Design and analysis of a positive-drive cam mechanism with a set of symmetrical offset rollers

Design and analysis of a positive-drive cam mechanism with a set of symmetrical offset rollers.

摘要
The cam mechanism is commonly used in a wide range of machinery due to its stability and efficiency. The pressure angle plays an important role in the design of the cam mechanism. A high-pressure angle could cause problems such as a jamming effect or stuck, higher contact force, and lower transmission efficiency. Conversely, a lower pressure angle necessitates a larger base circle radius, leading to an increase in the overall size of the cam mechanism. This paper addresses these challenges by proposing a modified constant diameter cam mechanism equipped with symmetrical offset rollers. The proposed design significantly improves the transmission efficiency, reduces contact forces and side thrust forces, and enables a more compact cam mechanism. An analytical approach is presented for the profile synthesis of the proposed cam, and its design limitations are thoroughly discussed. Furthermore, it is demonstrated that only a single cam profile is required to drive a follower equipped with symmetrical offset rollers. A force analysis confirms the superior performance of the proposed design compared to conventional constant diameter cam mechanisms. Furthermore, an optimization procedure is applied to achieve a balance design with a smaller base circle and a reduced pressure angle, while maintaining efficient force transmission. In the numerical example, the proposed design achieves a 37.39% reduction in maximum pressure angle, an 8.22% reduction in contact force, and up to a 56.04% reduction in side thrust forces. A sensitivity analysis is also conducted to evaluate the influence of design parameters on the maximum pressure angle and contact forces of the cam mechanism. The proposed approach not only enhances the performance of cam mechanisms but also provides a robust solution for applications requiring compact, efficient, and high-performing mechanical systems.