Method and Apparatus for Tail Sealing of Roll Products

Abstract

A circumferential location of a tail end of a log of convolutely wound web material is determined by rotating the log in a stationary position and a diameter of the log is sensed with a sensor at a plurality of times while rotating the log in the stationary position. A plurality of signals corresponding to the diameter of the log at the plurality of times are generated. The signals corresponding to the diameter of the log at the plurality of times a compared. A change in the signals corresponding to the diameter of the log at the plurality of times is detected and associated with the circumferential location of the tail end of the log.

What is claimed is: 
     
         1 . A method of determining a circumferential location of a tail end of a log of convolutely wound web material, the method comprising:
 a) rotating the log in a stationary position;   b) with a sensor, sensing a diameter of the log at a plurality of times while rotating the log in the stationary position, and generating a plurality of signals corresponding to the diameter of the log at the plurality of times;   c) comparing the signals corresponding to the diameter of the log at the plurality of times;   d) detecting a change in the signals corresponding to the diameter of the log at the plurality of times, and   e) associating the change in the signals with the circumferential location of the tail end of the log.   
     
     
         2 . The method of  claim 1  wherein the step of generating the plurality of signals corresponding to the diameter of the log at the plurality of times comprises generating a smoothed derivative representation of each of the signals. 
     
     
         3 . The method of  claim 1  further comprising directing an air blast toward the tail end of the log in one of a direction substantially the same as a winding direction of the log and a direction substantially opposite to a winding direction of the log. 
     
     
         4 . The method of  claim 1  wherein the step of rotating the log in a stationary position comprises rotating the log in a nip between a pair of spaced-apart, rotatable rollers. 
     
     
         5 . The method of  claim 1  further comprising further rotating the log to orient the tail end of the log to a selected position for further processing based upon the circumferential location of the tail end of the log. 
     
     
         6 . A method of determining a circumferential location of a tail end of a log of convolutely wound web material, the method comprising:
 a) rotating the log in a stationary position;   b) with a sensor, sensing a distance from the sensor to the log at a plurality of times while rotating the log in the stationary position, and generating a plurality of signals corresponding to the distance from the sensor to the log at the plurality of times;   c) comparing the signals corresponding to the distance from the sensor to the log at the plurality of times;   d) detecting a change in the signals corresponding to the distance from the sensor to the log at the plurality of times, and   e) associating the change in the signals with the circumferential location of the tail end of the log.   
     
     
         7 . The method of  claim 6  wherein the step of generating the plurality of signals corresponding to the distance from the sensor to the log at the plurality of times comprises generating a smoothed derivative representation of each of the signals. 
     
     
         8 . The method of  claim 6  further comprising directing an air blast toward the tail end of the log in one of a direction substantially the same as a winding direction of the log and a direction substantially opposite to a winding direction of the log. 
     
     
         9 . The method of  claim 6  wherein the step of rotating the log in a stationary position comprises rotating the log in a nip between a pair of spaced-apart, rotatable rollers. 
     
     
         10 . The method of  claim 6  further comprising further rotating the log to orient the tail end of the log in a selected position for further processing based upon the circumferential location of the tail end of the log. 
     
     
         11 . A machine having a pair of rotatable rollers, the rotatable rollers being spaced apart and forming a nip therebetween, the machine being configured to receive a log of convolutely wound web material into the nip between the rotatable rollers and to rotate the log between the rollers with the rollers, the machine further comprising a sensor adapted and configured to measure a distance from the sensor to an outer surface of the log when the log is located in the nip and rotated between the rollers, the machine further comprising a controller, the controller including a processor and memory, the controller being adapted and configured to: (i) process a plurality of signals from the distance sensor at a plurality of times during rotation of the log between the rollers, (ii) detect a change in the plurality of signals from the distance sensor at the plurality of times during rotation of the log between the rollers, (iii) associate the change in the signals with the circumferential location of the tail end of the log, and (iv) store a plurality of data structures in the memory of the controller, wherein the data structures comprise a plurality of data items associated together that are representative of the circumferential location of the tail end of the log. 
     
     
         12 . The machine of  claim 11  wherein the controller is configured to generate a smoothed derivative representation of each of the signals corresponding to the distance from the sensor to the log at the plurality of times when processing the plurality of signals. 
     
     
         13 . The machine of  claim 11  further comprising air pressure source, the air pressure source being arranged to direct pressurized air toward a tail end of the log in one of a direction substantially the same as a winding direction of the log and a direction substantially opposite to a winding direction of the log. 
     
     
         14 . The machine of  claim 11  wherein the controller is configured to rotate the log to orient a tail end of the log to a selected position for further processing based upon the circumferential location of the tail end of the log. 
     
     
         15 . A machine having a pair of rotatable rollers, the rotatable rollers being spaced apart and forming a nip therebetween, the machine being configured to receive a log of convolutely wound web material into the nip between the rotatable rollers and to rotate the log between the rollers with the rollers, the machine further comprising a sensor adapted and configured to measure a diameter of the log when the log is located in the nip and rotated between the rollers, the machine further comprising a controller, the controller including a processor and memory, the controller being adapted and configured to: (i) process a plurality of diameter signals at a plurality of times during rotation of the log between the rollers, (ii) detect a change in the plurality of diameter signals at the plurality of times during rotation of the log between the rollers, (iii) associate the change in the signals with the circumferential location of the tail end of the log, and (iv) store a plurality of data structures in the memory of the controller, wherein the data structures comprise a plurality of data items associated together that are representative of the circumferential location of the tail end of the log. 
     
     
         16 . The machine of  claim 15  wherein the controller is configured to generate a smoothed derivative representation of each of the diameter signals at the plurality of times when processing the plurality of diameter signals. 
     
     
         17 . The machine of  claim 15  further comprising an air pressure source, the air pressure source being arranged to direct pressurized air toward a tail end of the log in one of a direction substantially the same as a winding direction of the log and a direction substantially opposite to a winding direction of the log. 
     
     
         18 . The machine of  claim 15  wherein the controller is configured to rotate the log to orient a tail end of the log to a selected position for further processing based upon the circumferential location of the tail end of the log.