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.

Description

BACKGROUND OF THE INVENTION

This invention relates to packaging apparatus, and more particularly to apparatus for wrapping products in heat-shrinkable film for subsequent shrinking in a shrink tunnel.

The invention is especially concerned with apparatus of a type heretofore sold by the assignee of this application known as a "sleeve wrapper," in which a unit to be wrapped is fed forward by a conveyor against a vertical reach of film comprising a first web issuing from an upper roll and extending downwardly and a second web issuing from a lower roll and extending upwardly with the ends of the two webs heat-sealed together. As the unit moves forward, the upper web is draped over the unit and the lower web is draped under it. The unit then dwells in place while a pair of seal bars are closed behind the unit to heat-seal the two webs together on the trailing side of the unit and to sever the webs through the seal so as to provide a trailing seal for the film draped around the unit to form a sleeve, and a seal constituting the leading seal for the next sealing operation. After the sealing operation, the bars are opened and the enwrapped unit is fed forward away from the webs and another unit fed forward for being wrapped.

In the assignee's prior sleeve wrapping apparatus, the conveyor (and seal bars) have been intermittently operated in sealing cycles via start-and-stop electric motor operation under control of a photoelectric cell and this has tended to cause problems when attempting to wrap units of low stability, at commercially necessary speeds, the acceleration and deceleration characteristics of this type of operation being such as to tend to cause units of low stability to tip over and/or to become disoriented on starting and stopping the conveyor.

SUMMARY OF THE INVENTION

Accordingly, among the several objects of the invention may be noted the provision of an improved wrapping apparatus of the class described wherein the starting and stopping of the conveyor is so smooth as to enable handling of units of relatively low stability (e.g., filled bags) without the units tipping over or becoming disoriented while wrapping the units at commercially necessary speeds (e.g., up to 30-40 cycles per minute); the provision of such apparatus having means for correlating the operation of the conveyor and the seal bars with acceleration and deceleration characteristics such as provide smooth operation; the provision of such apparatus having continuously operating means for this purpose, as distinguished from on-off operation; and the provision of such apparatus which has increased life, lower maintenance and more reliable operation (on account of smooth operation).

In general, packaging apparatus of this invention comprises 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. The 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 sprockets about the crank axis without rotation of said first sprocket about its own axis, a second sprocket, a chain trained around said first and second srockets, 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 portion of a revolution of said first sprocket about the crank axis, and to discontinue forward drive of the chain during another portion of said revolution for a feed and dwell of the feed means during each revolution of the crank, and means for maintaining the chain relatively taut around said sprockets.

Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a packaging apparatus embodying this invention;

FIG. 2 is a semidiagrammatic view illustrating certain conveyors and drives of the apparatus;

FIGS. 2A and 2B are views based on FIG. 2 and showing moved positions of the units;

FIG. 3 is a view taken generally on line 3--3 of FIG. 2, on a much larger scale than FIG. 2, illustrating certain drive components of the apparatus;

FIG. 4 is a plan of an infeed and main conveyor of the apparatus;

FIG. 5 is a side elevation of FIG. 4;

FIG. 6 is an end elevation of FIG. 5 as viewed from the right of FIGS. 4 and 5;

FIG. 7 is a plan of certain drive components;

FIG. 8 is a side elevation of FIG. 7;

FIG. 9 is a longitudinal vertical section on line 9--9 of FIG. 1 showing the sealing means of the apparatus;

FIG. 10 is a partial transverse section on line 10--10 of FIG. 9 showing the sealing means;

FIG. 11 (sheet 1) on or crank 171. Sprocket 175 does not rotate on its own axis B2. A chain 177 is trained around sprocket 175 and a sprocket 179 (which may be referred to as the fourth sprocket) on a countershaft 181. Means indicated generally at 183 is provided for maintaining chain 177 generally taut around the sprockets 175 and 179. The driving sprocket 175 acts to pull a reach 177a of the chain 177 in a predetermined direction to effect rotation of the driven sprocket 179 and countershaft 181 (sprocket 179 being keyed thereto) and countershaft 181 has chain and sprocket drives 185 the chains of which are trained around sprockets 187 on crankshafts 145 to operate (close and open) the anvil and seal bar 115 and 131 during a portion of the revolution of the driving sprocket 175 about axis B1, and to discontinue the drive of the chain 177 during another portion of the said revolution for a dwell of the anvil and seal bars in their open position.

The length of the chain 19 of the drive 9 corresponds generally to the length of chain wrap needed for the condition when the axis A2 of the sprocket 15 is in dead-center position (not shown) in line with axis A1 and the axis of shaft 91 and on the side of axis A1 away from shaft 91 (referred to as the long dead-center position). As sprocket 15 rotates around with crank 11 (clockwise as viewed in FIGS. 2 and 8) from this dead-center position to its opposite dead-center position (referred to as its short dead-center position) the length of wrap decreases, and means 21 takes up the slack of the chain to maintain it taut. As shown, means 21 comprises a slack take-up sprocket 189 on a take-up arm 191 pivoted at 193 on part of frame 195 of the apparatus and biased by a coil tension spring 197 to pull the chain taut. Similarly, the length of chain 177 corresponds generally to the length of chain wrap needed for the condition when the axis B2 of sprocket 175 is in its long dead-center position in line with axis B1 and the axis of countershaft 181 and on the side of axis B1 away from the countershaft. As sprocket 175 rotates around with crank 171 (clockwise as viewed in FIGS. 2 and 8) from this dead-center position to its opposite or short dead-center position, the length of wrap decreases, and means 183 takes up the slack of the chain 177 to maintain it taut. As shown, means 183 comprises a slack take-up sprocket 199 on a take-up arm 210 pivoted at 203 on frame 195 and biased by a coil tension spring 205 to pull the chain taut.

The countershaft 181 has a double sprocket cluster 207 idling thereon. This is driven by a chain and sprocket drive 209 from shaft 173 and drives cam shaft 77 via the chain and sprocket drive 81.

It will be noted that the pitch circles of sprockets 15 and 175 are coincident with axes A1 and B1, respectively. This provides for dwell time of the conveyor 25 and sealing means 7 when the sprockets are in the positions shown in FIG. 8 (i.e., when the sprockets are half way between their short and long dead-center positions, or more particularly when a line passing through the axes A1 and A2 or through axes B1 and B2 is perpendicular to a respective line through A1 and shaft 91 and B1 and shaft 181).

In operation, with motor 159 running continuously, sprocket 11 is driven continuously. It drives sprocket 171 continuously via the chain drive 169. Sprocket 171 drives sprocket cluster 207 continuously via drive 209. Cluster 207 drives shaft 77 continuously via drive 81. Shaft 77 drives the infeed conveyor 43 continuously via drive 57. With shaft 77 operating continuously cams 75L and 75R act via levers 73L and 73R to swing stops 61L and 61R between their vertical stop positions and their outwardly angled retracted positions shown in solid lines and in phantom in FIG. 6 to release a unit for being wrapped.

Crank 11 rotates continuously (clockwise as viewed in FIGS. 2 and 8) around its axis A1 and effects rotation of the stated first sprocket 15 around axis A1 without rotation of sprocket 15 around its own axis A2. As sprocket 15 rotates from it position shown in FIG. 2, it pulls reach 19a of the chain 19 to drive the second sprocket 17 in forward direction (clockwise as viewed in FIG. 2) to drive the outfeed conveyor in forward direction. This effects driving in forward direction of the main conveyor 1 via the conveyor interconnecting drive 95. As sprocket 15 rotates around back to its position shown in FIG. 2, the conveyor is gradually decelerated to a stop, the chain 19 being maintained taut by the slack take-up sprocket 189 (see FIG. 8).

Thus, the conveyors 1 and 85 dwell when sprocket 15 is in its FIG. 2 position; hence this position is referred to as a dwell position.

Sprocket 171 rotates continuously (clockwise as viewed in FIGS. 2 and 8) around its axis B1 in unison with crank 11 and effects rotation of the third sprocket 175 around axis B1 without rotation of sprocket 174 around its own axis B2. As sprocket 171 rotates around from its position shown in FIG. 2, it pulls reach 177a of chain 177 to drive the fourth sprocket 179 and countershaft 181 in forward direction (clockwise as viewed in FIGS. 2 and 9). It will be noted that with sprocket 175 in its position as shown in FIG. 2, the seal bar 131 and anvil 115 are closed and momentarily remain closed for a time sufficient to complete the seal, this momentary dwell resulting from operation of the above-mentioned overtravel linkage. Countershaft 181, via drive 185, drives crank shaft 145 through a revolution in clockwise direction as viewed in FIG. 9, and this effects closing and opening of the seal bar 131 and anvil 115. The drives 5 and 157 are so phased relative to one another that the closing movement of the seal bar and anvil starts somewhat before the stopping of conveyors 1 and 85 and is completed during the dwell of the conveyors with both the conveyors and the seal bar and anvil dwelling simultaneously for a short period of time with their respective sprockets 15 and 175 at their dwell and momentary dwell positions, respectively. Then the opening movement of the seal bar and anvil starts during the dwell of the conveyors 1 and 85 and is completed somewhat after the start of the conveyors. It will be understood that the seal bar and anvil are well clear of the suit U when movement of conveyors 1 and 85 is initiated to convey a unit past films F1 and F2 for having the film wrapped therearound. It will be further understood that during certain portions of each cycle, both the conveyors and the anvil and heat-seal bar move simultaneously, and that the heat-seal bars remain stationary in their retracted or clear position during only a portion of each packaging cycle (this portion of the cycle corresponding to the time when units U are conveyed forward by the conveyors for having the film wrapped therearound). It will also be noted that the above-mentioned over-travel linkages (including rods 156 and springs 158) interconnecting bar 111 with cranks 149 and 153 allow the seal bar and the anvil to come together in sealing relation with the film and remain in sealing contact with the film for heat-sealing and severing of the film during continued rotation of the crank.

Following the progress of a unit U through the apparatus, the unit U is first placed on the infeed conveyor 43 (which runs continuously) and is fed forward thereby against the infeed stops 59L and 59R. It is arrested by these stops in the position indicated at P1 in FIG. 2 for an interval until they open and allow the unit to pass onto the main conveyor 1. This initial infeed and arrest provide an initial positioning of the unit at P1 for its travel through the apparatus. When the stops 59L and 59R open, the main conveyor 1 is running and feeds the unit forward. As it is fed forward by the main conveyor, stops 59L and 59R close to arrest the next unit at P1 and the main stops 61L and 61R (which operate in unison with stops 59L and 59R) also close to arrest the unit at position P2 shown in FIG. 2, for a final positioning of the unit relative to the seal forming means 7 for subsequent travel of the unit through means 7. The main conveyor comes to a stop shortly after the unit engages the stops 61L and 61R and is arrested at P2. The main stops 61L and 61R then open, and the main conveyor 1 starts running, feeding the unit U forward to a position P3 somewhat upstream from the sealing means 7 and stops. The stops, being spring-biased closed, are adapted to engage the sides of a unit and remain in engagement with the sides of a unit until the unit has cleared the stops, whereupon they may close to arrest the next unit regardless of the spacing between successive units.

After a unit U has reached position P3, on the next operation of the main conveyor 1, the unit is fed forward from position P3 to position P4 on the outfeed conveyor 85. As shown in FIG. 2A, in travelling from position P3 to position P4, the unit engages the vertical reach R of film which extends vertically in the space 93 between the exit end of conveyor 1 and the entry end of conveyor 85, and which is constituted by a downwardly extending end portion of film F1 and an upwardly extending end portion of film F2, the ends of these two films being joined at a heat seal such as indicated at S1 as a result of the previous sealing operation. The unit U, moving forward to position P4, pushes the film forward as shown in FIG. 2B, as a result of which the upper web F1 becomes draped over the unit and the lower web F2 becomes draped under the unit (see FIG. 2). The seal bar assemblies 107 and 109 then close on the webs behind the unit U as shown in FIG. 2 and effect heat-sealing together of the two webs and severing of the webs through the seal so as to provide a trailing seal S2 for the film draped around the unit and a seal S1 constituting the leading seal for the next sealing operation. The seal bar and anvil close to form the seals when the units and film are at a dead stop, and this is highly advantageous for forming good seals in that there is no stress on the seals as they are formed.

The seal bar and anvil then open, and conveyors 1 and 85 start up and operate through another cycle. Conveyor 85 feeds the enwrapped unit U from position P4 on to the roller conveyor 97, which may deliver it to a shrink tunnel (not shown). Conveyor 1 brings another unit through from P3 to P4 to be enwrapped and sealed.

FIG. 12 diagrammatically illustrates the kinematics of the apparatus, the horizontal lines therein indicating the acceleration and deceleration of the anvil 115 and the seal bar 131, and the vertical lines therein indicating the acceleration and deceleration of the intermittently operating conveyors 1 and 85. Line A depicts the action of the anvil 115 and line B depicts the action of the seal bar 131 in one cycle of operation, as related to the unit depicted at U. The interval of time in which the film is sealed (to form seals S2 and S1) is indicated at C. The acceleration and deceleration characteristics of the conveyors 1 and 85 are such that the starting and stopping of the conveyors occurs in a very smooth manner, making it possible to handle products of low stability (e.g., filled bags standing upright) without disorientation (e.g., without tipping over) at practical speeds, and at the same time making for longer like like, low maintenance requirements, and reliability.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

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 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.

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.

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.