Yonghui Park - Department of Mechanical Engineering, Yuhan University, ۵۹۰, Gyeongin-ro, Bucheon-si, Gyeonggi-do, Republic of Korea
Changwoo Lee - Steel-pipe Technology Team, Pohang Institute of Metal Industry Advancement, ۵۶, Jigok-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do, Republic of Korea

To learn the dynamic characteristics of a mold oscillator, we establish a model that describes the relationship between force equilibrium of a hydraulic cylinder and mold under various oscillation conditions. The non-linearity caused by the servo-value and the operating fluid is considered as excitation, and is calculated as control error between an input signal and mold oscillation in real-time by a PID control process. Based on the non-linear property, we determine that the dynamic behavior is caused by mold oscillation displacement and hydraulic cylinder pressure. We define excitation frequency and harmonic terms, and determine that the sources of the harmonic peak frequency and high peak frequency; (۵۰n ± exciting frequency ωexc) are friction between the piston and hydraulic cylinder, and variable stiffness of the operating fluid. Finally, a mathematical model of the hydraulic chamber that can represent the unknown non-linear phenomenon is derived.

Dynamics, mold oscillator, hydraulic cylinder, beat phenomenon