JPH10150699A - Oscillator of bolting langevin type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more reliable oscillator of a bolting Langevin type obtaining more stable ultrasonic output by eliminating the deformation of a diaphragm with the change of an ambient temperature. SOLUTION: The oscillator of the bolting Langevin type comprises a front mass, a rear mass, at least one piezoelectric element and an electrode arranged between the front and rear masses and bolt 5 penetrating the center part of each constituting part of these for fastening, a female screw hole 22b is provided for the front mass of the oscillator of the bolting Langevin type and bolt 8B welded to the diaphragm 7 is screw-fixed to the female screw hole through a joint material S. A margin is given to the gap dimension W between the female screw hole and the bolt to collect the joint material in the gap between the female screw hole and the bolt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolted Langevin type vibrator using a piezoelectric ceramic element.
In particular, the present invention relates to a bolted Langevin type vibrator used for an ultrasonic cleaning device and the like, and particularly to a joint structure of the ultrasonic cleaning device with a diaphragm.

[0002]

2. Description of the Related Art A conventional configuration will be described with reference to the drawings. FIG. 1 is a schematic exploded perspective view showing a state in which a bolted Langevin type vibrator is attached to a diaphragm, and FIG.
FIG. 2 is a partial sectional view showing a conventional example.

A bolted Langevin type vibrator is composed of a front mass 2, an electrode plate 4b, a piezoelectric element 3b, an electrode plate 4a, a piezoelectric element 3a, and a rear mass 1 in this order from the ultrasonic radiation surface, and includes a stud bolt 5 and a nut. 6, it is fastened and fixed. The front mass 2 is made of a metal block of an aluminum alloy, has a truncated cone shape, and has a female screw portion 21a in the center portion of which a bolt is partially screwed. The electrode plates 4a and 4b have a configuration in which a protruding lead portion for external connection is provided in an annular shape, and the material is nickel,
Stainless steel or beryllium copper is used. The piezoelectric elements 3a and 3b are made of piezoelectric ceramics such as PZT (lead zirconate titanate), and have an annular cylindrical shape having a through hole in the center. Rear mass 1
Is made of a metal block of SUS or an aluminum alloy, and has a circular cylindrical shape with a through hole provided in the center.

[0004] The bolted Langevin type vibrator constructed as described above is incorporated in an ultrasonic cleaning device and attached to the vibrating plate 7 (vibrating portion) of the cleaning tank. A bolt 8A (made of SUS or the like) for attaching a bolted Langevin type vibrator is welded to the diaphragm 7. The front mass 2 of the bolted Langevin type vibrator is provided with a female screw portion 22a configured to be fitted to the bolt 8A. Then, a bonding material S made of an epoxy resin is interposed on the radiation surface of the front mass, and after the female screw portion 22a is screwed into the bolt 8A, the bonding material is cured, and the bolted Langevin type vibrator and the diaphragm Are mounted integrally. The gap dimension between the bolt and the female screw portion of the front mass is generally formed to be about 0.1 mm in the past.

[0005]

However, the material of the front mass of the bolted Langevin type vibrator (aluminum alloy) and the material of the bolt attached to the diaphragm (SU)
Since S) is different, the respective thermal expansion coefficients are different.
In the conventional gap size (0.1 mm) between the bolt and the female screw portion of the front mass, with a change in the environmental temperature,
Distortion is caused directly by the mutual thermal expansion or thermal contraction. As shown in FIGS. 7A and 7B, the diaphragm is deformed by being pulled (at a high temperature) or pushed out (at a low temperature) at a joint portion between the diaphragm and the bolt, and There is a problem that the transmission efficiency of the ultrasonic wave is reduced because the transmission of the ultrasonic vibration is not uniform. Further, by repeating the deformation of the diaphragm, the bonding material joining the diaphragm and the radiation surface of the front mass may be peeled off, and the ultrasonic vibration may not be transmitted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a more reliable bolted Langevin type vibrator which eliminates deformation of a diaphragm due to a change in environmental temperature and provides more stable ultrasonic output. is there.

[0007]

SUMMARY OF THE INVENTION The present invention provides a front mass made of a metal block, a rear mass also made of a metal block, at least one piezoelectric element and an electrode plate disposed between the front mass and the rear mass. There is a bolted Langevin type vibrator consisting of bolts that penetrate through the central part of each of these components and tighten and fix them,
A female threaded hole is provided in a front mass of the bolted Langevin type transducer, and in the female threaded hole, via a joining material, a bolted Langevin type transducer which is screwed and attached to a bolt welded to the diaphragm, The gap between the female screw hole and the bolt has a margin, and the joining material is accumulated in the gap between the female screw hole and the bolt.

With the above structure, even if a front mass and a bolt, which are materials having different coefficients of thermal expansion, are used, the effects of mutual thermal expansion or thermal contraction due to the environmental temperature can be released in the gap with a margin. It does not cause distortion at the joint between the diaphragm and the bolt. The deformation of the diaphragm due to the distortion is prevented, and the output efficiency of the ultrasonic wave does not decrease.

Further, the female screw hole and the screw thread of the bolt are in a range in which they are entangled with each other, and the gap dimension between the female screw hole and the bolt is 0.3 mm or more.

[0010] With the above structure, the bolted Langevin type vibrator fixed to the bolt through the female screw hole does not fall off the diaphragm, and the gap size can be made three times or more of the conventional one. No distortion is caused at the joint portion with. Then, in order to prevent the deformation of the diaphragm due to the distortion, it is possible to suppress a decrease in the output efficiency of the ultrasonic wave.

Next, FIG. 3 shows a comparative example between the product of the present invention as shown in FIG. 2 and the conventional product as shown in FIG. FIG.
FIG. 4 is a graph showing the efficiency of ultrasonic output (sound pressure) with a change in environmental temperature when the bolted Langevin type vibrator of the related art and the present invention is attached to a diaphragm.

The graph used in the experiment to create this graph is shown below. Made of stainless steel with a diameter of 200
Two cylindrical containers having a thickness of 200 mm, a height of 200 mm, and a thickness of 1 mm on the bottom surface were prepared. The center of the bottom of each cylindrical container is SUS
Are welded, and the bolted Langevin type vibrator (gap size 0.3 mm) of the present invention and the conventional bolted Langevin type vibrator (gap size 0.1 mm) are bolted to each cylindrical container. It is attached via epoxy resin. Then, 5 liters of water was put into each of the cylindrical containers, and the ultrasonic output transmitted to the water was measured at the center of the water using a sound probe. In addition, the peak of the sound wave output near normal temperature was set to 100%.

FIG. 3 shows that there is no difference near normal temperature, but the sound wave output tends to decrease in comparison with the present invention as compared with the present invention as the temperature changes to the low temperature side or the high temperature side.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail with reference to the drawings. Since the basic configuration is the same as that shown in FIG. 1, FIG. 1 will be referred to, and the features of the present invention will be described with reference to FIG. FIG. 2 is a partial sectional view showing an embodiment of the present invention.

The bolted Langevin type vibrator is composed of a front mass 2, an electrode plate 4b, a piezoelectric element 3b, an electrode plate 4a, a piezoelectric element 3a, and a rear mass 1 in order from the ultrasonic wave emitting surface, and includes a stud bolt 5 and a nut. 6, it is fastened and fixed. The front mass 2 is made of an aluminum alloy metal block, has a truncated cone shape, and is provided with a female screw portion 21a in the center portion of which a stud bolt 5 is partially screwed. Each of the electrode plates 4a and 4b has a configuration in which a convex lead portion for external connection is provided in a ring shape, and nickel, stainless steel, beryllium copper, or the like is used as the material. The piezoelectric elements 3a and 3b are made of piezoelectric ceramics such as PZT (lead zirconate titanate), and have an annular cylindrical shape having a through hole in the center. The rear mass 1 is made of a metal block of SUS or aluminum alloy,
It has an annular cylindrical shape with a through hole provided in the center.

The bolted Langevin type vibrator constructed as described above is incorporated in an ultrasonic cleaning device and attached to the vibrating plate 7 (vibrating portion) of the cleaning tank. A bolt 8B (made of SUS or the like) for attaching a bolted Langevin type vibrator is welded to the diaphragm 7, and the bolt 8B has a triangular cross section and a height of about 1 mm.
mm thread is formed. The front mass 2 of the bolted Langevin type vibrator is provided with a female screw portion 22b configured to be screwed to the bolt 8B. The male screw portion has a triangular cross section and a depth of about 1 mm.
Are formed. Then, as shown in FIG. 2, the gap dimension W when the bolt and the female screw were screwed to each other was formed to be, for example, 0.3 mm.
A bonding material S made of an epoxy resin is interposed between the female screw portion and the radiation surface of the front mass, and after the female screw portion 22b is screwed into the bolt 8B, the bonding material is hardened, so that the bolted Langevin type vibration is obtained. The element and the diaphragm are integrally attached.

The gap dimension W may be 0.3 mm or more, but it is necessary that the gap dimension is within a range in which the threads are entangled with each other, and the thread shape (screw shape) of the first embodiment of the present invention is not limited. Groove shape) and thread height (thread groove depth), unless the gap dimension W is within 1 mm
Care must be taken in designing since the female screw portion 22b falls off the bolt 8B. In addition, the thread height (thread groove depth) is set to 1 mm in the present invention, but may be increased or decreased depending on the application.
It goes without saying that the gap size W also needs to be changed according to the size of the screw thread (screw groove).

Further, the present invention is not limited to the bolt shape and the female screw portion shape of the first embodiment of the present invention, and may have a square cross section as shown in FIG. 4 (a partial cross section showing another embodiment of the present invention). It can also be applied to shapes and the like. This shape has an advantage that the cap can be easily formed.

In the embodiment of the present invention, a female screw portion 21a for a stud bolt for integrating the bolted Langevin type vibrator main body and a female screw portion 22b for a bolt to be attached to the diaphragm are separately provided on the front mass 2. However, as shown in FIG. 5 (a partial sectional view showing another embodiment of the present invention), these may be integrally formed into a female screw portion 23b.

[0020]

According to the first aspect of the present invention, even if a front mass and a bolt, which are materials having different coefficients of thermal expansion, are used, the influence of mutual thermal expansion or thermal shrinkage due to the environmental temperature can be reduced within the gap having a margin. At the joint between the diaphragm and the bolt. The deformation of the diaphragm due to the distortion is prevented, and the output efficiency of the ultrasonic wave does not decrease. It is possible to provide a more reliable bolted Langevin type vibrator capable of obtaining a more stable ultrasonic output.

According to the second aspect, the bolted Langevin type vibrator fixed to the bolt through the female screw hole does not fall off the diaphragm, and the gap size is reduced to the conventional value.
Since it can be twice or more, distortion does not occur at the joint portion between the diaphragm and the bolt. The deformation of the diaphragm due to the distortion is prevented, and the output efficiency of the ultrasonic wave does not decrease. It is possible to provide a more reliable bolted Langevin type vibrator capable of obtaining a more stable ultrasonic output.

[Brief description of the drawings]

FIG. 1 is a schematic exploded perspective view showing a state in which a bolted Langevin type vibrator is attached to a diaphragm.

FIG. 2 is a partial sectional view showing an embodiment of the present invention.

FIG. 3 is a characteristic diagram comparing the present invention with a conventional one.

FIG. 4 is a partial sectional view showing another embodiment of the present invention.

FIG. 5 is a partial sectional view showing another embodiment of the present invention.

FIG. 6 is a partial sectional view showing a conventional example.

FIG. 7 is a plan view schematically showing a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rear mass 2 ... Front mass 3a, 3b ... Electrode plate 4a, 4b ... Piezoelectric ceramic 5 ... Stud bolt 6 ... Nut 7 ... Diaphragm 8A, 8B ... bolt

Claims (2)

[Claims] 1. A front mass made of a metal block,
A bolted Langevin type comprising a rear mass also made of a metal block, at least one piezoelectric element and an electrode plate arranged between the front mass and the rear mass, and a bolt which penetrates and fixes a central portion of each of these components. There is a vibrator, and a female screw hole is provided in a front mass of the bolted Langevin type vibrator, and the female screw hole is screwed to a bolt welded to the diaphragm via a bonding material and attached to the female screw hole. A bolted Langevin type vibrator, wherein the gap between the female screw hole and the bolt has a margin, and the joining material is stored in the gap between the female screw hole and the bolt. 2. The method according to claim 1, wherein the female screw hole and the screw thread of the bolt are in a range in which the screw threads of the female screw hole are entangled with each other, and the gap dimension between the female screw hole and the bolt is 0.3 mm or more. Bolted Langevin type vibrator.