Illustration of CAM
A cam rotating at consisted angular velocity operates an oscillating follower. Draw cam profile for the given data:
Angular displacement of the follower = 20^{o}
Angle of dwell after outstorke = 45^{o}
Angle for outstroke with SHM = 90^{o}
Angle for return stroke along uniform acceleration & retardation for retardation 5/3 of acceleration = 75^{o}
Distance among pivot centre and roller centre = 10.5 cm
Distance of the pivot point from centre of rotation of cam = 14 cm
Roller radius = 1.5 cm
Minimum radius of the cam = 15 cm
Solution:
Draw displacement diagram with appropriate scale . The corresponding lift shall be 10.5 × (20/ 180) × π = 3.665 cm. The diagram is illustrated in figure
For drawing cam profile you might proceed as:
(a) Draw two concentric circles having radii equivalent to minimum cam radius & minimum cam radius as well as roller radius along above chosen scale.
(b) Mark primary position of roller and situate pivot centre A having distance from cam centre & distance from roller centre.
(c) Draw a circle having O as centre and radius equivalent to OA.
(d) Having OA as zero angle line plot angles for outstroke θo, dwell & return stroke θr and divide angles θo & θr in equivalent parts say 8. Mark points on pivot circle i, j, k, etc.
(e) Having i, j, k, etc. as centres and radius equivalent to distance among pivot centre & roller centre, draw arcs that give points on prime circle 1, 2, 3, etc.
(f) Transfer displacement from displacement diagram, above the prime circle with arcs like 1 – 1′, 2 – 2′, 3 – 3′, etc.
(g) Along centres at 1′, 2′, 3′, etc. draw series of arcs having radius equivalent to roller radius to denote follower position.
(h) Draw a smooth curve that is tangential to all of these follower positions. It is the needed cam profile.