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Method of checking the composition of multilayer units composed of sheetlike parts and apparatus for composing, and checking the composition of, such units

  • US 5,265,733 A
  • Filed: 03/11/1992
  • Issued: 11/30/1993
  • Est. Priority Date: 02/22/1989
  • Status: Expired due to Term
First Claim
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1. A method for verifying any of the plurality of predetermined compositions of multilayered units composed of stacked sheetlike parts passed in spaced succession by a checkpoint, comprising the steps of:

  • determining a first value according to a thickness of a first unit of a first predetermined composition;

    storing said first value as a reference value for said first predetermined composition;

    determining a second value according to a thickness of a successive unit intended to have said first predetermined composition;

    comparing said reference value with said second value; and

    rejecting said successive unit when said second value is outside a tolerance range around said reference value;

    wherein said first and second values are calculated from a plurality of measurements taken during at least one predetermined measuring interval along each of said first unit and said successive unit, respectively, at least one limit of said at least one measuring interval being related to the passage of a transverse edge of the respective unit such that said measurements are taken along a section of the respective unit having one end located a selected distance from said transverse edge where the measured thickness in the section is substantially uniform and representative of the composition of that unit;

    wherein said tolerance range is one half of a value corresponding to a thickness of the thinnest sheetlike part of any of the plurality of predetermined compositions; and

    wherein said reference value for any unit is determined according to calculations of reference values associated with units of a different composition.

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