Cam and follower mechanism:

A cam and follower mechanism is illustrated in Figure (a), the dotted line specify the path of point B (on the follower). The cam rotates at 100 rad/s. Draw the velocity & acceleration diagram for the mechanism and find the linear acceleration of the follower. Minimum radius of cam = 30 mm & maximum lift = 35 mm.

(a)                                                                               (c)

Solution

Linear velocity of point A that is on the cam, V_A = ω × OA.

or,

                V_B  = V_A + V_BA

(a) Suppose suitable scale say 1 cm → 1 m/s.

(b) Plot velocity of A by drawing a line perpendicular to OA from pole o. It defined by oa.

(c) From the point o, draw a line parallel to motion of follower to define direction of velocity of follower.

(d) Draw a line from the point 'a', parallel to the motion of B that is parallel to the tangent at cam profile to meet line demonstrating direction of velocity of follower at the point  b. ob signify velocity of follower in magnitude & direction

 V_B  = 1.75 m/s   and

 V_BA  = 4.85 m/s

Velocity polygon is shown in Figure (b).

Acceleration Diagram

(a) Choose suitable scale say 1 cm → 200 m/s.

(b) Plot a_A by drawing a line parallel to OA from o′ & length equivalent to 2.25 cm.

 (c) Now plot a^cor perpendicular to profile of cam and length equivalent to 4.85 cm. It is defined by a′ b′₁.

(d) Now draw a line perpendicular to a′ b′₁ to signify direction of  .

(e) Draw another line from o′ to define direction of motion of B to meet direction of at b′.  o′ b′ shows acceleration of B in magnitude and direction.

                a_B  = 3 × 200 = 600 m/s²

The acceleration polygon is illustrated in Figure (c).