Apparatus and method for providing cushioning packaging material

Abstract

To provide a dunnage conversion apparatus for dispensing a cushioning wrap material from a roll of expandable slit sheet material.SOLUTION: A roll of expandable slit sheet material includes an expandable slit sheet material in an unexpanded state. The expandable slit sheet material is pulled from the roll of expandable slit sheet material and expanded to a pre-expanded state and an expanded state. To expand the expandable slit sheet material and form the cushioning wrap material, a stretching force is applied to the expandable slit sheet material in a stretching direction as the expandable slit sheet material is pulled from the roll of expandable slit sheet material. Accordingly, the dunnage conversion apparatus includes a tensioning device for assisting in the application of such stretching force.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to the field of packaging materials, and more particularly to packaging materials for wrapping and cushioning items. [Background technology]

[0002] During the process of packaging items into a packaging container for shipping or transporting the items from one location to another, protective packaging material (dunnage product) is typically placed inside the packaging container along with the items. The dunnage product is placed to fill voids or cushion the items during the shipping or transport process. Paper packaging material is an environmentally friendly packaging material that is recyclable, biodegradable, and composed of renewable resources. While it is possible to use sheet paper as a protective packaging material, it is desirable to convert sheet paper into a low-density dunnage product.

[0003] For example, expandable slit sheet packaging materials, also known as slit sheet materials, slit sheet stock materials, die-cut sheet stock materials, or slit materials, are useful as cushioning materials for packaging items and as void-filling materials for packaging. Slit sheet stock materials have a plurality of slits arranged in generally parallel rows across the width dimension of the slit sheet stock material. When a longitudinal or longitudinal stretching force is applied to the slit sheet material, the slit sheet material expands in both length and thickness, while decreasing in width, increasing in volume, and decreasing in density to a comparable extent. Thus, the term "expanded" as used herein refers to three-dimensional expansion or volume expansion. Such slit sheet paper packaging materials and methods for their manufacture are described in detail in U.S. Pat. Nos. 5,667,871 and 5,688,578, the disclosures of which are incorporated herein by reference in their entireties. Summary of the Invention

[0004] The present disclosure describes a dunnage conversion apparatus for dispensing a cushioning wrap from a roll of expandable slit sheet material. The roll of expandable slit sheet material includes expandable slit sheet material in an unexpanded state. The expandable slit sheet material can be drawn from the roll of expandable slit sheet material and expanded to a pre-expanded state and an expanded state. To expand the expandable slit sheet material to form the cushioning wrap, an extensional force is applied to the expandable slit sheet material in a stretching direction as the expandable slit sheet material is drawn from the roll of expandable slit sheet material. The extensional force is applied to the expandable slit sheet material by a user in combination with a tensioning device of the dunnage conversion apparatus.

[0005] An exemplary roll of expandable slit sheet material includes an expandable slit sheet material in an unexpanded state, the expandable slit sheet material including a row of slits extending across the width of the expandable slit sheet material such that a force applied across the direction of each slit causes the slit to open.

[0006] An exemplary dunnage conversion apparatus for dispensing cushioning packaging material from a roll of expandable slit sheet material includes a frame. The frame has a dispensing section support for supporting the roll of expandable slit sheet material in rotation about a central axis as the expandable slit sheet material is unwound from the roll. The apparatus also includes a tensioning device having a friction member abutting the roll of expandable slit sheet material and at least one biasing spring secured to the frame and the friction member. The biasing spring is configured to bias the friction member toward the roll of expandable slit sheet material in a direction perpendicular to the central axis. The biasing spring and the friction member maintain constant pressure on the roll as the expandable slit sheet material is unwound from the roll, reducing its diameter. The force applied by the tensioning device to the roll of expandable slit sheet material constantly and automatically applies resistance to rotation to the roll as the roll reduces in diameter. The force pulling the expandable slit sheet material away from the roll, in combination with the resistance to rotation, expands the expandable slit sheet material from an unexpanded state to an expanded state to form the cushioning packaging material.

[0007] The friction member may extend across at least a portion of the length of the roll of expandable slit sheet material in a direction parallel to the central axis.

[0008] The friction member may extend the entire length or more of the roll of expandable slit sheet material in a direction parallel to the central axis.

[0009] The friction member may have a friction member support pivotally mounted to the frame and a bar member attached to the friction member support, the bar member extending parallel to and contacting the roll of expandable slit sheet material.

[0010] At least one biasing spring may be secured to the frame at a first end of the biasing spring and secured to the friction member at a second end of the biasing spring.

[0011] At least one biasing spring may be a constant force spring.

[0012] At least one biasing spring may be configured to bias the friction member against the roll of expandable slit sheet material such that the bar member constantly abuts the roll of expandable slit sheet material as the roll of expandable slit sheet material reduces in diameter.

[0013] The dunnage conversion device may further include a pair of powered gripping rollers configured to engage the expandable slit sheet material and pull the expandable slit sheet material from the roll of expandable slit sheet material.

[0014] A pair of powered gripping rollers may be mounted downstream of the roll of expandable slit sheet material and the tensioning device.

[0015] A pair of powered gripping rollers may be configured to be biased toward one another and to receive the expandable slit sheet material between the pair of powered gripping rollers.

[0016] The dunnage conversion apparatus may further include a cutting device for cutting the buffer wrap material after the desired length of expandable slit sheet material has been drawn away from the roll of expandable slit sheet material to form the desired length of buffer wrap material.

[0017] A cutting device may be mounted downstream of the roll of expandable slit sheet material, the tensioning device and the pair of powered rollers.

[0018] Another exemplary dunnage conversion apparatus for dispensing cushioning packaging material from a roll of expandable slit sheet material also includes a frame. The frame has a dispensing section support for supporting the roll of expandable slit sheet material for rotation about a central axis as the expandable slit sheet material is unwound from the roll. The dunnage conversion apparatus also includes a tensioning device extending parallel to and spaced apart from the central axis, the tensioning device including a plurality of pre-expansion rollers. The pre-expansion rollers define a serpentine path through which the expandable slit sheet material passes as it is unwound from the roll of expandable slit sheet material. The force of unwounding the expandable slit sheet material from the roll cooperates with the pre-expansion rollers to expand the expandable slit sheet material from an unexpanded state to a pre-expanded state as it passes through the serpentine path, thereby reducing the amount of stretching force required to expand the expandable slit sheet material to an expanded state to form the cushioning packaging material.

[0019] The plurality of pre-expansion rollers may include three pre-expansion rollers that form a serpentine path.

[0020] The dunnage conversion device may further include a pair of powered gripping rollers configured to engage the expandable slit sheet material and pull the expandable slit sheet material from the roll of expandable slit sheet material.

[0021] A pair of powered gripping rollers may be attached downstream of the roll of expandable slit sheet material and the plurality of pre-expansion rollers.

[0022] A pair of powered gripping rollers may be configured to be biased toward one another and to receive the expandable slit sheet material between the pair of powered gripping rollers.

[0023] The dunnage conversion apparatus may further include a cutting device for cutting the buffer wrap material after the desired length of expandable slit sheet material has been drawn away from the roll of expandable slit sheet material to form the desired length of buffer wrap material.

[0024] A cutting device may be mounted downstream of the roll of expandable slit sheet material, the plurality of pre-expansion rollers and the pair of powered rollers.

[0025] A method for dispensing cushioning packaging material from a dunnage conversion device includes the steps of: (a) unwinding expandable slit sheet material from a roll of expandable slit sheet material, whereby the roll of expandable slit sheet material rotates about a central axis and decreases in diameter; and (b) applying rotational resistance to the roll of expandable slit sheet material with a tensioning device such that the length and thickness of the expandable slit sheet material expands during the unwinding step. The tensioning device includes a friction member that contacts the roll of expandable slit sheet material and at least one biasing spring secured to the frame and the friction member. The step of applying rotational resistance to the roll of expandable slit sheet material includes biasing the friction member of the tensioning device toward the roll of expandable slit sheet material in a direction perpendicular to the central axis with the biasing spring during the unwinding step.

[0026] Another method of dispensing cushioning packaging material from a dunnage conversion device includes the steps of: (a) drawing the expandable slit sheet material from a roll of expandable slit sheet material between a plurality of pre-expansion rollers extending parallel to and spaced apart from a central axis, the pre-expansion rollers defining a serpentine path along which the expandable slit sheet material is drawn, and (b) expanding the expandable slit sheet material from an unexpanded state to a pre-expanded state as the expandable slit sheet material is drawn through the serpentine path defined by the plurality of pre-expansion rollers.

[0027] Another exemplary dunnage conversion apparatus for dispensing cushioning wrap from a supply of expandable slit sheet material includes a supply support for the supply of expandable slit sheet material. The expandable slit sheet material on the supply is in an unexpanded state. The dunnage conversion apparatus also includes a tensioning device that facilitates applying a constant tension to the expandable slit sheet material as it is drawn from the supply. The constant tension causes the expandable slit sheet material to expand from the unexpanded state to an expanded state to form the cushioning wrap. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic diagram of an exemplary dunnage conversion device having a tensioning device. [Figure 2] FIG. 1 is a perspective view of an expandable slit sheet material in an unexpanded state. [Figure 3A] FIG. 1 is a perspective view of an expandable slit sheet material in an expanded state. [Figure 3B] 1 is a schematic diagram of a slit in an expandable slit sheet material in an expanded state. [Figure 4A] FIG. 1 is a perspective view of an expandable slit sheet material in a pre-expanded state. [Figure 4B] FIG. 1 is a schematic diagram of a slit in an expandable slit sheet material in a pre-expanded state. [Figure 5] 1 is a perspective view of an exemplary dunnage conversion device having a first exemplary embodiment of a tensioning device for applying rotational resistance to a roll of expandable slit sheet material. FIG. [Figure 6A] FIG. 6 is a cross-sectional view of the exemplary dunnage conversion device of FIG. 5. [Figure 6B] FIG. 6 is a cross-sectional view of the exemplary dunnage conversion device of FIG. 5. [Figure 7A] FIG. 10 is a perspective view of an exemplary dunnage conversion device having a second exemplary embodiment of a tensioning device for applying resistance to expandable slit sheet material being drawn from a roll of expandable slit sheet material. [Figure 7B]FIG. 7B is an enlarged perspective view of a portion of the second exemplary embodiment of the tensioning device of FIG. 7A. [Figure 8] FIG. 7C is a perspective view of an expandable slit sheet material passing over one of a plurality of pre-expansion rollers of the second exemplary embodiment of the tensioning device of FIGS. 7A and 7B. [Figure 9] FIG. 7C is a side view of a plurality of pre-extension rollers of the second exemplary embodiment of the tensioning device of FIGS. 7A and 7B. [Figure 10A] FIG. 10 illustrates the stretching force required to expand an expandable slit sheet material from an unexpanded state to an expanded state. [Figure 10B] FIG. 10 illustrates the reduction in extensional force required to expand an expandable slit sheet material from a pre-expanded state to an expanded state. [Figure 11] FIG. 1 is a schematic diagram of another exemplary dunnage conversion device having a tensioning device. DETAILED DESCRIPTION OF THE INVENTION

[0029] Referring now to the drawings, and initially to FIG. 1, FIG. 1 illustrates a schematic dunnage conversion apparatus 10 for dispensing cushioning packaging material from a supply of expandable slit sheet material, such as, for example, a roll 12. The roll 12 of expandable slit sheet material includes expandable slit sheet material 14 in an unexpanded state. The dunnage conversion apparatus 10 includes a frame 16 having at least one supply support 18 or a pair of laterally spaced supply supports 18 for supporting the supply or roll 12 of expandable slit sheet material for rotation about a central axis 20. The frame 16 may be surrounded by or defined by a housing (not shown) that surrounds portions of the apparatus 10 and encloses the roll 12. The expandable slit sheet material 14 is drawn from the roll 12 of expandable slit sheet material in the direction of arrow 22 in FIG. 1 as the roll 12 rotates about the central axis 20 in the direction of arrow 24. As the expandable slit sheet material 14 is drawn from the roll 12 and the roll 12 of expandable slit sheet material rotates about the central axis 20, the roll 12 decreases in diameter.

[0030] To form the buffer wrap, a tensioning or stretching force is applied to the expandable slit sheet material 14 in a longitudinal or stretching direction 26 transverse to the central axis 20, causing the expandable slit sheet material 14 to expand as it is pulled from the roll 12. Accordingly, the dunnage conversion apparatus 10 includes a tensioning device 32 (shown schematically in FIG. 1 ) to assist in applying a stretching force to the expandable slit sheet material 14 as it is pulled from the roll 12. Specifically, the tensioning device 32 may facilitate applying a constant tension to the expandable slit sheet material as it is drawn from the supply or roll 12. Thus, the constant tension causes the expandable slit sheet material to expand from an unexpanded state to an expanded state to form the buffer wrap.

[0031] 2-4B, an exemplary expandable slit sheet material 14 is depicted in various expanded states. Specifically, FIG. 2 shows the expandable slit sheet material 14 in an unexpanded state as provided on a roll 12 of expandable slit sheet material. The expandable slit sheet material 14 has longitudinally spaced apart (i.e., length L of the expandable slit sheet material 14). m ), extending laterally (i.e., along the width W of the expandable slit sheet material 14 m , along the width W of the expandable slit sheet material 14. The different arrangements of the slits 28 may include any one or more of different arrangements of the rows 30 relative to each other, different sizes of slits 28, different spacing between slits 28, different slit shapes or slit positions, such as angular positions relative to adjacent slits 28. The slits 28 may be formed by perforating, such as by cutting, or by varying the width W of the expandable slit sheet material 14. m The expandable slits can be formed by weakening the sheet material 14 intermittently throughout the length of the sheet.

[0032] The rows 30 of slits 28 are generally parallel to one another and generally periodically, typically equally, spaced apart longitudinally from one another. The slits 28 are intermittently but periodically distributed across the rows 30, with the slits 28 in each row 30 generally being arranged in a zigzag pattern (i.e., laterally offset) relative to the slits 28 in adjacent rows 30. Throughout each row 30 of slits 28, the total length of the slit regions may be longer than the total length of the non-slit regions disposed between the slits 28, thereby providing an optimal amount of expansion for the expandable slit sheet material 14. The expandable slit sheet material 14 is configured to expand in one or more dimensions. In other words, the expandable slit sheet material 14 may have a certain degree of expansion in the direction of extension across the width-extending slits 28 (i.e., the length L of the expandable slit sheet material 14). m When a stretching force is applied (along the axis of the sheet), a volumetric expansion of the expandable slit sheet material 14 occurs.

[0033] An exemplary expandable slit sheet material 14 includes paper such as kraft paper, typically a single-ply kraft paper. Suitable kraft paper may have various basis weights, such as 20 lb or 40 lb. The expandable slit sheet material 14 may have any of many alternative arrangements of the slits 28 or different sheet thicknesses (i.e., in the dimension perpendicular to the plane of the paper in the perspective shown in FIG. 2, typically measured by or related to basis weight).

[0034] When a stretching force is applied, the expandable slit sheet material 14 expands from an unexpanded state to an expanded state to form a cushioning envelope. FIG. 3A shows the effect of such stretching force in the direction of stretching (i.e., the length L of the expandable slit sheet material 14). m 1 shows the expandable slit sheet material 14 in an expanded state when a stretching force is applied (along the m While the length increases, the width W mSpecifically, when a stretching force is applied to the expandable slit sheet material 14 in the stretching direction, the regions on both sides of the slit 28 of the expandable slit sheet material 14 in the stretching direction are pulled apart from each other, and the slit 28 shortens in length L in the expanded state as shown in FIG. se and the expanded width W se The opening is in a shape having the following structure:

[0035] When an expansion force is applied to the expandable slit sheet material 14 in the expansion direction, the portions of the expandable slit sheet material 14 between the slits 28 also rotate relative to the previously linear plane of the expandable slit sheet material 14 in its unexpanded state (FIG. 2). This also increases the thickness of the expandable slit sheet material 14, as the rotated regions of the expandable slit sheet material 14 extend or protrude beyond the plane of the expandable slit sheet material in its unexpanded state. Thus, the thickness of the expandable slit sheet material 14 in its expanded state (FIG. 3A), when stretched in this manner, can be orders of magnitude or more greater than the thickness of the expandable slit sheet material 14 in its unexpanded state (FIG. 2).

[0036] Furthermore, when a stretching force is applied to the expandable slit sheet material 14 in the stretching direction, and the expandable slit sheet material 14 is expanded to the expanded state (FIG. 3A), the expandable slit sheet material 14 is inelastically deformed. This inelastic deformation allows the expandable slit sheet material 14 to remain in the expanded state and reduces the tendency of the expandable slit sheet material 14 to return to its previous unexpanded state (FIG. 2). In other words, the applied stretching force is sufficient to expand the expandable slit sheet material 14 beyond its elastic limit.

[0037] In one exemplary embodiment of the tensioning device 32 of the dunnage conversion apparatus 10, described in more detail below, the tensioning device 32 is configured to assist in the application of an extensional force such that the expandable slit sheet material 14 is first pre-expanded to a pre-expanded state before being expanded to an expanded state. FIG. 4A shows the expandable slit sheet material 14 in a pre-expanded state. In the pre-expanded state, the areas of the expandable slit sheet material 14 on either side of the direction of extension of the slit 28 are pulled apart from each other such that the slit 28 is slightly open (i.e., less than the opening of the slit 28 in the expanded state depicted in FIG. 3A), albeit less than in the expanded state 28 (FIG. 3A). In other words, the slit 28 in the pre-expanded state (FIG. 4A) has an expanded length L of the slit 28 in the expanded state. se Partially expanded length L sp and the expanded width W of the slit 28 in the expanded state. se Partially expanded width W is greater than sp The opening is partially opened to have a shape having the following characteristics:

[0038] 5-6B, a first exemplary embodiment of the tensioning device 32 in the dunnage conversion apparatus 10 will be described. The first exemplary embodiment of the tensioning device 32 provides resistance to rotation of the roll 12 of expandable slit sheet material as the expandable slit sheet material 14 is withdrawn therefrom and as the roll 12 of expandable slit sheet material rotates about the central axis 20. The first exemplary embodiment of the tensioning device 32 includes a friction member 34 that abuts the roll 12 of expandable slit sheet material and at least one biasing spring 36 secured between the frame 16 and the friction member 34. The biasing spring 36 may be a constant force spring that applies a constant biasing force to the roll 12 throughout the range of travel of the friction member 34. The biasing spring 36 is configured to bias the friction member 34 against the roll 12 in a direction perpendicular to the central axis 20 as the expandable slit sheet material 14 is withdrawn away from the roll 12.

[0039] The friction member 34 extends at least partially along the entire length of the roll 12 of expandable slit sheet material in a direction parallel to the central axis 20. For example, as shown in FIG. 5 , the friction member 34 extends along the entire length or more of the roll 12 of expandable slit sheet material in a direction parallel to the central axis 20, with the friction member 34 abutting the roll 12 along its entire length. The friction member 34 may include at least one friction member support 38 pivotally mounted to the frame 16 and a bar member 40 extending between or otherwise attached to the at least one friction member support 38. The friction member supports 38 may be pivotally mounted at their respective first ends to the frame 16 and attached at their respective second ends to the bar member 40.

[0040] As shown in FIG. 5 , two friction member supports 38 are attached at or beyond each end of the roll 12 of expandable slit sheet material, with a bar member 40 extending entirely between them. Thus, as shown, the bar member 40 is configured to abut the roll 12 along its entire length. Alternatively, the bar member 40 may be configured to extend only partially between the friction member supports 38. For example, the bar member 40 may be attached between the friction member supports 38 so that the bar member 40 extends parallel to the roll 12 and is configured to contact the roll 12 of expandable slit sheet material along only a portion of its length. In another alternative, a single friction member support 38 may be attached to the frame 16 at or beyond each end of the roll 12 of expandable slit sheet material, or at a location between the ends of the roll 12. The single friction member support 38 may be attached to the frame 16 at its first end and to the bar member 40 at its second end.

[0041] The biasing spring 36 is fixed at its first end to the frame 16 and at its second end to at least one friction member 34. For example, the second end of the biasing spring 36 can be fixed to the second end of at least one friction member support 38 or to the bar member 40. The biasing spring 36 may be manually adjustable to apply various biasing forces to the friction member 34. The biasing spring 36 may be a constant force spring. Thus, as shown in FIGS. 6A and 6B , the biasing spring 36 is configured to bias the friction member 34, specifically the bar member 40, with a constant force against the roll 12 of expandable slit sheet material as the expandable slit sheet material 14 is pulled from the roll 12 and the roll 12 rotates about the central axis 20 to reduce its diameter. Thus, the first exemplary embodiment of the tensioning device 32 is configured to constantly and automatically apply rotational resistance to the roll 12 as the roll 12 reduces its diameter.

[0042] The biasing spring 36 may apply a constant force, such as 35 Newtons, to the roll 12 in the range of 30 Newtons to 40 Newtons. The resistance to rotation of the roll 12 caused by the force applied by the biasing spring 36, combined with the coefficient of friction between the bar members 40 and the roll 12 (based on their respective roughnesses), determines the force required to pull the expandable slit sheet material 14 from the roll 12. Generally, the combination of the coefficient of friction between the bar members 40 and the roll 12 and the resistance to rotation of the roll 12 is sufficient to expand the expandable slit sheet material 14 from an unexpanded state (FIG. 2) to an expanded state (FIG. 3A) as the expandable slit sheet material 14 is pulled from the roll 12 and expands to form the cushioning packaging material.

[0043] A method of dispensing cushioning packaging material from a dunnage conversion apparatus described herein having a first exemplary tensioning device includes pulling the expandable slit sheet material away from the roll of expandable slit sheet material. Pulling the expandable slit sheet material away from the roll of expandable slit sheet material rotates the roll of expandable slit sheet material about a central axis, reducing its diameter. The method further includes applying rotational resistance to the rotation of the roll of expandable slit sheet material with the tensioning device as the diameter of the roll of expandable slit sheet material decreases, such that the length and thickness of the expandable slit sheet material expands during the pulling step. Various exemplary tensioning devices are described herein, including a friction member abutting the roll of expandable slit sheet material and at least one biasing spring secured to the frame and the friction member, and capable of applying force continuously and automatically without user-initiated action. Thus, the step of applying rotational resistance to the rotation of the roll of expandable slit sheet material includes biasing a friction member of a tensioning device by a biasing spring toward the roll of expandable slit sheet material in a direction perpendicular to the central axis during the step of drawing out the expandable slit sheet material and as the roll of expandable slit sheet material reduces in diameter.

[0044] 7A-9, a second exemplary embodiment of the tensioning device 32 is shown. The tensioning device 32 of the second exemplary embodiment includes a plurality of pre-expansion rollers 42 for creating resistance in the expandable slit sheet material 14 as it is unwound from the roll 12 of expandable slit sheet material. Each of the plurality of pre-expansion rollers 42 extends parallel to the central axis 20 and the roll 12 of expandable slit sheet material and is spaced apart from the central axis 20 and the roll 12 of expandable slit sheet material. The plurality of pre-expansion rollers 42 are mounted downstream of the roll 12 (in the direction in which the expandable slit sheet material 14 is unwound). As shown in FIG. 7B, the plurality of pre-expansion rollers 42 define a serpentine path through which the expandable slit sheet material 14 passes as it is unwound from the roll 12. In the illustrated embodiment, three pre-expansion rollers 42 form the serpentine path, although two pre-expansion rollers 42, or three or more pre-expansion rollers 42 may similarly be configured to form the serpentine path. The multiple pre-expansion rollers 42 expand the expandable slit sheet material 14 from an unexpanded state (FIG. 2) to a pre-expanded state (FIG. 4A) and then to a fully expanded state (FIG. 3A) as the expandable slit sheet material 14 is pulled from the roll 12 through the serpentine path.

[0045] Specifically, with reference to FIG. 8, as the expandable slit sheet material 14 travels through the serpentine path formed by the plurality of pre-expansion rollers 42, the expandable slit sheet material 14 is bent and expands to a width W of the expandable slit sheet material 14. m On each of the plurality of pre-expanding rollers 42 along the width W of the expandable slit sheet material 14 m4A and 4B, the expandable slit sheet material 14 is partially folded over each of the plurality of pre-expansion rollers 42. Each of the plurality of pre-expansion rollers 42 has a small diameter relative to the spacing between the rows of slits, and its tight radius defines a sharp bend around which the expandable slit sheet material 14 moves around each of the plurality of pre-expansion rollers 42. As the expandable slit sheet material 14 bends or folds over each of the plurality of pre-expansion rollers 42, the regions of the expandable slit sheet material 14 on either side of the slits 28 in the direction of stretch are pulled away from each other, gradually pulling the slits 28 open, as described above with reference to FIGS. 4A and 4B. That is, the bending of the expandable slit sheet material 14 over each of the plurality of pre-expansion rollers 42 is sufficient to initially open the slits 28 slightly and expand the expandable slit sheet material 14 to a pre-expanded state, but is insufficient to open the slits 28 beyond their elastic state. However, as the expandable slit sheet material 14 continues to move through and pass through the tortuous path, the forces on the slits 28 continue to cause the slit sheet material 14 to expand beyond the elastic state to the expanded state.

[0046] Referring to FIG. 9 , for example, the plurality of pre-expansion rollers 42 may include three pre-expansion rollers 42a-c. The first pre-expansion roller 42a provides a relatively small amount of consistent friction to the expandable slit sheet material 14 passing thereover. This relatively small amount of consistent friction causes the expandable slit sheet material 14 to closely pass the second pre-expansion roller 42b as it continues along its serpentine path. The second pre-expansion roller 42b thus slightly opens the slits 28 in the expandable slit sheet material 14 as the expandable slit sheet material 14 closely bends over and around the second pre-expansion roller 42b. The second pre-expansion roller 42b is free to rotate and may have a relatively tight radius, as described above. The third pre-expansion roller 42b provides an even smaller amount of consistent friction to the slightly opened expandable slit sheet material 14 passing thereover to further open the slits 28. The tensioning device 32 may further include a guide roller 41 positioned upstream of the first pre-expansion roller 42a for guiding the expandable slit sheet material 14 from the roll so that it approaches the first pre-expansion roller 42 at a constant angle even as the diameter of the roll 12 of expandable slit sheet material decreases.

[0047] A method of dispensing cushioning wrapping material from a dunnage conversion device having a second exemplary tensioning device described herein includes drawing the expandable slit sheet material away from a roll of expandable slit sheet material between a plurality of pre-expansion rollers extending parallel to and spaced apart from a central axis, the plurality of pre-expansion rollers defining a serpentine path along which the expandable slit sheet material is drawn. The method further includes expanding the expandable slit sheet material from an unexpanded state to a pre-expanded state as the expandable slit sheet material is drawn through the serpentine path defined by the plurality of pre-expansion rollers.

[0048] Expanding the expandable slit sheet material 14 to a pre-expanded state ( FIG. 4A ) with multiple pre-expansion rollers 42 reduces the amount of subsequent stretching force required to expand the expandable slit sheet material 14 to the expanded state ( FIG. 3A ) to form the cushioning wrap. FIGS. 10A-B graphically illustrate this force reduction. Specifically, FIG. 10A shows a line graph representing the amount of stretching force required to expand the expandable slit sheet material 14 from the unexpanded state ( FIG. 2 ) to the expanded state ( FIG. 3A ) when performed without multiple pre-expansion rollers 42. A first region 48 on the line graph represents the range of stretching force required to expand the expandable slit sheet material 14 from the unexpanded state ( FIG. 2 ) to the expanded state ( FIG. 3A ) without causing tearing of the expandable slit sheet material 14.

[0049] In comparison, Figure 10B shows a line graph representing the amount of stretching force required to expand the expandable slit sheet material 14 from the pre-expanded state (Figure 4A) to the expanded state (Figure 3A). The larger second region 52 on the line graph in Figure 10B represents the range of stretching force required to expand the expandable slit sheet material 14 from the pre-expanded state (Figure 4A) to the expanded state (Figure 3A) without causing tearing in the expandable slit sheet material 14. As shown, the stretching force required to expand the expandable slit sheet material 14 from the pre-expanded state to the expanded state (Figure 10B) is significantly reduced than the stretching force required to expand the expandable slit sheet material 14 from the unexpanded state to the expanded state (Figure 10A), having a significantly reduced minimum required stretching force (range 50).

[0050] Additionally, by combining the tensioning device 32 of the first embodiment with the tensioning device 32 of the second embodiment in the dunnage conversion device 10, the expansion of the expandable slit sheet material 14 into an expanded state can be further enhanced to form a cushioning packaging material.

[0051] 11 , further features of the dunnage conversion apparatus 10 are described. For example, in any exemplary embodiment, the dunnage conversion apparatus 10 may further include at least a pair of powered gripping rollers 44 configured to engage the expandable slit sheet material 14 and pull the expandable slit sheet material 14 from the roll 12 of expandable slit sheet material. Specifically, the pair of powered gripping rollers may be attached to the dunnage conversion apparatus 10 and configured to receive the expandable slit sheet material 14 therebetween. The pair of powered gripping rollers 44 may be configured to grip the expandable slit sheet material 14 in a lateral direction W of the expandable slit sheet material 14 passing therebetween. m The pair of powered gripping rollers 44 can be biased toward each other to provide a constant and even gripping force across the roll 12. The pair of powered gripping rollers 44 are configured to rotate about axes of rotation parallel to the central axis 20 to grip the expandable slit sheet material 14 and pull the expandable slit sheet material 14 away from the roll 12 of expandable slit sheet material. The pair of powered gripping rollers 44 are mounted downstream (in the direction that the expandable slit sheet material 14 is unwound) from the roll 12 of expandable slit sheet material and the tensioning device 32 of either exemplary embodiment. Thus, the pair of powered gripping rollers 44 are configured to apply a stretching force to the expandable slit sheet material 14, causing the expandable slit sheet material to expand from an unexpanded state (the first example described above) or a pre-expanded state (the second example described above) to an expanded state.

[0052] The pair of powered rollers 44 may be covered with or formed with a friction material or gripping means sufficient to grip the expandable slit sheet material 14 and pull the expandable slit sheet material 14 away from the roll 12 of expandable slit sheet material without the expandable slit sheet material 14 slipping therebetween.

[0053] The pair of powered gripping rollers 44 may be driven by a motor 45, and the speed of the pair of powered gripping rollers 44 may be set by a suitable arrangement of drive elements such as gears or chains, or the speed may be set electronically via a controller. The control device may also control the starting and stopping of the pair of powered gripping rollers to produce a controlled length of buffer wrap material. The control device may also be configured to control the cutting device 46. Specifically, in any exemplary embodiment, the dunnage conversion apparatus 10 may further include a cutting device 46 for cutting the desired length of expandable slit sheet material 14 after it has been drawn and expanded away from the roll 12 of expandable slit sheet material to form the desired length of buffer wrap material. The cutting device 46 is attached to the dunnage conversion apparatus downstream of the pair of powered rollers (in the direction in which the expandable slit sheet material 14 is drawn).

[0054] In summary, this disclosure describes a dunnage conversion apparatus 10 for dispensing a cushioning wrap from a roll 12 of expandable slit sheet material. The roll 12 of expandable slit sheet material includes an expandable slit sheet material 14 in an unexpanded state. The expandable slit sheet material 14 is drawn from the roll 12 of expandable slit sheet material and expanded to an expanded state. To expand the expandable slit sheet material 14 to form the cushioning wrap, an extensional force is applied to the expandable slit sheet material 14 in the direction of extension as the expandable slit sheet material 14 is drawn from the roll 12. Accordingly, the dunnage conversion apparatus 10 includes a tensioning device 32 to assist in the application of such extensional force.

[0055] While the invention defined in the following claims has been shown and described with respect to certain embodiments, equivalent alterations and modifications will occur to those skilled in the art upon reading and understanding this specification and the accompanying drawings. In particular, with respect to the various functions performed by the above-described entities (components, assemblies, devices, compositions of matter, etc.), the terms used to describe such entities (including references to "means") are intended, unless otherwise indicated, to correspond to any entity that performs the specified function of the described entity (i.e., is functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs that function in the exemplary embodiment of the invention illustrated herein. In addition, while a particular feature of the invention may be described above with respect to only one of several exemplary embodiments, such feature may be combined with one or more other features of other embodiments, as may be desired or advantageous for any given or particular application.

Claims

1. 1. A dunnage conversion apparatus for dispensing cushioning wrapping material from a roll of expandable slit sheet material having the expandable slit sheet material in an unexpanded state, the dunnage conversion apparatus comprising: a frame having a supply support for supporting a roll of expandable slit sheet material for rotation about a central axis as expandable slit sheet material is drawn from the roll of expandable slit sheet material; a plurality of pre-expansion rollers extending parallel to and spaced apart from the central axis, the plurality of pre-expansion rollers defining a serpentine path through which the expandable slit sheet material travels as it is unwound from the roll of expandable slit sheet material; Equipped with the plurality of pre-expansion rollers include a first pre-expansion roller disposed upstream, a second pre-expansion roller disposed downstream of the first pre-expansion roller and configured to be freely rotatable, and a third pre-expansion roller disposed downstream of the second pre-expansion roller, the third pre-expansion roller configured to provide a smaller amount of friction than the first pre-expansion roller; the dunnage conversion device further comprising a pair of powered gripping rollers configured to engage the expandable slit sheet material and pull the expandable slit sheet material from the roll of expandable slit sheet material; the plurality of pre-expansion rollers expand the expandable slit sheet material from the unexpanded state to a pre-expanded state as the expandable slit sheet material passes through the serpentine path, thereby reducing the amount of stretching force required to expand the expandable slit sheet material to an expanded state to form the cushioning wrap. Dunnage conversion device.

2. The dunnage conversion device of claim 1 , wherein the pair of powered gripping rollers are mounted downstream of the roll of expandable slit sheet material and the plurality of pre-expansion rollers.

3. 2. The dunnage conversion device of claim 1, wherein the pair of powered gripping rollers are configured to be biased toward each other to receive the expandable slit sheet material between the pair of powered gripping rollers.

4. 10. The dunnage conversion device of claim 1, further comprising a cutting device for cutting the cushioning wrap material after a desired length of the expandable slit sheet material has been drawn away from the roll of expandable slit sheet material to form the desired length of the cushioning wrap material.

5. 5. The dunnage conversion apparatus of claim 4, wherein the cutting device is mounted downstream of the roll of expandable slit sheet material, the plurality of pre-expansion rollers and a pair of powered gripping rollers.

6. 1. A method of dispensing cushioning wrapping material from a dunnage conversion apparatus having a roll of expandable slit sheet material rotatably supported by a frame of the dunnage conversion apparatus for rotation about a central axis, the roll of expandable slit sheet material comprising expandable slit sheet material in an unexpanded state, the dunnage conversion apparatus comprising: a frame having a supply support for supporting a roll of expandable slit sheet material for rotation about a central axis as expandable slit sheet material is drawn from the roll of expandable slit sheet material; a plurality of pre-expansion rollers extending parallel to and spaced apart from the central axis, the plurality of pre-expansion rollers defining a serpentine path through which the expandable slit sheet material travels as it is unwound from the roll of expandable slit sheet material; Equipped with the plurality of pre-expansion rollers include a first pre-expansion roller disposed upstream, a second pre-expansion roller disposed downstream of the first pre-expansion roller and configured to be freely rotatable, and a third pre-expansion roller disposed downstream of the second pre-expansion roller, the third pre-expansion roller configured to provide a smaller amount of friction than the first pre-expansion roller; the dunnage conversion device further comprising a pair of powered gripping rollers configured to engage the expandable slit sheet material and pull the expandable slit sheet material from the roll of expandable slit sheet material; The method comprises: drawing the expandable slit sheet material away from the roll of expandable slit sheet material between a plurality of pre-expansion rollers extending parallel to and spaced apart from the central axis; expanding the expandable slit sheet material from the unexpanded state to a pre-expanded state as the expandable slit sheet material is drawn through the serpentine path formed by the plurality of pre-expansion rollers; expanding the expandable slit sheet material from the pre-expanded state to an expanded state with the pair of powered gripping rollers; A method comprising:

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