Abstract: A wedge-shaped vibration-transmitting plate is located between the bottom wall of a cleaning tank and an ultrasonic transducer which is operable to produce vibratory energy in a liquid bath in the tank. The wedge-shaped plate diversifies the phase of initially in-phase energy waves produced by the transducer and causes waves of different phase to propagate upwardly through the liquid. As a result of the phase diversification, the concentration of high and low power levels at various depths in the bath is reduced so that cleaning action over the span of the vertical dimension is more uniform. In addition, the overall action of wave reflection at the upper surface of the bath fluctuates through a smaller range when the depth of the bath changes. This enables the transducer to be energized with a more stable input power.

Abstract: Metal pipe is planished by passing it longitudinally between two concentric circular arrays of independently rotatable planishing elements which are urged against the inner and outer surfaces of the pipe. The two circular arrays of planishing elements are radially aligned with each other on opposite sides of the pipe wall, and the pipe is rotated relative to the two arrays of planishing elements while the pipe is being passed therebetween.