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