CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Cam is a versatile, specially shaped part of a machine that is always in contact with a member a called the follower. The name cam should not be confused with the common abbreviation cam for camera and camcorder, both used in the fields of photography and video, nor with the acronym CAM applied to computer applied to computer-aided manufacturing, which utilizes computational facilities for machinery fabrication of all kinds.
Many different types of cam profile are designed and manufactured depending on a machine’s requirements (P.W Jensen, 1987). Cam is a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam is in most cases merely a flat piece of metal that has had an unusual shaped or profile machined onto it.
Many studies on the cam mechanisms concern the problem of vibrations. As machine speed increases the problem of vibrations of the cam mechanism has the more significant importance. The vibration level has the influence on the wear rate, noise level and service life of the cam actuated machines and devices and also to the precision operation of machines. Because of that it is important to understand the cause of vibrations and provide means to control or to minimize unwanted vibrations so that desirable system response characteristics may be predicted and obtained.
Cam follower mechanism are found in almost all mechanical device and machine for example in agriculture, transportation equipment, textiles, packaging, machine tools, printing press, automobile internal combustion engines, food processing machines, switches, ejection molds, and control systems, and more recently in micro machines such as micro electromechanical system[MEMS]. Figure 2.1 showed the automobile cam-driven overhead valve train linkage
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Figure 2.1 Automobile cam-driven overhead valve train