What will be required torque for motorised spool.

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Discussion Overview

The discussion focuses on calculating the required torque for a motorised spool intended to wind 5KM of fiber optic cable. Participants explore the necessary parameters for motor selection, including torque, power rating, and the impact of spool dimensions and acceleration on these calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant emphasizes the need to consider the worst-case mass of the unwound cable when calculating torque.
  • Another participant notes that a larger diameter spool requires more torque, particularly for acceleration.
  • There is a question about the appropriate basis for motor selection, with a suggestion to consider stall torque for reeling.
  • A participant shares their calculations for torque and power, using formulas involving force, acceleration, and velocity, and arrives at a power estimate of 0.443 KW.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the calculations or the selection criteria for the motor. There are differing views on the importance of spool dimensions and acceleration in determining torque requirements.

Contextual Notes

Some calculations depend on assumptions about the mass of the cable and the acceleration profile, which have not been fully detailed. The discussion also highlights the need for practical testing with a torque wrench, which may not be feasible at this stage.

mandarz
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For selecting motor... I need to calculate torque for motorised spool used to wind 5KM of fiber optic cable.

Cable O.D. 4mm.
The distance between flanges is 520mm.
Flange O.D. 650mm.
Application of spool is only reeling and unreeling. While unreeling will be done by manually.
Assume empty spool weight 20 Kg.
RPM=50


What will be torque and power rating?
 
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Welcome to PF;
At a constant speed - you only need torque for pulling the load and overcoming friction.
So you need the worst case mass of the entire unwound cable.

The dimensions of the spool are important - a large diameter spool needs more torque, particularly to accelerate.

The acceleration is important too - how fast do you want the spool to pin up to top speed?

If you already have a spool - turn it with a torque wrench and see.
 
Thanks Simon !

We don't have spool at the moment.

We are considering stall torque motor for reeling (Are you agree on this?, According to you selection of motor should be on what basis for this application?) .

Cable will be wind over 240mm barrel diameter.
 
mandarz said:
For selecting motor... I need to calculate torque for motorised spool used to wind 5KM of fiber optic cable.

Cable O.D. 4mm.
The distance between flanges is 520mm.
Flange O.D. 650mm.
Application of spool is only reeling and unreeling. While unreeling will be done by manually.
Assume empty spool weight 20 Kg.
RPM=50


What will be torque and power rating?

Welcome to the PF. You are supposed to show your own attempt at the solution when asking for help here on the PF. Please check your PMs.
 
Thanks Berkeman,

I have calculated as
1) T=F x r

where
F=ma

a=v square/r

v=pi x Dx N/60

power=force x velocity

with applying MKS units.. I calculated power as 0.443 KW.

Is this correct?
 

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