JP2002004798A - Fastening body and strain sensing system using fastening body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strain sensing system capable of preventing a fall of a nut or a rupture of a bolt. SOLUTION: A strain sensing system comprising a bolt, a nut, and a spacer installed between the nut and a body to be fastened and a transponder which uses a fastening body capable of sensing a strain which occurs in the axial direction of the bolt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastener capable of detecting a distortion generated in a bolt axial direction, and a strain detection system using the fastener.

[0002]

2. Description of the Related Art As is well known, bolts and nuts are used for fastening members in various structures. Also,
Concrete is sprayed onto the ground for the purpose of preventing the collapse of the tunnel, and bolts are driven in from the concrete surface toward the ground so as to prevent the concrete from peeling off from the ground.

[0003]

However, a bolt which fastens the above member or a bolt driven into concrete causes distortion which could not be predicted at first, causing the bolt to break, or a nut due to repeated vibration and thermal stress. The nut has come loose and the nut has come off.

Accordingly, the present inventor has made a technical problem to provide a strain detection system capable of preventing the breaking of bolts and the falling off of nuts beforehand, and as a result of repeated research and experiments in an attempt to realize the system. If there is something wrong with the bolt,
Focusing on the fact that signs of distortion appear in the nut and the spacer such as a washer mounted between the nut and the member or the member to be fastened such as concrete, light or sound, etc., if the amount of distortion exceeds a predetermined amount in the spacer. It has been found that the installation of a transponder that emits the above-mentioned problem enables early detection of an abnormality of a bolt, thereby achieving the above-mentioned technical problem.

[0005]

The technical problem can be solved by the present invention as described below.

That is, a fastening body according to the present invention comprises:
The nut includes a nut, a spacer mounted between the nut and the body to be fastened, and a transponder provided on the spacer. The transponder can detect distortion of the bolt in the axial direction.

Further, the distortion detection system according to the present invention comprises:
It comprises a combination of the fastening body according to the invention and a radio transceiver capable of transmitting and receiving between the fastening body and the transponder of the fastening body.

[0008]

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

FIG. 1 is a perspective view showing a distortion detection system according to the present embodiment, FIG. 2 is a block diagram of the transponder shown in FIG. 1, and FIG. 3 is a block diagram of a radio transceiver shown in FIG. In the drawing, reference numeral 1 denotes a fastening body driven into a shotcrete (an object to be fastened) 2, the fastening body 1 includes a bolt 3 and a nut 4 screwed into the bolt 3.
And a cylindrical spacer 6 fitted between the sprayed concrete 2 and the nut 4 and having flanges 5 and 5 on both sides.
And a transponder 7 fixed to the spacer 6.

The transponder 7 includes an antenna circuit 8 that receives an electromagnetic wave and converts it into electric energy, a detection circuit 9 connected to the antenna circuit 8, and a power supply circuit 10 connected to the detection circuit 9. A circuit section 11, a sensor circuit 12 to which a strain sensor for detecting a distortion generated in the axial direction of the bolt and outputting a detection signal if a predetermined value is exceeded is wired, and a differential amplifier circuit connected to the sensor circuit 12
13 and a sensor output circuit unit 15 including an arithmetic circuit 14 connected to the differential amplifier circuit 13 and a display transmission circuit unit including a display circuit 16 and a transmission circuit 17 in which display LEDs and a buzzer are wired.
Consists of eighteen. And the sensor output circuit unit 15
Is connected to the antenna power circuit 11 and the display transmission circuit 18
Is connected to the antenna power circuit unit 11 and the sensor output circuit unit 15.

A radio transmitter / receiver 19 transmits an electromagnetic wave to the transponder 7 and receives a signal transmitted from the transmission circuit 17 of the transponder 7 to display a distortion state of the volt 3. The unit 19 includes a constant-voltage power supply circuit 20, an arithmetic display circuit 21 connected to the constant-voltage power supply circuit 20 for lighting the display LDE a and sounding the buzzer b in accordance with predetermined conditions for the distortion state of the volt 3, and the transponder 7 It comprises an arithmetic display circuit 21 for receiving a signal transmitted from the transmission circuit 17, a reception circuit 22 connected to the constant voltage power supply circuit 20, and a transmission circuit 23 connected to the constant voltage power supply circuit 20 for transmitting electromagnetic waves. ing.

According to the fastening body 1 in the present embodiment,
Spacer 6 mounted between nut 4 for tightening bolt 3 driven into concrete 2 and concrete 2
If the concrete 2 is cracked, a strain is generated in the axial direction of the bolt 3 and the strain is detected by the strain sensor of the transponder 7, so that if the electromotive force is excited in the transponder 7, , Display circuit
The 16 display LEDs light or the buzzer sounds. Accordingly, the load state of the bolt 3 can be known from this.

Further, according to the distortion detection system of the present embodiment, if an electromagnetic wave is transmitted from the transmission circuit 23 of the radio wave transmitter / receiver 19 to excite the transponder 7 to generate an electromotive force,
The load condition of the bolt 3 can be known at any time from a remote place.

The spacer may be a washer commonly used with bolts and nuts. When the presence or absence of distortion is detected by turning on the display LED, the transmission circuit 17 of the display transmission circuit section 18 may be omitted.

[0015]

【Example】

FIG. 4 is a side view illustrating a bolt load test.
FIG. 5 is a graph for explaining the mechanical relationship between the bolt and the object to be fastened. In these figures, the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts. An object 2 made of hollow cylindrical cement having an outer diameter of 100 mm, an inner diameter of 26 mm, and a length of 150 mm is placed on the pedestal 25 of the pedestal 24, and a 250 mm long, M22 anchor bolt 3 is inserted from the pedestal 25 side.
Is sandwiched between the spacers 6 and tightened with the nut 4. The chuck portion 26 of the tensile tester is positioned from above to
Nut 4 through the tip of anchor bolt 3 to pedestal 27 of 26
Was fixed by screwing, and a bolt load test of the anchor bolt 3 by a tensile load was performed. 28 is the anchor bolt 3
A strain gauge is attached to the surface, and 29 is a gauge lead wire of the strain gauge 28.

The cement material used was Portland cement (JIS R 5210), and the hollow cylindrical cemented object 2 was manufactured according to JIS A 1132 and used after 7 days. The anchor bolt 3 and the nut 4 are bolts
Using cold drawn steel bars for nuts (JIS G 3151), JI
Compliant with SB 1180. The spacer 6 used was a flanged steel cylinder (JIS SC 10). Further, a strain gauge having a resistance of 1 KΩ (manufactured by Kyowa Dengyo Co., Ltd.) was used as a strain sensor of the transponder 7.

The object 2 to be fastened by the anchor bolt 3 and the nut 4
Is tightened, as shown in FIG.
Is elongated by λ _bolt , the object 2 is shrunk by λ _cement , and the balance is maintained by the load P. In this state, when a load ΔP is applied to the anchor bolt 3, the anchor bolt 3 becomes B
As the load increases to the point, it is displaced. The object 2 is displaced as the load decreases to the point C. Therefore, when the load P increases and the load on the anchor bolt 3 reaches the point D, the load on the object 2 becomes point E, that is, the tightening force becomes zero, and the anchor bolt 3 and the nut 4 are loosened.

A bolt load test was performed using the mechanical relationship between the bolt and the object to be fastened.

The initial fastening force of the anchor bolt 3 is distorted by ε.
_bolt ≒ 380 × 10 ^-6 At this time, the average strain caused by the object 2 and the transponder 7 is ε _cement ≒ −440 × 10
^-6 . The load of anchor bolt 3 is P _bolt ≒
It was 30KN. Anchor bolt 3 based on this state
And the value of strain ε _cement ≒ 360 × 10 ⁻⁶ was used as the threshold value of the strain sensor. At this time, the predicted load value for the anchor bolt 3 was P _bolt ≒ 59.3KN.

As shown in FIG. 4, the fastening member 1 is
Was attached to a tensile tester, and the tensile tester was operated to gradually extend the anchor bolt 3. Tensile load of tensile tester P ≒ 50.0KN and estimated value of strain of strain sensor ε ≒ 335
At × 10 ^-6 , the display LED of the transponder 7 lights up,
The buzzer rang.

At this time, the measured load value of the anchor bolt 3 is P _bolt ≒ 56.8 KN, and the predicted load value P _bolt ≒ 59.3 KN
It was close to KN. That is, it was confirmed that the device was operated reliably within an error of 10% or less and could be put to practical use.

[0023]

According to the present invention, it is possible to easily provide a strain detection system which can prevent breakage of bolts and nuts from falling off at the work sites and factories in shipbuilding and mechanical equipment as well as in civil engineering and construction. be able to.

Further, since the strain detecting system using the fastening body according to the present invention can be configured compactly and inexpensively, the manufacturing cost of instruments for detecting strain is reduced, and the measurement is performed because a transponder is employed. Labor costs can be reduced.

Therefore, it can be said that the present invention has very high industrial applicability because it can greatly contribute to ensuring safety in various industrial fields.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a distortion detection system according to an embodiment of the present invention.

FIG. 2 is a block diagram of the transponder shown in FIG.

FIG. 3 is a block diagram of the radio transceiver shown in FIG. 1;

FIG. 4 is a side view illustrating a bolt load test.

FIG. 5 is a graph illustrating a mechanical relationship between a bolt and an object to be fastened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fastened body 2 Shotcrete (concrete to be fastened) 3 Bolt 4 Nut 6 Spacer 7 Transponder 8 Antenna circuit 9 Detection circuit 10 Power supply circuit 11 Antenna power circuit section 12 Sensor circuit 13 Differential amplifier circuit 14 Operation circuit 15 Sensor output circuit section 16 Display circuit 17 Transmission circuit 18 Display transmission circuit section 19 Radio wave transmitter / receiver 20 Constant voltage power supply circuit 21 Operation display circuit 22 Receiving circuit 23 Transmission circuit 24 Specimen mount

Claims (2)

[Claims] 1. A bolt comprising a bolt, a nut, a spacer mounted between the nut and an object to be fastened, and a transponder provided on the spacer, for detecting a distortion of the bolt in the axial direction. Fasteners that can be. 2. A distortion detection system comprising a combination of the fastener according to claim 1 and a radio transceiver capable of transmitting and receiving between the fastener and a transponder of the fastener.