Converting from air cylinders to ???

[chadzeilenga]

We currently have a testing apparatus which is powered by an air cylinder. This apparatus operates in temp ranges from -40C to 85C. This system pushes a rack at a speed of approximately 0.13 ft/s.

When using this apparatus in the cold temp environment, the valves must be opened up all the way and this is difficult to do considering the configuration. Does anyone know much about electronic acutators for this type of application??

Thanks,
Chad

 

[Barry1961]

How much force and stroke are we talking about?

Barry1961

 

[chadzeilenga]

The rack has an approximate operating torque of 0.069 N*m. The stroke is up to 6"

 

[tygerdawg]

http://www.yamaharobotics.com

http://www.intelligentactuator.com

there are others on the market for pre-packaged electronic linear actuators, but these two come to mind. That -40C may be a little tricky, tho

TygerDawg

 

[Barry1961]

You may be able to use a small gearmotor. Probably 1/50th hp and around 240:1. With a 3" radius crank you could get your 6" stroke. Brother and Sumitomo make good gearmotors in this range and can be packed with extreme temp. grease. Probably run in the $250 range.
I did an application like this testing the pull of a vent cable in a car. The gearmotors smooth operation was a great improvement over the air cylinders jerky motion.

Barry1961

 

[chadzeilenga]

A gear motor is a good idea that would probably work well with some modification. Right now I am only trying to replace what we have with something better. Something which would require the least amount of modification to the exisiting test aparatus.

Chad

 

[jsummerfield]

Often spring loaded pneumatic actuators are used for their stored energy advantages over motor operated electrical actuators.

John

 

[chadzeilenga]

Thanks to all who have given suggestions. I have been in contact with a few companies regarding this issue and hopefully we will be able to get something to work for us.

Jsummerfield: I don't think that spring loaded pneumatic actuators would work in this situation since they are dual acting cylinders where we use a flow control to adjust the rate of travel in each direction.

Chad

 

[SteveMeisel]

Try Intelligent Actuators linear motion products. We are currently using several of them. They have been very reliable.

 

[chadzeilenga]

After playing with some "low-temp" pneumatic cylinders and having little success I think we are ready to redesign our testing fixture to adapt a 90° gearmotor to the fixture. I have run through some quick calculations.

The -40°C operating torque of our parts is 28 oz-in. With 16 parts installed on our test fixture, this places the force required to move the table around 90 lbs. At 85C this force is reduced to 36lb. These are only approximated forces.
The maximum travel of our text fixture is 8", but we normally only use 2-3" and use end stops to limit this.
Does anyone have any suggestions regarding the hp and rpm rating of the gearmotor that we try out?

 

[chadzeilenga]

 

[chadzeilenga]

Our parts fit into the round recesses in the green bars and engage with the gear teeth on the sliding table.

 

[pallen3]

We use air cylinders for many of our test fixtures. For low temprature testing, we insist on quality air driers and we adapt an external heating system to the cylinders. Usually something similar to wraping pipes to prevent them from freezing.

So far this has worked for us and other machine builders in the same industry.