meccanicamg
Guest
here we are with a sharing to do about cutting sheet with hydraulic shears.
in almost all the world, you calculate the cutting force (only to break the material) as:[math]f=\frac{0,8•uts•t2}{2•tan{\alpha}}[/math]where uts is the traction breaking load and t the thickness to be cut. the angle is the main inclination of the blade. someone says the value is too high.
on the book Machinery's handbook 29 and oberg, we talk about a formula, found not only in the American area but especially in the Asian area, where they use very shears that cut to the flight without stopping the tape.[math]f=\frac{n•k•μ·uts•t2}{tan{\alpha}}[/math]It is indicated that n is worth 0.75/0.85 for almost all materials and could be a kind of performance.
k is between 0.7 and 0.8 and represents the ratio between the value of uts and the cutting voltage.
μ represents the penetration percentage of the blade equal to the quantity cut and not torn. practically t•μ represents the first polished cut section of a sheet.
the table which relates the thickness t and the coefficient μ is as follows:
clearly that there are around fragile materials with also μ equal to 0.1-0,15-0,2.
this can be seen after cutting by measuring with the caliber.
in both cases, the strength obtained by 30% is increased to be able to win frictions of the axes that move and forces that arise from games wrong blades or broken blades.
the second formulation provides generally lower values than the first.
there are other formulations that indicate even lower values of cutting forces.
did any of you experiment by reading the pressures/forces by knowing uts, t and angle? have you noticed differences on slow and fast machines?other note: the second hydraulics with the cylinders from above have a speed of about 50mm/s and I think they have a fairly slow behavior compared to the shears moved by biella/handle that also arrive at 500mm/s. the energy of blade impact and material to be cut could adversely in the first case and favor in the second case the fracture making it seem lower however the cutting force with a fast machine. I believe that this follows the theory of fracture propagation that is studied in geometric defects or singularities.
I have seen that the big shears, with biella/manovella have often fly with energy up to 10 times what it takes to make a cutting and charging engines with factor 1.5/2 compared to what it would serve.
The side spins and horizontal separation of the blades multiplied by the friction coefficient affect a lot on baskets with bronze/steel lards to suck power to actuators.
it would be interesting to have a match with cutting range above 8-10-15-20mm.
in almost all the world, you calculate the cutting force (only to break the material) as:[math]f=\frac{0,8•uts•t2}{2•tan{\alpha}}[/math]where uts is the traction breaking load and t the thickness to be cut. the angle is the main inclination of the blade. someone says the value is too high.on the book Machinery's handbook 29 and oberg, we talk about a formula, found not only in the American area but especially in the Asian area, where they use very shears that cut to the flight without stopping the tape.[math]f=\frac{n•k•μ·uts•t2}{tan{\alpha}}[/math]It is indicated that n is worth 0.75/0.85 for almost all materials and could be a kind of performance.
k is between 0.7 and 0.8 and represents the ratio between the value of uts and the cutting voltage.
μ represents the penetration percentage of the blade equal to the quantity cut and not torn. practically t•μ represents the first polished cut section of a sheet.
the table which relates the thickness t and the coefficient μ is as follows:clearly that there are around fragile materials with also μ equal to 0.1-0,15-0,2.this can be seen after cutting by measuring with the caliber.
in both cases, the strength obtained by 30% is increased to be able to win frictions of the axes that move and forces that arise from games wrong blades or broken blades.
the second formulation provides generally lower values than the first.
there are other formulations that indicate even lower values of cutting forces.
did any of you experiment by reading the pressures/forces by knowing uts, t and angle? have you noticed differences on slow and fast machines?other note: the second hydraulics with the cylinders from above have a speed of about 50mm/s and I think they have a fairly slow behavior compared to the shears moved by biella/handle that also arrive at 500mm/s. the energy of blade impact and material to be cut could adversely in the first case and favor in the second case the fracture making it seem lower however the cutting force with a fast machine. I believe that this follows the theory of fracture propagation that is studied in geometric defects or singularities.
I have seen that the big shears, with biella/manovella have often fly with energy up to 10 times what it takes to make a cutting and charging engines with factor 1.5/2 compared to what it would serve.
The side spins and horizontal separation of the blades multiplied by the friction coefficient affect a lot on baskets with bronze/steel lards to suck power to actuators.
it would be interesting to have a match with cutting range above 8-10-15-20mm.
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