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JP2018038992

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DESCRIPTION JP2018038992
Abstract: The present invention provides an ultrasonic processing method suitable for precision
processing by enhancing the support rigidity of a Langevin type ultrasonic transducer and
enhancing the support accuracy. An external thread is provided on the outside of a housing, and
a taper for engaging with a tapered annular support frame 6b is provided on the inside of the
housing. Then, by tightening the housing nut 21 provided with a female screw, the tapered
annular support frame 6b and the housing 11 are taper-fitted to support and fix the Langevin
type ultrasonic transducer 1. The supply of electrical energy to the piezoelectric element 3 of the
Langevin type ultrasonic transducer 1 is carried out 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. It was made to apply. [Selected figure] Figure 4
Langevin-type ultrasonic transducer for ultrasonic processing and its supporting method
[0001]
The present invention relates to a Langevin type ultrasonic transducer for ultrasonic processing
and a supporting method thereof.
[0002]
Ultrasonic transducers that use a piezoelectric element as an ultrasonic wave generation source
are known in various configurations. As a typical configuration, a piezoelectric element fixed
between a pair of metal blocks and these metal blocks is known. A Langevin-type ultrasonic
transducer composed of elements is known.
04-05-2019
1
Above all, a bolt-clamped Langevin ultrasonic transducer with a structure in which piezoelectric
elements are connected between a pair of metal blocks by bolts and clamped with high pressure
is capable of high-energy ultrasonic vibration, so cutting of various materials The use in
ultrasonic processing has been studied in which it is attached to a tool for performing plastic
processing, abrasive processing, and the like.
[0003]
Although various types of ultrasonic transducers including the bolted Langevin type ultrasonic
transducer are already known, the typical bolted Langevin type ultrasonic transducer and its
form of use are attached just in case This will be briefly described below with reference to FIGS. 1
and 2 of FIG.
[0004]
FIG. 1 is a view showing an example of a typical structure of a bolt-clamped Langevin type
ultrasonic transducer.
The bolt-clamped Langevin ultrasonic transducer 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 bolts 4. Have. In FIG. 1, the
arrows drawn on the piezoelectric elements indicate the polarization direction. The piezoelectric
element 3 is connected to an electrode piece (usually using an electrode piece such as phosphor
bronze) 5a and 5b used as a terminal for applying electrical energy.
[0005]
FIG. 2 is a view showing a configuration example of an ultrasonic grinding apparatus (polishing
machine) using a bolted Langevin type ultrasonic transducer as an ultrasonic vibration source. In
FIG. 2, the ultrasonic grinding processing apparatus 10 accommodates the ultrasonic transducer
1 provided with the polishing tool 13 connected to the lower end portion via the horn 12 in the
housing 11, and this ultrasonic transducer 1 is used. It is rotatably supported by the bearing 14.
The rotation of the ultrasonic transducer 1 is driven by an AC spindle motor 16 connected to a
servo unit 15. In the apparatus of FIG. 2, the electrical energy for ultrasonic vibration of the
04-05-2019
2
ultrasonic transducer is a contact type power supply comprising a carbon brush connected to an
external electric energy supply source 17 and a slip ring 18. It is supplied through the device.
[0006]
By the way, the effect expected by giving ultrasonic vibration to various tools in an ultrasonic
processing apparatus is reduction of the cutting resistance by the said tool, improvement of
sharpness, improvement of processing precision, etc. However, the ultrasonic processing
apparatus manufactured so far and used for actual processing operations has not sufficiently
obtained the expected effect. For this reason, the spread of ultrasonic processing devices has not
progressed so much at the present time. Therefore, in order to promote the widespread use of
ultrasonic processing, it is considered necessary to improve the support rigidity of the ultrasonic
transducer and the accuracy of the support position in performing the ultrasonic processing
operation.
[0007]
The inventor of the present invention has devised and filed a patent application for an improved
invention of an ultrasonic transducer which can be expected to improve the support rigidity of
the ultrasonic transducer. For example, a recent invention among those improved inventions is
disclosed in Patent Document 1.
[0008]
Patent Document 1 discloses that a vibration complex of a tool and an ultrasonic vibrator is
supported with high stability, and a support of the complex of ultrasonic energy generated in the
ultrasonic vibrator (fixed support) As a supporting structure that enables high efficiency
application of vibrational energy to the tool by suppressing exposure to low levels, a flange is
attached to the ultrasonic vibrator equipped with the tool, and one side of the flange is A support
structure which is engaged and supported by bringing a support surface of a separately prepared
fixing body into contact in a stressed state (however, the flange of the ultrasonic vibrator is not
joined to the phantage supporting surface of the fixing body, In addition, the flange of the
ultrasonic vibrator which is engaged and supported in contact with the support surface of the
fixed body has a structure in which ultrasonic vibration is performed in the thickness direction of
the flange when the ultrasonic vibrator is in a vibrating state). It is done.
04-05-2019
3
[0009]
Further, in Patent Document 2, a transmission horn for transmitting an ultrasonic vibration
generated by supporting an ultrasonic transducer and an ultrasonic transducer, a tool detachably
mounted on the tip of the transmission horn, and the transmission horn support And an outward
projecting flange on the outer diameter side of the axial vibration node portion of the
transmission horn, and a support shaft provided on the central shaft of the axial vibration node
portion of the transmission horn A configuration is disclosed in which the horn is supported by
the flange and the support shaft against the outer cylinder.
[0010]
International Publication WO 2014/017460 AI Japanese Patent Application Laid-Open No. 577145
[0011]
Iwao Ikuo et al., "Machine Vibrational Science", Mathematical Engineering, May 2011, p22 to
p28, p152 to p158
[0012]
A large load is applied to the Langevin type ultrasonic transducer used for machining.
However, to date, Langevin-type ultrasonic transducers have been designed and manufactured
under no load conditions.
Therefore, when a load is applied, there is a big problem that the performance can not be fully
exhibited.
[0013]
The ultrasonic processing apparatus using the new ultrasonic transducer support structure
described in Patent Document 1 solves not a little problem of ultrasonic processing apparatus
using an ultrasonic transducer having a conventionally known structure. It has been seen.
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However, it has been found that, with the ultrasonic processing apparatus using the support
structure of the ultrasonic transducer described in Patent Document 1 as well, an improvement
in processing accuracy sufficiently satisfactory for practical use can not be obtained.
[0014]
According to the method of providing a support shaft on the central axis of the axial vibration
node portion in the transmission horn described in Patent Document 2, the position of the axial
vibration node depends on the shape of the tool attached to the tip of the transmission horn
Because of the change, when the tool length changes, the vibration of the ultrasonic transducer
may be reduced.
Moreover, since it supports using a screw, supporting rigidity may become low and processing
accuracy may fall.
[0015]
Therefore, 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 that can realize
improvement in processing accuracy.
[0016]
In order to improve the support structure of the new ultrasonic transducer described in Patent
Document 1, the inventor of the present invention examined the generation mechanism of
ultrasonic vibration in the Langevin-type ultrasonic transducer again.
And in the case of the examination, the support composition shown in Drawing 3 and Drawing 4
was considered as a model of composition which supports a Langevin type ultrasonic transducer
firmly. The Langevin ultrasonic transducer 1 having the supporting structure shown in FIG. 3
includes a metal front mass 2d, an electrode plate 5d made of phosphor bronze, a piezoelectric
element 3d polarized in the thickness direction, an electrode plate 5c made of phosphor bronze,
and a plate Piezoelectric element 3c polarized in the thickness direction, tapered annular support
frame 6b, piezoelectric element 3b polarized in the thickness direction, electrode plate 5b made
04-05-2019
5
of phosphor bronze, piezoelectric element 3a polarized in the thickness direction, phosphor
bronze The electrode plates 5a are sequentially arranged, 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.
[0017]
Also, considering the support stiffness 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. It is desirable to set it to / 5 or more and 2/3 or more. The total thickness
of the piezoelectric elements of the Langevin-type ultrasonic transducer is a tapered annular
support frame in order to supply electrical energy for exciting the desired magnitude of
ultrasonic vibration to the Langevin-type ultrasonic transducer. It is desirable to make it thicker
than 6b.
[0018]
On the other hand, the conventional Langevin-type ultrasonic transducer is to make the flange as
thin as possible so as to support the Langevin-type ultrasonic transducer so as to be able to
perform most without load. Less than 1/10 of the outside diameter of the piezoelectric element
of the ultrasonic transducer. However, when a load is applied, the thin flange supporting the
Langevin-type ultrasonic transducer deforms, thereby deteriorating the processing accuracy. ま
た。 The resonance frequency and the admittance value of the Langevin type ultrasonic
transducer greatly change, and the amount of amplitude decreases significantly.
[0019]
For the configuration of FIG. 3, the total thickness of the piezoelectric elements is 20 mm and the
diameter is 15 mm. And the thickness of the taper annular support frame 6b is 5 mm. Therefore,
the thickness of the tapered annular support frame 6b is 1/3 of the outside diameter of the
piezoelectric element of the Langevin type ultrasonic transducer. The total thickness of the
piezoelectric element is four times the thickness of the tapered annular support frame 6b.
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[0020]
A method of supporting the Langevin type ultrasonic transducer in the housing will be described
with reference to FIG. A steel housing 11 is prepared to support the bolted Langevin ultrasonic
transducer 1. An external thread is provided on the outside of the housing, and a taper for
engaging with the tapered annular support frame 6b is provided on the inside of the housing 11.
Then, by tightening the housing nut 21 provided with the internal thread, the tapered annular
support frame 6b and the housing 11 are supported by taper fitting. In addition, supply of
electrical energy to the piezoelectric element 3 of the Langevin ultrasonic transducer 1 is
performed 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 It was made
to do. Moreover, the numerical value which shows the dimension in FIG. 4 here is a mm unit.
[0021]
Here, the reason why the taper fitting and the tightening by the housing housing nut are selected
as means for supporting the ultrasonic transducer in the housing will be described. First, taper
fitting shown in FIGS. 5A and 5B and straight fitting shown in FIGS. 5C and 5D will be described.
Generally, the higher the required accuracy, the taper fitting is adopted. In the case of a straight
connection, the clearance for fitting the two parts causes the deflection. In addition, such runout
of the shaft portion causes the tool attached to the front mass to generate more amplified
unnecessary vibration and sound. By the way, in the case of the taper fitting, if the firm “large
contact (large end alignment) is out and the parts are finished with the taper standard, it is
possible to drastically reduce the generation of unnecessary vibration and sound. In addition,
with regard to maintenance, the occurrence of galling can be significantly reduced by taper
fitting. And, even if the fitting is repeated, it is easy to restore the accuracy compared with the
straight fitting. The taper fitting was adopted from the above features.
[0022]
Next, the reason for using the male screw of the housing 11 and the housing nut 21 as means for
fastening the ultrasonic transducer to the housing will be described. 5A and 5C use the male
screw of the housing 11 and the housing nut 21 as tightening means, and FIGS. 5B and 5D show
the bolt 4 through the hole of the holding plate in the screw hole of the housing 11 as tightening
means. It is the composition tightened by. First, in the case of using the housing nut 21, if the
04-05-2019
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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 becomes smaller. 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. Repeated work causes an error each time. Further, since the radius of the bolt 4 is small,
the clamping force is smaller than the housing nut 21 even if a plurality of bolts are used. From
the above reasons, as means for supporting the Langevin type ultrasonic transducer in the
housing 11 shown in FIG. 5A, taper fitting and tightening by the housing nut 21 are selected.
[0023]
As means for supporting the Langevin-type ultrasonic transducer in the housing, taper fitting and
tightening with a housing nut were selected, but as shown in the schematic view of FIG. 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 it can be fitted into 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 a flat surface. The housing nut 21 has a taper so that it can be fitted into the
tapered annular support frame 6b. The surface of the tapered annular support frame 6b shown
in FIG. 6C 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 tapers so that they can be
fitted into the tapered annular support frame 6b. This method is the most suitable shape for
precise processing because the positional accuracy can be enhanced by taper fitting on both
surfaces of the tapered annular support frame 6b.
[0024]
In order to evaluate the ultrasonic vibration characteristics of the bolt-clamped Langevin type
ultrasonic transducer 1 having the shape and size shown in FIG. 3, the impedance analyzer is
used to set the Langevin type ultrasonic transducer 1 in a non-constrained state. Frequency
characteristics were measured. And the frequency characteristic of the frequency of the
admittance peak which shows a resonance frequency was 29535 Hz, and the admittance value of
the peak was 8.28 mS.
[0025]
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In addition, a function synthesizer was connected to the power amplifier, and the current value
was about 133 mA at 29.39 KHz at which the current was maximized by sweeping the frequency
with a voltage of 20 Vp-p. And the amount of vibration displacement of the center of the front
mass under that condition was measured using a leather Doppler vibrometer. The amount of
vibration displacement was 14.1 μmp-p.
[0026]
FIG. 4 shows that the housing 11 and the housing nut 21 support the tapered annular supporting
frame 6b of the Langevin ultrasonic transducer 1 and the housing by taper fitting and support,
but the restraint of the bolted Langevin type ultrasonic transducer is used. As for the frequency
characteristics in the state, the frequency of the admittance peak indicating the resonance
frequency was 29800 Hz, and the admittance value of the peak was 10.1 mS. Normally, when the
bolted Langevin ultrasonic transducer 1 is restrained, the admittance value at the resonance
frequency becomes smaller compared to the unrestrained state, but various influences are
obtained when there is almost no influence of the restraint. The admittance is larger when there
is a constraint than when there is no constraint.
[0027]
In addition, a function synthesizer was connected to the power amplifier, and at a voltage of 20
Vp-p, the admittance value was about 146 mA at 29.66 KHz where frequency is swept and
admittance is maximized. And the amount of vibration displacement of the center of the front
mass under that condition was measured using a leather Doppler vibrometer. The amount of
vibration displacement was 14.1 μmp-p.
[0028]
The condition in which the Langevin-type ultrasonic transducer in FIG. 3 was unconstrained was
about 1% lower at the resonance frequency and about 22% smaller in the admittance value
compared to the Langevin-type ultrasonic transducer in the constrained state of FIG. . In addition,
when a function synthesizer is connected to a power amplifier and driven, the state in which the
Langevin-type ultrasonic transducer in FIG. 3 is not constrained is a current compared to the
Langevin-type ultrasonic transducer in the constrained state in FIG. Is about 10% smaller, and the
04-05-2019
9
amount of vibration displacement is the same.
[0029]
This degree of difference is easily generated by the temperature change of the Langevin
ultrasonic transducer. And even in the order of measurement, such a difference occurs. That is,
the state in which the Langevin-type ultrasonic transducer in FIG. 3 is not restrained is equal to
the difference between the Langeban-type ultrasonic transducers in the restrained state in FIG.
[0030]
The configuration of the Langevin-type ultrasonic transducer and the supporting method of the
Langevin-type ultrasonic transducer according to the present invention can realize high rigidity
support, and even if the Langeban-type ultrasonic transducer is repeatedly attached and
detached from the housing, the support accuracy Can be maintained. And in the ultrasonic
processing method using this, processing accuracy can be improved.
[0031]
It is a figure showing composition of a typical bolting Langevin type ultrasonic transducer. It is a
figure which shows the structure of the ultrasonic processing apparatus using a bolting Langevin
type ultrasonic transducer. It is a figure showing composition of a bolting Langevin type
ultrasonic transducer of the present invention. It is a figure which shows the structure which
supported and fixed the bolted Langevin type ultrasonic transducer | vibrator of this invention to
the housing by the housing nut. It is a figure explaining the comparison by straight fitting and
taper fitting, and the fastening by 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 which used
this invention. It is a figure explaining the ultrasonic drill using this invention.
[0032]
The Langevin-type ultrasonic transducer of the present invention and the supporting method
thereof exhibit the characteristics when mechanical load is applied to the Langeban-type
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10
ultrasonic transducer. In addition, the application can be divided into an application that is used
without rotation of the Langevin-type ultrasonic transducer and an application that is rotated.
[0033]
First, an ultrasonic cutter, which is an application that does not rotate the Langevin ultrasonic
transducer, 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 integrally formed with a tapered
annular support frame 6b, and a piezoelectric element, an electrode plate, a piezoelectric
element, an electrode plate Then, the rear mass made of steel is tightened by the through nut 7
and integrally made. The shape of the tapered annular support frame 6b is such that both sides
have a taper. And FIG. 7B is a perspective view of the cutter shown by sectional drawing of FIG.
7A. A cemented carbide cutting blade is joined to the tip of a cemented carbide or steel round bar
by brazing or the like. Also, the cutter blade may electrodeposit diamond depending on the
application.
[0034]
Then, by matching the taper of the housing 11 with the taper of the tapered annular support
frame 6b of the Langevin type ultrasonic transducer in the taper of the housing 11, and by
matching the taper of the housing nut with the taper for the housing nut of the tapered annular
support frame 6b. Support and fix the Langevin type ultrasonic transducer on the housing.
[0035]
Further, the collet is put into the tapered hole provided at the tip of the front mass, the collet nut
is tightened loosely, then the cutter is put into the collet and the tightening cutter is fixed to the
Langevin type ultrasonic transducer.
[0036]
Here, the operation method of the above-mentioned ultrasonic cutter is explained.
For example, in order to cut a plastic plate (not shown), the ultrasonic cutter is attached to a
three-dimensional machine and cut into a desired shape by a program.
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First, the power of the ultrasonic oscillation circuit 8 connected to the ultrasonic cutter by a lead
wire is switched on to excite ultrasonic vibration in a desired vibration mode in the ultrasonic
cutter. Thereafter, the three-dimensional machine is switched on, the machining program is
activated, and the plastic plate is cut. When the cutting is completed, the switch of the ultrasonic
oscillation circuit 8 is turned off and the power of the three-dimensional processing machine is
turned off to end the processing.
[0037]
The ultrasonic cutter using the Langevin-type ultrasonic transducer of the present invention and
the supporting method thereof has high rigidity and high supporting accuracy, so it can be used
with high accuracy and a large load.
[0038]
The ultrasonic drill which is an application which rotates a Langevin type ultrasonic transducer is
demonstrated using FIG.
A Langevin type ultrasonic transducer is manufactured by screwing the rear element made of
stainless steel into the male element of the stainless steel front mass in which the tapered
annular support frame 6b and the male screw are integrated and inserting the piezoelectric
element, the electrode element, the piezoelectric element and the electrode sheet in this order Do.
[0039]
On the other hand, create a spindle in the following procedure. Insert two bearings between the
housing and the case, then insert the outer spacer, inner spacer, and bearings, and tighten the
outer spacer ring and transformer base to make a spindle.
[0040]
Insert two lead wires (not shown) of the Langevin ultrasonic transducer into the housing and
04-05-2019
12
pass through the holes of the transformer base. 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 ultrasonic transducer is connected to the copper wire of
the rotary transformer. Then screw the rotary shaft into the transformer base.
[0041]
Next, the rotary transformer (fixed) is adhesively bonded to the rotary transformer base (fixed).
Then screw the rotary transformer base (fixed) to the sleeve and screw it into the housing.
[0042]
Attach the motor base to the sleeve with a screw, attach the coupling to the rotary shaft, attach
the motor base to the sleeve, insert the motor shaft into the coupling, and fix the motor to the
motor base with a bolt (not shown). After that, tighten the coupling and the motor shaft with
screws. An ultrasonic spindle is manufactured by the above. Then, the 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 tighten the ultrasonic drill.
[0043]
Here, the operation method of the above-mentioned ultrasonic drill is explained. For example, in
order to drill a cemented carbide plate (not shown), an ultrasonic drill is mounted on a threedimensional machine and drilled at a desired position by a program. First, the power of the
ultrasonic oscillation circuit connected to the ultrasonic drill is switched on, and the cutting fluid
is discharged from the nozzle almost simultaneously to excite ultrasonic vibration in a desired
vibration mode in the ultrasonic drill. Thereafter, the three-dimensional machine is switched on,
the machining program is activated, and the cemented carbide plate is drilled. When drilling is
completed, the ultrasonic oscillation circuit and the motor of the cutting fluid supply device are
turned off, and the power of the three-dimensional machine is turned off to complete the
machining.
[0044]
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Grooves can be machined by moving the end mill horizontally while rotating the end mill while
replacing the drill of the ultrasonic drill with the end mill. Since the support rigidity of the
Langevin type ultrasonic transducer of the present invention is large, it can be processed with
high accuracy even for horizontal force as compared with the normal support.
[0045]
The ultrasonic drill using the Langevin type ultrasonic transducer and the supporting method of
the present invention has high rigidity and high supporting accuracy, so it can be drilled with
high accuracy and can be used for a large load.
[0046]
As described above, the Langevin-type ultrasonic transducer of the present invention and the
supporting method thereof are suitable for ultrasonic processing to which a mechanical load is
applied.
[0047]
Reference Signs List 1 bolt tightening 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 circuit 10
Ultrasonic grinding apparatus 11 Housing 12 Horn 13 Grinding tool 17 Electric energy source
19 Hole 20 Base 21 Housing nut 22 Collet nut 23 Lead wire 24 Collet
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