The Integrated Approach Of The Guiding Mechanism Of A Straight Line Trajectory

The straight-line mechanism specially including approximate straight-line four-bar linkage is of importance for the practical use, so many mechanicians all over the world pay attention to the method and theory of synthesizing them. They are used a lot of aspects of mechanical engineering, for example, they can be used as four-bar straight-line guidance mechanism without friction and wearing along its paths in Roberts. Using the coupler curve with a straight - line section of the first mechanisms, a combined mechanism can also be created the follower of which can dwell approximately for a long time. So can cranes, which move in horizontal or vertical straight line. And so on.(1) In this paper the ways and theories of synthesizing two kinds of mechanisms are researched, one is precise straight-line linkage, the other is approximate straight-line linkage. The following will be introduced detailed researching and innovation about them:In the first part of the paper, according to geometrical theorem, the theory that a linear or round locus of some linkages must appear in some condition is proved. Some basic linkages that move in the disciplinarian is gained. In the end, some mechanism that makes a linear locus is synthesized.(2) In the second part of the paper,(1) It is shown how to draw the inflection circles when the positions of the linkages are not common, for example, link and crank or link and frame are on one line.(2) 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 straight - line mechanism by the old method. In this paper, according to intuitionistic analysis, we present a logical formula for curvature of every spot locus on the linkage of four-bar linkages, when the instant center of linkage is infinitely far. Afterward we deduce the formula by relativistic kinematics, and a diagrammatizing method getting zero-curvature spot on the linkage is gained by the formula, and then the formula is successfully applied to synthesize the four-bar approximate straight -line linkages with infinitely far instant center.(3) A new method of synthesizing approximate straight-line four-bar linkages from symmetrical four -bar linkages is brought forward, the method is inflection circles - interpolating node composite. Using it we gain more precise conventional...