Controlling a rodless cylinder 3

[Sprocket59]

With air pressure off, the piston of a rodless cylinder (1/2" bore, 15" stroke) is at mid-stroke. It's controlled with a 5 port, 2 position solenoid valve and flow restrictors at each actuator port (controlling exhaust). Upon pressurization, the piston shoots to the end of stroke regardless of flow restriction. This doesn't happen during normal cycling. The actuator has no leaks. What's up? Should I use a different valve?

 

[Barry1961]

During normal cycle there is always compressed air on one side of the piston. When you first turn the air on and the air is not compressed the piston has to travel some distance before it can compress the air enough to provide some speed regulation. If you adjust the flow control tight enough so the piston does not slam it will be too slow for normal operation.

If the piston is normally going to end up at one end of the stroke you can start the cycle by stroking the piston to the side it is already at. This will charge the cylinder with compressed air so it won’t slam on the first stroke. If there is an easy way to make the piston end up at the same end this is a good solution.

If you can not make the piston start from one end you can control it with two three position closed center valves. You can have one of the valves regulate the air flow very slowly for the first stroke to “home” the piston. Or tell the operator to slowly open the air valve when turning on the air.

Barry1961

 

[montazels]

1 solution: You need install a 2 ways flow restrictors (inlet/outlet) for each actuator port. With this, you control flow at entry and exit of rodless cylinder.

http://www.iteks.fr

 

[dbaird]

Use a soft-start valve.

http://www.manufacturingtalk.com/news/imi/imi138.html

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.