JPH01182727A - Measurement of force using ultrasonic wave - Google Patents

Abstract

PURPOSE:To reduce errors based on temperature distribution and stress distribution, in a stress medium, by using transverse ultrasonic waves on two propagating paths having perpendicular vibrating directions so that propagating distances in the direction perpendicular to the direction of a stress load are equal. CONSTITUTION:Transverse ultrasonic wave vibrators 2 and 3, which are bonded to a stress medium 1, are vibrated in the mutually perpendicular directions, which are shown by vibrating directions 10 of the transverse ultrasonic wave vibrators. The transverse ultrasonic waves are propagated in the directions perpendicular to force F in the stress medium. The propagating speeds of the transverse ultrasonic waves, whose vibrating directions are mutually perpendicular in the stress medium, are measured with sing-around units 4 and 5 by a sing-around method. When the sing-around frequencies are counted by counters 6 and 7, the force, which is applied on the stress medium, can be simply computed by an operating device 8 based on a specified expression.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of measuring force using ultrasonic waves, which uses a method of measuring ultrasonic velocity that changes depending on the stress applied to a solid.

Conventionally, a method of measuring stress using ultrasonic waves (Japanese Patent Application Publication No. 1983-90228) has been known.

The ultrasonic force measurement method of the present invention uses transverse ultrasonic waves that propagate in a direction perpendicular to the stress loading direction and have two propagation paths with equal propagation distances and mutually perpendicular vibration directions. Compared with the method of 1, the vibration direction coincides with the stress loading direction.

The other type is characterized in that transverse ultrasonic waves in two propagation paths whose vibration directions are perpendicular to the stress loading direction intersect with each other. This reduces measurement errors based on the two systems of low stress distribution compared to conventional methods.

If the load cell is constructed using the 9 measurement method, it can be used with conventional strain gauge type, capacitance type, magnetostrictive type, hydraulic pressure type, etc.
This makes it possible to realize a load cell based on a principle different from that of a pneumatic type or a gyro type.

The method for measuring force using ultrasonic waves according to the present invention will be explained in more detail below with reference to one drawing.

Figure 1 shows an outline of a device for measuring force based on the present invention. 3 is a transverse wave ultrasonic transducer whose vibration direction coincides with the direction of the force, 4.5 is a sing-around unit connected to the transverse ultrasonic transducer 2.3, and 6°7 is a transverse wave ultrasonic transducer. In the method of the present invention for counting the sing-around oscillation frequency, based on a measuring device having such a configuration, a transverse ultrasonic transducer 2.3 bonded to a stress medium l is subjected to transverse ultrasonic waves as shown in FIG. Oscillator vibration direction l
Vibrate in mutually perpendicular directions indicated by O, and propagate transverse ultrasonic waves in the stress medium 1 in a direction perpendicular to the force F, and find the propagation speed of the transverse ultrasonic waves whose vibration directions are perpendicular to each other in the stress medium.

Measurement is carried out by the sing-around method in each sing-around unit 4.5.

Here, the sing-around frequency in the transverse ultrasonic transducer 2.3 when no force is applied to the stress medium 1 is +fl, respectively. , f2°, the mutually equal ultrasonic propagation distance in the stress medium 1 is d, the ultrasonic velocity in the stress medium is Vo, and the delay time due to the device is τ7. r2
given that.

■ holds true.

Also, the sing-around frequency when applying force is f, f,', and the ultrasonic velocity is V, respectively.
, V2.

holds true.

get.

On the other hand, according to the theory, (Vz V+ ) /
Since Vo is proportional to the stress applied to the stress medium, the above a
and b i.e. flo, fxo, fl, fl
By measuring the relative sound velocity difference based on: Here, if the sing-around frequency is counted by the counter 6.7 in FIG. 1, the force applied to the stress medium can be easily calculated by the arithmetic unit 8 based on the sing-around frequency.

Moreover, in this case, a method is used to determine the magnitude of the force applied to the stress medium based on the speed difference of the transverse ultrasonic waves of the two systems of propagation paths that intersect with each other, so the measurement accuracy depends on temperature changes in the stress medium. The amount of decrease can be reduced.

The method for measuring force using ultrasonic waves described above is uniform.As detailed above, the method for measuring force using ultrasonic waves of the present invention is as follows:
The vibration direction and propagation path of transverse ultrasonic waves in the two propagation paths relative to the stress loading direction.

Proper selection increases the spatial utilization efficiency of the stress medium and also provides temperature compensation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus for carrying out the method of the present invention. FIG. 2 is a perspective view showing the arrangement of the stress medium and the vibrator. 1. Stress medium 2. 3. FIQ wave ultrasonic transducer 4.5. Sing Around Unit 6.7. Counter 8, arithmetic unit Fig. 1 Fig. 2

Claims (1)

[Claims] 1. A compressive or tensile force is applied to a stress medium, and the vibration propagates in a direction perpendicular to the direction of the applied force, one in which the vibration direction coincides with the stress loading direction, and the other in which the vibration direction is perpendicular to the stress application direction. , a method of determining the magnitude of the force applied to the stress medium based on the speed difference of the transverse ultrasound waves of two propagation paths whose propagation distances in the stress medium are equal and intersect with each other. Measuring method