Tubular Heater With External Thermocouple

Abstract

The problems associated with the prior art have been overcome by the present invention, which describes a tubular heating element having a more reliable and accurate temperature monitoring system. The tubular heating element has a thermocouple attached to its exterior surface, in close proximity to the cutting and sealing portion of the tubular heating element. In addition to improving the accuracy of the temperature measurement, this technique reduces electromagnetic interference caused by the interaction between the heating wire and the thermocouple.

What is claimed is: 
     
         1 . A side sealing machine for sealing a film, comprising:
 a tubular heating element, having an exterior, a hollow cavity within the tube, a leading edge adapted to encounter said film first, and a trailing edge adapted to encounter said film after said leading edge;   a heating element disposed within said hollow cavity of said tubular heating element, to heat said tubular heating element; and   a thermocouple disposed outside of said tubular heating element to monitor a temperature of said exterior of said tubular heating element.   
     
     
         2 . The side sealing machine of  claim 1 , wherein said thermocouple is encased in a sheath, wherein said sheath contacts said exterior of said tubular heating element. 
     
     
         3 . The side sealing machine of  claim 2 , wherein said sheath contacts said tubular heating element at a position where said tubular heating element contacts said film. 
     
     
         4 . The side sealing machine of  claim 2 , wherein said sheath is thermally bonded to said tubular heating element. 
     
     
         5 . The side sealing machine of  claim 2 , wherein said sheath is mechanically coupled to said exterior of said tubular heating element. 
     
     
         6 . The side sealing machine of  claim 2 , wherein said sheath is biased toward said exterior of said tubular heating element. 
     
     
         7 . The side sealing machine of  claim 1 , wherein said thermocouple contacts said tubular heating element at a position where said tubular heating element contacts said film. 
     
     
         8 . The side sealing machine of  claim 1 , wherein said thermocouple is thermally bonded to said tubular heating element. 
     
     
         9 . The side sealing machine of  claim 1 , wherein said thermocouple is mechanically coupled to said exterior of said tubular heating element. 
     
     
         10 . The side sealing machine of  claim 1 , wherein said thermocouple is biased toward said exterior of said tubular heating element. 
     
     
         11 . The side sealing machine of  claim 1 , further comprising a biasing member attached to said trailing edge, which in one position, urges said trailing edge downward toward a plane of said film; and wherein said tubular heating element is rotatably attached to a pivot point on said machine. 
     
     
         12 . The side sealing machine of  claim 1 , further comprising a controller in communication with said thermocouple and said heating element so as to control a temperature of said tubular heating element in response to said thermocouple. 
     
     
         13 . A tubular heating element for use with a side sealing machine, comprising:
 a hollow cavity within the tube;   a heating element disposed within said hollow cavity of said tubular heating element, to heat said tubular heating element; and   a thermocouple disposed outside of said tubular heating element to monitor a temperature of said exterior of said tubular heating element.   
     
     
         14 . The tubular heating element of  claim 13 , further comprising a sheath that contacts said exterior of said tubular heating element, wherein said thermocouple is encased in said sheath to monitor a temperature of said exterior of said tubular heating element. 
     
     
         15 . The side sealing machine of  claim 14 , wherein said sheath contacts said tubular heating element at a position where said tubular heating element contacts said film. 
     
     
         16 . The side sealing machine of  claim 14 , wherein said sheath is thermally bonded to said exterior of said tubular heating element. 
     
     
         17 . The side sealing machine of  claim 14 , wherein said sheath is attached to said exterior of said tubular heating element using a mechanical coupler. 
     
     
         18 . The side sealing machine of  claim 14 , wherein said sheath is biased toward said exterior of said tubular heating element. 
     
     
         19 . The side sealing machine of  claim 13 , wherein said thermocouple contacts said tubular heating element at a position where said tubular heating element contacts said film. 
     
     
         20 . The side sealing machine of  claim 13 , wherein said thermocouple is thermally bonded to said exterior of said tubular heating element. 
     
     
         21 . The side sealing machine of  claim 13 , wherein said thermocouple is attached to said exterior of said tubular heating element using a mechanical coupler. 
     
     
         22 . The side sealing machine of  claim 13 , wherein said thermocouple is biased toward said exterior of said tubular heating element.