L-type heat sealing device with uniform sealing pressure

Abstract

A heat sealing device includes a frame rotatably supporting gears and comprising four fixed upright guide rods. Upper and lower members, in the form of U-shape, are movable along the guide rods between engaging position and separated position. The upper and lower members each have four racks respectively engaging the gears whereby the upper and lower members are movable synchronously. A power cylinder has a rod mounted to the upper member for driving the upper and lower members toward/away from each other. Heating elements are mounted to the upper and lower members and are substantially opposite to each other. The upper and lower members are maintained substantially parallel to each other during the movement thereof whereby a uniform sealing pressure is applied to the heating elements of the upper and lower members to achieve high quality sealing results.

What is claimed is:  
     
         1 . A heat sealing device comprising: 
 a frame;    upper and lower members movably supported by the frame, the upper and lower members each comprising a heating device substantially opposite to and engageable with each other for performing a heat sealing operation on a package film;    a transmission system comprising a gear rotatably mounted to the frame and racks mounted to the upper and lower members and engaging the gear whereby the upper and lower members are movable in synchronization with each other; and    a driving device coupled to one of the upper and lower members to move the upper and lower members with respect to each and thus bringing the heating devices of the upper and lower members to engage each other.    
     
     
         2 . The heat sealing device as claimed in  claim 1  further comprising guide rods fixed to the frame for guiding the movement of the upper and lower members.  
     
     
         3 . The heat sealing device as claimed in  claim 2 , wherein the upper and lower members comprise bearing means slidable along the guide rods for guiding the movement of the upper and lower members.  
     
     
         4 . The heat sealing device as claimed in  claim 2 , wherein the frame comprises a bottom board from which the guide rods extend.  
     
     
         5 . The heat sealing device as claimed in  claim 1 , wherein the frame comprises a support plate to which the gear is rotatably mounted.  
     
     
         6 . The heat sealing device as claimed in  claim 1 , wherein the upper and lower members each comprise a U-shaped frame having lateral segments connected by an end segment, the U-shaped frames being substantially opposite to each other and maintained parallel to each other, the sealing device comprising sections mounted to one of the lateral segments and the end segment of U-shaped frame of the upper and lower members.  
     
     
         7 . The heat sealing device as claimed in  claim 1 , wherein the driving device comprises a power element coupled to the upper member for moving the upper and lower members.  
     
     
         8 . The heat sealing device as claimed in  claim 7 , wherein the power element comprises a power cylinder having a rod connected to the upper member.  
     
     
         9 . The heat sealing device as claimed in  claim 6 , wherein the driving device comprises a power cylinder having a rod, an end member being attached to the rod, the end member straddling between and fixed to the lateral segments of the upper member.