Packaging apparatus

Abstract

Packaging apparatus in which units to be wrapped and flexible packaging material for wrapping the units are fed forward with the units spaced apart in the direction of feed, with a dwell interval between successive feed cycles, and having means for forming a seal across the width of the material between two successive units during each dwell interval. The units are fed forward by conveyor means intermittently driven via a chain and sprocket drive including a crank rotatable about a predetermined axis, means for continuously rotating the crank in one direction about its said axis, a first sprocket secured to the crank with the axis of the first sprocket offset from the crank axis for rotation of the first sprocket about the crank axis without rotation of said first sprocket about its own axis, a second sprocket and a chain trained around said first and second sprockets. The sealing means is operated during the dwell intervals by a similar chain and sprocket drive mechanism.

What is claimed is: 
     
       1. Packaging apparatus comprising means for feeding forward units to be wrapped and flexible packaging material for wrapping the units, with the units spaced apart in the direction of feed, means for effecting intermittent operation of the feeding means intermittently to feed forward the units and the packaging material, with a dwell interval between successive feed cycles, and means for forming a seal across the width of the material between two successive units during each dwell interval, wherein said means for operating the feeding means comprises a chain and sprocket drive including a crank rotatable about a predetermined axis, means for continuously rotating the crank in one direction about its said axis, a first sprocket secured to the crank with the axis of said first sprocket offset from the crank axis for rotation of said first sprocket about the crank axis without rotation of said first sprocket about its own axis, a second sprocket connected to said feeding means, a chain trained around said first and second sprockets, said first sprocket acting to pull a reach of the chain in a forward direction to effect rotation of the second sprocket in a forward direction for driving said feed means during a first portion of a revolution of said first sprocket about the crank axis, and to discontinue .[.froward.]. .Iadd.forward .Iaddend.drive of the chain during a second portion of said revolution for a feed and dwell of the feed means during each revolution of the crank, means for maintaining the chain relatively taut around said sprockets, and means driven in timed relation to said first sprocket for operating said seal forming means to form a seal as the first sprocket rotates through said second portion of a revolution. 
     
     
       2. Packaging apparatus as set forth in claim 1 wherein the means for forming a seal comprises at least one sealing member movable between an open and a closed position, and the means for operating said seal forming means comprises means for moving said sealing member from its open to its closed position to form a seal across the width of the material between two successive units during each dwell interval of said feeding means and then back to open position comprising a second chain and sprocket drive including a second crank rotatable about a predetermined axis, means for continuously rotating said second crank in one direction about its axis in timed relation with said first crank, a third sprocket secured to said second crank with the axis of said third sprocket offset from the axis of said second crank for rotation of said third sprocket about the axis of said second crank without rotation of the said third sprocket about its own axis, a fourth sprocket connected to said operating means, a second chain trained around said third and fourth sprockets, said third sprocket acting to pull a reach of said second chain in one direction to effect rotation of said fourth sprocket through a cycle for moving said sealing member from its open position to its closed position and then back to its open position, and means for maintaining said second chain relatively taut around said third and fourth sprockets. 
     
     
       3. Packaging apparatus as set forth in claim 2 wherein the means for forming a seal comprises a sealing bar and an anvil movable toward one another from an open position to a closed position engaging the material for forming a seal and then back to open position, said operating means operating said sealing bar and anvil from said fourth sprocket. 
     
     
       4. Packaging apparatus as set forth in claim 2 wherein said feeding means comprises conveyor means for intermittently feeding forward the units to be wrapped one after another in a generally horizontal path, said apparatus having means for supplying two webs of flexible heat-sealable plastic film one to underlie and the other to overlie the units as they are fed forward, said conveyor means being intermittently driven by the first sprocket via the first-mentioned chain and the second sprocket. 
     
     
       5. Packaging apparatus as set forth in claim 4 wherein said conveyor means comprises a main conveyor on the upstream side of said seal forming means and an outfeed conveyor on the downstream side of said seal forming means, both intermittently driven by said first sprocket via the first-mentioned chain and the second sprocket. 
     
     
       6. Packaging apparatus as set forth in claim 5 having an infeed conveyor for delivering units to the main conveyor, means for continuously driving the infeed conveyor, retractable infeed stop means for engagement by a unit being conveyed forward by said infeed conveyor to arrest it in a preliminary position as it comes onto the main conveyor, main retractable stop means for engagement by a unit being conveyed forward by said main conveyor to arrest it in another predetermined position upstream from the seal forming means, and means for retracting said infeed and main stop means in unison for feeding forward units received randomly or at spaced intervals on the infeed conveyor one at a time for being wrapped in timed relation to operation of said seal forming means. 
     
     
       7. Packaging apparatus as set forth in claim 5 having a sealing bar and an anvil movable in a vertical transverse plane between the exit end of the main conveyor and the entry end of the outfeed conveyor from an open retracted position wherein the bar and anvil are spaced for passage therebetween of a unit to a closed position engaging the film for forming a seal and then back to open position, said sealing bar and anvil being operated via said fourth sprocket in a cycle involving closing and opening of said bar and anvil on each revolution of said third sprocket about the axis of the second crank, and mean whereby, at the start of a cycle, one web of film extends downwardly and the other extends upwardly in a vertical transverse plane behind the plane of the bar and anvil with the ends of the webs heat-sealed together. 
     
     
       8. Apparatus as set forth in claim 2 wherein said first and second cranks are constituted by sprockets and are interconnected by a chain for rotation therein in unison with the said first and third sprockets out of phase for operation of the sealing member during the dwell between successive feed cycles. .Iadd. 9. Packaging apparatus comprising means for feeding forward units to be wrapped and flexible packaging material for wrapping the units, with the units spaced apart in the direction of feed, means for effecting intermittent operation of the feeding means intermittently to feed forward the units and the packaging material, with a dwell interval between successive feed cycles, and means for forming a seal across the width of the material between two successive units during each dwell interval, wherein said means for operating the feeding means comprises a chain and sprocket drive including a crank rotatable about a predetermined axis, means for rotating the crank in one direction about its said axis, a first sprocket secured to the crank with the axis of said first sprocket offset from the crank axis for rotation of said first sprocket about the crank axis without rotation of said first sprocket about its own axis, a second sprocket connected to said feeding means, a chain trained around said first and second sprockets, said first sprocket acting to pull a reach of the chain in a forward direction to effect rotation of the second sprocket in a forward direction for driving said feed means during a first portion of a revolution of said first sprocket about the crank axis, and to discontinue forward drive of the chain during a second portion of said revolution for a feed and dwell of the feed means during each revolution of the crank, means for maintaining the chain relatively taut around said sprockets, and means driven in timed relation to said first sprocket for operating said seal forming means to form a seal as the first sprocket rotates through said second portion of a revolution. .Iaddend.