JPH02152734A - Measuring device for axial tension of bolt fastening - Google Patents

Abstract

PURPOSE:To prevent the dispersion of measuring values by a constant pressing force by storing into a fastening socket the ultrasonic sensor incorporating a switch at the tip part, providing a spring therein and closely fitting the ultrasonic sensor to the fastening bolt head part always. CONSTITUTION:An ultrasonic sensor 2 incorporating a switch 2a at the tip part is assembled in a fastening socket 1 while supported by a snap ring 2b after a spring 9 is interposed between the sensor 1 and spring 9. Accordingly, when the fastening socket 1 is bonded to a fastening bolt head part, the ultrasonic sensor 2 presses the head part of the bolt at all times by the spring 9. Moreover, in the case of setting a motor nut runner 7, the switch 2a is turned ON, and an initial value is measured by transmitting ultrasonic wave from an ultrasonic axial tension meter 3. The motor nut runner 7 is then driven, the fastening bolt is tightened and the axial tension can be measured. The working efficiency is thus improved, and also the ultrasonic sensor 2 can press the bolt head part with a constant pressing force always to prevent the dispersion of the measuring values.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for measuring and managing the tightening axial force of a bolt.

(Prior art) Conventionally, the torque method, torque gradient method, rotation angle method, etc. have been used to manage the tightening axial force of tightening bolts, but in recent years, as well as measuring the axial force of tightening bolts, As a method to rationalize this variation, a method using an ultrasonic axial force meter was developed. This method calculates the axial force from the change in bolt length before and after tightening the tightening bolt, and as shown in Figure 3, an ultrasonic axial force meter (10) and an ultrasonic sensor (11) are used. To measure the axial force when the bolt is separated, (1) Initial value measurement: Press the ultrasonic sensor (11) against the head of the tightening bolt (12) and measure the initial length of the bolt before tightening. Measure the
Set the zero point on the ultrasonic axial force meter.

(ii) Tightening: Temporarily remove the ultrasonic sensor from the bolt head, insert the socket (13) into the bolt head, and tighten the bolt with a wrench (14) or invactor.

(1) Measuring axial force: Press the ultrasonic sensor (11) against the head of the tightening bolt again to measure the length of the bolt after tightening.

Through the above process, the tightening axial force generated in the tightening bolt is measured.

(Issue to be Solved by the Invention) In the conventional method, the only way to press the ultrasonic sensor against the head of the bolt is by hand, and the measured values vary due to variations in the pressing force.

Furthermore, the measurements are as described above (, (1) initial value measurement, (i
It is complicated to attach and detach the ultrasonic sensor during the three steps of i) tightening and (iii) axial force measurement, and constant visual control is required to keep the tightening axial force within a certain range. , it is unsuitable for assembly line work.The present invention aims to solve the above-mentioned problems.

(Means for solving the problem) In order to achieve the above objective, ■A bolt tightening axial force measuring device consisting of an electric nut runner with a tightening socket and an ultrasonic axial force meter has a built-in switch in the tip. The ultrasonic sensor is housed in the tightening socket, and a spring is installed between the tightening socket and the ultrasonic sensor, so that the ultrasonic sensor can be kept in close contact with the head of the tightening bolt at all times. Bolt tightening axial force measuring device.

■Claim ■The bolt is characterized in that a switch is provided between the power source and the electric nut runner to be opened and closed by an electric signal from an ultrasonic axial force meter, thereby making it possible to control the bolt tightening axial force within a certain range. This is a tightening axial force measuring device.

(Function) With the above configuration, when the bolt tightening socket is inserted into the tightening bolt head, the ultrasonic sensor and the tightening bolt head are brought into close contact with each other by the spring. Furthermore, when the electric nut runner is set in the tightening socket, the switch is turned ON and ultrasonic waves are emitted from the ultrasonic axial force meter, which drives the zero-order electric nut runner, which measures the initial value. Then, tightening starts, and the axial force generated in the tightening bolt is sequentially recorded on the ultrasonic axial force meter. Claim■
When the axial force reaches the preset value on the ultrasonic axial force meter, the electrical circuit to the electric nut runner is cut off by the current from the ultrasonic axial force meter, and the rotation of the electric nut runner is stopped. Ru.

(Example) An example based on the present invention will be explained with reference to FIG. The ultrasonic sensor (2) built into the tightening socket (1) is
The connection (4) is connected to the ultrasonic axial force meter (3), and the connection (4) is connected to the power supply.
8a) (8b), and an ultrasonic axial force meter (
The electric signal from the comparator (3d) of 3) is provided to the switch (6) through the connection (5). As shown in Figure 2 (a), the tightening socket (1) has an ultrasonic sensor (2) with a built-in switch (2a) at its tip.
A spring (9) is inserted between the tightening socket and the ultrasonic sensor, and a snap ring (
2b) is supported by the tightening socket (1). The upper part of the tightening socket (1) has an electric nut runner ('
7) is provided with a hexagonal groove in the lower part to fit the head of the tightening bolt.

Figure 2 (b) is a diagram of the connection state between the tightening socket (1), the tightening bolt and the electric nut runner (7), and the ultrasonic sensor (2) is moved upward due to the height of the tightening bolt head. Although it is pushed up, the head of the bolt is constantly pressed by the spring (9), so there is no variation in the contact force between the ultrasonic sensor and the tightening bolt.In addition, ultrasonic sensor (2)
If a magnet (2b) is attached to the tip of the magnet (2b), the connection between the two becomes more reliable. When the electric nut runner (Ma) is inserted into the tightening socket (1), the above-mentioned switch (2a) turns to “O”.
N” state, current flows through the connections (8a) and (8b) to the ultrasonic axial force meter (3), and ultrasonic waves are transmitted from the transmitter (3a) of the ultrasonic axial force needle (3). , ultrasonic sensor (
In step 2), the initial value of the tightening bolt is measured, and an ultrasonic axial force meter (
It is stored in the initial settings (3C) in 3).

Next, when the electric nut runner (7) is driven, the tightening socket (1) rotates and tightens the tightening bolt, and the ultrasonic axial force meter (3) measures the axial force. Claim■
As shown, a switch (6) is installed between the electric nut runner (7) and the power source, and the comparator (3) of the ultrasonic axial force meter (3) is connected.
The current from d) is configured to reach the switch (6) via the connection (5), and as shown in Figure 4, the predetermined bolt position is determined in advance from the relationship between the axial force indicated by the ultrasonic axial force meter and the true axial force. By setting the axial force F, and storing this in the standard setting (3) of the ultrasonic axial force meter (3),
During tightening, when the axial force of the bolt reaches Fl (Fl in the ultrasonic axial force meter), current flows from the comparator (3d) and turns the switch (6) OFF, so the electric nut runner ( 7) Stop.

(Effects of the Invention) Since the present invention has the configuration described above, the axial force measurement work, which previously required three steps, can be performed by setting the tightening socket in the electric nut runner and tightening the nut. Just by inserting it into the bolt, initial value measurement, tightening, and axial force measurement can be carried out continuously, improving work efficiency, and since the ultrasonic sensor always holds down the bolt head with a constant pressing force,
Variations in measured values can also be prevented. In addition, 1. If the standard setting value is set in advance, a constant axial force is always ensured, and visual control is not required, making it suitable for assembly line work.

[Brief explanation of the drawing]

FIG. 1 shows a bolt tightening axial force measuring device based on an embodiment of the present invention. FIG. 2(a) is a sectional view of a tightening socket based on an embodiment of the present invention. FIG. 2(b) is a diagram showing a state in which a bolt and an electric nut runner are set in a tightening socket based on an embodiment of the present invention. FIG. 3 is an explanatory diagram of a process for measuring the axial force of a tightening bolt based on a conventional technique. Figure 4 is a relationship diagram between the axial force of the tightening bolt in the ultrasonic axial force meter and the axial force in the axial force meter. 1... Tightening nut, 2... Ultrasonic sensor S...
Ultrasonic axial force meter, 6...Switch 7...Electric nut runner Fig. 1 (b) CC) Fig. 3*4

Claims (2)

[Claims] (1) In a bolt tightening axial force measuring device consisting of an electric nutrunner with a tightening socket and an ultrasonic axial force meter,
An ultrasonic sensor with a built-in switch at its tip is housed in the tightening socket, and a spring is installed between the tightening socket and the ultrasonic sensor so that the ultrasonic sensor can be kept in close contact with the head of the tightening bolt at all times. A bolt tightening axial force measuring device characterized by: (2) Claim (1) states that a switch is provided between the power source and the electric nut runner to be opened and closed by an electric signal from an ultrasonic axial force meter, thereby making it possible to control the bolt tightening axial force within a certain range. Features: Bolt tightening axial force measuring device.