Seam-detecting device for interconnected sections of sheet material
AssigneeJohannes Menschner Maschinenfabrik GmbH & Co. KG
InventorAlfonsius A. J. Van Dijk
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Abstract
A device for detecting transverse seams at the junctions of interconnected sections of fabric, paper or other sheet material, advancing continuously past a treatment station, comprises a plurality of sensors in the form of potentiometers whose sliders are provided with rollers contacting the sheet surface at transversely spaced locations which may also be relatively offset in the direction of travel. The output signals of the several potentiometers are compared in an evaluator which distinguishes actual seams from surface irregularities or from thickness variations forming part of a certain pattern. The evaluator includes signal-storing means facilitating the detection of seams deviating within given limits from a transverse line.
Claims12
In an apparatus for the continuous advancement of a web of consecutive sections of sheet material, overlappingly interconnected by generally transverse seams of greater thickness, through a treatment station,
- the combination therewith of a seam detector comprising:
- a support with a flat surface underlying the path of said web;
- a plurality of pairs of conjugate thickness sensors fixedly disposed above said support and provided with mobile contactors engageable with an upper surface of a section of sheet material passing over said support, each of said sensors including a generator of variable voltage depending on the position of the respective contactor;
- a plurality of differentiators each connected to said conjugate sensors of a respective pair for emitting output signals in response to a change in said variable voltage generated by one of the sensors of the respective pair, indicative of an increase in web thickness detected at a certain location, unaccompanied by a compensatory voltage change generated by the other sensor of the pair;
- and
- evaluation means connected to said differentators for signaling the passage of a seam in response to a predetermined combination of said output signals.
In an apparatus for the continuous advancement of a web of consecutive sections of sheet material, overlappingly interconnected by generally transverse seams of greater thickness, through a treatment station,
- the combination therewith of a seam detector comprising:
- a support with a flat surface underlying the path of said web;
- a first, a second and a third thickness sensor fixedly disposed above said support and provided with mobile contactors engageable with an upper surface of a section of sheet material passing over said support, each of said sensors including a generator of variable voltage depending on the position of the respective contactor, said first and second sensors being spaced apart in the direction of advancement, said first and third sensors being spaced apart in a direction transverse to the direction of advancement;
- and
- processing means connected to said sensors for signaling the presence of a seam in response to similar voltage changes generated by said first and third sensors within a predetermined interval of each other, indicative of increases in web thickness along a generally transverse line, unaccompanied by a compensatory voltage change generated by said second sensor.
Dependencies are inferred from the claim text.