FP HW Tips

[woody]

the ball valve wont be fully open before the ram has reached end stroke

Are you sure?

OK ...What is the opening time of a 1 bore 3 stroke ram when supplied with 150 psi by a std 1/4 port 5/2 valve with a Cv of around 1.2?



The ram setup I suggested had a LOADED opening time of 0.12 sec... So...

BTW ..What is the opening time for a Burkert ?




(Message edited by woody on May 07, 200

[maddox]

Burkert gives a responce time of 0.05 seconds.

[wazio]

Hehehe, this is exactly what I wanted to see two different views on things and reasons to back them€¦

I like the simplicity of the solenoid valves, on and off, easy to set up and wire, however I don€™t really like the amount of tubing, size and fittings that will be required.

I like the ball valve because of the inline easy open/close but that is another whole system to fuss with and a bit more complex than the on off from the above system€¦

Hmmmmm


What are the normal ram sizes in your HW€™s? We were thinking in the ball park of 6€x8€-ish€¦ What is this Woody valve you speak of? We are trying to get a CNC shop to do some work for us so if might not be out of the realm of possibility.

[woody]

Cheers Mario ...
Working out the opening time for the ball valve will require finding the load or torque to open it.
A value picked off the net suggests 110 lbf-ins for a 1 ball valve.

Throwing some values in the calculators gives me a loaded opening time of around .09 second ( when using the afore mentioned 1 bore 3 stroke ram @ 150 psi )....increasing the bore to 1.25 gives us some extra OOoomph and reduces the calc opening time to 0.066 second with a required Cv of around 0.5.

Standard disclaimer ...
IF Ive got my calculations correct etc ..

[woody]

A F.P. 3 port valve made by me sometime ago...

http://www.robowars.org/forum/album_pic.php?pic_id=1422http://www.robowars.org/forum/album_pic.php?pic_id=1422

http://www.robowars.org/forum/album_pic.php?pic_id=1420http://www.robowars.org/forum/album_pic.php?pic_id=1420

Currently residing in my Feather

[m2xt]

Mario,

I have no problem in getting the ball valve open before the ram fully strokes. Also, its not just about valve operating times, its also about restrictions which serve to slug the gas flow from the buffer to the ram. You have far more restrictions in solenoid valve installations than in ball valve solutions. Having tried both methods its a no brainer as far as I am concerned. Design your ball valve system right and I believe it will out perform multiple solenoid valve designs.

[beast]

its not getting the ram up i have truble with its getting it back down quick
thats why i left a spring in our hydralic ram to pull it back down, but another 2kg of weight and i im giving up with bungy lol

but either system should work good enough

[maddox]

Im not convinced that the added low pressure set up in the robot is an advantage.

The most ideal solution is to use a fully custom build balanced valve. Or get the QEV -Bufferram- working.

Chad, multiple burkerts just require a nicely designed manifold. Or can be connected to each other with off the shelf hydraulic parts.

(Message edited by maddox on May 07, 200

[m2xt]

Mario, I totally agree that the LP side is a pain but at the time I wanted the ultimate performance that I could achieve using my own tools. Not only that, but it is variable pressure from 10 to 50 bar controlled from the Tx so I had both a LP flipper and a HP flipper and everything in between. Shame it drove like a sack of spuds and the flipper kept breaking open the back of the bot. The only other design I have tried that came close was a design based on the impact ram principle but that was inherently unsafe and let down by a poor build.

[maddox]

Paul, I can achive the variable pressure as well, nothing difficult to it, just requiring a servo to adjust a setting. But I didnt use it before, because it defeats the KISS idea.

Also, something I learned , flow and pressure , as well ramsize arent everything. In Hannibalito1 I tried several flipper arm leverages and lengths, and its a huge difference, even with minimal changes.

But my own guidelines.
Buffertank volume 3* ram volume
1 Burkert is good for a 70mm bore ram
2 Burkerts are good for 100mm bore
and 140mm bore needs 4 burkerts.

Flipperarm at least 5 times stroke. Point of impact depending on force on the ram, but leverage so that at least 5 times the weight of the to be trown opponent is available on the point.