The selection of the motion law of the driven component must first meet the working requirements of the machine The cam mechanism with constant velocity motion has rigid impact at the beginning and maximum stroke of the follower, and is only suitable for low-speed and light load situations.
The cam mechanism with equal acceleration and equal deceleration motion has flexible impact at the starting and ending points of the driven parts, and is only suitable for medium and low-speed situations, such as the forming cam of the vertical spindle weft winding machine. The cam mechanism with harmonic motion still has flexible impact at both ends, but the impact is smaller than that of the equal acceleration and equal deceleration motion laws. Therefore, it can be used for cam mechanisms with medium speed rotation, such as the tread plate of the weaving machine frame motion law, which often adopts the harmonic motion law.
In practical engineering, it is common to encounter situations where machinery has multiple requirements for the motion and dynamic characteristics of the driven parts, and it is difficult to fully meet these requirements with only one commonly used motion law.
In order to avoid impact, at the junction of two motion curves, the displacement, velocity, and acceleration of the two laws must be equal, and the slope of the acceleration curve must also be equal, so that the curves of the two laws at the junction are smooth and continuous.
The selection of the motion law of the driven component should also ensure that the cam mechanism has good dynamic characteristics and the designed cam is easy to process.