Apparatus for joining overlapped side edges of plastic film sheet formed into elongate tube

Abstract

A joining apparatus and methods wherein, after plastic film is formed into a variable size tube for receiving therein and enveloping corresponding variable size large articles such as bales of cotton, trash, cloth, etc., the joining apparatus joins an overlap region of the plastic film tube for effectively sealing and creating the plastic film tube. The joining apparatus includes an inner shoe located inside the formed tube. The overlap region slides over the inside shoe as the tube is formed. An outside shoe is moveable between an idle position away from and an operative position adjacent to the inside shoe. When in its operative position, the overlap region is sandwiched between the outside and inside shoes and heated air is provided under pressure through a groove on the outside shoe and onto the overlap region for effectively heating and joining the overlapped plastic sheets.

What is claimed is: 
     
         1 . In an apparatus for forming elongate film into a tube around articles, the forming apparatus including: a conveying surface adapted to carry the articles being wrapped; a forming collar adapted to wrap film around the articles carried on said conveying surface, said forming collar including left and right sections, said left section located adjacent a left side of said conveying surface and said right section located adjacent a right side of said conveying surface; wherein said left and right forming collar sections each include an inside surface, an outside surface and a leading edge; wherein elongate film having a central area and left and right sides is formed into a tube by directing: the central film area onto said conveying surface; the left film side along said forming collar left section outside surface, around its leading edge and along its inside surface; and, the right film side along said forming collar right section outside surface, around its leading edge and along its inside surface; wherein the formed tube includes an elongate overlap region whereat the left film side is arranged adjacent to and overlapping the right film side, the elongate overlap region extending longitudinally along the formed tube with one of the left or right film sides being on the inside of the formed tube and the other of the left or right film sides being on the outside of the formed tube;
 an apparatus for joining the left and right film sides to one another at said overlap region, said joining apparatus comprising:   an outside shoe adapted to be located outside the formed tube adjacent the overlap region and an inside shoe adapted to be located inside the formed tube adjacent the overlap region, whereby the overlap region may be sandwiched between said outside and inside shoes; and,   wherein hot air is selectively directed to the overlap region and whereby the first and second plastic film sheets are heated and joined to one another.   
     
     
         2 . The apparatus of  claim 1  wherein said outside shoe includes a face adapted to slidingly engage the plastic film overlap region and an air delivery groove extending into said outside shoe from a delivery groove opening in said face, wherein said hot air is selectively provided under pressure into said groove and exits through said air delivery opening whereby said hot air is directed onto said plastic film overlap region. 
     
     
         3 . The apparatus of  claim 2  wherein said groove is elongate and extends in the longitudinal direction of the formed tube, said elongate groove having an ingress end closest to said forming collar and an egress end opposite said ingress end. 
     
     
         4 . The apparatus of  claim 3  wherein said inside shoe includes an inside shoe face adapted to slidingly engage the plastic film overlap region and an inside groove extending into the inside shoe from said inside face, wherein said inside groove is elongate and extends in the longitudinal direction of the formed tube, said inside elongate groove having an ingress end closest to said forming collar and an egress end opposite said ingress end, and wherein said inside groove is adapted to be located adjacent to and facing said outside shoe groove with the plastic film overlap region therebetween. 
     
     
         5 . The apparatus of  claim 4  further comprising:
 an outside roller located adjacent said outer shoe groove egress end and having an outside bearing surface; 
 an inside roller located adjacent said inner shoe groove egress end and having an inside bearing surface; and, 
 wherein said outside bearing surface is adapted to be located adjacent to and facing said inside bearing surface with the plastic film overlap region therebetween. 
 
     
     
         6 . The apparatus of  claim 5  wherein said outside roller bearing surface is comprised of silicone rubber. 
     
     
         7 . The apparatus of  claim 5  wherein said outside shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         8 . The apparatus of  claim 7  further comprising a guiding post mounted to said outside shoe and slidingly engaging a supporting mount, whereby said outside shoe is guided between its operative and idle positions. 
     
     
         9 . The apparatus of  claim 8  further comprising a pneumatic cylinder connected between said outside shoe and said supporting mount and selectively energized for moving said outside shoe between said operative and said idle positions. 
     
     
         10 . The apparatus of  claim 5  further comprising an ingress roller located adjacent said outer shoe groove ingress end and having an outside bearing surface and wherein said ingress roller outside bearing surface is adapted to be located adjacent to and facing said inside shoe face with the plastic film overlap region therebetween. 
     
     
         11 . The apparatus of  claim 5  further comprising a manifold located within said air delivery groove and having a plurality of hot air distribution holes, said hot air adapted to travel through and be distributed by said manifold along said air delivery groove. 
     
     
         12 . The apparatus of  claim 5  wherein said left and right forming collar sections and said outside and inside shoes are supported on a movable carrier and said carrier is movable relative to said carrying surface. 
     
     
         13 . The apparatus of  claim 1  further comprising:
 an outside roller located adjacent said outer shoe and having an outside bearing surface; 
 an inside roller located adjacent said inner shoe and having an inside bearing surface; and, 
 wherein said outside bearing surface is adapted to be located adjacent to and facing said inside bearing surface with the plastic film overlap region therebetween. 
 
     
     
         14 . The apparatus of  claim 13  wherein said outside roller bearing surface is comprised of silicone rubber. 
     
     
         15 . The apparatus of  claim 13  wherein said outside shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         16 . The apparatus of  claim 15  wherein said left and right forming collar sections and said outside and inside shoes are supported on a movable carrier and said carrier is movable relative to said carrying surface. 
     
     
         17 . The apparatus of  claim 1  wherein said outside shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         18 . The apparatus of  claim 17  wherein said left and right forming collar sections and said outside and inside shoes are supported on a movable carrier and said carrier is movable relative to said carrying surface. 
     
     
         19 . The apparatus of  claim 1  wherein said left and right forming collar sections and said outside and inside shoes are supported on a movable carrier and said carrier is movable relative to said carrying surface. 
     
     
         20 . The apparatus of  claim 2  further comprising a manifold located within said air delivery groove and having a plurality of hot air distribution holes, said hot air adapted to travel through and be distributed by said manifold along said air delivery groove. 
     
     
         21 . In an apparatus for forming elongate film having a central area and left and right sides into an elongate tube and wherein the formed tube includes an elongate overlap region whereat the left film side is arranged adjacent to and overlapping the right film side, the elongate overlap region extending longitudinally along the formed tube with one of the left or right film sides being on the inside of the formed tube and the other of the left or right film sides being on the outside of the formed tube;
 an apparatus for joining the left and right film sides to one another at said overlap region, said joining apparatus comprising:   an outside shoe adapted to be located outside the formed tube adjacent the overlap region and an inside shoe adapted to be located inside the formed tube adjacent the overlap region, whereby the overlap region may be sandwiched between said outside and inside shoes; and,   wherein hot air is selectively directed to the overlap region and whereby the first and second plastic film sheets are heated and joined to one another.   
     
     
         22 . The apparatus of  claim 21  wherein said outside shoe includes a face adapted to slidingly engage the plastic film overlap region and an air delivery groove extending into said outside shoe from a delivery groove opening in said face, wherein said hot air is selectively provided under pressure into said groove and exits through said air delivery opening whereby said hot air is directed onto said plastic film overlap region. 
     
     
         23 . The apparatus of  claim 22  wherein said inside shoe includes an inside shoe face adapted to slidingly engage the plastic film overlap region and an inside groove extending into the inside shoe from said inside face, and wherein said inside groove is adapted to be located adjacent to and facing said outside shoe groove with the plastic film overlap region therebetween. 
     
     
         24 . The apparatus of  claim 23  wherein said outside shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         25 . The apparatus of  claim 23  further comprising:
 an outside roller located adjacent said outer shoe and having an outside bearing surface; 
 an inside roller located adjacent said inner shoe and having an inside bearing surface; and, 
 wherein said outside bearing surface is adapted to be located adjacent to and facing said inside bearing surface with the plastic film overlap region therebetween. 
 
     
     
         26 . The apparatus of  claim 22  further comprising a manifold located within said air delivery groove and having a plurality of hot air distribution holes, said hot air adapted to travel through and be distributed by said manifold along said air delivery groove. 
     
     
         27 . The apparatus of  claim 21  wherein said outside shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         28 . The apparatus of  claim 21  further comprising:
 an outside roller located adjacent said outer shoe and having an outside bearing surface; 
 an inside roller located adjacent said inner shoe and having an inside bearing surface; and, 
 wherein said outside bearing surface is adapted to be located adjacent to and facing said inside bearing surface with the plastic film overlap region therebetween. 
 
     
     
         29 . An apparatus for joining a first plastic film sheet and a second plastic film sheet to one another, the plastic film sheets being arranged adjacent to and overlapping one another at an overlap region, said apparatus comprising:
 a first shoe adapted to be located adjacent the first plastic film sheet at the overlap region and a second shoe adapted to be located adjacent to the second plastic film sheet at the overlap region, whereby the overlap region is sandwiched between said first and second shoes; and,   wherein hot air is directed to said overlap region and whereby the first and second plastic film sheets are joined to one another.   
     
     
         30 . The apparatus of  claim 29  wherein said first shoe includes a face adapted to slidingly engage the plastic film overlap region and an air delivery groove extending into said first shoe from a delivery groove opening in said face, wherein said hot air is selectively provided under pressure into said groove and exits through said air delivery opening whereby said hot air is directed onto said plastic film overlap region. 
     
     
         31 . The apparatus of  claim 30  wherein said second shoe includes a second shoe face adapted to slidingly engage the plastic film overlap region and a second groove extending into the second shoe from said second face, and wherein said second groove is adapted to be located adjacent to and facing said first shoe groove with the plastic film overlap region therebetween. 
     
     
         32 . The apparatus of  claim 31  wherein said first shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         33 . The apparatus of  claim 31  further comprising:
 a first roller located adjacent said first shoe and having a first bearing surface; 
 a second roller located adjacent said second shoe and having a second bearing surface; and, 
 wherein said first bearing surface is adapted to be located adjacent to and facing said second bearing surface with the plastic film overlap region therebetween. 
 
     
     
         34 . The apparatus of  claim 30  further comprising a manifold located within said air delivery groove and having a plurality of hot air distribution holes, said hot air adapted to travel through and be distributed by said manifold along said air delivery groove. 
     
     
         35 . The apparatus of  claim 29  wherein said outside shoe is selectively moveable between an operative position adjacent the plastic film overlap region and an idle position away from said plastic film overlap region. 
     
     
         36 . The apparatus of  claim 29  further comprising:
 a first roller located adjacent said first shoe and having an first bearing surface; 
 a second roller located adjacent said second shoe and having an second bearing surface; and, 
 wherein said first bearing surface is adapted to be located adjacent to and facing said second bearing surface with the plastic film overlap region therebetween.