Clarification Reg linear Movement

[enggasw]

Hey all,

I was undergoing a project where I had to incorporate two pneumatic cylinders for up and down linear motion, at the top it is connected with an epoxy plate with pins, it supposed to move in a linear motion along with the cylinder to set the pins with pads. In this process after all the proceeding we had a problem of the pins not moving in a straight line, the linear movement is somewhere having a tilt while actuating, we couldn't be able to figure out why we get that tilt even there we had four guide shafts at the four corners along with linear bearing. Could anyone guide me to figure out the issue in it.​

 

[Tmoose]

Step 1 - post pictures

 

[MintJulep]

1. Real parts have size variation that your CAD model doesn't.
2. Real parts have clearance that your CAD model may or may not have.
3. Real parts, when connected together are rarely perfectly orthogonal like your CAD model.
4. Real pneumatic cylinders do not act with perfect synchronization like you hope that they do.
5. An "epoxy plate" (whatever that is) is probably bendy.

 

[desertfox]

Hi enggasw

Please post some pictures are drawings without some kind of image we’re all guessing.
That said four guide posts might be your problem.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Jboggs]

1. Using two actuators for one linear motion is NEVER a good idea.
2. Using cylinders as linear guides is also a bad idea. Here's why:
a> They do not respond well to side (lateral) forces.
b> Exactly coordinating the motion of two cylinders is not easy.
3. Using two or more cylinders to drive linear motion usually results in binding.

There are ways to coordinate the motion of two or more cylinders, but they do NOT involve guide shafts. The problem usually isn't in the "straightness" of the linear motion. The problem is the difference in speeds, friction, and forces at the two cylinder connection points.