Packaging machine

0001This invention relates to packaging and more particularly to a method and apparatus for forming packages using pre-formed side connected bags.

0002US-A-5,743,070 (the S P Patent) entitled PACKAGING MACHINE, MATERIAL and METHOD discloses a machine for use in packaging which has been highly successful commercially. The S P Patent and patents which resulted from divisional applications claim a machine and a plastic web used by that machine as well as a process of making packages.

0003With the machine of the S P Patent the web is fed first through a slitter which splits a top portion into two lips that are respectively grasped between associated pairs of belts for transport through a load section. The belts which transport the web through the load section are more fully described in US-A-5,722,218 entitled Plastic Transport System, herein (the Load Belt Patent).

0004As the web is fed to the load section, the lips are spread to effect the sequential opening of the side connected bags, each into a rectangular opening for receiving a product to be packaged. The lips are then returned to juxtaposed relationship and trimmed as the lips are grasped by further belts in a sealer section. The further belts are preferably belts of the type described and claimed in US-A-6,170,238 entitled Sealing Machine and Method, herein (the Sealer Belt Patent).

0005While the machine of the referenced patents has proved highly successful it is relatively difficult to clean and not suitably constructed for use in packaging food products. Accordingly, it would be desirable to provide an improved machine of the SP Patent constructed to facilitate cleaning and to be adaptable for food packaging.

0006According to the present invention, there is provided a packaging machine for forming packages from a chain of side connected bags comprising: <ul id="ul0001" list-style="none" compact="compact"><li>a. a frame for supporting loading and closure sections above a surface and adjacent an operator station;</li><li>b. a package loading section pivotally connected to the frame;</li><li>c. at least the loading section including mechanism for transporting such a chain to and through a load station defined by the loading section, the mechanism including apparatus to open bags of the chain sequentially and to close such bags after they have been loaded at the load station; and the machine being characterised by:</li><li>d. at least the loading section (14) being movable when in use from a generally horizontal operating position to a front elevated position to provide operator access to an underside of the loading section.</li></ul>

0007The preferred embodiment of the closure section of the machine includes a heat sealer in which the source of heat for sealing is a resistence electrical heater. In order to enable washdown, such as with a pressure hose, the sealer heat source is readily removable from the balance of the sealer. Once the heat source is removed from the balance of the closure section, it can be stored in a cabinet mounted on the back of the machine. The cabinet, once an access door is closed, is hermetically sealed so that the heater element when stored in the cabinet is protected from damage by cleaning fluid flowed against the machine.

0008For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- <ul id="ul0002" list-style="none"><li>Fig. 1 is a foreshortened side elevational view of a packaging machine;</li><li>Fig. 2 is a top plan view of the machine foreshortened am amount corresponding to the foreshortening in Figure 1.</li><li>Fig. 3 is an end elevational view of the machine with the load and closure sections in their operating positions;</li><li>Fig. 4 is an end elevational view of the machine in which the load and closure sections have been moved to their cleaning positions;</li><li>Fig. 5 is a plan view of the closure section on a scale enlarged with respect to Figures 1 and 2;</li><li>Fig. 6 is a front elevational view of the closure section on the scale of Figure 5;</li><li>Fig. 7 is a sectional view of the closure section on an enlarged scale with respect to Figures 5 and 6 and as seen from a plane indicated by the line 7-7 of Figure 5;</li><li>Fig. 8 is a sectional view corresponding to Figure 7 showing the removable heater element assembly in a partially removed state; and</li><li>Fig. 9 is a view of the heater sub-assembly as it is removed from the balance of the closure section, all as seen from the same plane as Figures 7 and 8 and on the same scale.</li></ul>

0009Referring now to the drawings and to Figures 1 through 4 in particular, a packaging machine is shown generally at 10. The machine 10 includes a supporting frame 12 upon which load and closure sections 14,15 are mounted. A web supply platform 16 is provided at the back of the machine. The platform 16 is located to the right, as viewed in Figure 1, under an entrance end 18 of the load section.

0010When the machine is in use a supply in the form of a web or chain of side connect bags is positioned on the platform. The web is described fully in the SP Patent. The web is fed around web guides 20 to the entrance end 18 of the load section 14. The load section is as described in the referenced SP Patent with the exception of a redesigned burster 22 which now is driven by a stepper motor 24. Operation of the load section is also as described in the S P Patent while transport of the web through the load section is accomplished with belts as described and claimed in the Load Belt Patents.

0011One of the outstanding features of the machine 10 is the provision of an elongate cylindrical pivot tube 25 which is the 'backbone' of the machine. The tube 25 is positioned near the top and to the rear of the frame 12. The tube 25 extends the full length of the machine from the entrance end 18 to an exit end 26. The load and closure sections are rotatably mounted on the tube 25. The sections are moveable between generally horizontal operating positions as viewed in Figures 1-3 and generally vertical elevated positions as seen in Figure 4. The elevated positions are provided to facilitate cleaning and service.

0012A shock absorber 27 cushions movement between the operating and cleaning positions. An adjustable bolt and lock nut 28 act against a stop 30 to accurately position the sections in their operating positions, Figure 3. When the sections are in their operating positions, the shock absorber is in an extended condition as shown in phantom in Figure 3. When the sections are in their cleaning position the shock absorber is fully contracted and vertically aligned with frame end post 32, as seen in Figure 4.

0013When the sections are in the elevated or upright position of Figure 4, the centre of gravity has gone over centre. That is the centre of gravity is a) to the left, as seen in Figure 3, of an imaginary plane extending vertically and bisecting vertical posts 32 of the frame 12 when the sections are in their operating positions and b) to the right, as seen in Figure 4, of the imaginary plane when in their upright positions. Since the centre of gravity has passed over centre, the sections will remain in the upright positions until a force is applied to rotate the sections about the axis of the pivot tube to bring the centre of gravity to the front (the left as seen in Figure 3) of the machine and maintain the sections in the operating positions.

0014A drive 34 is operable to drive the workpiece feed belts of both the loading and the closure sections. Driving force is supplied by a motor 36. The drive also causes an annular knife blade 38 to rotate and sever workpiece web lips which support a plastic web as it is transported through the loading section, Figure 5. Trimmed scrap is pulled from the machine by a scrap puller 40, Figure 2. The puller 40 is driven by the motor 36 via a belt 42.

0015The trimmed web is fed through the closure section by belts made in accordance with the teachings of the Sealer Belt Patent and sealing is effected with sealer mechanism as described in the Sealer Belt Patent modified to utilise a new and novel heat source subassembly 44. Indeed, the principal novelty of the closer section 15 resides in a heat source subassembly 44 as shown in Figures 5 through 9 inclusive.

0016Referring now to Figures 5 - 9, the subassembly includes an elongate heat tube 46. An elongate resistance heater 48 is positioned eccentrically in the heat tube 46. An air supply conduit 50 is connected to the heat tube to provide a flow of air through a conduit 51 to and over the heater 48 to heat the flowing air. The heated air exits through an elongated opening 52 in the heat tube 46 The heat tube, when in use, is positioned such that the opening 52 is immediately above a small workpiece space between heater belts 54. The heater belts grip work pieces (bag tops) between them and feed the work pieces longitudinally of the opening 52 for sealing.

0017The provision of a single elongate heating element 48 provides one of the advantages of the present machine over the machine of the S P Patent. More specifically the single heating element contrasts with the prior machine which used a series of relatively small resistance heaters. While the series of heaters simplified the machines design in certain respects and reduced repair costs when an element failed, the prior system produced problems. For example a heat sensor was provided to sense heater failure. Early stages of failure of one of the elements remote from the sensor would not be detected and faulty seals would result.

0018As is best seen in Figures 7-9, the subassembly 44 includes a handle 56 to facilitate removal of the subassembly from and return to the closure section. The subassembly 44 includes spaced side mounting plates 58. The mounting plates frictionally engage spaced side locators of the closure section to position the subassembly on the closure section. When the machine is to be cleaned, an operator grasps the handle 56 and moves the subassembly 44 from the mounted position of Figure 7 through the partially removed position of Figure 8 to the removed condition of Figure 9. The subassembly is removed by simply lifting the handle upwardly to remove the subassembly as a locating rod 60 pivots about a pivot rod 61. The subassembly is then placed in a waterproof cabinet 62 shown in dotted lines in Figures 1 and 2. The cabinet 62 is constructed and positioned such that the loading and closure sections 14,15 can be moved freely from their operating positions to the cleaning positions and return.

0019When the subassembly is to be mounted on the closure section, a pointed free end of the locating rod is inserted into a mating hole of the subassembly to achieve location transversely of the path of workpiece travel through the closure section. The locating rod then pivots about the pivot rod 61 to guide the subassembly into its mounted use position on the closure section.

0020When the,sections are to be moved form their operating positions to their cleaning positions, the sections will be cleared of any plastic web used in packaging and the subassembly 44 is removed. It is then necessary to rotate the loading section first. Returning now to Figures 1 through 6 and to Figures 5 and 6 in particular it will be seen that the reason why the loading section must be rotated first is, the drive 34, apart from a closure part 64, is carried by and forms a part of the loading section 14. As is best understood by reference to Figure 6, the closure part 64 is disconnected from the remainder of the drive 34 when the loading section is rotated from its operating to its cleaning position. Upon return to the operating positions, the closure section should be returned first.

0021On subsequent return of the loading section to its operating position a locating pin 66 in the closure part extends into an alignment bore 68 in the drive to bring the drive into appropriate alignment with the closure part. Once the motor 36 is energised the drive will rotate until a drive pin 70 engages a driven pin 72 in the closure part. Once the pins 70,72 are in engagement the sealer belts will be driven to feed loaded bags through the closure section. Any delay between energising the motor 36 and driving of the sealer belts is not a problem because a web of bags must first be fed through the previously emptied loading section.

0022Another feature of the invention resides in the provision of a safety air cylinder 74, best seen in Figures 7-9. The cylinder is of the type in which a cylinder rod 75 is spring biased outwardly such that in a de-energised condition of the cylinder the rod projects outwardly as far as the cylinder's construction will permit. When the machine is in operation the air under pressure is supplied to the cylinder and the rod is retracted. Upon a malfunction of the machine the cylinder is de-energised and the internal spring drives the piston 75 upwardly. The piston in turn will engage and elevate the subassembly 44 to space the heat source from workpieces between the belts 54.