Patent Publication Number: US-7219890-B2

Title: Valve system for the count roll of an interfolding machine

Description:
RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 60/508,580, filed Oct. 3, 2003, the entirety of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to an interfolding machine for folding sheets of material, and more specifically, to an interfolding machine that includes a count roll to form a separation in a stack of interfolded sheets at a predetermined sheet. 
     BACKGROUND OF THE INVENTION 
     Interfolding of a web or sheet material (e.g., napkins, paper towels, tissue, etc.) is frequently performed using folding rolls of a folding machine. The folding rolls are operable to fold a series of successive sheets that are cut from one or more webs and supplied to the folding rolls in an overlapping relationship. Upstream of the folding rolls, the sheets are cut against a bed roll by a knife roll, and the sheets are then supplied to a retard roll that functions to provide the desired overlapping relationship of the sheets. From the retard roll, the sheets are advanced by a lap roll and are then supplied to the folding rolls for interfolding, to create a stack of interfolded sheets at the discharge of the folding rolls. A count roll is located adjacent the lap roll, and rotates in a timed relationship with the lap roll. The count roll is selectively operable to eliminate the sheet overlap at a desired sheet count, in order to create a separation in the supply of overlapped sheets to the folding rolls. The separation in the supply of sheets to the folding rolls functions to separate the stack of sheets discharged from the folding rolls into adjacent stacks or logs of sheets, each of which has a desired sheet count. The sheet overlap is interrupted by means of a vacuum system in the count roll that folds the leading edge of one of the sheets onto itself at the desired count. As the count roll rotates, the vacuum system is selectively actuated to engage the leading edge of the sheet as the sheets is transported on the lap roll, and carries and/or retains the leading edge of the sheet while the remainder of the sheet is advanced by the lap roll. The count roll then releases the leading edge of the sheet, and the retention of the remainder of the sheet on the count roll creates the sheet fold that eliminates the overlap between the leading edge of the sheet and the trailing edge of the downstream sheet. 
     However, known count roll systems for interfolding machines have drawbacks and limitations. For example, the operational speed of the interfolding machine is limited by a relatively short switching time that is available for actuating the vacuum system to turn the count roll valves on and off. Further, known count rolls use two vacuum ports on the count roll that are 180° apart, which can only provide an even count of sheets. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a count assembly that provides the ability to form a separation of successive sheets of material through an interfolding machine at a desired sheet count. The count assembly includes a count roll that is selectively supplied with vacuum from a vacuum assembly, which includes a manifold having a plurality of manifold ports coupled to a valve body having a plurality of interior chambers. A spool is located within a cavity defined by the valve body. The spool includes a plurality of spool ports to provide a plurality of respective vacuum paths to a rotating count roll. The spool also includes a plurality of machined openings along a perimeter or outer surface, and each machined opening in the spool communicates a respective manifold port with a respective interior chamber disposed in the valve body. 
     The invention also provides an interfolding machine for interfolding sheets of material, which are separated at a predetermined count of sheets. The interfolding machine includes a roll configured to count successive sheets of the material through the interfolding machine. The roll generally includes a series of holes or ports configured to communicate vacuum to the surface of the roll at a predetermined sheet count and at a desired point in rotation of the roll. The interfolding machine further includes a vacuum assembly that selectively communicates vacuum pressure to the holes or ports of the roll. The vacuum assembly includes a manifold having a series of manifold ports, and a valve body having a series of chambers, each of which is in communication with one of the series of manifold ports. The vacuum assembly further includes a spool inserted in the valve body. The spool is connected to the roll so as to rotate with the roll, and includes a plurality of spool ports along a circumference thereof to provide respective paths to communicate the vacuum pressure to the holes or ports of the folding roll. Each opening in the spool communicates one of the manifold openings with one of the chambers of the valve body. The vacuum assembly further includes a control valve for selectively exposing at least one of the valve chambers to atmosphere such that the roll selectively releases the web material at a predetermined point in rotation of the roll. 
     The invention also provides a method of separating successive sheets of overlapped sheets of material at a desired sheet count. The method generally includes the acts of providing a control valve, a spool, and a count roll, the count roll configured to create a fold separating the successive sheets of web material at a desired sheet count. The spool includes a plurality of chambers, each of which is configured to communicate a vacuum pressure at a plurality of ports along a perimeter of the spool with a plurality of holes in an outer surface of the count roll. The method further includes the acts of rotating the spool with respect to the control valve; aligning one or more of the chambers in the spool with an opening in the control valve; communicating one or more of the aligned chambers with atmosphere via the opening in the control valve; and releasing the vacuum pressure in one or more of the aligned chambers to atmosphere. 
     Other objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout. In the drawings: 
         FIG. 1  is an isometric view of an interfolding machine employing a count roll valve system in accordance with the present invention. 
         FIG. 2  is a schematic side elevation view of the interfolding machine as shown in  FIG. 1 . 
         FIG. 3  is a detailed isometric view of a count roll valve assembly incorporated in the interfolding machine of  FIGS. 1 and 2 . 
         FIG. 4  is a first detailed cross-sectional view of the count roll valve assembly along line  4 — 4  of  FIG. 3 . 
         FIG. 5  is a second detailed cross-sectional view of the count roll valve assembly along line  5 — 5  of  FIG. 3 . 
         FIG. 6  is a cross-sectional view of the count roll valve assembly along line  6 — 6  of  FIG. 4 . 
         FIG. 7  is an exploded isometric view of the count roll valve assembly shown in  FIG. 3 . 
         FIG. 8  is a schematic diagram of showing the count roll assembly of  FIGS. 3–7  engaging a leading edge of a sheet of material from a lap roll assembly, at a desired sheet count. 
         FIG. 9  is a schematic diagram similar to  FIG. 8  completing a fold in of the sheet of material to form a separation in the sheets supplied to the folding rolls. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     1. Folding Machine 
     Referring to  FIGS. 1 and 2 , an interfolding machine  25  is operable to convert a web of material  30  into a stack of interfolded sheets of material shown at  32 . Interfolding machine  25  incorporates a count roll valve system in accordance with the present invention, and generally includes a first pull roll  35  and a second pull roll  40  that receive the web of material  30  along a path (illustrated by an arrow  42  in  FIG. 2 ) from a supply roll (not shown) into the interfolding machine  20 . The first and second pull rolls  35  and  40  define a nip through which the web of material  30  passes, and function to unwind the web of material  30  and feed the web of material  30  in a path (illustrated by an arrow  44  in  FIG. 2 ) toward a nip defined between second pull roll  40  and a bed roll  45 . The web of material  30  is then advanced by bed roll  45  toward a knife roll  50 . In a manner as is known, the knife roll  50  cuts the web of material  30  into sheets, each of which has a predetermined length, and the bed roll  45  carries the sheets of material along a path (illustrated by arrow  52  in  FIG. 2 ) toward and through a nip defined between bed roll  45  and a retard roll  55 , which rotates at a slower speed of rotation than the bed roll  45 . In a manner as explained in copending application Ser. No. 10/953,175 filed Sep. 24, 2004, the retard roll  55  cooperates with a nip roller assembly  60  ( FIG. 2 ) to form an overlap between the consecutive sheets of material. The retard roll  55  carries the overlapped sheets of material along a path (illustrated by arrow  68  in  FIG. 2 ) to a lap roll  65 . 
     The lap roll  65  works in combination with the count roll  20  to eliminate the overlap between adjacent sheets of material at a predetermined sheet count, so as to create a separation in the stack  32  of interfolded sheets discharged from the interfolding machine  25 . The lap roll  65  carries the overlapped sheets  30  along a path (illustrated by arrow  78  in  FIG. 2 ) toward a nip defined between a first assist roll  80  and an adjacent second assist roll  85 . The first and second assist rolls  80  and  85  feed the sheets of the material to a nip defined between a first folding roll  90  and a second folding roll  95 . 
     Referring to  FIG. 2 , the first and second folding rolls  90  and  95  generally rotate in opposite directions (illustrated by arrows  96  and  98 , respectively, in  FIG. 2 ) to receive the overlapped sheets of material  30  therebetween. The periphery of the first folding roll  90  generally includes a series of the tucker assemblies  105  and gripper assemblies  100  uniformly and alternately spaced to interact with a series of tucker assemblies  105  and gripper assemblies  100  of the adjacent second folding roll  95 . The series of alternately spaced tucker assemblies  105  and gripper assemblies  100  of the first and second folding rolls  90  and  95  interact to grip, carry, and release the sheets of material in a desired manner so as to form stack  32  of interfolded sheets. The folding rolls  90  and  95  may be driven by a drive system  110  having a drive belt assembly  115  ( FIG. 1 ). 
     The stack  32  of interfolded sheets is discharged from between the first and second folding rolls  90  and  95  in a generally vertically-aligned fashion. The stack  32  of interfolded sheets may be supplied to a discharge and transfer system (not shown), which guides and conveys the stack  32  from the generally vertically-aligned orientation at the discharge of the interfolding machine  25  to a generally horizontally-aligned movement. One embodiment of a suitable discharge and transfer system is described in U.S. Pat. No. 6,712,746 entitled “Discharge and Transfer System for Interfolded Sheets,” filed May 5, 2000, the disclosure of which is hereby incorporated herein by reference in its entirety. Another representative discharge and transfer system is illustrated in copending application Ser. No. 10/610,458 filed Jun. 30, 2003, now U.S. Pat. No. 6,865,861 issue Mar. 15, 2005, the disclosure of which is also hereby incorporated herein by reference in its entirety. 
     2. Count Roll Assembly 
       FIGS. 3–7  show a count roll valve assembly  130  of the present invention, which is mounted to each end of count roll  20 . Count roll  20  is rotatably mounted to the frame of interfolding machine  25  by a pair of bearing box assemblies  132 . Each count roll valve assembly  130  generally includes a pair of ball bearings  135 , a rotating spool  140 , a valve body  145 , a pair of wear plates  150 , an OFF valve  155 , and a manifold cover  160 . 
     The rotating spool  140  of the count valve assembly  130  slips over a roll journal  170 , such that roll journal  170  is received within an internal passage  142  defined by spool  140 . Each roll journal  170  includes a flange  176  that is directly connected one of the ends of count roll  20 , in a manner as is known. Flange  176  defines port paths  185  that are aligned and communicate with port paths  185  that open onto the ends of count roll  20 . Port paths  185  of flange  176  communicate with separate interior chambers or passages  200   a–d  formed in the body of spool  140 . 
     The rotating spool  140  also includes radially and axially spaced machined openings or ports  210   a–d  that open onto the outer surface  212  of the body of spool  140 . Each opening  210   a–d  communicates with one of the separate interior chamber  200   a–d  disposed in the spool  140 , establishing communication with the outer surface of spool  140 . Each chamber  200   a – 200   d  connects one of the distinct openings  210   a–d  to one of the respective port paths  185   a–d  and to the respective holes  218   a–d  along the outer surface of the count roll  20 . 
     The valve body  145  does not rotate, and is supported on spool  140  by bearings  135 , which are affixed to the ends of spool  140  and within inwardly facing recesses formed in the ends of valve body  145 . Wear plates  150  straddle the outer one of bearings  135  at the bearing box  132 /frame side  222  (See  FIG. 1 ) of the assembly  20 . Valve body  145  is a generally cylindrical member, and includes a series of circumferential recesses  148   a,    148   b,    148   c  and  148   d  that extend inwardly from its outer surface. Valve body  145  defines an interior  149  within which spool  140  is received, and recesses  148   a – 148   d  communicate with valve body interior  149  through respective passages  151   a – 151   d  (FIGS.  4 , 5 ). 
     Manifold  160  generally includes a series of four C-shaped cover components  160   a–d  interconnected with a series of four C-shaped vacuum inlet components  165   a–d.  The width of each of the cover components  160   a–d  and respective vacuum inlet components  165   a–d  can vary. The preferred cover components  160   a–d  each extends a first portion of the circumference of the manifold  160 , and each of the vacuum inlet components  165   a–d  extends the remaining circumference of the manifold  160 . The manifold  160  further includes a series of gaskets  230  disposed between adjacent cover components  160   a–d  and vacuum inlet components  165   a–d.  Respective cover components  160   a – 160   d  and respective vacuum inlet components  165   a – 165   d  are secured together to enclose respective valve body recesses  148   a – 148   d.  With this construction, manifold  160  defines a series of annular vacuum supply cavities, each of which is supplied with vacuum from a vacuum source connected to vacuum inlet components  165   a – 165   d,  and which communicate with valve body interior through passages  151   a – 151   d.  Of course, the specific construction of manifold  160  may vary form that which is shown and described, which is not limiting on the invention. 
     The OFF valve  155  is generally a port cover plate structure that overlies the end of the spool  140  opposite plate portion  144 . OFF valve  155  is spring-loaded, stationary and presses against the outer wear plate  150 . In the illustrated embodiment, OFF valve  155  generally includes a U-shaped opening  225  through which roll journal  170  extends. Opening  225  in OFF valve  155  selectively communicates chambers or passages  200   a–d  with atmosphere during rotation of count valve  20  and spool  140 . When the energized or activated port passes the U-shaped cutout in valve  155 , the respective port is exposed to the atmosphere, which functions to cut off the supply of vacuum pressure to the holes  218   a–d  of the count roll  20 . This release of vacuum pressure functions to release engagement of the sheet  30  with the outer surface of count roll  20 . 
     In operation, when a desired sheet count is attained, the vacuum source is actuated to supply vacuum pressure to a selected one of vacuum inlet components  165   a – 165   d,  such as  165   a.  Vacuum pressure is transferred through one of the recesses in valve body  145 , such as recess  148   a,  and through the recess opening such as  151   a  to the chamber or passage, such as  200   a,  in spool  140 . In this manner, vacuum is supplied to the appropriate port path  185  and the associated set of vacuum ports, such as  218   a,  that open onto the surface of count roll  20 . In this manner, the supply of vacuum to the vacuum ports such as  218   a  functions to engage the leading edge of a sheet  30  out of overlapping relationship with the trailing edge of the downstream sheet, as shown in  FIG. 8 . Continued rotation of count roll  20  folds the sheet  30  onto itself, to create a separation in the supply of sheets to the folding rolls. When count roll  20  attains a rotational position corresponding to the location at which sheet  30  is to be released, spool  140  is positioned so that the activated chamber or passage, such as  200   a,  enters opening  225  in OFF valve  155 . As noted previously, this release of vacuum pressure releases engagement of the sheet  30  with the outer surface of count roll  20 , so that the folded sheet  30  is release and continues in the path toward folding rolls  90 ,  95 , as shown in  FIG. 9 . 
     The location at which activation or ON vacuum is supplied can be adjusted as desired by rotating the stationary valve body  145 . Similarly, the location at which vacuum is cut off can be adjusted by rotation of OFF valve  155 . Passages  151   a – 151   d  are in axial alignment with each other, which ensures that vacuum actuation occurs at a consistent point in the rotation of spool  140 , regardless of which of vacuum inlets  165   a – 165  is actuated. 
     The present invention provides numerous advantages in operation, including the ability to closely control the location at which vacuum is supplied to and cut off from the vacuum ports of the count roll. In addition, the chambered design of the present invention increases the available valve switching time. In contrast to known valve assemblies, each chamber  200   a–d  has an available dead time in excess of two hundred-seventy degrees of rotation, during which the chamber can be energized or activated with vacuum pressure. This increase in the available switching time can increase the potential operating speed of the interfolding machinery. Furthermore, individual port activation provides the availability of any sheet count, including odd numbered counts. In contrast, known valve assemblies are only able to provide even numbered counts. 
     A wide variety of machines or systems could be constructed in accordance with the invention defined by the claims. Hence, although the exemplary embodiment of a count assembly  20  in accordance with the invention will be generally described with reference to an interfolding machine for counting overlapped sheets of material  30  to be interfolded into a stack  32 , the application of the count assembly  20  is not so limited. The count assembly  20  of the invention could be employed to count a variety of web-materials being fed for a wide variety of uses and is not limiting on the invention. 
     The above discussion, examples, and embodiments illustrate our current understanding of the invention. However, since many variations of the invention can be made without departing from the spirit and scope of the invention, the invention resides wholly in the claims hereafter appended.