The self-intensifying technology of safety catchers is a fail safe principle that is similar to a wedge system--as the load continues to increase, the safety catcher continues to hold the rod in a fixed position until hydraulic or pneumatic pressure is restored.
If the SC is holding a load? You must first apply release pressure and then move the axis upward. At this time, you should be monitoring the “Unlocked” proximity switch indicating the status condition.
No, the clamp system requires approximately ½ inch of downward movement to develop full holding. The SC’s are single acting and only hold against gravity.
Factor of 100% is included. Minimum holding is 2 x M (admissible load) max holding is 3.5 x M. Force test required is 1.5 x M.
Admissible Load (M) sizing is determined by the platen weight + tooling weight and anything mounted to the platen.
No, the influence of mineral oil on the shaft is insignificant. and you will not lose holding capacity.
* In case Impact noises due to excess pressure are audible when pressurizing the Safety Catcher, these can be suppressed by means of a flow control valve in the p-line
**…
All mounting bracketry should be design for 4xM in the event of an overload condition.
The typical reaction time of the SITEMA Safety Catcher is approximately 150msec.
Typical travel without the optional Spring Base is between 5 and 15mm…with the Spring Base, an additional 6-10mm depending on the size. Full travel with the Spring Base option is can range between 10-25 mm depending on type and size. If the Catcher does not bottom out/compress the Spring Base fully, then release pressure…
* In case impact noises due to excess pressure are audible when pressurizing the safety catcher, these can be suppressed by means of a flow control valve in the p-line.
** In case the pressure is not sufficiently constant (e.g. pressure drop at the beginning of a downward stroke), we recommend a check valve in the p-connection of the valve.
To keep the clamping permanently open, safety catchers mostly are hydraulically actuated. Pneumatic versions are also available for smaller units.
In most applications an actuation as suggested in Fig. 2 is used. During every operational cycle, the 3/2-way valve is actuated electrically and releases the safety catcher.
In all other operational conditions, as well as in cases of power-failure, pressure line breakage, emergency stop, etc. the safety catcher becomes effective, secures the rod and/or stops the load. If necessary the valve can also be switched by another safety signal, e.g. speeding, contouring error, etc.
