JP2014168736A - Bolt fastening langevin type vibrator and ultrasonic welder using bolt fastening langevin type vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the first problem of providing a new method for enhancing a spurious resonance frequency by reducing a variation in a vibration state of a vibrator by preventing rupture of a piezoelectric element by uniformizing a load applied to the piezoelectric element of a bolt fastening Langevin type vibrator, and particularly, the second problem of providing the bolt fastening Langevin type vibrator for restraining heating of the piezoelectric element and an ultrasonic welder of using the bolt fastening Langevin type vibrator.SOLUTION: The bolt fastening Langevin type vibrator comprises a plurality of piezoelectric elements 4a and 4b having the electrostrictive effect, electrodes 5a and 5b inserted between the piezoelectric elements, a pair of metal blocks 3a and 3b for holding the piezoelectric elements and the electrodes and a bolt 2 for fastening the metal blocks, and conical concave surfaces A and B are formed on an end surface for abutting on at least one other part of the metal blocks, and the bolt is fastened, and is assembled by pressing the conical concave surfaces of the metal blocks to a surface of the piezoelectric elements or a surface of the electrodes.

Description

  The present invention relates to a bolt-clamped Langevin type vibrator and an ultrasonic welding apparatus using the bolt-clamped Langevin type vibrator, and more particularly, a bolt with improved pressing force (compression pressure) due to clamping generated at an interface between a metal block and a piezoelectric element. The present invention relates to an ultrasonic welding apparatus using a tightened Langevin type vibrator and a bolted Langevin type vibrator.

  Generally, a bolt-clamped Langevin-type transducer (BLT) includes a plurality of annular piezoelectric elements 14a and 14b having an electrostrictive effect as shown in FIG. 14b, annular electrodes 15a, 15b alternately stacked, a pair of cylindrical metal blocks 13a, 13b sandwiching the piezoelectric elements 14a, 14b and the electrodes 15a, 15b, and axes of the metal blocks 13a, 13b It is comprised from the volt | bolt 12 screwed together in the hole drilled in and fastening between both metal blocks 13a and 13b.

  When the pressing force (compression pressure) applied to the piezoelectric elements 14a and 14b varies, there is a problem that the quality of the Langevin vibrator is not stable. Further, when the pressing force is out of the predetermined range, the piezoelectric element may be destroyed in an extreme case. For this reason, the pressing force of the piezoelectric element by bolting has been strictly managed (for example, see Patent Document 1).

  In addition, as a method of making the load applied to the piezoelectric element uniform, preventing the piezoelectric element from being broken, reducing the variation in the vibration state of the vibrator, and increasing the spurious resonance frequency, one material of the metal block is set to a predetermined value or more. It has been proposed to use a material having a Young's modulus (see, for example, Patent Document 2).

Further, since there is a decrease in vibration efficiency when there is a gap in the contact portion between the piezoelectric element and each component, a method has been proposed in which an adhesive is applied to the contact portion to reduce the gap between the contact portions. (For example, refer to Patent Documents 3 and 4).
However, the conventional measures alone are not sufficient, although a certain effect can be expected. In particular, there has been a demand for new means effective in solving the problem of characteristic deterioration and destruction due to heat generation of the piezoelectric element.

  For example, when using bolted Langevin type vibrators at high frequencies, the entire length of the metal block may be shortened. However, if only the entire length of the metal block is shortened, tightening that occurs at the interface between the metal block and the piezoelectric element. It has been said that the compression pressure due to is significantly reduced especially at the outer peripheral portion, causing the characteristic deterioration and destruction of the bolted Langevin type vibrator due to heat generation.

Japanese Patent Laid-Open No. 2003-143697 JP-A-8-89893 JP 2005-278390 A JP-A-9-239318

  The present invention provides a new method for making a load applied to a piezoelectric element of a bolt-clamped Langevin type vibrator uniform, preventing destruction of the piezoelectric element, reducing variation in vibration state of the vibrator, and increasing a spurious resonance frequency. In particular, the second problem is to provide a bolt-clamped Langevin type vibrator that suppresses heat generation of the piezoelectric element and an ultrasonic welding apparatus using the bolt-clamped Langevin type vibrator. Yes.

  In the bolt-clamped Langevin type vibrator according to claim 1 of the present invention, a plurality of piezoelectric elements having an electrostrictive effect, electrodes alternately stacked with the piezoelectric elements, and a pair sandwiching the piezoelectric elements and the electrodes. In a bolted Langevin type vibrator having a metal block and a bolt for fastening the metal block, at least one of the facing surfaces of the pair of metal blocks has a conical shape centering on the axis of the bolt. The concave surface is formed, the bolt is tightened, and the conical concave surface of the metal block is pressed against the surface of the piezoelectric element or the surface of the electrode and assembled.

  With this configuration, when the bolt is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element, and an equal pressing force is applied. Alternatively, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the electrode, and an equal pressing force is applied. As described above, when equal pressing force is applied to the surface of the piezoelectric element and the surface of the electrode, respectively, the piezoelectric element and the electrode inside the surface of the piezoelectric element and the electrode can be applied with equal pressing force as compression pressure. . Therefore, destruction of the piezoelectric element can be prevented, variation in the vibration state of the vibrator is reduced, and the spurious resonance frequency can be increased.

In the bolt-clamped Langevin type vibrator according to the second aspect of the present invention, all of the end faces of the metal block having the concave surface are conical concave surfaces.
With this configuration, when the bolt is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element or electrode, and an equal pressing force can be applied as a compression pressure. it can.

In the bolt-clamped Langevin type vibrator according to claim 3 of the present invention, a part of each facing end surface of the metal block in which the concave surface is formed is a conical concave surface.
With this configuration, when the bolt is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element or electrode, and an almost uniform pressing force is applied as a compression pressure. Can do.

In the bolt-clamped Langevin type vibrator according to claim 4 of the present invention, the conical concave surface of the metal block is a conical surface having a linear cross section.
With this configuration, when the bolt is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element or electrode, and an almost uniform pressing force is applied as a compression pressure. Can do.

In the bolt-clamped Langevin type vibrator according to claim 5 of the present invention, a conical concave surface is used as an end surface in contact with another part of the metal block, and a conical surface having a curved cross section is used.
With this configuration, when the bolt is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element or electrode, and an almost uniform pressing force is applied as a compression pressure. Can do.

The ultrasonic welding apparatus using the bolt-clamped Langevin type vibrator according to claim 6 of the present invention uses any of the bolt-clamped Langevin type vibrators according to claims 1 to 5 described above.
With this configuration, an ultrasonic welding apparatus that suppresses heat generation of the piezoelectric element and maintains a stable oscillation state even when the ultrasonic welding cycle is repeated for a long time is realized.

  The present invention (1) makes the load applied to the piezoelectric element of the bolt-clamped Langevin type vibrator uniform, (2) prevents destruction of the piezoelectric element, (3) reduces variation in the vibration state of the vibrator, (4 ) The spurious resonance frequency can be increased. (5) There is an effect that it is possible to provide a bolted Langevin type vibrator that suppresses heat generation of the piezoelectric element and an ultrasonic welding apparatus using the bolted Langevin type vibrator.

Sectional drawing which showed the structure of the bolt fastening Langevin type vibrator | oscillator concerning 1st embodiment of this invention. 1 is an exploded cross-sectional view of a bolted Langevin type vibrator according to a first embodiment of the present invention. The figure which showed the inclination angle ((theta)) of the conical surface of the metal block of a bolt fastening Langevin type vibrator | oscillator concerning 1st embodiment of this invention, and a piezoelectric element. The graph which showed the situation of the stress of a piezoelectric element when changing the inclination-angle ((theta)) of a conical surface with the bolting Langevin type vibrator | oscillator concerning 1st embodiment of this invention, and showed it. The right view which made the cross section the part of ultrasonic welding apparatus using the bolt fastening Langevin type vibrator concerning a 1st embodiment of the present invention. The front view which showed the external appearance of the bolt fastening Langevin type vibrator concerning 2nd embodiment of this invention. Sectional drawing of the bolt fastening Langevin type vibrator | oscillator concerning 2nd embodiment of this invention. The graph which measured and showed the temperature rise condition when changing the inclination-angle ((theta)) of a conical surface with the bolt fastening Langevin type vibrator | oscillator concerning 2nd embodiment of this invention. The figure which showed the inclination angle ((theta)) of the conical surface of the metal block of a bolting Langevin type vibrator | oscillator concerning 3rd embodiment of this invention, and a piezoelectric element. The figure which showed the inclination angle ((theta)) of the conical surface of the metal block of a bolting Langevin type vibrator | oscillator concerning 4th embodiment of this invention, and a piezoelectric element. Sectional drawing which showed the structure of the conventional bolting Langevin type | mold vibrator.

(First embodiment of the present invention)
FIG. 1 is a cross-sectional view showing the configuration of a bolt-clamped Langevin type vibrator according to the first embodiment of the present invention. In FIG. 1, a bolted Langevin type vibrator (BLT) according to a first embodiment of the present invention includes a plurality of annular piezoelectric elements 4a and 4b having an electrostrictive effect, and alternating with the piezoelectric elements 4a and 4b. A pair of cylindrical metal blocks 3a and 3b sandwiching the piezoelectric elements 4a and 4b and the electrodes 5a and 5b, and the axial centers of the metal blocks 3a and 3b. It is comprised from the volt | bolt 2 which fastens between both metal blocks 3a and 3b by screwing in the hole made.

In the bolt-clamped Langevin type vibrator according to the first embodiment of the present invention, conical recesses centering on the axis of the bolt 2 are formed on the respective end faces of both the metal blocks 3a and 3b.
Specifically, the conical concave surface (A) of the metal block 3a is formed when one metal block 3a forms a conical concave surface (A) on the end surface that abuts the piezoelectric element 4a and the bolt 2 is tightened. Presses the surface of the piezoelectric element 4a. Further, when the other metal block 3b forms a conical concave surface (B) on the end surface where the metal block 3b comes into contact with the electrode 5b, and the bolt 2 is tightened, the conical concave surface (B) of the metal block 3b becomes the electrode 5b The surface is pressed.

  FIG. 2 shows an exploded cross-sectional view of the bolted Langevin type vibrator according to the first embodiment of the present invention. In FIGS. 1 and 2, the inclination angle is emphasized so that the conical concave surface (A) and the conical concave surface (B) of the metal block 3b can be easily understood on the end surface where the metal block 3a contacts the piezoelectric element 4a. However, the inclination angle of the conical slope is a very small angle. Therefore, when each component is arranged in the state of FIG. 2 and the bolt 2 is tightened as shown in FIG. 1, the conical concave surface (A) of the metal block 3a contacts the piezoelectric element 4a first from the outer peripheral portion. Then, the central portion around the bolt 2 to which a strong fastening force is applied comes into contact later, and finally the entire concave surface (A) is deformed so as to be in close contact with the surface of the piezoelectric element 4a, so that an equal pressing force is obtained. give. Similarly, the conical concave surface (B) of the metal block 3b comes into contact with the electrode 5b first from the outer peripheral portion, and the central portion around the bolt 2 to which a strong fastening force is applied comes into contact later. The entire concave surface (B) is deformed so as to be in close contact with the surface of the electrode 5b, and an equal pressing force is applied.

In the first embodiment, a simulation using the finite element method was performed by setting a plurality of angles for the inclination angles of the conical concave surfaces (A) and (B) of the metal blocks 3a and 3b.
FIG. 3 shows the inclination angle (θ) between the metal block of the bolt-clamped Langevin vibrator and the conical surface of the piezoelectric element according to the first embodiment of the present invention when a simulation using the finite element method is performed. Indicated. Since the shape of the bolted Langevin type vibrator to be analyzed is axially symmetric and vertically symmetrical, the analysis was performed only on a quarter of the entire bolted Langevin type vibrator. FIG. 3 is an enlarged cross section of one metal block 3a and the piezoelectric element 4a in the first embodiment. The piezoelectric element was made of piezoelectric ceramic, and the analysis was performed with the metal block made of duralumin.

FIG. 4 shows the simulation results using the finite element method of the stress (compressive stress) of the piezoelectric element according to the distance from the central axis (bolt 2 axis) when the inclination angle (θ) of the conical surface is changed. Indicated. The values of the inclination angle (θ) are 0 (rad), 1.0 × 10 ⁻³ (rad), 2.0 × 10 ⁻³ (rad), 2.2 × 10 ⁻³ (rad), 2. The case of 4 × 10 ⁻³ (rad), 2.6 × 10 ⁻³ (rad), and 2.8 × 10 ⁻³ (rad) was simulated. 4A and 4B, (1) the difference in the inclination angle (θ) of the conical surface greatly changes the distribution of the compression pressure (compression stress) applied to the contact interface between the metal block and the piezoelectric element. (2) It can be seen that there is an inclination angle at which the flattened compression pressure distribution is obtained.

In FIG. 4, when the inclination angle (θ) is 2.0 × 10 ⁻³ (rad) indicated by a thick solid line, the flattened compression pressure distribution, that is, the optimum value is obtained. From this, (1) the difference in the inclination angle (θ) of the conical surface greatly changes the distribution of the compression pressure applied to the contact interface between the metal block and the piezoelectric element. (2) The flattest compression pressure The conclusion was obtained that there is an inclination angle (optimum value) to be distributed.

  As described above, when equal pressing force is applied to the surface of the piezoelectric element 4a and the surface of the electrode 5b, the piezoelectric elements 4a and 4b and the electrodes 5a and 5b located on the inner side of the surface of the piezoelectric element 4a and the electrode 5b are equal. The pressing force is given as a compression pressure. Therefore, it is possible to prevent the piezoelectric element from being destroyed, to reduce the variation in the vibration state of the vibrator, and to increase the spurious resonance frequency.

  Then, a bolt-clamped Langevin type vibrator with a uniform load applied to the piezoelectric elements 4a and 4b is incorporated in a fixed horn, a booster horn and a tool horn are attached to the end of the fixed horn, and the bolt-clamped Langevin type vibrator is ultrasonically vibrated. Then, the tip of the tool horn vibrates with a predetermined frequency and amplitude. The workpiece can be ultrasonically welded by pressing the tip of a tool horn that vibrates ultrasonically against the surface of the plastic workpiece.

FIG. 5 is a right side view of the ultrasonic welding apparatus using the bolted Langevin type vibrator according to the first embodiment of the present invention, with a part thereof in cross section.
In FIG. 5, the fixed horn 6, the booster horn 7, and the tool horn 9 are assembled to the movable frame 35 in an integrated state. The fixed horn 6 incorporates the bolted Langevin type vibrator of the present invention. The movable frame 35 is attached to a lower end portion of a piston rod 38 of an air cylinder 37 as a press mechanism attached to the fixed frame 36 and is moved up and down by driving of the air cylinder 37 so as to weld the work 42 on the receiving jig 41. I have to. In FIG. 3, the tool horn 9 is located above the workpiece 42 and does not press the workpiece 42, but at the time of welding, the tool horn 9 that vibrates ultrasonically by driving the air cylinder 37 presses the workpiece 42 and presses the workpiece 42. 42 is welded.

  According to the ultrasonic welding apparatus using the bolted Langevin type vibrator according to the first embodiment of the present invention, the heat generated by the piezoelectric elements 4a and 4b is generated by making the load applied to the piezoelectric elements 4a and 4b uniform. Since it is suppressed to a low level, a stable oscillation state can be maintained even if the ultrasonic welding cycle is repeated for a long time.

  In the above description, the case where the conical concave surfaces (A) and (B) are provided on the metal blocks 3a and 3b has been described, but the conical concave surface is provided only on one of the metal blocks 3a and 3b. However, the effect of the present invention can be obtained by selecting the inclination angle of the conical concave surface according to the case.

(Second embodiment of the present invention)
FIG. 6 shows a front view showing the external appearance of a bolt tightening Langevin type vibrator according to the second embodiment of the present invention, and FIG. 7 shows a bolt tightening Langevin type according to the second embodiment of the present invention. A sectional view of a vibrator is shown.

  In the bolted Langevin type vibrator according to the second exemplary embodiment of the present invention, four annular electrodes 5a, 5b, 5c, 5d are alternately stacked on the four annular piezoelectric elements 4a, 4b, 4c, 4d, After passing the bolt 2 through the piezoelectric elements 4a, 4b, 4c and 4d and the electrodes 5a, 5b, 5c and 5d, the metal block 3a is screwed into one end of the bolt 2 and the metal block 3b is passed through the other end of the bolt 2. The nut 1 is screwed. The reason for using four piezoelectric elements is to increase the output and perform so-called strong ultrasonic welding.

In the bolt-clamped Langevin type vibrator according to the second embodiment of the present invention, conical recesses centering on the axis of the bolt 2 are formed on the end faces of the two metal blocks 3a and 3b. Yes.
Specifically, when one metal block 3a is formed with a conical concave surface (A) on the end surface in contact with the most piezoelectric element 4a and the bolt 2 is tightened, the conical shape of the metal block 3a is formed. The concave surface (A) presses the surface of the piezoelectric element 4a. Further, the conical concave surface (B) of the metal block 3b is formed when the conical concave surface (B) is formed on the end surface where the other metal block 3b is in contact with the electrode 5d on the other side and the bolt 2 is tightened. It is the same as the first embodiment of the present invention that presses the surface of the electrode 5d.

  6 and 7, the conical concave surface (A) of the metal block 3a and the conical concave surface (B) of the metal block 3b are shown with emphasis on the inclination angle so that they can be easily understood. Is a minute angle of about 0.02 ° to 0.06 °, and the conical concave surface (A) of the metal block 3a and the conical concave surface (B) of the metal block 3b are connected to the piezoelectric element 4a. It is the same as in the first embodiment of the present invention that the electrode 5d is deformed so as to be in close contact with the surface of the electrode 5d to give an equal pressing force.

  In producing the bolt-clamped Langevin type vibrator according to the second embodiment of the present invention, the applicant refers to the simulation result performed in the first embodiment, and the conical shape of the metal blocks 3a and 3b. The temperature rise situation by setting a plurality of inclination angles considered to be optimal for the inclination angle of the conical surfaces of the concave surfaces (A) and (B) of the bolts and operating the bolted Langevin type vibrator having the conical concave surfaces of the plural inclination angles Was measured to evaluate the optimum tilt angle as seen from the temperature rise. The contents will be described below. In addition, as a unit when setting a plurality of inclination angles in the second embodiment, a plurality of inclination angles are set in units of “° (degrees)” that are intuitively easy to understand instead of “rad (radian)”. .

  FIG. 8 shows the results of actual measurement of the temperature rise when the tilt angle (θ) of the conical surface is changed in the bolted Langevin type vibrator according to the second embodiment of the present invention. Here, a constant mechanical load was applied to the bolted Langevin type vibrator via a horn, the input voltage was constant at a predetermined voltage, and the state of heat generation was observed by continuous driving with natural cooling.

  In FIG. 8, the temperature of the surface (C) of the nut 1 is measured as shown in FIG. 6, and the vibrators 4a, 4b, 4c, 4d, electrodes 5a, 5b, 5c, 5d and metal blocks 3a, 3b. The overall temperature rise of was compared. The reason why the surface temperature of the nut 1 is measured is that the vibration operation of the ultrasonic vibration is not affected even if the measurement terminal of the thermometer is brought into contact with the surface of the nut 1 or a thermocouple is attached.

FIG. 8 shows each case where the value of the inclination angle (θ) is set to 0 °, 0.02 °, 0.04 °, and 0.06 °. In particular, 0.04 ° and 0.06 ° plotted a plurality of measurement values, and it was confirmed that the temperature measurement values were reproducible.
As shown in FIG. 8, when θ = 0 ° without inclination and the inclination angle is 0.02 °, the surface temperature of the nut 1 exceeded 60 ° C., but the inclination angles were 0.04 ° and 0.06 °. The surface temperature of the nut 1 at this time was about 55 to 50 ° C. In particular, when the inclination angle was 0.04 °, the value in the vicinity of 50 ° C., which is a value that is 10 ° or more lower than that when the inclination angle was 0 °, was maintained even after 60 minutes.

As a result, in the ultrasonic welding apparatus using the bolted Langevin type vibrator according to the second embodiment of the present invention, the heat generated by the piezoelectric elements 4a, 4b, 4c, and 4d is conical on the metal blocks 3a and 3b. It turns out that it was suppressed lower than the case where no is provided.
Although not shown, according to the ultrasonic welding apparatus using the bolted Langevin type vibrator according to the second embodiment of the present invention, the heat generation of the piezoelectric element is suppressed to a low level. As in the case of the ultrasonic welding apparatus using the bolted Langevin type vibrator of the embodiment, a stable oscillation state can be maintained even if the ultrasonic welding cycle is repeated for a long time.

(Third embodiment of the present invention)
In the first and second embodiments of the present invention, the bolt-clamped Langevin type vibrator having the conical concave surface on all of the end surfaces in contact with the other parts of the metal block is shown. The third embodiment of the present invention As a form of the above, a bolted Langevin type vibrator in which a part of each end face of each metal block is a conical concave surface will be described.

  FIG. 9 shows the inclination angle (θ) of the conical surface of the metal block and the piezoelectric element of the bolted Langevin type vibrator according to the third embodiment of the present invention. FIG. 9 shows an enlarged cross section of one metal block and the piezoelectric element as an example. The relationship between the other metal block and the electrode is the same.

In FIG. 9, the outer portion close to the outer periphery is a plane perpendicular to the central axis, and the inner portion is a concave portion (A) having a conical surface with an inclination angle (θ) with respect to the plane. The shape in which the inner side close to is a plane perpendicular to the central axis is shown.
The inclination angle of the conical slope of the concave portion of the end face of the metal block 3a is a minute angle of about 0.02 ° to 0.06 °. Therefore, when a part of each facing end face of the metal block is a conical concave surface, Even if it is a conical concave surface of a predetermined angle as a whole, when the bolt 2 is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element, so that a substantially uniform pressing force is obtained. Pressure can be applied. As a result, the piezoelectric element can be prevented from being broken, the variation in the vibration state of the vibrator can be reduced, and the spurious resonance frequency can be increased.

(Fourth embodiment of the present invention)
In the first to third embodiments of the present invention, an example in which the conical concave surface of the metal block is a conical surface having a linear cross section has been described. However, as a fourth embodiment of the present invention, a conical shape is used. A bolted Langevin type vibrator having a concave surface of which is a conical surface with a curved section will be described.

FIG. 10 shows, as an example, the inclination angle (θ) of one metal block of the bolted Langevin type vibrator according to the fourth embodiment of the present invention and the conical surface of the piezoelectric element. The relationship between the other metal block and the electrode is the same.
In FIG. 10, the entire metal block 3a from the outer periphery to the inner periphery is a conical surface with an inclination angle (θ), but the cross section is not a linear inclined surface, but an inclined surface with a curved (corrugated) cross section. There is no.

  The inclination angle of the conical slope of the concave portion at the opposite end face of the metal block 3a is a minute angle of about 0.02 ° to 0.06 °, and therefore the cross section of the end face is a curved inclined face. However, if the conical concave surface has a predetermined angle as a whole, when the bolt 2 is tightened, the conical concave surface of the metal block is deformed so as to be in close contact with the surface of the piezoelectric element, and a substantially equal pressing force is applied. Can be given. As a result, the piezoelectric element can be prevented from being broken, the variation in the vibration state of the vibrator is reduced, and the spurious resonance frequency can be increased.

  Although not shown, according to the ultrasonic welding apparatus using the bolted Langevin type vibrator according to the third and fourth embodiments of the present invention, the heat generation of the piezoelectric element is suppressed to a low level. As in the case of the ultrasonic welding apparatus using the bolted Langevin type vibrator according to the first and second embodiments, a stable oscillation state can be maintained even if the ultrasonic welding cycle is repeated for a long time.

  The present invention can be applied as a bolted Langevin type vibrator of an ultrasonic welding apparatus for ultrasonic welding of plastic. In particular, since the compressive pressure applied by tightening generated at the interface between the piezoelectric element and the electrode becomes uniform, it can be applied to a high-frequency bolted Langevin type vibrator.

  The present invention provides a new method for making a load applied to a piezoelectric element of a bolt-clamped Langevin type vibrator uniform, preventing destruction of the piezoelectric element, reducing variation in vibration state of the vibrator, and increasing a spurious resonance frequency. Conventionally known methods for using one of the metal blocks with a Young's modulus greater than a predetermined value, and applying adhesive to the contact area between the piezoelectric element and each component It can be applied in combination with other methods.

1 Nut 2 Bolt 3a, 3b, 13a, 13b Metal block 4a, 4b, 14a, 14b Piezoelectric element 5a, 5b, 15a, 15b Electrode 6 Fixed horn 7 Booster horn 9 Tool horn 35 Movable frame 36 Fixed frame 37 Air cylinder 41 Receiving Jig 42 Workpiece

Claims (6)

Bolt tightening having a plurality of piezoelectric elements having an electrostrictive effect, electrodes alternately stacked with the piezoelectric elements, a pair of metal blocks sandwiching the piezoelectric elements and the electrodes, and bolts for fastening the metal blocks In Langevin type vibrator,
Forming a conical concave surface centered on the axis of the bolt on at least one of the opposing end surfaces of the pair of metal blocks;
A bolt-clamped Langevin type vibrator assembled by tightening the bolt and pressing the conical concave surface of the metal block against the surface of the piezoelectric element or the surface of the electrode.   2. The bolted Langevin type vibrator according to claim 1, wherein all end faces of the metal block on which the concave surface is formed are conical concave surfaces.   The bolted Langevin type vibrator according to claim 1, wherein a part of the end face of the metal block on which the concave surface is formed is a conical concave surface.   The bolted Langevin type vibrator according to claim 2 or 3, wherein the conical concave surface of the metal block is a conical surface having a linear cross section.   4. The bolted Langevin type vibrator according to claim 2, wherein an end surface of the metal block that contacts the other component is a conical concave surface with a conical surface having a curved section. 5.   An ultrasonic welding apparatus using the bolted Langevin type vibrator according to any one of claims 1 to 5.

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