JPH0259324B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of fixing a bolt to a through hole formed in a metal plate, and particularly to a technique for increasing the bolt's pull-out load.

A head, a shaft having a smaller diameter than the head, and a shaft located between the head and the shaft, having a smaller diameter than the head and a larger diameter than the shaft, and on the outer peripheral surface. A bolt is known that includes a serration portion in which a plurality of protruding teeth are formed. When fixing such a bolt to a through-hole formed in a metal plate material, it is difficult to obtain a sufficient pull-out load by simply forcing the serrations into the through-hole. The end portion on the shaft side is compressed in the axial direction and plastically deformed in the radial direction, thereby improving the bolt pull-out load (strength in the pull-out direction). However, when such a conventional fixing method is applied, especially when the through hole formed in the metal plate material is formed by punching, the pullout load of the fixed bolt may vary greatly.

As a result of various studies based on the above circumstances, the present inventor found that if the press-fitting direction of the bolt matches the punching direction when forming a through-hole in a metal plate material, the bolt fixed in the through-hole will come out. We have discovered that the load can be extremely large and stably obtained. The present invention has been made based on the above findings.

That is, the gist of the present invention is as follows: (1) forming a through hole in a metal plate material by punching, the diameter being larger than the shaft part and smaller than the serration part; a fitting step of inserting the bolt into the through hole in the same direction as the punching direction, and forcibly fitting the serration portion of the bolt into the through hole; A caulking step of expanding the diameter of the end portion of the serration portion by compressing it toward the head, and caulking the end portion of the serration portion to a metal plate material. do.

In this way, the diameter of the entrance side of the through hole formed by punching (the side into which the punch punch enters) is generally formed to be approximately the same as the diameter of the punch due to the shearing action of the punch. The diameter of the punch on the exit side of the through hole (the protruding side of the punch) is larger than the diameter of the punch due to the breaking action, in other words, the diameter on the entrance side of the through hole. In this case, when the diameter of the end of the serration portion on the shaft portion side is expanded by caulking, the bolt removal load can be significantly increased, and this can be stably achieved.

In another aspect of the present invention, the steps include: (1) forming a through hole in a metal plate material by punching, the through hole having a diameter larger than the shaft portion and smaller than the serration portion; a fitting step of inserting the bolt into the through hole in the same direction as the punching direction and forcibly fitting the serration portion of the bolt into the through hole; (3) simultaneously with or after the fitting step; The end of the serration part on the shaft part side and the opening edge of the through hole, which is a part of the metal plate material and into which the serration part is press-fitted, are compressed toward the head. By squishing it into the metal plate material, the diameter of the end of the serration part is expanded, and at the same time, the diameter of the inner circumferential wall on the shaft part side of the through hole is reduced, and the end part of the serration part is inserted into the metal plate material. It is characterized by comprising a caulking process of caulking.

In this way, in addition to obtaining the same effect as the above-mentioned invention, the end of the serration portion on the shaft side and the opening edge of the through hole on the shaft side are both crushed into the metal plate material. By inserting the serration into the metal plate, the diameter of the end of the serration is expanded and at the same time the diameter of the inner circumferential wall on the shaft side of the through hole is reduced. A stable pull-out load can be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings.

In FIG. 1, the bolt 10 has a large diameter head 12.
, a shaft portion 14 having a smaller diameter than the head 12 and formed with a male thread, and a serration located between the head 12 and the shaft portion 14 and having a smaller diameter than the head 12 and a larger diameter than the shaft portion 14. It has a section. As shown in the cross-sectional view of FIG.
It has multiple on the outer circumferential surface. Figure 3 shows bolt 10
2 shows a cross section of a receiving jig 20 used for fixing the bolt 10. The receiving jig 20 has a receiving surface 22 having a hole 24 larger in diameter than the shaft portion 14 of the bolt 10 and smaller in diameter than the serration portion 16. An annular protrusion 26 having a larger outer diameter than the serration portion 16 is provided at the opening edge of the hole 24.
is installed protrudingly. Note that the height of the protrusion 26 is 0.5
A range of approximately 1.5 mm is desirable.

Hereinafter, the bolt 10 is attached to a metal plate material 28 having a thickness similar to the axial dimension of the serration portion 16 of the bolt 10.
The process for fixing it will be explained.

First, a through hole 30 is formed in the metal plate material 28 by a well-known punching process using a punch or the like. At this time, the diameter of the through hole 30 is formed to be smaller than the diameter of the serration portion 16 of the bolt 10 and larger than the diameter of the shaft portion 14, but the diameter of the through hole 30 on the inlet side of the punch is affected by the shearing effect. However, the diameter on the exit side of the punch of the through hole 30 is made larger than the diameter on the entrance side due to the breaking action. In the case where the through hole 30 is formed by punching, the hole 30 is formed on the inner circumferential surface on the exit side and has a thickness of 7 to 7 mm.
A fractured surface is formed in a range of about 8%, and it is inevitable that the fractured surface will be larger than the diameter on the inlet side. Note that the cross-sectional shape of the through hole 30 in the following figures is slightly exaggerated in order to facilitate understanding of the difference in diameter between the inlet side and the outlet side.

Next, the bolt 10 is inserted into the through hole 30 of the metal plate material 28 in the same direction as the punching direction, and the shaft portion 14 of the bolt 10 is fitted into the hole 24 of the receiving jig 20. The metal plate material 28 is received by the receiving jig 20, and a pressing force is applied to the head 12 of the bolt 10 from the press-fitting jig 32. Therefore, the serration portion 16 is forcibly fitted into the through hole 30 having a smaller diameter than the serration portion 16. As a result, the protruding tooth 18 provided on the outer peripheral surface of the serration portion 16 bites into the inner wall surface of the through hole 30. FIG. 4 shows this state.

Subsequently, when the pressing force from the press-fitting jig 32 is further increased, the end of the serration section 16 on the shaft section 14 side and the opening edge of the through hole 30 on the shaft section 14 side, which is a part of the metal plate material, are separated. , are violently abutted against the end faces of the protrusions 26 and are plastically deformed, and are crushed into the metal plate 28 by a distance corresponding to the height of the protrusions 26. Therefore, the diameter of the end of the serration portion 16 on the shaft portion 14 side is expanded, and at the same time the through hole 30
The inner circumferential wall on the shaft portion 14 side is pushed out toward the serration portion 16, thereby reducing the diameter. As a result, the protruding teeth 18 at the enlarged diameter portion of the serration portion 16 bite into the inner wall surface of the through hole 30 with high pressure, while the inner wall surface of the reduced diameter portion of the through hole 30 tooth 18
The serration portion 16 and the inner wall surface of the through hole 30 are strongly caulked together by digging into the valley between them with high pressure. FIG. 5 shows this state.

The pull-out load (strength in the pull-out direction) of the bolt 10 fixed in the above manner is the serration portion 16
is press-fitted in the punching direction of the through hole 30, and the end of the serration portion 16 on the shaft portion 14 side is expanded in diameter, so that the diameter of the through hole 30 becomes smaller at the end of the expanded diameter serration portion 16. As a result, a high pulling load can be stably obtained.

Further, according to this embodiment, the diameter of the end portion of the serration portion 16 on the shaft portion 14 side is expanded by the projection 26 provided on the receiving jig 20, and at the same time, the diameter of the end portion of the serration portion 16 on the shaft portion 14 side is expanded.
Since the diameter of the inner wall surface on the shaft portion 14 side of the serration portion 16 is reduced, the end portion of the serration portion 16 on the shaft portion 14 side and the inner wall surface of the through hole 30 on the shaft portion 14 side are caulked together extremely firmly with high surface pressure. As a result, even higher pullout load values can be obtained.

Further, according to this embodiment, since the opening edge of the through hole 30 and the end of the serration section 16 on the shaft section 14 side are crushed into the metal plate material 28 by the protrusion 26, the shaft section of the serration section 16 14 side end portion is reliably prevented from slightly bulging or protruding like a burr from the surface of the shaft portion 14 side of the metal plate material 28, and the mounting member to be tightened to the bolt 10 is securely attached to the metal plate material 28. It has the advantage of being able to be brought into close contact with the

Next, other embodiments of the present invention will be described. In the following description, parts common to those in the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the annular protrusion 26 in the receiving jig 20 of the previous embodiment is removed, while the bolt 1
0, the length of the serration portion 16 in the axial direction is slightly larger than the thickness of the metal plate 28.

According to this embodiment, when the crimping process shown in FIG. 7 is performed subsequent to the fitting process shown in FIG. The diameter of the hole 24 is expanded by hitting the opening edge of the hole 24. For this reason, the serration section 1
The enlarged diameter portion 6 bites into the inner wall surface of the through hole 30 with high surface pressure. Therefore, bolt 10
When drawing, the enlarged diameter portion of the serration section 16 moves from the large diameter side of the through hole 30 (the exit side of the punch) to the small diameter side (the entrance side of the punch).
Since the bolt 10 is about to be moved towards the target, the pullout load of the bolt 10 is increased and can be stably obtained.

Further, as shown in FIG. 8, the end of the serration portion 16 on the shaft portion 14 side of the bolt 10 may be formed in a wave shape. In such a case,
There is an advantage that the caulking load during the caulking process in which the end portions of the serration portions 16 are plastically deformed and expanded in diameter is reduced. The serration portion 16 having such a wavy end portion is formed, for example, by swaging.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the above-described embodiment, the protruding teeth 18 formed on the outer peripheral surface of the serration portion 16 are parallel to the axial direction, but the predetermined leads extend in one circumferential direction as they advance in the axial direction. It may also be formed into a spiral shape with corners. In such a case, there is an advantage that the pullout load of the bolt 10 can be further increased.

Further, in the embodiments shown in FIGS. 4 and 5, the axial length of the serration portion 16 of the bolt 10 is equal to the thickness of the metal plate 28, but the length is less than or equal to the thickness of the metal plate 28. It is also good.

Also, FIGS. 4 and 6 in the above-mentioned embodiments
The fitting process is explained in the figure, and the caulking process is explained in FIGS. After being press-fitted, there is no problem even if it is caulked at another location.

Further, the outer diameter of the annular projection 26 may be set so small that only the end of the serration 16 on the shaft portion 14 side abuts against the end surface of the projection 26. Further, the protrusion 26 may be partially protruded in the circumferential direction.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a front view of a bolt used in the method of the present invention. FIG. 2 is a cross-sectional view taken from the side of FIG. 1. FIG. 3 is a sectional view showing a receiving jig used in the method of the present invention. FIG. 4 is a diagram showing a fitting process in an application example of the method of the present invention. FIG. 5 is a diagram showing the caulking process following FIG. 4. FIGS. 6 and 7 are diagrams corresponding to FIGS. 4 and 5 showing other application examples of the method of the present invention. FIG. 8 is a diagram corresponding to FIG. 1 showing another example of the bolt used in the method of the present invention. 10: Bolt, 12: Head, 14: Shaft, 1
6: Serration portion, 28: Metal plate material, 30: Through hole.

Claims (1)

[Claims] 1. A head, a shaft having a smaller diameter than the head, and a shaft having a diameter smaller than the head and larger than the shaft, located between the head and the shaft. A fixing method for fixing a bolt to a metal plate material, the bolt having a serration portion having a plurality of protruding teeth formed on its outer peripheral surface, the bolt having a diameter larger than that of the shaft portion and the serration portion being formed on the metal plate material. forming a through hole with a smaller diameter by punching, and inserting the bolt into the through hole in the same direction as the punching direction, and forcing the serration part of the bolt into the through hole. a fitting step of fitting; and simultaneously or after the fitting step, the end of the serration portion on the shaft portion side is compressed toward the head to expand the diameter of the end; A method for fixing a bolt to a metal plate, the method comprising: a crimping step of crimping the part onto the metal plate. 2. A head, a shaft having a smaller diameter than the head, and a shaft located between the head and the shaft, having a smaller diameter than the head and a larger diameter than the shaft, and having a diameter on the outer peripheral surface. A fixing method for fixing a bolt having a serration portion in which a plurality of protruding teeth are formed to a metal plate, the metal plate having a through hole having a larger diameter than the shaft portion and a smaller diameter than the serration portion. a step of inserting the bolt into the through hole in the same direction as the punching direction, and a fitting step of forcibly fitting the serration portion of the bolt into the through hole; Simultaneously with or after the fitting process, the end of the serration section on the shaft section side, and the opening edge of the through hole, which is part of the metal plate material and into which the serration section is press-fitted, on the shaft section side. is compressed toward the head and crushed into the interior of the metal plate material, thereby expanding the diameter of the end of the serration portion and simultaneously reducing the diameter of the inner circumferential wall of the through hole on the shaft portion side. A method for fixing a bolt to a metal plate, the method comprising: caulking an end of a serration portion to the metal plate.