JPH09303364A - Bolt fastening structure and bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of looseness, and to prevent the generation of breakdown accident even in the case where looseness is generated by providing a bolt with a shaft part, a tool receiver part, a taper part and a male screw part, and providing a base part with a taper hole part and a female screw part, and fitting the bolt in the base part, and fastening the bolt in the condition that the bolt shaft part is exposed outside of the base part. SOLUTION: In this structure, a bolt 11 is fitted in a base part 12, and a male screw part 16 of the bolt 11 is screwed with a female part 18 of a base part 12 for fastening, and a taper part 15 of the bolt 11, which is formed at about 60 degree, is made to tightly contact with a taper hole part 17 of the base part 12, and a shaft part 13 of the bolt 11 is exposed outside of the base part 12. Since the taper part 15 is formed at a certain length, it can be twisted for deformation between the male screw part 16, and several times of the torque in comparison with that of the male screw part 16 can be applied to the taper part 15. Furthermore, the taper part 15 is formed into a wedge shape, a contact surface thereof can with stand a high pressure, and furthermore, since the contact area thereof is large, friction force for preventing the generation of looseness effectively work. Even in the case where looseness is generated, since the taper part 15 is formed thick and the surface thereof is formed smooth so as to prevent the generation of concentration of stress, breakdown is hard to be generated in the taper part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a bolt tightening structure used when a shaft such as a support shaft, a rotary shaft, and a guide post which receives a load from the side is fixedly provided, and the structure. Regarding bolts.

[0002]

Conventionally, a bolt tightening structure 1 shown in FIG. 3 has been used for a support shaft and the like.
That is, the bolt 2 includes a hexagonal head 3, a shaft portion 4, and a male screw portion 5.
And a step portion 6 is formed between the shaft portion 4 and the male screw portion 5, and the bolt 2 is screwed into the female screw portion 8 of the base portion 7 and tightened.

In this structure 1, the load applied to the shaft portion 4 from the side is supported by the coupling between the male screw portion 5 and the female screw portion 8 and the friction between the base surface of the step portion 6. It is difficult to obtain a large value for the frictional force of the stepped portion 6, because it is simply generated by the force of the bolt 2 pushing the surface of the base portion. Further, when the tightening is loosened, this frictional force is significantly reduced, and the load is concentrated and applied to the screw portion, particularly the first mountain portion on the shaft side of the male screw portion 5, so that the portion is easily broken.

Therefore, the present invention has been devised for the purpose of making it hard to loosen, and making it less likely to cause a damage accident even if it loosens.

[0005]

According to the bolt tightening structure of the present invention, a bolt is formed on a shaft portion which receives a load from the side and a rear portion, an inner portion or a periphery of the shaft portion, which engages with a tool to rotate. Has a tool receiving portion, a taper portion provided in front of the shaft portion and having a shape such that the front is narrowed, and a male screw portion formed in front of the taper portion, and a base portion of the bolt portion. Has a taper hole portion that is in contact with the taper portion and a female screw portion that is formed deep inside the taper hole portion and that engages with the male screw portion of the bolt. The bolt tightening structure is characterized in that the bolt is exposed outside the base and tightened.

The bolt of the present invention includes a shaft portion that receives a load from the side, a tool receiving portion that is formed behind, inside or around the shaft portion and that is engaged with a tool to rotate, and the shaft. A bolt having a tapered portion provided in front of the tapered portion and having a tapered shape in the front, and a male screw portion formed in front of the tapered portion.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for illustrating the present invention will be specifically described.

FIG. 1 shows a bolt tightening structure 10. The structure 10 includes a bolt 11 and a base 12.

The bolt 11 includes a shaft portion 13 and a tool receiving portion 1.
4, a taper portion 15, and a male screw portion 16. Shaft 13
Has a cylindrical shape and receives a load from the side. The tool receiving portion 14 is composed of a hexagonal head formed on the rear side (left side in the drawing) of the shaft portion 13, and is adapted to be engaged with a tool such as a wrench and rotated. The taper portion 15 is provided in front of the shaft portion 13 (to the right in the drawing), and is formed in a taper shape in which the front portion becomes thinner at an angle of about 60 degrees. The male screw portion 16 is provided in front of the tapered portion 15 and is made of a male screw similar to a normal bolt.

The base portion 12 includes a tapered hole portion 17 and a female screw portion 1.
8 The tapered hole portion 17 is located on the surface portion of the base portion 12 and can contact the tapered portion 15 of the bolt. The female screw portion 18 is formed deep inside the tapered hole portion 17 and can be screwed with the male screw portion 16 of the bolt.

In this structure 10, the bolt 11 is fitted to the base portion 12, the male screw portion 16 of the bolt is screwed into the female screw portion 18 of the base and tightened, the taper portion 15 is brought into close contact with the taper hole portion 17, and the shaft portion is formed. It is completed by exposing 13 to the outside of the base.

FIG. 2 shows a bolt tightening structure 20. The structure 20 includes a bolt 21 and a base portion 22.

The bolt 21 includes a shaft portion 23 and a tool receiving portion 2.
4, a taper portion 25, and a male screw portion 26. Shaft 23
Has a cylindrical shape and receives a load from the side. The tool receiving portion 24 is formed of a hexagonal hole formed at the rear (left side in the drawing) of the shaft portion 23 or inside thereof, and is adapted to be engaged with a tool such as a wrench and rotated. The tapered portion 25 is the shaft portion 2.
It is provided in front of 3 (to the right in the figure), and is formed in a tapered shape in which the front becomes thin at an angle of about 30 degrees. Male screw part 26
Is provided in front of the taper portion 25 and is made of a male screw similar to a normal bolt.

The base portion 22 includes a tapered hole portion 27 and a female screw portion 2.
8 The taper hole portion 27 is formed in the plate body forming the base portion 22 and can contact the taper portion 25 of the bolt. The female screw portion 28 is made of a normal nut and is screwed with the male screw portion 26 of the bolt that penetrates the tapered hole portion 27.

In this structure 20, the bolt 21 is fitted in the tapered hole portion 25 of the base portion 22, and the male screw portion 26 of the bolt is screwed into the female screw portion 28 to be tightened so that the tapered portion 25 is brought into close contact with the tapered hole portion 27. It is completed by exposing the shaft portion 23 to the outside of the base portion.

In each of the above-mentioned embodiments, the shaft portion of the bolt has a cylindrical shape, but it can have various shapes such as a prismatic shape depending on the application. The tool receiving portion is not limited to the hexagonal head and hexagonal hole described above, and may be a cross hole, a slot, or the like, as long as it can be engaged with the tool to rotate, and is provided on the rear or inside of the shaft portion. In addition, the shaft portion may be formed into a hexagonal column shape, and the outer periphery of the shaft portion may be used as a tool receiving portion as it is. The angle of the taper portion can be set variously according to the use and the like, and is preferably set to approximately 90 degrees or less.

[0017]

As described above, the bolt tightening structure and the bolt of the present invention have the tapered portion and the tapered hole portion. Therefore, the load applied to the shaft portion is the combination of the male screw portion and the female screw portion, and the taper portion. , Is supported by the joint surface of the tapered hole portion. The supporting force at the joining surface of the taper portion and the tapered hole portion is different from the supporting force at the step portion of the conventional structure being a mere frictional force.
Since the reaction force at the joint surface is used, it is extremely large and stable.

Further, it is difficult to loosen due to the following action. That is, the tightening force of the bolt is usually limited by the breaking strength of the threaded portion. According to the rule of thumb, the torque of the conventional bolt step is almost equal to that of the threaded portion. Since the tapered portion of the bolt of the present invention has a length, it can be twisted and deformed with the male screw portion, and a torque several times as large as that of the male screw portion can be applied. Further, since the tapered portion has a wedge shape, a wedge action works. Therefore, the pressure on the contact surface of the tapered portion can be significantly increased. In addition, since the contact area of the tapered portion is several times larger than that of the conventional stepped portion, the frictional force for preventing loosening also works effectively.

The bolt of the present invention has the property of not easily breaking even if it is loosened. That is, when loosened, the load is concentrated and borne by the taper portion near the shaft portion, but this taper portion is thicker than the threaded portion of the conventional bolt, the surface is smooth, and stress concentration is concentrated. Since it is a shape that does not easily occur, it does not break easily.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing another embodiment of the present invention.

FIG. 3 is a side sectional view showing a conventional form.

[Explanation of symbols]

10 ... Bolt tightening structure, 11 ... Bolt, 12 ... Base part,
13 ... Shaft part, 14 ... Tool receiving part, 15 ... Tapered part, 16
... Male screw portion, 17 ... Taper hole portion, 18 ... Female screw portion. 20
... Bolt tightening structure, 21 ... Bolt, 22 ... Base part, 23
... Shaft part, 24 ... Tool receiving part, 25 ... Tapered part, 26 ... Male screw part, 27 ... Tapered hole part, 28 ... Female screw part.

Claims (2)

[Claims] 1. A shaft portion in which a bolt receives a load from a side, a tool receiving portion formed behind, inside or around this shaft portion and engaged with a tool to rotate, and a front portion of the shaft portion. And a taper part that has a shape that becomes thinner at the front,
A male screw portion formed in front of the tapered portion, and a base portion having a tapered hole portion in contact with the tapered portion of the bolt,
It has a female screw portion formed at the back of the tapered hole portion and screwed with the male screw portion of the bolt, the bolt is fitted to the base portion, and the shaft portion of the bolt is exposed outside the base portion and tightened. Characteristic bolt tightening structure. 2. A shaft portion which receives a load from a lateral side, a tool receiving portion which is formed at the rear, inside or around the shaft portion and is engaged with a tool to rotate, and provided in front of the shaft portion. And a male screw portion formed in front of the tapered portion.