Load Shaping of Stretch Wrapped Palletized Loads

Various packaging techniques have been used to build a load of unit products and subsequently wrap them for transportation, storage, containment and stabilization, protection, and waterproofing. One system uses wrapping machines to stretch, dispense, and wrap packaging material around a load. The packaging material may be pre-stretched before it is applied to the load. Wrapping can be performed as an inline, automated packaging technique that dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Stretch wrapping, whether accomplished by a turntable, rotating arm, vertical rotating ring, or horizontal rotating ring, typically covers the four vertical sides of the load with a stretchable packaging material such as polyethylene packaging material. In each of these arrangements, relative rotation is provided between the load and the packaging material dispenser to wrap packaging material about the sides of the load.

Some types of loads, however, can present difficulties when stretch wrapping. Consumer paper products, for example, are often shipped by palletizing and wrapping multi-unit bundles stacked in multiple layers on a pallet, and without the use of separate cardboard boxes to house the multi-unit bundles. Paper towels and toilet paper, for example, are often sold in various quantities and packaged in polyethylene bags. The types of products and the bundling of those products, however, often can limit the maximum wrap force used to wrap the palletized bundles, as excessive wrap force can lead to deformation and/or crushing of the products, particularly at the corners of the load.

Due to the wide variety of sizes and quantities of paper products shipped in this manner, it is often the case that the lateral dimensions of these multi-unit bundles, when arranged on a pallet, do not precisely match the lateral dimensions of the pallet. Standard pallets in the United States, for example, are 40×48 inches, and when loaded side to side in a truck, have a combined width of 96 inches, which is generally just below the standard truck door opening width of about 98 inches.

Undersized loads (also referred to herein as “underhung loads”) are problematic because they create wasted space in a truck and thereby increase shipping costs, and moreover, as the loads are inboard of the edges of the pallet, they can require more expensive packaging material and lower wrapping parameters to wrap, which can also increase overall costs.

Oversized loads (also referred to herein as “overhung loads”) are also problematic, however, because they can increase the overall size of a pallet to such an extent that loading and unloading of pallets into and out of a truck can be more difficult and cause scuff damage as the sides of the load slide along adjacent loads and/or the sides of the truck. While stretch wrapping itself can be used to compress a load at higher wrap forces, it has been found that wrapping these types of loads at higher wrap forces can lead to rounding of the loads as well as damage to the loads, e.g., crushing of the cardboard cores of paper towel or toilet paper rolls.

Therefore, a significant need continues to exist in the art for an improved manner of wrapping multi-unit bundles that is secure and space efficient.

The invention addresses these and other problems associated with the art by applying compressive forces across opposing sides of a palletized load either before, after, or during stretch wrapping to generate a load having a desirable shape profile once wrapped. The compressive forces may be used, for example, in some instances to overcompress a load in one or more lateral directions beyond desired finished dimensions, such that once the load is thereafter allowed to recover or relax, the load assumes the desired finished dimensions.

Therefore, consistent with one aspect of the invention, a method of generating a wrapped load having a first length in a first lateral direction may include receiving a load that is unwrapped and that has a second length in the first lateral direction that is larger than the first length in the first lateral direction, applying a compressive force to opposing sides of the load along the first lateral direction to compress the load to a third length in the first lateral direction that is smaller than the first length in the first lateral direction, wrapping the load with packaging material using a load wrapping apparatus by generating relative rotation between a packaging material dispenser and the load about an axis of rotation, and allowing the load to recover in the first lateral direction such that the load has the first length in the first lateral direction after the load has been wrapped with packaging material.

In some embodiments, the load is supported by a pallet, and the first length is substantially equal to a length of the pallet in the first lateral direction. Also, in some embodiments, applying the compressive force is performed prior to wrapping the load. Further, in some embodiments, applying the compressive force is performed after wrapping the load. In some embodiments, applying the compressive force is performed while wrapping the load. In addition, in some embodiments, applying the compressive force to the opposing sides of the load includes positioning opposing press members adjacent the opposing sides of the load, and wrapping the load is performed while the opposing press members are positioned adjacent the opposing sides of the load such that packaging material is wrapped over at least a portion of the opposing press members, and the method further includes withdrawing the opposing press members after wrapping the load. In some embodiments, withdrawing the opposing press members further includes engaging the load to restrict lifting of the load while withdrawing the opposing press members.

In addition, in some embodiments, applying the compressive force is performed while the load is supported by a conveyor. Moreover, in some embodiments, the opposing sides includes first and second sides, and applying the compressive force is performed using first and second opposing press members respectively contacting the first and second sides. In some embodiments, the first and second press members respectively contact the first and second sides substantially across at least about 50 percent of the second length. Moreover, in some embodiments, the first and second sides have respective first and second heights, and the first and second press members respectively contact the first and second sides across at least about 50 percent of the first and second heights. In some embodiments, the first and second press members respectively contact the first and second sides proximate midpoints of the first and second sides. In addition, in some embodiments, the first and second press members respectively include first and second planar surfaces that respectively contact the first and second sides.

In some embodiments, applying the compressive force includes moving the first and second press members a predetermined distance. Moreover, in some embodiments, applying the compressive force includes moving the first and second press members to apply a predetermined force to the load. In addition, some embodiments may further include determining at least one of a distance to move the first and second press members and a force to apply with the first and second press members based on the first and second lengths.

In some embodiments, the compressive force is a first compressive force and the opposing sides are a first set of opposing sides of the load, the method further includes generating the wrapped load to have a first width in a second lateral direction that is substantially perpendicular to the first lateral direction, and the load is received with a second width in the second lateral direction that is larger than the first width in the second lateral direction. Generating the wrapped load to have the first width in the second lateral direction includes applying a second compressive force to a second set of opposing sides of the load along the second lateral direction to compress the load to a third width in the second lateral direction that is smaller than the first width in the second lateral direction, and allowing the load to recover in the second lateral direction such that the load has the first width in the second lateral direction after the load has been wrapped with packaging material. In addition, in some embodiments, applying the first compressive force and applying the second compressive force are performed concurrently. Also, in some embodiments, applying the first compressive force and applying the second compressive force are performed sequentially.

Moreover, in some embodiments, the first set of opposing sides includes first and second sides and the second set of opposing sides includes third and fourth sides, and applying the first and second compressive forces is performed using first, second, third, and fourth press members respectively contacting the first, second, third, and fourth sides. Further, in some embodiments, the first, second, third, and fourth press members are supported by a support structure providing movement of the first and second press members substantially along the first lateral direction and movement of the third and fourth press members substantially along the second lateral direction. Also, in some embodiments, applying the first and second compressive forces is performed using at least one drive operably coupled to the first, second, third, and fourth press members to move the first and second press members along the first lateral direction to apply the first compressive force to the first set of opposing sides and to move the third and fourth press members along the second lateral direction to apply the second compressive force to the second set of opposing sides. Further, in some embodiments, the at least one drive includes at least one screw drive, at least one chain drive, at least one belt drive, at least one electric motor, at least one electric drive, at least one pneumatic drive, or at least one hydraulic actuator.

In some embodiments, the first, second, third, and fourth press members are configured to apply the first and second compressive forces while the load is disposed on a conveyor, the third and fourth press members each include at least one door movable between an open position and a closed position, and the method further includes, prior to applying the first and second compressive forces, moving the at least one door of the third press member to the open position when conveying the load along the conveyor to position the load between the first and second press members, and after applying the first and second compressive forces, moving the at least one door of the fourth press member to the open position when conveying the load along the conveyor downstream of the first and second press members. Some embodiments may also include, prior to applying the second compressive forces, moving the first, second, third, and fourth press members in a substantially vertical direction to respectively position the first, second, third, and fourth press members adjacent to the first, second, third, and fourth sides, and after applying the first and second compressive forces, moving the first, second, third, and fourth press members in an opposite substantially vertical direction.

Also, in some embodiments, the first and third sides of the load extend along a first corner of the load, and the first and third press members include a plurality of interleaved fingers extending laterally to constrain the first corner of the load when applying the first and second compressive forces. In some embodiments, the first and third sides of the load extend along a first corner of the load, and the first and third press members are movably coupled to a floating corner member that extends along the first corner to constrain the first corner of the load when applying the first and second compressive forces.

Further, in some embodiments, wrapping the load is performed after applying the compressive force and using a wrap profile that applies a first containment force to the load based upon compressed dimensions of the load during wrapping such that a second containment force that is higher than the first containment force is applied to the load after recovery of the load after wrapping. In some embodiments, wrapping the load is performed while applying the compressive force and using a wrap profile that applies a first containment force to the load based upon compressed dimensions of the load during wrapping such that a second containment force that is higher than the first containment force is applied to the load after recovery of the load after wrapping. Further, in some embodiments, wrapping the load is performed prior to applying the compressive force and using a wrap profile that applies a first containment force to the load based upon uncompressed dimensions of the load during wrapping such that a second containment force that is lower than the first containment force is applied to the load after recovery of the load after applying the compressive force.

Consistent with another aspect of the invention, a method of generating a wrapped load having a first length in a first lateral direction and a first width in a second lateral direction that is substantially perpendicular to the first lateral direction may include receiving a load that is unwrapped and that has a second length in the first lateral direction and a second width in the second lateral direction, applying a first compressive force to a first set of opposing sides of the load along the first lateral direction and a second compressive force to a second set of opposing sides of the load along the second lateral direction to compress the load to a third length in the first lateral direction and a third width in the second lateral direction, after applying and releasing the first and second compressive forces, wrapping the load with packaging material using a load wrapping apparatus by generating relative rotation between a packaging material dispenser and the load about an axis of rotation, and allowing the load to recover in the first and second lateral directions after wrapping the load such that the load has the first length in the first lateral direction and the first width in the second lateral direction after the load has been wrapped with packaging material.

Consistent with another aspect of the invention, a method of generating a wrapped load having a first length in a first lateral direction and a first width in a second lateral direction that is substantially perpendicular to the first lateral direction may include receiving a load that is unwrapped and that has a second length in the first lateral direction and a second width in the second lateral direction, applying a first compressive force to a first set of opposing sides of the load along the first lateral direction and a second compressive force to a second set of opposing sides of the load along the second lateral direction to compress the load to a third length in the first lateral direction and a third width in the second lateral direction, while applying the first and second compressive forces, wrapping the load with packaging material using a load wrapping apparatus by generating relative rotation between a packaging material dispenser and the load about an axis of rotation, and allowing the load to recover in the first and second lateral directions after wrapping the load such that the load has the first length in the first lateral direction and the first width in the second lateral direction after the load has been wrapped with packaging material.

Consistent with another aspect of the invention, a method of generating a wrapped load having a first length in a first lateral direction and a first width in a second lateral direction that is substantially perpendicular to the first lateral direction may include receiving a load that is unwrapped and that has a second length in the first lateral direction and a second width in the second lateral direction, wrapping the load with packaging material using a load wrapping apparatus by generating relative rotation between a packaging material dispenser and the load about an axis of rotation, after wrapping the load, applying a first compressive force to a first set of opposing sides of the load along the first lateral direction and a second compressive force to a second set of opposing sides of the load along the second lateral direction to compress the load to a third length in the first lateral direction and a third width in the second lateral direction, and allowing the load to recover in the first and second lateral directions after wrapping the load and applying the first and second compressive forces such that the load has the first length in the first lateral direction and the first width in the second lateral direction after the load has been wrapped with packaging material.

Consistent with another aspect of the invention, a system may be configured to generate a wrapped load having a first length in a first lateral direction from an unwrapped load having a second length in the first lateral direction. The system may include a load shaping apparatus including first and second opposing press members configured to engage respective first and second sides of the load and apply a compressive force across the first and second sides of the load along a first lateral direction of the load to compress the load to a third length in the first lateral direction that is smaller than the first length in the first lateral direction, and a load wrapping apparatus configured to wrap the load with packaging material by generating relative rotation between a packaging material dispenser and the load about an axis of rotation, and after the compressive force has been applied across the first and second sides of the load by the load shaping apparatus, the load has been wrapped by the load wrapping apparatus, and the load recovers in the first lateral direction, the load has the first length in the first lateral direction.

Also, in some embodiments, the load shaping apparatus is upstream of the load wrapping apparatus. In addition, in some embodiments, the load shaping apparatus is upstream of the load wrapping apparatus. In some embodiments, the load shaping apparatus is configured to apply the compressive force across the first and second sides of the load while the load is wrapped by the load wrapping apparatus.

Consistent with another aspect of the invention, a load shaping apparatus may be configured to compress a load supported on a pallet, where the load includes first and second sides opposing one another in a first lateral direction and third and fourth sides opposing one another in a second lateral direction that is substantially perpendicular to the first lateral direction, and the load when unwrapped has a length in the first lateral direction that is greater than that of the pallet and a width in the second lateral direction that is greater than that of the pallet. The load shaping apparatus may include first, second, third, and fourth press members respectively configured to engage the respective first, second, third, and fourth sides of the load, and at least one drive operably coupled to the first, second, third, and fourth press members and configured to actuate the first and second press members to apply a first compressive force across the first and second sides of the load along the first lateral direction of the load to compress the length of the load to be less than that of the pallet and actuate the third and fourth press members to apply a second compressive force across the third and fourth sides of the load along the second lateral direction of the load to compress the width of the load to be less than that of the pallet.

In addition, in some embodiments, the first and third sides of the load extend along a first corner of the load, and the first and third press members include a plurality of interleaved fingers extending laterally to constrain the first corner of the load when applying the first and second compressive forces. Also, in some embodiments, the first and third sides of the load extend along a first corner of the load, and the first and third press members are slidably coupled to a floating corner member that extends along the first corner to constrain the first corner of the load when applying the first and second compressive forces.

These and other advantages and features, which characterize the invention, are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which there is described example embodiments of the invention.

Embodiments consistent with the invention may apply compressive forces across opposing sides of a palletized load either before, after, or during stretch wrapping to generate a load having a desirable shape profile once wrapped.

In particular, as noted above, it is generally desirable in some stretch wrapping applications to generate a wrapped palletized load where the lateral dimensions of the load (e.g., length and/or width) substantially match those of the pallet supporting the load. Doing so maximizes the space utilization during shipping and storage, as well as minimizes scuff damage to loads when pallets are positioned next to one another. In addition, inboard or underhung loads can require lower wrap settings and require special packing material for wrapping, while overhung loads, if sufficiently overhung, can potentially inhibit the ability of adjacent loads to be loaded into or unloaded from a truck in some instances (e.g., where two 48″ wide loads are placed in a truck having a 98″ wide opening).

One such application is wrapping bundles of consumer paper products, such as paper towels and toilet paper. Such products are often shipped by palletizing and wrapping multi-unit bundles stacked in multiple layers on a pallet, and without the use of separate cardboard boxes to house the multi-unit bundles. The types of products and the bundling of those products, however, often can limit the maximum wrap force used to wrap the palletized bundles, as excessive wrap force can lead to deformation and/or crushing of the products, particularly at the corners of the load.

Embodiments consistent with the invention, on the other hand, may use a load shaping operation either before, after or during stretch wrapping to generate a load with a desirable shape profile, including desirable lateral shape and/or dimensions. A load shaping operation, in particular, may include the application of a compressive force across opposing sides of a load that compresses the sides in a lateral direction beyond a desired dimension such that subsequent recovery or relaxation of the load allows the sides of the load to expand partially back to the desirable dimension. In various embodiments, the compressive force may be applied across a single pair of opposing sides, although in other embodiments compressive forces (which may be the same or may be different) may be applied across multiple pairs of opposing sides, e.g., all four sides of a rectangular load. The compressive forces for different pairs of opposing sides may be applied concurrently or sequentially in different embodiments.

It has been found, in particular, that compression of some types of loads, e.g., loads incorporating multi-unit bundles of consumer paper products, exhibits a significant inelasticity in a recovery stress strain curve, such that by overcompressing a load enables a lower containment force to be used to contain the load with a desired shape profile. It will be appreciated that containment force, as used in the context of the disclosure, generally refers to the cumulative force exerted on a load by the packaging material wrapped around the load. Containment force depends on a number of factors, including the number of layers of packaging material, the thickness, strength and other properties of the packaging material, the amount of pre-stretch applied to the packaging material, and the wrap force applied to the load while wrapping the load. The wrap force, in contrast, is a force that fluctuates as packaging material is dispensed to the load due primarily to the irregular geometry of the load.

Moreover, it has been found that by compressing a load across opposing sides, rather than around the circumference or girth of the load (as is the case with wrapping packaging material around the load), the containment force may hold the load in a desired shape with reduced crushing forces on the load contents, particularly proximate the corners of the loads. For loads including paper rolls wound about cardboard cores, for example, reduced crushing may be exhibited on the cardboard cores, thereby reducing the likelihood of load damage.

, for example, illustrate an example load shaping and wrapping operation consistent with the invention, and performed on a palletized loadincluding an overhung load of products(e.g., multi-unit bundles) supported by a pallet. In this example, it is assumed that it is desirable to generate a wrapped load in which the lateral dimensions of loadare substantially equal to the lateral dimensions of pallet, although it should be appreciated that the desired lateral dimensions of a wrapped load in other embodiments may not correspond to the lateral dimensions of a pallet, and may be larger or smaller in different embodiments. In addition, it will be appreciated that the relationship between the initial load length, the pallet length, the compressed load length and the desired or final load length in the first lateral direction need not match that of the corresponding widths in the second lateral direction, as, for example, the degree of overhang in one lateral direction may differ from that in the other lateral direction in some instances.

It may be seen in, for example, that prior to shaping or wrapping, in a first lateral direction, e.g., a length direction, the loadhas a length Lthat is greater than a length Lof pallet, and in a second lateral direction, e.g., a width direction, the loadhas a width Wthat is greater than a width Wof pallet. It will be appreciated that the terms “length” and “width” are used herein to refer to orthogonal or perpendicular lateral dimensions of a load, and do not imply any particular orientation of the load, such that, for example, the length of a load could be greater than, the same as, or less than the width of the load in different embodiments.

illustrates the application of compressive forces F, Fto opposing sides of load. Compressive force F, for example, is applied along the first lateral direction (i.e., the length direction) to compress loadto a length Lthat is smaller than the length Lof pallet, while compressive force Fis applied along the second lateral direction (i.e., the width direction) to compress loadto a width Wthat is smaller than the width Wof pallet. It will be appreciated that the compressive forces may be applied concurrently or sequentially in different embodiments. Moreover, in some embodiments, a compressive force may be applied only to one pair of opposing sides, e.g., if the dimension of the load in one lateral direction is substantially equal to or less than the dimension of the pallet in that lateral direction. In addition, in some embodiments, it may be desirable to not have the final dimensions of the load be centered within the pallet confines, e.g., using either unequal opposing forces or offsetting the centerline of the load shaping apparatus relative to the centerline of the pallet to provide an offset load footprint.

illustrates palletized loadafter the application of compressive forces Fand F, as well as after wrapping the load with packaging materialand allowing loadto recover in both lateral directions. It will be appreciated that loadhas recovered or relaxed to a length Lthat is substantially the same as the length Lof palletand a width Wthat is substantially the same as the width Wof pallet. Moreover, due to the inelasticity of the load after compression, the containment force required to maintain the load with the final or desired dimensions is substantially reduced relative to that which would be required were the load wrapped without compressive forces being applied.

The sequence in which a load is shaped, wrapped, and allowed to recover may vary in different embodiments, and may include load shaping that is performed before, after, or concurrently with load wrapping., for example, illustrates one example load shaping and wrapping systemin which an unwrapped load is generated by a palletizer or unit load formerand conveyed by a conveyorto a load shaping apparatusthat is configured to apply compressive forces to one or both pairs of opposing sides of the load along one or two lateral directions. The load is then conveyed by a conveyorto a load wrapping apparatusto wrap the load with packaging material by generating relative rotation between a packaging material dispenser and the load about an axis of rotation. The shaped and wrapped load may then be conveyed by a conveyorto an exit pointfor storage or shipping. Depending on the spring rate of the load, recovery or relaxation of the load may occur for a variable amount of time subsequent to the application of compressive forces, and in some instances, may continue while and/or after the load is wrapped by load wrapping apparatus. In addition, it will be appreciated that wrapping of the load may be configured with wrap settings that apply a containment force based on the desired or final lateral dimensions of the load.

It will also be appreciated that conveyors,,may be separate conveyors in some embodiments, or may be portions of a single conveyor. In addition, load shaping and/or load wrapping may be performed while the load (and pallet) are supported on a conveyor. Other manners of conveying a load between different machinery or stations may be used in other embodiments.

, as another example, illustrates a load shaping and wrapping systemin which an unwrapped load is generated by a palletizer or unit load formerand conveyed by a conveyorto a load wrapping apparatusto wrap the load with packaging material by generating relative rotation between a packaging material dispenser and the load about an axis of rotation. The load is then conveyed by a conveyorto a load shaping apparatusthat is configured to apply compressive forces to one or both pairs of opposing sides of the load along one or two lateral directions. The shaped and wrapped load may then be conveyed by a conveyorto an exit pointfor storage or shipping. In such an embodiment, wrapping of the load may be configured with wrap settings that are configured to apply a desired containment force for the final or desired lateral dimensions of the load (rather than the initial lateral dimensions of the unwrapped load) such that once the wrapped load is shaped via the application of compressive forces, the desired containment force will be achieved.

, as another example, illustrates a load shaping and wrapping systemin which an unwrapped load is generated by a palletizer or unit load formerand conveyed by a conveyorto a combined load shaping and wrapping apparatusincluding both a load shaping apparatusand a load wrapping apparatus, whereby the load wrapping apparatuswraps the load with packaging material by generating relative rotation between a packaging material dispenser and the load about an axis of rotation while load shaping apparatusapplies compressive forces to one or both pairs of opposing sides of the load along one or two lateral directions. The shaped and wrapped load may then be conveyed by a conveyorto an exit pointfor storage or shipping. In such an embodiment, wrapping of the load may again be configured with wrap settings that are configured to apply a desired containment force for the final or desired lateral dimensions of the load to accommodate the recovery or relaxation of the load after shaping and wrapping is complete.

It will be appreciated that, in some embodiments, when wrapping of the load is performed after or while applying compressive forces, it may be desirable to use a wrap profile that applies a containment force to the load based upon the compressed dimensions of the load during wrapping such that a relatively higher containment force is applied to the load after recovery of the load after wrapping.

In addition, in some embodiments, when wrapping of the load is performed prior to applying compressive forces, it may be desirable to use a wrap profile that applies a containment force to the load based upon uncompressed dimensions of the load during wrapping such that relatively lower containment force is applied to the load after recovery of the load after applying the compressive force.

It will also be appreciated that compressive forces may also be applied on the top of a load (i.e., in a generally vertical direction) during a load shaping operation in some embodiments, e.g., to lower the height of the load and/or to otherwise assist in forming a desired load shape. Furthermore, where multiple palletized loads are stacked on top of one another, compressive forces may be applied in a generally vertical direction in some embodiments to lower the overall height of the stacked loads. In addition, in some embodiments, the application of compressive forces in one or more lateral directions may be performed concurrently for two or more palletized loads that are stacked on top of one another. Moreover, in some embodiments, compressive forces may be applied at multiple times, e.g., both before and after wrapping.

Further details regarding the load wrapping apparatus and the load shaping apparatus used to implement the aforementioned operations are provided below.

Various load wrapping apparatus configurations may be used in various embodiments of the invention, e.g., to implement any of load wrapping apparatuses,, andof. For example,illustrates a rotating arm-type wrapping apparatus, which includes a roll carriage or elevatormounted on a rotating arm. Roll carriagemay include a packaging material dispenser. Packaging material dispensermay be configured to dispense packaging materialas rotating armrotates relative to a loadto be wrapped. In an example embodiment, packaging material dispensermay be configured to dispense stretch wrap packaging material. As used herein, stretch wrap packaging material is defined as material having a high yield coefficient to allow the material a large amount of stretch during wrapping. However, it is possible that the apparatuses and methods disclosed herein may be practiced with packaging material that will not be pre-stretched prior to application to the load. Examples of such packaging material include netting, strapping, banding, tape, etc. The invention is therefore not limited to use with stretch wrap packaging material. In addition, as used herein, the terms “packaging material,” “web,” “film,” “film web,” and “packaging material web” may be used interchangeably.

Packaging material dispensermay include a pre-stretch assemblyconfigured to pre-stretch packaging material before it is applied to loadif pre-stretching is desired, or to dispense packaging material to loadwithout pre-stretching. Pre-stretch assemblymay include at least one packaging material dispensing roller, including, for example, an upstream dispensing rollerand a downstream dispensing roller. It is contemplated that pre-stretch assemblymay include various configurations and numbers of pre-stretch rollers, drive or driven roller and idle rollers without departing from the spirit and scope of the invention.

The terms “upstream” and “downstream,” as used in this application, are intended to define positions and movement relative to the direction of flow of packaging materialas it moves from packaging material dispenserto load. Movement of an object toward packaging material dispenser, away from load, and thus, against the direction of flow of packaging material, may be defined as “upstream.” Similarly, movement of an object away from packaging material dispenser, toward load, and thus, with the flow of packaging material, may be defined as “downstream.” Also, positions relative to load(or a load support surface) and packaging material dispensermay be described relative to the direction of packaging material flow. For example, when two pre-stretch rollers are present, the pre-stretch roller closer to packaging material dispensermay be characterized as the “upstream” roller and the pre-stretch roller closer to load(or load support) and further from packaging material dispensermay be characterized as the “downstream” roller.

A packaging material drive system, including, for example, an electric motor, may be used to drive dispensing rollersand. For example, electric motormay rotate downstream dispensing roller. Downstream dispensing rollermay be operatively coupled to upstream dispensing rollerby a chain and sprocket assembly, such that upstream dispensing rollermay be driven in rotation by downstream dispensing roller. Other connections may be used to drive upstream rolleror, alternatively, a separate drive (not shown) may be provided to drive upstream roller. Moreover, in some embodiments the roll of packaging materialmay be undriven and may rotate freely, while in other embodiments the roll may be driven, e.g., by biasing a surface of the roll against upstream dispensing rolleror another driven roller, or by driving the roll directly.

Downstream of downstream dispensing rollermay be provided one or more idle rollers,that redirect the web of packaging material, with the most downstream idle rollereffectively providing an exit pointfrom packaging material dispenser, such that a portionof packaging materialextends between exit pointand a contact pointwhere the packaging material engages load(or alternatively contact point′ if loadis rotated in a counter-clockwise direction).

Load wrapping apparatusalso includes a relative rotation assemblyconfigured to rotate rotating arm, and thus, packaging material dispensermounted thereon, relative to loadas loadis supported on load support surface. Relative rotation assemblymay include a rotational drive system, including, for example, an electric motor. It is contemplated that rotational drive systemand packaging material drive systemmay run independently of one another. Thus, rotation of dispensing rollersandmay be independent of the relative rotation of packaging material dispenserrelative to load. This independence allows a length of packaging materialto be dispensed per a portion of relative revolution that is neither predetermined nor constant. Rather, the length may be adjusted periodically or continuously based on changing conditions. In other embodiments, however, packaging material dispensermay be driven proportionally to the relative rotation, or alternatively, tension in the packaging material extending between the packaging material dispenser and the load may be used to drive the packaging material dispenser.

Load wrapping apparatusmay further include a lift assembly. Lift assemblymay be powered by a lift drive system, including, for example, an electric motor, that may be configured to move roll carriagevertically relative to load. Lift drive systemmay drive roll carriage, and thus packaging material dispenser, generally in a direction parallel to an axis of rotation between the packaging material dispenserand loadand load support surface. For example, for load wrapping apparatus, lift drive systemmay drive roll carriageand packaging material dispenserupwards and downwards vertically on rotating armwhile roll carriageand packaging material dispenserare rotated about loadby rotational drive system, to wrap packaging material spirally about load.

One or more of downstream dispensing roller, idle rollerand idle rollermay include a corresponding sensor,,to monitor rotation of the respective roller. In particular, rollers,and/or, and/or packaging materialdispensed thereby, may be used to monitor a dispense rate of packaging material dispenser, e.g., by monitoring the rotational speed of rollers,and/or, the number of rotations undergone by such rollers, the amount and/or speed of packaging material dispensed by such rollers, and/or one or more performance parameters indicative of the operating state of packaging material drive system, including, for example, a speed of packaging material drive system. The monitored characteristics may also provide an indication of the amount of packaging materialbeing dispensed and wrapped onto load. In addition, in some embodiments a sensor, e.g., sensoror, may be used to detect a break in the packaging material.