23
4.0 C om m is s io nin g
NOTE
Once all these steps have been achieved, it’s advisable to make
the cylinder move several times forward-backward slowly on
the complete stroke and to check the position control behaviour
while the cylinder speed and acceleration are gradually
increased.
For more detailed information about how to check the posi-
tion control behaviour, please read paragraph ⮑ 4.4 How
to check position control behaviour – first approach,
page 24.
4.2 General
recommendations for use
WARNING
For whatever reason, the cylinder move must not be stopped by
a stiff mechanical stop except if the speed of the motor is low
(value below or equal to a few percent of the maximum speed
value) and the cylinder force is limited to a low value (by defining
a limitation on motor current). Otherwise, the kinetic energy
stored within the internal rotating parts of the cylinder will be
stopped in a very short time. This will create very high loads
(inside the cylinder and in the cylinder pushing tube) which might
seriously damage the cylinder and its external environment.
1. Cylinders include two internal mechanical stops: one in
the retracted and one in the extended position. In all
cases, these stops are only to be used manually at slow
speed and under small loads. They are not designed for
the cylinder to push into them with significant loads and
speeds.
2. For initial operation, it is advised that the user slowly in-
creases the cycle rate of the cylinder without overheat-
ing. As a general rule, the stabilized temperature of the
cylinder should not exceed 80°C (whatever surface
where measure is made). For more detailed information
on that subject, please read paragraph
⮑ 5.2 Lubrication – detailed description, page 29.
3. Depending on the cycle rate, working cycle definition
(load, speed, acceleration/deceleration profiles) and en-
vironmental conditions, the cylinder can heat more or
less. For more detailed information on that subject,
please read paragraph ⮑ 5.2 Lubrication – detailed
description, page 27.
4.3 How to define zero
reference
To define zero reference by using the home switch, there are
two ways to do it:
• The home switch is integrated in the Ewellix cylinder.
or:
• The home switch is fixed to the machine driven by the
Ewellix cylinder.
WARNING
It is required to enable the limit switches in the servoamplifier, so
that a zero reference search using the home switch can be done
from any starting cylinder position.
Case “home switch is integrated in the Ewellix
cylinder”
Two ways are possible to define the zero reference (choice
will depend on actual opportunities offered by customer
application):
• Search for the zero reference always has to begin in a di-
rection where the pushing tube is going towards the re-
tracted position. In that case, write the following program.
-
Make the cylinder pushing tube move up to reach the
limit switch in the retracted position.
-
Then, make the cylinder pushing tube go out until the
home switch detects the roller screw nut.
-
Then, launch a search for the first zero of the encoder (or
resolver). Define the zero reference once the encoder (or
resolver) zero has been found.
• Search for the zero reference always has to begin in a di-
rection where the pushing tube is going towards the ex-
tended position. In that case, write the following program:
-
Make the cylinder pushing tube move up to reach the
limit switch in the extended position.
-
Then, make the cylinder pushing tube go in until the
home switch detects the roller screw nut.
-
Then, launch a search for the first zero of the encoder (or
resolver). Define the zero reference once the encoder (or
resolver) zero has been found.
NOTE
As a general rule, there isn’t necessarily a link between the zero
defined by a zero reference search and the zero position given in
the cylinder drawing. Very often these two zeros correspond to
two different cylinder positions.
WARNING
The zero reference defined by searching for the home switch
will be reproducible for one cylinder but won’t be identical
between different cylinders.
Consequently, when an old cylinder is replaced by a new one, it
is required to redefine all actuator positions to be reached during
machine operation (in function of new cylinder zero reference).
Otherwise it may occur unexpected actuator position with risk of
heavy property damage.
Summary of Contents for SLSA Series
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