cylinder sizing
cylinder sizing
(OP)
Need help sizing a cylinder for an application, a little confused on calculating the force needed. We need to rotate a roller conveyor out of the way so a pallet car can pass by, drawing attached. We believe 2 pneumatic 4" bore cylinders with 24" of stroke and around 80psi will work. If any more info is needed let me know.
Thanks
Thanks





RE: cylinder sizing
Ted
RE: cylinder sizing
Certified SolidWorks Associate
SW2009 X64 SP4.1
Dell Precision T3600
Nvidia Quadro 4000
Xeon 3.2GHz Quad Core, 8GB RAM
Win 7 Pro X64
RE: cylinder sizing
Ted
RE: cylinder sizing
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: cylinder sizing
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: cylinder sizing
Your design is simple in building but complex in analysis.
Replace the bracket that you were attaching the piston to with a Pulley at the pivot point. Fix a cable to the pulley and run it around the pulley a couple of times and then have the actuator pull the cable. (like a garage door system).
This will create a constant moment arm for the actuator and your calculations will be simplified. You will want a damper on this so the unit never slams down.
Note
If you are feeling adventuresome you can change the pulley to a cam so that the torque exerted by the unit 17,700*cos(raised angle) = Actuator force * cam radius. Rearranging this cam radius = 17,700 * cos(raised angle)/(1625*2) where the raised angle goes from 0 to 90.
RE: cylinder sizing
Certified SolidWorks Associate
SW2009 X64 SP4.1
Dell Precision T3600
Nvidia Quadro 4000
Xeon 3.2GHz Quad Core, 8GB RAM
Win 7 Pro X64
RE: cylinder sizing
Right not it will go BANG! Very loudly, and probably only once.
RE: cylinder sizing
Ted
RE: cylinder sizing
RE: cylinder sizing
Also, 80 psi is getting kind of high. Most plants I have worked around want 60 psi as the maximum design pressure.
Agree with Mint Julep on the lowering. Think about this one.
RE: cylinder sizing
To Orkney the torque out properly you need to show the drawbridge at different angles with the cylindr connected.
At each position the vertical weight of the drawbridge multiplied by its horizontal distance to the hinge which gives the torque the cylinders must exert about the same hinge, so in order to get that you need to find the line distance perpendicular from the hinge to the cylinder line of action and multiply this by the force available in the cylinder.
Again you need to layout the drawbridge and cylinder in different positions because as the drawbridge rises the torque around the hinge decreases but your cylinder mechanical advantage also decreases as the drawbridge comes up and as mentioned by others there might not be enough advantage for the cylinder to do its job.
RE: cylinder sizing
A counter balance with perhaps a pneumatic worm gear driving a quarter circle gear would seem to be far mor controllable - provide smooth constant speed rotation and be able to inch the last few degrees to stop it clattering into things at the end of the action.
There's a reason that all lift bridges like this use counter weights.
A complete re-design me thinks....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: cylinder sizing
If the drawbridge is raised to less than 90 degrees or the cg is kept to the left of the hinge, gravity will return the drawbridge. The rate of descent can be controlled with a meter-out control on the cylinder exhaust cycle.
Ted