Bolt crimping structure, crimping bolt crimping method and crimping die

Abstract

The present invention is a crimp securing structure of a bolt, the structure being such that a crimp bolt 10 in which a crimping recess 13 is provided in the upper surface of a top part is secured by crimping to a metal sheet 30. The present invention is characterized in that the thickness of a metal material press-fitted into the crimping recess 13 of the crimp bolt is reduced at a central section so as to be less than that at a peripheral edge section of the crimping recess 13. In order to obtain this crimp securing structure, a crimping die 20 in which a stress-relief recess 23 is formed at a protruding central section is used to prevent the occurrence of excessive localized stress in the crimping recess 13.

Description

[Technical field]

[0001] The present invention relates to a bolt crimping and fixing structure, a crimping and fixing method for a crimp bolt, and a crimping die. [Background technology]

[0002] Crimp bolts are bolts that fix the head of the bolt to a metal plate by crimping it. Unlike weld bolts, they do not require heating and do not cause the metal plate to deform or discolor, so they are widely used in industrial fields.

[0003] As shown in Patent Document 1, crimp bolts are generally of the type having a crimping recess formed on the head seat, or the type having a crimping recess formed on the upper end of the shank directly below the seat, but as shown in Patent Document 3, a crimp bolt with a crimping recess on the top surface of the head is also known.

[0004] When a crimped bolt with a crimping recess on the top surface of its head is crimped to a metal plate, a convex crimping die is placed on the back surface of the metal plate, the crimped bolt is placed on the surface of the metal plate with its head facing downwards, and the bolt head is pressed with a punch. At this time, the metal plate is pressed by the convex part of the crimping die, and the metal material is forced into the crimping recess of the bolt, resulting in crimping as shown in Figure 8. The shaft of the crimped bolt protrudes from the metal plate and is used to attach other components.

[0005] In order to achieve a strong crimping fixation, it is necessary to plastically flow and fill the crimping recess with the metal material. However, if the pressure is increased for this purpose, the metal material pressed into the crimping recess will have nowhere to go due to the convex part of the die, and excessive local stress may occur in the crimping recess, causing deformation or destruction of the bolt head. In this case, the crimping strength will be reduced. Furthermore, if the pressure is reduced to avoid this phenomenon, the metal material cannot be pressed deep into the crimping recess, and the crimping strength will be reduced. Thus, it has not been easy to firmly crimp and fix a crimped bolt with a crimping recess on the top surface of the head. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-155860 A [Patent Document 2] JP 2019-138368 A [Patent Document 3] JP 2004-324813 A Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional method and provide a bolt crimping fixing structure, a method for crimping a crimp bolt, and a crimping die that can firmly crimp and fix a crimp bolt having a crimping recess on the top surface of its head to a metal plate. [Means for solving the problem]

[0008] The bolt crimping structure of the present invention, which has been made to solve the above problems, is a bolt crimping structure in which a crimping bolt is crimped and fixed without penetrating a metal plate, the crimping bolt is provided with a crimping recess on the top surface of its head, the bottom surface of the recess being flat, By making the press-fit distance of the metal material in the central portion of the caulking recess smaller than that in the peripheral portion, A metal material is pressed into the crimping recess. Axial The thickness is thin at the periphery of the caulking recess and thick at the center. And constant The present invention is characterized in that:

[0009] The method of crimping a crimp bolt of the present invention, which has been made to solve the above problems, is to place a crimp bolt having a crimping recess on the top surface of its head with its head facing downward on the surface of a metal plate, and to press a die having a diameter smaller than that of the crimping recess of the crimp bolt against the surface of the die. Ring-shaped A convex portion is formed, and the central portion of the convex portion is Flat bottom A crimping die with a stress relaxation recess is placed on the back surface of a metal plate, and the crimping bolt is driven into the metal plate with a punch without penetrating it, and the metal material is pressed into the crimping recess by the convex portion on the surface of the crimping die. By making the press-fit distance of the metal material in the central portion of the crimping recess smaller than that in the peripheral portion, the thickness of the metal material in the axial direction pressed into the crimping recess is made thinner at the peripheral portion of the crimping recess and thicker and constant at the central portion. The present invention is characterized by It is something.

[0010] The crimping die of the present invention, which has been made to solve the above problems, is used to crimp and fix a crimp bolt having a crimping recess on the top surface of the head with a flat bottom surface without penetrating the metal plate, and has a surface on which a crimping bolt is formed with a diameter smaller than that of the crimping recess of the crimping bolt. Ring-shaped A convex portion is formed, and the central portion of the convex portion is Flat bottom with no holes The present invention is characterized by the formation of a stress relaxation recess. Effect of the Invention

[0011] The bolt crimping structure of the present invention is a bolt having a flat bottom surface in a recess formed on the top surface of the head of the crimping bolt. Axial The thickness is made thicker in the center of the crimping recess, and the press-fit distance of the metal material in the center is made smaller than that of the peripheral area. This allows the metal material to flow deep into the crimping recess, and the press-fit distance of the metal material in the center is made smaller, suppressing the generation of excessive local stress in the crimping recess. This prevents the bolt head from being deformed or destroyed, and allows for strong crimping fixation.

[0012] In addition, the method of fixing the crimp bolt of the present invention is to fix the crimp bolt to the center of the convex portion. Flat bottom with no holes Since the crimping is performed using a crimping die and punch with stress relief recesses, the convex portion allows the metal material to be pressed deep into the crimping recess, and by allowing some of the metal material pressed into the crimping recess to escape into the stress relief recess, the generation of excessive local stress can be suppressed. This prevents the bolt head from being deformed or destroyed, and allows for strong crimping fixation. [Brief description of the drawings]

[0013] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a cross-sectional view showing a bolt crimping structure according to an embodiment. [Figure 4] FIG. [Diagram 5] FIG. 4 is a cross-sectional view showing a state before crimping begins. [Figure 6] FIG. 4 is a cross-sectional view showing a state immediately before the punch is lowered. [Figure 7] FIG. 11 is a cross-sectional view showing a state in which the punch is lowered. [Figure 8] FIG. 1 is a cross-sectional view showing a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the present invention will be described below. Figure 1 is a perspective view of a crimp bolt 10 used in this embodiment, and Figure 2 is a top view thereof. As shown in these figures, this crimp bolt 10 has a head 11 and a shaft 12, and a crimping recess 13 is formed on the top surface of the head 11. The bottom surface of the crimping recess 13 is flat, and the peripheral inner surface 14 of the crimping recess 13 is tapered, widening toward the bottom surface. In addition, the peripheral inner surface 14 of the crimping recess 13 is formed with uneven portions 15 for preventing rotation.

[0015] 3 shows a crimping structure in which the crimp bolt 10 is crimped and fixed to a metal plate 30. As shown in the figure, the metal material of the metal plate 30 is plastically pressed into the crimping recess 13 of the crimp bolt 10. Axial The thickness is thin at the periphery of the crimping recess 13 and thick at the center. That is, the metal material is pressed deep into the periphery of the crimping recess 13, thereby obtaining sufficient crimping strength. The metal material also bites into the rotation-preventing unevenness 15 formed on the inner peripheral surface 14 of the crimping recess 13, thereby obtaining sufficient rotation-preventing strength.

[0016] In contrast, the press-fit distance of the metal material is smaller at the center of the crimping recess 13 than at the periphery. In the conventional structure shown in Figure 8, the thickness of the metal material pressed into the crimping recess 13 is constant, and this is a feature of the crimping structure of the present invention. By reducing the press-fit distance of the metal material into the crimping recess 13 in this way, the generation of excessive local stress within the crimping recess 13 is suppressed. This prevents the bolt head from being deformed or destroyed as in the conventional structure, and enables strong crimping and fixation.

[0017] Next, the method of crimping the crimp bolt of the present invention will be described. For this method, a special crimping die 20 as shown in Fig. 4 is used. This crimping die 20 is made of hard metal, and the upper surface 21 of the cylindrical body is flat, and in the center Ring-shaped A convex portion 22 is formed. This convex portion 22 has the role of press-fitting a metal plate into the inside of the crimping recess 13 of the crimp bolt 10 and causing the metal material to plastically flow. For this reason, the outer diameter of this convex portion 22 is formed smaller than the inner diameter of the crimping recess 13.

[0018] A stress relaxation recess 23 is formed in the center of this convex portion 22. As shown in Fig. 5, in this embodiment, the bottom surface of the stress relaxation recess 23 is flat. The height of the bottom surface of the stress relaxation recess 23 is the midpoint between the surface 21 of the die and the convex portion 22. The specific dimensions are determined according to the material and thickness of the metal plate 30 that is the counterpart material. will be done.

[0019] To fix the crimp bolt 10 to the metal plate 30 by crimping using the crimping die 20 configured in this way, first, as shown in Fig. 5, the crimping die 20 is placed on the back surface of the metal plate 30, and the crimp bolt 10 is placed on the front surface of the metal plate 30 with the head facing downward. As in the conventional case, the crimping die 20 and the crimp bolt 10 are positioned so that they are on the same axis. In this state, the metal plate 30 is on the convex portion 22 of the crimping die 20. Next, a punch 40 is placed above the crimp bolt 10 as shown in Fig. 6. The punch 40 has a recess 41 formed therein into which the shaft portion 12 of the crimp bolt 10 is inserted, and the flat lower surface 42 has a larger diameter than the head 11 of the crimp bolt 10.

[0020] From this state, the punch 40 is lowered as shown in Fig. 7, and the crimp bolt 10 is driven into the metal plate 30. At this time, the metal material of the metal plate is plastically flowed by the convex portion 22 on the surface of the die 20 into the crimping recess 13 of the crimp bolt 10, and the crimp bolt 10 is crimped and fixed to the metal plate 30. Ring-shaped The metal material is pressed deep into the crimping recess 13 by the convex portion 22, and is in close contact with the peripheral inner surface 14 of the tapered crimping recess 13 that widens toward the bottom surface, and is also bitten into the anti-rotation uneven portion 15. This provides excellent pull-out strength and anti-rotation strength.

[0021] During the crimping, a part of the metal material flows into the stress relaxation recess 23 formed in the center of the convex portion 22 of the die 20. As a result, the crimped structure of the present invention shown in FIG. 3 is obtained. According to the crimping method of the present invention, it is possible to suppress the occurrence of excessive local stress compared to the case of using a conventional die without the stress relaxation recess 23. Therefore, the bolt head is not deformed or destroyed, and a strong crimping can be achieved as shown in FIG. 3. The area and depth of the stress relaxation recess 23 are determined according to the material and thickness of the metal plate 30, but if the height of the bottom surface of the stress relaxation recess 23 is set to the intermediate height between the surface 21 of the die and the convex portion 22, the metal plate 20 is reliably pressed even at the center of the stress relaxation recess 23, so there is no risk of the crimping strength decreasing. The shaft 12 of the crimped bolt 10 is used to attach other members.

[0022] As described above, according to the present invention, superior crimping strength can be obtained compared to the case where a conventional die not having the stress relaxation recesses 23 is used. [Explanation of symbols]

[0023] 10 Crimp bolt 11 Head 12 Shaft 13 Caulking recess 14. Inner periphery 15 Anti-rotation concave and convex part 20 Crimping dies 21 Surface 22 Convex part 23 Stress relief recess 30 metal plate 40 Punch 41 Recess 42 Bottom surface

Claims

1. A crimping and fixing structure for a bolt in which the crimping bolt is crimped and fixed without penetrating a metal plate, wherein the crimping bolt has a crimping recess with a flat bottom surface on the top surface of its head, and the pressing distance of the metal material in the center of the crimping recess is smaller than that of the peripheral portion, so that the axial thickness of the metal material pressed into the crimping recess is thin at the peripheral portion of the crimping recess and thick and constant in the central portion.

2. a crimping die having a ring-shaped convex portion on the surface of a die which is smaller in diameter than the crimping concave portion of the crimping bolt and a stress relief concave portion with a flat bottom in the center of the convex portion is placed on the back surface of the metal plate, and the crimping bolt is driven into the metal plate with a punch without penetrating it, and a metal material is pressed into the crimping concave portion by the convex portion on the surface of the crimping die, and a pressing distance of the metal material in the center of the crimping concave portion is made smaller than that of the peripheral portion, thereby making the axial thickness of the metal material pressed into the crimping concave portion thinner at the peripheral portion of the crimping concave portion and thicker and constant in the central portion.

3. A crimping die used to crimp a crimping bolt having a crimping recess with a flat bottom surface on the top surface of its head without penetrating the metal plate, characterized in that a ring-shaped convex portion having a smaller diameter than the crimping recess of the crimping bolt is formed on the surface of the die, and a stress relief recess with a flat bottom surface and no holes is formed in the center of this convex portion.

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