The Development Of A Cad System Of Conjugate Cam Based On Allowable Pressure Angle

With the development of computer technology, more and more design and calculation methods can be achieved by using computer-aided methods, which not only greatly improve the design and computational efficiency, but save time for the engineers. Conjugate cam, as a common mechanical drive mechanism, has been widely applied in light industry and high-speed field because of its high-precision motion control and drive performance. At present, there is a lot of computer-aided conjugated cam design software, but we can found that these sorts of software required some structural parameters, including:the distance between roller follower oscillating shaft and conjugate cam shaft, the main and vice follower’s length, the angle between main and vice follower, and the initial position of follower. The calculation of these structural parameters are very complex, so it’s very difficult to master it and apply it into conjugate cam design for an engineering designer in a short time. Besides, such conjugate cam design software only check the pressure angle after the design, which often leads to redesign because the pressure angle does not meet the requirements. In addition, we could not obtain an original design of conjugate cam essentially by using those kinds of existing conjugate cam design software. This article intends to develop a piece of computer-aided conjugate cam design software, which will make up for the inadequacies of traditional software mentioned above.Follower’s motion, as a motion output, is a prerequisite for the design of the cam mechanism. Therefore, firstly, the article analyzes common follower motion law and combined motion law, as well as set up their mathematical model; secondly, as the follower motion law has been known, deducing the mathematical expressions which use to determine the cam shaft feasible region based on allowable pressure angle, and the equations of pitch and contour curve of conjugate cam after determining the cam shaft; afterwards, using binary arc spline theory to fit the feature points of conjugate cam’s contour curve and getting its fitting curve which can be applied in numerical control processing NC code directly. Then, designing the overall architecture of the computer-aided design software based on conjugate cam of allowable pressure angle, adopting module development, and obtaining complete software through debugging and running. Finally, using a conjugated cam design example to verify the feasibility and introduce the usage of the software, and evaluating the inaccuracies of this software from both theory and simulation aspects.The main contribution of this study is the development of a CAD system of conjugate cam based on allowable pressure angle. The design considered allowable pressure angle requirements at the beginning, calculation and computer displaying the feasible region of conjugate cam shaft visually. After selecting the conjugate cam shaft by using human-computer interaction, the computer will calculate every necessary structural parameters of conjugate cam mechanism and the feature points of conjugate cam’s contour curve automatically, finally, generating NC code which can be directly used in CNC machining. The software solves issues that the structural parameters design theory is complex and its application is difficult in conjugate cam design process, and it can truly assist engineering designer to do conjugate cam innovative design and has very important engineering significance.