Ironworker Shear apparatus

[bkufa]

Hello,

I am currently designing an Ironworker machine and I need help designing the shear. See my blog post for more info on the puropse of the machine. ( Removed Link to what appears to be a commercial site )

The shear will need to shear 1"x12" of A36 steel. I need to know what force is necessary when you are shearing with a rotating blade, or what moment would be necessary at the shearing point furthest from the pin. Even just how to calculate this would be valuble. Since the angle is changing therefore the thickness, I'm assuming you'd need some ridiculously complicated equation to find the necessary force.

I would like to use a rotating blade vs. a blade which moves vertically because the rotating blade Ironworkers usually have much simpler designs and need less force.

If it helps, I was told by an ironworker blade manufacturer that with a vertically moving blade with a 5 degree rake, you can shear it with 120 tons.

Any info helps, even just the right terminology.

Thanks,
Brianna

[PinkertonD]

Hi Brianna,

Just to get you started, it is not all that complicated. As a general guide, the force required will be (fairly) constant for the portion of metal in shear. How wide the material is does not really matter to any large degree. What matters is the length of material being torn apart (cut/sheared) at any given time and the maxium thickness at the start.

Shearing is not cutting per se, think of it as pushing one piece of metal past another, you just have to be breaking the moving piece off the fixed piece and that's where the force comes in.

Do you have a copy of Machinery's Handbook. All will be revealed.

[bkufa]

Hello Dave, thanks for the response, it definately helps my understanding.

The copy I have of it is from the 70's, but I can access newer ones from the library.

Could you tell me what keyword I should look up? I scoured the pages under shear and cutting in the index and couldn't find any info. The closest I came is the force to punch. It could be because its such an old book.

Thanks,
Brianna

[PinkertonD]

Hi Brianna,

Shearing metal is not a simple thing, it is a combination of processes. It starts out as bending, with the end result equivalent to the material failing to withstand the load applied. It depends on the strength of the material, the thickness, the shear area and a bunch more. It is not like calculating the circumference of a circle.

My 25th edition shows a goodly amount of stuff on shear and shearing. I am not sure why you can't find it in a 70s version as this is not new science.