Low profile conveyor for use in stretch wrapping operations

Abstract

Apparatuses and related methods of use are provided for the accumulation and wrapping of palletized loads with packaging material. In an exemplary embodiment of the present disclosure, the apparatus includes a low profile conveyor having non-powered conveying elements. In another embodiment, the apparatus is a stretch wrapping system for wrapping palletized loads. The stretch wrapping system may include a dispenser, a means for providing relative rotation between the dispenser and the load to be wrapped, a low profile conveyor, and a powered pusher assembly for moving the loads.

Description

This application claims priority under 35 U.S.C. § 119 based on U.S. Provisional Application No. 60/510,083, filed Oct. 10, 2003, the complete disclosure of which is incorporated herein by reference.

DESCRIPTION OF THE INVENTION

1. Field of the Invention

The present invention relates generally to methods and apparatuses for improving throughput of loads built on and transported with pallet trucks or “pallet jacks,” and more particularly, to providing methods for accumulating and wrapping order-picked loads.

2. Background of the Invention

High volume distribution warehouses such as WAL-MART®, HOME DEPOT®, and KROGER® utilize a relatively common process to order pick products and load trucks for individual stores. The term “order-picking” refers to the process of assembling one or more loads of products. The process begins with a computer generated “pick list” given to an individual often called a “picker.” The pick list may contain various different types of products, such as bottles, cartons, trays, boxes, bags, plastic totes, drums, yarn spools, or the like. These types of products are typically stacked in rows arranged upon a warehouse floor (see FIG. 1).

The picker loads two pallets onto a special battery powered pallet truck. The pallets are normally constructed with a top platform and at least a partial bottom platform, for example, the bottom platform may have spaces between the boards that form the bottom platform. The bottom platform supports the load when stacked on top of another load. The pallets are preferably constructed of wood, but alternatively may be made of plastic. Plastic pallets generally have a series of “legs” rather than a bottom platform (see FIG. 4). The pallets are typically constructed to industry standards, such as GMA standards (see FIG. 2). Alternatively, pallets may be leased from a supplier, such as Chep (see FIG. 3), a well-known pallet supplier.

The pallets are positioned on long forks of the pallet truck, one behind the other. The long forks are cantilevered off of the pallet truck, but may include collapsible wheels on their distal ends. The picker maneuvers the forks of the pallet truck through the fork holes (between the top and bottom platforms of the pallet or between the legs of the pallet) with the collapsible wheels in a raised position. After the forks extend through both pallets, the picker raises the pallets off of the ground by hydraulically lowering the collapsible wheels on the forks. The wheels pass through holes in the bottom platform and engage the ground, raising the pallets off of the ground.

The picker moves up and down aisles of the warehouse to locate the products on the pick list, pulling each product and placing it on one of the pallets. The process is repeated until the order is finished and a load is built. The resulting load can be homogenous, i.e., contain only one type of product, or non-homogenous, i.e., contain many different types of products of various sizes and shapes. Most often, the pull list requires the formation of non-homogenous loads, which may be very unstable.

After the load is built, it must be wrapped to contain the load for shipping. Various packaging techniques have been used to wrap a load of products for transportation, storage, containment and stabilization, protection and waterproofing. One system uses stretch wrapping machines to stretch, dispense, and wrap stretch packaging material around a load. Stretch wrapping can be performed as an inline automated packaging technique which dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Pallet stretch wrapping, whether accomplished by turntable, rotating arm, or rotating ring typically covers the four vertical sides of the load with a stretchable film such as polyethylene film. In each of these arrangements, relative rotation is provided between the load and a packaging material dispenser to wrap packaging material about the sides of the load.

When the load is complete, the picker delivers the load to a stretch wrapping area, typically containing a single stretch wrapping apparatus. Since only one load can be wrapped at a time, the two loads on the pallet truck must be separated. Normally, the picker drops the loads in a staging area or “parking lot” type area, where the load remains until it is picked up and transported to the stretch wrapping apparatus. The transport of the load from the staging area to the wrapping apparatus may be performed by a second worker, often called an “operator.” In addition to transporting the unwrapped load to the wrapping apparatus, the operator must set the unwrapped load aside, remove a wrapped load from the wrapping apparatus and move it to a loading staging area or directly to the truck, then place the unwrapped load on the wrapping apparatus, attach the leading end of the film to the load, and cut the film at the end of the wrapping cycle. This process involves multiple handling of the picked load due to the fact that the picker cannot directly place the load in a wrap zone of the stretch wrapping apparatus. In addition, more than one picker is generally working the warehouse floor, resulting in a large number of unwrapped loads sitting in the staging area, waiting to be transported to the stretch wrapping apparatus. Since typical wrapping stations wrap only one load at a time, the result is a bottleneck at the staging area waiting for the wrapping apparatus, thereby limiting efficiency.

While use of a conveyor to feed loads to the stretch wrapping apparatus seems an obvious solution, there have been several failed attempts to do so. Pallet trucks are unable to lift the loads high enough to place the picked loads onto a conventional, above-floor conveyor. Conveyors with lift tables or elevators are available to automate the process. However, such devices require a large amount of space and are mechanically complex and costly to maintain. In addition, conveyors have been placed in pits created in the floor to lower the conveyor to be approximately level with the floor. This requires a large amount of space and the permanent destruction of the floor. In addition, such a process is costly. Due to the widespread use of pallet trucks, manufacturers have not been able to successfully employ either powered or non-powered conveyors to sequence loads around a wrapping operation.

In light of these drawbacks, there is a need to reduce the complexity, time, and number of material handling steps necessary to move loads to and from a wrapping station in a simple, reliable, and inexpensive manner.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to methods and apparatuses for wrapping a palletized load with packaging material which provides advantages and obviates a number of problems in earlier methods and apparatuses for wrapping a load.

In accordance with an aspect of the present invention, a low profile conveyor includes at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements. The low profile conveyor further includes a base surface positioned between the conveyor elements.

Another aspect of the present invention includes a stretch wrapping system for wrapping palletized loads. The system includes a dispenser for dispensing packaging material, means for providing relative rotation between the dispenser and a load to wrap packaging material around the load, a low profile conveyor comprising at least two conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements. The low profile conveyor further includes a base surface positioned between the conveyor elements, and the stretch wrapping system further includes a powered pusher assembly for moving the load on the conveying surfaces of the at least two conveyor elements.

Yet another aspect of the present invention includes a method of wrapping a palletized load with packaging material. The method includes placing a palletized load to be wrapped onto a low profile conveyor comprising at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor element. The low profile conveyor further includes a base surface positioned between the conveyor elements, and the method further includes pushing the load with a powered pusher assembly to move the load on the conveying surfaces of the at least two conveyor elements, and providing relative rotation between a packaging material dispenser and the load to wrap packaging material around sides of the loads.

A further aspect of the present invention includes a method of wrapping a palletized load with packaging material. The method includes placing a first palletized load of a dual load carried by a pallet truck onto a low profile load conveyor having at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements. The low profile load conveyor further includes a base surface positioned between the conveyor elements. The method further includes placing a second palletized load of the dual load carried by the pallet truck onto the low profile load accumulation conveyor, pushing the first palletized load with a powered pusher assembly to move the first palletized load on the conveying surfaces into a wrapping area, and providing relative rotation between a packaging material dispenser and the first palletized load to wrap packaging material around sides of the first palletized load.

Another aspect of the present invention includes a low profile conveyor having at least two conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements, a base surface positioned between the conveyor elements, and a powered pusher assembly for moving the load on the conveying surfaces of the at least two conveyor elements.

Yet another aspect of the present invention includes a stretch wrapping system for wrapping palletized loads. The system includes a dispenser for dispensing packaging material, means for providing relative rotation between the dispenser and a load to be wrapped to wrap packaging material around the load, a first low profile conveyor portion comprising first and second conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of the first conveyor element is parallel to the longitudinal axis of the second conveyor element. The first low profile conveyor further includes a base surface positioned between the first and second conveyor elements. The system further includes a second low profile conveyor portion comprising third and fourth conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of the third conveyor element is parallel to the longitudinal axis of the fourth conveyor element. The second low profile conveyor also includes a base surface positioned between the third and fourth conveyor elements, and the system further includes at least one powered pusher assembly for moving the load on the conveying surfaces.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a top view of a warehouse floor showing a conventional wrapping staging area, stretch wrapping apparatus, and loading staging area;

FIG. 2 is a partial isometric view of a GMS pallet;

FIG. 3 is a partial isometric view of a Chep pallet;

FIG. 4 is an isometric view of a plastic pallet;

FIG. 5 is a top view of a warehouse floor showing a load accumulation area, a stretch wrapping apparatus, and a wrapped load staging area according to one aspect of the present invention;

FIG. 6A is a side view of a pallet truck with an elevated palletized load;

FIG. 6B is a side view of the pallet truck of FIG. 6A lowering the palletized load onto a low profile conveyor, according to one aspect of the present invention;

FIG. 6C is a side view of the pallet truck of FIG. 6A withdrawing from the palletized load with the leg and support wheel in a retracted position, according to one aspect of the present invention;

FIG. 7A is an end view of a low profile conveyor supporting a pallet mounted on forks of the pallet truck, according to one aspect of the present invention;

FIG. 7B is a top cross-sectional view taken along line B-B of the low profile conveyor supporting a pallet mounted on forks of the pallet truck of FIG. 7A, according to one aspect of the present invention;

FIG. 7C is a side view of the low profile conveyor supporting a pallet mounted on forks of the pallet truck of FIG. 7A, according to one aspect of the present invention;

FIG. 8A is a partial isometric view of a low profile accumulation conveyor, according to one aspect of the present invention;

FIG. 8B is an enlarged partial view of a conveying surface of the low profile accumulation conveyor of FIG. 8A;

FIG. 8C is an isometric view of a shaft and a roller used to form the conveying surface of FIG. 8B;

FIG. 9A is a side view of a palletized load being placed onto the low profile conveyor by a pallet truck, according to one aspect of the invention;

FIG. 9B is an end view of the palletized load of FIG. 9A being placed onto the low profile conveyor by the pallet truck, according to one aspect of the invention;

FIG. 10A is an isometric view of a stretch wrapping system including a low profile conveyor according to one aspect of the present invention;

FIG. 10B is an isometric view of a pusher arm of a pusher assembly according to one aspect of the invention;

FIGS. 11A-11D are top views of order-picked loads being processed on a stretch wrapping apparatus including a low profile infeed conveyor and a low profile exit conveyor, according to one aspect of the present invention;

FIGS. 12A-12D are cross-sectional end views of various configurations of a low profile conveyor including various surface types and showing relative heights in the different combinations, according to one aspect of the present invention;

FIGS. 13A-13B are top views of various configurations of a low profile infeed conveyor and a low profile exit conveyor used with a rotatable turntable, according to one aspect of the present invention; and

FIG. 13C is an isometric view of a rotatable turntable and a stretch wrapping system used with a system having the configurations of FIGS. 13A and 13B, according to one aspect of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

The present invention permits pickers to deliver order-picked loads directly to an accumulation conveyor in front of the stretch wrapping apparatus. The accumulation conveyer of the present invention is “low profile” to permit the order-picked loads to be placed directly onto the conveyor with the pallet truck. As used herein, the term “low profile” means that the height of the conveying surface, above a base surface, is less than the distance between the raised bottom pallet surface of a pallet supported by forks of the pallet truck and the base surface when the forks of the pallet truck are in their “raised” position.

The present invention describes various surfaces and their heights relative to one another. These surfaces will now be defined.

As used herein, the term “base surface” is intended to define the surface between the conveyor elements upon which the pallet truck drives to position and deposit a palletized load onto the conveying surfaces of the conveyor elements. As shown in FIGS. 12A-12D, the “base surface” may be the floor (FIG. 12D), a base plate upon which the conveyor elements and guide element are mounted (FIG. 12C), or one or more rolling plates positioned on top of the base plate (FIGS. 12A and 12B). If the base surface comprises one or both of a base plate and a rolling plate, it is preferred that the total height of the base surface does not exceed approximately 2 inches above the ground. This is because the load carried by the pallet truck is very unstable, and to drive up a ramp of more that 2 inches is likely to disturb or shift the load. In a preferred embodiment, the base surface, when comprising one or both of a base plate and a rolling plate, is between 0.5 inch and 0.25 inch in height.

As used herein, the term “conveying surface” is intended to define a rolling or movable top surface of a conveyor element upon which the load is placed to be moved into a load wrapping area. As shown in FIGS. 12A-12D, the distance between the top of the conveying surface and the base surface is always less than the distance between the base surface and the raised bottom pallet surface of a pallet supported on forks of a pallet truck, when the pallet truck is on the base surface. As shown in FIGS. 12A-12D, the conveying elements may be placed on the floor or on a base plate.

As used herein, the “guide element surface” is a top surface of a structure centrally positioned between the two conveyor elements. As shown in FIGS. 12A-12D, the guide element may be positioned on the same surface as the conveyor elements, or may be positioned on a rolling surface if one is provided. The distance between the guide element surface and the base surface is less than a distance between the base surface and the top of the conveying surface so as to prevent the guide element surface from interfering with conveyance of the load on the conveying surfaces.

As used herein, the term “raised bottom pallet surface” is intended to define the base of the bottom deck of a pallet when supported by forks of a pallet truck in a raised position. The distance between the raised bottom pallet surface and the base surface is always larger than the distance between the base surface and the top of the conveying surfaces of the conveyor elements to facilitate positioning of the palletized load on the conveying surfaces.

As shown in FIG. 8B, the conveying surface preferably extends no more than one inch above the base surface. Generally, the distance between a bottom surface of the pallet and the ground when the forks of the pallet truck are in their “raised” position is between about 0.5 inch and 4 inches. Therefore, the conveying surface may extend between approximately 0.5 inch and approximately 3.5 inches above the base surface, but preferably is approximately 1 inch above the base surface. It is important to note that the height of the conveying surfaces cannot be so small that the conveying surfaces cannot support the weight of the load. An example follows.

A typical pallet truck may be able to raise its forks approximately 9 inches above the ground. The pallet truck supports a palletized load on its forks. The pallet supporting the load is generally about 6 inches in height, with a top platform and a bottom platform each having approximately 0.5 inch height. The forks of the pallet truck extend between the top and bottom platforms of the pallet to support the load. Therefore, assuming the forks are raised to their maximum height, approximately 5-5.5 inches of pallet hang down from the forks and above the ground, leaving approximately 3.5-4 inches of clearance between the raised bottom pallet surface and the ground. However, it is important to note that it is very rare to transport an order-picked load with the forks raised to their maximum height due to the instability of the order-picked load. Instead, it is common to transport the load with the bottom of the pallet as close to the ground as possible, for example, a 0.5 inch above the ground.

The low height of the conveying surfaces is important not only for placing the load onto the conveying surfaces as discussed above, but also for permitting the forks of the pallet truck to be withdrawn from the pallet fork holes after the load is positioned on the conveying surfaces. As noted above, a pallet generally has a height of 6 inches, with top and bottom platforms representing approximately 0.166 of that height. That leaves approximately 5 inches of space for the forks of the fork truck. The forks of the fork truck include a leg with a support wheel to help carry the load. The support wheel extends outward from the bottom of the pallet to the ground. The support wheel is not hydraulically retractable, but instead is “pushed” even with the fork into a retracted position by releasing hydraulic fluid pressure and by the weight of the load.

Thus, when the load is positioned on the conveying surfaces, the distance between the raised bottom pallet surface and the base surface cannot be so great that the pallet truck cannot withdraw the forks from the fork holes in the pallet. In addition to overcoming the distance between the top of the conveying surface and the base surface, the leg and support wheel must also be withdrawn over the bottom deck of the pallet. Thus, if the bottom deck of the pallet is 0.5 inch thick, and the top of the conveying surfaces is approximately 1 inch above the base surface, the leg and wheel must be withdrawn upwards 1.5 inches. If the height is greater than this, the leg and wheel will tend to grab the pallet, rather than be pushed up into the forks as the forks are withdrawn, preventing withdrawal of the forks.

The present invention also provides a wrapped load accumulation conveyor to convey the wrapped loads away from the stretch wrapper. Both accumulation conveyors are preferably non-powered, thereby providing an inexpensive means for moving the loads. These accumulation conveyors may be incorporated into any stretch wrapping system, but are particularly suited for systems which use pallet trucks or pallet jacks.

According to one aspect of the invention, a low profile accumulation conveyor is provided. As embodied herein and shown in FIGS. 8A-8C, the accumulation conveyor 100 may include two conveyor elements 110. Each conveyor element 110 includes a non-powered rolling conveying surface 111. Each conveying surface 111 may be formed by a plurality of non-powered rollers 112, each roller 112 being mounted on a shaft 114. In one example, the non-powered rollers have a 0.75 inch diameter and are supported on 0.5 inch diameter shafts. Alternatively, it is possible that the conveying surfaces 111 may not be a roller surface, but instead may be some other low-friction surface. For example, instead of non-powered rollers 112, the conveying surfaces 111 may use drag chains, belts, transfer ball bearings, or other non-powered low friction elements such as a smooth surface. Each conveyor element 110 includes a pair of side rails, an inner side rail 120 and an outer side rail 118. The shafts 114 may be mounted in the rails 118, 120 in any suitable way, for example, with slots in the rails to support the rollers 112.

Each of the conveyor elements 110 includes a longitudinal axis 110a and the conveyor elements 110 are positioned parallel to one another such that their longitudinal axes 110a are parallel. The conveyor elements 110 are spaced apart from one another a sufficient distance to permit the forks of a pallet truck to fit between the respective inner side rails 120 of the conveyor elements 110. The conveyor elements 110 are also positioned close enough to one another that at least a portion of each of the outer side edges of the pallet supporting the load are positioned on the conveying surfaces 111 of the conveyor elements 110, as shown in FIG. 9B.

The conveyor elements 110 may be positioned on the floor or mounted on a base plate 116. If mounted on a base plate 116, the base plate 116 may include a tapered end 117 to facilitate access by the pallet truck. Preferably, the base plate 116 extends no more than approximately 2 inches above the ground to facilitate the pallet truck driving onto the base plate with an unstable load. More preferably, the base plate 116 extends approximately 0.25 inch above the ground. The pallet truck can drive up the tapered end 117 of the base plate 116 to deposit the load(s) onto the conveying surfaces 111 of the conveyor elements 110. Regardless of whether a base plate 116 is used, it is also possible to utilize one or more rolling plates 113 (see FIGS. 12A and 12B). The purpose of the rolling plate 113 is to reduce the distance between the top of the conveying surface 111 of the conveyor elements 110 and the base surface. When rolling plates 113 are used, they become the base surface. Rolling plates 113 may be placed directly on the floor or on top of the base plate 116.

The accumulation conveyor 100 may also include elements for guiding the forks of the pallet truck. As embodied herein and shown in FIG. 9B, the guide elements for guiding the forks of the pallet truck may include a raised center structure 122. The raised center structure 122 may be centered between the inner side rails 120 of the conveyor elements 110. If a base plate 116 is used, the center structure 122 may be positioned on the base plate 116. If rolling plates 113 are used, the center structure 122 may or may not be positioned on the rolling plates 113 (see FIGS. 12A and 12B).

Preferably, the distance between the top of the raised center structure 122 and the base surface is less than the distance between the tops of the conveying surfaces 111 of the conveyor elements 110 and the base surface. This prevents the palletized load 124 from resting on the raised center structure 122 when the load 124 is placed on the conveying surfaces 111 of conveyor elements 110, which might create friction resistance to forward movement of the load 124 on the conveying surfaces 111. Raised center structure 122 may include tapered edges 123. The raised center structure 122 may have any length suitable. For example, the raised center structure 122 may extend for the entire length of the accumulation conveyor 100, or it may be the approximate length of the forks of the pallet truck. Raised center structure 122 cooperates with inner side rails 120 of the conveyor elements 110 to guide the forks of the pallet truck, keeping the forks of the pallet truck between the raised center structure 122 and the inner side rails 120. This prevents the fork truck from moving onto the conveying surfaces 111 of the conveying elements 110 and helps to position the outer side edges of the palletized load 124 with respect to the conveying surfaces 111.

Although less preferred, it is also possible that the low profile conveyor includes only one conveyor element 110. In such an embodiment, the conveying surface must be wide enough to support the load and narrow enough to permit the forks of the fork truck to move on either side of the conveyor element 110 to deposit the load on the conveying surface 111. Alternatively, more than two conveying elements 110 may be used to form the low profile conveyor.

According to another aspect of the invention, the load accumulation conveyor 100 is provided with a load pusher assembly 150 for moving the load on the conveying surfaces 111 of the conveying elements 110 to a stretch wrapping apparatus. Such a pusher assembly is disclosed in U.S. Patent Application Publication No. 2002/0056253 entitled “Method and Apparatus for Wrapping a Load,” the entire contents of which is incorporated herein by reference. In a preferred embodiment, the pusher assembly 150 includes a pusher bar or arm 151. Pusher arm 151 is preferably located alongside the load accumulation conveyor 100 and a stretch wrapping apparatus. As shown in FIG. 10B, pusher arm 151 includes a pusher carrier 154 that rides on a pusher guide 156 and is powered by a pusher drive 158. In a preferred embodiment, the pusher arm 151 may be a rotating bar mounted to a linear bearing. The pusher arm 151 may have a first travel position where the arm is upright and vertical, and a second pushing position where the arm is lowered and horizontal.

Alternatively, a motor with integrated gear box may be attached to pusher carrier 154 to drive pusher arm 151 along the pusher guide 156. In such an embodiment, the motor drives the rotation of the pusher arm 151 about a center of rotation as determined by the carrier frame 154. Thus, pusher arm 151 is moveable between an upright travel position and a horizontal pushing position.

Referring to FIG. 10B, pusher arm 151 preferably has an “L” shape, and is configured such that a guiding leg 151b of the “L” moves along pusher guide 156 that forms a track for pusher carrier 154 which carries pusher arm and moves it along the guide. Pushing leg 151a of pusher arm 151 extends across the conveying surfaces 111 when in the pushing position, i.e., horizontal and lowered position. In a preferred embodiment, the pushing leg 151a is of a length greater than or equal to the width of the load to be pushed. However, it is possible to reduce the length of the pushing leg 151a while still moving the load in the desired manner. Pusher arm 151 may be made of any material of sufficient strength and rigidity to move loads, such as steel. In addition, when more than one load is to be placed on the accumulation conveyor 100, it may be desirable or necessary, dependent upon the configuration of the conveyor 100, to use more than one pusher arm 252a, 252b, to move the load, as shown in FIGS. 11A-11B. In such a case, it may be desirable to provide one rotatable pusher arm, and one non-rotatable or fixed pusher arm. When two or more pusher arms are used, it may be desirable to link them to one another such that they act in concert.

Pusher arm 151 is moveable between an upright, vertical position and a lowered, horizontal pushing position. Pusher arm 151 preferably remains in the upright position unless engaging and moving a load between positions, for example, from an accumulation area to a wrapping area. The movement of pusher arm 151 may be controlled in any suitable way. For example, movement may be controlled by simple logic programming. In addition, it may be preferable to provide a signal or flag to determine whether there is a load already on the wrapping area. If there is a load on the wrapping area, the pusher arm 151 will not move another load the from accumulation area to the wrapping area.

According to another aspect of the invention, the accumulation conveyor 100 may be incorporated into a stretch wrapping system 200. As embodied herein and shown in FIGS. 11A-11D, the stretch wrapping system 200 may include a low profile conveyor including a load accumulation area and a load wrapping area, a packaging material dispenser, means for providing relative rotation between a load and the dispenser, and a load pusher assembly for moving the load between the load accumulation area and the load wrapping area.

According to one aspect of the invention, system 200 includes a low profile conveyor 201 including a load accumulation area 225 and a load wrapping area 230. As embodied herein and shown in FIGS. 11A-11D, the accumulation conveyor 201 includes two conveyor elements 210. As shown in FIGS. 8A-8C, each conveyor element 210 may include a non-powered conveying surface 211. Each conveying surface 211 may be formed by a plurality of non-powered rollers 212, each roller 212 being mounted on a shaft 214. In one example, the non-powered rollers have a 0.75 inch diameter and are supported on 0.5 inch diameter shafts. Alternatively, it is possible that the conveying surfaces 211 may not be a roller surface, but instead may be some other low-friction surface. For example, instead of non-powered rollers 212, the conveying surfaces 211 may use drag chains, belts, transfer ball bearings, or other non-powered, low friction elements such as a smooth surface. Each conveyor element 210 includes a pair of side rails, an inner side rail 220, and an outer side rail 218. The shafts 214 may be mounted to the rails 218, 220 in any suitable way, for example, with slots in the rails 218, 220 to receive the shafts 214 that support the rollers 212.

Each of the conveyor elements 210 includes a longitudinal axis 210a and the conveyor elements 210 are positioned parallel to one another such that their longitudinal axes 210a are parallel. The conveyor elements 210 are spaced apart from one another a sufficient distance to permit the forks of a pallet truck to fit between the respective inner side rails 220 of the conveyor elements 210. The conveyor elements 210 are also positioned close enough to one another that at least a portion of each of the outer side edges of the pallet supporting the load are positioned on the conveying surfaces 211 of the conveyor elements 210, as shown in FIG. 9B.

The conveyor elements 210 may be positioned on the floor or mounted on a base plate 216 as previously described with respect to FIGS. 12A-12D. Preferably, the base plate extends no more than approximately 2 inches above the ground to facilitate the pallet truck driving onto the base plate with an unstable load. More preferably, the base plate extends approximately 0.25 inch above the ground. The pallet truck can drive up the tapered end 217 and onto the base plate 216 to deposit the load(s) onto the conveying surfaces of conveyor elements 210 in a load accumulation area 225 of conveyor 201. Regardless of whether a base plate 216 is used, it is also possible to utilize one or more rolling plates 213 as previously described with respect to FIGS. 12A and 12B.

The accumulation conveyor 201 may also include a guide element for guiding the forks of the pallet truck as previously described with respect to FIG. 9B.

As embodied herein and shown in FIGS. 11A-11D, the low profile conveyor 201 preferably includes a load accumulation area 225, a load wrapping area 230, and a load exit area 235. The load accumulation area 225 is positioned upstream of the wrapping area 230. The wrapping area 230 is positioned between the load accumulation area 225 and the load exit area 235. The load accumulation area 225 is configured to receive loads from pallet trucks and move these loads into the load wrapping area 230. A load pusher assembly 250a is provided for moving loads between the load accumulation area 225 and the load wrapping area 230. The load pusher assembly 250a is substantially the same as load pusher assembly 150 discussed above with respect to FIG. 10b. Such a pusher assembly is also disclosed in U.S. Patent Application Publication No. 2002/0056253 entitled “Method and Apparatus for Wrapping a Load,” the entire contents of which is incorporated herein by reference. In a preferred embodiment, the pusher assembly 250a includes two pusher bars or arms 252a. Pusher arms 252a are preferably located alongside the load accumulation area 225. A separate exit pusher assembly 250b may be provided to move wrapped loads from the wrapping area 230 to the load exit area 235. In a preferred embodiment, the exit pusher assembly 250b includes a single pusher bar or arm 252b. Pusher arm 252b is preferably located alongside the load wrapping area 230 and load exit area 235. Alternatively, the load pusher assembly and the exit pusher assembly may be connected to form a single unit.

According to another aspect of the invention, system 200 may include a packaging material dispenser. As shown in FIG. 10A, a dispenser 202 is provided for dispensing packaging material 207. Packaging material dispenser 202 dispenses a sheet of packaging material 207 in a web form and includes a roll carriage that supports a roll of packaging material. The roll carriage of dispenser 202 is mounted and vertically moveable on an arm 204 to dispense packaging material 207 spirally about load 224 as rotation is provided between load 224 and dispenser 202. The roll carriage may include a support for the packaging material roll and means for moving on arm 204.

According to one aspect of the present invention, the dispenser 202 may include a prestretch portion configured to prestretch the film. The prestretch portion may be any type of conventional prestretch portion, including either powered roller stretch or unpowered roller stretch.

In a preferred embodiment, stretch wrap packaging material is used. In the stretch wrapping art, stretch wrap packaging material is known to have a high yield coefficient to allow the material a large amount of stretch during wrapping. Various other packaging materials, generally not considered to be stretch wrap materials, such as netting, strapping, banding, and tape, can be used as well.

According to another aspect of the invention, system 200 includes means for providing relative rotation between the dispenser 202 and the load 224. As shown in FIG. 10A, dispenser 202 is mounted on a vertical structure such as a rotary arm 204. Rotary arm 204 has a first portion secured to a bearing member and a second portion holding the dispenser 202. The first portion of the arm 204 is rotatable about a vertically extending axis of rotation to wrap packaging material 207 around the sides of the load 224.

A motor drive (not shown) is provided for providing relative rotation around the generally vertical axis between the packaging material dispenser and the load to wrap packaging material about the sides of load. The drive rotates rotatable arm 204 and dispenser 202 about generally vertical axis to wrap packaging material 207 around the sides of load 224.

According to another aspect of the invention, it may be desirable to provide a system 300 that includes more than one accumulation conveyor 301 feeding a stretch wrapper, or in some instances, a separate exit conveyor 401. As embodied herein and shown in FIGS. 13A-13C, the accumulation conveyor 301 and exit conveyor 401 each may include two or more conveyor elements 310, 410 respectively, the conveyor elements being similar to conveyor elements 110, 210 previously described. Each conveyor element 310, 410 may have conveying surfaces 311, 411 respectively, the conveying surfaces being similar to conveying surfaces 111, 211 previously described. Each conveyor element 310, 410 also has a longitudinal axis 310a, 410a, respectively, as described above with regard to conveyor elements 110, 210. In addition, each of the conveyor elements making up a conveyor (e.g., an accumulation conveyor or an exit conveyor) may be positioned parallel to one another such that their longitudinal axes are parallel. For example, conveyor elements 310 making up conveyor 301 are positioned parallel to one another such that their longitudinal axes 310a are parallel. However, conveying elements 310, 410 making up separate conveyors may or may not be positioned parallel to one another. For example and as shown in FIG. 13B, conveying elements 310 making up conveyor 301 are positioned parallel to one another, and conveying elements 410 making up conveyor 401 are positioned parallel to one another; however, conveying elements 310 and 410 may be positioned substantially at any angular orientation with respect to each other.

In addition, it is also possible to provide more than one accumulation conveyor 301. For example, a system may include two accumulation conveyors, each conveyor including, for example, two conveyor elements having longitudinal axes which are parallel to the additional conveyor elements making up the individual conveyor. The longitudinal axes of individual accumulation conveyors need not be parallel to one another and preferably are not parallel to one another. The addition of another accumulation conveyor may increase throughput and may provide additional space for holding loads to be wrapped. Alternatively, more than one exit conveyor may be used instead of or in conjunction with additional accumulation conveyors. In an embodiment in which separate accumulation and exit conveyors are provided, it may be necessary to provide a structure to transition the load between the two conveyors. One such structure is a turntable, as described below. Additional structures suitable to move the load from the accumulation conveyor to the exit conveyor may also be used.

According to another aspect of the present invention, the means for providing relative rotation may include a rotatable turntable 332 that rotates a load 324 relative to a dispenser 302, which may be mounted to move vertically on a mast 304. In such an embodiment, it would be necessary to provide two pairs of conveying elements 310, 410, one to form the low profile conveyor 301 in the load accumulation area and a second pair to form a low profile conveyor 401 in the load exit area, as previously described. The rotatable turntable 332 in conjunction with a pusher assembly 350b is capable of moving the load 324 between the accumulation conveyor 301 and the exit conveyor 401.

As shown in FIG. 13C, packaging material dispenser 302 dispenses a sheet of packaging material 316 in a web form and may include a roll carriage 309 that supports a roll 308 of packaging material 316. Roll carriage 309 of dispenser 302 is mounted on and vertically moveable on a mast 304 to dispense packaging material 316 spirally about load 324 as rotation is provided between the load and the dispenser 302.

Rotatable turntable 332 may include a non-powered upper conveyor surface 330 with a plurality of non-powered rollers 312 for supporting the load during wrapping. Alternatively, instead of non powered rollers 312, the non-powered conveyor load wrapping surface 330 may use drag chains, belts, transfer ball bearings, or other non-powered, low friction elements such as a smooth surface. Alternatively, the upper conveyor surface 330 may power rollers 312.

The rollers 312 of the conveyor load wrapping surface 330 are preferably capable of being locked into a non-rolling position during wrapping. That it, when load 324 is being wrapped, the rollers 312 of the load wrapping surface 330 do not move, reducing the chances of a load shifting during wrapping. Prior and subsequent to the wrapping cycle, the rollers 312 of the conveyor load wrapping surface 330 are preferably in an “unlocked” or rolling position. Thus, the rollers 312 are capable of rolling to assist in moving load 324 onto or off of the conveyor load wrapping surface 330. Alternatively, tabs or pins can be used, projecting through the rollers 312, to prevent travel of the load.

Rotatable turntable 332 may include a packaging material holder assembly 370 for holding a leading end of the packaging material 316 during wrapping of the load. The packaging material holder assembly 370 may be positioned at an end of the load wrapping surface 330 where it will not interfere with the movements of loads onto and off of the rotatable turntable 332. Alternatively, instead of a packaging material assembly 370, a clamp or other means may be used to restrain the leading end of the packaging material during wrapping.

A method of use of the system 200 will now be described.

A picker builds a dual load 24a, 24b. To build the dual load 24a, 24b, the picker moves a pallet truck 40 (sometimes hand operated with the picker walking behind the pallet truck, sometimes operator rides) between rows 10 of products in a warehouse and “picks” the necessary products to form the loads 24a, 24b. (See FIG. 5.) Each load 24a, 24b is built on a pallet 26. Each pallet 26 includes a top platform 28, a bottom platform 30, side supports 32, fork holes 34, and bottom holes 36 in the bottom platform 30 (see FIGS. 2, 3, and 6A-6C). The pallets 26 are supported on forks 42 of a pallet truck 40 operated by the picker. The forks 42 of the pallet truck 40 extend through the fork holes 34 of the pallets 26 and a support wheel 44 mounted on a leg 46 extends from each fork 42 and through the bottom holes 36 in the bottom platform 30 of the pallet 26. When the forks 42 are in a raised position, the support wheel 44 is in contact with the ground and the leg 46 extends downwardly from fork 42.

To position the dual load 24a, 24b in the accumulation area 225 on the conveyor 201, the picker “drives” the pallet truck 40 onto the base surface (floor, base plate 216, or rolling plate 213) with the forks 42 and their respective leg 46 and wheel 44 positioned on either side of the raised center structure 222 (if present). Each fork 42, leg 46, and wheel 44 is guided onto the base surface, in this example, base plate 216 between the raised center structure 222 and the inner side rails 220 of the conveyor elements 210, as shown in FIGS. 9A and 9B. The pallet truck 40 moves onto the base surface with the palletized loads elevated (see FIG. 6A). The forks 42 of the pallet truck 40 are then lowered to lower a first palletized load onto the conveying surfaces 211 of the conveyor elements 210 (see FIG. 6B). As the pallet truck 40 backs out of the first pallet, the leg 46 and support wheel 44 are retracted by contact with the base deck boards 30 of the pallet 26 to completely withdraw from the first pallet (see FIG. 6C). The forks 42 are then raised to elevate a second palletized load and this process is repeated to position the second palletized load. Preferably, the conveyor 201 includes a mechanism to engage a bottom portion of the pallet to ensure that the load is positioned appropriately. This is particularly useful when placing more than one load. An example of a suitable mechanism is a plate which permits forward movement and prevents reverse movement, as illustrated in FIG. 9A. After the first palletized load passes over the plate, the plate will engage a back portion of the pallet, preventing backward movement of the load and assisting in withdrawal of the forks from the fork holes of the pallet.

As shown in FIGS. 1A and 11B, the dual loads 24a, 24b may be positioned on the accumulation area 225 of the conveyor 201 while another load 24c is being wrapped in the wrapping area. As shown in FIG. 11B, a second dual load 24d, 24e may be positioned behind the first dual load 24a, 24b in the accumulation area 225 of the conveyor 201 by a different picker.

During wrapping, the pusher arms 252a remain in an upright position (see FIG. 11A). During the last rotation of the wrapping cycle (wrapping load 24c), pusher arms 252a rotate approximately 90 degrees into the horizontal pushing position (see FIG. 11B). Pusher arms 252a then begin to move in the downstream direction toward the wrapping area 230 along pusher guide 256 while in the horizontal pushing position. As pusher arms 252a move downstream, they engage the first dual load 24a, 24b on the non-powered conveying surfaces 211 of the conveyor elements 210 in the load accumulation area 225 and simultaneously push the first portion 24a of the dual load 24a, 24b from the load accumulation area 225 into the wrapping area 230 and second portion of the dual load 24b to a position closer to the wrapping area 230.

At the same time, pusher arm 252b of the exit pusher assembly 250b moves along pusher guide 256b in an upstream direction. When pusher arm 252b reaches a position slightly upstream of the end of the load being wrapped, pusher arm 252b rotates approximately 90 degrees into the horizontal pushing position. Pusher arm 252b then begins to move in the opposite direction (downstream) along pusher guide 256b while in the horizontal pushing position. As pusher arm 252b moves, it engages a side of the wrapped load 24c on the non-powered conveying surfaces 211 of conveyor elements 210 in the wrapping area 230 and pushes the wrapped load 24c from the load wrapping area 230 into load exit area 235 (see FIG. 11C).

Once the load 24a is positioned in the load wrapping area 230, relative rotation is provided between the load 24a and the dispenser 202 by rotating rotatable arm 204 and dispenser 202 around the load 24a. As the arm 204 and dispenser 202 rotate, packaging material 207 is wrapped around the sides of the load 24a. The operator picks up the wrapped load 24c from the load exit area 235 and transports it to a truck-loading staging area.

A method of use of the system 300 will now be described.

A picker builds a dual load and positions the dual load on accumulation conveyor 301 in substantially the same manner as described above with respect to FIGS. 2, 3, 5, 6A-6C, 9A and 9B. If a second accumulation conveyor is provided (not shown), a second picker may position a second dual load on the second accumulation conveyor while the first dual load is being positioned on the accumulation conveyor 301. A load 324 may or may not be wrapped while the loads are positioned.

After the loads are positioned, the pusher arms 352a of load pusher assembly 350a move along pusher guide 356 and push a load from the accumulation conveyor 301 onto rotatable turntable 332. If necessary, rotatable turntable may rotate to align its conveyor surface with conveyor 301 in order to facilitate movement of the load onto the turntable. Rotatable turntable 332 rotates load 324 and dispenser 302 dispenses packaging material 316 and moves vertically on mast 304 to wrap packaging material 316 around the sides of the load 324.

After wrapping, load 324 is pushed onto exit conveyor 401 by exit pusher assembly 350b as it travels along exit pusher guide 356b. If the longitudinal axis of load accumulation conveyor 301 is not parallel to the longitudinal axis of the exit conveyor 401, it may be necessary to rotate turntable 332 to align the load with exit conveyor 401 prior to moving the load 324 onto exit conveyor 401 with pusher arm 352b.

The remainder of the process is substantially as described above. If more than one accumulation conveyor is provided, the process may alternatively take loads from each conveyor. Additionally, if more than one exit conveyor is provided, loads may alternatively be provided to the exit conveyors. In each instance, it may be necessary for the turntable to rotate to align its conveying surface with the conveyor delivering or receiving the load.

Embodiments of the invention may be used in conjunction with any packing or loading process, including where products are picked and loaded together for transportation. In addition, at least certain aspects of the aforementioned embodiments may be combined with other aspects of the embodiments, or removed, without departing from the scope of the invention.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

1. A low profile conveyor, comprising:

at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements; and

a base surface positioned between the conveyor elements.

2. The low profile conveyor of claim 1, wherein the base surface is the ground.

3. The low profile conveyor of claim 1, wherein the conveying surface of each of the at least two conveyor elements is between about 3.5 inches and about 0.5 inch above the base surface.

4. The low profile conveyor of claim 3, wherein the conveying surface of each of the at least two conveyor elements is approximately 1 inch above the base surface.

5. The low profile conveyor of claim 1, further comprising a guide element.

6. The low profile conveyor of claim 5, wherein the guide element includes a raised structure positioned between the at least two conveyor elements.

7. The low profile conveyor of claim 6, wherein the raised structure is centered between the at least two conveyor elements.

8. The low profile conveyor of claim 6, wherein the raised structure extends a first distance above the base surface and the at least two conveyor elements extend a second distance above the base surface, wherein the first distance is different from the second distance.

9. The low profile conveyor of claim 8, wherein the first distance is less than the second distance.

10. The low profile conveyor of claim 1, wherein the conveyor is configured to receive a load from a pallet truck.

11. The low profile conveyor of claim 10, wherein the pallet truck includes forks configured to support a base of a pallet a first distance from the base surface, wherein the at least two conveyor elements extend a second distance above the base surface, and wherein the second distance is less than the first distance.

12. The low profile conveyor of claim 1, wherein the at least two conveyor elements are spaced to permit the passage of pallet truck forks between them.

13. The low profile conveyor of claim 1, wherein the rolling elements include rolling surfaces mounted on shafts.

14. The low profile conveyor of claim 1, further comprising a pusher assembly for pushing a load on the conveying surfaces of the at least two conveyor elements.

15. The low profile conveyor of claim 14, wherein the pusher assembly includes an L-shaped pusher arm.

16. The low profile conveyor of claim 15, wherein the pusher arm is rotatable.

17. The low profile conveyor of claim 15, wherein the pusher arm is rotatable between an upright, vertical position and a lowered, horizontal position.

18. The low profile conveyor of claim 15, wherein the pusher assembly further includes a second pusher arm.

19. The low profile conveyor of claim 18, wherein the pusher arms are linked to move together.

20. The low profile conveyor of claim 1, wherein the base surface includes a base plate.

21. The low profile conveyor of claim 20, wherein the at least two conveyor elements are mounted on the base plate.

22. The low profile conveyor of claim 1, wherein the base surface includes at least one rolling plate.

23. The low profile conveyor of claim 22, wherein the at least one rolling plate is positioned on a base plate.

24. The low profile conveyor of claim 23, wherein the at least two conveyor elements are mounted on the base plate.

25. The low profile conveyor of claim 23, further including a third and fourth conveyor elements.

26. A stretch wrapping system for wrapping palletized loads, comprising:

a dispenser for dispensing packaging material;

means for providing relative rotation between the dispenser and a load to wrap packaging material around the load;

a low profile conveyor comprising at least two conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements, and a base surface positioned between the conveyor elements; and

a powered pusher assembly for moving the load on the conveying surfaces of the at least two conveyor elements.

27. The stretch wrapping system of claim 26, wherein the at least two conveyor elements are non-powered.

28. The stretch wrapping system of claim 26, wherein the conveying surface of each of the at least two conveyor elements is between about 3.5 inches and about 0.5 inch above the base surface.

29. The stretch wrapping system conveyor of claim 28, wherein the conveying surface of each of the at least two conveyor elements is approximately 1 inch above the base surface.

30. The stretch wrapping system of claim 26, wherein the low profile conveyor further includes a guide element.

31. The stretch wrapping system of claim 30, wherein the guide element includes a raised structure positioned between the at least two conveyor elements.

32. The stretch wrapping system of claim 31, wherein the raised structure is centered between the at least two conveyor elements.

33. The stretch wrapping system of claim 31, wherein the raised structure extends a first distance above the base surface and the at least two conveyor elements extend a second distance above the base surface, wherein the first distance is different from the second distance.

34. The stretch wrapping system of claim 33, wherein the first distance is less than the second distance.

35. The stretch wrapping system of claim 26, wherein the conveyor is configured to receive a load from a pallet truck.

36. The stretch wrapping system of claim 35, wherein the pallet truck includes forks configured to support a base of a pallet a first distance from the base surface, wherein the at least two conveyor elements extend a second distance above the base surface, and wherein the second distance is less than the first distance.

37. The stretch wrapping system of claim 26, wherein the at least two conveyor elements are spaced to permit the passage of pallet truck forks between them.

38. The stretch wrapping system of claim 26, wherein each conveying surface is formed by a plurality of rolling elements positioned between the side rails.

39. The stretch wrapping system of claim 38, wherein the non-powered rollers are mounted on shafts connected to the rails.

40. The stretch wrapping system of claim 26, wherein the pusher assembly includes an L-shaped pusher arm.

41. The stretch wrapping system of claim 40, wherein the pusher arm is rotatable.

42. The stretch wrapping system of claim 40, wherein the pusher arm is rotatable between an upright, vertical position and a lowered, horizontal position.

43. The stretch wrapping system of claim 40, wherein the pusher assembly further includes a second pusher arm.

44. The stretch wrapping system of claim 40, wherein the pusher arms are linked to move together.

45. The stretch wrapping system of claim 26, wherein the means for providing relative rotation includes a rotatable arm.

46. The stretch wrapping system of claim 26, wherein the low profile accumulation conveyor includes a load accumulation area, a load wrapping area, and a load exit area.

47. The stretch wrapping system of claim 46, further comprising an exit pusher assembly for pushing the load from the load wrapping area to the load exit area on the at least two conveying surfaces.

48. The stretch wrapping system of claim 26, wherein the base surface includes a base plate.

49. The stretch wrapping system of claim 48, wherein the at least two conveyor elements are mounted on the base plate.

50. The stretch wrapping system of claim 26, wherein the base surface is one of a floor and the ground.

51. The stretch wrapping system of claim 26, wherein the base surface includes at least one rolling plate.

52. The stretch wrapping system of claim 51, wherein the at least one rolling plate is positioned on a base plate.

53. The stretch wrapping system of claim 52, wherein the at least two conveyor elements are mounted on the base plate.

54. The stretch wrapping system of claim 26, wherein the low profile conveyor further includes third and fourth conveyor elements.

55. The stretch wrapping system of claim 54, wherein first and second conveyor elements are arranged on an upstream side of the means for providing relative rotation and the third and fourth conveyor elements are arranged on a downstream side of the means for providing relative rotation.

56. The stretch wrapping system of claim 55, wherein each of the third and fourth conveyor elements have a longitudinal axis, and wherein the third and fourth conveyor elements are positioned such that the longitudinal axis of the third conveyor element is parallel to the longitudinal axis of the fourth conveyor element.

57. The stretch wrapping system of claim 55, wherein the means for providing relative rotation includes a turntable.

58. The stretch wrapping system of claim 56, wherein the longitudinal axes of the first and second conveying elements are not parallel to the longitudinal axes of the third and fourth conveying elements.

59. A method of wrapping a palletized load with packaging material, comprising:

placing a palletized load to be wrapped onto a low profile conveyor comprising at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor element, and a base surface positioned between the conveyor elements;

pushing the load with a powered pusher assembly to move the load on the conveying surfaces of the at least two conveyor elements; and

providing relative rotation between a packaging material dispenser and the load to wrap packaging material around sides of the loads.

60. The method of claim 59, wherein pushing the load includes moving the load from a load accumulation area to a load wrapping area.

61. The method of claim 59, wherein pushing the load includes moving the load from a load wrapping area to a load exit area.

62. The method of claim 59, wherein the packaging material dispenser is mounted on a rotatable arm and wherein providing relative rotation includes rotating the rotatable arm.

63. The method of claim 59, wherein providing relative rotation includes rotating a turntable supporting the load.

64. A method of wrapping a palletized load with packaging material, comprising:

placing a first palletized load of a dual load carried by a pallet truck onto a low profile load conveyor comprising at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements, and a base surface positioned between said conveyor elements;

placing a second palletized load of the dual load carried by the pallet truck onto the low profile load accumulation conveyor;

pushing the first palletized load with a powered pusher assembly to move the first palletized load on the conveying surfaces into a wrapping area; and

providing relative rotation between a packaging material dispenser and the first palletized load to wrap packaging material around sides of the first palletized load.

65. The method of claim 64, further comprising building a dual load on pallets carried on a pallet truck.

66. The method of claim 64, further comprising pushing the wrapped first palletized load with a second powered pusher assembly to move the wrapped load on the conveying surfaces.

67. The method of claim 64, further comprising, subsequent to wrapping the first palletized load, pushing the second palletized load with the powered pusher assembly to move the second palletized load on the conveying surfaces into a wrapping area.

68. The method of claim 64, wherein placing the first palletized load of the dual load carried by the pallet truck includes driving the pallet truck onto the base surface and lowering forks of the pallet truck to position the first palletized load on the conveying surfaces.

69. The method of claim 68, wherein driving onto the base surface includes guiding the forks of the pallet truck between the at least two conveyor elements.

70. The method of claim 69, wherein guiding the forks of the pallet truck includes moving each fork between one of the at least two conveyor elements and a raised structure centered between the at least two conveyor elements.

71. The method of claim 68, wherein placing the first palletized load of the dual load carried by the pallet truck further includes backing the pallet truck up to withdraw the forks from fork holes in the pallet supporting the first palletized load.

72. The method of claim 64, wherein the packaging material dispenser is mounted on a rotatable arm and wherein providing relative rotation includes rotating the rotatable arm.

73. The method of claim 64, wherein providing relative rotation includes rotating a rotatable turntable supporting the load.

74. The method of claim 73, further comprising rotating the turntable to position the load to be moved onto an exit conveyor comprising at least two non-powered conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements, and a base surface positioned between said conveyor elements.

75. A low profile conveyor, comprising:

at least two conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of one of the conveyor elements is parallel to the longitudinal axis of the other of the conveyor elements;

a base surface positioned between the conveyor elements; and

a powered pusher assembly for moving the load on the conveying surfaces of the at least two conveyor elements.

76. The low profile conveyor of claim 14, wherein pushing the wrapped load includes rotating a pusher arm from an upright position to a horizontal position.

77. The low profile conveyor of claim 63, wherein pushing the load includes engaging a side of the load with a portion of a pusher assembly.

78. A stretch wrapping system for wrapping palletized loads, comprising:

a dispenser for dispensing packaging material;

means for providing relative rotation between the dispenser and a load to be wrapped to wrap packaging material around the load;

a first low profile conveyor portion comprising first and second conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of the first conveyor element is parallel to the longitudinal axis of the second conveyor element, and a base surface positioned between the first and second conveyor elements;

a second low profile conveyor portion comprising third and fourth conveyor elements, each conveyor element having a longitudinal axis and including an inner side rail, an outer side rail, and a conveying surface formed by a plurality of rolling elements positioned between the side rails, wherein the longitudinal axis of the third conveyor element is parallel to the longitudinal axis of the fourth conveyor element, and a base surface positioned between the third and fourth conveyor elements; and

at least one powered pusher assembly for moving the load on the conveying surfaces.

79. The stretch wrapping system of claim 78, wherein the conveyor elements are non-powered.

80. The stretch wrapping system of claim 78, wherein the conveying surfaces of the each of the conveyor elements are between about 3.5 inches and 0.5 inches above the base surface.

81. The stretch wrapping system of claim 80, wherein the conveying surfaces of each of the conveyor elements is approximately 1 inch above the base surface.

82. The stretch wrapping system of claim 78, wherein each of the low profile conveyors further includes a guide element.

83. The stretch wrapping system of claim 82, wherein each guide element includes a raised structure.

84. The stretch wrapping system of claim 78, wherein each conveyor is configured to receive a load from a pallet truck.

85. The stretch wrapping system of claim 78, wherein the powered pusher assembly includes an L-shaped arm.

86. The stretch wrapping system of claim 85, wherein the pusher arm is rotatable.

87. The stretch wrapping system of claim 78, further including a second powered pusher assembly.

88. The stretch wrapping system of claim 87, wherein a first powered pusher assembly is adjacent the first low profile conveyor and a second powered pusher assembly is adjacent the second low profile conveyor.