Research on the Crawling Mechanism of Giant Hydraulic Press at a Low-Speed Running State

This paper studied on the giant die forging machine´s nonlinear dynamic characteristics at the low speeds through theoretical analysis and experimental verification. In the discussion of hydraulic cylinder, the author cited the Stribeck nonlinear friction and came up with an idea that oil pressure fluctuation can lead to a crawling phenomenon. stribeck nonlinear friction can generate limit cycle oscillations which could impact hydraulic press´s stability at a low-speed state at the same time the oil pressure fluctuation can be fitting by cubic curve whose role is similar to a nonlinear spring. When the pressure fluctuated, it worked as a hard spring or soft spring, and then it would cause a phenomenon that speed would sudden jump up or down. So, giant hydraulic machine´s crawling is caused by fluctuated pressure and nonlinear friction.