基于键合图的环切机构动力学建模及其非线性振动研究

Dynamic Modeling and Nonlinear Vibration Research of the Rotary Cutting Mechanism Based on Bond Graphs

管道切口端面的质量是保障管路系统安全运行的重要因素之一,但在管道切削过程中存在非线性因素,可能会导致切管机发生混沌、拟周期等有害振动,从而影响切削精度和加工质量。因此,揭示切管机动力学失稳的机制以避免有害振动是改善运转性能、提高切削精度的关键。以一种刀旋式切管机的环切机构为对象,基于键合图理论建立了机构的动力学模型,通过计算灵敏度确定了关键动力学参数,并综合应用分岔图、Lyapunov指数图、相图、时间响应图等,揭示了关键参数的分岔机制。结果表明,随着激励幅值、激励频率和基座弹性系数等参数的变化,系统会存在倍周期分岔、Hopf分岔、混沌和吸引子共存等复杂动力学行为,从而产生严重降低切削质量的振动和运动突变。研究结果可为该机构后续动态性能优化和有害振动抑制提供参考。

The quality of the cut end surface of pipelines is one of the important factors to ensure the safe operation of the pipeline system.However,the existence of nonlinear factors in the pipeline cutting process may lead to chaos,quasi-periodic and other harmful vibration of the pipe cutting machine,which may affect the cut-ting accuracy and quality.Therefore,revealing the mechanism of dynamic instability of the pipe cutting machine to avoid the harmful vibration is the key to improve the operation performance and cutting accuracy.In this study,the dynamic model of the rotary cutting mechanism of a rotary pipe cutter is established based on the bond graph theory,the key dynamic parameters are determined by calculating the sensitivity,and the bifurcation mechanism of key parameters is revealed comprehensively by using the bifurcation diagram,the Lyapunov expo-nent diagram,the phase diagram and the time response diagram.The results show that with the changes of the excitation amplitude,the excitation frequency and the elastic coefficient of the base,complex dynamic behaviors such as the period-doubling bifurcation,Hopf bifurcation,the chaos and the coexistence of attractors will exist in the system,resulting in vibration and sudden change of the motion that seriously reduce cutting quality.The results provide reference for the subsequent dynamic performance optimization and vibration suppression of the mechanism.