Research on an Efficient Noncontact Power Transfer Method for Elliptical Ultrasonic Tool Holders

Le résumé fourni par la source

The elliptical ultrasonic tool holder (EUTH) is a critical core component in elliptical ultrasonic vibration-assisted milling. Traditional EUTH employ conductive slip rings for power transmission, which severely restricts milling speed. This study investigates an efficient non-contact power transfer method for EUTH, utilizing a dual-channel rotary transformer to replace conductive slip rings. Electrical energy is transferred through air coupling between the primary and secondary sides of the rotary transformer, and this frictionless power transmission method eliminates limitations on milling speed. A finite element model (FEM) of the elliptical ultrasonic transducer was used to analyze its modal shape, impedance, and resonant frequency temperature drift characteristics, thereby determining the transducer's resonant frequency, vibration amplitude, and node positions. The rotary transformer was designed using ferrite core material with high magnetic permeability and low electrical conductivity to reduce eddy current losses. An equivalent circuit model of the EUTH was established, and compensation circuits were designed to improve the efficiency of non-contact power transfer. A dual channel ultrasonic generator (DCUG) was developed using a Class D amplifier, enabling adjustable voltage amplitude, phase, and frequency. A Fuzzy-PID algorithm was implemented to achieve automatic resonant frequency tracking for the DCUG. Finally, a milling platform was set up to conduct elliptical ultrasonic vibration-assisted milling experiments, where the DCUG drove the EUTH. Experimental results show that below 40 kHz, the maximum driving voltage of the dual-channel ultrasonic generator reaches 300Vp-p, while the elliptical vibration displacements at the tool tip in the X and Y directions are both approximately 20μmp-p. The output amplitude current remains stable, and the system automatically tracks the resonant frequency of the EUTH during milling. This provides an effective method for achieving high-efficiency non-contact power transfer in EUTH.

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