Abstract

An automated computer-based method for deriving the shape of machine elements such as cams is described for complex mechanisms. Traditional cam synthesis concentrates on follower motion; the method described here enables complete control of the required output motion. Output motion is defined for any constant or variable camshaft velocity. The process is not limited by the degrees of freedom, follower shape, follower suspension, or complexity of the mechanism linking followers to output points.

The method includes a velocity analysis to predict cam shape, pressure angle, and relative velocity of the follower with respect to the cam. This analysis allows immediate visual inspection and further dynamic and wear analyses. Cam-follower contact stress is readily calculated for an entire cycle of motion during the synthesis process.

An example consisting of a five-bar linkage displaced by three cams is synthesized using the methodology. The general method described facilitates development of mechanisms previously not feasible using conventional methods. Servomotor command displacement profiles required for complex systems can also be derived using this method.

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