Device for monitoring the depletion of material uncoiling from rolls, applicable in particular to wrapping machines

• US 5,177,446 A
• Filed: 07/03/1990
• Issued: 01/05/1993
• Est. Priority Date: 07/05/1989
• Status: Expired due to Term

• Current Assignee: G. D. Societa Per Azioni
• Original Assignee: G. D. Societa Per Azioni
• Inventors: Boriani, Silvano, Gamberini, Antonio
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): Regan, Maura K.
• Application Number:
  US07/547,182
• Time in Patent Office: 917 Days
• Field of Search: 242/57, 340/675, 324/671, 324/660, 324/661-663
• US Class Current: 324/671
• CPC Class Codes: B65H 23/005 Sensing web roll diameter warning or safety devices responsive to a predetermined diameter B65H26/08
• CPC Class Codes: B65H 2701/52 Integration of elements inside the core or reel

Abstract

A sensing facility that is integrated into a station from which strip material is fed to a wrap station, and/or into the roll and shaft from which the strip is effectively uncoiled, is designed to monitor an electrical impedance generated by the roll and shaft and/or linked to their overall radial dimensions. An output signal is triggered when the monitored level of impedance matches a selected reference value.

Claims

1. A device for monitoring depletion of a continuous strip of material uncoiling from a roll of a wrapping machine, comprising:

a feed station having at least one roll-and-roll-shaft assembly rotatable about the longitudinal axis of the roll and roll shaft thereof, for uncoiling a continuous strip of material coiled on the roll thereof;

a wrap station, arranged to be supplied with said continuous strip of material as said strip is uncoiled from said roll of said roll-and-roll-shaft assembly of said feed station;

sensing means, located at one of said feed station and said roll-and-roll-shaft assembly for sensing an electrical impedance that is generated by at least one of;

said roll of said roll-and-roll-shaft assemblies, and

a function of location of an imaginary cylindrical shell of known radius located between opposite ends of said roll shaft and coaxial with said axis, and

for relaying an output signal upon encountering a value of impedance which is at least as great as a preset reference value;

said sensing means including;

a cylindrical element located between and coaxial with said roll and said roll shaft;

a shoe or plate occupying a fixed radial position in relation to said cylindrical element, said cylindrical element and said shoe or plate being separated by a distance that is sufficiently great as to permit mounting a full said roll when bearing a predetermined full amount of said continuous strip of material coiled thereon, on said shaft;

an electrical power source, to which said shoe or plate and said cylindrical element are both operatively connected in such a way as to constitute respective armatures of a capacitor stage in which the dielectric is provided by said strip of material coiled on said roll, and of which the capacitive reactance is a function of the thickness of the material of said strip occupying the space between said cylindrical element and said shoe or plate, permittivity of said material being par; and

measurement and comparison means, operatively connected to said capacitor stage for generating an output signal upon sensing an impedance which is at least as great as a selected reference value.

2. A device for monitoring depletion of a continuous strip of material uncoiling from a roll of a wrapping machine, comprising:

a feed station having at least one roll-and-roll-shaft assembly rotatable about the longitudinal axis of the roll and roll shaft thereof, for uncoiling a continuous strip of material coiled on the roll thereof;

a wrap station, arranged to be supplied with said continuous strip of material as said strip is uncoiled from said roll of said roll-and-roll-shaft assembly of said feed station;

sensing means, located at one of said feed station and said roll-and-roll-shaft assembly for sensing an electrical impedance that is generated by at least one of;

said roll of said roll-and-roll-shaft assemblies, and

a function of location of an imaginary cylindrical shell of known radius located between opposite ends of said roll shaft and coaxial with said axis, and

for relaying an output signal upon encountering a value of impedance which is at least as great as a preset reference value;

said sensing mans including;

a cylindrical element which is located radially between and disposed coaxial with said roll and said roll shaft;

a shoe or plate carried by an arm pivotably anchored at one end to said feed station and riding in permanent radial contact with the strip coiled onto said roll;

an electrical power source, to which said shoe or plate and said cylindrical element are both operatively connected in such a way as to constitute respective armatures of a capacitor stage in which the dielectric medium is provided by said strip of material coiled on said roll, and of which the capacitive reactance is a function of the thickness of the material of said strip occupying the space between said cylindrical element and said shoe or plate, permittivity of said material being par;

measurement and comparison means, operatively connected to said capacitor stage for generating an output signal upon sensing an impedance which is at least as great as a selected reference value.

3. A device for monitoring depletion of a continuous strip of material uncoiling from a roll of a wrapping machine, comprising:

a feed station having at least one roll-and-roll-shaft assembly rotatable about the longitudinal axis of the roll and roll shaft thereof, for uncoiling a continuous strip of material coiled on the roll thereof;

a wrap station, arranged to be supplied with said continuous strip of material as said strip is uncoiled from said roll of said roll-and-roll-shaft assembly of said feed station;

sensing means, located at one of said feed station and said roll-and-roll-shaft assembly for sensing an electrical impedance that is generated by at least one of;

said roll of said roll-and-roll-shaft assemblies, and

a function of location of an imaginary cylindrical shell of known radius located between opposite ends of said roll shaft and coaxial with said axis, and

for relaying an output signal upon encountering a value of impedance which is at least as great as a preset reference value;

said sensing means including;

a cylindrical element secured coaxially to said roll shaft beyond the axial extent of said roll;

a shoe or plate occupying a same diametral plane, relative to said axis, as said cylindrical element and carried by a freely revolving roller mounted to an arm pivotably anchored at one end to said feed station and riding in permanent circumferential contact with said strip of material coiled onto said roll;

an electrical power source, to which said shoe or plate and said cylindrical element are both operatively connected in such a way as to constitute respective armatures of a capacitor stage in which the dielectric medium is air, and of which the capacitive reactance is a function of the distance separating said cylindrical element and said shoe or plate;

measurement and comparison means, operatively connected to said capacitor stage for generating an output signal upon sensing an impedance which is at least as great as a selected reference value.

4. A device for monitoring depletion of a continuous strip of material uncoiling from a roll of a wrapping machine, comprising:

a feed station having at least one roll-and-roll-shaft assembly rotatable about the longitudinal axis of the roll and roll shaft thereof, for uncoiling a continuous strip of material coiled on the roll thereof;

a wrap station, arranged to be supplied with said continuous strip of material as said strip is uncoiled from said roll of said roll-and-roll-shaft assembly of said feed station;

sensing means, located at one of said feed station and said roll-and-roll-shaft assembly for sensing an electrical impedance that is generated by at least one of;

said roll of said roll-and-roll-shaft assemblies, and

a function of location of an imaginary cylindrical shell of known radius located between opposite ends of said roll shaft and coaxial with said axis, and

for relaying an output signal upon encountering a value of impedance which is at least as great as a preset reference value;

said sensing means including;

a pair of rollers disposed for permanent contact with, respective opposite faces of said strip of material adjacent where said strip of material uncoils from said roll, said rollers being operatively connected to an electrical power source by a relative circuit and being thereby provided with a potential difference which is less than the dielectric strength of the material from which said strip of material is made;

an electrically conductive band of material arranged for application to said strip of material during manufacture of said strip of material, at a point coinciding with a radially inner coiled turns of said strip of material on the roll, said band having dimensions such as to interconnect and short-circuit said rollers in said relative circuit;

measurement and comparison means incorporated into said relative circuit connecting the rollers with said power source, for generating an output signal upon sensing the passage of current of at least a given amount through said relative circuit.

5. A device for monitoring depletion of a continuous strip of material uncoiling from a roll of a wrapping machine, comprising:

a feed station having at least one roll-and-roll-shaft assembly rotatable about the longitudinal axis of the roll and roll shaft thereof, for uncoiling a continuous strip of material coiled on the roll thereof;

a wrap station, arranged to be supplied with said continuous strip of material as said strip is uncoiled from said roll of said roll-and-roll-shaft assembly of said feed station;

sensing means, located at one of said feed station and said roll-and-roll-shaft assembly for sensing an electrical impedance that is generated by at least one of;

said roll of said roll-and-roll-shaft assemblies, and

a function of location of an imaginary cylindrical shell of known radius located between opposite ends of said roll shaft and coaxial with said axis, and

for relaying an output signal upon encountering a value of impedance which is at least as great as a preset reference value;

said sensing means including;

an inductive proximity transducer carried by an arm pivotably anchored to said feed station and disposed substantially in contact with said strip of material wound onto said roll, and for generating a signal when a magnetic field of said transducer is damped by the proximity of a metal element applied to the strip at a point coinciding with a radially inner coiled turn of said strip of material on said roll.

7. A device as defined in claim 5, wherein:

said inductive proximity sensor is carried by a freely revolving roller mounted to said pivotally anchored arm and riding in permanent circumferential contact with said strip of material coiled onto said roll.

6. A device for monitoring depletion of a continuous strip of material uncoiling from a roll of a wrapping machine, comprising:

a feed station having at least one roll-and-roll-shaft assembly rotatable about the longitudinal axis of the roll and roll shaft thereof, for uncoiling a continuous strip of material coiled on the roll thereof;

a wrap station, arranged to be supplied with said continuous strip of material as said strip is uncoiled from said roll of said roll-and-roll-shaft assembly of said feed station;

sensing means, located at one of said feed station and said roll-and-roll-shaft assembly for sensing an electrical impedance that is generated by at least one of;

said roll of said roll-and-roll-shaft assemblies, and

a function of location of an imaginary cylindrical shell of known radius located between opposite ends of said roll shaft and coaxial with said axis, and

for relaying an output signal upon encountering a value of impedance which is at least as great as a preset reference value;

said sensing means including;

an inductive proximity transducer carried by an arm pivotably anchored to said feed station for generating a signal when a magnetic field of said transducer is damped by the proximity of a cylindrical metal element associated with said roll shaft.

8. A device as defined in claim 6, wherein:

said inductive proximity sensor is carried by a freely revolving roller mounted to said pivotally anchored arm and riding in permanent circumferential contact with said strip of material coiled onto said roll.