Datasheet

Design of Equipment and Machinery
Selection
Series CL
Specific Product Precautions 1
Be sure to read before handling.
The precautions on these pages are for the fine lock cylinders and the lock-up cylinders.
For general actuator precautions, refer to Actuator Precautions on pages 3 to 7.
Warning
Warning
1. Construct so that the human body will not
come into direct contact with driven objects
or the moving parts of locking cylinders.
If there is a risk of contact, provide safety
measures such as a cover or a system that
uses sensors that will activate an
emergency stop before contact is made.
2. Use a balance circuit in which lurching of
the piston is taken into consideration. If the
lock is applied at a desired position of a
stroke and compressed air is applied to
only one side of the cylinder, the piston will
lurch at a high speed the moment the lock
is disengaged. In such a situation, there is
a risk of injury to humans, or equipment
damage. To prevent the piston from
lurching, use a balance circuit such as the
recommended pneumatic circuit (P. 598). If
an air-hydro fine lock cylinder is used,
make sure to operate the lock portion
through air pressure. Never use oil on the
lock-up cylinder because the lock-up
cylinder is a non-lube style. Failure to
observe this could cause the lock to
malfunction.
Refer to the following criteria for the
maximum load in the locked state, and
set.
When a cylinder is in a no-load and locked
state, the holding force (maximum static load)
is the lock’s ability to hold a static load that
does not involve vibrations or shocks. To
ensure braking force, the maximum load
must be set as described below.
1. For constant static loads, such as for drop
prevention:
• Fine lock series (Series CLJ2/CLM2/
CLG1)
35% or less of the holding force
(maximum static load)
Note) For applications such as drop
prevention, consider situations in which
the air source is shut off, and make
selections based on the holding force of
the spring locked state. Do not use the
pneumatic lock for drop prevention
purposes.
• Lock-up series (Series CL1)
50% or less of the holding force
(maximum static load)
2. When kinetic energy acts upon the cylinder,
such as when effecting an intermediate
stop, there are constraints in terms of the
allowable kinetic energy that can be
applied to the cylinder in a locked state.
Therefore, refer to the allowable kinetic
energy of the respective series.
Furthermore, during locking, the
mechanism must sustain the thrust of the
cylinder itself, in addition to absorbing the
kinetic energy. Therefore, even within a
given allowable kinetic energy level, there
is an upper limit to the amount of the load
that can be sustained.
• Fine lock series (Series CLJ2/CLM2/
CLG1)
Maximum load at horizontal mounting:
70% or less of the holding force
(Maximum static load) for spring lock
Maximum load at vertical mounting: 35%
or less of the holding force (Maximum
static load) for spring lock
• Lock-up series (Series CL1)
Maximum load at horizontal mounting:
50% or less of the holding force
(Maximum static load)
Maximum load at vertical mounting: 25%
or less of the holding force (Maximum
static load)
3. In a locked state, do not apply impacts,
strong vibrations or rotational forces.
Do not apply a impacts, strong vibrations or
rotational forces from external sources,
because this could damage or shorten the
life of the lock unit.
4. The locking of the fine lock cylinder is
directional.
Although the fine lock cylinder can be locked
in both directions, be aware that its holding
force is smaller in one of the directions.
CLJ2/CLM2/CLG1···· Holding force at piston
rod extended side decreases approx. 15%.
5. The locking of the lock-up cylinder is
unidirectional.
Because the locking direction of the lock-up
cylinder is unidirectional, select the locking
direction in accordance with the particular
operating conditions. It is also possible to
manufacture a bidirectional lock-up cylinder.
For details, refer to “Made to Order” on page
1989. Due to the nature of its construction,
a lock-up cylinder has a play of
approximately 0.5 mm to 1 mm in the axial
direction. Therefore, if an external stopper is
used to stop the piston rod and the lock is
engaged, the piston rod will shift in the
amount of its axial play.
6. To effect an intermediate stop, take the
cylinder’s stopping precision and overrun
amount into consideration.
Because the lock is applied by mechanical
means, the piston will not stop immediately
in response to a stopping signal, but only
after a time lag. This lag determines the
amount of the overrun of the piston stroke.
Thus, the range of the maximum and
minimum amounts of the overrun is the
stopping precision.
• Place the limit switch before the desired
stopping position, only in the amount of
the overrun.
• The limit switch must have a detection
length (dog length) of the overrun
amount + α.
• For SMC’s auto switches, the operating
range are between 8 and 14 mm. (It
varies depending on a switch model.)
When the overrun amount exceeds this
range, self-holding of the contact should
be performed at the switch load side.
∗ For stopping accuracy, refer to Series CLJ
(P. 603), Series CLM2 (P. 614), Series
CLG1 (P. 627), and Series CL1 (P. 637)
respectively.
7. In order to further improve stopping
accuracy, the time from the stop signal to
the operation of the lock should be
shortened as much as possible.
To accomplish this, use a device such as a
highly responsive electric control circuit or
solenoid valve driven by direct current, and
place the solenoid valve as close as
possible to the cylinder.
8. Be aware that the stopping accuracy is
influenced by changes in the piston speed.
The variance in the stopping position
increases if the piston speed changes,
such as due to load fluctuations during the
reciprocal movement of the piston.
Therefore, take measures to ensure a
constant piston speed immediately
preceding the stopping position.
Furthermore, the variances in the stopping
position increases when the piston is
effecting a cushioning stroke or during
acceleration after starting its movement.
9. When unlocking is performed, if the thrust
is applied to the piston, unlocking will not
be easily done. To avoid that, ensure that
unlocking should be performed before the
thrust is applied to the piston.
Overrun amount
Stop signal
596
P0595-P0668-E.qxd 08.11.17 2:57 PM Page 596