Locking structure of bolt, locking method of self-locking bolt, and locking mold

Abstract

This invention relates to a bolt locking and fixing structure for a bolt obtained by locking a self-locking bolt (10) having a locking recess (13) on the upper surface of the head to a metal plate (30). The characteristic feature is that the thickness of the metal material pressed into the locking recess (13) of the self-locking bolt is thinner at the periphery and thicker at the center. To obtain this locking and fixing structure, a locking mold (20) having a stress-relieving recess (23) at the center of the convex portion is used to prevent excessive local stress from being generated within the locking recess (13).

Description

Technical Field

[0001] This invention relates to a bolt locking and fixing structure, a self-locking bolt locking and fixing method, and a locking mold. Background Technology

[0002] Self-locking bolts are bolts whose heads are locked and fixed to a metal plate. Since they do not require heating like welded bolts, the metal plate will not deform or discolor, and they are widely used in industrial fields.

[0003] As shown in Patent Document 1, self-locking bolts generally come in two types: those with a locking recess formed on the head support surface and those with a locking recess formed on the upper end of the shaft portion directly below the support surface. However, as shown in Patent Document 3, self-locking bolts with a locking recess on the upper surface of the head are also known.

[0004] When fastening a self-locking bolt with a locking recess on its upper surface to a metal plate, a convex locking die is positioned on the back of the metal plate, and the self-locking bolt is placed on the surface of the metal plate with its head facing down. A punch is then used to press the bolt head. At this time, the metal plate is pressed by the convex part of the locking die, causing the metal material to be pressed into the locking recess of the bolt. Figure 8 The bolt is shown as being locked and secured. Because the shaft of the bolt protrudes from the metal plate after being locked and secured, it is used to install other components.

[0005] For a secure locking mechanism, the metal material needs to plastically flow into and fill the locking recess. However, if the pressure is increased for this purpose, the metal material pressed into the locking recess by the mold's protrusion has nowhere to go, potentially creating excessive localized stress within the recess and causing the bolt head to deform or break. This reduces the locking strength. Conversely, if the applied pressure is reduced to avoid this phenomenon, the metal material cannot be pressed deep into the locking recess, further reducing the locking strength. Consequently, it becomes difficult to securely lock the bolt with the locking recess on its head surface.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-155860

[0009] Patent Document 2: Japanese Patent Application Publication No. 2019-138368

[0010] Patent Document 3: Japanese Patent Application Publication No. 2004-324813 Summary of the Invention

[0011] Therefore, the purpose of this invention is to solve the above-mentioned problems and provide a locking and fixing structure, a locking and fixing method for a self-locking bolt having a locking recess on the upper surface of the head and a locking mold for securely locking and fixing a bolt to a metal plate.

[0012] The bolt locking and fixing structure of the present invention, made to solve the above problems, is obtained by locking and fixing a self-locking bolt to a metal plate. Its characteristic is that the self-locking bolt has a locking recess on the upper surface of its head, and the thickness of the metal material pressed into the locking recess is thin at the periphery and thick at the center.

[0013] Furthermore, the locking and fixing method for the self-locking bolt of the present invention, made to solve the above-mentioned problems, is characterized in that: a self-locking bolt having a locking recess on its upper head surface is disposed on the surface of a metal plate with its head facing downwards; a locking mold having a protrusion formed on its surface and a stress-relieving recess formed in the center of the protrusion is disposed on the back side of the metal plate; a punch is used to drive the self-locking bolt into the metal plate; and the metal material is pressed into the locking recess by the protrusion on the surface of the mold. As will be described later, the shape of the stress-relieving recess is not limited to a shape with a flat bottom surface and can be deformed in various ways.

[0014] In addition, the locking mold of the present invention, made in order to solve the above problems, is used to lock and fix a self-locking bolt having a locking recess on the upper surface of the head to a metal plate. Its feature is that a convex portion is formed on the surface of the mold, and a stress-relieving recess is formed in the center of the convex portion.

[0015] Invention Effects

[0016] In the bolt locking structure of the present invention, the thickness of the metal material pressed into the locking recess formed on the upper surface of the head of the self-locking bolt is thicker in the central part of the locking recess, and the pressing distance of the metal material in the central part is smaller than that of the metal material in the peripheral part. Therefore, the metal material can flow deep into the locking recess, and the pressing distance of the metal material in the central part is small, thereby suppressing excessive local stress generated in the locking recess. Therefore, the bolt head will not be deformed or damaged, and a firm locking and fixing can be achieved.

[0017] Furthermore, in the locking and fixing method of the self-locking bolt of the present invention, a locking die and a punch with a stress-relieving recess formed in the center of the convex portion are used for locking. Therefore, the metal material can be pressed deep into the locking recess using the convex portion, and by allowing a portion of the metal material pressed into the locking recess to enter the stress-relieving recess, excessive local stress can be suppressed. Therefore, the bolt head will not be deformed or damaged, and a firm locking and fixing can be achieved. Attached Figure Description

[0018] Figure 1 This is a 3D diagram of a self-locking bolt.

[0019] Figure 2 This is a top view of a self-locking bolt.

[0020] Figure 3 This is a cross-sectional view showing the bolt locking structure of the embodiment.

[0021] Figure 4 It is a 3D view of the locking mold.

[0022] Figure 5 It is a cross-sectional view showing the state before locking begins.

[0023] Figure 6 It is a cross-sectional view showing the state just before the punch is about to descend.

[0024] Figure 7 It is a cross-sectional view showing the state after the punch has descended.

[0025] Figure 8 It is a cross-sectional view representing the prior art. Detailed Implementation

[0026] The following describes embodiments of the present invention.

[0027] Figure 1 This is a perspective view of the self-locking bolt 10 used in this embodiment. Figure 2 This is its top view. As shown in these figures, the self-locking bolt 10 has a head 11 and a shaft portion 12, and a locking recess 13 is formed on the upper surface of the head 11. The bottom surface of the locking recess 13 is flat, and the surrounding inner surface 14 of the locking recess 13 is tapered, extending towards the bottom surface. In addition, an anti-rotation protrusion 15 is formed on the surrounding inner surface 14 of the locking recess 13.

[0028] Figure 3 This describes a locking structure that secures the self-locking bolt 10 to the metal plate 30. As shown, the metal material of the metal plate 30 is plastically pressed into the locking recess 13 of the self-locking bolt 10. The thickness of the metal material is thinner at the periphery and thicker at the center of the locking recess 13. That is, the metal material is pressed deeper at the periphery of the locking recess 13, thereby achieving sufficient locking strength. In addition, the metal material is also embedded in the anti-rotation protrusion 15 formed on the inner surface 14 surrounding the locking recess 13, thereby achieving sufficient anti-rotation strength.

[0029] In contrast, the pressing distance of the metal material in the central part of the locking recess 13 is smaller than that in the peripheral part. Figure 8In the existing structure shown, the thickness of the metal material pressed into the locking recess 13 is constant; therefore, this is a characteristic of the locking structure of the present invention. By making the pressing distance of the metal material pressed into the locking recess 13 smaller in this way, excessive local stress within the locking recess 13 is suppressed. Therefore, unlike the prior art, the bolt head will not deform or break, and a secure locking fixation can be achieved.

[0030] Next, the locking and fixing method of the self-locking bolt of the present invention will be described. In this locking and fixing method, a method is used... Figure 4 The special locking mold 20 shown is made of hard metal. The upper surface 21 of the cylindrical body is flat, and a circular convex portion 22 is formed in its center. This convex portion 22 has the function of pressing the metal plate into the locking recess 13 of the self-locking bolt 10 and causing the metal material to flow plastically. Therefore, the outer diameter of the convex portion 22 is formed to be smaller than the inner diameter of the locking recess 13.

[0031] A stress-relieving recess 23 is formed in the center of the convex portion 22. For example... Figure 5 As shown, in this embodiment, the bottom surface of the stress-relieving recess 23 is flat. Furthermore, the height of the bottom surface of the stress-relieving recess 23 is the height between the surface 21 of the mold and the convex portion 22. The specific dimensions are determined based on the material and thickness of the metal plate 30 of the target component. Moreover, the stress-relieving recess 23 is not limited to the shape with a flat bottom surface as in this embodiment; it can also have, for example, a shape with a conical convex shape, an annular groove or protrusion, a trapezoidal protrusion, etc., formed on the bottom surface.

[0032] When using the locking mold 20 configured in this way to lock and fix the self-locking bolt 10 to the metal plate 30, firstly, as... Figure 5 As shown, the locking mold 20 is positioned on the back side of the metal plate 30, and the self-locking bolt 10 is positioned on the surface of the metal plate 30 with its head facing downwards. As in the prior art, the locking mold 20 and the self-locking bolt 10 are positioned coaxially. In this state, the metal plate 30 rests on the protrusion 22 of the locking mold 20. Next, as... Figure 6 As shown, the punch 40 is positioned above the self-locking bolt 10. A recess 41 is formed on the punch 40 for the shaft portion 12 of the self-locking bolt 10 to be inserted, and the diameter of the flat lower surface 42 is larger than the diameter of the head 11 of the self-locking bolt 10.

[0033] From this state, the punch is 40 as... Figure 7The plate descends in that manner, driving the self-locking bolt 10 into the metal plate 30. At this time, the metal material of the metal plate plastically flows through the protrusion 22 on the surface of the mold 20 and is pressed into the locking recess 13 of the self-locking bolt 10, thereby locking the self-locking bolt 10 to the metal plate 30. Figure 6 As shown, the metal material is pressed into the depth of the locking recess 13 by the circular protrusion 22 of the mold 20, and comes into close contact with the inner surface 14 of the tapered locking recess 13 that extends toward the bottom surface, and is embedded in the anti-rotation protrusion 15. As a result, excellent pull-out strength and anti-rotation strength can be obtained.

[0034] Additionally, during the locking process, a portion of the metal material flows to the stress-relieving recess 23 formed in the center of the convex portion 22 of the mold 20. As a result, it becomes... Figure 3 The locking structure of the present invention is shown. According to the locking and fixing method of the present invention, compared with the use of existing molds without stress-relieving recesses 23, excessive local stress can be suppressed. Therefore, the bolt head will not deform or break, and it can achieve... Figure 3 The locking mechanism is securely tightened as shown. The area and depth of the stress-relieving recess 23 are determined based on the material and thickness of the metal plate 30. However, if the height of the bottom surface of the stress-relieving recess 23 is equal to the height between the surface 21 of the mold and the protrusion 22, the metal plate 20 will also be reliably pressurized at the center of the stress-relieving recess 23. Therefore, there is no need to worry about a reduction in locking strength. The shaft portion 12 of the self-locking bolt 10 is used to mount other components.

[0035] As explained above, according to the present invention, superior locking strength can be obtained compared to the use of existing molds without stress-relieving recesses 23.

[0036] Explanation of reference numerals in the attached figures

[0037] 10…Self-locking bolt; 11…Head; 12…Shaft; 13…Locking recess; 14…Surrounding inner surface; 15…Anti-rotation recess; 20…Locking mold; 21…Surface; 22…Protrusion; 23…Stress relief recess; 30…Metal plate; 40…Punch; 41…Recess; 42…Lower surface.

Claims

1. A bolt locking and fixing structure, which is obtained by locking and fixing a self-locking bolt to a metal plate in a manner that does not penetrate the metal plate, characterized in that: The self-locking bolt has a locking recess on the upper surface of the head, with a flat bottom surface and a tapered inner surface that expands towards the bottom surface. On the radially inner side of the opening of the locking recess, the thickness of the metal material pressed into the locking recess is thin at the periphery and thick at the center.

2. A method for locking and fixing a self-locking bolt, which forms the locking and fixing structure of the bolt as described in claim 1, characterized in that: A self-locking bolt with a flat bottom surface and a tapered locking recess extending towards the bottom surface on the upper surface of the head is positioned with its head facing downwards on the surface of a metal plate. A locking mold with a circular convex portion formed on the surface of the mold and a stress-relieving recess formed in the center of the convex portion is positioned on the back of the metal plate. A punch is used to drive the self-locking bolt into the metal plate without penetrating it. The metal material is pressed into the locking recess through the convex portion of the mold surface.

3. A locking mold, used in the locking and fixing method of the self-locking bolt according to claim 2, for locking and fixing a self-locking bolt with a locking recess on the upper surface of its head to a metal plate in a manner that does not penetrate the metal plate, characterized in that: A circular convex portion is formed on the surface of the mold, and a stress-relieving concave portion is formed in the center of the convex portion. The convex part of the mold is used to press the metal plate into the locking recess of the self-locking bolt.

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