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Lead Screw model in Creo and calculations

  1. Feb 20, 2014 #1
    Hi

    I'm trying to make a lead screw in Creo which would be used to move a 400lb load linearly along the ground. This would be turned manually using a lever as shown in the pic (not the complete model). I have used a lead screw with a major diameter of 1 1/4 and determined the torque to move the load would be around 36.70 lb-in. What I'm unable to determine is the speed at which this would move the load a total distance of 3 feet, and if it would be possible to change this speed so that the lever doesn't have to be turned for quite a lot of time. Any help would be appreciated.

    Thanks in advance!
     

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  2. jcsd
  3. Feb 20, 2014 #2

    Baluncore

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    Welcome to the PF.
    The diameter of the lead screw is not the important parameter, you need to specify the pitch of the screw thread.
    That will tell you how far the load will move for each turn of the crank handle, (your lever).
    The speed you turn the crank will decide the speed the load moves.
     
  4. Feb 21, 2014 #3
    Hi

    Thanks for the reply. I took a TPI of 4 and etermined the torque required to move the load. I was basically looking for a way to related the RPM and the linear velocity, which I have figured out now.
    Also, I'm trying to determine the fail conditions for the L-shaped support holding the lead screw and the lever, but I have no clue where to start. I've been trying to run simulations in Creo to determine this but to no avail. What stresses and strains should I take into consideration? And how will a force or torque on the lever lead to failure of the support?

    Thanks!
     
  5. Feb 21, 2014 #4

    Baluncore

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    If you assume the base plate is firmly attached, then only the vertical part of the mount will deflect when an axial force is applied by the lead screw. That will bend the material that is between the base and the lead screw. When the material bends the screw will be misaligned in the thread which will have other implications.
     
  6. Feb 26, 2014 #5
    Thanks for the answer! I decided to perform the analysis in Workbench instead of in Creo and did manage to get some results from your answer.

    Thanks again!
     
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