JPS625676B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for ultrasonically cleaning an object by driving an ultrasonic transducer alternately with two different frequency outputs. Since the ultrasonic intensity (amplitude) varies depending on the distance from the ultrasonic emission surface to the surface where the vibrations are reflected, such as the object to be cleaned or the surface of the cleaning liquid, the ultrasonic frequency should always be adjusted so that the ultrasonic vibrations are maximized and the cleaning effect is enhanced. Adjustments are made manually or automatically (called automatic tracking). FIG. 1A shows an explanatory diagram of an example of a conventional method, and 1
is a cleaning tank, 2 is a cleaning liquid, 3 is an ultrasonic vibrator, 4 is an ultrasonic oscillator, and 5 is an object to be cleaned. 2 shows the state immersed in the cleaning liquid 2 in different ways. In this way, each point on the surface of the object to be cleaned 5 is usually not at a constant distance from the ultrasonic emission surface.
Now, among the distances from the ultrasonic emission surface to the ultrasonic reflection surface of the object to be cleaned 5, the distance to a specific point is l ₁ to _{l 7}
Let us consider the relationship between this distance and the wavelength of ultrasonic vibration. In the method using one ultrasonic oscillator 4, the resonance frequency of the ultrasonic transducer 3 is adjusted according to the distance l ₂ .
oscillate the ultrasonic oscillator 4 at f ₀ , for example 26kHz,
When cleaning the object 5, the distance l ₂ and the distance l ₆ which is an integer multiple of a half wavelength (λ/2) from this distance = l ₂ + n
The maximum ultrasonic vibration can be obtained from the reflecting surfaces of λ/2 (n=1, 2, 3...), but the
Distance 1/4 wavelength (λ/4) apart l ₄ = l ₂ +nλ/2±λ/4
The ultrasonic vibration is at its minimum on the reflective surface, and the cleaning effect in this area is poor. FIG. 1B shows the ultrasonic intensity distribution according to f ₀ in this case. FIG. 2A shows an explanatory diagram of another example of the conventional method that improves the above-mentioned drawbacks, in which 4a and 4b are two ultrasonic oscillators, and every half cycle of the frequency of the commercial power supply 6, a diode 7a or 7b is used. The resonant frequency f ₀ of the ultrasonic transducers 3a to 3d is
A slightly different frequency f ₁ = f ₀ + Δf ₀ = 26.3kHz,
Each generates an output of f ₂ =f ₀ −Δf ₀ =25.7kHz. In this method of using two ultrasonic oscillators 4a and 4b, the distance
The ultrasonic vibration reaches its maximum at f ₁ = 26.3 kHz on the reflecting surfaces of l ₁ and l ₅ , and at f ₂ = 25.7 kHz on the reflecting surfaces of l ₃ and l ₇ , and a nearly uniform cleaning effect can be obtained regardless of the distance. However, as the number of ultrasonic transducers used increases,
The disadvantage is that the wiring is also complicated. The present invention aims to improve the above-mentioned drawbacks, and a method and apparatus for implementing the present invention will be explained in detail below with reference to FIG. The present invention shown in the third diagram is operated alternately via the diode 7a or 7b every half cycle of the frequency of the commercial power supply 6, and the resonance frequency f ₀ is set by the resonance characteristic of one magnetostrictive ultrasonic transducer 3. ,for example
Slightly different frequencies f ₁ = f ₀ + Δf ₀ = 26 within a range that is considered substantially flat and centered around 26 kHz.
+0.3=26.3kHz, _f2 = _f0 − _Δf0 =26−0.3=
Using two ultrasonic oscillators 4a and 4b that each generate an output of 25.7kHz, these frequencies f ₁ and f ₂
When driving the magnetostrictive ultrasonic transducer 3 alternately every half cycle of the commercial power frequency with the output _of By alternately turning on and off the semiconductor switch circuit SC every half cycle of the commercial power frequency, a capacitor C consisting of a capacitor C ₂ connected in parallel through a capacitor C 2 is changed to C=C ₁ +C ₂ or C=C ₁ ; A method and apparatus for ultrasonically cleaning an object 5 by resonating and matching a series resonant circuit consisting of an inductance Ld and a capacitance C formed by the winding of a magnetostrictive ultrasonic transducer 3 to two frequencies f ₁ and f ₂ respectively. be. Note that there is a relationship between capacitance C ₁ + C ₂ , C ₁ and resonance frequency f ₁ , f ₂

【formula】

There is a relationship as shown in [Formula], and it goes without saying that the values of C ₁ and C ₂ must be determined so as to satisfy this relationship. Further, as a semiconductor switch circuit SC, for example, as shown in FIG. 4, one set of bridge terminals a,
Connect b between two points where two capacitors C ₁ and C ₂ are connected/disconnected, in this case between one terminal of two capacitors C ₁ and C ₂ , and connect the bridge terminals c and d of the other set. A non-directional semiconductor switch circuit can be used in which the collector and emitter of an NPN switching transistor 8 are connected between them, and the commercial power supply 6 is connected between the base and emitter of this switching transistor 8. In addition, in order to increase the withstand voltage and current, the capacitance is increased as shown by the dotted line.
Parallel circuits of C ₃ and C ₄ may be connected in series. Thus, the ultrasonic oscillators 4a and 4b operate alternately every positive and negative half cycle of the commercial power supply 6, and the transistor 8 is turned on and off every positive and negative half cycle of the commercial power supply 6. In the positive half cycle, the transistor 8 is on, so for the output of the frequency f ₁ of the ultrasonic oscillator 4a, the circuit between the terminals a and b of the bridge circuit includes the diode 9a, the collector of the transistor 8, the emitter, and the diode 9b. Or, the circuit of diode 9c, collector and emitter of transistor 8, and diode 9d is in a closed state, and the capacitance C ₂ is
It is connected in parallel to C ₁ and the total capacitance C becomes C ₁ +C ₂ .
In addition, in the negative half cycle, since transistor 8 is off, terminals a and b of the bridge circuit are in an open state, capacitance C ₂ is not connected in parallel with C ₁ , and the total capacitance C becomes C ₁ . . As a result, in the positive half cycle of the power supply 6, the output of the frequency f ₁ of the ultrasonic oscillator 4a is applied to the series circuit of the ultrasonic vibrator 3 and the capacitance C=C ₁ +C ₂ .

[Formula] causes series resonance, and in the negative half cycle of the power supply 6, the output of the frequency f ₂ of the ultrasonic oscillator 4b is added to the series circuit of the ultrasonic vibrator 3 and the capacitance C=C _1.

[Formula] causes series resonance, and electrical matching of the ultrasonic transducer 3 is achieved for each frequency f ₁ and f ₂ . In this way, in the method of the present invention shown in FIG. 3, the capacitance C ₂ of the ultrasonic transducer 3 is changed every half cycle of the frequency of the commercial power supply 6 to cause resonance and matching, and output two frequencies f ₁ and f ₂ . As a result, the number of ultrasonic vibrators 3 used can be reduced to one, and the wiring thereof is simplified, and the ultrasonic vibrations can be controlled regardless of the distance between the ultrasonic reflecting surface and the reflecting surface of the object 5 to be cleaned. The size can be made almost uniform, and a uniform cleaning effect can be obtained over the entire object to be cleaned. In addition, in FIG. 3, two ultrasonic oscillators 4a, 4
b are completely separate, but since they do not operate at the same time, only the oscillation parts of f ₁ and f ₂ are made separate, the voltage/power amplification part is shared, and the two oscillation parts are combined as shown in Figure 3. It goes without saying that it may be activated every half cycle of the commercial power supply 6, as shown in FIG. Of course, the present invention may be practiced by connecting several ultrasonic transducers in parallel. In addition, in the method and apparatus shown in Figure 3, the change in the capacitance connected to one ultrasonic oscillator is the change in the capacitance connected to the two capacitors C ₁ and C ₂ .
This is done depending on whether or not to make disconnections parallel,
Of course, this can be done by connecting the two capacitors C ₁ and C ₂ in series and switching off one of the capacitors by the semiconductor switch circuit SC. Next, to give an example of an experiment, a steel block measuring 4 cm x 4 cm x 16 cm was coated with water-soluble paint and left ^for 10 days to be cleaned. Cleaning was carried out using a conventional method in which the ultrasonic vibrator was hung diagonally with a wire in a cleaning tank with a capacity of 20 mL, and was driven with one frequency output for 10 seconds, and an inventive method in which the ultrasonic vibrator was driven with two frequency outputs. As a result, in the former conventional method, cleaning unevenness was observed at every half wavelength of the distance from the ultrasonic emission surface, but in the latter method of the present invention, this cleaning unevenness was greatly improved, and there was no problem at all in practice. .

[Brief explanation of the drawing]

Figures 1A and B are an explanatory connection diagram of an example of the conventional method and an ultrasonic intensity distribution diagram in this method, respectively, and Figures 2A and B are an explanatory connection diagram of another example of the conventional method and a diagram of the ultrasonic intensity distribution in this method, respectively. FIG. 3 is an explanatory connection diagram of an embodiment of the method and apparatus of the present invention, and FIG. 4 is a connection diagram showing an example of a semiconductor switch circuit used in the method and apparatus of the present invention. 1...Cleaning tank, 2...Cleaning liquid, 3...Ultrasonic transducer, 4a, 4b...Resonance characteristics of the ultrasonic transducer 3, within a range that is considered to be substantially flat centered around the resonance frequency _f0 . Two ultrasonic oscillators that alternately generate outputs of two frequencies f ₁ and f ₂ at every half cycle of the commercial power frequency, 5...Cleaning object, 6...
Commercial power supply, 7a, 7b... Diode, 8... Switching transistor, 9a to 9d... Bridge circuit diode, a, b... One set of bridge terminals, c, d... Other set of bridge terminals,
_C1 , _C2 ...capacitance, C...capacitance connected to the ultrasonic transducer 3, Ld...inductance due to the winding of the ultrasonic transducer 3, SC...semiconductor switch circuit.

Claims (1)

[Claims] 1. One or more ultrasonic transducers having the same resonance characteristics having a resonant frequency are attached to a cleaning tank, and the resonance characteristics of the ultrasonic transducers are used to generate a substantially The ultrasonic transducer or all of the plurality of ultrasonic transducers are simultaneously driven alternately with power of two slightly different frequencies within a range that is considered flat. Ultrasonic cleaning method used. 2. One or more ultrasonic transducers with the same resonance characteristics having a resonant frequency are attached to a cleaning tank, and the range of the resonance characteristics of the ultrasonic transducers is considered to be substantially flat centered around the resonant frequency. When simultaneously driving the one ultrasonic transducer or all of the plurality of ultrasonic transducers alternately every half cycle of the commercial power supply frequency with power of two slightly different frequencies within the The capacitance connected to the transducer is changed by a semiconductor switch circuit that alternately turns on and off every half cycle of the commercial power frequency, and one resonant circuit consisting of the ultrasonic transducer and the capacitor resonates at each of the two frequencies. An ultrasonic cleaning method using two frequencies, characterized in that they are aligned and matched. 3. One or more ultrasonic transducers with the same resonance characteristics and having a resonance frequency attached to the cleaning tank;
The resonance characteristics of this ultrasonic transducer generate two slightly different frequency outputs within a range that is considered to be substantially flat around the resonant frequency, alternately every half cycle of the commercial power frequency. A sonic oscillator that turns on and off every half cycle of the mains frequency.
The two capacitors are connected/disconnected by repeating the off-state alternately to change the capacitance connected to the one or more ultrasonic transducers, thereby converting one resonant circuit by the ultrasonic transducer and the capacitor into two. It consists of a semiconductor switch circuit for resonating and matching each frequency, and this semiconductor switch circuit connects and disconnects the two capacitors between one set of bridge terminals of a bridge circuit consisting of four diodes. 2, the collector and emitter of a switching transistor are connected between the other set of bridge terminals, and a commercial power supply is connected between the base and emitter of this switching transistor. Ultrasonic cleaning equipment using two frequencies.