Fastener and molded product member

Abstract

To provide a fastener and a molded product member capable of fixing a fastener at a predetermined position on an upper surface of a boss hole when heating and pressurizing the fastener to the boss hole provided in a molded product member.SOLUTION: A fastener 1 comprises: a large diameter part 3 having an end surface a at a tip part of a short cylindrical body 2 and knurls (uneven stripes) provided on an outside peripheral surface; a small diameter part 4; a plug body part 5 having square-mesh knurls (uneven stripes) on an outside peripheral surface; and a rear end part 6. The plug body part 5 is formed into a truncated-conical shape, and its outer diameter decreases toward the rear end part 6. The rear end part 6 is further provided with a bottom hole 7 that fits with a protrusion part provided at the bottom of a hole in a molded product member, which will be described later. The body 2 is also provided with a closed-end female screw 8 extending from the end surface a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fastener and a molded member suitable for use by being fitted and fixed into the molded member made of synthetic resin. [Background technology]

[0002] Conventionally, when a screw hole is formed in a component made of a synthetic resin molded product and a bolt or the like is screwed in to fix the component, the screw hole becomes deformed or destroyed and becomes unusable when the component is subjected to tension, torsion, vibration or other external forces, or when the bolt or the like is repeatedly attached and removed. Therefore, nut-shaped metal fasteners have been put to practical use, which can be fitted into holes in molded members such as synthetic resins to stably fix bolts and the like and can withstand repeated fastening and unfastening. Furthermore, a method has been proposed in which the outer peripheral surface of the fastener is provided with knurling or other irregularities so that the fastener bites into the hole in the molded member and is fixed with sufficient strength (for example, Patent Documents 1 and 2).

[0003] When such a fastener is fitted into a molded member, the fastener is heated (at about 200°C) and pressurized into a boss hole provided in the molded member to fit it in. Conventionally, when a molded member has six boss holes, such as in a smartphone, each hole has been heated and pressurized one by one. In recent years, with the trend towards automation, for example, if there is a molded product member with six boss holes, there is an increasing demand to be able to insert six fasteners at once.

[0004] However, when a prototype was made to meet such demands, and six heating and pressure rods were installed in six holes and heating and pressure were applied, slight temperature unevenness in the heating and pressure rods repeatedly resulted in the fasteners being deeply embedded in the holes, some not fully entering the holes and floating on the top surface of the holes, and some with molten synthetic resin protruding from the holes, and there were problems with the fasteners not being able to be inserted evenly into each hole onto the top surface of the boss hole of the molded product component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 50-85756 [Patent Document 2] Japanese Unexamined Patent Publication No. 58-124809 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, when a fastener is inserted into a boss hole provided in a molded product member by applying heat and pressure in the process of automation, there has been a problem in that the fastener cannot be fixed in a predetermined position on the upper surface of the boss hole. An object of the present invention is to provide a fastener and a molded member that can fix the fastener in a predetermined position on the top surface of a boss hole provided in the molded member when the fastener is inserted into the boss hole through the application of heat and pressure. [Means for solving the problem]

[0007] Therefore, the present invention is a fastener to be fixed to a hole provided in a molded synthetic resin member, comprising a large diameter portion having a number of uneven ridges on the outer peripheral surface of a cylindrical main body and an outer diameter larger than the diameter of the hole, a small diameter portion having an outer diameter smaller than the outer diameter of the large diameter portion and provided on the outer peripheral surface of the cylindrical main body adjacent to the large diameter portion, and a plug portion having a number of uneven ridges on the outer peripheral surface of the cylindrical main body adjacent to the small diameter portion, the outer diameter of which decreases at a predetermined gradient in a truncated cone shape, with the side in contact with the small diameter portion being the maximum outer diameter. The present invention also relates to a fastener and a molded product member to be fixed to a hole provided in a molded product member of a synthetic resin, the fastener having a number of uneven ridges on the outer peripheral surface of a cylindrical main body, a large diameter portion having an outer diameter larger than the diameter of the hole, a small diameter portion having an outer diameter smaller than the outer diameter of the large diameter portion and provided on the outer peripheral surface of the cylindrical main body adjacent to the large diameter portion, and a plug body portion having a number of uneven ridges on the outer peripheral surface of the cylindrical main body adjacent to the small diameter portion, the outer diameter of which decreases at a predetermined gradient in a truncated cone shape from the side contacting the small diameter portion to the maximum outer diameter, and a bottom hole provided with a predetermined depth and size at the rear end of the plug body portion where the outer diameter is reduced, and the molded product member has a protrusion at the bottom of the hole that fits into the bottom hole. Effect of the Invention

[0008] The present invention makes it possible to provide a fastener and a molded member that can fix the fastener at a predetermined position on the top surface of a boss hole provided in the molded member when the fastener is inserted into the boss hole through the application of heat and pressure. [Brief description of the drawings]

[0009] [Figure 1] 1 is a half-sectional view showing an example of a fastener to which a first embodiment according to the present invention can be applied. [Diagram 2] FIG. 2 is a cross-sectional view showing the shape of a molded member to which the first embodiment can be applied. [Diagram 3] FIG. 13 is a diagram showing the state in which the fastener is temporarily placed in the hole of the molded product member. [Figure 4] FIG. 4 is a diagram showing the state in which the fastener is fixed in a hole in the molded product member. [Diagram 5] FIG. 11 is a cross-sectional view showing the shape of a conventional molded product member. [Figure 6] FIG. 4 is a cross-sectional view showing an independently molded protrusion. [Figure 7] FIG. 11 is a half-sectional view showing an example of a fastener to which the second embodiment can be applied. [Figure 8] FIG. 11 is a diagram showing a state in which a fastener according to a second embodiment is temporarily placed in a hole in a molded product member. [Figure 9]FIG. 11 is a diagram showing the state in which the fastener of the second embodiment is fixed in a hole in a molded product member. [Figure 10] FIG. 13 is a half-sectional view showing an example of a fastener to which the third embodiment can be applied. [Figure 11] FIG. 11 is a cross-sectional view of a disk used in the third embodiment. [Figure 12] FIG. 13 is a view showing a state in which a disk is temporarily fixed to the rear end portion of the fastener of the third embodiment. [Figure 13] FIG. 11 is a diagram showing a state in which a fastener according to a third embodiment is temporarily placed in a hole in a molded product member. [Figure 14] FIG. 11 is a diagram showing the state in which the fastener of the third embodiment is fixed in a hole in a molded product member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a half-side cross-sectional view showing a fastener 1 called an insert according to a first embodiment of the present invention. That is, this fastener 1 is provided with a large diameter portion 3 having an end face a at the tip of a short cylindrical main body 2 and having a knurl (uneven stripes) on the outer peripheral surface, a small diameter portion 4, a plug body portion 5 having a square mesh knurl (uneven stripes) on the outer peripheral surface, and a rear end portion 6. The plug body portion 5 has a truncated cone shape with the maximum outer diameter on the side in contact with the small diameter portion 4, and the outer diameter decreases toward the rear end portion 6. Therefore, in this embodiment, the angle of the gradient is 1 degree. The angle of this gradient is processed in the range of 0.1 degrees to 5 degrees depending on the size and material of the fastener. In addition, the maximum outer diameter of the plug body portion 5 is processed to be the same as or smaller than the hole diameter of the molded product member described later.

[0011] In addition, a 42-degree chamfer is applied along the rear end 6 of the plug body 5. This chamfer is applied at 42 degrees to facilitate the flow of molten synthetic resin, which will be described later, around the periphery of the plug body 5, but this can be adjusted between 40 degrees and 45 degrees depending on the size of the fastener. Furthermore, a bottom hole 7 is provided in the rear end 6 with a predetermined depth and size so as to fit with a protrusion provided at the bottom of a hole in a molded product member, which will be described later. Further, the main body 2 is provided with a female screw 8 at a closed end from an end face a.

[0012] The fastener 1 of this embodiment is machined to an accuracy of 1 / 100 mm. For example, the dimensions of fastener 1 are as follows: total length (from end face a to rear end 6) is 10.00 mm, large diameter portion 3 has an outer diameter of 7.00 mm and a length of 2.00 mm, small diameter portion 4 has an outer diameter of 6.00 mm and a length of 0.50 mm, plug portion 5 has a maximum outer diameter of 6.80 mm and a length of 7.50 mm on the side in contact with small diameter portion 4, and bottom hole 7 has an inner diameter of 2.00 mm and a depth of 0.50 mm. The bottom of bottom hole 7 is machined to have an R. The female thread 8 is machined with M4.

[0013] Although the fastener 1 is made of brass in this embodiment, metals such as stainless steel, carbon steel, aluminum, and zinc may also be used.

[0014] 2 is a cross-sectional view showing an example of the configuration of a molded member 11 molded from a synthetic resin. The molded member 11 has a hole 13 formed in advance in a boss 12 formed to protrude, and a protrusion 14 provided at the bottom of the hole. The protrusion 14 is provided so as to fit into the bottom hole 7 of the fastener 1. The tip of the boss 12 has an end face b. That is, the hole 13 provided in the boss 12 in this embodiment is formed with a hole diameter that is a predetermined value smaller than the outer diameter of the large diameter portion 3 and is larger than or equal to the maximum outer diameter of the plug portion 5. Specifically, the hole 13 is formed with an inner diameter of 6.80 mm and a depth of 10.50 mm. The protrusion 14 has an outer diameter of 2.00 mm and is formed to a height of 1.50 mm from the bottom of the hole 13. The protrusion 14 is cylindrical, but is not limited to this shape and may be, for example, a cylinder with a dome-shaped tip. The point is that it is sufficient if it is easily melted by the heat and pressure described below.

[0015] Next, the configuration of the fastener 1 will be described in more detail. As described above, fastener 1 is provided with plug body portion 5, which serves as a guide when fastener 1 is fitted into hole 13 provided in synthetic resin molded member 11. Furthermore, fastener 1 of the present invention is not one in which plug body portion 5 scrapes the peripheral surface of the hole in the molded member as in the past, but rather, as will be described in detail later, synthetic resin molten from the bottom surface of the hole hardens so as to envelop plug body portion 5. This is a novel concept that is completely different from conventional fasteners.

[0016] Next, a method for fitting the fastener 1 into the hole 13 of the molded product member 11 in such a configuration will be described. That is, this fitting method involves fitting the fastener 1 into the hole 13 of the molded product member 11 by applying pressure while heating it. First, the fastener 1 is fed to the hole 13 of the molded product member 11 by a parts feeder or the like. At that time, the fastener 1 is temporarily placed above the hole 13 of the molded product member 11 with the plug portion 5 acting as a guide. As shown in FIG. 3, the large diameter portion 3 is stopped at the upper portion of the hole 13 . In this state, fastener 1 is heated and pressurized from above (top of the figure), allowing large diameter portion 3 of fastener 1 to enter hole 13, and at the same time bottom hole 7 is heated and pressurized to melt protrusion 14. When protrusion 14 melts, the molten synthetic resin is forced upward from the bottom of hole 13 and rear end 6 of fastener 1, via the chamfered portion of plug body 5, and flows onto the knurled peripheral surface of plug body 5.

[0017] FIG. 4 shows the state of the fastener 1 after it has been heated and pressurized. The fastener 1 is fitted into the hole 13 of the molded member 11. Since it is pressurized to a predetermined position, the end face a of the fastener 1 and the top face b of the molded member 11 are flush and aligned (predetermined position). Since the fastener 1 is pressurized to a predetermined position, it does not bite into the hole 13 beyond that position. Also, the synthetic resin melted by the protrusions 14 flows and cools and hardens at a position approximately halfway through the plug body 5. Therefore, the synthetic resin does not overflow from the hole 13. In the worst case, the synthetic resin does not overflow because of the small diameter portion 4. The synthetic resin that has flowed into the peripheral surface of the plug body 5 bites into the square mesh knurling, so the fastener 1 is fixed in the hole 13. As a result, the fastener 1 maintains the tensile strength to the hole 13 of the molded member 11, and further, with the large diameter portion 3 being added, the torsional strength (rotational torque) can be ensured. Also, because the expansion pressure from inside the boss hole 13 caused by the insertion of the above-mentioned fastener 1 is weaker than in the past, it is possible to avoid cracks that sometimes occur in the upper part of the boss 12. Furthermore, it is believed that cracks due to aging can also be avoided.

[0018] Next, a second embodiment will be described. 5 shows a conventional molded product member 21 having a hole 23 in a boss 22 and an end face c on the upper surface of the boss 22. The present application can also be applied to such conventional molded products having holes. 6 is a cross-sectional view showing an independently molded protrusion 30 which replaces the protrusion 14 shown in the first embodiment. The protrusion 30 has an outer diameter of 2.00 mm, a height of 1.50 mm, and is provided with a flange portion 31 having an outer diameter of 3.00 mm and a thickness of 0.50 mm. The protrusion 30 is molded with a predetermined volume from the same material as the molded product member 21. The predetermined volume here is determined by the melted volume and the amount that flows onto the peripheral surface of the plug body portion 5, which will be described later.

[0019] 7 shows a fastener 1 applied to a hole 22 in a conventional molded member 21. A protrusion 30 made of the same synthetic resin material as the molded member 21 is attached to the bottom hole 7 of the fastener 1 with adhesive or the like. In this state, the fastener 1 is supplied to the hole 23 in the molded member 21 by a parts feeder or the like. 8 is a diagram showing the supplied fastener 1 in a temporarily placed state above the hole 23 of the molded product member 21. In this state, the fastener 1 is heated and pressurized from above (top of the figure), allowing the large diameter portion 3 of the fastener 1 to enter the hole 23, and at the same time, the protrusion 30 is melted from the bottom hole 7 of the fastener 1. When the protrusion 30 melts, the molten synthetic resin is forced upward from the bottom of the hole 23 and the rear end portion 6 of the fastener 1, via the chamfered portion of the plug body portion 5, and flows onto the knurled peripheral surface of the plug body portion 5.

[0020] FIG. 9 shows the state after the fastener 1 is heated and pressurized. The fastener 1 is fitted into the hole 23 of the molded member 21. The fastener 1 is pressurized to a predetermined position, so that the end face a of the fastener 1 and the top face c of the molded member 21 are flush with each other (predetermined position). This is because the fastener 1 is pressurized to a predetermined position, so it does not bite into the hole 23 beyond that position. Also, the synthetic resin melted by the protrusions 30 flows and cools and hardens at a position approximately halfway through the plug body 5. Therefore, the synthetic resin does not overflow from the hole 23. In the worst case, the synthetic resin does not overflow because of the small diameter portion 4. The synthetic resin that has flowed into the peripheral surface of the plug body 5 bites into the square mesh knurling, so the fastener 1 is fixed in the hole 23. As a result, the fastener 1 maintains the tensile strength in the hole 23 of the molded member 21, and further, the addition of the large diameter portion 3 ensures the torsional strength (rotational torque). Also, because the expansion pressure from inside the boss hole 23 caused by the insertion of the above-mentioned fastener 1 is weaker than in the past, it is possible to avoid cracks that sometimes occur in the upper part of the boss 22. Furthermore, it is believed that cracks due to deterioration over time can also be avoided.

[0021] Next, a third embodiment will be described. FIG. 10 is a half-side cross-sectional view showing a fastener 41 called an insert according to a third embodiment. That is, this fastener 41 is provided with a large diameter portion 43 having an end face d at the tip of a short cylindrical body 42 and having a knurl (uneven stripes) on the outer peripheral surface, a small diameter portion 44, a plug body portion 45 having a square-mesh knurl (uneven stripes) on the outer peripheral surface, and a rear end portion 46. The plug body portion 45 is in a truncated cone shape with the maximum outer diameter on the side in contact with the small diameter portion 44, and the outer diameter becomes smaller toward the rear end portion 46. Therefore, the angle of the gradient is 1 degree in the figure. The gradient angle is machined in the range of 0.1 degrees to 5 degrees depending on the size and material of the fastener.

[0022] In addition, a 42-degree chamfer is applied along the rear end surface 46 of the plug body portion 45. This chamfer is applied at an angle of 42 degrees to facilitate the flow of molten synthetic resin, which will be described later, onto the peripheral surface of the plug body portion 45, but this angle can be adjusted between 40 degrees and 45 degrees depending on the size of the fastener. Further, the main body 42 is provided with a female screw 47 as a through screw from the end face d.

[0023] The fastener 1 of this embodiment is machined to an accuracy of 1 / 100 mm. For example, the dimensions of fastener 41 are machined to have a total length (from end face d to rear end face 46) of 10.00 mm, large diameter portion 43 with an outer diameter of 7.00 mm and a length of 2.00 mm, small diameter portion 44 with an outer diameter of 6.00 mm and a length of 0.50 mm, and plug portion 45 with a maximum outer diameter of 6.80 mm on the side in contact with small diameter portion 44 and a length of 7.50 mm. Female thread 47 is machined with M4. Although the fastener 41 is made of brass in this embodiment, metals such as stainless steel, carbon steel, aluminum, and zinc may also be used.

[0024] 11 is a cross-sectional view of a disk 51 used in this embodiment. The disk 51 is composed of a fitting portion 52 and a sealing portion 53. This disk 51 is machined to an accuracy of 1 / 100 mm, with the fitting portion 52 having an outer diameter of 4.00 mm and a length of 0.60 mm, and the sealing portion 53 having an outer diameter of 6.00 mm and a length of 0.40 mm. The disk 51 may also be formed by pressing. A predetermined amount of resin 54 is attached to the sealing portion 53 of the disk 51 with adhesive or the like. The resin 54 is made of the same synthetic resin material as the molded product member 21 shown in Fig. 5. The "predetermined amount" here is determined by the melted volume and the amount that flows onto the peripheral surface of the plug portion 45, which will be described later. The resin 54 may be a thermoplastic adhesive. The point is that it must melt and flow when heated and harden when cooled.

[0025] 12 is a diagram showing a state in which the disk 51 is temporarily fixed from the rear end portion 46 of the fastener 41. That is, the fitting portion 52 of the disk 51, which has an outer diameter of 4.00 mm, is fitted into the through-thread M4, which is the female thread 47 of the fastener 41, and the fastener 41 is temporarily fixed. FIG. 13 is a diagram showing a state in which the fastener 41 is temporarily placed above the hole 23 of the molded product member 21. As shown in FIG. In this state, fastener 41 is heated and pressurized from above (top of the figure), allowing large diameter portion 43 of fastener 41 to enter hole 23, and at the same time melting resin 54 of disk 51 temporarily fixed to fastener 41. When resin 54 melts, the molten resin is forced upward from the bottom of hole 23 and sealing portion 53 of disk 51, via the chamfered portion of plug portion 45, and flows onto the knurled peripheral surface of plug portion 45.

[0026] FIG. 14 shows the state after the fastener 41 is heated and pressurized. The fastener 41 is fitted into the hole 23 of the molded member 21. The fastener 41 is pressurized to a predetermined position, so that the end face d of the fastener 41 and the upper face c of the molded member 21 are flush with each other (predetermined position). This is because the fastener 41 is pressurized to a predetermined position, so that it does not bite into the hole 23 beyond that position. Also, the molten resin 54 flows and cools and hardens at a position approximately halfway through the plug body portion 45. Therefore, the resin does not overflow from the hole 23. In the worst case, the resin does not overflow because of the small diameter portion 44. The resin that has flowed into the peripheral surface of the plug body portion 45 bites into the square mesh knurling, so the fastener 41 is fixed to the hole 23. As a result, the fastener 41 maintains the tensile strength to the hole 23 of the molded member 21, and further, the addition of the large diameter portion 43 ensures the torsional strength (rotational torque). Also, because the expansion pressure from inside the boss hole 23 caused by the insertion of the above-mentioned fastener 41 is weaker than in the past, it is possible to avoid cracks that sometimes occur in the upper part of the boss 22. Furthermore, it is believed that cracks due to deterioration over time can also be avoided.

[0027] As described above, according to the above-mentioned embodiment of the invention, it is possible to provide a fastener and a molded product member that can fix the fastener in a predetermined position on the upper surface of a boss hole provided in the molded product member when the fastener is inserted into the boss hole through application of heat and pressure.

[0028] The present invention is not limited to the above embodiment, and can be modified in various ways in the implementation stage without departing from the gist of the invention. The embodiments may be implemented in combination as appropriate as possible, and in that case, the combined effects can be obtained. Furthermore, the above embodiment includes inventions at various stages, and various inventions can be extracted by appropriate combinations of the disclosed multiple constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, if the problem described in the "Problem to be Solved by the Invention" column can be solved and the effect described in the "Effect of the Invention" column can be obtained, the configuration from which the constituent elements are deleted can be extracted as the invention. Furthermore, this invention is the result of the inventor's long-held contemplation of a completely new fastener, which he came up with on April 8th of this year, and after repeated trials, has finally been completed. [Explanation of symbols]

[0029] 1,41...fixing device, 2,42...main body, 3,43...large diameter portion, 4,44...small diameter portion, 5,45...plug body portion, 6,46...rear end portion, 7...bottom hole, 8,47...female thread, 11,21...molded member, 12,22...boss, 13,23...hole, 14,30...projection portion, 51...disc, 52...fitting portion, 53...sealing portion.

Claims

1. A fastener to be fixed to a hole provided in a synthetic resin molded member, a large diameter portion having a large number of projections and recesses on an outer peripheral surface of a cylindrical body and an outer diameter larger than a diameter of the hole; a plug portion having a large number of projections and recesses on an outer peripheral surface of the cylindrical body adjacent to the large diameter portion, the plug portion having a maximum outer diameter on the side in contact with the large diameter portion and an outer diameter that decreases at a predetermined gradient in a truncated cone shape; A fastener comprising:

2. A fastener to be fixed to a hole provided in a synthetic resin molded member, a large diameter portion having a large number of projections and recesses on an outer peripheral surface of a cylindrical body and an outer diameter larger than a diameter of the hole; a small diameter portion provided on an outer peripheral surface of the cylindrical body adjacent to the large diameter portion, the small diameter portion having an outer diameter smaller than the outer diameter of the large diameter portion; a plug portion having a number of ridges and grooves on an outer peripheral surface of the cylindrical body adjacent to the small diameter portion, the plug portion having a maximum outer diameter on the side in contact with the small diameter portion and an outer diameter that decreases at a predetermined gradient in a truncated cone shape; A fastener comprising:

3. 3. The fastener according to claim 1, wherein the inclination of the plug portion is from 0.1 to 5 degrees.

4. 3. The fastener according to claim 1, wherein the maximum outer diameter of the plug body is equal to or smaller than the diameter of the hole.

5. A fastener that is fixed to a hole provided in a synthetic resin molded member and the molded member, The fastener has a large diameter portion having an outer diameter larger than the diameter of the hole, a small diameter portion provided on the outer peripheral surface of the cylindrical body adjacent to the large diameter portion and having an outer diameter smaller than the outer diameter of the large diameter portion, a plug portion having a large number of uneven portions on the outer peripheral surface of the cylindrical body adjacent to the small diameter portion, the plug portion having an outer diameter that decreases at a predetermined gradient in a truncated cone shape from the side in contact with the small diameter portion, and a bottom hole provided with a predetermined depth and size at the rear end of the plug portion where the outer diameter is reduced, A fastener and a molded member, wherein the molded member has a protrusion at the bottom of the hole that fits into the bottom hole.

6. A fastener to be fixed to a hole provided in a synthetic resin molded member, a large diameter portion having a large number of projections and recesses on an outer peripheral surface of a cylindrical body and an outer diameter larger than a diameter of the hole; a small diameter portion provided on an outer peripheral surface of the cylindrical body adjacent to the large diameter portion, the small diameter portion having an outer diameter smaller than the outer diameter of the large diameter portion; a plug portion having a number of ridges and grooves on an outer peripheral surface of the cylindrical body adjacent to the small diameter portion, the plug portion having a maximum outer diameter on the side in contact with the small diameter portion and an outer diameter that decreases at a predetermined gradient in a truncated cone shape; A bottom hole having a predetermined depth and size is provided at the rear end of the plug body portion where the outer diameter is reduced; a protrusion of a predetermined amount made of the same material as the molded product member, which is fitted into and bonded to the bottom hole; A fastener comprising:

7. A fastener to be fixed to a hole provided in a synthetic resin molded member, a large diameter portion having a large number of projections and recesses on an outer peripheral surface of a cylindrical body and an outer diameter larger than a diameter of the hole; a small diameter portion provided on an outer peripheral surface of the cylindrical body adjacent to the large diameter portion, the small diameter portion having an outer diameter smaller than the outer diameter of the large diameter portion; a plug portion having a number of ridges and grooves on an outer peripheral surface of the cylindrical body adjacent to the small diameter portion, the plug portion having a maximum outer diameter equal to the diameter of the hole and a predetermined gradient in outer diameter in a truncated cone shape; a disk including a fitting portion fitted into the rear end portion of the plug portion where the outer diameter is reduced, and a sealing portion made of the same material as the molded product member and bonded with a predetermined amount of synthetic resin; A fastener comprising:

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