Principle Of Operation; The Welding System; The Power Supply; The Converter - Branson 900IW+ Series Operator's Manual

900IW Series Integrated Welders
C.1 Principle of Operation
Thermoplastic parts are welded ultrasonically by applying high frequency
vibrations to the parts being assembled. The vibrations, through surface
and intermolecular friction, produce a sharp rise in temperature at the joint
where the parts meet.
When the temperature is high enough to melt the plastic, there is a "flow"
of material between the parts. When the vibrations stop, the material
solidifies under pressure and a uniform weld results.
Most plastics welders operate at a frequency above the range of human
hearing (18 kHz) and are thus called ultrasonic.
C.2 The Welding System
The intergrated welder is a self-contained ultrasonic plastic welding
system. It consists of a welding stand and an enclosure housing a power
supply, controls, indicators, and a converter-booster-horn stack. The
system can perform ultrasonic welding, inserting, staking, spot welding,
swaging, degating, and continuous ultrasonic operations. It is designed for
automated, semi-automated and/or manual production units.
C.2.1 The Power Supply
The power supply converts conventional 50/60 Hz line current to 20 kHz
electrical energy. It contains all the electronic controls.
C.2.2
The Converter
The 20 kHz electrical energy from the power supply is applied to the
converter or transducer element. This transforms the high frequency
electrical oscillations into mechanical vibrations at the same frequency as
the electrical "vibrations." The heart of the converter is a lead zirconate
titanate electrostrictive element. When subjected to an alternating voltage,
this element expands and contracts, resulting in better than 90% energy
conversion.
Theory