Hadewe B.v.

Ydo N Hoekstra

Klaas Drenth

Klaas Dreuth

An apparatus for verifying any of a plurality of predetermined compositions of multilayered units composed of stacked sheetlike parts passed in spaced succession by a checkpoint, including 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.

Method of checking the composition of multilayer units composed of

A method for verifying any of a plurality of predetermined compositions of multilayered units composed of stacked sheetlike parts passed in spaced succession by a checkpoint, including the steps of determining a first value according to a thickness of a first unit of a first predetermined composition; storing the first value as a reference value for the first predetermined composition; determining a second value according to a thickness of a successive unit intended to have the first predetermined composition; comparing the reference value with the second value; and rejecting the successive unit when the second value is outside a tolerance range around the reference value; wherein the first and second values are calculated from a plurality of measurements taken during at least one predetermined measuring interval along each of the first unit and the successive unit, respectively, at least one limit of the at least one measuring interval being related to the passage of a transverse edge of the respective unit such that the 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.

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Joure, Netherlands

Ydo N Hoekstra