WO1999062795A1

WO1999062795A1 - Sheet stabilizing powered conveyor

Info

Publication number: WO1999062795A1
Application number: PCT/US1999/012341
Authority: WO
Inventors: David E. Suica; Alan L. Abel; Thor A. Schmidt
Original assignee: United Pentek, Inc.
Priority date: 1998-06-03
Filing date: 1999-06-03
Publication date: 1999-12-09
Also published as: AU4330799A

Abstract

A conveyor system including a plurality of adjacent conveying sections extending longitudinally in a downstream direction. Each conveying section includes a plurality of laterally spaced modular conveying units supported for independent lateral positioning. Each conveying unit includes a continuous belt wrapped around first and second rotatably mounted end rolls. Each of the first and second end rolls are positioned in spaced relation to and mounted independently of the first and second end rolls of every other conveying unit. A propelling member is supported intermediate the first and second end rolls and drives the belt in motion.

Description

SHEET STABILIZING POWERED CONVEYOR

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to conveyors, and more particularly, to live conveyor systems for transporting loads over a series of driven conveying belts. 2. Description of the Prior Art

Live conveyor systems which transport loads without gravity assistance are generally well known in the art. One type of conventional live conveyor system is disclosed in U.S. Patent No. 4,293,065, which is assigned to the assignee of the present invention. The conveyor system disclosed in this patent includes a plurality of load-carrying rollers supported for rotation and arranged above an endless driving means. The endless driving means includes an upper frictional contact pass for engaging the load-carrying rollers wherein movement of the endless driving means results in rotation of the load-carrying rollers such that loads supported on the rollers are carried downstream. A plurality of conveying zones extend longitudinally along the length of the conveyor wherein the endless driving means is vertically movable into and out of engagement with the load-carrying rollers in each individual zone. As such, the load-carrying rollers in each zone may be independently driven in rotation whereby loads may be accumulated within the various zones extending along the length of the conveyor.

One of the problems associated with such traditional roller conveyor systems occurs during the transport of sheet product. This problem, commonly known as "sheet walk", occurs when a bottom sheet is displaced with respect to the remaining sheets in a stack. Sheet walk may be contributed to the fact that the leading edge of the bottom sheet of a stack engages a vertical surface of each load- carrying roller as the stack is transported downstream. Each load-carrying roller essentially pushes against the bottom sheet in a direction opposite to the movement of the stack such that the bottom sheet begins to lag behind the remaining sheets in the stack. As such, the entire stability of the stack is compromised, often resulting in serious skewing, misalignment, or collapsing of the stack at it reaches a downstream end of the conveyor. Additionally, contact between leading edges of the sheets and successive rollers may damage the sheets, resulting in their rejection as defective products.

Attempts to solve the sheet walk problem of roller conveyor systems have resulted in the substitution of an endless conveying band for the load-carrying rollers. Typically, the conveying band comprises a single loop of flat-link chain which passes around drive and tensioning rollers positioned at opposing ends of the system. The chain conventionally extends longitudinally along a center axis of the conveyor system and separates a pair of load support surfaces. Various portions of the conveying chain are vertically moveable to a position above the adjacent support surfaces for selectively engaging and transporting loads in contact therewith. An example of a conventional endless chain conveyor system is disclosed in U.S. Patent No. 4,149,626.

Several problems are inherent with the above described prior art chain conveyor systems. For example, conveying chains have outwardly extending protuberances which often mark or damage the'bottom sheet in a stack. In many instances, the damage may propagate up through the stack thereby damaging additional sheets. Additionally, typical conveying chains are made of metal such that their operation is noisy and requires extensive regular maintenance, including the use of expensive lubricants.

The above described endless chain conveyor system has limited flexibility in selectively controlling the transport speeds of different loads since the chain travels at a uniform speed along its length. Different loads along the length of the conveyor must either be at rest or move at the same speed as other loads on the chain. A conveyor system having independently controllable conveyor zones is disclosed in U.S. Patent No. 3,187,878. Each conveyor zone includes a plurality of laterally spaced belts wrapped around a common pair of rolls. The belts in each adjacent conveyor zone are overlapping such that the upper runs of the belts in one zone are overlapping with respect to the upper runs of the belts in an adjacent zone. Prior art conveyor systems typically provide little, if any, flexibility in allowing expansion of the system in either lateral width or longitudinal length. Essentially, each conveyor system has to be installed with a defined width and length which may not be readily modified. The overall operative dimensions of the conveyor system cannot be altered without effectively requiring the construction of an entirely new conveyor system.

Accordingly, there is a need for a conveyor system having a plurality of longitudinally overlapping belts for eliminating instability or sheet walk of sheet product transported therealong while also providing for a plurality of independently controllable accumulating conveying zones. Additionally, there is need for such a conveyor system having a modular frame for providing flexibility in expanding its effective width or length.

SUMMARY OF THE INVENTION The present invention provides a conveyor system for transporting loads and, more particularly, for transporting stacks of sheet product with improved stability. The conveyor system also facilitates efficient maintenance and flexibility in modifying its length or width.

The conveyor system of the present invention includes a plurality of adjacent conveying sections extending longitudinally, or in the machine direction, from an upstream end to a downstream end. Each conveying section includes a plurality of laterally, or cross-machine, spaced modular conveying units. The conveying units of each section are supported on a plurality of laterally extending crossties which, in turn, are supported on a floor surface.

Each conveying unit includes a continuous belt wrapped around first and second rotatably mounted end supports which define first and second ends of a belt path of travel. Each belt includes upper and lower runs separated by the end supports. The first and second end supports of each conveying unit are rotatably supported within a belt support frame which, in turn, is supported for selective lateral movement along the plurality of crossties.

A propelling member is supported intermediate the first and second end supports and engages the lower run for driving the endless belt in motion. The propelling member of each conveying unit is operably connected to a laterally extending drive shaft. The drive shaft is driven in rotation by an electric gear motor preferably positioned laterally proximate the longitudinal axis of the conveying section.

The belt path of each conveying unit is laterally offset from the belt paths of the conveying units of each adjacent conveying section. Additionally, the belt path of each conveying unit longitudinally overlaps with the belt paths of the conveying units of each adjacent conveying section. More particularly, each end support preferably includes upstream and downstream end surfaces and a laterally extending center axis, wherein the center axes of the second end supports of each conveying section are positioned longitudinally downstream from the upstream end surfaces of the first end supports of an adjacent downstream conveying section. Therefore, it is an object of the present invention to provide a conveyor system providing for improved stability of sheet product conveyed thereon by eliminating load-carrying rollers.

It is a further object of the present invention to provide such a conveyor system for eliminating sheet walk of transported sheet product. It is another object of the present invention to provide a conveyor system having a longitudinally continuous conveying surface for providing uninterrupted transport of loads along the length of the conveyor.

It is a further object of the present invention to provide such a continuous conveying surface defined by a plurality of longitudinally overlapping belts.

It is an additional object of the present invention to provide such a conveyor system including a belt support frame facilitating maintenance of the conveyor system.

It is still another object of the present invention to provide such a belt support frame which facilitates simple and efficient assembly of the conveyor system.

It is a further object of the present invention to provide a conveyor system of modular construction such that the width and length of the conveyor system may be readily modified. It is a further object of the present invention to provide such a conveyor system of simple and cost effective design.

It is another object of the present invention to provide a conveyor system having a plurality of independently controllable zones for accumulating loads.

It is yet another object of the present invention to provide a conveyor system having direction reversible belts.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a top plan view in partial schematic of a conveyor system of the present invention; Fig. 2 is a partial top plan view of a conveying section of the conveyor system of Fig. 1, with the protective covers removed; Fig. 3 is a side elevational view thereof;

Fig. 4 is a perspective view of a first end of a modular conveying unit of the present invention with a partial cutaway of the belt; Fig. 5 is a perspective view of a second end of the modular conveying unit of Fig. 4 with a partial cutaway of the belt;

Fig. 6 is a side elevational view of the tensioning device of a modular conveying unit of the present invention taken along line 6-6 of Fig. 2;

Fig. 7 is a detail side elevational view, in partial schematic, illustrating the longitudinal overlap of adjacent conveying sections; and

Fig. 8 is a perspective view of an alternative embodiment of a modular conveying unit of the present invention with a partial cutaway of the belt and belt support frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to Fig. 1 , a conveyor system 10 constructed in accordance with the preferred embodiment of the present invention is shown as including a plurality of conveying sections 12, 14 and 16 extending along a longitudinal axis 17 between upstream and downstream ends 18 and 20. While Fig. 1 illustrates first, second and third adjacent conveying sections 12, 14 and 16, respectively, it may be appreciated that any number of conveying sections may be utilized, depending upon the particular requirements of the conveyor system 10. As detailed below, the conveyor system 10 of the present invention provides great flexibility in allowing for the simple alteration of its effective length or width.

Each conveying section 12, 14 and 16 includes a plurality of laterally spaced conveying units 22 extending longitudinally in overlapping relation with at least some of the conveying units 22 of adjacent conveying sections 12, 14 and 16. Protective covers 24, preferably comprising sheet metal, are fixed between laterally adjacent conveying units 22 to shield personnel from moving parts positioned therebelow. In the following description, each individual conveying unit 22 will be identified by a reference numeral in combination with a lowercase letter. Turning now to Figs. 2 and 3, conveying section 14 is illustrated in greater detail. While conveying sections 12 and 16 preferably have structures similar to conveying section 14, it may be appreciated that the dimensions and number of conveying units 22 of each conveying section 12, 14 and 16 may be varied. Each conveying unit 22 is elevated in spaced relationship to a floor 26 by a plurality of laterally extending crossties 28. Each crosstie 28 is comprised of hollow rectangular steel and is fixed to the floor 26 by height adjusting devices 30. The height adjusting devices 30 include a plate 32 fixed to one of the crossties 28 and rotatably supporting an adjusting nut assembly 34. An adjusting screw 36 is threadably received within the nut assembly 34 and is supported by the floor 26. As may be readily appreciated, rotation of the adjusting nut assembly 34 causes vertical movement of the plate 32 and crosstie 28 relative to the floor 26.

As illustrated in Figs. 2, 4 and 5, the upper surfaces 38 of at least a pair of crossties 28 are formed with a plurality of apertures 40 in equal spaced relation to each other and extending the entire length of the crosstie 28 in a lateral direction to the conveyor system 10. It may be appreciated that longitudinally extending connecting ties (not shown) may interconnect selected crossties 28 for providing additional structural support to the conveying sections 12, 14 and 16.

With further reference to Figs. 3-5, each conveying unit 22 includes a belt support frame 44 including an upper planar surface 46 supported above the plurality of crossties 28. The upper planar surface 46 extends between first and second ends 48 and 50 of the frame 44 and is preferably provided by hollow rectangular steel supported by a plurality of brackets 54. The brackets 54 are preferably L-shaped and include an elongated slot 56 through which bolts 58 may pass to secure the belt support frame 44 to a plurality of crossties 28. The bolts 58 are then passed through selected ones of the apertures 40 and are secured in place by nuts (not shown) in a manner as is known in the art. As may be readily appreciated, the plurality of apertures 40 formed within the crossties 28 allow for the simple, rapid and efficient repositioning of each modular conveying unit 22 in a lateral position along the plurality of crossties 28. Further, the securing arrangement of the modular conveying units 22 provides for the easy insertion or deletion of conveying units 22 to either increase or decrease the overall operating width or length of the conveying system 10.

First and second end supports, preferably end rolls 60 and 62, are each rotatably supported by a pair of arms 64 proximate the first and second ends 48 and 50 of the frame 44. It should be noted that sprockets, gears, pulleys, sleeves, and similar components may be readily substituted for the rolls 60 and 62. A continuous belt 68 is wrapped around the first and second end rolls 60 and 62 along a longitudinally extending belt path 70 having opposing first and second ends coinciding with the first and second end rolls 60 and 62. The belt 68 includes upper and lower runs 72 and 74 separated by the end rolls 60 and 62 wherein the upper run 72 extends above the upper planar surface 46. The belt 68 is preferably of a smooth flexi-mechanical design consisting of a plurality of modular molded thermoplastic links 76 hinged together at pivot points 77 to form a flat conveying surface 78. However, similar belts including those of a seamless continuous design may be readily substituted therefor. In the preferred embodiment of the present invention, the belt 68 comprises Series 1400 flat top modular plastic conveyor belt available from Intralox of New Orleans, Louisiana. As illustrated in Figs. 4 and 5, each link 76 of the belt 68 preferably includes a pair of tracking tabs 79 extending inwardly therefrom. A pair of longitudinally extending, laterally spaced guide rails 80 are supported by the upper planar surface 46 of the belt support frame 44. The tracking tabs 79 of the belt 68 are received between the guide rails 80 to assist in the proper tracking of the belt 68 along the belt path 70 while the inner surface 81 of the outer edges of the belt 68 ride on top of the guide rails 80 thereby reducing frictional forces acting against movement of the belt 68 (Fig. 3). The end rolls 60 and 62 preferably include a pair of laterally spaced annular flanges 82. In a manner similar to the guide rails 80, the tabs 79 of the belt 68 are received between the annular flanges 82 to assist in proper tracking of the belt 68. The lower run 74 of the belt 68 extends longitudinally below the upper planar portion 46 and is operably connected to a drive mechanism 84 and guided through a cooperating tensioning device 86. The drive mechanism 84 preferably includes a propelling member 88 which is operably connected to a laterally extending drive shaft 90 passing perpendicularly through each frame 44 and rotatably supported by a conventional bearing 91 (Fig. 6).

The propelling member 88 preferably comprises a split sprocket including a plurality of teeth 92 engaging the belt 68 along the lower run 74 intermediate the end rolls 60 and 62. The split sprocket 88 further includes portions 94 and 96 which may be dis-assembled from around the drive shaft 90. The portions 94 and 96 of the split sprocket 88 are attached around the drive shaft 90 by the use of a pair of bolts 98. The split sprocket 88 facilitates ease of installation and removal by eliminating the necessity of passing the sprocket 88 over an end of the drive shaft 90. The sprocket 88 preferably comprises a series 1400 18 tooth sprocket available from Intralox, Inc. of New Orleans, Louisiana. Referring further to Fig. 2, it should be noted that each drive shaft 90 preferably includes a plurality of drive shaft segments 98 connected by a mechanical self-aligning coupling 100 such that rotational movement of one drive shaft segment 98 is transferred to an adjacent drive shaft segment 98. The coupling 100 facilitates customization of the conveyor system 10 to a desired width without requiring the purchase of an entire new drive shaft 90. The coupling 100 preferably comprises Jaw Type Coupling Part No. LI 10H x 1- % available from Browning Manufacturing of Maysville, Kentucky, although similar couplings may be readily substituted therefor. An electric gear motor 102 is preferably disposed centrally in a lateral direction between the conveying units 22 and drives the drive shaft 90 in rotation. The motor 102 may be fixed to a mounting plate 103 extending between a pair of crossties 28. While the motor 102 preferably comprises Model No. KAF47DT9054BMHR available from Eurodrive of Troy, Ohio, similar drives may be readily substituted therefor.

Referring now to Figs. 3 and 6, the tensioning device 86 includes first and second tension rolls 104 and 106 positioned in spaced relation to each other and on opposite sides of the propelling roll 88 along the belt path 70. The tension rolls 104 and 106 are rotatably supported by axles 108 and 110 extending from the belt support frame 44 and fixed to adjustable plates 112 and 114. Each of the tension rolls 104 and 106 are independently vertically movable for engaging the lower run 74 and controlling the tension within the belt 68. More particularly, the axle 108 and 110 of each roll 104 and 106 is vertically moveable within a slot 116 and 118 formed within the frame 44. The adjustable plates 112 and 114 have elongated slots 120 and 122 for receiving bolts 124 and 126 which are secured to the frame 44. It may be readily appreciated that by loosening the bolts 124 and 126, the adjustable plates 112 and 114 and respective tension rolls 104 and 106 may be vertically moved.

Referring now to Figs. 2 and 7, each end roll 60 and 62 includes upstream and downstream surfaces 128 and 130 comprising part of the cylindrical outer surface for contacting the belt 68 as the rolls 60 and 62 rotate. A center axis 132 of each roll 60 and 62 extends in a lateral direction. As previously described, each end roll 60 and 62 is positioned in spaced relation to and mounted independently of every other first and second end roll 60 and 62. Since each respective end roll 60 and 62 is mounted independently of every other end roll 60 and 62, the belts 68 of each adjacent conveying section 12, 14 and 16 may be positioned in a longitudinally overlapping and laterally offset position.

More particularly, the center axis 132 of the second end roll 62 of the first conveying section 12 is preferably positioned longitudinally downstream from the upstream end surface 128 of the first support 60 of the second conveying section 14 while at the same time positioned longitudinally upstream from the downstream end surface 130 of the first support 60 of the second conveying section 14. In other words, since the end rolls 60 and 62 are independently mounted, the center axis 132 of the second end roll 62 of conveying section 12 may be longitudinally positioned anywhere between the upstream and downstream end surfaces 128 and 130 of the first support 60 of adjacent conveying section 14. The end rolls 60 and 62 of the second and third adjacent conveying sections 14 and 16 have similar relative positioning as the end rolls 60 and 62 of the first and second adjacent conveying sections 12 and 14.

The unique overlapping arrangement of the conveyor system 10 of the present invention permits for continuous travel of an article placed upon the conveying belts 68 from one conveying section 12, 14 and 16 to another while also providing for a simple modular construction. More particularly, each modular unit 22 is essentially self contained and only connected to other conveying units within its own conveying section 12, 14 and 16 through the drive mechanism 84.

Referring further to Fig. 1, sensor 134 is positioned proximate the downstream ends of each conveying section 12, 14 and 16. The sensor 134 preferably comprises photo optical switches for detecting articles positioned thereabove. The sensors 134 are in communication with a controller (not shown) wherein activation of the sensors 134 signal the controller which then instructs the motors 102 of each conveying section 12, 14 and 16 to operate in a predetermined manner as preferably provided by control software. The belts 68 of each conveying section 12, 14 and 16 may thereby be independently and selectively controlled. As such, the conveyor system 10 may have independently operable conveying sections 12, 14 and 16 such that loads may be accumulated in certain ones of the conveying sections 12, 14 and 16. Turning now to Fig. 8, an alternative embodiment of the conveying unit 22' of the present invention is illustrated as including a belt support frame 44' having a generally S-shaped cross section. The belt support frame 44' includes a horizontally extending flange portion 136 including mounting holes at opposing ends through which bolts 138 may pass to secure the belt support frame 44' to a plurality of crossties 28.

Integrally formed and positioned at an angle to the flange portion 136 is a substantially vertically extending web portion 140. At an approximate 90° angle to the web portion 140 and integrally formed therewith is a substantially horizontally extending upper planar portion 142. Extending downwardly in a substantially vertical direction is a side support portion 144. The belt support frame 44' defines an open belt positioning channel 146, the function of which will be described in greater detail below. A seamless continuous belt 68' is driven in motion by the propelling roll 88' which is connected to a propelling shaft 148. The propelling shaft 148 may be fixed to the propelling roll 88' in a conventional mechanical manner. A propelling pulley 150 is similarly fixed to an opposing end of the propelling shaft 148. At least one driving belt 152, preferably a V-belt, operably connects the propelling pulley 150 to a drive pulley 154. The drive pulley 154 is fixed to a drive shaft segment 98' for rotation therewith.

Prior art conveyors have typically required the disassembly of relatively complex frame assemblies in order to remove or install seamless belts. However, the belt support frame 44' of the present invention provides for a belt positioning channel 146 to facilitate the quick and easy removal and installation of continuous belts 68.

During removal of the belt 68', the tension rolls 104' and 106' are moved relative to the propelling roll 88' in a manner for reducing tension within the belt 68'. The lower run 74' may thereby be removed from the propelling roll 88' and tension rolls 104' and 106' and guided out through the belt positioning channel 146 defined by the belt support frame 44'. As such, the belt 68' is free to be removed from the conveyor system 10. During installation of the belt 68', the process is merely reversed, whereby the upper run 72' of the belt 68' is placed on top of the upper planer portion 142 and the lower run 74' is inserted through the belt positioning channel 146 and then wrapped around tension rolls 104' and 106' and propelling roll 88'. The tension rolls 104' and 106' are then moved relative to the propelling roll 88' such that the belt 68' is once again placed in tension.

Next the operation of a conveying section 12, 14 and 16 will be described in greater detail. During initial operation of the conveyor system 10, the controller instructs the motors 102 of each conveying section 12, 14 and 16 to operate in a predetermined manner. When each motor 102 is active, it rotates the plurality of drive shafts 90 associated with conveying section 12, 14, 16. Rotation of the drive shafts 90 causes similar rotation of the propelling members 88 thereby resulting in the movement of the belts 68. It should be noted that placement of the propelling members 88 intermediate the end rolls 60 and 62 permits reversible operation of the belts 68. Rotational movement of each propelling member 88 causes the belt 68 to move about the end rolls 60 and 62 and the tension rolls 104 and 106. As may be readily appreciated, movement of the upper run 72 of the belt 68 results in the transport of any article positioned in contact thereabove. As the articles travel downstream along the longitudinal axis 17 of the conveyor system 10, sensors 132 of the various conveying sections 12, 14 and 16 are triggered. Upon receiving a signal from one of the sensors 132, the controller instructs the motors 102 to operate in a predetermined manner to control spacing or accumulating of the articles.

While the forms of apparatus herein described constitute a preferred embodiments of this invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

Claims

-CLAIMS-

1. A conveyor system comprising: a plurality of laterally extending, longitudinally spaced crossties; a plurality of frames supported by and extending substantially perpendicularly to said crossties, each of said plurality of frames supported for independent lateral positioning relative to other said frames along said crossties; each of said frames including opposing first and second ends and an upper planar surface supported above said crossties and extending in a longitudinal direction between said first and second ends; first and second supports mounted proximate said first and second ends of each of said frames, said first and second supports of each of said frames positioned in spaced relation to said first and second supports of every other one of said frames; an endless belt supported by each of said frames and including upper and lower runs guided along a longitudinally extending belt path, said upper run extending above said upper planar portion of each respective said frame, said belt path including opposing first and second ends coinciding with said first and second supports; and a drive mechanism including a motor and a plurality of propelling members operably connected to said motor, each of said propelling members operably connected to one of said belts.

2. The conveyor system of claim 1 wherein said first and second supports comprise first and second rotatably mounted rolls.

3. The conveyor system of claim 2 wherein each of said first and second rolls includes a pair of annular flanges engaging said belt for maintaining said belt on said belt path.

4. The conveyor system of claim 1 wherein each of said frames further comprises a pair of longitudinally extending guide rails supported by said upper planar surface and engaging said belt for maintaining said belt on said belt path.

5. The conveyor system of claim 4 wherein said belt includes a plurality of guide tabs extending inwardly from said belt and cooperating with said guide rails for maintaining said belt on said belt path.

6. The conveyor system of claim 1 wherein each of said propelling members is operably connected to one of said belts intermediate said first and second supports.

7. The conveyor system of claim 6 wherein said drive mechanism further comprises a laterally extending drive shaft operably connecting each of said propelling members with said motor.

8. The conveyor system of claim 1 further comprising a tensioning device operably connected to said belt, said tensioning device including a pair of moveable tension rolls positioned along said belt path on opposite sides of said propelling member.

9 A conveyor system comprising: a first conveying section; a second conveying section disposed immediately downstream from said first conveying section; each of said first and second conveying sections including at least one longitudinally extending conveying unit, said at least one conveying unit including a frame having opposing first and second ends and an upper planar surface extending between said first and second ends, first and second supports rotatably mounted proximate said first and second ends, and an endless belt supported by said frame along a longitudinally extending belt path, said belt path having opposing first and second ends coinciding with said first and second supports; each of said first and second supports including upstream and downstream end surfaces and a laterally extending center axis, said first and second supports of each said conveying unit positioned in spaced relation to and .mounted independently of said first and second supports of every other said conveying unit; and wherein said second end of said belt path of said at least one conveying unit of said first conveying section longitudinally overlaps with and is laterally offset from said first end of said belt path of said at least one conveying unit of said second conveying section.

10. The conveyor system of claim 9 wherein said center axis of said second support of said at least one conveying unit within said first conveying section is positioned longitudinally downstream from said upstream end surface of said first support of said at least one conveying unit within said second conveying section.

11. The conveyor system of claim 10 wherein said center axis of said second support of said at least one conveying unit within said first conveying section is positioned longitudinally upstream from said downstream end surface of said first support of said at least one conveying unit within said second conveying section.

12. The conveyor system of claim 9 wherein said first and second supports comprise first and second rotatably mounted rolls.

13. The conveyor system of claim 12 wherein each of said first and second rolls includes a pair of annular flanges engaging said belt for maintaining said belt on said belt path.

14. The conveyor system of claim 9 wherein each of said frames further comprises a pair of longitudinally extending guide rails supported by said upper planar surface and engaging said belt for maintaining said belt on said belt path.

15. The conveyor system of claim 14 wherein said belt includes a plurality of guide tabs extending inwardly from said belt and cooperating with said guide rails for maintaining said belt on said belt path.

16. The conveyor system of claim 9 wherein each of said conveying sections further includes a plurality of laterally extending, longitudinally spaced crossties, each of said frames supported for independent lateral positioning relative to other said frames along said crossties.

17. The conveyor system of claim 9 wherein each said conveying unit further includes a propelling member operably connected to said belt intermediate said first and second supports.

18. The conveyor system of claim 17 wherein each said conveying section further includes a motor and a laterally extending drive shaft operably connecting each said propelling member to said motor.

19. A conveyor system comprising: a first conveying section; a second conveying section disposed immediately downstream from said first conveying section; each of said first and second conveying sections including a plurality of longitudinally extending, laterally spaced conveying units and a drive mechanism; each of said conveying units including a frame having opposing first and second ends and an upper planar surface extending longitudinally between said first and second ends, first and second supports rotatably mounted proximate said first and second ends, and an endless belt supported by said frame along a longitudinally extending belt path, said belt path having opposing first and second ends coinciding with said first and second supports; said first and second supports of each said conveying unit positioned in spaced relation to and mounted independently of said first and second supports of every other said conveying unit; said drive mechanism of each said conveying unit including a motor and a plurality of propelling members operably connected to said motor, each of said propelling members operably connected to one of said belts intermediate, said first and second supports; and wherein said second ends of said belt paths of said first conveying section longitudinally overlap with and are laterally offset from said first ends of said belt paths of said second conveying section.