Digital Design And Dynamics Research Of Cam Opening Device

In the thesis, the conjugate cam shedding mechanism is researched by a dynamic method and the precision analysis. At the same time, the new method of conjugate cam reverse is proposed, and the harmonic motion algorithm are optimized. Then, the harmonic motion algorithm is used for the loom cam design.This thesis contains the following aspects:First of all, the author accomplished the reverse of the conjugate cam and the establishment of the digital prototype of the cam shedding device. This thesis introduces a reverse method of conjugate cam, maps out the cam profile data, sets up 3D model and makes the kinematics simulation analysis of conjugate cam mechanism through the software Pro/E. And then, this thesis also obtains reverse displacement, velocity and acceleration curves of the former follower. The author can obtain the characteristic parameters through the Non dimensional treatment of motion curve, and then redesign the cam by using the polynomial motion law with the control conditions. Finally, it shows that the inverse method can effectively improve the dynamic performance of cam opening device of cam through the simulation and trial and now in mass production. At the same time, according to the two-dimensional drawings of the cam opening device, the digital model of the opening device is set up by using Pro/E to lay a good foundation for the follow-up study.Secondly, the dynamic analysis of a single freedom degree of conjugate cam opening mechanism is carried out. The kinematics analysis is carried out at the first. The static dynamics is solved based on the kinematics analysis, and then the Lagrangian dynamics model is established. By using the dynamic simulation software ADAMS, the dynamic simulation analysis is carried out. The result proves the success of the cam reverse.Thirdly, based on the differential method and probability theory, the analysis of the accuracy of the cam opening mechanism is carried out. The error model of the cam opening mechanism is established, and the expression error of the swing arm is obtained. Meanwhile, the control method is proposed. Based on the analysis, the influence of initial angle error, phase angle error and the length of each pole on the output of the swing arm is pointed out. Namely, It indicates that error of initial angle and phase angle is the main error source of the institution. This conclusion can be directly applied to actual production, and this optimized design agency pointed out the direction.Finally, the algorithm of harmonic motion is optimized. This thesis studied on the relationship between the size of retention error and the maximum acceleration of the cam based on the design of the harmonic motion law. The results showed that the maximum acceleration can be reduced effectively through increasing the retention errors. One method was proposed to reduce the maximum acceleration by increasing the stop error, and the practical examples are given. In addition, the harmonic motion was used in the loom cam design. Compared with cams designing by other movement patterns, it found that the maximum speed and acceleration of the cam is obviously decreased designed by utilizing harmonic motion law.