JP2018038992A - Ultrasonic processing langevin-type ultrasonic vibrator, and support method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic processing method suitable for precision processing by increasing the support rigidity of a Langevin type ultrasonic transducer and increasing the support accuracy. SOLUTION: A male screw is provided on the outside of a housing, and a taper for fitting with a tapered annular support frame 6b is provided on the inside of the housing. Then, the Langevin type ultrasonic oscillator 1 was supported and fixed by tapering the tapered annular support frame 6b and the housing 11 by tightening the housing nut 21 provided with the female screw. The electric energy is supplied to the piezoelectric element 3 of the Langevin type ultrasonic transducer 1 from the ultrasonic oscillation circuit 8 provided outside the housing through the hole 19 formed in the housing 11. It was made to apply. [Selection diagram] FIG. 4

Description

  The present invention relates to a Langevin type ultrasonic transducer for ultrasonic processing and a support method thereof.

  Various types of ultrasonic transducers using a piezoelectric element as an ultrasonic wave generation source are known. As a typical configuration, a piezoelectric block fixed between a pair of metal blocks and these metal blocks is used. A Langevin type ultrasonic transducer composed of elements is known. In particular, bolted Langevin type ultrasonic vibrators with a structure in which piezoelectric elements are connected by bolts between a pair of metal blocks and fastened and fixed at a high pressure are capable of high-energy ultrasonic vibration, so cutting of various materials is possible. In addition, the use in ultrasonic processing attached to a tool for performing plastic working, abrasive grain processing, and the like has been studied.

  The configuration of various ultrasonic transducers, including bolt-clamped Langevin type ultrasonic transducers, is already known, but as a precaution, the configuration of typical bolt-clamped Langevin type ultrasonic transducers and their usage forms are attached. This will be briefly described below with reference to FIGS.

  FIG. 1 is a diagram showing an example of a typical structure of a bolted Langevin type ultrasonic transducer. The bolt-clamped Langevin type ultrasonic vibrator 1 has a structure in which a piezoelectric element (eg, a piezoelectric ceramic plate) 3 is sandwiched between a pair of metal blocks 2a and 2b and the metal blocks 2a and 2b are fastened to each other using a bolt 4. Have. In FIG. 1, the arrow written in the piezoelectric element indicates the polarization direction. The piezoelectric element 3 is connected to electrode pieces 5a and 5b (usually using electrode pieces such as phosphor bronze) used as terminals for applying electric energy.

  FIG. 2 is a diagram illustrating a configuration example of an ultrasonic grinding apparatus (polishing machine) that uses a bolted Langevin type ultrasonic vibrator as an ultrasonic vibration source. In FIG. 2, an ultrasonic grinding apparatus 10 accommodates an ultrasonic vibrator 1 having a polishing tool 13 connected to a lower end portion via a horn 12 in a housing 11. The bearing 14 is rotatably supported. The rotation of the ultrasonic transducer 1 is driven by an AC spindle motor 16 connected to the servo unit 15. In the apparatus of FIG. 2, the electrical energy for ultrasonic vibration of the ultrasonic vibrator is a contact-type power supply composed of a carbon brush connected to an external electric energy supply source 17 and a slip ring 18. Supplied through the device.

  By the way, the effects expected by applying ultrasonic vibration to various tools in the ultrasonic processing apparatus are reduction of cutting resistance, improvement of sharpness, improvement of processing accuracy, and the like. However, the expected effects have not been sufficiently obtained with ultrasonic processing apparatuses manufactured so far and used in actual processing operations. For this reason, at the present time, the spread of ultrasonic processing apparatuses has not progressed much. Accordingly, in order to promote the widespread use of ultrasonic machining, it is necessary to improve the support rigidity of the ultrasonic transducer and the accuracy of the support position in the implementation of the ultrasonic machining operation.

  The inventor of the present invention has so far devised an improved invention of an ultrasonic transducer that can be expected to improve the support rigidity of the ultrasonic transducer, and has applied for a patent. For example, Patent Document 1 discloses a recent invention among the improved inventions.

  In Patent Document 1, a vibration composite of a tool and an ultrasonic vibrator is supported with high stability, and a support (fixed support) of the composite of ultrasonic energy generated in the ultrasonic vibrator. As a support structure that enables high-efficiency application of vibrational energy to the tool by suppressing exposure to a low level, a flange is attached to the ultrasonic vibrator equipped with the tool, and one side of the flange is In addition, a support structure that engages and supports by contacting the support surface of a separately prepared fixed body in a stressed state (however, the flange of the ultrasonic vibrator is not joined to the flange support surface of the fixed body, Also, the flange of the ultrasonic vibrator that is engaged with and supported by the support surface of the fixed body is structured to vibrate ultrasonically in the thickness direction of the flange when the ultrasonic vibrator is in a vibrating state. Has been.

  In Patent Document 2, an ultrasonic vibrator, a transmission horn that transmits ultrasonic vibration generated by supporting the ultrasonic vibrator, a tool that is detachably attached to the tip of the transmission horn, and a transmission horn support A flange that protrudes outward on the outer diameter side of the shaft vibration node portion of the transmission horn and a support shaft at the center shaft portion of the shaft vibration node portion of the transmission horn for transmission. A configuration is disclosed in which a horn is pressed and supported on an outer cylinder by a flange and a support shaft.

International Publication WO2014 / 017460AI JP-A-5-77145

Yoshio Iwata et al., “Mechanical Vibration”, Mathematical Engineering, May 2011, p22-p28, p152-p158

  A large load is applied to the Langevin type ultrasonic transducer used for machining. However, up to now, Langevin type ultrasonic transducers are designed and manufactured without load. Therefore, when a load is applied, there is a big problem that the performance cannot be fully exhibited.

  With the ultrasonic processing apparatus using the new support structure of the ultrasonic vibrator described in Patent Document 1, the problems of the ultrasonic processing apparatus using the ultrasonic vibrator having a conventionally known structure can be solved. It has been seen. However, the ultrasonic machining apparatus using the support structure of the ultrasonic vibrator described in Patent Document 1 has also been found to be unable to obtain a sufficiently satisfactory machining accuracy in practical use.

  Depending on the method of providing a support shaft at the center shaft portion of the shaft vibration node portion in the transmission horn described in Patent Document 2, the position of the shaft vibration node position depends on the shape of the tool attached to the front end portion of the transmission horn. Therefore, if the tool length changes, the vibration of the ultrasonic transducer may be reduced. Moreover, since it supports using a screw, support rigidity becomes low and there exists a possibility that processing precision may fall.

  Accordingly, an object of the present invention is to provide a structure and a supporting method of a Langevin type ultrasonic transducer suitable for ultrasonic processing capable of improving processing accuracy.

  The inventor of the present invention examined the generation mechanism of the ultrasonic vibration in the Langevin type ultrasonic vibrator again for the purpose of improving the support structure of the new ultrasonic vibrator described in Patent Document 1. In the examination, the support configuration shown in FIGS. 3 and 4 was considered as a model of the configuration that firmly supports the Langevin type ultrasonic transducer. The Langevin ultrasonic transducer 1 having the supporting structure of FIG. 3 includes a metal front mass 2d, a phosphor bronze electrode plate 5d, a piezoelectric element 3d polarized in the plate thickness direction, a phosphor bronze electrode plate 5c, a plate Piezoelectric element 3c polarized in the thickness direction, tapered annular support frame 6b, piezoelectric element 3b polarized in the plate thickness direction, electrode plate 5b made of phosphor bronze, piezoelectric element 3a polarized in the plate thickness direction, made of phosphor bronze The electrode plates 5a are arranged in order, and a metal rear mass 2a having a male screw is screwed into the front mass 2b and tightened. Here, the tapered annular support frame 6b has a conical shape with a small diameter on the housing side and a large diameter on the front mass side.

  Further, considering the support rigidity and vibration characteristics of the Langevin type ultrasonic transducer, first, regarding the support stiffness, the thickness of the tapered annular support frame 6b is 1 of the outer diameter of the piezoelectric element of the Langevin type ultrasonic transducer. / 5 or more is preferable. Then, the total thickness of the piezoelectric elements of the Langevin type ultrasonic transducer to supply electrical energy for exciting the magnitude of the desired ultrasonic oscillation to the Langevin type ultrasonic transducer is a tapered annular support frame. It is desirable that the thickness be larger than 6b.

On the other hand, the conventional Langevin type ultrasonic transducer is to make the flange as thin as possible so that it can support the Langevin type ultrasonic transducer so that it can perform best with no load. It is smaller than 1/10 of the outer diameter of the piezoelectric element of the ultrasonic vibrator.
However, when a load is applied, the thin flange that supports the Langevin type ultrasonic transducer is deformed, thereby deteriorating the processing accuracy. Also. The resonance frequency and the admittance value of the Langevin type ultrasonic transducer are greatly changed, and the amplitude is greatly reduced.

  In the configuration of FIG. 3, the total thickness of the piezoelectric elements is 20 mm, and the diameter is 15 mm. The thickness of the tapered annular support frame 6b is 5 mm. Therefore, the thickness of the tapered annular support frame 6b is 1/3 of the outer diameter of the piezoelectric element of the Langevin type ultrasonic transducer. The total thickness of the piezoelectric elements is four times the thickness of the tapered annular support frame 6b.

  A method of supporting a Langevin type ultrasonic transducer on the housing will be described with reference to FIG. In order to support the bolted Langevin ultrasonic transducer 1, a steel housing 11 is prepared. A male screw is provided on the outer side of the housing, and a taper for fitting with the tapered annular support frame 6b is provided on the inner side of the housing 11. Then, by tightening the housing nut 21 provided with the female screw, the tapered annular support frame 6b and the housing 11 are supported and fixed by fitting the taper. The electrical energy is supplied to the piezoelectric element 3 of the Langevin ultrasonic transducer 1 by applying a voltage of a predetermined frequency from the ultrasonic oscillation circuit 8 provided outside the housing through the hole 19 formed in the housing 11. I tried to do it. Moreover, the numerical value which shows the dimension in FIG. 4 here is a mm unit.

Here, the reason why the taper fitting and the tightening with the housing housing nut are selected as the means for supporting the ultrasonic vibrator on the housing will be described.
First, the taper fitting shown in FIGS. 5A and 5B and the straight fitting shown in FIGS. 5C and 5D will be described. In general, the higher the required accuracy, the more taper fitting is employed. In the case of straight connection, the clearance for fitting the two parts becomes a factor of fluctuation. Further, such shaft deflection causes unnecessary amplified vibrations and sounds to be generated in the tool attached to the front mass.
By the way, in the case of the taper fitting, if a firm “large contact (large end alignment)” is provided and parts are finished on the basis of the taper, generation of unnecessary vibrations and sounds can be drastically reduced.
As for maintainability, the occurrence of galling can be greatly reduced by taper fitting. Even if the fitting is repeated, the accuracy can be easily restored as compared with the straight fitting.
Based on the above features, a taper fit was adopted.

Next, the reason why the male screw of the housing 11 and the housing nut 21 are used as means for fastening the ultrasonic vibrator to the housing will be described.
5A and 5C show the case where the male screw of the housing 11 and the housing nut 21 are used as the fastening means, and FIGS. 5B and 5D show the bolt 4 through the screw hole of the housing 11 through the hole of the holding plate as the fastening means. It is the structure which tightens with.
First, in the case of using the housing nut 21, if the processing accuracy of the male screw shape and male screw accuracy of the housing 11 and the female screw accuracy of the housing nut 21 is increased, the error with respect to the central axis is reduced.
On the other hand, when the bolt 4 is used, there is an error due to the clearance of the pressing plate. And since a plurality of bolts 4 are used, a tightening error occurs. An error occurs every time the operation is repeated. Further, since the radius of the bolt 4 is small, the tightening force is small as compared with the housing nut 21 even when a plurality of bolts are used.
For the above reason, the taper fitting and the tightening by the housing nut 21 were selected as means for supporting the Langevin type ultrasonic transducer on the housing 11 shown in FIG. 5A.

As a means for supporting the Langevin type ultrasonic transducer on the housing, taper fitting and tightening with a housing nut were selected. As shown in the schematic diagram of FIG. 6, the tapered annular support frame 6b has three support methods. is there.
In the tapered annular support frame 6b shown in FIG. 6A, the surface in contact with the housing 11 is tapered, and the opposite surface is a flat surface. The housing 11 has a taper so that the taper can be engaged with the tapered annular support frame 6b.
In the tapered annular support frame 6b shown in FIG. 6B, the surface in contact with the housing nut 21 is tapered, and the opposite surface is flat. The housing nut 21 has a taper so that the taper can be engaged with the tapered annular support frame 6b.
In the tapered annular support frame 6b shown in FIG. 6C, the surface in contact with the housing 11 is tapered, and the surface in contact with the housing nut 21 is also tapered. The housing 11 and the housing nut 21 have a taper so that the taper can be engaged with the tapered annular support frame 6b. This method is the most suitable shape for precision machining because the positional accuracy can be increased by taper fitting on both surfaces of the tapered annular support frame 6b.

  In order to evaluate the ultrasonic vibration characteristics of the bolted Langevin type ultrasonic transducer 1 having the shape and size shown in FIG. 3, the Langevin type ultrasonic transducer 1 is unconstrained using an impedance analyzer. Frequency characteristics were measured. As for the frequency characteristics, the frequency of the admittance peak indicating the resonance frequency was 29535 Hz, and the peak admittance value was 8.28 mS.

  In addition, when a function synthesizer was connected to the power amplifier, the frequency was swept at a voltage of 20 Vp-p to maximize the current, and the current value was about 133 mA. Then, the amount of vibration displacement at the center of the front mass under the conditions was measured using a laser Doppler vibrometer. The vibration displacement amount was 14.1 μmp-p.

  FIG. 4 shows a case in which the housing 11 and the housing nut 21 support the tapered annular support frame 6b of the bolted Langevin ultrasonic transducer 1 and the housing by taper fitting. Regarding the frequency characteristics in the state, the frequency of the admittance peak indicating the resonance frequency was 29800 Hz, and the peak admittance value was 10.1 mS. Normally, when the bolted Langevin ultrasonic transducer 1 is constrained, the admittance value at the resonance frequency is smaller than that in the unconstrained state, but there are various effects when there is almost no constraining effect. The admittance is greater when there is a constraint than when there is no constraint.

  In addition, when a function synthesizer was connected to the power amplifier, the frequency was swept at a voltage of 20 Vp-p, the admittance was maximized at 29.66 KHz, and the admittance value was about 146 mA. Then, the amount of vibration displacement at the center of the front mass under the conditions was measured using a laser Doppler vibrometer. The vibration displacement amount was 14.1 μmp-p.

  The state in which the Langevin type ultrasonic transducer of FIG. 3 is unconstrained is about 1% lower in resonance frequency and about 22% lower in admittance value than the Langevin type ultrasonic transducer in the constrained state of FIG. . When the function synthesizer is connected to the power amplifier and driven, the state in which the Langevin type ultrasonic transducer in FIG. 3 is unconstrained is more current than that in the constrained Langevin type ultrasonic transducer in FIG. Was about 10% smaller and the vibration displacement was the same.

  Such a difference is easily caused by a temperature change of the Langevin type ultrasonic transducer. And this degree of difference also occurs in the measurement order. That is, the state in which the Langevin type ultrasonic transducer of FIG. 3 is unconstrained is equal to the difference between the Langevin type ultrasonic transducer in the constrained state of FIG.

  The structure of the Langevin type ultrasonic transducer and the method of supporting the Langevin type ultrasonic transducer of the present invention can realize a highly rigid support, and support accuracy even when the Langevin type ultrasonic transducer is repeatedly detached from the housing. Can be maintained. And in the ultrasonic processing method using this, processing accuracy can be improved.

It is a figure which shows the structure of a typical bolting Langevin type ultrasonic transducer | vibrator. It is a figure which shows the structure of the ultrasonic processing apparatus using a bolting Langevin type ultrasonic transducer | vibrator. It is a figure which shows the structure of the bolting Langevin type ultrasonic transducer | vibrator of this invention. It is a figure which shows the structure which supported and fixed the bolting Langevin type ultrasonic transducer | vibrator of this invention to the housing with the housing nut. It is a figure explaining the comparison with a straight fitting and a taper fitting, and fastening with a housing nut and a bolt. It is a figure explaining the kind of taper of a taper annular support frame. It is a figure explaining the ultrasonic cutter using this invention. It is a figure explaining the ultrasonic drill using this invention.

  The Langevin type ultrasonic vibrator and the supporting method thereof according to the present invention exhibit its characteristics when a mechanical load is applied to the Langevin type ultrasonic vibrator. In addition, it is possible to classify the use into a use in which the Langevin type ultrasonic transducer is not rotated and a use in which it is rotated.

  First, an ultrasonic cutter which is an application in which a Langevin type ultrasonic transducer is not rotated will be described with reference to FIG. In the Langevin type ultrasonic transducer shown in FIG. 7A, a screw is screwed into a steel front mass 2 formed integrally with a tapered annular support frame 6b, and a piezoelectric element, an electrode plate, a piezoelectric element, an electrode plate, Then, a steel rear mass is tightened with a through nut 7 so as to be integrated. The shape of the tapered annular support frame 6b has a taper on both sides. FIG. 7B is a perspective view of the cutter shown in the sectional view of FIG. 7A. A cemented carbide cutter blade is joined to the tip of a cemented carbide or steel round bar by a method such as brazing. Moreover, the cutter blade may electrodeposit diamond depending on the application.

  Next, by matching the taper of the housing 11 with the taper of the tapered annular support frame 6b of the Langevin type ultrasonic transducer, and fitting the taper of the housing nut to the taper for the housing nut of the tapered annular support frame 6b The Langevin type ultrasonic transducer is supported and fixed to the housing.

  Further, a collet is inserted into a tapered hole provided at the front end of the front mass, the collet nut is loosely tightened, and then the cutter is inserted into the collet, and the tightening cutter is fixed to the Langevin type ultrasonic vibrator.

  Here, the operation method of the ultrasonic cutter will be described. For example, in order to cut a plastic plate (not shown), an ultrasonic cutter is attached to a three-dimensional processing machine and cut into a desired shape by a program. First, the power supply of the ultrasonic oscillation circuit 8 connected to the ultrasonic cutter by a lead wire is turned on to excite ultrasonic vibration of a desired vibration mode in the ultrasonic cutter. Then, the three-dimensional machine is turned on, the machining program is activated, and the plastic plate is cut. When the cutting is finished, the ultrasonic oscillation circuit 8 is turned off, the power of the three-dimensional processing machine is turned off, and the processing is finished.

  The ultrasonic cutter using the Langevin type ultrasonic vibrator and the supporting method of the present invention has high rigidity and high support accuracy, and therefore can be used with high accuracy and a large load.

  An ultrasonic drill that is used to rotate a Langevin type ultrasonic transducer will be described with reference to FIG. A Langevin type ultrasonic transducer is manufactured by screwing a stainless steel rear mass into the male screw of the stainless steel front mass that integrates the tapered annular support frame 6b and the male screw in the order of piezoelectric element, electrode plate, piezoelectric element and electrode plate. To do.

  On the other hand, a spindle is created by the following procedure. Insert two bearings between the housing and the case, then insert the outer spacer, inner spacer and bearing, tighten the outer spacer ring and the transformer base, and manufacture the spindle.

  Two lead wires (not shown) of the Langevin type ultrasonic transducer are put in the housing, and the hole of the transformer base is passed through. Then, the taper of the housing and the taper of the tapered annular support frame 6b are matched and connected by tightening. Thereafter, the lead wire (not shown) of the Langevin type ultrasonic transducer and the copper wire of the rotary transformer are connected. Then, the rotating shaft is screwed into the transformer base.

  Next, the rotary transformer (fixed) is bonded to the rotary transformer stand (fixed) with an adhesive. Then, screw the rotary transformer base (fixed) to the sleeve and screw it into the housing.

  The motor base is attached to the sleeve with screws, the coupling is attached to the rotating shaft, the motor base is attached to the sleeve, the motor shaft is inserted into the coupling, and the motor is also fixed to the motor base with a bolt (not shown). Then, the coupling and the motor shaft are tightened with screws. The ultrasonic spindle is manufactured as described above. Then, a collet is put into the tapered hole of the front mass, the collet nut is lightly tightened, and then the drill is put into the collet to form an ultrasonic drill.

  Here, the operation method of the ultrasonic drill will be described. For example, in order to make a hole in a carbide plate (not shown), an ultrasonic drill is attached to a three-dimensional processing machine to make a hole at a desired position by a program. First, the power supply of the ultrasonic oscillation circuit connected to the ultrasonic drill is turned on, and the cutting fluid is discharged from the nozzle almost simultaneously to excite ultrasonic vibration of a desired vibration mode in the ultrasonic drill. Then, the three-dimensional machine is turned on, the machining program is activated, and the carbide plate is drilled. When the drilling is finished, the ultrasonic oscillation circuit and the motor of the cutting fluid supply device are turned off, and the power of the three-dimensional processing machine is turned off to finish the machining.

  If the drill of the ultrasonic drill is replaced with an end mill and the end mill is rotated, the end mill is moved in the horizontal direction, so that grooving can be performed. Since the support stiffness of the Langevin type ultrasonic transducer of the present invention is large, it can be processed with high accuracy even in the horizontal direction as compared with the normal support.

  The ultrasonic drill using the Langevin type ultrasonic transducer of the present invention and its support method has high rigidity and high support accuracy, so that it can be drilled with high accuracy and can be used for a large load.

  As described above, the Langevin type ultrasonic transducer and the supporting method thereof according to the present invention are suitable for ultrasonic processing to which a mechanical load is applied.

1 Bolt-clamped Langevin type ultrasonic transducer 2a Metal block (rear mass)
2b Metal block (front mass)
3 Piezoelectric Element 4 Bolt 5 Phosphor Bronze Electrode 6a Annular Support Frame 6b Tapered Annular Support Frame 7 Nut 8 Ultrasonic Oscillator 10 Ultrasonic Grinding Device 11 Housing 12 Horn 13 Grinding Tool 17 Electric Energy Supply Source 19 Hole 20 Base 21 Housing nut 22 Collet nut 23 Lead wire 24 Collet

Claims (4)

  In a Langevin type ultrasonic transducer composed of a pair of metal blocks and a piezoelectric element fixed between these metal blocks, the support plate has a tapered shape, and the housing supports the Langevin type ultrasonic transducer. A Langevin type ultrasonic transducer is provided with a taper that fits with the taper of the support plate, and the Langevin type ultrasonic transducer is supported and fixed to the housing by fastening a housing nut and a male screw provided outside the housing. And support method.   In a Langevin type ultrasonic transducer composed of a pair of metal blocks and a piezoelectric element fixed between these metal blocks, the support plate has a tapered shape, and the housing nut tapers with the taper of the support plate The Langevin type ultrasonic transducer is supported and fixed to the housing by pressing the flat side of the indicator plate to the housing, fitting the taper of the housing nut and the support plate, and tightening the housing nut and the housing. Langevin type ultrasonic transducer and supporting method.   In a Langevin type ultrasonic transducer composed of a pair of metal blocks and a piezoelectric element fixed between these metal blocks, both sides of the support plate are tapered, and the housing is fitted with the taper of the support plate. A taper is provided, and a taper that fits into the taper of the support plate is provided on the housing nut, and the Langevin ultrasonic transducer is supported and fixed to the housing by tightening the male screw provided on the outside of the housing nut and the housing. Langevin type ultrasonic transducer and support method.   The thickness of the tapered annular support frame 6b is larger than 1/5 of the outer diameter of the piezoelectric element of the Langevin type ultrasonic transducer and smaller than 2/3. Langevin type ultrasonic transducer and support method.

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