Abstract:
A packaging machine utilizing side connected chains of open bags is disclosed. The machine has loading and closure sections which are moveable between operating and cleaning/service positions. A resistance heater subassembly is removeable to enable washdown.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to packaging and more particularly to a novel and improved method and apparatus for forming packages using pre-formed side connected bags.  
       BACKGROUND OF THE INVENTION  
       [0002]     U.S. Pat. No. 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.  
         [0003]     With 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 U.S. Pat. No. 5,722,218 issued Mar. 3, 1998 and entitled Plastic Transport System, herein (the Load Belt Patent).  
         [0004]     As 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 U.S. Pat. No. 6,170,238 issued Jan. 9, 2001 and entitled Sealing Machine and Method, herein (the Sealer Belt Patent)  
         [0005]     The SP, Load Belt and Sealer Belt Patents are herein incorporated by reference in their entireties.  
         [0006]     While 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 a novel and improved machine of the SP Patent constructed to facilitate cleaning and to be adaptable for food packaging.  
       SUMMARY OF DISCLOSURE  
       [0007]     A machine made in accordance with the present disclosure includes loading and closure sections which are pivotal between package forming positions and cleaning positions. In the cleaning position the undersides of the loading and closure sections are positioned for facile cleaning. In the preferred and disclosed arrangement the sections are respectively mounted on an elongated tube for rotation about the tube axis between use and cleaning positions.  
         [0008]     The 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. In the preferred and disclosed arrangement 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. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a foreshortened side elevational view of the improved packaging machine;  
         [0010]      FIG. 2  is a top plan view of the machine foreshortened am amount corresponding to the four shortening in FIGURE.  1 ;  
         [0011]      FIG. 3  is an end elevational view of the machine with the load and closure sections in their operating positions;  
         [0012]      FIG. 4  is an end elevational view of the machine in which the load and closure sections have been moved to their cleaning positions;  
         [0013]      FIG. 5  is a plan view of the closure section on a scale enlarged with respect to  FIGS. 1 and 2 ;  
         [0014]     FIGURE.  6  is a front elevational view of the closure section on the scale of  FIG. 5 ;  
         [0015]      FIG. 7  is a sectional view of the closure section on an enlarged scale with respect to  FIGS. 5 and 6  and as seen from a plane indicated by the line  7 - 7  of  FIG. 5 ;  
         [0016]      FIG. 8  is a sectional view corresponding to  FIG. 7  showing the removable heater element assembly in a partially removed state; and  
         [0017]      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  FIGS. 7 and 8  and on the same scale. 
     
    
     DETAILED DESCRIPTION  
       [0018]     Referring now to the drawings and to  FIGS. 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  FIG. 1 , under an entrance end  18  of the load section.  
         [0019]     When 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.  
         [0020]     One 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  FIGS. 1-3  and generally vertical elevated positions as seen in  FIG. 4 . The elevated positions are provided to facilitate cleaning and service.  
         [0021]     A 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,  FIG. 3 . When the sections are in their operating positions, the shock absorber is in an extended condition as shown in phantom in  FIG. 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  FIG. 4 .  
         [0022]     When the sections are in the elevated or upright position of  FIG. 4 , the center of gravity has gone over center. That is the center of gravity is a) to the left, as seen in  FIG. 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  FIG. 4 , of the imaginary plane when in their upright positions. Since the center of gravity has passed over center, 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 center of gravity to the front (the left as seen in  FIG. 3 ) of the machine and maintain the sections in the operating positions.  
         [0023]     A 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,  FIG. 5 . Trimmed scrap is pulled from the machine by a scrap puller  40 ,  FIG. 2 . The puller  40  is driven by the motor  36  via a belt  42 .  
         [0024]     The 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 utilize 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  FIGS. 5 through 9  inclusive.  
         [0025]     Referring now to  FIGS. 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.  
         [0026]     The 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.  
         [0027]     As is best seen in  FIGS. 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  FIG. 7  through the partially removed position of  FIG. 8  to the removed condition of  FIG. 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 water proof cabinet  62  shown in dotted lines in  FIGS. 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.  
         [0028]     When 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.  
         [0029]     When 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  FIGS. 1 through 6  and to  FIGS. 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  FIG. 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.  
         [0030]     On 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 energized 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 energizing 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.  
         [0031]     Another feature of the invention resides in the provision of a safety air cylinder  74 , best seen in  FIGS. 7-9 . The cylinder is of the type in which a cylinder rod  75  is spring biased outwardly such that in a de-energized condition of the cylinder the rod projects outwardly as far as the cylinder&#39;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-energized 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 .  
         [0032]     Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction, operation and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.