JP6311099B2 - Ultrasonic composite vibrator - Google Patents

Description

  The present invention relates to an ultrasonic composite vibrator, and more particularly to an ultrasonic composite vibrator that generates at least two ultrasonic composite vibrations.

  In recent years, ultrasonic transducers are also used for applications such as drilling, welding and welding. In these applications, the composite vibration mode in which two or more vibrations are combined is superior to the single vibration mode in which the vibration trajectory is linear, so that the finish of the object to be processed is superior, and therefore, it is known to be more preferable. Accordingly, various ultrasonic composite vibrators that generate composite vibration have been developed.

  As an example of the ultrasonic composite vibrator, for example, Patent Document 1 is cited. In Patent Document 1, a piezoelectric element having a longitudinal vibration mode is arranged at the position of a longitudinal vibration node and driven at a single frequency, and an oblique slit for converting the longitudinal vibration into a torsional vibration is provided at the position of the torsional vibration node. An ultrasonic composite vibrator to be arranged in the above is disclosed.

  Further, for example, Patent Document 2 discloses an ultrasonic composite vibrator in which two types of piezoelectric elements, ie, a piezoelectric element having a longitudinal vibration mode and a piezoelectric element having a torsional vibration mode are stacked and arranged at a vibration node.

JP 2005-288351 A JP 2001-179179 A

  However, the apparatus described in Patent Document 1 has a problem that vibration is weak because longitudinal vibration is converted into torsional vibration by an oblique slit. In addition, the wavelengths of the vibrations for obtaining the longitudinal vibration and the torsional vibration are not the same, and the positions of the nodes of the vibrations are different. The vibration source itself should originally be fixed at the position of the node, but the position of the node is different for each vibration, so it is difficult to fix the vibration source. Furthermore, since the piezoelectric element is driven at a single frequency and converted into torsional vibration using an oblique slit, there has been a problem that longitudinal vibration and torsional vibration cannot be separately controlled separately.

  In Patent Document 2, the position of each vibration node is the same, but even if two types of piezoelectric elements are stacked and arranged on the vibration node, the position of the node is one, and there are two types centered there. The piezoelectric elements had to be shifted and arranged. That is, since each piezoelectric element cannot be accurately placed at the position of each vibration node, the vibration efficiency is poor. In particular, when attempting to increase the vibration power of a vibration source using a piezoelectric element group in which a plurality of piezoelectric elements having the same vibration mode are stacked, the piezoelectric element far from the position of the vibration node in the piezoelectric element group vibrates. As a result, the efficiency was very poor.

  In view of such a situation, the present invention provides an ultrasonic composite vibrator that can efficiently transmit vibration of each vibration mode to the vibrator and can be separately controlled for each vibration. It is something to be offered.

In order to achieve the above-described object of the present invention, an ultrasonic composite vibrator according to the present invention is different from a vibrator main body having a length of one wavelength or more of the resonance frequency and having at least two node positions. And at least two piezoelectric elements each having a vibration mode, the piezoelectric elements respectively disposed at positions of at least two nodes of the vibrator main body .

Here, each piezoelectric element arranged at the position of the node of the vibrator body may be composed of a piezoelectric element group in which a plurality of piezoelectric elements having the same vibration mode are stacked.

  The at least two piezoelectric elements may be driven by different drive signals.

  The at least two piezoelectric elements may be driven by a common drive signal.

  Further, different vibration modes of at least two piezoelectric elements may be longitudinal vibration and torsional vibration.

  The ultrasonic composite vibrator of the present invention has an advantage that vibration of each vibration mode can be efficiently transmitted to the vibrator and can be separately controlled separately for each vibration.

FIG. 1 is a schematic side view for explaining the configuration of the ultrasonic composite vibrator of the present invention. FIG. 2 is a distribution diagram of longitudinal vibration and torsional vibration of the ultrasonic composite vibrator of the present invention. FIG. 3 is a schematic side view for explaining a configuration when a piezoelectric element group is used in the ultrasonic composite vibrator of the present invention.

Hereinafter, embodiments for carrying out the present invention will be described together with illustrated examples. FIG. 1 is a schematic side view for explaining the configuration of the ultrasonic composite vibrator of the present invention. As shown in the figure, the ultrasonic composite vibrator 10 of the present invention is mainly composed of a vibrator main body 11 and a piezoelectric element 20. This is driven by the drive unit 30.

Vibrator body 1 1, have a wavelength longer than the resonant frequency, so as to have a position of at least two sections, the length and the resonance frequency is set. Specifically, ultrasonic composite transducer 10 is bolted Langevin type transducer incorporating a piezoelectric element 20 to the position of the two sections of the vibrator body 1 1. The ultrasonic composite oscillator 10, that engineering tool horn 12 is not connected. As an example of the resonance frequency of the vibrator body 1 1, the resonance frequency of the longitudinal vibration 3 3.8 kHz, the resonant frequency of the torsional vibration 20. What is necessary is just to design so that it may become the length of 1 wavelength of each vibration to propagate as 9 kHz. Vibrator body 1 1 may be any and cylindrical for example, made of duralumin. Engineering tools horn 12 is intended to be in direct contact with the workpiece, it is preferable strong wear. The tool horn 12 only needs to be screwed into the vibrator main body 11 so as to be replaceable, and can be replaced when worn. Moreover, it is also possible to process the front-end | tip part of the tool horn 12 suitably so that processing efficiency may be raised. Furthermore, the tool horn 12 can be exchanged for one suitable for the type of processing to be performed on the workpiece.

The piezoelectric element 20 includes at least two piezoelectric elements 21 and 22 each having different vibration modes. For example, it includes a longitudinal vibration piezoelectric element 21 having a longitudinal vibration mode and a torsional vibration piezoelectric element 22 having a torsional vibration mode. Further, the ultrasonic composite vibrator of the present invention is not limited to these vibration modes, and various piezoelectric elements such as a piezoelectric element having a bending vibration mode can be combined. The piezoelectric element 20 is disposed at the position of the two sections of the vibrator body 1 1. Specifically, in the illustrated example, the longitudinal vibration piezoelectric element 21 is disposed at the first node position from the left, and the torsional vibration piezoelectric element 22 is disposed at the second node position.

Here, the position of the vibration node will be described with reference to FIG. In Figure 1, a sine wave expressed in gray line on the vibrator body 1 1 is a vibration distribution of the vibrator body 1 1. As shown in the figure, in the ultrasonic composite vibrator 10 of the present invention, the piezoelectric elements 21 and 22 are arranged at the positions of the two nodes of the vibrator main body 11 , and the wavelength of the longitudinal vibration and the wavelength of the torsional vibration are matched. I understand that

The ultrasonic composite vibrator 10 configured as described above is driven by the drive unit 30. The drive unit 30 applies a resonance frequency signal in the longitudinal vibration mode to the piezoelectric element 21 for longitudinal vibration and applies a resonance frequency signal in the torsional vibration mode to the piezoelectric element 22 for torsional vibration . For example, two drive units 30 may be prepared for longitudinal vibration and for torsional vibration, and a resonance frequency signal may be applied to each piezoelectric element. Specifically, the resonance frequency of longitudinal vibration is 33.8 kHz, and the resonance frequency of torsional vibration is 20 . When designing the vibrator body 1 1 is a 9 kHz, the drive unit 30, the longitudinal vibration piezoelectric element 21 applies a resonance frequency of 3 3.8 kHz, the torsional vibration piezoelectric element 22 20. A resonance frequency of 9 kHz may be applied. By driving with different drive signals in this way, each vibration obtained can be arbitrarily controlled. Therefore, for example, the intensity of each vibration can be arbitrarily adjusted by adjusting the voltage of the applied signal.

  Further, the two piezoelectric elements may be driven by a common drive signal. In this case, the drive unit may be composed of, for example, an oscillator for longitudinal vibration, an oscillator for torsional vibration, and an adder that synthesizes them. The longitudinal vibration oscillator generates a resonance frequency signal for longitudinal vibration. The torsional vibration oscillator generates a resonance frequency for torsional vibration. Then, the adder may add these respective resonance frequency signals and then apply this drive signal to each piezoelectric element.

  As described above, the ultrasonic composite vibrator of the present invention can use various modes of drive signals and has a high degree of freedom.

Now, specific characteristics of the ultrasonic composite vibrator of the present invention configured as described above will be described with reference to FIG. FIG. 2 is a distribution diagram of longitudinal vibration and torsional vibration of the ultrasonic composite vibrator of the present invention. As measurement conditions, the resonance frequency of longitudinal vibration was 33.8 kHz, and the resonance frequency of torsional vibration was 20 . As 9 kHz, what was designed as the length which becomes 1 wavelength of each vibration to propagate was used. Specifically, a vibrator main body 11 shown in FIG. 1 connected to a tool horn 12 having a length of 72.6 mm and a diameter of 30 mm was used. For measurement, the distance in the length direction of the tool horn 12 was defined as x [mm]. Further, each vibration of the tool horn 12 portion was obtained as a terminal current of 50 mA for the longitudinal vibration piezoelectric element 21 and the torsional vibration piezoelectric element 22. FIG. 2A is a vibration distribution diagram when both piezoelectric elements 21 and 22 are driven with a drive frequency of 33.8 kHz, and FIG. 2B is a diagram of both piezoelectric elements 21 and 22 with a drive frequency of 20.9 kHz. It is each vibration distribution figure at the time of driving.

  As can be seen from FIG. 2A, when driven at 33.8 kHz, the longitudinal vibration has a distribution of 1/2 wavelength and the torsional vibration has a distribution of 3/4 wavelength. It can also be seen that the longitudinal vibration amplitude is obtained to be larger than the torsional vibration amplitude throughout the tool horn. From this, it can be seen that longitudinal vibration is mainly obtained as designed at a driving frequency of 33.8 kHz.

  Further, as can be seen from FIG. 2B, when driven at 20.9 kHz, the torsional vibration has a half-wave distribution, but it can be seen that longitudinal vibration is hardly obtained. This shows that torsional vibration is mainly obtained as designed at a drive frequency of 20.9 kHz.

  It can also be seen that the positions of the nodes of the longitudinal vibration distribution when driven at 33.8 kHz and the positions of the nodes of torsional vibration when driven at 20.9 kHz are substantially the same.

  Thus, it can be seen that in the ultrasonic composite vibrator of the present invention, the obtained vibration nodes coincide with each other. Accordingly, it is easy to fix the vibrator, and it can also be seen that one vibration does not substantially affect the other vibration.

In the illustrated example described above, the example in which the two piezoelectric elements are arranged at the positions of the two nodes with respect to the vibrator main body having the positions of the two nodes has been described, but the present invention is not limited to this. That is, the vibrator body may be configured to have a length having three or more nodes, and more piezoelectric elements may be used, and these piezoelectric elements may be disposed at each vibration node.

The piezoelectric element may be composed of a piezoelectric element group in which a plurality of piezoelectric elements having the same vibration mode are stacked. FIG. 3 is a schematic side view for explaining a configuration when a piezoelectric element group is used in the ultrasonic composite vibrator of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same parts. In the same figure, only the vibrator main body and the piezoelectric element are shown. As illustrated, for example, the longitudinal vibration piezoelectric element 21 may include a longitudinal vibration piezoelectric element group 24 in which a plurality of piezoelectric elements 21 are stacked. Similarly, the torsional vibration piezoelectric element 22 may include a torsional vibration piezoelectric element group 25 in which a plurality of piezoelectric elements 22 are stacked. In such a configuration, since the piezoelectric element group in each vibration mode can be arranged so that the center of the piezoelectric element group is at the position of the vibration node, the vibration efficiency is extremely low compared to the inefficient state as in the prior art. Will be better.

Moreover, since the position of the node of the vibration of the longitudinal vibration and the torsional vibration of the ultrasonic composite vibrator of the present invention coincides, when the vibration source is actually fixed, it is easy to fix at the position of the node. For example, the vibrator body is configured to have a length corresponding to 1.5 wavelengths and configured to have three node positions. As a result, one node can be fixed, and the positions of the other two nodes can be used for the arrangement of the piezoelectric elements.

  Note that the ultrasonic composite vibrator of the present invention is not limited to the above-described illustrated examples, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Ultrasonic compound vibrator 11 Vibrator body 12 Tool horn 20 Piezoelectric element 21 Piezoelectric element for longitudinal vibration 22 Piezoelectric element for torsional vibration 24 Piezoelectric element group for longitudinal vibration 25 Piezoelectric element group for torsional vibration 30 Drive part

Claims (5)

An ultrasonic composite vibrator that generates an ultrasonic composite vibration, wherein the ultrasonic composite vibrator includes:
A vibrator main body having a length of one wavelength or more of the resonance frequency and having at least two node positions;
At least two piezoelectric elements each having different vibration modes for matching the positions of the nodes, the piezoelectric elements respectively disposed at the positions of at least two nodes of the vibrator body;
An ultrasonic composite vibrator comprising:   2. The ultrasonic composite vibrator according to claim 1, wherein each piezoelectric element arranged at a node position of the vibrator main body includes a piezoelectric element group in which a plurality of piezoelectric elements having the same vibration mode are stacked. An ultrasonic composite vibrator.   3. The ultrasonic composite vibrator according to claim 1, wherein the at least two piezoelectric elements are respectively driven by different drive signals.   3. The ultrasonic composite vibrator according to claim 1, wherein the at least two piezoelectric elements are respectively driven by a common drive signal. 4.   5. The ultrasonic composite vibrator according to claim 1, wherein different vibration modes of the at least two piezoelectric elements are longitudinal vibration and torsional vibration. 6.