Creative Design And Investigations On Planetary Indexing Cam Mechanism

The indexing cam mechanisms are more suitable to the work conditions where high speed and accurate output precision are needed, and have become the developing direction of modern intermittent mechanisms due to their advantages of simple structure, automatic positioning compared with other intermittent mechanisms. However, existing indexing cam mechanisms can't realize large index number by using compact structure because of their structure limitation.Two structures (typeâ…¢and typeâ…£) of planetary indexing cam mechanism are presented in this dissertation. New structures yield several advantages, including simple structure, smaller volume, large indexing number, strong carrying capacity and having no output mechanism, so their application prospect is extensive.In this dissertation, firstly, based on the forming principle of conjugate tooth contour, the equations of the two structures'cam pitch curve are derived. The animation of the mechanism is also described using Matlab software. The property of the cam curve and the design parameters are discussed. Typeâ…£of small indexing number are also studied, and the creative method is summarized.Secondly, the structure design of typeâ…¢and typeâ…£is studied. The rotation direction and the method that confirms dead point using three-ring structure or asymmetric two-ring structure are analyzed. The discrimination of typeâ…¢and typeâ…£is described through indexing mode, the method to confirm dead point and the meshing of the cam and the pin gear. The supporting structure of the pin is also discussed.Thirdly, the stress between the cam and the pin gear is over constraint problem, aiming at which the deformation compatibility condition is established. The pressure angles of one-ring and two-ring structure are calculated. The acting force and the contact strength between the cam and the rollers and the flexural strength are calculated. Therefore, without regard for the mismatching tolerance the meshing gap caused by the difference of stress direction is analyzed.Fourthly, differential method is used to calculate the output error of planetary indexing cam mechanism, and the general equation is also derived, according which the influence of parameters on output error is analyzed.Finally, the design and manufacturing of a prototype named two-ring planetary indexing cam mechanism is performed. All the parts are newly designed. The performance of the prototype indicates that the new mechanism is feasible. The vibration and noise of the prototype are measured and analyzed when the balance weight is mounted or not. The experiment result proves that balance is necessary to noise and vibration reduction.