Applied Mechanics- Design of hinge support brackets for load in Pin axial direction 2

[Tejas123]

Hi all,
Actully in my current project ,I want to rotate the arm about vertical axis i.e. in horizontal plane. But while rotating it has to carry high gravitational load at its other end. This load is giving vertical reactions in hinge C bracket ( in which pin and arm is fixed ), which I want to design.

I was thinking to make C bracket by welding the plates together providing stiffeners and all .
But the main issue is how and what will be reactions in this C bracket.
How to go for it?

Thanks in advance.

design configuration- Arm is placed inside C bracket and pin is put vertically through both elements for locking and giving rotational motion only in horizontal plane

 

[IFRs]

Is the free body diagram drawn to scale? If not, please do it again. I don't agree that welding is inherently bad - proper joint preparation and weld application along with some clean-up cam result in a very square and flat part. But that's for professionals.

 

[IFRs]

I would ignore moments, design for shear and use a factor of safety of 2 on yield. This is not a part on the space shuttle and a little extra weight will hurt. Consider the materials chosen - you want good shear and bearings strength combined with high toughness. I'm not a real fan of bushings because by definition they are soft and will wear. For an object that rotated 2x a year and otherwise just sits there, I'd consider making your C shape by welding and finish machining or just machining a block of steel, then drilling and boring tight tolerance through holes, and using cold rolled steel for the shaft.

 

[IFRs]

I will not go any further until you accurately represent the size and dimensions of the parts and the load. Also, who cares if it deflects a little ? - you need to define what constitutes appropriate behavior and what is a failure?

 

[chicopee]

Copious amount of grease may work if the motion of the arm is the number that you provided, therefore, grease fittings and channels may need to be incorporated and smooth out any sharp corners at the entry side of the"C" bracket.

 

[drawoh]

Tejas123,

Tolerances and relative dimensions are everything here. Your hinge will work one of two ways.

[ol]
[li]The arm will rotate, and contact the top and bottom flanges, causing a friction contact.
The pin will prevent the arm from being pulled out by sideways loads.[/li]
[li]The arm will rotate, and contact the pin, causing a friction contact. The bottom flange will keep the arm from dropping to the ground. [/li]
[/ol]

The lowest friction torque will come when you reduce the radius at which the friction operates. You want to contact the pin. As I noted above, the wider your C-bracket and your contact length is, the lower the forces will be.

--
JHG