Kinematic analysis of polynomial type constant breadth cam mechanisms

In addition to force closed cam mechanisms, which are more common in use, form closed constant breadth cam mehanisms are preferred in many applications due to their cheap and simple construction. Since Reuleaux type cams (whose profile consists of circular arcs), which are one of these types of cam mechanisms, are not very dynamically suitable due to discontinuities in velocity and acceleration characteristics. It is more appropriate to use polynomial type constant breadth curves, which do not have these disadvantages, as cam profiles. In this study, general kinematic analysis of polynomial type constant breadth cam mechanisms with translating and oscillating followers are performed by applying the kinematic inversion principle. Detailed displacement, velocity and acceleration graphs are given for cam profiles consisting of five different polynomial type constant breadth curves obtained by examining the studies in the literature and partially by trial and error method. As a result of the analysis, it has been shown that the Dwell-Rise-Dwell motion type can be obtained for each profile by changing the fixed joint point coordinates of the cam profile. The standard cam motion types in practice and the Reuleaux type (whose profile formed with circular arcs) cam mechanisms with translating follower are compared with polynomial type constant breadth cams and the advantages of the polynomial type constant breadth cam mechanisms are mentioned. In addition, kinematic analysis has been carried out for the profiles consisting of the said constant breadth curves in constant breadth cam driven four bar and inverted slider crank mechanisms. As a result of the analysis, it has been proven that the dwell motion, which is not possible to obtain in the classical four bar and inverted slider crank, can be obtained in the output link of these constant breadth cam driven linkages.