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Manipulator Taber Bearing Problem

Manipulator Taber Bearing Problem

Manipulator Taber Bearing Problem

(OP)
Hi everyone.

I am designing a manipulator to hold the dashboard in an automotive company, the manipulator is supposed to carry a load of about 120 Kg at a maximum distance of 5 meters and it is used to transport that payload inside the car.

So I designed a system to have several rotational links and one linear motion at the end of the manipulator. As you imagine there is alot of axial load and moment, so I designed the bearing blocks for the rotational links as two taber bearing in an X configurations as seen in this image.


my current problem is that when I add the final link of the system, the manipulator deflects greatly at the bearing blocks as seen in the image.


Deflection at the bearing block


I have tried changing the bearings to larger sizes but its the same problem, I think its a problem of selection of taber bearing. is there any other bearing selection(I have thought about using a compination of thrust bearing and roller bearing) that would solve this problem or is it a problem of needing counterweight or wires to support the system?

I really need your support in this, appreciate any responses, thanks

RE: Manipulator Taber Bearing Problem

taPer bearing.

The internal shaft should be one piece, not a stub shaft with a bolt.

RE: Manipulator Taber Bearing Problem

I do work with bearings. But mostly with EDM. So I may not be qualified to give advice in this case. But:
The whole thing looks weak. There is a lot of newton-metres acting on the main bearing and I doubt if a solid shaft would help much. Did you do any calculation before selecting dimensions and structure?

I would go back to the drawing board and redesign the whole thing. The comBination should be designed to take up the same bending momentum as the sturdy bottom plate and pillar. Those are the only parts that doesn't yell "Help!" when you look at the design.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Manipulator Taber Bearing Problem

Are there 3 of those bearing assemblies in the arm?

What would an acceptable deflection be?

What is the maximum allowable rotating torque/friction per joint?
What size is bolt 1, and how tight are you tightening it?
I'm hoping all the components are steel, not aluminum.

Or as others pointed out, the disk secure by bolt 1 is separating from the shaft.
The bolt needs to be TIGHT and capable of providing clamping well in excess of the 600 kgm prying action. Also the face end of the shaft and the underside of the disk that form the clamped joint must be VERY flat, or better yet, very slightly concave to provide any real bending stiffness

It looks like the bearings may also be separating due to lack of preload.

I'm guessing even after the interface details and bearing arrangement are optimized, Much Larger diameters and well controlled preload and stiffer components and interfaces are needed.

RE: Manipulator Taber Bearing Problem

Based on the drawing you have provided, as assuming that 1) bearing sizes are sufficient and 2) the bearings are installed with sufficient preload..

Your stub shaft arrangement (where the flange and shaft are separate, and held together by a single fastener) is the weak point of this design.

The taper roller bearings you're using, with proper preload, are VERY stiff under radial loads; any deflection you're seeing is likely other parts.

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