Patent Publication Number: US-9427928-B2

Title: Method and machine for producing packaging cushioning

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to packaging materials and, more specifically, to a machine and method for producing packaging cushioning from sheets of a selected substrate, such as paper. 
     Machines for producing packaging cushioning from paper are well-known in the art. Such machines generally operate by pulling a web of paper from a roll, manipulating the paper web in such a way as to convert the paper into packaging cushioning, and then severing the cushioning into cut sections of a desired length. 
     While such machines are widely used and have been commercially successful, in many applications, there is a need for improved functionality. For example, paper rolls tend to be quite heavy and cumbersome to lift and load onto cushion conversion machines. Although the volume of cushioning that can be produced from a roll of paper tends to off-set the weight disadvantage for high-volume packaging operations, for lower-volume packaging operations, a lighter, easier-to-handle alternative would be preferred. 
     Moreover, while severing mechanisms in roll-fed machines provide a workable means for producing cushions of a desired length, such mechanisms present ongoing safety concerns, in both the design and operation of such machines. As such, it would be desirable to be able to produce packaging cushions of a desired length without the need for a severing or perforation mechanism. 
     While individual sheets of paper can be used to make cushioning, no means is known for connecting the sheets in such a way that packaging cushions having any desired length can be produced. 
     Finally, in many packaging applications, it is necessary to vary the density of the packaging cushions to suit the weight or nature of the objects being packaged. Currently, this can only be accomplished by adding additional paper rolls or changing rolls to paper of a different weight. In both cases, the machine must be shut down and the new roll(s) must be threaded into the machine. It would be desirable to change the cushion-density without having to make such changes. 
     Accordingly, there is a need in the art for a machine and method for producing packaging cushioning that is capable of fulfilling the foregoing performance requirements. 
     SUMMARY OF THE INVENTION 
     That need is met by the present invention, which, in one aspect, provides a method for producing packaging cushioning, comprising: 
     a. successively feeding sheets of a substrate at a first speed to a crumpling mechanism; 
     b. crumpling the sheets in the crumpling mechanism, the crumpling mechanism crumpling the sheets at a second speed to convert the sheets into packaging cushion units; and 
     c. controlling at least one of the first and second speeds to produce a desired degree of overlap between successive sheets, thereby generating a connected series of the packaging cushion units, wherein the connected series of packaging cushion units has a density that is proportional to the degree of overlap between successive sheets. 
     In accordance with another aspect of the invention, a machine is provided for producing packaging cushioning, comprising: 
     a. a feed mechanism for successively feeding sheets of a substrate at a first speed; 
     b. a crumpling mechanism for receiving the sheets from the feed mechanism and crumpling the sheets at a second speed to convert the sheets into packaging cushion units; and 
     c. a controller for controlling at least one of the first and second speeds to produce a desired degree of overlap between successive sheets, thereby generating a connected series of the packaging cushion units, wherein the connected series of packaging cushion units has a density that is proportional to the degree of overlap between successive sheets. 
     By employing individual sheets of a packaging substrate, e.g., paper, the machine and method of the present invention avoids the need to lift and load heavy rolls of the substrate onto the machine. The use of individual sheets also avoids the need for a severing or perforation mechanism, as is generally the case when the substrate is supplied from a roll. At the same time, the machine and method of the present invention allow packaging cushion units made from the sheets to be connected in such a way that packaging cushions having any desired length can be produced. Moreover, the density of the packaging cushions may be varied as desired to suit the various weights, shapes, and sizes of the objects being packaged. Significantly, such density variation may be accomplished on a real-time/on-demand basis and without the need to add additional paper rolls and/or change rolls to paper of a different weight. 
     These and other aspects and features of the invention may be better understood with reference to the following description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic view of a machine for producing packaging cushioning in accordance with the present invention; 
         FIGS. 2-6  are similar to  FIG. 1 , and show the machine in various stages of packaging cushion production; 
         FIG. 7  is a plan view of an alternative machine in accordance with the present invention; 
         FIG. 8  is a perspective view of the machine shown in  FIG. 7 , along lines  8 - 8 ; 
         FIGS. 9A and 9B  are similar to  FIG. 7 , and show the illustrated machine in two different stages of packaging cushion production; 
         FIG. 10  is a plan view of a connected string of packaging cushion units as produced in  FIG. 9B ; 
         FIG. 11  a cross-sectional view of the string of packaging cushion units shown in  FIG. 10 , taken along lines  11 - 11 ; and 
         FIG. 12  is similar to  FIG. 10 , except one of the packaging cushion units is separated from the connected string of packaging cushion units. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  schematically illustrates a machine  10  in accordance with the present invention for producing packaging cushioning. Machine  10  comprises a feed mechanism  12 , a crumpling mechanism  14 , and a controller  16 . 
     As shown in  FIGS. 2-6 , feed mechanism  12  successively feeds sheets  18  of a substrate at a first speed, which is represented by arrow  20  ( FIG. 2 ). 
     Crumpling mechanism  14  receives the sheets  18  from the feed mechanism  12 , and crumples the sheets at a second speed, which is represented by arrow  22  ( FIG. 3 ). The crumpling of the sheets  18  is effected in such a manner that the sheets are converted into packaging cushion units  24 . 
     Controller  16  controls at least one of the first and second speeds  20 ,  22  to produce a desired degree of overlap  26  between successive sheets  18  ( FIG. 3 ). Such overlap  26 , in combination with the crumpling in crumpling mechanism  14 , generates a connected series  28  of packaging cushion units  24  ( FIGS. 4-6 ). In accordance with the present invention, the connected series  28  of packaging cushion units  24  has a density that is proportional to the degree of overlap  26  between successive sheets  18 . 
     Sheets  18  may comprise any type of material desired for use in packaging cushions, including paper, e.g., kraft paper, fiberboard, thermoplastic film, etc., including recycled forms of the foregoing materials, as well as combinations thereof, e.g., laminated paper, coated paper, composite paper, etc. The sheets may have any desired shape, e.g., square, rectangular, etc., with any desired dimensions, e.g., a 20 inch length dimension and a 15 inch width dimension. 
     Sheets  18  may be arranged for supply to machine  10  in any convenient form, e.g., as a stack  30  as shown, or in shingled, random, or individual form, etc., as desired. When sheets  18  are arranged as a stacked supply  30  as shown, machine  10  may further include a supply tray  32 , which is configured and dimensioned for holding the sheets in a stacked arrangement of desired height, i.e., to accommodate a desired maximum number of sheets  18  in stack  30 . When such an embodiment is employed, feed mechanism  12  may be disposed and configured for feeding the sheets  18  from supply tray  32  to crumpling mechanism  14 . As such, the feed mechanism  12  may comprise a first feed roller  34  to advance the sheets  18  from the supply  30  thereof, and a second feed roller  36  to receive the sheets from the first feed roller  34  and feed the sheets into crumpling mechanism  14 . 
     The first feed roller  34  may be associated with a motor, schematically designated as motor “M 3 ” in the drawings, to drive the rotation of the feed roller. The feed roller  34  may be in a fixed position relative to tray  32 , with the tray including a movable tray base  38 , e.g., pivotally movable as shown, which may be biased towards feed roller  34 , e.g., via spring  40 . In this manner, as the stacked supply  30  of sheets  18  depletes, the sheets are continuously urged against the feed roller  34  so that the feed roller can continue to advance the sheets sequentially from the stack. 
       FIGS. 2-6  illustrate tray  32  with a relatively full stack  30 , such that spring  40  is fully compressed and tray base  38  is substantially aligned with the bottom  42  of tray  32 . The pivot point for tray base  38 , e.g., hinge  41  as shown, may be placed at any desired location along the bottom  42  of tray  32 , e.g., opposite from spring  40  as shown or, e.g., closer to spring  40  such that the movable tray base  38  is shorter than as shown. 
     Instead of, or in addition to, a movable tray base  38 , the first feed roller  34  may be movably biased towards the stack  30 . 
     First feed roller  34  may be accompanied by as many additional feed rollers as necessary to advance the sheets  18 . For example, two or more feed rollers  34  may be arrayed across the width of the sheets  18 , e.g., as shown in  FIG. 8  (wherein first feed roller  34  is shown as a pair  34   a, b  of such feed rollers). 
     As shown in the illustrated embodiment, the second feed roller  36  is positioned to receive the sheets  18  from first feed roller  34 , e.g., via guide member  44 , and then feed the sheets into the crumpling mechanism  14 . The second feed roller  36  may be associated with a motor, schematically designated as motor “M 1 ” in the drawings, to drive the rotation of the feed roller. As an alternative to the illustrated embodiment in which separate motors M 3  and M 1  are employed to drive the rotation of the first and second feed rollers  34  and  36 , respectively, a single motor (not shown) may be employed to drive the rotation of both the first and second feed rollers  34  and  36 , e.g., via appropriate linkage, which may include drive belt(s), drive chain(s), drive axel(s), etc. 
     Second feed roller  36  may be accompanied by as many additional feed rollers as necessary to advance the sheets  18 . For example, two or more feed rollers  36  may be arrayed across the width of the sheets  18 , e.g., as shown in  FIG. 8  (wherein second feed roller  36  is shown as a pair  36   a, b  of feed rollers). 
     A backing member  46  may be included, to provide a support against which second feed roller  36  rotates, to thereby facilitate the feeding of sheets  18  into crumpling mechanism  14 . Backing member  46  may be a static member, which provides frictional resistance to the rotation of roller  36  such that the sheets  18  are compressed between the roller  36  and backing member  46  while passing therebetween, with the sheets making sliding contact with the member  46 . Alternatively, backing member  46  may be a rotational member, which rotates passively via rotational contact with the driven roller  36 . As a further alternative, the relative position of the second feed roller  36  and backing member  46  may be switched such that the driven roller  36  is beneath the backing member  46 . This orientation may be particularly convenient when a single motor is employed to power the rotation of both the first and second feed rollers. 
     As may be appreciated, feed mechanism  12  generally defines a path of travel along which the sheets  18  move between the supply  30  of the sheets and the crumpling mechanism  14 . As mentioned briefly above, the feed mechanism  12  may further include guide member  44 , which may be included to facilitate the movement of the sheets along the travel path, e.g., by directing the movement of the sheets from the first feed roller  34  to the second feed roller  36 . 
     The guide member  44  may be structured and arranged to change the movement of the sheets  18  on the travel path, e.g., from a first direction  48 , in which the sheets are fed from supply/stack  30 , to a second direction  50 , in which the sheets are crumpled ( FIG. 2 ). Advantageously, this allows the machine  10  to have a compact configuration or ‘footprint,’ e.g., in which the supply tray  32  with sheet supply  30  is positioned beneath crumpling mechanism  14  as shown. 
     In the presently illustrated embodiment, the crumpling mechanism  14 , second feed roller  36 , backing member  46 , and motors M 1 , M 2  may be contained within a housing  54  (shown in phantom). The first direction  48  may be substantially parallel to and substantially opposite from the second direction  50  (see,  FIG. 2 ), such that the housing  54  may be positioned substantially directly above the supply tray  32 , e.g., in a stacked configuration as shown. Guide member  44  may thus define an arcuate path of travel for sheets  18  as shown, e.g., with approximately 180 degrees of curvature. With such a structure, secondary or inner guide member  45  may also be included, and may have a complementary position on the inside of the arcuate path defined by guide member  44  as shown. 
     In the above-described embodiment, the second feed roller  36  receives the sheets  18  indirectly from the first feed roller  34 , e.g., via guide member  44 . Alternatively, the feed mechanism  12  may define a more linear path of travel for the sheets  18 , in which the sheets are advanced from supply  30  in substantially the same direction as they are crumpled in crumpling mechanism  14 . This may be accomplished, e.g., by positioning the supply tray  32  beside, rather than beneath, housing  54 . In such embodiment, the second feed rollers may receive the sheets  18  substantially directly from the first feed roller  34 , i.e., with no intervening guide member  44 . More generally, supply tray  32  and housing  54  may have any desired relative orientation. For example, the tray  32  and housing  54  may be positioned at 90 degrees to one another, e.g., with the housing  54  having a substantially horizontal orientation and the tray  32  having a substantially vertical orientation. 
     Feed rollers  34 ,  36  may comprise any material suitable for conveying sheets  18 , such as metal (e.g., aluminum, steel, etc.), rubber, elastomer (e.g., RTV silicone), urethane, etc., including combinations of the foregoing materials. As an alternative to wheel-type rollers as shown, one or both feed rollers  34 ,  36  may comprise one or more counter-rotating drive belts, drive bands, etc. As a further alternative to feed rollers  34 ,  36 , or in addition thereto, feed mechanism  12  may convey the sheets  18  via any suitable sheet-handling means, including pneumatic conveyance, electrostatic conveyance, vacuum conveyance, etc. 
     Crumpling mechanism  14  may comprise a pair of compression members  52   a  and  52   b  that convert the sheets  18  into packaging cushion units  24  by compressing the sheets therebetween. The compression members  52   a, b  may comprise a pair of counter-rotating wheels, belts, etc., or, as shown, a pair of counter-rotating gears, which may have radially-extending teeth  56  that mesh together to effect the crumpling of the sheets  18 , e.g., as illustrated in  FIGS. 3-6 . The teeth  56  are preferably sized and shaped to convey and crumple the sheets  18  without tearing the sheets. The compression members  52   a, b  and teeth  56  may be formed of any material capable of conveying and crumpling the sheets  18 , and preferably with sufficient toughness to withstand wear but without causing damage to the sheets  18 . Many suitable materials exist. Examples include polymeric materials such as ultra-high molecular weight polyethylene (UHMWPE), polyimide, fluorocarbon resins such as polytetrafluoroethylene (PTFE) and perfluoropropylene, acetal resins, i.e., resins based on polyoxymethylene, including homopolymers (e.g., Delrin® brand polyoxymethylene), copolymers, and filled/impregnated grades, such as PTFE-filled acetal resins; various metals such as aluminum, steel, etc.; metals with low-COF coatings, e.g., anodized aluminum or nickel impregnated with low-COF polymers such as PTFE or other fluorocarbon resins; and mixtures or combinations of the foregoing. 
     In accordance with the present invention, the compression members  52   a, b  connect the packaging cushion units  24  together by crumpling the sheets  18  at the overlap  26  between successive sheets. That is, the inventors found that the action of crumpling two overlapped sheets together has the effect of joining the sheets together at the overlapped portions of the sheets. By controlling the first speed  20  relative to the second speed  22 , the overlap  26  can have any desired degree. Preferably, the overlap  26  is only a partial overlap such that a chain of the sheets  18 , as converted into packaging cushion units  24 , may be connected together, i.e., to form connected series  28 . 
       FIGS. 2-6  illustrate a sequence of events that lead to the conversion of sheets  18  into packaging cushion units  24 , and to their being connected together to form a connected series  28  of the packaging cushion units  24 . 
       FIG. 2  illustrates the beginning of the production process, in which first feed roller  34  of feed mechanism  12  engages the upper-most sheet  18   a  in stack  30 , and rotates in the direction of the indicated arrow to move the sheet in first direction  48 . Sheet  18   a  immediately encounters guide member  44 , which causes it to change course to second direction  50 , thereby leading the sheet  18   a  into the nip between second feed roller  36  and backing member  46 . Motor M 1  is powering the rotation of the second feed roller  36 , as indicated by the rotational arrows associated with the feed roller  36  and backing member  46 , such that sheet  18   a  is fed towards crumpling mechanism  14  at first speed  20 . The magnitude of first speed  20  is determined by the output of motor Ml. Motors M 1  and M 3  may be synchronized such that the speed at which the sheets  18  are advanced from supply  30  is the same as the speed  20  at which the sheets are fed to the crumpling mechanism  14 . As noted above, this may be accomplished by employing only one motor in place of the separate motors M 1  and M 3 , and transmitting the rotational output of such motor to both the first and second feed rollers  34 ,  36 . Alternatively, by operating the first and second feed rollers  34 ,  36  at different speeds, compressive or tensional forces may be imparted on the sheets  18  prior to their conveyance to the crumpling mechanism  14 . 
     The feeding of the sheets  18  by the feed mechanism  12  may be facilitated by including a second guide member, which may include upper and lower guide plates  58   a, b . As shown, guide plates  58   a, b  may be positioned between second feed roller  36  and crumpling mechanism  14 , and arranged to form a passage  60  therebetween to guide the movement of the sheets  18  as they are fed by the second feed roller  36  and into the crumpling mechanism  14 . 
     In  FIG. 3 , a second sheet  18   b  has been withdrawn from supply stack  30  by first feed roller  34 , transferred to second feed roller  36 , and is being fed through passage  60  towards crumpling mechanism  14  by the second feed roller  36  at first speed  20 . At the same time, the first sheet  18   a  has reached crumpling mechanism  14  and is being crumpled and conveyed thereby at second speed  22 . Second speed  22  results from the rotational speed at which the compression members  52   a, b  counter-rotate against one another, as indicated by the rotational arrows. The rotational speed of the compression members  52   a, b , in turn, is determined by the output of motor M 2 . 
     In accordance with the present invention, at least one of the first and second speeds  20 ,  22  are controlled to produce a desired degree of overlap  26  between successive sheets  18 , thereby generating the connected series  28  of packaging cushion units  24 . As shown in  FIG. 3 , the overlap  26  is produced between the trailing end  62  of sheet  18   a  and the leading end  64  of sheet  18   b . Such overlap may result from a speed differential between first speed  20  and second speed  22 . 
     For example, the crumpling mechanism  14  and second feed roller  36  may be operated such that second speed  22  is slower than first speed  20 . In this manner, when sheet  18   a  is released from feed mechanism  12  and engaged only by crumpling mechanism  14 , it will be moving at the slower second speed  22 . Conversely, while the next sheet  18   b  is engaged only by the feed mechanism  12 , i.e., prior to the leading end  64  thereof reaching the crumpling mechanism  14 , it (sheet  18   b ) moves at the relatively higher first speed  20 . As a result, the leading end  64  of sheet  18   b  overtakes and slides over or under the trailing end  62  of sheet  18   a , to form overlap  26  as shown. The degree of the overlap  26  will continue to increase until the leading end  64  of sheet  18   b  reaches the crumpling mechanism  14  and/or sheet  18   b  is released from feed mechanism  12 . 
     That is, as shown in  FIG. 4 , once the leading end  64  of sheet  18   b  becomes engaged by the crumpling mechanism  14 , the speed at which the sheet  18   b  moves through machine  10  will decrease from first speed  20  to second speed  22 . At that point, with both sheets  18   a, b  moving at the same speed, i.e., speed  22 , and both sheets being engaged by crumpling mechanism  14 , no further relative movement of sheets  18   a, b  will occur, such that no further increase in the overlap  26  will occur. Thus, as shown, the overlapped section  26  of successive sheets  18   a  and  18   b  are crumpled together in crumpling mechanism  14 , which has the effect of joining the trailing end  62  of sheet  18   a  to the leading end  64  of the following sheet  18   b . This, in turn, results in the connection of the packaging cushion unit  24   a , as formed by the crumpled sheet  18   a , to the next packaging cushion unit  24   b , which is being formed in  FIG. 4  from sheet  18   b  as it is crumpled in crumpling mechanism  14 . 
     In  FIG. 5 , the connection process between packaging cushion units  24   a  and  24   b  is complete in that the overlap  26  between the respective successive sheets  18   a  and  18   b  has moved through and past crumpling mechanism  14 . The remainder of sheet  18   b  is being crumpled to complete its conversion into packaging cushion unit  24   b . The resultant series  28  of connected packaging cushion units is being conveyed out of machine  10 , e.g., via outlet  66  in housing  54 . If desired, a receptacle, e.g., a storage bin or the like (not shown), may be employed for containment of the connected series  28  of packaging cushion units  24  until such cushion units are needed for use. In such case, the outlet  66  may be configured to guide the connected series  28  directly into the receptacle. 
     Also in  FIG. 5 , first feed roller  34  of feed mechanism  12  engages the next sheet  18   c  in stack  30 , and advances it towards second feed roller  36  via guide member  44 . The sheet  18   c  then moves through the nip between second feed roller  36  and backing member  46  at first speed  20  towards the preceding sheet  18   b , which is moving at a slower second speed  22  as a result of its engagement by crumpling mechanism  14 . The speed differential between speeds  20  and  22  will result in leading end  64  of sheet  18   c  overtaking the trailing end  62  of the preceding sheet  18   b  to form another overlap  26  (shown in  FIG. 6 ), as described above relative to  FIG. 3 . 
     In  FIG. 6 , an overlap  26  has formed between the leading end  64  of sheet  18   c  and the trailing end  62  of the preceding sheet  18   b . Such overlap  26  is being crumpled together in crumpling mechanism  14 , which has the effect of joining the trailing end  62  of sheet  18   b  to the leading end  64  of the following sheet  18   c . This, in turn, results in the connection of the packaging cushion unit  24   b , as formed by the crumpled sheet  18   b , to the next packaging cushion unit  24   c , which is being formed from sheet  18   c  as it is crumpled in crumpling mechanism  14 . 
     As also shown in  FIG. 6 , as the supply  30  of sheets  18  in tray  32  depletes, spring  40  extends, and thereby causes the tray base  38  to pivot upwards to maintain the uppermost sheet in the supply stack in contact with first feed roller  34 . 
     The foregoing process may continue for as long as desired, e.g., until supply  30  of sheets  18  in tray  32  is depleted, in order to add as many additional packaging cushion units  24  as desired to the connected series  28 . 
     First speed  20  and/or second speed  22  may be controlled by controlling the rotational speed of the second feed roller  36  and/or that of the crumpling mechanism  14 , respectively. Controller  16  may thus be in electrical communication with motor M 1  and/or M 2 . Thus, for example, the speed at which motor M 2  drives the rotation of the compression members  52   a, b  may be fixed, while controller  16  may be operably linked to motor M 1  to cause the motor to provide a range of controllable output speeds which, in turn, produce a range of rotational speeds for second feed roller  36 . Alternatively, the speed of motor M 1  may be fixed while motor M 2  is a variable speed motor, the speed of which is controlled by controller  16 . As a further alternative, both motors M 1  and M 2  may be variable-speed motors, and both may be operably linked to controller  16 , e.g., via control wires  68  and  70  as shown, so that the speed of one or both of motors M 1 , M 2  may be controlled. 
     Controller  16  may be an electronic controller, such as a printed circuit assembly containing a micro controller unit (MCU), which stores pre-programmed operating codes; a programmable logic controller (PLC); a personal computer (PC); or other such control device which allows the speed of motors M 1  and/or M 2  to be controlled via local control, e.g., via an operator interface; remote control; pre-programmed control, etc. 
     Controller  16  may control the operation of motor M 1  and/or M 2 , thereby controlling at least one of the first and second speeds  20 ,  22 , automatically, manually, or via a combination of both automatic and manual control. In some embodiments, controller  16  may be configured to receive input from an operator, i.e., from an operator interface such as a foot pedal, hand switch, control panel, etc., including combinations of the foregoing. An operator may thus be able to select a desired degree of overlap between successive sheets, as well as the number of packaging cushion units to be connected in a given series of such units. 
     Thus, for example, controller  16  may include, or be electronically associated with, an operator input device, e.g., a switch or the like (not shown), which allows the operator to select a desired degree of overlap between successive sheets. A two-position switch, for example, could allow an operator to choose between a ‘low-density’ mode of operation and a ‘high-density’ mode of operation. 
     In the ‘low-density’ mode, controller  16  would command machine  10  to connect packaging cushion units  24  together with a minimum degree of overlap, e.g., just enough to form a connection, such as between about 1 and about 3 inches of overlap between successive sheets. The advantage of the low-density mode is that a minimal amount of sheets  18  are used for a given length of connected packaging cushion units  24 , thus providing an economical mode of operation as would be appropriate, e.g., for lighter weight objects to be packaged. As an example, for sheets  18  having a length of 20 inches and a width of 17 inches, such low-density/minimal overlap mode was achieved when machine  10  was configured as alternative machine  10 ′ as shown in  FIGS. 7-9 , and was operated at a first speed  20  of about 40 inches/second and a second speed  22  of about 26 inches/second, or a first speed  20 /second speed  22  ratio of about 1.5. Such speed ratio of about 1.5 resulted in an overlap  26  of about 2 inches. 
     In the ‘high-density’ mode, controller  16  would command machine  10  to connect packaging cushion units  24  together with a greater degree of overlap, e.g., between about 4 and about 6 inches of overlap between successive sheets. Although a greater number of sheets  18  are used to produce a given length of connected packaging cushion units  24 , i.e., as compared with the low-density mode, an increase in the density of the packaging cushions often becomes necessary when the packaging application changes, e.g., to properly protect higher-weight objects that need to be packaged. As an example, for sheets  18  having a length of 20 inches and a width of 17 inches, such high-density/higher overlap mode was achieved when machine  10  was configured as alternative machine  10 ′ as shown in  FIGS. 7-9 , and was operated at a first speed  20  of about 28 inches/second and a second speed  22  of about 12 inches/second, resulting in a speed differential of about 16 inches/minute. Such speed differential of 16 inches/minute resulted in an overlap  26  of about 5 inches. Stated differently, the speed ratio between first speed  20  (28 inches/second) and second speed  22  (12 inches/minute) in this example was about 2.33. 
     An alternative control scheme is to enable the operator to select any desired differential or ratio between first speed  20  and second speed  22 , between pre-set minimum and maximum amounts. For example, a potentiometer that adjusts the speed ratio between first speed  20  and second speed  22  may be employed, wherein a setting of “0” (zero) corresponds to the minimum allowed differential between speeds  20  and  22  (minimum allowed overlap between successive sheets/minimum density), and “10” (ten) corresponds to the maximum allowed differential between such speeds (maximum allowed overlap/maximum density). Another alternative would be to have a multitude of preset density conditions, which the operator can select by switching between predetermined ratio settings using a multi-position switch. 
     As a further alternative, controller  16  may be configured to allow an operator to set the operating speeds of motor M 1  and/or M 2  manually, e.g., as the sole means of control. In such embodiment, controller  16  may be a simple device containing, for example, a multi-position switch or dial to control the speed of motor M 1 /second feed roller  36  and/or a second switch or dial to control the speed of motor M 2 /compression members  52   a, b.    
     As may be appreciated, the ability to easily change the density of the connected series  28  of packaging cushion units  24  as needed, i.e., without having to change to a different type/weight of sheet, or add sheets from a different source, in order to suit the changing needs of differing packaging applications is a distinct advantage of the present invention. 
     The controller  16  may further include or be associated with a dial or the like, which allows an operator to select a desired number of packaging cushion units to be produced upon a further command from the operator, such as the actuation of a foot pedal or hand switch (not shown) in electrical communication with the controller. Such actuation by the operator will then result in machine  10  commencing operation and continuing to operate until the selected number of packaging cushion units are produced. 
     In one mode of operation, controller  16  may be programmed by specifying, via appropriate input command, the diameter of both the first and second feed rollers  34 ,  36 , as well as the length of the sheets  18 . When controller  16  is operably linked to motor M 1  as described above (i.e., via control wire  68 ), and also to motor M 3  (control wire not shown; M 1  and M 3  may be the same motor) the speed of motors M 1  and M 3  may be controlled by controller  16 . Based on the operational run-time and rotational-speed commands that the controller has given to each of the feed rollers  34 ,  36 , coupled with any necessary feed-back to verify that such commands have been carried out, the controller  16  will “know”, through simple calculations, the approximate number of sheets  18  that have been fed by the first feed roller  34  and by the second feed roller  36 . In this manner, controller  16  can maintain an approximate count of the number of packaging cushion units produced each time that an operator commands the machine to run, e.g., so that the controller  16  can automatically command the machine to stop when the requested number of cushion units has been produced. Other means for counting the number of cushion units produced, which will generally be more precise but also more costly, are also possible, e.g., photo-eyes, motor encoders, etc. Such devices may be employed to provide feed-back to controller  16  regarding the number of sheets and/or cushion units that have passed a given point in machine  10 . 
     Controller  16  may include or be associated with a further operator input device, e.g., a switch or the like, which allows the operator to select an ‘eject’ mode, wherein machine  10  ejects the resultant string of packaging cushion units, e.g., into a bin or other receptacle, or a ‘hold’ mode, wherein machine  10  holds the last packaging cushion unit produced in a string of cushions in the outlet  66  for manual removal by the operator. 
     For example, with reference to  FIG. 6 , if the operator selects a string of about three (3) packaging cushion units  24  to be produced, and also selects the ‘eject’ mode, controller  16  will command motor M 3  and then M 1  to discontinue operations once it (the controller  16 ) determines that sheets  18   a - c  have passed through the first and second feed rollers  34 ,  36 . In this case, the resultant series  28  of three (3) connected packaging cushion units would be ejected out of machine  10  via conveyance by crumpling mechanism  14 , which the controller  16  will command to continue to operate for a predetermined time (based on speed  22  and the pre-programmed length of sheets  18 ) after second feed roller  36  ceases to operate. 
     Using the same example, if the operator selects the ‘hold’ mode, an additional sheet, e.g., a fourth sheet  18   d  (not shown), will be connected to sheet  18   c  (or to the last sheet to be included in the series) via an overlap  26  (also not shown), and the controller  16  will command all motors M 1 -M 3  to stop once that overlap has cleared the compression members  52   a, b , such that the resultant series  28  of about three (3) connected packaging cushion units is extending from outlet  66 , connected to a partially formed cushion unit formed by the next sheet (e.g.,  18   d ), which is held in the machine by the compression members  52   a, b . To remove such connected series  28 , the operator simply pulls cushion unit  24   c  to release it from the overlapped connection  26  with the partially-formed cushion unit formed from the next sheet (e.g.,  18   d ). 
     An alternative means for achieving a speed differential between the speed at which the sheets are crumpled vs. the speed at which the sheets are fed, in order to achieve a desired degree of overlap, may be effected by varying the relative positioning of the crumpling mechanism  14  vs. the feed mechanism  12  during the movement of the sheets. This may be accomplished by effecting relative translational movement of the crumpling and/or feed mechanisms  14 ,  12  during transport of the sheets  18 , wherein the timing and magnitude of such translational movement is controlled to achieve a desired degree of overlap between successive sheets. With reference to  FIG. 3 , for example, overlap  26  can be provided by the relative movement of crumpling mechanism  14  towards second feed roller  36  such that the leading end  64  of sheet  18   b  overtakes and overlaps the trailing  62  of preceding sheet  18   a . The entire crumpling mechanism  14 , for example, could be placed on a track, rail, or other means of guided translational movement, and moved towards second feed roller  36  via an appropriate actuator, e.g., a piston, to produce the overlap  26 . When the overlap  26  reaches and becomes engaged by the compression members  52   a, b , the crumpling mechanism  14  can then be returned to its starting position, i.e., translated away from second feed roller  36 , and thus in position for a subsequent overlap-causing movement. 
     Accordingly, relative to a fixed point on machine  10 , the second speed (at which the sheets are crumpled) may be controlled via translational movement of crumpling mechanism  14  to achieve a desired degree of overlap between successive sheets. Similarly, control of the first speed could be achieved by effecting translational movement of the feed mechanism  12  relative to the crumpling mechanism  14 . 
     As illustrated in the drawings, crumpling mechanism  14  receives sheets  18  indirectly from feed mechanism  12 , i.e., via guide plates  58   a, b , which are interposed between the feed mechanism  12  and the crumpling mechanism  14 . Alternatively, such guide plates  58   a, b  may be omitted such that the crumpling mechanism  14  receives the sheets directly from the feed mechanism  12 . 
     As a further alternative, a machine in accordance with the present invention may include a convergence device in place of guide plates  58   a, b . As shown in  FIGS. 7-9 , in alternative machine  10 ′, at least part of convergence device  72  may be positioned between feed mechanism  12  and crumpling mechanism  14  for reducing the width dimension of the sheets  18 . As shown, convergence device  72  may be in the form of a chute, with a relatively wide entrance portion  74  and a relatively narrow exit portion  76 . Second feed roller  36  may be in the form of a pair of such feed rollers  36   a, b , which may be positioned at or near the entrance portion  74  of convergence device  72 , and driven by motor M 1  via a common drive axle  78 . With this arrangement, the feed mechanism  12  feeds the sheets  18  into crumpling mechanism  14  by pushing the sheets through the convergence device  72  and then into the crumpling mechanism  14 . 
     Exit portion  76  may be positioned adjacent the crumpling mechanism  14 , such that sheets  18  exiting the convergence device  72  are directed into the crumpling mechanism. A guide channel  80  may extend from convergence device  72  as shown, to contain and direct the sheets  18  as they are crumpled in mechanism  14 . In alternative machine  10 ′, crumpling mechanism  14  may thus be positioned within the guide channel  80 , and may be driven by motor M 2  via drive axle  82 . 
     As perhaps best shown in  FIG. 8 , convergence device  72  may include opposing side walls  88   a, b , which converge in a direction leading from the entrance portion  74  to the exit portion  76 , i.e., along second direction  50 . Side walls  88   a, b  may be included as necessary to facilitate the convergence of sheets  18  by helping to contain and direct the sheets as their width is reduced. 
     As also shown in  FIG. 8 , first feed roller  34  may comprise a pair of rollers  34   a, b , which may be driven by motor M 3  via common drive axle  84 . A pair of springs  40 , indicated as springs  40   a, b  in  FIG. 8 , may be included to bias tray base  38  towards the feed rollers  34   a, b . Tray base  38  may be pivotally attached to the bottom  42  of tray  32  via multiple hinges  41   a - c.    
       FIG. 9A  is essentially a plan view of  FIG. 2 , in that sheet  18   a  is being fed from stack  30  and into crumpling mechanism  14  at first speed  20 . In  FIG. 9A , however, machine  10 ′ includes convergence device  72 , instead of guide plates  58   a, b , through which sheet  18   a  is being conveyed en route to crumpling mechanism  14 . 
     As may be appreciated, sheets  18  generally have a length dimension and a width dimension, each of which may be the same or different among the various sheets in stack  30 . With respect to sheet  18   a  for example, the width dimension “W 1 ” thereof is shown in  FIG. 9A ; the length dimension “L” of the sheets is shown in  FIG. 2 . The sheets  18  generally also have a pair of opposed lateral sides  86   a, b  ( FIG. 9A ). 
     Accordingly, when alternative machine  10 ′ is employed, i.e., with convergence device  72 , a method in accordance with the present invention may further include the step of reducing the width dimension of the sheets. As shown in  FIG. 9A , such width reduction step may occur prior to the crumpling step in crumpling mechanism  14 , and may be effected by directing the sheets  18  through convergence device  72 . Thus, as the sheets  18  move from the entrance portion  74  to the exit portion  76  along second direction  50 , the convergence device  72  causes the lateral sides  86   a, b  to converge towards one another. 
     For example, as shown in  FIG. 9A , the initial width W 1  of sheet  18   a  may be slightly less than that of the entrance portion  74  of convergence device  72  so that the sheet can be fed into the device  72 . As the sheet moves along second direction  50 , the lateral sides  86   a, b  of the sheet come in contact with the convergent side walls  88   a, b . Such convergent contact between the lateral sides  86   a, b  and the side walls  88   a, b  causes the lateral sides  86   a, b  of the sheet to converge towards one another as shown. As a result, upon reaching the exit portion  76  of the convergence device  72 , and then traveling through the guide channel  80 , the width of the sheet is reduced from width W 1  to width W 2 . 
     The side walls  88   a, b  may be curved as shown in  FIG. 8 , or may have any other shape, e.g., square or rectangular, that facilitates the convergence of the lateral sides  86   a, b . The convergence device  72  may include a bottom surface  90  as shown, and may also include a top surface (not shown), e.g., similar to upper guide plate  58   a  as shown in  FIGS. 1-6  with respect to machine  10 . As shown in  FIGS. 7-8 , cut-outs  91  in bottom surface  90  may be provided for second feed rollers  36   a, b  and backing members  46 . Alternatively, both the backing members  46  and cut-outs  91  may be omitted as shown in  FIGS. 9A-B , wherein feed rollers  36   a, b  drive the sheets  18  against the bottom surface  90  of convergence device  72 . 
       FIG. 9B  is essentially a plan view of  FIG. 5 , except that convergence device  72  is used instead of guide plates  58   a, b . Thus, similar to  FIG. 5 , in  FIG. 9B  the connection process between packaging cushion units  24   a ′ and  24   b ′, from respective successive sheets  18   a  and  18   b , is complete, with the overlap  26   a  between sheets  18   a, b  having moved through and past crumpling mechanism  14 . The remainder of sheet  18   b  is being crumpled to complete its conversion into packaging cushion unit  24   b ′. The next successive sheet  18   c  is being fed by feed mechanism  12  at first speed  20  towards the preceding sheet  18   b , which is moving at a slower second speed  22  as a result of its engagement by crumpling mechanism  14 . The speed differential between speeds  20  and  22  will result in leading end  64  of sheet  18   c  overtaking the trailing end  62  of the preceding sheet  18   b  to form another overlap  26 , e.g., as shown in  FIG. 6 . 
     It may be appreciated that the shape and characteristics of packaging cushion units  24 ′, as produced by machine  10 ′, are different than those of packaging cushion units  24 , as produced by machine  10 , in that, prior to crumpling, the convergence device  72  of machine  10 ′ reduces the width dimension W 1  of sheets  18 , such that the width of the resultant packaging cushion units  24  is W 2 . Generally, the convergence device  72  may be configured to effect any desired width reduction in sheets  18 . The ratio of W 1 :W 2  may be, for example, within the range of 10:1 to 1:1, e.g., between about 9:1 to about 2:1, such as between about 8:1 to about 3:1, 7:1 to 4:1, etc. 
     In the present embodiment, convergence device  72  reduces such width by causing the lateral sides  86   a, b  to converge. For example, the convergence of the lateral sides  86   a, b  may be such that the lateral sides overlap one another and form the sheets  18  into a tube  93  as shown, e.g., with only lateral side  86   a  being visible. As shown, sheet  18   b  has been formed into a tube  93 , and the width thereof is being reduced as it travels towards the exit portion  76  of convergence device  72 . Sheet  18   c  is in the process of being formed into a tube. The differential between its speed  20  and that of sheet  18   b  (i.e., slower speed  22 ) will result in leading end  64  of the tube being formed from sheet  18   c  overtaking the trailing end  62  of the tube  93  formed from preceding sheet  18   b , which will form another overlap of the tubes, i.e., as at  26  in  FIG. 9B . 
     In the illustrated embodiment, the final width of the packaging cushion units  24  is shown to be essentially the same as that of the outlet  66  of housing  54 , i.e., W 2 . It should be understood, however, that this is not necessarily the case. For example, the internal structure of housing  54  can be arranged such that the final width of the packaging cushion units  24  is less than the width of the outlet  66 , e.g., as would be the case if the exit portion  76  of convergence device  72  is narrower than outlet  66 . 
     Regardless of the manner in which the lateral sides  86   a, b  are converged in device  72 , as shown in  FIG. 9B , the crumpling mechanism  14  crimps the converged lateral sides, e.g., as the tube  93  passes through the crumpling mechanism. This has the effect of causing the resultant packaging cushion unit  24 ′ to maintain a substantially tubular, i.e., longitudinally-rolled, form. 
     Referring now to  FIGS. 10-11 , the packaging cushion units  24 ′ will be described in further detail.  FIGS. 10-11  show a connected series  28 ′ of packaging cushion units  24 ′, comprising packaging cushion units  24 ′ a - c , as made from machine  10 ′. A greater or less number of packaging cushion units may be included in any given connected series of such cushions. Each packaging cushion unit  24 ′ comprises a pair of end regions  92  bounding a central region  94 . As shown, the end regions  92  correspond to the overlap  26  between successive sheets  18 . As indicated collectively in  FIGS. 9B through 11 , crumpling mechanism  14  crimps the overlapped end regions  92  of adjacent packaging cushion units  24 ′ together. This has the effect of connecting the packaging cushion units  24 ′ to thereby form the connected series  28 ′. Thus, in the illustration set forth in  FIGS. 10-11 , packaging cushion units  24   a ′ and  24   b ′ are connected at overlap  26   a , while packaging cushion units  24   b ′ and  24   c ′ are connected at overlap  26   b.    
     When machine  10 ′ is employed, the overlapped end regions  26 / 92  may be formed by inserting the leading end  64  of a sheet  18 , which is being formed into a tube  93 , into the trailing end  62  of the preceding sheet that has already been formed into a tube  93 . For example, as shown in  FIG. 9B , sheet  18   c  is being formed into a tube, with the leading end  64  having a cone shape as a result of the converging side walls  88   a, b  of convergence device  72 . As the sheet  18   c  moves towards the preceding sheet  18   b  at speed  20 , the cone-shaped leading end  64  will be inserted into the trailing end  62  of the tube-shaped sheet  18   b , which is moving at the slower speed  22 . 
     Thus, the crumpling mechanism  14  as employed in machine  10 ′ crimps both of the following: 
     1) the converged lateral sides  86   a, b , which has the effect of causing the resultant packaging cushion unit  24 ′ to maintain a substantially tubular, i.e., longitudinally-rolled, shape; and 
     2) the overlapped end regions  26 / 92  of adjacent packaging cushion units  24 ′, which has the effect of connecting the packaging cushion units  24 ′ together as a series  28 ′. 
     Regardless of whether machine  10  or  10 ′ is employed, the connected series  28 / 28 ′ of packaging cushion units  24 / 24 ′ will generally have a density that is proportional to the degree of overlap  26  between successive sheets  18 . Thus, the higher the degree of the overlap  26 , the higher will be the average density of the connected series  28 / 28 ′ of packaging cushion units. With a higher degree of overlap, more sheets  18  will be present per unit volume of the connected series  28 / 28 ′ than when the degree of overlap is less. 
     The degree of overlap  26  is proportional to the speed differential between the first and second speeds  20 ,  22 . Thus, the degree of overlap  26 , and therefore the density of the connected series  28 / 28 ′ of packaging cushion units  24 / 24 ′, may be controlled by controlling such speed differential. 
     Generally, the degree of overlap between any two successive sheets  18  may range from greater than 0% to less than 100%, e.g., between about 1% and about 75% overlap, between about 2% and about 50% overlap, or between about 3% and about 40% overlap, etc. For example, sheets  18  having a width “W 1 ” of 17 inches and a length “L” of 20 inches were formed on machine  10 ′ into a connected series  28 ′ of packaging cushion units  24 ′ with an overlap of about 25%, i.e., with about 5 inches of overlap between successive sheets  18 , by employing a first speed  20  of about 28 inches/second and a second speed  22  of about 12 inches/second, resulting in a speed differential of about 16 inches/minute or, stated differently, a speed ratio (first speed:second speed) of 2.33:1. The initial width W 1  of the sheets  18  (17 inches) was reduced to a final width W 2  in the resultant packaging cushion units of 3-3.5 inches, for a W 1 :W 2  ratio of about 5:1. The density of the resultant series  28 ′ of packaging cushion units  24 ′ was about 1.4 lbs/ft 3 . 
     When a similar series  28 ′ of connected packaging cushion units  24 ′ was formed with an overlap  26  of 2 inches, i.e., a lower degree of overlap than 5 inches as in the previous example, the resultant density of the connected series  28 ′ was also lower—namely, about 1.2 lbs/ft 3 . In this example, the first speed  20  was about 40 inches/second and the second speed  22  was about 26 inches/second. 
     Referring now to  FIG. 12 , a further beneficial feature of the invention will be described. Namely, in accordance with some embodiments of the invention, the packaging cushion units may be connected such that each packaging cushion unit  24 / 24 ′ is slidingly separable from an adjacent packaging cushion unit  24 / 24 ′. As shown in  FIG. 12 , packaging cushion unit  24   c ′ is being slidingly separated from connected series  28 ′. More specifically, packaging cushion unit  24   c ′ is being slidingly separated from adjacent packaging cushion unit  24   b ′ in the direction of arrows  96 . This may be accomplished by connecting the cushion units  24   b ′ and  24   c ′ in such a way that the overlapped end regions  92  at which the two cushion units are connected, i.e., at overlap  26   b  in  FIGS. 10-11 , are releasable. Such releasable connection may, for example, be effected via a friction fit, which is produced by the crumpling of sheets  18  at the overlap  26  between successive sheets. 
     A friction fit between adjacent packaging cushion units may be achieved via the use of the crumpling mechanism  14  as described above, i.e. comprising counter-rotating compression members  52   a, b , each of which have cooperative teeth  56  that intermesh together. The intermeshing teeth  56  may be shaped and arranged to crimp the sheets  18  so as to form an alternating series of convex impressions  98  and concave impressions  100  in packaging cushion units  24 ′, e.g., ‘peaks’  98  and ‘valleys’  100 , as perhaps best shown in  FIG. 11 . The width of the compression members  52   a, b  may be substantially equal to the final width W 2  of the packaging cushion units  24 ′ so that the peaks and valleys  98 ,  100  extend transversely across substantially the entire width W 2  of the units  24 ′. Alternatively, as shown in  FIGS. 9A / 9 B, the width of the compression members  52   a, b  may be less than width W 2 , so that the peaks and valleys  98 ,  100  extend transversely across only a part of the width W 2  of the packaging cushion units  24 ′, e.g., across a center region  102  ( FIG. 12 ), leaving longitudinally-extending outer regions  104  substantially without impressions  98 ,  100 . 
     In the overlap areas  26 , the peaks and valleys  98 ,  100  of the crimped end regions  92  of adjacent packaging cushion units  24 ′ serve to connect the units  24 ′ together with a friction fit, which also permits the units  24 ′ to be slidingly separated from one another, e.g., as shown in  FIG. 12 . In addition to the degree of overlap  26 , the coefficient of friction of sheets  18 , etc., the depth of the peaks and valleys  98 ,  100  will determine the strength of the connection between adjacent packaging cushion units  24 / 24 ′. The depth of the peaks and valleys  98 ,  100 , is based, at least in part, on the extent of intermeshing of the teeth  56  of counter-rotating compression members  52   a, b . Thus, in addition to the selection of the degree of overlap  26  and the type of sheets  18 , the depth of the peaks and valleys  98 ,  100  may be established to provide a desired amount of connection strength between adjacent packaging cushion units, so that any two units may be disconnected from one another upon the application of a desired amount of tensional force, e.g., manual force, as exerted, e.g., in the direction of arrows  96  in  FIG. 12 . 
     Advantageously, in accordance with the present invention, packaging cushions of any desired size, e.g., comprising a desired number of connected packaging cushion units  24 / 24 ′, may be created by separating two of the packaging cushion units from one another to thereby remove a packaging cushion from the connected series  28 / 28 ′ of packaging cushion units. With reference to  FIG. 12 , for example, a packaging cushion  106  may comprise connected packaging cushion units  24   a ′ and  24   b ′. As may be appreciated, the density of packaging cushion  106  varies along its length dimension (parallel to arrows  96 ), with the density being higher in the overlap area  26   a  (at which the cushion units are connected) than in the remaining parts of the cushion  106 . This is advantageous in packaging applications in which an object to be packaged has a relatively heavy or protruding portion; the higher density part  26  of the packaging cushion can be placed in contact with such heavy or protruding portion to provide extra support thereto. 
     The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention.