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  • Calculate Time For A Sprng Index Plunger To Release

    Discussion in 'Calculations' started by rustie, Dec 4, 2013.

    1. rustie

      rustie New Member

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      Hi,

      I need to calculate the speed for an index plunger to fully release.

      The basic setup is simple. It is pretty much identical to a collapsible loft ladder......Within a sliding mechanism, we have a fixed plate and a sliding plate. A plunger is housed within the fixed plate. This plunger is compressed as it is pressed against the sliding plate. The sliding plate has a through hole in it. As this sliding plate slides across the fixed plate the through hole will at some point align with the spring plunger. At which the plunger will be free to release.

      The challenge is the moving plate moves very very quickly. I need to ensure that the spring plunger can release quickly enough to guarantee the plunger engages into the sliding plate. Can anybody suggest how I can calculate the speed for the plunger to release.

      Thanks.
       
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    3. Erich

      Erich Well-Known Member

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      Draw a Free body diagram of the plunger.
      Put all the forces acting on the plunger.
      Spring force, friction between plunger and housing, Friction between nose of plunger and moving plate are some of the forces that I think are involved. You know your mech better so you may need to add some.

      Use Newtons Second Law. Sum of Forces = Mass*Acceleration.

      Integrate once to get velocity.
       

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