Abstract:
An apparatus and method for separating a web material are disclosed herein. The apparatus includes a bedroll and a chop off roll. The bedroll includes a bedroll blade and a bedroll web pin. The chop off roll includes a pin pad and a plurality of chop off roll blades. The bedroll web pin and the bedroll blade mesh with the pin pad and the chop off roll blades. The chop off roll blades are moved relative to the bedroll blade, stretching and separating the web material. The web pin perforates the web material and may completely or partially separate a portion of the web material. The web pin and the separated portion perforate the pin pad. The separated portion is stripped from the web pin as the pin passes out of the pin pad.

Description:
CROSS-REFERENCE TO RELATION APPLICATION 
       [0001]    This application is a divisional of Ser. No. 10/652,325, filed Aug. 29, 2003. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to an apparatus for separating a web material. More particularly, the invention relates to an apparatus for separating a web material along a line of weakness. 
       BACKGROUND OF THE INVENTION 
       [0003]    Web materials are a ubiquitous part of daily life. Metal foils, plastic films, plastic bags, paper toweling, bath tissue, facial tissues, thread, wire and rope are all web materials. The manufacturing of these web materials often requires the formation of small discrete rolls of the web material from a large source roll, or parent roll. The formation of the small rolls requires the separation of the web material into smaller lengths corresponding to the quantity of web material desired for the small roll. 
         [0004]    The web material as it is provided in the small roll often comprises lines of weakness that are transverse to the length of the web material to facilitate further separation of the web material into discrete segments for use by the consumer. It is desirable to separate the web material at a line of weakness when a first small roll is completed and prior to the beginning of a subsequent small roll. The separation of the material at a line of weakness yields a more uniform appearing roll and more efficient handling of the web material during the processing from a parent roll into small rolls. 
       SUMMARY OF THE INVENTION 
       [0005]    An apparatus and method for separating a web material is described herein. In one embodiment the apparatus comprises a bedroll. The bedroll is disposed such that web material passes around at least a portion of the circumference of the bedroll in a direction of travel. The bedroll is disposed generally transverse to the direction of travel. The bedroll comprises a shell and a bedroll chop off assembly. The bedroll chop off assembly comprises at least one web pin and at least one blade. The at least one blade is disposed generally transverse to the direction of travel and oriented with a blade tip directed away from the center of the bedroll shell. The blade tip and a tip of the web pin are capable of extending beyond the circumference of the shell of the bedroll. The bedroll is capable of rotating at a first circumferential speed. 
         [0006]    The apparatus further comprises a chop off roll. The chop off roll is disposed proximally to the bedroll and generally parallel to the bedroll. The chop off roll comprises at least one pin pad and at least two blades. The pin pad is capable of circumferentially interfering with at least one web pin of the bedroll. The blades are disposed generally transverse to the direction of travel of the web. The two blades are disposed at a chop off blade spacing. The two blades are capable of rotationally meshing with at least one bedroll blade. The chop off roll is capable of rotating at a second circumferential speed that is distinct from the first circumferential speed. 
         [0007]    In another aspect, the invention comprises a method for separating a web material along a line of weakness. The method comprises steps of providing a bedroll as set forth above, and providing a chop off roll disposed proximal to the bedroll and generally parallel to the bedroll. The chop off roll is spaced apart from the bedroll by a chop off gap. The method further comprises steps of rotating the bedroll at a first circumferential speed, and rotating the chop off roll at a second circumferential speed. The second circumferential speed is distinct from the first circumferential speed. The web material is routed through the chop off gap. The web material is perforated by the web pin and the web material and web pin perforate at least a portion of a pin pad. The chop off blades and at least one bedroll blade rotationally mesh and the web is separated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    While the claims hereof particularly point out and distinctly claim the subject matter of the present invention, it is believed the invention will be better understood in view of the following detailed description of the invention taken in conjunction with the accompanying drawings in which corresponding features of the several views are identically designated and in which: 
           [0009]      FIG. 1  is a schematic side view of a portion of a bedroll and chop off roll of one embodiment of the invention. 
           [0010]      FIG. 2  is a schematic side view of a portion of a bedroll and chop off roll according to another embodiment of the invention. 
           [0011]      FIG. 3  is schematic side view of a pin pad and web pin according to the invention. 
           [0012]      FIG. 4  is a schematic view of a portion of a chop off roll blade according to one embodiment of the invention. 
       
    
    
       [0013]    All references cited in the following detailed description of the invention are hereby incorporated herein by reference. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0014]      FIG. 1  illustrates an embodiment of the apparatus of the invention. As shown in the figure, the apparatus comprises a bedroll  100 , and a chop off roll  200 . The bedroll  100  and chop off roll  200  are generally cylindrical and are disposed generally parallel to each other. A gap  400  is present between the outer circumference  105  of the bedroll  100  and the outer circumference  205  of the chop off roll  200 . A web material  300  is routed through the gap  400  between the bedroll  100  and the chop off roll  200  and around at least a portion of the circumference  105  of the bedroll  100 . The web material proceeds through the gap  400  in a direction of travel. The bedroll  100  and the chop off roll  200  are disposed generally transverse to the direction of travel of the web material  300 . 
         [0015]    The web material  300  may comprise any web material known in the art. Exemplary web materials include without being limiting, wire, rope, thread, paper webs including tissue and hard grades of paper, metal foils, plastic and celluloid films. The web material  300  is characterized by having one dimension much greater than the other two dimensions. The web material  300  may have a first dimension (length) and a second dimension (width) each much greater than a third dimension (thickness). The web material may comprise lines of weakness  310  generally transverse to the length of the web material  300 . A line of weakness  310  comprises a portion of the web material  300  having a tensile strength along the length of the web material  300  that is measurably less than the tensile strength of other portions of the web material  300 . During the processing of the web material  300  it is often desirable to separate the web material  300  at a line of weakness  310 . 
         [0016]    The bedroll  100  comprises a shell  110  and a bedroll chop off assembly  120 . The bedroll chop off assembly  120  is movable from a first position to a second position through the action of at least one cam and cam follower combination as is known in the art. The bedroll chop off assembly  120  comprises at least one web pin  130 , and at least one blade  140 . The web pin  130  is disposed proximally to the blade  140  and comprises a pin tip  132 . The bedroll chop off assembly  120  may comprise a plurality of web pins  130  disposed generally along a line generally transverse to the direction of travel of the web material  300 . The blade  140  is disposed generally transverse to the direction of travel of the web material  300  and comprises a blade tip  142 . In one embodiment, the bedroll chop off assembly  120  comprises a single blade  140 . In another embodiment the chop off assembly  120 , comprises two blades  140 . In another embodiment the bedroll chop off assembly  120 , comprises three blades  140 . Still other embodiments comprising more than three blades  140  are within the scope of the invention. In each embodiment comprising a plurality of blades  140 , the blades  140  are disposed transverse to the direction of travel of the web material  300  and are generally parallel to each other separated by a bedroll blade spacing. 
         [0017]    As the bedroll chop off assembly  120  moves from the first position to the second position, the web pin tip  132  and the blade tip  142  move from a radial position that is within the circumference of the shell  110  of the bedroll  100  to a radial position that is beyond the shell  110  of the bedroll  100 . In this second position, the web pin tip  132 , and the blade tip  142 , interfere with the plane of the web material  300  as the web material, the blade and the web pin pass through the gap  400 . 
         [0018]    The bedroll  100  is capable of powered rotating about its axis. This powered rotation may be achieved by any means that is known in the art. As the bedroll  100  rotates, the blade  140  and web pin  130  move past the gap  400  at a first circumferential velocity depending upon the rotational speed of the bedroll  100  and the radial location of the bedroll chop off assembly  120 . The blade  140  and web pin  130  are disposed in the bedroll chop off assembly  120  such that as the bedroll  100  rotates, the blade  140  passes through the gap  400  followed by the web pin  130 . The circumferential velocity is determined as the tangential speed at the radial position defined by the blade tip  142 . 
         [0019]    The chop off roll  200 , comprises at least one pin pad  230  The pin pad  230  is disposed in alignment with the web pin  130  of the bedroll  100 . The pin pad  230  and the web pin  130  interfere with each other and the web pin tip  132  perforates at least a portion of the pin pad  230  as the pin pad  230  and the web pin  130  pass together through the gap  400 . In another embodiment the chop off roll  200  comprises a plurality of pin pads  230  disposed along a line generally transverse to the direction of travel of the web material  300 . In this embodiment, the pin pads  230  are aligned with the web pins  130  located on the bedroll chop off assembly  120 . 
         [0020]    As shown in  FIG. 3 , the pin pad  230  comprises a first portion  232  comprising a resilient material, and a second portion  234 . The first portion  232  and/or the second portion  234  define an open chamber  236 . The second portion  234  may comprise a resilient material or may comprise a non-resilient material. Exemplary resilient materials include closed cell polyester foam, and urethane materials. Exemplary non-resilient materials include metal substrates such as steel, copper, tin and aluminum, polycarbonates, acrylics and other polymeric materials as are known in the art. The first portion  232  is fixedly attached to the second portion  234 . The first portion  232  is disposed on the chop off roll  200  at a radial position that will interfere with the web pin tip  132 . The shape of the pin pad  230  facilitates the perforation of a portion of the pin pad  230  by the web pin  130  and by any web chad  500  separated from the main web  300  by the web pin  130 . The web chad  500  and the web pin tip  132 , pass into the chamber  236  of the pin pad  230 . The pin pads may be provided individually or as a plurality of pin pads formed in an assembly. The pin pad  230  may be fastened to the chop off roll  200  by any means known in the art. Mechanical fasteners, such as nails, screws, and rivets, adhesives, clamping mechanisms, or sliding dovetail fasteners are non-limiting examples of means for fastening the pin pads  230 . 
         [0021]    The chop off roll  200  further comprises at least two blades  240 . The blades  240  are disposed generally transverse to the direction of travel of the web material  300  and generally parallel to each other and separated by a chop off roll blade spacing. One blade  240  is disposed proximal to the pin pad  230 . In an embodiment comprising a plurality of pin pads  230 , one blade is disposed parallel to the line along which the plurality of pin pads  230  are disposed. The blades  240  each comprise a blade tip  242 . In another embodiment the chop off roll  200  comprises three blades  240 . Embodiments wherein the chop off roll  200  comprises more than three blades are within the scope of the invention. The blades  240  may be provided as single blades, or the blades  240  may be provided as pairs through u-channels. 
         [0022]    The u-channel  260  illustrated in  FIG. 4  comprises two blades  240 , and a connecting element  248 . As shown in the figure, the u-channel  260  is attached to a blade head  270  together with the pin pad  230 . The blade head  270  is attached to the chop off roll  200 . The chop off roll  200  is capable of powered rotation about its axis. This powered rotation may be achieved by any means for rotating a cylindrical roll as are known in the art. The blades  240  and pin pad  230  are disposed relative to each other such that as the chop off roll  200  rotates, the blades  240  pass through the gap first followed by the pin pad  230 . The chop off roll  200  rotates at a second circumferential speed corresponding to the tangential speed of the circumference defined by the radial position of the blade tips  242 . 
         [0023]    The rotation of the bedroll  100  is synchronized with the rotation of the chop off roll  200  by means known in the art. The synchronized rotation yields a meshing of the blade  140  of the bedroll  100  between the blades  240  of the chop off roll  200  as the blades  140  and  240  pass through the gap. The radial positions of the bedroll blade tip  142  and the chop off roll blade tips  242  interfere with each other. The position of the bedroll blade  140  and the chop off roll blades  240  must be maintained such that the blades  140  and  240  do not occupy the same space when passing through the gap  400 . 
         [0024]    In one embodiment, the radius of the chop off roll  200  is similar to the radius of the bedroll  100 . The similarity of radii facilitates a large depth of engagement between the bedroll blade  140  and the chop off roll blade  240  as the respective blades mesh in the gap  400 . This large depth of engagement facilitates a greater stretching of the web  300  as the blades mesh. 
         [0025]    The circumferential velocity of the blade tips  142  and  242  are maintained at different velocities as the tips  142  and  242  pass through the gap  400 . The differing blade tip velocities yield relative motion between the blade  140  and blades  240  as the blades mesh. This relative motion may be used to separate the web material  300  at a line of weakness  310 . 
         [0026]    The blades  140  and  240  may each comprise a single blade segment. In another embodiment, each blade may comprise a plurality of blade segment. In this embodiment, the blade segments may be disposed adjacent each to the next along a line generally transverse to the direction of travel with little if any spacing between the segments in the direction transverse to the direction of travel. In another embodiment, the blade segments may be spaced apart by a segment gap. The segment gap may range from 0.125 to 2 inches (3 to 50 mm). In another embodiment the gap may range from 0.5 to 1.5 inches 12 to 37 mm). The segment gap varies according to the nature of the web material and the separation characteristics of the web material  300 . Blades comprising a plurality of spaced apart blade segments require less material and facilitate the removal and replacement of a damaged segment without the necessity of replacing an entire blade. As described above, the blades may be provided as single blades or as a u-channel. 
         [0027]    As shown in  FIG. 4 , the blades  240  may comprise a serrated web contacting edge. The serrations  246  of the web contacting edge may stabilize the position of the web material and facilitate the stretching of the web material  300  and subsequent failure of the line of weakness  310 . In an alternative embodiment, the blade  140  may comprise a serrated web contacting edge  146 . 
         [0028]    The chop off roll  200  may further comprise a web pad  250  or plurality of web pads  250 . The web pad is disposed adjacent to the blades  240  and comprises an outer surface disposed radially at a distance about equal to the radial position of the blade tip  242 . The web pads  250  are disposed generally along a line transverse to the direction of travel of the web material  300 , and downstream from the blades  240  on the circumference  205  of the chop off roll  200 . 
         [0029]    As the web pads  250 , blades  140  and  240 , web pins  130  and pin pads  230  pass sequentially through the gap  400 , the web pads  250  press the web material  300  against the circumference  105  of the bedroll shell stabilizing the position of the web material  300  as the blades  140  and  240  mesh to constrain the web material to ultimately yield the failure of the web material  300  at a line of weakness  310 . 
       Method of Use 
       [0030]    The use of the above described apparatus comprises routing a web material  300  around a portion of the circumference of the bedroll  100  and through the gap  400 . The bedroll  100  and chop off roll  200  are concurrently rotated. The blades  240  and  140  mesh in the gap  400 . The web material  300  is constrained to a path defined by the blade tips  142  and  242 . The circumferential velocities of the bedroll  100  and chop off roll  200  are varied one from the other. The variance in velocities causes the blade tips  142  and  242  to move relative to each other changing the web path. Without being bound by theory, Applicants believe the web material  300  is stretched by the relative blade movement and subsequently fails at a line of weakness  310 . 
         [0031]    After the web material fails at a line of weakness  310 , the downstream portion of the web material  300  proceeds through the converting process as the tail of the last separated portion of the web material  300 . The web material portion may be wound in a roll or subjected to various other converting processes. The upstream portion of the separated web material  300  is the leading edge of the web material yet to be processed. The web pins  130  penetrate the upstream portion prior to the web separation to secure the upstream web and provide for consistent web handling of the upstream web. 
         [0032]    The web pins  130  may each tear a small chad  500 , of the web material  300  during web penetration. The chad  500  may be completely severed, or partially severed from the web material  300 . As is known in the art, the web pin  130 , together with the chad  500 , penetrates the pin pad  230  and the chad  500  may become lodged in the pin pad  230 . The accumulation of chads  500  impacted upon each other in the pin pad  230  may damage the web pins  130 , and may reduce the service life of the pin pads  230 . As shown in  FIG. 3 , Applicants&#39; design for a pin pad  230  provides for the complete perforation of a portion of the pin pad  230  by the web pin  130  and the chad  500 . The web pin  130  and chad  500  pass into, and completely through, a portion of the pin pad  230  into the chamber  236 . The web pin  130  subsequently passes back through the pin pad  130 , and the chad  500  is stripped away from the web pin  130 . The chad  500  subsequently falls from the chamber as the chop off roll  100  rotates. The chads  500 , do not accumulate and the useful service life of the pin pads is not adversely affected by an accumulation of chads  500 . 
         [0033]    While particular embodiments of the present invention have been illustrated and described, it would have been obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of the invention.