Abstract:
An interfolding apparatus including first and second interfolding rolls. The first interfolding roll is supplied sheets of web product and the second interfolding roll is supplied additional sheets of web product. The interfolding rolls rotate to form a first number of folds in the sheets and rotate to form the first number of folds in some of the additional sheets and a second, different number of folds in at least one other of the additional sheets. The interfolding rolls rotate to interfold the sheets with the additional sheets having the first number of folds to form a stack of interfolded web product and rotate to interfold at least one of the sheets with at least one of the additional sheets having the second number of folds to form a discontinuity in the stack.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to apparatuses and methods for interfolding sheets of web product to create a stack of interfolded sheets and to form a separation or discontinuity between the sheets of the stack.  
       BACKGROUND OF THE INVENTION  
       [0002]     A typical interfolding apparatus has two rotating interfolding rolls that issue a stream of interfolded web material. In operation, separate streams of web material are delivered to individual cutting rolls where the web material is cut into sheets. The sheets then move downward to corresponding interfolding rolls that are positioned to form a nip. The interfolding rolls rotate in opposite directions and receive the newly-cut sheets of web material from the cutting rolls.  
         [0003]     The sheets are usually staggered with respect to the first and second interfolding rolls so that a middle portion of a first sheet of one roll passes through the nip at approximately the same time as leading and trailing edges of sheets of the opposite roll. At this time, vacuum or mechanical grippers of the first roll attract and retain the center of the first sheet and the leading and trailing edges of the opposing sheets to begin a fold in the first sheet and to capture the leading and trailing edges within the fold.  
         [0004]     As the gripper rotates with the sheet, a packer finger pushes the middle portion along with the leading and trailing edges from the gripper to a position where the fold can be pressed with the leading and trailing edges of the opposing sheets being folded within the middle portion. This process continues alternately with the other interfolding roll to form an interfolded stack of material.  
         [0005]     A specific number of sheets are typically counted for packaging purposes. Elements commonly referred to as count fingers and package building fingers can be used to separate a stack with a desired number of sheets. The count fingers are inserted sequentially from opposite sides into the stack of interfolded web material to create a clip below the count fingers having a known quantity of items. The inserted count fingers separate from each other to separate the interfolded sheets of the adjacent stacks.  
       SUMMARY  
       [0006]     One embodiment of the present invention provides an interfolding apparatus including first and second interfolding rolls. The first interfolding roll is supplied sheets of web product and the second interfolding roll is supplied additional sheets of web product. The interfolding rolls rotate to form a first number of folds in the sheets and rotate to form the first number of folds in some of the additional sheets and a second, different number of folds in at least one other of the additional sheets. The interfolding rolls rotate to interfold the sheets with the additional sheets having the first number of folds to form a stack of interfolded web product and rotate to interfold at least one of the sheets with at least one of the additional sheets having the second number of folds to form a discontinuity in the stack.  
         [0007]     Another embodiment of the present invention provides an interfolding apparatus including a first interfolding roll supplied sheets of web product having a first length, and a second, adjacent interfolding roll supplied additional sheets of web product. Some of the additional sheets have the first length and at least one other of the additional sheets has a second, different length. The interfolding rolls rotate to interfold the sheets with the additional sheets having the first length to form a stack of interfolded web product, and the interfolding rolls are rotatable to interfold the sheets with at least one of the additional sheets having the second length to form a discontinuity in the stack.  
         [0008]     In yet another embodiment, the present invention provides a method of interfolding sheets of web product. The method includes providing an interfolding apparatus including a first interfolding roll and a second interfolding roll adjacent to the first interfolding roll, supplying sheets of web product having a first length to the first interfolding roll, supplying some additional sheets of web product having the first length to the second interfolding roll, and supplying at least one other of the additional sheets of web product having a second, different length to the second interfolding roll, interfolding the sheets with the additional sheets having the first length, forming a stack of interfolded web product, interfolding the sheets with at least one of the additional sheets having the second length, and forming a discontinuity in the stack.  
         [0009]     Other embodiments of the present invention include a method of interfolding sheets of web product. The method includes providing an interfolding apparatus including a first interfolding roll and a second interfolding roll adjacent to the first interfolding roll, supplying sheets of web product to the first interfolding roll, supplying additional sheets of web product to the second interfolding roll, forming a first number of folds in the sheets, forming the first number of folds in some of the additional sheets, forming a second, different number of folds in at least one other of the additional sheets, interfolding the sheets with the additional sheets having the first number of folds, forming a stack of interfolded web product, interfolding at least one of the sheets with at least one of the additional sheets having the second number of folds, and forming a discontinuity in the stack.  
         [0010]     Independent features and independent advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     In the drawings, wherein like reference numerals indicate like parts:  
         [0012]      FIG. 1  is a side view of the interfolding apparatus of the present invention; and  
         [0013]      FIG. 2  is an enlarged side view of the stack of interfolded web product shown in  FIG. 1 . 
     
    
       [0014]     Before at least one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other constructions and of being practiced or of being carried out in various ways.  
         [0015]     Also, it is to be understood that the phraseology and terminology used herein with reference to element orientation are only used to simplify description of the present invention, and do not alone indicate or imply that the element referred to must have a particular orientation. In addition, terms such as “first” and “second” are used herein for purposes of description and are not intended to indicate or imply relative importance or significance.  
       DETAILED DESCRIPTION  
       [0016]      FIG. 1  illustrates an interfolding apparatus  10  operable to manipulate two streams of web material  12 A,  12 B in downstream directions to create stacks of interfolded web product. The downstream direction is identified by arrows  14 A,  14 B. The interfolding apparatus  10  includes a first set of rotatable guide rolls  16 A, a first cutting assembly  18 A located downstream of the first set of guide rolls  16 A, and a first rotatable interfolding roll  20 A located downstream of the first cutting assembly  18 A. The interfolding apparatus  10  also includes a second set of rotatable guide rolls  16 B, a second cutting assembly  18 B located downstream of the second set of guide rolls  16 B, and a second rotatable interfolding roll  20 B located downstream of the second cutting assembly  18 B.  
         [0017]     The guide rolls  16 A are positioned adjacent each other and define a nip  22 A. The first guide rolls  16 A are rotatable in opposite directions. The second set of guide rolls  16 B is substantially similar to the first set of guide rolls  16 A. The guide rolls  16 A,  16 B can be passive rolls used to direct and guide the web  12 A,  12 B, or can be active powered rolls that additionally pull the web, positively feeding it in the downstream direction to the cutting assemblies  18 A,  18 B.  
         [0018]     The first cutting assembly  18 A includes a rotatable cutting roll  24 A and an anvil bar  26 A. The cutting roll  24 A rotates counter-clockwise and includes eight knife stations  28 A about its periphery. Each knife station  28 A includes a blade  30 A selectively adjustable between retracted and extended positions relative to an axis  32 A of the cutting roll  24 A. The blade  30 A can be actuated using an electronically-actuated solenoid, electric motor, servo-motor, air bladder, air cylinder, cams, linkages or the like. When in the extended position, the extended blade  30 A will contact the anvil bar  26 A during rotation of the cutting roll  24 A. In contrast, the blade  30 A will not contact the anvil bar  26 A during rotation of the cutting roll  24 A when in the retracted position. A more detailed explanation of a similar adjustable cutting blade system is provided in U.S. Pat. No.6,296,601, which is assigned to the same assignee as the present application. The entire contents of this patent is incorporated by reference into this application.  
         [0019]     The cutting roll  24 A also includes two vacuum passageways  34 A,  36 A associated with each knife station  28 A. Specifically, a first, or downstream vacuum passageway  34 A is located downstream of the blade  30 A and a second, or upstream vacuum passageway  36 A is located upstream of the blade  30 A. Vacuum pressure can be selectively applied to each of the vacuum passageways through a pump and valve system (not shown). The second cutting assembly  18 B is a substantial mirror image of the first cutting assembly  18 A except that the cutting roll  24 B of the second cutting assembly  18 B rotates about an axis  32 B in a clockwise direction.  
         [0020]     Although both rolls  24 A,  24 B are described and illustrated as including actuable blades  30 A,  30 B, other configurations can also be used with the present invention. For example, one of the two cutting rolls  24 A,  24 B could include all non-actuable, or fixed blades. Also, the cutting rolls  24 A,  24 B could each include any combination of fixed and actuable blades located about the periphery of the cutting roll  24 A,  24 B. In addition, although eight knife stations  28 A,  28 B are shown on each roll  24 A,  24 B of the illustrated embodiment, it is within the scope of the present invention to instead use more or less knife stations  28 A,  28 B on each cutting roll  24 A,  24 B.  
         [0021]     The first interfolding roll  20 A rotates clockwise and is positioned adjacent to the first cutting roll  24 A to define a nip  38 A. The first interfolding roll  20 A includes a plurality of vacuum port sets. Each set of vacuum ports includes a first, leading port  40 A and a second, trailing port  42 A. Vacuum pressure can be selectively applied to each of the vacuum ports  40 A,  42 A through a pump and valve system (not shown). The second interfolding roll  20 B is substantially similar to the first interfolding roll  20 A except that the second interfolding roll  20 B rotates counter-clockwise and is positioned adjacent to the second cutting roll  24 B to define a nip  38 B. In other embodiments, the vacuum ports  40 A,  40 B,  42 A,  42 B on the interfolding rolls can be replaced by a mechanical gripper and tucker system.  
         [0022]      FIG. 1  illustrates the operation of the interfolding apparatus  10  to build continuous interfolded stacks S 1 , S 2 . The first guide rolls  16 A receive the web product  12 A from a parent roll (not shown) positioned and unwound upstream of the interfolding apparatus  10 . The first guide rolls  16 A rotate to guide and direct the web product  12 A through the nip  22 A toward the first cutting assembly  18 A.  
         [0023]     The first cutting roll  24 A rotates counter-clockwise and includes four blades  30 A extended and four blades  30 A retracted in an alternating configuration. Therefore, assuming the blades  30 A are numbered consecutively, blades one, three, five, and seven are extended and blades two, four, six, and eight are retracted. As the web  12 A is delivered to the periphery of the cutting roll  24 A, the web  12 A is gripped by the vacuum provided through the vacuum passageways  34 A,  36 A such that the web  12 A is rotated and carried with the cutting roll  24 A. As the cutting roll  24 A continues to rotate with the web  12 A, the extended blades  30 A will contact the anvil bar  26 A thereby creating a clean cut across the web  12 A that is positioned between the blade  30 A and the anvil bar  26 A. The cut defines a trailing edge of a sheet immediately downstream of the cut, and defines a leading edge of the web product  12 A immediately upstream of the cut. The downstream vacuum passageway  34 A continues to hold the trailing edge of the downstream sheet, and the upstream vacuum passageway  36 A continues to hold the leading edge of the web  12 A.  
         [0024]     As the next consecutive retracted blade  30 A rotates passed the anvil bar  26 A, the retracted blade  30 A will not contact the anvil bar  26 A and therefore will not cut the web  12 A positioned between the retracted blade  30 A and the anvil bar  26 A. Although the blade  30 A is retracted, the vacuum passageways  34 A,  36 A in the knife station  28 A hold the web  12 A as it rotates passed the anvil bar  26 A. Rotation of the cutting roll  24 A can continuously create sheets downstream of the anvil bar  26 A. The sheets have a first length equal to the distance between two consecutive extended blades  30 A along the periphery of the cutting roll  24 A.  
         [0025]     Next, the cut sheets are transferred in the nip  38 A from the cutting roll  24 A to the first interfolding roll  20 A. As the sheet is moved through the nip  38 A, the downstream vacuum passageway  34 A releases the leading edge of the sheet and vacuum is applied to the trailing port  42 A of the interfolding roll  20 A to attract and hold the leading edge of the sheet onto the interfolding roll  24 A. As the cutting and interfolding rolls  24 A,  20 A continue to rotate the sheet through the nip  38 A, the vacuum passageways  34 A,  36 A adjacent to the next consecutive retracted blade  30 A release the sheet, and vacuum is applied to the next set of vacuum ports  40 A,  42 A on the interfolding roll  20 A to attract and hold the center portion of the sheet on the interfolding roll  20 A. The trailing edge of the sheet is then rotated into the nip  38 A where the upstream vacuum passageway  36 A adjacent to the next consecutive extended blade  30 A releases the trailing edge of the sheet, and vacuum is applied to the leading port  40 A of the next set of vacuum ports  40 A,  42 A on the interfolding roll  24 A, completing the transfer of the sheet onto the interfolding roll  20 A. Rotation of the cutting roll  24 A and the interfolding roll  20 A continuously transfers sheets from the cutting roll  24 A to the interfolding roll  20 A.  
         [0026]     The process described above with respect to the first guide rolls  16 A, first cutting assembly  18 A, and first interfolding roll  20 A also applies to the operation of the second guide rolls  16 B, second cutting assembly  18 B, and second interfolding rolls  20 B except that the second guide rolls  16 B are fed web  12 B that is separate from the web  12 A fed to the first guide rolls  16 A.  
         [0027]     After the sheets are transferred to the cutting rolls  24 A,  24 B, the sheets move into the nip  44  between the two interfolding rolls  20 A,  20 B. The sheets are staggered with respect to the nip  44  so that a middle portion of a first sheet of one interfolding roll passes through the nip  44  at approximately the same time as leading and trailing edges of upstream and downstream sheets of the opposite interfolding roll. At this time, the vacuum port of the first interfolding roll attracts and retains the center of the first sheet and the leading and trailing edges of the opposing sheets to begin a fold in the first sheet and to capture the leading and trailing edges within the fold.  
         [0028]     As the first interfolding roll  20 A rotates with the sheet, a packer finger (not shown) pushes the middle portion along with the leading and trailing edges from the vacuum port to a position where the fold can be pressed with the leading and trailing edges of the opposing sheets being folded within the middle portion. As understood by those skilled in the art, this process continues alternately with the second interfolding roll  20 B to form continuous stacks SI, S 2  of interfolded sheets. Each sheet in the stacks SI, S 2  includes a single fold  46  and two panels  48 . One panel  48  is located upstream of the fold  46  (and is folded within the sheet above) and the other panel  48  is located downstream of the fold  46  (and is folded within the sheet below). In the illustrated embodiment, the length of one panel  48  is approximately equal to the distance between consecutive blades  30 A,  30 B (regardless of retracted or extended position) on the cutting roll  24 A,  24 B. Accordingly, the sheets extending between two extended blades  30 A,  30 B of the above-described configuration can be called two-panel sheets  50  after they are passed through the interfolding rolls  20 A,  20 B.  
         [0029]     Some embodiments of the present invention create a separated stack S 1  not interfolded with an adjacent stack S 2 . The interfolding apparatus  10  of the present invention creates a discontinuity, or a non-interfolded position  52  separating a completed interfolded stack SI below the non-interfolded position  52  and a new interfolded stack S 2  being built above the non-interfolded position  52 .  
         [0030]     When a discontinuity is desired to complete a stack SI and to allow the completed stack SI to be non-interfolded with the adjacent stack S 2 , the sheet length created by the first cutting roll  24 A is modified by adjusting the blades  30 A on the first cutting roll  24 A. In the illustrated embodiment, the original configuration, extending blades one, three, five, and seven, is changed such that only blades one, four, and seven are extended providing two retracted blades  30 A between extended blades one and four, and two retracted blades  30 A between extended blades four and seven. Rotation of the cutting roll  24 A in this configuration will cut two sheets having a second length equal to the distance between the two consecutive extended blades  30 A along the periphery of the cutting roll  24 A. The second length is 1.5 times the length of the first length. After the second sheet is cut, the blade configuration is again adjusted to return to the original blade arrangement, which operates to cut sheets having the first length.  
         [0031]     The sheets having the second length are transferred from the cutting roll  24 A to the interfolding roll  20 A to be passed through the nip  44  of the interfolding rolls  20 A,  20 B. The sheets having the second length are then interfolded with the sheets having the first length that continue to be supplied by the second interfolding roll  20 B. The sheets having the second length form three-panel sheets  54  and the sheets having the first length continue to form two-panel sheets  50 .  
         [0032]     As shown in  FIG. 2 , interfolding the two sheets  54  having the second length with the continuous stream of sheets  50  having the first length results in a discontinuity or a non-interfolded position  52  separating a completed interfolded stack SI below the non-interfolded position  52  and a new interfolded stack S 2  being built above the non- interfolded position  52 . In some embodiments, a single count finger can be inserted into the non-interfolded position  52  and the movement and separation of the completed stack Si is simplified.  
         [0033]     On the right side of the stacks S  1 , S 2 , the sheets are consistently single-fold, two-panel sheets  50 . On the left side, the two-fold, three-panel sheets  54  are interfolded and create the non-interfolded position  52  between them. In the illustrated embodiment, the first three-panel sheet  54  is used to align trailing edges of sheets from the first and second interfolding rolls  20 A,  20 B separating the stacks SI and S 2 . This alignment creates the non-interfolded position  52 . The second three-panel sheet  52  is used to offset the sheets on opposing interfolding rolls  20 A,  20 B to allow the necessary overlap causing the creation of a new interfolded, continuous interfolded stack S 2  of sheets  
         [0034]     Various features of the invention are found in the following claims.