energy needed to cut a hole
energy needed to cut a hole
(OP)
Hi all.
I have to cut sae 1070 Harden and tempered to 55 HRC, blue spring strip, 0.5mm thick 6 mm diameter hole.
It is done by hiting a 6 mm punch , made from HSS, to the such strip. I did it by a hammer about 1000 grams by my arm force.
It Works.
But I want to do it by a free fall weigth, or potential energy.
So my question is : how much energy is need to cut such hole.
For a 55 HRC the ultimate yield is about 212 Kg/mm2, so for a 6 mm diameter there is 6 mm * pi* 0.5 mm = 9.42 mm2 area
and for this ultimete yield 9.42 mm2 * 212 Kg/mm2 = 1997.04 Kg
But this is weigth , not energy.
As the work to do is seldom used I want to make the free fall hammer . The allowed heigth will be 2.00 meter , what will be the hammer weigth.
It seem to be a lazy student home work , but not .
Furthermore that all we are allways student I'm 55 old mechanics and want to know the theory on this fact.
I have to cut sae 1070 Harden and tempered to 55 HRC, blue spring strip, 0.5mm thick 6 mm diameter hole.
It is done by hiting a 6 mm punch , made from HSS, to the such strip. I did it by a hammer about 1000 grams by my arm force.
It Works.
But I want to do it by a free fall weigth, or potential energy.
So my question is : how much energy is need to cut such hole.
For a 55 HRC the ultimate yield is about 212 Kg/mm2, so for a 6 mm diameter there is 6 mm * pi* 0.5 mm = 9.42 mm2 area
and for this ultimete yield 9.42 mm2 * 212 Kg/mm2 = 1997.04 Kg
But this is weigth , not energy.
As the work to do is seldom used I want to make the free fall hammer . The allowed heigth will be 2.00 meter , what will be the hammer weigth.
It seem to be a lazy student home work , but not .
Furthermore that all we are allways student I'm 55 old mechanics and want to know the theory on this fact.
Pardal





RE: energy needed to cut a hole
The formula I have is for the punching force and is :-
F=1.5 x s x L x t
where s= ultimate shear stress of the material
L= perimeter
t=material thickness
ultimate shear stress for a material = 0.7 x ultimate
tensile strength
so to calculate the energy required then:-
energy = force x (the distance the force it acts over)
so using your figures 212kg/mm^2 x 0.7=148.4kg/mm^2
blanking force =148.4 x 1.5 x 6 x 3.142 x 0.5=2098.2276kg
energy req= 2098.2276kg x 9.81 (to convert kg to newtons)x
0.0005m
energy req = 10.29J
mass req at a 2m height
energy = mass x 9.81 x 2
10.29j/(9.81 x2)=mass=2.098kg
please note these formula are approximations only.
hope this helps
regards
desertfox
RE: energy needed to cut a hole
0.6 is closer to the shear strength / tension strength ratio for most materials. Was that a typo?
RE: energy needed to cut a hole
It was no typo according to my machinery's hand book
all steels listed which include steels from the sae range and structural,stainless are given a maximum shear stress
of 0.75 x u.t.s.
I am aware though that this figure for shear can vary some use 50%, some 60% and others 70 to 75% depends what your doing and what safety factor you use.
regards
desertfox