Fastening tool and fixing method of the same

Abstract

To provide a fastening tool which is fixed to a hole provided at a molding member made of thermoplastic resin and includes a penetration screw processed in a nut form, and to provide a fixing method of the fastening tool.SOLUTION: A fastening tool 1 of the invention has, in a short columnar body 2, a head 3 having an end surface a and provided on an outer peripheral surface, a plug body part 4 provided on the outer peripheral surface and having a knurl part (irregularities), a small diameter part 5, and a tip part 6. The tip part 6 is chamfered. An outer diameter of the plug body part 4 is processed so as to be smaller than an outer diameter of the head by a predetermined value. In the body 2, a female screw 7 is provided from the end surface a to the tip part 6 as a penetration screw.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 member made of thermoplastic resin, 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 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 (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 fastening and unfastening. Furthermore, a method has been proposed in which the outer peripheral surface of such fasteners is provided with knurled or other irregularities so that the fasteners bite into the holes in the molded members and are fixed with sufficient strength (for example, Patent Documents 1 and 2).

[0003] When such a fastener is fitted into a molded component, it is pressed and fitted into a boss hole provided in the molded component while being heated (to about 200°C). Utilizing the properties of this thermoplastic resin, the present inventor filed a patent application on November 4, 1993 for a fastener suitable for mass production.

[0004] However, the nut-shaped fastener disclosed in the above-mentioned application had a problem in that it could only be machined with a closed-end screw, and could not be machined with a through-thread. [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 nut-shaped fastener filed on November 4, 1993 had the problem that it could only be machined with a closed-end screw, and could not be machined with a through-thread. The object of this invention is to provide a fastener with a nut-shaped through-thread that can be fixed to a hole provided in a molded member made of thermoplastic resin, and a method for fixing the fastener. [Means for solving the problem]

[0007] Therefore, the present invention is a metal fastener having a through-thread machined into the shape of a nut which 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 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 having an outer diameter smaller than the outer diameter of the head; a small diameter portion adjacent to the plug body portion and provided on the outer peripheral surface of the cylindrical body, the small diameter portion being smaller than the outer diameter of the plug body portion; and a tip portion adjacent to the small diameter portion and provided on the outer peripheral surface of the cylindrical body, the tip portion having an outer diameter larger than the outer diameter of the small diameter portion. The present invention also relates to a method for fixing a metal fastener having a nut-like through-thread which is heated and pressurized to be fixed in a hole provided in a molded thermoplastic resin member, the fastener having a cylindrical body, a head having an outer diameter the same as the diameter of the hole, a plug body portion having a number of uneven stripes on the outer peripheral surface of the cylindrical body adjacent to the head, and an outer diameter smaller than the outer diameter of the head, a small diameter portion being provided on the outer peripheral surface of the cylindrical body adjacent to the plug body portion and having an outer diameter smaller than the outer diameter of the plug body portion, and a tip portion being provided on the outer peripheral surface of the cylindrical body adjacent to the small diameter portion and having an outer diameter larger than the outer diameter of the small diameter portion, and when the fastener is inserted into a hole provided in the molded thermoplastic resin member and the head of the fastener is heated and pressurized, the tip portion and the small diameter portion of the fastener are melted and fixed to the bottom of the hole. Effect 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 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 is provided with a short cylindrical body 2, a head 3 provided on the outer peripheral surface having an end face a, a plug portion 4 provided on the outer peripheral surface with a knurl (uneven stripes), a small diameter portion 5, and a tip portion 6. The head 3 is machined with an outer diameter that is the same as the hole diameter of the molded thermoplastic resin member described later. The head is designed according to the size of the fastener, with the hole diameter of the molded member being equal to or greater than the outer diameter of the head. This is to change the design dimensions when necessary to remove air from inside the hole when the fastener is pressed into the hole while being heated. Therefore, the head may be made smaller than the hole diameter of the molded member by a predetermined value according to 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 done by designing the tip 6 and the small diameter portion 5 so that the molten thermoplastic resin does not flow into the head 3, as will be described in detail later.

[0012] The body 2 is provided with a female thread 7 as a through thread from the end face a to the tip portion 6 . Furthermore, tip portion 6 is intended to provide the fastener with sufficient strength to pull out of the hole, and can be shaped in a variety of 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 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 m, all of which are machined. Tip 6 is chamfered. Female thread 7 is machined with 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 is formed with 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 fastener 1 is fitted into hole 13 provided in molded member 11 of thermosetting resin. Furthermore, fastener 1 of the present invention does not have plug portion 4 that scrapes the peripheral 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 the bottom of hole 13 and are embedded in the bottom of the hole and harden. This is a novel idea that is completely different from the conventional idea of ​​forcibly fitting a fastener with an outer diameter larger than the inner diameter of a hole.

[0016] Next, a method for fitting and fixing the fastener 1 into the hole 13 of the molded product member 11 in such a configuration will be described. That is, in this fitting and fixing method, the fastener 1 is heated and pressurized to be fitted into the hole 13 of the molded product member 11. First, the fastener 1 is fed into 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 in the hole 13 of the molded product member 11 with the plug body 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), and the tip 6 melts the bottom of the hole 13, 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 melting is accelerated by the addition of pressure. The molten resin at the bottom of the hole flows from the tip 6 through the small diameter portion 5 onto the knurled peripheral surface of the plug body portion 4.

[0018] FIG. 4 shows the state after the fastener 1 is heated and pressurized. The fastener 1 is fitted and fixed in the hole 13 of the molded product member 11. The fastener 1 is pressed and stopped at a position (predetermined position) where the tip portion 6 + small diameter portion 5 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 product member 11 are flush and coincident with each other (predetermined position). Conversely, by applying heat and pressure to a position (1.00 mm, the total length of the tip portion 6 + small diameter portion 5 in the embodiment) where the end face a of the fastener 1 and the end face b of the molded product member 11 are flush and coincident with each other, the tip portion 6 and small diameter portion 5 are embedded in the bottom of the hole 13. When the tip portion 6 and small diameter portion 5 are embedded in the bottom of the hole 13, the resin of the volume flows onto the knurled circumferential surface of the plug body portion 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 hole 13 melted by tip portion 6 and small diameter portion 5 flows into the knurled peripheral surface of plug portion 4, and tip portion 6 and small diameter portion 5 become embedded in the bottom of hole 13. The fastener 1 maintains its tensile strength (pulling 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 can also ensure torsional strength (rotational torque) due to the resin c that flows into and hardens around the knurled surface of the plug body portion 4. Also, 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 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 avoided.

[0020] As described above, according to the above-mentioned embodiment of the invention, it is possible to provide a fastener having a nut-like through-thread that can 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 embodiment, and can be modified in various ways without departing from the gist of the invention. The embodiments may be combined as appropriate as possible, and the combined effects can be obtained. The above embodiment includes inventions at various stages, and various inventions can be extracted by appropriate combinations of the disclosed components. For example, even if some components are deleted from all the components 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 components are deleted can be extracted as the invention. The present invention is applicable 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 in a molded thermoplastic resin member, A cylindrical body has a head having an outer diameter equal to the diameter of the hole, a plug portion having a number of projections and recesses on an outer peripheral surface of the cylindrical body adjacent to the head portion and an outer diameter smaller than the outer diameter of the head portion; a small diameter portion provided 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; a tip portion provided on an outer peripheral surface of the cylindrical body adjacent to the small diameter portion and having an outer diameter larger than the outer diameter of the small diameter portion; A fastener 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 provided in a molded thermoplastic resin member, comprising the steps of: The fastener has a cylindrical body, a head having an outer diameter equal to the diameter of the hole, a plug portion having a number of ridges on the outer peripheral surface of the cylindrical body adjacent to the head and an outer diameter smaller than the outer diameter of the head, a small diameter portion provided 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 provided on the outer peripheral surface of the cylindrical body adjacent to the small diameter portion and having 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 provided in the thermoplastic resin molded 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.

3. 3. The fastener according to claim 1, wherein the head has an outer diameter smaller by a predetermined value than the diameter of the hole provided in the molded thermoplastic resin member.

4. 3. The fastener according to claim 1, wherein the tip portion and the small diameter portion are embedded in a bottom of a hole provided in a molded member made of thermoplastic resin by melting the bottom of the hole.

5. The fastener according to claim 1 or claim 2, characterized in that when the fastener is inserted into a hole provided in the thermoplastic resin molded member and a head of the fastener is heated and pressurized, the fastener is inserted to a predetermined position.

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