June 22, 2008
June 22, 2008
June 25, 2008
13.124.1 - 13.124.10
A Teaching Tool for Design and Analysis of Cam and Follower Mechanisms
This paper presents a software tool for teaching the kinematics, design and analysis of cam and follower mechanisms used in the undergraduate mechanisms course that is generally included in the Mechanical Engineering curriculum. The software tool has mainly been developed to enhance student learning, but it can readily be used to design and analyze cam mechanisms for industrial applications. The software includes numerous combinations of follower types (e.g., knife-edged, flat face and roller) and follower motions e.g., constant velocity, constant acceleration and harmonic. In order for the students to gain insight into the subject, the software generates detailed information about the displacement, velocity and acceleration of the follower in tables and graphs more so than the other cam and follower design tools used in industrial applications. It also provides graphical representations and animation of the cam and follower mechanism. Specifically, the emphasis of this work has been on having interactive software that can enhance student learning by exposing them to theoretical and practical aspects of the design of cam and follower mechanisms. The software provides design tips in the form of warning and error messages whenever the users attempt to enter invalid values of input parameters, and suggests fault-recovery steps that help the users optimize their designs. The paper includes two simple design projects, generated by the software program to demonstrate important problems such as elevated pressure angle and undercutting that can occur in the design of cam mechanisms. The software tool was used in a lecture where positive feedback from students enrolled in the mechanisms course has encouraged the authors to continue the development of such educational software tools for other applications.
Cam and follower mechanisms were traditionally designed using graphical layouts, intuition and experience. As a result, the measurement of the radius of curvature was often inadequate for modern machines1 where accurate contact stresses between the cam and the follower were required. Clearly, the problem is more complicated for complex machines with several types of follower motion in which the radius of curvature over every particular segment of the cam profile must be considered separately. Besides the practical issues, a major drawback of the traditional methods was in regard to learning of the analysis and design of the cam and follower mechanisms, which was often overlooked in the mechanisms course of Mechanical Engineering curriculum.
With the availability of digital computers, however, the design of cam and follower is more straightforward provided that appropriate mathematical and numerical schemes are available to evaluate all of the design criteria2,3. In general, the design of a cam mechanism involves the determination of the cam profile such that a full 360 rotation of the cam results in a full cycle of the desired motion of the follower. A powerful and versatile example of such computer-aided cam design tool is the CamDesign program4. This program not only facilitates the analysis and design of cam and follower mechanisms but also provides extensive feedback to help the user learn the steps of the design.
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