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 facilitates cutting work, and a method for fixing the fastener.SOLUTION: This fixture 1 is provided with a head part 3 provided on an outside peripheral surface having an end surface (a) in a short columnar body 2, a plug body part 4 provided on the outside peripheral surface and having a knurl (an uneven line), and a tip part 5. The tip part 5 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. The body 2 is provided with an internal thread 6 as a through-thread from the end face a to the tip 5.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 to fit into a boss hole in the molded component. Utilizing the properties of this thermoplastic resin, the inventor filed a patent application on November 8, 2023, for a fastener with a nut-shaped through-thread that can be fixed into a hole in a molded thermoplastic resin component.

[0004] However, the above-mentioned fastener having a nut-shaped through-thread has a problem in that the cutting process is complicated. [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, the fastener with a nut-shaped through-thread that is fastened to a hole in a thermoplastic resin molded member, filed on November 8, 2023, has the problem that cutting is complicated. The object of this invention is to provide a fastener that can be easily cut to be fastened to a hole in a thermoplastic resin molded member, and a fastener fixing method. [Means for solving the problem]

[0007] Therefore, the present invention provides a metal fastener having a nut-like through-thread that is fixed by heating and pressurizing into a hole in a thermoplastic resin molded member, and is equipped with a cylindrical body having a head with an outer diameter the same as the diameter of the hole, a plug body portion adjacent to the head and having a number of uneven stripes on the outer peripheral surface of the cylindrical body and an outer diameter smaller than the outer diameter of the head, and a tip portion adjacent to the plug body portion and provided at the tip of the outer peripheral surface of the cylindrical body. The present invention also provides a method for fixing a metal fastener having a nut-shaped through-thread that is heated and pressurized to be fixed in a hole in a thermoplastic resin molded member, the fastener having a cylindrical body, a head having an outer diameter the same as the diameter of the hole, a number of ridges on the outer peripheral surface of the cylindrical body adjacent to the head, a plug body portion having an outer diameter smaller than the outer diameter of the head, and a tip portion provided at the tip of the outer peripheral surface of the cylindrical body adjacent to the plug body portion, when the fastener is inserted into a hole in the thermoplastic resin molded member and the head of the fastener is heated and pressurized, the tip portion of the fastener melts down to the bottom of the hole, and the molten resin flows into the number of ridges on the outer peripheral surface of the plug body portion and into the threads of the through-thread, where it solidifies, thereby fixing the fastener in the hole. [Effects of the Invention]

[0008] The present invention can provide a fastener that can be easily machined to be fixed to a hole provided in a molded member made of thermoplastic resin, and a method for fixing 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 4 provided on the outer peripheral surface with knurling (uneven stripes), and a tip 5.

[0011] 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.

[0012] The outer diameter of the plug body 4 is made smaller than the outer diameter of the head by a predetermined value. This is done so that the molten thermoplastic resin from the tip 5 does not flow into the head 3, as will be described in detail later. The tip 5 is chamfered. The tip 5 is used to melt the bottom of the hole in the thermoplastic resin molded product described below, and can be formed into various shapes depending on the size of the fastener. For example, the tip may have a smaller diameter than the outer diameter of the plug body. The main body 2 is provided with a female screw 6 as a through screw from the end face a to the tip 5 .

[0013] The fastener 1 of this embodiment is machined to an accuracy of 1 / 100 mm. For example, the dimensions of fastener 1 are 12.00 mm in total length (from end face a to tip 5), 6.00 mm in outer diameter and 6.00 mm in length for head 3, and 5.00 mm in outer diameter and 6.00 mm in length for plug 4. The female thread 6 is machined to M4. Although the fastener 1 is made of brass in this embodiment, other 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, melts from tip portion 5 into the bottom of hole 13 and embeds itself in the bottom of the hole, solidifying. 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. Another feature of the present invention is that the resin melted from the tip 5 flows to the female thread 6 side and hardens on the threads, thereby maintaining the pull-out strength of the fastener 1 relative to the hole 13.

[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 5 of fastener 1 rests on the bottom of hole 13. In this state, fastener 1 is heated and pressurized from above (top of the figure), causing the bottom of hole 13 to melt from tip 5, allowing fastener 1 to enter hole 13. That is, the heated fastener 1 begins to melt the resin at the bottom of the hole that contacts the knurled peripheral surface side of plug body portion 4 and the female thread 6 side from tip 5, and the melting is accelerated by the application of pressure.

[0018] FIG. 4 shows the state of fastener 1 after it has been heated and pressurized. Fastener 1 is fitted into hole 13 in molded member 11 and secured therein. Since fastener 1 has a total length of 12.00 mm and hole 13 has a depth of 10.00 mm, fastener 1 is pressed down to a position 2 mm (predetermined position) where it is embedded. As a result, end face a of fastener 1 and end face b of molded member 11 are flush and coincident (predetermined position). Conversely, by applying heat and pressure to a position where end face a of fastener 1 and end face b of molded member 11 are flush and coincident (in this embodiment, the difference between the total length of fastener 1, 12.00 mm, and the depth of hole 13, 10.00 mm, is 2.00 mm), plug body portion 4 is embedded in the bottom of hole 13 from tip 5 to a position 2.00 mm. By filling the bottom of hole 13 up to 2.00 mm from tip 5 of plug body 4, that volume of resin flows toward the knurled surface of plug body 4. As a result, it is pushed up to resin d on the knurled surface and solidifies, as shown in Figure 4. However, resin c that flows and penetrates toward female thread 6 does not remain in a clean state as shown in the figure, and furthermore, it is unavoidable from a structural standpoint that the range of motion of the M4 bolt is narrowed by the resin filling the threads.

[0019] In this way, the resin at the bottom of hole 13 melted by plug body 4 from tip 5 flows into the knurled peripheral surface of plug body 4 and also flows into the female thread 6 side, so that 2.00 mm from tip 5 of plug body 4 is buried in the bottom of hole 13. The fastener 1 maintains tensile strength (pull-out strength) to the hole 13 of the molded member 11 due to the resin c that melts on the female thread 6 side, penetrates the threads, and hardens. Furthermore, the fastener 1 can also ensure torsional strength (rotational torque) due to the resin d that penetrates the knurled circumferential surface 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 described above, it is possible to avoid cracks that sometimes occur in the upper part of the boss 12. Furthermore, it is thought that cracks due to deterioration of the boss 12 over time can also be avoided.

[0020] As described above, according to the above-described embodiment of the present invention, it is possible to provide a fastener that can be easily machined to be fixed into a hole provided in a molded thermoplastic resin member, and a method for fixing 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...tip portion, 6...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, the plug portion being fused to the bottom of the hole and partially embedded in the bottom of the hole, and the resin molten at the bottom of the hole flows onto the ridges and is fixed to the hole; a tip portion provided adjacent to the plug portion at the tip of the outer circumferential surface of the cylindrical main body 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 portion provided on a cylindrical main body, a plug portion adjacent to the head portion and having a number of ridges on the outer peripheral surface of the cylindrical main body, the plug portion melting into the bottom of the hole and partially filling the hole bottom, and the resin melted at the bottom of the hole flows onto the ridges and is fixed to the hole, and a tip portion adjacent to the plug portion and provided at the tip of the outer peripheral surface of the cylindrical main body, the tip portion being filled into the hole bottom, 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 and a part of the plug body melt and fill the hole bottom, and this molten resin flows into the numerous uneven ridges on the outer peripheral surface of the plug body and into the threads of the through screw, and hardens, 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 large number of ridges on the outer peripheral surface of a cylindrical main body, the plug body portion being fixed to the hole by melting the bottom of the hole and partially filling the bottom of the hole, and the resin melted at the bottom of the hole flows onto the ridges and is fixed to the hole; a tip portion provided adjacent to the plug portion at the tip of the outer circumferential surface of the cylindrical main body 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, the plug body portion being melted at the bottom of the hole to partially fill the bottom of the hole, and the resin melted at the bottom of the hole flows onto the ridges and is fixed to the hole, and a tip portion is provided adjacent to the plug body portion at the tip of the outer peripheral surface of the cylindrical main body, and is embedded in the bottom of the hole, 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 and a part of the plug body melt and fill the hole bottom, and this molten resin flows into the numerous uneven ridges on the outer peripheral surface of the plug body and into the threads of the through screw, and hardens, thereby fixing the fastener in the hole.

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