Abstract:
A system for removing chips from a web is disclosed, the system having a rotationally variable speed shoe for receiving a chip, a rotationally constant speed transfer roll for receiving a portion of a web from a die and anvil system, with the shoe initially rotating at a constant speed, slowing to allow a portion of the web to rip away from the chip at a leading rotational edge of the chip, next increasing in rotational speed to allow the chip to rip away from the web at a trailing rotational edge of the chip.

Description:
RELATED APPLICATION 
     This is a continuation application of U.S. Ser. No. 11/436,274, filed 18 May 2006 now U.S. Pat. No. 7,780,052. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to disposable undergarments and, more specifically, to methods and apparatuses for forming disposable undergarments, and particularly to removing unwanted portions of web material such as leg holes, from the undergarment as it is formed. 
     Generally, disposable undergarments such as pants-type diapers are made up of two nonwoven layers of material with elastic strands of material placed between the two nonwoven layers of material thus creating an elastic web laminate. The layers of material are continuous sheets of material that are eventually cut into individual undergarment lengths. The elastic strands may be arranged and cut so that specific areas of the undergarment are free of elastic tension or forces. An absorbent pad, often contained within an insert or core is then also placed into the pants-type diaper product. 
     To insure the pants-type diaper retains a proper shape and to hold all of the added layers of the diaper, reinforcing layers and backing materials are normally added to the continuous sheets of material, with the reinforcing layers corresponding to the cut elastic strands of each individual blank. Each of these layers needs to be adhesively joined at some point in the manufacturing process to the elastic web laminate to form the completed undergarment. 
     Often, void spaces need to be created in the diaper, such as holes cut out of the main web for provided leg holes when the undergarment is ultimately formed. To create the void spaces, the web is ordinarily die cut, with the web severed between a die and an anvil. The portion of the web material that is removed is referred to as a “chip.” As the die wears throughout time, the severing of the chip from the web material becomes gradually a duller cut. This complicates the removal of the chip because the severing might not create a continuous cut out chip, with possibly some strands of the web material still coupling the chip with the web. It is desired to lengthen the amount of time and increase the number of chips that a single die can effectively be used for, to reduce the number of die change-outs. 
     SUMMARY OF THE INVENTION 
     A system for removing chips from a web is disclosed, the system comprising a rotationally variable speed shoe for receiving a chip, a rotationally constant speed transfer roll for receiving a portion of a web from a die and anvil system, said shoe initially rotating at said constant speed, next slowing in rotational speed to allow said portion of said web to rip away from said chip at a leading rotational edge of said chip, next increasing in rotational speed to allow said chip to rip away from said web at a trailing rotational edge of said chip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a trim shoe of the present invention, with an infeed web, and a chip to be removed therefrom. 
         FIG. 2  is a two dimensional representation of the trim shoe of  FIG. 1 . 
         FIG. 3  is a cross sectional view of a trim shoe. 
         FIG. 4  is a schematic view of a trim shoe receiving an article from a transfer roll in an initial chip engaging position. 
         FIG. 5  is a schematic view of the trim shoe separating a first article from a second article. 
         FIG. 6  is a schematic view of the trim shoe separating trim from the first article. 
         FIG. 7  is a schematic view of the trim shoe discharging the trim. 
         FIG. 8  is a schematic view of the trim shoe returning to its initial chip engaging position. 
         FIG. 9  is a schematic view of the trim shoe returned to its initial chip engaging position. 
         FIGS. 10-13  are plan views of the position of the chip relative to the web, demonstrating the ripping effects of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     Referring now to  FIG. 1  a perspective view of a trim removal system  10  of the present invention is shown. An infeed web  24 , and a chip or chips  30  to be removed therefrom is shown. A transfer roll  14  and an associated trim shoe or trim shoes  12  are provided to engage the web  24  and chips  30 . Preferably, the trim shoes  12  are shaped complimentary with the chips  30 . Vacuum ports  16  are provided on the transfer roll  14  and trim shoes  12  for maintaining the web  24  and chips  30  in close contact with the transfer roll  14  and trim shoes  12 . 
     An inner axle  18  and an outer axle  20  are coupled to the transfer roll  14  (or hub  22 ) and the trim shoes  12 , respectively. The inner axle  18  and the outer axle  20  are capable of being operated at different speeds in relation to one another by servo motor (not shown). This difference in speed allows the trim shoes  12  to rotate faster or slower with respect to the transfer roll  14  as desired. In use, as will be described later, this speed differential creates a ripping effect by first pulling the web  24  away from the chip  30  as the transfer roll  14  is rotating faster than the shoe  12 , then by pulling the chip  30  away from the web  24  as the shoe  12  is rotating faster than the transfer roll  14 . 
     Referring now to  FIG. 2 , a two dimensional representation of the trim shoe  12  and transfer roll  14  of  FIG. 1  is shown. As can be seen, vacuum channels  17  communicate with vacuum ports  16  on both the trim shoe  12  and transfer roll  14  to maintain control of the chip  30  and web  24 . From this perspective, it can be seen that different rotational speeds of the trim shoe  12  and transfer roll  14  will cause a ripping effect by first pulling the web  24  away from the chip  30  as the transfer roll  14  is rotating faster than the shoe  12 , then by pulling the chip  30  away from the web  24  as the shoe  12  is rotating faster than the transfer roll  14 . 
       FIG. 3  is a cross sectional view of a trim shoe  12  and transfer roll  14  of the present invention. As can be seen, vacuum is communicated to ports  16  through channels  17 , which are coupled to a source of vacuum (not shown). Rotation of the outer axle  20 , which is coupled to the shoe  12 , causes rotation of the shoe  12 . The inner axle  18  is coupled preferably to hub  22  and to transfer roll  14 . 
     Referring now to  FIGS. 4-9 , a sequence is shown of the trim removal system  10  removing chips  30  and discharging them, and then the system  10  returning to its initial position to remove more chips  30  from the next segment of web  24 .  FIGS. 10-13  are plan views of the position of the chips  30  relative to the web  24  at the positions associated with  FIGS. 4-7  respectively, demonstrating the ripping effects of the present invention. 
     Referring now to  FIG. 4 , a schematic view of the system  10  is shown receiving an infeed web  24 . In this figure, die and anvil system  26  is shown rotating to engage the web  24  and cut from it chips  30  (not apparent in this view), as is well known in the art. Unfortunately, the die of the die and anvil system  26  is susceptible to wear and tear and requires replacement once the die dulls to an unacceptable condition. 
     In this view, the trim shoe  12  can be seen in an initial chip engaging position, aligned to receive the chip  30  of the web  24  onto the shoe  12 , which, as described previously, will be urged against the surface of the shoe  12  by vacuum ports  16 . The trim shoe  12  will be seen to be rotating about outer axis  20 . In this view, a discharge chute  28  is shown for ultimately receiving waste chips  30 , and an outfeed conveyor  40  is provided for receiving the web  24  with the chip  30  removed, for further processing and manufacturing steps in the composition of the disposable garments, as desired. 
     Inner axle  18  is preferably operated at a first continuous speed, rotating hub  22  and transfer roll  14  at a continuous speed, consistent with the infeed speed of the web  24 . At this initial chip engaging position shown in  FIG. 4 , the outer axle  20 , and associated shoes  12 , are rotated at the same speed as the inner axle  18 . 
     The position of the chip  30  relative to the web  24  is shown in  FIG. 10  for the initial chip engaging position. In this position, the anvil and die  26  has created a sever, but the chip  30  and web  24  could remain somewhat coupled depending on the sharpness of the die  26 . 
     Referring now to  FIG. 5 , the outer axle  20 , and associated shoes  12 , are toggled slower than inner axle  18  to allow the web  24  to be ripped from the chip  30  at the leading edge of the chip  30  in the machine direction. It is apparent in this view that the distance between the trailing edge of the shoes  12  has become closer to the leading edge of the transfer roll  14 . 
     This ripping is caused by the main web  24  being ripped away from the chip  30  at the leading edge of the chip  30  as is shown in associated  FIG. 11 . 
     Referring now to  FIG. 6 , the outer axle  20  is toggled equal to and then faster than the inner axle  18 , to allow the chips  30  to rip from the web  24  at the trailing edge of the chips  30  as is shown in associated  FIG. 12 . 
     At this point in the process, the chip will be removed from the web  24  by ripping first the main web  24  away from the chip  30  at the leading edge of the chip  30 , and next by ripping the trailing edge of the chip  30  from the web  24 . 
     The outfeed conveyor  40  is provided for receiving the web  24  with the chip  30  removed as shown in  FIG. 13 , for further processing and manufacturing steps in the composition of the disposable garments, as desired. The vacuum of the transfer roll  14  can be turned off at this point to allow for release of the web  24  to the conveyor, for instance in accordance with application Ser. No. 11/141,552, entitled “High Speed Vacuum Porting” which is incorporated herein by reference. 
     Referring now to  FIG. 7 , the chip  30  is discharged into a discharge chute  28 , which is preferably vacuum assisted, although other collection means would satisfactorily accomplish the function of collecting waste chips  30 . 
     It is noted that vacuum is allowed to turn off of the shoes  12  to allow the chips  30  to release into the chute  28 . Alternatively a vacuum in the chute  28  could simply be provided that is stronger than the vacuum applied to the shoes  12 . 
     The rotational speed of the shoes  12  and outer axle  20 , which were first operated at a speed roughly equal to inner axle  18 , rotating hub  22  and transfer roll  14 , initially decreased, or lagged as is shown by comparing  FIG. 4  with  FIG. 5 . 
     Next, the rotational speed of the shoes  12  and outer axle  20 , increased, or surged relative to the inner axle  18 , rotating hub  22  and transfer roll  14 . 
     In order to return to the initial chip engaging position, the rotational speed of the shoes  12  and outer axle  20 , must again decrease, or lag relative to the inner axle  18 , rotating hub  22  and transfer roll  14 . This lag is apparent by comparing  FIG. 6  to  FIGS. 7 ,  8  and  9 . Finally, in  FIG. 9 , through one revolution, the system  10  has removed and discharged the chips  30 , discharged the web  24  for further processing, and the shoes  12  have been returned to their initial position to remove more chips  30  from the next segment of web  24 . 
     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.