- Introduction
- FM: Sweep and Dual Sweep
- Ultrasonic Power Into a Tank
- FM: Upsweep
- Multiple Frequencies (1)
- Multiple Frequencies (2)
- Cavitation
- Transducer Impedence (1)
- Transducer Impedence (2)
- Transducer Impedence (3)
- Universal Transducer
- Applying the Technology (1)
- Applying the Technology (2)
- Applying the Technology (3)
- Conclusion
|
 |
Designer Waveforms: Ultrasonic Technologies to Improve Cleaning and Eliminate Damage
(p. 11)
previous pagenext page
Universal Transducer
The figure 8 curve is an optimized universal transducer for a multiple frequency system. The transducers forming this array consist of an aluminum front driver, two back-to-back piezoelectric ceramics, a steel back mass, a compression bolt and appropriate electrodes. It differs from the most numerously produced Langevin type transducers in that it has a cone shaped back mass and the metric compression bolt threads into the steel back mass rather than into the aluminum front driver. The first change helps flatten the impedance curve and the second maintains compression because the steel threads deform elastically during operation rather than the plastic deformation that occurs in aluminum threads. The relatively flat impedance versus frequency curve combined with a properly designed generator characteristic puts about the same power into the liquid at every different center frequency (i.e., 40 kHz, 72 kHz, 104 kHz and 170 kHz), and keeps this power relatively constant at the infinite number of frequencies contained in the four kilohertz bandwidths around each of the center frequencies. Therefore, the amplitude modulation (AM) pattern resulting from this type of transducer array is rectangular in nature (i.e., each frequency along the frequency spectrum is delivered with nearly equal power).
The advantages and disadvantages of the rectangular AM pattern of the figure 8 system are the opposite of those for the power impulse system of figure 7. The elimination of damage caused by power spikes increases part yield and the benefits of the cleaning effects in the multiple frequency ranges improves part cleanliness.
previous pagenext page
|
