Abstract
The response of a hydraulic copying system degrades when input frequency increases beyond the break frequency of the system. Providing another flow input directly to the power cylinder of the copying system, the output displacement can be improved in a frequency range between the break frequency and the natural frequency of the hydraulic copying system. A new dislacement type flow generator was invented to supply the flow input, and combined with a hydraulic copying system. The new copying system was applied to turn an elliptical piston of automobile engines, where a fast reciprocating motion of cutting tool is generally required. The static and dynamic characteristics of the device coincided well with the theory in this paper. The results of machining were sufficiently accurate in all of test runs over half a year.
