Abstract:
A cushioning conversion system includes a cushioning conversion machine which converts stock paper into a plurality of cut pads, and a conveyor system positioned to receive pads produced by the cushioning conversion machine and including a conveyor which conveys the pads away from the machine and at least one moveable gate having an open position allowing a pad to pass, therethrough and a closed position for stopping progress of a pad along the conveyor when there is insufficient space on the conveyor downstream of the gate to permit a pad to progress substantially through the gate.

Description:
RELATED APPLICATIONS 
     This application is a divisional of Ser. No. 08/951,277, now U.S. Pat. No. 5,868,657 filed Oct. 16, 1997 which is file wrapper continuing application of Ser. No. 08/486,863 filed Jun. 7, 1995, now abandoned, entitled “Cushioning Conversion Machine System, Outlet Conveyor and Assembly”. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to a cushioning conversion machine which converts paper stock into cushioning material, and more particularly, to a cushioning conversion machine an outlet conveyor and an assembly for preventing accumulating pads from nesting becoming damaged or causing jamming of the cushioning conversion machine. 
     BACKGROUND OF THE INVENTION 
     In the process of shipping an item from one location to another, a protective packaging material is typically placed in the shipping container to fill any voids and or to cushion the item during the shipping process. Some commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to perform adequately as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and or plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable and thus they cannot avoid further multiplying our planet&#39;s already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility. 
     These and other disadvantages of conventional plastic packaging materials have made paper protective packaging material a very popular alternative. Paper is biodegradable, recyclable and renewable; making it an environmentally responsible choice for conscientious companies. 
     While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a low density cushioning product. This conversion may be accomplished by a cushioning conversion machine, such as those: disclosed in U.S. Pat. Nos. 4,026,198; 4,085,662; 4,109,040; 4,237,776; 4,557,716; 4,650,456; 4,717,613; 4,750,896; and 4,968,291. (These patents are all assigned to the assignee of the present invention and their entire disclosures are hereby incorporated by reference.) Such a cushioning conversion machine converts sheet-like stock material, such as paper in multi-ply form, into low density cushioning pads or dunnage. 
     A cushioning conversion machine, such as those disclosed in the above-identified patents, may include a stock supply assembly, a forming assembly, a gear assembly, and a cutting assembly, all of which are mounted on the machine&#39;s frame. During operation of such a cushioning conversion machine, the stock supply assembly supplies the stock material to the forming assembly. The forming assembly causes inward rolling of the lateral edges of the sheet-like stock material to form a continuous strip having lateral pillow-like portions and a thin central band. The gear assembly, powered by a feed motor, pulls the stock material through the machine and also coins the central band of the continuous strip to form a coined strip. The coined strip travels downstream to the cutting assembly which cuts the coined strip into pads of a desired length. 
     Typically, the cut pad is transferred downstream to a transitional zone, such as a table, a conveyor, a bin, etc., and is thereafter removed from the transitional zone and inserted within a container for cushioning purposes. In the past, the transitional zone has been positioned beneath the cutting assembly whereby gravity caused the pad to fall towards the transitional zone, or, in other words, away from the cutting assembly. Additionally or alternatively, the approaching coined strip would urge the cut pad in this direction. 
     The practice of depending upon the force of gravity and or the urging of the approaching strip for pad-transferring purposes has, for the most part, been very successful. Nevertheless, applicant appreciated that in certain circumstances (such as high constant volume cushioning situations), pad-transfer problems sometimes, albeit very rarely, occurred. For example, because of the lightweight nature of the pad, one would occasionally fail to travel downstream to the transitional zone. While, in most instances, the approaching pads would eradicate this failure by pushing the “stalled” pad downstream, periodically the approaching pads would instead “shingle” (ie., the pads would stack one on top of the other in a shingle-like arrangement). Such shingling (although itself uncommon) would usually result in the “jamming” of the cushioning conversion machine and this jamming would almost always translate into machine downtime. 
     Further, problems could arise from the accumulation of a large number of pads in the transitional zone, such as on a conveyor. While the use of a conveyor, generally works well in conveying formed pads away from the cushioning conversion machine, if the conveyor were to become filled with pads, the pads would tend to nest or shingle resulting in the difficult removal of the pads from the conveyor and possible damage to the pads. 
     SUMMARY OF THE INVENTION 
     The present invention provides a cushioning conversion system including a cushioning conversion machine and a conveyor system which conveys pads away from the machine while preventing pads from becoming nested or forced together. The conveyor system includes a series of stop gates which permit a pad to pass by when there is sufficient space for the pad on the conveyor downstream of the stop gate and which stops the progress of the pad along the conveyor when there is insufficient space for the pad. Each stop gate is preferably controlled by an associated sensor located downstream of the gate. A sensor may also be used to determine and communicate to the cushioning conversion machine that there is insufficient space on the conveyor for a new pad, whereupon the machine can discontinue its production of pads until space is available thereby decreasing the potential for jams in the machine. 
     In accordance with one aspect of the invention, a cushioning conversion system includes a cushioning conversion machine which converts stock paper into a plurality of cut pads, and a conveyor system positioned to receive pads produced by the cushioning conversion machine and including a conveyor which conveys the pads away from the machine and at least one moveable gate having an open position allowing a pad to pass therethrough and a closed position for stopping progress of a pad along the conveyor when there is insufficient space on the conveyor downstream of the gate to permit a pad to progress substantially through the gate. 
     In accordance with a further aspect of the invention, a cushioning conversion system includes a cushioning conversion machine which converts stock paper into a plurality of cut pads, and a conveyor system positioned to receive pads produced by the cushioning conversion machine and including a conveyor which conveys the pads away from the machine and at least one moveable gate having an open position allowing a pad to pass therethrough and a closed position for stopping progress of a pad along the conveyor. 
     In accordance with a still further aspect of the invention, a cushioning conversion system includes a reversible conveyor system, and a cushioning conversion machine located at each end of the reversible conveyor system, each machine for selectively converting stock paper into a plurality of cut pads and depositing the pads on the conveyor system when active, the reversible conveyor system including a conveyor which conveys the pads away from the active machine and at least one moveable gate having an open position allowing a pad to pass therethrough and a closed position for stopping progress of a pad along the conveyor. 
     In general, the invention comprises the foregoing and other features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrated embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the annexed drawings: 
     FIG. 1 is an elevation view of a cushioning conversion machine including the conveyor system of the present invention; 
     FIG. 2 is a cutaway view of the opposite side of the cushioning conversion machine of FIG. 1; 
     FIG. 3 is an illustration of a section of the conveyor system of FIG. 1 showing the stop gate assembly; 
     FIGS. 4A through 4D are top views of the conveyor system of FIG. 1 illustrating the progression of pads along the conveyor; 
     FIG. 5 is a top view of an ordinary conveyor system illustrating the shingling and nesting problems associated with such a conveyor; 
     FIG. 6 is a top view of an alternate cushioning conversion system including a reversible conveyor with a cushioning conversion machine located at either end of the conveyor; and 
     FIG. 7 is a view of a section of the conveyor system of FIG. 5 showing the area of the stop gate assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings and initially to FIGS. 1 and 2, there is shown a cushion conversion system  8  including a cushioning conversion machine  10  having a pad-transferring assembly  12  positioned at its exit  13  for transferring the cushioning product, or pads  14 , produced by the machine to a conveyor system  16  occupying the transitional zone  17  of the machine. The conveyor system  16  urges the pads away from the machine  10  while permitting the pads to be removed by an operator from any position on the conveyor for use in providing cushioning to a container. 
     The cushioning conversion machine  10  includes a frame  18  by which are supported the various components for converting stock material, such as kraft paper, to a strip of cushioning product and cutting the strip into sections, called pads. Such components include a stock supply assembly  19 , a forming assembly  20  for forming the stock material into the strip of cushioning product  21 , a feed assembly  22  for feeding stock material through the forming assembly and out the machine exit  13  to the pad-transferring assembly  12 , and a cutting assembly  24  for cutting the strip of cushioning material into pads of a desired length. Preferably operation of the pad-transferring assembly  12 , the feed assembly  22  and the cutting assembly  24  are controlled by a controller (shown schematically at  26 ), such as the controller described in co-owned U.S. patent application Ser. No. 08/279,149 which is incorporated herein by this reference. 
     During the conversion process, the forming assembly  20  causes the lateral edges of the stock material to roll inwardly to form a continuous strip having two lateral pillow-like portions and a central band therebetween. The feed assembly  22  performs a “pulling” function by drawing the continuous strip through the nip of two cooperating and opposed gears  27  thereby drawing stock material through the forming assembly  20  for a duration determined by the length of time that a feed motor  29  rotates the opposed gears. The feed assembly  22  additionally performs a “coining” or “connecting” function as the two opposed gears  27  coin the central band of the continuous strip as it passes therethrough to form a coined strip. As the coined strip travels downstream from the feed assembly  22 , the cutting assembly  24  cuts the strip into sections or pads  14  of a desired length. These cut sections then preferably travel through a post-cutting constraining assembly (not shown) and exit to the pad-transferring assembly  12 . 
     The pad-transferring assembly  12 , as is more fully described in co-owned U.S. patent application Ser. No. 08/154,911 which is incorporated herein by this reference, cooperates with the conveyor system  16  to engage the leading edge of a pad  14  just prior to being cut by the cutting assembly  24  and to pull the pad away from the cutting assembly and the machine  10 . Typically, the pad-transferring assembly  12  would include a belt spaced from the conveyor of the conveyor system  16  to gently compress and frictionally engage the pad  14  therebetween to transfer the pad from the machine exit  13  to the conveyor system to be further conveyed from the machine  10  for use by an operator. 
     Referring to FIGS. 1 through 4, the conveyor system  16  includes a continuous belt conveyor  30  extending between a pair of end rollers  32  located at distal ends of the conveyor system. The conveyor  30  may be one of many suitable types and finishes with a coefficient of friction between the conveyor and the pad so as to cause the pad to move with the conveyor while permitting the pad to slide relative to the conveyor without damage to the pad when the pad has reached the end of the conveyor or is otherwise prohibited from movement such as by another pad or by a stop gate assembly  34 , as is described more fully below. The conveyor  30  is powered in a conventional manner by a conveyor motor, not shown, which may, for example, have a roller which frictionally engages the conveyor to cause linear movement of the conveyor or which may rotate one of the end rollers  32  to move the conveyor. A pad  14  transferred to the conveyor  30  by the pad-transferring assembly  12  will thus generally progress away from the machine  10  toward the pad stop  35  located at the end of the conveyor distal from the machine. 
     At either lateral side of the conveyor  30  and extending substantially the length of the conveyor is a guide rail  36 . Positioned above the conveyor  30  are a number of hold-down rods  38  also running substantially the length of the conveyor with breaks in the vicinity of each stop gate assembly  34 . The guide rails  36  and hold-down rods  38  maintain the pads in a generally ordered, single file arrangement on the conveyor  30 . The guide rails  36  are held in position above the conveyor by connection with an overhead frame assembly  40  which is in turn supported on each side of the conveyor  30  by a pair of outer support rails  42 . 
     Each stop gate assembly  34  includes a gate  44  comprised of a rod  46  terminating in a contact foot  48  and which is moveable between an upper or open position out of the way of the pads  14  as they move along the conveyor  30  and a lower or closed position in which the contact foot stops a pad from further movement with the conveyor. The position of the gate  44  is controlled by a pneumatic cylinder  50  within which one end of the rod  46  is disposed or through another similar means, such as a solenoid or motor. Each stop gate assembly  34  includes an overhead frame assembly  52  which supports the pneumatic cylinder  50  and is in turn supported at each side of the conveyor by the outer support rails  42 . The stop gate assemblies  34  are preferably arranged relative to the end of the conveyor  30  and spaced relative to each other so that a number of pads fit in a single file order between the last stop gate assembly  34  and the ends of the conveyor and between the stop gate assemblies with a small gap between the last pad in the series of pads and the stop gate assembly. 
     Associated with and located downstream of each stop gate assembly  34  is a sensor  54  for sensing the presence of a stopped pad. The spacing of the sensor  54  from the associated stop gate assembly  34  is preferably such that upon the detection of a stopped pad, the stop gate  44  can close with the contact foot  48  positioned between successive pads on the conveyor, although the stop gate may close with a pad located below the contact foot. The sensor  54  is preferably located between the guide rails  36  and the outer support rails  42  and located adjacent openings  56  in the guide rails. The sensor may be implemented as a separate emitter  54   a  and receiver  54   b  located on opposite sides of the conveyor  30 , as illustrated in the figures, or the emitter and receiver may be embodied in a single device with a retroreflector located opposite the single device. The sensor  54  preferably is a time delay photoelectric sensor which generates an electrical control signal upon the interruption of an optical signal by a pad for a predetermined period of time to ensure that the pad is stopped. An exemplary series of suitable photoelectric sensors is manufactured by Automatic Timing and Controls Company, Inc. of Prussia, Pa. and designated as series 7080. The signal generated by the sensor  54  is used to control the solenoid on the stop-gate assembly  34  through appropriate control circuitry not shown in the figures. 
     As shown in FIGS. 4A through 4D, a sensor  58 , such as a photoelectric sensor similar to sensor  52  without a time delay, is located near the exit  13  of the cushioning conversion machine  10  just past the pad-transferring assembly  12  and senses the presence of a stopped pad  14  near the exit of the machine. The sensor  58  provides a control signal indicating the detection of pad to the machine  10 , preferably the machine controller  26 . The control signal from the sensor  58  may be analyzed with other control signals, such as a signal generated by a sensor (not shown) within the pad-transferring assembly  12  and other machine information, such as whether the machine is in a feed operation or a cutting operation, and appropriate action taken by the controller  26 . For instance, if the controller  26  determines that the machine  10  is performing a feed operation, i.e., the feed motor  29  is running, and the sensor  58  has detected the presence of a pad  14  without interruption for, a certain length of time, the controller may deactivate the feed motor to prevent further production of pads until the pad adjacent the sensor  58  has been conveyed past the sensor by the conveyor  30 . In this manner the machine  10  can controllably produce pads only when there is space on the conveyor  30  for additional pads thereby decreasing the possibility of pads becoming jammed in the cutting or feed assemblies  24 ,  22 , respectively, as a result of backpressure from previously formed pads. 
     In the absence of the stop gate assembly  34  and sensors  52  and  58 , pads  14  will be continually produced by the machine  10  and transferred to the conveyor  30  by the pad transferring assembly  12  without regard to the number of pads on the conveyor, as shown in FIG.  5 . In such a situation, when pads  14  are not removed from the conveyor  30  by an operator as the conveyor fills with pads, the leading pad  14   a  will contact the pad stop  35  at the end of the conveyor and pads will begin to accumulate behind the leading pad  14   a . As pads  14  are added to the conveyor  30  but a corresponding number are not removed, the pads nearer the pad stop  35  will begin to nest and reorient themselves on the conveyor  30  as a result of the pressure from the series of pads  14  behind those pads as they are continually urged by the movement of the conveyor  30  away from the machine  10 , as shown generally at  60 . This nesting and reorientation of the pads on the conveyor makes it difficult for an operator to remove one pad at a time and may cause damage to the pads, such as the pad becoming unconnected or uncoined, upon the operator attempting to pull a pad from the conveyor. In many instances it may also be difficult to remove only one pad at a time from the conveyor and the operator may be forced to manually separate the pads thus slowing the process of the operator removing a pad from the conveyor and placing it in a container for packaging. Despite the presence of the hold down rods  38 , the force of the accumulated pads as they continue to be urged towards the pad stop  35  may also cause the pads to slide over top one another or shingle, also making removal from the conveyor difficult and potentially damaging to the pad. 
     The present invention overcomes these problems through the use of the stop gate assembly  34  and sensors  52  and,  58 . Referring to FIGS. 4A-4D and initially to FIG. 4A there is shown a conveyor system  16  in a condition completely filled with pads. (In FIGS. 4A through 4D for ease of discussion, the stop gate assemblies  34  are shown as  34   a  and  34   b  with the stop gate  34   a  being closer to the pad stop  35 .) With the conveyor filled with pads, the stop gate assemblies  34   a  and  34   b  are both in their closed conditions. Referring to the area  62  of the conveyor  30  there are shown three pads  14  aligned behind the leading pad  14   a  which is in contact with the pad, stop  35 . The third pad  14   b  aligned behind the leading pad  14   a  is stopped adjacent the sensor  54  downstream of the stop gate assembly  34   a . As the sensor  54  will detect the presence of the stopped pad  14   b  it generates a control signal which causes the stop gate  34   a  to close. A series of pads thus begins to accumulate in the area  64  located between the stop gate assemblies  34   a  and  34   b.    
     Once a number of pads  14  have accumulated in the area  64 , the presence of a stopped pad will be detected by the sensor  54  immediately downstream of the stop gate assembly  34   b  which will thus generate a control signal which causes the stop gate  34   b  to close. The pads  14  will then accumulate behind the stop gate assembly  34   b  in the area  66  between the stop gate assembly  34   b  and the machine  10 . Once a number of pads have accumulated in this area  66  and have backed up so that the last pad in the series is adjacent the sensor  58 , the sensor will detect the presence of the stopped pad and inform the controller  26  of the machine  10  of the presence of the stopped pad and the machine  10  may then take appropriate action to stop operation of the feed assembly  22  until there is sufficient room on the conveyor  30  for additional pads  14 . Since only a limited number of pads  14  may accumulate in any given area  62 ,  64 ,  66  of the conveyor  30 , the accumulated pressure of the pads as they are urged away from the machine  10  by the conveyor  30  is not sufficient to cause the pads to become misaligned on the conveyor  30 , to become nested or to begin to stack or shingle. Consequently, the pads  14  are presented in an ordered fashion and are easy to remove from the conveyor  30  by an operator and also do not jam the machine  10 . 
     When a pad is removed from the conveyor  30 , such as pad  14   a  from area  62 , the pads in that area will then progress along the conveyor  30  away from the machine  10  as indicated by arrow  68  in FIG.  4 B. As the pads progress away from the machine  10  the pad  14   b  will move away from the sensor  54  downstream of the stop gate assembly  34   a , thus causing the stop gate to open. When the stop gate assembly  34   a  opens, as shown in FIG. 4C, the pads  14  accumulated in the area  64  will also begin to progress away from the machine  10  as indicated by arrow  70 . As the pads  14  in the area  64  progress, the trailing pad will move away from the sensor  54  downstream of the stop gate assembly  34   b , thus causing stop gate assembly  34   b  to open, as shown in FIG.  4 D. 
     Once the stop gate  34   b  has opened, the pads accumulated in the area  66  will progress away from the machine  10 , as shown by arrow  72 , and the last pad in the accumulated series of pads will be conveyed away from the sensor  58 . When the sensor  58  detects that there is an opening on the conveyor  30 , the controller  26  will cause the feed assembly  22  to create another pad which will be transferred to the conveyor  30  by the pad-transferring assembly  12  as indicated by arrow  74 . This process will continue as pads are removed from the conveyor  30 . It is noted that pads do. not have to be removed from the area  62  alone, but can be removed from the other areas of the conveyor such as areas  64  or  66  whereupon the same process as described above will occur upstream of the removed pad. In the event that a period of time progresses where no pads are removed from the conveyor  30 , the conveyor will again begin to fill with accumulated pads as is indicated in FIG.  4 A. 
     Referring now to FIGS. 6 and 7 there is shown an alternate embodiment of a cushioning conversion system  80  including a reversible conveyor system  16 ′ with a cushioning conversion machine  10  and an associated pad-transferring assembly  12  located at either end of the conveyor system for producing pads and transferring them to the conveyor system for conveyance to an operator. The conveyor system  16 ′ is similar to the conveyor system  16  described above with the exception that the conveyor  30  is reversible and that each of the stop gate assemblies  34  includes a pair of sensors  54 ′ and  54 ″ associated therewith. In this embodiment, one machine  10  operates or is active at a time with the conveyor  30  of the conveyor system  16 ′ moving in a direction to convey the pads  14  produced by the active machine in a direction away from that machine. Control of the individual stop gate assemblies  34  is then in accordance with the control signal generated by the sensor  54 ′ located downstream from the stop gate assembly relative to the direction of conveyance of the conveyor  30 . For example, when the cushioning conversion machine  10  shown on the left side of FIG. 6 is active and the conveyor  30  is conveying pads away from the machine in the direction of arrow  82  as shown in FIG. 7, or to the right, the stop gate assembly  34  will be controlled in accordance with the control signals generated by the sensors  54 ′. Alternatively, when the machine  10  shown on the right side of FIG. 6 is active and the conveyor  30  is conveying pads away from the machine in the direction of arrow  84  shown in FIG. 7, or to the left, the stop gate assembly  34  would be controlled in accordance with the control signals generated by the sensor  54 ″. The operation of the conveyor system  16 ′ would then be basically as described above relatively to FIGS. 4A-4D. In this manner, if one of the cushioning conversion machines  10  becomes damaged, jammed or must be deactivated for maintenance or for the resupply of paper, then the other machine will be activated and will produce the required pads, and the conveyor  30  will be reversed accordingly. Reversal of the conveyor  30  and selection of the active cushioning conversion machine  10  may be automated or manual as desired in a particular application. 
     While the cushioning conversion system and conveyor system have been described relative to a number of specific embodiments, it will be readily apparent that the present invention has a wide range of applications in many types or configurations of cushioning conversion machines and conveyors.