JPH0312364Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an ultrasonic device that has been treated with voltage resistance to prevent dielectric breakdown caused by the electric charge and to allow safe work, especially when applying ultrasonic vibrations to an electrically charged object. It concerns a sound wave vibrator.

When applying ultrasonic vibrations to perform ultrasonic processing on a charged object, for example to drill a hole, conventionally, the magnetostrictive vibrator is processed only by insulation between the magnetostrictive vibrator used as the ultrasonic drive source and the drive winding. This prevents the electric charge from affecting the oscillator being driven, and also prevents danger to the operator's body.

However, in this method, the value of electric charge becomes high, and in practice, dielectric breakdown occurs at about 1 KV, so there are restrictions on use, and it is desirable to be able to use it safely even under conditions of even higher electric charges.

The present invention was developed in consideration of these points, and a vibration system is constructed by combining in series a "vibrator," a "cone," and a "horn" that are designed to have the same resonance frequency. This is a conventional type of ultrasonic transducer in which a part of the cone is replaced with ceramic without changing the resonance frequency, and will be described in detail below with reference to examples.

Fig. 1A shows the state when ultrasonic vibration is applied to the charged object 1 to be vibrated, Fig. 1B shows the vibration velocity distribution, and Fig. 2 shows the shape of the insulating ceramic 4 shown in Fig. 1. The ultrasonic transducer is integrally composed of a horn 2 made of metal such as stainless steel, a cone 3 made of the same metal, an insulating ceramic 4, and a transducer 5 made of a magnetostrictive material. 4 is bonded to the cone 3 and the vibrator 5 with adhesive, respectively. The cone 3 is used to magnify the vibration of the end face of the vibrator 5 and transmit it to the horn 2, and the amplitude ratio is proportional to the approximate area ratio of the thick end face (slanted part) and the narrow end face of the cone 3.

The ceramic material used here is alumina, silicon nitride, etc., which have high tensile strength and can withstand vibration stress.
If the thickness l is alumina, the dielectric strength is 15KV/mm.
Take this into account and decide accordingly.

Considering that the dielectric strength is determined by the dielectric breakdown on the outer periphery rather than the dielectric breakdown inside the insulator itself, the shape is designed to increase the creepage distance by cone 3.
and a large diameter portion 11 larger than the outer diameter of the vibrator 5.
shall be. In other words, the dielectric strength of alumina, which is an insulator, is 15KV/mm, so if the thickness l is 10mm,
It will be 150KV. However, the dielectric strength voltage of air is lower than this, so if you increase the creepage distance of the insulator to increase the dielectric strength voltage,
Dielectric breakdown at the outer periphery can be prevented. By doing so, it is possible to prevent the influence of electric charge from being exerted on the vibrator 5 and the like. In addition, a small diameter protrusion 12 is formed on the bottom surface, and when joining the cone 3 and ceramic 4, the protrusion 12 is press-fitted into a recess 13 provided in the cone 3 and bonded. It is designed to prevent the adhesive from peeling off.

On the other hand, since no internal stress is generated at the bonding surface between the ceramic 4 and the vibrator 5, sufficient adhesive strength can be obtained even if the bonding surface remains flat without any special consideration.

Note that since the insulating ceramic 4 forms a part of the cone 3, the resonant frequency of the cone 3 is adjusted based on physical constants so that the resonant frequency of the cone 3 matches the resonant frequency of the horn 3 and the vibrator 5. The dimensions of both are determined.

Although not directly related to the present invention, 6 is a fixed flange provided at the vibration node position of the cone, 7 is an insulating case, 8 is a lead wire for the drive winding of the vibrator 5, and 9 is a connector. When the output cord of the oscillator (not shown) is connected and the ultrasonic vibrator is driven, the tip of the horn 2 vibrates as shown by the arrow.
This vibration is applied to the charged object 1 to be vibrated. Reference numeral 10 denotes a discharge mechanism, which discharges the electric charges on the horn and the cone when the tip of the horn is separated from the charged object.

The state of the vibration velocity distribution of each part during operation is as shown in FIG. 1B.

As described above, in the present invention, the resonant frequency of the horn 2 and the vibrator 5 is changed by integrally providing the insulating ceramic 4 having a distance necessary for a predetermined dielectric strength voltage to the cone 3 which is a part of the vibration system. Furthermore, since the outer diameter of the insulating ceramic 4 is made larger than the outer diameters of the cone 3 and the vibrator 5, dielectric breakdown of the outer circumference of the insulator can be prevented. Therefore, the influence of electric charges on the vibrator 5 and the like can be eliminated, and a withstand voltage effect can also be obtained. The results of practical tests confirmed that it can be used in the range of about 0 to 50 KV.

[Brief explanation of the drawing]

FIG. 1A shows the configuration of the embodiment, and FIG. 1B is a drawing showing the vibration velocity distribution corresponding to each part. FIG. 2 is a drawing showing the shape of the ceramic 4. As shown in FIG. 1... Charged vibrating object, 2... Horn, 3...
... Cone, 4 ... Ceramic, 5 ... Vibrator, 6
... Fixed flange, 7 ... Insulation case, 8 ... Lead wire, 9 ... Connector, 10 ... Discharge mechanism, 1
1...Ceramic large diameter part, 12...Protrusion part, 13
...Concavity.

Claims (1)

[Scope of utility model registration request] In an ultrasonic vibrator having a structure in which a horn, a cone, and a vibrator, each having the same resonant frequency, are integrally coupled in series, a large-diameter portion that is larger in size than the diameter of the cone and the vibrator and has an appropriate thickness; An insulating ceramic having a small-diameter protrusion at the center of the end face is formed as a part of the cone, and the resonant frequency of the cone and the insulating ceramic as a unit is matched with the resonant frequency of the horn and the vibrator, and An insulated ultrasonic transducer having a structure in which a protrusion is press-fitted into a recess provided at the center of an end face of a cone and fixed with adhesive, and the end face of the large diameter part and the end face of the vibrator are fixed with adhesive.