Bosch rexroth MBT, Manual

Page: 301 / 422

10.2 Basic formulae
10.2.1 General movement equations
The variables required for sizing and selecting the motor are calculated using
the equations shown in the following.
The torques and speeds of the process are used to select drives
when configuring rotary direct drives.
n(t) Speed profile in time characteristic
a(t) Acceleration profile vs. time in m/s²
M(t) Torque profile in time characteristic in N
J
rot
Rotor inertia torque in kg*m²
F
0
(t) Base force in N
M
F
Friction torque in N
M
eff
Effective force in N
n
avg
Mean speed in min -1
t Time in s
T Total time in s
Fig. 10-2: General equations of motion
In most cases the mathematical description of the required positions vs. the
time is known (NC-program, electronic cam disk). The load cycle or the load
profile can be calculated using the load cycle/the load profile. Standard soft‐
ware (such as MS Excel or MathCad) can be used for calculating the re‐
quired variables, even with complex motion profiles.
The following chapter provides a more detailed correlation for tra‐
pezoidal or triangular speed curves.
MBT High Synchronous Torque Motors 289/409
Motor dimensioning
R911298798_Edition 08 Bosch Rexroth AG