Brake system for a dunnage conversion machine

Abstract

A brake assembly for a dunnage conversion machine (10), the brake assembly comprising a spindle (18) configured to accept a roll (14) of sheet material (12); a tension belt (40) having a tension and configured to engage the spindle (18) and impart a friction force on the spindle (18); a tensioner (42) configured to adjust tension in the tension belt (40), whereby increasing tension in the tension belt (40) increases the friction force imparted on the spindle (18); a controller (26) configured to control the tensioner (42); a sensor (50) configured to detect an amount of sheet material (12) remaining on the roll (14); wherein the sensor (50) detects an amount of sheet material (12) remaining on the roll (14) as the conversion machine draws sheet material (12) off of the roll (14) and signals the controller (26), wherein, in response to the signal, the controller (26) actuates the tensioner (42) to reduce the tension in the tension belt (40) to compensate for the amount of sheet material (12) drawn off of the roll (14).

Description

[0001] BRAKE SYSTEM FOR A DUNNAGE CONVERSION MACHINE

[0002] Field of the Invention

[0003] The present disclosure relates generally to the field of dunnage conversion systems, and more particularly to a braking system for a supply of sheet material for a dunnage conversion machine.

[0004] Background

[0005] In the process of packing an article in a packaging container to ship the article from one location to another, a protective packaging material (generally referred to as a dunnage product) is often placed in the packaging container with the article. The dunnage product is included to fill any voids or to cushion the article, and also may provide thermal insulation that helps to preserve the temperature in the container during the shipping process. Dunnage conversion machines, also referred to as converters, generally convert a sheet stock material into a relatively less dense dunnage product, to protect articles in a shipping container during shipment. Dunnage products also may provide insulation qualities that can assist in maintaining the temperature of products being shipped.

[0006] Many suitable dunnage products can be produced from a sheet stock material, such as paper or plastic. Paper packing material is an ecologically-friendly packing material that is recyclable, biodegradable, and composed of a renewable resource. While paper in sheet form could possibly be used as a protective packaging material, it may be preferable to convert the sheets of paper into a dunnage product having a lower density than the paper used to make the dunnage product.

[0007] The sheet stock material usually is supplied in the form of a roll or a fan-folded stack from which the sheet stock material is paid off or drawn off for conversion by the machine into the dunnage product. Rolls of sheet stock material typically have a hollow core around which the sheet stock material is wound and are supported on a spindle that allows the roll to rotate as the conversion machine draws the sheet stock material from the roll. Summary

[0008] The present disclosure describes a dunnage conversion machine, and more particularly a brake assembly for a supply of sheet material for a dunnage conversion machine. The brake assembly uses a tension belt on a spindle that is inserted into and coupled to a hollow core of the roll. Variable tension is applied to the belt to resist rotation of the roll and thereby maintain a constant tension on the sheet material being drawn from the roll, whereby the tension on the belt is decreased as sheet material is dispensed from the roll.

[0009] As the sheet material is drawn from the roll and converted into dunnage products, the diameter and mass of the roll decreases. As the mass of the roll decreases, the tension on the belt is reduced to reduce the friction force acting on the spindle that supports the roll of sheet material. Thus, the roll of sheet material will remain in constant tension. Maintaining constant tension is advantageous because dunnage conversion machines typically operate in a start-stop manner. In conventional designs, as the machine stops, the roll of sheet material can over-rotate or overrun due to the rotational inertia of the roll, causing a loose loop of sheet material to form between the roll and the conversion machine. This loose loop is then taken up by the machine when it restarts, with nearly zero tension in the sheet material until the slack of the loose loop is taken up fully. Then the tension in the sheet material spikes as the machine continues to draw sheet material from the roll, and has to overcome the inertia of the mass of the roll at rest before a steady-state level of tension is achieved. This low tension condition followed by the sudden high tension condition can lead to nonuniform properties in the resulting dunnage product. The sudden high-tension condition can cause the sheet material to tear or jam in the machine, leading to further stoppage of the machine and downtime, as well as wasted sheet material, as the tearing or jamming problems are corrected.

[0010] The present disclosure minimizes or prevents the overrun problem by automatically imparting a variable resistance force to rotation of the roll, thereby maintaining tension in the sheet material as it is drawn off the roll, slowing rotation and minimizing or eliminating overrun when the dunnage conversion machine stops. Providing more uniform tension in the sheet stock material as it is drawn from the roll also promotes a more uniform, higher quality dunnage product.

[0011] An exemplary brake assembly for a dunnage conversion machine includes a spindle affixed to a mounting surface of the dunnage conversion machine. This mounting surface can be a separate frame or support, part of the conversion machine, or a frame or support attached to the conversion machine.

[0012] An exemplary dunnage conversion machine for producing a dunnage pad from a sheet material provided on a roll may include one or more of the following features: a support for the roll of sheet material, a conversion assembly that converts the sheet material into a dunnage product, the conversion assembly including a pair of rotatable members that draw sheet material from the roll, and the support including a brake assembly.

[0013] The dunnage conversion machine may include a frame that defines the mounting surface.

[0014] The dunnage conversion machine may include a vertical configuration for the mounting surface.

[0015] An exemplary method for producing a dunnage pad from a sheet material includes one or more of the following steps, (i) providing a roll of sheet material having a hollow cylindrical core, (ii) supporting the roll of sheet material on an a spindle received in the core with an exemplary brake device attached to the spindle , (iii) advancing the sheet material from the roll in a downstream direction to a dunnage conversion machine, converting the sheet material into a dunnage product with a lower density than a density of the sheet material, (iv) stopping the advancing of the sheet material, and (v) slowing rotation of the roll of sheet material with friction resistance from the exemplary brake device.

[0016] Brief Description of the Drawings

[0017] FIG. 1 is a schematic illustration of a dunnage conversion system that employs a dunnage conversion machine to draw sheet stock material from a roll;

[0018] FIG. 2 is a side elevation view of an exemplary brake assembly for a conversion machine with a roll of sheet stock material; FIG. 3 is an alternate embodiment of an exemplary brake assembly for a conversion machine with a roll of sheet stock material;

[0019] FIG. 4 is a front view of the brake assembly of FIG. 2; and

[0020] FIG. 5 is a flow chart of an exemplary method of producing a dunnage product from a roll of sheet stock material.

[0021] Detailed Description

[0022] Dunnage conversion machines typically operate to produce dunnage products on demand, as needed, which typically results in frequent start-stop operation. A typical dunnage conversion system is schematically depicted in FIG 1. The system includes a dunnage conversion machine 10 that draws sheet stock material 12 from a feedstock, specifically a supply of sheet stock material (interchangeably referred to as sheet material or sheet stock or stock material) in roll form 14, whereby the sheet material 12 is converted into a dunnage material 16 (interchangeably referred to as a discrete dunnage product or simply dunnage) for use in packaging.

[0023] An exemplary supply of sheet stock includes a sheet material wound into a roll 14 and supported by a spindle 18 for rotation with the spindle. For dunnage conversion machines that draw a sheet stock material from a roll for conversion into a relatively lower-density dunnage product, every start requires the conversion machine to overcome the inertia of the stationary roll to draw the sheet material therefrom. And every stop allows the inertia of the roll to continue to rotate and create a loose segment of sheet material that is not drawn into the conversion machine. Restarting the conversion machine then causes the conversion machine to draw this loose segment into the conversion machine under minimal or no tension and then impart a sudden increase in tension on the stock material as the slack is taken up. This sudden increase in tension in the stock material is imparted to the stationary roll, as well as to the spindle that supports the roll for rotation.

[0024] A typical dunnage conversion machine includes a forming assembly 20 that shapes the sheet stock material and a feeding assembly 22 that draws the sheet material in an upstream-to-downstream direction from the supply and through the forming assembly. The upstream-to-downstream direction also can be referred to as a downstream direction, and an upstream direction is opposite the downstream direction. The conversion machine optionally may include a severing assembly 24 for severing discrete lengths of dunnage 16 at desired lengths as it is produced. The conversion machine 10 also can include a controller 26 with a microprocessor 28, a memory 30, and software that controls the conversion machine 10 and accessories, typically at least the feeding assembly 22 and the severing assembly 24, to produce the desired lengths of dunnage 16.

[0025] As mentioned above, the supply of sheet stock material 12 is provided in the form of a roll 14, and an exemplary sheet material is paper, such as kraft paper. The roll 14 of sheet material 12 may have a single ply, or multiple plies, and may be perforated at regular intervals to facilitate producing predetermined lengths of dunnage product without cutting the stock material or to provide an expandable sheet stock material 12. Rolls of sheet material are typically wound around a hollow core. The hollow core may be reusable after depletion of the stock material, or the core may be removed after winding to form a “coreless” roll of stock material. The core may include a stiff tubular structure, such as a cardboard, paperboard, or plastic tube. Alternatively, a coreless roll may have a hollow cylindrical volume at its center. Any of these types of rolls may be referred to as a “hollow core” roll of sheet material.

[0026] The roll 14 of sheet stock material 12 is mounted on a rotating spindle 18 that allows the roll 14 to rotate with the spindle 18 as the dunnage conversion machine 10 draws the sheet stock material 12 from the roll 14. The roll 14 of sheet stock material is mounted on the rotating spindle 18 via a friction connection that is sufficient to cause the roll 14 and spindle 18 to rotate as one. In other words, the friction connection is adequate to ensure that the roll 14 does not slip or slide with respect to the spindle 18 when starting or stopping, such that when the spindle 18 is slowed or stopped, the roll 14 will slow or stop simultaneously with the spindle 18. Likewise, when sheet material 12 is drawn off the roll 14, causing the roll 14 to rotate, the spindle 18 will rotate simultaneously with the roll 14.

[0027] Turning now to FIG. 2, a roll 14 of sheet material 12 is installed on a spindle 18. A belt 40 is attached to the spindle 18 by wrapping the belt over or around the spindle 18 and attaching the belt 40 to a tensioner 42. The tensioner 42 applies tension to the belt 40 to impart a friction force on the spindle 18, causing a moving spindle 18 to slow and resist rotation of the roll 14 and spindle 18, but still permit the spindle 18 and roll 14 to rotate. This friction force acts as a braking mechanism to slow the rotation of the hollow cylindrical core of the roll 14 and maintain tension of the sheet material 12 in the dunnage conversion machine 10 when the dunnage conversion machine 10 is stopped or turned off. The tensioner 42 is configured to provide variable tension, to increase or decrease tension as needed.

[0028] As shown in FIG. 3, the tensioner 42 can comprise a piston 44 and cylinder 46. The ends of the belt 40 are attached to the piston 44. The piston 44 retracts into the cylinder 46 to add tension to the belt 40 or extends out from the cylinder 46 to reduce tension to the belt 40, thus increasing or decreasing the friction force on the spindle 18, respectively. The piston 44 and cylinder 46 are preferably pneumatically operated, but can be operated by any method known in the art, including but not limited to hydraulic, electromechanical, electromagnetic, and the like.

[0029] A sensor 50 is disposed near the roll 14 and detects or measures the size (typically the diameter or radius) of the roll 14. (As used herein, the terms detect, measure, monitor, or sense can be used interchangeably). Alternatively, the sensor 50 may be coupled to a support structure for the roll 14 to measure the weight of the roll 14. As the roll 14 is depleted, the sensor 50 sends a signal to the controller 26. The controller 26 actuates or instructs the tensioner 42 to reduce the tension to compensate for the reduced mass as a result of the sheet material 12 being drawn off or increase the tension when a new roll 14 is detected in the supply. The sensor 50 can continuously monitor the roll 14 and send signals to the controller 26, and the controller 26 can constantly adjust the tension on the belt 40, providing continuously variable tension that decreases with the reduction in size or weight of the roll 14. In an exemplary embodiment, the controller 26 can actuate the piston 44 in the cylinder 46 by adjusting the pressure in the pneumatic line 48 attached to the cylinder 46 (See FIG. 3).

[0030] The sensor 50 is positioned relative to the roll 14 of sheet material to measure the amount of sheet material 12 remaining on the roll 14. In an exemplary embodiment, measuring the amount of sheet material 12 remaining on the roll 14 is accomplished by measuring the diameter of the roll 14. The sensor 50 can be positioned in any orientation and location that allows for an accurate measurement of the amount of sheet material 12 remaining on the roll 14. For example, the sensor 50 can be located to the side of the roll 14 (See FIGs. 2 and 4) or below (or above) the roll 14 (See FIG. 3). The sensor 50 measures 52 the amount of sheet material 12 remaining on the roll 14. The sensor 50 can measure the amount of sheet material 12 using any technique 52 or device known in the art, such for example, a laser, an infrared beam, a visible light beam, a camera, video image comparison, a probe / member in physical contact with the outer (topmost) surface of the roll, a weight scale, etc.

[0031] In an alternative exemplary embodiment, the sensor 50 monitors 52 the roll 14 and once the diameter of the roll 14 reaches a first threshold diameter, the controller 26 actuates the tensioner 42 to decrease the tension to a first preset (predetermined) reduced tension level. As the roll 14 is further depleted, and the diameter of the roll 14 reaches a second threshold diameter, the controller 26 actuates the tensioner 42 to decrease the tension to a second preset reduced tension level. This process can be repeated for an arbitrary number of threshold diameters and predetermined tension settings. In other words, it is possible to have n threshold levels and preset tension settings, where n is an integer greater than 0. Moreover, in an alternate exemplary embodiment, each threshold level can have its own sensor 50 to detect when the roll 14 has reached the threshold level. In other words, it is possible to have n sensors 50, n threshold levels, and n tension settings, where n>0.

[0032] In another exemplary embodiment, the system can have three tension settings (i.e. an embodiment where n = 3): standby tension, large roll tension, and small roll tension. In this embodiment, standby tension is the greatest amount of tension in the belt 40 and small roll tension is the least amount of tension in the belt 40 (i.e. standby tension > large roll tension > small roll tension). Initially, before the system has begun operation (i.e. the system is in standby mode, such as during replacement of a roll 14), the tensioner 42 holds the tension in the belt 40 in standby tension for the maximum amount of tension in the belt 40. Once a new (large or full) roll 14 has been installed, the system is started, and the controller 26 sends a signal to the tensioner 42 to reduce the belt tension to the large roll tension as the roll 14 begins to rotate. As the system operates and the roll 14 is depleted, the sensor 50 detects when the diameter of the roll 14 has reached a threshold diameter, at which point the controller 26 sends a signal to the tensioner 42 to reduce tension on the belt 40 to the small roll tension.

[0033] As the roll 14 is depleted, the diameter of the roll 14 decreases, which reduces the mass and the rotational inertia of the roll 14. As the rotational inertia of the roll 14 decreases, the amount of force required to slow the rotation of the roll 14 and spindle 18 decreases. Accordingly, as the roll 14 is depleted, the controller 26 reduces the tension on the belt 40 to compensate for the drawn off sheet material 12, since less friction force on the spindle 18 is required to slow the rotation of the spindle 18 and the roll 14 of sheet material 12. Thus, a friction force proportional to the diameter of the roll 14 is maintained on the spindle 18. In other words, to slow the rotation of a roll 14 of sheet material 12, a larger friction force is used for a larger roll 14, and a smaller friction force is used for a smaller roll 14.

[0034] This frictional resistance prevents or reduces the degree to which the sheet stock material 12 may overrun and continue to unwind from the roll 14 when the conversion machine 10 stops, and ensures that a proper tension is applied as the sheet stock material 12 is drawn from its respective roll 14. Without this proper tension and resistance, the sheet stock material 12 may unwind from the roll 14 in an uncontrolled and inconsistent manner, resulting in excess unwound sheet stock material 12 or tearing of the sheet stock material 12 that may interfere with the conversion process and decrease the quality of the resulting dunnage products. Additionally, the tension can be relieved before the conversion machine 10 begins to draw sheet material 12 from the supply 14, so that tension is not added to the force required to initiate rotation of the roll 14. The controller 26 can increase the tension applied up to the desired level once the roll 14 begins rotating so that when the conversion machine 10 stops the roll 14 does not unwind in an uncontrolled manner.

[0035] An exemplary method 100 of producing a dunnage product from sheet material is depicted in FIG. 5. The method includes the step 102 of providing a supply of sheet material as a roll. As noted above, the sheet material may be any suitable sheet material, such as but not limited to paper (e.g., kraft paper, tissue paper, etc.)

[0036] The method 100 also includes the step 104 of supporting the roll of sheet material on a spindle. The brake assembly may include a frame wherein a spindle is rotationally attached to the frame, whereby the spindle is free to rotate relative to its support structure.

[0037] The method 100 also includes the step of advancing 106 the sheet material from the supply in a downstream direction. Once the material is advanced downstream into the dunnage conversion machine, the method 100 then includes the step 108 of converting the sheet material into a dunnage product with lower density than the sheet material.

[0038] In an exemplary embodiment, the converting step includes the step 110 of creating tension in the sheet material transverse to the width dimension to cause the sheet material to expand to an expanded state. After creating tension, the method then includes the step 112 of reducing the tension of the sheet material. Once tension is fully removed, the sheet material is in an expanded relaxed state wherein the density of sheet material is lower than the sheet material on the roll.

[0039] After a desired length of dunnage product has been produced, the dunnage conversion machine is stopped or turned off. The method 100 includes the step 114 of applying friction to a spindle holding the roll of sheet material with the brake assembly 10 to resist rotational motion of the roll of sheet material. When the machine is turned off, the friction will minimize or eliminate overrun caused by rotational inertia of the roll. Thus, the step of applying friction to the spindle occurs before the machine is turned off.

[0040] The method also might include the step 116 of connecting overlapping layers of the sheet material in an expanded relaxed state to at least one cover sheet to hold the sheet material in the expanded state and to form a dunnage product.

[0041] Alternative converting steps may include inwardly gathering the sheet material, or randomly crumpling the sheet material, or otherwise deforming the sheet material into a lower density configuration than the starting sheet stock material in the roll.

[0042] In summary, an exemplary brake assembly for a dunnage conversion machine 10 includes a rotating spindle 18 connected to a location on a mounting surface of the dunnage conversion machine 10 configured to accept a roll 14 of sheet stock material 12. A tension belt 40 is configured to engage the spindle 18 and impart a friction force on the spindle 18. A tensioner 42 is configured to apply tension in the tension belt 40. Increasing tension in the tension belt 40 increases the friction force imparted on the spindle 18. A controller 26 is configured to control the tensioner 42. A sensor 50 is configured to detect an amount of sheet material 12 on a roll 14. The sensor 50 detects 52 an amount of sheet material 12 remaining on the roll 14 of sheet material as the sheet material 12 is drawn from the roll 14 and signals the controller 26. The controller 26 actuates the tensioner 42 to reduce the tenson in the tension belt 40 to compensate for the sheet stock material 12 drawn off of the roll 14 for conversion into a dunnage product 16.

[0043] Although the invention defined by the following claims has been shown and described with respect to a certain embodiment, equivalent alternations and modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In particular regard to the various functions performed by the above described integers (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such integers are intended to correspond, unless otherwise indicated, to any integer which performs the specified function of the described integer (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.

Claims

ClaimsWe claim:1 . A brake assembly for a dunnage conversion machine (10), the brake assembly comprising: a spindle (18) configured to accept a roll (14) of sheet material (12); a tension belt (40) having a tension and configured to engage the spindle (18) and impart a friction force on the spindle (18); a tensioner (42) configured to apply tension in the tension belt (40), whereby increasing tension in the tension belt (40) increases the friction force imparted on the spindle (18); a controller (26) configured to control the tensioner (42); a sensor (50) configured to detect an amount of sheet material on the roll (14); wherein the sensor (50) detects an amount of sheet material (12) remaining on the roll (14) and signals the controller (26), wherein, in response to the signal, the controller (26) actuates the tensioner (42) to reduce the tenson in the tension belt (40) to compensate for the amount of sheet material (12) drawn off of the roll (14).

2. The brake assembly as claimed in claim 1 , wherein the tensioner (26) is a pneumatic cylinder (46).

3. The brake assembly as claimed in claim 2, wherein the controller (26) controls the tensioner (42) by changing a pressure in a pneumatic line (48) connected to the pneumatic cylinder (46).

4. The brake assembly as claimed in claim 1 or any preceding claim, wherein the sensor (50) detects the amount of sheet material (12) on the roll (14) of sheet material by measuring a diameter of the roll (14).

5. The brake assembly as claimed in claim 1 or any preceding claim, in combination with a hollow cylindrical core for a roll (14) of sheet material (12), wherein the spindle (18) is configured to be received in the hollow cylindrical core.

6. The brake assembly as claimed in claim 4, wherein the sensor (50) is selected from a laser, an infrared light emitter, visible light emitter, a scale, and a camera.

7. The brake assembly as claimed in claim 4, wherein the sensor (50) is a probe configured to abut the roll.

8. A system for producing for producing a dunnage product from a sheet material provided on a roll, the system comprising: a dunnage conversion machine (10); a support for the roll (14) of sheet material (12); and a conversion assembly that converts the sheet material (12) into a dunnage product (16), the conversion assembly including a feeding assembly (22) that draws sheet material (12) from the roll (14); wherein the support includes the spindle (18) and brake assembly as claimed in claim 1 or any preceding claim.

9. The system as claimed in claim 8, comprising a frame that defines the mounting surface.

10. The system as claimed in claim 8, wherein the mounting surface is vertical.1 1. A method for producing a dunnage product from a sheet material, the method comprising the steps of: providing a roll of sheet material having a hollow cylindrical core;supporting the roll of sheet material on a spindle having a brake assembly as claimed in claim 1 or any preceding claim with the spindle received in the core; advancing the sheet material from the roll in a downstream direction; converting the sheet material into a dunnage product with a lower density than the sheet material; stopping the advancing step; and slowing the rotation of the roll of sheet material with friction resistance from the brake assembly.

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