Fastening tool and fixing method of the same

Abstract

To provide a fastening tool which can be fixed to a hole provided at a molding member made of thermoplastic resin and enables easy cutting, 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), and a tip part 5. The tip part 5 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 6 is provided from the end surface a to the tip part 5 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 an application on November 8, 1993 for a fastener with a nut-shaped through-thread that can be fixed into a hole provided in a molded component made of thermoplastic resin.

[0004] However, the above-mentioned fastener having a nut-like 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

Problems to be Solved by the Invention

[0006] As described above, the fixture with a through-thread processed in a nut shape to be fixed to the hole provided in the molded member of the thermoplastic resin and filed on November 8, 1993 had a problem that the cutting process was complicated. The object of the present invention is to provide a fixture and a fixing method thereof that are easy to cut and fix to the hole provided in the molded member of the thermoplastic resin.

Means for Solving the Problems

[0007] Therefore, the present invention is a metal fixture with a through-thread processed in a nut shape to be fixed to the hole provided in the molded member of the thermoplastic resin by heating and pressurization, and has a head with the same outer diameter as the hole diameter of the hole on a cylindrical main body, and a plurality of concave and convex stripes on the outer circumferential surface of the cylindrical main body adjacent to this head, a plug body portion with an outer diameter smaller than the outer diameter of the head, and a tip portion provided at the tip on the outer circumferential surface of the cylindrical main body adjacent to this plug body portion. Further, the present invention is a fixing method of a metal fixture with a through-thread processed in a nut shape to be fixed to the hole provided in the molded member of the thermoplastic resin by heating and pressurization. The fixture has a head with the same outer diameter as the hole diameter of the hole on a cylindrical main body, a plurality of concave and convex stripes on the outer circumferential surface of the cylindrical main body adjacent to this head, a plug body portion with an outer diameter smaller than the outer diameter of the head, and a tip portion provided at the tip on the outer circumferential surface of the cylindrical main body adjacent to this plug body portion. When the fixture is inserted into the hole provided in the molded member of the thermoplastic resin and the head of the fixture is heated and pressurized, the bottom of the hole is melted from the tip portion of the fixture, and the melted resin flows into the plurality of concave and convex stripes on the outer circumferential surface of the plug body portion and the thread ridges of the through-thread and solidifies, so that the fixture is fixed to the hole.

Effects of the Invention

[0008] The present invention can provide a fastener that can be easily machined to be fixed into a hole provided in a molded member made of thermoplastic resin, and a method for fixing 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 head 3 provided on the outer peripheral surface of a short cylindrical body 2 having an end face a, a plug portion 4 provided on the outer peripheral surface with a knurl (uneven stripes), and a tip portion 5.

[0011] 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.

[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 by designing it 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 a hole in a molded member of thermoplastic resin, which will be described later, and can be formed into various shapes according to the size of the fastener. For example, the tip may have a smaller diameter than the outer diameter of the plug body. The body 2 is provided with a female thread 6 as a through thread from the end face a to the tip portion 5 .

[0013] The fastener 1 of this embodiment is machined to an accuracy of 1 / 100 mm. For example, the dimensions of the fastener 1 are 12.00 mm in total length (from the end face a to the tip 5), 6.00 mm in outer diameter and 6.00 mm in length for the head 3, and 5.00 mm in outer diameter and 6.00 mm in length for the plug 4, which are machined. The female thread 6 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 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 body portion 4, which serves as a guide when fastener 1 is fitted into hole 13 provided in molded member 11 made of thermosetting resin. Furthermore, fastener 1 of the present invention has plug body portion 4 that does not scrape the peripheral surface of the hole in the molded member as in the past, but melts the bottom of hole 13 from tip portion 5 and embeds itself in the bottom of the hole and hardens, as will be described in detail later. 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. Another feature of the present invention is that the molten resin from tip 5 also flows to the female thread 6 side and hardens on the threads, thereby maintaining the pull-out strength of fastener 1 relative to hole 13.

[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 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, enabling 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 and female thread 6 side of plug body portion 4 from tip 5, and the melting is accelerated by the application of pressure.

[0018] FIG. 4 shows the state of the fastener 1 after it has been heated and pressurized. The fastener 1 is fitted and fixed in the hole 13 of the molded member 11. Since the total length of the fastener 1 is 12.00 mm and the depth of the hole 13 is 10.00 mm, the fastener 1 is pressed and stopped at a position 2 mm (predetermined position) where it is embedded. As a result, the end face a of the fastener 1 and the end face b of the molded member 11 are made to coincide flatly and flush with each other (predetermined position). Conversely, by applying heat and pressure to a position where the end face a of the fastener 1 and the end face b of the molded member 11 are made to coincide flatly and flush with each other (in this embodiment, the difference between the total length of the fastener 1, 12.00 mm, and the depth of the hole 13, 10.00 mm, is 2.00 mm), the plug body portion 4 is embedded in the bottom of the hole 13 from the tip end 5 to a position 2.00 mm. By filling the bottom of hole 13 up to a position 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 hardens, 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 portion 4 from tip portion 5 flows into the knurled peripheral surface side of plug body portion 4 and also flows into the female thread 6 side, so that 2.00 mm from tip portion 5 of plug body portion 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 by 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) by the resin d that penetrates the knurled peripheral surface of the plug body portion 4 and hardens. 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 avoid 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-described embodiment of the 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 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...tip portion, 6...female thread, 11...molded member, 12...boss, 13...hole.

Claims

1. A fixing tool made of metal with a through-thread processed in a nut shape that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, having a head with an outer diameter equal to or a predetermined value smaller than the inner diameter of the above hole on a cylindrical main body, having a number of uneven stripes on the outer circumferential surface of the cylindrical main body adjacent to this head, and a plug body part with an outer diameter smaller than the outer diameter of the head by a predetermined value, and a tip part provided at the tip on the outer circumferential surface of the cylindrical main body adjacent to this plug body part, and characterized by comprising the above.

2. A fixing tool made of metal with a through-thread processed in a nut shape that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, having a head with an outer diameter equal to or a predetermined value smaller than the inner diameter of the above hole on a cylindrical main body, having a number of uneven stripes on the outer circumferential surface of the cylindrical main body adjacent to this head, and a plug body part with an outer diameter smaller than the outer diameter of the head by a predetermined value, and having a tip part provided at the tip on the outer circumferential surface of the cylindrical main body adjacent to this plug body part, and characterized in that the total length of the cylindrical main body is longer than the depth of the hole provided in the molded member.

3. A fixing method for a fixing tool made of metal with a through-thread processed in a nut shape that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, The above fixing tool has a head with an outer diameter equal to or a predetermined value smaller than the inner diameter of the above hole on a cylindrical main body, has a number of uneven stripes on the outer circumferential surface of the cylindrical main body adjacent to this head, has a plug body part with an outer diameter smaller than the outer diameter of the head, and has a tip part provided at the tip on the outer circumferential surface of the cylindrical main body adjacent to this plug body part, A method for fixing a fixture, characterized in that the fixture is inserted into a hole provided in a molded member of the thermoplastic resin, and when the head of the fixture is heated and pressurized, the bottom of the hole is melted from the tip, and the melted resin flows into a number of uneven ridges on the outer circumferential surface of the plug body portion and the thread of the through screw and solidifies, thereby fixing the fixture to the hole.

4. A method for fixing a metal fixture processed with a through screw in a nut shape that is fixed by being heated and pressurized in a hole provided in a molded member of a thermoplastic resin, The fixture has a cylindrical main body with a head having an outer diameter equal to or a predetermined value smaller than the diameter of the hole, a number of uneven ridges on the outer circumferential surface of the cylindrical main 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 on the outer circumferential surface of the cylindrical main body adjacent to the plug body portion. When the fixture is inserted into a hole provided in the molded member of the thermoplastic resin and the head of the fixture is heated and pressurized, the tip portion and a part of the plug body portion are buried in the bottom of the hole by an amount that the total length of the cylindrical main body is longer than the depth of the hole. A method for fixing a fixture, characterized in that the melted resin flows into a number of uneven ridges on the outer circumferential surface of the plug body portion and the thread of the through screw and solidifies, thereby fixing the fixture to the hole.

5. The fixture according to claim 1, claim 2, or claim 3, characterized in that the tip portion and a part of the plug body portion melt the bottom of the hole provided in the molded member of the thermoplastic resin and are buried in the bottom of the hole.

6. The fixture according to claim 1, claim 2, claim 3, or claim 4, characterized in that when the fixture is inserted into a hole provided in the molded member of the thermoplastic resin and the head of the fixture is heated and pressurized, the fixture is inserted under pressure to a predetermined position.

7. The fixing tool according to claim 1, claim 2, claim 3, or claim 4, characterized in that the resin melted from the tip to the bottom of the hole flows onto the thread of the through screw and solidifies, thereby maintaining the pulling strength of the fixing tool with respect to the hole.

8. The fixing tool according to claim 1, claim 2, claim 3, or claim 4, characterized in that the torsional strength of the fixing tool with respect to the hole is ensured by the resin that has penetrated and solidified on the circumferential surface of the concavo-convex strip of the plug body portion.

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