Ultrasonics38(2000)72–76
www.elsevier.nl/locate/ultras One-dimensional longitudinal–torsional vibration converter
with multiple diagonally slitted parts
Jiromaru Tsujino*,Tetsugi Ueoka,Kenichi Otoda,Atsushi Fujimi
Faculty of Engineering,Kanagawa University,Yokohama221-8686,Japan
Abstract
For increasing the available vibration velocity of the one-dimensional longitudinal–torsional vibration converter,a new type of complex vibration converter with multiple slitted parts installed in the positions avoiding longitudinal nodal positions along the converter for decreasing the maximum vibration stress level at the vibration nodal part was studied.The free end of the converter vibrates in an elliptical or circular locus.Complex vibration systems with elliptical to circular or rectangular to square loci can be applied effectively for various high-power applications,including ultrasonic welding of metal or plastics,ultrasonic wire bonding of IC,LSI and electronic devices,and also ultrasonic motors.The converter with multiple slitted parts was improved in the vibration stress level and the quality factor compared with the converter with single slitted part.©2000Elsevier Science B.V.All rights reserved.
Keywords:Circular vibration locus;Complex vibration;Complex vibration ultrasonic welding;Longitudinal–torsional vibration converter; Ultrasonic motor;Ultrasonic plastic welding;Vibration converter with diagonal slits
1.Introduction vibration characteristics because the maximum vibration
stress along the converter is decreased in comparison to
the converter with a slitted part,and the maximum Complex vibration systems with elliptical to circular
vibration amplitude of the converter increases signifi-or rectangular to square loci are effective for various
cantly.Vibration locus,and vibration velocity and phase high-power applications.A one-dimensional longitudi-
distributions along the converter were measured by two nal–torsional vibration converter with a slitted part at
laser Doppler vibrometers.The new-type converters longitudinal vibration nodal area driven by a longitudi-
中文翻译英文转换器
were used for ultrasonic plastic welding and ultrasonic nal vibration system is useful for high-power applica-
motors.
tions including ultrasonic welding of various materials,
The maximum available vibration velocity increased ultrasonic wire bonding of bonding of IC,LSI and
significantly with the new converter.Welding character-electronic devices,and also ultrasonic motors[1–4].A
istics of plastic materials were improved by the complex new type of converter with multiple slitted parts,for
vibration converter.
improving the vibration characteristics and increasing
The longitudinal and torsional vibration amplitudes the available vibration velocity of the converter,is
of a15mm diameter of a new converter for an ultrasonic studied.The slitted parts are installed in multiple posi-
motor increased to about12m m(peak-to-zero value) tions avoiding longitudinal nodal positions along the
from6m m with a former converter under the same converter for decreasing the maximum vibration stress driving voltage60Vrms at55kHz.
level at the vibration nodal part.Using multiple slitted The converter with multiple slitted parts was found parts,the maximum vibration stress along a converter to be effective for improving the vibration characteristics decreases and the quality factor increases,and the and increasing the available complex vibration velocity. maximum vibration amplitude increases significantly at
the same driving voltage[5].The converter has superior
2.Configurations of vibration converters
*Corresponding author.Tel.:+81-45-481-5661;
Configurations of two examples of the vibration fax:+81-45-491-7915.
E-mail address:tsujino@cc.kanagawa-u.ac.jp(J.Tsujino)converters20mm in diameter and79mm in length,with
0041-624X/00/$-see front matter©2000Elsevier Science B.V.All rights reserved.
PII:S0041-624X(99)00175-4
73
J.Tsujino et al./Ultrasonics 38(2000)72–764.Complex vibration ultrasonic plastic welding
4.1.Vibration characteristics of a complex v ibration con v erters
Fig.2shows the relationship between driving fre-quency and longitudinal and torsional vibration velocity of a complex vibration system with the vibration con-verter (a).The driving voltage is kept constant at 20Vrms.Longitudinal and torsional vibration velocities have maximum values at di fferent frequencies at around 26.3and 26.4kHz.The elliptical locus is obtained at the free edge of the converter.
Torsional and radial vibration velocity distributions at 26.8kHz along a complex vibration converter with Fig.1.Various one-dimensional longitudinal to torsional vibration double slitted parts (a)and (b)are shown in Fig.3.One converters with double slitted parts.
torsional vibration velocity nodal part is within a left slitted area,and the vibration velocities have maximum values at the free edge.
The radial vibration velocity distribution along a slitted parts that were installed avoiding a longitudinal complex vibration converter with double slitted parts
nodal part,are shown in Fig.1.The cylindrical longitu-dinal–torsional vibration converters,made of aluminum alloy (JISA7075B),had two slitted parts on both sides
of a longitudinal vibration nodal part at its circumfer-ence.The converters were driven by a longitudinal vibration source.Various converters with (a)di fferent and (b)the same angle diagonally slitted parts were made in the trials.The vibration converter part had 18diagonal slits of 45or 135°,10mm width and 0.5mm width were cut along its circumference using an electrosparking machine.The slit depth was altered from 1.0to    3.0mm.The free edge part of the converter vibrated longitudinally and torsionally and vibrated in an elliptical locus.
Fig.2.Torsional and radial vibration velocity distributions along com-plex vibration converters (a)and (b).Driving voltage:20Vrms.
3.Vibration characteristics of the converters with two slitted parts
The free admittance loops of the total vibration systems with the converters [Fig.1(a)and (b)]were measured.The quality factor and motional admittance,|Y mo
|,of the vibration system with a converter with di fferent angle slitted parts (a)and the same angle slitted parts (b)were about 600and 30mS under welding conditions of two 1.0mm thick polypropyrene sheets with a static pressure of 890kPa.The admittance loops of the vibration system with the converters show single circular shapes because the resonance frequencies of the longitudinal and torsional vibrations are close.The quality factors and motional admittances of the both Fig.3.Relationship between driving frequency,and longitudinal and systems are large.Elliptical loci were obtained at the torsional vibration velocity of a complex vibration system with a vibra-tion converter (A).Driving voltage:20Vrms.
free edges of the converters.
74J.Tsujino et al./Ultrasonics38(2000)72–76
(a)is also shown in Fig.3(dotted line).A radial and double slitted parts.In the case of the converter
with single slitted part,the slitted part is positioned at vibration velocity maximum position means a longitudi-
a nodal position of the longitudinal vibration along the nal vibration nodal position,and the longitudinal nodal
cylindrical longitudinal–torsional vibration converters. position is positioned between two slitted parts.The
On the contrary,in the case of the converter with two two slitted areas exist out of the longitudinal nodal
slitted parts,the slitted parts are positioned avoiding position where the vibration stress has a maximum value
the longitudinal vibration nodal position.The converter along the converter.
with diagonal slits is driven by a longitudinal vibration
source of two piezoelectric ceramic(lead–zircon–tita-4.2.Welding characteristics of complex v ibration
nate;PZT)disks,15mm in diameter and5.0mm in ultrasonic plastic welding
thickness.The vibration converter slitted part has12
diagonal slits of45or135°and0.5mm in width and10 The relationship between welding time,specimen
or5mm in length,cut by an electrosparking machine deformed thickness at the welded parts and the weld
along the circumference of these converters fabricated strength of the lapped polypropyrene sheets(1.0mm in
from aluminum alloy(JISA7075B).The slit depths of thickness),welded using a27kHz complex vibration
the15mm diameter converter are altered from1.5to system with a converter(a)and(b),is shown in Fig.4.
3.5mm.The free edge of the converter vibrates longitu-The weld strengths obtained by the system with con-
dinally and torsionally and vibrates in an elliptical locus. verter(a)are larger than those with a converter(b).
The PZT longitudinal vibration transducers,a longi-The welding time required becomes shorter using the
tudinal vibration rod with aflange for supporting the vibration system(a)with a larger torsional vibration
motor and a slitted cylinder are clamped by a connecting component.The decrease in specimen deformed thick-
bolt.The driving part of the converter and the rotor ness at the welded parts roughly corresponds to the
part are statically pressed using corned disk springs by obtained weld strength.Specimens were welded in a
a center bolt and nuts.The driving surfaces of the shorter welding time using a complex vibration system
converter(JISA7075B)and the rotor(steel:SKD-61or compared with a longitudinal vibration system.Complex
SK-4:tempered)are ground to beflat and smooth using vibration is effective for ultrasonic welding of plastic
1500–2000mesh polishing powder.
materials as for metal materials.
5.2.Vibration characteristics of15mm diameter
ultrasonic motors
5.Ultrasonic motors with a longitudinal–torsional
converter
The longitudinal and torsional vibration amplitudes
at the free edge of these converters were measured by 5.1.Configuration of ultrasonic motors two laser Doppler vibrometers when the driving fre-
quency was altered.These converters have near-reso-The configurations of the ultrasonic motors an
d nance frequencies of the longitudinal and torsional vibration converters,15mm in diameter,are shown in vibrations similar to Fig.2.The largest longitudinal Fig.5.Fig.5(a)and(b)show the configurations of vibration amplitudes of the converter of single and two 15mm diameter motors using a converter with single slitted parts without a rotor part were about6and
12m m(peak-to-zero value)at frequencies of50–55kHz.
The largest longitudinal vibration amplitudes of these
converters with a rotor part are about3and9m m at
frequencies near to55kHz.The largest vibration ampli-
tudes of a converter with double slitted parts are about
two to three times compared with the amplitudes of a
converter with single slitted part.
5.3.Vibration loci at the dri v ing surface of the con v erter
In these cases,the longitudinal vibration is partially
converted to torsional vibration at the slitted parts,and
the cylinder part of the converter vibrates longitudinally
and torsionally.The vibration locus at the free edge is
determined by the vibration phase difference between Fig.4.Relationship between welding time,deformed weldment height
these vibrations.Vibration loci at the driving surfaces and weld strength of the lapped polypropyrene sheets(1.0mm in thick-
of longitudinal–torsional converters were measured ness),welded using a27kHz complex vibration system with a converter
(a)and(b).using two laser Doppler vibrometers(~20MHz)that
75
J.Tsujino et al./Ultrasonics38(2000)72–76
Fig.5.Configurations of15mm diameter ultrasonic motors using a longitudinal–torsional vibration converter with single slitted part(a)and double slitted parts(b).
detect longitudinal and torsional vibrations indepen-length of the ultrasonic motor of15mm diameter in the dently.The vibration locus is shown on a digital memory
driving frequency55.1kHz(without a rotor)and oscilloscope screen as a Lissajousfigure.Fig.6shows54.26kHz(with a rotor).The vibration locus amplitude the vibration loci at the driving surfaces of converters
at the driving surfaces of converter decreases slightly with double slitted parts of3.3mm depth and5mm when the ultrasonic motor rotates.
Fig.6.Vibration loci at a driving part of a15mm diameter converter with and without a rotor part.
76J.Tsujino et al./Ultrasonics38(2000)72–76
6.Conclusion materials.The15mm diameter ultrasonic motor,
together with a converter with double slitted parts, For increasing the available vibration velocity of the
rotated at over300rpm.
complex vibration converter,a new type of converter The converters with multiple slitted parts were found with multiple slitted parts was studied.
to be effective for improving the vibration characteristics This converter has multiple slitted parts that are and increasing the available complex vibration velocity. installed in multiple positions,avoiding nodal positions
along the converter for decreasing the maximum vibra-
tion stress level at the vibration node part.The welding
References
characteristics of ultrasonic plastic welding using com-
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Takeuchi,Proc.Int.Congress on Acoustics(1995)447–450.. parts were tested.
[2]J.Tsujino,Proc.IEEE1995Ultrasonics Symp.,IEEE,New York,
The longitudinal vibration nodal part was located
1996,pp.1051–1060.
between two slitted parts of the converters.The driving[3]J.Tsujino,T.Uchida,K.Yamano,T.Iwamoto,T.Ueoka,Proc. surface of the converter and the ultrasonic motor with
2nd World Congress on Ultrasonics,Yokohama,Japan(1997)
152–153.
double slitted parts vibrated at higher vibration velocities
[4]J.Tsujino,T.Uchida,K.Yamano,T.Iwamoto,T.Ueoka,Proc. than those with a single slitted part at the same driv-
IEEE1997Ultrasonics Symp.,IEEE,New York,1998, ing voltage.
pp.855–860.
The converter with double slitted parts significantly[5]J.Tsujino,T.Ueoka,Proc.IEEE1999Ultrasonics Symp.,IEEE, improved the ultrasonic welding characteristics of plastic
New York,1999,pp.723–728.

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