Tuesday, September 16, 2008

Basic of mechanical :cam

cam
Cam is a rotating mechanical member used for transmitting desired motion to afollower by direct contact
Classification of cam
(i) according to cam shape
(ii) according to follower movement
(iii) according to manner of constraint of the follower
Classify cam based on a shape
(i) wedge cam
(ii) radial cams
(iii) spiral cams
(iv) drum cams
(v) spherical cams
classification of follower
(i) According to follower shape
(ii)according to motion of follower
roller followerIn place of a knife edge roller is provided at the contacting end of the follower
Spherical follower In the contacting end of the follower is of spherical shape
Angle of ascend The angle of rotation of the cam from the position when the follower begins to risetill it reaches its highest points
Angle of descend The angle through which the cam rotates during the time the follower returns to
Angle of dwell It is the angle through which the cam rotates while the follower remains stationary atthe highest or the lowest
Angle of action The total angle moved by the cam during its rotation between the beginning of riseand the end of return of the follower
radial or disc camsIn radial cams the follower reciprocates or oscillates in a direction perpendicular to thecam axis . The cams are all radial rams. In actual practice, radial cams are widely useddue to their simplicity and compactness.
dwell The zero displacement or the absence of motion of the follower during the motion of thecam is called dwell.
classification of followers according to follower shape
(i) Knife edge follower(ii) Roller follower(iii) Mushroom or flat faced follower and(iv) Spherical faced or curved shoe follower
classification of follower according to the motion of the follower
(i) Reciprocating or translating follower(ii) Oscillating or rotating follower15.What is classification of followers according to the path of motion ?(i) Radial follower and(ii) Offset follower
the motion of the follower The follower can have any of the following four types of motions(i) Uniform velocity(ii) Simple harmonic motion(iii) uniform acceleration and retardation(iv) cycloidal motion.
application of camClosing and opening of inlet and exit value operating in IC engine .
necessary elements of a cam mechanism(i) Cam-The driving member is known as the cam(ii) Follower-The driven member is known as the follower.(iii) Frame-It supports the cam and guider the follower.
translating angle The wedge is replaced by a flat plate with a groove . The plate cam moves back andforth imparting a translatory motion to the follower. Thus these cams are also known astranslating cams.