计及运动副间隙的双曲柄六杆压力机机构动力学仿真向量键合图法

A vector bond graph method for dynamic simulation of double crank six-bar press mechanism with joint clearance

针对计及运动副间隙的双曲柄六杆压力机机构动力学仿真问题,提出了相应的向量键合图法。基于修正非线性连续接触碰撞力的混合模型,推导出间隙运动副的相对碰撞速度向量方程。在此基础上,建立了可以更精确描述间隙运动副的向量键合图模型,具有通用性强、模块化的特点,便于嵌入到系统的向量键合图模型中。由机构运动副的约束关系,将各构件的向量键合图模型相互键接,建立了计及驱动电机、运动副间隙的双曲柄六杆压力机机构向量键合图模型。应用相应的方法,使机构向量键合图模型的贮能元件皆具有积分因果关系,实现了计及驱动电机、运动副间隙的双曲柄六杆压力机机构计算机建模及动力学仿真。在此基础上,分析了运动副间隙对压力机机构运动学及动力学性能的影响,验证了所述方法的可靠性及有效性。通过与无质量弹簧阻尼运动副间隙模型的计算对比,进一步表明该方法可以提高系统动力学仿真的精度及实用性。

For the dynamic simulation of double crank six-bar press mechanism with joint clearance,the corresponding vector bond graph procedure was proposed.Based on an improved hybrid nonlinear continuous contact and collision model,the vector equation for relative collision velocity of joint clearance was derived.Based this,a vector bond graph model describing joint clearance more accurately was made,which possesses modular and universal characteristics and is suitable for embedding into the system vector bond graph.From the constraint relations of mechanism kinematic pairs,the vector bond graph model of double crank six-bar press mechanism with joint clearance driven by an electric motor was made by bonding vector bond graphs of mechanism components.By the corresponding method,all the energy storage elements of the mechanism vector bond graph possessed integral causality,and the computer modeling and dynamic simulation of double crank six-bar press mechanism with joint clearance driven by the electric motor was realized.Based on this,the influence of joint clearance on kinematic and dynamic character of press mechanism was analyzed,and the reliability and validity of the procedure proposed were illustrated.Finally,by comparing with the calculated results of the joint clearance model of the mass-less spring damping,it is further clarified that the method presented in this paper can improve the accuracy and practicability of system dynamic simulation.