Abstract:
A gravity feed roller track and method of manufacturing same are disclosed. The roller track includes a roller tray in which a plurality of rollers are frictionally held. The tray includes a bottom wall from which first and second side supports normally extend. Each of the side supports is substantially z-shaped in vertical cross-section. More specifically, each of the side shapes includes upper and lower vertical sections laterally spaced by an angled extension wall. A plurality of recesses are provided in the extension walls and lower vertical support wall for receipt of hubs of each of the rollers. The tracks allow for smooth rolling and dispensing of product from the roller track, accommodate a range of product sizes, and enable a single size roller to be used with tracks of various width.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to gravity fed shelving for product conveyance, such as at the retail level and, more particularly, to improved rollers and tracks therefor.  
         BACKGROUND OF THE INVENTION  
         [0002]    Roller-type gravity fed shelving is typified by the roller-type commodity stand of U.S. Pat. No. 6,089,385, and the Conveyor of U.S. Pat. No. 5,048,661. Additionally, there are also the “Volume Master” (Trademark) gravity flow tracks made by Anthony Manufacturing Company, Inc., of San Fernando, Calif. Finally, the assignee of the present application also has long made its NylaRol® gravity flow shelving. Particularly, rollers transversely mounted at spaced locations along one or more track members, and with their uppermost height stationed at a point above the tracks, are used to roll-convey product along the track. In a gravity-fed alignment situation, the rear of the track is higher than the front or dispensing end, and product is fed by gravity and rolls to the frontmost available position along the track.  
           [0003]    Because of the various products needing conveyance, e.g. half gallon milk containers on the one hand versus soft drink cans and cartons of half and half cream on the other hand, product widths vary greatly. When used in retail sales settings, e.g. convenient stores, it is imperative that such gravity fed roller tracks operate smoothly, continuously feed the product to the front without a product “hangup” on any portion along the track, and can be easily installed and cleaned. However, various problems are found with the prior art gravity fed roller products. For example, separate track members are often required for each unit; the units are difficult to clean when there has been spillage (e.g., milk leaking from a container); the roller hubs often extend beyond the outer limits of the exterior track walls, thereby causing restriction to roller spin in many cases; the use of large-diameter rollers inherently creates a larger than desirable, center-to-center distances between roller axes; neither the rollers nor the tracks can be removed from the angled shelf without disassembly, i.e. creating expensive and time consuming cleanings and adjustments; and different width products require different sized rollers and tracks. Regarding the latter, when the prior larger-diameter rollers are utilized, smaller product containers, e.g. quart containers and square half gallon containers, often ride rough, and even hangup during gravity feeding, due to the larger center-to-center distance between rollers.  
         SUMMARY OF THE INVENTION  
         [0004]    The z-tray of the present invention is easily formed from a stamped flat metal sheet, and then formed up to create the unique z-shape, whereby the hubs of the unit-length mini rollers are rotatably supported in the side walls of the z-tray, while the upper (or “rolling engagement”) surface of each roller is maintained at a height above the supporting side walls of the z-tray. Once formed, the z-tray is a one piece, completely removable and easily cleanable rigid conveyor roller track, without any separate track members being required. The present z-tray design permits a minimum of clearance between adjacent product conveyance lanes. Since the roller hubs do not extend beyond the outside limits of the exterior vertical walls of a given z-tray, there is no chance for roller spin restriction, as is common in the prior art. The small center-to-center dimensions available through the use of the present small diameter unit rollers, permits successful transport of very small product packages, i.e., less than 3″ in depth.  
           [0005]    The glass filled injectable plastic material preferably used for molding the present mini rollers enable each roller to be molded without distortion, and the glass fill assists in increasing the strength and hardness of each roller. To create optimal rolling ability, and thereby reduce friction, a preferred axial diameter-to-roller diameter ratio is utilized for the present mini roller part.  
           [0006]    The present invention overcomes the problems in the prior art by providing a specially configured “z-tray” for use with small-diameter rollers, preferably formed as injection molded and glass-filled members. To accommodate larger product width, as compared to small product width, the same length, small-diameter roller of the present invention can be utilized, but simply with a z-tray that has been formed with wider outside retaining walls, still leaving the rollers high. That is, whether a given z-tray is for a large product or a small product, its roller support structure is formed to retain the same size mini roller, and the outside retaining walls are then closer or farther apart depending on the conveyed product&#39;s width. Further, larger diameter prior art-style rollers, such as the standard aluminum tube with nylon hub-type roller commonly used, can be retrofitted into the present invention&#39;s z-type tray to create an improved gravity fed roller track having lift out and easy cleaning capability. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The foregoing advantages and benefits of the present invention are joined with accompanying drawings, of which:  
         [0008]    [0008]FIG. 1 is a perspective view of a gravity flow roller track constructed in accordance with the teachings of the invention;  
         [0009]    [0009]FIG. 2 is an enlarged fragmented view of a roller and roller hub mounted within a recess of the roller track of FIG. 1;  
         [0010]    [0010]FIG. 3 is a fragmented side view of the roller track of FIG. 1;  
         [0011]    [0011]FIG. 4 is an end view of the roller track of FIG. 1 with side walls of the roller track being formed shown in phantom;  
         [0012]    [0012]FIG. 5 is a perspective view of an alternative embodiment of a roller track constructed in accordance with the teachings of the invention;  
         [0013]    [0013]FIG. 6 is a fragmentary top view of a roller and roller hub mounted in a recess of the roller track of FIG. 5  
         [0014]    [0014]FIG. 7 is a fragmentary side view of the roller track of FIG. 5;  
         [0015]    [0015]FIG. 8 is a cut-away perspective view of an end roller of FIG. 5;  
         [0016]    [0016]FIG. 9 is a fragmentary side view of the roller track of FIG. 5;  
         [0017]    [0017]FIG. 10 is a fragmentary end view of the roller track of FIG. 5, with a roller being inserted into the back being shown in phantom lines; and  
         [0018]    [0018]FIG. 11 is a perspective view of a second alternative embodiment of a roller track constructed in accordance with the teachings of the invention. 
     
    
       [0019]    While the invention is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    Referring now to the drawings, and with specific reference to FIG. 1, a roller track constructed in accordance with the teachings of the invention is generally referred to by reference numeral  20 . While the track  20  is generally depicted as a gravity feed roller track, meaning that the track is angled so as to allow gravity to pull products forward to a dispensing position, it is to be understood that the teachings of the invention can be employed for construction of other types of roller conveyors including horizontal conveyors. Moreover, while the roller track  20  depicted will be described below primarily for use in conjunction with product movement within refrigerated display cases of convenient stores, refrigerators, and the like, or boxed bulk food shelving at warehouse food stores, it is to be understood that such conveyors can be employed in other situations requiring product conveyance as well.  
         [0021]    As shown in FIG. 1, the roller track  20  includes a roller frame or tray  22  within which are mounted a plurality of rollers  24 . In each of the depicted embodiments, the roller tray  22  includes a bottom wall  26  which is substantially planar in shape, and which includes first and second side edges  28 ,  30  from which first and second side supports  32  and  34 , respectively, extend vertically upwardly or normal to the bottom wall  26 .  
         [0022]    As shown best in FIG. 4, each of the side supports  32 ,  34  includes a lower vertical support wall  36 , an intermediate extension wall  38  and an upper guide wall  40 . The lower and upper walls  36 ,  40  are substantially parallel and offset by a distance a equal to the width of the extension wall  38 .  
         [0023]    Again as shown best in FIG. 4, the extension wall  38  extends outwardly and downwardly from an upper edge  42  of each lower support wall  36 . The angle at which the extension wall  38  extends from the lower support wall  36 , referred to in FIG. 4 as reference character β, is preferably an acute angle within the range of about 45° to about 85°, and more preferably about 75°, the importance of which will be discussed in further detail herein.  
         [0024]    Turning now to FIGS. 2 and 3, the roller tray  22  is shown to include a plurality of spaced recesses  44  for receipt of the rollers  24 . Each of the recesses  44  is formed in the extension wall  38  and lower support wall  36  of one of the first and second side supports  32 ,  34 . As shown best in FIG. 3, the shape of the recess within the lower support wall  36  may be substantially circular while, as shown in FIG. 2, the shape of the recess formed within the extension wall  38  may be substantially rectangular. Each of the recesses  44  may further include a retention nib  46  or pair of retention nibs  46  to decrease the width of the recess  44  sufficiently so as to frictionally engage and retain the rollers  24 , while allowing the rollers  24  to rotate freely.  
         [0025]    With respect to each of the rollers  24 , the embodiment depicted in FIGS.  1 - 4  shows each to be of a unit length and made of a unitary piece of material, preferably injection molded plastic with a glass fill. One preferred material is a 6/6 Nylon with 30-35% glass beads available from Arbon Corporation, under part no. 124-0-B. Such a material provides adequate strength and hardness in the roller while enabling the roller to be molded within strict tolerances and with minimized distortion or other deformation. Each of the rollers  24  preferably includes a central cylinder  48  having first and second ends  50 ,  52 , from which hubs  54  and  56  extend, respectively. In a preferred embodiment of the roller  24 , each of the central cylinders  48  includes a diameter of approximately 0.25-0.75″ and a length of approximately 1.5 to 5.5″. More preferably, each cylinder has a diameter of about 0.3125″ and a length of about 2.5″. Of course, the roller  24  can be manufactured to alternative dimensions, but the inventors have found that such dimensions are preferable to ensure free flow of product through the roller track  20  by allowing sufficient top clearance of the roller cylinders  24  over the extension walls  38 , yet also have sufficiently small center-to-center dimensions. Accordingly, a roller diameter to roller length ratio of approximately 0.09 to 0.12 is preferable, although rollers of alternative ratios are certainly possible and encompassed within the scope of the present invention.  
         [0026]    In addition to such dimensions, it is preferable to closely space the rollers  24 . Doing so increases the surface area or area of contact between the product being conveyed by the roller track and the cylindrical cylinders  48 , thereby reducing the load on each roller  24  and facilitating movement and preventing product hang ups during conveyance. The inventors have found that, using rollers of the above dimension, a center-to-center spacing is preferably within the range of about 0.25 to 0.75″ and more preferably approximately 0.375″. Of course, in alternative embodiments, wherein rollers of larger dimension are used for example, spacings of larger dimension would be employed.  
         [0027]    Referring now to FIG. 4, it will be noted that a top edge  58  of each cylindrical cylinder  48  extends above the upper edge  42  of the lower support wall  36  by a distance γ. One benefit of such positioning is that a product  60  (as shown in phantom lines in FIG. 4) can roll upon the central cylinders  48  of each roller  24  with adequate clearance between a bottom surface  62  of each product  60  and the extension wall  38 . In concert with such clearance, the guide walls  40  ensure lateral positioning of the product  60 . Accordingly, not only does the product  60  remain correctly positioned on the roller track  20 , but the product  60  also freely moves along the roller track  20  when positioned at a sufficient incline, such as that shown in FIG. 3, to ensure gravity feed of the product  60 .  
         [0028]    Turning now to FIGS.  5 - 10 , an alternative embodiment of a roller track constructed in accordance with the teachings of the invention is again generally referred to by reference numeral  20 . Wherein like elements are employed in the alternative embodiment, like reference numerals are used in the following description. One difference with respect to the alternative embodiment of FIGS.  5 - 10 , is with respect to the rollers  24 . Each of the rollers  24  includes a central cylinder  48 , first and second ends  50  and  52 , and first and second hubs  54  and  56  as with the first embodiment.  
         [0029]    However, the rollers  24  of the alternative embodiment are not of a unitary construction. Rather, each roller includes a hollow cylindrical sleeve  66  (preferably formed of metal, e.g. aluminum) with stub axles  68  and  70  (preferably formed of injection-molded plastic) inserted into hollow ends  50 ,  52 . As shown best in FIG. 10, each of the stub axles  68 ,  70  includes an end plate  72  from which a spacer  73  and a hub  54 ,  56  laterally extend. Opposite the spacer  66  and hub  56 , a retention cylinder  74  laterally extends inwardly. The retention cylinder  74  may be sized so as to frictionally engage an inner circumferential surface  76  of the metal sleeve  66 , or may include a plurality of retention wedges or other structures to provide sufficient frictional interference between the retention cylinders  74  and the metallic sleeve  64 . Such rollers are commonly available, as through the assignee. It can therefore be seen that the teachings of the invention enable conventional rollers to be retrofitted into the z-shaped roller trays  22 , thereby reducing cost, alleviating inventory, and facilitating use.  
         [0030]    Turning now to FIG. 11, a still further embodiment of a roller track  20  constructed in accordance with the teachings of the invention is illustrated. The second alternative embodiment is constructed identically to that of the embodiment of FIGS.  1 - 4 , but as will be noted, the extension walls  38  are of a substantially greater dimension. Each of the rollers  24  are of the same length and diameter as that of the first embodiment, but the extension walls  38  are elongated so as to increase the distance Δ between the guide walls  40 . Accordingly, where the product  60  to be conveyed is of a substantially greater width, it can be accommodated on the roller track  20  of the second alternative embodiment.  
         [0031]    For example, whereas the roller track  20  of the first embodiment (FIGS.  1 - 4 ) may be sized to accommodate quart size milk cartons in a convenience store refrigerator (having generally a three inch width dimension), the roller track  20  of the second alternative embodiment may be sized to accommodate half gallon cartons, or perhaps even full gallon jugs (the latter having generally a six inch width dimension). The guide walls  40  are sufficiently spaced to accommodate such sizes, and the rollers  24  provide sufficient surface area for smooth movement of the product  60  through the roller track without any hangup or jerky movement. The angle β between the extension walls  38  and the lower support walls  36  and clearance γ between the product  60  and the lower support wall  36  are sufficient so as to avoid any interference between the extension walls  38  and the product  60 .  
         [0032]    In manufacturing roller tracks  20  according to the teachings of the invention, a first step is to fabricate a blank (not shown) cut to the dimensions of the desired conveyor. This may be performed by, for example, die cutting or stamping metal, such as aluminum. Preferably, the blank is stamped with recesses  44  therein.  
         [0033]    As shown best in FIG. 4, a next step is to form the blank into the z-shaped tray  22 . This may be performed, for example, by folding the ends of blank into the desired z-shaped configuration and then folding the sides  32 ,  34  upwardly as indicated in phantom lines in FIG. 4.  
         [0034]    Once the tray  22  is so formed, the roller track  20  can be completed by inserting the rollers  24  into opposite pairs of recesses  44 . As indicated in phantom lines in FIG. 10, this can be achieved by snapping a first hub  56  of each roller  24  into a suitable recess  44 , and then downwardly depressing the opposite hub  54  of the same roller  24  into frictional engagement with an opposite recess  44 . The roller  24  is thereby rotatably retained and journalled in the tray  22  with the track  20  being completed when each of the recesses  44  is filled with rollers  24  as depicted in FIGS. 1 and 5.  
         [0035]    From the foregoing, it will be appreciated that the teachings of the invention can be used to construct a gravity feed roller track with substantially improved operation.