12-07-2013, 04:55 PM
Welding Characteristics of 90 kHz Two-Vibration- System Ultrasonic Plastic Welding Equipment
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ABSTRACT
Direct and transmission welding characteristics of
an ultrasonic plastic welding system using 90 kHz
upper and lower vibration systems are studied. By
using high frequency and two-vibration-system
welding equipment, the welding characteristics are
improved, resulting in smaller required vibration
amplitude and less damage caused by vibration in
the specimens than those of conventional systems.
The 90 kHz welding equipment consists of two
vibration sources using six bolt-clamped Langevintype
piezoelectric ceramic (lead-zircon-titanate;
PZT) transducers of 15 mm in diameter and a
welding frame. The required velocity for a 90
kHz welding system is about 30% that of a 27 kHz
system in the case of direct welding. In the case of
transmission welding, the required sum of
vibration velocities of upper and lower welding tips
is less than that of one welding tip system.
INTRODUCTION
Welding characteristics of an ultrasonic plastic
welding system using 90 kHz upper and lower
vibration systems, whose frequencies are higher
than that of conventional systems of 15 to 40 kHz,
are studied.
The ultrasonic plastic welding method is
applicable for joining almost all thermoplastic
materials due to its short welding time without
adhesive and is used widely to join thermoplastic
products which are difficult to join by microwave
joining due to their low dielectric loss.
The ultrasonic plastic welding method using two
vibration systems was proposed by the author for
improving its welding characteristics, and its
effectiveness was shown in the cases of the same or
different vibration frequencies of 20 kHz and 27
kHz which are the same as in the ultrasonic metal
welding method with two vibration system also
proposed by the author [ 1]-[3].
Weld conditions of direct welding using 27
kHz and 90 wiz systems
Direct welding conditions of thin lapped sheets
using a 90 kHz welding equipment with two
vibration systems are shown in Fig.4. Critical
welding conditions are determined by altering
vibration velocities of upper and lower welding
tips. Required weld conditions are determined as
the sum of upper and lower welding tips because
the obtained curves are linear[3]. As static pressure
increases, required welding tip total vibration
velocity decreases. Direct welding conditions of
lapped sheets using 27 kHz and 90 kHz welding
equipments is shown in FigS.
CONCLUSIONS
Welding characteristics of ultrasonic plastic
welding using 90 kHz upper and lower vibration
systems were studied. The 90 kHz welding
equipment consists of two vibration sources with
almost equal vibration characteristics using six boltclamped
Langevin-type PZT transducers of 15
mm in diameter and a welding frame.
These vibration sources are driven independently
by two controlling systems and 500 W power
amplifiers.