JPS62238101

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DESCRIPTION JPS62238101
[0001]
The present invention relates to an ultrasonic transducer that generates longitudinal vibration,
torsional vibration, and combined vibration of longitudinal vibration and torsional vibration, and
a drive control method thereof, and particularly to vibration cutting in a machine tool or the like.
The present invention relates to an ultrasonic transducer suitable for use in an ultrasonic motor
or the like and a drive control method thereof. In general, a Langevin-type vibrator is commonly
used as a high-power ultrasonic transducer, in which an annular electrostrictive element is
sandwiched between metal members and resonated integrally, and the type of the transducer is
an axis. There are a vertical vibrator that vibrates in a direction and a torsional vibrator that
torsionally vibrates about an axis. These transducers are uni-directional transducers that
generate vibrations in only one axial direction or in only one torsional direction. An example of
an ultrasonic motor constructed by such a single directional vibrator is disclosed in Japanese
Patent Application Laid-Open No. 55-125052. That is, a vibrating reed is provided at the output
end of the vertical vibrator, and the vibrating reed is pressed against the rotor by slightly
inclining with respect to the axial direction of the normal vibrator of the movable member such
as the rotor. . As a result, the tip end portion of the vibrating reed is elliptically vibrated as a
result, and the rotor is frictionally driven. In the case of such a unidirectional vibrator, there is a
disadvantage that the wear between the vibrating reed and the rotor contact portion is
significant, and furthermore, the generation of noise is also large. Next, a vibrator as shown in
FIG. 25 is known as one different from such a vibrating reed type. That is, the vibrator 3 is
formed by integrally fastening the vertical vibrator 1 and the torsion converter 2. A wide groove
4 is formed on one surface of the torsional transducer 2 and a beam-like projection 5 is formed
on the other surface at an angle with the groove 4. Further, a disc-shaped rotor 8 is rotatably
attached to the torsion conversion body 2 via a bolt 6 and a coil spring 7 in a pressed state. In
such a structure, when longitudinal vibration is generated by the vertical vibrator 1, the vibration
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is transmitted to the torsion converter 2, and the tip direction of the beam-like protrusion 5 of
the torsion converter 2 is in the arrow direction Elliptical vibration occurs, whereby the rotor 8
rotates in the direction of the arrow. Although such a longitudinal torsion conversion type solves
the defect of the above-mentioned vibrator piece type, the ellipticity of the elliptical vibration
which is the vibration mode of the output end is uniformly according to the shape of the torsion
converter 2 However, it is impossible to control the ellipticity that is optimal for friction drive
and to control the rotation direction thereof.
That is, all of them are driven only in a single direction of the rotor 8, and moreover, wear of the
contact surface is small, and can not be controlled into an elliptical shape necessary for
efficiently driving at the maximum torque. From the above two, a means for generating a
compound vibration by individually driving an axial vibration and a torsional vibration
respectively has been invented, and a patent application is filed by the present applicant under
Japanese Patent Application Laid-Open No. 61-28482. It is published as a bulletin. That is, a
vibrator in which a radial or longitudinal resonator having its resonance frequency set equal to
the torsional resonance frequency at the node of the torsional vibrator and perpendicular to the
axis and its driving element are integrally fastened. To control the form of the combined complex
vibration at the output end by changing the respective amplitudes or relative phases, or the
amplitudes and relative phases. Moreover, as what comprised the ultrasonic motor using such a
vibrator ¦ oscillator, Unexamined-Japanese-Patent No. 61. No. 30,972. Problems to be Solved by
the Invention In the vibrator disclosed in Japanese Patent Application Laid-Open No. 61-28482
by the present applicant, since the vibration in the twisting direction and the axial direction can
be separately driven, each amplitude is different. By controlling the phase and relative phase,
various complex vibrations can be obtained. However, the problem is that the components of the
radial or longitudinal resonator become large relative to the torsional vibrator, and this makes it
impossible to form the vibrator in a small size. Means for solving the problem The cross-sectional
shape of the metal member integrally fastened to the TIE strain element for torsional vibration
and the electrostrictive element for longitudinal vibration is changed to match the torsional
resonant frequency with the longitudinal resonant frequency Form as. In addition, the 9-function
electrostrictive element for torsional vibration P and longitudinal vibration are used in which the
drive of the electrostrictive element for torsional vibration and the electrostrictive element for
longitudinal vibration is performed with the amplitude or relative phase, or the amplitude and
relative phase are controlled. When the metal member integrally fastened to the electrostrictive
element has a normal circular shape, the resonance frequency in the axial direction is essentially
higher than the resonance frequency in the twist direction, but the cross-sectional shape of the
metal member The resonance frequencies of the two coincide with each other by changing. 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 any combination of linear vibration,
longitudinal vibration and torsional vibration, and any direction. Shall be Embodiment An
embodiment of the present invention will be described based on the drawings.
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First, the vibrator 10 shown in FIG. 1 comprises a longitudinal vibration electrostrictive element
11.12 and a torsional vibration electrostrictive element 13.14 formed in an annular shape. The
longitudinal vibration vibrator 11.12 has an annular shape with a hole 15 at the center as shown
in FIG. 3, and is polarized as shown by an arrow in its thickness direction, and electrodes 16 are
provided on both sides thereof. Therefore, by applying an electric field to these electrodes 16,
stretching vibration occurs in the thickness direction. On the other hand, the electrostrictive
element 13.14 for torsional vibration has a hole 17 at its center, and is manufactured as follows.
First, as shown in FIG. 4, a large number of polarization electrodes 18 are uniformly provided in
the circumferential direction from one surface to the other surface, and polarization is
sequentially performed in the circumferential direction between adjacent polarization electrodes
18 as shown by arrows. Next, the polarization electrode 18 is removed, and an electrode 20 is
formed on both sides as shown in FIG. Therefore, when an electric field is applied in the
thickness direction, slip vibration is generated in the circumferential direction. The
electrostrictive element 13.14 for torsional vibration may be a known element such as the means
described in Japanese Patent Application Laid-Open No. 60-257777, which has already been
filed by one person of the present invention. 6 shows electrode plates 22, 23, 24. 25 in which the
terminal portion 21 is made to project. Next, as shown in FIG. 1 (a), the electrostrictive element
for m vibration 11.12 and the electrostrictive element for torsional vibration 13. 14 are
sequentially stacked and integrally fastened to metal members 27. 28 located at both ends. That
is, a through hole 29 and a large diameter recess 30 are formed in the metal member 27, and a
female screw portion 31 is formed in the metal member 28 and fastened by a bolt 32. A parallel
notch 33 is formed on the tip side of the metal member 28, and the tip is an output end 34. Thus,
the electrode plate 22 between the longitudinal vibration electrostrictive element 11 and the
metal member 28, the electrode plate 24 between the longitudinal vibration electrostrictive
element 12, and the torsional vibration electrostrictive device 13 are commonly connected. The
common electrode plate 22.24. When an alternating voltage is applied to the common electrode
plate 22.24 and the electrode plate 23 between the longitudinal vibration electrostrictive
elements 11.12 and the frequency thereof is adjusted to the longitudinal resonance frequency,
the vibrator 10 moves in the axial direction. The output end face 34 resonates at the maximum
amplitude. Further, since the common electrode plate 22.24 and the metal member 27 are in
electrical conduction, an alternating voltage is applied between the common electrode plate
22.24 and the electrode plate 25 between the torsional vibration electrostrictive element 13.14.
When the voltage is applied to adjust the frequency to the torsional resonance frequency, the
vibrator 10 resonates at the maximum amplitude and resonates at the output end face 34 in the
torsional direction.
Therefore, although it is the feature of the present invention that the parallel notches 33 are
provided in the metal member 28, the important function of the parallel notches 33 will be
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described. First, the longitudinal resonance vibration state of the round bar without the parallel
notch portion 33 is a conventionally known vertical vibrator, and the torsional resonance
vibration state of the round bar similarly constitutes a normal torsional vibrator. The resonance
frequency at λ / 2 resonance (λ is one wavelength) in such a vibrator is, for example,
considerably lower at 13.2 kllz in the twisting direction when the longitudinal direction is 21.3
kllz, but this is While the vibration is a longitudinal wave, the torsional vibration is a transverse
wave, resulting in a large difference. In the past, it was difficult to make the resonance frequency
in the longitudinal direction and the twisting direction have the same difference with each other,
so it is easy to control the complex vibration such as ellipse, circle or tilt vibration with good
controllability. It could not occur. Therefore, if the resonance frequency in the axial direction and
the torsional direction can be made the same, the vibration at point A on the circumference of the
output end 34 in FIG. 2 is the axial vibration 35 and torsional vibration 36 in FIG. Since they are
orthogonal to each other, their combined vibration is straight line 37 if they are in the same
phase as shown in the figure, and if the relative vibration is inverted 180 ° and axial vibration is
dotted line 38, the combined vibration is dotted line 39 and its vibration direction Change 90 '.
Further, when the relative phase is 90 °, the synthetic vibration becomes a circular vibration 40,
and the direction of rotation is reversed by the relative 90 ° leading or lagging phase.
Furthermore, the orthogonal composition of sine wave oscillations is diverse as it is well known
in the prior art, for example, it becomes an elliptic oscillation by changing its relative amplitude,
or an inclined ellipse by a combination of relative amplitude and relative phase. Can be produced.
Therefore, when examining the second resonance mode (lλ resonance) of the torsional
resonance frequency at 21.3 kllz, the longitudinal resonance frequency at the above-mentioned
round bar is 24.5 kllz, and here, the aforementioned parallel The notch 33 reduces the end mass
at longitudinal resonance to increase its frequency, and at the time of torsional resonance, a
deflection component is introduced to act in a direction to lower the frequency, so that of the
parallel notch 33; The two resonances can be matched to each other by the resonance. 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 J at the point P where the two
curves coincide is Wo, and the frequency is indicated by fo. And when the vibration amplitude
distribution is shown when the respective resonance frequencies of the vibrator 10 shown in FIG.
1 (a) match, the state of torsional vibration is shown in FIG. 1 (b), and the state of longitudinal
vibration is 1 (C).
Therefore, it can be seen that the cross-sectional shape of the metal member 28 changes from
the node. By forming in this manner, the torsional vibration amplitude is expanded. Thus, in the
vibrator 10 in which the torsional resonance frequency and the longitudinal resonance frequency
are equalized by the parallel notches 33, the amplitudes and relative phases of the electrode
plate 23 and the electrode plate 25 with respect to the common electrode pair 22 and 24,
respectively. Connect to a drive power supply that can be controlled, and adjust its frequency to a
resonant frequency. First, assuming that the drive voltage to the electrode plate 25 is 0 and only
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the drive voltage to the electrode plate 23 is applied, the point A of the circumference L of the
output end 34 vibrates in the axial direction as shown in FIG. Do. Then, if the relative phase of
the drive voltage to the electrode plate 25 is 90 ° and the amplitude is increased, as shown in
FIG. And its vibration posture is changing. Further, assuming that the relative phase is 1 90 ', as
shown in FIGS. 9 (e) (f) (g), the direction of rotation is reversed so as to change its vibration
mode. Next, assuming that the drive voltage to the electrode plate 23 is O and only the drive
voltage to the electrode plate 25 is applied, the point A is torsionally vibrated in the direction
perpendicular to the axis as shown in FIG. 10 (d). When the amplitude of the drive voltage to: 3 is
increased, the ellipticity as shown in FIG. 10 (C) (b) (a) or (e) (f) (g) due to the amplitude and the
relative phase ± 90 '. The vibration form which changed the direction and the rotation direction
is obtained. Then, with the drive voltage to the mandrel plate 23 constant and the phase of the
drive voltage to the electrode plate 25 kept in phase, its amplitude increases from O, as shown in
FIGS. 11 (a) to 11 (e). As shown in, the vibration amplitude increases while changing the tilt angle
from the axial vibration. In addition, when the phase between the redrive voltages is reversed and
is increased from the amplitude O of the drive voltage to the electrode plate 25, as shown in
FIGS. 12 (a) to (e), the inclination from the axial vibration is The vibration amplitude increases
while changing the angle to the opposite of FIG. Also, if the torsional drive voltage to the
electrode plate 25 is constant and the amplitude of the axial drive voltage to the electrode plate
23 is increased from zero while keeping the phase of the axial drive voltage in phase constant, as
shown in FIG. As shown in e), the vibration amplitude increases while changing the tilt angle
from the torsional vibration. If the amplitude of the drive voltage to the company's electrode
plate 23 is increased from 0 by reversing the phase between the redrive voltages, as shown in
FIGS. The vibration amplitude increases while changing the tilt angle to the opposite.
Finally, when drive voltages with the same vibration amplitude in the axial direction and torsional
direction are applied to the electrode plates 23.25, and the relative phase of the redrive voltage is
0 °, the axis is as shown in FIG. 15 (e). On the other hand, 45 ° inclined linear vibration is
obtained, but by controlling its relative phase, it is obtained as inclined ellipse, circle, opposite
inclined ellipse and opposite inclined straight line (d) (c) (c) (b) (a) When the relative phase is
reversed, similarly, the reversed vibration in the rotational direction is obtained as (f 2) (g) (h) (i).
As described above, various complex vibration modes such as straight lines, inclined straight
lines, ellipses, inclined ellipses, and circles can be obtained by controlling the respective
amplitudes and relative phases of the axial drive voltage and the torsional drive voltage. In
addition, although what provided the parallel notch part 33 to the output end part 34 was
demonstrated, the various deformation ¦ transformation for obtaining the same effect is
demonstrated to FIG. 16 thru ¦ or FIG. First, as shown in FIG. 16, the output end 34 has the same
cross section as the cross section of the metal member 28, and the length of the parallel notch
33 does not reach the tip. Next, FIG. 17 shows the small diameter portion 41 as a parallel notch
33. In FIG. In the embodiment shown in FIG. 18, a round hole 42 penetrating in one direction at
right angles to the axial direction is formed, and the remaining part having the round hole 42 is a
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parallel notch 33. In the embodiment shown in FIG. 19, a cross-shaped cross hole 43 is formed at
right angles to the axial direction, and the rest of the cross hole 43 is a parallel notch 33. In the
example shown in FIG. 20, four slits 44 long in the axial direction are formed in the
circumference L, and the remaining portion where these slits 44 are formed is a parallel notch
33. 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 a parallel notch 33. In the configuration shown in FIG. 22, the
output end 34 is formed to be larger than the diameter of the vibrator 10, and a round hole 46 is
formed at the axial center in the same manner as shown in FIG. The remaining portion of is the
parallel notch 33. In the configuration shown in FIG. 23, the parallel notch 33 has a small
diameter and is formed as an equal diameter up to the output end 34. Furthermore, as shown by
the dotted line in FIG. good. According to such means, the expansion ratio of the vibration
amplitude in the twisting direction is large, and when used for an ultrasonic motor, it is suitable
for one having a relatively high rotational speed. In such a modification, although the shape of
the output end 34 is circular, it is advantageous to use the vibrator 10 capable of using all of the
circular surfaces, for example, for an ultrasonic motor.
That is, the contact surface with the rotor becomes large, the transmission torque per unit area is
small, the wear of the contact surface is reduced, and the durability and the reliability are
increased. Thus, in order to obtain an increase in the contact area and an increase in the
rotational torque, as shown in FIG. 22, it is advantageous to increase the area of the output end
34. Further, in the above embodiment, although the resonance in the longitudinal direction by λ
/ 2 and the torsion in the direction of 1λ has been described, the present invention is not limited
thereto. For example, the resonance in the longitudinal direction by 1λ and the resonance in 2λ
Is also able to operate well. Such an example is shown in FIG. That is, as shown in FIG. 24 (b),
resonance occurs at 2λ in the twisting direction, and as shown in (C), resonance occurs at 1λ in
the axial direction. As compared with the one shown in FIG. 2, the one shown in FIG. 24 has the R
step of the parallel notch 33 located near the nodes of the torsional vibration and the
longitudinal vibration, so There is a great advantage that the longitudinal vibration and the
vibration are both expanded at the output end 34 and the nodes of the vibration coincide so that
the vibrator 10 can be held at this node portion. It is what you are doing. In the embodiment
described above, the fastening structure is the bolt 32. However, in practice, the fastening may
be performed from the outer periphery using an outer periphery bolt or an outer periphery ring.
In addition, the number and position of the electrostrictive elements 11 to 14 can be freely
changed as needed. Therefore, in terms of the drive method, any of the well-known constant
voltage drive and constant current drive may be used. The constant voltage drive is applied to the
parallel resonance frequency, and the constant current drive is applied to the series resonance
frequency. Is desirable. Effect of the Invention The present invention changes the cross-sectional
shape of the metal member integrally fastened to the electrostrictive element for torsional
vibration and the electrostrictive element for longitudinal vibration as described above to change
the torsional resonance frequency and the longitudinal resonance frequency. Because they are
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formed to coincide with each other, it is possible to change the driving states in the axial
direction and the twisting direction to generate vibrations in various vibration modes.
[0002]
Brief description of the drawings
[0003]
1 is a cross-sectional view of a vibrator showing an embodiment of the present invention, FIG. 2
is a perspective view thereof, FIG. 3 is a perspective view of an electrostrictive element for
longitudinal vibration, and FIG. 4 is an electrostrictive element for torsional vibration 5 is a
perspective view of an electrostrictive element for torsional vibration, FIG. 6 is a perspective view
of an 'It electrode plate, and FIG. 7 is a combination of axial vibration and torsional vibration. FIG.
8 is a graph showing the relationship between axial vibration and torsional vibration
corresponding to the change in the parallel notch, and FIGS. 9 to 15 are graphs showing changes
in the vibration condition. Figs. 6 to 23 are side and sectional views showing a modification of
the parallel notch portion, Fig. 24 is a side view of a vibrator showing deformation of the
vibration mode, and Fig. 25 is an exploded view showing an example of the prior art. It is a
perspective view.
11.12 ... for longitudinal vibration electrostrictive elements, 13.14 ... torsional vibration
electrostrictive elements, 27.28 ... metal member, 34 ... Deno J end filing human Taga electric
stock Company, -m--One stomach Stomach Figure JLL-"工 l lΔpq 7 votes δ diagnosis ÷
7800700 θ \ Procedure correction book (KI) March 5, 1987 1 Display of the case Japanese
Patent Application No. 61-81922 2. The name of the invention The relationship between the
ultrasonic transducer and its drive control method 3 and the case for correction Patent applicant
4, representative 107 without "Alternate electric field in electrode 16" Japanese Patent
Application No. 61-81922 Amendment to this application, the description in the specification is
amended as follows. Note 1: The r-squared line on page 7, line 7 is corrected to "normal line". 2.
Correct the vibrator piece type on page 5, line 12, to vibrator piece type . 3. Correct
"circles etc." on page 8, line 3 to "cylinders etc." 4, Amplitude or relative phase on page 8,
line 8 is corrected as follows. [Amplitude or relative phase when driving each of the
electrostrictive elements] 5, the electric field to the electrode 16 on page 9, line 3 and line 4
is corrected as follows. 6. Correct the "electric field in the thickness direction" on page 9, line 14,
as follows. Alternate electric field in the direction of 1 is corrected to on both ends on
page 10, line 8 to on both sides .
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