Transducer unit and ultrasonic vacuum cleaning machine

Abstract

The purpose of the present disclosure is to provide a vibrator unit in which ultrasonic vibrators can be prevented from being broken. A vibrator unit 11 according to the present invention comprises a dish-shaped diaphragm 21 and ultrasonic vibrators 30 and emits ultrasonic waves from an emitting surface 34 of a front plate of the ultrasonic vibrators 30. The dish-shaped diaphragm 21 comprises a bottom portion 22 having a first convex surface 22a on the outer side, a side portion 23 extending in the vertical direction, and a connecting portion 24 having a second convex surface 24a on the outer side. The ultrasonic vibrators 30 each have a structure in which a drive unit is sandwiched between the front plate and a backing plate and fixed with a bolt, and the front plate is attached to the first convex surface 22a. The diameter of the emitting surface 34 is 1 / 4 or more of a wavelength λ of the drive frequency of the ultrasonic vibrator 30. The backing plate is fastened and fixed by threadingly fitting a nut 40 to a protruding portion of the bolt inserted through the backing plate. The backing plate and the nut 40 are formed by using a metal material having a higher rigidity than a metal material that forms the front plate. Selected drawing: FIG. 1.

Description

Technical Field

[0005]

[0001] The present invention relates to a vibrator unit that irradiates ultrasonic waves from an ultrasonic vibrator, and an ultrasonic decompression cleaning machine using the same.

Background Art

[0002] Conventionally, an ultrasonic cleaning machine that performs cleaning (ultrasonic cleaning) of an object to be cleaned by irradiating ultrasonic waves into a cleaning liquid has been put into practical use (see, for example, Patent Document 1). Ultrasonic cleaning can act on the details of an object to be cleaned having a complex shape and can be efficiently cleaned by a combination of the physical action of ultrasonic waves and the chemical action of the cleaning liquid. Therefore, it has become indispensable in the manufacture of precision mechanical parts, optical parts, liquid crystal displays, semiconductors, and the like.

[0003] In addition, the ultrasonic cleaning machine described in Patent Document 1 includes a dish-shaped diaphragm also called a radiation plate. The dish-shaped diaphragm also serves as the bottom of a cleaning tank in which a cleaning liquid is stored, and a plurality of ultrasonic vibrators are attached to the outer surface (convex surface). The ultrasonic vibrators are joined to the dish-shaped diaphragm using an adhesive such as an epoxy resin-based adhesive or a stud bolt. The ultrasonic waves irradiated from each ultrasonic vibrator are radiated from the inner surface (concave surface) of the dish-shaped diaphragm and concentrated on the central portion in the cleaning tank.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a transducer unit and an ultrasonic vacuum cleaning machine that can prevent damage to an ultrasonic transducer. [Means for solving the problem]

[0007] To solve the above problems, the invention described in claim 1 comprises a bottom portion having a first convex surface with constant curvature on its outward side, a side portion extending in the vertical direction, and a connecting portion having a second convex surface with greater curvature than the first convex surface on its outward side, which connects the bottom portion and the side portion. It is attached to the cleaning tank body that makes up the cleaning tank of an ultrasonic cleaning machine. It has a disc-shaped diaphragm and a structure in which the drive unit is sandwiched between the front plate and the backing plate and fixed with bolts, and the front plate is Avoiding the aforementioned side portion and the second convex surface The first convex surface only It comprises multiple bolt-fastened Langevin-type ultrasonic transducers that can be attached, and from the radiating surface of the front plate Towards the washing tank under reduced pressure A transducer unit that emits ultrasonic waves. A flange is formed to protrude from the upper end of the side portion in a direction perpendicular to the side portion, and the lower end of the washing tank body is joined to the upper surface of the flange. The gist of this transducer unit is that the diameter of the radiating surface is at least 1 / 4 of the wavelength λ of the driving frequency of the ultrasonic transducer, the backing plate is tightened and fixed by screwing a nut onto the protruding portion of the bolt through which the backing plate is inserted, and the backing plate and the nut are made of a metal material with higher rigidity than the metal material constituting the front plate.

[0008] Accordingly, according to the invention described in claim 1, since the backing plate and nut of the ultrasonic transducer are formed using a metal material with higher rigidity than the metal material constituting the front plate of the ultrasonic transducer, the bending rigidity of the backing plate can be increased by tightening and fixing the backing plate with a nut. Consequently, the bending vibration component of the backing plate is reduced, and the bending displacement of the backing plate is also reduced. As a result, the stress due to the bending vibration component is less likely to act on the drive part of the ultrasonic transducer, thus preventing damage to the ultrasonic transducer.

[0009] Furthermore, because the ultrasonic transducer is less prone to damage, an ultrasonic transducer that is easily affected by the vibration modes of the dish-shaped diaphragm, specifically an ultrasonic transducer whose radiating surface diameter is 1 / 4 or more of the wavelength λ, can be used as the ultrasonic transducer described in claim 1. Since this ultrasonic transducer has a relatively large diameter, it is possible to reduce the number of ultrasonic transducers that can be attached to the first convex surface of the dish-shaped diaphragm. Therefore, the manufacturing cost of the transducer unit can be reduced.

[0010] The invention described in claim 2 is characterized in that, in claim 1, the radiating surface is a concave surface having the same curvature as the first convex surface, and the concave surface is joined to the first convex surface via an adhesive layer of uniform thickness.

[0011] Therefore, according to the invention described in claim 2, the distance from the first convex surface of the dish-shaped diaphragm is constant at any point on the radiating surface (concave surface) of the ultrasonic transducer, making it possible to uniformly transmit ultrasonic waves irradiated from the radiating surface. Furthermore, since the radiating surface and the first convex surface are joined via an adhesive layer of uniform thickness, it is easier to impart high bonding strength between them.

[0012] The invention described in claim 3 is characterized in that, in claim 1 or 2, a stud bolt is provided protruding from the first convex surface, a bolt hole opening on the radiating surface is provided in the front plate, and the ultrasonic transducer is attached to the dish-shaped diaphragm by screwing the stud bolt into the bolt hole.

[0013] Therefore, according to the invention described in claim 3, the mounting strength of the ultrasonic transducer is increased by screwing the stud bolts protruding from the first convex surface of the dish-shaped diaphragm into the bolt holes of the ultrasonic transducer. As a result, the ultrasonic transducer can be securely attached to the dish-shaped diaphragm.

[0014] The invention described in claim 4 is characterized in that, in any one of claims 1 to 3, the plurality of ultrasonic transducers are divided into a plurality of groups, and each of the groups has an electrical wiring system.

[0015] Therefore, according to the invention described in claim 4, it is not necessary to drive all ultrasonic transducers using a single electrical wiring system, thus reducing the load on the electrical wiring system. Furthermore, since ultrasonic transducers can be driven in groups, ultrasonic waves can be irradiated in various ways.

[0016] The invention described in claim 5 is a transducer unit that irradiates ultrasonic waves into the cleaning tank in a reduced pressure state from the radiating surface of the front plate at a driving frequency of 40 kHz or higher, wherein a flange is formed to protrude from the upper end of the side portion in a direction perpendicular to the side portion, and the upper end of the side portion has a first convex surface with a constant curvature on its outer side, the side portion has a second convex surface with a greater curvature than the first convex surface on its outer side, and the transducer unit that irradiates ultrasonic waves into the cleaning tank in a reduced pressure state from the radiating surface of the front plate at a driving frequency of 40 kHz or higher, wherein a flange is formed to protrude in a direction perpendicular to the side portion at the upper end of the side portion. The gist of this transducer unit is that the lower end of the cleaning tank body is joined to the upper surface of the flange, the diameter of the radiating surface is greater than 1 / 4 of the wavelength λ of the driving frequency of the ultrasonic transducer and greater than the diameter of the backing plate, the backing plate is tightened and fixed by screwing a nut onto the protruding portion of the bolt through which the backing plate is inserted, the thickness of the front plate is equal to the sum of the thicknesses of the drive unit, the backing plate and the bolt, the metal material constituting the front plate is an aluminum alloy, and the backing plate, the bolt and the nut are formed using a metal material whose bending stiffness, derived as the product of Young's modulus and the second moment of area, is 2.7 times or more that of the metal material constituting the front plate.

[0018] The invention described in claim 6 comprises a cleaning tank comprising a vibrator unit according to any one of claims 1 to 5 and a cleaning tank body joined to the upper side of the dish-shaped diaphragm. Ta The gist of this invention is an ultrasonic vacuum cleaning machine characterized by the following features.

[0019] Therefore, according to the invention described in claim 6, since the back plate and nut of the ultrasonic vibrator are formed using a metal material with higher rigidity than the metal material constituting the front plate of the ultrasonic vibrator, by tightening and fixing the back plate with the nut, the bending rigidity of the back plate can be increased. Along with this, since the bending vibration component of the back plate is reduced, the bending displacement of the back plate also becomes smaller. As a result, it becomes difficult for the stress due to the bending vibration component to act on the drive part of the ultrasonic vibrator, so damage to the ultrasonic vibrator can be prevented. Therefore, by using this ultrasonic vibrator in the vibrator unit, the durability of the ultrasonic decompression cleaning machine can be improved. Furthermore, since the ultrasonic vibrator is less likely to be damaged, even if the inside of the cleaning tank is decompressed and the bending displacement of the dish-shaped diaphragm becomes large, ultrasonic waves can be reliably irradiated from the radiation surface of the ultrasonic vibrator into the cleaning tank, and thus precise cleaning of the object to be cleaned can be reliably performed.

[0020] Also, since the ultrasonic vibrator is less likely to be damaged, an ultrasonic vibrator that is easily affected by the vibration mode of the dish-shaped diaphragm, specifically, an ultrasonic vibrator whose radiation surface diameter is 1 / 4 or more of the wavelength λ, can be adopted as the ultrasonic vibrator described in claim 6. Since this ultrasonic vibrator has a relatively large diameter, it is possible to reduce the number of ultrasonic vibrators attached to the first convex surface of the dish-shaped diaphragm. Therefore, the manufacturing cost of the ultrasonic decompression cleaning machine can be reduced.

Effects of the Invention

[0021] As described in detail above, according to the inventions described in claims 1 to 6, damage to the ultrasonic vibrator can be prevented.

Brief Description of the Drawings

[0022] [Figure 1] Schematic configuration diagram showing the ultrasonic decompression cleaning machine in this embodiment. [Figure 2] Bottom view showing the vibrator unit. [Figure 3] Perspective view showing a bolt-tightened Langevin-type ultrasonic vibrator. [Figure 4] Cross-sectional view taken along line A-A of FIG. 3. [Figure 5] Cross-sectional view of the main part showing the connection structure of the ultrasonic vibrator to the dish-shaped diaphragm. [Figure 6] Schematic bottom view showing the arrangement pattern of the groups in other embodiments. [Figure 7] Schematic bottom view showing the arrangement pattern of the groups in other embodiments.

BEST MODE FOR CARRYING OUT THE INVENTION

[0023] Hereinafter, an embodiment in which the present invention is embodied in an ultrasonic decompression cleaning machine will be described in detail based on the drawings.

[0024] As shown in FIG. 1, the ultrasonic decompression cleaning machine 1 includes a cleaning tank 10 composed of a vibrator unit 11 and a cleaning tank body 12. A cleaning liquid W1 is stored in the cleaning tank 10. The vibrator unit 11 includes a dish-shaped diaphragm 21 and a plurality (108 in this embodiment) of ultrasonic vibrators 30 joined to the dish-shaped diaphragm 21. The ultrasonic decompression cleaning machine 1 of this embodiment is a device that cleans the object to be cleaned 13 accommodated in the cleaning tank 10 by irradiating ultrasonic waves from each ultrasonic vibrator 30 to the cleaning liquid W1 in the cleaning tank 10 in a decompressed state where the inside of the cleaning tank 10 is decompressed. Note that the ultrasonic decompression cleaning machine 1 can also clean the object to be cleaned 13 in a normal pressure state where the inside of the cleaning tank 10 is not decompressed or in a pressurized state where the inside of the cleaning tank 10 is pressurized.

[0025] As shown in FIGS. 1 and 2, the dish-shaped diaphragm 21 forms the bottom of the cleaning tank 10 and is made of a metal plate (a stainless steel plate made of SUS304 or the like in this embodiment). The dish-shaped diaphragm 21 includes a bottom portion 22, side portions 23 extending in the vertical direction, and a connecting portion 24 connecting the bottom portion 22 and the side portions 23. The bottom portion 22 has a first convex surface 22a with a constant curvature on the outside, and the connecting portion 24 has a second convex surface 24a with a larger curvature than the first convex surface 22a on the outside.

[0026] Furthermore, a discharge pipe 25 for discharging the cleaning fluid W1 is provided in the center of the bottom portion 22. The discharge pipe 25 protrudes downward from the first convex surface 22a and connects the inside and outside of the dish-shaped vibrating plate 21. In addition, a flange 26 is formed on the entire upper end of the side portion 23, and the flange 26 is provided with a plurality of screw holes 27 (see Figure 2). Each screw hole 27 is arranged at equal angular intervals with respect to the central axis C1 of the dish-shaped vibrating plate 21 (see Figures 1 and 2). Then, by inserting a screw (not shown) through each screw hole 27 and screwing the tip of each inserted screw into the lower end of the cleaning tank body 12, the cleaning tank body 12 is joined onto the flange 26 of the dish-shaped vibrating plate 21.

[0027] As shown in Figures 3 and 4, the ultrasonic transducer 30 of this embodiment is a bolted Langevin-type transducer, and is attached at multiple points on the bottom 22 of the dish-shaped diaphragm 21. The ultrasonic transducer 30 is composed of a front mass 31 (front plate), a back mass 32 (backing plate), a drive unit 41, and bolts 33.

[0028] The front mass 31 is positioned at the front end of the ultrasonic transducer 30 and emits ultrasonic waves from a radiating surface 34 on its front surface. In this embodiment, the front mass 31 is formed in a circular cross-section. The radiating surface 34 is a concave surface having the same curvature as the first convex surface 22a of the dish-shaped diaphragm 21. Furthermore, as shown in Figure 5, a plurality of stud bolts 28 are provided protruding from the first convex surface 22a. On the other hand, the front mass 31 is provided with bolt holes 35 that open at the radiating surface 34. The ultrasonic transducer 30 is attached to the dish-shaped diaphragm 21 by screwing the stud bolts 28 into the bolt holes 35. Furthermore, the concave surface (radiating surface 34) is joined to the first convex surface 22a via an adhesive layer 36 of uniform thickness (epoxy adhesive in this embodiment).

[0029] As shown in Figures 3 and 4, the back mass 32 is located at the rear end of the ultrasonic transducer 30. The drive unit 41 is made up of two piezoelectric elements 42 and two electrode plates 43 stacked alternately and is sandwiched between the front mass 31 and the back mass 32. Since the piezoelectric elements 42 are annular and the electrode plates 43 are substantially annular with tab portions in part, the drive unit 41 has a bolt insertion hole 44 that penetrates its own center. Each piezoelectric element 42 is polarized in the thickness direction.

[0030] Furthermore, a female screw hole 37 is formed in the front mass 31 coaxially with the central axis C2 of the ultrasonic transducer 30. The female screw hole 37 communicates with a bolt hole 35 and a bolt insertion hole 44. On the other hand, a through hole 38 is formed in the back mass 32 coaxially with the central axis C2. The through hole 38 communicates with a bolt insertion hole 44 and opens on the rear surface 39. A bolt 33 with male threads formed on its outer circumference is inserted from the back mass 32 side, and its tip reaches the female screw hole 37 on the front mass 31 side via the through hole 38 and the bolt insertion hole 44. The bolt 33 is screwed into the female screw hole 37. Then, by screwing a nut 40 onto the protruding portion of the bolt 33 that has been inserted through the back mass 32, the front mass 31, the drive unit 41 and the back mass 32 are tightened and fixed together to form a single unit.

[0031] In this embodiment, the ultrasonic transducer 30 has a front mass 31 made of aluminum alloy (A5056). On the other hand, the back mass 32 and the nut 40 are made of a metal material with higher rigidity than the metal material (aluminum alloy) that constitutes the front mass 31. In this embodiment, the back mass 32 is made of stainless steel (SUS304) and the nut 40 is made of iron (S25C). The metal material used to form the bolt 33 is arbitrary, but stainless steel is used here.

[0032] Furthermore, in the ultrasonic transducer 30 of this embodiment, the piezoelectric element 42 constituting the drive unit 41 is formed using a lead-free ceramic piezoelectric material, specifically, an alkali niobate-based ceramic piezoelectric material. A suitable example of an alkali niobate-based ceramic piezoelectric material is a potassium-sodium niobate-based (KNN) ceramic piezoelectric material, which is a solid solution of potassium niobate and sodium niobate having a perovskite structure. The piezoelectric element 42 may also be formed using a ceramic piezoelectric material containing Pb (lead), such as lead zirconate titanate (PZT).

[0033] As shown in Figures 3 and 4, the ultrasonic transducer 30 of this embodiment is formed such that the resonant frequency (driving frequency) is 40 kHz and the diameter D1 of the radiating surface 34 is 45 mm. That is, the diameter D1 of the radiating surface 34 is set to be at least 1 / 4 of the wavelength λ of the resonant frequency (= 38 mm or more).

[0034] Furthermore, the tab portion of the electrode plate 43 of each ultrasonic transducer 30 is electrically connected to a wire (not shown). These wires are led out to the outside of the ultrasonic vacuum cleaning machine 1 via a cable (not shown) and are electrically connected to a drive control device and a power supply device (both not shown), which include an oscillator. Also, as shown in Figure 2, each ultrasonic transducer 30 is divided into four groups A to D. Each group A to D has the same number of ultrasonic transducers 30 (27 in this embodiment). In this embodiment, each group A to D is provided with a separate electrical wiring system (i.e., cable, drive control device, and power supply device).

[0035] In this ultrasonic vacuum cleaning machine 1, each group A to D of ultrasonic transducers 30 is simultaneously driven based on a drive signal from the drive control device and begins to vibrate. The ultrasonic waves emitted from the radiating surface 34 of each ultrasonic transducer 30 are then emitted into the cleaning liquid W1 from the inner surface (concave surface) of the dish-shaped vibrating plate 21 and concentrated in the central part of the cleaning tank 10. At this time, bubbles are generated in the cleaning liquid W1 by the concentrated ultrasonic waves, and the object to be cleaned 13 is cleaned by the impact of the bubbles bursting.

[0036] Next, we will explain the evaluation method and results for the oscillator unit.

[0037] First, the measurement samples were prepared as follows. A transducer unit identical to the transducer unit 11 of this embodiment was prepared and designated as the example. In addition, several ultrasonic transducers were prepared in which the back mass 32 and nut 40 of this embodiment were replaced with back masses (backing plates) made of aluminum alloy. A transducer unit was prepared by attaching these multiple ultrasonic transducers to a dish-shaped diaphragm 21 and designated as the comparative example.

[0038] Next, the vibration modes of each measurement sample (example and comparative example) under reduced pressure were analyzed. Specifically, a reduced pressure state was assumed in which the inside of the dish-shaped diaphragm was reduced by 100 kPa. Note that since many bubbles are generated on the inner surface of the dish-shaped diaphragm under reduced pressure, the reduced pressure state was analyzed as an air load ρc (= 400 [Pa·s / m]). Then, under reduced pressure, the vibration modes were analyzed when ultrasound with a frequency of 34 kHz and an output of 4.8 kW was irradiated into the dish-shaped diaphragm from each ultrasonic transducer.

[0039] As a result, in the comparative example where the ultrasonic transducer had an aluminum alloy back mass, it was confirmed that a dominant (large) vibration mode of bending vibration, which causes cracking of the ceramic element (cracking of the drive unit), was generated in the dish-shaped diaphragm. Consequently, it was confirmed that the end face (radiating surface) of the ultrasonic transducer was displaced obliquely, and that a longitudinal-bending combined vibration mode was excited in the ultrasonic transducer. Furthermore, it was confirmed that the stress due to the bending vibration component was concentrated in the outer periphery of the drive unit. On the other hand, in the example where the ultrasonic transducer had a stainless steel back mass and an iron nut, it was confirmed that the bending vibration component was significantly reduced compared to the comparative example.

[0040] From the above, it has been proven that changing the aluminum alloy back mass (comparative example) of the ultrasonic transducer to a stainless steel back mass and an iron nut increases the bending stiffness EI (resistance to bending deformation) of the material and reduces the bending vibration component. The bending stiffness EI is derived from the formula (Young's modulus E) × (second moment of area I). ​​For example, if the cross-sectional shape is the same, changing the material from aluminum alloy (A5056, Young's modulus E=71GPa) to stainless steel (SUS304, Young's modulus E=190GPa) increases the bending stiffness EI by approximately 2.7 times. Furthermore, since the bending vibration component is reduced, it is considered that stress caused by the bending vibration component can be prevented from destroying the drive unit.

[0041] Furthermore, the diameter D1 of the radiating surface of the ultrasonic transducer in the embodiment was 45 mm, which was confirmed to exceed the limit dimension λ / 4 = 38 mm for uniform longitudinal vibration by the ultrasonic transducer alone at a driving frequency of 34 kHz. For this reason, it is considered that the vibration mode of the ultrasonic transducer in the embodiment is easily influenced by the vibration mode of the connected dish-shaped diaphragm.

[0042] Therefore, according to this embodiment, the following effects can be obtained.

[0043] (1) In the ultrasonic vacuum cleaning machine 1 of this embodiment, the back mass 32 and nut 40 of the ultrasonic transducer 30 are made of a metal material (stainless steel, iron) that has higher rigidity than the metal material (aluminum alloy) that constitutes the front mass 31 of the ultrasonic transducer 30. Therefore, by tightening and fixing the back mass 32 with the nut 40, the bending rigidity EI of the back mass 32 can be increased. Accordingly, the bending vibration component of the back mass 32 is reduced, and the bending displacement of the back mass 32 is also reduced. As a result, the stress due to the bending vibration component is less likely to act on the drive unit 41 of the ultrasonic transducer 30, so damage to the ultrasonic transducer 30 can be prevented. Therefore, by using this ultrasonic transducer 30 in the transducer unit 11, the durability of the ultrasonic vacuum cleaning machine 1 can be improved. Furthermore, because the ultrasonic transducer 30 is less likely to be damaged, even if the pressure inside the cleaning tank 10 is reduced and the bending displacement of the dish-shaped vibrator 21 increases, ultrasonic waves can be reliably irradiated into the cleaning tank 10 from the radiating surface 34 of the ultrasonic transducer 30. Therefore, precise cleaning of the object to be cleaned 13 can be reliably performed.

[0044] Furthermore, because the ultrasonic transducer 30 is less prone to damage, an ultrasonic transducer that is easily affected by the vibration mode of the dish-shaped diaphragm 21, specifically an ultrasonic transducer whose radiating surface 34 diameter D1 is 1 / 4 or more of the wavelength λ (38 mm or more in this embodiment), can be used as the ultrasonic transducer 30 in this embodiment. Since this ultrasonic transducer 30 has a relatively large diameter D1, it is possible to reduce the number of ultrasonic transducers 30 attached to the first convex surface 22a of the dish-shaped diaphragm 21. Therefore, the manufacturing cost of the ultrasonic vacuum cleaning machine 1 can be reduced.

[0045] (2) Generally, bolt-tightened ultrasonic transducers are used for vacuum cleaning, with a radiating surface diameter of 1 / 4 or less of the wavelength λ and a drive frequency of 28 kHz. However, due to the low frequency, precise cleaning of the object to be cleaned 13 is not possible. On the other hand, the ultrasonic vacuum cleaning machine 1 of this embodiment uses an ultrasonic transducer 30 with a drive frequency of 40 kHz. As a result, precise cleaning of the object to be cleaned 13 can be performed in a short time, thus reducing power consumption. Furthermore, by using the ultrasonic vacuum cleaning machine 1, a powerful cleaning effect can be obtained, thus reducing the amount of cleaning agent contained in the cleaning solution W1 used. In this case, running costs such as the cost of cleaning agent and its disposal costs can be reduced, and the environmental burden can also be reduced.

[0046] (3) In this embodiment, the radiating surface 34 of the front mass 31 of the ultrasonic transducer 30 is joined to the first convex surface 22a of the dish-shaped diaphragm 21 via the adhesive layer 36, thereby increasing the mounting strength of the ultrasonic transducer 30. Furthermore, the mounting strength of the ultrasonic transducer 30 is further increased by screwing the stud bolts 28 protruding from the first convex surface 22a into the bolt holes 35 of the front mass 31. As a result, the ultrasonic transducer 30 can be securely attached to the dish-shaped diaphragm 21.

[0047] (4) In the ultrasonic transducer 30 of this embodiment, with the back mass 32 mounted on the drive unit 41, the front mass 31, drive unit 41, and back mass 32 are tightened and fixed together by screwing a nut 40 onto a bolt 33 that is screwed onto the front mass 31 and through which the drive unit 41 and back mass 32 are inserted. Since there is no thread (female thread) formed in the through hole 38 of the back mass 32, the back mass 32 does not move easily when tightened. Therefore, the back mass 32 can be positioned with high precision. In addition, damage to the drive unit 41 caused by the movement (tilting) of the back mass 32 when tightened can be prevented.

[0048] The above embodiment may be modified as follows.

[0049] In the ultrasonic vacuum cleaning machine 1 of the above embodiment, an ultrasonic transducer 30 was used with a driving frequency of 40 kHz and a radiating surface diameter D1 of 45 mm. However, it is possible to change to another ultrasonic transducer as long as the diameter D1 satisfies the relationship that it is 1 / 4 or more of the wavelength λ (38 mm or more in the case of 40 kHz). For example, the ultrasonic transducer 30 may be changed to an ultrasonic transducer with a driving frequency of 40 kHz and a radiating surface diameter of 38 mm.

[0050] In the above embodiment, the front mass 31 was formed using an aluminum alloy (A5056, Young's modulus 71 GPa), the back mass 32 was formed using stainless steel (SUS304, Young's modulus 190 GPa), and the nut 40 was formed using iron (S25C, Young's modulus 205-206 GPa), but it is not limited to this. For example, if the front mass 31 is formed using an aluminum alloy, the back mass 32 and nut 40 may be formed using other metal materials with higher rigidity than aluminum alloy, specifically copper alloys such as copper (Young's modulus 117 GPa) and brass (Young's modulus 103-110 GPa), steel materials such as carbon steel (Young's modulus 205 GPa) and nickel steel (Young's modulus 193 GPa), nickel (Young's modulus 204 GPa), titanium (Young's modulus 106 GPa), titanium alloy (Young's modulus 106 GPa), etc.

[0051] In the ultrasonic transducer 30 of the above embodiment, the radiating surface 34 of the front mass 31 was a concave surface having the same curvature as the first convex surface 22a of the dish-shaped diaphragm 21, but the radiating surface 34 may be a flat surface.

[0052] In the above embodiment, the multiple ultrasonic transducers 30 attached to the dish-shaped diaphragm 21 were divided into four groups A to D. However, each ultrasonic transducer 30 may be divided into five or more groups, or into three or fewer groups. Furthermore, each ultrasonic transducer 30 does not have to be divided into multiple groups. In this case, all ultrasonic transducers 30 are driven using a single electrical wiring system (cable, drive control device, and power supply).

[0053] In the above embodiment, each ultrasonic transducer 30 was divided into four groups A to D along the diameter direction (vertical direction in Figure 2) of the dish-shaped diaphragm 21, but the way the groups are divided may be changed. For example, as shown in Figure 6, each ultrasonic transducer 30 may be divided into multiple groups (groups A to D in Figure 6) arranged at equal angular intervals with respect to the central axis C1 of the dish-shaped diaphragm 21. Alternatively, as shown in Figure 7, each ultrasonic transducer 30 may be divided into multiple groups (groups A to D in Figure 7) arranged concentrically.

[0054] In the above embodiment, the flange 26 of the dish-shaped vibrating plate 21 and the lower end of the washing tank body 12 were connected by screws, but they may also be connected by welding.

[0055] Next, in addition to the technical ideas described in the claims, the technical ideas that can be grasped by the embodiments described above are listed below.

[0056] (1) The transducer unit according to any one of claims 1 to 5, wherein the drive unit is made up of a piezoelectric element and an electrode plate stacked on top of each other, and the ultrasonic transducer has a structure in which the front plate and the backing plate are fastened together by the bolts that pass through the drive unit.

[0057] (2) The vibrator unit according to any one of claims 1 to 5, characterized in that the backing plate and the nut are formed using a metal material that has higher rigidity than an aluminum alloy.

[0058] (3) The vibrator unit according to any one of claims 1 to 5, characterized in that the backing plate is made of stainless steel and the nut is made of iron. [Explanation of symbols]

[0059] 1… Ultrasonic vacuum cleaning machine 10…Washing tank 11…Oscillator unit 12…Washing tank body 21...Dish-shaped diaphragm 22...bottom 22a...first convex surface 23... Side 24...Connection part 24a…Second convex surface 26…Flange 28… Stud bolts 30… Ultrasonic transducer 31...Front mass as front panel 32...Back mass as a backing plate 33... Volts 34…Radial surface of the front panel 35… Bolt holes 36...adhesive layer 40... Nut 41…Drive unit A-D...Groups D1...Diameter of the radiating surface

Claims

1. A dish-shaped vibrating plate is attached to the cleaning tank body that constitutes the cleaning tank of an ultrasonic cleaning machine, comprising a bottom portion having a first convex surface with a constant curvature on its outward side, a side portion extending in the vertical direction, and a connecting portion having a second convex surface with a greater curvature than the first convex surface on its outward side and connecting the bottom portion and the side portion, The structure has a drive unit sandwiched between the front plate and the back plate and fixed with bolts, and the front plate is attached only to the first convex surface, avoiding the side and the second convex surface, and has multiple bolt-fastened Langevin-type ultrasonic transducers. A transducer unit comprising, which irradiates ultrasonic waves from the radiating surface of the front plate toward the inside of the cleaning tank under reduced pressure, A flange is formed to protrude from the upper end of the side portion in a direction perpendicular to the side portion, and the lower end of the washing tank body is joined to the upper surface of the flange. The diameter of the radiating surface is at least 1 / 4 of the wavelength λ of the driving frequency of the ultrasonic transducer. The backing plate is tightened and secured by screwing a nut onto the protruding portion of the bolt through which the backing plate is inserted. The backing plate and the nuts are formed using a metal material that has higher rigidity than the metal material that constitutes the front panel. A vibrator unit characterized by the following features.

2. The vibrator unit according to claim 1, characterized in that the radiating surface is a concave surface having the same curvature as the first convex surface, and the concave surface is bonded to the first convex surface via an adhesive layer of uniform thickness.

3. A stud bolt is provided protruding from the first convex surface, The front panel is provided with bolt holes that open on the radiating surface, The ultrasonic transducer is attached to the dish-shaped diaphragm by screwing the stud bolt into the bolt hole. The transducer unit according to feature 1 or 2.

4. The transducer unit according to any one of claims 1 to 3, characterized in that the plurality of ultrasonic transducers are divided into a plurality of groups, and each group has an electrical wiring system.

5. A dish-shaped vibrating plate attached to the cleaning tank body of an ultrasonic cleaning machine, comprising a bottom portion having a first convex surface with constant curvature on its outward side, a side portion extending in the vertical direction, and a connecting portion having a second convex surface with greater curvature than the first convex surface on its outward side and connecting the bottom portion and the side portion, The structure has a drive unit sandwiched between the front plate and the back plate and fixed with bolts, and the front plate is attached only to the first convex surface, avoiding the side and the second convex surface, and has multiple bolt-fastened Langevin-type ultrasonic transducers. A transducer unit comprising, which irradiates ultrasonic waves from the radiating surface of the front panel toward the inside of the cleaning tank under reduced pressure at a driving frequency of 40 kHz or higher, A flange is formed to protrude from the upper end of the side portion in a direction perpendicular to the side portion, and the lower end of the washing tank body is joined to the upper surface of the flange. The diameter of the radiating surface is greater than 1 / 4 of the wavelength λ of the driving frequency of the ultrasonic transducer and greater than the diameter of the backing plate. The backing plate is tightened and secured by screwing a nut onto the protruding portion of the bolt through which the backing plate is inserted. The thickness of the front panel is equal to the sum of the thicknesses of the drive unit, the backing plate, and the bolts. The metal material constituting the front panel is an aluminum alloy, and the backing plate, bolts, and nuts are formed using a metal material whose bending stiffness, derived as the product of Young's modulus and the second moment of area, is 2.7 times or more that of the metal material constituting the front panel. A vibrator unit characterized by the following features.

6. An ultrasonic vacuum cleaning machine characterized by comprising a cleaning tank comprising a transducer unit according to any one of claims 1 to 5 and a cleaning tank body joined to the upper side of the dish-shaped diaphragm.

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