KINEMATIC ANALYSIS OF CONSTANT BREADTH CAM DRIVEN LINKAGES

Abstract

Several constant breadth curves are defined that can be used as cam profiles in constant breadth cam mechanisms that are closed cam mechanisms. There are two objectives for this study. One of them is to study the kinematic analysis of different type of constant breadth cam mechanisms. The other objective is to obtain a dwell period for constant breadth cam driven linkages that is impossible for a standard cam mechanism. A general kinematic analysis of a constant breadth cam mechanism with translating flat-faced follower was carried out with the principle of kinematic inversion. With the results, the kinematic analyses of the constant breadth cam driven inverted slider crank mechanism and four bar mechanism were examined in detail and a general method is given for all constant breadth cam profiles and cam driven linkages. It has been seen that a dwell period of 45° (with the fixed joint coordinates as x_n = 18 mm and y_n= 8.5 mm) and 40° (with the fixed joint coordinates as x_n = 18.5 mm and y_n= 8.5 mm) can be obtained in designed cam driven four bar and inverted slider crank mechanism respectively. After the displacement analysis, some velocity and acceleration analysis examples are given by taking the derivative of displacement. Similar kinematic analyses are possible for cam-driven mechanisms with more links. Also, it has been seen that changing the location of fixed joint of the cam profile can affect the displacement, velocity and acceleration graphics of the mechanism. With this, the dwell period can be changed too.