JPS6151511A - Ultrasonic wave converging device - Google Patents

Abstract

PURPOSE:To reduce the size of the device and also to reduce an offset quantity by making the aperture diameter of the side end part of an ultrasonic wave transmitting and receiving element by a specific value smaller than the diameter of its front surface. CONSTITUTION:A cone 29 is mounted on the front surface of the ultrasonic wave transmitting and receiving element 26 fixed by a holder 27 by using a cone holding plate 30, and an ultrasonic wave from the element 26 is reflected by the conic reflecting surface 29a of the cone 29, further reflected by the parabolic inner peripheral reflecting surface 28a of the horn 28, and converged on a focus O. In this case, the diameter (d) of the aperture of the horn 28 at the side of the element 26 is mde smaller than the diameter (e) of the element 26 to inhibit an ultrasonic wave from near the outer periphery of the element 26 from passing through the aperture part of the horn 28. Thus, the influence of a contour wave is eliminated.

Description

[Detailed description of the invention] Industrial applications This invention relates to an ultrasonic focusing device.

Conventional configuration and its problems Conventional ultrasonic focusing devices include a cone with a conical reflecting surface attached to the front of the ultrasonic transceiver element, and a parabolic curved cone placed coaxially with this cone. and a horn having an inner circumferential reflective surface forming a shape, and the aperture diameter at both ends of the horn is larger than the diameter of the ultrasonic wave transmitting/receiving element. The outline will be explained below. In FIG. 3, when a high voltage pulse is applied to the ultrasonic transceiver element 1 fixed to the holder 2, an ultrasonic pulse of a predetermined frequency is transmitted into the air. Ultrasonic pulses transmitted from the ultrasonic transceiver element 1 (
The arrow) reaches the cone 4 attached to the front surface of the ultrasonic wave transmitting/receiving element 1, is reflected by the conical reflecting surface, changes direction, and then reaches the inner circumferential reflecting surface of the horn 3. The inner reflective surface of the horn 3 forms a parabolic curved surface, and the reflected ultrasonic waves are converged at a focal point of 0. The cone holding plate 5 fixes the cone 4 in a predetermined position relative to the horn 3.

By attaching the ultrasonic focusing device having such a configuration to the front surface of the ultrasonic transceiver element 1, the signal strength of the ultrasonic waves reaching the focal point O is significantly increased compared to the case where no ultrasonic focusing device is attached. do. Furthermore, the signal intensity at a point away from the focal point 0, such as point A, is lower than when no ultrasonic focusing device is attached, so the directivity becomes more sensitive.

Note that the ultrasonic waves emitted or reflected from the focal point 0 follow the above-mentioned path in the reverse direction and reach the ultrasonic wave transmitting/receiving element 1. It is also configured to receive ultrasonic waves.

FIG. 4 is a diagram schematically showing a screw tightening head when the ultrasonic wave transmitting/receiving element equipped with the ultrasonic focusing device described above is used in a screw tightening robot to realize a hole position correction function.

An ultrasonic transmitting/receiving element 6 equipped with an ultrasonic focusing device composed of a horn 8, a cone 9, and a cone holding plate IO on the front side is fixed to a screw head 11 via a retainer 7. The screw tightening rod 11 is fixed to a manipulator 12, and is moved in the X direction and the Y direction by an external control signal. In FIG. 4, the ultrasonic wave transmitted from the ultrasonic wave transmitting/receiving element 6 is transmitted to the cone 9. It is reflected by the horn 8 and the object to be measured 1
3 and reaches the ultrasonic wave transmitting/receiving element 6 via the reverse route. In addition, the object to be measured 13 is
The distance to is set to match the distance from the front surface of the ultrasonic wave transmitting/receiving element 6 to the focal point, and the ultrasonic wave transmitting/receiving element 6 is moved by the manipulator 12 while maintaining the distance mL from the object to be measured 13. Move in the X and Y directions.

In FIG. 4, reference numeral 15 indicates the intersection of the focused ultrasonic beam transmitted from the ultrasonic wave transmitting/receiving element 6 and the object to be measured 13;
Reference numeral 6 indicates the intersection of the focused ultrasonic beam transmitted from the ultrasonic transceiver element 6 and the object to be measured 13 when the manipulator 12 is moved a predetermined distance in the X direction from this point. Fifth
A solid line 18 in the figure indicates the reflected signal intensity when the ultrasonic wave is transmitted and received by the ultrasonic wave transmitting/receiving element 6 while moving the manipulator 12 at a predetermined interval from the position of the intersection point 15 to the position of the intersection point 16 in FIG. And the manipulator 12 is on the horizontal axis.
This is an example of the results obtained by plotting the amount of movement in the X direction of , with the reflected signal strength on the vertical axis, and performing interpolation processing using a quadratic curve.

Note that in this conventional example, the ultrasonic transceiver element 6 and the object to be measured 13
The distance between is 75 nm, and the distance between intersection 15 and intersection 16 is 10B.
, the movement interval of the manipulator 12 is one crane. Further, the diameter of the hole 14 to be measured was set to 5111 mm. In FIG. 5, the reflected signal intensity is at its minimum at the position 6111, where the amount of movement of the manipulator 12 is 6111, and the reflected signal intensity at that time is 2600 mV. At this time, the intersection of the focused ultrasonic waves transmitted from the ultrasonic wave transmitting/receiving element 6 and the object to be measured 13 coincides with the center position of the hole to be measured 14 on the object to be measured 13 in the X direction.

Therefore, the X-direction offset amount (
The manipulator 12 is moved to the coordinates of adding δ (distance) between the intersection of the ultrasonic wave transmitted and focused from the ultrasonic wave transmitting/receiving element 6 and the object to be measured 13 and the intersection of the extension of the driver bit 17 and the object to be measured 13. This allows the driver bit 17 to be moved onto the central axis of the hole 14 to be measured in the X direction.

Similar (7)? By applying [ in the Y direction, the driver bit 17 can be moved onto the center axis of the hole to be measured 14 in the Y direction, and by performing the above two steps consecutively, the driver bit 17 can be moved to the center axis of the hole to be measured 14 can be moved on the central axis of If a screw is then supplied and the driver bit 17 is rotated and lowered, the screw can be reliably tightened into the screw hole, and high precision and efficiency of the screw tightening work can be realized. On the other hand, the broken line 1 in Figure 5
9 fixes the ultrasonic transmitting/receiving element 6R body (without the ultrasonic focusing device) to the screw head 11, and then attaching the ultrasonic transmitting/receiving device under the same conditions as when the ultrasonic focusing device is attached. 6 is the result of interpolation processing using a quadratic curve when transmitting and receiving ultrasonic waves. Note that at this time, since the ultrasonic waves transmitted from the ultrasonic transceiver element 6 are not focused, the offset amount is determined by the intersection between the center of the ultrasonic beam and the object to be measured 13, and the intersection between the extension of the driver bit 17 and the object to be measured 13. It is the distance from

Comparing the solid line 18 and the broken line 19 in FIG. It can be seen that the ice detection sensitivity is improved by this.This improvement in ice detection sensitivity is due to the fact that the ice detection sensitivity is too low to be detected by a single ultrasonic transceiver element without using a conventional ultrasonic focusing device. We hope that position detection will be possible, and fluorine has a great effect on ultrasonic focusing devices.

However, by installing the ultrasonic focusing device, the diameter of the ultrasonic wave transmitting/receiving element 6 increases compared to the case of using only the ultrasonic wave transmitting/receiving element 6, and the offset Iδ increases. This increase in the offset amount δ increases the time it takes for the driver bit 17 to move to the center position of the hole 14 to be measured, and an increase in the diameter leads to a narrowing of the operating range of the screw tightening robot.

Furthermore, the sound field formed by the ultrasonic waves transmitted from the ultrasonic transceiver element 6 is not uniform, and FIG. 3 is a diagram showing a model of a sound field in the vicinity of an element 20. FIG. Ultrasonic waves emitted from the ultrasonic transceiver element 20 can be classified into straight waves 21, which are emitted as plane waves only to the front of the sound source, and contour waves 22, which are emitted in a spherical shape from the periphery of the sound source. In FIG. 6, if the aperture of the ultrasonic wave transmitting/receiving element 20 is a, and the distance between the point C on the central axis of the ultrasonic wave transmitting/receiving element 20 and the ultrasonic wave transmitting/receiving element 20 is X, then the ultrasonic wave reaching the zero point The waveform is a composite waveform of the above-mentioned straight wave 21 and contour wave 22. FIG. 7 is a diagram showing this waveform, and 2
3, 24.25 have x/a values of 0.1.
0.5. The waveform when the value is 1.0 is shown. As shown in FIG. 7, it can be seen that the waveform of the ultrasonic wave transmitted from the ultrasonic wave transmitting/receiving element 20 is distorted due to the influence of the contour wave 22.

This waveform distortion poses a problem in that it lowers the accuracy of detecting the tapped hole position described above.

Purpose of the Invention This invention aims to reduce the diameter of an ultrasonic focusing device and reduce the offset amount δ.
An object of the present invention is to provide an ultrasonic focusing device that can improve hole position detection accuracy by reducing the effects of contour waves and eliminating the influence of contour waves.

Structure of the Invention The present invention provides an ultrasonic wave transmitting/receiving element, a cone disposed at the center of the front surface of the ultrasonic wave transmitting/receiving element and having a generally conical reflecting surface facing the front surface, and an ultrasonic wave transmitting/receiving element arranged coaxially with the cone. An inner peripheral reflecting surface having a generally parabolic curved surface faces the conical reflecting surface, and an opening diameter at an end on the side of the ultrasonic wave transmitting/receiving element is formed to be smaller by a predetermined amount than an aperture at the front surface of the ultrasonic wave transmitting/receiving element. It is characterized by having a pawn.

This makes it possible to reduce the diameter of the ultrasonic focusing device, reduce the amount of offset, and improve hole position detection accuracy by eliminating the influence of contour waves.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, 26 is an ultrasonic wave transmitting/receiving element;
7 is a retainer, 28 is a horn having an inner peripheral reflective surface 28a, 2
9 is a cone having a conical reflecting surface 29a, and 30 is a cone holding plate. Further, the aperture d of the opening of the horn 28 on the side of the ultrasonic wave transmitting/receiving element 26 is smaller than the aperture e of the ultrasonic wave transmitting/receiving element 26 . Among the ultrasonic waves transmitted from the ultrasonic wave transmitting/receiving element 26 fixed to the holder 27, the ultrasonic waves passing through the opening of the horn 28 are transmitted to the cone 29 attached to the front surface of the ultrasonic wave transmitting/receiving element 26. After reaching the horn 28 and changing its direction by being reflected by the opposing conical reflecting surface 29a, the horn 28
reach. The inner peripheral reflective surface 28a of the horn 28, which faces the reflective surface 29a, forms a parabolic curved surface, and the reflected ultrasonic waves are focused at a focal point O. On the other hand, the ultrasonic wave transmitting/receiving element 26
Ultrasonic waves transmitted from near the outer periphery of the horn 28 cannot pass through the opening of the horn 28, so they do not reach the focal point O.

In this example, the distance between the ultrasonic transmitting/receiving element 26 and the focal point O is %! uL is 75 mm, which is the same as in the case of the ultrasonic focusing device shown in the conventional example, and the diameter of the ultrasonic wave transmitting/receiving element 26 is 36+u.
, the diameter of the horn 28 is 50.8 inches at both ends, 2
6 questions.

A solid line 31 in FIG. 2 indicates that this ultrasonic focusing device is applied to the screw tightening robot (FIG. 2) shown in the conventional example, and the ultrasonic transmitting/receiving elements 26 are set at a predetermined interval under the same conditions as in the conventional example. This shows the reflected signal intensity when ultrasonic waves are transmitted and received while moving the ultrasonic wave element 26.The horizontal axis is the amount of movement of the ultrasonic wave transmitting/receiving element 26, and the vertical axis is the reflected signal intensity, which is plotted and interpolated with a quadratic curve. This is an example of the result of processing. In the solid line 31 in FIG. 2, the reflected signal intensity is at its minimum at the position where the amount of movement of the ultrasonic wave transmitting/receiving element 26 is six cranes, and the reflected signal intensity at that time is 1750 mV. The broken line 32 in FIG. 2 is the result of interpolation processing using a quadratic curve when ultrasonic waves are transmitted and received using the ultrasonic focusing device configured as shown in the conventional example (see FIG. 3) under the same conditions as this embodiment. be. Solid line 3 in Figure 2
1 and the broken line 32, the solid line 31, that is, the result when the ultrasonic focusing device shown in this example is attached, has smaller data variations, and the ultrasonic wave is emitted from near the outer periphery of the ultrasonic wave transmitting/receiving element 26 in a spherical shape. It can be seen that the influence of the contour wave 22 is removed, and the hole position detection accuracy is improved. In addition, the diameter of the ultrasonic focusing device shown in the conventional example is 80 m, and the offset +-it when applied to a screw tightening robot is 65 m, whereas the diameter of the ultrasonic focusing device shown in this example is 56 m. The fin offset amount is 52 m, making it possible to reduce the diameter of the ultrasonic focusing device and reduce the offset amount.

In addition, in FIG. 2, the reflected signal intensity of the solid line 31 is lower than that of the broken line 32, and the detection sensitivity of the ultrasonic focusing device shown in this embodiment may be lower than that of the ultrasonic focusing device shown in the conventional example. As can be seen, the decrease in detection sensitivity in this example is within a range that does not pose a practical problem.

Effects of the Invention According to the ultrasonic focusing device of the present invention, by making the aperture diameter of the horn on the side of the ultrasonic wave transmitting/receiving element smaller than the diameter of the ultrasonic wave transmitting/receiving element, it is possible to reduce the diameter of the ultrasonic focusing device and tighten screws. When applied to robots, it is possible to reduce the amount of offset and improve hole position detection accuracy by eliminating the influence of contour waves, which has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 12 is a relationship between the amount of movement of the ultrasonic transceiver element and the intensity of the reflected signal, and FIG. 3 is a sectional view of a conventional ultrasonic focusing device. Fig. 4 is a schematic diagram of the screw tightening head when applied to a screw tightening robot, and Fig. 5 shows the ultrasonic transmitting/receiving element at a constant position in the X direction during hole position detection using the device configured as shown in Fig. 4. Figure 6 is a diagram showing the relationship between the amount of movement of the ultrasonic transceiver element and the reflected signal strength when transmitting and receiving ultrasonic waves while moving the ultrasonic wave transceiver in parallel at intervals. FIG. 7 is a waveform diagram showing the waveform of the ultrasonic wave transmitted from the ultrasonic wave transmitting/receiving element and reaching the zero point in FIG. 6. 26... Ultrasonic wave transmitting/receiving element, 28... Horn, 29
...Cone, d...Aperture of the horn, e...Aperture of the ultrasonic transceiver element Fig. 1 Fig. 2 Fig. 3 Fig. 5 Fig. 6

Claims (1)

[Claims] an ultrasonic wave transmitting/receiving element, a cone placed at the center of the front surface of the ultrasonic wave transmitting/receiving element and having a generally conical reflecting surface facing the front surface thereof, and a cone placed coaxially with the cone to form a roughly parabolic curved surface. an ultrasonic horn having an inner circumferential reflecting surface facing the conical reflecting surface and an opening diameter at an end on the side of the ultrasonic wave transmitting/receiving element being smaller than a diameter of the front surface of the ultrasonic wave transmitting/receiving element by a predetermined amount; Sound wave focusing device.