JP2003227768A - Measuring device for bolt axial force - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-type measuring device for the axial force of a bolt which utilizes ultrasonic wave for judging tightening of bolts, used especially for such structure with less space above, below, or beside a nut. <P>SOLUTION: The measuring device comprises a head provided with a nut housing part in which a nut to be measured in housed, and a grip which an operator grips. It comprises a probe shifting means wherein the head is provided with at least a pair of probe housing parts communicating with the nut housing part, and a probe is so housed in the probe housing part as to be centrally retractable with a measurement surface opposed to the nut housing part side, thus interlocking all the probes together for appearing/disappearing from the nut housing part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt axial force measuring device using ultrasonic waves for determining the quality of bolt tightening, and more particularly to a structure in which there is not much space above or below a nut or laterally. The present invention relates to a thin measuring device capable of determining the quality of tightening of a bolt used in.

[0002]

2. Description of the Related Art Conventionally, a torque method or a rotation angle method is often used as a method for measuring the axial force of a bolt. However, an accurate axial force may not be introduced mainly because the torque coefficient is not accurately determined. Further, the method of measuring the axial force of the bolt from the torque value when the bolt starts to rotate using a torque wrench at the time of maintenance and inspection of the bolt is often not accurate for the above reason.

Therefore, the change in the propagation time of the ultrasonic wave in the axial direction of the bolt is obtained to obtain the axial force and extension of the bolt, or the axial force is obtained from the sound wave ratio of the longitudinal and transverse waves of the ultrasonic wave in the axial direction of the bolt. The method of non-destructively obtaining the axial force by the magnetoacoustic method has been realized. FIG. 8 is a conceptual diagram illustrating a method of using ultrasonic waves for measuring the axial force of a bolt. In FIG. 8, reference numeral 50 indicates a bolt, reference numeral 51 indicates a nut, and reference numeral 52 indicates an ultrasonic wave. The ultrasonic waves 52 are irradiated in the axial direction of the bolt 50, and the axial force of the bolt can be measured by the reflected intensity.

Further, in place of the irradiation of ultrasonic waves in the axial direction of the bolt, a method and apparatus for obtaining the axial force of the bolt from the magnitude of the ultrasonic transmission pulse of the nut facing surface have been proposed and put into practical use. (Patent No. 3116298, etc.).

FIG. 9 illustrates the principle of a method for obtaining the axial force of a bolt from the magnitude of the ultrasonic transmission pulse of the opposing surface of the nut. In this method, as shown in FIG. 9A, the transmitting side probe 53 and the receiving side probe are brought into close contact with the opposing surfaces of the nut 51 screwed to the bolt 50, and ultrasonic waves are transmitted. The axial force of the bolt can be measured by monitoring the transmitted pulse, which is the shortest distance in the order of the nut 51, the bolt 50, and the nut 51.

FIG. 9 (b) is a conceptual diagram when measuring the bolt axial force when the bolt is tightly tightened. When the axial force of the bolt 50 is sufficient, ultrasonic waves are transmitted and received on the opposite surfaces of the nut 51, and the nut 51, the bolt 50, and the nut 51 pass through the screw thread of the nut 52 and the bolt 51 in this order. Propagates and a waveform 55 showing the shortest distance transmitted pulse appears, as shown in the graph of FIG.

FIG. 9 (c) is a conceptual diagram when measuring the bolt axial force when the bolt is loose and tightened. When ultrasonic waves are transmitted / received on the opposite surfaces of the nut when the axial force of the bolt is reduced, the ultrasonic wave is propagated in the order of the shortest distance in the order of the nut 51, the bolt 50, and the nut 51. At 51, it propagates with reflection and diffraction. Therefore, as shown in the graph of FIG. 9C, a waveform 56 showing the shortest distance transmission pulse whose amplitude is smaller than that of the transmission pulse 55 when the bolt is firmly tightened appears.

FIG. 9 (d) is a conceptual diagram when measuring the bolt axial force when the bolt is completely loosened. When the ultrasonic force is transmitted / received on the opposite surfaces of the nut when the axial force of the bolt is 0, the ultrasonic wave is not propagated in the shortest distance in the order of the nut 51, the bolt 50, and the nut 51. The nut 51 only propagates with reflection and diffraction. Therefore, as shown in the graph of FIG. 9D, the waveforms 55 and 56 indicating the shortest distance transmission pulse do not appear.

In order to improve and develop the method of using ultrasonic waves for measuring the axial force of the bolt, the method is used for determining the quality of tightening of a bolt used for assembling a steel tower on which a transmission line is installed. There is a background.

Here, the bolts used for assembling the steel tower are usually fastened vertically, the tips of the bolts project in the vertical direction, and there are often no obstacles above and below the tips of the bolts. Also, in the method of obtaining the axial force of the bolt from the magnitude of the ultrasonic transmission pulse of the nut facing surface,
It is required that the probe, which comes into contact with the facing surface of the nut at the time of measurement, accurately faces on a line that is perpendicular to the axis of the bolt. Therefore, considering the work efficiency and the posture of the worker at the time of measurement, it is convenient to use the measuring device as shown in FIG. 10 as the measuring device used in the method (Japanese Patent No. 3116298, Japanese Patent No. 3116298). Open 2000-227372). The measuring device shown in FIG. 10A has one nut 5
1 measures the axial force of the bolt 50 screwed on,
The measuring device shown in FIG. 10B is configured to measure the axial force of the bolt 50 while avoiding a double nut in which a nut is further screwed on the upper side of the nut 51 or itering. In any of the measuring devices shown in FIGS. 10A and 10B, the probes 53 and 54 are provided in the cylindrical support bodies 58 and 59, and nuts are provided from above the tip of the bolt as shown by arrows 60 and 61. The bolt axial force is measured by contacting the probe with the surface facing the nut.

[0011]

However, in the conventional measuring device as shown in FIG. 10, the cylindrical support member 5 is used.
8 and 59, and the dimension in the axial direction of the bolt is large, it may be difficult to cover the measuring device with the nut. For example, there is a gas tank (gas holder) 62 (FIG. 7A) as a structure required to control the axial force of a bolt other than assembling a steel tower. Reference numeral 6 in FIG.
3 is a spare nozzle of the illustrated gas tank (gas holder) 62, reference numeral 64 is a manhole, and reference numeral 65 is an emergency shutoff valve. Further, FIG. 7B is an enlarged view of the part A in FIG. 7B. Gas tank (gas holder) 6
2 spare nozzle 63, manhole 64, emergency shutoff valve 65
If the axial force of the bolt is not controlled, the flange portion of the above may cause gas leakage and is dangerous.

However, the gas tank (gas holder) 6
The spacing W above or below the nut tightened in 2 is often narrow as shown in FIG.
In the conventional measuring device shown in (a) and (b), it is difficult to install for measurement, and in some cases even installation cannot be performed, which is a problem.

[0013]

According to the present invention, a probe is housed in a thin head portion having a housing portion for a nut to be measured, and a measuring surface of the probe is housed in the nut housing portion. The above-mentioned conventional problems have been solved by the measuring device in which the probe is projected and retracted so as to be in close contact with the side surface.

That is, the measuring device of the present invention is a measuring device comprising a head part having a nut accommodating part for accommodating a nut to be measured and a grip part grasped by a measurer, wherein the head part is the nut accommodating part. At least a pair of probe accommodating portions communicating with the probe accommodating portion are formed, and the probe accommodating portion is accommodated in the probe accommodating portion so that the measuring surface can be retracted in a centripetal manner toward the nut accommodating portion side. The bolt axial force measuring device is provided with a probe moving means for interlocking all of the children in and out of the nut accommodating portion.

If the head portion has a thickness enough to accommodate the probe, the axial force of the bolt can be measured even in a structure in which there is not much space above, below or laterally of the tightened nut. In addition, it is preferable to be as thin as possible.

It is sufficient that the nut housing portion is slightly larger than the diameter of the nut to be measured and has a size that allows loose fitting into the nut. Further, in the method of obtaining the axial force of the bolt from the magnitude of the ultrasonic transmission pulse of the nut facing surface, at least a pair of probes must be provided, so that the shape of the nut accommodating portion is at least two facing surfaces. Must be formed. Therefore, in the case of measuring a hexagonal nut, if it is shaped like a box wrench or a wrench head, it can be used as the shape of the head portion because two opposing surfaces are formed.

The grip portion may have any shape as long as it can be easily worked by the measurer depending on the measurement location, but there is not much space above, below, or to the side of the nut. In consideration of the work of the structure, it can be attached to the outer peripheral surface of the head portion so as to extend laterally of the head portion.

The probe accommodating portion communicates with the nut accommodating portion because the probe accommodating portion must accommodate the probe and can be retracted from the probe accommodating portion to the nut accommodating portion. Here, the probe accommodating portion may be a through hole that is narrow on the nut accommodating portion side of the head portion and wide on the outer peripheral side of the head portion.

It is to be noted that at least a pair of probe accommodating portions are formed, as described above, in the method of obtaining the axial force of the bolt from the magnitude of the ultrasonic transmission pulse of the nut facing surface, at least This is because the pair of probes must be provided.

The probe is accommodated in the probe accommodating portion so that the measuring surface can be retracted and retracted in a centripetal manner with the measuring surface facing the nut accommodating portion side. Therefore, when the measuring device is installed, the probe is detected. If the probe is housed in the probe housing, the probe does not come into contact with the nut, and it is easy to loosely fit the nut housing in the nut to be measured. Further, when measuring the axial force of the bolt, the probe needs to have its measurement surfaces in close contact with the bolt-opposing surfaces, but the probe can move from the probe accommodating portion toward the nut accommodating portion in a centripetal manner. Therefore, the measurement surface can be brought into close contact with the bolt facing surface, respectively. In addition, in the method of obtaining the axial force of the bolt from the magnitude of the ultrasonic transmission pulse of the nut facing surface, the probe that contacts the nut facing surface during measurement is accurately measured on a line that is exactly orthogonal to the bolt axis. However, since the probe is housed so as to be retractable in a centripetal manner toward the nut housing portion side, it can be accurately opposed on a line that is exactly orthogonal to the axis of the bolt.

The measuring surface of the probe may have a film made of a polymer compound. If a film made of a high molecular compound is formed, the adhesion to the side surface of the nut is high and it is not necessary to apply glycerin or the like as a contact medium at the time of measurement.

The probe moving means for projecting and retracting the probe into and out of the nut accommodating portion is tightened by connecting all the probes so that all the probes can be moved by operating the operation lever. A member and an operating lever are connected, and a tightening member that connects all the probes and a tightening member that is connected to the tightening member and moves the probe in the nut center direction. It can be configured to include an operation lever that can be operated. Here, the tightening member may be made of a flexible material such as a wire, but may be a band-shaped spring member having a high elasticity. Also, the operating lever is attached to the grip part,
It can be configured to be connected to the tightening member via the connecting member.

The ultrasonic wave data obtained by the measuring apparatus of the present invention is converted into an axial force using a conversion formula obtained by an experiment conducted in advance, and it is determined whether or not a predetermined axial force is secured.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The measuring apparatus 1 of the present invention shown in FIG.
A nut accommodating portion 3 is provided in the head portion 2 constituting the. Since the nut housing portion 3 is loosely fitted to the nut to be measured, if the nut diameter is similar,
It is possible to use a measuring device with a nut housing 3 of the same dimensions. In addition, it has a hexagonal shape that matches the shape of the nut that is often used, and the inner surface facing the nut is 3
Since they are formed in pairs, the probe accommodating portion 4 (FIG. 3) is provided on each surface.
Are provided, and each accommodates the probe 5 (FIG. 5).
As a result, the axial force can be measured at three locations (three channels), but the measurement can be performed at one location (one channel) and two locations (two channels) as required. In addition, reference numeral 6 in FIG. 1 denotes a connection cable, which is connected to an ultrasonic bolt axial force meter (not shown) to transmit and receive ultrasonic waves for measurement. Can be changed, and the ultrasonic wave amplitude and frequency can be changed by setting the ultrasonic bolt axial force meter.

The tightening member 7 constituting the probe moving means is attached to the back surface 5b of the probe 5 opposite to the measuring surface 5a as shown in FIGS. It is loosely fitted in the accommodation groove 17 of the tightening member provided along the outer periphery of the portion 2. With the tightening member 7 loosely fitted,
Since the tightening member 7 and the outer peripheral surface of the head portion 2 are separated from each other, the probe 5 attached to the tightening member 7 is attracted in a direction away from the outer peripheral surface of the head portion 2, and the probe accommodating portion 4 It will be completely contained in. On the other hand, when the operation lever 18 connected to the tightening member 7 is gripped and the tightening member 7 is tightened, the diameter of the tightening member 7 is reduced so as to be in close contact with the outer peripheral surface of the head portion 2. As a result, the probes 5 are pushed out from the probe accommodating portion 4 to the nut accommodating portion 3 side, so that the axial force of the bolt can be measured by bringing the measurement surface 5a into contact with and in close contact with the side surface of the nut 8 to be measured. This is possible (5, 7 shown by the chain line in FIG. 3).

[0026]

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

The bolt axial force measuring device 1 of the present invention comprises a head portion 2 having a nut housing portion 3 for housing a nut 8 to be measured and a grip portion 9 which can be grasped by a measurer (FIG. 1). 2 forms three pairs (six places) of probe accommodating portions 4 that communicate with the nut accommodating portion 3 (FIG. 3).
In each of the probe accommodating portions 4, the probe 5 is accommodated with the measurement surface 5a facing the nut accommodating portion 3 side, and all the six probe 5 are interlocked with the nut accommodating portion 3. A probe moving means to be projected and retracted is attached (Fig. 3).

The grip portion 9 is composed of a grip portion 19 which can be gripped by a measurer and a shaft 20 which connects the head portion 2 (FIG. 1).

The probe accommodating portion 4 has a through hole that is narrow on the nut accommodating portion 3 side of the head portion 2 and wide on the outer peripheral side, and the probe 5 has a tapered shape corresponding to the shape of the probe accommodating portion 4. In this shape, a film (silicon rubber) made of a polymer compound is formed on the measurement surface 5a.

The probe moving means is a tightening member 7 made of a belt-shaped spring member to which all the probes 5 are connected, and is connected to the tightening member 7 and is attached to the side of the grip 19 of the grip 9. And an operating lever 18 which is

Tightening member 7 to which the probe 5 is attached
Is loosely fitted in the accommodation groove 17 provided along the outer periphery of the head portion 2, and its attachment is performed in the following manner. First, as shown in FIG. 3, the tip 7a of the tightening member 7 is fixed to the fixing point 11 on the side of the head portion 2 near the grip 9 (FIG. 1). After that, the tightening member 7 is rotated once around the outer peripheral surface of the head portion 2 from the fixed point 11 and is hung on the deflection roller 12 mounted at a position beyond the fixed point 11 of the head portion 2 to tighten the tightening member 7 Is loosely fitted in a housing groove 17 provided along the outer periphery of the head portion 2. The other end 7b of the tightening member 7
Is connected to the operation lever 18 via the connecting member 13 at the tip of the deflecting roller 12. A spring 14 is attached to an end 13a of the connecting member 13 on the tightening member 7 side so as to urge the connecting member 13 toward the head 2 side. One end of the spring 14 is hooked on the head portion 2. As a result, the tightening member 7 made of a strip-shaped spring member is urged to expand its diameter, and the probe 5 is
Along with the elasticity of the spring member, it is urged radially outward.

The probe 5 is attached to the tightening member 7 as described above. The attachment will be described with reference to FIG. First, the strip-shaped spring member constituting the tightening means 7 is movably passed through without being fixed to the locking metal fitting 10. In this state, the locking metal fitting 10 is fitted into the groove 5c on the back surface 5b of the probe 5, the probe 5 is housed in the probe housing portion 4 (FIG. 3), and the tightening means 7 is operated as described above. The probe 5 can be attached to the fastening means 7 by loosely fitting it into the accommodation groove 17 provided along the outer periphery of the head portion 2.

The measuring device 1 has an overall length about the shoulder width of the worker in consideration of the workability of the measurer and the handling of the measurement in a narrow place.
By changing the length of the measuring device 1, it is possible to obtain the measuring device 1 having the full length dimension according to the conditions such as the working place.

Next, the measuring device 1 configured as described above.
How to use is explained. At the time of measurement, first connect the connection cable 6 of each probe 5 to an ultrasonic bolt axial force meter (not shown).
Connected to. Next, water is sprayed on the surface of the nut 8 to be measured, and the measurer 15 loosely fits the nut housing portion 3 (FIG. 1) of the measuring device 1 into the nut 8 as shown in FIG. At that time, each inner wall surface of the nut housing portion 3 (each probe 5
The measurement surface 5a) is loosely fitted so as to face each side surface of the nut 8. After that, when the operating lever 18 is gripped, the tightening member 7 is tightened so as to reduce its diameter along the outer peripheral surface of the head portion 2. As a result, the probes 5 are pushed out from the respective probe housing portions 4 toward the nut housing portion 3 side as shown by the arrow 21, and the measurement surface 5a comes into contact with the side surface of the nut 8 to be measured and further presses. If they are brought into close contact with each other, each probe 5
Contacts the opposite sides of the nut 8 with approximately the same pressure,
Axial force can be measured (Figs. 3 and 5).

In order to perform an accurate measurement, it is necessary that the measuring surface 5a, which is in close contact with the side surface of the nut 8 during the measurement, does not move, but as shown in FIG. The portion of the portion 2 has a narrow through hole on the side of the nut accommodating portion 3 and a wide through hole on the outer peripheral side, and the one probe 5 has a tapered shape corresponding to the shape of the probe accommodating portion 4, so that the nut accommodating portion 3 side The side surface 5d (FIG. 4) of the pushed-out probe 5 is in surface contact with the side wall of the probe housing portion 4, so that the probe 5 is stable,
Can be measured.

In FIG. 6, reference numeral 16 is a flange portion of the emergency shutoff valve of the gas tank (gas holder), but the head portion 2 can be easily attached to the nut 8 even when there is not much space below the nut. Can be fitted loosely.

After the data collection by the ultrasonic bolt axial force meter is completed, if the operator loosens the operation lever 18, the connecting member 1
The operation lever 18 is easily returned by the action of the spring 14 attached to the end portion 13a of No. 3. At this time, since the tightening means 7 is a spring member, it is easily loosened by its spring action, and accordingly, each probe 5 is housed in the probe housing portion 4 as shown by an arrow 22 (see FIG. 5).

[0038]

[Example of use] Next, an example of actual use of the measuring apparatus 1 of the present invention will be described.

1. Conversion Type Introduction Test First, a conversion type introduction test for converting the ultrasonic transmission amount (transmission pulse magnitude (dB)) obtained using the measuring apparatus 1 of the present invention into an axial force will be described.

This measuring apparatus 1 has an ultrasonic transmission amount of an ultrasonic bolt axial force meter output (transmission pulse size (d
B)) is measured. Therefore, this measuring device 1
In order to grasp the actual axial force by using, it is necessary to obtain in advance a conversion formula for converting the ultrasonic transmission amount measured by the measuring device 1 into the axial force for each bolt to be measured. is there.

[0041] 2-2 Test method After measuring the initial value of the bolt with an ultrasonic axial force meter,
Set the nut in the torque tester and use seven levels of axial force (0, 3, 6, 9, 12, 15, 18t) with the torque tester.
The amount of transmitted ultrasonic waves at the time of introducing is measured. Bolt is 11
Since there are books, the number of data is 77.

From the relationship between the introduced axial force and the measured ultrasonic wave transmission amount, linear regression analysis by the least squares method is performed to determine the conversion formula for obtaining the bolt axial force.

In one measurement, three channels from CH1 to CH3 were used, and the average value was calculated.

3. Test Results When the test data is shown, the measurement data as shown in FIG. 11 could be obtained. When a linear regression analysis by the least squares method was performed on this measurement data, a straight line in the graph as shown in FIG. 12 could be obtained. As a result, a conversion formula for converting the amount of transmitted ultrasonic waves into an axial force, Y = −0.58X + 27.6 (Y = calculated axial force, X = transmission pulse (dB)) was obtained.

4. Comparative Example A conversion formula for converting the amount of transmitted ultrasonic waves into an axial force needs to be obtained for each type of bolt to be measured. Therefore, for comparison, other bolts using the measuring device 1 are compared. An example of introducing a conversion formula for converting the amount of transmitted ultrasonic waves into an axial force will be shown.

The bolt to be measured in this comparative example is bolt hexagonal bolt M24 × 100 (hot dip galvanizing: strength category 6.8). The test date is the same as the test in the first half of July 2001.
It is the 12th of the month.

For the five bolts, eight steps of axial force, which is one step larger than that in the above test, were introduced by a torque tester, and 40 measurement data were collected. As a result of obtaining a conversion formula from this measurement data in the same manner as described above, a conversion formula for converting the ultrasonic transmission amount into the axial force, Y = −0.77X + 42.0 (Y = calculated axial force, X = transmission pulse ( dB)) could be obtained.

FIG. 13 is a summary of measured data, and FIG. 14 is a graph showing straight lines obtained by linear regression analysis by the least squares method with respect to the measured data.

5. On-site measurement The axial force of the bolt is calculated from the amount of ultrasonic transmission measured on the site by the measuring device 1 using the conversion formula previously obtained in the above procedure.

FIG. 15 shows the axial force measurement result of the bolt for tightening the flange of the emergency shutoff valve 65 of the gas tank (gas holder) 62 shown in FIG. 7A. As a result of the axial force measurement using the measuring device 1, of all 16 bolts, the number 44
The axial force of the bolt at (position: GM24 C-08) is 6.1.
The axial force of the bolts of tf, 50 (position: GM C-14) was 5.5 tf, which did not reach 6.5 tf set to the specified axial force (thick frame in FIG. 15). Therefore, the number 44
(Position: GM24 C-08) and 50 (Position: GMC-
The bolt of 14) was tightened to secure a sufficient axial force. As a result, the number 80 (position: GM C-
08), 81 (position: GM C-14),
Axial forces of 10.7 tf and 8.4 tf, which were equal to or greater than the specified axial forces, were able to be secured (thick frame in FIG. 15).

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to such embodiments, and within the technical scope understood from the description of the claims. It can be changed into various forms.

[0052]

According to the present invention, since the head portion having the nut housing portion for housing the nut to be measured and the grip portion which can be grasped by the measurer are provided, the probe is retracted in a centripetal manner. This has the effect of enabling a thin measuring device.This makes it possible to measure the axial force of a bolt used in a structure that does not have much space above, below, or to the side of the tightened nut. There is an effect that can be.

Further, since it is provided with a tightening member which connects all the probes accommodated in the probe accommodating portion of the head part, all the probes are made centripetal by gripping the operation lever. The nut can be raised and lowered to bring the measurement surface into contact with the nut. This has the effect of facilitating the operation for measuring the axial force.

[Brief description of drawings]

FIG. 1 is a plan view of a measuring device according to an embodiment of the present invention.

FIG. 2 is a left side view of the same.

FIG. 3 is an enlarged explanatory view of a head portion.

FIG. 4 is an explanatory view of attachment of a strip-shaped spring constituting a tightening unit to the back surface of the probe.

FIG. 5 is a partially enlarged cross-sectional view of the probe accommodating portion.

FIG. 6 is an explanatory view of a usage state of the embodiment of the present invention.

7A and 7B are explanatory diagrams of inspection points that can be measured by the measuring apparatus according to the embodiment of the present invention. FIG.
FIG.

FIG. 8 is a conceptual diagram of a conventional axial force measuring method using ultrasonic waves applied in the axial direction of a bolt.

FIG. 9 (a) is a conceptual diagram of a method for obtaining the axial force of a bolt from the magnitude of ultrasonic transmission pulses on the surface facing the nut. (B) A conceptual diagram showing a state of ultrasonic transmission when the axial force of a tightly tightened bolt is measured using the measuring method of FIG. 9 (a), and a graph showing a waveform of an ultrasonic transmission pulse at that time. (C) A conceptual diagram showing the state of ultrasonic transmission when measuring the axial force of a loosely tightened bolt, and a graph showing the waveform of an ultrasonic transmission pulse at that time. (D) A conceptual diagram showing a state of ultrasonic wave transmission when the axial force of a bolt having an axial force of 0 is measured and a graph showing a waveform of an ultrasonic wave transmission pulse at that time.

FIG. 10 (a) is an explanatory diagram of a conventional measuring device in which a probe is mounted on a tubular support. (B) Explanatory drawing of the other conventional measuring device which mounted the probe in the cylindrical support body.

FIG. 11 is a measurement data table showing the relationship between the introduced axial force and the ultrasonic transmission amount for obtaining the conversion formula required when using the measuring device of the present invention.

FIG. 12 is a graph for obtaining a conversion formula by using the linear regression analysis of the numerical values in the measurement data table shown in FIG. 11 by the least squares method.

FIG. 13 is a measurement data table showing the relationship between the introduction axial force and the ultrasonic transmission amount for other bolts.

FIG. 14 is a graph for obtaining a conversion formula using the numerical values in the measurement data table shown in FIG. 13 using linear regression analysis by the least square method.

FIG. 15 is a table showing the results of axial force measurement performed using the measuring device of the present invention.

[Explanation of symbols]

1 Measuring device 2 head 3 Nut housing 4 Probe housing 5 probe 5a Measuring surface 5b back 5c groove 6 connection cable 7 Tightening means 8 nuts 9 Grip part 14 spring 18 Operation lever

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuhiro Nimura             Aichi Prefecture Nagoya City Atsuta Ward Sakuradacho 19-18 East             Within Japan Gas Co., Ltd. (72) Inventor Hiroyuki Furuta             Aichi Prefecture Nagoya City Atsuta Ward Sakuradacho 19-18 East             Within Japan Gas Co., Ltd. (72) Inventor Nobuo Matsuyama             12-19 Higashioosone-cho, Higashi-ku, Nagoya-shi, Aichi             Himeno Co., Ltd. (72) Inventor Yasushi Ikegaya             2-4 Azamino Minami, Aoba-ku, Yokohama-shi, Kanagawa             No. 7 Just Co., Ltd. F-term (reference) 2F051 AA00 AB04

Claims (5)

[Claims] 1. A measuring device comprising a head section having a nut housing section for housing a nut to be measured, and a grip section which can be grasped by a measurer, wherein the head section comprises at least a pair of probes communicating with the nut housing section. A probe accommodating portion is formed, and the probe is accommodated in the probe accommodating portion such that the measuring surface can be retracted in a centripetal manner toward the nut accommodating portion side, and all of the probe is interlocked. A bolt axial force measuring device, comprising: a probe moving unit that moves in and out of a nut housing portion. 2. The probe accommodating portion is a through hole that is narrow on the nut accommodating portion side of the head portion and wide on the outer peripheral side, and the shape of the probe is tapered corresponding to the shape of the probe accommodating portion. The bolt axial force measuring device according to claim 1, wherein: 3. The bolt axial force measuring device according to claim 1, wherein a film made of a polymer compound is formed on the measuring surface of the probe. 4. The probe moving means is capable of moving the probe toward the center of the nut by tightening the tightening member connecting all the probes and connecting with the tightening member and tightening the tightening member. The bolt axial force measuring device according to claim 1, wherein the device includes a controllable lever. 5. The bolt axial force measuring device according to claim 4, wherein the tightening member is a belt-shaped spring member, the operating lever is attached to the grip portion, and is connected to the tightening member via a connecting member. .