Knee-Shaped Acceleration Characteristic; Function: Adaptation To The Motor Characteristic Curve; Function: Effects On The Path Acceleration - Siemens SINUMERIK 840D Function Manual

12.2.19

Knee-shaped acceleration characteristic

12.2.19.1

Function: Adaptation to the motor characteristic curve

Various motor types, particularly stepper motors, have a torque characteristic that is highly
dependent on the speed with a steep decline in the torque in the upper speed range. For
optimal utilization of the motor characteristic, the acceleration of the associated NC axis must
be reduced as of a specific speed.
①
②
n
red
n
max
M
max
M
red
Characteristic curve types
As a controller-internal emulation of the torque characteristic curve of the motor, the following
characteristic curve types can be selected for the reducing range (see chapter
"Parameterization (Page 383)"):
● Constant torque characteristic
● Hyperbolic torque characteristic
● Linear torque characteristic
12.2.19.2

Function: Effects on the path acceleration

The path acceleration characteristic curve results from the types of characteristic curve for the
axes that are of relevance for the path. If axes with different types of characteristic curve are
interpolated together, the acceleration profile for the path acceleration will be determined on the
basis of the reduction type that is most restrictive.
The following order of priorities applies, whereby 1 = top priority:
1. Acceleration reduction: 0 = constant characteristic
2. Acceleration reduction: 1 = hyperbolic characteristic
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
Normal range
Reducing range
Speed as of which traversing is done with reduced torque
Maximum speed
Maximum torque
Torque at n (corresponds to acceleration reduction)
max
B2: Acceleration and jerk
12.2 Functions
379