Need Help With Off Center Axial Loading Calculations Please

[italyct23]

Hello,

I am using a hot press machine to press powder into a designated shape. The force comes from above the powder and is axial only. The powder is placed in a circular die and another "punch" is placed between the die and the actual pressing ram. I am trying to prove the implications of not centering the die with the punch and the punch with the ram. In other words, I think I am trying to prove that if one of these componenents is not lined up axially with the ram, the component may see some type of bending stress or something like that.

Please see this diagram for an example of the setup including an offset example:
[URL=http://img217.exs.cx/my.php?loc=img217&image=axialloading7dl.jpg

I have been searching through my mechanics of materials text book and haven't found any easy way of explaining this. I'm just looking for some simple calcualtions that show the severity of not lining all of these components up.

I appreciate any help that is offered.

Thank you,
Mike

 

[desertfox]

Hi italyct23

If you imagine that the ram see's the offset load then the
combined stress is that of the bending stress and normal
tensile stress ie:-

on one side of the ram the stress will be:- (W/A)+ My/I

and on the other:- (W/A)- My/I

where W=axial load
A= cross sectional area of the ram
M= bending moment due to offset of axial from the ram
centre

y= the distance from the neutral axis to the outer
surface of the ram

I= second moment of area of the ram


regards desertfox