Fastening member

Abstract

To provide a fastening member capable of easily and securely mounting a fixation object on a wall surface regardless of thickness of a wall material.SOLUTION: A fastening member 1 includes: a cylinder part 2 having a cylindrical shape and including a plurality of leg parts 21 divided by a plurality of slits extending from one end 2a to the other end 2b; a bar-like part 3 provided on the inner side of the cylinder part 2 and extending along a central axis C of the cylinder part 2; and a flange part 4 provided at the other end 2b of the cylinder part 2 and expanding from an opening edge on the other end 2b side of the cylinder part 2 to outside. A plurality of recesses and a plurality of projections are formed on the inner peripheral surface of the cylinder part 2 to be alternately aligned along the central axis C. A plurality of recesses and a plurality of projections are formed on the outer peripheral surface of the bar-like part 3 to be alternately aligned along the central axis C. Recesses and projections 23 formed on the inner peripheral surface of the cylinder part 2 and recesses and projections 34 formed on the outer peripheral surface of the bar-like part 3 are fitted to each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fastening member. [Background technology]

[0002] Fastening members are sometimes used to secure a fixed object to a wall surface. An example of a fixed object is a cover provided with an operating unit or the like. An example of a fastening member is a screw. For example, a switch box that is pre-fixed to the inside of a wall is fastened to a cover that is provided on the outside of the wall with a screw, thereby securing the cover to the wall surface. Fastening with a screw requires the cover to be held down with one hand while turning the screw, making the work difficult and reducing work efficiency.

[0003] Therefore, Patent Document 1 discloses a fastening member that can fix an object to a wall surface without using screws. The fastening member disclosed in Patent Document 1 is configured such that after the shank is passed through a hole formed in the object to be fastened, the part at the end of the hole expands outward to prevent the fastening member from slipping out of the hole, thereby fastening the object. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-148430 Summary of the Invention [Problem to be solved by the invention]

[0005] In the fastening member disclosed in Patent Document 1, the outward extending range of the shaft is fixed. Therefore, there is a problem that fastening cannot be performed when the thickness of the object to be fastened or the distance between the objects changes. In the example of fastening the cover and switch box described above, the distance between the cover and the switch box varies depending on the thickness of the wall material. [Means for solving the problem]

[0006] In order to solve the above-described problems, the fastening member includes a cylindrical portion having a plurality of leg portions divided by a plurality of slits extending from one end to the other end in a cylindrical shape, a rod-shaped portion provided inside the cylindrical portion and extending along the central axis of the cylindrical portion, and a flange portion provided at the other end of the cylindrical portion and spreading outward from the opening edge on the other end side of the cylindrical portion. A plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis on the inner peripheral surface of the cylindrical portion, and a plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis on the outer peripheral surface of the rod-shaped portion. The unevenness formed on the inner peripheral surface of the cylindrical portion and the unevenness formed on the outer peripheral surface of the rod-shaped portion are fitted to each other.

Effects of the Invention

[0007] According to the present invention, there is an effect that the object to be fixed can be easily and surely fixed to the wall surface regardless of the thickness of the wall material.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

[0009] Hereinafter, embodiments of the fastening member according to the present application will be described in detail with reference to the drawings. Note that the fastening member according to the present application is not limited by this embodiment.

[0010] <Regarding the overall configuration of the fastening member> FIG. 1 is a perspective view of the fastening member according to the embodiment. FIG. 2 is a cross-sectional view of the fastening member according to the embodiment. The fastening member 1 includes a cylindrical portion 2, a flange portion 4, a rod-shaped portion 3, and a spring portion 5.

[0011] The cylindrical portion 2 has a cylindrical shape. The cylindrical portion 2 is formed of, for example, resin. A plurality of slits 22 are formed in the cylindrical portion 2 from one end 2a toward the other end 2b. In the following description, the direction from the other end 2b toward the one end 2a in the fastening member 1 is referred to as the one end 2a side. Also, the direction from the one end 2a toward the other end 2b in the fastening member 1 is referred to as the other end 2b side.

[0012] A plurality of leg portions 21 divided by the plurality of slits 22 are formed in the cylindrical portion 2. By being divided by the plurality of slits 22, the plurality of leg portions 21 are connected to each other on the other end 2b side and separated on the one end 2a side.

[0013] As shown in FIG. 2, on the inner peripheral surface of the cylindrical portion 2, unevenness 23 is formed in which a plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis C of the cylindrical portion 2. In other words, the unevenness 23 is formed by changing the inner diameter of the cylindrical portion 2 along the central axis C.

[0014] On the outer peripheral surface of the cylindrical portion 2, unevenness 24 is formed in which a plurality of concave portions and a plurality of convex portions are arranged alternately along the central axis C of the cylindrical portion 2. The interval between the concave and convex portions formed in the unevenness 24 is shorter than the interval between the concave and convex portions formed in the unevenness 23.

[0015] FIG. 3 is an enlarged partial perspective view of one end of the fastening member according to the embodiment. At one end 2a of the cylindrical portion 2, a connecting portion 25 is formed for connecting the leg portions 21 divided by the slit 22. The connecting portion 25 prevents the leg portions 21 from spreading outward by connecting the leg portions 21 to each other. The connecting portion 25 breaks when a load for expanding the inner diameter of the cylindrical portion 2 is applied by the movement of the rod-shaped portion 3 described later. When the connecting portion 25 breaks, the interval between the leg portions 21 is allowed to widen.

[0016] The flange portion 4 is formed at the other end 2b of the cylindrical portion 2. The flange portion 4 is formed integrally with the cylindrical portion 2. The flange portion 4 is formed so as to spread outward from the opening edge of the other end 2b of the cylindrical portion 2.

[0017] Returning to FIG. 2, the rod-shaped portion 3 is a rod-shaped member provided inside the cylindrical portion 2 and extending along the central axis C. The rod-shaped portion 3 is formed of, for example, resin. On the outer peripheral surface of the rod-shaped portion 3, unevenness 34 is formed in which a plurality of concave portions and a plurality of convex portions are arranged along the central axis C of the cylindrical portion 2. The unevenness 23 formed on the inner peripheral surface of the cylindrical portion 2 and the unevenness 34 formed on the outer peripheral surface of the rod-shaped portion 3 are fitted to each other. In the following description, the state in which the unevenness 23 and the unevenness 34 are fitted to each other is also referred to as the initial state of the fastening member 1.

[0018] FIG. 4 is an enlarged partial cross-sectional view of the portion A shown in FIG. 2. The surface 23a facing the one end 2a side on the inner peripheral surface of the cylindrical portion 2 where the unevenness 23 is formed is a surface perpendicular to the central axis C. The surface 34a facing the other end 2b side on the outer peripheral surface of the rod-shaped portion 3 where the unevenness 34 is formed is a surface perpendicular to the central axis C. In the initial state, the surface 23a and the surface 34a face each other. Since the surface 23a and the surface 34a perpendicular to the central axis C face each other, the rod-shaped portion 3 cannot be moved to the other end 2b side from the initial state.

[0019] On one hand, the surface 23b facing the other end 2b side on the inner peripheral surface of the cylindrical portion 2 where the unevenness 23 is formed approaches the central axis C as it goes toward the one end 2a side along the central axis C. The surface 34b facing the one end 2a side on the outer peripheral surface of the rod-shaped portion 3 where the unevenness 34 is formed approaches the central axis C as it goes toward the one end 2a side along the central axis C. In the initial state, the surface 23b and the surface 34b face each other. Since the surface 23b and the surface 34b that approach the central axis as they go toward the one end 2a side along the central axis C face each other, when trying to move the rod-shaped portion 3 toward the one end 2a side from the initial state, the surface 34b will push the surface 23b. When the surface 34b pushes the surface 23b, a force that expands outward is applied to the leg portion 21 of the cylindrical portion 2. When the leg portion 21 expands outward due to the force that expands outward, the rod-shaped portion 3 can move toward the one end 2a side.

[0020] When the rod-shaped portion 3 moves toward the one end 2a side, at each location where the concave portion and the convex portion are formed, a force that tries to expand outward is applied to the leg portion 21. Therefore, at a plurality of locations of the leg portion 21 along the central axis C, a force that tries to expand outward is applied to the leg portion 21.

[0021] On the rod-shaped portion 3, an other-end-side protrusion 31, a head portion 32, and a one-end-side protrusion 33 are formed.

[0022] FIG. 5 is a partially enlarged cross-sectional view showing an enlarged other-end-side protrusion portion of the fastening member according to the embodiment. The other-end-side protrusion 31 protrudes from the other end 2b of the cylindrical portion 2 in the initial state where the unevenness 23 and the unevenness 34 are fitted together. The outer diameter of the other-end-side protrusion 31 is formed smaller than the inner diameter of the cylindrical portion 2, and in the initial state, it is possible to push the other-end-side protrusion 31 inside the cylindrical portion 2.

[0023] The head 32 is formed at the end of the other-end-side protruding portion 31. The head 32 is formed so as to spread outward from the other-end-side protruding portion 31 and faces the flange portion 4. By forming the head 32, when the other-end-side protruding portion 31 is pushed into the inside of the cylindrical portion 2, the head 32 abuts against the flange portion 4 and further pushing-in is restricted. That is, the head 32 functions as a stopper when the other-end-side protruding portion 31 is pushed in.

[0024] Returning to FIG. 2, in the initial state where the unevenness 23 and the unevenness 34 are fitted together, the one-end-side protruding portion 33 protrudes from the other end 2b of the cylindrical portion 2.

[0025] FIG. 6 is a partial enlarged cross-sectional view in which the B portion shown in FIG. 2 is enlarged. The outer peripheral surface of a certain range from one end 2a of the cylindrical portion 2 and the outer peripheral surface of the one-end-side protruding portion 33 are both formed so as to approach the central axis C toward the one end 2a side along the central axis C.

[0026] When the outer diameter at the base of the one-end-side protruding portion 33 is D1 and the outer diameter of the end portion on the one end 2a side of the cylindrical portion 2 is D2, the relationship is D1 > D2. With this configuration, the end portion on the one end 2a side of the cylindrical portion 2 does not protrude outside the base of the one-end-side protruding portion 33. As a result, when the fastening member 1 is inserted into a hole or the like from the one-end-side protruding portion 33, it is less likely that the end portion on the one end 2a side of the cylindrical portion 2 will be caught by the edge or the inner peripheral surface of the hole and the insertion will be hindered.

[0027] Returning to FIG. 5, the spring portion 5 is formed so as to extend from the surface of the flange portion 4 facing the one end 2a side toward the one end 2a. When the tip of the spring portion 5 is pushed into the other end 2b side and compressed, the spring portion 5 tries to restore to its original shape and exerts a biasing force in a direction away from the flange portion 4 toward the one end 2a side. Note that the shape of the spring portion 5 and the like is not limited to the example shown in FIG. 5 as long as it is configured to exert a biasing force in a direction away from the flange portion 4 toward the one end 2a side.

[0028] <Regarding the fixation of the object to be fixed by the fastening member> FIG. 7 is a perspective view showing an example of an object to be fixed by the fastening member according to the embodiment. As shown in FIG. 7, an example of the object to be fixed to the wall surface by the fastening member 1 is a cover 7 in which an operation unit or the like is formed. The cover 7 is fixed to the wall surface by being fastened to a switch box 6 provided in advance inside the wall.

[0029] The switch box 6 is a member fixed in advance inside the wall. A hole 61 through which the fastening member 1 can pass is formed in the switch box 6. A contact surface 62 against which the wall material constituting the wall abuts is formed in the switch box 6.

[0030] The cover 7 is a member fixed to the wall surface outside the wall using the fastening member 1. A hole 71 through which the fastening member 1 can pass is formed in the cover 7. A contact surface 72 against which the wall material abuts is formed in the cover 7.

[0031] FIGS. 8 and 9 are cross-sectional views for explaining the procedure of fixing an object to be fixed with the fastening member according to the embodiment.

[0032] As shown in FIG. 8, the switch box 6 is fixed in advance inside the wall with the contact surface 62 in contact with the wall material 8 constituting the wall. An opening is formed in a part of the region of the wall material 8 that overlaps the switch box 6. The cover 7 is in a state of covering the opening of the wall material 8, and the contact surface 72 is in contact with the wall material 8.

[0033] In this state, the fastening member 1 in the initial state passes through the hole 71 formed in the cover 7 and the hole 61 formed in the switch box 6. At this time, the fastening member 1 is inserted until the flange portion 4 or the spring portion 5 abuts against the cover 7. The fastening member 1 can be passed through the hole 71 and the hole 61 without the need for an operation of turning it like a screw multiple times.

[0034] From the state shown in FIG. 8, by pushing the head 32 in and moving the rod-shaped portion 3 toward one end 2a side, the state shown in FIG. 9 is obtained. As the rod-shaped portion 3 moves, a force is applied to push the leg portion 21 outward at each location where the concave portion and the convex portion are formed as described above. Due to this force, the connecting portion 25 breaks and the leg portion 21 spreads outward.

[0035] Here, between the hole 71 and the hole 61, although the surrounding is hollow, since the leg portion 21 is pressed at the portion of the hole 61, the leg portion 21 does not spread. On the other hand, on the one end 2a side rather than the portion passing through the hole 61, since there is nothing to suppress the spread, the leg portion 21 spreads. Also, since a force to push and spread is applied at the portion where the concave portion and the convex portion are formed immediately after passing through the hole 61, the leg portion 21 is bent and pushed and spread starting from the location passing through the hole 61. In this way, by pushing and spreading the leg portion 21 starting from the location passing through the hole 61, the pushed and spread leg portion 21 abuts against the edge of the hole 61, and the fastening member 1 cannot be removed. In this state, since the cover 7 is pressed against the flange portion 4 of the fastening member 1, the fixing of the cover 7 to the wall surface is completed.

[0036] Therefore, by simply passing the fastening member 1 in the initial state through the holes 71 and 61 and pushing in the head 32, the object to be fixed can be easily and reliably attached to the wall surface. Also, since a force to push and spread is applied to the leg portion 21 at each location where the concave portion and the convex portion are formed, even when the thickness of the wall material 8 is different and the distance between the holes 71 and 61 changes, the leg portion 21 is bent and pushed and spread starting from the location passing through the hole 61. Therefore, the object to be fixed can be easily and reliably attached to the wall surface regardless of the thickness of the wall material 8. Note that there may be a case where the contact surface 62 of the switch box 6 is fixed without contacting the wall material 8. For example, when the contact surface 62 is fixed to a support material provided inside the wall and supporting the wall material 8 without contacting the wall material, the wall material 8 may not be sandwiched between the switch box 6 and the cover 7. In such a case, the distance between the holes 71 and 61 varies depending on the fixing position of the switch box 6 fixed in advance inside the wall, rather than the thickness of the wall material 8. Examples of the support material for supporting the wall material include a lightweight steel frame base material.

[0037] Figure 10 is a cross-sectional view schematically showing the state of the leg portion between the hole of the switch box and the hole of the cover. In Figure 10, for ease of understanding, the change in the shape of the leg portion 21 is exaggeratedly shown.

[0038] Also, in Figure 10, the leg portion 21 in the initial state is shown by a solid line, and the leg portion 21 in the state where the head portion 32 is pushed in and expanded is shown by a dashed line.

[0039] As shown in Figure 9, on the one end 2a side rather than the portion passing through the hole 61, the leg portion 21 spreads so as to be farther away from the central axis C toward the one end 2a side. On the other hand, a force to expand by moving the rod-shaped portion 3 toward the one end 2a side is also applied to the leg portion 21 between the hole 71 and the hole 61. In the portion between the hole 71 and the hole 61, since the leg portion 21 is held by the hole 71 and the hole 61, the leg portion 21 cannot be deformed. However, as shown in Figure 10, between the hole 71 and the hole 61, since there is nothing to suppress the deformation around the middle portion, the leg portion 21 deforms so as to bulge outward.

[0040] By deforming as shown in Figure 10, the length of the leg portion 21 becomes longer between the hole 71 and the hole 61 than in the initial state. That is, the leg portion 21 extends between the hole 71 and the hole 61 compared to the initial state. When the leg portion 21 extends, a restoring force to return to the original length is generated. The restoring force generated in the leg portion 21 becomes a force to attract the switch box 6 and the cover 7, so that the cover 7 is more firmly fixed to the wall surface.

[0041] On the other hand, since this restoring force becomes a tensile force applied to the leg portion 21, if the restoring force is too large, the leg portion 21 may break. Here, when the spring portion 5 formed on the flange portion 4 is compressed, the flange portion 4 moves toward the one end 2a side, and the restoring force applied to the leg portion 21 is reduced. Thereby, breakage of the leg portion 21 is prevented. Note that when it is assumed that the leg portion 21 does not break due to the restoring force generated in the leg portion 21, the spring portion 5 may not be formed.

[0042] <Summary of effects> The fastening member 1 according to the embodiment includes a cylindrical portion 2 having a plurality of leg portions 21 divided by a plurality of slits 22 extending from one end 2a to the other end 2b in a cylindrical shape, a rod-shaped portion 3 provided inside the cylindrical portion 2 and extending along the central axis C of the cylindrical portion 2, and a flange portion 4 provided at the other end 2b of the cylindrical portion 2 and spreading outward from the opening edge on the other end 2b side of the cylindrical portion 2. A plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis C on the inner peripheral surface of the cylindrical portion 2, and a plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis C on the outer peripheral surface of the rod-shaped portion 3. The unevenness 23 formed on the inner peripheral surface of the cylindrical portion 2 and the unevenness 34 formed on the outer peripheral surface of the rod-shaped portion 3 are fitted to each other.

[0043] From the initial state in which the unevenness 23 formed on the inner peripheral surface of the cylindrical portion 2 and the unevenness 34 formed on the outer peripheral surface of the rod-shaped portion 3 are fitted, by moving the rod-shaped portion 3 along the central axis C, the convex portions of the rod-shaped portion 3 and the convex portions of the cylindrical portion 2 face each other, and the leg portions 21 are pushed outward. Since the force for pushing the leg portions 21 outward is generated at each location where the concave and convex portions are formed, the leg portions 21 are bent starting from the location where the fastening member penetrates the object to be fixed and spread outward. By spreading the leg portions 21, the fastening member 1 cannot come off. Thereby, for example, the object to be fixed can be securely and easily fixed regardless of the thickness of the wall material 8 to which the object to be fixed is fixed. Since the fastening member 1 can be inserted into the object to be fixed without the need for an operation of turning it like a screw many times, the fixing operation becomes easy and the work efficiency is improved.

[0044] Further, the rod-shaped portion 3 has an other-end-side protruding portion 31 that protrudes from the other end 2b of the cylindrical portion 2 in a state where the unevenness 23 of the cylindrical portion 2 and the unevenness 34 of the rod-shaped portion 3 are fitted. Since the other-end-side protruding portion 31 protrudes from the other end 2b of the cylindrical portion 2, by pushing in the other-end-side protruding portion 31, the rod-shaped portion 3 can be moved toward the one end 2a side to expand the leg portions 21.

[0045] Further, at the end of the other-end-side protrusion 31, a head 32 that extends outward so as to face the flange portion 4 is formed. Since the head 32 that faces the flange portion 4 is formed, the rod-shaped portion 3 will not be pushed into the one-end 2a side beyond the position where the head 32 abuts against the flange portion 42. Therefore, the amount of insertion of the rod-shaped portion 3 when fixing an object to be fixed using the fastening member 1 can be defined by the head 32.

[0046] Also, the rod-shaped portion 3 has a one-end-side protrusion 33 that protrudes from one end 2a of the cylindrical portion 2 in a state where the unevenness 23 of the cylindrical portion 2 and the unevenness 34 of the rod-shaped portion 3 are fitted together. When the outer diameter at the base of the one-end-side protrusion 33 is D1 and the outer diameter of the end portion on the one-end 2a side of the cylindrical portion 2 is D2, the relationship D1 > D2 is established. By setting the relationship D1 > D2, the end portion on the one-end 2a side of the cylindrical portion 2 will not protrude outward beyond the base of the one-end-side protrusion 33. Here, if the end portion on the one-end 2a side of the cylindrical portion 2 protrudes outward beyond the base of the one-end-side protrusion 33, when inserting the fastening member 1 into the hole of the object to be fixed, the end portion on the one-end side of the cylindrical portion 2 may get caught, causing an obstacle to the insertion operation. On the other hand, setting the relationship D1 > D2 makes it less likely for such a problem to occur.

[0047] Note that if the movement of the rod-shaped portion 3 toward the other end 2b side can be restricted by the relationship D1 > D2, it is not always necessary to restrict the movement of the rod-shaped portion 3 toward the other end 2b side by making the surface 23a and the surface 34a shown in FIG. 4 perpendicular to the central axis C. For example, the surface 23a and the surface 34a may be formed so as to move away from the central axis C as they go toward the one-end 2a side along the central axis C.

[0048] Also, a connecting portion 25 for connecting a plurality of leg portions 21 is integrally formed at one end 2a of the cylindrical portion 2. From the viewpoint of making the fastening member 1 correspond to the thicknesses of various wall materials 8, the fastening member 1 is likely to adopt an elongated shape along the central axis C. When the fastening member 1 becomes elongated, the leg portions 21 also become elongated. When the leg portions 21 become elongated, the end portion on the one end 2a side of the leg portions 21 may spread outward even in the initial state. If the end portion on the one end 2a side of the leg portions 21 spreads outward in the initial state, it is likely to become an obstacle such as being caught by the hole when inserting the fastening member 1 into the hole to be fixed. The formation of the connecting portion 25 for connecting the plurality of leg portions 21 prevents the leg portions 21 from spreading in the initial state. Note that the connecting portion 25 only needs to be formed with a strength sufficient to connect the leg portions 21 in the initial state and needs to break when the rod-shaped portion 3 is pushed in. Therefore, the leg portions 21 are formed, for example, thinner than the cylindrical portion 2 or with a shorter length in the direction along the central axis C.

[0049] Also, a plurality of irregularities 24 are formed on the outer peripheral surface of the cylindrical portion 2. When an internal thread is formed on the inner peripheral surface of a hole formed in the object to be fixed, for example, the hole 61 formed in the switch box 6, the irregularities 24 formed on the outer peripheral surface of the cylindrical portion 2 engage with the internal thread, making the fastening member 1 more difficult to come off. Thereby, it becomes possible to more firmly fix the object to be fixed by the fastening member 1.

[0050] Also, a spring portion 5 is further provided, which is formed on the one end 2a side of the flange portion 4 and exerts a biasing force in a direction away from the one end 2a side from the flange portion 4. By forming the spring portion 5 on the one end 2a side of the flange portion 4, it becomes possible to more firmly fix the object to be fixed by the biasing force of the spring portion 5. Also, it is possible to prevent the leg portions 21 from breaking due to the tensile force generated by the extension of the leg portions 21 as shown in FIG. 10.

[0051] In addition, in the structure in which the unevenness 23 formed on the inner peripheral surface of the cylindrical portion 2 and the unevenness 34 formed on the outer peripheral surface of the rod-shaped portion 3 are fitted together, the maximum outer diameter of the rod-shaped portion 3 is larger than the minimum inner diameter of the cylindrical portion 2. Therefore, it was impossible to insert the rod-shaped portion 3 into the inside of the cylindrical portion 2 later, and it was difficult to manufacture by resin molding using a mold. However, for example, if a 3D printer is used, such a structure can be easily manufactured.

[0052] As described above, some embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and the present invention can be implemented in other forms with various modifications and improvements based on the knowledge of those skilled in the art, including the aspects described in the column of the disclosure of the invention.

Explanation of Reference Numerals

[0053] 1 Fastening member 2 Cylindrical portion 2a One end 2b The other end 21 Leg portion 22 Slit 23, 24 Unevenness 23a, 23b Surfaces 25 Connecting portion 3 Rod-shaped portion 31 Protrusion on the other end side 32 Head 33 Protrusion on the one end side 34 Unevenness 34a, 34b Surfaces 4 Flange portion 5 Spring portion 6 Switch box 61 Hole 62 Contact surface 7 Cover 71 Hole 72 Contact surface 8 Wall material

Claims

1. a cylindrical part having a plurality of legs divided by a plurality of slits extending from one end to the other end in a cylindrical shape; a rod-shaped part provided inside the cylindrical part and extending along the central axis of the cylindrical part; a flange part provided at the other end of the cylindrical part and spreading outward from the opening edge on the other end side of the cylindrical part, and comprising: on the inner peripheral surface of the cylindrical part, a plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis; on the outer peripheral surface of the rod-shaped part, a plurality of concave portions and a plurality of convex portions are alternately arranged along the central axis; a fastening member in which the unevenness formed on the inner peripheral surface of the cylindrical part and the unevenness formed on the outer peripheral surface of the rod-shaped part are fitted to each other.

2. The fastening member according to claim 1, wherein the rod-shaped part has an other-end-side protruding part protruding from the other end of the cylindrical part in a state where the unevenness of the cylindrical part and the unevenness of the rod-shaped part are fitted.

3. The fastening member according to claim 2, wherein a head portion that spreads outward is formed at an end of the other-end-side protruding part so as to face the flange part.

4. The rod-shaped part has an one-end-side protruding part protruding from the one end of the cylindrical part in a state where the unevenness of the cylindrical part and the unevenness of the rod-shaped part are fitted, The fastening member according to claim 1, wherein when the outer diameter at the root of the one-end-side protruding part is D1 and the outer diameter at the end on the one-end side of the cylindrical part is D2, the relationship D1 > D2 is satisfied.

5. The fastening member according to claim 1, wherein a connecting part for connecting the plurality of legs is integrally formed at the one end of the cylindrical part.

6. The fastening member according to claim 1, wherein a plurality of unevennesses are formed on the outer peripheral surface of the cylindrical part.

7. The fastening member according to claim 1, further comprising a spring part formed on the one-end side of the flange part and exerting a biasing force in a direction away from the flange part toward the one-end side.

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