Patent Publication Number: US-9884465-B2

Title: Dunnage conversion machine and method with downstream feed monitor

Description:
FIELD OF THE INVENTION 
     This invention relates generally to an apparatus and method for converting a stock material into a dunnage product, and more particularly to a dunnage conversion machine and method with means for controlling the speed at which the stock material is fed through the machine. 
     BACKGROUND 
     In the process of shipping one or more articles from one location to another, a packer typically places some type of dunnage material in a shipping container, such as a cardboard box, along with the article or articles to be shipped. The dunnage material partially or completely fills the empty space or void volume around the articles in the container. By filling the void volume, the dunnage prevents or minimizes movement of the articles that might lead to damage during the shipment process. Some commonly used dunnage materials are plastic foam peanuts, plastic bubble pack, air bags and converted paper dunnage material. 
     A supply of dunnage material can be provided to the packer in advance, or the dunnage material can be produced as it is needed. A dunnage conversion machine can be used to convert a supply of stock material, such as a roll or stack of paper, into a lower density dunnage product as it is needed by the packer. For example, U.S. Pat. No. 6,676,589 discloses a dunnage conversion machine that converts a continuous sheet of paper into a crumpled dunnage product. 
     The mechanism that feeds sheet stock material through a conversion machine can jam, causing the operator to stop the machine, open the machine&#39;s housing, physically reach into the machine to clear the stock material from where it is jamming the feed mechanism, close the machine&#39;s housing, and then go through a restart sequence before resuming dunnage conversion. Not only is this process time-consuming, but it also may lead to the production of a defective length of dunnage that must be discarded, increasing waste. Jamming is a more common occurrence with lower quality stock material. A jam condition occurs when the feed mechanism is unable to move stock material through the conversion machine, typically because the stock material has caught on something in its path, such as wrapping itself around a portion of the feed mechanism. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved electronic monitoring and control system for detecting and resolving many jamming conditions before they require significant operator intervention. By monitoring movement of the stock material downstream of a feeding device the system can detect a potential jam condition and control the feeding device to prevent or minimize the occurrence or severity of the jam condition, thereby minimizing the amount and degree of required operator intervention. The result is greater run time without required operator intervention and an improved ability to feed lower quality stock material without jamming. The present invention also can improve yield, defined as the length of the stock material compared to the volume of dunnage produced. 
     More particularly, the present invention provides a machine for converting a sheet stock material into a relatively lower density dunnage product, comprising a conversion assembly for converting a sheet stock material into a relatively lower density dunnage product, the conversion assembly including a feeding device to feed the sheet stock material through the conversion assembly; a sensor downstream of the feeding device to detect movement of the sheet stock material at a point downstream of the feeding device and providing an output corresponding to the movement; and a controller that controls the feeding device based on the output from the sensor. 
     In an exemplary embodiment, the controller controls the feeding device by slowing the feeding device when the sensor detects a jam condition where the feeding device is energized and no movement is detected by the sensor during a predetermined period. 
     The present invention also provides a method of controlling a machine that converts a sheet stock material into a relatively lower density dunnage product, comprising the following steps: feeding a sheet stock material through a conversion assembly; sensing movement of the sheet stock material downstream of the conversion assembly; and modulating the feeding step in response to the sensing step. The method may include the step of detecting operation of a feeding device that performs the feeding step, where the modulating step includes reducing the feeding step when the feeding device is operating and no movement is sensed during a predetermined period. If the sensing step includes detecting no movement for a predetermined time, then the modulating step may include stopping the feeding step. 
     The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and annexed drawings setting forth in detail certain illustrative embodiments of the invention, these embodiments being indicative, however, of but a few of the various ways in which the principles of the invention may be employed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary dunnage conversion machine provided by the present invention with a transparent housing to show internal components of the machine, as seen from above and looking in a downstream direction. 
         FIG. 2  is a perspective view of the machine of  FIG. 1 , as seen from below and looking in a downstream direction. 
         FIG. 3  is a top view, slightly in perspective, of the conversion machine of  FIG. 1 , with the transparent housing and an internal wall removed to more clearly show the internal components. 
         FIG. 4  is an enlarged perspective view of a downstream end of the conversion machine of  FIG. 1 , with the transparent housing removed to more clearly show the internal components. 
         FIG. 5  is an enlarged perspective view of a downstream end of the conversion machine of  FIG. 4  with additional internal wall structures removed to more clearly show the internal components of the machine. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings in detail,  FIGS. 1-3  show an exemplary embodiment of a dunnage conversion machine  10  provided by the present invention that provides an improved electronic monitoring and control system for detecting and resolving many jamming conditions before they require significant operator intervention. By monitoring movement of the stock material downstream of a feeding device the system can detect a potential jam condition and control the feeding device to prevent or minimize the occurrence or severity of the jam condition, thereby minimizing the amount and degree of required operator intervention. The result is greater run time without required operator intervention and an improved ability to feed lower quality stock material without jamming. The present invention also can improve yield, defined as the length of the stock material compared to the volume of dunnage produced. 
     The conversion machine  10  includes a conversion assembly  12  that has a forming device  14  for guiding and inwardly gathering sheet stock material, a feeding device  16  downstream of the forming device  14  that pulls the sheet stock material from a supply (not shown), through the forming device  14 , and through an output chute  20  and out an outlet  22 . The conversion assembly  12  also includes a severing device  24  downstream of the feeding device  16  for severing discrete lengths of sheet material, and a sensing device  26  downstream of the feeding device  16  for monitoring movement of the sheet material adjacent the sensing device  26 . The sensing device  26  can be upstream or downstream of the severing device  24 . The severing  24  device can be omitted, such as where the sheet stock material is already provided in discrete lengths or where discrete lengths are otherwise readily separable, such as by use of a perforated or otherwise weakened stock material that is easily torn. The conversion machine  10  also includes a housing  28  that encloses the conversion assembly  12 , and which must be opened or removed to clear a jam and thus resolve a jam condition where the feeding device  16  cannot feed the stock material. The machine  10  also includes a mounting bracket  29  for mounting the machine  10  to a stand or other support. 
     The forming device  14  includes a converging chute  30  that converges in at least one dimension in a downstream direction. In other words, as the stock material moves through the conversion machine  10  in an upstream-to-downstream direction, a dimension of the converging chute  30  at an upstream end is larger than a corresponding dimension at a downstream end. In particular, a width dimension corresponding to a width dimension of a sheet stock material is reduced to inwardly gather and crumple sheet stock material as it moves through the chute  30 . The forming device  14  also includes a constant entry member  32 , which in the illustrated embodiment is formed by a pair of rollers  34  aligned end-to-end and positioned at an angle relative to one another. These rollers  34  have rounded ends that allow for some reduction in tension at the edge of the sheet stock material as it is fed into the conversion assembly  12 . More particularly, the sheet stock material is fed over the constant entry member  32  and into the converging chute  30 . The illustrated chute  30  converges in a both width and height as the stock material moves from an upstream end to a downstream end of the converging chute  30 . Regardless of the angle at which the conversion machine  10  is mounted relative to the supply of stock material, the constant entry member  32  guides the stock material into the converging chute  30  along the same path. The constant entry member  32  provides a constant entry plane for the stock material entering the converging chute  30 . 
     The converging chute  30  acts as a funnel and typically is formed as a fixed shape. To provide some adjustability in the amount of inward gathering of the stock material, the illustrated forming device  14  provides a pair of vertical rollers  36  and multi-position mounting tabs  40  at an upstream end the converging chute  30 . The mounting tabs  40  provide multiple mounting positions relative to the converging chute  30  for adjusting the effective width of the converging chute  30 . At a downstream end of the converging chute  30  the forming device  14  includes another pair of vertical rollers  42  that are closely spaced in fixed positions to further guide the stock material from the converging chute  30  and toward the feeding device  16 . These fixed-position rollers  42 , like the upstream adjustable-position rollers  34 , are not powered and preferably freely rotate. The narrow gap between the fixed-position rollers  42  can help to crease folds in the sheet stock material that were formed during the gathering and converging process in the converging chute  30 . A tunnel member  44  leads from these rollers  42  at the downstream end of the converging chute  30  to the feeding device  16 . The tunnel member  44  constrains the sheet stock material in its crumpled state and guides the crumpled stock material to the feeding device  16 . 
     Turning now to  FIGS. 4 and 5 , the feeding device  16  feeds the sheet stock material through the conversion assembly  12  and out the conversion machine  10 . In the illustrated embodiment the feeding device  16  includes at least one rotatable feed member that extends into the path of the sheet stock material. More particularly, the feeding device  16  includes first and second rotatable feed members  46  and  50  on respective opposite sides of the path of the sheet stock material to feed the sheet material therebetween. The tunnel member  44  that is part of the forming device  16  also helps to define the path for the sheet stock material up to and through the feeding device  16 . 
     The feed members  46  and  50  in the illustrated embodiment include a pair of resilient wheels  51  and  52 , one of which is driven by a motor  54  and a gearbox  56 , the motor  54  being controlled by a controller  60  (shown schematically). The controller  60  controls the feeding device  16  based on the output from the sensor  62  in the sensing device  26 , which is described further below. This is accomplished by controlling the feed motor  54 , for example. 
     The illustrated wheels  51  and  52  are made of a resilient material and include holes that further facilitate movement of the wheel material to allow the sheet material to pass between the closely-spaced feed wheels  51  and  52 . An elastomeric or rubber-like material can be used to make the feed wheels  51  and  52  such that they will have both the necessary resiliency and sufficient friction to engage and pull the sheet stock material from the supply, through the forming device  14 , through the feeding device  16 , past the severing device  24  and out the output chute  20 . Alternatively, the feed members can be paddle wheels or gears, either of which would advance the sheet stock material. Depending on their spacing, these types of feed member also could crimp, cut, or otherwise act on the sheet stock material passing through the feeding device. If non-resilient feed members are employed, at least one feed member is preferably resiliently biased into the path of the sheet material. 
     The severing device  24  includes a guillotine-style cutting blade  66  that is driven by a cut motor  70  to travel across the path of the sheet stock material. The controller  60  also controls operation of the cut motor  70  and thus the severing operation. In an exemplary embodiment, the controller  60  includes a logic instruction that prohibits the severing device  24  from operating while the feeding device  16  is operating or during a detected jam condition. Alternatively, a single motor may be employed and a clutch can be employed to selectively drive either the feeding device  16  or the severing device  24 . 
     The walls  72  of the output chute  20  define a passage downstream of the severing device  24 . These walls  72  define a path from the severing device  24  out of the conversion machine  10  and further assist in constraining the sheet stock material and help to maintain column strength in the sheet stock material so that additional sheet stock material moving downstream can push the severed length of dunnage out of the output chute  20  through the outlet  22 . 
     Also downstream of the feeding device  16  and the severing device  24  is a sensor  62  for the sensing device  26  for detecting movement of the sheet stock material at a point downstream of the feeding device  16 . The sensor  62  provides an output corresponding to the sensed or detected movement. In the illustrated embodiment, the sensing device  26  includes a pair of wheels  74  and  76 , one of which  76  is biased by a spring  80  toward the other wheel  74 , which is mounted for rotation in a fixed position but which extends through a wall  72  of the output chute  20  and into the path of the stock material to engage the stock material and detect whether or not the stock material is moving. The sensing device  26  does this through an encoder  84  mounted to the axle of the rotating wheel  74  to monitor rotation of the axle to which the wheel  74  is attached. The axes of the sensing wheels  74  and  76  are parallel to the axes of the feeding wheels  51  and  52 . This is believed to provide better tracking of the sensing wheels against the sheet stock material. The respective pairs of axes are not limited to this arrangement and the respective axes may be offset or even perpendicular. The encoder  84  converts motion of the shaft into an electronic signal that it communicates with the controller  60 , either through a wire or wirelessly. Thus the sensor  62  is the encoder  84 . 
     In an exemplary embodiment, the controller  60  monitors the signal output from the sensor  62 . When the feeding device  16  is activated to feed sheet stock material, and after a suitable delay to ensure that the stock material has time to travel from the feeding device  16  to the sensor  62 , the controller  60  monitors the signal output from the sensor  62 . If the signal indicates no motion or movement at a rate below a predetermined value, a percentage, or an amount of decrease in movement, the controller  60  will slow or stop the feed motor  54  for a predetermined time. The feeding device is restarted after a predetermined time or after a signal input by an operator. In our experience, many times an operator can pull on a section of the stock material that extends from the machine  10  and then continue the operation of the feeding device  16  without having to open the housing to clear a jam. Thus the controller  60  is effectively preventing a jam condition and detecting a potential for a jam before a significant jam condition occurs that would require more time-consuming intervention. 
     In detecting movement of the sheet stock material the sensor  62  may also detect the speed of the stock material. The controller  60  can then control the feeding device  16  by slowing the feeding device  16  when the sensor  62  detects a jam condition. The condition can exist where the downstream speed falls from a first speed above a predetermined value to a second speed at or below the predetermined value. The jam condition exists when the feeding device  16  is energized and no movement is detected by the sensor  62  during a predetermined period, for example. The sensing device  62  can also include an output device  82  (shown schematically) connected to the controller  60  to output an alert to alert an operator that a jam condition exists. The output device can include a light or a speaker or other means for alerting the operator. 
     In an alternative embodiment (not shown), the sensing device  26  can include a second sensor that detects operation of the feeding device  16 , such as an encoder mounted to one of the feed wheels  51  or  52 . This would allow the controller  60  to compare the speed at the feed wheels  51  and  52  to the speed at the sensor wheels  74  and  76 . The speed could be determined assuming that the sheet stock material would be moving at the same speed as a peripheral portion of the respective wheel where it engages the sheet stock material. 
     The controller  60  can also include an input device  83  (shown schematically) connected to the controller  60  for an operator to indicate that a jam condition has been resolved. The input device can include a switch, a footswitch, a button switch, a keypad or any other switch that would allow the conversion machine to resume operation after resolution of the jam condition. 
     In operation, when the controller  60  detects a potential jam condition, based on the signal received from the sensor  62 , the controller  62  slows down or stops the feed motor  54  and thus the feeding device  16 . After a predetermined time, the controller  60  can return the feed motor  54  and feeding device  16  to full speed operation and the potential jam condition often will resolve without any operator intervention. In some circumstances, the operator pulls on a portion of the sheet material extending from the outlet  22  before the controller  60  resumes full speed of the motor  54  and the feeding device  16 , either automatically after a predetermined time or upon receiving a signal from the operator via the input device  83 . Again, the operator&#39;s intervention is simple and does not require the time-consuming procedure of opening the housing  28  of the conversion machine  10  to clear the jam. The operator may observe the slowing or stopping of the feeding device  16 , or the controller  60  can provide a signal to the output device  82  to alert the operator to the potential for a jam condition so that the operator can assist the controller  60  in resolving the jam condition before a more time-consuming procedure is required. 
     The controller  60  can store in memory the number of potential jam conditions and their time or frequency to facilitate maintenance and repair at a scheduled down time for maintenance. The controller  60  also could alert an operator to frequent potential jam conditions as a way of signaling a need for maintenance or inspection. In this way the controller both prevents potential jam conditions from becoming more time-consuming for the operator during operation and provides a record for improving maintenance procedures to further minimize or eliminate time-consuming jam conditions. 
     Early detection and prevention of jam conditions also facilitates the use of different grades of sheet stock material. As a result, the same conversion machine or type of conversion machine can operate with both high and low quality sheet stock material, and/or different thicknesses or basis weights of stock material. This flexibility makes operation of the machine more economical since a user&#39;s needs may change over time. 
     Putting it another way, the present invention provides a conversion machine  10  with a conversion assembly  12  that includes means for feeding a sheet stock material through the conversion assembly, means for sensing movement of the sheet stock material downstream of the conversion assembly  12 , and means for controlling the feeding means in response to a signal from the sensing means. In this characterization, the feeding means includes a rotatable feed member  46  or  50  that extends into a path of sheet material, the sensing means includes a rotatable member  74  or  76  that extends into a path of sheet material downstream of the feed member  46  or  50 , and an encoder  84  coupled to the rotatable member  74 . The modulating means includes a controller  60  coupled to the rotatable feed member via the encoder  84 . The controller  60  can control operation of the rotatable feed members  51  and  52  in response to signals from the encoder  84 . 
     In summary, the present invention provides a dunnage conversion machine  10  that provides an improved electronic monitoring and control system for detecting and resolving many jamming conditions before they require significant operator intervention. The machine includes  10  a conversion assembly  12  with a feeding device  16  that feeds the sheet stock material through the machine  10 , and a sensing device  26  downstream of the feeding device  16  to monitor movement of the stock material downstream of the feeding device  16  and to output a corresponding signal. A controller  60  controls operation of the feeding device  16  in response to the signal from the sensing device  26 . The controller  60  uses the signal to detect a potential jam condition and controls the feeding device  16  to prevent or minimize the occurrence or severity of the jam condition, thereby minimizing the amount and degree of required operator intervention. 
     The present invention provides one or more of the features described in the following clauses: 
     A. A machine  10  for converting a sheet stock material into a relatively lower density dunnage product, comprising: a conversion assembly  12  for converting a sheet stock material into a relatively lower density dunnage product, the conversion assembly  12  including a feeding device  16  to feed the sheet stock material through the conversion assembly  12 ; a sensor  62  downstream of the feeding device  16  to detect movement of the sheet stock material at a point downstream of the feeding device  16  and providing an output corresponding to the movement; and a controller  60  that controls the feeding device  16  based on the output from the sensor  62 . 
     B. A machine  10  as set forth in clause A or any other clause that depends from clause A, where the sensor  62  detects the speed of the stock material and the controller  60  controls the feeding device  16  by slowing the feeding device  16  when the sensor  62  detects a jam condition where the downstream speed falls from a first speed above a predetermined value to a second speed at or below the predetermined value. 
     C. A machine  10  as set forth in clause A or any other clause that depends from clause A, where the controller  60  controls the feeding device  16  by slowing the feeding device  16  when the sensor  62  detects a jam condition where the feeding device  16  is energized and no movement is detected by the sensor  62  during a predetermined period. 
     D. A machine  10  as set forth in clause A or any other clause that depends from clause A, where the feeding device  16  includes at least one rotatable feed member  46  that extends into a path of the sheet material. 
     E. A machine  10  as set forth in clause D or any other clause that depends from clause D, where the feeding device  16  includes a pair of feed members  46  and  50  on opposing sides of the path of the sheet material to feed the sheet material therebetween. 
     F. A machine  10  as set forth in clause D or any other clause that depends from clause D, where the sensor  62  includes at least one wheel  76  that is biased into the path of the sheet material and is movable out of the path of the sheet material. 
     G. A machine  10  as set forth in clause D or any other clause that depends from clause D, where the at least one feed member  46  or  50  includes at least one of a friction wheel, a paddle wheel, and a gear. 
     H. A machine  10  as set forth in clause D or any other clause that depends from clause D, where the sensor  62  includes a rotatable member  74  or  76  extending into a path of the sheet material and an encoder  84  connected to the controller  60  that converts rotation of the rotatable member  74  or  76  into an electrical signal output to the controller  60 . 
     I. A machine  10  as set forth in clause A or any other clause that depends from clause A, where the conversion assembly  12  includes a converging chute  30  upstream of the feeding device  16  that converges in at least one dimension in an upstream-to-downstream direction. 
     J. A machine  10  as set forth in clause A or any other clause that depends from clause  1 , further comprising a severing device  26  downstream of the feeding device  16  to sever discrete lengths of dunnage from the sheet material, the controller  60  controlling the severing device  26  in coordination with the feeding device  16 . 
     K. A machine  10  as set forth in clause A or any other clause that depends from clause A, further comprising an output device coupled to the controller  60  to alert an operator that a jam condition exists. 
     L. A machine  10  as set forth in clause A or any other clause that depends from clause A, comprising a sensor  62  that detects operation of the feeding device  16 . 
     M. A machine  10  as set forth in clause A or any other clause that depends from clause A, further comprising an input device coupled to the controller  60  for an operator to indicate that a jam condition has been resolved. 
     N. A method of controlling a machine that converts a sheet stock material into a relatively lower density dunnage product, comprising the following steps: feeding a sheet stock material through a conversion assembly; sensing movement of the sheet stock material downstream of the conversion assembly; modulating the feeding step in response to the sensing step. 
     O. A method as set forth in clause N or any other clause that depends from clause  14 , where the modulating step includes slowing the feed speed when the downstream speed falls from a first speed above a predetermined value to a second speed at or below the predetermined value. 
     P. A method as set forth in clause O or any other clause that depends from clause O, where the modulating step includes slowing the feed speed by at least one of a predetermined absolute amount, and a predetermined percentage, or slowing the feed speed to a predetermined reduced speed that is less than the feed speed. 
     Q. A method as set forth in clause N or any other clause that depends from clause N, comprising the steps of detecting operation of a feeding device that performs the feeding step, where the modulating step includes reducing the feeding step when the feeding device is operating and no movement is sensed during a predetermined period. 
     R. A method as set forth in clause P or any other clause that depends from clause P, where the modulating step includes stopping the feeding step. 
     S. A method as set forth in clause P or any other clause that depends from clause P, where the modulating step includes increasing the feed speed a predetermined time after the slowing step. 
     T. A method as set forth in clause S or any other clause that depends from clause S, where the modulating step includes increasing the feed speed after the slowing step in response to an operator input. 
     U. A method as set forth in clause N or any other clause that depends from clause N, where if the sensing step includes detecting no movement for a predetermined time, then the modulating step includes stopping the feeding step. 
     V. A machine  10  for converting a sheet stock material into a relatively lower density dunnage product, comprising: a conversion assembly  12  including means  16 ,  46  and  50 ,  51  and  52 ,  54 ,  56  for feeding a sheet stock material through the conversion assembly  12 ; means  26 ,  62 ,  74  and  76 ,  84  for sensing movement of the sheet stock material downstream of the conversion assembly  12 ; and means  60  for controlling the feeding means in response to a signal from the sensing means. 
     W. A machine  10  as set forth in clause V or any other clause that depends from clause V, where the feeding means includes a rotatable feed member  46  or  50  that extends into a path of the sheet material, the sensing means includes a rotatable member  74  or  76  that extends into a path of the sheet material downstream of the feed member and an encoder  84  coupled to the rotatable member  74  and  76 , and the modulating means includes a controller  60  coupled to the rotatable feed member  74  and  76  and the encoder  84 . 
     Although the invention has been shown and described with respect to a certain illustrated embodiment or embodiments, equivalent alterations and modifications will occur to others skilled in the art upon reading and understanding the 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 (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated embodiment or embodiments of the invention.