Abstract:
A method and an apparatus for pre-fastening disposable absorbent articles having a slot-and-tab fastening system during manufacturing of the pre-fastened disposable articles, such as diapers, pull-on diapers, training pants, adults incontinence pads and the like.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of the parent application U.S. Ser. No. 10/036,633 filed on Dec. 21, 2001; U.S. Pat. No. 6,669,618. 

   FIELD OF THE INVENTION 
   The present invention relates to a high-speed-manufacturing method of pre-fastening a disposable absorbent article having a slot-and-tab fastening system. 
   BACKGROUND 
   Disposable absorbent articles such as diapers, pull-on diapers, training pants, adults incontinence pads and the like, can include a fastening system for joining the front of the article to the rear of the article. The fastening system can comprise a tab member and a slot member disclosed in U.S. patent application Ser. No. 09/143,184 filed on Aug. 28, 1998, which is incorporated by reference herein. The disclosed fastening system is a refastenable fastening system that enables the wearer or the caretaker to refasten the article during the wear to provide a more comfortable fit. The engagement of the tab and slot members can be done by the wearer or caretaker when securing the article around the wearer, or, alternatively, during manufacturing of the article to effect a pre-fasten article that is ready to be pulled on the wearer. Such manufacturing requires folding a normally flat-out article into a folded configuration and inserting the tab member into a slot of the slot member to form the pre-fastened article. However, the manufacturing of disposable absorbent article is normally a high-speed production wherein individual articles often move along a production path at a speed of hundreds feet per minute, and inserting the tab member into the corresponding slot of the slot member at such high production speeds represents a problem. 
   Therefore, it would be beneficial to provide a high-speed-manufacturing method of pre-fastening a disposable absorbent article having a slot-and-tab fastening system to produce a pre-fastened absorbent article having engaged tab and slot members. 
   SUMMARY OF THE INVENTION 
   In response to the difficulties and problems discussed above, a new high-speed method of pre-fastening disposable absorbent articles during manufacturing of pre-fastened disposable absorbent articles having a slot-and-tab fastening system has been discovered. 
   The present invention concerns a method of dynamically pre-fastening disposable absorbent articles having a slot-and-tab fastening system as the articles are driven forward at a relatively high velocity along a predetermined path. The method includes the step of providing a disposable absorbent article being folded longitudinally into a bi-fold configuration. The method further includes the step of inserting at least a portion of a tab member of the slot-and-tab fastening system through a slot of the slot-and-tab fastening system. And the method further includes the step of while holding the portion of the tab member being inserted through the slot, moving the slot member of the article opposite to the direction of insertion of the portion of the tab member until the slot of the slot member passes beyond a lip portion of the tab member to effect a complete insertion of the tab member though the slot member and to effect a closed configuration of the slot-and-tab fastening system forming a pre-fastened disposable absorbent article. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter, which is regarded as the present invention, it is believed that the invention will be more fully understood from the following description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a plan view of a diaper having a fastening device comprising a tab member and a slot member in its flat out, uncontracted state with the body-facing surface oriented toward the viewer; 
       FIG. 2  is a perspective view of the diaper of  FIG. 1 , wherein the tab member is engaged with the slot member by passing the tab member through the slot of the slot member; 
       FIG. 3  is a plan view of the slot member of the diaper of  FIG. 1 ; 
       FIG. 4  is a plan view of the tab member of the diaper of  FIG. 1 ; 
       FIG. 5  is a plan view of the engaged tab and slot members; 
       FIG. 6  is an end view of the engaged tab and slot members shown in  FIG. 5 ; 
       FIG. 7  is a simplified front elevation view of one embodiment of an apparatus of the present invention; 
       FIG. 7   a  is a magnified, partial, front elevational view of the circled area  7   a  shown in  FIG. 7 ; 
       FIG. 8  is fragmental, simplified side plan view taken along arrow  8  of the apparatus of  FIG. 7 , showing two slot locators; 
       FIG. 9  is a cross-sectional view, taken along lines  9 — 9 , of the slot locator shown in FIG.  8 . 
       FIG. 10  is an enlarged view of circled area  10  of  FIG. 7   a , showing the diaper in its instant position just prior to thrusting a leading part of the diaper pad against a stationary folding board of the apparatus of the present invention; 
       FIG. 11  is an enlarged view of circled area  11  of  FIG. 7   a , showing the diaper in its instant position of thrusting the leading part of the diaper pad against the stationary folding board of the apparatus of the present invention; 
       FIG. 12  is an enlarged view of circled area  12  of  FIG. 7   a , showing the diaper in its instant position having the tab member intercepted between a guiding rail and the folding board; 
       FIG. 13  is an enlarged view of circled area  13  of  FIG. 7   a , showing the diaper in its instant position of aligning the tab member with a slot of the slot member; 
       FIG. 14  is a cross-sectional view, taken along lines  14 — 14  in  FIG. 13 , showing alignment of the tab member with the slot of the slot member by the guiding rail and the folding board; 
       FIG. 15  is an enlarged view of circled area  15  of  FIG. 7   a , showing the diaper in its instant position of initially inserting the tab member into the slot of the slot member; 
       FIG. 16  is an enlarged view of circled area  16  of  FIG. 7   a , showing the diaper in its instant position of further inserting the tab member into the slot and attaching the inserted portion of the tab member to the drum by a tab-clamping device; 
       FIG. 17  is cross-sectional view, taken along lines  17 — 17  in  FIG. 16 , illustrating the tab-clamping device attaching the tab member to the drum; 
       FIG. 18  is an enlarged view of circled area  18  of  FIG. 7   a , showing the diaper in its instant position of pulling off the diaper by a take-away conveyor to complete the insertion of the tab member through the slot of the slot member to effect the engagement; and 
       FIG. 19  is a simplified front elevation view of another embodiment of an apparatus of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As used herein, the term “absorbent article” refers to devices, which absorb and contain body exudates and, more specifically, refers to devices that are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. 
   The term “disposable” is used herein to describe absorbent articles, which generally are not intended to be laundered or otherwise restored or reused as absorbent articles (i.e., they are intended to be discarded after a single use and, preferably, to be recycled, composted or otherwise discarded in an environmentally compatible manner). 
   The term “diaper” refers to an absorbent article generally worn by infants and incontinent persons about the lower torso and typically having a fastening system to connect a back waist region with the front waist region in a closed configuration so as to provide lateral tensions about the circumference of the diaper to hold the diaper on the wearer. 
   The term “pre-fastened disposable article” or “pre-fastened article” or “pre-fastened diaper” refers herein to disposable absorbent articles, which are provided to consumer in a pre-fastened configuration of the fastening system (i.e., the fastening system is engaged to form a closure) of the article and, which are intended to be put on the wearer through the legs of the wearer. 
   The terms “pull-on diaper” and/or “training pants” refer herein to disposable absorbent articles typically having a fixed, closed configuration around the waist of the wearer and, which are intended to be put on the wearer by pulling the article through the legs of the wearer. 
   For ease of understanding, much of the following description with respect to disposable absorbent articles comprising a slot-and tab fastening system will be made in terms of a diaper  20  disclosed in U.S. patent application Ser. No. 09/143,184 filed on Aug. 28, 1998, which is incorporated by reference herein. 
     FIG. 1  illustrates a plan view of one embodiment of the diaper  20  in its flat-out, uncontracted state (i.e., with elastic induced contraction pulled out) including a slot-and-tab fastening system  40 . The portion of the diaper  20  that faces or contacts the wearer, the inner surface  50 , is oriented towards the viewer. As shown in  FIG. 1 , the diaper  20  preferably comprises a liquid pervious topsheet  22 ; a liquid impervious backsheet  24  joined with the topsheet  22 ; an absorbent core  26  positioned between the topsheet  22  and the backsheet  24 ; side panels  28 ; leg cuffs  32 ; a waist feature  30  and the slot-and-tab fastening system  40 . 
   The diaper  20  is shown in  FIG. 1  to have an outer surface  52 , an inner surface  50  opposed to the outer surface  52 , first waist region  36 , a second waist region  38  opposed to the first waist region  36 , a crotch region  37  positioned between the first waist region  36  and the second waist region  38 . The diaper  20  also has longitudinal edges  54  and end edges  56 . The inner surface  50  of the diaper  20  generally comprises that portion of the diaper  20  that is positioned adjacent to the wearer&#39;s body during use (i.e., the inner surface  50  generally is formed by at least a portion of the topsheet  22  and other components joined to the topsheet  22 ). The outer surface  52  generally comprises that portion of the diaper  20  that is positioned away from the wearer&#39;s body (i.e., the outer surface  52  generally is formed by at least a portion of the backsheet  24  and other components joined to the backsheet  24 ). The diaper  20  also has a longitudinal centerline  100  and a lateral centerline  110 . 
   The slot-and-tab fastening system  40  joins at least a portion of the first waist region  36  of the diaper  20  with at least a portion of the second waist region  38 , preferably to form leg and waist openings. As shown in  FIGS. 1 and 2 , the fastening system  40  can comprise a tab member  42  and a slot member  44 . 
   The slot member  44 , shown in  FIG. 3 , includes an inboard portion  64  attached to the side panel  28 , an outboard portion  66  and a slot  46  disposed between the inboard portion  64  and the outboard portion  66 . The slot  46  has a length S. 
   As shown in  FIG. 5 , the tab member  42  preferably includes a generally elongate member having a length T, a proximal edge  60 , a distal edge  62 , a lip portion  48  generally adjacent at least a portion of the proximal edge  60 . The length T of the tab member  42  should be sized to fit through the slot  46  of the slot member  44  with little or no bending or deformation of either component. The lip portion  48  is that portion of the tab member  42  which is not joined directly to the underlying structure of the article to which the tab member  42  is attached. The lip portion  48  should lift away from the underlying structure of the article so that it can be positioned in an overlapping configuration with at least a portion of the outboard portion  66  of the slot member  44  when in use (shown in FIGS.  5  and  6 ). 
   As shown in  FIG. 6 , the fastening system  40  can be fastened by passing the tab member  42  completely through the slot  46  of the slot member  44 . Once the tab member  42  has been passed through the slot member  44 , as shown in  FIGS. 7 , the lip portion  48  of the tab member  42  is rotated into a plane generally parallel with the plane of the slot member  44  such that at least a part of the lip portion  48  is overlapping at least a part of the outboard portion  66  of the slot member  44 . In this configuration, the lip portion  48  of the tab member  42  will prevent the tab member  42  from slipping back through the slot  46  and disengaging the fastening system  40 . 
   Referring to  FIG. 1 , the diaper  20  has a longitudinal centerline  100  dividing the diaper  20  laterally equally between two opposing longitudinal edges  54 , and a lateral centerline  110  dividing the diaper  20  longitudinally equally between two opposing end edges  56 . The diaper  20  also has fastening centerline  120  dividing the diaper  20  longitudinally equally between the tab member  44  and the slot member  42  so when the diaper  20  is folded along the fastening centerline  120 , the tab member  42  and the slot  46  of the corresponding slot member  44  are generally aligned for at least partial insertion of the tab member  42  into the slot  46 . The fastening centerline  120  divides the diaper  20  into a leading part  122  having the tab members  42  and a trailing part  124  trailing the leading part  122  and having the slot members  44 . The fastening centerline  120  may or may not coincide with lateral centerline  110 . 
   The diaper  20  can be folded along the fastening centerline  120  into two opposing parts with the topsheet  22  facing inside of the folded article  20  ( FIG. 2 ) and with the respective tab members  44  and slot members  42  facing each other and properly aligned to form an engagement by inserting the tab member  44  through the slot  46  of the corresponding slot member  42  by a new process of the present invention. The new process can be provided by an apparatus  200 , one embodiment of which is shown in  FIG. 7  as a simplified, front elevation view.  FIG. 8  shows a fragmental, simplified side plan view of the apparatus  200  taken along arrow  8  of FIG.  7 . The new process is a dynamic process, meaning herein that the steps of the new process are performed when the apparatus  200  is in motion, preferably at a predetermined velocity, which can range from about 200 feet per minute to about 1,000 feet per minute. 
   Referring to  FIGS. 1 ,  7  and  8 , a web  202  preferably comprising a multiplicity of disposable absorbent articles  20 , can move along a predetermined path  204  at a predetermined velocity  206 . The web  202  can be generally flat under tension directed in the direction of the predetermined path  204 . The articles  20  can be oriented in relation to the predetermined path  204  such that the leading part  122  of the article  20  leads the trailing part  124  of the article  20 . The web  202  can be deposited onto a peripheral surface  208  of an anvil roll  210  of a rotary cutter  212  such that the inner surface  50  of the diaper  20  is facing the peripheral surface  208  of the anvil roll  210 . The web  202  can be held flat against the peripheral surface  208  by an anvil roll holding force  218 , which can be provided by any suitable means including mechanical clamps, belts, electrostatics, magnetism, vacuum and the like. In one embodiment of the present invention, the anvil roll holding force can be provided by vacuum communicating through openings in the peripheral surface  208  of the anvil roll  210 . The web  202 , held flat against the peripheral surface of the anvil roll  210 , can be cut into individual articles  20  by a cutter  214  rotating with a cutter roll  216  of the rotary cutter  212 . 
   After the cut, the individual articles  20  can continue to be held flat against the peripheral surface  208  of the anvil roll  210  by the anvil roll holding force  218  until the individual articles  20  can be transferred onto a peripheral surface  220  of a drum  222  disposed adjacent the anvil roll  210  and rotating in the direction of the predetermined path  204 . During the transfer, the anvil roll holding force  218  can be turned off and a drum holding force  224  turned on to hold the individual article  20 , now facing the peripheral surface  220  of the drum  222  with the outer surface  52  including the backsheet  24  of the article  20 . The drum holding force  224  can be provided by the same means as the anvil roll holding force  218  described herein above. In one embodiment of the present invention, the drum holding force  224  can be provided by vacuum communicating through the openings in the peripheral surface  220  of the drum  222 . Individual articles  20  can continue to be held flat by the drum  222  under tension directed in the direction of the predetermined path  204 . 
   In addition to the drum holding force  224 , the articles  20  can be held to the peripheral surface  220  of the drum  222  along a fastening centerline  120  of the article  20 , dividing the diaper  20  longitudinally equally between the tab member  44  and the slot member  42 , so when the diaper  20  is folded along the fastening centerline  120 , the tab member  42  and the slot  46  of the corresponding slot member  44  are generally aligned for at least partial insertion of the tab member  42  into the slot  46 . The article  20  can be held along the fastening centerline  120  by any suitable means including a single continuous clamp or two or more separate clamps disposed along the fastening centerline  120 . In one embodiment of the present invention, the article  20  can be held by two centerfold clamps  234  (see  FIG. 8 ) disposed along the fastening centerline  120  for attaching the article  20  along the fastening centerline  120  to the peripheral surface  220  of the drum  222 . The center-fold clamps  234  can be activated by any suitable means capable of attaching and detaching the article  20  along the fastening centerline  120 , including electro-mechanical, pneumatic, hydraulic, servomotors, cams and the like. 
   After depositing the article  20  onto the drum  222 , the slots  46  of the slot members  44  of the article  20  can be located on the peripheral surface  220  of the rotating drum  222  at a target position  230  by any suitable mechanical device capable of engaging with the slots  46  and moving the slots  46  transversely to the predetermined path  204  into the target position  230 . The target position  230  is a position of the slot member  44  on the peripheral surface  220  of the drum  220  suitable for engaging with the corresponding tab members  42  of the article  20 . In one embodiment of the present invention shown in  FIGS. 8 and 9 , each slot  46  can be positioned into the target position  230  by a slot locator  232 . The slot locator  232  can be actuated by any suitable means, including electro-mechanical, pneumatic, hydraulic, servomotors, and the like. In one embodiment of the present invention shown in  FIG. 9 , the slot locator  232  can be actuated by a cam (not shown) engaging a cam follower  235  attached to the slot locator  232 . 
   The apparatus  200  of the present invention can further include a peel-off roll  250  disposed adjacent the drum  222 , preferably at a 6 o&#39;clock position of the drum  222 , for separating the leading part  122  of the article  20  from the peripheral surface  220  of the drum  222  and transferring the leading part  122  of the article  20  onto the peripheral surface  252  of the peel-off roll  250 . Prior to this, the leading part  122  can be separated from the peripheral surface  220  of the drum  222  by deactivating the drum holding force  224  under the leading part  122  of the article  20  and activating a drum separating force  236  under the leading part  122  of the article  20 . The drum separating force  236  can be provided by any suitable means including mechanical, electrostatic, magnetic and the like. In one embodiment of the present invention, the drum separating force  236  can be provided by compressed air vented though the holes in the peripheral surface  220  of the drum  222 . 
   After the leading part  122  is separated from the drum  222 , the leading part  122  can be transferred onto and held against a peripheral surface  252  of the peel-off roll  250  by means of a peel-off roll holding force  254 . The peel-off roll holding force  254  can be provided by the same means as the anvil roll holding force  218  described herein above. In one embodiment of the present invention, the peel-off roll holding force  254  can be provided by vacuum communicating through the openings in the peripheral surface  252  of the peel-off roll  250 . 
   After the leading part  122 , is transferred onto the peel-off roll  250 , the peel-off roll holding force  254  can be substituted by a peel-off roll separating force  256 , similar to the drum separating force  236 , described herein above. The peel-off roll separating force  256  can separate the leading part  122  from the peel-off roll  250 , and a centrifugal force, resulting from the rotation of the drum  222 , can extend the leading part  122  radially from the peripheral surface  220  of the drum  222 . (See  FIG. 10. ) 
   Next, referring to  FIG. 11 , under continuing rotation of the drum  222 , the leading part  222  extending from the peripheral surface  220  of the drum  222  can move into contact with a stationary folding board  238  situated along the predetermined path  204  to form a bi-fold configuration  21  of the diaper  20 , wherein the article  20  is folded longitudinally. During the move into contact of the leading part  122  with the folding board  238 , each tab member  42  of the leading part  122  folds at least partially around the folding board  238 , preferably around a longitudinal edge  240  of the folding board  238 . Further, referring to  FIG. 12 , under continuing rotation of the drum  222 , the tab member  42  can pass between the longitudinal edge  240  and a stationary guiding rail  242  disposed adjacent the longitudinal edge  240  and extending along the predetermined path  204 . 
   Further, under continuing rotation of the drum  222 , the tab member  42  being passed between the longitudinal edge  240  of the folding board  238  and the guiding rail  242 , can be guided by the longitudinal edge  240  of the folding board  238  and the guiding rail  242  to align the tab member  242  with the slot  46  as shown in  FIGS. 13 and 14 , where  FIG. 14  is a cross-sectional view taken along lines  14 — 14  of FIG.  13 . (As described herein above, the slot  46  has been aligned and held in the target position by the slot locator  132 .) 
   Further, as shown in  FIGS. 15 and 16 , under continuing rotation of the drum  222 , the tab member  42  can be further guided by the longitudinal edge  240  of the folding board  238  and the guiding rail  242  to insert at least a portion  47  (see  FIG. 17  showing a cross-sectional view taken along lines  17 — 17  of  FIG. 16 ) of the tab member  42  through the slot  46  of the article  20  into an opening  244  in the peripheral surface  220  of the drum  222 .  FIG. 17  also shows the next step of attaching the portion  47  of the tab member  44  to the drum  222  by a clamp  246 . As the slot locator  232 , described herein above, the clamp  246  can be actuated by any suitable means, including electro-mechanical, pneumatic, hydraulic, servomotors, and the like. In one embodiment shown in  FIG. 17 , the clamp  246  can be actuated by a cam (not shown) engaging a cam follower  248  attached to the clamp  246 . 
   Further, while the portion  47  of the tab member  42  is clamped to the drum  222 , the article  20  can be partially lifted from the peripheral surface  220  of the drum  222  (as shown in  FIG. 18 ) by a conveyor  260 , or any other suitable device, after deactivating the center-fold clamps  234  releasing the article  20  along the fastening centerline  120 , and also after deactivating the drum holding force  224  releasing the trailing part  124  of the article  20  from the peripheral surface  220  of the drum  222 . While the portion  47  of the tab member  42  continues to be attached to the drum  222  by the clamp  246 , the article  20  can be lifted from the peripheral surface  220  of the drum  222 . By lifting the article  20 , the slot  46  of the slot member  44  of the article  20  can move in relation to the tab member  42  until the slot  46  passes beyond the lip portion  48  of the tab member  42 . In this configuration, the lip portion  48  of the tab member  42  will prevent the tab member  42  from slipping back through the slot  46  and disengaging the fastening system  40 . After completing the engagement, the tab member  42  can be released from the drum  222  by deactivating the clamp  246 , and the conveyor  260  can complete lifting the article  20  from the drum  222 . The lifted article  20  can now have a closed configuration  262  (see  FIG. 2 ) of the slot-and-tab fastener system  40  forming a pre-fastened article  20 . The conveyor  260  can then transport the pre-fastened article  20  to downstream process operations. 
   Alternatively to the embodiment  200  shown in  FIG. 7 , wherein the web  202  can be cut into individual articles  20  by the rotary cutter  212  prior to depositing the individual articles onto the peripheral surface  220  of the drum  222 ,  FIG. 19  shows another embodiment  300  of the present invention. In the embodiment  300 , the web  202  can be deposited onto and secured to the peripheral surface  220  of the drum  222  and then cut into individual articles  20  by any suitable cutting device, for example, a rotary cutter  310  cutting against the peripheral surface  220  of the drum  222 . The rest of the operations of the embodiment  300  can be the same as described herein above for the embodiment  200 . 
   While particular embodiments and/or individual features of the present invention have been illustrated and described, it would be 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. Further, it should be apparent that all combinations of such embodiments and features are possible and can result in preferred executions of the invention. Therefore, the appended claims are intended to cover all such changes and modifications that are within the scope of this invention.