Patent Publication Number: US-6712748-B2

Title: Method and apparatus for folding a web

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of the copending parent application U.S. Ser. No. 09/703,742 filed Nov. 1, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a method and an apparatus for folding a web. More particularly, this invention relates to a method and an apparatus for folding a web by use of a continuous twist belt. 
     BACKGROUND OF THE INVENTION 
     Conventional methods of making a longitudinal fold in a continuous web material generally employ stationary folding devices, such as rails or folding boards, and active folding devices, such as folding belts, which move with the web in the direction of the web to be folded. 
     Stationary folding devices, such as rails, are generally used for folding relatively stiff webs having both continuous and/or discontinuous longitudinal edges, and for folding soft, flexible webs having usually only continuous longitudinal edges. Other stationary folding devices, such as folding boards, are generally used for folding soft, flexible webs having usually only continuous longitudinal edges. 
     Active folding devices, such as folding belts, are generally used for folding both relatively rigid and soft, flexible webs having both continuous or discontinuous longitudinal edges. However, conventional belt folding devices do not work consistently well in folding relatively narrow longitudinal folds in soft, flexible webs. 
     One type of a conventional folding belt system  10  is illustrated in FIGS. 1-5, wherein the longitudinal axis of rotation  14  of the folding belt  12  is not parallel, (i.e., angled) to the fold line  24  of the web  18 . (The term “longitudinal axis of rotation” refers herein to an axis around which a folding belt rotates or twists during folding a web.) In one embodiment, as shown in FIG. 1, the web  18  is disposed to a conveyor belt  20  (or any suitable web-supporting device) and folded inward along the first longitudinal edge  22  of the web  18  creating the fold line  24  and the longitudinally folded flap  25  along the fold line  24 . The fold line  24  is substantially parallel to the longitudinal centerline  26  of the conveyor belt  20  and the machine direction  17 . (The term “longitudinal centerline” refers herein to a centerline which is equidistant between the opposing longitudinal edges of a belt. The term “machine direction” refers herein to the direction in which the materials being processed move.) The web  18  travels in the first or machine direction  17 , and the folding belt  12  travels in the second direction  19 , which is angled in relation to the machine direction  17 . Further, the longitudinal axis of rotation  14  of the folding belt  12  generally coincides with the longitudinal centerline  16  of the folding belt  12 . FIG. 2 illustrates an initial arrangement of the folding belt  12  at a zero rotation position of the folding belt  12  in relation to the conveyor belt  20  and the web material  18 , wherein the folding belt  12  is generally coplanar with the conveyor belt  20 . FIG. 3 illustrates an intermediate arrangement of the folding belt  12  between the zero rotation position of FIG. 2 and a 90-degree rotation position of FIG.  4 . FIG. 5 illustrates a final arrangement of the folding belt  12  in providing the longitudinally folded flap  25  along the fold line  24 . As seen in FIGS. 3-4, during rotation of the folding belt  12 , the first longitudinal edge  28  of the folding belt  12  loses its contact with the web  18  when the first longitudinal edge  28  rotates around the longitudinal axis of rotation  14  of the folding belt  12 , away from the web  18 . Furthermore, during this rotation, the web-contacting surface  29  of the folding belt  12  also moves away from the web  18 . This relative movement between the web-contacting surface  29  of the folding belt  12  and the web  18  may result in wrinkles in the folding flap  25  and/or in improper fold configurations of the folded flap  25 , especially when folding relatively narrow folds in soft, flexible webs. 
     Another type of a belt folding device is disclosed in U.S. Pat. No. 5,762,597, issued on Jun. 9, 1998 to Valterio. This device employs a folding belt supported by an under-belt track which forces the belt to rotate around an axis which is generally parallel to the machine direction and, thus, to the longitudinal fold line. However, the drawback of this device may be excessive wear of the folding belt and deteriorating quality of the fold due to a drag between the belt and the under-belt track. 
     Still another type of a belt folding device is disclosed in U.S. Pat. No. 4,795,416 issued on Jan. 3, 1989 to Cogswell et al. The device employs several folding belts disposed consecutively along the web path to fold the web in consecutive stages, wherein each folding belt rotates a portion of a total rotation required for providing a complete fold in a web. The shortcoming of this device may be a gap separating the sequential folding belts, especially, when folding discontinuous longitudinal edges in soft, flexible materials. The discontinuous edges may be caught in the gap and cause jams and/or inconsistency in quality of the folds. 
     Given the foregoing, there exists a continuing need in the art to provide a folding device for folding relatively narrow longitudinal fold(s), especially discontinuous, relatively narrow longitudinal folds(s) in soft, flexible webs. Further, it would be desirable to provide a folding device having a folding belt without the use of an under-belt track. Such needs are satisfied by the belt folder of the present invention. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a method is provided for making a longitudinal fold in a web moving in a machine direction. The method generally includes the following steps: (1) providing a web-supporting device having a web-contacting surface and first and second opposing longitudinal edges; (2) providing a simply-supported folding belt disposed adjacent to the first longitudinal edge of the web-supporting device, the simply-supported folding belt includes a first surface contacting the web, a first longitudinal edge and a second longitudinal edge opposed thereto, a width extending between the first and the second longitudinal edges, a longitudinal centerline, and a longitudinal axis of rotation which is generally parallel to the longitudinal centerline; (3) providing the web having a first and a second longitudinal edges opposed to each other, the web being superimposed onto the web-contacting surface of the web-supporting device such that the first longitudinal edge of the web extends laterally beyond the first longitudinal edge of the web-supporting device and at least partially onto the first surface of the simply-supported folding belt; and (4) folding the first longitudinal fold of the web by twisting the simply-supported folding belt around its longitudinal axis of rotation such that the first surface of the simply-supported folding belt rotates toward the first longitudinal edge of the web-supporting device to face at least partially the web-contacting surface of the web-supporting device, wherein the longitudinal axis of rotation of the simply-supported folding belt extends substantially parallel to a longitudinal fold line of the longitudinal fold of the web. Furthermore, the longitudinal axis of rotation of the simply-supported folding belt of the present invention may be offset a distance from the longitudinal centerline, wherein the offset distance is less than half of the width of the simply-supported folding belt or substantially equal to the half of the width of the simply-supported folding belt or greater than half of the width of the simply-supported folding belt. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified plan view from the top of a conventional embodiment utilizing a conveyor belt conveying a web and a folding belt to make a longitudinal fold in the web. 
     FIG. 2 is a cross-sectional view along cut line  2 — 2  of FIG.  1 . 
     FIG. 3 is a cross-sectional view along cut line  3 — 3  of FIG.  1 . 
     FIG. 4 is a cross-sectional view along cut line  4 — 4  of FIG.  1 . 
     FIG. 5 is a cross-sectional view along cut line  5 — 5  of FIG.  1 . 
     FIG. 6 is a simplified plan view from the top of one embodiment of the present invention utilizing a conveyor belt conveying a web and a simply-supported folding belt to make a longitudinal fold in the web. 
     FIG. 7 is a cross-sectional view along cut line  7 — 7  of FIG.  6 . 
     FIG. 8 is a cross-sectional view along cut line  8 — 8  of FIG.  6 . 
     FIG. 9 is a cross-sectional view along cut line  9 — 9  of FIG.  6 . 
     FIG. 10 is a cross-sectional view along cut line  10 — 10  of FIG.  6 . 
     FIG. 11 is a simplified plan view from the top of another embodiment of the present invention utilizing a conveyor belt conveying a web and a simply-supported folding belt to make a longitudinal fold in the web. 
     FIG. 12 is a cross-sectional view along cut line  12 — 12  of FIG.  11 . 
     FIG. 13 is a cross-sectional view along cut line  13 — 13  of FIG.  11 . 
     FIG. 14 is a cross-sectional view along cut line  14 — 14  of FIG.  11 . 
     FIG. 15 is a cross-sectional view along cut line  14 — 14  of FIG.  11 . 
     FIG. 16 is a graph illustrating tension profiles in folding belts of the present invention. 
     FIG. 17 is a plan view of one embodiment of a folding belt of the present invention in an unspliced form. 
     FIG. 18 is a side view of the folding belt shown in FIG. 17 after it has been spliced into a continuous belt. 
     FIG. 19 is a perspective view of another embodiment of a folding belt of the present invention. 
     FIG. 20 is a side view of a folding belt pulley used in the present invention. 
     FIG. 21 is a perspective view of the embodiment of the present invention shown in FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It will be readily apparent to those skilled in the art that the present invention may be useful for folding nearly any web, dry or wet, having sufficient structural integrity to be processed as a continuous web. Non-limiting examples of such webs may include non-woven substrates, plastic films, foams, tissues, rubbers, metal foils and other materials, either separately or in combination, and in single or multiple-layer forms. In particular, the present invention may be useful in production of disposable absorbent articles or any garment-like product, both disposable and non-disposable, manufactured by utilizing a web having continuous or discontinuous longitudinal edges, which need to be folded. 
     In the following description, a “web” is any web of material which is continuous in a machine direction and which may include components that are discontinuous or discrete in the machine direction. Further, the web may comprise a single or multiple layers of materials, attached or not attached to each other. The web may also comprise a plurality of interconnected disposable absorbent articles, such as diapers or feminine hygiene articles. As used herein, the term “absorbent article” refers to devices which absorb and contain body exudates, and more specifically, refers to devices which 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 an absorbent article, i.e., they are intended to be discarded after a single use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner. As used herein, the term “diaper” refers to an absorbent article generally worn by infants and other incontinent persons about the lower torso. The term “feminine protection device” refers to an absorbent article worn by women to absorb and contain menses and other vaginal exudates. The term “body wrap” refers to an article or a garment worn about the body, typically to provide some therapeutic benefit, such as, for example, pain relief, wound coverage or to hold another device or article near the body. As used herein, the term “garment” refers to an article of clothing, including undergarments such as disposable diapers, training pants, incontinence briefs, incontinence undergarments, absorbent inserts, diaper holders and liners, feminine protection devices, bandages, body wraps, bibs and the like. 
     FIGS. 6-10 illustrate the folding belt system  40  of the present invention having a simply-supported folding belt  46 . (The term “simply-supported folding belt” or “folding belt” refers hereinafter to a belt which extends between at least two opposing pulleys by wrapping at least partially around at least one of these pulleys, and which is not supported between these pulleys by an under-belt track directing the belt to rotate or twist between these pulleys.) In the system  40 , contrary to the conventional art shown in FIGS. 1-5, the longitudinal axis of rotation  42  of the folding belt  46  is substantially parallel to the fold line  24  of the web  18 . (The term “longitudinal axis of rotation” refers herein to an axis around which a folding belt rotates or twists during folding a longitudinal fold of a web.) Accordingly, contact between the folding belt  46  and the web  18  is maintained during the folding of the flap  25 . In the system  40 , the longitudinal axis of rotation  42  of the folding belt  46  generally coincides with the longitudinal centerline  44  of the folding belt  46 , which is substantially parallel to the machine direction  17 . (The term “longitudinal centerline” refers herein to a centerline which is equidistant between the opposing longitudinal edges of a belt.) 
     FIG. 7 illustrates an initial arrangement of the folding belt  46  at a zero rotation position of the folding belt  46  in relation to the conveyor belt  20  (or any other suitable web-supporting device). The folding belt  46  is preferably not coplanar with the conveyor belt  20 . In the initial position, as shown in FIG. 7, the folding belt  46  is disposed generally parallel to the conveyor belt  20 , however, the folding belt  46  need not be necessarily generally parallel to the conveyor belt  20 ; the folding belt  46  can be inclined in relation to the conveyor belt  20  as long as at least a portion of the folding belt  46  is subordinate to the conveyor belt  20 . For example, the initial position of the folding belt  46  can be any position intermediate to the position of FIG. 7 and a transitional position of FIG.  8 . FIGS. 9 and 10 illustrate, respectively, a 90-degree-rotation position and a final, about 180-degree-rotation position of the folding belt  46  in relation to the conveyor belt  20  and the web  18 . As seen from FIGS. 8-9, the folding belt  46  and the flap  25  both rotate around the coinciding axis  42  and fold line  24  and, therefore, there is no substantial relative movement between the web-contacting surface  50  of the folding belt  46  and the flap  25 . Thus, no drag is produced which may affect formation of wrinkles and/or irregularities in the shape of the folded flap  25 . 
     FIGS. 11-15 show an alternative embodiment of the present invention, wherein the folding belt system  60  includes the folding belt  66  having the longitudinal axis of rotation  62  substantially parallel to the longitudinal fold line  24  of the web  18 . However, in the system  60 , the longitudinal axis of rotation  62  does not coincide with the longitudinal centerline  64  of the folding belt  66 , but preferably generally coincides with the first longitudinal edge  68  of the folding belt  66 . FIG. 12 illustrates an initial arrangement of the folding belt  66  at a zero rotation position of the folding belt  66  in relation to the conveyor belt  20  (or any other suitable web-supporting device) and the web material  18 , wherein the folding belt  66  is generally coplanar with the conveyor belt  20 . FIGS. 13,  14  and  15  illustrate, respectively, an intermediate position, a 90-degree rotation position, and a final 180-degree position of rotation of the folding belt  66  in relation to the conveyor belt  20  and the web  18 . As seen from FIGS. 12-15, the folding belt  66  and the flap  25  both rotate around the axis  62  and, therefore, there is no substantial relative movement between the web-contacting surface  50  of the folding belt  66  and the flap  25 . Thus, again, no drag is created which may affect formation of wrinkles and/or irregularities in the shape of the folded flap  25 . 
     In order to provide rotation of the folding belt  66  in its longitudinal direction around an axis other than its longitudinal centerline  64  (as illustrated in FIGS.  11 - 15 ), the folding belt  66  may be subjected to a non-symmetrical tension profile across the width of the folding belt  66 . The term “non-symmetrical tension profile” across the belt width refers herein to a tension profile across the belt width which is not symmetrical in relation to a longitudinal centerline of the belt. The term “symmetrical tension profile” refers herein to a tension profile across the belt width which is symmetrical or has a mirror image in relation to a longitudinal centerline of the belt. The belts with symmetrical tension profiles across the belt width, when twisted by rotating the opposite ends of the belt in opposite directions, will generally twist about an axis of rotation which generally coincides with the longitudinal centerline of the belt. 
     Some examples of tension profiles to which a simply-supported folding belt may be subjected are shown in FIG. 16, wherein the vertical axis represents a tension in the cross-section of the belt and the horizontal axis represents the belt width  67  extending between the first longitudinal edge  68  and the second longitudinal edge  72 , and wherein the first longitudinal edge  68  is proximal to the longitudinal centerline  26  of the conveyor belt  20 . One example of a symmetrical tension profile in a twisted belt is illustrated by the function  80  which is symmetrically positioned in relation to the longitudinal centerline  42 . (However, any other shapes or configurations of symmetrical tension profiles in the folding belt of the present invention may be suitable.) 
     Examples of non-symmetrical tension profiles are illustrated by functions  82 ,  84  and  86  (see FIG.  16 ), each having the higher tension  100 ,  104  and  117 , respectively, at the first longitudinal edge  68  and the lower tension,  102 ,  106  and  119 , respectively, at the second longitudinal edge  72 . Furthermore, the function  82  illustrates a folding belt having both edges under positive tension values  100  and  102 , however, each of the functions  84  and  86  illustrates a folding belt having the positive tension value  104  and  117 , respectively, on the first longitudinal edge  68  and the negative tension values  106  and  119 , respectively, on the second longitudinal edge  72  extending below the zero-tension line  108 . Thus, each of the functions  84  and  86  represents a twisted belt, wherein the first longitudinal edge  68  is stretched under the positive tension  104  and  117 , and the second longitudinal edge  72  is compressed under the negative tension (i.e., compression)  106  and  119 . The function  82  provides the axis of rotation  43 , which is offset from the longitudinal centerline  24  at a distance less than half of the width  67  of the belt  66 . The function  84  provides the axis of rotation  62  which is offset from the longitudinal centerline  24  a distance substantially equal to the width  67  of the belt  66 . The function  86  provides an axis of rotation  65  which is offset from the longitudinal centerline  24  a distance greater than half of the width  67  of the belt  66 . (It should be noted, that any other shapes or configurations of non-symmetrical tensions profiles in a folding belt of the present invention may be suitable.) 
     Referring to FIG. 16, the function  84  is one preferred embodiment of a non-symmetrical tension profile for the folding belt  66  of the system  60  of the present invention, wherein the folding belt  66  rotates around its first longitudinal edge  68  which generally coincides with the longitudinal axis of rotation  64 . The function  84  intersects with the zero-tension line  108  at the point  110 . The point  110  projects on the horizontal axis forming the point  110 ′ which divides the width  67  of the folding belt  66  into the tension zone  112  and the compression zone  114 . The tension zone  112  and the compression zone  114 , respectively, define the tensile area  116  and the compressive area  118 , each of which is contained between the function  84  and the zero-function line  108 . In one preferred embodiment of the present invention, the tensile area  116  and the compressive area  118  are preferably substantially equal in order to provide rotation of the folding belt  66  around its longitudinal axis of rotation  64  generally coinciding with the first or shorter longitudinal edge  68  of the folding belt  66 . The tensile areas  116  and  118  represent the forces causing rotation of the simply-supported folding belt  66 . If the compressive area  118  is greater than the tensile area  116 , a resulting force, specifically, a lateral component of this force, may affect mistracking of the folding belt  66 . In contrast, if the tensile area  116  is greater than the compressive area  118 , then the resulting differential force may shift the axis of rotation  64  from the first longitudinal edge  68  inward toward the second longitudinal edge  72  of the folding belt  66 . 
     The non-symmetrical tension-profiles in a folding belt can be provided by one or more of the following factors: (1) by the belt geometry, wherein the opposing longitudinal edges of the belt are not equal in length in relaxed or untensioned state; (2) by the geometry of the opposing pulleys around which a simply-supported folding belt is wrapped during the rotation, wherein at least a portion of at least one of the opposing pulleys has a shape resembling a frustum of a cone; and (3) by the belt material properties, wherein the modulus of elasticity of the belt is varied along the belt width. However, it should be noted that the non-symmetrical tension profiles in a folding belt can be also provided by other factors. These factors may include cylindrical pulleys (with a crown or without the crown) disposed such that the cylindrical surface of the pulleys is inclined in relation to the surface of the belt to simulate the effect provided by the cone-shaped pulleys of the present invention. 
     The folding belt of the present invention may be constructed as a continuous belt by any known process, such as, for example, molding, casting, thermoforming, woven or non-woven processes and the like. Further, the folding belt of the present invention may have a first surface  70  and a second surface  71  which are separated from each other by a thickness  45  of the folding belt (see FIGS.  7  and  12 ). Alternatively, the folding belt of the present invention may be a mobius belt (i.e., when the belt is spliced after being twisted 180 degrees such that the first surface  70  continues from the second surface  71  as shown, for example, in FIG.  19 ). 
     The folding belt of the present invention can be fabricated from any material suitable to perform the desired function of providing a suitable web-supporting or web-contacting surface of the folding belt capable of folding a longitudinal edge of the web. The folding belt materials can include materials having very wide differences in various material properties, for example, tensile strength, elasticity, stretch, flexibility, surface properties and the like. Therefore, suitable folding belt materials may include various conventional belting materials, as well as non-conventional applications of certain materials as folding belts, for example, non-woven webs and the like. 
     In the folding belt system  60  shown in FIGS. 11-15, the non-symmetrical tension profile is provided by the geometry of the folding belt  66 , wherein the first longitudinal edge  68  is shorter then the second longitudinal edge  72 . One way to create the folding belt  66  is shown in FIG. 17, where the folding belt  66  is cut out from a sheet of the belt material  81  at the predetermined radius R, thus forming the curved strip of belt  82 . The strip  82  is then spliced into the continuous belt  66  shown in FIG. 18 in its relaxed or untensioned state, forming a frustum of a cone. It should be noted that other ways to provide a belt having unequal longitudinal edges may include a straight belt having at least one end of the belt cut and spliced at an angle, i.e. not perpendicular to the longitudinal edge of the belt. It also should be noted that the folding belt may be spliced by any suitable method known in the art. 
     Referring to FIG. 17, the radius R of the simply-supported folding belt  66  can be calculated by the following equation:        radius   =     width             length   2     +       (     flipangle   ·   width     )     2         length     -   1                       
     wherein 
     width is the width  120  of the folding belt  66  which is generally selected by the width of the folded flap, 
     length is the length between the two opposing idlers, around which the folding belt wraps, measured between the centers of rotation of the opposing idlers, 
     flipangle is the degree of rotation which the folding belt makes in providing a fold, for example, from the initial position of the folding belt  66  shown in FIG. 12 to the final position shown in FIG.  15 . 
     The tension profile in the folding belt  66  can be calculated by the following equation:        tension   =       ∫   0   width            [         elong   +   length           length   2     +       (     flipangle   ·   width     )     2           -   1     ]            E   M     ·        width                           
     wherein 
     elong is the difference in length between stretched and unstretched conditions of the shorter longitudinal edge of the folding belt (the first longitudinal edge  68  of the folding belt  66 ), 
     E M  is a modulus of elasticity of the folding belt material. 
     In one embodiment of the present invention the radius R of the folding belt  66  preferably ranges from about 500 mm to about 5,000 mm, and more preferably from about 800 mm to about 1,800 mm. The width  67  of the folding belt  66  preferably ranges from about 10 mm to about 150 mm, and more preferably from about 10 mm to about 40 mm. 
     In use, the folding belt  66  of the present invention wraps around pulleys defining a continuous path of the folding belt  66 . One embodiment of the pulleys of the present invention is represented by a pulley  200  shown in FIG.  20 . The pulley  200  is shaped preferably as a frustum of a cone having the smaller diameter  202 , the larger diameter  204 , and the width  206 . The diameters  202  and  204  and the width  206  could have any suitable dimensions. In a preferred embodiment of the present invention, the smaller diameter  202  is preferably about 50 mm, the larger diameter  204  is preferably about 50.6 mm, and the width  206  is preferably about 20 mm, which is generally equal to the width  67  of the folding belt  66 . Further, the pulley  200  also preferably includes chamfers or fillets  208  on both sides of the width  206  of the pulley  200 . In any case, the pulley  200  can be fabricated from any suitable material, for example, metals, plastics and the like. In one preferred embodiment of the present invention, the pulley  200  is fabricated from an anodized aluminum. 
     The folding belt system  60  of FIGS. 11-15 is also illustrated in a perspective view in FIG. 21, wherein folding belts  66  and  66 ′ fold both longitudinal folds of the web  18  carried by conveyor belts  20  and  20 ′. (It should be noted that the number of conveyor belts carrying the web can be any suitable number that ranges from a single belt to multiple belts.) The conveyor belts  20  and  20 ′ preferably include vacuum holes to provide accurate positioning of the fold line  24  of the web  18 . However, the web  18  may be held by any suitable means including but not limited to mechanical grippers, high coefficient friction areas, electrostatic charges, compressed air jets and/or combinations thereof. Similarly, if desired, the one or more folding belts  66  and  66 ′ may include any suitable web-holding means, for example, mechanical grippers, high coefficient friction areas, electrostatic charges, compressed air jets and/or any combination thereof. Each of the folding belts  66  and  66 ′ may have similar configuration, therefore, for simplicity of explanation, the invention will be described for a single folding belt  66  configuration. 
     Referring to FIG. 21, the folding belt  66  moves in a continuous path that includes the folding path  140  and the returning path  142 . The folding path  140  extends in the direction of the web path  154  from the starting folding position  190  to the finished folding position  192 . The starting folding position  190  coincides with the axis  180  of the first pulley  150 . The finished folding position  192  coincides with the axis  182  of the second pulley  152 . (These pulleys are illustrated in FIG. 20 as pulley  200 .) The first pulley  150  is disposed adjacent to the first longitudinal edge  172  of the conveyor belt  20  such that, in the starting folding position  190 , the web-contacting surface  160  of the conveyor belt  20  is generally coplanar with the web-contacting surface  70  of the folding belt  66 . The second pulley  152  is disposed such that the web-contacting surface  70  of the folding belt  66  faces the web-contacting surface  160  of the conveyor belt  20  and is separated by the gap  31  (see FIG. 15) which is generally equal to the combined thickness of the folded web  18 . Further, the second pulley  152  is disposed such that the first longitudinal edge  68  of the folding belt  66  remains substantially parallel to the first longitudinal edge  172  of the conveyor belt  20 . Further, the first pulley  150  and the second pulley  152  are disposed such that the larger diameter  204  (see FIG. 20) of the pulleys  150  and  152  is aligned with the shorter or first longitudinal edge  68  of the folding belt  66 . 
     The first and second pulleys  150  and  152 , respectively, are preferably separated along the web path  154  by a folding length  156 . The folding length  156  may be selected from a desired length-to-width ratio between the folding length  156  and the width  67  (see FIG. 17) of the folding belt  66 . The length-to-width ratio preferably ranges from about 3 to about 50, and more preferably from about 5 to about 20. In the folding belt system  60 , the length-to-width ratio is preferably about 18, the belt width  67  is preferably about 20 mm, and the folding length  156  is preferably about 360 mm. Further, along the folding length  156 , the folding belt  66  preferably rotates about 180 degrees at a rate of rotation of 0.5 degrees per mm. The term “rate of rotation” refers herein to a ratio between a degree of rotation or twisting of a folding belt extending between two opposing pulleys (around which the folding belt wraps) and a length between the axes of rotation of the two opposing pulleys. 
     As shown in FIG. 21, the axis  190  of the first pulley  150  of the folding belt  66  coincides with the axis  194  of the first pulley  196  of the conveyor belt  20 . However, it should be noted that the axis  190  need not necessary coincide with the axis  194 . 
     Referring to FIG. 21, the returning path  142  of the folding belt  66  can take any suitable configuration such that it does not disturb the required tension profile of the folding belt  66  in the folding path  140 . Because the tension profile of the folding belt  66  is generally dependent upon the rate of rotation of the folding belt  66 , it is preferred to maintain a substantially equal rate of rotation throughout the length of the folding belt  66 , which includes the returning path  142 . The returning path  142  can be defined by any suitable number of pulleys. In one preferred embodiment of the present invention shown in FIG. 21, there are three returning path pulleys  210 ,  212  and  214  defining the returning path  142 . The returning pulleys  210 ,  212  and  214  can have any suitable shape and dimensions, and can be manufactured from any suitable material. In one preferred embodiment of the present invention, the returning pulleys  210 ,  212  and  214  preferably have the same shape and dimensions as the pulleys  150  and  152  from the folding path  156 . Further, similarly to the pulleys  150  and  152 , the returning pulleys  210 ,  212  and  214  are disposed such that the larger diameter  204  (see FIG. 20) of the pulleys is aligned with the shorter or first longitudinal edge  68  of the folding belt  66 . 
     The simply-supported folding belt pulleys and the conveyor pulleys described herein may be arranged and rotatably supported within a suitable frame, and conventional drive mechanisms are operatively connected thereto employing ordinary techniques well known to a person skilled in the art. 
     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.