JP2016056940A - Fastening tool, hammer rod and fastening tool fixing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening tool, a hammer rod and a fastening tool fixing method in which a productivity at the time of mass-production when the fastening tool is fixed to a sheet metal having a thickness of 0.3 mm or less is improved.SOLUTION: This invention is constituted in such a way that a lower hole 8 of a sheet metal 7 is put into a caulking part 4 and the sheet plate 7 is placed on a main body 2 of a fastening tool 1. A hammer 20 is inserted from an insertion part 22 into an open hole 6 of the caulking part 4 of the fastening tool 1, the caulking part 4 is pressed by the insertion part 22 from above on the central axis, expanded in a peripheral region and subsequently the caulking part 4 is formed by a forming part 23 around the lower hole 8 of the sheet metal 7 and caulked. Subsequently, the hammer 20 is pulled out of the caulking part 4 of the fastening tool 1, its caulking operation is finished and the caulking part 4 of the fastening tool 1 is caulked around the lower hole 8 of the sheet metal 7 and fixed there.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fixing tool, a striking rod and a fixing method for fixing to a thin metal plate used in, for example, a cellular phone.

Conventionally, nut-shaped metal fasteners called inserts (fasteners) that can withstand tensile loads and torque loads and reliably press-fit with thin plates (sheet metal) have been put into practical use. When such a nut-like metal fastener is attached, there is no risk of loosening or dropping.
A knurled shape is formed on the outer peripheral surface of the protruding portion (the portion that is actually press-fitted into the thin plate) provided in the fixture so that such a fastener is press-fitted into a hole provided in advance in the thin plate and fixed with sufficient strength. There has been proposed a method of providing other uneven strips and press-fitting into a thin plate (for example, Patent Document 1).

In recent years, for example, in the case of a mobile phone or the like, there has been an increasing demand for design that makes the case lighter and thinner so that it is described as “light thin and short”. In order to meet such a demand, it is necessary to make the sheet (sheet metal) itself thin and further shorten the overall length of the fixing tool.
On the other hand, in order to embed the protruding portion of the conventional fixing tool in the sheet metal, a certain thickness of the sheet metal is necessary. Conventionally, the minimum sheet thickness of the sheet metal is about 0.5 mm. For this reason, the inventor has not been able to cope with a sheet metal having a thickness of less than 0.5 mm, but the present inventor has solved this problem and made it possible even with a sheet thickness of less than 0.3 mm (for example, Patent Document 2).

  However, when dealing with a sheet metal having a sheet thickness of less than 0.3 mm, for example, if the sheet metal material is a relatively soft material such as aluminum, the jig on the receiving side must be received in a timely manner when fixed with a striking rod. There was a problem of poor productivity during mass production.

  JP-A-8-291815   JP 2014-126203 A

As described above, in order to respond to design demands such as lightening and thinning in a casing of a mobile phone or the like, when the sheet metal itself is thinned, and the sheet metal having a thickness of less than 0.3 mm is handled, the sheet metal material is particularly used. In the case of a relatively soft material, the jig on the receiving side must be received in a timely manner when fixed with a striking rod, and there is a problem that productivity in mass production is poor.
An object of the present invention is to provide a fixing tool, a striking rod, and a fixing method of the fixing tool which are improved in productivity at the time of mass production when fixing to a sheet metal having a thickness of less than 0.3 mm.

Therefore, the present invention is a fixing tool provided with a female screw that is fixed to a lower hole that has no protrusion on the front and back of the sheet metal provided on a sheet metal having a thickness of less than 0.3 mm and 0.1 mm or more. The fixing tool has a columnar main body and a caulking portion adjacent to the main body and having a smaller diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis. The female screw penetrating the same central axis and the through hole penetrating the same central axis in the caulking portion in contact with the female screw are provided.
Further, the present invention is a fixing tool provided with a female screw that is fixed to a lower hole having no protrusion on the front and back of the sheet metal provided on a sheet metal of less than 0.3 mm and 0.1 mm or more in thickness. The fixing tool has a cylindrical main body and a pressing portion adjacent to the main body and having a smaller diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis. The internal thread of which the effective screw thread number is secured through the same central axis, and the through hole which is in contact with the internal thread and penetrates the same central axis in the pressing portion, the through hole and the internal thread With a groove between the two.

  The present invention can provide a fixing tool, a striking rod, and a fixing method of the fixing tool that improve productivity in mass production when fixing to a sheet metal having a thickness of less than 0.3 mm.

1 is a half sectional view showing an example of a fixing tool to which a first embodiment of the present invention can be applied. Sectional drawing which shows an example of the sheet metal which crimps and fixes a fixing tool. The figure which shows the external appearance of the hammer (striking stick) for caulking a fixing tool. The figure which shows the state before crimping which puts a sheet metal on a fixing tool through a caulking part to a lower hole on a main body. The figure which shows the state after crimping and fixing a fixing tool to a sheet metal. The half sectional view which shows an example of the fixing tool which can apply the 2nd Embodiment of this invention. Sectional drawing which shows an example of the sheet metal which presses and fixes a fixing tool. The figure which shows the external appearance of the hammer (pressing bar) for pressing a fixing tool. The figure which shows the state before the press which put the sheet metal on the fixing tool through the press part to the lower hole on the main body. The figure which shows the state after pressing and fixing a fixing tool to a sheet metal.

The first embodiment of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a half sectional view showing a fixing tool 1 called an insert according to the present invention. That is, in the fixing tool 1, a columnar main body 2 and a caulking portion 4 having a diameter smaller than the outer diameter of the main body 2 adjacent to the main body 2 are integrally provided on the same central axis.

  Further, a female screw 5 penetrating from the base end surface a side of the main body 2 to the other end side is provided. Further, the caulking portion 4 is provided with a through hole 6 on the same central axis in contact with the female screw 5 for caulking processing described later. The through hole 6 is chamfered on the inner surface of the other end surface with respect to the base end surface a. Further, the outer peripheral surface b of the caulking portion 4 is knurled. In addition, the outer diameter of the caulking part 4 and the shape of the uneven stripes can be changed according to the material of the sheet metal.

  FIG. 2 is a cross-sectional view showing the sheet metal 7 on which the fixing tool 1 is caulked. In FIG. 2, a sheet metal 7 is previously provided with a pilot hole 8 (a pilot hole having no protrusions on the front and back of the sheet metal) into which the caulking portion 4 of the fixing tool 1 is inserted. The lower hole 8 is provided substantially at the center of a recess 9 in which the sheet metal 7 is dimpled (recessed). The dimple (recess) processing may be circular, elliptical, hexagonal, or the like as long as the lower hole 8 is provided in the recess.

Further, as will be described in detail later, the recess 9 of the sheet metal 7 has a depth that prevents the caulking portion 4 after the caulking processing of the fixing tool 1 from the surface c of the sheet metal 7 from jumping out.
In the first embodiment, for example, the material of the sheet metal 7 is aluminum, and the material of the fixing tool 1 is brass.

Moreover, the fixing tool 1 of the present embodiment is cut in units of 1/100 mm.
For example, the dimensions of the fastener 1 are 2.00 mm in total length (from the base end surface a to the other end surface), the outer diameter of the main body 2 is 2.60 mm, the length in the column direction is 1.20 mm, and the outer diameter of the caulking portion 4. Is 2.40 mm, the length in the column direction is 0.8 mm, the female screw 5 is M1.2, and the inner diameter of the through hole 6 of the caulking portion 4 is 1.90 mm.
The dimensions of the sheet metal 7 are, for example, a plate thickness of 0.2 mm ± 0.05 mm and a hole diameter of the lower hole 8 of 2.5 mm.
Moreover, although the fixing tool 1 uses brass in the present embodiment, it corresponds to the material of the sheet metal (soft steel, stainless steel, aluminum, zinc, etc.), such as carbon steel, mild steel, stainless steel, aluminum, zinc, etc. May be used.

FIG. 3 is a view showing an appearance of a hammer (striking rod) 20 for caulking the fixing tool 1 to the sheet metal 7. For example, the hammer 20 is provided with a tip portion 21 for inserting and fixing the hammer 20 into the through hole 6 of the caulking portion 4 of the fixing tool 1 at the tip.
The distal end portion 21 includes an insertion portion 22 that is inserted into the through hole 6 of the caulking portion 4 of the fixing tool 1 and a molding portion that molds the caulking portion 4 after the insertion portion presses the caulking portion 4 and expands to the periphery. 23. The insertion portion 22 has a substantially conical shape formed with a concave curved taper in the axial direction.
For example, the hammer 20 has a length of 40 mm and an outer diameter of 6.0 mm. The tip 21 is machined with an outer diameter of 5.00 mm and a length in the column direction of 3.50 mm.

Next, the operation for caulking and fixing the fixing tool 1 to the sheet metal 7 in such a configuration will be described with reference to FIGS.
As shown in FIG. 4, first, the lower hole 8 of the sheet metal 7 is fitted into the caulking portion 4, and the sheet metal 7 is placed on the main body 2 of the fixing tool 1. In addition, since the main body 2 of the fixing tool 1 does not use a jig, it is placed on a flat fixing base (for example, an iron board).

Subsequently, a hammer 20 is inserted from the upper part of the figure into the through hole 6 of the caulking part 4 of the fixing tool 1 in FIG. 4 from the upper part in the figure, and the caulking part 4 is pressed by the insertion part 22 from the upper part on the central axis. It is spread around. Subsequently, the caulking part 4 is molded around the lower hole 8 of the sheet metal 7 by the molding part 23 and caulked.
Thereafter, the caulking operation is completed by removing the hammer 20 from the caulking portion 4 of the fixing tool 1.

FIG. 5 shows a state in which the caulking operation is completed and the fixing tool 1 is fixed to the sheet metal 7. The caulking portion 4 of the fixing tool 1 is caulked around the lower hole 8 of the sheet metal 7 and fixed. . As a result, the fixing strength required between the fixing tool 1 and the sheet metal 7 is firmly fixed to the sheet metal 7 by the knurls (concave and convex portions: b section shown in FIGS. 4 and 5) applied to the caulking part 4. Can be obtained.
Further, since the lower hole 8 of the sheet metal 7 is in the recess 9, the caulking portion 4 after being caulked is prevented from jumping out from the surface c of the sheet metal 7.

In the first embodiment, the sheet thickness of the sheet metal is 0.2 mm. However, the thickness of the sheet metal that becomes a thin sheet by using a fixing tool, a hammer (striking rod), and a fixing method based on the present embodiment. Even if is less than 0.3 mm, the fixing tool can be fixed.
The plate thickness of less than 0.3 mm is a standard plate such as 0.25 mm ± 0.05 mm, 0.2 mm ± 0.05 mm, 0.15 mm ± 0.05 mm, 0.1 mm ± 0.05 mm, etc. Thickness is included. The fixing tool 1 can be applied to a sheet metal of less than 0.3 mm and 0.1 mm or more.

  As described above, according to the first embodiment, there is provided a fixing tool, a hitting rod, and a fixing method for fixing the fixing tool, which improve productivity in mass production when fixing to a sheet metal having a thickness of less than 0.3 mm. Can be provided.

Next, a second embodiment of the present invention will be described in detail.
FIG. 6 is a half sectional view showing a fixing tool 31 called an insert according to the second embodiment of the present invention. That is, in the fixing tool 31, a columnar main body 32 and a pressing portion 34 having a diameter smaller than the outer diameter of the main body 32 adjacent to the main body 32 are integrally provided on the same central axis.
Further, a female screw 35 penetrating from the base end surface d side of the main body 32 to the other end side is provided. As will be described in detail later, the female screw 35 has a predetermined length so as to ensure the number of effective threads. In the second embodiment, seven threads are secured as the number of effective threads.

Further, the outer peripheral surface e of the pressing portion 34 is knurled. Further, the pressing portion 34 is provided with a through hole 36 on the same central axis in contact with the female screw 35 for the pressing process described later. A groove f is provided between the through hole 36 and the female screw 35. Although described later in detail, the groove f prevents the thread of the female screw 35 from being deformed when the pressing portion 34 is pressed.
In addition, the outer diameter of the pressing part 34, the shape of the through hole, the groove, and the ridges and the like can be changed according to the material of the sheet metal.

FIG. 7 is a cross-sectional view showing a sheet metal 37 to which the fixing tool 31 is fixed. In FIG. 7, the sheet metal 37 is previously provided with a lower hole 38 (a lower hole having no protrusions on the front and back of the sheet metal) into which the pressing portion 34 of the fixing tool 31 is inserted. The lower hole 38 is provided substantially at the center of a recess 39 in which a sheet metal 37 is dimpled (recessed). The dimple (dimple) process may be circular, elliptical, hexagonal, or the like, as long as the lower hole 38 is provided in the depressed portion.
In addition, although mentioned later in detail, the dent 39 of the sheet metal 37 has such a depth that the pressing portion 34 after pressing the fixing tool 31 from the surface g of the sheet metal 37 does not protrude.
In the second embodiment, for example, the material of the sheet metal 37 is aluminum, and the material of the fixing tool 31 is brass.

Moreover, the fixing tool 1 of the present embodiment is cut in units of 1/100 mm.
For example, the dimensions of the fixing tool 31 are 3.57 mm in total length (from the base end face d to the other end face), the outer diameter of the main body 32 is 2.00 mm, the length in the column direction is 1.57 mm, and the outer diameter of the pressing portion 34. Is 2.60 mm, the length in the column direction is 2.00 m from the main body 32, the internal thread 35 is M1.2, and the inner diameter of the through hole 36 of the pressing portion 34 is 2.10 mm.
The female screw 35 has a dimension of 1.87 mm in the column direction from the base end face d in order to ensure seven effective screw threads. Therefore, as shown in FIG. 6, it is longer than the length of the main body 32 in the column direction. Therefore, a groove f is provided between the pressing portion 34 and the through hole 36 in order to prevent deformation of the thread of the female screw 35 during pressing of the pressing portion 34.

The groove f of the pressing portion 34 is cut to a depth of 0.30 mm and a width of 0.35 mm from the surface opposite to the base end surface d of the female screw 35 provided in the main body 32. The depth and width of the groove f can be changed according to the material of the fixing tool 31.
The sheet metal 37 has a thickness of 0.20 mm and a diameter of the lower hole 38 of 2.70 mm. The plate thickness of the sheet metal 37 is in the range of 0.20 mm ± 0.05 mm.
Moreover, although the fixing tool 31 uses brass in this embodiment, a metal such as carbon steel, mild steel, stainless steel, aluminum, zinc or the like corresponding to the material of the sheet metal (soft steel, stainless steel, aluminum, zinc, etc.). May be used. In short, it is sufficient if the material of the fixing tool is harder than the material of the sheet metal.

FIG. 8 is a view showing the appearance of a hammer (pressing bar, striking bar) 40 for pushing the fixing tool 31 into the sheet metal 37. The hammer 40 has a concave portion 41 at the tip and presses the pressing portion 34 of the fixing tool 31 to fix the fixing tool 31 to the sheet metal 37.
For example, the dimension of the hammer 40 is a cylinder having a length of 40 mm and an outer diameter of 4.80 mm, and the recess 41 at the tip has an inner diameter of 4.00 mm and a depth of 0.40 mm.
The concave portion 41 of the hammer 40 has a pressing portion 34 that is formed by pressing the pressing portion 34 and pressed from the surface g of the metal plate 37 when the pressing portion 34 of the fixing tool 31 is pressed into the depression 39 of the metal plate 37. It is pressed so as not to jump out.

For example, when the depth of the recess 39 of the sheet metal 37 is 0.50 mm, the depth of the recess 21 is 0.40 mm. Further, when the depth of the recess 39 of the sheet metal 37 is 0.30 mm, the depth of the recess 41 is 0.25 mm. That is, the depth of the recess 39 of the sheet metal 37 and the depth of the recess 41 of the hammer 40 have a correlation, and the respective depths are determined according to the finished condition after pressing.
Furthermore, the tip of the hammer 40 (the portion that is a convex portion with respect to the concave portion 41) presses the periphery of the lower hole 38 of the sheet metal 37 to prevent deformation of the periphery of the lower hole 38 of the sheet metal 37 during pressing.

Next, in such a configuration, an operation of pressing and fixing the fixing tool 31 to the sheet metal 37 will be described with reference to FIGS.
As shown in FIG. 9, first, the lower hole 38 of the sheet metal 37 is fitted into the pressing portion 34, and the sheet metal 37 is placed on the fixing tool 31. Since the main body 32 of the fixing tool 31 does not use a jig, it is placed on a flat fixing base (for example, an iron board).

Subsequently, the pressing portion 34 of the fixing tool 31 in FIG. 9 is crushed by pressing the hammer 40 from the upper part in the drawing. At that time, the pressing portion 34 is crushed flat in the pressing direction while the circumferential surface of the knurl (uneven surface) expands around. As a result, the knurls (concave and convex) provided on the peripheral surface e of the pressing portion 34 bite into the concavo-convex ridge around the lower hole 38 of the sheet metal 37 and are crushed flat in the pressing direction. To be molded.
In addition, since the groove | channel f is provided when the press part 34 is crushed flat, the thread of the internal thread 35 is prevented from being deformed.
Thereafter, the hammer 40 is returned from the pressing portion 34 of the fixing tool 1 to the upper side in the figure, thereby completing the pressing operation.

FIG. 10 shows a state in which the pressing operation is completed and the fixing tool 31 is fixed to the sheet metal 37, and the pressing portion 34 of the fixing tool 31 is pressed and fixed around the lower hole 38 of the sheet metal 37. . That is, the periphery h of the lower hole 38 of the sheet metal 37 is press-formed into the concavo-convex line by the knurling (uneven line) provided around the pressing portion 34, and the fixing tool 31 is fixed to the sheet metal 37. As a result, it is possible to obtain the required fixing strength, particularly the torque load, between the fixing tool 31 and the sheet metal 37.
Further, since the lower hole 38 of the sheet metal 37 is in the recess 39, the fixing tool 31 prevents the pressing portion 34 after being fixed to the sheet metal 37 from jumping out from the surface g of the sheet metal 37.

Although the sheet thickness of the sheet metal is 0.2 mm in the second embodiment, the sheet thickness of the sheet metal that becomes a thin sheet by using the fixing tool, the hammer (pressing bar), and the fixing method based on the present embodiment. Even if is less than 0.3 mm, the fixing tool can be fixed.
The plate thickness of less than 0.3 mm is a standard plate such as 0.25 mm ± 0.05 mm, 0.2 mm ± 0.05 mm, 0.15 mm ± 0.05 mm, 0.1 mm ± 0.05 mm, etc. Thickness is included. The fixing tool 31 can be applied to a sheet metal of less than 0.3 mm and 0.1 mm or more.

  As described above, according to the second embodiment, the fixing tool, the hitting rod, and the fixing method for improving the productivity in mass production when fixing to a sheet metal having a thickness of less than 0.3 mm. Can be provided.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. In addition, the embodiments may be combined as appropriate as possible, and in that case, the combined effect can be obtained. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.

  DESCRIPTION OF SYMBOLS 1,31 ... Fixing tool, 2,32 ... Main body, 4 ... Caulking part, 5,35 ... Female screw, 6,36 ... Through-hole, 7, 37 ... Sheet metal, 8,38 ... Pilot hole, 9,39 ... Depression, 20, 40 ... hammer, 21 ... tip part, 22 ... insertion part, 23 ... molding part, 34 ... pressing part, 41 ... concave part.

Claims (6)

A fixing tool provided with a female screw that is fixed to a lower hole having no projection on the front and back of the sheet metal provided on a sheet metal having a thickness of less than 0.3 mm and 0.1 mm or more,
The fixing tool has a columnar main body and a caulking portion adjacent to the main body and smaller in diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis,
The fixing tool comprising: the female screw penetrating the same central axis of the main body; and a through-hole penetrating the same central axis in the caulking portion in contact with the female screw. A fixing tool and a striking rod provided with a female screw that is fixed to a pilot hole provided with no projection on the front and back of the sheet metal provided on a sheet metal having a thickness of 0.1 mm or more and less than 0.3 mm,
The fixing tool has a cylindrical main body and a caulking portion adjacent to the main body and smaller in diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis, The internal thread that penetrates the same central axis of the main body, and a through-hole that penetrates the same central axis in the caulking portion in contact with the female thread,
The hitting rod has a substantially conical shape formed by a concavely curved taper in an axial direction inserted into a through hole provided in a caulking portion of the fixing tool at a tip of a cylindrical main body larger than an outer diameter of the main body. A molding part for molding the insertion part and the caulking part;
The insertion portion at the tip of the hitting rod is inserted into the through hole of the caulking portion, and the crimping portion is expanded around the lower hole of the sheet metal by being pressed by the insertion portion of the hitting rod. A fixing tool and a striking rod, wherein a caulking portion expanded around a hole is further crimped by being pressed by a molding portion of the striking rod. A fixing method of a fixing tool provided with a female screw that is fixed to a lower hole having no projection on the front and back of the sheet metal provided on a sheet metal having a thickness of less than 0.3 mm and 0.1 mm or more,
The fixing tool has a cylindrical main body and a caulking portion adjacent to the main body and smaller in diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis, The internal thread that penetrates the same central axis of the main body, and a through-hole that penetrates the same central axis in the caulking portion in contact with the female thread,
The sheet metal has the prepared hole having an inner diameter larger than the outer diameter of the caulking portion and smaller than the main body,
The hitting rod has a substantially conical shape formed by a concavely curved taper in an axial direction inserted into a through hole provided in a caulking portion of the fixing tool at a tip of a cylindrical body larger than an outer diameter of the large diameter portion. Having a shape insertion part and a molding part for molding the caulking part,
When the sheet metal is in contact with the surface of the main body, which is in contact with the outer peripheral surface of the caulking part, by fitting the pilot hole of the sheet metal into the caulking part of the fixing tool, the through hole of the caulking part is subjected to the hammering. The insertion part at the tip of the bar is inserted, and the crimping part is expanded around the lower hole of the sheet metal by being pressed by the insertion part of the hitting bar, and the crimped part is expanded around the lower hole of the sheet metal Is fixed by being pressed against the forming part of the hitting rod, and the fixing tool is fixed to the sheet metal by a large number of concave and convex strips of the molded crimping part. Fixing method. A fixing tool provided with a female screw that is fixed to a lower hole having no projection on the front and back of the sheet metal provided on a sheet metal having a thickness of less than 0.3 mm and 0.1 mm or more,
This fixing tool has a cylindrical main body and a pressing portion adjacent to the main body and having a large diameter on the outer peripheral surface that is smaller than the outer diameter of the main body on the same central axis.
The internal thread in which the number of effective threads is secured through the same central axis of the main body, and a through hole that is in contact with the female thread and penetrates the same central axis in the pressing portion,
A fixing tool having a groove between the through hole and the female screw. A fixing tool and a pressing rod provided with a female screw that is fixed to a lower hole having no projection on the front and back of the sheet metal provided on a sheet metal having a thickness of less than 0.3 mm and 0.1 mm or more,
The fixing tool has a cylindrical main body and a pressing portion adjacent to the main body and having a smaller diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis. The internal thread of the main body passing through the same central axis and having an effective number of threads secured, and a through-hole passing through the same central axis in the pressing portion in contact with the female thread, Having a groove between the hole and the female thread,
The pressing rod has a cylindrical shape larger than the outer diameter of the large-diameter portion and has a recess at the tip,
A fixing tool and a pressing rod, wherein the pressing portion is pressed by the pressing rod, and the pressing portion is crushed flatly in the pressing direction while expanding to the outer peripheral surface. A fixing method of a fixing tool provided with a female screw that is fixed to a lower hole having no projection on the front and back of the sheet metal provided on a sheet metal having a thickness of less than 0.3 mm and 0.1 mm or more,
The fixing tool has a cylindrical main body and a pressing portion adjacent to the main body and having a smaller diameter than the outer diameter of the main body and having a large number of irregularities on the outer peripheral surface on the same central axis. The internal thread of the main body passing through the same central axis and having an effective number of threads secured, and a through-hole passing through the same central axis in the pressing portion in contact with the female thread, Having a groove between the hole and the female thread,
The sheet metal has the prepared hole having an inner diameter larger than the outer diameter of the pressing portion and smaller than the main body,
The pressing rod has a cylindrical shape larger than the outer diameter of the main body and has a recess at the tip,
When the sheet metal is in contact with the surface of the main body that is in contact with the outer peripheral surface of the pressing portion by fitting the pilot hole of the sheet metal into the pressing portion of the fixing tool, the pressing portion is pressed by the pressing rod. The fixing device is fixed to the sheet metal by being crushed in a flat shape in the pressing direction while the pressing portion expands to the outer peripheral surface.

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