Abstract:
Apparatus and methods are provided for folding discrete items such as diapers at high speeds. Discrete items are conveyed in a machine direction toward a pair of vacuum drums rotating in the machine direction and first carrying a top side of a leading edge of the discrete item away from the conveyor, and then carrying a bottom side of the leading edge with a second rotational vacuum drum back towards the conveyor. The diaper fold is created at a contact point with a folding finger which travels rotationally and straight in a fixed orientation about a pair of belts, into and out of contact with the diaper.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention disclosed herein relates to apparatus and methods for folding discrete pieces traveling on a production line. While the description provided relates to diaper manufacturing, the apparatus and method are easily adaptable to other applications. 
         [0002]    Generally, diapers comprise an absorbent insert or patch and a chassis, which, when the diaper is worn, supports the insert proximate a wearer&#39;s body. Additionally, diapers may include other various patches, such as tape tab patches, reusable fasteners and the like. The raw materials used in forming a representative insert are typically cellulose pulp, tissue paper, poly, nonwoven web, acquisition, and elastic, although application specific materials are sometimes utilized. Usually, most of the insert raw materials are provided in roll form, and unwound and applied in assembly line fashion. 
         [0003]    In the creation of a diaper, multiple roll-fed web processes are typically utilized. To create an absorbent insert, the cellulose pulp is unwound from the provided raw material roll and pulverized by a pulp mill. Discrete pulp cores are formed by a core forming assembly and placed on a continuous tissue web. Optionally, super-absorbent powder may be added to the pulp core. The tissue web is wrapped around the pulp core. The wrapped core is debulked by proceeding through a calendar unit, which at least partially compresses the core, thereby increasing its density and structural integrity. After debulking, the tissue-wrapped core is passed through a segregation or knife unit, where individual wrapped cores are cut. The cut cores are conveyed, at the proper pitch, or spacing, to a boundary compression unit. 
         [0004]    The diaper is built by sandwiching the formed core between a backsheet and a topsheet, and the combined web receives ears for securing the diaper about the waist of a baby. 
         [0005]    Most products require some longitudinal folding. It can be combined with elastic strands to make a cuff. It can be used to overwrap a stiff edge to soften the feel of the product. It can also be used to convert the final product into a smaller form to improve the packaging. 
         [0006]    Diapers are typically formed in a machine direction in a generally flat condition. Formed diapers require folding both longitudinally to tuck the ears and associated tape or hook applicators into the diaper, and also cross-folded generally at a crotch region to stack the diapers prior to packaging. 
         [0007]    The folded product is then passed downstream to a packaging machine where the diapers are stacked and packaged and shipped for sale. 
       SUMMARY OF THE INVENTION 
       [0008]    Provided are method and apparatus for minimizing waste and improving quality and production in web processing operations. 
         [0009]    Importantly, the methods taught in the present application are applicable not only to diapers and the like, but in any web based operation. The folding techniques taught herein can be directed any discrete component of a manufactured article, i.e., the methods taught herein are not product specific. For instance, the present methods can be applied as easily with respect to diaper components as they can for feminine hygiene products. 
         [0010]    Apparatus and methods are provided for folding discrete items such as diapers at high speeds. Discrete items are conveyed in a machine direction toward a pair of vacuum drums rotating in the machine direction and first carrying a top side of a leading edge of the discrete item away from the conveyor, and then carrying a bottom side of the leading edge with a second rotational vacuum drum back towards the conveyor. The diaper fold is created at a contact point with a folding finger which travels rotationally and straight in a fixed orientation about a pair of belts, into and out of contact with the diaper. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic of a representative web processing system; 
           [0012]      FIG. 2  is a side view of a folding system of the present invention; 
           [0013]      FIG. 3A  is a side view of a folding system of the present invention at a beginning point of a folding sequence, with an operator and a drive side folding finger advancement device hidden; 
           [0014]      FIG. 3B  is a top view of the operator and drive side blade advancement devices of the folding system, shown in sequence with  FIG. 4A ; 
           [0015]      FIGS. 4A and 4B , and likewise  FIGS. 5A and 5B  through  FIGS. 14A and 14B  are side views of the folding system of the present invention operating through an entire folding sequence, and the correlating top views of the operator and drive side blade advancement devices operating through an entire folding sequence. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    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. 
         [0017]    It is noted that the present folding techniques and apparatus are described herein with respect to products such as diapers, but as previously mentioned, can be applied to a wide variety of processes in which discrete components are applied sequentially. 
         [0018]    Referring to  FIG. 1 , a web processing operation starts with incorporating raw materials such as paper pulp and super absorbent polymer (SAP) in a pulp mill. The mixture is sent to a core forming drum, where cores are formed for retaining liquids. The core undergoes scarfing to trim the core to desired dimensions. 
         [0019]    The process continues through debulking, embossing, optionally core cutting and spacing, and optionally, compression. The core can be placed between a preformed cover sheet containing cuff elastics and an acquisition layer, and a backsheet layer, sandwiching the core. 
         [0020]    Ears are formed by applying a tape or hook and loop fastening mechanism to an ear web, and ears are die cut and spaced and spread as necessary, for instance as described in U.S. Pat. No. 8,016,972, incorporated herein by reference. The web can undergo folding, extraction and trimming of excess material, and application of material to tighten the diaper about the waist. Eventually, the product is folded and packaged. 
         [0021]    As seen on  FIG. 1 , the           symbol is shown at locations of introductions of discrete components into the process. At these locations, inspection can take place to determine the presence or absence of acceptable product introduction. In addition to visual inspection, operational characteristics such as startup/ramp-up/shutdown operations can trigger waste minimization techniques as will be described later. 
         [0022]    At each of these operations shown in  FIG. 1 , diagnostics can be performed to indicate whether the product meets acceptable criteria. If so, discrete elements, such as the core, tissue layers, elastic, etc., continue to be applied in a sequence such as shown in  FIG. 1 . If not, no additional discrete elements need be applied. 
         [0023]    The present invention is directed at the folding step in the position indicated on  FIG. 1 . The device used to perform the folding step is described and shown with reference to the following figures and description. 
         [0024]    Referring now to  FIG. 2 , a side view of a folding system  10  of the present invention is shown from an operator side of the folding system. An incoming web of material  12  to be folded enters a slip/cut anvil  14  and knife  16  combination to sever the web  12  into discrete pieces  18 . The incoming web of material  12  can have ear segments already folded over as described with reference to  FIG. 1 . 
         [0025]    After being severed into a single diaper (or other single discrete component)  18 , the diaper is conveyed by a bottom feed conveyor  20  to a combination of vacuum drums  22 ,  24  and  26  which control movement and initiate the folding as will be described later. A pair of rotating belt units  28  and  30  rotate folding fingers  36  not visible from this view. The folding fingers tuck the diaper to support the folded diaper and the folded diapers  18 ′ are passed downstream to stacking and packaging. 
         [0026]    Referring now to  FIG. 3A , a side view of the folding system  10  of the present invention at a beginning point of a folding sequence is shown. In this view for simplicity, the operator side rotating belt units  28  and  30 , and drive side rotating belt units  32  and  34  are not shown.  FIG. 3B  is top view of the operator and drive side blade advancement devices of the folding system, shown in sequence with  FIG. 3A .  FIGS. 3A and 3B , and likewise FIGS.  4 A and  4 B- FIGS. 14A and 14B  are side and top views respectively of the folding system of the present invention operating through an entire folding sequence of a single diaper  18 . This sequence is intended to be carried out repeatedly and continuously on a continuous stream of incoming discrete diapers  18 . 
         [0027]    Referring still to  FIG. 3A , a top feed conveyor  58  in conjunction with the bottom feed conveyor  20  transport diaper  18  from the anvil  16 /knife  14  combination of  FIG. 2 . The diaper is carried by a first vacuum drum  26  provided with vacuum ports  50  to transport the diaper  18 . A folding finger  36  can be seen approaching the laid out diaper between vacuum rolls  22  and  26 , and travels horizontally just above the top horizontal surface of conveyor  20 . For simplicity of illustration, a single folding finger  36  is shown in  FIG. 3A  and subsequent side views, but in a preferred embodiment, two folding fingers  36  will cooperate in tandem to assist in folding of diaper  18 . It is noted that a single folding finger  36  could be used in the folding operation, in this embodiment only one tandem of the operator side rotating belt units  28  and  30 , or drive side rotating belt units  32  and  34  would be necessary. 
         [0028]    Vacuum drum  26  operates clockwise as shown, and vacuum drum  22  operates counterclockwise as shown from an operator side view. The construction and operation of high speed vacuum ported drums  22 ,  24  and  26  can be constructed according to the vacuum porting design and principles described in U.S. Pat. No. 7,533,709, incorporated herein by reference. In summary of that teaching, the vacuum ported drums  22 ,  24  and  26  are generally cylindrical bodies connected to a source of vacuum. The drums have a diaper retaining portion on their outer surfaces in order to hold (when desired) and control the path of the diaper  18 . The diaper retaining portion is formed with a plurality of vacuum holes on the cylindrical surface. A vacuum slot (not shown) is provided on an end face surface (commutating surface) of the vacuum ported drums  22 ,  24  and  26  and is adapted to put the plurality of vacuum holes in communication with the vacuum source. In this manner, instantaneous on/off control of vacuum surface ports  50  can be achieved as described in U.S. Pat. No. 7,533,709. 
         [0029]    Referring now to  FIG. 3B , operator side rotating belt units  28  and  30 , and drive side rotating belt units  32  and  34  are shown. Each of operator side rotating belt units  28  and  30 , and drive side rotating belt units  32  and  34  the carry a belt  62 , and each is rotated for instance by a motor (not shown). In the view shown, in conjunction with  FIG. 3A , the operator side rotating belt units  28  and  30 , and drive side rotating belt units  32  and  34  rotate counterclockwise to advance folding fingers  36  around the travel path of the belt units, with the folding fingers oriented to point upward for the operator side rotating belt units  28  and  30 , and downward for drive side rotating belt units  32  and  34 . Operator side rotating belt units  28  and  30  cooperate to rotate one or more folding fingers  36  around the travel path of the belt units. Diaper  18  can be seen carried by conveyor  20  in an unfolded condition. 
         [0030]    Folding fingers  36  are pivotally mounted by pivotal mounts  52  attaching folding one or more folding fingers  36  to both the operator side rotating belt units  28  and  30 , and one or more folding fingers  36  to both drive side rotating belt units  32  and  34 . Because a folding finger is pivotally mounted at two points to two simultaneously rotating belts (be they operator side rotating belt units  28  and  30 , or drive side rotating belt units  32  and  34 ), during travel with the belts  62  the orientation of folding fingers  36  remains fixed pointing upward for folding fingers  36  carried by the operator side rotating belt units  28  and  30 , and fixed pointing downward for folding fingers  36  carried drive side rotating belt units  32  and  34 . The distance between the two belts  62  of the operator side rotating belt units  28  and  30  remains constant, and the distance between the two belts  62  of drive side rotating belt units  32  and  34  also remains constant. The operator side rotating belt units  28  and  30  are spaced apart from one another in a cross machine direction at a distance equal to the intended distance for cross-machine direction travel of folding fingers  36  during the folding sequence. The drive side rotating belt units  32  and  34  also are spaced apart from one another in a cross machine direction at a distance equal to the intended distance for cross-machine direction travel of folding fingers  36  during the folding sequence. 
         [0031]    Although four folding fingers  36  are shown carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34 , more or less can be used according to preference. As noted, a single folding finger  36  could be used in the folding operation to fold a single diaper  18 , but in a preferred embodiment as shown in  FIG. 3B , two folding fingers  36  each act on a single diaper  18 , each folding finger  36  extending nearly roughly to a centerline of the diaper  18  in the cross-machine direction. 
         [0032]    Referring to  FIGS. 4A and 4B  together as the folding sequence advances, a leading edge of discrete diaper  18  has been picked up by rotating vacuum drum  22  by vacuum ports  50  which are activated as previously described. 
         [0033]    As shown in  FIGS. 5A and 5B , rotating vacuum drum  22  has carried the leading edge of diaper  18  further away from rotating drum  26  and conveyor  20 , and folding finger  36  approaches a midsection of diaper  18 . The folding fingers  36  carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34  have advanced accordingly, at preferably about the same speed as the conveyor  20  carrying diaper  18 . 
         [0034]    Referring to  FIGS. 6A and 6B , folding finger  36  approaches closer to the midsection of diaper  18 , and is seen traveling above vacuum drum  26  and about to enter a notched portion  54  of the otherwise cylindrical vacuum drum  22 . The notched portion  54  is provided to allow passage of the folding finger  36  past the vacuum drum  22 . The folding fingers  36  carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34  have advanced accordingly, as shown on  FIG. 6B . 
         [0035]    Referring to  FIGS. 7A and 7B , folding finger  36  has entered notched portion  54  of the otherwise cylindrical vacuum drum  22  and contacted a midsection of diaper  18  to initiate a fold at the point of contact, while the leading edge of diaper  18  is still carried by rotating vacuum drum  22 . The folding fingers  36  carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34  have advanced accordingly, as shown on  FIG. 7B . 
         [0036]    Referring to  FIGS. 8A and 8B , folding finger  36  continues its horizontal path just above the top horizontal surface of conveyor  20  and maintains the midsection of diaper  18  on conveyor  20 . The folding fingers  36  carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34  have advanced accordingly, as shown on  FIG. 8B . 
         [0037]    Referring to  FIGS. 9A and 9B , vacuum ports  50  on drum  22  have been deactivated past a maximal counterclockwise downstream advance of leading edge of diaper  18 , and vacuum ports  50  on drum  24  rotating counterclockwise have been activated. Drum  24  engages what was previously an underside of diaper  18  but has now become a topside of diaper  18 . Drums  22  and  24  are closely spaced together at this point in the folding process to maintain control of diaper  18 . At points previous to this in the folding process, extended notch  56  creates a non-contacting surface area of drum  24  that has prevented drum  24  from contacting the diaper  18 , along drum  22  to carry diaper  18  counterclockwise without interference. The folding fingers  36  carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34  have advanced accordingly, as shown on  FIG. 9B . 
         [0038]    Referring to  FIGS. 10A and 10B , drum  24  rotating counterclockwise assists the leading portion of diaper  18  downwards during rotation back towards conveyor  20  to lay the leading half of the diaper over the trailing half of the diaper. The counterclockwise rotational velocity of the outermost perimeter of drum  24  is substantially equal to the speed of conveyor  20 , as well as substantially equal to the counterclockwise rotational velocity of the outermost perimeter of drum  22  to avoid shear forces on diaper  18  and to establish a controlled laydown of the leading half of folded diaper  18 . The folding fingers  36  carried by belts  62  of operator side rotating belt units  28  and  30  and drive side rotating belt units  32  and  34  have advanced accordingly, as shown on  FIG. 10B . 
         [0039]    The folding process continues in sequence through  FIGS. 11A and 11B , and  12 A and  12 B, until the fold is completed and the folded diaper  18  is completely folded and the top of diaper  18  is released from vacuum ports  50  of drum  24  as shown in  FIG. 13A . 
         [0040]    Referring now to  FIGS. 14A and 14B , folding fingers  36  round downstream corners of operator side rotating belt units  28  and  30 , and drive side rotating belt units  32  and  34  and are thereby withdrawn from the folded diaper  18  in the cross-machine direction, and free to travel along their counterclockwise path until rounding upstream corners of operator side rotating belt units  28  and  30 , and drive side rotating belt units  32  and  34  to return to the beginning of the folding process and start anew. Downstream conveyor  60 , along with conveyor  20 , carry the folded diaper  18 ′ downstream for further processing as desired, such as stacking and packaging. 
         [0041]    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.