An Comprehensive Error Free Design For Oscillating Follower Spatial Cam

Oscillating follower spatial cam mechanisms are widely used in machinery field. However, the currently used methods to design the pitch curve of a spatial cam produce errors, as described in detail. In view of which, an accurate design methodology is proposed. Firstly, the methodology for the design of a cam mechanism’s motion law is systemically analyzed, including the use of spline functions when dealing with discrete points, according to functions of the mechanism. Thus, combined with the condition of the swing link, the follower’s motion law is also determined. Secondly, space coordinates of the follower’s motion track are utilized, and with the consideration of deviation angle, equations or polar equations of3D expansion pitch curve are derived, which are error free and can be easily plotted and used to analyze and design a spatial cam. The deduced expressions of pressure angle and radius of curvature are based on motion law of the follower and prime cylinder radius of cylindrical cam or prime polar radius of conical cam, and the functions of minimum prime cylinder radius or minimum prime polar radius with respect to allowable pressure angle or allowable radius of curvature are established through these expressions. Thus, geometric parameters of a spatial cam can be determined according to certain working and processing conditions. Finally, through example analysis based on the motion law of a cycloidal function, the relation curves between the maximum pressure angle as well as the minimum radius of curvature of the expansion pitch curves and the prime cylinder radius or the prime polar radius of the spatial cams are described by software under specific design requirements. By comparing with the currently used methods, this methodology is validated to be accurate for the design of an oscillating follower spatial cam’s expansion pitch curve. With this, the whole process of a spatial cam design is completed.