JP2002090237A - Socket for measuring axial force of bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy by shielding disturbances such as vibration in a socket capable of measuring the axial force of a bolt by an embedded ultrasonic probe. SOLUTION: An magnet 5 is incorporated in the main body of the socket 1 for fastening the bolt. A magnet 13 is also incorporated in a holding piece 12 for holding the ultrasonic probe 10 in such a way that the polarities of the magnet 13 are opposed to those of the magnet 5 so that the ultrasonic probe 10 is biased toward the tip by the repulsion between the magnets. As in close contact with the head 7 of the bolt 6, the ultrasonic probe 10 becomes in a noncontact state with the main body of the socket 1 at measurements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a socket for measuring the axial force of a bolt using an ultrasonic probe, and is suitable for measuring the axial force when tightening a bolt.

[0002]

2. Description of the Related Art As a method for measuring the axial force of a bolt, a method using an ultrasonic wave is known as a method capable of obtaining relatively accurate measurement. This method utilizes the property that the speed of sound changes according to the elongation caused by elastic deformation of the bolt due to tightening, and calculates the axial force from the measured value. An ultrasonic probe serving as a sensor is made of a vibrator and a resin, and the vibrator is placed in contact with a bolt head in a tightened state serving as an object to be measured. Then, an ultrasonic pulse is transmitted, and the data obtained by receiving the echo is sent to an axial force meter having an analysis / calculation function, and the propagation time of the ultrasonic wave is detected to calculate the axial force.

A socket for measuring the axial force of a bolt is a socket having an ultrasonic probe built into a socket used for bolt tightening. When a bolt tightening operation is performed by a handle fitted to the socket, the axial force is simultaneously progressed. Since measurement can be performed, the feature is that the set axial force can be obtained accurately and easily.

[0004] During the measurement, the ultrasonic probe incorporated in the socket needs to make reliable contact with the head of the bolt. For this purpose, it is necessary to urge the ultrasonic probe in the bolt direction. Conventionally, the simplest method using a spring force as illustrated in FIG. 7 has been adopted. That is, the compression spring 16 is interposed between the holding piece 12 incorporating the ultrasonic probe 10 and the main body of the socket 1, and the ultrasonic probe 10 is pushed forward by the repulsive force of the spring 16.

[0005]

In order to tighten the bolt, it is necessary to pivot the socket with a strong force. The biggest drawback of a socket that uses a spring is that swinging when tightening the bolt and intermittent sliding caused by friction between the socket body and the spring are directly transmitted to the contact surface as disturbance, and the ultrasonic probe and the bolt This makes the contact state unstable, resulting in poor measurement accuracy.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
Bring the ultrasonic probe into contact with the bolt from its axial direction,
By receiving the echo of the ultrasonic pulse transmitted from the ultrasonic probe, in the socket for measuring the axial force of the bolt to calculate the axial force of the bolt, the ultrasonic probe is fixed to a holding piece together with a magnet, The ultrasonic probe is biased toward the object to be measured by utilizing a repulsive force between the magnet and the magnet incorporated in the socket. A part of the outer peripheral surface of the holding piece of the ultrasonic probe is formed with a conical surface having a small diameter on the side of the object to be measured, and the inner periphery of the socket is engaged with the conical surface to form the ultra-cone. A conical surface for locking the urging of the sound wave probe is formed.

According to a third aspect of the present invention, an ultrasonic probe is incorporated at a tip of the holding piece, and a magnet is incorporated at a rear end of the holding piece.
The ultrasonic probe and the magnet are incorporated.

The present invention utilizes a repulsive force generated when two magnets face the same polarity in place of a compression spring so that disturbance such as vibration generated when the socket is turned is not transmitted to the ultrasonic probe. The ultrasonic probe and the socket body are not in contact with each other. The reason that the ultrasonic probe and the socket body abut on a conical surface is that when the ultrasonic probe is in a free state, the center of the ultrasonic probe fits in the center position of the socket and the head of the bolt enters. This is because the ultrasonic probe can move without contacting and being caught by the inner peripheral surface of the socket body if the conical surface is used.

A type in which a magnet is incorporated at the rear end of the holding piece can be used for general purposes because the diameter of the ultrasonic probe can be increased by an amount corresponding to the absence of the magnet at the front end.
The type in which a magnet and an ultrasonic probe are incorporated at the tip of the holding piece is attracted to the object to be measured by the magnetic force, in addition to the repulsive force of the two magnets, and the ultrasonic probe becomes more Since it is firmly fixed, it is effective not only in the vibration at the time of the socket turning operation but also in the work environment where the vibration from other machines is intense at the measurement site.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show an embodiment according to claim 3, wherein the main body of the socket 1 is constituted by a combination of three cylindrical parts, and integrally formed by screwing screws from four sides with countersunk screws 2. Assembled. A square hole 3 into which a square drive provided at the tip of a turning handle is inserted is formed in the upper end surface of the socket 1. In a direction orthogonal to the square hole 3, a lateral hole 4 is formed to prevent the socket 1 from coming off by a ball plunger built in the square drive that bites and presses.

Inside the socket 1, a magnet 5 having a through hole in the center is fixed. Further, a hexagonal hole 8 as shown in FIG. 3, for example, is formed at the tip of the socket 1 in accordance with the shape of the head 7 of the bolt 6 on the object side. On the inner peripheral surface of the main body of the socket 1 located between the magnet 5 and the hexagonal hole 8, a conical surface 9 having a smaller diameter near the hexagonal hole 8 is formed.

The ultrasonic probe 10 has a round disk shape in which a thin disk-shaped vibrator 11 serving as a sensor and a main body are integrated, and is embedded in the tip of a holding piece 12.
On the other hand, a magnet 13 having a through hole at the center is embedded in the rear end portion of the holding piece 12 with the polarity facing the magnet 5 fixed to the main body of the socket 1. Regarding the appearance of the holding piece 12, a conical surface 14 is provided on a part of the cylindrical outer peripheral surface, and the holding piece 12 is shaped to engage with the conical surface 9. From the ultrasonic probe 10, lead wires 15 are connected to magnets 13,5.
Through the center hole of the main body of the socket 1 and bends laterally to the outside, and is connected to an axial force meter having an analysis / calculation function.

FIG. 1 shows a state in which the ultrasonic probe 10 is not in use. The ultrasonic probe 10 is urged toward the distal end by the repulsive force of the magnets 5 and 13 and is locked by the conical surface 9. I have. Since the holding piece 12 abuts on the conical surfaces 9 and 14, the ultrasonic probe 10 fits with the main body of the socket 1 so as to coincide with the axis. Next, as shown by the virtual line,
When the hexagonal hole 8 is fitted into the head 7 of the bolt 6 with a force greater than the repulsive force of the magnet, the vibrator 11 of the ultrasonic probe 10 is pushed up while being in contact with the head 7 of the bolt 6, and Is in a non-contact state. If the handle is turned with the square drive of the handle inserted into the square hole 3, the axial force can be measured in real time without being affected by disturbance at the time of turning. If the turning operation is mechanized, it becomes possible to provide an automatic machine in which the bolt tightening torque is constant.

FIG. 4 shows a fourth embodiment of the present invention, in which a cylindrical magnet 13 is fixed to the tip of a holding piece 12 and an ultrasonic probe 10 is mounted inside the magnet 13. Has become. In addition to the repulsive force of the magnet 13, the magnet 13 makes a stronger contact with the head 7 of the bolt 6 made of a material to be attracted by the magnet. Measurement can be performed.

FIG. 5 and FIG. 6 show waveform data of a received wave by actual measurement. The vertical axis represents sound pressure, and the horizontal axis represents propagation time. FIG. 5 shows a conventional case using a spring.
While the received waveform for each pulse is not constant due to the influence of disturbance, the waveform when the magnet shown in FIG. 6 is used is always stable and has high sound pressure level.

[0016]

In the socket for measuring the axial force of a bolt according to the present invention, the ultrasonic probe is formed in non-contact with the socket body by utilizing the repulsive force of the magnet. A constant received waveform of the ultrasonic wave can be obtained without receiving the force, and thus, the tightening force of the bolt can be measured in real time with high accuracy. Further, since the ultrasonic probe is firmly fixed to the bolt exerted by the attraction of the magnet, stable measurement can be performed even in a poor measurement environment. If the steering wheel turning is mechanized, highly accurate bolting work can be automated.

[Brief description of the drawings]

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

FIG. 2 is a plan view of FIG.

FIG. 3 is a bottom view of FIG. 1;

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

FIG. 5 shows received waveform data when a conventional socket is used.

FIG. 6 shows received waveform data when the socket of the present invention is used.

FIG. 7 is a front sectional view showing an example of a conventional socket.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Socket 3 Square hole 5, 13 Magnet 8 Hexagon hole 10 Ultrasonic probe 12 Holding piece

Claims (4)

[Claims] 1. An axial force of a bolt, wherein an axial force of the bolt is calculated by bringing an ultrasonic probe into contact with the bolt from an axial direction thereof and receiving an echo of an ultrasonic pulse transmitted from the ultrasonic probe. In the measuring socket, the ultrasonic probe is fixed to a holding piece together with a magnet, and the ultrasonic probe is opposed to the magnet by using a repulsive force between the magnet and the magnet incorporated in the socket. A socket for measuring the axial force of a bolt, characterized in that the socket is urged against the bolt. 2. A part of an outer peripheral surface of a holding piece of the ultrasonic probe is formed with a conical surface having a small diameter on an object to be measured side.
The socket for axial force measurement according to claim 1, wherein a conical surface that engages with the conical surface and locks the urging of the ultrasonic probe is formed on an inner periphery of the socket. . 3. The bolt axial force measuring socket according to claim 1, wherein an ultrasonic probe is incorporated at a front end of the holding piece, and a magnet is incorporated at a rear end. 4. The socket for measuring the axial force of a bolt according to claim 1, wherein an ultrasonic probe and a magnet are incorporated at a tip of the holding piece.