液压系统弹簧刚度动态变化下的压力冲击余弦级数研究

分析了油液含气量和液压缸活塞位移对液压油的有效体积弹性模量和液压缸等效动态弹簧刚度的影响，利用余弦级数计算出压力冲击的作用时间，并利用AMESim仿真软件验证所求时间的准确性。在此基础上利用动量定理推导出了压力冲击的计算公式，并求出了压力冲击的数值大小。研究结果表明，液压缸的等效动态弹簧刚度和油液中的含气量是影响压力冲击数值大小的主因，因此在设计液压系统时，可以降低油液中的含气量，提高液压缸的等效动态弹簧刚度来确保系统的稳定。以国内某钢厂的全液压双边滚切剪作为实验对象，由于数据采集的时间间隔为0.5 s/次，在出现压力冲击的时候数值没采集到，但是通过现场油管爆裂来看是有冲击产生的。通过分析理论推导与所采集到的压力冲击的大小，得出误差在11.12%左右，验证了理论推导的正确性。

Pressure Shock Cosine Series Under Dynamic Change of Spring Stiffness for Hydraulic System

The influence of air content in oil and piston displacement of hydraulic cylinder on effective bulk elasticity modulus of hydraulic oil and equivalent dynamic spring stiffness of hydraulic cylinder is analyzed. The cosine series is used to calculate pressure shock time, and the software AMESim is used to verify accuracy of the time required. Based on this, a pressure shock formula is deduced and a numerical value of pressure shock is calculated by the momentum theorem. The results show that equivalent dynamic spring stiffness of hydraulic cylinder and air content in the fluid are the main factors that affect the magnitude of pressure shock. Therefore, when a hydraulic system is designed, we can reduce the air content in the fluid and improve the equivalent hydraulic cylinder dynamic spring stiffness to ensure system stability. Taking a full-hydraulic bilateral hobbing cutter made by a steel mill in China as the experimental object, we have no time to collect the numerical value when pressure shock occurs due to the large time interval of data collection, but an impact in view of burst on site is produced. Comparing theoretical derivation with magnitude of the pressure shock collected, we obtain that the error is about 11.12%, which verifies the correctness of theoretical derivation.