100-412-234 REV. 06 19
The Pneumatic System
The pneumatic system included on the 2000Xc Power Supply model is contained within
the actuator’s sheet-metal enclosure and consists of solenoid valves, an air cylinder, and a
pressure regulator. The horn’s rate of descent is adjusted by the Downspeed control in the
power supply control panel. The rate of return is fixed. For information on setting the
Downspeed control, see 2.5 Actuator Controls and Indicators
2.1.5 The Ultrasonic Stack
Converter
The converter is mounted in the actuator as part of the ultrasonic stack. The ultrasonic
electrical energy from the power supply is applied to the converter (sometimes called the
transducer). This transforms the high frequency electrical oscillations into mechanical
vibrations at the same frequency as the electrical oscillations. The heart of the converter
are piezoelectric ceramic elements. When subjected to an alternating voltage, these
elements alternately expand and contract, resulting in better than 90% conversion of
electrical to mechanical energy.
Booster
Success in ultrasonic assembly depends on the right amplitude of movement at the horn
face. Amplitude is a function of horn shape, which is largely determined by the size and
form of the parts to be assembled. The booster can be used as a mechanical transformer
to increase or decrease the amplitude of vibrations applied to the parts through the horn.
The booster is a resonant half-wave section of aluminum or titanium. It is mounted
between the converter and the horn, as part of the ultrasonic stack. It also provides a
clamping point for rigid stack mounting.
Boosters are designed to resonate at the same frequency as the converter with which they
are used. Boosters are usually mounted at a nodal (minimum vibration) point of axial
motion. This minimizes the loss of energy and prevents vibration from being transmitted
into the actuator.
Horn
The horn is selected or designed for a specific application. Each horn is tuned typically as
a half-wave section that applies the necessary force and vibration uniformly to the parts to
be assembled. It transfers ultrasonic vibrations from the converter to the workpiece. The
horn is mounted to the booster as part of the ultrasonic stack.
Depending on their profile, horns are referred to as stepped, conical, exponential, bar, or
catenoidal. The shape of the horn determines the amplitude at the face of the horn.
Depending on the application, horns can be made from titanium alloys, aluminum, or
steel. Titanium alloys are the best materials for horn fabrication due to their high level of
strength and low loss. Aluminum horns are usually chrome- or nickel-plated or hard-
coated to reduce wear. Steel horns are for low amplitude requiring hardness, such as
ultrasonic insertion applications.
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