JPH0570002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a bolt loosening detection impact machine used to detect loosening of bolts in steel structures such as bridges.

[Prior art]

For example, steel structures such as bridges are assembled using a large number of bolts. Then, it is necessary to confirm the safety of the structure by inspecting the degree of loosening of the bolts when the steel structure is assembled or completed, or after a certain period of time has elapsed.

A general bolt loosening test method involves striking the bolt head or nut in the shearing direction with a hammer for hammer testing, and making a human judgment based on the vibrations and sounds generated. However, this method often relies on people's "feelings", and as a result, there are large individual differences, and not only can accurate judgments be made only by experienced people, but even highly skilled people cannot make judgments when the amount of slack is small. be.

On the other hand, when detecting the looseness of an object to be detected such as a rotor bar, wedge, or coil of a rotating electrical machine, a hammer section with a sensor hits the object to be detected, and the looseness is detected based on the electrical signal waveform obtained from this sensor. For example, Japanese Patent Application Laid-Open No. 60-29660
It is known from the publication No.

[Problem to be solved by the invention]

By the way, there is a problem when applying the above-described loosening detection method of striking an object to be detected with a hammer portion having a sensor to detecting loosening of a bolt.

That is, in this method for detecting the looseness of a detected object, the detected object is manually struck with a hammer having a sensor, and therefore the striking force changes each time. Therefore, when applied to detect loosening of a large number of bolts, it is difficult to determine whether the bolts are loose, and not only does the work require a lot of time and effort, but it also requires placing a relatively large number of bolts in a relatively small area. If there are any bolts, the distance between the bolts will inevitably become smaller, making it difficult to accurately strike the hammer in the direction of shearing the bolts, resulting in a problem that the accuracy of detecting bolt loosening will be reduced.

[Means to solve the problem]

The structure of the impact machine for detecting bolt loosening according to the present invention in order to solve the problems of the prior art as described above is such that the impact machine main body 2 has a bolt 30 attached to the head of the bolt 30 or the nut 6 in the axial direction of the bolt 30. A fixing part 3 that can be inserted and fitted and has an open part 7 that exposes the head 6' of the bolt 30 or one surface of the nut 6, and the hammer part 5 that is disposed opposite to the fixing part 3.
A drive section 4 for driving the hammer section 5 is provided, and a sensor 17 is provided on at least one of the hammer section 5 or the fixed section 3, and the drive section 4
Accordingly, the hammer part 5 pushes the head 6' or nut 6 of the bolt 30 from the opening part 7 into the bolt 30.
It is constructed so that it can be struck with a constant striking force in a direction perpendicular to the axis of the ball.

[Effect]

In the structure of such a striking machine for detecting bolt loosening, the drive unit can always strike the bolt head or nut with a constant force, and the electrical signal obtained from the sensor indicates the degree of bolt loosening. It appears as a curve corresponding to the accusative case.

This electrical signal is then converted into a digital signal and input to a signal processing device provided in the main body of the striking machine, where it is compared with a reference value and the result is displayed on a display device.

〔Example〕

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

FIG. 1 is a side view of the impact machine for detecting bolt loosening according to the present invention, and FIG. 2 is a front view thereof. It is constructed by attaching a fixing part 3, a driving part 4, and a hammer part 5 to 2.

More specifically, as shown in FIG. 3, the fixing part 3 has an open part 7 formed along the five sides of the nut 6 (or the head 6' of the bolt 30), and has an open part 7 formed in a part thereof. 6 in the axial direction of the bolt 30.

The drive section 4 provided on the side of the fixing section 3 includes an outer shell 8 and a receiving section 9 disposed inside the outer shell 8.
, a guide section 10 formed on an extension line of this receiving section 9 , and a solenoid coil 11 arranged on the outer periphery of this guide section 10 .
A movable iron core 13 is fitted inside so as to be slidable in the vertical direction by the action of a solenoid coil 11.

The upper part of the movable iron core 13 is the edge part 14 of the hammer part 5
It passes through a hole 15 provided in the hole 15, and a large diameter portion 16 is provided at the upper end thereof.

The hammer portion 5 is formed wide in order to obtain sufficient striking force, and a load detector (force sensor) made of a piezoelectric element, a strain gauge, etc. is attached as a sensor 17 to the lower surface of the hammer portion 5 . The sensor 17 is attached by forming a recess 18 on the lower surface of the hammer portion 5, housing the sensor 17 in the recess 18, and closing it with a lid 19, as shown in FIG.

This sensor 17 can also be used as a sensor, for example, by pressing an acceleration detector (acceleration sensor) 21 into a recess 20 provided in the fixing part 3 with a spring 31, as shown in FIG.

Reference numeral 22 denotes a return spring, which is disposed between the hammer part 5 and a frame 23 attached to guide the hammer part 5 with respect to the drive part 4, and when the drive part 4 is not operating. It acts to push the hammer part 5 upward.

And switch 2 installed at the base of handle 1
4 to energize the solenoid coil 11 and draw the movable iron core 13 into the drive section 4.

That is, the hammer portion 5 is connected to the return spring 22.
(downward) against the spring force of
is struck in a direction perpendicular to the axis of the bolt 30. Force or acceleration sensor 17 due to this impact
(or 21), and this signal is sent to a comparison section or calculation section 25 or the like provided in the handle 1 to detect an abnormality in the bolt.

This comparison section or calculation section 25 amplifies the signal 26 from the sensor 17 (or 21) in an amplification section 27, as shown in FIG. 6, for example, and compares it with a reference value L input in advance in a comparison section 28. , if the reference value L deviates from the allowable range, the sound generator 29 can issue an alarm. The signal 26 from this sensor 17 (or 21) is
For example, the pulse waveform, pulse width, etc. can be used to guide the arithmetic unit 25 to determine an abnormality.

Preferably, the movable iron core 13 is pulled downward by the drive part 4, its lower end contacts the receiving part 9, and the large diameter part 16 at its upper end releases the tension on the hammer part 5 (the edge of the hammer part 5 part 14 and movable iron core 1
The hammer 5 is configured to strike the flat part f of the nut 6 after the nut 6 is no longer constrained by the large diameter part 16 of the nut 6. That is, when the signal 26 is guided to the calculation unit 26 as a pulse wave diameter or pulse width, the hammer 5 is released from the engagement with the driving unit 4 and allowed to advance freely during the impact, so that the hammer unit 5 can be hit in a pure frame. A pulse waveform due to the force can be obtained and good judgment can be made.

〔Effect of the invention〕

As is clear from the above description, according to the structure of the impact machine for bolt loosening detection according to the present invention, the impact force with which the hammer part hits the nut or bolt head is always constant, and therefore the impact force from the sensor is constant. Since the signal obtained is proportional to the loosening of the bolts, it is possible to accurately detect loosening of bolts even when there are a large number of bolts and the intervals between them are narrow, and it is also extremely simple and easy to detect loosening of bolts. effective.

[Brief explanation of the drawing]

The figure shows an embodiment of the present invention.
The figure is a side view of the bolt loosening detection device according to the present invention, FIG. 2 is a plan view thereof, and FIG.
4 is a sectional view of the force sensor section provided on the hammer section, FIG. 5 is a sectional view of the force sensor section provided on the fixed section, and FIG. 6 is a block diagram of the control section. f...Flat part of nut, H...impact machine for detecting bolt loosening, 1...handle, 2...main body, 3...fixing part,
4...Drive part, 5...Hammer part, 6...Nut, 7...
Opening part, 8... Outer shell, 9... Receiving part, 10... Guide part,
11...Solenoid coil, 13...Movable iron core, 14
... Edge, 15... Hole, 16... Large diameter part, 17... Sensor, 18, 20... Recess, 19... Lid, 21... Acceleration detector, 22... Return spring, 23...
Frame body, 24...Switch, 25...Discriminator, 26...Signal, 27...Amplifier, 28...Comparison section, 29...Audio generator, 30...Volt, 31...Spring.

Claims (1)

[Claims] 1. On the main body of the striking machine, there is a fixing part that can be inserted into and fitted into the bolt head or nut in the axial direction of the bolt and has an open part that exposes one side of the bolt head or nut, and a fixing part that is opposite to this fixing part. a hammer portion disposed in a fixed position, and a driving portion that drives the hammer portion; a sensor is provided on at least one of the hammer portion or the fixed portion; and the driving portion causes the hammer portion to move the bolt from the open portion. A structure of a striking machine for detecting bolt loosening, characterized in that the head or nut can be struck with a constant striking force in a direction perpendicular to the axis of the bolt.