Stretch Film Wrapping and Unwrapping for Recycling And/Or Reuse Applications

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 of goods in commerce. One system uses stretch wrapping machines, also referred to herein as stretch wrappers or stretch wrapping apparatuses, to stretch, dispense, and wrap a polymer-based packaging material, e.g., stretch film, around a load. The polymer-based packaging material may also 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.

Worldwide sensitivity to sustainability has increased interest in reducing or eliminating the single use and disposal of polymer packaging materials. Non-polymer alternatives such as paper have been considered; however, the stretchability of these non-polymer alternatives is generally less than that provided by polymer-based packaging materials, and wrapping a load with materials exhibiting limited stretchability presents a number of concerns with respect to puckering and tears. In addition, polymer-based packaging materials incorporating recycled content have also been considered, although it has been found that the incorporation of recycled content can significantly reduce the performance of a packaging material as compared to virgin polymer packaging material. Moreover, regardless of the technology, all of these different alternative materials are still typically disposed of once the load is unwrapped at its ultimate destination.

While improvements in stretch wrapping technology over the decades have substantially reduced the costs and environmental impacts of stretch wrapping, there is a continuing desire to further improve sustainability. Various jurisdictions around the world, for example, are focusing regulatory efforts on reusability and limiting the use of single-use materials, including single-use materials utilized for the transportation of goods.

A need therefore exists in the art for systems and methods capable of securing and transporting palletized loads with reduced usage of single-use materials.

In addition, regardless of the type of material used to wrap a load, whenever it is time to access the individual unit products in the load, the material wrapped around the load generally must be removed. Conventionally, the material is removed by manually cutting through the material on one side of the load and then removing the material as a single bundle. Efforts have been made to develop machinery for automating the process; however, such efforts have generally utilized robotics to mimic the manual process, and have generally been complex, expensive, and slow.

Therefore, a need also continues to exist in the art for systems and methods capable of efficiently removing the material used to wrap a load.

The invention addresses these and other problems associated with the prior art by providing various stretch wrapping apparatus and/or unwrapping apparatus designs for use in recycling and/or reuse applications. In recycling applications, for example, various unwrapping apparatus designs may be utilized to collect stretch film spirally wrapped around a load, generally by unwrapping the stretch film over the course of multiple revolutions. In reuse applications, as another example, various stretch wrapping apparatus designs may be used to wrap stretch film around a load in a manner that conditions the stretch film for reusability, while various unwrapping apparatus designs may be utilized to collect the stretch film from a load into a roll form that is suitable for use in wrapping other loads.

Therefore, consistent with one aspect of the invention, an unwrapping apparatus may include a collection roller rotatable about a first axis of rotation, the collection roller sized and configured to collect a plurality of lengths of stretch film, each length of stretch film of the plurality of lengths of stretch film collected from a respective load of a plurality of loads, and a rotational drive configured to, for each respective load of the plurality of loads, generate relative rotation between the collection roller and the respective load about a second axis of rotation to collect the respective length of stretch film from the respective load with the collection roller over a plurality of relative rotations between the respective load and the collection roller.

In some embodiments, the first axis of rotation is substantially parallel to the second axis of rotation while the rotational drive generates the relative rotation between the collection roller and the load. In addition, some embodiments may further include a rotating arm, and the collection roller is supported on the rotating arm and the rotational drive is configured to rotate the rotating arm around the load and about the second axis of rotation. Some embodiments may further include a turntable supporting the load, and the collection roller is supported on a mast and the rotational drive is configured to rotate the turntable and thereby rotate the load about the second axis of rotation. Further, in some embodiments, the first axis of rotation is substantially vertical and the collection roller is maintained at a predetermined elevation while unwrapping the stretch film from the load.

In some embodiments, the length of stretch film collected from each respective load of the plurality of loads is spirally wrapped around the respective load throughout a wrapped region of the respective load, and the collection roller has a length along the first axis of rotation that is at least as long as a distance between opposing edges of the wrapped region of each respective load of the plurality of loads. In addition, in some embodiments, the length of stretch film collected from each respective load of the plurality of loads is spirally wrapped around the respective load, and the collection roller has a length along the first axis of rotation that is at least about twice the width of the length of stretch film collected from each respective load. Some embodiments may also include a film guide disposed proximate an end of the collection roller and configured to redirect stretch film collected from at least one of the plurality of loads to within a predetermined region of the collection roller.

In some embodiments, the collection roller is further pivotable between unwrapping and unloading positions about a pivot axis that is substantially perpendicular to the first axis of rotation, and the first axis of rotation is substantially parallel to the second axis of rotation when the collection roller is in the unwrapping position. In addition, in some embodiments, the collection roller includes a stretch film removal end that allows removal, from the collection roller, of a roll of stretch film collected on the collection roller through axial movement of the roll of stretch film along the first axis of rotation and in a direction of the stretch film removal end of the collection roller.

In addition, some embodiments may further include a roller drive configured to drive rotation of the collection roller, a drive member operably coupled to the roller drive, and a driven member operably coupled to the collection roller, the driven member configured to engage the drive member when the collection roller is in the unwrapping position such that operation of the roller drive causes rotation of the collection roller, and to disengage from the drive member when the collection roller is in the unloading position. In some embodiments, the driven member is disposed at the stretch film removal end of the collection roller and is sized to pass through an interior channel of the roll of stretch film during removal of the roll of stretch film from the collection roller. Moreover, in some embodiments, the first and second axes of rotation are substantially vertical, and the roller drive and drive member are positioned proximate a top of the collection roller when the collection roller is in the unwrapping position. In some embodiments, the roller drive includes a motor and is independently controlled from the rotational drive.

Some embodiments may also include a roller bracket configured to rotatably support a first end of the collection roller for rotation of the collection roller about the first axis of rotation, and a roller support configured to pivotably support the roller bracket for pivoting of the collection roller between unwrapping and unloading positions about a pivot axis that is substantially perpendicular to the first axis of rotation, and when the collection roller is in the unwrapping position, the roller bracket is configured to support an opposing second end of the collection roller, and the roller bracket is configured to disengage from the second end of the collection roller when the collection roller is in the unloading position to allow removal, from the collection roller, of a roll of stretch film collected on the collection roller through axial movement of the roll of stretch film along the first axis of rotation and in a direction of the second end of the collection roller.

In addition, in some embodiments, the roller bracket includes first and second bracket members coupled to one another and respectively configured to support the first and second ends of the collection roller, and the second bracket member is movable relative to the first bracket member to disengage from the second end of the collection roller when the collection roller is in the unloading position.

In some embodiments, the collection roller has a collapsible core that is configured to be in an extended configuration during operation of the rotational drive such that a roll of stretch film is collected on the collection roller during the relative rotation while the collapsible core is in the extended configuration, and is movable to a collapsed configuration to reduce a cross-sectional size of the collection roller and thereby allow for removal of the roll of stretch film from the collection roller through axial movement of the roll of stretch film along the first axis of rotation. Moreover, in some embodiments, the collection roller is further pivotable between unwrapping and unloading positions about a pivot axis that is substantially perpendicular to the first axis of rotation, the collection roller is configured in the extended configuration when in the unwrapping position, and the collection roller is configured to move to the collapsed configuration in response to movement of the collection roller to the unloading position. Also, in some embodiments, the collection roller is movable between the extended and collapsed configurations in response to movement of the roll of stretch film along the first axis of rotation. In some embodiments, the collection roller includes a plurality of faces coupled to a shaft member through a plurality of collapsible couplers, each collapsible coupler includes a track and a cam follower configured to follow the track, and the track of each collapsible coupler includes an angled portion that includes both axial and radial components to move the plurality of faces both axially and radially when moving from the extended configuration to the collapsed configuration.

Consistent with another aspect of the invention, an unwrapping apparatus for unwrapping a load having stretch film spirally wrapped around the load may include a collection roller rotatable about a first axis of rotation, and a rotational drive configured to generate relative rotation between the collection roller and the load about a second axis of rotation to collect the stretch film with the collection roller over a plurality of relative rotations between the load and the collection roller. The collection roller includes a collapsible core that is configured to be in an extended configuration during operation of the rotational drive such that a roll of stretch film is collected on the collection roller during the relative rotation while the collapsible core is in the extended configuration, and is movable to a collapsed configuration to reduce a cross-sectional size of the collection roller and thereby allow for removal of the roll of stretch film from the collection roller through axial movement of the roll of stretch film along the first axis of rotation.

In addition, in some embodiments, the collection roller is further pivotable between unwrapping and unloading positions about a pivot axis that is substantially perpendicular to the first axis of rotation, the collection roller is configured in the extended configuration when in the unwrapping position, and the collection roller is configured to move to the collapsed configuration in response to movement of the collection roller to the unloading position. Also, in some embodiments, the collection roller is movable between the extended and collapsed configurations under the influence of gravity when the collection roller is in the unloading position. Moreover, in some embodiments, the collection roller is movable between the extended and collapsed configurations in response to movement of the roll of stretch film along the first axis of rotation.

Further, in some embodiments, the collection roller includes a plurality of faces coupled to a shaft member through a plurality of collapsible couplers. Also, in some embodiments, each collapsible coupler includes a track and a cam follower configured to follow the track. Further, in some embodiments, the track of each collapsible coupler includes an angled portion that includes both axial and radial components to move the plurality of faces both axially and radially when moving from the extended configuration to the collapsed configuration. Some embodiments may further include an electronically-controlled roller actuator configured to move the collection roller between the extended and collapsed configurations.

Consistent with another aspect of the invention, an unwrapping apparatus for unwrapping a load having stretch film spirally wrapped around the load may include a collection roller rotatable about a first axis of rotation, a rotational drive configured to generate relative rotation between the collection roller and the load about a second axis of rotation to collect the stretch film with the collection roller over a plurality of relative rotations between the load and the collection roller, and a roller support configured to pivotably support the collection roller for movement between unwrapping and unloading positions about a pivot axis that is substantially perpendicular to the first axis of rotation. When in the unwrapping position, the collection roller is oriented to collect the stretch film during the relative rotation between the collection roller and the load, and when in the unloading position, the collection roller is oriented for removal of the collected stretch film from the collection roller through axial movement of the collected stretch film along the first axis of rotation.

In some embodiments, the first axis of rotation is substantially parallel to the second axis of rotation when the collection roller is in the unwrapping position. Also, in some embodiments, the collection roller includes a stretch film removal end that allows removal, from the collection roller, of a roll of stretch film collected on the collection roller through axial movement of the roll of stretch film along the first axis of rotation and in a direction of the stretch film removal end of the collection roller.

Some embodiments may also include a roller drive configured to drive rotation of the collection roller, a drive member operably coupled to the roller drive, and a driven member operably coupled to the collection roller, the driven member configured to engage the drive member when the collection roller is in the unwrapping position such that operation of the roller drive causes rotation of the collection roller, and to disengage from the drive member when the collection roller is in the unloading position.

In some embodiments, each of the drive member and the driven member is a contact friction roller. Further, in some embodiments, each of the drive member and the driven member is a gear. In some embodiments, the driven member is disposed at the stretch film removal end of the collection roller and is sized to pass through an interior channel of the roll of stretch film during removal of the roll of stretch film from the collection roller. Further, in some embodiments, the driven member is disposed at an opposite end of the collection roller from the stretch film removal end of the collection roller.

Also, in some embodiments, the first and second axes of rotation are substantially vertical, and the roller drive and drive member are positioned proximate a top of the collection roller when the collection roller is in the unwrapping position. In addition, in some embodiments, the roller drive includes a motor and is independently controlled from the rotational drive. In some embodiments, the roller drive is mechanically linked to the rotational drive to rotate the collection roller in response to the relative rotation generated between the collection roller and the load.

Some embodiments may also include a roller bracket configured to rotatably support a first end of the collection roller for rotation of the collection roller about the first axis of rotation, and a roller support configured to pivotably support the roller bracket for pivoting of the collection roller between unwrapping and unloading positions about a pivot axis that is substantially perpendicular to the first axis of rotation.

In addition, in some embodiments, when the collection roller is in the unwrapping position, the roller bracket is configured to support an opposing second end of the collection roller. Also, in some embodiments, the roller bracket is configured to disengage from the second end of the collection roller when the collection roller is in the unloading position to allow removal, from the collection roller, of a roll of stretch film collected on the collection roller through axial movement of the roll of stretch film along the first axis of rotation and in a direction of the second end of the collection roller.

In addition, in some embodiments, the roller bracket includes first and second bracket members coupled to one another and respectively configured to support the first and second ends of the collection roller, and the second bracket member is movable relative to the first bracket member to disengage from the second end of the collection roller when the collection roller is in the unloading position. In addition, some embodiments may also include a cam arrangement operably coupled to the second bracket member and configured to move the second bracket member relative to the first bracket member in response to movement of the collection roller between the unwrapping and unloading positions. In some embodiments, the cam arrangement includes a track and a cam follower configured to follow the track, the track coupled to one of the roller support and the second bracket member and the cam follower coupled to the other of the roller support and the second bracket member such that the cam follower follows the track in response to movement of the collection roller between the unwrapping and unloading positions.

Consistent with another aspect of the invention, an unwrapping apparatus for unwrapping a load having stretch film spirally wrapped around the load throughout a wrapped region of the load may include a collection roller rotatable about a first axis of rotation and having a length along the first axis of rotation that is at least as long as a distance between opposing edges of the wrapped region of the load, and a rotational drive configured to generate relative rotation between the collection roller and the load about a second axis of rotation to collect the stretch film with the collection roller over a plurality of relative rotations between the load and the collection roller.

Further, in some embodiments, the collection roller has a length along the first axis of rotation that is at least about 80 inches. In addition, in some embodiments, the collection roller has a length along the first axis of rotation that is at least about 110 inches. Further, in some embodiments, the collection roller has a length along the first axis of rotation that is at least about twice the width of a web of the stretch film collected from the load. Some embodiments may further include a film guide disposed proximate an end of the collection roller and configured to redirect the stretch film collected from the load to within a predetermined region of the collection roller.

Consistent with another aspect of the invention, a method of unwrapping a plurality of lengths of stretch film from a plurality of loads, with each length of stretch film of the plurality of lengths of stretch film spirally wrapped around a respective load of the plurality of loads, may include, for each respective load of the plurality of loads, generating relative rotation between a collection roller and the respective load about a first axis of rotation, and while generating the relative rotation, rotating the collection roller about a second axis of rotation over a plurality of relative rotations between the respective load and the collection roller to collect the respective length of stretch film from the respective load. The plurality of lengths of stretch film form a roll of stretch film collected on the collection roller, and for a first load of the plurality of loads that is unwrapped after the respective length of stretch film for at least one other load of the plurality of loads has been collected onto the roll of stretch film on the collection roller, a leading end of the respective length of stretch film for the first load is secured to the roll of stretch film prior to generating the relative rotation between the collection roller and the first load such that rotation of the collection roller during the relative rotation winds the respective length of stretch film for the first load onto the roll of stretch film collected on the collection roller.

Some embodiments may also include recycling the roll of stretch film collected on the collection roller. In addition, some embodiments may further include forming a supply roll of stretch film using the roll of stretch film collected on the collection roller for reuse in wrapping one or more additional loads. Further, in some embodiments, the plurality of lengths of stretch film are collected from the plurality of loads and removed from the collection roller without cutting any of the plurality of lengths of stretch film.

Consistent with another aspect of the invention, a stretch film supply roll may include a plurality of lengths of stretch film wound into a roll form, and a plurality of lap seals joining together adjacent lengths of stretch film from the plurality of lengths of stretch film to form a continuous web of stretch film on the roll form.

In addition, in some embodiments, first and second lengths of the plurality of lengths are formed of different film material. Also, in some embodiments, first and second lengths of the plurality of lengths are manufactured by different manufacturers. Moreover, in some embodiments, first and second lengths of the plurality of lengths have different thicknesses.

In some embodiments, each of the plurality of lengths of stretch film is a used length of stretch film that has previously been used to wrap a load. Further, in some embodiments, each of the plurality of lengths of stretch film has been used to wrap a different load. Also, in some embodiments, each of the plurality of lengths of stretch film has previously been controllably elongated when wrapping a load. Further, in some embodiments, each of the plurality of lengths of stretch film has previously been controllably elongated substantially below a yield point of such length of stretch film.

Also, in some embodiments, a first length of stretch film of the plurality of lengths of stretch film includes a cumulative elongation gauge disposed on a surface thereof. In addition, in some embodiments, the cumulative elongation gauge is formed on the first length of stretch film with a predetermined dimension along an elongation direction of the stretch film supply roll such that a current elongation of the first length of stretch film is determinable based on a measurement of a current dimension of the cumulative elongation gauge along the elongation direction of the stretch film supply roll. Moreover, in some embodiments, the cumulative elongation gauge is formed on the first length of stretch film prior to first use of the first length of stretch film to wrap a load. In some embodiments, the cumulative elongation gauge is formed on the first length of stretch film during manufacture of the first length of stretch film. Further, in some embodiments, the cumulative elongation gauge includes a plurality of marks separated from one another along the elongation direction of the stretch film supply roll by the predetermined dimension. In some embodiments, the cumulative elongation gauge includes a plurality of shapes having the predetermined dimension along the elongation direction of the stretch film supply roll.

Some embodiments may further include a core about which the plurality of lengths of stretch film are wound, and the roll form is defined by the core. Further, in some embodiments, the core is cylindrical. In some embodiments, the stretch film supply roll is a coreless roll. Also, in some embodiments, a first length of stretch film of the plurality of lengths of stretch film is a used length of stretch film that has previously been used to wrap a load and includes a tail mark formed thereon during wrapping the load to indicate a tail location.

Moreover, in some embodiments, a first lap seal of the plurality of lap seals is a pressed, clamped, rolled, wiped, or heated lap seal. In addition, in some embodiments, a first lap seal of the plurality of lap seals includes an adhesive. Also, in some embodiments, a first lap seal of the plurality of lap seals overlaps an underlying layer of stretch film on the stretch film supply roll, and the first lap seal and/or the overlapped layer includes a treated surface that reduces adherence between the first lap seal and the overlapped layer. In some embodiments, the treated surface is an abraded surface. In addition, in some embodiments, the treated surface is a powder treated surface. Also, in some embodiments, the treated surface is a liquid treated surface.

Consistent with another aspect of the invention, a stretch film supply roll may include a plurality of lengths of stretch film wound into a roll form, each of the plurality of lengths of stretch film collected from a respective load of a plurality of loads, and at least two of the plurality of lengths of stretch film having different thicknesses and/or formed of different film material, and a plurality of lap seals joining together adjacent lengths of stretch film from the plurality of lengths of stretch film to form a continuous web of stretch film on the roll form.

Consistent with another aspect of the invention, a stretch film supply roll may include a plurality of lengths of stretch film wound into a roll form, and a plurality of lap seals joining together adjacent lengths of stretch film from the plurality of lengths of stretch film to form a continuous web of stretch film on the roll form, and for a first lap seal of the plurality of lap seals, adherence of the first lap seal to a first length of stretch film among the plurality of lengths of stretch film that is at least partially overlapped by the first lap seal is reduced.

Consistent with yet another aspect of the invention, an unwrapping apparatus for unwrapping a load having stretch film spirally wrapped around the load may include a take up device configured to collect stretch film unwrapped from the load, and a rotational drive configured to generate relative rotation between the take up device and the load about an axis of rotation to collect the stretch film with the take up device over a plurality of relative rotations between the load and the take up device.

In some embodiments, the rotational drive is configured to generate relative rotation between the take up device and the load about the axis of rotation to spirally unwrap the stretch film from the load. Moreover, in some embodiments, the rotational drive is configured to generate relative rotation between the take up device and the load about the axis of rotation to unwrap the stretch film from the load as a continuous web of stretch film. In some embodiments, the take up device is configured to collect the stretch film unwrapped from the load into a roll of stretch film. Also, in some embodiments, the take up device is configured to collect the stretch film unwrapped from the load into the roll of stretch film by winding the collected stretch film into a roll form.

Moreover, in some embodiments, the take up device is configured to wind the collected stretch film into the roll form by rolling the collected stretch film onto a core. Further, in some embodiments, the core is sized and configured for use as a supply roll in a stretch film wrapping apparatus.

In addition, in some embodiments, the stretch film unwrapped from the load includes a first length of stretch film, and the take up device is configured to wind the collected stretch film into the roll form after a lap seal is formed between an end of the first length of stretch film and an end of a second length of stretch film that has previously been wound into the roll form. Further, in some embodiments, the lap seal joins the first and second lengths of stretch film into a continuous web of stretch film. In some embodiments, the take up device is configured to form the lap seal between the first and second lengths of stretch film. In addition, in some embodiments, the take up device is configured to treat the lap seal by pressing, clamping, rolling, wiping, heating and/or applying adhesive to the lap seal. Moreover, in some embodiments, the take up device is configured to treat a portion of the lap seal and/or a portion of the roll form overlapped by the lap seal to reduce adhesion of the lap seal to the portion of the roll form.

In addition, in some embodiments, the axis of rotation is a first axis of rotation, the stretch film is spirally wrapped around the load throughout a wrapped region of the load, and the take up device includes a collection roller rotatable about a second axis of rotation and having a length along the second axis of rotation that is at least as long as a distance between opposing edges of the wrapped region of the load. Moreover, in some embodiments, the take up device includes a film windup carriage configured for movement along a generally vertical direction to align with the stretch film during unwrapping. Further, in some embodiments, at least a portion of the film windup carriage is tiltable to align with the stretch film during unwrapping. Some embodiments may also include a carriage drive configured to move the film windup carriage along the generally vertical direction, at least one sensor for sensing alignment of the stretch film during unwrapping, and a controller coupled to the carriage drive and the at least one sensor and configured to control an elevation and/or tilt of the film windup carriage in response to the sensor.

Consistent with another aspect of the invention, a method of unwrapping a load having stretch film spirally wrapped around the load may include generating relative rotation between a take up device and the load about an axis of rotation, and while generating the relative rotation, collecting the stretch film with the take up device over a plurality of relative rotations between the load and the take up device.

Also, in some embodiments, generating the relative rotation between the take up device and the load about the axis of rotation spirally unwraps the stretch film from the load. In addition, in some embodiments, generating the relative rotation between the take up device and the load about the axis of rotation unwraps the stretch film from the load as a continuous web of stretch film. In some embodiments, collecting the stretch film with the take up device includes collecting the stretch film into a roll of stretch film by winding the collected stretch film into a roll form. Also, in some embodiments, winding the collected stretch film into the roll form includes rolling the collected stretch film onto a core sized and configured for use as a supply roll in a stretch film wrapping apparatus.

Moreover, in some embodiments, the stretch film unwrapped from the load includes a first length of stretch film, and winding the collected stretch film into the roll form is performed after a lap seal is formed between an end of the first length of stretch film and an end of a second length of stretch film that has previously been wound into the roll form. In addition, in some embodiments, the lap seal joins the first and second lengths of stretch film into a continuous web of stretch film. Some embodiments may also include forming the lap seal between the first and second lengths of stretch film. In addition, some embodiments may further include treating the lap seal by pressing, clamping, rolling, wiping, heating and/or applying adhesive to the lap seal. Some embodiments may also include treating a portion of the lap seal and/or a portion of the roll form overlapped by the lap seal to reduce adhesion of the lap seal to the portion of the roll form.

Also, in some embodiments, the take up device includes a collection roller having a vertical extent that is at least as long as a distance between a topmost edge and a bottommost edge of the stretch film spirally wrapped around the load, and winding the collected stretch film into the roll form includes winding the collected stretch film onto the collection roller. In some embodiments, the take up device includes a film windup carriage configured for movement along a generally vertical direction to align with the stretch film during unwrapping, the method further including moving the film windup carriage along the generally vertical direction while generating the relative rotation between the take up device and the load. In addition, some embodiments may also include sensing alignment of the stretch film during unwrapping using at least one sensor, and in response to sensing the alignment of the stretch film, controlling an elevation and/or tilt of the film windup carriage while generating the relative rotation between the take up device and the load.

Consistent with another aspect of the invention, an unwrapping apparatus for unwrapping a load having stretch film spirally wrapped around the load may include a take up device configured to collect stretch film unwrapped from the load, a rotational drive configured to generate relative rotation between the take up device and the load about an axis of rotation, a lift drive configured to control an elevation of the take up device relative to the load, an alignment sensor for sensing alignment of a web of the stretch film extending between the load and the take up device, and a controller coupled to the rotational drive, the lift drive, and the alignment sensor, the controller configured to control the rotational drive to generate the relative rotation to collect the stretch film with the take up device over a plurality of relative rotations between the load and the take up device, the controller further configured to control the elevation of the take up device during the relative rotation in response to the alignment sensor.

Further, in some embodiments, the alignment sensor includes an edge detection sensor configured to detect an edge of the web of stretch film. In addition, in some embodiments, the edge detection sensor includes an ultrasonic array including a plurality of ultrasonic sensors arranged in an array and positioned to detect the web of stretch film such that the edge of the web of stretch film is detected based upon which of the plurality of ultrasonic sensors detects the web of stretch film. Further, in some embodiments, the edge detection sensor further includes opposing first and second members that define a gap, each ultrasonic sensor includes a transmitter disposed on one of the opposing first and second members and a receiver disposed on the other of the opposing first and second members, and at least a portion of the web of stretch film extends through the gap between the opposing first and second members to selectively block a transmission path between the transmitter and receiver of each of at least a subset of the plurality of ultrasonic sensors.

In addition, in some embodiments, the take up device further includes a collection roller configured to collect the stretch film unwrapped from the load into a roll of stretch film, and a tracking roller positioned intermediate the edge detection sensor and the collection roller and configured to position the web of stretch film proximate to the edge detection sensor during the relative rotation. Also, in some embodiments, the tracking roller is pivotably supported on a spring-biased arm and configured to engage the web of stretch film between the edge detection sensor and the collection roller.