- #1
MOTASH
- 6
- 0
Hi All,
I'm working on some design and apparently my physics expertise are getting rusty,i'd appreciate some help with the following:-
I need to calculate the required torque for a stepper motor to rotate a solid cylinder with the following properties:-
radius : 20cm
height: 12cm
density : the cylinder shall be made of ABS, but having cavities(symmetrically spaced) filled with liquid(water), for simplicity i am assuming a homogeneous density of 1.1g/cm3
The cylinder is suspended vertically on bearing and i am ignoring static friction , the rotation is around the vertical axis
The stepper is expected to have 1.8deg/step, and speed of 30rpm
I've done some math trying to calculate the torque required to rotate one step from rest :
Torque = Moment of inertia * Angular Acceleration
Cylinder mass : 16.587kg
Moment of inertia : 0.33175 kg.m2
Step time (@30rpm) : 10ms
Ang. velcoity : 3.14159 rad/s
the acceleration figure will be ridiculous, leading to a very large torque(compared to the holding torque i get in datasheets)
what's wrong with the approach/units or should the result be compared to the stalling torque(never mentioned in datasheets of common steppers)
Any help is much appreciated
I'm working on some design and apparently my physics expertise are getting rusty,i'd appreciate some help with the following:-
I need to calculate the required torque for a stepper motor to rotate a solid cylinder with the following properties:-
radius : 20cm
height: 12cm
density : the cylinder shall be made of ABS, but having cavities(symmetrically spaced) filled with liquid(water), for simplicity i am assuming a homogeneous density of 1.1g/cm3
The cylinder is suspended vertically on bearing and i am ignoring static friction , the rotation is around the vertical axis
The stepper is expected to have 1.8deg/step, and speed of 30rpm
I've done some math trying to calculate the torque required to rotate one step from rest :
Torque = Moment of inertia * Angular Acceleration
Cylinder mass : 16.587kg
Moment of inertia : 0.33175 kg.m2
Step time (@30rpm) : 10ms
Ang. velcoity : 3.14159 rad/s
the acceleration figure will be ridiculous, leading to a very large torque(compared to the holding torque i get in datasheets)
what's wrong with the approach/units or should the result be compared to the stalling torque(never mentioned in datasheets of common steppers)
Any help is much appreciated