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  • Diamond lead screw (Self reversing screw)

    Discussion in 'The main mechanical design forum' started by abilash2006, Sep 23, 2014.

    1. abilash2006

      abilash2006 New Member

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      Dear Friends,

      I am looking to Design a self reversing diamond lead screw for cable winding on a new underwater winch application i am working on at present.

      Following are the data's -

      Winch drum core - 200 mm
      cable dia - 7 mm
      no of lays - 27

      Gear ratio - 2: 1 , Main shaft 150 RPM , Lead screw - 75 RPM

      Screw prawl travel - 187 mm ?
      Pitch on the diamond screw - 14 mm ?

      I would need to have some design drawings on the diamond screw . how the profile is cut and marked is what i would like to know to complete the shaft on my own.

      Any other example design of a diamond screw will also help.

      Thanks in advance.

      Kind Regards,

      Jana
       
    2.  
    3. Lochnagar

      Lochnagar Well-Known Member

      Joined:
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      Hi Abilash,

      With the pitch you have indicated (14mm) that is going to be a very thin pawl - which I think may give you a number of issues. (The pawls and levelwinds I have designed - have typically been for spooling cables down to a diameter of 16mm). It is unclear from your posting what sort of line pull you are talking about - but assuming it is not massive - then my suggestion would be to approach the problem slightly differently and do one of the following:-

      1. Consider using a small fleet angle - see the document below for an explanation of this - and you will not need a levelwind bar full stop. You might like to go and have a look at a telescopic crane - and you will see that they do not have any spooling device - they just rely on the very small fleet angle - and the drum self spools.
      http://www.bridon.com/usa/x/download...et%20angle.pdf

      2.Consider driving an ordinary ISO trapezoidal lead screw (clockwise and anti-clockwise) which thus moves a nut onto which you have the guide rollers attached - which ensures the wire is at the right position on the drum. This could be done with a DC electric motor - with a control algorithm - that moves the nut and guide rollers at the right speed across the front of the drum. This technology already exists - and has been used on subsea tether management systems.

      Hope this helps.
       

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