Wrapping machine

Abstract

A method and an apparatus ( 10 ) for wrapping a bundle on 5 of the 6 faces thereof comprises gripping fingers ( 44 ) for holding a sheath (S) from opposed lateral sides of the bundle while folding members ( 62, 64 ) pivot into the sheath to tuck in inner creases along the sides of the bundle also thereby forming two-ply outer creases. The two-ply outer creases are brought down against the inner creases by the gripping fingers ( 44 ) and a sealing unit ( 40 ) is presses against the sides of the bundle to seal the so formed three-ply folds.

1 . A method for wrapping a bundle into a sheath, the method comprising:
 drawing the sheath in front of the bundle, holding the sheath against a front face of the bundle, drawing the sheath over a top surface of the bundle while the sheath is being held at the front of the bundle, creating a three-ply fold in the sheath on each opposed lateral sides of a front end portion of the bundle, fastening the three-ply folds in place, drawing the sheath over a rear face of the bundle, holding the sheath against the rear face of the bundle, creating a three-ply fold in the sheath on each opposed lateral sides of a rear end portion of the bundle, and fastening the three-ply folds in place.   
     
     
         2 . The method defined in  claim 1 , wherein the fastening steps comprise placing an anvil member between the sheath and the bundle and pressing the three-ply folds between the anvil member and a heat sealing member. 
     
     
         3 . The method defined in  claim 1 , wherein creating a three-ply fold comprises moving a folding member on one side of the bundle into a laterally held portion of the sheath, the engagement of the folding member in the sheath forming a fold in the sheath, the fold defining an inner crease lying against an underlying side surface of the bundle and a two-ply outer crease in a remaining portion of the laterally held portion of the sheath, and drawing the two-ply outer crease over the inner crease, thereby forming a three-ply fold. 
     
     
         4 . The method defined in  claim 1 , wherein creating a three-ply fold comprises holding a side portion of the sheath so as to create a foldable flap extending laterally outwardly from one end of the bundle, moving a folding member in the foldable flap to tuck in a first portion of the flap against one side of the bundle, thereby forming an inner crease, and pulling a remaining portion of the foldable flap over the first portion of the sheath. 
     
     
         5 . The method defined in  claim 3 , wherein the folding member has a stem and a freely articulated arm pivotally mounted to a distal end potion of the stem, the freely articulated arm having a lever portion extending beyond the stem portion, and wherein continued advancement of the folding member in the laterally held portion of the sheath causes the articulated member to pivot relative to the stem under the force transmitted from the sheath to the lever portion of the articulated arm, thereby creating a fold line in the sheath. 
     
     
         6 . The method defined in  claim 4 , wherein holding a side portion of the sheath comprises moving a pair of gripping fingers along a ramp having a 45 degrees inclination to an elevation corresponding generally to a top surface of the bundle, and then gripping the sheath with the gripping fingers. 
     
     
         7 . The method defined in  claim 6 , wherein pulling a remaining portion of the foldable flap over the first portion of the sheath comprises moving the gripping fingers down the ramp and pivoting the gripping fingers from a horizontal orientation to a vertical orientation. 
     
     
         8 . A method of bagging a bundle into a sheath having a bottom open face comprising covering the bundle with the sheath, creating a pleat at each corner of the sheath, each pleat being made by doubling the sheath over on itself to form a section of three thicknesses including an inner crease along a side of the bundle and a two-ply outer crease having two superposed sheath layers, and for each pleat, joining the two-ply outer crease to the inner crease. 
     
     
         9 . The method defined in  claim 8 , wherein creating a pleat comprises moving a folding member on each side of the bundle into a laterally held portion of the sheath, the engagement of the folding member in the sheath forming a fold in the sheath, the fold defining the inner crease and the two-ply outer crease, and drawing the two-ply outer crease over the inner crease. 
     
     
         10 . The method defined in  claim 9 , wherein the laterally held portion of the sheath is held by a pair of gripping fingers movable along a ramp having a 45 degrees inclination. 
     
     
         11 . The method defined in  claim 10 , wherein drawing the two-ply outer crease over the inner crease comprises moving the gripping fingers down the ramp and pivoting the gripping fingers from a horizontal orientation to a vertical orientation. 
     
     
         12 . An apparatus for wrapping a bundle, comprising a conveyor for carrying the bundle through the apparatus, a sheath dispensing unit for covering a top surface and the lateral sides of the bundle with a sheath, first and second pairs of gripping fingers for holding the sheath from opposed lateral sides of the bundle, folding members disposed on opposed lateral side of the conveyor to tuck in the sheath along the sides of the bundle at each end of the bundle while the sheath is held by said gripping fingers, thereby forming pleats at each corner of the sheath, each pleat comprising an inner crease lying against an underlying side surface of the bundle and a two-ply outer crease held by the gripping members, the first and second pairs of gripping members being movable to draw the two-ply outer creases over corresponding inner creases, and a joining unit engageable with the sheath to join the two-ply outer crease to the underlying inner crease at each pleat. 
     
     
         13 . The apparatus defined in  claim 12 , wherein the sheath dispensing unit comprises an overhead supply reel mounted on a carrier axially displaceable back and forth relative to a feeding direction of the conveyor, and indexing rollers mounted to a support which is in turn mounted to the carrier for up and down movement with respect thereto. 
     
     
         14 . The apparatus defined in  claim 12 , wherein the joining unit comprises first and second heat sealing members facing each other from opposed sides of the conveyor, the sealing members being movable towards and away from each other along an axis transversal to the conveyor. 
     
     
         15 . The apparatus defined in  claim 12 , wherein the first and second pairs of gripping members are reciprocable along respective ramps, the ramps being oriented transversally to the conveyor and having an inclination of about 45 degrees. 
     
     
         16 . The apparatus defined in  claim 13 , wherein the first and second pairs of gripping members are reciprocable along respective ramps, the ramps being oriented transversally to the conveyor and having an inclination of about 45 degrees when the gripping fingers are displaced to a sheath grabbing position, and wherein the ramps are pivotable to a collapsed position to clear the passage of the indexing rollers. 
     
     
         17 . The apparatus defined in  claim 12 , wherein each pair of gripping fingers is pivotable from a horizontally extending position to a vertically extending position. 
     
     
         18 . The apparatus defined in  claim 14 , further comprising a pair of anvil members mounted on opposed sides of the conveyor, the anvil members being displaceable between a collapsed position to an upstanding position in which the anvil members lie vertically between the sheath and an adjacent surface of the bundle in alignment with the first and second heat sealing members, the anvil members offering substantially uniform bearing surfaces against which the first and second heat sealing members can be pressed during the sealing operation. 
     
     
         19 . The apparatus defined in  claim 13 , further comprising front and rear heel members pivotable between a collapsed position for clearing the passage of the bundle on the conveyor and a raised position for respectively retaining the sheath against the front and rear faces of the bundle while the carrier is displaced relative to the bundle. 
     
     
         20 . The apparatus defined in  claim 12 , wherein the folding members are pivotable about an axis generally transversal to the conveyor for movement between an idle position in which the folding members lie in a generally horizontal plane and an upstanding position for tucking in the sheath along the sides of the bundle. 
     
     
         21 . The apparatus defined in  claim 12 , wherein each of the folding members has a stem and a freely articulated arm pivotally mounted to a distal end portion of the stem, the articulated arm and the stem are partially longitudinally offset, the articulated arm having an end portion extending beyond the distal end portion of the stem to provide a lever for automatically causing the arm to pivot relative to the stem when a force is applied on the lever.