Patent Publication Number: US-6702220-B2

Title: Web storage device for a packaging machine

Description:
TECHNICAL FIELD 
     The present invention relates to packaging machines that form a tubular bag material and deliver product to the interior thereof so that when the tubular bag material is transversely out and scaled discreet bags are formed. More particularly, the present invention relates to the delivery of plastic film to packaging machines. 
     BACKGROUND OF THE INVENTION 
     For example, in the manufacture of bags of snack foods, a tubular bag material is passed through the packaging machine. Product to be packaged is delivered into the interior of the tubular bag material with the tubular bag material then being transversely out and scaled to form discreet bags. Plastic film that forms the bag is passed about a former which forms the tubular bag material. The plastic film is delivered from rolls which are mounted on driven spindles, with the plastic film passing through a film storage device prior to delivery to the former. The film storage device aids maintaining a continuous supply of film to the packaging machine. The film is stored within the device to aid in overcoming fluctuations in the ratio of delivery and the rate of use of the plastic film. 
     The above-mentioned storage devices have included a pivotally mounted arm with a series of rollers about which the film passes. Pivoting movement of the arm aids in compensating for any differences in the rate of supply and the used rate of the film. These pivotally mounted arms have a number of disadvantages including not being able to determine with required accuracy the amount of material stored in the device and not being able to at all times maintain the correct tension in the film being delivered to the packaging machine. 
     Further disadvantages include the device occupying considerable space and being difficult to feed film through. 
     Previous film storage devices are disclosed in Patent Specifications GB2237008, U.S. Pat. Nos. 4,441,664, 5,317,858, JP08-301210 (Publication No. 10-119910), JP08-29 (Publication No. 10-119909), JP10-290828 (Publication No. 2000-118512), JP11-199092 (Publication No. 2001-018920), JP10-053989 (Publication No. 11-245916), GB1089792, U.S. Pat. Nos. 4,315,394, 4,693,053, 4,501,109 and 4,691,499. Each of these previously known devices has a film storage device which essentially includes one or more roller that moves substantially nearly relative to a fixed roller in order to store the film. 
     Disclosed in U.S. Pat. No. 4,315,394 is a device to tension film. The device includes a slit roller through which the film passes. The slip is spaced from the longitudinal axis of the roller so that angular movement of the roller adjusts the tension in the film. The roller is intended to act as a film storage device so it is relatively small in diameter and has the slip spaced from the longitudinal axis of the roller which would thereby limit the amount of film that can be stored. 
     OBJECT OF THE INVENTION 
     It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages. 
     SUMMARY OF THE INVENTION 
     There is disclosed herein a film storage device to receive film from a roll and to deliver the film to a machine, said device including: 
     a base which is to be stationary; 
     a carriage mounted on the base for pivoting movement about a fixed axis relative to the base and having a periphery about which the film is to be wound so as to store portions of the film; 
     a torque applying member engaging the carriage so as to urge the carriage to pivot about said axis in a predetermined direction; and 
     a film passage extending through the carriage transversely through said axis and between angularly spaced locations on said periphery so that film in use passes through the passage to be wound about said periphery. 
     There is further disclosed herein a film storage device to receive film from a roll and to deliver the film to a machine that uses the film, said device including: 
     a base which is stationary; 
     a carriage mounted on the base for pivoting movement about a carriage axis and having a periphery about which the film is to be wound so as to store portions of the film, said periphery including a plurality of rollers mounted on the carriage for rotation about axes parallel to said carriage axis; 
     a torque applying member engaged in a carriage so as to urge the carriage to pivot about said carriage axis in a predetermined direction; and 
     a film passage extending through the carriage transversely with respect to said carriage axis and between angularly spaced locations on said periphery so that film in use passes through the passage to be wound about said periphery. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: 
     FIG. 1 is schematic side elevation of a packaging machine and associated film delivery assembly; 
     FIG. 2 is a schematic side elevation of a film storage device; 
     FIG. 3 is a schematic and elevation of the device of FIG. 2; 
     FIG. 4 is a further side elevation of the device of FIG. 2; 
     FIG. 5 is a further end elevation of the device of FIG. 2; 
     FIG. 6 is an enlarged view of a portion of the device as shown in FIG. 2; and 
     FIG. 7 is schematic and elevations illustrating operation of the device of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the accompanying drawings there is schematically depicted a packaging machine  10 . The packaging machine  10  receives plastic film (web) and passes the film about a former  11  to form tubular bag material. The tubular bag material is pulled through the machine  10  by belt drive assemblies  12  which deliver the tubular bag material to sealing and cutting jaws  13  so that discreet bags of product are delivered to a chute  14 . Product is delivered to the interior of the tubular bag material through the interior of the former  11 . 
     Film delivered to the former  11  comes from a film supply assembly  15 . The film supply assembly  15  includes rotatable driven shafts  16  which support rolls  17  of plastic film  19 . The plastic film  19  is taken from one of the rolls  17  and is delivered to a series of rollers  18 . The plastic film  19  weaves through the rollers  18  to be delivered to a film storage device  20 . From the device  20 , the film  19  is delivered to the former  11 . 
     The film storage device  20  includes a base  31  which pivotally supports a carriage  22  about which the film  19  is wound so as to be stored thereby. The carriage  22  is urged to rotate in the direction of the arrows  23  to a maximum film storage position  24 , from a minimum storage position  25 . More particularly, the carriage  22  is urged to move in the direction of the arrows  23  by means of coil spring  26  having one end fixed with respect to the base  21  and having another end fixed to the carriage  22 . The spring  26  applies a torque to the carriage  22  in the direction of the arrows  23 . 
     The carriage  22  includes a mounting  27  upon which there is mounted a plurality of rollers  53  which provide the periphery about which the film  19  is wound as illustrated in FIG.  7 . Each of the rollers  53  is rotatable mounted for rotation about its longitudinal axis relative to the mounting  27 . 
     The carriage  22  further includes a shaft  28  welded to the mounting  27  so the mounting  27  can pivot about the longitudinal axis  29 . More particularly, the carriage  22  is mounted by way of bearings  30  for movement about the axis  29 , which axis  29  is fixed with respect to the base  21 . 
     Attached to the base  21  is a bearing housing  31  as well as a coil housing  32  supporting a coil  33 . The coil  33  is part of a brake assembly  34  which is operable to retain the carriage  22  stationary. The assembly  34  further includes a brake disc  35  urged away from engagement with the housing  32  by means of a disc spring  36 . The disc  35  is attached to the spring  36  by means of rivets  37  while the spring  36  is attached to an end member  38  by means of rivets  39 . More particularly, the member  38  is fixed to the shaft  28  by means of a key  40 . When the coil  33  is electrically energised the disc  35  is drawn into engagement with the housing  32  so that the carriage  22  is maintained stationary with respect to the base  21 . When the coil  33  is no longer energised the spring  36  moves the disc  35  from conduct with the housing  32 . 
     Associated with the end of the shaft  28  is an encoder  41  which provides a signal indicative of the angular displacement of the carriage  22  thereby enabling calculation of the length of web stored within the device  20 . 
     The encoder  41  is maintained stationary relative to the shaft  28  by means of a bracket  42  fixed to the base  21  by means of a spacer  43  and bolt  44 . 
     The angular limits of rotation of the carriage  22  and therefore the shaft  28  are defined by stops  45  (maximum storage position) and  46  which stops engaging mounting  47  fixed to the carriage  22 . A proximity switch  48  is mounted in the base  21  adjacent the stop  46  to provide a signal indicating when the carriage  22  is engaged with the stop  45 . The stops  45  and  46  are attached to the base  21  and are therefore stationary. The stops  45  and  46  are spaced by 240° thereby limiting movement of the carriage  22  to that angular displacement. 
     The carriage  22  is provided with a transverse passage  50  through which the film  19  passes. The passage  50  extends transverse of the axis  29  between two angularly spaced location on the periphery of the carriage  22  to thus enable the film  19  to pass through the carriage  22  to be wound about the periphery of the carriage  22 , that is the rollers  53 . With reference to FIG. 7, when the carriage  22  is in the position  49  the passage  50  is aligned with two stationary rollers  51  between which the web  19  passes. The rollers  51  would be mounted on the base  21 . This would normally be the feed position when the web is initially being fed through the carriage  22 . However the spring  26  urges the carriage  22  to move in the direction of the arrow  23  until it reaches the limit position  52 . At the position  52  the maximum amount of web  19  is stored. In this embodiment, the passage  50  extends through the axis  29 . As can be seen in the drawing, the passage  50  and axis  29  are in a common plane. 
     When the film  19  is being fed through the passage  50 , typically the brake assembly  34  would be activated so that the carriage  22  is maintained stationary with the passage  50  aligned with the rollers  51 . 
     The remote ends of the rollers t 3  are secured within an end plate  55  for rotation relative thereto about the longitudinal axes of the rollers  53 , that is axes parallel to the axis  29 . The rollers  53  facilitate movement of the film  19  through the device  20  as the rollers  53  rotate with the movement of the film  19 .