Figuring out Gear ratio and motor torque on a flat conveyor
Figuring out Gear ratio and motor torque on a flat conveyor
(OP)
I am looking at using a MK conveyor that you can mount fixtures on to hold parts that will be driven by a servo motor and a gear box. The total weight of all of my fixtures and parts that will be on the conveyor is 100 pounds. The conveyor will have to move 360mm every 18 seconds and needs to move this distance in 1 second. The conveyor has a belt radius of 52mm.
I wanting to know how to figure the gear box ratio that I will need and the servo motor torque that I will need. Can anybody help me out? I do not want to know the answer, I want to know how you can get the answer so that I can figure this out on my own next time.
I wanting to know how to figure the gear box ratio that I will need and the servo motor torque that I will need. Can anybody help me out? I do not want to know the answer, I want to know how you can get the answer so that I can figure this out on my own next time.





RE: Figuring out Gear ratio and motor torque on a flat conveyor
In the interest of "just making sure", add at least 0.1 g to the theoretical acceleration to account for friction, etc., and that is for clean conditions, if you are conveying rocks through a mine in a dirty environment, the friction could be much bigger than this.
Figure out the total mass of all the parts, the fixtures, and the belt.
F = m x A
T = F x R (at the conveyor pulley)
Figure out the rotation speed of the conveyor pulley at the conveyor's needed top speed
The ratio between that rotation speed and the rotation speed of commonly available motors will tell you the gearbox ratio.
Then figure out the theoretical torque without considering frictional losses.
Obtain the efficiency of the gearbox and obtain the required motor output torque accounting for gearbox losses.
It would be wise to add some percentage to the calculation results, both in terms of torque and speed, just to make sure.
RE: Figuring out Gear ratio and motor torque on a flat conveyor
RE: Figuring out Gear ratio and motor torque on a flat conveyor
With the conveyor having a radius of 52mm that would equal the circumference of 0.32656 meters. So with one revolution of the conveyor I almost travel the distance needed. I will be using a servo motor and the gear ratio will be determeind on the RPM of the motor I pick. Could you show me how you calculate the torque so that I understand it
RE: Figuring out Gear ratio and motor torque on a flat conveyor
With the conveyor having a radius of 52mm that would equal the circumference of 0.32656 meters. So with one revolution of the conveyor I almost travel the distance needed. I will be using a servo motor and the gear ratio will be determeind on the RPM of the motor I pick. Could you show me how you calculate the torque so that I understand it
RE: Figuring out Gear ratio and motor torque on a flat conveyor
With the conveyor having a radius of 52mm that would equal the circumference of 0.32656 meters. So with one revolution of the conveyor I almost travel the distance needed. I will be using a servo motor and the gear ratio will be determind on the RPM of the motor I pick. Could you show me how you calculate the torque so that I understand it
RE: Figuring out Gear ratio and motor torque on a flat conveyor
RE: Figuring out Gear ratio and motor torque on a flat conveyor
RE: Figuring out Gear ratio and motor torque on a flat conveyor
There is no single unique solution to moving 360mm in 1 second so you just have to pick something that works. For example, you could instantaneously accelerate to 360mm/s and then run at constant 360mm/s and instantaneously decelerate. This gives the lowest top speed but of course instantaneous acceleration requires infinite force and so this solution is not practical. An attempt to come close to this would be violent on your fixtures and workpieces.
Another choice is to accelerate uniformly over 1/2 second to some top speed that we don't yet know and then decelerate uniformly to zero over the next 1/2 second. This motion profile will minimize the acceleration.
From basic dynamics
D = 1/2 * a * T^2
We know D (= 180mm, half the distance that you need to travel) and we know T (1/2 second, half the time available) so solve for a:
a = 2 * D / T^2 = 2 * 0.18 / (0.5^2) = 1.44 m/s2 (For reference, gravity is 9.81 m/s2 so this is quite plausible and achievable)
We need that top speed ...
V = A * t = 1.44 * 0.5 = 0.72 m/s
Other motion profiles are possible. You could accelerate a bit harder to a slightly lower top speed, plateau there for some period of time, then decelerate slightly harder. It's an arbitrary choice at that point. But if your drive is capable of giving the speed above, and capable of delivering something greater than the calculated acceleration given above, you will have some room to make that decision later.
Can you take it from there? I know you said you didn't want numbers, but it's too hard to explain this concept without applying some numbers to it, might as well use yours.
RE: Figuring out Gear ratio and motor torque on a flat conveyor
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com
RE: Figuring out Gear ratio and motor torque on a flat conveyor
I'll just add that each of his suggested motion profiles have distinct discontinuities in the velocity vs. time profile - hence theoretically infinite jerk at those transitions.
A sinusoidal motion profile would avoid that.
RE: Figuring out Gear ratio and motor torque on a flat conveyor
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