高速凸轮机构动力学分析与设计理论及应用研究-机械工程专业毕业论文.docx

天津工业大学
硕士学位论文
高速凸轮机构动力学分析与设计理论及应用研究
姓名:魏展
申请学位级别:硕士
专业:机械工程
指导教师:金国光
201112
摘要
高速凸轮机构是机械系统中比较常用的一种机构,对其进行深入系统的动力学研究具有重要的学术意义和工程实用价值。本学位论文基于有限元法对凸轮机构柔性构件进行离散化处理,并依据Kane方程建立了高速凸轮机构的动力学方程。为保证动力学方程的通用性,采用了6个自由度的平面梁单元。得到的凸轮机构动力学方程是一个更具一般性的柔性梁类动力学方程,只要构件经有限元离散化处理后,其单元仍为“梁单元", 则该动力学方程仍然成立。
建立高速凸轮机构的动力学模型,并简化为单自由度动力学模型。求得该模型的动力学方程,进而推算出凸轮轮廓线设计方程。得到的高次多项式曲线光滑而无冲击,满足凸轮高速运转时的动力学特性要求。
应用所建模型对实例进行仿真。对高速凸轮从动件动态响应进行研究,为更精确地设计高速ffll轮机构提供了可能;对凸轮与滚子间接触力的仿真研究可判断滚子间歇性脱离现象,也为弹簧弹性系数和外载荷进行优化设计‘提供了理论依据:采用模态截断法可判断实际应用的中的高速凸轮系统是否需要进行动力学分析;对凸轮廓线的仿真设计为凸轮机构现代化生产提供了数据支持。
关键词:高速凸轮有限元模态柔性构件动力学
Abstract
H igh—speed cam is monly used as a body in mechanical system,an in·depth and overall dynamics study has important academic significance and practical this dissertation,Flexible elements of cam mechanism for
discretization has been done according to ,the modal-coordinates dynamic equations of cam mechanisms are established based on Kane’S ensure the generality of the dynamic equation,Six degrees of freedom plane beam element is the equation is a more general dynamic
equations of flexible beam type dynamic equation,as long as the unit is still”beam
element“after the treatment of finite-element discretization,the dynamic equation stilI holds.
In order to design a smooth and higher-degree polynomial curve for satisfying the need of dynamic features of high-speed cam,the dynamic model of cam mechanism is simplified into a single—flee-of-degree dynamic dynamic equation in this model can be used to establish the design equation of the cam profile. The curve obtained from calculation is smooth and can satisfy the requirement of dynamics characteristics.
Some typical cam mechanisms are used as simulating examples to validate these dynamic model the dynamic response of the cam follower,and more accurate design for the high—speed cam mechanism will be more easily. Simulation research of the contact forc