Page 12 of 58
POS-123-*-2030
In manual mode (
START
disabled) the drive can be moved by means of
HAND+
or
HAND-
. The drive moves
under open-loop control at the programmed manual speeds.
When the
HAND (+
or
-)
signal is switched off, the current actual position is accepted as the required position
and the drive comes to a controlled stop.
The HAND mode can be used
– in case of a sensor failure – to drive the axis manually.
Influences on positioning accuracy:
The positioning accuracy is determined by the hydraulic and mechanical conditions. The right choice of valve
is therefore a decisive factor. In addition, two mutually contradictory requirements (short position time and high
accuracy) must be taken into account when designing the system.
The electronic limitations lie mainly in the resolution of the analogue signals, although a resolution of
< 0,01 % only needs to be considered for our modules with long positions. In addition, the linearity of the
individual signal points (PLC, sensor and control module) must be taken into account.
It is generally recomended to calculate the static and dynamic behavior of the hydraulic axis. For supporting
this, following technical basic data are required:
-
minimum natural frequency of the cylinder,
-
maximum theoretical speed for extending and retracting,
-
valve characteristics (natural frequency, overlapped or zero lapped, hysteresis and the flow gain (flow and
pressure drop),
-
system pressure, maximum pump flow,
-
and a description of the general system requirements.
V+
V+
A:A
D:A
A:B
D:B
MAX:A
MAX:B
driving out
volumetric flow
P-A
and B-T
control direction
control direction
driving in
