曲柄群机构的受力模型及曲柄布置形式分析

曲柄群机构为含有过约束的平面杆机构。根据该机构的特点,建立了曲柄群机构中各运动构件的静平衡方程,并以曲柄的轴向变形构造变形协调方程,建立了含有任意多曲柄的曲柄群机构的动态静力分析模型。通过一个算例验证了该方法的有效性和便捷性,为分析其他类型含过约束杆机构的受力提供参考。以含3个曲柄的曲柄群机构为例,分析了曲柄的不同布置形式对曲柄群机构受力的影响。结果表明,对于含3个曲柄的曲柄群机构,将两个从动曲柄关于主动曲柄对称布置能大幅降低曲柄群机构的受力峰值,分析结果为曲柄群机构的结构设计及尺寸选择提供理论依据,为进一步研究受力的影响因素奠定基础。

Force Model for Crank Group Mechanism and Analysis of Crank Arrangement

Crank group mechanism is a planar bar mechanism with over constraint. According to the characteristics of the mechanism,the static equilibrium equations of each motion component in crank group mechanism are established. And dynamic static force analysis model of crank group mechanism containing any crank is established based on deformation coordination equation from the axial deformation of the crank.A numerical example is given to illustrate the effectiveness and convenience of the method. Influence of different arrangement of crank on the force of crank group is analyzed,taking crank group mechanism with 3 cranks as an example. The results show that the maximum force peak of crank group mechanism can be greatly reduced by the symmetrical arrangement of 2 driven crank on active crank for the crank group mechanism with 3 cranks. The analysis provide a theoretical basis for the structural design and size selection of crank group mechanism,and lay the foundation for further study of factors affecting force.