Apparatus and method for dispensing cushioning wrap 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 generally relates to the field of packaging materials, and more particularly to packaging materials for packaging and cushioning articles.

Background Art

[0002] In the process of packaging an article in a packaging container for shipping or transporting the article from one location to another, protective packaging materials (dunnage products) are typically placed in the packaging container together with the article. Dunnage products are put in to fill voids or cushion the article during shipping or transportation. Paper-based packaging materials are environmentally friendly packaging materials that are recyclable, biodegradable, and composed of renewable resources. Although it is also possible to use sheet-like paper as a protective packaging material, it is desirable to convert the sheet-like paper into a low-density dunnage product.

[0003] For example, expandable slit sheet packaging materials, also referred to as slit sheet materials, slit sheet stock materials, die-cut sheet stock materials, or slit materials, are useful as cushioning materials for packaging articles and as void-filling materials for packaging. The slit sheet stock material has a plurality of slits arranged in a plurality of generally parallel rows across the width dimension of the slit sheet stock material. When a stretching force is applied to this slit sheet material in the length direction or longitudinal direction, the slit sheet material expands in both length and thickness while the width decreases, the volume increases, and the density decreases to a similar extent. In this specification, the term "expansion" thus means three-dimensional expansion or volume expansion. Such slit sheet paper packaging materials and methods for manufacturing them are described in detail in U.S. Patent Nos. 5,667,871 and 5,688,578, the disclosures of which are hereby incorporated by reference in their entirety.

Summary of the Invention

[0004] The present disclosure describes a dunnage converting apparatus for supplying a cushioning packaging material from a roll of an expandable slit sheet material. The roll of the expandable slit sheet material includes the expandable slit sheet material in a non-expanded state. The expandable slit sheet material can be drawn out from the roll of the expandable slit sheet material and expanded into a pre-expanded state and an expanded state. In order to expand the expandable slit sheet material to form a cushioning packaging material, when the expandable slit sheet material is drawn out from the roll of the expandable slit sheet material, a stretching force is applied to the expandable slit sheet material in the stretching direction. This stretching force is applied by a user to the expandable slit sheet material in combination with a tension applying device of the dunnage converting apparatus.

[0005] An exemplary roll of the expandable slit sheet material includes the expandable slit sheet material in a non-expanded state. The expandable slit sheet material includes a plurality of rows of slits extending across the width of the expandable slit sheet material such that the slits open by a force applied across the direction of each slit.

[0006] An exemplary dunnage conversion device for supplying cushioning packaging material from a roll of expandable slit sheet material includes a frame. The frame has a supply section support for supporting a roll of expandable slit sheet material against rotation about a central axis as the expandable slit sheet material is drawn from the roll. The device also includes a tension applying device having a friction member that abuts the roll of expandable slit sheet material and at least one biasing spring fixed 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 a constant pressure on the roll as the expandable slit sheet material is drawn away from the roll and the diameter of the roll decreases. The force applied to the roll of expandable slit sheet material by the tension applying device constantly and automatically applies a rotational resistance to the roll as the roll decreases in diameter. The force pulling the expandable slit sheet material away from the roll cooperates with the rotational resistance to expand the expandable slit sheet material from a non-expanded state to an expanded state to form the cushioning packaging material.

[0007] The friction member may extend over 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 over the entire length or a length greater than the entire length 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 rotatably attached to the frame and a bar member attached to the friction member support, the bar member extending parallel to the roll of expandable slit sheet material and contacting the roll of expandable slit sheet material.

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

[0011] At least one biasing spring can be a constant load spring.

[0012] At least one biasing spring can be configured to bias a friction member against a roll of extensible slit sheet material such that the bar member constantly abuts against the roll of extensible slit sheet material when the diameter of the roll of extensible slit sheet material is decreasing.

[0013] The dunnage conversion device can further include a pair of powered gripping rollers configured to engage an extensible slit sheet material and draw the extensible slit sheet material out of a roll of extensible slit sheet material.

[0014] The pair of powered gripping rollers can be mounted downstream of the roll of extensible slit sheet material and the tension applying device.

[0015] The pair of powered gripping rollers can be biased towards each other and configured to receive an extensible slit sheet material therebetween.

[0016] The dunnage conversion device can further include a cutting device for cutting a cushioning packaging material after a desired length of the extensible slit sheet material has been drawn away from the roll of extensible slit sheet material and the cushioning packaging material of the desired length has been formed.

[0017] The cutting device can be mounted downstream of the roll of extensible slit sheet material, the tension applying device and the pair of powered rollers.

[0018] Another exemplary dunnage converting apparatus for supplying cushioning packaging material from a roll of expandable slit sheet material also includes a frame. The frame has a supply support portion for supporting a roll of expandable slit sheet material for rotation about a central axis when the expandable slit sheet material is drawn from the roll of expandable slit sheet material. The dunnage converting apparatus also includes a tensioning device including a plurality of pre-expansion rollers extending parallel to the central axis and spaced from the central axis. The plurality of pre-expansion rollers define a serpentine path through which the expandable slit sheet material passes when the expandable slit sheet material is drawn from the roll of expandable slit sheet material. The force for pulling the expandable slit sheet material from the roll cooperates with the plurality of pre-expansion rollers to expand the expandable slit sheet material from a non-expanded 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 packaging material.

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

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

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

[0022] The pair of powered gripping rollers may be biased toward each other and configured to receive the expandable slit sheet material therebetween.

[0023] The dunnage conversion device may further include a cutting device for cutting the cushioning packaging material after an extensible slit sheet material of a desired length is drawn out from a roll of the extensible slit sheet material and the cushioning packaging material of the desired length is formed.

[0024] The cutting device may be attached downstream of a roll of the extensible slit sheet material, a plurality of preliminary expansion rollers, and a pair of powered rollers.

[0025] A method of supplying the cushioning packaging material from the dunnage conversion device includes the following steps. (a) A step of pulling out an extensible slit sheet material from a roll of the extensible slit sheet material, whereby the roll of the extensible slit sheet material rotates around a central axis and the diameter decreases. (b) A step of applying rotational resistance to the roll of the extensible slit sheet material by a tension applying device so that the length and thickness of the extensible slit sheet material expand during the pulling out step. The tension applying device includes a friction member that contacts the roll of the extensible slit sheet material and at least one biasing spring fixed to the frame and the friction member. The step of applying rotational resistance to the roll of the extensible slit sheet material includes biasing the friction member of the tension applying device toward the roll of the extensible slit sheet material in a direction perpendicular to the central axis by the biasing spring during the pulling out step.

[0026] Another method of supplying the cushioning packaging material from the dunnage conversion device includes the following steps. (a) A step of pulling out the extensible slit sheet material between a plurality of preliminary expansion rollers that extend parallel to the central axis and are arranged spaced apart from the central axis, which define a meandering path through which the extensible slit sheet material is pulled out from the roll of the extensible slit sheet material, and (b) a step of expanding the extensible slit sheet material from a non-expanded state to a preliminary-expanded state when the extensible slit sheet material is pulled out through the meandering path formed by the plurality of preliminary expansion rollers.

[0027] Another exemplary dunnage conversion device for supplying cushioning packaging material from a supply section of an expandable slit sheet material includes a supply section support for the supply section of the expandable slit sheet material. The expandable slit sheet material on the supply section is in a non-expanded state. The dunnage conversion device also includes a tension applying device that facilitates applying a constant tension to the expandable slit sheet material when the expandable slit sheet material is drawn out from the supply section. Due to this constant tension, the expandable slit sheet material expands from the non-expanded state to the expanded state to form the cushioning packaging material.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10A

Figure 10B

Figure 11

DETAILED DESCRIPTION OF THE INVENTION

[0029] Next, referring to the drawings, first referring to FIG. 1, FIG. 1 shows a schematic dunnage conversion device 10 for supplying a cushioning packaging material from a supply section of an extensible slit sheet material, such as roll 12. The roll 12 of the extensible slit sheet material contains the extensible slit sheet material 14 in a non-expanded state. The dunnage conversion device 10 includes a frame 16 having at least one supply section support 18 or a pair of laterally spaced supply section supports 18 for supporting the supply section of the extensible slit sheet material or the roll 12 for rotation about the central axis 20. The frame 16 may be surrounded by a housing (not shown) that surrounds a portion of the device 10 or may be defined by the housing and may surround the roll 12. The extensible slit sheet material 14 is drawn from the roll 12 of the extensible slit sheet material in the direction of arrow 22 in FIG. 1, and the roll 12 rotates in the direction of arrow 24 about the central axis 20. When the extensible slit sheet material 14 is drawn from the roll 12 and the roll 12 of the extensible slit sheet material rotates about the central axis 20, the diameter of the roll 12 decreases.

[0030] To form the buffer packaging material, due to the tension or stretching force applied in the longitudinal or stretching direction 26 that intersects the central axis 20 on the expandable slit sheet material 14, as the expandable slit sheet material 14 is pulled from the roll 12, it expands. Therefore, the dunnage conversion device 10 includes a tension applying device 32 (schematically shown in FIG. 1) to assist in applying a stretching force to the expandable slit sheet material 14 when the expandable slit sheet material 14 is pulled from the roll 12. Specifically, the tension applying device 32 can facilitate applying a constant tension to the expandable slit sheet material when the expandable slit sheet material is drawn out from the supply part or the roll 12. Therefore, due to the constant tension, the expandable slit sheet material expands from the non-expanded state to the expanded state to form the buffer packaging material.

[0031] Referring to FIGS. 2 to 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 the non-expanded state when provided on the roll 12 of the expandable slit sheet material. The expandable slit sheet material 14 is spaced apart in the longitudinal direction (i.e., along the length L of the expandable slit sheet material 14) and extends in the transverse direction (i.e., along the width W of the expandable slit sheet material 14), and has a plurality of slits 28 arranged in a plurality of rows 30 of slits 28. Different arrangements of the slits 28 can include any one or two or more of the slit positions such as different arrangements of the rows 30 relative to each other, different sizes of the slits 28, different intervals between the slits 28, different slit shapes, or angular positions with respect to adjacent slits 28. The slits 28 can be formed by perforating, such as by cutting, or by intermittently weakening the expandable slit sheet material 14 across the width W of the expandable slit sheet material 14. m along), and extends in the transverse direction (i.e., along the width W of the expandable slit sheet material 14), and has a plurality of slits 28 arranged in a plurality of rows 30 of slits 28. Different arrangements of the slits 28 can include any one or two or more of the slit positions such as different arrangements of the rows 30 relative to each other, different sizes of the slits 28, different intervals between the slits 28, different slit shapes, or angular positions with respect to adjacent slits 28. The slits 28 can be formed by perforating, such as by cutting, or by intermittently weakening the expandable slit sheet material 14 across the width W of the expandable slit sheet material 14. m along), and extends in the transverse direction (i.e., along the width W of the expandable slit sheet material 14), and has a plurality of slits 28 arranged in a plurality of rows 30 of slits 28. Different arrangements of the slits 28 can include any one or two or more of the slit positions such as different arrangements of the rows 30 relative to each other, different sizes of the slits 28, different intervals between the slits 28, different slit shapes, or angular positions with respect to adjacent slits 28. The slits 28 can be formed by perforating, such as by cutting, or by intermittently weakening the expandable slit sheet material 14 across the width W of the expandable slit sheet material 14. m across), the expandable slit sheet material 14 can be formed by weakening.

[0032] The rows 30 of the slits 28 are typically parallel to each other and are typically periodically and typically equally spaced longitudinally from each other. The slits 28 are intermittent but periodically distributed across the rows 30, and the plurality of slits 28 in each row 30 are typically arranged in a zigzag pattern (i.e., offset laterally) with respect to the slits 28 in adjacent rows 30. Across each row 30 of the slits 28, the total length of the slit regions may be longer than the total length of the non-slit regions disposed between each slit 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, when a stretching force is applied to the expandable slit sheet material 14 in a stretching direction across the slits 28 extending in the width direction (i.e., along the length L m of the expandable slit sheet material 14), volumetric expansion of the expandable slit sheet material 14 occurs.

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

[0034] When a stretching force is applied, the expandable slit sheet material 14 expands from a non-expanded state to an expanded state, forming a cushioning packaging material. FIG. 3A shows the expandable slit sheet material 14 in an expanded state when such a stretching force is applied in the stretching direction (i.e., along the length L m of the expandable slit sheet material 14). When a stretching force is applied, the length L m of the expandable slit sheet material 14 becomes longer compared to the expandable slit sheet material 14 in the non-expanded state, while the width W mbecomes shorter (FIG. 2). Specifically, when a stretching force is applied in the stretching direction to the extensible slit sheet material 14, the regions on both sides of the slit 28 of the extensible slit sheet material 14 in the stretching direction are pulled away from each other, and the slit 28 opens into a shape having an extended length L se and an extended width W se .

[0035] When a stretching force is applied in the stretching direction to the extensible slit sheet material 14, the portion of the extensible slit sheet material 14 between the slits 28 also rotates with respect to the previous straight plane of the extensible slit sheet material 14 in the non-extended state (FIG. 2). As a result, the rotated region of the extensible slit sheet material 14 extends or protrudes beyond the plane of the extensible slit sheet material in the non-extended state, so that the thickness of the extensible slit sheet material 14 also increases. Therefore, the thickness of the extensible slit sheet material 14 in the extended state (FIG. 3A) is significantly or even more greater than the thickness of the extensible slit sheet material 14 in the non-extended state (FIG. 2) when stretched in this way.

[0036] Furthermore, when a stretching force is applied in the stretching direction to the extensible slit sheet material 14 and the extensible slit sheet material 14 is extended to the extended state (FIG. 3A), the extensible slit sheet material 14 deforms inelastically. Due to this inelastic deformation, the extensible slit sheet material 14 remains in the extended state, and the tendency for the extensible slit sheet material 14 to return to its previous non-extended state (FIG. 2) is reduced. In other words, the applied stretching force is sufficient to expand the extensible slit sheet material 14 beyond its elastic limit.

[0037] In one exemplary embodiment of the tension applying device 32 of the dunnage converting device 10, which will be described in more detail below, the tension applying device 32 is configured to assist in applying a stretching 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 the pre-expanded state. In the pre-expanded state, the regions of the expandable slit sheet material 14 on both sides of the slit 28 in the stretching direction are pulled apart from each other such that, although less than in the expanded state 28 (FIG. 3A), the slit 28 opens slightly (i.e., less than the opening of the slit 28 in the expanded state depicted in FIG. 3A). In other words, the slit 28 in the pre-expanded state (FIG. 4A) has a length L in a partially expanded state that is smaller than the length L in the expanded state of the slit 28 in the expanded state se and a width W in a partially expanded state that is larger than the width W in the expanded state of the slit 28 in the expanded state sp and is partially opened into a shape having the same. se and is partially opened into a shape having a width W in a partially expanded state that is larger than the width W in the expanded state of the slit 28 in the expanded state sp and is partially opened into a shape having the same.

[0038] Next, turning to FIGS. 5-6B, a first exemplary embodiment of the tension applying device 32 in the dunnage converting device 10 will be described. The first exemplary embodiment of the tension applying device 32 creates a resistance to the rotation of the roll 12 of the expandable slit sheet material when the expandable slit sheet material 14 is drawn therefrom and when the roll 12 of the expandable slit sheet material rotates about the central axis 20. The first exemplary embodiment of the tension applying device 32 includes a friction member 34 that abuts the roll 12 of the expandable slit sheet material and at least one biasing spring 36 fixed between the frame 16 and the friction member 34. The biasing spring 36 may be a constant load spring that applies a constant biasing force to the roll 12 over the entire movement range of the friction member 34. The biasing spring 36 is configured to bias the friction member 34 in a direction perpendicular to the central axis 20 with respect to the roll 12 when the expandable slit sheet material 14 is drawn out so as to leave the roll 12.

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

[0040] As shown in FIG. 5, two friction member supports 38 are attached at respective locations at the ends of the roll 12 of the expandable slit sheet material or beyond the ends of the roll 12, and the bar member 40 extends therebetween in its entirety. Thus, as shown, the bar member 40 is configured to abut against 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 such that the bar member 40 extends parallel to the roll 12 and contacts the roll 12 of the expandable slit sheet material along only a portion of the length of the roll 12. In another alternative, a single friction member support 38 may be attached to the frame 16 at respective locations at the ends of the roll 12 of the expandable slit sheet material or beyond the ends of the roll 12 or at positions between the respective ends of the roll 12. The single friction member support 38 may be attached to the frame 16 at its first end and attached to the bar member 40 at its second end.

[0041] The biasing spring 36 is fixed to the frame 16 at its first end and fixed to at least one friction member 34 at its second end. 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 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 load spring. Thus, as shown in FIGS. 6A and 6B, when the expandable slit sheet material 14 is pulled from the roll 12 and the roll 12 rotates around the central axis 20 and its diameter decreases, the biasing spring 36 biases the friction member 34, specifically the bar member 40, against the roll 12 of the expandable slit sheet material with a constant force. Therefore, the first exemplary embodiment of the tension applying device 32 is configured to constantly and automatically apply rotational resistance to the roll 12 when the roll 12 decreases in diameter.

[0042] The biasing spring 36 can apply a constant force in the range of 30 N to 40 N, such as 35 N, to the roll 12. Combined with the friction coefficient between the bar member 40 and the roll 12 (based on their respective roughnesses), the rotational resistance to the roll 12 generated by the force applied by the biasing spring 36 determines the force required to pull the expandable slit sheet material 14 from the roll 12. Generally, the combination of the friction coefficient between the bar member 40 and the roll 12 and the rotational resistance of the roll 12 is sufficient to expand the expandable slit sheet material 14 from the non-expanded state (FIG. 2) to the expanded state (FIG. 3A) when the expandable slit sheet material 14 is pulled from the roll 12 and expands to form the cushioning packaging material.

[0043] A method of supplying cushioning packaging material from a dunnage conversion device described herein having a first exemplary tensioning device includes pulling an extensible slit sheet material away from a roll of extensible slit sheet material. Pulling the extensible slit sheet material away from the roll of extensible slit sheet material rotates the roll of extensible slit sheet material about a central axis and decreases the diameter. The method further includes applying a rotational resistance to the rotation of the roll of extensible slit sheet material by a tensioning device as the diameter of the roll of extensible slit sheet material decreases such that the length and thickness of the extensible slit sheet material expand during the pulling step. Various exemplary tensioning devices are described herein, and an exemplary tensioning device includes a friction member that abuts the roll of extensible slit sheet material and at least one biasing spring fixed to the frame and the friction member, and can apply a force constantly and automatically without a starting operation by a user. Thus, applying a rotational resistance to the rotation of the roll of extensible slit sheet material includes biasing the friction member of the tensioning device toward the roll of extensible slit sheet material in a direction perpendicular to the central axis by the biasing spring during the step of pulling the extensible slit sheet material and while the roll of extensible slit sheet material decreases in diameter.

[0044] Referring to FIGS. 7A-9, a second exemplary embodiment of the tension applying device 32 is shown. The tension applying device 32 of the second exemplary embodiment includes a plurality of pre-extension rollers 42 for causing resistance to the expandable slit sheet material 14 when the expandable slit sheet material 14 is pulled out from the roll 12 of the expandable slit sheet material. Each of the plurality of pre-extension rollers 42 extends parallel to the central axis 20 and the roll 12 of the expandable slit sheet material and is disposed spaced apart from the central axis 20 and the roll 12 of the expandable slit sheet material. The plurality of pre-extension rollers 42 are attached downstream of the roll 12 (in the direction in which the expandable slit sheet material 14 is pulled out). As shown in FIG. 7B, the plurality of pre-extension rollers 42 define a meandering path through which the expandable slit sheet material 14 passes when the expandable slit sheet material 14 is pulled out from the roll 12. In the illustrated embodiment, three pre-extension rollers 42 form the meandering path, but two pre-extension rollers 42, or three or more pre-extension rollers 42, may be configured to form the meandering path as well. The plurality of pre-extension rollers 42 expand the expandable slit sheet material 14 from the non-expanded state (FIG. 2) to the pre-expanded state (FIG. 4A), and then to the fully expanded state (FIG. 3A) when the expandable slit sheet material 14 is pulled from the roll 12 and passes through the meandering path.

[0045] Specifically, referring to FIG. 8, when the expandable slit sheet material 14 moves along the meandering path formed by the plurality of pre-extension rollers 42, the expandable slit sheet material 14 is bent, and the width W of the expandable slit sheet material 14 m on each of the plurality of pre-extension rollers 42 along the width W of the expandable slit sheet material 14 mIt is partially folded around each of a plurality of preliminary expansion rollers 42 along. Each of the plurality of preliminary expansion rollers 42 has a small diameter with respect to the interval between the rows of slits, and its tight radius defines a sharp bending portion where the expandable slit sheet material 14 moves around each of the preliminary expansion rollers 42. When the expandable slit sheet material 14 bends or is folded on each of the plurality of preliminary expansion rollers 42, as described above with reference to FIGS. 4A and 4B, the regions of the expandable slit sheet material 14 on both sides of the slit 28 in the stretching direction are pulled apart from each other, and the slit 28 is gradually pulled open. That is, the bending of the expandable slit sheet material 14 on each of the plurality of preliminary expansion rollers 42 initially slightly opens the slit 28 and is sufficient to expand the expandable slit sheet material 14 to a preliminary expansion state, but is insufficient to open the slit 28 beyond the elastic state. However, as the expandable slit sheet material 14 continues to move through the meandering path, when passing through the meandering path, the force applied to the slit 28 continues to expand the slit sheet material 14 beyond the elastic state to the expansion state.

[0046] Referring to FIG. 9, for example, the plurality of preliminary expansion rollers 42 may include three preliminary expansion rollers 42a to 42c. The first preliminary expansion roller 42a applies a relatively small amount of constant friction to the expandable slit sheet material 14 passing therethrough. Due to this relatively small amount of constant friction, the expandable slit sheet material 14 passes closely through the second preliminary expansion roller 42b when continuing along the meandering path. Accordingly, the second preliminary expansion roller 42b slightly opens the slit 28 of the expandable slit sheet material 14 when the expandable slit sheet material 14 is closely bent over and around the second preliminary expansion roller 42b. The second preliminary expansion roller 42b is freely rotatable and may have a relatively small radius as described above. The third preliminary expansion roller 42b applies an even smaller amount of constant friction to the slightly opened expandable slit sheet material 14 passing thereover to further open the slit 28. The tension applying device 32 may further include a guide roller 41 disposed upstream of the first preliminary expansion roller 42a for guiding the expandable slit sheet material 14 from the roll so as to approach the first preliminary expansion roller 42 at a constant angle even if the diameter of the roll 12 of the expandable slit sheet material decreases.

[0047] A method of supplying a cushioning packaging material from the dunnage conversion device described herein having a second exemplary tension applying device includes pulling out an expandable slit sheet material between a plurality of preliminary expansion rollers extending parallel to the central axis and spaced apart from the central axis so as to be away from the roll of the expandable slit sheet material. The plurality of preliminary expansion rollers define a meandering path through which the expandable slit sheet material is pulled out. The method further includes expanding the expandable slit sheet material from a non-expanded state to a preliminary-expanded state when the expandable slit sheet material is pulled out through the meandering path formed by the plurality of preliminary expansion rollers.

[0048] By expanding the expandable slit sheet material 14 to a pre-expanded state (FIG. 4A) by a plurality of pre-expansion rollers 42, the amount of subsequent stretching force required to expand the expandable slit sheet material 14 to an expanded state (FIG. 3A) to form a cushioning packaging material is reduced. FIGS. 10A - B illustrate this reduction in force. Specifically, FIG. 10A shows a line graph representing the amount of stretching force required to expand the expandable slit sheet material 14 from an unexpanded state (FIG. 2) to an expanded state (FIG. 3A) when performed without a plurality of pre-expansion rollers 42. The first region 48 on the line graph represents the range of stretching force required to expand the expandable slit sheet material 14 from an unexpanded state (FIG. 2) to an expanded state (FIG. 3A) without causing a tear in the expandable slit sheet material 14.

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

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

[0051] Next, turning to FIG. 11, further features of the dunnage conversion device 10 are described. For example, in any of the exemplary embodiments, the dunnage conversion device 10 may further include at least a pair of powered gripping rollers 44 configured to engage an expandable slit sheet material 14 and draw the expandable slit sheet material 14 from a roll 12 of the expandable slit sheet material. Specifically, the pair of powered gripping rollers may be attached to the dunnage conversion device 10 and configured to receive the expandable slit sheet material 14 therebetween. The pair of powered gripping rollers 44 may be biased against each other to provide a constant and uniform grip force across the lateral width W m of the expandable slit sheet material 14 passing therebetween. The pair of powered gripping rollers 44 are configured to rotate about an axis of rotation parallel to the central axis 20 so as to grip the expandable slit sheet material 14 and pull the expandable slit sheet material 14 away from the roll 12 of the expandable slit sheet material. The pair of powered gripping rollers 44 are attached downstream (in the direction in which the expandable slit sheet material 14 is drawn) of the roll 12 of the expandable slit sheet material and the tensioning device 32 of any of the exemplary embodiments. Accordingly, the pair of powered gripping rollers 44 are configured to apply a stretching force to the expandable slit sheet material 14 and expand the expandable slit sheet material from a non-expanded state (the first example above) or a pre-expanded state (the second example above) to an expanded state.

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

[0053] A pair of powered gripping rollers 44 may be driven by a motor 45. The speed of the pair of powered gripping rollers 44 may be set by an appropriate configuration 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 start and stop of the pair of powered gripping rollers so as to manufacture a buffer packaging material of a controlled length. The control device may also be configured to control the cutting device 46. Specifically, in any of the exemplary embodiments, the dunnage conversion device 10 further includes a cutting device 46 for cutting the buffer packaging material after an extensible slit sheet material 14 of a desired length is pulled out from a roll 12 of the extensible slit sheet material, extended, and a buffer packaging material of the desired length is formed. The cutting device 46 is attached to the dunnage conversion device on the downstream side (the direction in which the extensible slit sheet material 14 is pulled out) of the pair of powered rollers.

[0054] In summary, the present disclosure describes a dunnage conversion device 10 for supplying a buffer packaging material from a roll 12 of an extensible slit sheet material. The roll 12 of the extensible slit sheet material includes an extensible slit sheet material 14 in a non-extended state. The extensible slit sheet material 14 is pulled out from the roll 12 of the extensible slit sheet material and extended to an extended state. When pulling out the extensible slit sheet material 14 from the roll 12 to expand the extensible slit sheet material 14 to form a buffer packaging material, a stretching force is applied to the extensible slit sheet material 14 in the stretching direction. Accordingly, the dunnage conversion device 10 includes a tension applying device 32 for assisting in applying such a stretching force.

[0055] The invention defined in the following claims is shown and described with respect to a particular embodiment, but reading and understanding this specification and the accompanying drawings will result in equivalent changes and modifications by those skilled in the art. In particular, with respect to the various functions performed by the various integers (components, assemblies, devices, components, etc.) described above, the terms used to describe such integers (including references to "means") are, unless otherwise indicated, not necessarily structurally equivalent to the disclosed structure that performs the function in the exemplary embodiments of the invention illustrated herein, but are intended to correspond to any integer that performs the specified function of the described integer (i.e., is functionally equivalent). Additionally, although a particular feature of the invention may have been described above with respect to only one of several exemplary embodiments, such a feature may be combined with one or more other features of one or more other embodiments as may be desired and advantageous for any given or particular application.

Claims

1. 1. A dunnage conversion machine for dispensing cushioning wrapping material from a roll of expandable slit sheet material having an expandable slit sheet material in an unexpanded state, the machine comprising: a frame having a feed 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 the expandable slit sheet material is unwound from the roll of expandable slit sheet material; Equipped with 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 travels through the serpentine path, thereby reducing the amount of stretching force required to expand the expandable slit sheet material to the expanded state to form the cushioning wrap. Dunnage conversion device.

2. The dunnage conversion device of claim 1 , wherein the plurality of pre-expanded rollers includes three pre-expanded rollers that form the serpentine path.

3. 2. The dunnage conversion apparatus of claim 1, 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.

4. The dunnage conversion apparatus of claim 3 , 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.

5. The dunnage conversion apparatus of claim 3 , wherein the pair of powered gripping rollers are configured to be biased toward one another to receive the expandable slit sheet material between the pair of powered gripping rollers.

6. 2. The dunnage conversion apparatus 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 a desired length of the cushioning wrap material.

7. 7. The dunnage conversion apparatus of claim 6, 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.

8. 1. A method of dispensing cushioning wrapping material from a dunnage conversion machine having a roll of expandable slit sheet material rotatably supported by a frame of the dunnage conversion machine for rotation about a central axis, the roll of expandable slit sheet material including expandable slit sheet material in an unexpanded state, the method comprising: 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, the plurality of pre-expansion rollers defining a serpentine path along which the expandable slit sheet material is drawn; 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 defined by the plurality of pre-expanding rollers. A method comprising:

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