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Shearbar clearance detector

  • US 4,412,212 A
  • Filed: 08/10/1981
  • Issued: 10/25/1983
  • Est. Priority Date: 08/10/1981
  • Status: Expired due to Fees
First Claim
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1. In a cutting machine having a shearbar and a plurality of blades movable with respect to the shearbar to cut material inserted therebetween, a clearance monitor for monitoring clearance between the blades and the shearbar, comprising:

  • a proximity sensor fixed with respect to the shearbar for sequentially generating a plurality of proximity signals, each proximity signal varying as a function of velocity and separation of the one of the plurality of blades with respect to the shearbar;

    an integrator coupled to receive the plurality of proximity signals, the integrator converting each proximity signal to a gap signal having a magnitude representing a minimum separation between the sensor and the corresponding blade, the magnitude of the gap signal being substantially independent of blade velocity;

    an averaging circuit coupled to sequentially receive the gap signals and generating an average gap signal representing an average over time of the minimum separations between the sensor and the plurality of blades;

    means for generating an offset signal having a desired magnitude;

    differential amplifier means for generating a difference signal representing a difference between the offset and the average gap signal;

    variable amplifier means for generating an output signal obtained by multiplying the difference signal by a predetermined gain factor;

    display means for generating an operator-detectable signal representing the output signal; and

    adjustable means for varying the magnitudes of the offset signal and the gain factor.

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