回转副精度特性的弹性冗余空间机构模型

A Novel Precision-characterization Model of a Revolute Joint Based on the Concept of Spatial Mechanisms with Redundant Elastic Constraints

提出回转副精度特性的弹性冗余空间机构模型,将实际回转副中的弹性约束等效映射为多个从动件弹性冗余支承,实际回转副零件的几何误差特性等效映射为刚性凸轮轮廓曲面,形成以多组从动件弹性悬浮刚性凸轮几何轮廓的弹性冗余空间机构,从而较真实地反映实际回转副结构及其零件的几何、运动、材料物理性质与工况载荷特性等因素的耦合关系。建立弹性冗余空间凸轮机构的几何位移基本方程、静力平衡方程、物性方程,将回转副精度及其随位置和载荷变化的特性转化为弹性冗余空间机构的位移分析与静力分析求解问题,并给出典型回转副精度特性计算分析与试验测试对比示例,为机器精度分析与设计提供新的理论基础,也为机构学理论开辟新的应用领域。

A novel approach,based on the concept of spatial mechanism with redundant elastic constraints is presented to set up a comprehensive precision-characterization model of an actual revolute joint.When considering component flexibility and manufacturing errors,the shaft in an actual revolute joint can move in a much more complex manner in comparison with an ideal revolute joint with only one rotational degree of freedom.In the proposed model,the rigid cams with special profiles are used to represent the geometrical error,springs are used to describe the deformations of joint components and surfaces in actual machine parts.The spatial cams,suspended by multiple straight-followers with springs,called an RE mechanism,is proposed to simulate the kinematics of the shaft in the revolute joint.The basic model equations,such as kinematic equations,equations of equilibrium,and equations of physical properties are concisely derived.With the proposed model,the precision of an actual revolute joint and its load-dependent properties can be seen as the solutions of the basic equations of a corresponding RE mechanism.An example is presented to illustrate the solution process of the precision model of a revolute joint,and numerical results were compared with the experimental results obtained from the corresponding test setup.The proposed model provides for the first time a theoretical basis for joint precision analysis and synthesis.This opens up a new application of the theory of mechanism in design of machine components.