Abstract:
A flight lug is provided for releasable attachment to a conveyor belt. The lug comprises a base and first and second side walls mounted to opposite edge surfaces of the base such that the base extends between and interconnects the side walls intermediate upper and lower ends of the side walls. Flanges extend inwardly from adjacent the lower ends of the side walls. Each flange defines a slot between the flange and the lower surface of the base for receiving an edge of the belt. The first side wall is pivotally attached to the base for movement relative to the base between a first position where the flange on the lower end of the first side wall is spaced a first distance from the flange on the lower end of the second side wall for allowing the belt to fit between the flanges, and a second position where the flanges on the side walls are spaced apart a second distance which is less than the width of the belt for capturing the belt in the slots between the side walls.

Description:
BACKGROUND OF INVENTION  
       [0001]     This invention generally relates to a flight lug used in a conveyor system including one or more endless conveying belts for moving articles, and more particularly to a flight lug which is releasably fastened to a conveyor belt for selectively changing the position of, or replacing, the flight lug.  
         [0002]     A conveyor system includes one or more continuous flexible conveyor belts movably supported on a framework. There are two general types of conveyor belts, chain belts and cord belts. Cord belts comprise polyurethane or similar suitable belt material surrounding fiber or steel cords. Cord belts are preferred over chain belts for high speed conveyor systems, or when cleanliness is a process requirement.  
         [0003]     An array of spaced flight lugs are fixed along the length of a conveyor belt and project upwardly from the outer surface of the belt. The flight lugs are separated by a distance appropriate for individual articles being transported by the conveyor system, in effect, defining pockets which receive the articles. One or more flight lugs engage an article as the article is moved for properly positioning the articles on the conveyor belt and pushing the articles along in the direction of the path of travel.  
         [0004]     Conventional flight lugs used on cord belts are formed from plastic. The plastic lugs are permanently welded, or vulcanized, directly onto the belt by melting the lug and the adjoining surface of the belt. However, vulcanized lugs are sometimes distorted which eventually results in tears at the edges of the belt. If a belt with welded plastic lugs is damaged or otherwise becomes jammed, the damaged lugs must be replaced in the field or the belt changed. Replacement of the lugs necessitates disassembly of the belt. This is a time consuming process resulting in significant labor costs and machine downtime, thereby increasing the overall cost associated with using a conventional conveyor system. Moreover, removal of a damaged lug that has been welded to the belt can damage the belt.  
         [0005]     The pitch of a conveyor belt is determined by the space between the lugs. It is occasionally desirable to modify a conveying system for moving articles of different sizes, which requires changing the pitch of the belt. This is usually accomplished by moving the lugs toward or away from each other to accommodate smaller or larger articles, respectively. For example, a conveyor system running on a 12″ pitch at a speed of 1000 feet per minute moves 1000 pieces per minute. If the article being moved will allow a 6″ pitch, the conveyor system will move 2000 parts per minute with the belt running at the same speed. Unfortunately, since plastic lugs are permanently welded to the belt, the pitch of the belt cannot be easily changed. Therefore, a change in pitch requires that the belt be replaced by another belt with a different pitch.  
         [0006]     For the foregoing reasons, there is a need for a flight lug which can be easily removed from a conveyor belt for repositioning or replacement to reduce the labor cost and machine downtime associated with a change in pitch or to repair a conveyor system. Ideally, the flight lugs should be adapted for use with a wide range of article configurations and sizes.  
       SUMMARY OF INVENTION  
       [0007]     According to the present invention, a lug is provided for releasable attachment to a conveyor belt. The lug comprises a base having an upper surface, a lower surface and edge surfaces each extending between and interconnecting the upper surface and the lower surface of the base. First and second side walls are mounted to opposite edge surfaces of the base such that the base extends between and interconnects the side walls intermediate upper and lower ends of the side walls. A flange extends inwardly from adjacent the lower ends of each of the side walls, each flange defining a slot between the flange and the lower surface of the base for receiving an edge of the conveyor belt. The first side wall is pivotally attached to the base for movement relative to the base between a first position where the flange on the lower end of the first side wall is spaced a first distance from the flange on the lower end of the second side wall for allowing the belt to fit between the flanges, and a second position where the flanges on the side walls are spaced apart a second distance which is less than the width of the belt for capturing the belt in the slots between the side walls.  
         [0008]     Also according to the present invention, a conveying system is provided for transporting objects along a path of travel during operation of the conveying system. The conveying system comprises a frame and a drivable endless conveying belt supported on the frame for movement in a direction of the path of travel. The belt has an inner surface and an outer surface. The outer surface of the belt forms an object conveying surface and the inner surface of the belt includes longitudinally spaced teeth extending transversely to the path of travel. A plurality of flight lugs are releasably mounted at spaced intervals along the belt in the direction of the path of travel. Each lug comprises a base having an upper surface, a lower surface and edge surfaces extending between and interconnecting the upper surface and the lower surface of the base. First and second side walls are integral with opposite edge surfaces of the base such that the base extends between and interconnects the side walls intermediate upper and lower ends of the side walls. A flange extends inwardly from adjacent each of the lower ends of the side walls. Each flange defines a slot between the flange and the lower surface of the base for receiving an edge of the belt. The first side wall is pivotally attached to the base for movement relative to the base between a first position where the flange on the lower end of the first side wall is spaced a first distance from the flange on the lower end of the second side wall for allowing the belt to fit between the flanges, and a second position where the flanges on the side walls are spaced a second distance which is less than the width of the belt for capturing the belt in the slots between the side walls. The lug is positioned on the belt so that the flanges extending between the teeth on the inner surface of the belt. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]     For a more complete understanding of the present invention, reference should now be made to the embodiment shown in the accompanying drawings and described below. In the drawings:  
         [0010]      FIG. 1  is a perspective view of a portion of a conveyor system including several sets of conveyor belts and flight lugs secured to two of the belts according to the present invention.  
         [0011]      FIG. 2  is a perspective view of a flight lug according to the present invention.  
         [0012]      FIG. 3  is a perspective view of the flight lug shown in  FIG. 2  in a locked position.  
         [0013]      FIGS. 4 and 5  are bottom and top plan views, respectively, of the flight lug shown in  FIG. 3 .  
         [0014]      FIGS. 6 and 7  are side elevational views of the flight lug shown in  FIG. 3 .  
         [0015]      FIGS. 8 and 9  are rear and front elevational views, respectively, of the flight lug shown in  FIG. 3 .  
         [0016]      FIG. 10  is a top perspective view of a portion of a conveyor belt with two flight lugs in position on the belt according to the present invention with one of the flight lugs in an unlocked position and the other flight lug in a locked position.  
         [0017]      FIG. 11  is a bottom perspective of the conveyor belt and flight lugs shown in  FIG. 10 .  
         [0018]      FIG. 12  is a rear elevational view of another embodiment of a flight lug according to the present invention.  
         [0019]      FIGS. 13 and 14  are top plan and rear elevational views, respectively, of yet another embodiment of a flight lug according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     Certain terminology is used herein for convenience only and is not to be taken as a limitation of the present invention. For example, words such as “upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe the configuration shown in the FIGS. Indeed, the components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise.  
         [0021]     Referring now to the drawings, wherein like reference numerals designate corresponding or similar elements throughout the several views, there is shown in  FIG. 1 a  portion of an exemplary conveyor system generally designated at  20 . The conveyor system  20  comprises three series of continuous flexible conveyor belts which pass over pairs of toothed sprockets, none of which are visible in the  FIG. 1 . The conveyor belts are polyurethane belts with cord reinforcements, as is conventional. A first series of parallel belts  22  and a third series of parallel belts  24  are at the right and left most portions of  FIG. 1 , respectively. These belts include a urethane foam upper surface to provide a tacky grip. A second series of parallel belts  26  run between the first and third series of belts  22 ,  24 . The three series of conveyor belts  22 ,  24 ,  26  run on a flat bed frame  28  having longitudinal grooves into which the belts fit. The belts move in the direction of a path of travel denoted by a reference arrow in the  FIG. 1 . The conveyor system  20  can be an indexing or continuous conveyor system.  
         [0022]     A plurality of flight lugs  40  are positioned along two of the second series of conveyor belts  26  and protrude upwardly from the upper surface of the belts  26 . The lugs  40  are disposed in longitudinal spaced relationship on the conveyor belts  26  thus forming a series of flights along a portion of the length of the conveyor system  20 . The details of each lug  40  and its attachment to the belts  26  are described below.  
         [0023]     A source of supply of articles (not shown) is disposed adjacent the upstream end  32  of the conveyor system  20 . In the exemplary conveyor system  20  shown in  FIG. 1 , the articles are substantially flat, sleeve-type paperboard cartons  42  supplied from a carton magazine. The conveyor system  20  moves in synchronized relationship with the delivery of cartons  42  from the magazine. The cartons  42  are fed one at a time onto the first series of conveyor belts  22  moving in the direction of the path of travel. The first series of belts  22  are moving faster than the second series of conveyor belts  26  so that a carton  42  is accelerated by the first series of belts  22  onto the second series of belts  26 . The lugs  40  on the second series of belts  26  flip into position between adjacent cartons  42  such that the cartons are received within the flights defined by the lugs  40 . Two cartons  42  are shown in  FIG. 1  as received within their respective flights on the second series of belts  26 . The front edge of the cartons  42  engage the lugs  40  for positioning the cartons  42  squarely on the belts. The third series of conveyor belts  24  move at the same speed as the second series of belts  26 . The third series of belts  24  pick up the cartons  42  with the help of a vacuum source holding the cartons  42  to the belts and moving the cartons  42  along the conveyor system  20  in the direction of the path of travel. It is understood that the conveyor system  20  could also be designed such that the lugs  40  come from behind the cartons  42  and engage the trailing edge of the cartons  42 .  
         [0024]     It is understood that the conveyor system shown in  FIG. 1  and described above is merely exemplary of one application of the flight lug according to the present invention. The applicants do not intend to limit the present invention to only this conveyor system. Numerous other applications are contemplated. For example, the flight lugs could be adapted to receive other devices for engaging and transporting articles along a conveyor system. In this embodiment of the present invention, therefore, the flight lugs need not engage the articles to be moved by the conveyor system.  
         [0025]     A flight lug  40  according to the present invention is shown in  FIGS. 2-9 . The flight lug  40  is generally chair-shaped, including a generally planar front wall  44  and opposed side walls  46 ,  48 . A generally planar base  50  extends perpendicularly from the lower edge of the front wall  44  and is connected between the front wall  44  and the side walls  46 ,  48 . The major portion of the base  50  is rectangular in plan view ( FIGS. 4 and 5 ) with a central tab  52  extending from an edge of the base  50  opposite the front wall  44 .  
         [0026]     The flight lug  40  is preferably formed in one piece from a rigid durable high molecular weight plastic material such as HDPE. HDPE offers the benefits of ease of machinability coupled with a relatively low cost. Other suitable plastics include DELRIN, nylon and the like. The lug  40  may also be formed from natural or synthetic rubber or other elastomer such as, for example, ethylene, propylene, dieneter-polymer elastomer. Other suitable durable, rigid materials could also be used for the flight lugs  40  as long as the material is strong enough to avoid breaking or stress during operation. Moreover, the flight lug  40  may be of different heights and shapes to accommodate various article sizes and shapes.  
         [0027]     Referring to  FIGS. 6-9 , the lower ends of the side walls  46 ,  48  extend downwardly from the base  50  and terminate in inwardly turned flanges  54 ,  56 . Opposed parallel slots  58 ,  60  are defined by the lower ends of the side walls  46 ,  48 , the lower surface  51  of the base  50  and the flanges  54 ,  56 . The slots  58 ,  60  provide means for attaching the flight lug  40  to a conveyor belt, as will be described more fully below.  
         [0028]     As best seen in  FIGS. 3 and 8 , a groove  62  is formed in the upper surface  53  of the base  50  at the junction of one of the side walls  46  and the base  50 . The side wall  46  is also not connected to the adjacent edge of the front wall  44  ( FIG. 6 ). This configuration allows the side wall  46  to pivot about an axis at the junction of the side wall  46  and base  50 . One position of the pivoting side wall  46  is shown in  FIG. 2  where the side wall  46  is angled inwardly toward the opposite side wall  48 .  
         [0029]     Referring to  FIGS. 2, 3  and  8 , a detent  64  is integrally formed on the inner surface  45  of the front wall  44 . The detent  64  comprises a transverse ramp extending furthest away from the inner surface  45  of the front wall  44  at the edge of the front wall  44  adjacent the pivoting side wall  46 . The detent  64  is sized and positioned such that when the pivoting side wall  46  is rotated in the direction of the arrow in  FIG. 2  to a second position where the side wall  46  is perpendicular to the base  50 , the side wall  46  snaps into place behind the detent  64 .  
         [0030]     In use, a flight lug  40  according to the present invention is releasably attached to a conveyor belt by moving the pivoting side wall  46  from the first position, where the side wall  46  is angled inwardly toward the opposite side wall  48  ( FIG. 2 ), to the second locked position, where the pivoting side wall  46  is behind the detent  64  ( FIG. 3 ). This process is shown in  FIGS. 10 and 11 . Two flight lugs  40  are shown on a portion of a conveyor belt  26 . The flight lug in the lower portion of  FIGS. 10 and 11 , generally designated at  40   a , is in the second, or locked, position, and the other flight lug, generally designated at  40   b , is in the first, or unlocked, position.  
         [0031]     The first step in attaching the flight lug of the present invention to the conveyor belt  26  is to slip the belt into the slot  58  formed at the lower end of the rigid, non-pivoting side wall  48  such that the flange  56  fits between two of the teeth  27  on the inner surface  66  of the belt  26 . Next, with the base  50  of the lug  40  held firmly against the upper surface of the conveyor belt  26 , the pivoting side wall  46  is manually pushed outwardly. Outward movement of the pivoting side wall  46  causes the belt  26  to slip into the slot  60  on the pivoting side wall  46  with the flange  54  fitting between the same two teeth  27  on the belt  26  as the opposite flange  56 . The user continues to push the pivoting side wall  46  outwardly until the wall slides over the detent  64 . Once the side wall  46  is past the thicker end of the detent  64 , the side wall  46  snaps into position thus locking the lug  40  on the belt  26 .  
         [0032]     When the flight lug  40  is the locked position on the conveyor belt  26 , the belt  26  is captured in the slots  58 ,  60 , which are sized and shaped to snuggly receive the conveyor belt  26  so that the lug  40  is firmly fixed to the belt  26 . The flanges  54 ,  56  extend only partially across the inner surface  66  of the belt  26  thereby leaving space between the teeth  27  for engagement by the sprockets (not shown). The flat lower surface  51  of the base  50  of the lug  40  is against the upper surface of the conveyor belt  26  for further supporting the lug  40 . This configuration minimizes tortional bending or twisting of the lug  40  during operation. The front wall  44  is generally perpendicular to the conveyor belt  26  and has an outer surface  47  facing in what could be a direction of travel of the conveyor belt  26  for engaging articles to be moved.  
         [0033]     The flight lug  40  is removed from the conveyor belt  26  by reversing the procedure described above. That is, the pivoting side wall  46  is first moved away from the front wall  44  until the inner edge of the side wall  46  clears the detent  64 . This releases the side wall  46 , which is then pivoted inwardly toward the rigid side wall  48  so that the conveyor belt  26  slips out of the slot  60 . The lug  40  is then moved slightly transversely of the conveyor belt  26  for freeing the belt from the other slot  58  at the lower end of the rigid wall  48 . The lug  40  is then lifted off of the conveyor belt  26  and may then be reattached at another desired position.  
         [0034]     Another embodiment of a flight lug  40  according to the present invention is shown in  FIG. 12 . In this embodiment, there is no detent  64 . As described above, it is presumed that a device (not shown) for engaging and transporting articles along a conveyor system may be attached to the lug  40 . Such device could also securely position the pivoting side wall  46  in the locked position. The device may a simple clip, or the device may be specifically designed for movement of a particular article. The latter is sometimes referred to in the art as a fill-block, which can vary in size as needed for various article size groupings and configurations.  
         [0035]     Still another embodiment of a flight lug  40  according to the present invention is shown in  FIGS. 13 and 14 . In this embodiment, there is no detent  64  for holding the pivoting side wall  46  in the locked position. Instead, two opposed posts  90  extend inwardly toward one another from the side walls  46 ,  48 . A coil spring  92  fits over the posts  92  and between the side walls  46 ,  48 . The spring  92  functions to bias the pivoting side wall  46  into the locked position. The lug  40  may be moved to the unlocked position by simply pinching the side wall  46 ,  48 , which moves the pivoting side wall inward allowing the lug  40  to be removed form a conveyor belt.  
         [0036]     It is understood that other embodiments of the present invention are possible, including an embodiment wherein both of the side walls  46 ,  48  are pivotally mounted to the base  50 . This configuration of the flight lug  40  would obviate the need for the front wall  44  in some applications.  
         [0037]     A flight lug according to the present invention has a number of advantages, including the ability to be quickly and easily removed and selectively positioned along the length of the conveyor belt without tools or fasteners. This allows a new pitch to be set on the same belt to accommodate articles of different sizes and shapes. No disassembly of the conveyor system is required and no prolonged work stoppage is necessary. Thus, costs associated with conventional flight lugs are reduced through reduced labor and minimized machine downtime during set-up and change over procedures and repair.  
         [0038]     Although the present invention has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that we do not intend to limit the invention to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. For example, the lug has a number of applications including attaching various articles, such as hanging buckets, to any moving conveying system,. Accordingly, we intend to cover all such modifications, omission, additions and equivalents as may be included within the spirit and scope of the invention as defined by the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.