Fastener and method of fixing fastener

Abstract

To provide a fastener which is fixed to a hole provided in a molded article member of a thermoplastic resin and in which a through screw is machined in a nut shape, and a fixing method of the fastener.SOLUTION: This fixture 1 has a head part 3 arranged on an outside peripheral surface having an end surface (a) in a short columnar body 2, a plug body part 4 arranged on the outside peripheral surface and having a knurl (an uneven streak), a small diameter part 5 and a tip part 6. The tip part 6 is chamfered. The outer diameter of the plug portion 4 is processed to be smaller than the outer diameter of the head portion by a predetermined value. In the main body 2, a female screw 7 is provided as a through screw from the end surface a to the tip part 6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fastener suitable for use by being fitted and fixed to a molded thermoplastic resin member, and a method for fixing the fastener. [Background technology]

[0002] Conventionally, when a screw hole is formed in a component made of a molded thermoplastic resin and a bolt or the like is screwed into the screw hole to fix it, the screw hole becomes deformed or destroyed, making it unusable, when the component is subjected to tension, twisting, vibration, or other external forces, or when the bolt or the like is repeatedly attached and detached. Therefore, nut-shaped metal fasteners (inserts) have been put to practical use, which can be fitted into holes in molded members to stably fix bolts and the like and can withstand repeated attachment and detachment. Furthermore, methods have been proposed in which the outer peripheral surface of such fasteners is provided with knurling or other irregularities so that the fasteners can bite into holes in molded members and be fixed with sufficient strength (for example, Patent Documents 1 and 2).

[0003] When such a fastener is fitted into a molded component, it is heated (to around 200°C) and pressurized into a boss hole in the molded component to fit it in. Utilizing the properties of this thermoplastic resin, the inventor filed a patent application on November 4, 2023 for a fastener suitable for mass production.

[0004] However, the nut-shaped fastener described in the above application had the problem that it could only be machined with a closed-end screw, and could not be machined with a through-thread screw. [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 mentioned above, the nut-shaped fastener filed on November 4, 2023 had the problem that it could only be processed with a closed-end screw, and could not be processed with a through-thread. The object of this invention is to provide a fastener with a nut-shaped through-thread processed therein that can be fixed to a hole provided in a thermoplastic resin molded member, and a method for fixing the fastener. [Means for solving the problem]

[0007] Therefore, the present invention provides a metal fastener having a nut-like through-thread that is heated and pressurized to be fixed into a hole in a molded thermoplastic resin member, the fastener comprising: a cylindrical body having a head having an outer diameter equal to the diameter of the hole; a plug portion having a smaller outer diameter than the head and having a number of uneven ridges on the outer peripheral surface of the cylindrical body adjacent to the head; a small-diameter portion having an outer diameter smaller than the plug portion and located on the outer peripheral surface of the cylindrical body adjacent to the plug portion; and a tip portion having an outer diameter larger than the small-diameter portion and located on the outer peripheral surface of the cylindrical body adjacent to the small-diameter portion. The present invention also provides a method for fixing a metal fastener having a nut-like threaded through-hole that is fixed by applying heat and pressure to a hole in a molded thermoplastic resin member, the fastener comprising: a cylindrical body; a head having an outer diameter equal to the diameter of the hole; a plug portion having a number of irregularities on the outer peripheral surface of the cylindrical body adjacent to the head and having an outer diameter smaller than the outer diameter of the head; a small-diameter portion located on the outer peripheral surface of the cylindrical body adjacent to the plug portion and having an outer diameter smaller than the outer diameter of the plug portion; and a tip portion located on the outer peripheral surface of the cylindrical body adjacent to the small-diameter portion and having an outer diameter larger than the small-diameter portion, wherein when the fastener is inserted into a hole in the molded thermoplastic resin member and the head of the fastener is heated and pressurized, the tip portion and small-diameter portion of the fastener melt and are fixed to the bottom of the hole. [Effects of the Invention]

[0008] The present invention can provide a fastener having a nut-like through-thread that is fastened to a hole provided in a molded member made of thermoplastic resin, and a method for fastening the fastener. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a half-sectional view showing an example of a fastener to which a first example according to an embodiment of the present invention can be applied. [Figure 2] 1 is a cross-sectional view showing the shape of a molded member to which the first embodiment can be applied. [Figure 3] FIG. 10 is a diagram showing a state in which the fastener is temporarily placed in a hole in the molded product member. [Figure 4] FIG. 10 is a diagram showing the state in which the fastener is fixed to the hole in the molded product member. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a half-sectional view showing a fastener 1 called an insert according to a first embodiment of the present invention. That is, this fastener 1 has a short cylindrical body 2, a head 3 provided on the outer peripheral surface having an end face a, a plug body portion 4 provided on the outer peripheral surface with knurling (uneven stripes), a small diameter portion 5, and a tip portion 6. The head 3 is machined with an outer diameter equal to the hole diameter of the molded thermoplastic resin member described below. The head is designed according to the size of the fastener, with the "hole diameter of the molded member ≧ the outer diameter of the head." This is done to change the design dimensions if necessary to remove air from the hole when the fastener is heated and pressurized into the hole. Therefore, the head may be made smaller than the hole diameter of the molded member by a predetermined value depending on the size of the fastener.

[0011] The outer diameter of the plug body 4 is made smaller than the outer diameter of the head by a predetermined value. This is because the tip 6 and the small diameter portion 5 are designed to prevent the molten thermoplastic resin from flowing into the head 3, as will be described in detail later.

[0012] The main body 2 is provided with a female thread 7 as a through-thread from the end face a to the tip end 6. The tip portion 6 is used to provide the fastener with sufficient strength to pull out of the hole, and can be shaped in various ways depending on the size of the fastener.

[0013] 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 tip 6) is 11.00 mm, head 3 has an outer diameter of 6.00 mm and a length of 6.00 mm, plug body 4 has an outer diameter of 5.60 mm and a length of 4.00 mm, small diameter portion 5 has an outer diameter of 4.60 mm and a length of 0.50 mm, and tip 6 has an outer diameter of 5.20 mm and a length of 0.50 mm. Tip 6 is chamfered. Female thread 7 is machined to M4. 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 thermoplastic resin. The molded member 11 is formed by providing a hole 13 in a boss 12 and providing an end face b on the upper surface of the boss 12. The hole 13 has an inner diameter of 6.00 mm and a depth of 10.00 mm.

[0015] Next, the configuration of the fastener 1 will be described in more detail. As described above, fastener 1 is provided with plug portion 4, which serves as a guide when fitting into hole 13 formed in thermosetting resin molded member 11. Furthermore, fastener 1 of the present invention does not have plug portion 4 that scrapes the circumferential surface of the hole in the molded member as in the past, but rather, as will be described in detail later, tip portion 6 and small diameter portion 5 melt into the bottom of hole 13 and solidify there. This is a novel concept that is completely different from the conventional idea of ​​forcibly fitting a fastener with an outer diameter larger than the inner diameter of the hole.

[0016] Next, a method for fitting and fixing the fastener 1 into the hole 13 of the molded member 11 in such a configuration will be described. That is, this fitting and fixing method involves applying pressure to the fastener 1 while heating it, thereby fitting it into the hole 13 of the molded member 11. First, the fastener 1 is fed into the hole 13 of the molded member 11 by a parts feeder or the like. At this time, the fastener 1 is temporarily placed in the hole 13 of the molded member 11, with the plug portion 4 acting as a guide.

[0017] As shown in Figure 3, the tip of the tip 6 of the fastener 1 rests on the bottom of the hole 13. In this state, the fastener 1 is heated and pressurized from above (top of the figure), causing the bottom of the hole 13 to melt due to the tip 6, allowing the fastener 1 to enter the hole 13. That is, the heated fastener 1 begins to melt the resin at the bottom of the hole from the tip 6, and the application of pressure accelerates the melting. The molten resin at the bottom of the hole flows from the tip 6 through the small diameter portion 5 onto the knurled surface of the plug body portion 4.

[0018] FIG. 4 shows the state of the fastener 1 after it has been heated and pressurized. The fastener 1 is fitted into and fixed in the hole 13 of the molded member 11. The fastener 1 is pressed and stopped at a position (predetermined position) where the total length of the tip portion 6 plus the small diameter portion 5 (1.00 mm) is embedded in the bottom of the hole 13. As a result, the end face a of the fastener 1 and the end face b of the molded member 11 are flush and aligned (predetermined position). Conversely, by applying heat and pressure to a position (in this embodiment, 1.00 mm, the total length of the tip portion 6 plus the small diameter portion 5) where the end face a of the fastener 1 and the end face b of the molded member 11 are flush and aligned, the tip portion 6 and the small diameter portion 5 are embedded in the bottom of the hole 13. As the tip portion 6 and the small diameter portion 5 are embedded in the bottom of the hole 13, resin corresponding to their volume flows onto the knurled surface of the plug body 4. As a result, as shown in Figure 4, the resin is pushed up to about half of the knurled part and hardens (resin c).

[0019] In this way, the resin at the bottom of the hole 13 melted by the tip portion 6 and the small diameter portion 5 flows into the knurled surface of the plug body portion 4, and the tip portion 6 and the small diameter portion 5 become embedded in the bottom of the hole 13. The fastener 1 maintains tensile strength (pull-out strength) in the hole 13 of the molded member 11 due to the resin d that melts and hardens between the tip portion 6 and the small diameter portion 5. Furthermore, the fastener 1 also ensures torsional strength (rotational torque) due to the resin c that flows onto the knurled periphery of the plug body portion 4 and hardens. Furthermore, since there is no expansion pressure from inside the boss hole 13 due to the insertion of the fastener 1 as described above, it is possible to prevent cracks that sometimes occur in the upper part of the boss 12. Furthermore, it is believed that cracks due to deterioration of the boss 12 over time can also be prevented.

[0020] As described above, according to the above-described embodiment of the present invention, it is possible to provide a fastener having a nut-like through-thread that is fastened to a hole provided in a molded thermoplastic resin member, and a method for fastening the fastener.

[0021] The present invention is not limited to the above-described embodiments and may be modified in various ways without departing from the spirit of the invention. Furthermore, the embodiments may be combined as appropriate to the extent possible, and the combined effects may be obtained. Furthermore, the above-described embodiments include inventions at various stages, and various inventions may be extracted by appropriately combining the disclosed multiple constituent elements. For example, if some constituent elements are deleted from all constituent elements shown in the embodiments, and the problem stated in the "Problem to be Solved by the Invention" section can be solved and the effects stated in the "Effects of the Invention" section can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention. The present invention applies to fasteners with an outer diameter of 30 mm or less. [Explanation of symbols]

[0022] 1...fixing device, 2...main body, 3...head, 4...plug body portion, 5...small diameter portion, 6...tip portion, 7...female thread, 11...molded member, 12...boss, 13...hole.

Claims

1. A metal fastener having a nut-shaped through-thread that is fixed by applying heat and pressure to a hole having a hole bottom provided in a thermoplastic resin molded member, a head provided on a cylindrical body; a plug portion having a number of ridges on the outer peripheral surface of the cylindrical body adjacent to the head portion, such that the molten resin at the bottom of the hole flows onto the ridges and is fixed to the hole; a small diameter portion provided adjacent to the plug body portion, the small diameter portion having an outer diameter smaller than the outer diameter of the plug body portion and embedded in the bottom of the hole; a tip portion provided adjacent to the small diameter portion, the tip portion having an outer diameter larger than the outer diameter of the small diameter portion, and embedded in the bottom of the hole; A fastener characterized by comprising:

2. A method for fixing a metal fastener having a nut-shaped through-thread that is fixed by applying heat and pressure to a hole having a hole bottom provided in a thermoplastic resin molded member, comprising: The fastener has a head provided on a cylindrical body, a plug body portion adjacent to the head and having a number of ridges on the outer peripheral surface of the cylindrical body, and is fixed to the hole when molten resin at the bottom of the hole flows onto the ridges, a small diameter portion provided adjacent to the plug body portion and embedded in the bottom of the hole with an outer diameter smaller than that of the plug body portion, and a tip portion provided adjacent to the small diameter portion and embedded in the bottom of the hole with an outer diameter larger than the outer diameter of the small diameter portion, a method for fixing a fastener, characterized in that when the fastener is inserted into a hole having a hole bottom provided in the thermoplastic resin molded member and the fastener is heated and pressurized, the tip portion and small diameter portion melt and fill the hole bottom, the resin that is melted and extruded from the hole bottom by the tip portion and small diameter portion flows onto the circumferential surface of the plug body, and the molten resin solidifies at the tip portion, small diameter portion, and the circumferential surface of the plug body, thereby fixing the fastener in the hole.

3. A metal fastener having a nut-shaped through-thread that is fixed by applying heat and pressure to a hole having a hole bottom provided in a thermoplastic resin molded member, a plug body portion having a cylindrical body and a number of ridges on an outer peripheral surface thereof, and a resin melted at the bottom of the hole flows onto the ridges to be fixed to the hole; a small diameter portion provided adjacent to the plug body portion, the small diameter portion having an outer diameter smaller than the outer diameter of the plug body portion and embedded in the bottom of the hole; a tip portion provided adjacent to the small diameter portion, the tip portion having an outer diameter larger than the outer diameter of the small diameter portion, and embedded in the bottom of the hole; A fastener characterized by comprising:

4. A method for fixing a metal fastener having a nut-shaped through-thread that is fixed by applying heat and pressure to a hole having a hole bottom provided in a thermoplastic resin molded member, comprising: The fastener has a plug body portion having a large number of ridges on the outer peripheral surface of a cylindrical main body, and is fixed to the hole by resin melted at the bottom of the hole flowing onto the ridges, a small diameter portion provided adjacent to the plug body portion and embedded in the bottom of the hole with an outer diameter smaller than that of the plug body portion, and a tip portion provided adjacent to the small diameter portion and embedded in the bottom of the hole with an outer diameter larger than that of the small diameter portion, a method for fixing a fastener, characterized in that when the fastener is inserted into a hole having a hole bottom provided in the thermoplastic resin molded member and the fastener is heated and pressurized, the tip portion and small diameter portion melt and fill the hole bottom, the resin that is melted and extruded from the hole bottom by the tip portion and small diameter portion flows onto the circumferential surface of the plug body, and the molten resin solidifies at the tip portion, small diameter portion, and the circumferential surface of the plug body, thereby fixing the fastener in the hole.

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