JPH02245276A - Ultrasonic vibrator - Google Patents

Abstract

PURPOSE:To maintain the optimum resonated state by providing a mechanism for controlling the constrained state of a resonator close to a vibrator to control the resonance frequency of the vibrator. CONSTITUTION:A discoid supporting member 7 is fixed at the node of vibration, one side of a ring-shaped laminated piezoelectric element 9 is fixed to the number 7, and the other side is brought into contact with a flange 8 for controlling the resonance frequency provided to the resonator 2b. When a voltage is impressed on the element 9, a strain displacement is generated in the thickness direction of the ring. The load produced at the contact face between the element 9 and the flange 8 is changed by the magnitude of the generated strain. Contrarily, when a voltage is impressed to generate a contraction strain in the element 9, the constraining force of the flange 7 is weakened, and a mechanical resonance frequency is decreased. Consequently, the vibrator is driven at a specified resonance frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic vibrator used as an ultrasonic source in an ultrasonic application AII device such as an ultrasonic processing machine or an ultrasonic motor.

[Conventional technology]

Fig. 3 is a perspective view showing a conventional ultrasonic transducer shown in Chapter 3 (P, 61) of [Ultrasonic Engineering J (1975, Kogyo Kenkyukai), for example, and Fig. 4 is a sectional view of the same ( la), (
lb) is a disk-shaped piezoelectric element that serves as an excitation source for the ultrasonic vibrator.

(2a) and (2b) are resonators made of cylindrical metal blocks.

(3) is a piezoelectric element (la), (lb) and a resonator (2
a) Bolt connecting (2b), (4m),
(4b) is an electrode plate for supplying power to the piezoelectric elements (la) and (1k). Figure 5 shows a piezoelectric element (1m
), (lb).

This ultrasonic transducer is generally called a bolted Langevin transducer, and as shown in the cross-sectional diagram in Figure 4, it is made up of two cylindrical pieces sandwiching a piezoelectric element (1 m) and (Ib) that serve as the vibration source. The resonators (2a) and (2b) are firmly connected by bolts (311c).This ultrasonic vibrator is a vertical vibrator that generates vibrations in the axial direction of a cylinder, and has a disk shape that serves as an excitation source. The piezoelectric elements (la) and (Ib) are polarized in the thickness direction of the element as shown by the arrow (P) in FIG.
) When an appropriate AC voltage is applied in the thickness direction, vibrational distortion in the thickness direction as shown by arrows (A) and (A') in the same figure is generated. As shown in the cross-sectional diagram in Fig. 4, the resonators (2a) and (2b) made of cylindrical metal blocks are electrically connected by bolts (3), so two piezoelectric elements (1 m) , (lb) are arranged so that the polarization directions are opposite to each other so that the two generated distortions are in the same direction, and the electrode plates (4a) are sandwiched between the two pixel elements and overlapped, and are electrically driven in parallel. There is. The length of the transducer indicated by the symbol (L) in Figure 3 is designed to be 4 wavelengths of longitudinal vibration at a predetermined resonance frequency, so both end faces of the cylindrical ultrasonic transducer vibrate. The center becomes the node of vibration. A cylindrical ultrasonic vibrator can be supported using the vibration nodes in the center as shown in FIG. FIG. 6 is a sectional view showing an ultrasonic vibrator and a fixing part, in which (5) is a support flange provided at a vibration node, and (6) is a fixing member of the vibrator. By fixedly supporting the peripheral edge of the seven supporting flange (5) by the fixing member (6), it is supported by the cylindrical ultrasonic transducer.

[Problem to be solved by the invention]

Since the conventional ultrasonic transducer is configured as described above, the resonance frequency is fixed depending on the shape and dimensions of the transducer. Therefore, in order to drive an ultrasonic transducer at a predetermined resonant frequency, extremely precise shape and dimensions processing is required. There were issues such as not being able to maintain the condition.

The present invention was made to solve the above-mentioned problems, and an object thereof is to obtain an ultrasonic transducer whose mechanical resonance frequency can be electrically controlled.

[Means to solve the problem]

The ultrasonic vibrator of the present invention has a resonant system consisting of an excitation source and a resonator, and is supported near the nodes of vibration generated in the resonant system, and the restraint state of the resonator near the support is electrically controlled. A mechanism is provided to control the resonant frequency of the ultrasonic transducer.

[For production]

The ultrasonic transducer according to the present invention uses a mechanism that electrically controls the constraint state of the resonator provided near the support part of the transducer, so that the constraint state of the part changes. changes, and the mechanical resonance frequency of the vibrator changes.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a cross-sectional view of a cylindrical ultrasonic vibrator according to an embodiment of the present invention, in which (7) is a disk-shaped support member that supports the ultrasonic vibrator near the vibration nodes; ) is a resonant frequency control flange provided on the resonator (2b), (9
) is the support member (7) and the resonance frequency control flange (8)
This is a ring-shaped laminated piezoelectric element provided between the two.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

The cylindrical ultrasonic transducer of the embodiment shown in FIG. 1 is a longitudinal transducer that generates vibration in the axial direction of the cylinder, similar to the conventional example described above. Since the length of the vibrating body represented by the symbol (L) is set at the wavelength of longitudinal vibration at a predetermined resonance frequency, the central part of the vibrator becomes a node of vibration, but there are two disk-shaped support members. (7) is attached to the vibration node. One side of the ring-shaped laminated piezoelectric element (9) is fixed to the support member (7) of the ultrasonic transducer, and the other side is fixed to the resonator (2).
b) is in contact with the resonance frequency control flange (8) provided in FIG.

When a suitable voltage is applied to the laminated piezoelectric element (9), the first
As shown by the arrow (B) in the figure, since the ring is configured to generate strain displacement in the thickness direction, the laminated piezoelectric element (9) and the resonant frequency control flange (8) depend on the magnitude of the generated strain. ) will change the load generated on the contact surface.

As a result, the restraint state of the resonance frequency control flange (8) changes, and the mechanical resonance frequency of the ultrasonic transducer changes. That is, when a voltage is applied to the one-layer piezoelectric element (9) so as to cause an elongation strain, the resonant frequency control flange (8)
) increases, which increases the width of the vibration nodes in the center of the cylindrical transducer, and equivalently shortens the axial length of the ultrasonic transducer. This increases the mechanical resonance frequency. Conversely, if a voltage is applied to the VI layer piezoelectric element 9) to cause shrinkage strain, the restraining force of the resonant frequency control flange (7) becomes weaker, and the equivalent length of the ultrasonic transducer becomes smaller than the actual dimension (L ), the mechanical resonance frequency decreases.

The relationship between the equivalent length and the resonant frequency of the ultrasonic transducer mentioned above can be easily determined from the fact that the first natural vibration frequency of the M vibration of a rod with a uniform cross section with both end faces free is expressed by the following equation, as is well known. I can make an analogy.

However, in the above formula, 4 is the length of the rod, E is the longitudinal elastic modulus of the material of the rod, and ρ is the density of the material of the rod.

Now, in the above embodiment, the ultrasonic transducer is a cylindrical vertical transducer, but the present invention does not particularly limit the shape of the transducer to the shape of the above embodiment, and other than that shown in FIG. It may be as shown in the perspective view of the embodiment.

In Figure 2, the two heads are plate-shaped resonators whose one end is fixed to the fixing member (6), 01) is a piezoelectric element that becomes the excitation source of the plate-shaped resonance regime, and the piezoelectric element (+1) is a plate-shaped resonator. (The piezoelectric element 0υ is a thin plate element that is uniformly polarized in the thickness direction, as shown by the arrow (P) in the same figure.

When an appropriate AC voltage is applied in the thickness direction of the piezoelectric element 0υ, the plate-shaped resonator a [
Bending vibration occurs, and the open end of the plate-shaped resonator a vibrates as shown by the arrow (C) in FIG. A laminated piezoelectric element (9 m) is placed near the fixed part of the plate-shaped resonator Ql so as to sandwich the plate-shaped resonance structure from both sides.

(9b) is placed. The laminated piezoelectric element is configured to generate strain displacement in the direction shown by the arrow (B) in Fig. 2, and by changing the voltage applied to the laminated piezoelectric element (9m) and (9b), the above-mentioned effect can be achieved. As in the example case,
The restraint state near the fixed part of the plate-shaped resonator α1 changes and an ultrasonic wave is generated! ! The resonant frequency of the mover changes.

Furthermore, in the above embodiment, the case where a piezoelectric element is used as the excitation source of an ultrasonic vibrator has been described, but in this invention, the type of excitation source of the vibrator is not particularly limited, and an electrostrictive element is used. It may also be an electrical input/mechanical output element such as a magnetostrictive element or a magnetostrictive element.

Furthermore, in the above embodiment, an 81M piezoelectric element was used to control the restraint state near the support part of the ultrasonic transducer, but the mechanism for electrically controlling the restraint state is a mechanism using electromagnetic force. It may be.

[Effects of the Invention] As described above, according to the present invention, the mechanical resonance frequency of the ultrasonic transducer is configured to be electrically controllable.
The ultrasonic transducer can be driven at a predetermined resonance frequency regardless of load fluctuations or temperature changes, and there is also an advantage that strict machining of the shape and dimensions of the ultrasonic transducer is not required.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an ultrasonic transducer according to an embodiment of the present invention, and FIG. 2 is a perspective view showing another embodiment of the invention.
Figure 3 is a perspective view showing an example of a conventional ultrasonic transducer;
The figure shows the disconnection configuration of the conventional example shown in Fig. 3, Fig. 5 is an explanatory diagram showing the piezoelectric element that is the excitation source of the ultrasonic transducer, and Fig. 6 shows the conventional method of fixing and supporting the ultrasonic transducer. FIG. (1m), (lb), 01) is a piezoelectric element that is an electrical input mechanical output element that serves as an excitation source; (2a), (
2b) The resonator is a resonator, (6) is a fixing member, and (9) is a laminated piezoelectric element, which constitutes a mechanism that electrically controls the restraint state with the resonator. Note that in the two figures, the same reference numerals indicate the same or corresponding parts. Figure 1 Figure 1 Figure 1

Claims (1)

[Claims] It has a resonant system consisting of an electrical input mechanical output element serving as an excitation source and a resonator coupled to the electrical input mechanical output element, and a fixed member In the ultrasonic vibrator supported by the ultrasonic vibrator, a mechanism is provided to electrically control the constraint state of the resonator near the support portion of the vibrator, thereby controlling the resonant frequency of the ultrasonic vibrator. Ultrasonic transducer.