Demand Based Wrapping

Abstract

A control system for a wrapping apparatus may include a packaging material dispenser configured to dispense packaging material for wrapping a load. The control system may also include at least one sensor assembly configured to generate a signal based on instantaneous demand for packaging material at the load. The control system may further include a controller configured to control operation of the packaging material dispenser based at least in part on the signal.

1 . An apparatus for wrapping a load, comprising:
 a packaging material dispenser including a dispensing drive configured to drive the packaging material dispenser to dispense packaging material,   a relative rotation assembly configured to provide relative rotation between the packaging material dispenser and the load,   a first sensor assembly that senses a characteristic indicative of instantaneous demand for packaging material at the load by measuring at least one of:
 a first distance from a rotational axis of a packaging material dispenser or from a rotational axis of a rotating turntable for rotating the load to a point on a surface of the load, 
 a second distance from a point to a plane defined by a surface of a length of packaging material that extends between the packaging material dispenser and the load, or 
 a speed of packaging material dispensed by the packaging material dispenser at a location between the packaging material dispenser and the load, and 
   a controller that controls operation of the dispensing drive based at least in part on the sensed characteristic.   
     
     
         2 . The apparatus of  claim 1 , wherein the first sensor assembly monitors the speed of packaging material dispensed by the packaging material dispenser at the location between the packaging material dispenser and the load by sensing one of:
 a speed of the dispensed packaging material,   an amount of packaging material dispensed, or   relative movement of a path of the dispensed packaging material relative to the packaging material dispenser.   
     
     
         3 . The apparatus of  claim 1 , wherein the first sensor assembly monitors an idle roller engaging at least a portion of the dispensed packaging material. 
     
     
         4 . The apparatus of  claim 3 , wherein the first sensor assembly is configured to monitor a speed of rotation of the idle roller. 
     
     
         5 . The apparatus of  claim 3 , wherein the idle roller and the first sensor assembly are positioned downstream from a dispensing roller of the packaging material dispenser. 
     
     
         6 . The apparatus of  claim 1 , wherein the first distance is a distance between the first sensor assembly and the point on the surface of the load. 
     
     
         7 . The apparatus of  claim 6 , wherein the first sensor assembly and the point on a surface of the load are on one of:
 a line extending radially from a rotational axis of the load, or a line extending radially from a rotational axis of the packaging material dispenser.   
     
     
         8 . The apparatus of  claim 1 , wherein the second distance is a distance between the first sensor assembly and the plane defined by the surface of the length of packaging material that extends between the packaging material dispenser and the load. 
     
     
         9 . The apparatus of  claim 1 , wherein the first sensor assembly is coupled to the packaging material dispenser. 
     
     
         10 . The apparatus of  claim 1 , further including a second sensor assembly operatively coupled to a dispensing roller of the packaging material dispenser, the second sensor assembly configured to sense rotation of the dispensing roller. 
     
     
         11 . The apparatus of  claim 10 , wherein the controller sets operation of the dispensing drive such that a signal generated by the second sensor assembly is proportional to a signal generated by the first sensor assembly, during at least a portion of a wrapping cycle. 
     
     
         12 . The apparatus of  claim 1 , wherein the controller controls operation of the dispensing drive such that a predetermined ratio between an amount of packaging material dispensed and the instantaneous demand is achieved for at least a portion of the relative rotation. 
     
     
         13 . A method for wrapping a load, comprising:
 driving a packaging material dispenser to dispense packaging material with a dispensing drive,   providing relative rotation between the packaging material dispenser and the load,   measuring a characteristic indicative of instantaneous demand for packaging material at the load by sensing at least one of:
 a first distance from a rotational axis of the material dispenser or from a rotational axis of a rotating turntable for rotating the load to a point on a surface of the load, 
 a second distance from a point to a plane defined by a surface of a length of packaging material that extends between the packaging material dispenser and the load, or 
 a speed of packaging material dispensed by the packaging material dispenser at a location between the packaging material dispenser and the load, and 
   controlling operation of the dispensing drive based at least in part on the sensed characteristic.   
     
     
         14 . The method of  claim 13 , wherein controlling operation of the dispensing drive includes producing a predetermined ratio between an amount of packaging material dispensed and the instantaneous demand. 
     
     
         15 . The method of  claim 13 , further comprising:
 sensing rotation of a dispensing roller of the packaging material dispenser with a dispensing roller sensor assembly, and   generating a dispensing roller signal with the dispensing roller sensor assembly based on the sensed rotation of the dispensing roller.   
     
     
         16 . The method of  claim 13 , wherein sensing the characteristic indicative of instantaneous demand for packaging material at the load comprises:
 engaging the dispensed packaging material with an idle roller, and   sensing rotation of the idle roller with an idle roller sensor assembly.   
     
     
         17 . The method of  claim 16 , wherein sensing rotation of the idle roller with the idle roller sensor assembly includes generating an idle roller signal with the idle roller sensor assembly based on the sensed rotation of the idle roller. 
     
     
         18 . The method of  claim 17 , wherein controlling operation of the dispensing drive includes producing a predetermined ratio between the dispensing roller signal and the idle roller signal. 
     
     
         19 . The method of  claim 13 , wherein sensing the characteristic indicative of instantaneous demand for packaging material at the load comprises measuring the first distance between a distance measuring device and the point on the surface of the load. 
     
     
         20 . The method of  claim 13 , wherein sensing the characteristic indicative of instantaneous demand for packaging material at the load comprises measuring the second distance between a distance measuring device and the plane defined by the surface of the length of packaging material that extends between the packaging material dispenser and the load.