Sealing line adjustable sealing device

Abstract

A sealing device forms a sealing line on a package film enclosing an article with the package film being properly tensioned. The sealing device includes two conveyor belts for conveying the article and the package film in a forward direction. The conveyor belts are spaced from each other in the forward direction, defining a gap therebetween. A movable carrier plate carries and supports upper and lower sealing members with the conveyor belts arranged between the upper and lower members. The upper and lower members, to which heat sealing blades are attached, are moveable with respect to each other through the gap between the conveyor belts for bringing heat sealing blade to engage the package film, and thus forming a sealing line on the package film. A stationary bottom plate is arranged below the carrier plate and supports a plurality of guide rods movably engaging the carrier plate for guiding the movement of the carrier plate with respect to the conveyor belts. A motor is mounted on the bottom plate and is coupled to a worm-gear based speed reduction system. The worm, serving as an output shaft, threadingly and thus drivingly engages the carrier plate for moving the carrier plate along the guide rods thereby repositioning the upper and lower members with respect to the conveyor belts thereby changing relative position of the upper and lower member with respect to the article carried by the conveyor belts for adjusting the position of the sealing line.

What is claimed is  
     
         1 . A sealing device adapted to form a sealing line on a package film enclosing an article, the sealing device comprising: 
 a conveyor system adapted to convey the article and the package film;    a sealing system comprising a movable carrier plate on which upper and lower sealing members are mounted with the conveyor system arranged between the upper and lower members, the upper and lower members being moveable with respect to each other for engaging and forming a sealing line on the package film; and    an elevating means comprising: 
 a plurality of guide rods extending in a predetermined direction and movably engaging the carrier plate for guiding the movement of the carrier plate in the predetermined direction with respect to the conveyor system, and  
 a carrier moving system comprising a driving device and at least a toothed output shaft driven by the driving device and drivingly engaging the carrier plate for moving the carrier plate along the guide rods thereby re-positioning the sealing system with respect to the conveyor system and the article.  
   
     
     
         2 . The sealing device as claimed in  claim 1 , wherein the conveyor system comprises first and second conveyor belts spaced from each other, defining a gap therebetween through which the upper and lower sealing members move with respect to each other.  
     
     
         3 . The sealing device as claimed in  claim 1 , wherein each sealing member has a front edge and a lateral edge to each of which a heat-sealing blade is attached.  
     
     
         4 . The sealing device as claimed in  claim 1 , wherein the elevating means comprises a bottom plate on which the driving device and the toothed output shaft are mounted.  
     
     
         5 . The sealing device as claimed in  claim 1 , wherein the driving device comprises a motor.  
     
     
         6 . The sealing device as claimed in  claim 1 , wherein the driving device has an output spindle which is mechanically coupled to the toothed output shaft by a speed reduction system.  
     
     
         7 . The sealing device as claimed in  claim 6 , wherein the speed reduction system comprises a worm-gear speed reduction device comprising a worm on which the toothed output shaft is formed, the speed reduction device having an input shaft with a first gear mounted therein, a second gear being mounted to the spindle of the driving device and coupled to the first gear by a chain for driving the speed reduction system.  
     
     
         8 . The sealing device as claimed in  claim 6 , wherein the speed reduction system comprises two worm-gear based speed reduction devices mechanically coupled to each other for simultaneous operation.  
     
     
         9 . The sealing device as claimed in  claim 8 , wherein each speed reduction device has an input shaft with a gear mounted thereon, the gears being coupled together by a chain.  
     
     
         10 . The sealing device as claimed in  claim 1 , wherein the carrier plate comprises a threaded coupling member threadingly engaging the toothed output shaft of the carrier moving system for moving the carrier plate.  
     
     
         11 . The sealing device as claimed in  claim 1 , wherein the elevating means comprises upper and lower limit sensors arranged above and below the carrier plate for limiting upward and downward movement of the carrier plate.