Packaging machine

Abstract

A packaging machine including a supply of film for wrapping a package and a hot plate for heat fusing the film of a wrapped package. Power to the heating element is only delivered to the element during a heating cycle, thus conserving electrical power. A photo eye senses the package and a control circuit energizes the heating element the element reaches a desired heating temperature in 2 to 4 seconds. The frame of the machine includes a lower base member to which an upper base plate, preferably formed from a continuous sheet, is rigidly attached. The upper plate includes a support surface for the hot plate, a vertical wall to which the photo eye is attached that is interconnected with the support surface by a curved transition surface. The upper base plate also includes a lateral, rearwardly extending plate portion which defines at least a portion of a hardware enclosure.

1 . A packaging machine for wrapping a package with a stretchable film, the packaging machine having a frame defining a wrapping surface, a supply of wrapping film accessible by an operator, a means for severing a length of film used to wrap a package from the supply and a hot plate including a heating element for fusing at least a portion of the film that is wrapped around the package, said packaging machine comprising a package sensor for sensing the presence of a package to be sealed, said sensor forming part of a heating circuit for said heating element that applies power to said heating element when a package is sensed, said sensor comprising a photo eye assembly arranged such that it senses a package to be sealed as it is placed on said hot plate. 
     
     
         2 . The apparatus of  claim 1  wherein said heating element is energized for as long as a package to be sealed is sensed by said photo eye assembly. 
     
     
         3 . The apparatus of  claim 1  further including a temperature response device associated with said heating element for deenergizing said heating element if a predetermined operating temperature is exceeded. 
     
     
         4 . The apparatus of  claim 1  further comprising a temperature controller which modulates power to said heating element to maintain said heating element at a predetermined temperature. 
     
     
         5 . The apparatus of  claim 4  further comprising a feedback component which senses temperature of said heating element and communicates with said temperature controller. 
     
     
         6 . The apparatus of  claim 5  wherein said feedback component comprises a thermistor. 
     
     
         7 . The apparatus of  claim 3  wherein said temperature responsive device is a thermostat. 
     
     
         8 . The apparatus of  claim 1  further comprising an interval timer for controlling a maximum time that said heating element can be energized. 
     
     
         9 . The apparatus of  claim 1  wherein said frame comprises:
 a) a lower base member having integrally formed side plates and laterally extending tabs defining a mounting location for a cut-off rod and at least one upturned mounting flange; 
 b) an upper base plate defining a substantially horizontal support surface for said hot plate and a vertical wall interconnected with said support surface by a curved transition portion and further including a substantially laterally extending enclosure portion for defining a portion of a hardware enclosure located between the side plates of said lower base member when said upper base plate is mounted to said lower base member; and 
 c) said upper base plate further including at least one downwardly depending flange that is engageable with said upturned flange of said lower base member. 
 
     
     
         10 . A packaging machine for wrapping a package with a stretchable film, the packaging machine having a frame defining a wrapping surface, a supply of wrapping film accessible by an operator, a means for severing a length of film used to wrap a package from the supply and a hot plate including a heating element for fusing at least a portion of the film that is wrapped around the package, said packaging machine comprising:
 a) a lower base member having integrally formed side plates and laterally extending tabs defining a mounting location for a cut-off rod and at least one upturned mounting flange;   b) an upper base plate defining a substantially horizontal support surface for said hot plate and a vertical wall interconnected with said support surface by a curved transition portion and further including a substantially laterally extending enclosure portion for defining a portion of a hardware enclosure located between the side plates of said lower base member when said upper base plate is mounted to said lower base member; and   c) said upper base plate further including at least one downwardly depending flange that is engageable with said upturned flange of said lower base member.   
     
     
         11 . The apparatus of  claim 10  further comprising a vertical plate member for joining said enclosure portion of said upper base plate with said lower base member. 
     
     
         12 . The apparatus of  claim 10  wherein said vertical wall portion mounts said photo eye assembly. 
     
     
         13 . The apparatus of  claim 10  further comprising a bridge plate pivotally mounted between said side plates of said lower base member. 
     
     
         14 . The apparatus of  claim 5  wherein said feedback component comprises a thermocouple. 
     
     
         15 . The apparatus of  claim 10  wherein said lower base member and said upper base plate are formed from a substantially continuous metal sheet. 
     
     
         16 . A packaging machine for wrapping a package with a stretchable film, comprising:
 a) a supply of wrapping film accessible by an operator and a frame defining a wrapping surface;   b) a heated rod for severing said film;   c) said frame defined by a lower base member and an upper base plate, said base member and upper plate formed from a continuous sheet material;   d) a hot plate for fusing at least a portion of the film that is wrapped around a package;   e) an optical sensor for sensing the presence of a package to be sealed on said hot plate, said sensor forming part of a heating circuit for communicating power to said hot plate when a package is sensed.   
     
     
         17 . The packaging machine of  claim 16  wherein said optical sensor is a photo eye assembly. 
     
     
         18 . The packaging machine of  claim 17  wherein said upper base plate defines a support surface for said hot plate, a substantially vertical portion to which said photo eye assembly is mounted and a lateral portion at least partially defining an enclosure.