinforcing fibers are aligned in the horizontal direction; and an inner resin section (12) which is arranged in the horizontal direction between the outer resin section (11) and the collar; wherein a mean value of a fiber orientation angle of the inner resin section (12) with respect to a side surface (22) of the collar (20) is smaller than a mean value of a fiber orientation angle of the outer resin section (11) with respect to the side surface (22) of the collar (20), the resin element (10) can be produced by pressing the several base materials and causing the several base materials to flow to reach the side surface (22) of the collar (20), the inner resin section (12) has a boundary between the multiple base materials on a surface in the orthogonal direction of the inner resin section (12), the collar (20) has a flange section (24) which extends from an end section in an orthogonal direction in the horizontal direction, and the flange section (24) covers the boundary between the multiple base materials in an orthogonal direction.

Description

Technical field

[0001] The present invention relates to a resin structure according to the preamble of claim 1. State of the art

[0002] JP 2015-86942 A discloses a resin structure comprising a resin element having a through-hole penetrating in an orthogonal direction and a collar fitted into the through-hole. The resin structure is attached to a metallic fastener by means of a bolt (screw) and a nut inserted into the collar.

[0003] The resin element is made of a composite material in which reinforcing fibers, such as carbon fibers or glass fibers, are cured with the resin. The reinforcing fibers are aligned in a horizontal direction along the length of the resin element, thereby improving its strength.

[0004] DE 10 2016 222 467 A1 discloses a method for producing a fiber structure. In this method, at least one fiber layer is aligned in a predetermined position, and a positioning device is inserted into the fiber layer at a predetermined location within the fiber structure. The positioning device penetrates the fiber structure in an insertion direction, displacing the fibers within the fiber structure substantially in a plane perpendicular to the insertion direction of the positioning device.

[0005] DE 11 2017 001 652 T5 discloses a method for inserting an insert into a composite panel, wherein the composite panel comprises a thermoplastic polymer material and reinforcing fibers embedded in the thermoplastic polymer material. The fibers are pushed apart in a radial direction. This creates fiber bundles around the insert without the fibers breaking.

[0006] DE 10 2017 111 146 A1 discloses a method for manufacturing a molded part with a fiber-reinforced carrier and a connecting bushing attached to it, which has at least one fastening opening. For this purpose, a fiber-reinforced mat is inserted between the respective embossing surfaces of two tool components, which are in an open position. The mat can consist of natural fibers or synthetic fibers, such as glass fibers or plastic fibers. The connecting bushing is positioned on a positioning dome located on at least one tool component. After the fiber-reinforced mat has been inserted and the connecting bushing positioned, the tool components are closed, so that the mat is compressed and pressed to produce the fiber-reinforced carrier. The positioning dome creates an opening in the mat by punching out a waste piece from the mat. Summary of the invention: Technical problem

[0007] When the resin structure is secured with a fastener (or attached element), the stress (or strain) concentrates around the collar, and a force acts in one direction, pressing the resin element against a side surface of the collar. If the resin element cannot withstand the force acting on the side surface of the collar, a force acts on one surface (e.g., the top surface) of the resin element in one direction (e.g., upwards) along the side surface of the collar, and a force acts on the other surface (e.g., the bottom surface) of the resin element in the opposite direction (e.g., downwards) along the side surface of the collar.

[0008] If the resin element is formed by laminating several base materials in an orthogonal direction, which are made from a resin containing reinforcing fibers, the strength between the base materials is weak compared to the strength in the base material in which the reinforcing fibers are aligned, which is why there is a risk of delamination, in which the base materials in the resin element are separated from each other around the collar.

[0009] One object of the present invention is therefore to prevent the occurrence of delamination in a resin structure formed by laminating several base materials in an orthogonal direction, which are made from a resin containing reinforcing fibers. Means to solve the problem

[0010] A resin structure according to one aspect comprises: a resin element having a through-hole penetrating in an orthogonal direction perpendicular to a horizontal direction; and a collar fitted into the through-hole, the resin element being formed by laminating several base materials in the orthogonal direction, which are made of a resin containing reinforcing fibers. The resin structure is characterized in that the resin element has: an outer resin section in which the reinforcing fibers are aligned in the horizontal direction; and an inner resin section arranged in the horizontal direction between the outer resin section and the collar.wherein a mean value of a fiber orientation angle of the inner resin section with respect to a side surface of the collar is smaller than a mean value of a fiber orientation angle of the outer resin section with respect to the side surface of the collar, wherein the resin element is producible by pressing the multiple base materials and causing the multiple base materials to flow to reach the side surface of the collar, wherein the inner resin section has a boundary between the multiple base materials on a surface in the orthogonal direction of the inner resin section, the collar has a flange section extending from an end section in the orthogonal direction in the horizontal direction, and the flange section covers the boundary between the multiple base materials in the orthogonal direction.

[0011] Since the mean fiber orientation angle of the inner resin section with respect to the collar's side surface is smaller than that of the outer resin section with respect to the collar's side surface, the reinforcing fibers of the inner resin section align in one direction along the collar's side surface compared to the reinforcing fibers of the outer resin section. Consequently, the strength of the inner resin section increases in the direction along the collar's side surface compared to the outer resin section, thus preventing delamination in the inner resin section. Brief description of the drawings Fig. Figure 1 is a cross-sectional view of a resin structure according to one embodiment. Fig. Figure 2 is an enlarged cross-sectional view of the resin structure according to the embodiment. Fig. Figure 3 is an enlarged cross-sectional view of a resin structure according to a first modified example of the embodiment. Fig. Figure 4 is an enlarged cross-sectional view of a resin structure according to a second modified example of the embodiment. Fig. Figure 5 is an enlarged cross-sectional view of a resin structure according to a third modified example of the embodiment. Fig. Figure 6 is an enlarged cross-sectional view of a resin structure according to a fourth modified example of the embodiment. Fig. Figure 7 is an enlarged cross-sectional view of a resin structure according to a fifth modified example of the embodiment. Fig. Figure 8 is a diagram describing a process for producing a resin structure 1. Description of the embodiments

[0012] Preferred embodiments of the present invention are described in more detail below with reference to the accompanying drawings. In the following description of the drawings, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic, and the proportions of the respective dimensions and the like may differ from reality. Specific dimensions and the like should therefore be determined with reference to the following description. Furthermore, the drawings may contain parts with different dimensional relationships or ratios.In the present description and in the drawings, elements that have essentially the same function and configuration are designated by the same reference numerals to avoid redundant description, while elements that are not directly related to the present invention are not shown. (1) Schematic structure of the resin

[0013] A schematic diagram of a resin structure 1 is shown with reference to the Fig. 1 and Fig. 2 described. Fig. Figure 1 is a cross-sectional view of a resin structure according to one embodiment, and Fig. Figure 2 is an enlarged cross-sectional view of the resin structure according to the embodiment.

[0014] Arrow X in the drawing indicates a horizontal direction, and arrow Z indicates an orthogonal direction. In the horizontal direction X, a direction approaching a collar 20 described later can be called the inward direction X1, and a direction away from the collar 20 can be called the outward direction X2. The orthogonal direction Z can be called the upward and downward directions. One direction in the orthogonal direction Z can be called the upward direction Z1, and the other direction in the orthogonal direction Z can be called the downward direction Z2. The horizontal direction X can be called an in-plane direction, and the orthogonal direction Z can be called an out-of-plane direction.

[0015] As in Fig. As shown in Figure 1, the resin structure 1 has a resin element 10, a collar 20, a fastening element 30, a bolt (screw) 40 and a nut 50.

[0016] As in Fig. 1 and Fig. As shown in Figure 2, the resin element 10 extends in the horizontal direction X. The resin element 10 has a first through-hole 15 that penetrates in the orthogonal direction Z. The collar 20 is fitted into the first through-hole 15.

[0017] The resin element 10 is formed by laminating several base materials in the orthogonal direction Z, which are made of a resin containing reinforcing fibers. The resin containing reinforcing fibers can be referred to as a fiber-reinforced resin. The lines shown in each drawing ( Fig. Figures 1 to 8 within the resin element 10 schematically indicate a fiber orientation of the reinforcing fibers in the respective area.

[0018] The resin material of a resin containing reinforcing fibers can be either a thermoplastic resin or a thermosetting resin. Examples of thermoplastic resins include polyamide or polypropylene, while examples of thermosetting resins include epoxy resin or phenolic resin.

[0019] Resin element 10 can use carbon fibers, glass fibers, polyamide fibers, polyethylene fibers, or similar materials as reinforcing fibers. Therefore, for example, a carbon fiber reinforced plastic (CFRP) as a composite material in which the carbon fibers are cured with a resin, a glass fiber reinforced plastic (GFRP) as a composite material in which the glass fibers are cured with a resin, or similar materials can be used as a resin containing reinforcing fibers.

[0020] The reinforcing fiber can be a discontinuous fiber. The length of a reinforcing fiber can be 10 mm or more. A weighted mean fiber length can be 10 mm or more and 100 mm or less.

[0021] The collar 20 is fitted into the first through-hole 15. The collar 20 has a second through-hole 25 into which the bolt 40 is inserted. The second through-hole 25 penetrates the collar 20 in the orthogonal direction Z.

[0022] The collar 20 can be formed as a metal block made of, for example, a steel material, an aluminum material, an aluminum alloy material or similar.

[0023] The fastening element 30 can be formed as a metal plate made of, for example, steel, aluminum, an aluminum alloy, or a similar material. The fastening element 30 has an opening into which the bolt 40 is inserted.

[0024] In the present embodiment, the bolt 40 and the nut 50 are used as fasteners for securing the resin element 10 and the fastening element 30. The bolt 40 has a threaded section 42 that is inserted into the second through-hole 25 of the collar 20, and a bolt head 44 that is provided in the orthogonal direction Z at an end section of the threaded section 42. The nut 50 has a fastening through-hole 55 into which the threaded section 42 is inserted. A threaded section that is screwed to the threaded section 42 of the bolt 40 is formed on a side wall of the fastening through-hole 55.

[0025] As in the Fig. 1 and Fig. Figure 2 shows an example of a case in which the resin element 10 is formed from three base materials in the present embodiment.

[0026] The resin element 10 has an outer resin section 11 and an inner resin section 12.

[0027] A region of the outer resin section 11 can be defined by an orientation angle of the individual fibers that form the reinforcing fibers. In this description, an angle (fiber orientation angle) θ1, formed by a neutral plane of the resin element and the individual fiber, is set in the range of 0° to 90°, with the mean value being calculated. If the mean value is 0° to 30°, this defines the resin element with reinforcing fibers oriented horizontally; if the mean value is 30° to 60°, this defines the resin element with reinforcing fibers oriented arbitrarily; and if the mean value is 60° to 90°, this defines the resin element with reinforcing fibers oriented vertically.

[0028] A method for measuring the alignment angle of a single fiber is not particularly limited; however, the alignment angle can be measured by acquiring an image of the single fiber, e.g., using X-ray CT. If the reinforcing fiber has high radiolucency and is difficult to image, the image of the single fiber can be acquired using an electron microscope.

[0029] If the single fiber is curved, a direction of the single fiber is also approximated by a direction of a line segment in which the two ends of the single fiber are connected.

[0030] The outer resin section 11 is a section in which the reinforcing fiber is aligned in the horizontal direction X. The mean value of the fiber orientation angle θ1 of the outer resin section 11 with respect to the neutral plane of the resin element 10 is therefore 0° to 30°. The outer resin section 11 has a first outer layer 111, a second outer layer 112, and a third outer layer 113. The first outer layer 111 forms one surface (upper surface 10U) in the orthogonal direction Z. The first outer layer 111 corresponds to an upper layer. The second outer layer 112 is located in the orthogonal direction Z between the first outer layer 111 and the third outer layer 113. The third outer layer 113 forms the other surface (lower surface 10L) in the orthogonal direction Z. The third outer layer 113 corresponds to a lower layer.

[0031] The inner resin section 12 is a section located in the horizontal direction X between the outer resin section 11 and the collar 20. The inner resin section 12 has a first inner layer 121, a second inner layer 122, and a third inner layer 123.

[0032] The first inner layer 121 forms one surface (upper surface 10U) in the orthogonal direction Z. The first inner layer 121 corresponds to an upper layer. As in Fig. As shown in Figure 2, the first inner layer 121 can be in contact with the collar 20. Alternatively, only the first inner layer 121 can be in contact with the collar 20, and the second inner layer 122 and the third inner layer 123 need not be in contact with the collar 20. Therefore, the first inner layer 121 can be in contact with a side surface of the collar 20 over a larger area than the third inner layer 123.

[0033] Therefore, the area of ​​a contact surface of the first inner layer 121 with respect to the side surface of the collar 20 is larger than that of a contact surface of the third inner layer 123 with respect to the side surface of the collar 20. It should be noted that the first inner layer 121 can be in contact with the side surface of the collar 20 over a larger area than the second inner layer 122. Therefore, the area of ​​the contact surface of the first inner layer 121 with respect to the side surface of the collar 20 is larger than that of the contact surface of the second inner layer 122 with respect to the side surface of the collar 20.

[0034] The first inner layer 121 can form a lower surface 10L. If it forms the lower surface 10L, the first inner layer 121 can form the lower surface 10L on the side closest to the collar 20.

[0035] The first inner layer 121 can extend downwards in the inward direction X1. The first inner layer 121 can cover the second inner layer 122. Therefore, in the horizontal direction X, the first inner layer 121 can overlap with the second inner layer 122. Furthermore, in the horizontal direction X, the first inner layer 121 can overlap with the third inner layer 123.

[0036] The second inner layer 122 is located in the orthogonal direction Z between the first inner layer 121 and the third inner layer 123. The second inner layer 122 can form the lower surface 10L.

[0037] The second inner layer 122 can extend downwards in the inward direction X1. The second inner layer 122 can cover the third inner layer 123. Therefore, in the horizontal direction X, the second inner layer 122 can overlap with the third inner layer 123.

[0038] The third inner layer 123 forms the other surface (lower surface 10L) in the orthogonal direction Z. The third inner layer 123 corresponds to a lower layer. If the multiple inner layers form the lower surface 10L, the third inner layer 123 can form the lower surface 10L on the side of the outermost outer resin section 11.

[0039] The collar 20 has a side surface 22 that is in contact with the inner resin section 12. The mean fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 is smaller than the mean fiber orientation angle θ21 of the outer resin section 11 with respect to the side surface 22 of the collar 20. Consequently, the reinforcing fibers of the inner resin section 12 extend along the side surface 22 of the collar 20 (i.e., in the orthogonal direction Z) compared to the reinforcing fibers of the outer resin section 11. Therefore, the strength in the inner resin section 12 is higher in the direction along the side surface 22 of the collar 20 compared to the outer resin section 11, thus preventing delamination in the inner resin section 12.

[0040] The mean value of the fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 can be from 0° to 30°. Consequently, in the inner resin section 12, the strength decreases in the direction along the side surface 22 of the collar 20 (orthogonal direction Z in Fig. 1) so that delamination in the inner resin section 12 can be prevented. It should be noted that in the present embodiment, the mean value of the fiber orientation angle θ21 of the outer resin section 11 with respect to the side surface 22 of the collar 20 can be between 60° and 90°. In this case, the reinforcing fibers are aligned in the horizontal direction in which the outer resin section 11 extends, and the strength of the outer resin section 11 can increase.

[0041] The fiber orientation angles θ21 and θ22 of the reinforcing fibers (or the individual fiber) with respect to the side surface 22 of the collar 20 are angles θ21 and θ22 formed by a direction connecting both ends of a boundary line between the collar 20 (or its side surface 22) and the resin element 10 when the side surface 22 of the collar 20 is cut on a surface containing a central axis C of the collar 20, and by a direction of the individual fiber, and are set in the range of 0° to 90°. The individual fiber is chosen such that the surface containing the central axis C of the collar 20 passes through a portion of the individual fiber. If the individual fiber is curved, its direction is approximated by the direction connecting both ends.

[0042] Since, as in the present embodiment, the side surface 22 of the collar 20 is parallel to the orthogonal direction Z, the fiber orientation angles θ21 and θ22 of the reinforcing fibers with respect to the side surface 22 of the collar 20 are equal to 0° when the individual fiber is parallel to the orthogonal direction Z, and equal to 90° when the individual fiber is perpendicular to a Z-axis.

[0043] The mean fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 is calculated as an average by randomly selecting a total of 100 individual fibers from the inner resin section 12 and measuring the fiber orientation angle for each individual fiber. The mean fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 is calculated in the same way as the inner resin section 12.

[0044] In the inner resin section 12, the mean value of the fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 can decrease continuously in the inward direction X1. Consequently, it is possible to prevent a decrease in strength due to a discontinuous diffraction of the fiber orientation.

[0045] It should be noted that, as in the present embodiment, if the side surface 22 of the collar 20 is parallel to the orthogonal direction Z, the inner resin section 12 can have reinforcing fibers oriented in the orthogonal direction Z. Consequently, the strength in the orthogonal direction Z is further increased by the reinforcing fibers oriented in the orthogonal direction Z, thus preventing delamination in the inner resin section 12.

[0046] Furthermore, if, as in the present embodiment, the side surface 22 of the collar 20 is parallel to the orthogonal direction Z, the mean value of the inclination angle (i.e., the angle θ1) of the reinforcing fibers with respect to the horizontal direction X increases in the inward direction X1. That is, the orientation of the reinforcing fibers can change continuously in the inward direction X1. Consequently, it is possible to prevent the decrease in strength due to discontinuous changes in orientation. The mean value of the inclination angle θ1 of the reinforcing fibers with respect to the horizontal direction can be greater inside the inner resin section 12 in the horizontal direction X than on the outside of the inner resin section 12 in the horizontal direction X.

[0047] In the present embodiment, the side surface 22 of the collar 20 is parallel to the orthogonal direction Z. Consequently, the reinforcing fibers in the inner resin section 12 are aligned along the side surfaces 22, so that the number of reinforcing fibers oriented obliquely to the horizontal direction X can increase. (2) Modified examples according to the invention

[0048] Each modified example of the embodiment according to the invention is described with reference to the Fig. 3 to 7 described. Fig. Figure 3 is an enlarged cross-sectional view of a resin structure according to a first modified example of the embodiment. Fig. Figure 4 is an enlarged cross-sectional view of a resin structure according to a second modified example of the embodiment. Fig. Figure 5 is an enlarged cross-sectional view of a resin structure according to a third modified example of the embodiment. Fig. Figure 6 is an enlarged cross-sectional view of a resin structure according to a fourth modified example of the embodiment. Fig. Figure 7 is an enlarged cross-sectional view of a resin structure according to a fifth modified example of the embodiment. Note that the part identical to that described above is omitted.

[0049] As in Fig. As shown in Figure 3, a collar 20 has a flange section 24 extending from an end section in an orthogonal direction Z in a horizontal direction X.

[0050] An inner resin section 12 has boundaries between several base materials on a surface of the inner resin section in the orthogonal direction Z. In particular, the inner resin section 12 has a boundary B1 between a first inner layer 121 and a second inner layer 122 on a lower surface 10L. The inner resin section 12 has a boundary B2 between the second inner layer 122 and a third inner layer 123 on the lower surface 10L.

[0051] Flange section 24 covers the boundaries between the several base materials in the horizontal direction X. In particular, flange section 24 covers boundary B1 and boundary B2. Accordingly, it is possible to prevent the concentration of stresses near boundaries B1 and B2 when a load is applied, and consequently, it is possible to prevent the occurrence of delamination originating from boundaries B1 and B2 on the lower surface 10L.

[0052] As in Fig. As shown in Figure 4, the flange section 24 covers the inner resin section 12 in the horizontal direction X. The flange section 24 can also cover part of the outer resin section 11. The inner resin section 12 has a lower degree of in-plane alignment of the reinforcing fibers (i.e., alignment in the horizontal direction) than the outer resin section 11. Therefore, its strength under in-plane loading in the horizontal direction X is lower. By covering the inner resin section 12 with the flange section 24, it is therefore possible to prevent the concentration of stresses on a portion of the inner resin section 12 and thus prevent failure originating from the inner resin section 12.

[0053] As in Fig. As shown in Figure 5, the collar 20 has a side surface 22 that is in contact with the inner resin section 12 and is inclined with respect to the orthogonal direction Z. The collar 20 has a conical shape.

[0054] The first inner layer 121, corresponding to the upper layer, is in contact with the side surface of the collar 20 over a larger area than the third inner layer 123, corresponding to the lower layer. Therefore, the area of ​​a contact surface of the first inner layer 121 with respect to the side surface of the collar 20 is larger than that of a contact surface of the third inner layer 123 with respect to the side surface of the collar 20.

[0055] A thickness T in the horizontal direction X from a central axis C of the collar 20 to the side surface 22 increases from the first inner layer 121 (upper layer) towards the third inner layer 123 (lower layer). Consequently, during manufacturing, the distance from each base material to the side surface 22 can correspond to a flow distance of the respective base material, and therefore some base materials (e.g., the base material corresponding to the first inner layer 121) can flow more than necessary, thus preventing the formation of a boundary within the inner resin section 12 due to the bonding of the three inner layers. This boundary causes a decrease in strength. Therefore, the collar 20, as shown in Fig. As shown in Figure 5, the conical shape can prevent the decrease in strength.

[0056] It should be noted that, as in Fig. As shown in Figure 5, the side surface 22 of the collar 20 is inclined with respect to the orthogonal direction Z. Therefore, a fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 does not coincide with the fiber orientation angle with respect to the orthogonal direction Z.

[0057] It should be noted that the central axis C of the collar 20 is an axis along the orthogonal direction Z. Furthermore, the thickness T can be a radius of the collar 20.

[0058] As in Fig. As shown in Figure 6, the thickness T decreases in the horizontal direction X from the central axis C of the collar 20 to the side surface 22, starting from the first inner layer 121 (upper layer) and progressing to the third inner layer 123 (lower layer). Consequently, the base material flows along the slope of the side surface 22 during manufacturing, and thus the reinforcing fibers are easily aligned along this slope. By adjusting the alignment angle of the reinforcing fibers, it is possible to prevent delamination and also to prevent a decrease in strength under load in the horizontal direction X (in-plane loading).

[0059] As in Fig. As shown in Figure 7, the collar 20 has a first flange section 24A extending from one end section in the orthogonal direction Z in the horizontal direction X, and a second flange section 24B extending from the other end section in the horizontal direction X.

[0060] Consequently, it is possible to prevent the concentration of stresses on the inner resin section 12 not only on one side but also on the other side in the orthogonal direction Z, and it is possible to further prevent the occurrence of delamination and fracture originating from the inner resin section 12. (3) Method for producing a resin structure

[0061] Next, a method for producing the resin structure 1 is described with reference to Fig. 8 described. Fig. Figure 8 is a diagram describing a process for producing a resin structure 1.

[0062] As in Fig. Figure 8 shows a method for producing a resin structure 1 using a collar 20. Fig. 7 described. First, as an example, a case of using a thermoplastic resin for the resin element 10 is described.

[0063] First, several base materials 100 are heated with an infrared heater or similar device until the base material 100 reaches a melting point or higher.

[0064] In step S10, the collar 20 and the several base materials 100 are placed in a mold. The mold is set to a temperature below the melting point of the base material 100.

[0065] The multiple base materials 100 are laminated in the orthogonal direction Z. The multiple base materials 100 can be pre-integrated by a stamping process. The multiple base materials 100 are provided with openings 150 that are larger than the outer diameter of the collar 20. The collar 20 is positioned within the opening 150. A gap is provided between the side surface 22 of the collar 20 and the multiple base materials 100.

[0066] Since the temperature of the mold is lower than the melting point of the base material 100, the lower mold 220 draws heat from the lower base material 100 and consequently the lower base material 100 has a lower flowability than the upper base material 100.

[0067] In step S20, an upper form 210 presses against the multiple base materials 100 to exert pressure on them. The multiple base materials 100 flow to reach the side surface of the collar 20. Subsequently, the multiple base materials 100 are cooled and solidified.

[0068] Since the lower form 220 draws heat from the lower base material 100, the lower base material 100 has a lower flowability than the upper base material 100. Therefore, the upper base material 100 has a large flow distance, and the lower base material 100 has a small flow distance. Consequently, the upper base material 100 can cover the lower base material 100. In this way, by increasing the flow distance of one (upper) base material 100 in the orthogonal direction Z and decreasing the flow distance of the other (lower) base material 100 in the orthogonal direction Z, as described above, an average value of the fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 can be set to 0° to 30°.Consequently, the mean value of a fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 can be smaller than that of a fiber orientation angle θ21 of the outer resin section 11 with respect to the side surface 22 of the collar 20.

[0069] In step S30, the upper form 210 is removed after the multiple base materials 100 have been cooled and solidified. The multiple base materials 100, which have been cooled and solidified, form the resin element 10. As a result, the resin structure 1 with the resin element 10 and the collar 20 can be produced.

[0070] It should be noted that in the case where the thermosetting resin is used for the resin element 10, the resin structure 1 can be produced by compression molding and thermosetting a semi-cured resin element in which the reinforcing fibers are impregnated in the thermosetting resin.

[0071] Since, in this case, the lower base material 100 is heated from the lower mold 220 before pressing, the lower base material 100 has a lower flowability than the upper base material 100. Therefore, the upper base material 100 has a large flow distance, and the lower base material 100 has a small flow distance. Consequently, the upper base material 100 can cover the lower base material 100. In this way, by increasing the flow distance of one (upper) base material 100 in the orthogonal direction Z and decreasing the flow distance of the other (lower) base material 100 in the orthogonal direction Z, the mean value of the fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 can be adjusted to 0° to 30°.Consequently, the mean value of the fiber orientation angle θ22 of the inner resin section 12 with respect to the side surface 22 of the collar 20 can be smaller than that of a fiber orientation angle θ21 of the outer resin section 11 with respect to the side surface 22 of the collar 20. (4) Other embodiments

[0072] While the present invention has been described in more detail with reference to the embodiments mentioned above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described herein. The present invention can be implemented with modified examples and changes without deviating from the inventive concept and scope of the present invention as defined by the scope of the claims. Therefore, the description of the present embodiments serves for illustration purposes and has no limiting effect on the present invention. List of reference symbols 1 Resin structure 10 resin elements 10L lower surface 10U upper surface 11 outer Harz section 12 inner Harz section 15 first through hole 20 collars 22 Side surface 24 Flange section 24A first flange section 24B second flange section 25 second through hole 30 Fastening element 40 bolts 42 Thread section 44 bolt head 50 mother 55 Mounting through hole 100 basic materials 111 first outer layer 112 second outer layer 113 third outer layer 121 first inner layer 122 second inner layer 123 third inner layer 150 opening 210 upper form 220 lower form B1 border B2 border C Central axis

Claims

[1] Resin structure (1), comprising: a resin element (10) having a through-hole that penetrates in an orthogonal direction perpendicular to a horizontal direction; and a collar (20) that is fitted into the through-hole, wherein the resin element (10) is formed by laminating several base materials in the orthogonal direction which are made of a resin containing reinforcing fibers, characterized by , that the resin element (10) exhibits: an outer resin section (11) in which the reinforcing fibers are aligned in the horizontal direction; and an inner resin section (12) which is arranged in the horizontal direction between the outer resin section (11) and the collar; wherein a mean value of a fiber orientation angle of the inner resin section (12) with respect to a side surface (22) of the collar (20) is smaller than a mean value of a fiber orientation angle of the outer resin section (11) with respect to the side surface (22) of the collar (20), the resin element (10) can be produced by pressing the several base materials and causing the several base materials to flow to reach the side surface (22) of the collar (20), the inner resin section (12) has a boundary between the multiple base materials on a surface in the orthogonal direction of the inner resin section (12), the collar (20) has a flange section (24) which extends from an end section in an orthogonal direction in the horizontal direction, and the flange section (24) covers the boundary between the multiple base materials in an orthogonal direction. [2] Resin structure (1) according to claim 1, characterized by , that the mean value of the fiber orientation angle of the inner resin section (12) with respect to the side surface (22) of the collar (20) is 0° to 30°. [3] Resin structure (1) according to claim 1 or 2, characterized by , that the mean value of the fiber orientation angle of the inner resin section (12) with respect to the side surface (22) of the collar (20) in the inner resin section (12) decreases continuously in the inward direction. [4] Resin structure (1) according to any one of claims 1 to 3, characterized by , that the collar (20) has the flange section (24) which extends from the end section in an orthogonal direction in the horizontal direction, and the flange section (24) covers the inner resin section (12) in an orthogonal direction. [5] Resin structure (1) according to any one of claims 1 to 4, characterized by , that the side surface (22) of the collar (20) is in contact with the inner resin section (12) and is inclined with respect to the orthogonal direction; the inner resin section (12) exhibits: an upper layer that forms a surface in the orthogonal direction; and a lower layer that forms the other surface in the orthogonal direction; wherein the upper layer is in contact with the side surface (22) over a larger area than the lower layer; and the thickness of the collar (20) increases in a horizontal direction from a central axis of the collar (20) to the side surface (22) from the upper layer to the lower layer. [6] Resin structure (1) according to any one of claims 1 to 4, characterized by , that the side surface (22) of the collar (20) is in contact with the inner resin section (12) and is inclined with respect to the orthogonal direction; the inner resin section (12) exhibits: an upper layer that forms a surface in the orthogonal direction; and a lower layer that forms the other surface in the orthogonal direction; wherein the upper layer is in contact with the side surface (22) of the collar (20) over a larger area than the lower layer; and the thickness of the collar (20) decreases in a horizontal direction from a central axis of the collar (20) to the side surface (22) from the upper layer to the lower layer. [7] Resin structure (1) according to any one of claims 1 to 4, characterized by , that the side surface (22) of the collar (20) is in contact with the inner resin section (12) and is parallel to the orthogonal direction.

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