Patent Publication Number: US-6708855-B2

Title: Transverse folding apparatus

Description:
BACKGROUND AND SUMMARY OF INVENTION 
     This invention relates to an apparatus and method for the transverse folding of webs such as those made into wet wipes, napkins, hankies, or the like. Representative showings of the prior art can be seen in co-owned U.S. Pat. Nos. 1,566,079, 3,489,406, 3,498,600, 3,689,061, 3,870,292, 4,349,185, 4,625,957, 4,682,997, and 4,824,426, and other U.S. Pat. Nos. 5,211,320, 5,795,433, 5,904,277. 
     The process of producing stacks of transverse folded product usually requires vacuum rolls to hold, transfer, and fold the product. The prior art devices which used vacuum rolls were limited in speed as the vacuum had to be turned on and off at critical times. The vacuum systems are very expensive to manufacture, have very high maintenance costs and downtime, and are often limited in speed as the vacuum system plugs. When wet product is folded, wetting solutions are extracted from the web, which is undesirable and costly. The extracted solutions are difficult to recycle and increase waste. 
     The prior art vacuum and cutoff rolls were also limited in the products they could run. Cutoff sizes were set by the roll diameters, and running multiple cut lengths required significant change-over of parts and time. 
     It is desirable to provide a machine which can operate more products and cost less to operate with less waste. 
     U.S. Pat. No. 3,762,697 describes a folder for a web-fed rotary press. The folder includes folding blade cylinders which include tucking devices which travel in a hypocycloidal path as the cylinders rotate. 
     U.S. Pat. No. 4,190,242 also describes a tucking device which travels in a hypocycloidal path within a gripping-cylinder. The gripping cylinder includes pins for holding product on the cylinder. 
     U.S. Pat. No. 5,368,540 describes a hypocycloidal folding device which includes a folding cylinder which carries folding jaws which follow a hypocycloidal path. 
     The assignee of this invention has sold machines for folding wrapping paper and machines for folding diapers which utilized tuckers which travelled in a hypocycloidal path. However, such machines were not suitable for folding wet wipes and were set up for folding only one product length. The machines were not readily adjustable for folding products of varying lengths. 
     When the machine for folding wrapping paper was used for folding wet products, the wet produts, and even some dry non-woven products, would stick to the cutoff blades and not drop downwardly. The product also tended to stick to the vertical belts which conveyed the product to the tucker. The product would sometimes follow the belts into the tucking nip and would not be folded. 
     SUMMARY OF THE INVENTION 
     The invention provides a transverse folding apparatus which is particularly suitable for wet wipes and which eliminates vacuum rolls. The elimination of vacuum systems reduces costs and avoids the limitations of the prior art vacuum systems. 
     The apparatus uses a pinch cutoff to cut individual product to the desired length, a vertical belt feed system, a horizontal belt system, a hypocycloidal motion tucker for folding the product, and a stacker. The cutoff and anvil rolls include corrugated comb shells which pull the product off of the rolls. One of the sets of vertical belts extends beyond the tucker so that the leading end of the product was conveyed past the tucker. The tucker is notched so that it did not contact the belts. 
     The hypocycloidal tucker can be used with an infinite range of product lengths, and a variable speed cutoff system varies the product length as desired within a wide range of product sizes. 
    
    
     DESCRIPTION OF THE DRAWING 
     The invention will be explained in conjunction with illustrative embodiments shown in the accompanying drawing, in which 
     FIG. 1 is a side view of a transverse folding apparatus in accordance with the invention; 
     FIG. 2 is an enlarged fragmentary view of a portion of FIG. 1; 
     FIG. 3 is an enlarged side-view of the cutoff and anvil rolls; 
     FIG. 4 is a top plan view of the cutoff and anvil rolls; 
     FIGS. 4A through 4C are sectional views through comb shells on the cutoff and anvil rolls showing various spacings and positions of the ridges on the shells; 
     FIGS. 5A through 5I illustrate the cutoff cycle in 15° increments; 
     FIG. 6 illustrates the inside belt which travels both vertically and horizontally; 
     FIG. 7 is a fragmentary side view of FIG. 6; 
     FIG. 8 illustrates the vertical belts below the hypocycloidal tucker; 
     FIG. 9 is a side view of the hypocycloidal tucker; 
     FIGS. 10A through 10L illustrate the hypocycloidal movement of the tucker for initiating a transverse fold in a product; 
     FIGS. 11A through 11L illustrates the motions of the rotary arm and the tucker; 
     FIG. 12 is a fragmentary top plan view of the tucker and one set of vertical belts; 
     FIG. 13 is a view similar to FIG. 12 showing an alternative drive system for the tucker; and 
     FIG. 14 is a fragmentary view of an alternative timing belt. 
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENT 
     Referring to FIG. 1, a web W is fed to transverse folding apparatus  10  from an unwind stand  11 . The unwind stand rotatably supports a parent roll  12  of web material. The web material can be material suitable for producing wet wipes, napkins, hankies, or the like. The particular unwind stand illustrated includes a belt drive  13  for rotating the parent roll and unwinding the web. The unwind can be a single position unwind or a turret style or side shifting style which allows a new parent roll to be held in a standby position. 
     The folding apparatus includes a frame  15  which supports the components of the apparatus. The web W travels from the unwind through a slitter  16  upstream of the folding apparatus. The slitter slits the web into multiple webs of the desired width. For example, the web can be slit into four webs which are processed together. Other web widths and multiples of slits are possible. A driven bowed roll  17  spreads the web and reduces possible wrinkles prior to the slitter. 
     The slit webs are slightly separated by conventional web separation bars  18 . For example, the separation bars can align the slit webs on ten inch center to center spacing for processing throughout the rest of the machine. 
     A vector driven draw roll  20  controls the tension of the webs for folding. 
     If the folding apparatus is used for folding wet product, the slit webs are moistened or wetted with the correct amount of lotion or fluid by a wicking type wetting tube  21 . 
     A cutoff roll  23  and an anvil roll  24  are rotatably mounted on the frame  15  and are driven by a suitable drive, for example, a servo motor. In the embodiment illustrated three cutoff knives  25  (FIG. 3) are mounted on the cutoff roll and provide a flex pinch cut against pads  26  on the anvil roll. In one specific embodiment the three knives were spaced at 120° on a 9.5 inch surface pitch to provide a cut range of approximately 6 to 8.7 inches. Different diameter cutoff rolls can be used with one, two, three or more cutoff knives. 
     Referring again to FIG. 2, a feed roll  27  is mounted above the cutoff assembly and is mechanically driven from the cutoff rolls by a variable speed belt or by a separate motorized drive. The feed roll meters the proper amount of folded web from the folding plates  22  to be cut by the cutoff rolls. Feeding the folded web faster than the cutoff rolls produces longer product. Feeding the folded web slower than the cutoff rolls produces shorter product. 
     The webs enter the cutoff rolls vertically to aid the moistened webs in entrance and exit transfers. Downward vertical discharge from the cutoff rolls assists in advancing the web product with a gravity feed. Discharging wet limp product would be more difficult if the discharge was more toward horizontal. 
     In the preferred embodiment the feed roll  27  is speed changed to control product length, and vertical belts below the cutoff rolls run at the same speed as the cutoff roll. In an alternate method the vertical belts can run at the same speed as the feed roll. 
     The slit webs then travel through conventional folding plates  22  for making one or more longitudinal folds in each web. Typical folds for this type of machine include “C”, “Z”, and “V” folds, or variations of those basic styles. Other fold configurations may be provided with some possible alternations to the web path. 
     The cutoff roll  23  and anvil roll  24  are provided with comb shells  28  (FIGS. 3 and 4) which are retained on the rolls by screws  28   a . Each roll includes three curved shells. Each shell has a corrugated outer surface which is provided by radially outwardly extending ridges  28   b . The ridges on each of the cutoff roll and anvil roll are positioned facing the valleys  28   c  between adjacent ridges on the other roll. The tips of the extended ridges are inline with opposing tips in the preferred embodiment, i.e., the tips of both shells lie in the same plane as can be seen in FIG.  4 A. The tips may also be deeper and into the opposing valley (FIG.  4 B), and may be located closer to each other (FIG.  4 C). The preferred embodiment has the ridges spaced about 0.75 inch apart. Other spacings or shapes would also work. 
     As the product moves between the cutoff and anvil rolls, the corrugated comb shells grip and slightly squeeze the product. The corrugations pull the product off of the cutoff blades and anvils with a two-part force—one force slightly narrows the product and one force slightly lifts the product off of the blades and anvils so that the product moves vertically downwardly after being cut. FIGS. 5A-5I illustrate the vertical movement of the product through the nip between the cutoff roll and anvil roll in 15° increments of the rotation of the cutoff and anvil rolls. The corrugations also stiffen the product, which reduces wrinkling and cross direction skew, while also helping to hold the panels of the fold together and to deliver the product to the vertical belts. 
     Opposed sets of V-belts  29  and  30  transfer the cut-to-length folded web downwardly toward a cross folder assembly  31 . Each of the right and left sets  29  and  30  of V-belts includes a pair of V-belts for each lane of cut-to-length folded webs, for example, four lanes. The right and left V-belts grip each folded web inwardly of the side edges of the folded web. 
     The right hand set  29  of V-belts travels vertically downwardly from the cutoff rolls over five vertically spaced rollers  32 , past the cross folder assembly  31 , around a driven roller  33 , upwardly around a roller  34 , and back to the top roller  32 . 
     The left hand set  30  of the V-belts travels vertically downwardly over an upper change part roller  35 , over five idler rollers  36 , and over a bottom change part roller  37 . The belts turn to the left after the bottom roller  37 . The left V-belts then travel horizontally under four horizontally spaced rollers  44 , are diverted over two rollers  39  and  40 , travel horizontally over rollers  41  and  42 , upwardly over driven roller  43 , downwardly over pivotable roller  44 , and upwardly to the top roller  35 . 
     A 5.5 inch wide flat belt  46  travels horizontally below the horizontally spaced rollers  38 ,  41 , and  42  for each lane of product. The belts  46  travel horizontally between rollers  47  and  48  and downwardly over driven roller  49 . The width of each of the belts  46  is sufficient to extend across the width of the cut-to-length products. 
     A 5.5 inch wide flat belt  51  travels vertically below and in alignment with the vertical position of the left set of V-belts  30  for each lane of product. The belts  51  travel vertically downwardly between rollers  52  and  53  and upwardly over driven roller  54 . 
     Referring to FIGS. 6 and 7, the upper change part roller  35  rotates on a shaft  56  which is mounted in slots  57  in spaced-apart vertical belt frames  58 . The lower change part roller  37  is similarly mounted on a shaft  59  which is inserted in slots  60  in the belt frames  58 . Each of the change part rollers  35  and  37  is provided with a pair of grooves  61  for the two V-belts which engage each lane of product. The idler rollers  36  are mounted on shafts  62  which are supported by the frames  58 . Each idler roller engages a single V-belt. 
     The change part rollers  35  and  37  are retained in the slots  57  and  60  in the frames by the tension of the V-belts  30 . Tension on the belts is controlled by pivoting roller  44 , which is mounted on an arm  63  which pivots about pivot axis  64 . When the product width is changed, the belts  30  are loosened by pivoting the roller  44  upwardly so that the change part rollers  35  and  37  can be removed from the frames and replaced by change part rollers which have a different spacing between the grooves  61 . The idler rollers  36  are slidably mounted on the shafts  62  and are moved into alignment with the grooves  61 . The pivoting roller  44  is then pivoted downwardly to tighten the belts  30  around the change part rollers  35  and  37  and the idler rollers  36 . 
     Referring to FIGS. 8,  9 , and  12 , the cross folder or tucker assembly  31  includes a pair of rotary arms  66  which are mounted on a rotary shaft  67 . The shaft  67  is rotatably mounted on the frame  15  and is driven by motor  68  (FIG.  12 ), which may be a servo, and a belt  69 . 
     Alternatively, as illustrated in FIG. 13, the rotary shaft  67  can be mechanically driven by the cutoff rolls  23  and  24  through belts  70  and  71  and a phaser  72 . The phaser is used to adjust the movement of the tucker assembly so that the tucker assembly engages the desired portion of the product which is to be folded. 
     A rotatable pulley  73  is rotatably mounted on the left end of the rotary arms  66  and carries a flat tucker blade  74 . A fixed timing pulley  75  is ensleeved over the rotary shaft  67  but does not rotate with the shaft. A rotatable pulley  76  is mounted on the right end of the rotary arms  66 . A timing belt  77  extends around the pulleys  73 ,  75 , and  76 . 
     As the rotary shaft rotates, the rotary arms  66  and the pulley  73  orbit around the fixed timing pulley  75 . The tip of the tucker blade then traces a hypocycloidal path indicated by the three peaks  78 ,  79 , and  80  in FIGS. 2 and 8. 
     In one specific embodiment the drive ratio of the fixed pulley  75  to the orbiting pulley  69  was 3:1 and the blade to pivot ratio was 2:1. Other ratios will also work. The distance from the tip of the tucker blade to its pivot was 1.625 inches, and the radius of the orbit arm was 3.25 inches. These ratios work well with web speeds in excess of 500 feet per minute. Other sizes would also work with the same ratio. 
     The right and left V-belts  29  and  30  transfer the cut-to-length products downwardly from the cutoff rolls to the hypocycloidal tucker assembly  31 . The belts grip each product inwardly of the side edges to provide clearance for horizontal belts which will be described hereinafter. The tucker blade  70  is provided with notches  81  (FIG. 12) along the length thereof to provide clearance for the V-belts, two belts for each lane of product. 
     Referring to FIG. 8 and 10A, the leading end  82  of each cut-to-length product  83  is conveyed by the belts  29 ,  30  and  51  past the horizontal plane  84  through the axis of the rotary shaft  62  of the tucker assembly and past the nip between the belts  30  and  46  which travel over rollers  37  and  47 . The downwardly extending V-belts  29  ensure that the leading end of the product moves past the tucker position. This controls the crossfold registration. If the V-belts  29  did not extend past the tucker position, some products, particularly wet products, might turn left at the tucker position and enter the nip between belts  30  and  46 . 
     FIG. 10A illustrates the position of the product  83  and the tucker blade  74  just prior to the tucker blade contacting the product. As the rotary arms  66  of the tucker assembly continue to rotate counterclockwise, the tucker blade  74  engages the product and pushes the product into the nip between the belts  30  and  46  (FIGS.  10 B- 10 F). 
     In the embodiment illustrated, the tucker blade  74  contacts the center of the length of the product in order to fold the product in half. However, the tucker can be adjusted to make the fold in any desired location. The tucker can also be adjusted to engage the leading end of the product in order to change the product direction without folding the product. 
     The rotary tucker shaft  67  is rotated one revolution per product by the tucker drive. For a single product size this can be a mechanical drive in time with the cutoff rolls. For a totally automated process the tucker, the cutoff roll, and packer (to be described hereinafter) can be servo driven. When separately driven, the velocity of the rotary tucker shaft is controllable such that it can make one revolution for each product. The speed can be cycled faster or slower during periods of the revolution to allow. the tucker blade velocity to be near match to the web velocity in a perpendicular direction. The desirable velocity of the tip of the tucker blade would be about web speed at the point of contact, the tip velocity then decelerates at the end of the hypocycloidal motion. 
     The folded product is tucked into the horizontal belts  30 ,  46  at a match speed to the horizontal belt speed. This creates the transverse fold on the product. The tucker&#39;s flat blade tip follows a hypocycloidal path and moves the product from the vertical belt path into the horizontal belt nip. It then rapidly decelerates to a stop at the end of its path (FIG.  10 F), then moves back out and cycles around for the next product (FIGS.  10 F- 10 L). The tucker drive utilizes timing belts, but the drive could also be accomplished with gears. 
     Referring to FIG. 2, the folded product is advanced horizontally to the left by the belts  30  and  46  toward a creaser roll  88  and a backup roll  89 . A pad  90  is carried by the creaser roll and extends radially outwardly beyond the surface of the creaser roll. 
     The creaser roll is rotated by a suitable drive mechanism. For example, in FIG. 12 the creaser roll is driven by the rotary shaft  67  through belt  91 . The shaft  67  is driven by servo  68 . In FIG. 13 the creaser is also driven by the rotary shaft  67  through belt  91 , but the shaft  67  is mechanically driven by the cutoff rolls. The drive for the creaser roll is timed so that the pad  90  engages the leading edge of the fold and presses the leading edge against the backup roll  89 . Since the pad  90  engages only the leading edge of the folded product, the amount of fluid which is pressed out of wet product is limited, and into the center of the product. 
     The creaser roll  88  extends axially cross all of the lanes of product. The upper belt  34  is therefore diverted around the creaser roll by rollers  45  and  46  so that the belts do not engage the creaser roll. 
     The creased and folded product is transferred to horizontally extending upper and lower stacker infeed belts  96  and  97 . The stacker infeed belts lightly grip the outside edges of the product laterally outwardly of the upper V-belt  30 . The right end of the upper belt  96  can therefore travel around a roller which is axially aligned with the roller  42  for the belt  30 . The belt  96  also travels over rollers  98 ,  99 , and  100 . 
     The lower stacker infeed belt  97  travels around driven roller  102  and roller  103 ,  104 , and  105 . 
     The product is conveyed by the stacker infeed belts  96  and  97  to a stacker station which includes a conventional rotary packer  110 . The rotary packer makes one revolution per product. As the product reaches the stacker station, the rotary packer is moving downward. The packer makes contact with the folded and tucked product which is held by the horizontal belts  96  and  97  just as the product reaches the stacker station. The packer pushes the product from the belts onto a stack. The packer only needs to push the product through the belts, releasing it into the stack  112 . The distance of travel needs to be only about one inch, or just enough to release the product from the belts  96  and  97 . A servo controls the count in the stack by driving count fingers  114  in between stacks. An elevator  116  lowers the full stack to a table  118 , and a pneumatic pusher  120  or servo driven belt moves the stack onto a collator conveyor belt  122 . 
     The folding apparatus can provide a wide range of cutoff lengths by using a cutoff roll  23  with one, two, three, or more cutoff knives  25 . For example, a two-time cutoff roll can provide a 9 to 13 inch cutoff range. A one-time cutoff roll can provide an 18 to 26 inch cutoff range. 
     The tucker assembly, which rotates three revolutions for every revolution of cutoff, would also be adjusted to make one tuck for each product. The stacker would also be modified for the longer products by adjusting the packer length, stop, count fingers, elevator, and pusher stroke. For any type of cutoff roll the apparatus can provide infinite adjustment of the cut length by rotating the cutoff rolls  24  and  26  faster or slower than web speed. The speed of the tucker will also be changed so that the product is tucked at the desired location. 
     It is possible to incorporate additional tucker stations to provide additional folds such as “C”, “Z”, “W”, or combinations thereof. 
     FIG. 14 illustrates a modified timing belt  124  which can be used instead of the V-belts. A timing belt can be wrapped around each of the cutoff roll and anvil roll to carry the product vertically downwardly from the cutoff roll. Each belt is provided with notches  125  for the cutoff blades and notches  126  for the hypocycloidal tucker blade. The timing belt also eliminates the need for the comb shells  28  and  29 . 
     Alternatively, a timing belt  124  could be used with only one of the cutoff and anvil rolls, and V-belts could be used below the other roll as previously described. 
     When the folding apparatus is started, the tucker assembly can be disengaged, for example, by disengaging a clutch for the drive to the rotary shaft  67 . The scrap or cull products which are cut by the cutoff rolls  23  and  24  are then conveyed downwardly by the belts  29 ,  30 , and  51  past the tucker assembly where they can be discharged from the folding apparatus. 
     While in the foregoing specification a detailed description of specific embodiments were set forth for the purpose of illustration, it will be understood that many of the details hereingiven may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.