JPH1162935A - Torque control bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform strict management of torque without using a torque wrench and to prevent a fastening head part from falling from a bolt body, in fixing by a bolt. SOLUTION: A torque control bolt comprises a bolt body 2 having a stem part 22 and a head part 21; a fastening head part 4 having a lock groove 41 formed on an outer periphery coupled through a stress concentrating part 3 broken when a given load is applied; and a coup-ling body 5 having lock parts 53 locked at respective lock grooves 41 formed in the tips of a plurality of arm parts 52 extending from the edge of a bottom part 51, having a through- hole 50 in which the stem part 22 of the bolt body 2 is loosely fitted, vertically to the bottom 51. Namely, when, by inserting the stem part 22 of the bolt body 2 in the through-hole 50 of the coupling body 5 and fitting the locking part 53 in a lock groove 41, the fastening head part 4 is fastened, even after a stress concentrating part 3 is broken by torque exceeding a given value, a state that the fastening head part 4 is coupled to a bolt body 2 is maintained by the coupling body 5 and a fall is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt for fixing a member, and more particularly to a torque control bolt requiring torque management.

[0002]

2. Description of the Related Art When two or more members are fixed by tightening bolts, the fixing is insufficient when the torque is less than necessary, but the object to be fixed may be damaged when tightening with more torque than necessary. is there.

[0005] For example, as shown in FIG. 5, at the connection portion of the electric wire 71, the ends of both the electric wires 71, 71 are compressed by tightening a connector 73 having a saw-toothed tip with a bolt 72. By cutting into the electric wire 71, both electric wires 71, 71 may be conducted.
At this time, if the connector 73 is too tightly tightened,
1 is unnecessarily damaged, and if it is too weak, conduction becomes insufficient. Therefore, it is necessary to strictly control the range of torque control.

However, it is extremely inefficient and troublesome to perform the work of tightening the individual bolts 72 while checking the torque load with a torque wrench or the like, and it is difficult to control the torque strictly. It was easy for the wire 71 to be excessively damaged due to insufficient or excessive tightening.

Accordingly, conventionally, as shown in FIG. 6, using a torque control bolt 81 in which a tightening head 85 is connected to a head 83 of a bolt body 82 via a stress concentration point 84,
When the tightening head 85 is tightened beyond a predetermined torque, it is broken at the stress concentration point 84 to separate the tightening head 85 from the bolt body 82, thereby confirming that the tightening operation has been completed. It has been known.

However, such a torque control bolt 8
1 is that after the tightening head 85 is broken at the stress concentration point 84, it falls off from the bolt body 82. Therefore,
When working at a high place, such as the above-described work for conducting electric wires, it is extremely dangerous to drop many fastening heads 85.
5 had to be collected one by one so as not to drop, which was troublesome. Further, when such a torque control bolt 81 is used in a precision instrument or the like, the fastening head 85 may enter the inside of the instrument and cause a malfunction.

[0007]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is that when torque management is required for fixing with a bolt, it is extremely troublesome and strict to control the torque using a torque wrench. Management is difficult,
In addition, the conventional torque control bolt is said to have a problem in that it is troublesome to collect and collect because the tightening head is separated, or may cause a malfunction in the case of precision equipment. Is a point.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides, as a first means, a bolt body having a shaft and a head, and the bolt body is broken when a predetermined load is applied to the head. A fastening head connected via a stress concentrating portion and provided with a locking groove on the outer periphery, and a bottom portion provided with a through hole into which the shaft portion of the bolt body is loosely fitted. And a connecting body formed with a locking portion that can be locked in the locking groove at the tip of a plurality of arm portions extending toward the locking portion.

That is, by inserting the shaft portion of the bolt main body into the through hole of the connecting body and fitting the locking portion into the locking groove, when tightening the tightening head, the torque exceeds a predetermined torque. Even after the stress concentration portion is broken, the tightening head is kept connected to the bolt body by the connecting body so as not to fall off.

Further, since the connecting body is loosely fitted to the bolt main body, even if the tightening head is turned after the stress concentration portion is broken, the tightening head and the connecting body idle and the bolt main body turns. There is no further tightening.

According to a second aspect of the present invention, there is provided a bolt body having a shaft portion and a head and having a locking groove formed on the outer periphery of the head, and a predetermined load is applied to the head of the bolt body. A fastening head which is connected via a stress concentration portion which is broken when it is broken, and which has a large diameter portion on the tip side, and an edge of a top portion provided with a through hole into which the fastening head is loosely fitted. A plurality of arms extending in the vertical direction, and having a locking portion formed at the distal end of the plurality of arms so as to be locked in the locking groove. When the tightening head is tightened, the tightening head does not fall off the bolt body after the stress concentration portion breaks beyond a predetermined torque when the tightening head is tightened.

Furthermore, the present invention provides, as a third means, a tightening head via a stress concentration portion which is broken when a predetermined load is applied to a head of a bolt body having a shaft and a head. Are connected, and furthermore, the head and the tightening head are connected by a linear body having a predetermined slack, so that after the stress concentration part is broken, the linear body is tightened. Is connected to the bolt body so as not to fall off.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of an embodiment of the present invention. A stress concentration portion 3 is formed on the base end side of a head 21 of a bolt body 2 so as to be easily broken. A fastening head 4 that can be fastened with tools such as a spanner is connected.

The stress concentration portion 3 may be a thin shaft located on the central axis as shown in FIG. 1, or may be thin along the outer circumference of the fastening head 4 and the head 21. It may be connected. In any case, the tightening head 4 is tightened using a tightening tool such as a wrench so that the bolt main body 2 is screwed into the object to be fixed and exceeds a predetermined torque, and at the same time, the stress concentration portion 3 is broken. It is formed.

On the other hand, on the outer periphery of the fastening head 4, a locking groove 41 is provided.
Are formed. As shown in FIG. 1, the locking groove 41 may be a part of the outer periphery, such as two opposing portions, or may be formed in an annular shape over the entire periphery.

As shown in FIG. 2, the connecting body 5 has a disc-shaped bottom portion 51 having a through hole 50 formed at the center thereof, and an upwardly extending position from a position where a peripheral edge of the bottom portion 51 faces. Two extending arm portions 52, and a fastening head 4 projecting inward from the distal end of the arm portions 52 in parallel with the bottom portion 51.
The through hole 50 has a diameter slightly larger than the shaft portion 22 of the bolt body 2. The shaft 2 of the bolt body 2 is inserted into the through hole 50.
2, and the connecting portion 5 is attached to the bolt body 2 and the tightening head 4 by fitting the locking portion 53 into the locking groove 41. At this time, it is preferable to set the length of the arm 52 so that the bottom 51 of the connector 5 is located at the base end of the shaft 22 of the bolt body 2.

Thus, the bolt body 2 and the tightening head 4
Are connected by the connecting body 5, the locking portion 53 is fitted in the locking groove 41 and the head 21 does not pass through the through hole 50 even if the stress concentration portion 3 is broken. The fastening head 4 does not fall off. Moreover, the shaft portion 22 has the through hole 5
The bolt body 2 does not rotate even if the connecting body 5 fitted and fixed to the locking portion 53 rotates together with the tightening head 4 after the stress concentration portion 3 is broken, because the fitting portion 5 is loosely fitted. Therefore, after the stress concentration portion 3 breaks due to the application of a predetermined torque or more, the tightening head 4 idles together with the connecting body 5 so that the resistance to the tightening suddenly weakens, thereby completing the tightening. That can be confirmed.

In this way, the accuracy of the torque control can be kept within the range of the variation in the strength of the stress concentration portion 3, so that the torque can be controlled very accurately only by performing a normal tightening operation, and the tightening can be performed. The falling off of the head 4 can be prevented.

FIG. 3 shows a different embodiment of the present invention.

A locking groove 23 is formed on the outer periphery of the head 21a of the bolt body 2a, and can be fastened to the base end side of the head 21a with a tool such as a wrench via the stress concentration portion 3a. The fastening head 4a is connected. In addition, a rib-shaped large-diameter portion 42 is formed on the tip end side of the fastening head 4a.
Note that the locking groove 23 may be formed over the entire outer circumference of the head 21a, or may be formed at two opposing locations or at a plurality of locations.

A connecting body 5a having substantially the same shape as the connecting body 5 shown in FIG. 2 is attached to the bolt body 2a and the tightening head 4a by using the embodiment shown in FIG. 1 upside down. That is, the connecting body 5a has a disc-shaped top 51a having a through hole 50a slightly larger in diameter than the fastening head 4a, and a top 5a.
1a, two arms 52a extending downward from a position facing the peripheral edge, and a head 2 projecting inward from the tip of the arm 52a in parallel with the top 51a and inward.
1a, and a locking portion 53a fitted into the locking groove 23 of FIG. The fastening head 4a is inserted into the through hole 50a, and the locking portion 53a is fitted into the locking groove 23.

Thus, the bolt body 2a and the tightening head 4a
After the stress concentration portion 3a is broken, the locking portion 53a is fitted in the locking groove 23 and the large diameter portion 42 does not pass through the through hole 50a. The attached head 4a does not fall off. Moreover, the connecting body 5a
Is loosely fitted to the fastening head 4a, so that the stress concentration portion 3a
After the fracture, the bolt body 2a does not rotate even if the tightening head 4a is rotated. Therefore, it is possible to confirm that the tightening has been completed in the same manner as in the above-described embodiment.

In the embodiments shown in FIGS. 1, 2 and 3, the number of the arm portions 52, 52a of the connecting members 5, 5a may be three or more.

FIG. 4 shows a third embodiment of the present invention, in which a bolt body 2 connected by a stress concentration portion 3b is shown.
b and the fastening head 4b are connected using a linear body 6 made of a chain, a metal wire, or the like. After the linear body 6 reaches a predetermined torque and the stress concentration portion 3b breaks, only the tightening head 4b slightly turns idle, so that the resistance rapidly decreases, and it is immediately indicated that the tightening operation has been completed. The connection is made with a predetermined slack so that it can be confirmed and is not pulled and cut when idling.

After the stress concentration portion 3b breaks due to the action of a predetermined torque or more, the tightening head 4b is kept connected to the bolt body 2b by the linear body 6. The part 4b is prevented from falling off.

[0027]

According to the present invention, accurate torque management can be performed only by performing a normal tightening operation without dropping off a part of the component separated from the bolt body.

Therefore, the trouble of picking up the separated parts is unnecessary, and the parts fall down when working at a high place, causing danger, and in the case of precision equipment, the parts enter into the inside to cause a failure. It can be used safely without being lost.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a connector used in the embodiment of FIG.

FIG. 3 is a longitudinal sectional view showing a different embodiment of the present invention.

FIG. 4 is a front view showing still another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing an example of a conventional method of connecting electric wires.

FIG. 6 is a front view showing a conventional example of a torque control bolt.

[Explanation of symbols]

 2, 2a, 2b Bolt body 3, 3a, 3b Stress concentration portion 4, 4a, 4b Tightening head 5, 5a Connecting body 6 Linear body 21, 21a, 21b Head 22 Shaft 23, 41 Locking groove 50 , 50a Through hole 51 Bottom 51a Top 52, 52a Arm 53, 53a Locking part

Claims (3)

[Claims] A bolt body having a shaft portion and a head portion; and a head portion of the bolt body is connected to a head portion of the bolt body via a stress concentration portion that is broken when a predetermined load is applied, and a locking groove is formed on the outer periphery. A fastening head provided; and the tip of a plurality of arms extending vertically from an edge of a bottom provided with a through hole into which a shaft of the bolt body is loosely fitted. A connector having a locking portion that can be locked in the groove;
By inserting the shaft portion into the through hole and fitting the locking portion into the locking groove, when the tightening head is tightened, the stress concentration portion breaks beyond a predetermined torque. The torque control bolt is characterized in that the tightening head does not fall off from the bolt body after the tightening. 2. A bolt body having a shaft portion and a head, wherein a locking groove is provided on an outer periphery of the head; and a bolt is broken when a predetermined load is applied to the head of the bolt body. A fastening head connected via a stress concentration portion having a large-diameter portion on the tip side; and a vertical direction from an edge of a top provided with a through-hole into which the fastening head is loosely fitted. A coupling body having a plurality of arm portions extending toward the distal end formed with a locking portion capable of being locked in the locking groove; and allowing the fastening head to pass through the through hole and the locking groove. A configuration in which, when the fastening head is tightened, the fastening head does not fall out of the bolt body after the stress concentration portion breaks beyond a predetermined torque when the fastening head is tightened. A torque control bolt, characterized in that: 3. A tightening head is connected to the head of the bolt body having a shaft and a head via a stress concentration portion that is broken when a predetermined load is applied. A torque control bolt, wherein the head and the tightening head are connected by a linear body having a predetermined slack.