预紧组合结构液压机临界预紧力的研究

Study on Critical Preload of Prestressed Composite Structure Hydraulic Press

预紧组合结构广泛应用于大型液压机本体设计,预紧力的确定是其关键问题。针对锻造液压机,尤其是自由锻液压机经常处于偏心载荷工况这一问题,在现有的偏载工况机架受力分析模型的基础上,进一步引入预紧力,建立了液压机机架临界预紧力的计算模型,并以三缸双球铰液压机为例,推导了其临界预紧力计算公式。设计制造了以某厂120 MN三缸双球铰自由锻造液压机为原型的1∶15的本体模型,并对该液压机处于不同工作载荷、偏心距分别为10 mm和30 mm工况下机架保持整体性所需的临界预紧力进行了实验测试。实验结果表明,所提的临界预紧力计算方法具有一定的可靠性,但该值偏安全。

The prestressed composite structures are widely used in the body design of heavy hy-draulic press.How to determine the appropriate preload is a crucial issue.A calculation model of crit-ical preload of hydraulic press frame was built with consideration of preload,for the hydraulic forging presses,especially the hydraulic free forging presses,under eccentric loads,on the basis of existing analysis model.Taking the three-cylinder and double-spherical j oints hydraulic press as an example, the formula of critical preload was derived.To verify the formula,the critical preloads of a body mod-el were tested experimentally,which was designed and manufactured at a ratio of 1：1 5 based on 120 MN hydraulic press,under different loads and offsets （10 mm and 30 mm）.The results show that critical preloads calculated by the method herein are consistent with experimental values.