Abstract:
A conveyor assembly  18  that detects bags that leak. The assembly  18  includes a first conveyor  24  that operates in unison with a second conveyor  29 . The conveyors  24  and  29  confine the bags in chambers, with the bags being engaged by pressure assemblies  50  so that the bags that leak are reduced in volume. The bags are engaged at a downstream position and at an upstream position by detection devices  44  that provide a signal indicative of the volume of each bag. These signals are compared to thereby identify bags that leak.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to conveyors and more particularly, but not exclusively to conveyors employed in the packaging industry.  
         BACKGROUND OF THE INVENTION  
         [0002]    There are many instances in the packaging industry, particularly the packaging industry associated with snack foods, for bags to be delivered from a packaging machine to a predetermined location in a selected orientation. Traditionally, bags emanating from a packaging machine generally fall to a conveyor and arrive at the predetermined location in an unpredictable orientation.  
           [0003]    There is also known apparatus to test bags for leaks. For example, leaks may occur in bags where product inadvertently becomes located between the sealing jaws of a packaging machine and therefore located in the seals at the ends of the bag. Known apparatus to test bags for leaks includes reciprocally mounted plates which engage the bag to apply pressure thereto. Any reduction in the volume of the bag indicates a leak. Accordingly, the apparatus includes a sensing mechanism to detect movement of the plate and therefore a reduction in volume of the bag. Known apparatus also include a plurality of fingers which engage the bag to determine the profile thereof. Again, pressure is applied to the bag and the profile again determined. Any reduction in the volume of the bag indicates a leak. Such known apparatus are described in U.S. Pat. Nos. 6,202,476 and 6,041,646. These known leak detecting apparatus although reliable are known to fail to detect some leaks.  
         OBJECT OF THE INVENTION  
         [0004]    It is the object of the present invention to provide a conveyor which maintains the orientation of articles being conveyed thereby, and more particularly but not exclusively to overcome or substantially ameliorate the above disadvantage of known apparatus to detect leaks in bags.  
         SUMMARY OF THE INVENTION  
         [0005]    There is disclosed herein a conveyor assembly to move items along a predetermined path, said conveyor assembly including:  
           [0006]    a first conveyor length extending parallel to said path and being provided to substantially rigidly support the items in contact with said first length;  
           [0007]    a second conveyor length to be moved in unison with the first conveyor length and being substantially coextensive with respect thereto, and wherein said second conveyor length is substantially inflexible except for defamation about an axis transverse of said path so that said second length can be deformed to accommodate any of the items located between the first and second lengths by defamation of the second length.  
           [0008]    Preferably, said assembly includes:  
           [0009]    a first conveyor having said first length;  
           [0010]    a support for said first length so that the first length substantially rigidly supports the items with said second length being above said first length;  
           [0011]    a second conveyor having said second length; and wherein one of the conveyors has a first endless member and a second endless member transversely spaced from the first member.  
           [0012]    Preferably, the first and second members provide said first conveyor, with the conveyor members being generally parallel along said first length with their transverse spacing forming a gap, to provide access to items located between the first and second lengths, and said support has a longitudinal slot adjacent said gap to also provide access to the items.  
           [0013]    Preferably said assembly is adapted to convey bags, with said assembly including a detection device to protrude between the first and second members to engage the bags located between the first and second lengths to apply pressure thereto and to determine a change in the volume of the bag to thereby detect bags with leaks.  
           [0014]    In a further preferred form, said assembly is adapted to convey bags, with said assembly further including a detection device to engage said second length to apply pressure to bags located between the first and second lengths and to detect a change in volume of the bags to thereby detect bags that leak.  
           [0015]    In a further preferred form, said assembly includes first and second belts, said first and second belts being positioned on opposite sides of said first length to engage said first length so as to maintain said first length stationary with respect to said second length.  
           [0016]    There is further disclosed herein a combination to detect leaks in bags, said combination including:  
           [0017]    a conveyor assembly that receives the bags so that the bags are located at spaced locations along the conveyor assembly, the conveyor assembly providing two conveyor lengths that are coextensive and between which the bags are located so that each bag is located in a chamber defined between the lengths, each chamber having a configuration, and a retaining assembly associated with a first one of the lengths so as to maintain the configuration of the chambers provided by the lengths;  
           [0018]    a pressure assembly to engage the bags within the chambers to apply pressure thereto so that bags that leak are reduced in volume;  
           [0019]    a detector located downstream of the pressure assembly to engage each bag in its respective chamber and to provide a signal indicative of the volume of each bag engaged; and  
           [0020]    a detector upstream of said pressure assembly to engage each bag in its respective chamber and generate a signal indicative of the volume thereof so that bags that leak can be detected by comparing the signals generated by the detectors in respect of each bag.  
           [0021]    Preferably in the above combination the first length is provided by a first conveyor and said second length is provided by a second conveyor, with one of the conveyors including coextensive transversely spaced first and second endless members, and each detector includes a projection that projects between the endless members to engage the bags, and said pressure assembly includes at least one projection that projects between the endless members also to engage the bags to apply pressure thereto.  
           [0022]    There is still further disclosed herein a combination to detect leaks in bags, said combination including:  
           [0023]    a conveyor assembly that receives the bags so that the bags are located at spaced locations along the conveyor assembly, said assembly having opposing surfaces between which the bags are located so that the bags are confined; and  
           [0024]    a detector device that engages each bag at a downstream location and an upstream location so as to generate signals indicative of the volume of each bag at each location; and  
           [0025]    a pressure device to apply pressure to the bags as they pass between the upstream and downstream occasions so that bags that leak will have a reduced volume by the time they reach said upstream location so that the signals generated in respect of each bag can be compared to thereby identify bags that have been reduced in volume as a result of the pressure being applied thereto.  
           [0026]    There is still further enclosed herein a method of detecting bags that leak, said method including the steps of:  
           [0027]    locating a plurality of bags, each having a volume, on a conveyor assembly that substantially encloses the bags each in a respective chamber, each chamber having a configuration that is maintained over a length of the conveyor assembly;  
           [0028]    engaging each bag at a downstream location of said length with a detector that generates a signal indicative of the volume of the bag engaged;  
           [0029]    applying pressure to the bags upstream of said downstream detector; and  
           [0030]    engaging each bag at an upstream location, after pressure has been applied to the bags, with a detector that generates a signal indicative of the volume of each bag engaged so that the signals generated in respect of each bag can be compared to identify the bags that have been reduced in volume as result of the pressure being applied thereto. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0031]    A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein:  
         [0032]    [0032]FIG. 1 is a schematic side elevation of a packaging machine and conveyor assembly associated therewith;  
         [0033]    [0033]FIG. 2 is a schematic side elevation of a portion of the conveyor of FIG. 1;  
         [0034]    [0034]FIG. 3 is a schematic side perspective view of a portion of the conveyor of FIG. 1;  
         [0035]    [0035]FIG. 4 is a schematic side elevation of a device to engage bags being moved by the conveyor of FIG. 1 to apply pressure to the bags;  
         [0036]    [0036]FIG. 5 is a schematic end elevation of the conveyor portion of FIG. 3;  
         [0037]    [0037]FIG. 6 is a schematic side elevation of a device to aid in detecting bags with leaks;  
         [0038]    [0038]FIG. 7 is a schematic end elevation of the device of FIG. 6;  
         [0039]    [0039]FIG. 8 is a schematic side elevation of a modification of the conveyor of FIG. 1 with a device to aid in detecting bags with leaks;  
         [0040]    [0040]FIG. 9 is a schematic top plan view of a link employed in the conveyor of FIG. 1;  
         [0041]    [0041]FIG. 10 is a schematic top plan view of a portion of a conveyor employed in FIG. 1;  
         [0042]    [0042]FIG. 11 is a schematic end elevation of the link of FIG. 9;  
         [0043]    [0043]FIG. 12 is a schematic end elevation of a pin employed in the conveyor portion of FIG. 10; and  
         [0044]    [0044]FIG. 13 is a schematic end elevation of a conveyor portion of FIG. 10. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    In the accompanying drawings, there is schematically depicted a packaging machine  10  that receives batches of product through a former  11 . The former  11  also receives a strip of bag material  12  and forms the bag material  12  into a tubular configuration that is to pass through the machine  10 . The machine  10  has a rotary jaw assembly  13  that transversely seals and transversely cuts the tubular bag material to form discreet bags  14 . The bags  14  fall from the jaw assembly  13  to a chute  15 . The tubular bag material is pulled past the former  11  and from the rolls  16  by driven belts  17 . For example, the machine  13  could be the packaging machine described in U.S. Pat. No. 4,663,917.  
         [0046]    The chute  15  is part of a conveyor assembly  18 . The assembly  18  has a longitudinally extending frame  19 . Associated with the frame  19  is a first conveyor  24  that includes a driven sprocket  25  driving an endless conveyor member or belt  26 . The lower end of the belt  26  passes a guide member  27 . The first conveyor  24  provides a first conveyor length  28 .  
         [0047]    Associated with and above the first conveyor  24  is a second conveyor  29 . The second conveyor  29  includes a driven sprocket  20  and an endless conveyor member or belt  23 . The belt  23  passes a second sprocket  21  and a vertically extending guide surface  31  within the chute  15 . The belt  23  provides a second conveyor length  32  that is substantially parallel and coextensive with respect to the first conveyor length  28 .  
         [0048]    Each belt  23  and  26  is formed from a plurality of links  33  that are preferably moulded from plastics material. The links  33  include a plurality of first projections  34  each provided with an aperture  35 . Each link  33  further has a second series of projections  35 , with the projections  35  each having an aperture  37 . A series of links  33  are arranged as shown in FIG. 10, with the projections  34  located between the projections  36  of the next adjacent link  33 . A pin  38  passes through the aligned apertures  35  and  37  so that adjacent links  33  are pivotably attached for relative movement about a longitudinal axis of the respective pin  38 . A short segment of each of the belts  23  and  26  is illustrated in FIGS. 10 and 13. Particularly with respect to the belt  23 , the link construction ensures that the belt  23  is only flexible about the longitudinal axis of the pin  38 , that is an axis transverse of the belt  23 . The construction inhibits defamation of the belt  23  apart from pivoting movement between the links  33  about the pins  38 , that is an axis transverse of the belt  26 .  
         [0049]    The chute  15  in co-operation with the belt  23  captures each bag  14  as it is delivered from the machine  13  so as to preserve the initial orientation of the bag  14 . That is, the bag  14  is retained with the lower bag seal  39  leading and being trailed by the upper bag seal  40 . More particularly, the belt  23  by moving in the direction of the arrow  41 , converges with respect to the chute  15  so as to securely engage each bag  14  and move the bags  14  in the direction of the arrow  41 . Each of the bags  14  moves along the chute  15  until it reaches the belt  26 . The belt  26  is also moving in the direction of the arrow  41  and at the same speed as a belt  23 . As the first length  28  is generally coextensive with the second length  32 , and moving in unison therewith, again the orientation of the bags  14  is retained. When the bags  14  becomes “sandwiched” between the belts  23  and  26 , the belt  23  deforms so as to pass over the bags  14  while the belt  26  remains substantially flat due to the supporting surface provided by the longitudinally extending plate  42 .  
         [0050]    In the embodiment of FIG. 3, there is provided a retaining assembly  57  including adjacent each longitudinal side of the first conveyor length  28 , a retaining belt  43 . The retaining assembly  57  engages the length  28  so that the lengths  28  and  29  provide compartments  58  relatively fixed in configuration. The retaining belts  43  have their transverse width extending generally upwardly and pass between pairs of rollers  44 , of which at least one is driven. More particularly, the belts  43  engage the belt  26  so as to maintain the configuration of the belt  26  over the first length  28  once the belt  23  has been deformed to accommodate a bag  14 . Accordingly, the bags  14  are each confined in a generally rigid compartment  58 . Each compartment is defined between opposing conveyor surfaces  59  and  60 .  
         [0051]    In the embodiment of FIGS.  1  to  7 , the plate  42  and belt  26  are longitudinally divided so that the belt  26  has two coextensive endless belt members  46  (providing the first belt length  28 ), with the belt members  46  spaced by a gap  47 . The plate  42  has a longitudinal slot  58  adjacent the gap  47 .  
         [0052]    In this embodiment, there is provided in combination with the conveyor assembly  18  a detection device  44  to detect bags that leak. The device  44  includes a detector  45  as seen in FIG. 6. The detector  45  includes an arm  48  that projects through the gap  47  and slot  58  to engage the bag  14 . The detector  45  generates a signal indicative of the volume of the bag  14 . More particularly, the arm  48  is attached to a signal generator  49  that generates the abovementioned signal. The arm  48  is urged into contact with the bags  14  by the arm  57  being weighted.  
         [0053]    Located at spaced positions along the length of the first conveyor  24  are pressure assemblies  50 . Each of the assemblies  50  includes an arm  51  that is urged by means of a spring  52  into contact with the bags  14  to apply pressure thereto. This pressure will cause at least partial deflation of any bag that leaks. Each of the arms  51  is pivotably mounted by means of a pivot assembly  53  so that the arms  51  can pivot about generally horizontal transverse axis to permit the bags  14  to pass thereby.  
         [0054]    Located adjacent the upper end of the conveyor  24  is a further detector  45  comprising an upstream detector that again would generate a signal indicative of the volume of each of the bags  14  passing thereby. This is compared to the signal generated by the lower (downstream) detector  45  in respect of the particular bag  14  thereby enabling the detection of bags  14  that leak. The defective bags  14  can be removed and if required, the machine  13  stopped and serviced should that be required. The upstream and downstream detectors  45  provide a detector device that provides two signals for each bag.  
         [0055]    In the above preferred embodiment in respect of detecting bags that leak, the bags  14  are engaged by each detector  45 . That is each bag  14  is engaged by a single arm  48  so that there is a relatively small contact area with the bags  14 . This enhances detection as any volume reduction will result in a substantial angular deflection of the arm  48  of the upstream detector  45  relative to the arm  48  of the downstream detector  45 .  
         [0056]    In an alternative embodiment (as shown in FIG. 8), detectors  54  are employed. Each detector  54  includes a pivoted arm  55  terminating with rollers  56 . The rollers  56  are urged into contact with the conveyor  23  to thereby apply pressure to the bags  14 . A bag  14  that leaks will therefore reduce in volume as the conveyor  23  deforms under the rollers  56 . The detectors  54  include electronic apparatus to produce a signal indicative of the angular displacement of the arms  55 . Should the arms  55  have a significant different angular displacement for a specific bag  14 , the bag  14  would be considered defective, that is, a bag that leaks. Again the bag would be removed, and the machine  13  serviced if required.