液压冲击锤瞬态冲击动力特性分析

Analysis of Dynamic Characteristic of Transient Impact from Hydraulic Hammer

基于弹性体一维振动瞬态应力波传播理论,建立了液压冲击锤活塞与钎杆冲击过程的双柔性杆共轴纵向碰撞计算模型.应用瞬态波函数特征值展开法求解冲击过程中各冲击部件的位移-时间瞬态响应函数,进一步分析了冲击过程中钎杆和活塞的应力波传播规律及各截面的冲击动力特性.文中还分析了液压冲击锤在不同钎杆长度、钎杆直径及活塞初始冲击速度下对冲击部件冲击过程瞬态动力响应的影响.钎杆长度变化对冲击过程撞击力影响不大,随着钎杆长度变短,活塞进入反弹的时间加快;钎杆直径增大时,撞击力幅值增大,破碎能力增强,冲击能量利用率降低;活塞初冲速度增大时,撞击力成比例增大,冲击锤破碎能力迅速提升.文中结果可为优化液压冲击锤系统结构、合理设计冲击破碎性能、合理调节冲击施工参数提供理论依据.

On the basis of the transient stress wave propagation theory of one-dimensional vibration elastomer,a model is constructed to calculate the coaxial longitudinal collision of double flexible rod during the impact of hydraulic hammer drill rod on the corresponding piston. Then,the displacement-time transient response impact function of each impact part is solved by means of the eigenvalue expansion method of transient wave function,and the stress wave propagation rules of both the drill rod and the piston as well as the dynamic characteristics of each crosssection of both the drill rod and the piston are analyzed. Furthermore,the transient dynamic responses of impact parts with different drill rod lengths and diameters as well as with different initial speeds of piston are discussed.The results indicate that（1） drill rod length slightly affect the impact force and a short drill rod may result in a fast rebound of the piston;（2） with the increase of drill rod diameter,the impact force amplitude increases and the crushing ability improves,which means a relatively low energy efficiency; and（3） with the increase of the initial piston speed,the impact force proportionally increases and the crashing ability of hydraulic hammer greatly improves. These results can provide a theoretical basis for an optimization of the structure and performance of hydraulic hammers as well as a reasonable adjustment of construction parameters.