JPS6344970A - Ultrasonic vibrator and drive control method thereof - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention Field of the Invention The present invention relates to an ultrasonic vibrator that generates longitudinal vibration, torsional vibration, and composite vibration of longitudinal vibration and torsional vibration, and a drive control method thereof. In particular, the present invention relates to an ultrasonic vibrator suitable for use in vibration cutting in machine tools, ultrasonic motors, etc., and a drive control method thereof.

Conventional technology In general, as a powerful ultrasonic vibrator, a Langevin type vibrator, in which an annular electrostrictive element is sandwiched between metal members and resonates as a unit, is often used. There are vertical oscillators that vibrate in different directions, and torsional oscillators that vibrate torsionally around an axis. These vibrators are unidirectional vibrators that generate unidirectional vibrations only in the axial direction or only in the torsional direction.

For example, an ultrasonic motor constructed using such a unidirectional vibrator is disclosed in Japanese Patent Application Laid-Open No. 55-1, 25052.
There is something described in the No. That is, a vibrating piece is provided at the output end of a vertical vibrator, and the normal line of a movable member such as a rotor is tilted slightly in the axial direction of the vibrator, so that the vibrating piece is pressed against the rotor. be. As a result, the tip of the vibrating piece vibrates elliptically, driving the rotor by friction.

When such a unidirectional vibrator is used, there are disadvantages in that the contact portion between the vibrating piece and the rotor is subject to significant wear, and furthermore, a large amount of noise is generated.

Next, a vibrator as shown in FIG. 25 is known as a vibrator different from such a vibrator piece type. That is,
The vibrator 3 is formed by integrally fastening the vertical vibrator and the torsional converter 2. A wide groove 4 is formed on one surface of the torsion converting body 2, and a beam-like protrusion 5 is formed on the other surface at a certain angle with the groove 4. Further, a disc-shaped rotor 8 is attached to the torsion converting body 2 via a bolt 6 and a coil spring 7 so as to be rotatable in a pressed state. In such a structure, when vertical vibration is generated by the vertical vibrator 1, the vibration is transmitted to the torsion converter 2, and the beam-like protrusion 5 of the torsion converter 2
An elliptical vibration occurs in the direction of the arrow at the tip of the
The rotor 8 rotates in the direction of the arrow.

Although such a vertical torsion conversion type solves the drawbacks of the vibrating piece type described above, the ellipticity of the elliptic vibration, which is the vibration mode of the output end, is uniformly determined by the shape of the torsion conversion body 2. Therefore, it is impossible to control the ellipticity to be optimal for frictional drive or to control the direction of rotation. That is, in both cases, the rotor 8 is driven only in a single direction, and furthermore, it is not possible to control the rotor 8 into an elliptical shape, which is necessary for efficient driving with little contact surface wear and maximum torque.

In view of the above, a means for generating complex vibrations by driving axial vibrations and torsional vibrations individually was invented, and a patent application was filed by the present applicant in Japanese Patent Laid-Open No. 61-28482. It is published as a public bulletin.

In other words, a vibrator in which a radial or longitudinal resonator located at a node part of the torsional vibrator, perpendicular to the axis and whose resonant frequency is set to be the same as the torsional resonant frequency, and its driving element are integrally fastened together. The configuration of the composite vibration at the output end is controlled by changing the amplitude or relative phase, or the amplitude and relative phase.

Furthermore, an ultrasonic motor configured using such a vibrator is disclosed in Japanese Patent Application Laid-Open No. 61-309 filed by the present applicant.
It is disclosed in Publication No. 72.

Problems to be Solved by the Invention In the vibrator disclosed in Japanese Unexamined Patent Publication No. 61-28482 by the present applicant, vibrations in the torsional direction and the axial direction can be driven separately, so the amplitudes of each It has the characteristic that a variety of complex vibrations can be obtained by controlling the vibration and relative phase. However, the problem is that the components of the radial or longitudinal resonator are larger than the torsional vibrator, which makes it impossible to form the vibrator in a compact size.

Means for Solving the Problem Among the metal members integrally fastened to both sides of the electrostrictive element for torsional vibration and the electrostrictive element for longitudinal vibration, the metal member on the side that does not have the protruding J end or The cross-sectional shapes of both metal members are changed so that the torsional resonance frequency and the longitudinal resonance frequency match.

Further, the electrostrictive element for torsional vibration and the electrostrictive element for longitudinal vibration are driven in a state where the amplitude or relative phase, or the amplitude and relative phase are controlled.

Action If the metal member integrally fastened to the electrostrictive element for torsional vibration and the electrostrictive element for longitudinal vibration has a shape such as a normal cylinder, the resonant frequency in the axial direction is higher than the resonant frequency in the torsional direction due to the nature of the wood. Although it is expensive, by varying the cross-sectional shape of the metal member, the resonance frequencies of both can be matched.

In addition, by appropriately controlling the amplitude or relative phase, or the amplitude and relative phase, the vibration state of the output end can be changed to linear vibration, circular vibration, or elliptical vibration, which is a combination of longitudinal vibration and torsional vibration, in any direction. shall belong to.

Example An embodiment of the present invention will be described based on the drawings.

First, the vibrator 10 shown in FIG. 1 includes a longitudinal vibration electrostrictive element 11 formed in an annular shape. ．． 12 and torsional vibration electrostrictive element 1
．． 3.14.

As shown in FIG. 3, the longitudinal vibration vibrators 1.1 and 1.2 have an annular shape with a hole 15 in the center, are polarized in the thickness direction as shown by the arrows, and have electrodes 16 on both sides. It is being Therefore, by applying an electric field to these electrodes 16, stretching vibration occurs in the thickness direction.

On the other hand, the torsional vibration electrostrictive elements 13 and 14 have a hole 17 in the center, and are manufactured as follows. First, as shown in FIG. 4, a large number of polarization electrodes 18 are provided evenly in the circumferential direction from one surface to the other.
Polarization is performed sequentially in the circumferential direction between adjacent polarization electrodes 18 as shown by the arrows, and then the polarization electrodes 18 are removed to form electrodes 20 on the entire both sides as shown in FIG. Therefore, when an electric field is applied in the thickness direction, sliding vibration is generated in the circumferential direction.

The electrostrictive elements 13, 1.4 for torsional vibration may be of a known type, such as the means described in Japanese Unexamined Patent Publication No. 60-257777 filed by the present applicant.

Moreover, what is shown in FIG. 6 is electrode plates 22, 23, 24, and 25 from which terminal portions 21 are projected.

Next, as shown in FIG. 1(a), the longitudinal vibration electrostrictive elements 11.12 and the torsional vibration electrostrictive elements 13. 1/l are sequentially overlapped and integrally fastened with metal members 27 and 28 located at both ends. That is, the metal member 27 has a through hole 29 and a large diameter recess 3.
0 is formed in the metal member 28, and a female threaded portion 31 is formed in the metal member 28, which is fastened with a bolt 32. A parallel notch 3 is provided on the distal end side of the metal member 28.
3 is formed, and the tip of the metal member 27 is the output end 3.
It is said to be 4.

Therefore, the electrode plate 22 between the electrostrictive element 1 for longitudinal vibration and the metal section 28 and the electrode plate 24 between the electrostrictive element 12 for longitudinal vibration and the electrostrictive element for torsional vibration 3 are commonly used. The common electrode plates 22 and 24 are connected to the common electrode plates 22 and 24.

This common electrode plate 22, 24 and the longitudinal vibration electrostrictive element 11
．． When an alternating current voltage is applied to the electrode plate 23 between the transducers 12 and the frequency is adjusted to the longitudinal resonance frequency, the vibrator 10 emits resonance vibration in the axial direction with the J end face 34 having the maximum amplitude.

Further, since the common electrode plate 22.24 and the metal part 27 are electrically connected, the electrode plate 25 between the common electrode plate 22.24 and the electrostrictive elements 1.3 and 1.4 for torsional vibration When an alternating current voltage is applied to and the frequency thereof is adjusted to the torsional resonance frequency, the output end face 34 of the vibrator 10 resonates in the torsional direction with maximum amplitude.

Therefore, a feature of the present invention is that a parallel notch 33 is provided in the metal part 28.
Explain important effects.

First, the longitudinal resonant vibration state of a round bar without parallel notches 33 constitutes a conventionally known vertical vibrator, and the torsional resonance vibration state of a round bar similarly constitutes a normal torsional vibrator. At the time of λ/2 resonance in such a resonator (
λ is one wavelength), for example, the resonance frequency in the vertical direction is 21.
, 3 kHz, the twist direction is 13.2kll
Mr. Li, such as Z, makes a big difference because longitudinal vibration is a longitudinal wave, while torsional vibration is a transverse wave.

Conventionally, it was difficult to make the resonant frequencies in the longitudinal and torsional directions the same due to the differences in wood quality, so it was possible to easily and easily control the complex vibrations such as elliptical, circular, or tilted vibrations. It could not occur.

Therefore, if the resonance frequencies in the axial direction and the torsional direction can be made the same, then point A on the circumference of the output end 34 in FIG.
Since the axial vibration 35 and the torsional vibration 36 in Fig. 7 are at right angles to each other, if they are in the same phase as shown in the figure, their combined vibration will be a straight line 37, and the relative phase will be 18.
If the axial vibration is reversed by 0° and the axial vibration becomes a dotted line 38, the resultant vibration becomes a dotted line 39, and the vibration direction is changed by 90°.

Further, when the relative phase is 90°, the resultant vibration becomes a circular vibration 40, and the direction of rotation thereof is reversed depending on the relative phase advance or lag of 90°. Furthermore, as is well known, orthogonal synthesis of sinusoidal vibrations produces a variety of complex vibration forms, such as elliptical vibration by changing the relative amplitude, or inclined ellipse by combining the relative amplitude and relative phase. can be produced.

Therefore, the longitudinal resonance frequency of the round bar shown earlier is 21.3
k) The second mode of the torsional resonance frequency when lz (1
λ resonance) is found to be 24.5kHz, and the aforementioned parallel notches 33 reduce the end mass during longitudinal resonance and raise the frequency, and the deflection component during torsional resonance. Since it acts in the direction of lowering the frequency, the thickness of the parallel notch 33 allows the respective resonance frequencies to be matched. The situation is shown in FIG. The horizontal axis represents the thickness W of the parallel notch 33,
The vertical axis represents each resonance frequency, and the thickness at the point P where both lines match is W. , the frequency is f. It is shown in

The vibration amplitude distribution when the resonance frequencies of the vibrator 1o shown in FIG. 1
Figure (C). Therefore, it can be seen that the cross-sectional shape of the metal portion iFA'28 changes from the node.

In the vibrator 10 in which the torsional resonance frequency and the longitudinal resonance frequency are made the same by the parallel notch 33 in this way,
Electrode plate 23 and electrode plate 2 with respect to common electrode plate 22, 24
5 is connected to a driving power source that can control the amplitude and relative phase, respectively, and the frequency is adjusted to the resonant frequency.

First, when the drive voltage to the electrode plate 25 is O and only the drive voltage to the electrode plate 23 is applied, a point A on the circumference of the output end 34 is applied.
vibrates in the axial direction as shown in FIG. 9(d). Therefore,
When the relative phase of the drive voltage to the electrode plate 25 is set to 90° and the amplitude is increased, the shape changes from FIG. 9(c) to FIG. The vibrational state changes.

Furthermore, if the relative phase is set to -90°, then Fig. 9(e)(f
) As shown in (g), the direction of rotation is reversed and the vibration state changes.

Next, when the driving voltage to the electrode plate 23 is set to O and only the driving voltage is applied to the electrode plate 25, the point A torsionally vibrates in the direction perpendicular to the axis as shown in FIG. 10(d), and the electrode plate 23 As you increase the amplitude of the drive voltage to
0', Figure 10 (C) (b) (a) or (
It is possible to obtain vibration states in which the ellipticity and rotation direction are changed as shown in e), (f), and (g).

Next, when the driving voltage to the electrode plate 23 is kept constant and the amplitude of the driving voltage to the electrode plate 25 is increased from ◯ while keeping the phase of the driving voltage to the electrode plate 25 in the same phase, it becomes as shown in FIGS. 11(a) to (e). As shown, the vibration amplitude increases from the axial vibration while changing the inclination angle. Furthermore, when the phase between the circumferential drive voltages is reversed and the amplitude of the drive voltage to the electrode plate 25 is increased from 0, the inclination changes from the axial vibration as shown in FIGS. 12(a) to (e). The vibration amplitude increases while changing the angle opposite to that in FIG.

Further, while the torsional drive voltage to the electrode plate 25 is kept constant and the phase of the axial drive voltage to the electrode plate 23 is kept in the same phase,
When the amplitude is increased from O, the vibration amplitude increases from the torsional vibration while changing the inclination angle, as shown in FIGS. 13(a) to (e). Additionally, the amplitude of the drive voltage to the electrode plate 23 is reduced to O by inverting the phase between the circumferential drive voltages.
14(a) to (e), the vibration amplitude increases while changing the inclination angle from the torsional vibration in the opposite direction.

Finally, if driving voltages are applied to the electrode plates 23 and 25 so that the vibration amplitudes are the same in the axial direction and the torsional direction, and the relative phase of the re-driving voltage is set to 0°, the axial In contrast, a 45° inclined linear vibration is obtained, and by controlling the relative phase, inclined ellipses, circles, oppositely inclined ellipses, and oppositely inclined straight lines (d), (c), (b), and (a) are obtained. Similarly, (f) (g) (h) (
Vibration with the direction of rotation reversed as shown in i) is obtained.

In this way, by controlling the respective amplitudes and relative phases of the axial portion '#jJ voltage and the torsional driving voltage, various complex vibration states such as a straight line, a tilted straight line, an ellipse, a tilted ellipse, and a circle can be obtained.

Although the explanation has been given on the case where the parallel notch 33 is provided up to the end, various modifications to obtain the same effect will be described in the first section.
6 to 22 will be explained.

First, in the one shown in FIG. 16, the tip has the same cross section as the metal member 28, and the length of the parallel notch 33 does not reach the tip.

Next, in the one shown in FIG. 17, the narrow diameter portion 41 is made into a parallel notch portion 33.

In the case shown in FIG. 18, a round hole 42 is formed that extends in one direction at right angles to the axial direction, and the remainder of the round hole 42 is a parallel notch 33.

In the one shown in FIG. 19, a cross-shaped hole 43 is formed at right angles to the axial direction, and the remainder of the cross-shaped hole 43 is a parallel notch 33.

In the case shown in FIG. 20, four axially long slits 44 are formed on the circumference, and the remaining part after forming these slits 44 is a parallel notch 33.

In the case shown in FIG. 21, a round hole 45 is formed at the center in the axial direction, and the remaining portion of the round hole 45 is made into a parallel notch 33.

The device shown in FIG. 22 has a tip portion formed with a diameter larger than the diameter of the vibrator 10, a round hole 46 formed in the axial center like the one shown in FIG. The portion shown in FIG. 3 is a parallel cutout portion 33.

In the one shown in FIG. 23, the parallel notch 33 has a small diameter and is formed with equal diameter up to the tip, and
A shaft center hole may be provided as shown by the dotted line in the figure.

Furthermore, in the above embodiments, a state in which resonance is caused at λ/2 in the longitudinal direction and 1λ in the torsional direction has been described, but the present invention is not limited thereto.
Even if it resonates at λ, it can similarly operate well. Such an example is shown in FIG. That is, as shown in FIG. 24(b), it resonates at 2λ in the torsional direction, and as shown in FIG. 24(c), it resonates at 1λ in the axial direction.

In the above embodiment, the bolt 32 is used to tighten the bolt 32, but in practice, an outer bolt or an outer ring may be used to tighten from the outer periphery.

Further, the number and position of the electrostrictive elements 1] to 4 can be freely changed as necessary.

As for the drive method, it is possible to use either constant voltage drive or constant current drive, which are well known in the past. Constant voltage drive is applied to the parallel resonant frequency, and constant current drive is applied to the series resonant frequency. It is desirable that

Further, in the embodiment described above, a state in which the cross-sectional shape of the metal member 28 which does not include the output end portion 34 is changed has been described.
4 may be modified so that the torsional resonance frequency and the longitudinal resonance frequency coincide with each other.

Effects of the Invention The present invention forms an output end in one of the metal members that are integrally fastened to both sides of the electrostrictive element for torsional vibration and the electrostrictive element for longitudinal vibration as described above, Since the cross-sectional shape of the other metal member or both metal members is changed so that the torsional resonance frequency and the longitudinal resonance frequency match,
It is possible to generate vibrations in various vibration states by changing the drive state in the axial direction and the torsional direction, and moreover, it can be formed into a small size as a vibrator.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a vibrator showing one embodiment of the present invention, and FIG.
The figure is a perspective view, and Figure 3 is a perspective view of an electrostrictive element for longitudinal vibration.
Fig. 4 is a perspective view of an electrostrictive element for torsional vibration in an intermediate state of manufacture, Fig. 5 is a perspective view of the electrostrictive element for torsional vibration, Fig. 6 is a perspective view of an electrode plate, and Fig. 7 is a perspective view of an electrostrictive element for torsional vibration. A graph showing the vibration state formed by combining torsional direction vibration, FIG. 8 is a graph showing the relationship between axial direction vibration and torsional direction vibration corresponding to changes in the parallel notch, and FIGS. 9 to 15. 16 to 23 are side views and sectional views showing modifications of the parallel notch, FIG. 24 is a side view of the vibrator showing changes in the vibration state, and FIG. 25 is a graph showing changes in the vibration state. FIG. 2 is an exploded perspective view showing an example of the conventional technology. 11.12... Electrostrictive element for longitudinal vibration, 1.3.14...
・Electrostrictive element for torsional vibration, 27.28...metal member,
34... Output end applicant Taga Electric Co., Ltd. -22~: GoC) ν Oshih COθ / θ O'Ss \ Procedural amendment (voluntary) Patent application filed March 5, 1988. -189844 No. 2, Title of the invention Ultrasonic transducer and its drive control method 3, Person making the amendment Relationship with the case Patent applicant 4, Agent No. 107 None The amendment is made as below. Written amendment to Japanese Patent Application No. 189844/1989 Regarding this application, the description in the specification is amended as follows. 1, correct the "normal line" in the first line of page 4 to "r normal". 2. Correct "cylindrical, etc." on page 7, line 16 to "cylindrical, etc." 3. Correct "Also, amplitude or relative phase" in the third line of page 8 as follows. "Also, amplitude or relative phase when driving each electrostrictive element" 4. "Electric field applied to electrode 16" on page 8, lines 16 and 17 is corrected as follows. “Apply an alternating electric field to the electrode 16” 5. “Apply an electric field in the thickness direction” on page 9, line 9. 6. “Apply an alternating electric field in the thickness direction” on page 9, line 9. " is corrected to "on both sides."

Claims (1)

[Claims] 1. A vibrator is formed by integrally fastening an electrostrictive element for torsional vibration, an electrostrictive element for longitudinal vibration, and metal members located on both sides of these on the same axis, and one An output end is formed on one end surface of the metal member, and the cross-sectional shape of the other metal member or both metal members is deformed so that the torsional resonance frequency and the longitudinal resonance frequency match. Ultrasonic transducer. 2. The ultrasonic transducer according to claim 1, wherein the torsional vibration resonates at 1λ and the longitudinal vibration resonates at 1/2λ. 3. The ultrasonic transducer according to claim 1, wherein the torsional vibration resonates at 2λ and the longitudinal vibration resonates at 1λ. 4. The electrostrictive element for torsional vibration, the electrostrictive element for longitudinal vibration, and the metal member are integrally fastened on the same axis, and the cross-sectional shape of the metal member is adjusted so that the torsional resonance frequency and the longitudinal resonance frequency match. and the electrostrictive element for torsional vibration and the electrostrictive element for longitudinal vibration are driven by a drive output in which the amplitude or relative phase, or the amplitude and relative phase are controlled. Vibrator drive control method. 5. A drive control method for an ultrasonic transducer according to claim 4, characterized in that the drive output is a drive voltage. 6. A drive control method for an ultrasonic transducer according to claim 4, characterized in that the drive output is a drive current.