- #1
ram18
- 15
- 0
hi ,
I am going to design sealpress mechanism for rotary system . I need to find out how much torque required to rotate my steel roller which is connected to end of my cylinder. from wikipedia i find out rolling resistance =
The force of rolling resistance, not adjusted for velocity, can be calculated by[3]:
F = Crr x Nf
where
F is the rolling resistance force (shown in figure 1),
Crr is the dimensionless rolling resistance coefficient or coefficient of rolling friction (CRF), and
Nf is the normal force (equal to W shown in figure 1, not just N shown in figure 1).
The coefficient of rolling friction for a slow rigid wheel, not adjusted for velocity, can be calculated by[1][2]
Crr = Sqr of z/d
where
z is the sinkage depth
d is the diameter of the rigid wheel
The force of rolling resistance can also be calculated by[1]:
F= Nf Xb/r
where
F is the rolling resistance force (shown in figure 1),
r is the wheel radius,
b is the rolling resistance coefficient or coefficient of rolling friction with dimension of length, and
Nf is the normal force (equal to W shown in figure 1, not just N shown in figure 1).
In my case I have steel roller and i am going to press buna(rubber) seal by roller .
So if i assume b = 0.4 inch , r = 1.75 , nf =500 pound
F = Nf x b /r = 500x 0.4 / 1.75 = 114.28 pound
so torque = force x radius = 114.28 x 1.75 = 199.99 inch-lb
If i change the radius of roller r = 2.25
F = Nf x b / r = 500x 0.4 / 2.25 = 88.88 pound
Torque = 88.88 x 2.25 = 199.99 inch -lb
so i got same torque that means radius of roller doesn't effect of torque . i am confused about that so please give me some right direction .
Thanks.
I am going to design sealpress mechanism for rotary system . I need to find out how much torque required to rotate my steel roller which is connected to end of my cylinder. from wikipedia i find out rolling resistance =
The force of rolling resistance, not adjusted for velocity, can be calculated by[3]:
F = Crr x Nf
where
F is the rolling resistance force (shown in figure 1),
Crr is the dimensionless rolling resistance coefficient or coefficient of rolling friction (CRF), and
Nf is the normal force (equal to W shown in figure 1, not just N shown in figure 1).
The coefficient of rolling friction for a slow rigid wheel, not adjusted for velocity, can be calculated by[1][2]
Crr = Sqr of z/d
where
z is the sinkage depth
d is the diameter of the rigid wheel
The force of rolling resistance can also be calculated by[1]:
F= Nf Xb/r
where
F is the rolling resistance force (shown in figure 1),
r is the wheel radius,
b is the rolling resistance coefficient or coefficient of rolling friction with dimension of length, and
Nf is the normal force (equal to W shown in figure 1, not just N shown in figure 1).
In my case I have steel roller and i am going to press buna(rubber) seal by roller .
So if i assume b = 0.4 inch , r = 1.75 , nf =500 pound
F = Nf x b /r = 500x 0.4 / 1.75 = 114.28 pound
so torque = force x radius = 114.28 x 1.75 = 199.99 inch-lb
If i change the radius of roller r = 2.25
F = Nf x b / r = 500x 0.4 / 2.25 = 88.88 pound
Torque = 88.88 x 2.25 = 199.99 inch -lb
so i got same torque that means radius of roller doesn't effect of torque . i am confused about that so please give me some right direction .
Thanks.