What is the Correct Approach to Calculating Torque Requirements in a Shaft Arrangement?

[Analysis]

Dear all,

I need clarification regarding torque requirement in the following arrangement.
Imagine a shaft 25mm diameter 600mm length simply supported and one end.
Gear is attached to drive the shaft.
Load is externally applied via lever arm and different material(polymer) same
diameter is in contact.
My query is what is the torque required to drive this shaft arrangement.
Load,shaft geometries,speed are the known values.


My approach is assumed that at static condition load is applied over shaft, finding

the reaction force at each bearing end and from this force multiplied by bearing

mean radius with co efficient of friction of bearing which is normally(0.0025max).


Is the approach is correct?

1)My suspect is when applying force to the bearing, friction coefficient will
increase how to change of friction is accommodated?
2)Rollers in contact with pressure, to overcome frictional resistance will be less
only i.e. shaft in contact assume that 100 N is acting,to overcome this force we
will multiply with friction coefficient of two materials say 0.3 and the calculation is
100 x 0.30=30N is enough to overcome the force of 100 N
3)To find reaction force at the ends can i use of 30N instead of 100N?
4)Suppose reaction force will changes in each end,say one end is 50 N and
another end is 35N can i take highier value?
5)Above is that running torque what will the empherically starting torque to select
induction motor or servo drive motor specification.can i take say 1.5 times
running torque for both? Can i use T=IxAlpha approach?
6)In this gear is going to drive the shaft gear PCD has any influences?bcoz gear
radius is used to drive the shaft torque?

(Since image is not uploading i am narrating the problem)

Thanks in advance
Prakash

 

[LightHero]

Your approach is correct. To answer your questions: 1) The friction coefficient will depend on the materials used in contact, as you noted. You can adjust the coefficient to account for this. 2) Yes, you can use 30N instead of 100N. 3) Yes, you can take the higher value. 4) Yes, you can take 1.5 times the running torque for both. T=IxAlpha is a valid approach. 5) The gear PCD has an influence if it affects the torque transmission. If the gear is too small, it may not be able to transmit enough torque.

 

[astrokreng]

Dear Prakash,

Thank you for your detailed description of your arrangement and query regarding torque requirements. Your approach of calculating the reaction force at each bearing end and multiplying it by the bearing's mean radius and coefficient of friction is correct in theory. However, there are some factors that may affect the accuracy of your calculation.

1) The friction coefficient may vary depending on the material and surface finish of the bearing and shaft. It is important to accurately determine the coefficient of friction in order to get an accurate torque requirement.

2) The pressure between the rollers and the shaft may also affect the frictional resistance. If the pressure is not evenly distributed, it may cause uneven wear and affect the overall torque requirement.

3) Using the calculated frictional force of 30N instead of the applied force of 100N may underestimate the torque requirement. It is important to consider the actual applied force in your calculation.

4) It is recommended to use the higher value of the reaction force at each end to ensure that the bearing is able to support the load.

5) The starting torque of the motor will depend on the type and size of the motor, as well as the load and speed requirements. It is best to consult with a motor specialist to determine the appropriate starting torque for your specific application. The T=IxAlpha approach can be used for calculating the required torque for a specific acceleration or deceleration.

6) The gear PCD may have some influence on the torque required to drive the shaft, as it affects the gear ratio and the amount of force applied to the shaft. However, the gear PCD alone cannot determine the torque requirement and other factors, such as the gear's material and surface finish, must also be considered.

I hope this helps clarify your query. It is always best to consult with a specialist or perform thorough testing to determine the accurate torque requirement for your specific arrangement.