The Mechanical Analysis Of Over-Constrained Spatial RCCR Mechanism

The Space crossed RCCR mechanism is a topic for many years. The mechanism is a simple structure, less components, low pairs connection, ease to manufacture and assemble, in addition, its every dowel bar is parallel and equivalent to each other, which provides a wide range of potential applications for the mechanism. So this is why our group have studied the mechanism for years. In the beginning, Qihui Yu analyzed the one pair of dowel bar motion and mechanics of spatial RCCR mechanism, and validated it by simulation. We know that the mechanism dowel bar is translational motion, the intersection trajectory of dowel bar(The forcing pair) is an ellipse, the intersection angle of the input and output shaft of the mechanism can be freely selected between 0-180 degrees and a series of motion law, but its mechanics is not very satisfactory, there is infinite force at singular point. Next, for this defect, Qinghe Niu finished three pairs of dowel bars space RCCR mechanical analysis. Although the motion and mechanics problem does not exist, but he took the deformation of dowel bars into account, his analysis result contains too much elasticity curve component. For the of several pairs of dowel bars spatial RCCR mechanism, this paper illustrates solve the mechanics of the over-constrained problem with the deformation compatibility equation by flexible treatment of the forcing pairs. And validated it through the Motion plugins of Solidworks. On the basis of this theory solving ideas, I do the statics and dynamic analysis of three pairs of dowel bars of same offset, three pairs of dowel bars of different offset, several pairs(n pairs) of dowel bars. Finally, taking three pairs of dowel bars of different offset RCCR mechanism as the research object, I finish the dynamic analysis of the situation of take into account dynamic friction of the kinematic pairs(This article does not consider the viscous friction of lubrication). When we just do the flexible treatment at the forcing pairs, this solution is more conducive to grasp the essential characteristics of the mechanism. As opposed to the result of my upperclassman Qinghe Niu,this result of the solution is almost the same to the simulation result, which has not so much the elastic component. When the offset of the dowel bars is different, the static binding force of the forcing pairs is associated with the offset, the maximum static binding force appears in the dowel bar of second largest offset. Discussing the dynamic binding force of the forcing pairs, when the offset of dowel bars is the same, the inertial force of dowel bars does no difference with the dynamic blinding force of Z-direction. However, when the offset is different, the dynamic blinding force of Z-direction is associated with the mass, intersection angle, offset of the dowel bars. Besides, it is associated with the speed of the mechanism, which is most important.In this paper, we have finished the theoretical solution of the blinding force of the forcing pairs of several dowel bars spatial RCCR mechanism(the blinding force of other kinematic pairs can easy to acquire according to the equation of forces). It has basically covered over all the situations of several dowel bars spatial RCCR mechanism. And I verified it through the simulation of the plugin Motion of Solid Works. It is a phased summary for the spatial RCCR mechanism. It also provides a theoretical support for the design and application of the spatial RCCR mechanism.