STUDY OF A MICRO FEEDING TOOL HOLDER WITH BELLOWS-TYPE DISPLACEMENT AMPLIFICATION MECHANISM

摘要

In this study, a micro feeding tool holder with a displacement magnification mechanism is provided for improving the feeding resolution of an existing ultraprecision machine. The tool hold is actuated by the piezoelectric actuator, and the feeding stroke is amplified by a bellows-type hydraulic device with two different cross-sectional areas. Due to the nature of incompressible liquid in the closed chamber of the hydraulic device, the tiny displacement of the PZT actuator can be amplified based on the area ratio of the two bellows. In this paper, detail design of the tool holder is described and fundamental characteristics are presented. According to the experimental results, a maximum displacement of 54.35 μrn was obtained with a displacement amplification ratio of 4.4 when the PZT actuator was excited by an applied voltage of 100 V. In addition, the feeding resolution was examined as less than 10 nm, and the stiffness and natural frequency of the tool holder were obtained as 1.42 N/μm and 150 Hz, respectively. Based on the experimental examinations, it is confirmed that the tool holder can be applied to practical machining process.