Introduction To Cam

Present day requirements usually dictate that machine components move in a prescribed, exact path. Connected members alone can rarely fulfill this requirement. It is therefore necessary to resort to the use of miscellaneous surfaces called cams. Since the cam may have any shape, it is simple and adaptable. To design by use of other mechanisms to produce a given motion, velocity and acceleration is complicated; to do so with a cam is by comparison easy, accurate and efficient.
A cam may be defined as a rotating or a reciprocating element of a mechanism which imparts a rotating, reciprocating or oscillating motion to another element termed as follower. In most of the cases the cam is connected to a frame, forming a turning pair and the follower is connected to the frame to form a sliding pair. The cam and the follower form a three-link mechanism of the higher pair type. The three links of the mechanism are:
i) The cam which is driving link and has a curved or a straight contact surface.
ii) The follower which is the driving link and it gets motion
by contact with the surface of the cam and
iii) The frame which is used to support the cam and guide the follower.
Complicated output motions which are otherwise difficult to achieve can be easily produced with the help of cams. The cams are widely used for operating the inlet and exhaust valves of internal combustion engines, automatic attachment of machineries, printing control mechanisms,
spinning and weaving textile machineries ,shoe-making machinery, feed mechanism of automatic lathes etc. In fact all modern automatic machines require the help of a cam. A cam is difficult to manufacture, especially when it is to be produced in small quantities. When produced on a mass scale, it is manufactured by a punch press, by die-casting or by milling from the master cam.

Abstract For Computer Aided Generation Of Cam Profiles

ABSTRACT

Cams are the most important machine elements found in many machinery we use in our daily life. The cam and follower motion is the simplest and widely used mechanism. In cams, disc or plate types of cams are commonly preferred for wide range of applications as they are compact.
The design and manufacturing of the plate cams is a very delicate job. The shape of the cam is determined by its designated function .In the cam-follower mechanism, the profile of the cam is the most important aspect which should be designed accurately as it decides the motion of the follower. Small surface errors imperceptible to the eye may produce high stress and vibrations in the follower linkages at high speeds. In the conventional design process we use free hand curves to draw the profiles. It is laborious, time consuming and not so accurate as well. Computers, which are widely applicable in every field, are used to overcome the difficulties encountered in the conventional design process. The factors that favors computer aided design process are accuracy, time saving .This project is an effort to try to develop a methodology of drawing the cam profiles and it is very easy to understand the program as it is written in the “C” language which is known to all.