Pneumatic system design

K

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kwinny

I have a problem where a pneumatic cylinder is operating a lot slower than required. The current set up has a 6 Bar supply, 6mm nylon air pipe approx 15 meters in length from the SOV to the cylinder (double acting), the sov has a 1/8 port and the cylinder has a 1/8 port. The cylinder bore is 2", a stroke length of approx 450mm and moving a weight of approx 270kg.

It is taking approx 30 sec to operate from limit to limit and i require an operation time of no less than 10 sec.

i would be very grateful for any help you could give.
 
S
Check to see if flow controls (speed controls) have been installed anywhere in the system and are impeding the flow, and adjust to be less restrictive if so.

Next step, move the valve to the other end of the 15m tubing run (at the cylinder end). If you want, you can go so far as to plumb the valve directly into the port of the cylinder. If the valve is manual and the cylinder location is inaccessible to people, replace the valve with an electric solenoid or remote air piloted valve (preferably electric solenoid) and locate the switch or air pilot valve where the people can operate it.

Once the 15m of tubing is continuously pressurized rather than switching from pressurized to exhaust with every stroke of the cylinder, consider replacing it with larger tubing, say 10-12mm so you don't get a lot of pressure drop. Alternatively, or in addition, you could install a pressure accumulator at the cylinder end of the tubing run before the valve.

Finally, depending on the configuration of the load, your cylinder may be a little undersized for moving 270kg (600lb) or your valve Cv may be too small. You might need to replace one or the other or both with a larger unit. Remember though, that if you replace the cylinder with a larger bore, its volume increases and all these other steps for optimizing response time will become even more critical.
 
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