Sealing System for a Packaging Apparatus

Abstract

A sealing jaw apparatus for a film wrapping machine utilizes a continuous web of thermoplastic film. The sealing jaw apparatus includes a first jaw unit to one side of a film travel path. The first jaw unit includes spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms. The heated sealing bar includes spaced-apart noses defining a slot therebetween. A second jaw unit is to an opposite side of the film travel path. The second jaw unit includes spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film. Spaced-apart sealing surfaces are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction. A knife assembly severs the thermoplastic film between the spaced-apart locations.

1 . A sealing jaw apparatus for a film wrapping machine utilizing a continuous web of thermoplastic film, the sealing jaw apparatus comprising:
 a first jaw unit to one side of a film travel path, the first jaw unit comprising spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms, the heated sealing bar including spaced-apart noses defining a slot therebetween; and   a second jaw unit to an opposite side of the film travel path, the second jaw unit comprising spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film, spaced-apart sealing surfaces that are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction, and a knife assembly for severing the thermoplastic film between the spaced-apart locations.   
     
     
         2 . The sealing jaw apparatus of  claim 1 , wherein the knife assembly is moveable between a retracted position where a cutting edge of the knife assembly is recessed from the sealing surfaces within a slot defined therebetween and an extended position where the cutting edge is extended beyond the sealing surfaces and into the slot between the noses. 
     
     
         3 . The sealing jaw apparatus of  claim 2  further comprising an actuator carried by the second sealing jaw unit that extends the knife assembly. 
     
     
         4 . The sealing jaw apparatus of  claim 1  further comprising metal support members carried by the second jaw unit that define the gripping surfaces. 
     
     
         5 . The sealing jaw apparatus of  claim 4  further comprising sealing members connected to the metal support members, the sealing members formed of an elastic material and forming the sealing surfaces. 
     
     
         6 . The sealing jaw apparatus of  claim 4 , wherein the sealing members are located within respective recesses formed in the metal support members. 
     
     
         7 . The sealing jaw apparatus of  claim 1 , wherein the clamp arms each include a gripping member located at an end of the clamping arm, the gripping member including a contoured end surface that engages the gripping surface. 
     
     
         8 . The sealing jaw apparatus of  claim 3 , wherein at least one of the first and second jaw units is moveable toward and away from the other of the first and second jaw units. 
     
     
         9 . The sealing jaw apparatus of  claim 8 , wherein the apparatus operates such that the knife assembly is maintained in the retracted position until the noses engage the spaced-apart sealing surfaces. 
     
     
         10 . A method of sealing layers of plastic film from a continuous film web, the method comprising:
 engaging the layers between a first jaw unit and a second jaw unit, the first jaw unit comprising spaced-apart clamp arms that engage spaced-apart gripping surfaces of the second jaw unit;   sealing the layers at two seal locations that are spaced-apart in a web running direction using a heated sealing bar carried by the first jaw unit and located between the spaced-apart clamp arms, the sealing bar including spaced-apart noses defining a slot therebetween, the spaced-apart noses engaging spaced-apart sealing surfaces carried by the second jaw unit; and   severing the layers between the first and second seal locations using a knife assembly carried by the second jaw unit.   
     
     
         11 . The method of  claim 10 , wherein the step of severing the layers includes extending the knife assembly from a retracted position where a cutting edge of the knife assembly is recessed from the sealing surfaces within a slot defined therebetween, beyond the sealing surfaces and into the slot between the noses. 
     
     
         12 . The method of  claim 11 , wherein the step of severing the layers occurs after the step of sealing the layers. 
     
     
         13 . The method of  claim 11 , wherein the knife assembly is extended using an actuator carried by the second jaw unit. 
     
     
         14 . The method of  claim 10 , wherein the step of sealing the layers at two seal locations further includes, after the spaced-apart clamp arms engage the spaced-apart gripping surfaces of the second jaw unit, extending the heated sealing bar relative to the clamp arms until the spaced-apart noses engage spaced-apart sealing surfaces carried by the second jaw unit. 
     
     
         15 . The method of  claim 14 , wherein the step of extending the heated sealing bar includes extending the heated sealing bar relative to the knife assembly. 
     
     
         16 . A sealing jaw apparatus for a film wrapping machine utilizing a continuous web of thermoplastic film, the sealing jaw apparatus comprising:
 a first jaw unit to one side of a film travel path, the first jaw unit comprising spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms, the heated sealing bar including spaced-apart noses defining a slot therebetween; and   a second jaw unit to an opposite side of the film travel path, the second jaw unit comprising spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film and spaced-apart sealing surfaces that are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction; and   a knife assembly for severing the thermoplastic film between the spaced-apart locations;   wherein the heated sealing bar moves relative to the knife assembly to bring the noses into contact with the spaced-apart sealing surfaces.   
     
     
         17 . The sealing jaw apparatus of  claim 16 , wherein the knife assembly is carried by the second jaw and is moveable between a retracted position where a cutting edge of the knife assembly is recessed from the sealing surfaces within a slot defined therebetween and an extended position where the cutting edge is extended beyond the sealing surfaces and into the slot between the noses. 
     
     
         18 . The sealing jaw apparatus of  claim 17  further comprising an actuator carried by the second sealing jaw unit that extends the knife assembly. 
     
     
         19 . The sealing jaw apparatus of  claim 16 , wherein the clamp arms each include a gripping member located at an end of the clamping arm, the gripping member including a contoured end surface that engages the gripping surface. 
     
     
         20 . The sealing jaw apparatus of  claim 16  further comprising metal support members carried by the second jaw unit that define the gripping surfaces.