Minimum motor power for a mechanical horizontal sieving machine

In summary, the conversation discussed the calculations and equations used to determine the acceleration, friction force, crank force, total force, torque, and motor power needed for a motor to accelerate a screen and powder in a horizontal crank mechanism. The calculations were based on the values of r, l, angle, w, and n, and the final result was determined to be 50 watts. The conversation also mentioned the importance of adding a safety factor when selecting the motor for this application.
  • #1
khodournajem
2
0
Homework Statement
I'm making a small project (horizontal sieving machine)
i will use the crank slide mechanism , the doctor want from me to calculate the input power of the dc motor and the output power to calculate the efficiency of the system.
so i test the maximum load which is 10 kg equally distributed on a frame of 6 bearings of friction coefficient 0.3,
the minimum displacement of the net frame to begin sieving is 5 cm per 1 second which is 0.05/s meters,
so the crank radius will be 2.5 cm (0.025) that gives a 60 rpm and i am using a 10 cm connecting rode. so this is my critical issue.
is i'm thinking right ?
how can i calculate the power?
do i have to calculate the force of the crank ?
how can i calculate the output power if my result is correct.
please help
Relevant Equations
𝐹=μN

𝐹𝑐𝑟𝑎𝑛𝑘=ma

𝜏=F×d

P=τ×w
r = 2.5
l=10 cm
angle = 0 (maximum connecting rode elongation)
w = 0.5 (30 rpm)
n=10/2.5 = 4
so the acceleration is 1.5×0.5×0.5(1 + 1/4 ) = 0.4 m/s

friction force = 10*9.81*0.3 = 29.4 Newton.

Crank force is the mass of the object into acceleration.
So crank force = 10 × 0.4 = 4 Newton
Therefore total force will be: 29.4 + 4 =33.4 Newton.

Torque is the total force into the distance.
So torque = 33.4 × 0.05 = 1.67 N.m.

Finally motor power is the torque into the angular speed in minute.
Power = 1.67 × 30 = 50 watts.here is a approx picture (in my project the motor and the connecting rode and the frame is horizontally placed)
 

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  • #2
Welcome, khodournajem!

The motor will need to accelerate the mass of the screen and powder from V=0 to V=max at half of the stroke in certain period of time, while overcoming friction.
That will demand a horizontal force that can be calculated.
The crank mechanism will require the greater torque at certain angle position to provide that horizontal force.
Then, you can add some safety factor regarding the needed torque at the required rpm of your motor for its selection.

​

 
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Likes khodournajem
  • #3
thank you lnewqban for your time ,

i know these informations , i want to know if my calculations, used equations and last result are correct .
regards.
 

1. What is the minimum motor power required for a mechanical horizontal sieving machine?

The minimum motor power required for a mechanical horizontal sieving machine depends on various factors such as the size and type of the machine, the material being sieved, and the desired sieving efficiency. Generally, a motor power of at least 0.5 horsepower (HP) is recommended for small to medium-sized machines, while larger machines may require a motor power of 1 HP or more.

2. How does the motor power affect the performance of a mechanical horizontal sieving machine?

The motor power plays a crucial role in the performance of a mechanical horizontal sieving machine. A higher motor power allows the machine to run at a faster speed, resulting in a more efficient sieving process. It also enables the machine to handle larger quantities of materials and heavier loads, making it suitable for industrial applications.

3. Can a mechanical horizontal sieving machine operate without a motor?

No, a mechanical horizontal sieving machine cannot operate without a motor. The motor is responsible for providing the necessary power to drive the machine and create the necessary vibrations for sieving. Without a motor, the machine will not be able to function properly and may result in inaccurate or incomplete sieving results.

4. Is it possible to use a motor with a lower power rating for a mechanical horizontal sieving machine?

While it is possible to use a motor with a lower power rating for a mechanical horizontal sieving machine, it is not recommended. A lower power motor may not be able to provide enough force and speed for efficient sieving, resulting in longer sieving times and lower accuracy. It is best to use a motor with a power rating that meets or exceeds the recommended minimum for optimal performance.

5. Are there any safety precautions to consider when using a mechanical horizontal sieving machine with a motor?

Yes, there are a few safety precautions to consider when using a mechanical horizontal sieving machine with a motor. It is important to ensure that the machine is properly grounded, and all electrical connections are secure to prevent any accidents. It is also recommended to wear appropriate personal protective equipment, such as gloves and safety glasses, when operating the machine. Additionally, the machine should be regularly inspected and maintained to prevent any potential hazards.

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