Page 236 - Robot Builders Source Book - Gordon McComb

224 Transporting Devices

inclination/?. Armature 3 of the magnet is fastened to the tray, while magnet 4 is mounted
on the base of the device. Now we consider the operation of one spring. Its lower end
is fastened to the base at point O and its upper end A is connected to the tray. When
the coil of electromagnet 4 is energized, the armature 3 is pulled towards the magnet.
Tray 1 moves together with the armature, and the springs deflect by a corresponding
angle. As a result, the initial inclination angle /? increases by A/? while point A moves to
point A! along an arc with radius R. Thus every point of the tray is displaced horizon-
tally by distance L and vertically by length h, and the whole tray passes from position
I-I to position II-II. When the voltage feeding the coil of the electromagnet is switched
off, the elastic forces of springs 2 return the tray to its previous position, thus complet-
ing one cycle of the device's operation. With the standard alternating current network,
one can obtain either 100 cycles per second or 50 cycles per second (with a rectifier).
Let us consider the behavior of a body possessing mass m and located on the tray.
This body exerts a downward pressure on the tray by its weight, which obviously equals
mg. A frictional force P F appears in the horizontal direction. This force depends on the
frictional coefficient n (characteristic of the tray and body materials) and on the ver-
tical force N that the body exerts on the tray during the tray's motion. During this
motion, varying horizontal and vertical acceleration components appear. The vertical

FIGURE 6.22a General view of a vibroconveyer driven by an electromotor. This device
works according to the diagram shown in Figure 6.22. It was designed and built in the
Engineering Institute of Ben-Gurion University by Dr. R. Mozniker for investigative
purposes, and is a miniature copy of industrial vibroconveyors. Since it is driven by a
motor and crankshaft, it maintains a constant vibrational amplitude.
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