不同支撑方式的滚珠丝杠进给系统静/动刚度分析

Analysis of static and dynamic stiffness characteristics of two type of ball screw feed systems with different support modes

滚珠丝杠进给系统是数控机床的重要组成部分,其静/动刚度对机床性能和稳定性有重要影响。在工作过程中,滚珠丝杠进给系统的静/动刚度随行程变化而变化。为研究不同支撑方式的滚珠丝杠进给系统静/动刚度特性,采用集中参数法,搭建系统动力学模型,开展行程范围内系统静/动刚度变化规律研究,并关注工件的质量和放置位置对系统静/动刚度的影响。结果显示:负行程中,随着行程增加,两端固定支撑的系统静/动刚度先减小后增大;一端固定一端浮动支撑方式的系统静/动刚度持续减小,且两者相比,两端固定支撑的系统动刚度对工件的质量和放置位置更为敏感,即固有频率变化相对较大。结果可用于指导滚珠丝杠进给系统的优化设计以及工作过程中工件的质量和放置位置的选择。

Ball screw feed system is an important part of CNC machine tool,and its static/dynamic stiffness has an important effect on the machine tool performance and stability.In the working process,the static/dynamic stiffness of the ball screw feed system changes with the stroke.In order to study the static/dynamic stiffness characteristics of the ball screw feed system with different support modes,the lumped mass method was used to establish a dynamic model,and the static/dynamic stiffness variation of the system within the stroke was studied.The influence of the mass and placement of the workpiece on the static/dynamic stiffness of the system was also concerned.The re`sults show that in the negative stroke,the static/dynamic stiffness of the system with fixed supports at both ends decreases first and then increases with the increase of stroke;the static/dynamic stiffness of the system with one end fixed and one end floating support decreased continuously.Compared with the two,the dynamic stiffness of the system with two ends fixed support was more sensitive to the mass and placement of the workpiece,that is,the natural frequency changed relatively large.The results can be used to guide the optimal design of the ball screw feed system and the selection of the mass and placement of the workpiece during the working process.