JPH0541823Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic vibrator, and more particularly to an ultrasonic vibrator for ultrasonically cleaning objects to be cleaned in a cleaning fluid.

[Prior art] As is well known, with the recent development of precision industry,
A large number of highly precise devices that are able to withstand oil, cutting chips, and foreign dust are now being produced.
For this reason, ultrasonic cleaning has become popular in place of the conventional simple cleaning using showers, jets, brushes, etc. This is because ultrasonic cleaning is a simple operation and can clean the product well in a short time without directly touching the product. The general configuration of an ultrasonic cleaning device for performing such ultrasonic cleaning is, as shown in Fig. 9, with a stud bolt 3' placed on the bottom surface 2' of a cleaning tank 1' made of SUS, etc. An ultrasonic vibrator 7' is constructed by attaching a vibrating element 12' consisting of an aluminum diaphragm 4', a piezoelectric element 5', and a resonant diaphragm 6' via an adhesive. In the case of the above structure, when a high frequency voltage is applied to the piezoelectric element 5' to cause electrostrictive motion, the diaphragms 4' and 6' vibrate at high frequency, causing the bottom surface 2' of the cleaning tank to vibrate at high frequency. Since this high frequency vibration is transmitted to the cleaning fluid 8' contained in the cleaning tank 1', ultrasonic cleaning can be performed if the object to be cleaned is placed in the cleaning fluid 8'.

As described above, when the ultrasonic transducer 7' is constructed by attaching one vibrating element 12' on one resonant diaphragm 6', the resonant diaphragm 6' has a single resonant frequency ₀ [ KHz] begins to vibrate.
The resonant plate 6' thus has a single resonant frequency ₀ [K
Hz], a strong sound pressure can be generated as shown by a in FIG. but,
In this way, the resonant diaphragm 6' has a single resonant frequency _{of 0.}
When ultrasonic vibration is performed at [KHz], a standing wave b' is generated in the cleaning fluid 8' as shown in FIG.
As a result, the strength of the standing wave b' varies in the cleaning fluid 8' every 1/2 of the wavelength of the standing wave b', and the object to be cleaned located at the stress node can hardly be cleaned. occurs. In other words, uneven cleaning occurs on the object to be cleaned.

In order to eliminate such uneven cleaning, the resonant diaphragm 9' is formed of a square bar as shown in FIG.
An ultrasonic transducer 10' in which two transducer elements 12' are attached has been put into practical use.

[Problems to be solved by the invention] As described above, when two vibrating elements 12' are attached to a common resonant diaphragm 9' and vibrated ultrasonically,
The frequency of the above common resonant diaphragm 9' is the resonant frequency
₀ [KHz] has a constant width.
That is, the ultrasonic vibration in this case has a resonance frequency of ₀ [KHz] and a frequency of ₁ , as shown in c in Figure 6.
It is now performed at a width of ~f ₃ [KHz]. This consists of a vibrating element 12' mounted on a resonant diaphragm 9',
It is thought that this is caused by the slight difference in the frequency of vibration 12' within the range of manufacturing tolerances and the occurrence of resonance unevenness in the resonant diaphragm 9'.

Since the vibration is in a frequency band with a certain width, when this ultrasonic vibrator 10' is attached to the bottom surface 2' of the cleaning tank 1' and the cleaning fluid 8' is vibrated, a stable wave is generated. In addition to b′, traveling waves can also be generated. Therefore, it is possible to eliminate uneven cleaning compared to the case of ultrasonic cleaning using only the standing wave b'. However, in this case, the resonance frequency is approximately ₀ [KHz].
Vibration in a frequency band exceeding 1.2 times is extremely weak, and the damping rate in the liquid is also extremely large. Therefore, the non-stationary wave, that is, the traveling wave, generated by this ultrasonic vibrator 10' is of little use in actual cleaning, and is a weak constant wave generated by vibration near the resonance frequency ₀ [KHz]. The reality was that cleaning was done only by the presence of waves. In other words, the cleaning effect was not improved.

Furthermore, as shown in FIG.
When 0' is applied to the drop-in type ultrasonic generator 11', vibrations in the frequency band shown at d in FIG. 6 are generated. This resulted in a far inferior result compared to the case where it was attached to the bottom surface 2'.

The present invention was developed in view of the above points, and its purpose is to generate standing waves and non-standing waves in a well-balanced manner, thereby eliminating uneven cleaning and improving cleaning performance. The purpose of the present invention is to provide an ultrasonic vibrator that enables ultrasonic cleaning.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a superstructure in which two vibrating elements each having a vibrating plate are mounted in parallel on a common resonating plate. In the sonic vibrator, the length l ₁ of one surface 3 of the resonance plate to which the two vibration elements 4 and 5 are attached in the parallel direction of the vibration elements 4 and 5 is equal to the cleaning fluid 1.
The vibration elements 4, 5 on the other side 14 of the resonance plate are attached to the cleaning tank 12 containing the vibration elements 4, 5.
The length of the resonance plate in the parallel direction of the vibration elements 4 and 5 is changed from the one surface 3 side to the other surface 1 so that the length l ₂ in the parallel direction
It is characterized by a gradual change over the four sides.

[Function] Since the present invention consists of the above-mentioned technical means, it is possible to vibrate the common resonant plate 2 in a frequency band with a certain width, and to generate a strong vibration pressure at a resonant frequency of ₀ [KHz]. ] vibration and a resonant frequency that can generate non-standing waves ₀ [KHz]
It has been experimentally confirmed that it is possible to generate both vibrations of other frequencies in a well-balanced yet strong manner. Although the applicant has not clearly elucidated the reason for this, one possible reason is as follows.

In other words, when an elastic rod is subjected to longitudinal vibration from the outside by some method, it initially begins to vibrate according to the externally applied frequency, but this forced vibration soon stops and the elastic rod itself is the most likely to vibrate. It starts to vibrate at a specific frequency, gradually attenuates, and after a certain period of time has passed, the amplitude reaches O.

This is called the natural frequency of the elastic body, and this natural frequency is determined by the material, length, etc. of the elastic body. Therefore, if you apply vibration at the natural frequency from the beginning, it will vibrate well because it is the frequency at which it is most likely to vibrate. This phenomenon in which the natural frequency and the frequency of the external driving force match is called resonance.

The cleaning fluid 15 contained in the cleaning tank 12 is connected to the natural frequency of the common resonance plate 2, that is, the resonance frequency.
When vibrating only at ₀ [KHz], only standing waves are generated as described above, resulting in uneven cleaning. However, in this case, the common resonance plate 2 is attached to the surfaces 13 and 18 that vibrate the cleaning fluid 15, with the length of the surface 3 to which the two vibrating elements 4 and 5 are attached being l ₁ . The length l ₂ of the surface 14 is longer than the above-mentioned length l ₁ . Therefore the frequency f ₄ corresponding to the length l ₁
The common resonant plate ₂ can be vibrated in a wide frequency band from [KHz] to a frequency ₁ [KHz] corresponding to the length l2.

For this purpose, this common resonant plate 2 has a natural frequency,
That is, it is possible to generate strong sound pressure in the cleaning fluid 15 by a standing wave by vibrating at the resonance frequency x [KHz], and it is also possible to cause the cleaning fluid to vibrate strongly even at frequencies other than the resonance frequency x [KHz]. It is believed that cleaning can be performed using non-standing waves.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings FIGS. 1 to 8.

In the figure, 1 indicates an ultrasonic transducer, and 2 is a common resonator.
The two vibration elements 4, 5 are attached to the surface 3 of the resonator 2. The vibration elements 4, 5 each comprise an aluminum diaphragm 6, piezoelectric elements 7, 8, and terminals 9, 9 for feeding power to the piezoelectric elements 7, 8. The vibration elements 4, 5 are attached to the common resonator plate 2 with a bolt 10.

The above-mentioned common resonance plate 2 is formed of a rectangular aluminum plate with a rectangular planar shape, and the second
As shown in the drawings and FIG. 3, screw holes 11, 11 are formed at symmetrical positions from the center. These screw holes 11, 11 are formed for screwing in bolts 10 for mounting the vibration elements 4, 5 on the surface 3 of a common diaphragm.

The corner portion 3a of the common resonance plate 2 is cut at an angle of 45 degrees toward the back surface 14 that is bonded to the bottom surface 13 of the cleaning tank 12, and the length of the surface 3 in the parallel direction of the vibration elements 4 and 5 is l ₁ is the length of the back surface 14 l ₂
It is shorter than . Thereby, the length of the resonance plate 2 in the parallel direction of the vibrating elements 4 and 5 gradually changes from the front surface 3 toward the back surface 14.
The ultrasonic transducer 1 formed in this way is installed in the cleaning tank 1.
In order to ultrasonically vibrate the cleaning fluid 15 contained in the cleaning tank 2, its back surface 14 is bonded to the bottom surface 13 of the cleaning tank 12 using an adhesive, for example, as shown in FIG.

Next, the operation will be explained based on the above embodiment.

Since the ultrasonic vibrator 1 of this embodiment is constructed as described above, when a predetermined high frequency voltage is applied to the terminals 9, 9, it vibrates in a wide frequency band from ₁ [KHz] to ₄ [KHz]. do. This seems to be because the common resonance plate 2 of this ultrasonic transducer 1 is formed with different lengths, such that the length of the front surface 3 is l ₁ and the length of the back surface 14 is l ₂ . . That is, the fifth
As shown in the figure, the front side 3 vibrates at a high frequency ₄ [KHz] corresponding to the length l ₁ , and the back side 14 vibrates at a low frequency ₁ [KHz] corresponding to the length l ₂ . Vibrate. Further, the resonant plate 2 as a whole vibrates at the natural frequency of this common resonant plate 2, that is, the resonant frequency x [KHz].

When the common resonance plate 2 vibrates as described above,
This vibration is transmitted to the cleaning liquid 15 contained in the cleaning tank 12 via the bottom surface 13 of the cleaning tank 12,
The cleaning fluid 15 is vibrated ultrasonically.

Among the frequency components included in the vibration of the common resonance plate 2, strong sound pressure is generated in the cleaning fluid 15 due to ultrasonic vibrations having a resonance frequency x [KHz], and the cleaning fluid is contained in the cleaning fluid. Good ultrasonic cleaning of the target object. The ultrasonic waves generated in the cleaning fluid 15 by this resonance frequency x [KHz] become standing waves.
Therefore, ultrasonic cleaning cannot be performed at the vibration nodes. However, the ultrasonic vibrator 1 in this case vibrates in a wide frequency band between frequency ₁ [KHz] and frequency ₄ [KHz]. This vibration is caused by a slight difference in the balance of vibration within the manufacturing tolerance of the two sets of vibrating elements 4 and 5 mounted on the surface 3 of the common resonant plate 2 as in the past, or by the resonance of the resonant plate 2. Unlike vibrations caused by unevenness, etc., this is a strong vibration that occurs in response to the lengths l ₁ and l ₂ of the resonator plate itself. Therefore, as shown in FIG. 6, the sound pressure does not suddenly weaken when the frequency exceeds _1.20 [KHz], which is 1.2 times the resonance frequency, as in the conventional vibration c. In other words, as shown by the dashed line e in Fig. 6, the vibration in the frequency band higher than the resonance frequency Become. Therefore, it is thought that it is possible to generate a sound pressure level of 16 or more that can be cleaned over a wide frequency band.

Since standing waves are not generated by vibrations at frequencies other than the resonance frequency x [KHz], the object to be cleaned can be cleaned well without uneven cleaning.

When the ultrasonic transducer 1 of the present invention was applied to an immersion-type ultrasonic generator 17, good cleaning could be achieved by using the method shown in FIG. That is, in the conventional immersion type ultrasonic generator, the convex surface of the vibration surface is directed outward as shown in FIG. 12, but in this example, the concave surface of the vibration surface 18 is directed outward. This is what I did.

In this embodiment, the common resonance plate 2 is shown as having a rectangular planar shape, but the planar shape may be formed in other shapes such as an ellipse as shown in FIG. You may.

[Effects of the invention] As detailed above, according to the invention, the common resonant plate 2 can be vibrated mainly at its overall natural frequency fx [KHz], and the resonant plate 2
From the frequency ₄ [KHz] corresponding to the length l ₁ of the surface 3 on which the vibrating elements 4 and 5 are attached, the other surface 1 of the resonance plate 2
4 can be vibrated well over a wide frequency band of frequency ₁ corresponding to the length l ₂ of cleaning fluid 15, that is, the frequency band of vibration can be widened, and therefore, there is no standing wave in cleaning fluid 15. Ultrasonic waves can generate both non-standing waves and non-standing waves in a well-balanced manner at a sound pressure higher than the sound pressure level that can be used for cleaning, thereby eliminating uneven cleaning and achieving good ultrasonic cleaning. We can provide vibrators.

[Brief explanation of the drawing]

The attached drawings, FIGS. 1 to 8, show embodiments of the present invention, in which FIG. 1 is a perspective view of an ultrasonic transducer, FIG. 2 is a plan view of a common resonant plate, and FIG. A cross-sectional view taken along line A-A, Fig. 4 shows the state in which it is attached to the bottom of the cleaning tank, Fig. 5 shows the relationship between the common resonance plate and the frequency generated, and Fig. 6 shows the relationship between frequency and sound. Fig. 7 is a graph showing the relationship between the frequency and sound pressure of a conventional ultrasonic transducer and the ultrasonic transducer of the present invention. FIG. 8 shows a modified example, and FIG. 9 is a plan view of a common resonance plate showing an example in which the common resonance plate is formed into an elliptical shape.
Fig. 12 shows the prior art, Fig. 9 shows an example in which a single vibration element is attached to a single resonant plate, and Fig. 1
Figure 0 is a side view showing an example of two vibration elements mounted on a common resonator plate, Figure 11 is a side view of an example of a conventional immersion type ultrasonic generator, and Figure 12 is a cleaning tank. FIG. In addition, in the figure 1... Ultrasonic transducer, 2... Common resonance plate, 3... Surface, 3a... Corner, 4, 5... Vibration element, 12... Cleaning tank, 13... Bottom surface, 14...
...back side, 15...cleaning fluid, 18...vibration surface, l ₁
...Length on the front side, l ₂ ...Length on the back side, respectively.

Claims (1)

[Claims for Utility Model Registration] 1. In an ultrasonic vibrator comprising two vibrating elements each having a vibrating plate attached in parallel on a common resonating plate, the two vibrating elements 4 and 5 are attached to one surface 3 of the resonant plate;
The length of the vibrating elements 4 and 5 in the parallel direction
l ₁ is the other surface 14 of the resonant plate attached to the cleaning tank 12 containing the cleaning fluid 15
The length of the vibrating elements 4 and 5 in the parallel direction
The vibration elements 4 and 5 are arranged so that the length is shorter than l ₂ .
An ultrasonic transducer characterized in that the length of the resonance plate in the parallel direction is gradually changed from the one surface 3 side to the other surface 14 side. 2 Corner portion 3a of the surface 3 of the resonance plate to which the vibration element is attached in the parallel direction of the vibration element
The ultrasonic transducer according to claim 1, which is a registered utility model, wherein the ultrasonic transducer is cut at an angle of 45 degrees toward the surface 14 that is attached to the cleaning tank 12.