BECKHOFF AL2000 Application - Manual (Page 21)

Eiserstraße 5 / D-33415 Verl / Telefon 05246/963-0 / Telefax 05246/963-149
21
Physical background
Usually a linear motor’s motion can be distinguished in 3 stages:
1. acceleration
2. constant (or maximum) velocity
3. deceleration
Below this is reperesented in a velocity-time diagram.
Velocity-time diagram for a combined or ' long motion'
During t
a
the accelaration takes place and during tc the velocity is constant at its maximum. The decelaration to
stand still takes place in t
d
. The total distance covered by the motion equals the area under the graphical draw-
ing.
During acceleration and decelaration the largest forces are displayed while the movement at constant speed
only requires the force needed to overcome friction. A linear motor that is constantly moving to and fro without
reaching its maximum velocity is thus loaded upmost. In the diagram below this situation is sketched.
Velocity-time diagram for a combined or ' short motion'