Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

Optimization of Hopkinson Bar Structure for Measuring Discharge Reaction Force in WEDM

Wenting Gu1,2,a, Masanori Kunieda2 and Wansheng Zhao1

1School of Mechanical Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China

2 Department of Precision Engineering, The University of Tokyo, 7-8-1, Hongo, Bunkyo-Ku, Tokyo, 113-8654, Japan


There is an inevitable problem that limits the improvement of machining accuracy in wire electrical discharge machining (WEDM), that is vibration of wire electrode caused by kinds of force accompanying discharge process. It is known that discharge reaction force is one of the most influential forces, which is formed by the oscillation of discharge bubble. However, it is difficult to measure the discharge reaction force itself directly because of properties of wire electrode such as tiny surface and low rigidity. In this study, a novel force measurement method was proposed based on Hopkinson bar measurement theory. In the novel force measurement setup, the end structure of the Hopkinson bar was designed to be smaller than the cross-section area of the bar trunk, aiming to measure the discharge reaction force acting on the end of the Hopkinson bar without large disturbance to the discharge gap phenomena. To explore the best structure of the Hopkinson bar, models built in COMSOL Multiphysics software were elaborated according to the theory of elastic wave. The propagations of the stress wave in different designs were analyzed. Finally, the optimal design was found to enable the stress wave to propagate without a large loss of energy.

Keywords: Hopkinson bar structure, Optimal design, Discharge reaction force, Simulation study, WEDM

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