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Torque required to rotate this wheel?

  1. Jul 10, 2014 #1
    Dear experts,
    I am an electrOnics engg and weak in mech parts .
    please refer to the attached images of this hand machine,
    The wheel at the top weighs 30 kg and is rotated through hand because of which the horizontal plate attached at the bottom moves down and cuts objects using die placed.

    I want to rotate this wheel using single phase Ac motor at around 30-60 rpm but I have no idea of torque required and the rating of motor to buy.
    Can anybody please help.
    Wheel weight -30 KG
    Wheel diameter - 60 cm

    Thanks in advance, Please help
     

    Attached Files:

  2. jcsd
  3. Jul 10, 2014 #2

    Simon Bridge

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    The net torque required to turn a wheel at a constant rate is zero. Torque is a kind of force - do you remember Newton's Laws?

    Losses in the mechanism tend to depend on speed, this is why you need a non-zero applied torque to maintain a constant speed. You want to use a motor to apply some torque. What is important here is how fast you want to get up to that speed - you'll want a throttle on the motor to keep it there.

    Bottom line - the information is not enough to do a calculation - we need to know about the lubricant and the contact points and so on as well. You'll have to measure the required torque or the losses.
     
  4. Jul 10, 2014 #3
    Thank Simon for replying.
     
  5. Jul 11, 2014 #4
    Hi Simon,

    I m planning to rotate the above wheel clockwise for 360 degrees and then anticlockwise for next 360 degree and repeating this pattern alternately, so definately there will be some torque required.
    This alternate rotation I will be doing eith the help microcontroller and relay.

    If you can just give a rough idea about what rating motor should I buy, whether it is 1HP or 2HP.
    Or whether 2 HP mottor will be sufficient to rotate the wheel ?
     
  6. Jul 11, 2014 #5
    I think it would be easiest to just measure the torque needed as the press is applied by hand. The highest torque will be right towards the end of the stroke, and will be determined by how much output force you need to apply, and the ratio and efficiency of the screw.

    If you can use a digital torque wrench to drive the wheel to see how much torque is being used, you will have a number to work with.

    If you put a gear reduction on it, a much smaller motor can be used, of course, and you will probably be best off just replacing that heavy wheel with a lighter large diameter gear, pulley or sprocket, and using that as your reduction gear/belt/chain drive.
     
  7. Jul 12, 2014 #6

    Simon Bridge

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    Of course there will be - you are not paying attention: torque causes acceleration.

    Probably a 0.25hp motor will turn the wheel - slowly.
    Please pay attention - to know about the torque required, we need to know about how still the wheel is and how quickly you want it to change it's speed.

    You are best to just measure it.
     
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