Patent Document

BACKGROUND OF THE INVENTION 
     This invention relates generally to the art of film wrapping systems for use in wrapping objects with shrink wrap film, such as polyurethane wrapping film, and more particularly to improvements directed to dispensing such film from a film roll. 
     A wide variety of systems are known for wrapping packages in thermoplastic film. Some of these machines are known as L-sealers because they form “trim seals” utilizing a web of center folded film. More recent machines have utilized a continuous longitudinal sealer and a cross sealer which moves at approximately the velocity of the packages as they travel through the machine so that it is not necessary to stop the packages while performing the end sealing operation. Such prior art machines have generally been of three types. One type had a continuous side sealer and a complex series of multiple flighted end sealing jaws which were spaced for a particular product. This type required substantial set-up time for change in length of product to be wrapped. A second machine of this type, while making packages similar to those produced on an L-sealer worked by drawing film off a roll under tension, folding it around the product, drawing it past a hot knife side sealing mechanism and then formed the end seal with a moving end sealer. 
     A third type of machine had an overlapped longitudinal seal on the top or bottom of the wrapped packages. Since the overlap not only ran along the bottom of the packages but also ran halfway up both ends, the packages lacked the neat appearance and hence the sales appeal of the trim sealed packages as made on the L-sealers. Since many of the products so wrapped are sold in self-service retail stores, the appearance of the package has an important effect on the sales of the product. An additional disadvantage of the overlapped seal is that the width of the web of film must be precisely correct, requiring an exact width film for each size of product. 
     Shrink wrap packaging systems of these types process and wrap a variety of different products. Commonly, such products are of differing shapes, sizes and dimensions. For example, shrink wrap packaging systems may process and wrap a single compact disc (CD) package which is very thin or other consumer retail items which have a significantly greater height and larger vertical dimension. 
     One problem associated with most known shrink wrap packaging system is the difficulty to efficiently process and wrap a wide variety of packages and products, especially those having distinctly different dimensions and heights. For example, most known shrink wrap packaging systems utilize film which is provided on a roll in two plies with each ply being joined together by a longitudinal fold line. The two-ply film is dispensed from the supply roll typically in a direction generally perpendicular to the feed direction of the products to be wrapped. As the film is dispensed and delivered to a wrapping station of the shrink wrap packaging system, it is commonly inverted and reoriented to provide an opening for convenient access and entry of the products between the dual plies of the film. The film is reoriented by an upper and a lower film inverting rod or plow system. The upper and lower film inverting rods are positioned above and below, respectively, the feed conveyor which is advancing the products to be wrapped. Examples of such an arrangement are shown in U.S. Pat. Nos. 3,583,888; 3,583,889; 4,035,983; and 4,219,988, each of which are incorporated by reference herein. 
     The film inverter rods disclosed in the above-identified patents are each fixed relative to one another so that the spacing between the inverter rods is fixed. Recent advancements in the art of shrink wrap packaging systems have included adjustable film inverter rods to accommodate a variety of differing height products being wrapped. As such, the spacing between the film inverter rods may be adjustable. 
     However, one problem associated with adjustable film inverter rods is that the delivery of the two-ply film to the film inverter rods is often misaligned providing for poor geometry for the film being delivered to the film inverter rods once the spacing between the inverter rods is changed. Optimally the free edges of the upper and lower plies should be generally aligned with one another downstream from the film inverter rods for proper wrapping of the products and positioning of the side seam on the product. However, when the upper film inverter rod is moved relative to the lower film inverter rod for a different height product, the geometry of the film being delivered and processed at the wrapping station becomes misaligned. As a result, the film will not track properly and will not be in the required tubular configuration at the wrapping station. This requires readjustment and/or refeeding of the film through the various rollers, significant operator involvement and down time of the packaging system. The misalignment of the upper and lower plies of the film results in improperly wrapped products, side seals on the products which are located in a conspicuous or improper location, inefficient use or waste of the film wrapping material and other associated problems. 
     Therefore, a need exists in the shrink wrap packaging industry for a packaging system which can readily accommodate a wide variety of product configurations and heights without the above-described problems associated with known film delivery systems and wrapping operations. 
     SUMMARY OF THE INVENTION 
     These and other objectives have been achieved with this invention, which in one embodiment includes a film delivery unit for a shrink wrap packaging system. The film wrapping system includes a feed conveyor to delivery a series of products to a wrapping station. The wrapping station includes a pair of film inverter rods which are adjustable for spacing from one another to correspond to the height of the product being wrapped. A film delivery unit dispenses a supply of two-ply film in a direction generally perpendicular to the feed direction of the products. The two-ply film is inverted by the inverter rods at the wrapping station where the products are inserted between the plies of the film. The system includes a film inverter rod adjustment mechanism to adjust the spacing between the rods. 
     The system also includes a film delivery unit adjustment mechanism to adjust a position of the film delivery unit and the film being delivered to the wrapping station as a function of the spacing between the film inverter rods and, consequently, the height of the product being wrapped. In one embodiment of this invention, the film delivery unit adjustment mechanism moves the film delivery unit and the supply of film upstream in the feed direction relative to the film inverter rods for larger height products and downstream for smaller height products. Additionally, the system in another embodiment includes an adjustable roller positioned between the film delivery unit and the wrapping station to deliver the film to the wrapping station at a desired height relative to the position of the film inverter rods. 
     The shrink wrap packaging system also includes a side seal mechanism and an end seal mechanism each located downstream in the feed direction from the wrapping station to join the first and second plies together and enclose each of the products in individually wrapped packages. A heat shrink tunnel in one embodiment is located downstream from the sealing mechanisms to heat the film and thereby shrink it around the product as is well known in the industry. 
     As a result of the film delivery unit and associated adjustment mechanism according to this invention, a variety of product configurations and heights can be conveniently and efficiently wrapped while adjusting the spacing between the film inverter rods without fouling the geometry of the film delivery system and thereby avoiding the associated problems and disadvantages of shrink wrap packaging systems in the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objectives and features of the invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a top view of a film wrapping system and associated method according to one embodiment of this invention; 
     FIG. 1A is a view similar to FIG. 1 of a portion of the wrapping system with a film delivery unit re-positioned; 
     FIG. 2 is a schematic view of a series of products as they travel through the system and in addition showing a film folding operation; 
     FIG. 3 is a perspective view of the film delivery unit and a product wrapping station of the system of FIG. 1; 
     FIG. 4 is schematic end view of the components of FIG. 3 with a portion of the film delivery unit removed to show the film path; and 
     FIG. 5 is plan view of the film delivery unit of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, a top view of an exemplary automatic high-speed film packaging system  10  according to one embodiment of this invention is shown. The system  10  generally includes a feed conveyor  12 , a film delivery unit  14 , a wrapping station  16 , a side sealer  18 , an end sealer  20 , associated downstream conveyor(s)  22  and a heat shrink tunnel  24 . Products P to be wrapped in film  26  enter the system  10  via a feed conveyor  12 . The conveyor  12  delivers the spaced-apart and generally aligned products P to the wrapping station  16  where a folded film  26  from a film roll  28  in the film delivery unit  14  surrounds each product P. The folded film  26  enveloping each product P is sealed at its free edges  30 ,  30  by the side sealer  18  to form a tube of film  26  enclosing the spaced products P. The film salvage  32  (FIG. 2) at the sealed edge  34  is severed and removed. The film  26  between the adjacent products P is sealed and severed at the end sealer  20  to produce individual sealed packages of the product P. 
     The system  10  wraps a product P in a flexible plastic film  26  in which the travel of the product P is essentially continuous through the system  10  in a feed direction indicated by arrow A. The film  26  may be any one of a variety of films well known in the art and is supplied to the system  10  as a folded web at right angles to the feed direction of the product P (shown in FIGS. 1 and 2) through the system. The film  26  is provided to upper and lower inverter rods  36   a ,  36   b  of the wrapping station  16  where the film  26  is redirected and turned inside out to travel in the feed direction with the products P delivered by the feed conveyor  12 . 
     The feed conveyor  12  pushes products P into the wrapping station  16  to cause them to be enclosed by the folded film  26  supplied by film delivery unit  14  on the top, bottom, and one side of the product P with the other side of the product P adjacent to the free edges  30 ,  30  of the folded film  26  being open initially. The product P thus enclosed in the web of film  26  travels with the film  26  past the side sealing mechanism  18  in FIG. 1 which seals the two free edges  30 ,  30  of the folded film  26  together to form a continuous tube of film which envelops the succession of products P which are being fed into the system  10  by feed conveyor  12 . The side sealer  18  also severs the excess width  32  of film  26  from the tube and this salvage  32  is removed by a salvage accumulator  38 , such as a vacuum or other take-up mechanism. 
     As the product P progresses further through the system  10 , the end sealing mechanism  20  seals the trailing edge  40  of each package while simultaneously sealing the leading edge  42  of the succeeding package in the system and it also severs one package from the other while the packages are traveling without stopping through the system  10 . The end seal mechanism  20  is so designed that it travels a short distance with the product P at substantially the same velocity while the seal is being made. After the seal has been made, the sealing mechanism  20  releases from the film  26  and returns to its original position to repeat the transverse seal for the next product. The wrapped product may then be conveyed through the shrink tunnel  24  for shrinking of the film around the product. While exemplary embodiments of the side sealer  18 , end sealer  20  and shrink tunnel  24  are shown and described herein as part of the system, specific models or embodiments of these components could readily be varied or changed as known by one of ordinary skill in this art without departing from the scope of this invention. 
     Because the product P being wrapped in the film proceeds through the system  10  at a substantially uniform velocity, the system  10  is capable of operating at film web speeds as high as 120 feet per minute although 60 to 100 feet per minute is a more typical speed. The system  10  is capable of wrapping in excess of one product P per second. 
     FIG. 2 shows the various stages of wrapping of successive products P 1 -P 5  with the plastic film  26  as the products proceed through the system  10 . Product P 5  is shown in FIG. 2 as being partially covered by the folded film  26  as it passes between the inverter rods  36   a ,  36   b . Product P 4  is shown exiting the side sealer  18  with the salvage  32  of the film  26  being separated from the side sealed package P 4  and being collected by salvage accumulator  38 . The side sealer  18  produces the side seal  34  that completes the tube envelope of relatively loose plastic film  26  around the products P. 
     The end sealing mechanism  20  produces a trim seal between the packages P 3  and P 2 . The end sealing mechanism  20  also severs the film  26  to provide product P 3  with a leading edge  42  and product P 4  with a trailing edge  40 . The product P 1  is shown as it exits from the heat shrink tunnel  24  where the loose fitting film envelope is shrunk to form a tight fitting film cover. The system  10  is designed to accommodate a variety of product heights and configurations as shown by product P 3  having a greater height than the other products. It will be appreciated that FIG. 2 is schematic and the relative positions of the products P 1 -P 5  and associated components of the system  10  have been adjusted for simplification. 
     The component parts and the assembly in combination of the continuous high-speed wrapping system  10  of FIG. 1 will now be discussed in detail, focusing in particular on the wrapping station  16  and the film delivery unit  14 . 
     Preferably, the product P is centered with respect to the feed conveyor  12  by means of guides (not shown) as is readily understood by those skilled in this art. The film  26  is folded about a longitudinal fold  44  thereby forming upper and lower plies  46   a ,  46   b  in which each ply has a free edge  30  opposite from the fold line  44 . Commonly, the two-ply folded film  26  is provided on the supply roll  28 . Alternatively, single ply film may be provided on a supply roll and subsequently folded into the described two-ply configuration as is well known in the art. 
     As shown particularly in FIGS. 1,  2  and  4 , the two-ply film  26  is delivered from the supply roll  28  by the film delivery unit  14  in a direction indicated by arrow B generally perpendicular to the feed direction (arrow A) of the products P. As the film  26  enters the wrapping station  16 , each ply  46   a ,  46   b  is guided around one of the film inverter rods  36   a ,  36   b  and thereby redirected approximately 90° to travel in the feed direction of arrow A. The film inverter rods  36   a ,  36   b  are oriented approximately 45° with respect to the feed direction. In addition to being redirected, the film  26  is inverted by the film inverter rods such that confronting inner first faces  48 ,  48  of the film  26  provided by the film delivery unit  14  are inverted so that previously outer second faces  50 ,  50  of the plies  46   a ,  46   b  of the film  26  are juxtaposed to each other and around the product P downstream from the film inverter rods  36   a ,  36   b.    
     As shown particularly in FIGS. 3 and 4, each film inverter rod  36   a ,  36   b  is joined to a pair of mounting rods  52 ,  54  to form a generally triangular configuration. Mounting rod  52  is oriented generally parallel to the feed direction; whereas, mounting rod  54  is oriented generally perpendicular to the feed direction. An inclined guide tab  56  is mounted proximate the intersection of each film inverter rod  36  and the associated mounting rod  52 . The intersection between each film inverting rod  36  and the associated mounting rod  52  provides a reference point R which will be discussed herein below. 
     Film inverter rods  36   a ,  36   b  and the associated mounting rods  52 ,  54  are mounted to a hub  58   a ,  58   b , respectively. The hub  58   b  for the lower film inverter rod  36   b  is fixed beneath the feed conveyor  12 . The hub  58   a  for the upper film inverter rod  36   a  is mounted on a film inverter rod adjustment mechanism  60  to adjust a spacing S between the upper and lower film inverter rods  36   a ,  36   b  in a direction generally perpendicular to the feed direction (i.e., vertically) to accommodate products P of differing heights. The film inverter rod adjustment mechanism  60  in one embodiment includes an operator hand wheel  62  mounted atop a threaded rod  64  to rotate the rod  64 . The hub  58   a  includes a threaded aperture  66  engaged with the threaded rod  64  as well as two additional apertures  68 ,  68  through which guide rods  70 ,  70  project. In operation of the system  10 , the operator rotates the hand wheel  62  in the appropriate direction to raise or lower the upper film inverter rod  36   a  so that the upper ply  46   a  of the film  26  is positioned slightly above the top upper surface of the product P being wrapped. The upper and lower film inverter rods  36   a ,  36   b , as well as the film inverter rod adjustment mechanism  60 , are mounted to a block  72  which is supported on a platform  74  underlying the lower film inverter rod  36   b  as well as the feed conveyor  12 . A frame  76  supports the wrapping station  16 , associated film inverter rod components as well as the film delivery unit  14  as shown in FIG.  3 . The downstream conveyors  22  and associated components are not shown in FIG. 3 to provide a better view of the components in the wrapping station  16  and the film delivery unit  14 . 
     The film delivery unit  14 , as shown generally in FIGS. 3-5, is mounted adjacent to the wrapping station  16  in a direction generally perpendicular to the feed direction. The film delivery unit  14  supplies film  26  from the supply roll  28  to the wrapping station  16 . The supply roll  28  is supported by a cradle assembly  78  of the film delivery unit  14 . The cradle assembly  78  includes a pair of spaced cradle rollers  80 ,  80  mounted for rotation between spaced end plates  82 ,  82  of the cradle assembly  78 . The supply roll  28  is positioned atop the cradle rollers  80 ,  80  and between a pair of film roll retainer posts  84   a ,  84   b . Preferably, the gap between the film roller retainer posts  84   a ,  84   b  is adjustable to accommodate supply rolls  28  of different lengths. Specifically, in one embodiment, the downstream film roll retainer post  84   b  is joined to a bracket  86  that is secured by a set screw  88  in a slot  90  of front frame member  92  in the cradle assembly  78 . To adjust the spacing between the film roll retainer post  84   a ,  84   b  for different length supply rolls  28 , the operator would loosen the set screw  88  and slide the bracket  86  and associated film roll retainer post  84   b  along the slot  90  to the appropriate position to capture the supply roll  28  between the film roll retainer post  84   a ,  84   b.    
     Referring to FIG. 4, the path of the film  26  from the supply roll  28  through the delivery unit  14  and to the wrapping station  16  is shown. The supply roll  28  rotates on the cradle rollers  80 ,  80  and the film  26  is fed around a lower deflecting roller  94  toward a film splitter insert  96 . The film splitter insert  96  advantageously separates or loosens the two film plies  46   a ,  46   b  from one another to avoid difficulty downstream in the film path in case the film  26  has an excessive buildup of static electricity, is particularly tacky or otherwise resistant to having the plies  46   a ,  46   b  separated. After the film splitter insert  96 , the film  26  travels between a pair of nip rollers  98 ,  100  and downwardly around a dancer roller  102 . The lower nip roller  98  is preferably rubber and is coupled to a belt drive  104  trained around the output shaft of a motor  106 . The motor  106  rotates the rubber nip roller  98  thereby pulling the film  26  from the supply roll  28 . The motor  106  which drives the roller  98  must turn the supply roll  28  in a direction to provide film  26  to the wrapping station  16 . The motor  106  must at all times provide film  26  in excess of the maximum speed of the feed conveyor  12  to ensure minimum tension of the film  26  as it passes over the film inverter rods  36   a ,  36   b . The dancer roller  102  is coupled to a tension arm  108  for pivotal movement about a tension pivot  110  to maintain tension on the film  26 . If slack in the film  26  develops because of an interruption in the flow of products P, for example, the tension arm  108  is coupled to a controller (not shown) for the motor  106  to interrupt the dispensing of the film  26  until additional film is required by the wrapping station  16 . As such, film tension is controlled by the dancer roller  102  through the tension arm  108  in association with the control of the motor  106 . 
     The upper nip roller  100  may include a number of pins or spikes  112  to perforate the film  26  passing between the nip rollers  98 ,  100  as is customary in the shrink wrap industry. The film  26  passes around an intermediate deflecting roller  114  and an upper deflecting roller  116  before exiting the film delivery unit  14 . The various rollers  94 ,  98 ,  100 ,  102 ,  114  and  116  extend between a pair of spaced sidewalls  156 ,  156  of the film delivery unit  14 . 
     The system  10  includes a film delivery height adjustment roller  118  positioned between the film delivery unit  14  and the wrapping station  16 . The roller  118  is mounted between a pair of arms  120 ,  120  which are coupled to corresponding links  122  mounted to the frame  76 . Advantageously, the position of the arms  120 ,  120  and subsequently the position of the roller  118  is adjustable to deliver the film  26  to the wrapping station  16  at an appropriate height relative to the position of the film inverter rods  36   a ,  36   b . Preferably, the vertical position of the roller  118  is equal distance between the upper and lower film inverter rods  36   a ,  36   b . Since the spacing S between the film inverter rods is adjustable, the height of the film delivery roller  118  is likewise adjustable to provide for proper positioning relative to the film inverter rods  36   a ,  36   b . The arm  120  supporting the roller  118  includes a set screw  124  which is captured within an arcuate slot  126  in a guide plate  128 . Adjustment of the roller  118  height is accomplished by the operator by loosening the set screw  124  and pivoting the arms  120  coupled to the roller  118  upwardly or downwardly as desired and then resecuring the set screw  124  with the roller  118  in the appropriate position approximately midway between the upper and lower film inverter rods  36   a ,  36   b . As the film  26  passes around the roller  118 , the two plies  46   a ,  46   b  are separated and guided by the respective film inverter rods  36   a ,  36   b  to surround the product P on the conveyor  12 . 
     As shown particularly in FIGS. 3-5, the film delivery unit  14  is movably mounted relative to the frame  76  on a pair of spaced generally tubular rails  130 ,  130 . In one embodiment, each of the rails  130  extends generally in the feed direction and is supported on one of a pair of spaced generally U-shaped brackets  132  mounted to a lower portion of the frame  76 . The film delivery unit  12  moves on the rails  130 ,  130  by a series of support roller bearings  134 . Each support roller bearing  134  is mounted for rotation between a pair of downwardly depending support plates  136 ,  136  mounted on a lower surface of the film delivery unit  14 . Preferably, each pair of support plates  136 ,  136  has two upper and one lower support roller bearing  134  mounted therebetween for rotation along the respective rail  130 . The support roller bearings  134  are positioned as generally shown in FIG. 5 to provide support and stable movement along the rails  130 ,  130  of the film delivery unit  14  as required. 
     The position of the film delivery unit  14  is adjustable on the rails  130 ,  130  in a direction generally parallel to the feed direction in via a film delivery unit adjustment mechanism  138 . The film delivery unit adjustment mechanism  138  according to one embodiment of this invention provides for proper positioning and delivery of the film  26  to the wrapping station  16  as a function of the spacing S between the film inverter rods  36   a ,  36   b . Specifically, in one embodiment, the film delivery unit adjustment mechanism  138  includes an adjustment knob  140  mounted for rotation and projecting from casing  142  mounted to the frame  76 . The adjustment knob  140  is mounted for rotation relative to the casing  142  and is coupled to a threaded rod  144  which is engaged in a threaded aperture  146  in one of the sidewalls  156  of the film delivery unit  14 . As such, rotation of the adjustment knob  140  and the threaded rod  144  attached thereto moves the film delivery unit  14  in a lateral direction, as shown in FIG. 5, or upstream/downstream relative to the feed direction. Proper positioning of the film delivery unit  14  and the supply roll  28  according to this invention provides for accurate and precise film  26  geometry as it is delivered through the film delivery unit  14  to the wrapping station  16 . Preferably, the film inverter rods  36   a ,  36   b  in the wrapping station  16  remain stationary as the position of the film delivery unit  14  is adjusted. 
     In particular, it has been determined that the relative position of the film inverter rods  36   a ,  36   b  in the feed direction compared to the leading or upstream edge  148  of the film supply roll  28  mounted on the delivery unit  14  is important to maintain proper geometry of the film  26  being dispensed from the supply roll  28  through the delivery unit  14  and applied at the wrapping station  16  to the products P on the conveyor  12 . The relative position of the upstream edge  148  of the supply roll  28  in comparison to the reference point R on the film inverter rods  36   a ,  36   b  is utilized to provide for proper film delivery geometry. 
     As the spacing S between the upper and lower film inverter rods  36   a ,  36   b  is adjusted to accommodate different height products P, movement of the film delivery unit  14  in a direction generally parallel to the feed direction is required to maintain proper film delivery geometry. For products P which are extremely thin and having little or no height such as a CD lying generally flat on the feed conveyor  12 , the reference point R on the film inverter rods  36   a ,  36   b  is generally aligned with the upstream edge  148  of the supply roll  28  on the film delivery unit  14 . However, the film delivery unit  14  must be moved in a direction generally parallel to the feed direction as the spacing S between the film inverter rods  36   a ,  36   b  is adjusted to accommodate different height products P. 
     In operation, the spacing S between the film inverter rods  36   a ,  36   b  is adjusted to accommodate the product P height. Once the film inverter rods  36   a ,  36   b  are so adjusted, the position of the film delivery height adjustment roller  118  is likewise set by the operator to be approximately equal distance between the film inverter rods  36   a ,  36   b . The film delivery unit  14  is then moved relative to the reference point R on the film inverter rods  36   a ,  36   b  to provide for proper alignment, geometry and delivery of the film  26  to the wrapping station  16 . According to one embodiment of this invention, the film delivery unit  14  is moved via the adjustment knob  140  along the rails  130  one-half inch to adjust for each inch in package height to establish the correct film delivery geometry. The film inverter rods  36   a ,  36   b  at the wrapping station  16  should remain stationary as the film delivery unit  14  position is adjusted. For each inch increase in product height, the position of the film delivery unit  14  is adjusted one-half inch in the upstream direction. Conversely, for each inch decrease in package height or spacing between the film inverter rods  36   a ,  36   b , a half-inch movement of the film delivery unit  14  in the downstream feed direction is required for correct film geometry. 
     For example, as shown in FIG. 1, the relative position of the edge  148  of the supply rod  28  compared to the reference point R provides appropriate tracking and film  26  delivery geometry for a product such as P 3  of FIG.  2 . However, for a product P 4  of lesser height, the spacing S is decreased and the edge  148  is adjusted with the film delivery unit  14  downstream parallel to the feed direction to a position relative to reference point R as shown in FIG.  1 A. 
     A product height indicator  150  is provided to indicate the spacing S between the film inverter rods  36   a ,  36   b . A product height adjustment scale  152  is mounted on the frame  76  and an indicator  154  moves with the film delivery unit  14  so that the operator may accurately position the film delivery unit  14  relative to the inverter rods  36   a ,  36   b . While the adjustment mechanisms  60  and  138 , as well as the positioning of roller  118 , are shown and described herein as being independent from each other, alternative embodiments of this invention include automatic adjustment of the positions of the film roll  28  and/or roller  118  in response to changes to the spacing S. 
     An important feature of this invention is the positioning of the film delivery unit  14  and the supply roll  28  thereon relative to the film inverter rods  36   a ,  36   b  in the feed direction. According to one embodiment of this invention, the film delivery unit adjustment mechanism  138  adjusts the position of the film delivery unit  14  in the upstream or downstream directions. Alternatively, the position of the film inverter rods  36   a ,  36   b  relative to the feed direction may be adjusted by movement of the block  72  relative to the frame  76  and supply roll  28  to provide for the appropriate relative position between the film inverter rods  36   a ,  36   b  and the supply roll  28  mounted on the film delivery unit  14 . Nevertheless, as a result of this invention, proper film delivery geometry from the supply roll to the film inverter rods can be easily and efficiently obtained in conjunction with the adjusted spacing between the film inverter rods to accommodate varying height products without fouling the delivery of the film along the film path and maintaining alignment of the free edges of the plies of the film wrapped around the products. 
     From the above disclosure of the general principles of the present invention and the preceding detailed description of at least one preferred embodiment, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, I desire to be limited only by the scope of the following claims and equivalents thereof.

Technology Category: b