Unit design – cam mechanisms

This is one of the SEED curriculum engineering design guides. SEED (Sharing Experience in Engineering Design) is an organisation of teachers of design in tertiary education.

The purpose of this guide is to enable the user to determine the optimum dimensions and to specify the sprung force closure of a disc cam mechanism, which produces the required output motion, whilst satisfying the kinematic constraints imposed by the maximum pressure angle and profile curvature. Cam mechanisms are used to convert a simple input motion, such as a shaft rotating at nominally “constant” speed, into a complex output motion. The output motion from cam mechanisms is versatile as the displacement, velocity and acceleration are all controlled accurately; it can also include stationary periods. Each movement can be specified independently of the remainder of the operating sequence. Besides the familiar application of the cam-operated valves of petrol engines the mechanism is used in textile manufacture, automatic assembly, wrapping machinery and many special-purpose devices. This guide assumes that the procedure given in SEED Design Guide “Planar Mechanisms” has been followed. Books and commercial software packages, which cover the design, dynamics and strength of most configurations of the cam mechanism, are cited in “Sources of Information“.

The guide includes the sections:

• Prepare the Timing Chart
• Construction and Operation
• Terminology
• Dimensions and Notation
• Output Motion
• Non-Dimensional Parameters
• Cam Laws
• Cam Law Selection
• Minimum Cam Size From Kinematic Constraints
• Space Constraints and Configuration
• Application of a Spreadsheet
• Optimum Cam Size
• Force Closure
• Dynamic Design

[Description and screenshot taken from the SEED Curriculum for Engineering Design page for this guide. (c) The Design Society used under the terms of their (CC BY-NC-SA 3.0) license.]

Link: http://www.bath.ac.uk/idmrc/themes/projects/delores/co-design-website/dpg/cam/camhome.html
Author: G. Druce
License: http://creativecommons.org/licenses/by-nc-sa/3.0/
Rights: Copyright 2011 The Design Society - This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. See http://www.bath.ac.uk/idmrc/themes/projects/delores/co-design-website/teachers/curriculum/about.html