Pneumatic speed

[steppmjk]

We need to increase the speed and force of our kicker.we have two 3/4" x5 double action cylinders on it now.Would increasing the diameter of the cylinders help?Also we use surgical tubing to assist , would it be better to use single action cylinders or should we stay with the double action that we have?

[sgreco]

Do you think you can provide us with a picture?

A bigger bore cylinder will be able to pull back more force in springs, but if you don't have a separate release mechanism you'll find that the cylinder is restricted by friction in the cylinders linear slide and how fast air can exit.

[karpiron]

Are you using a dedicated solenoid for each accuator

[Mark McLeod]

Increasing the cylinder diameter increases the force, but decreases the speed.

Adding more cylinders can maintain the same speed, and increase the force.

Some speed increase can be obtained by opening up the exhaust port of the cylinder to the atmosphere (remove all fittings and use the bare cylinder port) and retracting it with a spring or elastic, like surgical tubing.
The problem with having a cylinder directly in the loop is that it will act as a shock absorber by slowing your kick to the speed that air can be pushed out of the open end of the cylinder or pumped into the charged end.
One way around this problem is to latch the cylinder partially extended and precharge it to get around the 1/4" feed tube restriction. Then release the latch.

[jspatz1]

Are you using two solenoid valves, one on each cylinder? Do so if not. In the past we have even used two solenoid valves on each cylinder (some inspectors crinkled their nose at this.) The flowrate through the valve is your primary bottleneck. Increase the amount of tension on your elastics until the return force of the cylinders can barely hold it back, this will maximize their contribution to your speed and force.

[steppmjk]

We're using one valve for both cylinders.what kind of latch can I use to load the system?

[Mark McLeod]

A regular gate latch is the most common I've seen used this year with a separate tiny cylinder to unlatch it.
If you do the precharge trick don't pull the cylinder all the way back when it latches. Leave a couple of inches of cylinder as precharge volume.

You can also do a variation, such as

1. using a cylinder to pull back a heavily elastic powered kicker
2. latching it back
3. returning the cylinder to it's forward position
4. opening the latch to kick
5. repeat.

[steppmjk]

Thanks for your help I'll giv eit a try

[dtengineering]

Put your valves as close to your cylinders as you can so you keep your tubing runs short (you have to vent/pressurize the tubing as well as the cylinder, remember).

Try putting a clippard tank right next to the valves on the low pressure side of the system. That means you've got lots of 60psi air right next to your valves, and close to your cylinders. You can even use the brass fittings to connect your vavles directly to the cylinder.

Jason

[steppmjk]

Do you think two smaller cylinder is better than one large one?

[Daniel_LaFleur]

Originally Posted by jspatz1

Are you using two solenoid valves, one on each cylinder? Do so if not. In the past we have even used two solenoid valves on each cylinder (some inspectors crinkled their nose at this.) The flowrate through the valve is your primary bottleneck. Increase the amount of tension on your elastics until the return force of the cylinders can barely hold it back, this will maximize their contribution to your speed and force.

This may or may not be true. There can (and usually are) many 'bottlenecks' in a pneumatic system such as using 'Tee' fittings instead of 'Y' fittings. Do not assume that your bottleneck is the valves, instead test,test,test.

Originally Posted by steppmjk

We're using one valve for both cylinders.what kind of latch can I use to load the system?

Each cylinder has a volume that is to be filled. The valve has a flow rate (Cv) for which only a certain amount of air can pass (actually the flow rate is a curve based on pressure difference across the orifice). You'll need to find the appropriate flowrate to volume ratio for your needs.

Standard gate latch from home Depot.

Originally Posted by Mark McLeod

A regular gate latch is the most common I've seen used this year with a separate tiny cylinder to unlatch it.
If you do the precharge trick don't pull the cylinder all the way back when it latches. Leave a couple of inches of cylinder as precharge volume.

You can also do a variation, such as

1. using a cylinder to pull back a heavily elastic powered kicker
2. latching it back
3. returning the cylinder to it's forward position
4. opening the latch to kick
5. repeat.

These tips are probably the best.

Originally Posted by dtengineering

Put your valves as close to your cylinders as you can so you keep your tubing runs short (you have to vent/pressurize the tubing as well as the cylinder, remember).

Try putting a clippard tank right next to the valves on the low pressure side of the system. That means you've got lots of 60psi air right next to your valves, and close to your cylinders. You can even use the brass fittings to connect your vavles directly to the cylinder.

Jason

Jasons tips are for if you do not precharge your system. If you do precharge your system then you want the volume between the valve and the cylinder (giving more air in the precharge) and the largest orifice in between (1/8" to 1/8" nipple fitting).

Good luck.

[sgreco]

Originally Posted by dtengineering

Put your valves as close to your cylinders as you can so you keep your tubing runs short (you have to vent/pressurize the tubing as well as the cylinder, remember).

I'm curoius why this makes a difference? It's a closed system and (aside from the two pressure regulators), the pressure is constant thoughout the system regardless of the size. So when you release the solenoid, all you're doing is blocking one passage way and opening another, then the air gets redistributed. I'm sure there is a reason for your point, I'm just curoius what it is because before now I would have assumed that based on the nature of the system length/size shouldn't make a difference. Does it have to do with leaks? I'm aware there is air loss in the system, but wouldn't that be caused by the number of connection and not the length?

[IndySam]

Originally Posted by sgreco

I'm curoius why this makes a difference? It's a closed system and (aside from the two pressure regulators), the pressure is constant thoughout the system regardless of the size. So when you release the solenoid, all you're doing is blocking one passage way and opening another, then the air gets redistributed. I'm sure there is a reason for your point, I'm just curoius what it is because before now I would have assumed that based on the nature of the system length/size shouldn't make a difference. Does it have to do with leaks? I'm aware there is air loss in the system, but wouldn't that be caused by the number of connection and not the length?

The air has to flow through the hose. The higher pressure air moves through the hose in a wave that replaces the lower pressure air. In a shorter hose that wave will reach your cylinder faster. Trust me, it makes a big difference.

[steppmjk]

Anyone have any data on surgical tubing, like best size or optimal power to stretch?