Abstract:
An apparatus for use in a shrink packaging machine for accommodating a greater height variance of articles includes: rollers, each roller including a shaft and a cylinder on the shaft for rotation about an axis of the shaft; and a frame including a pair of parallel side members generally extending in a first, horizontal direction and defining slots receiving opposite ends of the shafts for mounting of the rollers there between. Each of the slots has a slot length that extends in horizontal and vertical directions, and the rollers each generally extends in a third direction orthogonal both to the horizontal and vertical directions. Furthermore, each of the rollers is received within a pair of the slots and is vertically and horizontally displaceable and, when each roller is disposed at its respective lowermost position, the axes of the rollers do not all lie within a horizontal plane.

Description:
COPYRIGHT STATEMENT 
   All of the material in this patent document is subject to copyright protection under the copyright laws of the United States and other countries. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in official governmental records but, otherwise, all other copyright rights whatsoever are reserved. 
   BACKGROUND OF THE INVENTION 
   The present invention relates generally to shrink packaging machines and, in particular, to shrink packaging machines for shrink wrapping thin or lightweight articles including, for example, easily deformed, bent, or folded articles that are thin or light weight, and that have a range of various heights. 
   In shrink wrapping articles, it is common to entirely cover each article top and bottom with a shrink film, such as polyvinyl chloride or polypropylene soft shrink material, and then transport the article covered in shrink film on a mesh or solid belt conveyer, or sometimes a roller conveyer, through a shrink tunnel including a hot air chamber. Typically, hot air is heated to between 150° Fahrenheit and 600° Fahrenheit and blown in the hot air chamber onto the shrink film while it is conveyed through the shrink tunnel. The hot air shrinks the shrink film about the article. 
   If the article happens to be thin, then pressure exerted on the article by the shrinking film tends to cause deformation or bending of the article. Additionally, if the article happens to be lightweight, then turbulent air blown within the hot air chamber tends to cause the article to float or otherwise lift off of the conveyor and move around within the chamber, which is undesirable. 
   A number of approaches to solving the problem of shrink wrapping thin or lightweight articles have been utilized. One older approach utilizes both bottom and top mesh or solid belt conveyers synchronized to travel in the same direction through the tunnel at the same speed. The top conveyer is spaced over the bottom conveyer at a distance which allows the particular article to fit between and contact the two conveyers. The use of two synchronized conveyers is fairly expensive and requires resetting of the distance between the two conveyers whenever an article having a new thickness is to be shrink wrapped. Furthermore, such an approach can not be readily deployed in existing shrink packaging machines that are not built to accommodate this approach. 
   In another approach to solving the problem of shrink wrapping thin or lightweight articles, efforts have been made to develop a low energy shrink film which can be used at lower temperatures and with less air circulation. Although such an approach may have merit, more traditional mechanical approaches may be preferable. 
   Another approach developed some years ago is disclosed in U.S. Pat. No. 5,009,057 to Wilkinson (“the &#39;057 Patent”), the entirety of which is hereby incorporated herein by reference. This approach is illustrated and described herein with respect to  FIGS. 1-12 , and the present invention is considered to represent an improvement to shrink packaging machines and methods that utilize the approach of the &#39;057 Patent. 
   In accordance with the &#39;057 Patent, a shrink packaging machine  10  represented in  FIGS. 1-5  includes a conveyer  12  for transporting an article  46  wrapped in shrink film through a shrink tunnel  14  and a hot air chamber  16  in which hot air is blown onto the shrink film within the shrink tunnel  14 . The shrink packaging machine  10  also includes an apparatus  18  that prevents the article from becoming deformed and prevents the article from lifting off of the conveyer  12  during the shrink wrapping process. 
   The apparatus  18  includes a plurality of spaced apart rollers  20  and a support  22  for disposition of the plurality of rollers  20  above the conveyer  12 . The plurality of rollers  20  are maintained by the support  22  in a disposition above and out of contact with the conveyer  12 . Alternatively, the rollers  20  may be maintained by the support  22  in a disposition in which the rollers  20  rest upon the conveyer  12  as shown in order to accommodate an extremely thin article  46 . 
   Each of the plurality of rollers  20  includes a central horizontal shaft  24  and a cylinder  26  rotatably mounted on the shaft  24 . Each cylinder  26  is covered with a high temperature-resistant non-stick coating, such as silicon rubber or Teflon®. Support  22  includes a pair of side rails  28 , 30  spaced apart and forming slots  32  for receiving opposite ends of the shafts  24 . The slots  32  of the left side rail  28  are directly opposite and identical in shape to corresponding slots  32  of the right side rail  30  so that the axis of each of the plurality of rollers  20  extends in a direction generally orthogonal to the direction of motion  34  of the conveyer  12 . 
   The support  22  also includes threaded studs  36  passing through both side rails  28 , 30  for securing the side rails  28 , 30  in a fixed, spaced apart relationship. Each threaded stud  36  is secured to the side rails  28 , 30  by inner nuts  38  and outer nuts  40 . 
   As shown in  FIG. 5 , each slot  32  extends in a direction that includes both a vertical component  42  and a horizontal component  44  relative to the direction of the conveyor motion  34 . The vertical component  42  allows the vertical displacement of a corresponding one of the plurality of rollers  20  by an article  46  as the article is conveyed past the roller  20 . The horizontal component  44  allows a corresponding roller  20  to be pushed slightly backwards in the direction of motion  34  of the conveyer  12 , thereby making it easier for the article  46  to lift the roller  20 . 
   As shown in  FIG. 3 , the support  22  also includes threaded legs  48  mounted to pivot about axes  50  in respective directions  52 , 54  that are transverse to the direction of motion  34  of the conveyer  12 . The legs  48  thus can be pivoted outwardly from the side rails  28 , 30  and adjusted in length through adjusting nuts  56  to properly brace against side ledges  58  and upwardly extending lips  60  of the shrink packaging machine  10 . The threaded legs  48  are of the same diameter and thread pitch as the threaded studs  36  so that all may be cut from the same stock. By simply cutting the threaded studs  36  to the proper length, the apparatus  18  can be easily made to work with any width conveyer or article  46 . 
   Each side rail  28 , 30  may form regularly spaced upper holes  62  and regularly spaced lower holes  64  positioned just above the slots  32  for receiving the threaded studs  36 . The side rails  28 , 30  also form regularly spaced pairs of apertures  65  for receiving mounts  66  for the mounting of threaded legs  48 . The rails  28 , 30  can thus be cut to any length without special manufacture, and both rails can be cut from the same stock, simply reversing the direction which a particular rail faces to make it either a right side rail  30  or a left side rail  28 . 
   A thin flat article  46  is shrink wrapped by covering the article  46  with shrink film and then conveying the article  46  on conveyer  12  through the shrink tunnel  14 . At least one of the plurality of rollers  20  forcibly holds down the article  46  forcing it into constant engagement with the conveyor  12  as hot air is blown on article  46  in the hot air chamber  16 . The plurality of spaced apart rollers  20  permits the hot air to be blown in-between the rollers  20  and around the article  46 . 
   In the shrink packaging machine  10  as shown in  FIGS. 1-5 , the cylinders  26  of the rollers  20  actually contact the surface of the conveyer  12  which, in turn, imparts to each cylinder  26  rotational motion around its respective shaft  24  further facilitating the movement of the article  46  covered in shrink film through the shrink tunnel  14 . In this respect, the rollers  20  each at least contacts the particular article  46  during its passage through the shrink tunnel  14  even if each roller  20  does not actually touch the conveyer  12 , although it also is possible for the rollers  20  to be disposed just slightly above the article  46  in order to simply prevent the article  46  from curling or deforming more than a limited amount. 
   A second apparatus  18  representative of the approach of the &#39;057 Patent is illustrated in  FIGS. 6-12 , wherein similar structures are referenced by the same callout numbers. The illustrations of the second apparatus  18  have been simplified in order to render more apparent the differences between the prior art of the &#39;057 Patent and various embodiments of the present invention. 
   In this respect, a right side elevational view of the second apparatus is illustrated in  FIG. 6 , and a front elevational view of the second apparatus  18  is illustrated in  FIG. 7 . A right side elevational view of the second apparatus  18  is illustrated in  FIG. 8  and is shown in operation with a conveyor  12  of a shrink packaging machine  10  wherein a thin article  46  is about to be shrink wrapped. Because of the low profile (height) of the article  46  relative to the diameter of the rollers  20 , the article  46  moves smoothly underneath the rollers  20  by displacing them vertically and horizontally. Articles  86  relatively thicker than article  46  also may be guided smoothly underneath the rollers  20  if the thicker articles  86  have appropriate contours that enable each roller  20  to be displaced vertically and horizontally, as shown in  FIGS. 9-10 . For example, the articles  86  of  FIGS. 9-10  each includes a generally wedge-shaped profile on its leading edge that provides an incline for ascension of the rollers  20 . 
   In contrast, the second apparatus  18  of the shrink packaging machine may not properly work with a series of thick, non-contoured articles  146  to be shrink wrapped as illustrated, for example, in  FIGS. 11-12 . In this scenario, the thicker size of the lead article  146  tends to contact the first roller  20  at an angle nearly perpendicular to the surface of the roller  20  and, instead of being guided smoothly underneath the roller  20 , the article  146  is blocked and even damaged by the roller  20 , as illustrated in  FIG. 12 . 
   In this situation, even though the second apparatus  18  may have sufficient vertical roller movement to accommodate the thickness of the article  146 , the thickness of the article  146  relative to the diameter of the roller  20  and the distance between the roller  20  and the conveyor  12  act to prevent such vertical displacement from occurring. This further leads to lifting of the rearward portion of the article  146  off of the conveyor  12 , especially when the first roller is disposed in contact with the conveyor  12  and, as a result, is undergoing rotational movement that tends to force downward the front portion of the article  146 . 
   As will be appreciated by the Ordinary Artisan, the scenario illustrated in  FIG. 12  may result in damage to the article  146 , misalignment of one or more of the articles  146  passing into the second apparatus  18 , and/or jamming of the apparatus  18 , all of which then may require undesired manual intervention, moreover, it will be appreciated that, while the second apparatus  18  illustrated in  FIGS. 11-12  could be raised to properly work with the thicker articles  146 , such modification and setup of the shrink packaging machine  10  also requires manual intervention. 
   Accordingly, a need exists for an apparatus that may be used, for example, in place of the second apparatus of  FIGS. 6-12  and that accommodates both the articles  46  and articles  146  shown therein. One or more embodiments of the present invention comprise such an apparatus. 
   SUMMARY OF THE INVENTION 
   In a first aspect of the invention, a shrink packaging machine for shrink wrapping an article with shrink film includes: a hot air chamber; a conveyor operable to transport the article covered by shrink film at least partially through the hot air chamber; a first roller disposed over the conveyor and configured to engage the article transported on the conveyor; and a plurality of additional rollers disposed over the conveyor. Each of the plurality of additional rollers is vertically displaceable relative to the conveyor independent of displacement of the other of the plurality of additional rollers. Furthermore, when each of the plurality of additional rollers is in a respective lowermost position relative to the conveyor, an axis of rotation of the first roller is disposed at a height from the conveyor that is greater than a respective height from the conveyor at which each axis of rotation of each of the plurality of additional rollers is disposed. 
   In a feature of this aspect, the first roller is vertically displaceable relative to the conveyor independent of displacement of the plurality of additional rollers. The first roller may be vertically displaceable within a slot and the extent of vertical displacement may be limited by a blocking member or an insert that is removable disposed within the slot. The first roller also may be horizontally displaceable relative to the conveyor. Alternatively, the first roller may be disposed in fixed vertical disposition over the conveyor. 
   In another feature of this aspect, one of the plurality of additional rollers is configured to engage the article transported on the conveyor during engagement of the article by the first roller. 
   In another feature of this aspect, each of the first roller and the plurality of additional rollers has the same diameter. Alternatively, the first roller may have a diameter different from a respective diameter of each of the plurality of additional rollers. In this respect, the diameter of the first roller may be greater than the respective diameter of each of the plurality of additional rollers and, moreover, the first roller may be driven by contact with the conveyor and each of the plurality of additional rollers may be driven by contact with the conveyor when each of the plurality of additional rollers is in its respective lowermost position relative to the conveyor. 
   In yet another feature, the machine further includes a second roller disposed over the conveyor that is configured to engage the article transported on the conveyor during engagement of the article by the first roller. Moreover, when each of the plurality of additional rollers is in its respective lowermost position relative to the conveyor, an axis of rotation of the second roller is disposed at a height from the conveyor that is greater than a respective height from the conveyor at which each axis of each of the plurality of additional rollers is disposed. The axis of the first roller, in turn, is disposed at a height from the conveyor that is greater than the height from the conveyor at which the axis of the second roller is disposed. 
   With additional regard to this feature, the second roller may be vertically displaceable relative to the conveyor independent of displacement of the other of the plurality of additional rollers. The second roller further may be horizontally displaceable relative to the conveyor. The first roller also may be vertically displaceable relative to the conveyor independent of displacement of the plurality of additional rollers with the second roller being vertically displaceable to an extent greater than that of the first roller. The vertical displacement of the first roller and the vertical displacement of the second roller both also may be limited by a blocking member, such as a pivot arm or a slot insert. Alternatively, the first roller and the second roller both may be disposed in fixed vertical disposition over the conveyor. 
   In another aspect of the invention, a method of shrink wrapping an article in a shrink packaging machine includes the steps of: transporting on a conveyor into a hot air chamber of the shrink packaging machine an article covered in shrink film; engaging the article being transported on the conveyor with a first roller such that the first roller rolls over the article and applies a downward force onto the article as the article passes there under; as the first roller rolls over the article and applies a downward force onto the article, engaging the article being transported on the conveyor with a second roller such that the second roller rolls over the article and applies a downward force onto the article as the article passes there under. The step of engaging the article with the first roller further comprises engaging the article with the first roller at a first initial vertical height from the conveyor that is less than the initial vertical height of an axis of rotation of the first roller from the conveyor, and the step of engaging the article with the second roller further comprises engaging the article with the second roller at a second initial vertical height from the conveyor that is less than the initial vertical height of an axis of rotation of the second roller from the conveyor, the initial vertical height of the axis of rotation of the second roller from the conveyor being less than the initial vertical height of the axis of rotation of the first roller from the conveyor. 
   In a feature of this aspect, the method comprises the further step of engaging the article being transported on the conveyor with a third roller such that the third roller rolls over the article and applies a downward force onto the article as the article passes there under, the further step being performed as the second roller rolls over the article and applies a downward force onto the article. The step of engaging the article with the third roller further may comprise engaging the article with the third roller at a third initial vertical height from the conveyor that is less than the initial vertical height of the axis of rotation of the third roller, the initial vertical height of the axis of rotation of the third roller being less than the initial vertical height of the axis of rotation of the second roller. 
   In another feature, the step of engaging the article with the first roller further comprises engaging the article with the first roller such that the first roller is vertically displaced in a direction generally orthogonal to the direction of transport of the article on the conveyor. The step of engaging the article with the first roller further may comprise engaging the article with the first roller such that the first roller also is horizontally displaced in a direction generally parallel to the direction of transport of the article on the conveyor. 
   In another feature of the method, the step of engaging the article with the first roller further comprises engaging the article with the first roller such that the first roller is neither vertically displaced in a direction generally orthogonal to the direction of transport of the article on the conveyor nor horizontally displaced in a direction generally parallel to the direction of transport of the article on the conveyor. 
   In another feature, the method further comprises the step of adjusting the initial vertical height of the axis of rotation of the first roller by moving a member that defines a lower margin of a slot against which the first roller is supported. The initial vertical height of the axis of rotation of the second roller also may be adjusted by moving a member that defines a lower margin of a slot against which the second roller is supported. 
   In another feature, the method further comprises the step of adjusting the initial vertical height of the axis of rotation of the first roller by installing an insert into a slot in which the first roller is retained such that the insert defines a lower margin of the slot which the first roller abuts. The initial vertical height of the axis of rotation of the second roller also may be adjusted by installing an insert into a slot in which the second roller is retained such that the insert defines a lower margin of the slot which the second roller abuts. 
   In still another feature, the method further comprises the step of adjusting the initial vertical height of the axis of rotation of the first roller by installing the first roller in a pair of opposed apertures among a plurality of opposed aperture pairs, each of the pair of opposed apertures having a different vertical height from the conveyor. The initial vertical height of the axis of rotation of the second roller also may be adjusted by installing the second roller in a pair of opposed apertures among a plurality of opposed aperture pairs, each of the pair of opposed apertures having a different vertical height from the conveyor. 
   In a feature of this aspect of the invention, the first roller may be driven by the conveyor by positioning the first roller in contact with the conveyor. The second roller also may be driven by the conveyor by positioning the first roller in contact with the conveyor. 
   In another feature, the method further comprises the steps of successively engaging the article being transported on the conveyor with each of a plurality of additional rollers such that each of the plurality of additional rollers applies a downward force onto the article as the article passes there under. In this feature, the steps of successively engaging the article with each of a plurality of additional rollers further may comprise successively engaging the article with each of a plurality of additional rollers at the same initial vertical height that is less than the respective vertical height of the axis of rotation of each additional roller, and further may comprises engaging the article with each of the plurality of additional rollers such that each additional roller is both vertically displaced in a direction generally orthogonal to the direction of transport of the article on the conveyor and horizontally displaced in a direction generally parallel to the direction of transport of the article on the conveyor. 
   In yet a third aspect of the invention, an apparatus for use in a shrink packaging machine includes: a plurality of rollers, each roller including a shaft and a cylindrical member mounted on the shaft for rotation about an axis of the shaft; and a frame including a pair of parallel side members generally extending in a first, horizontal direction and defining a plurality of slots receiving opposite ends of the shafts of the rollers for mounting of the rollers between the side members. Each of the slots has a slot length that extends in a direction having both a component extending in the first, horizontal direction and a component extending in the second, vertical direction orthogonal to the first, horizontal direction. In this respect, the rollers mounted between the side members each generally extends in a third direction orthogonal both to the first, horizontal direction and to the second, vertical direction, with each of the rollers being received within a pair of the slots and being vertically and horizontally displaceable within the pair of the slots. In accordance with this aspect of the invention, the axes of the rollers do not lie within a horizontal plane when each roller is disposed at a lowermost position within its respective pair of slots. 
   In a feature of this aspect, the slot length of each a first subset of the plurality of slots is less than a slot length of each of a second subset of the plurality of slots. Each subset of slots may include only a single slot or a plurality of slots. 
   In yet another feature, the slot length of each a first subset of the plurality of slots is less than a slot length of each of a second subset of the plurality of slots; the slot length of each of the second subset of the plurality of slots is less than a slot length of each of a third subset of the plurality of slots; the side members have opposed ends in the first, horizontal direction; and the first subset of slots is disposed closer to a first the opposed end of the side members than the second subset of slots, and the second subset of slots is disposed closer to the first opposed end of the side members than the third subset of slots. 
   In another feature, the lowermost position of one of the rollers is selectively adjustable. In this respect, the lowermost position of one of the rollers may be defined by a blocking member that is adjustably positionable. For example, the blocking member may comprise an arm that is pivotably mounted and that extends adjacent to one or more of the slots. Alternatively, the blocking member may comprise an insert that is adapted to be removably disposed within the slot and the inert may be chosen from one of a plurality of differently sized inserts. For example, the inserts may have different lengths for selectively limiting the range of movement of rollers within the slots. 
   In still yet another aspect, an apparatus for use in a shrink packaging machine includes: a first plurality of rollers, each roller including a shaft and a cylindrical member mounted on the shaft for rotation about an axis of the shaft; and a frame including a pair of parallel side members generally extending in a first, horizontal direction and defining a plurality of slots receiving opposite ends of the shafts of the rollers for mounting of the rollers between the side members. Each of the slots has a slot length that extends in a direction having both a component extending in the first, horizontal direction and a component extending in the second, vertical direction orthogonal to the first, horizontal direction, and the rollers mounted between the side members each generally extends in a third direction orthogonal both to the first, horizontal direction and to the second, vertical direction. Each of the rollers mounted between the side members also is received within a pair of the slots and is vertically and horizontally displaceable within the pair of the slots, the axes of the rollers generally lying within a horizontal plane when each roller is disposed at a lowermost position within its respective pair of slots. 
   The apparatus further includes a plurality of additional rollers, each additional roller including a shaft and a cylindrical member mounted on the shaft for rotation about an axis of the shaft, each additional roller being mounted between the side members in fixed disposition relative to the side members in both the first, horizontal direction and the second, vertical direction, the additional rollers. In accordance with this aspect, the axes of the additional rollers do not lie within a horizontal plane and none are generally coplanar with the axes of the first plurality of displaceable rollers when each of the displaceable rollers is disposed at the lowermost position within its respective pair of slots. The axes of the additional rollers themselves may or may not be coplanar. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One or more embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein the same elements are referred to with the same reference numerals, and wherein: 
       FIG. 1  is a right side elevational view of a prior art shrink packaging machine along with a shrink wrapped article. 
       FIG. 2  is a left side elevational view of a prior art apparatus positioned within a hot air chamber above a conveyer of a shrink packaging machine and an article covered with shrink film to be shrink wrapped. 
       FIG. 3  is a front elevational view of the apparatus of  FIG. 2  also showing side ledges and upwardly extending lips of the shrink packaging machine. 
       FIG. 4  is a left rear perspective view of the apparatus of  FIG. 2 . 
       FIG. 5  is an elevational view of a side rail of the apparatus of FIG.  2 .; 
       FIG. 6  is a right side elevational view of a prior art apparatus similar to that of  FIGS. 1-5 . 
       FIG. 7  is a front elevational view of the apparatus of  FIG. 6 . 
       FIG. 8  is a right side elevational view of the apparatus of  FIG. 6 , shown in operation with a conveyor of a shrink packaging machine and a thin article to be shrink wrapped. 
       FIGS. 9 and 10  are right side elevational views of the apparatus of  FIG. 6 , shown in operation with a conveyor of a shrink packaging machine and a thick, contoured article to be shrink wrapped. 
       FIGS. 11 and 12  are right side elevational views of the apparatus of  FIG. 6 , shown in operation with a conveyor of a shrink packaging machine and a thick, non-contoured article to be shrink wrapped. 
       FIG. 13  is a right side elevational view of an apparatus in accordance with a first preferred embodiment of the present invention. 
       FIG. 14  is a front view of the apparatus of  FIG. 13 . 
       FIG. 15  is a right side cross-sectional view of the apparatus of  FIG. 13 , taken along line  15 - 15  of  FIG. 14 . 
       FIG. 16  is a right side elevational view of one of the side rails of the apparatus of  FIG. 13 . 
       FIG. 17  is a right side elevational view of the apparatus of  FIG. 13 , shown in operation with a conveyor of a shrink packaging machine, with an article to be shrink wrapped midway through the apparatus. 
       FIG. 18  is a right side cross-sectional view of the apparatus of  FIG. 17 . 
       FIG. 19  is a right side elevational view of a apparatus in accordance with a second preferred embodiment of the present invention. 
       FIG. 20  is a right side elevational view of a side rail of a apparatus in accordance with a third preferred embodiment of the present invention. 
       FIG. 21  is a right side view of the slot inserts of  FIG. 20 . 
       FIG. 22  is a right side elevational view of a side rail of a apparatus in accordance with a fourth preferred embodiment of the present invention. 
       FIG. 23  is a right side elevational view of a portion of an extended version of the side rail of  FIG. 14 . 
       FIG. 24  is a right side elevational view of the side rail of  FIG. 14  connected to the side rail of  FIG. 6 . 
   

   DETAILED DESCRIPTION 
   As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art (“Ordinary Artisan”) that the present invention has broad utility and application. Furthermore, any embodiment discussed and identified as being “preferred” is considered to be part of a best mode contemplated for carrying out the present invention. Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure of the present invention. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present invention. 
   Accordingly, while the present invention is described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present invention, and is made merely for the purposes of providing a full and enabling disclosure of the present invention. The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded the present invention, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection afforded the present invention be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself. 
   Thus, for example, any sequence(s) and/or temporal order of steps of various processes or methods that are described herein are illustrative and not restrictive. Accordingly, it should be understood that, although steps of various processes or methods may be shown and described as being in a sequence or temporal order, the steps of any such processes or methods are not limited to being carried out in any particular sequence or order, absent an indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and orders while still falling within the scope of the present invention. Accordingly, it is intended that the scope of patent protection afforded the present invention is to be defined by the appended claims rather than the description set forth herein. 
   Additionally, it is important to note that each term used herein refers to that which the Ordinary Artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaning of a term used herein—as understood by the Ordinary Artisan based on the contextual use of such term—differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the Ordinary Artisan should prevail. 
   Furthermore, it is important to note that, as used herein, “a” and “an” each generally denotes “at least one,” but does not exclude a plurality unless the contextual use dictates otherwise. Thus, reference to “a picnic basket having an apple” describes “a picnic basket having at least one apple” as well as “a picnic basket having apples.” In contrast, reference to “a picnic basket having a single apple” describes “a picnic basket having only one apple.” 
   When used herein to join a list of items, “or” denotes “at lease one of the items,” but does not exclude a plurality of items of the list. Thus, reference to “a picnic basket having cheese or crackers” describes “a picnic basket having cheese without crackers”, “a picnic basket having crackers without cheese”, and “a picnic basket having both cheese and crackers.” Finally, when used herein to join a list of items, “and” denotes “all of the items of the list.” Thus, reference to “a picnic basket having cheese and crackers” describes “a picnic basket having cheese, wherein the picnic basket further has crackers,” as well as describes “a picnic basket having crackers, wherein the picnic basket further has cheese.” 
   Turning now to the drawings, a right side elevational view and a right side cross-sectional view of a first embodiment  118  of an apparatus in accordance with the present invention are illustrated, respectively, in  FIGS. 13 and 15 . A front elevational view of the apparatus  118  is illustrated in  FIG. 14 . The apparatus  118  is shown in  FIGS. 13-15  in conjunction with a conveyor  12  of a shrink packaging machine  10 , wherein an article  146  to be shrink wrapped is just coming into contact with the apparatus  118 . 
   The apparatus  118  includes a plurality of spaced apart rollers  20  and a support  122  for disposition of the plurality of rollers  20  above the conveyer  12 . The rollers  20  and their disposition above the conveyor  12  are similar to those described previously with regard to  FIGS. 1-12 , and each roller  20  includes a central horizontal shaft  24  and a cylinder  26  that is rotatably mounted on the shaft  24 . The cylinder  26  of each roller  20  preferably is covered with a high temperature-resistant non-stick coating, such as silicon rubber or Teflon®. The covering may constitute an application of the material to the roller, thereby forming a coating, or, alternatively, the covering may constitute a piece of the material that is adhered, or otherwise attached to, the rollers  20 . 
   The support  122  includes a pair of spaced apart side members comprising side rails  128 , 130  which define slots  132  for receiving opposite ends of the shaft  24  of each roller  20 .  FIG. 16  is a right side elevational view of one of the side rails  130  of the apparatus of  FIG. 15 . The slots  132  of the left side rail  128  are preferably directly opposite and identical in shape to corresponding slots  132  of the right side rail  130  so that each of the plurality of rollers  20  is oriented with its axis disposed generally orthogonal to the direction of motion  34  of the conveyer  12 . The support  122  also preferably includes at least one threaded stud  36  passing through both side rails  128 , 130  for securing the side rails  128 , 130  in their spaced apart relationship. In the embodiment shown, each threaded stud  36  is secured to the side rails  128 , 130  by inner nuts  38  and outer nuts  40 . 
   Each slot  132  preferably extends in a direction having both a vertical component  42  and a horizontal component  44 . The vertical component  42  allows vertical displacement of a corresponding one of the plurality of rollers  20  by an article  146  as the article  146  is conveyed past the roller  20 . The horizontal component  44  of each slot  132  allows horizontal displacement of a corresponding roller  20  whereby the corresponding roller  20  is pushed slightly backwards in the direction  34  of motion of the conveyer  12 , making it easier for the article  146  to lift the roller  20 . 
   Each side rail  128 , 130  may form regularly spaced pairs of apertures positioned just above the slots  132  for receiving the threaded studs  36  and/or for receiving mounts for mounting threaded legs (not shown). The rails  128 , 130  thus can be cut to any length without special manufacture, and both rails  128 , 130  can be cut from the same stock, simply reversing the direction which a particular rail faces to make it either a right side rail  130  or a left side rail  128 . The threaded legs may be generally similar to the threaded legs  48  of  FIG. 3  and have similar functionality and design. 
   Referring now to  FIG. 16 , a significant distinction is evident between the slots  132  in the side rails  128 , 130  of the apparatus  118  and the slots  32  shown and described previously with respect to the apparatus  18  of  FIGS. 1-12 . Specifically, as shown in  FIG. 16 , variations in slot length exist between a first subset of slots  133 , a second subset of slots  134 , a third subset of slots  135 , and a fourth subset of slots  136  of the apparatus  118 , wherein the apparatus  18  of  FIGS. 1-12  include slots  32  having substantially uniform length, wherein each subset includes one or more slots. In this regard, each of the fourth subset of slots  136  are preferably of the same general size and design as the slots  32  shown, for example, in  FIG. 5 . The first, second and third subsets of slots  133 , 134 , 135 , however, are of progressively greater lengths, all of which are less than the slot length of the fourth subset of slots  136 . 
   Additionally, the lower end of each of the first subset of slots  133  preferably is positioned at a distance from the bottom of the rail  130  that is slightly greater than the distance from the bottom of the rail  130  of each lower end of the second subset of slots  134 . Similarly, the lower end of each of the second subset of slots  134  is positioned at a distance from the bottom of the rail  130  that is slightly greater than the distance from the bottom of the rail  130  of each lower end of the third subset of slots  135 , and the lower end of each of the third subset of slots  135  is positioned at a distance from the bottom of the rail  130  that is slightly greater than the distance from the bottom of the rail  130  of each lower end of the fourth subset of slots  136 . When rollers having similar diameters (such as illustrated rollers  20 ) are mounted in these slots, this arrangement creates a graduated or tapered opening into the upstream end of the shrink tunnel of the shrink packaging machine in which the apparatus  118  is included. 
   This graduated or tapered opening provided by the relative positions of the rollers  20  retained by the first, second, and third subsets of slots  133 , 134 , 135  provides a significant advancement over the prior arrangements of rollers  20 , such as that shown in  FIGS. 1-12 . In particular, relatively thicker articles, such as articles  146  of  FIGS. 11-12 , are accommodated by the apparatus  118  of the present invention in contrast to the apparatus  18  of the prior art illustrated in  FIGS. 1-12 . 
   In operation, the article  146  first comes into contact with the lower front portion of a roller  20  retained in a slot  133 . Because the article  146  engages the lower portion of the first roller  20 , i.e., because the article  146  does not initially engage the first roller in a direction that is substantially perpendicular to the surface of the roller at the point of engagement, the first roller  20  is readily displaced for passage of the article  146  under the first roller  20 . 
   Once the article  146  passes beneath the first roller  20 , the article  146  comes into contact with the lower front portion of the next subsequent roller  20  retained in a slot  134 . Because the first roller  20  rides on top of the article  146  when the article  146  comes into contact with the second roller  20 , the first roller  20  tends to exert pressure upon the article  146  and serves to counteract any tendency of the back portion of the article  146  to lift up from the conveyor  12  upon contact with the second roller  20 . Consequently, the second roller is more readily displaced by the article  146 . 
   The article  146  furthermore preferably engages the second roller in a direction that is not substantially perpendicular to the surface of the roller at the point of engagement, whereby the second roller is more readily displaced for passage of the article  146  there under. However, it will be appreciated that, because of the force exerted by the first roller on the article  146 , the article  146  may engage the second roller in a direction that is closer to being orthogonal to the surface of the roller at the point of engagement than the direction of contact at the point of engagement between the article  146  and the first roller. 
   The article  146  then comes into contact with the lower front portion of the next subsequent roller  20  retained in a slot  135 . Because one or more of the previous rollers continue to ride upon of the article  146  when the article  146  comes into contact with the next subsequent roller, pressure is exerted upon the article  146  that serves to counteract any tendency of the back portion of the article  146  to lift up from the conveyor  12  upon contact with the next subsequent roller. Consequently, the next subsequent roller is more readily displaced by the article  146 . 
   The article  146  furthermore preferably engages the next subsequent roller in a direction that is not substantially perpendicular to the surface of the roller at the point of engagement, whereby the next subsequent roller is more readily displaced for passage of the article  146  there under. However, it will be appreciated that, because of the continued force exerted by one or more previous rollers on the article  146 , the article  146  may engage the next subsequent roller in a direction that is closer to being orthogonal to the surface of the roller at the point of engagement than the direction of contact at the point of engagement between the article  146  and a previous roller. 
   Finally, the article  146  comes into contact with the lower front portion of the next subsequent roller  20  retained in a slot  136 . Because one or more of the previous rollers continue to ride upon of the article  146  when the article  146  comes into contact with the next subsequent roller, pressure is exerted upon the article  146  that serves to counteract any tendency of the back portion of the article  146  to lift up from the conveyor  12  upon contact with the next subsequent roller. Consequently, the next subsequent roller is more readily displaced by the article  146 . 
   The article  146  furthermore preferably engages the next subsequent roller in a direction that is not substantially perpendicular to the surface of the roller at the point of engagement, whereby the next subsequent roller is more readily displaced for passage of the article  146  there under. However, it will be appreciated that, because of the continued force exerted by one or more previous rollers on the article  146 , the article  146  may engage the next subsequent roller in a direction that is closer to being orthogonal to the surface of the roller at the point of engagement than the direction of contact at the point of engagement between the article  146  and a previous roller. In fact, the point of engagement may be such that the roller would not be displaced by the article  146  but for the continued force being exerted upon the article  146  by one or more of the previous rollers. 
   It will also be noted that the tapered opening provided by the apparatus  118  especially works well if the article  146  itself is compressible. In this regard, while the article  146  displaces the first roller  20 , the article  146  further may be compressed by the first roller  146 , thereby lowering the vertical height of its point of impact with the second roller. The degree of compression further may be increased by increasing the weight of the first roller, or by fixing the vertical disposition of the first roller as in other embodiment of the invention described below. Compression of the article  146  also tends to facilitate passage of the article  146  under subsequent rollers. 
   Some overall benefits are shown, for example, in  FIGS. 17-18 , which illustrate a right side elevational view and a right side cross-sectional view, respectively, of the apparatus  118 . As shown in  FIGS. 17-18 , a thick article  146  to be shrink wrapped has been transported midway through the apparatus  118  on the conveyor  12 . As the article  146  has passed the various rollers  20  forming the tapered opening of the shrink packaging machine, the rollers  20  are successively displaced while their weight causes the article  146  to be compressed. In this way, article  146 , which would have been too thick to be reliably guided under the first roller  20  of the prior art apparatus  18  illustrated in  FIGS. 1-12  without manual intervention and adjustment, now may be shrink wrapped without such manual intervention using the apparatus  118  of the present invention. 
   Apart from the aforementioned, the structure and operation of the apparatus  118  of the present invention is otherwise very similar to that of the apparatus  18  of  FIGS. 1-12 . In this regard, the articles  146  is shrink wrapped by covering the article  146  with shrink film in the normal way, which is well known in the art; conveying covered article  146  on conveyer  12  through the shrink tunnel; holding the covered article  146  down by exerting pressure from at least one of the plurality of rollers; and blowing hot air on the shrink film covering the article  146  in a hot air chamber while the article  146  is held down by the at least one roller  20 . 
   Furthermore, it will be appreciated that having a plurality of rollers  20  spaced apart from each other allows hot air to be blown in-between the rollers and around the article  146 . 
   The cylinders  26  of the rollers  20  also may be disposed so as to rest upon the surface of conveyer  12 , thereby imparting to each cylinder  26  rotational motion around its respective shaft  24  and further facilitating movement of the article  146  underneath each of the plurality of rollers  20  during movement of the conveyor  12 . However, as will be appreciated, in order for all of the rollers  20  to be so driven by the conveyor  12 , the diameters of the rollers  20  will differ between the rollers  20 . It alternatively is contemplated that, while each of the rollers  20  preferably is disposed low enough to actually contact the particular article  146  to be shrink wrapped, it is possible to simply have rollers  20  disposed so as to be slightly positioned above the article  146  without actually contacting the article absent initial curling or deformation of the article, which would be sufficient to prevent the article  146  from curling or deforming more than a limited amount. 
   A characteristic of the apparatus  118  of  FIGS. 13-18  is that the angle of the tapered opening created by the rollers  20  retained by the four subsets of slots  133 , 134 , 135 , 136  is fixed, i.e., the lowest point of slot  133  is vertically fixed relative to the lowest point of slot  134 , the lowest point of slot  134  is vertically fixed relative to the lowest point of slot  135 , and the lowest point of slot  135  is vertically fixed relative to the lowest point of slot  136 . 
   In variations of the apparatus  118  of the first preferred embodiment, the cylinders of the rollers may include varying diameters (rather than uniform diameters as described) such that a tapered opening is not necessarily provided and such that the conveyor drives each of the rollers when disposed in its respective lowermost position. Nevertheless, because the height of the axes of rotation of at least the first couple of the rollers successively decreases, articles having a greater height still are accommodated generally as described above. 
     FIG. 19  is a right side elevational view of a second preferred embodiment  218  of an apparatus in accordance with the present invention. This apparatus  218  is similar to the first preferred embodiment  118  except that one or both of the side rails  128 , 130  of the first preferred embodiment have been replaced by a side member such as the right side rail  230  shown in  FIG. 19 . This side rail  230  includes slots all having a substantially uniform slot length, such as the fourth subset of slots  136 ; however, the apparatus  218  also includes an adjustable positioning arm  270  mounted at a pivot point  272 . The arm  270  may have any one of various configurations so long as it serves the function of establishing a lower limit on the movement of the respective rollers  20  in one or more of the slots  136 . Thus, an upper edge  274  of the arm  270  is arranged to receive and support the end of one or more of the roller shafts  24 , as shown in  FIG. 19 . The arm  270  is held in place by tightening a fastener  276  at the pivot point  272 . 
   The arm  270  additionally, or alternatively, may be further reinforced by a second fastener  278  inserted through a curved slot  280 , located near the end of the arm  270  so as to optimize the moment of force relative to the pivot point  272 . As shown, the slot  280  may be arranged in the body of the side rail  230 , but it will be apparent that generally similar results may be achieved by locating the slot in the arm itself, provided that the arm is modified in such a way as to accommodate a slot  280  of suitable length. The second fastener  278  preferably includes a thumb screw with a relatively large diameter, thereby making adjustment thereof easier. 
   When the second fastener  278  is used, the first fastener  276  may remain loosened. In operation, the thumb screw of the second fastener  278  then only need be loosened enough to permit the arm  270  to be positioned at a desired angle. Once in place, the second fastener  278  is tightened so as to fix the lower range of movement of the roller shafts  24  in their respective slots  136 . The apparatus  218  may then be used in like manner to the one shown in  FIGS. 13-18 . However, if unsatisfactory results are being achieved in the shrink wrapping operation, or if the size of the articles being shrink wrapped is changed beyond what otherwise can be accommodated by the prevailing setting, then the lower range of movement of the roller shafts  24  may be adjusted merely by loosening the thumb screw  278 , repositioning the arm  270 , and retightening the thumb screw  278 . 
   The basic functionality of the present invention may also be accomplished in any of a variety of alternative configurations. For example, results similar to those achieved with the preferred embodiment  218  of  FIG. 19  may be achieved by replacing the pivoting arm  270  illustrated therein with a member that may be moved up and down at each end, by a plurality of separate pivoting arms or members that each control the position of a portion of the roller shafts  24 , or the like. Further, each movable end of a member or pivoting arm may be secured using a fastener inserted through a slot, as illustrated in  FIG. 19 , by a ratcheting mechanism, by a slot arrangement having a plurality of detent positions, or any other suitable attachment means. 
   Additionally, in variations of the apparatus  218  of the second preferred embodiment, the cylinders of the rollers may include varying diameters (rather than uniform diameters as described) such that a tapered opening is not necessarily provided and such that the conveyor drives each of the rollers when disposed in its respective lowermost position. Nevertheless, because the height of the axes of rotation of at least the first couple of the rollers successively decreases, articles having a greater height still are accommodated generally as described. 
     FIG. 20  illustrates a right side elevational view of a side rail  330  of yet a third preferred embodiment of an apparatus of the present invention (not shown). This side rail  330  is somewhat similar to the side rail  230  of  FIG. 19 , in that it includes slots all having a substantially uniform slot length, such as the fourth subset of slots  136 . However, the side rail  330  includes one or more slot inserts  90 , 92 , 94  (more clearly shown in  FIG. 21 ), each of which is retained in place by a fastener arrangement  96  such as, for example, a nut, washer, and bolt assembly. These inserts  90 , 92 , 94  may be installed or removed as necessary from the slots  136  nearest the front of the apparatus of which side rail  330  forms a part in order to control the lower range of movement of the roller shafts  24  in their respective slots  136 . Different sizes or numbers of inserts may be used in order to produce tapered openings of different lengths or angles. 
   In variations of the apparatus of this third preferred embodiment, the cylinders of the rollers may include varying diameters (rather than uniform diameters as described) such that a tapered opening is not necessarily provided and such that the conveyor drives each of the rollers when disposed in its respective lowermost position. Nevertheless, because the height of the axes of rotation of at least the first couple of the rollers successively decreases, articles having a greater height still are accommodated generally as described. 
     FIG. 22  illustrates a right side elevational view of a side rail  430  of a fourth preferred embodiment of an apparatus (not shown) in accordance with the present invention. This side rail  430  also provides some adjustability to the length or angle of the tapered opening, which is accomplished via the inclusion of one or more series of holes  97 , 98  in a pattern that facilitates the creation of the tapered opening. As shown in  FIG. 22 , a first series of holes  97  creates a first line, generally collinear with the bottom of the first slot  136 , while a second series of holes  98  creates a second line, also generally collinear with the bottom of the first slot  136 . Rollers  20  inserted in either series of holes  97 , 98  thus form a gradual linear progression downward from high to low, thereby creating the tapered opening. Additional series of holes, or series having different numbers of holes, may likewise be used. The opening further need not be linear and may be curved. The arrangement provide, though, suffers from the disadvantage of not permitting movement of the rollers  20  in the series of holes  97 , 98 , but provides for a tapered opening and adjustability of the angle or length of the opening that is provided. 
   In variations of the apparatus of this fourth preferred embodiment, the cylinders of the rollers may include varying diameters (rather than uniform diameters as described) such that a tapered opening is not necessarily provided and such that the conveyor drives each of the rollers when disposed in its respective lowermost position. Nevertheless, because the height of the axes of rotation of at least the first couple of the rollers successively decreases, articles having a greater height still are accommodated generally as described. 
   It will be apparent to the Ordinary Artisan that the relatively short side rails  130 , 230 , 330 , 430  shown in  FIGS. 13-22  may represent merely an end section of a longer side rail. For example,  FIG. 23  illustrates a right side elevational view of a portion of a long side rail that includes an end portion similar to the side rail  130  of  FIG. 14 . It also will be clear that the slot and hole arrangements described and illustrated above may be used in side rails of any length. 
   Alternatively, larger side rails may be constructed from shorter ones. For example,  FIG. 24  is a right side elevational view of the side rail  130  of  FIG. 14  connected to the side rail  30  of  FIG. 6 . Connection may be accomplished in any of a variety of ways, including but not limited to the connection plate  100  fastened to respective ends of the side rails  130 , 30  as shown in  FIG. 24 .