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Homework Help: Lead screw and frame calculations

  1. Sep 30, 2010 #1
    Hi

    I am new to the design game as it where and I have scoured books and the internet looking for calcs, examples, help with a design I am putting together which involves raising and lowering a heavy object using a lead screw. I know its not strictly CNC stuff but I believe someone may be able to help with the power screw/lead screw side of the design. I have attached images to aid in the understanding.

    The system is straight forward, a yellow bracket which is hung supports the system and allows the system to slide left and right on Winkel Rollers. The main body of the system (in green) consists of a box section frame with guide channels and houses the lead screw. The screw is turned by an operator which raises and lowers the slide (shown in orangy-red) again using winkel rollers in the guide channels. The slide has a rotating arm (in cyan) which swings the wheel clear.

    Basically I need to do some scoping calcs and I don't know where to start. Obviously at this stage the scoping is to make sure the design is actually feasable so its section sizes, lead screw size etc... and making sure its all not going to fail under load.

    So i'm lookto make sure the channel and angle on the yellow bracket can take the load from the main body and wheel.

    The box section, channel, platesm winkel wheels and lead screw can take the load of the wheel, slide and arm

    The slide can take the load of the arm and wheel

    The arm can take the load of the wheel.

    I'm hoping you can help me calc the lead screw size. The lead screw is zzzmm long, trapazoidal thread (if this it he best) and is to raise and lower around 250kg. There is no desired speed of lowering/raising as the screw will be turned via handwheel or socket, either way the rotation will be provided by the operator.

    Of course if you can help with any of the other sections that would be brilliant. For my attemt at the calcs I took the main body (green) in isolation and worked on the assumption is supported at the base and that the 250kg load is just acting in a linear fashion up and down the lead screw. (as per image 4)

    Any help would be greatly, GREATLY appreciated. And if you can help but need more information please do not hesitate to ask.

    I am not neccessarily looking for the answers but if the formula I require or some instructions on how I can quickly go about analysing the structure and get what I need, that would be great.

    I also have a 3D PDF i can post - email as neccessary.
     

    Attached Files:

  2. jcsd
  3. Sep 30, 2010 #2
    sorry, I missed image 4 off.
     

    Attached Files:

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