Force amplifier question - (Toggle type linkage)

[harleykayak]

I'm getting along in years and it seems I've forgotten most of what I ever knew about linkage calculations and related formulas. I was wondering if someone could give me some help in determining what the resultant force I could get out of the mechanism depicted in the attached PDF file. It would be safe to neglect friction and linkage weights. I just need to know if the 2000 pound actuator would give me the pressing force I'm looking for when input via the toggle linkage.

 

[rb1957]

I find it hard to follow your drwg.

if "F_out" is the only reaction, the only connection to the rest-of-the-world, then F_out = F_in.

if there's another pivot point, then it'd be different ...

what is the Tee, with the blue dim'ns ? is it turning the curved arm ? about the "bearing" (at the bottom of the sketch) ? But the initial sketch doesn't appear to result in the final sketch ?? How about labelling some things ? how about showing the fixed points ? (maybe you are, with some Design icon convention, but I don't recognise it)

another day in paradise, or is paradise one day closer ?

 

[Nescius]

Sum the torques about the pivot point at the top of the C frame.

If the L-shaped member is in equilibrium, torque due to the 2000 lbf actuator will be counteracted by a force in the linkage bar that connects the L-shaped member and the ram.

The linkage bar force must act directly in line with the linkage bar itself, since it is pinned at each end. (As my physics professor said, "You can't push with a rope!")

The linkage bar will likewise act on the ram, a force that can be resolved into a vertical and a horizontal, side-load component.

Of course, as the linkage bar moves nearly in line with the ram, the theoretical mechanical advantage will approach infinity. The stiffness of the press will then rule the day.

 

[Jboggs]

If I understand your diagram correctly, the force F out resultant in the diagram on the left is determined only by the deflection and induced strain in the affected components, of which the arm with the 2000 lb force on it is not one.

 

[jlnsol]

Initial force when positioned as the right figure would be nearly 10 kN and the result force can be unlimited in left position, in other words result force can break the linkages when there is an hard end stop.

 

[waross]

If the left sketch is the final postion the force will approach infinity.
If the right skett h is towards the final position the force will approach zero.

For intermediate estimates determine how far the press will travel for a 1cm travel of the acting force.
Use that result to approximate the MA and the resultant force.

Bill
--------------------
"Why not the best?"
Jimmy Carter