Sideguards are commonly used with belt conveyors to prevent conveyed materials such as aggregates, vegetables, and fruits from falling off the sides of the belt. Typically, a sideguard is positioned near both sides of each belt row. The leading edge of a sideguard is usually laterally offset from the trailing edge. In this way, the leading edge of a sideguard of a trailing row does not interfere with the trailing edge of a sideguard of a leading row. In modular plastic belts, the sideguards are typically angularly disposed from one edge to the other so that the sideguards of consecutive rows form a continuous wall of sideguards overlapping fan-like. When a belt with sideguards bends backwards, such as when entering an incline, the overlap of consecutive sideguards and, consequently, the force exerted by the overlapping sideguards on each other, increase. To endure the increased force during backflexing without damage, sideguards are usually designed to be thin and therefore resilient. But thin sideguards are easier to break with equipment, such as hoses for cleaning, that may come into contact with the sideguards during belt operation or maintenance.

In modular plastic conveyor belts, sideguards are usually supplied as attachments to belts. The sideguards snap into belt structure or are connected to the hinge rods joining consecutive rows of belt modules together. But these connections are often fairly loose.

Although excess play in the connections provides some relief to the bacldlexing problem, loose connections prevent consecutive sideguards from meshing well and therefore leave gaps through which conveyed articles can escape. Furthermore, these connection schemes are generally insufficiently sturdy to accommodate other than thin, lightweight sideguards.

Thus, there is a need for a plastic conveyor belt module with durable sideguards that can handle backflexing of a conveyor belt.

Summary These needs and others are satisfied by a plastic conveyor belt module embodying features of the invention. The module includes a plastic module body that extends longitudinally from a first end to a second end and transversely from a first side to a second side. The module body further includes a top surface extending longitudinally from the first end to the second end and transversely from the first side to the second side. A sideguard upstanding from the top surface forms a wall that extends generally longitudinally from a first edge at a first end of the module body to a second edge at a second end. The first edge and the second edge of the sideguard are generally perpendicular to the top surface. The sideguard is also unitarily molded with the plastic module body. These modules and other modules devoid of sideguards can be arranged together to construct a modular conveyor belt with the sideguards forming a continuous wall along the length of the belt.

Brief Description of the Drawings These and other features, aspects, and advantages of the invention are better understood by reference to the following description, appended claims, and accompanying drawings, in which: FIGS. lA-l C are top plan, front elevation, and side elevation views of a plastic conveyor belt module with a unitary sideguard embodying features of the invention; FIGS. 2A and 2B are cross section views of the sideguard of FIG. 1 viewed along lines IIA-IIA and IIB-IIB of FIG. 1C ;

FIG. 3 is an isometric view of a portion of a modular plastic conveyor belt constructed of the belt modules of FIG. 1 on a flat conveying path ; FIG. 4 is an isometric view of the conveyor belt of FIG. 3 on a backflexing conveying path; and FIG. 5 is an isometric view of a conveyor belt as in FIG. 3, but including belt modules with unitary flights as well as sideguards.

Detailed Description A conveyor belt module embodying features of the invention is shown in FIG. 1. The module 10 includes a module body 12 having a top surface or conveying deck 14 and an opposite bottom surface 15. The module extends longitudinally from a first end 16 to a second end 17. The module extends transversely in a lateral direction from a first side 18 to a second side 19. First and second sets of hinge eyes 20,21 are spaced apart along the first and second ends of the module body. Holes 22 through the hinge eyes admit a hinge rod for interconnecting modules together into a conveyor belt. Retention structure 24 in the outermost hinge eye of the module can be used to capture the head of a hinge pin and retain it in place.

Upstanding structure in the form of a sideguard 26 forming a vertical wall extends upward from the deck at a lateral position spaced inward of the outside of the module. The sideguard is unitarily formed with the module body preferably in an injection molding process. The module is preferably molded out of a thermoplastic material, such as polypropylene, polyethylene, acetal, or a composite resin that may include fibers or other additives.

Leading and trailing edges 28,29 of the sideguard preferably extend perpendicularly upward from the deck at one of the hinge eyes 20,21. Thus, viewed from the side of the

module, the sideguard has a rectangular profile with a flat top 30. (To make the module easier to remove from the mold during manufacturing, the leading and trailing edges are preferably <BR> <BR> angled slightly off perpendicular from the deck. ) As can be seen in FIGS. 1 A and 1B, as well as FIGS. 2A and 2B, the leading and trailing edges are laterally offset. By extending out onto the hinge eyes at least as far as the centerline of the rod holes 22, the sideguard can form a wall with the sideguards of leading and trailing rows of modules in a conveyor belt. The lateral offset allows the sideguards of consecutive rows to mesh without interference.

The sideguard can be considered as a pair of laterally offset trapezoidal plates 32,33 joined along imaginary portions 34', 35'of confronting lateral faces 34,35. The long base 41 of each trapezoid extends longitudinally along the deck. The generally vertical leading and trailing edges 28,29 of the sideguard form straight edges of the trapezoidal plates. The opposite sides 36, 37 of each plate are angled obliquely from the plane of the deck. Thus, the sideguard forms wedge-or V-shaped indentations 38, 39 along the leading and trailing edges on opposite sides of the sideguard. The junction 40 between the two plates is in the shape of a trapezoidal prism with a longitudinal base 41 and a pair of angled edges 36,37 converging toward each other with distance above the deck. Parallel lateral faces of the junction 42,43 define a central thickness of the sideguard. Flush extensions 44,45 of the two faces terminate in the leading and trailing edges 28,29. The lateral thickness of the extensions is less than the central thickness of the sideguard by an amount corresponding to the lateral depth of the wedge-shaped indentations. The junction between the two plates can be considered a connecting portion between two plate portions of the sideguard. As shown in FIG. 2, the longitudinal extent of the connecting portion 46 decreases with distance above the deck.

FIG. 3 shows a portion of a conveyor belt constructed of sideguard modules as in FIG. 1. The belt 47 includes short edge modules 48 (like the module in FIG. 1), long edge modules 49, and interior modules 50 without sideguards. The short edge modules differ from

the long edge modules only in that the long edge modules have more hinge eyes and are wider than the short edge modules. Any number of interior modules can be added to construct a belt of any desired width in a bricklay pattern. Each row of modules is connected to leading and trailing rows by a hinge rod 52 inserted in a passageway formed by the aligned holes 22 of interleaved hinge eyes of adjacent rows. The sideguards are indented inward of the outside edge of the belt, leaving an indent 53 along the sides. The indent provides the edges of the belt with flat bearing surfaces that can ride on support shoes in the conveyor returnway.

When the belt is operated on a level conveying path, the sideguards of consecutive rows overlap slightly because the leading and trailing edges 28,29 rise generally perpendicularly from the deck at positions at or just beyond the center lines 54 of the rod holes. The lateral offset of the leading and trailing edges allows consecutive side guards to overlap without interfering with each other. The wedge-shaped indentations 38, 39 provide room for the sideguards to collapse if the belt has to backflex as shown in FIG. 4. When the belt backflexes, the trailing edge 29 of a leading module moves along the wedge-shaped indentation until it comes in contact with the leading angled, or slanted, edge 36 of the trailing sideguard on the interior side of the belt. A similar meeting of the corresponding edges of the sideguard occurs on the exterior side of the belt. The angle of the angled edge determines the amount of backflexing that can be accommodated. In this way, the belt can backflex without lateral forces being exerted between consecutive flights. This allows the flights to be made thick and, therefore, durable.

Another version of a belt module with unitary sideguards is illustrated in the belt segment of FIG. 5. Like the belt segment of FIG. 3, the belt segment 60 of FIG. 5 includes short edge modules 48, long edge modules 49, and flat-top interior modules 50. But the belt also includes flighted interior modules 62 and short and long flighted edge modules 64,65.

The short and long flighted edge modules have a flight 66 unitarily molded with the module

body. The flight extends upward from the deck of the module and is preferably perpendicularly attached to the interior wall of the sideguard 26. A belt constructed of these modules, as shown in FIG. 5, divides the conveyor into a series of individual moving compartments 68 bounded on four sides by the walls formed by the flights and sideguards.

Although the invention has been described in detail with reference to a couple of preferred versions, other versions are possible. For example, the top of the sideguards does not have to be flat. As another example, the sideguard could be positioned closer to the edge of the belt then the indented sideguards shown in detail. As yet another example, the sideguards of consecutive modules do not have to overlap or extend onto the hinge eyes. In some application, a gap between sidewalls may be acceptable. So, as these few examples suggest, the scope of the invention as defined in the claims, is not meant to be limited to the versions described in detail.

What is claimed is: