Siemens SINUMERIK 840D sl Function Manual

Functions
2.18 Kneeshaped acceleration characteristic curve
Basic logic functions: Acceleration (B2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
43
2.18 Kneeshaped acceleration characteristic curve
2.18.1 Detailed Description
2.18.1.1 Adaptation to the motor characteristic curve
Function
Various types of motor, particularly stepper motors, have a torque characteristic that is highly
dependent upon speed and shows a steep decrease in torque in the upper speed range. To
ensure optimum utilization of the motor characteristic curve, it is necessary to reduce the
acceleration once a certain speed is reached.

0
UHG
0>1P@


Q>@
Q
PD[
Q
UHG
0
PD[
Figure 2-5 Torque characteristic curve of a motor with torque characteristic that is highly dependent
upon speed
1: Torque decrease zone
n
red
: Speed above which reduced torque has to be assumed
n
max
: Maximum speed
M
max
: Max. torque
M
red
: Torque at n
max
(corresponds to creep acceleration)
Simulation of torque characteristic
For the purpose of simulating the torque characteristic of the motor characteristic curve, the
machine data:
MD35242 $MA_ACCEL_REDUCTION_TYPE =
characteristic
can be used to select various types of characteristic curve:

Siemens SINUMERIK 840D sl Specifications

General

Control Type	CNC
Number of Axes	Up to 31
Max Number of Channels	10
Interfaces	Ethernet, PROFIBUS, PROFINET, USB
Interpolation	5-axis interpolation
Operating Temperature	0°C to 45°C
Relative Humidity	Up to 95% (non-condensing)
Display	TFT color display, various sizes
Programming Languages	DIN/ISO
Safety Features	Safety Integrated
PLC	Integrated PLC S7-300
Drive Interface	SINAMICS S120
Data Storage	CF card, USB
Operating System	Windows-based