瞬心无穷远时近似直线轨迹的四杆机构综合  

SYNTHESIS OF FOUR-BAR APPROXIMATE STRAIGHT-LINE LINKAGE WITH INFINITELY FAR INSTANT CENTER

作　　者：王忠[1] 朱洪俊[1] 廖磊[1] 杨玉民[1] 

机构地区：[1]西南科技大学制造科学与工程学院,绵阳621010

出　　处：《机械工程学报》2007年第10期46-49,共4页Journal of Mechanical Engineering

基　　金：国家高技术研究发展计划(863计划;2002AA421220);四川省教育厅计划(2004C016)资助项目。

摘　　要：连杆拐点圆上点附近曲线段与直线之间的近似度很高,工程上常利用其机构作为直线导引机构。针对铰链四杆机构连杆瞬心无穷远时拐点圆不存在,现有的方法不能综合出近似直线轨迹四杆机构的问题,提出瞬心无穷远时连杆曲率叠加原理,根据运动学原理进行分析,推导连杆上任意点曲率计算公式,证明曲率叠加原理的正确性,并得到求解铰链四杆机构连杆两铰链线上零曲率点的图解法。利用图解法能够解决瞬心无穷远时近似直线导引机构的综合问题,从理论上解决了瞬心无穷远时这一特定位置近似直线轨迹导引机构的综合问题。得到的方法简单、直观、适用,是拐点圆理论有力的补充和完善。The coupler curve which is near the zero-curvature point on the inflection circle is close to the straight line, the mechanism is often as the approximate straight-line guidance mechanism. When the instant center of linkage is infinitely far, there is no inflection circle in the linkage of four-bar linkage mechanism. It is difficult to synthesize approximate straightline mechanism by the old methods. According to the intuitionistic analysis, a logical superposed formula for curvature of every spot locus on the linkage of four-bar linkages is presented, when the instant center of linkage is infinitely far. Afterward the formula is deduced by relativistic kinematics. The superposed formula is correct, and a diagrammatizing method getting zero-curvature spot on the linkage is gained by this formula, then the formula is successfully applied to synthesize the four-bar approximate straight-line linkages with infinitely far instant center. The method has such advantages： simplicity, visualization and practicality, which strongly supplements the theory of the inflexion circle.

关 键 词：近似直线 四杆机构 综合 

分 类 号：TH13[机械工程—机械制造及自动化]