JPH0672827B2 - Bolt looseness detection method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bolt looseness detection method and apparatus for fastening a steel structure such as a bridge.

[Conventional technology]

For example, steel structures such as bridges are fastened and assembled using a large number of bolts. At the time of assembling or completing this steel structure, or when a certain period of time has passed, it is necessary to inspect the looseness of bolts to confirm the safety of the structure.

In general, as a bolt looseness inspection method, a method of hitting the head or nut of the bolt with a hammer for hitting inspection and making a judgment by a person by the hitting at that time is used. However, this method often depends on the "intuition" of the person, and as a result, there are large individual differences, and not only a skilled person can make an accurate judgment, but also a small amount of looseness makes it impossible to make an accurate judgment. There was a problem that even a skilled person would make a different judgment.

As a result, the present inventor has made earnest studies on loosening detection of bolts, and as a result, strikes the hexagonal planes of bolts and nuts in the shearing direction, detects the force or acceleration due to this impact, or both, and detects this detection signal. Have previously proposed a method for detecting bolt looseness and a bolt looseness detector (for example, Japanese Patent Application Nos. 62-252551 and 1-24040).

[Problems to be Solved by the Invention]

By the way, bolts and nuts that fasten steel structures, usually because paint is applied to the surface for rust prevention and corrosion, when detecting force or acceleration due to impact as described above,
This detection signal shows a different value as compared with the case without coating. That is, when the hammer and the bolt / nut are hit, a part of this hitting energy is used to peel off the paint, and there is a problem that it is difficult to obtain an accurate detection signal, and when such paint peeling occurs, After looseness inspection, it is necessary to perform partial painting work.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, in which the material is brought into contact with the hexagonal planes of bolts and nuts, and the material is hit in the shearing direction of the bolts and nuts from above, A method for detecting the force or acceleration due to this impact and detecting the looseness of bolts and nuts by this detection signal, and a device for carrying out this method. A fixed part that engages with the head is provided, an open part is provided in a part of this fixed part, and a material that abuts the hexagonal plane of the bolt / nut is provided in this open part. A hammer having a force sensor is attached to the tip of the supported arm, and the hammer strikes in the shearing direction of the bolts and nuts from the material.

Further, preferably, an opening portion is provided in a direction (vertical direction) orthogonal to the both sides (horizontal direction) of the fixing portion engaging with both sides of the head of the bolt / nut, and the hexagonal plane of the bolt / nut is provided in the opening portion. Is provided so as to come into contact with the second contact member, and the acceleration sensor is attached to the second contact member.

[Action]

According to the bolt loosening detection method and device as described above, since the hard material is brought into contact with the hexagonal plane of the bolt / nut, and hit from above, paint is not applied to the surface of the bolt / nut. Even if it is applied, it is not peeled off, so that a good signal can be obtained and there is no need for correction application of paint.

〔Example〕

An embodiment of a bolt looseness detecting method and device according to the present invention will be described below with reference to FIGS. 1 to 15.

FIGS. 1 to 4 show a first embodiment of a bolt looseness detecting device, FIG. 1 is a side view thereof, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 2 is a view taken along the line III-III in FIG. 2, and FIG. 4 is a sectional view taken along the line IV-IV in FIG.

The bolt looseness detecting device is composed of a main body 1, an arm 2 pivotally supported at one end of the main body 1, and a fixing portion 3 that engages with the heads of bolts and nuts 19.

Specifically, a motor 6 with a reduction gear is attached to the main body 1 with a bolt 4 via an attachment member 5.
Thus, the cam 7 is rotated about the shaft 8. The cam 7 is capable of abutting against a pressing member 9 which will be described later, and depressing the arm 2 against the spring force of the spring 10.

A cylindrical body 11 is further attached to the main body 1, and a tension spring 10 is arranged between a lower end of a screw shaft 12 provided at the top of the cylindrical body 11 and a mounting piece 13 provided at a lower portion. . A wing nut 14 is screwed onto the screw shaft 12.
By turning 14, the spring force of spring 10, namely hammer 17
It is configured so that the impact force of can be adjusted.

A long hole 15 is formed at the lower end of the mounting piece 13, and a pin 16 provided on the arm 2 is fitted in the long hole 15. That is,
Immediately before the hammer 17 described later hits the hexagonal plane of the bolt / nut 19, the stopper 18 contacts the lower end of the tubular body 11, and the arm 2 is not directly pulled by the spring 10.
In a free state, the hammer 17 hits one hexagonal plane of the bolt / nut 19. This gives a good signal.

As shown in FIG. 2, the fixing portion 3 attached to the tip of the main body 1 is configured to be sandwiched by two V-shaped engaging portions on both sides of the hexagonal plane of the bolt / nut 19. And, the open portions 20, 21 are provided above and below the V-shaped engaging portions.
Is provided.

A second member 23 having an acceleration sensor 22 is arranged in the upper opening 20, and a first member 25 having a striking portion projection 24 as shown in FIGS. 2a and 2b is further provided in the lower opening 21. Are arranged respectively, and further, the first material 25 and the second material 23 are arranged.
Is configured so that a tension spring 27 penetrating a hole formed in the mounting portion 26 of the fixed portion 3 integrally presses the fixed portion 3 with the elastic force.

Specifically, the distance between the first contact member 25 and the second contact member 23 is arranged to be slightly smaller than the interval between the parallel portions of the hexagonal portions of the bolt / nut 19 that face each other. A tension spring 27 is provided in a tensioned state between the first abutment member 25 and the second abutment member 23 and presses the bolt / nut 19 so as to hold the two surfaces thereof.

In addition, 28 is a stopper attached to the rear side surface of the fixed portion 3 by a screw 29, and this stopper 28 is the fixed portion 3
When inserted into the hexagonal part of the bolt / nut, it functions to determine the position in the depth direction.

The first material 25 (Figs. 2a, 2b, 2c, 2d) is a hammer 17
It is necessary to withstand the impact force of the steel, and therefore, a hard material such as spring steel or tool steel is used.

As shown in FIG. 1, a grip portion 31 is attached below the main body 1 so that the fixing portion 3 can be accurately fitted into the bolts and nuts 19. A pressing member 9 that abuts on the cam 7 with a bolt 32 is attached to the arm 2 and a hammer 17 having a force sensor 33 is provided at the tip.

In the above configuration, when detecting the looseness of the bolt,
The hexagonal portion of the bolt / nut 19 is fitted into the fixing portion 3 having a hexagonal opening. At this time, the first strip 25 and the second strip 23 move slightly outward against the spring force of the tension spring 27, so that the first strip 25 and the second strip 23 are separated from each other. Both abut the flat surface of the hexagonal portion of the bolt / nut 19.

Then, a switch (not shown) is turned on to operate the motor 6 and rotate the cam 7 in the direction of arrow e shown in FIG. When the arm 2 is pushed downward against the spring force, that is, the arm 2 is pushed downward from the position indicated by the solid line, and when the position indicated by the chain double-dashed line is reached, the pressing member 9 disengages from the corner of the cam 7 and the spring force of the spring 10 causes the arm 2 to move. The hammer 17 which is momentarily pulled up and attached to the tip of the arm 2 strikes the protrusion 24 of the first contact member 25.

At this time, a force sensor 33 provided on the hammer 17 exerts a force caused by striking, and an acceleration sensor provided on the material 23 for acceleration.
A pulse signal is detected by 22, the pulse signal is amplified and A / D converted, and this is displayed as a waveform by a recording means such as an XY plotter or a printer.

Then, the change of the pulse waveform, specifically, the ratio of the rising angle (or slope) and the falling angle (or slope) of the pulse waveform is obtained and compared with a predetermined value to detect the looseness of the bolt.

Since the acceleration of the hammer 17 is proportional to the force detected by the force sensor 33, the force can be detected by attaching an acceleration sensor instead of the force sensor 33.

In addition, instead of the change of the pulse waveform, for example, a force sensor
It is also possible to detect the looseness of the bolt by calculating the ratio of the signal F obtained from 33 and the signal A obtained from the acceleration sensor 22.

5 to 15 show a second embodiment of the fixing portion 3 of the bolt / nut looseness detecting device.

This fixed part 3 is a flange attached to the tip of the main body 1.
A base 36 attached to the bolt 34 by a bolt 35, a second pad 37, and the like. More specifically, a flange 34 is attached to the tip of the main body 1 as shown in FIGS. 7 and 8. The base 36 has a notch 38 in the center as shown in FIGS. 9 to 11, and has bolt holes 39, 4
A vertical member 41 having 0, an upper horizontal member 42 protruding from the upper end of the vertical member 41, a lower horizontal member 43 protruding in parallel with the upper horizontal member 42, and a lower horizontal member 43 attached to the lower horizontal member 43. The eye plate 44 and the lower positioning seat 45 of the hexagonal portion of the bolt / nut 19 are also included.

The length l of the upper horizontal member 42 and the lower horizontal member 43 is determined so that the tips of the upper and lower horizontal members 42 come into contact with the side surfaces of the structural member when the heads of the bolts and nuts 19 are fitted.
The lower horizontal member 43 and the lower horizontal member 43 constitute a contact member for contacting the side surface of the structure. First base member 46 (FIGS. 16 and 17) bent downward toward the insertion side of bolts and nuts 19 is attached to the lower portion of base 36 with bolts 47, as shown in FIG. And the recess shown in FIG. 12 and FIG.
An upper positioning seat 49 having a bolt 48 for positioning the hexagonal portion of the bolt / nut 19 is attached by a bolt 50. The upper positioning seat 49 is integrally formed by the connecting member 51.

As shown in FIGS. 14 and 15, the second contact member 37 is provided with an eye plate 52 at the lower part, and an acceleration sensor 53 at the center is attached to the eye plate 52 of the second contact member 37. A tension spring 54 is arranged between the eye plate 44 provided on the base material 36.

In the bolt / nut detecting device having the fixing portion 3 configured as described above, the fixing portion 3 is moved axially in the hexagonal portion of the head of the bolt / nut 19 and fitted therein, After that, in the same manner as in the first embodiment, the hammer 17 strikes the hexagonal plane of the bolt / nut 19 in the shearing direction of the bolt / nut 19 from above the first contact member 46, and the impact force is applied. The force sensor 33 detects the acceleration as a pulse signal by the acceleration sensor 53, the pulse signal is amplified, further A / D converted, and displayed as a pulse waveform, which is obtained by the change or by the force sensor 33. Signal F
The looseness of the bolt is detected by calculating the ratio between the signal A and the signal A obtained from the acceleration sensor 53.

〔The invention's effect〕

As is apparent from the above description, according to the bolt loosening detection method and device of the present invention, the material is brought into contact with the hexagonal plane of the bolt / nut, and the shearing direction of the bolt / nut is applied from above the material. Even if paint is applied to the hexagonal part of the bolts and nuts because it is hit, a good signal can be obtained without peeling it off, and therefore accurate looseness of bolts and nuts can be determined. Not only is it possible to eliminate the need for repainting work after the inspection is completed.

In addition, bolts are often easy to move by hitting from below to above, so if the hexagonal flat surface of the bolt / nut is hit from below to above, better looseness detection There is an effect that it becomes possible.

[Brief description of drawings]

1 to 15 show an embodiment of a bolt loosening detecting method and device according to the present invention, and FIGS. 1 to 4 are explanatory views of a nut loosening detecting device of the first embodiment. so,
1 is a side view, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and 2a.
Figures and 2b show a side and front view of the first piece, Figure 2c and
FIG. 2d is a side view and a front view of another type of the first material, FIG. 3 is a view taken along the line III-III of FIG. 2, and FIG. 4 is a sectional view taken along the line IV-IV of FIG. 5 to 17 are explanatory views of a second embodiment of the looseness detecting device for bolts and nuts, and FIG. 5 is a front view of a fixing portion,
FIG. 6 is a side view thereof, FIG. 7 is a side view of the tip of the main body, and FIG. 8 is a front view of the same. 9 is a front view of the base body, FIG. 10 is a side view of the same, FIG. 11 is a plan view of the same, FIG. 12 is a front view of the upper positioning seat, FIG. 13 is the same perspective view, and FIG. 14 is movable. FIG. 15 is a front view of the material, and FIG. 15 is a front view thereof. FIG. 16 is a front view of the first material, and FIG. 17 is a side view of the same. 1 …… Main body, 2 …… Arm 3 …… Fixed part, 17 …… Hammer 19 …… Bolt / nut Hexagonal part 20,21 …… Open part, 22 …… Accelerometer 23 …… Second material, 24 ...... Protrusion 25 …… First material, 33 …… Force sensor 36 …… Base, 37 …… Second movable material 38 …… Notch, 41 …… Vertical material 42 …… Top horizontal material, 43… … Lower horizontal member 45 …… Lower positioning seat, 46 …… First material 48 …… Recess, 49 …… Upper positioning seat 51 …… Coupling material, 53 …… Accelerometer 54 …… Tension spring

Claims (2)

[Claims] 1. A hexagonal flat surface of a bolt / nut is brought into contact with this material, and the material is struck in the shearing direction of the bolt / nut from the corresponding material, the force and / or acceleration due to the impact is detected, and the bolt is detected by the detection signal. Looseness detection method for bolts to detect looseness. 2. A fixing portion for engaging a nut or a bolt head portion is provided at a tip of a main body, an opening portion is provided at a part of the fixing portion, and the opening portion is in contact with a hexagonal plane of a bolt / nut. A material is provided, and a hammer having a force or acceleration sensor is attached to the tip of an arm pivotally supported on the lower end of the other end of the main body, and the hammer strikes the material in the shearing direction of bolts and nuts. Looseness detection device for bolts.