BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI

36 Radu Ibănescu and Cătălin Ungureanu
Φ
d
F
B
h
C
A
l
R
M m
e
O
ϕ (t)
G
a
Fig. 1 – Eccentric cam.
h i
diagram is obtained showing the dependence of the cam follower length with
respect to the moment acting on the cam, so that the cam follower does not
stick. The required length of the cam follower guide can be chosen from this
diagram.
2. The Eccentric Cam Mechanism
The eccentric cam mechanism consists of a disk of radius R actuated by a
couple M m (Fig. 1). The disk can rotate about the fix point O located at the
distance e from the centre of the circle. The cam follower is vertical and it has a
horizontal bar at each of its ends. The bar at the bottom end lies on the cam. The
bar at the top end is actuated by a spring having the spring stiffness k e and by a
constant force F collinear to the spring. The disk weight is G and the weight of
the cam follower is assumed to be very small and hence negligible.
The friction coefficient between the cam follower and the disk and the
cam follower and its guide is μ. The friction coefficient in the joint at O is μ 1 .
All the dimensions are known and can be seen in Fig. 1. The problem is to
determine the minimum value of the driving couple M m to maintain the
mechanism in equilibrium at limit state. The disk and the cam follower are