Fastening tool and fixing method of the same

Abstract

To provide a fastening tool which is suitable for mass production and can be fixed to a hole provided at a molding member made of thermoplastic resin, and to provide a fixing method of the fastening tool.SOLUTION: A fastening tool 1 of the invention is provided having, in a short columnar body 2, a head 3 having an end surface a and provided on an outer peripheral surface, a small diameter part 4, a plug body part 5 provided on the outer peripheral surface and having a knurl part (irregularities) having a rectangular net form, a rear end part 6, and an anchor 7 (an anchor part) comprising a shank 7a and an anchor head 7b. The anchor head 7b of the anchor 7 is cut in a cone shape in which a gradient surface is curved to the core side to be recessed. The plug body part 5 has a truncated cone shape, in which the side contacting with the small diameter part 4 has a maximum outer diameter, and its outer diameter is reduced toward the rear end part 6. An angle of a gradient of the truncated cone shape is set to 10 degrees.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fixture suitable for being fitted and fixed to a molded member of a thermoplastic resin for mass production, and a method for fixing the fixture.

Background Art

[0002] Conventionally, when a screw hole is formed in a member made of a molded product of a thermoplastic resin and a bolt or the like is screwed and fixed, when subjected to tensile, torsional, vibrational or other external forces, or when the bolt or the like is repeatedly attached and detached, the screw hole is deformed or destroyed and cannot be used. Therefore, a nut-shaped metal fixture (insert) has been put into practical use that can be stably fixed by fitting and fixing a bolt or the like to a hole provided in a molded member, and can withstand repeated attachment and detachment. Further, a method has been proposed in which a knurled or other unevenness is provided on the outer peripheral surface of the fixture so that such a fixture bites into the hole of the molded member and is fixed with sufficient strength (for example, Patent Documents 1 and 2).

[0003] When fitting such a fixture into a molded member, the fixture is heated (around 200°C) and pressed into a boss hole provided in the molded member. This is possible because the molded member of such a synthetic resin is a thermoplastic resin. Therefore, the inventor of the present invention filed an application on July 10 this year regarding a fixture and a method for fixing the fixture that can be fixed to a hole provided in a molded member made of a thermosetting resin as well as a thermoplastic resin as a synthetic resin, or a hole provided in carbon (carbon base material). Japanese Patent Application No. 2023-133165

[0004] However, in the above-described fixture, a thermoplastic resin is attached to the rear end portion of the fixture with an adhesive or the like. This has a problem that it takes time and effort to attach the thermoplastic resin to the fixture and is not suitable for mass production.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 50-85756 [Patent Document 2] Japanese Patent Application Laid-Open No. 58-124809 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] As described above, the fixture applied for in Japanese Patent Application No. 2023-133165 has a problem that since a thermoplastic resin is attached to the rear end portion of the fixture with an adhesive or the like, it takes time and effort to attach the thermoplastic resin to the fixture and it is not suitable for mass production. The object of the present invention is to provide a fixture that can be fixed to a hole provided in a molded product member of a thermoplastic resin suitable for mass production and a method for fixing the fixture. [Means for Solving the Problems]

[0007] Therefore, the present invention is a nut-shaped metal fixture that is fixed by heating and pressurization to a hole provided in a molded product member of a thermoplastic resin, and has a head with an outer diameter the same as the inner diameter of the hole on a cylindrical main body, and a large number of uneven ridges on the outer circumferential surface of the cylindrical main body adjacent to this head, and a plug body portion having a frustum of a cone shape with a predetermined gradient such that the outer diameter becomes smaller with the side in contact with the head as the maximum outer diameter, and an anchor portion provided adjacent to this plug body portion. Further, the present invention is a method for fixing a nut-shaped metal fixture that is fixed by heating and pressurization to a hole provided in a molded product member of a thermoplastic resin, and the fixture has a head with an outer diameter the same as the inner diameter of the hole on a cylindrical main body, and a large number of uneven ridges on the outer circumferential surface of the cylindrical main body adjacent to this head, and a plug body portion having a frustum of a cone shape with a predetermined gradient such that the outer diameter becomes smaller with the side in contact with the head as the maximum outer diameter, and an anchor portion provided adjacent to this plug body portion. When the fixture is inserted into the hole provided in the molded product member of the thermoplastic resin and the head of the fixture is heated and pressurized, the anchor portion of the fixture melts and fixes the bottom of the hole. [Effects of the Invention]

[0008] The present invention can provide a fixture that can be fixed to a hole provided in a molded product member of a thermoplastic resin suitable for mass production and a method for fixing the fixture.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a fixture 1 called an insert according to a first embodiment of the present invention. That is, this fixture 1 has a head 3 provided on the outer peripheral surface of a short cylindrical main body 2 having an end face a, a small-diameter portion 4, a plug portion 5 provided on the outer peripheral surface and having a square mesh knurl (concavo-convex strip), and a rear end portion 6. Further, it is provided with an anchor 7 composed of a shank (anchor handle) 7a and an anchor head (anchor crown) 7b that also serves as a claw. The anchor head 7a of the anchor 7 is cut into a conical shape with a gradient surface curved and recessed toward the core side. The head 3 is processed to have the same outer diameter as the hole diameter of a molded product member of a thermoplastic resin to be described later. Note that the head is designed according to the size of the fixture with "hole diameter of the molded product member ≥ outer diameter of the head". This is to change the design dimensions when necessary to exhaust the air inside the hole when the fixture is pressed while heating it in the hole. Therefore, this head may be made a predetermined value smaller than the hole diameter of the molded product member according to the size of the fixture.

[0011] Further, the plug body portion 5 has a frustum shape with the side in contact with the small-diameter portion 4 having the maximum outer diameter, and the outer diameter decreases toward the rear end portion 6. Therefore, in this embodiment, the gradient angle is 10 degrees. The gradient angle of this plug body portion is processed in the range of 0 degrees to 20 degrees according to the size and material of the fastener. Note that a gradient angle of 0 degrees for the plug body portion means a cylinder, but if required in the design, it may be a cylinder shape instead of a frustum shape. Further, the maximum outer diameter of the plug body portion 5 is processed to have the same outer diameter as the hole diameter of the molded product member described later. Note that the plug body portion is designed according to the size of the fastener with "hole diameter of the molded product member ≧ maximum outer diameter of the plug body portion". Therefore, this maximum outer diameter may be made a predetermined value smaller than the hole diameter of the molded product member according to the size of the fastener.

[0012] On the main body 2, a female screw 8 is provided with a closed end from the end face a. Also, the small-diameter portion 4 may not be provided. The main point is that, although details will be described later, it suffices to design so that the thermoplastic resin melted from the plug body portion 5 does not flow into the head portion 3. Also, the anchor is for obtaining the pull-out strength of the fastener with respect to the hole and can be formed into various shapes according to the size of the fastener.

[0013] The fastener 1 of this embodiment is machined in units of 1 / 100 mm. For example, the dimensions of the fastener 1 are such that the overall length (from the end face a to the anchor 7) is 11.00 mm, the outer diameter of the head portion 3 is 6.00 mm and the length is 5.50 mm, the outer diameter of the small-diameter portion 4 is 5.80 mm and the length is 0.50 mm, the maximum outer diameter of the side of the plug body portion 5 in contact with the small-diameter portion 4 is 6.00 mm and the length is 4.00 mm, the outer diameter of the shank 7a is 2.00 mm and the length is 0.50 mm, and the maximum outer diameter of the anchor head 7b is 3.00 mm and the length is 0.50 mm, and it is machined. The female screw 8 is machined to be M4. Note that the fastener 1 uses brass in this embodiment, but metals such as stainless steel, carbon steel, aluminum, and zinc may also be used.

[0014] Figure 2 is a cross-sectional view showing a configuration example of a molded product member 11 formed of a thermoplastic resin. In the molded product member 11, a hole 13 is provided in a boss 12, and an end face b is provided 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 fixture 1 will be described in more detail. As described above, the fixture 1 is provided with a plug body portion 5, which serves as a guide when being fitted into the hole 13 provided in the molded product member 11 made of a thermosetting resin. Further, in the fixture 1 of the present invention, the plug body portion 5 does not cut the peripheral surface of the hole of the molded product member as in the prior art. Specifically, as will be described later, the anchor 7 melts the bottom of the hole 13 and is embedded and solidified at the bottom of the hole. It is a novel concept completely different from the idea of forcibly fitting a fixture with an outer diameter larger than the inner diameter of the hole as in the prior art.

[0016] Next, in such a configuration, a method of fitting and fixing the fixture 1 into the hole 13 of the molded product member 11 will be described. That is, this fitting and fixing method is to fit the fixture 1 into the hole 13 of the molded product member 11 while heating and pressurizing the fixture 1. First, the fixture 1 is supplied to the hole 13 of the molded product member 11 by a parts feeder or the like. At this time, the plug body portion 5 of the fixture 1 serves as a guide and is in a temporarily placed state in the hole 13 of the molded product member 11.

[0017] As shown in Figure 3, the tip of the anchor 7 of the fixture 1 rides on the bottom of the hole 13. In this state, the fixture 1 is pressurized while being heated from above (in the drawing), and the bottom of the hole 13 is melted by the anchor 7, enabling the fixture 1 to enter the hole 13. That is, in the heated fixture 1, the melting of the resin at the bottom of the hole starts from the anchor head 7b of the anchor 7, and pressure is also applied to accelerate the melting. The melted resin at the bottom of the hole flows into the knurled peripheral surface of the plug body portion 5 from the anchor 7 via the rear end portion 6.

[0018] Figure 4 shows the state after the fixture 1 is heated and pressurized. The fixture 1 is fitted and fixed in the hole 13 of the molded product member 11. The fixture 1 is pressurized until the entire length 1.00 mm of the anchor 7 is buried in the bottom of the hole 13 (predetermined position) and then stops. As a result, the end face a of the fixture 1 and the end face b of the molded product member 11 are flat and coincide in the same plane (predetermined position). Conversely, by pressurizing while heating until the end face a of the fixture 1 and the end face b of the molded product member 11 are flat in the same plane (1.00 mm corresponding to the entire length of the anchor 7 in the embodiment), the anchor 7 is buried in the bottom of the hole 13.

[0019] In this way, the resin at the bottom of the hole 13 melted from the anchor 7 bites into the square mesh knurls of the plug body portion 5 and the anchor 7 is in a state of being buried in the bottom of the hole 13. The fixture 1 can maintain the tensile strength (pull-out strength) of the molded product member 11 in the hole 13 by the anchor 7 and can also ensure the torsional strength (rotational torque) by the square mesh knurls of the plug body portion 5. In addition, since there is no expansion pressure from the inside of the hole 13 of the boss due to the insertion of the fixture 1 described above, it is possible to avoid cracks that sometimes occur in the upper part of the boss 12. Furthermore, it is considered that cracks due to the aging deterioration of the boss 12 can also be avoided.

[0020] As described above, according to the embodiment of the above invention, it is possible to provide a fixture that can be fixed to a hole provided in a molded product member of a thermoplastic resin suitable for mass production and a method for fixing the fixture.

[0021] Note that the invention of the present application is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof at the implementation stage. Also, the embodiments may be implemented in appropriate combinations as much as possible, and in that case, the combined effects can be obtained. Furthermore, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problems described in the column of the problems to be solved by the invention can be solved and the effects described in the column of the effects of the invention can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention. The invention of the present application is applied to those having an outer diameter of the fixture of 30 mm or less.

Explanation of Reference Numerals

[0022] 1... Fixture, 2... Body, 3... Head, 4... Small-diameter portion, 5... Plug body portion, 6... Rear end portion, 7... Anchor, 8... Female screw, 11... Molded product member, 12... Boss, 13... Hole.

Claims

1. A nut-shaped metal fixture that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, a cylindrical main body having a head with an outer diameter equal to or slightly smaller than the diameter of the hole, a plug body portion having a plurality of uneven ridges on the outer circumferential surface of the cylindrical main body adjacent to the head, and having a frustoconical shape with a predetermined gradient such that the outer diameter decreases with the side in contact with the head as the maximum outer diameter, an anchor portion consisting of an anchor handle having an outer diameter smaller than that of the plug body portion adjacent to the plug body portion, and an anchor crown having an outer diameter larger than that of the anchor handle adjacent to the anchor handle, characterized in that it comprises the above.

2. A method for fixing a nut-shaped metal fixture that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, the above fixture having a cylindrical main body with a head having an outer diameter equal to or slightly smaller than the diameter of the hole, and a plurality of uneven ridges on the outer circumferential surface of the cylindrical main body adjacent to the head, and a plug body portion having a frustoconical shape with a predetermined gradient such that the outer diameter decreases with the side in contact with the head as the maximum outer diameter, and an anchor portion consisting of an anchor handle having an outer diameter smaller than that of the plug body portion adjacent to the plug body portion, and an anchor crown having an outer diameter larger than that of the anchor handle adjacent to the anchor handle, 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 pressed, the anchor portion of the fixture melts the bottom of the hole and is fixed by the anchor portion and the plug body portion, characterized in that it is a method for fixing a fixture.

3. The gradient of the plug body portion is in the range of 0 degrees to 20 degrees, characterized in that it is the fixture according to Claim 1 or Claim 2.

4. A nut-shaped metal fixture that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, a cylindrical main body having a head with an outer diameter equal to or slightly smaller than the diameter of the hole, a plurality of uneven ridges on the outer circumferential surface of the cylindrical main body adjacent to the head, and a cylindrical plug body portion having an outer diameter equal to or slightly smaller than the outer diameter of the head, an anchor portion consisting of an anchor handle having an outer diameter smaller than that of the plug body portion adjacent to the plug body portion, and an anchor crown having an outer diameter larger than that of the anchor handle adjacent to the anchor handle, characterized in that it comprises the above.

5. A nut-shaped metal fixture that is fixed by heating and pressing into a hole provided in a molded member of a thermoplastic resin, It has an anchor portion consisting of a head with an outer diameter equal to or a predetermined value smaller than the hole diameter of the above hole on a columnar main body, a large number of uneven ridges on the outer circumferential surface of the columnar main body adjacent to this head, a plug body portion with a cylindrical shape having an outer diameter equal to or a predetermined value smaller than the outer diameter of this head, an anchor handle with an outer diameter smaller than the outer diameter of the plug body portion adjacent to this plug body portion, and an anchor crown with an outer diameter larger than the outer diameter of the anchor handle adjacent to this anchor handle. A fixing method of a fixing tool, characterized in that when the fixing tool is inserted into a hole provided in the molded product member of the above thermoplastic resin and the head of the fixing tool is heated and pressurized, the anchor portion of the fixing tool melts the bottom of the hole and is fixed by the anchor portion and the plug body portion.

6. The fixing tool according to claim 1 or claim 2 or claim 4 or claim 5, wherein the anchor portion melts the bottom of a hole provided in a molded product member of a thermoplastic resin and is buried in the bottom of the hole.

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