JPH0753263B2 - Method of driving composite vibration of ultrasonic transducer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite vibration driving method for an ultrasonic vibrator that combines and vibrates unidirectional vibrations such as longitudinal and flexural vibrations that have been frequently used in the past. A composite of ultrasonic transducers used for ultrasonic welders that weld and join plastics and metals, ultrasonic bonders, ultrasonic cutters that cut sheet materials, ultrasonic wrappers that polish metal molds, cemented carbide, or ceramics. The present invention relates to a vibration driving method.

2. Description of the Related Art Conventionally, as an ultrasonic transducer that generates a composite vibration, one that generates a circular vibration by flexing the longitudinal and flexural or longitudinal and torsional resonance frequencies, or an ultrasonic motor that uses a traveling wave There are some that have been adapted to
Generally, most of the ultrasonic transducers generate only vertical unidirectional vibration.

Under such circumstances, the applicant of the present invention, as previously disclosed in JP-A-62-114478, sets the blade provided at the output end of the flexural vibrator at a right angle to the vibrator axis or at a controlled angle. We proposed an ultrasonic cutter that can be used by vibrating it.

An example using such a vibrator will be described with reference to FIGS. 6 to 9.

First, the annular electrostrictive elements 2 and 3 polarized in the thickness direction are
Electrodes 14 and 15 are formed on one surface of the insulating portion 13 as a center, and a common electrode 16 is formed on the other surface of the electrode 14 and 15.

The two electrostrictive elements 2 and 3 are arranged so that the insulating portions 13 are aligned and the electrodes 14 and 15 are opposed to each other with the two electrode plates 4 and 5 interposed therebetween. Then, the common electrode plate 6 is joined to the surface of the common electrode 16 of one of the electrostrictive elements 3, and further, the metal material 9 having the output end portion 10 formed thin and having the exponential step 8 is joined. ing. A metal material 7 is bonded to the surface of the common electrode 16 of the other electrostrictive element 2. Then, these are integrally fixed by the bolts 11 to form the flexural vibrator 1.

Next, a cutter blade 12 is fixed to the output end 10 of the flexural vibrator 1 by silver brazing or the like.

In such a configuration, with the common electrode plate 6 as a reference,
When a driving voltage having a flexural resonance frequency in which the phases are inverted to each other is applied to the electrode plates 4 and 5, flexural resonance vibration occurs at right angles to the axis and in the electrode dividing direction, and the blade edge vibrates strongly in the direction of arrow 17.

Then, as shown in FIG. 9, the sheet 19 which is the material to be cut
Is placed on the table 18 having the spot facing 20 provided to escape the cutting edge portion, and the sheet 19 is fed in the right or left direction,
The sheet 19 is easily cut by repeating the large acceleration of the ultrasonic vibration of the cutter blade 12. Furthermore, according to the flexural vibrator in which the longitudinal and flexural resonance frequencies are matched, it is possible to apply vibration in a direction perpendicular to the axis to the cutting edge,
By controlling the drive voltage applied to each electrode, the vibration direction of the cutting edge can be continuously controlled from the axial direction to the direction perpendicular thereto.

However, matching the longitudinal resonance frequency and the flexural resonance frequency is quite difficult, even with a fixed tool. That is, the resonance frequency that changes depending on the magnitude of the load is, of course, due to tool replacement, wear and regrinding.
The rate of change differs depending on the resonance mode, and the difference between the resonance frequencies greatly separates with the load. As a result, the relative phase and relative amplitude are deviated and the vibration direction cannot be controlled correctly.

Means for Solving the Problems The invention according to claim 1 drives the flexural vibrator for longitudinal vibration at a longitudinal resonance frequency, and at the same time, drives the flexural vibration at a flexural resonance frequency different from that.

According to the second aspect of the present invention, the flexural vibrator is driven for longitudinal vibration at a longitudinal resonance frequency, and at the same time, the flexural vibrator is driven for complex flexural vibration by compounding flexural vibrations at right angles. .

Action A single flexural vibrator can easily generate a composite compound vibration in the axial direction and the direction perpendicular to it, and also, the first and second flexures perpendicular to each other in the longitudinal direction and the bending direction. Since it is not necessary to match the resonance frequency with the direction, the flexibility of the dimension of the flexible oscillator is large,
This can greatly simplify the structure of the vibration system.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. This embodiment relates to an ultrasonic cutter, and the same parts as those described with reference to FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

First, the flexural vibrator 21 having the electrostrictive elements 2 and 3 is provided with a right male screw 23 at its output end 22. A left male screw 25 is provided on the tool 24 in which the blade 26 is joined by silver brazing. The flexural vibrator 21 and the tool 24 are fitted with the fastening ring 27 provided with the right and left female screws and the spanner hook 28, and the respective directions of the cutting direction of the blade 26 and the flexural vibration direction are set. It is fastened together.

The blade 26 has various blades such as an R blade, a sharp blade, and a flat blade in addition to the sword tip shown in the drawing. A plurality of types of tools having these blades 26 are prepared and selectively exchanged through the fastening ring 27. used.

Then, from the high-frequency power source 30 adjusted to the flexural resonance frequency of the flexural vibrator 21 including the tool 24, voltages having mutually inverted phases are output from the secondary coil 32 of the output transformer 31 to the electrode plates 4,5.
When applied to the electrostrictive elements 2 and 3, the lower half contracts at the moment when the thickness of the upper half of the electrostrictive elements 2 and 3 expands, and a bending mode vibration distribution occurs due to the cycle operation that reverses after a half cycle, and the cutting edge is aligned with the axis as shown by arrow 37. It vibrates at right angles.

Next, a high frequency power supply 34 having a longitudinal resonance frequency, an output transformer 35, a secondary coil 32 of the transformer 31 and a middle point tap 33.
When a voltage is applied to the electrode plates 4 and 5, as a common-mode voltage, the electrostrictive elements 2 and 3 expand and contract at the same time in the vertical direction, so that an axial longitudinal mode vibration distribution occurs and the cutting edge as indicated by arrow 38. Vibrates in the axial direction.

Therefore, when both high frequency power sources 30 and 34 are driven at the same time, a composite compound vibration of vibrations in directions perpendicular to each other is generated at the cutting edge. Since the respective resonance frequencies change as the tool 24 is replaced or the cutting edge is worn or a load is applied, it is preferable that the frequencies of the high frequency power supplies 30 and 34 can oscillate by tracking the respective resonance frequencies. Since each oscillation frequency oscillates independently, there is no relation between frequency and phase,
The composite compound vibration changes in random directions. The composite compound vibration at the cutting edge is a combination of the flexural vibration 37 and the longitudinal vibration 38. By controlling the amplitude of each vibration, the shape of the envelope of the vibration locus is flexed as shown in FIG. The direction may be a straight line (a), a rectangle (b), a square (c), a rectangle (d), and a straight line (e), which are appropriately selected depending on the material of the material to be cut and the content of the cutting process.

In this way, the blade edge vibrates randomly in all directions by the combined compound vibration on the plane with the axis and the direction perpendicular to it as biaxial, so it does not depend on the relative angle between the blade of the vibrator and the material to be cut. Good cutting is possible.

This also means that the cutting edge cuts at any angle with respect to the material to be cut, and thus exhibits a remarkable cutting effect as compared with the conventional unidirectional vibration.

Next, a second embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to an ultrasonic wrapper, and the one shown in FIGS. 3 and 4 has a first flexural vibration and a second flexural vibration which is driven with a phase difference of 90 degrees in the direction perpendicular thereto. A vibrator and its drive circuit that generate longitudinal vibration together with combined flexural vibration combined with flexural vibration.

Then, the electrostrictive elements 41, 42 that generate the first flexural vibration
Has electrodes divided into upper and lower parts on one side, and electrode plates 43,44
Is energized by. The electrostrictive elements 45 and 46 that generate the second flexural vibration in the direction perpendicular to the first flexural vibration have electrodes divided into left and right on one surface and are energized by the electrode plates 47 and 48. These are sandwiched by the metal materials 51 and 52 together with the common electrodes 49 and 50, and are integrally fastened by the central bolt 53 to form the composite flexural vibrator 40. Output transformer 55 from high-frequency power supply 54 for driving flexural vibration
When a voltage whose phase is inverted by is applied to the electrode plates 43 and 44, the electrostrictive elements 41 and 42 are driven to be inverted up and down to generate the first bending vibration in the up and down direction.

Further, a part of the power supply 54 is 90 degrees out of phase by the phase shifter 56, and the voltage is applied to the electrode plates 47 and 48 through the output transformer 57 to invert and drive the electrostrictive elements 45 and 46 to the left and right. A second flexural vibration in the left-right direction is generated.

Next, the high frequency power supply 58 for vertical vibration drive is the output transformer 59.
Via the secondary winding intermediate taps of the deflection output transformers 55, 57, and drives all the electrode plates 43, 44, 47 and 48 in phase. Therefore, longitudinal vibration in the axial direction is excited.
A tool 61 having the same cylindrical grindstone 60 is tightly fastened to the output end of the oscillator 40 by fastening nuts 62 having left and right female threads.

FIG. 5 shows the vibration mode of the tool 61 and the tip. A first flexural vibration 63 and a second flexural vibration 64 are generated at the tip of the grindstone 60 as shown by arrows in Fig. 5 (b), but they are synchronized with a phase difference of 90 degrees. As shown in FIG. 5 (c), its vibration form becomes a circular vibration 65, and a longitudinal vibration 66 not synchronized with them causes a cylindrical compound vibration 67 vibrating in random directions.

Further, if the dimensions of the tool are considerably different in the left-right direction and the vertical direction, the first and second flexural resonance frequencies are separated from each other, and it becomes difficult to generate the circular vibration 65. However, in such a case, if the first and second flexural vibrations are independently tracked independently of the resonance frequency, a good effect can be obtained.

Such a cylindrical grindstone 60 and its cylindrical composite vibration 67,
It is useful for polishing R-shaped corners. The flexural vibration component on the side surface and the longitudinal vibration component on the bottom surface act as an auxiliary to increase the polishing effect.

The synthetic vibration of the longitudinal vibration component and the flexural vibration component at right angles to the synthetic vibration direction changes randomly at different vibration frequencies, and the random change of the vibration direction has a favorable effect on the machining result. Compared with the conventional polishing action only by a single longitudinal or flexural vibration, a combined vibration of the vibration and the orthogonal vibration results in a significant increase in the polishing effect. Furthermore, by controlling the amplitudes of the vertical and flexural components to optimal values according to the shape of the polished surface and the processing conditions, effective polishing can be performed from rough polishing to finishing.

EFFECTS OF THE INVENTION As described above, according to the present invention, the flexural vibrator is driven for the longitudinal vibration at the longitudinal resonance frequency, and the flexural vibration is driven for the flexural resonance frequency different from the longitudinal resonance frequency. This makes it possible to easily generate a composite compound vibration in the axial direction and the direction perpendicular to it, and it is necessary to match the resonance frequencies in the longitudinal direction and the bending direction or in the first and second bending directions perpendicular to each other. Therefore, there is an advantage that the degree of freedom of the dimension of the tool is large and the configuration of the vibration system can be very simplified.

[Brief description of drawings]

1 is a side view showing a first embodiment of the present invention, FIG. 2 is a plan view showing the shapes of envelopes of various vibration loci, and FIG. 3 is a side view showing a second embodiment of the present invention. Fig. 4 is a perspective view of an electrode plate, Fig. 5 is an explanatory view showing a vibration state of a tool and its tip, Fig. 6 is a side view showing a conventional example, Fig. 7 is a perspective view of an electrode plate, FIG. 8 is a perspective view of the electrostrictive element, and FIG. 9 is a partial sectional view showing the cutting operation. 21 ... Flexible vibrator

Claims (2)

[Claims] 1. A composite vibration driving method for an ultrasonic vibrator, comprising: driving a flexural vibrator to longitudinal vibration at a longitudinal resonance frequency and driving flexural vibration to a flexural resonance frequency different from that. 2. A flexural oscillator is driven for longitudinal vibration at a longitudinal resonance frequency, and at the same time, it is driven for complex flexural vibration by compounding flexural vibrations at different flexural resonance frequencies. Method for driving complex vibration of sound wave oscillator.