Stacking machine and method

Abstract: A stacking machine (10) with a cutter (24, 28) having a nip between two rollers and a continuous first conveyor belt (38) against an under surface of a lower run (46) of which bundles of web material cut to length by the cutter are conveyed to a first or a second stacking station (18, 20). A second adjacent toothed conveyor belt (50) passing round toothed rollers (52, 54) has spaced clamp arms (58) connected thereto which move with the first conveyor belt and hold the bundles against the first conveyor belt until the bundles are restrained either by a retractable stop actuated by an air cylinder (124) at the first stacking station (18) or by a fixed stop (116) at the second stacking station (20) where they fall onto vertically displaceable vibrating plates (90) from which a stack of bundles is periodically displaced by fingers (104) extending through the plate onto an adjacent take-away conveyor equipped with pusher fingers (138).

Description: The invention relates to machines for cutting, conveying and stacking web material and related methods. Conventional stacking machines receive a continuous rope of web material, cut the rope into multiply bundles and stack the bundles. The stacks are discharged for subsequent processing. In a prior machine, disclosed in U.S. Patent No. 5,328,323 (on which the preambles of the independent claims are based), handling of the severed bundles is facilitated because the plies are wetted and cohere to each other. The cohesion holds folded piles on the top of the bundles down flat on the bundles as the severed bundles are moved from the cutting rolls downstream to a stacking station. However, this stacking machine is unsuitable for stacking bundles severed from multiply ropes formed of folded dry web material where the plies are not wetted and the top ply is not cohesively bonded to the lower plies and is susceptible to being blown up and then bent out of proper position on the bundle. Furthermore, each bundle is held against an upper surface of a centrally slotted plate by being held between a pair of feed belts running along either side of the slot and complimentary hold down belts. When each bundle reaches the stacking station, it has to be forced downwardly through the slot being bent in the process. The requirement for such bending renders the machine unsuitable for bundles of relatively stiff material. A further prior conveying machine is described in patent JP-A-63202554. The machine feeds a continuous sheet between two synchronised endless belts which have magnets and magnetic members incorporated thereinto for improving the gripping of the sheet. A still further prior art conveying machine is described in patent U.S. 4,566,360 in which an endless conveyor belt is pressed against material being conveyed by a spring loaded pressure device consisting of individual pressure pieces arranged in a row in the running direction of the conveyor belt. The invention provides an improved article stacking machine and method as set out in independent claims 1 and 9 respectively for continuously stacking articles, typically folded sheets or stacks of folded sheets, supplied to the machine. A cutter cuts a continuous rope to form the articles. The machine and method are particularly useful in high production rate continuous stacking of bundles severed from the lead end of an indefinite length multiply dry rope fed to the machine. The rope typically includes four or five stacked plies of folded dry web material, such as fabric softener sheets or paper towel sheets. The plies may be folded as desired. A Z-fold is typical. Bundles are stacked without fold back of the sheet edges. While the machine is particularly adapted to rapid production stacking of dry bundles, it may also be used to stack bundles which have been wetted. Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention, of which there are five sheets and one embodiment. In the drawings: Figure 1 is a plan view of the invention, partially broken away; Figure 2 is a vertical sectional view taken generally along line 2--2 of Figure 1; Figure 3 is a vertical sectional view taken generally along line 3--3 of figure 2; Figure 4 is a top view of a clamp arm; Figure 5 a sectional view taken along line 5--5 of Figure 4; Figure 6 is a sectional view taken generally along line 6--6 of Figure 2; Figure 7 is a sectional view taken along line 7--7 of Figure 6; and Figures 8, 9 and 10 are views illustrating gripping of the lead end of a multiply bundle. Stacking machine 10 includes a rectangular frame 12 supporting a cutter, a pair of bundle cutoff rolls 14, a bundle conveyor 16 extending downstream from the rolls 14, a pair of like drop-type stations 18 and 20 spaced along conveyor 16 and a stack takeaway conveyor 22 located to one side of bundle conveyor 16. Cutoff rolls 14 are of the type disclosed in U.S. Patent No. 5,363,728, assigned to Elsner Engineering Works, Inc. The cutter includes a knife roll 24 having three radially extending and circumferentially spaced cutoff knives 26 and an anvil roll 28 located below the knife roll and cooperative with the knife roll. Both rolls 24 and 28 are rotated by appropriate drives in the directions of arrows 30 shown in Figure 2 to sever the lead end of a flat multiply rope of folded web material. The rope is fed downstream in the direction of arrow 32 between the rolls, as shown in Figures 1 and 2. The end of the rope is cut into multiply segments or bundles which are discharged from the cutoff rolls and are fed downstream to the bundle conveyor 16 which moves the bundles to stacking stations 18 and 20. Conveyor 16 includes a pair of elongate horizontally extending vertical plates 34 and 36 extending in a downstream direction from rolls 14. Continuous flat conveyor belt 38 is wound around a pair of rollers 40 and 42. Roller 40 is located immediately downstream and slightly above the nip between cutoff rolls 14. A suitable drive rotates roller 40 in the direction of arrow 44 to move the lower run 46 of belt 38 in a downstream direction away from the cutoff rolls. Lower run 46 slides along a fixed elongate support plate 48 extending over and past stations 18 and 20. Endless toothed clamp conveyor belt 50 is wound around a pair of toothed rollers 52 and 54 as shown in Figures 1 and 2 and includes an upper run 56 extending between the rollers. Belt 50 and rollers 52 and 54 are offset to one side of belt 38, as illustrated best in Figure 1. A plurality of clamp arms 58 are mounted on belt 50 and extend from belt 50 toward and under belt 38. Each clamp arm 58 includes an elongate base 60 extended transversely across the outer surface of belt 38 and an arm extension 62 which projects from the base toward and under belt 38, as illustrated in Figure 3. The extension 62 is connected to base 60 by horizontal hinge connection 64 to permit upward pivoting of the extension toward the lower run 46 of belt 38. Tension spring 66 extends between supports extending above the base 60 and extension 62 to bias the extension upwardly about the hinge connection. Upward pivotal movement of the arm extension is limited by adjustable stop 68 on the base which engages an abutment 70 on extension 62 adjacent the hinge. See Figure 5. Mounting plate 72 is secured to the side of base 60 away from spring 66 with belt 50 sandwiched between the plate and the base. The plate includes a rib which fits within a groove on the side of the belt away from the base to accurately hold the clamp arm on the belt in a desired longitudinal position on the belt and with the base extending perpendicularly to the belt. Clamp element 74, which may be formed of relatively low friction nylon (RTM), is mounted on the free end of extension 62 on a pivot pin 76 which permits pivoting of the element about an axis extending parallel to the axis of hinge 64 and along the length of lower belt run 46. Free pivoting of the clamp element about pin 76 insures that the element is held flush against a bundle clamped between the member and belt 38, independent of the thickness of the bundle. A suitable drive continuously moves the upper run 56 of belt 50 downstream between rollers 52 and 54 at the same speed that the lower run 46 of belt 38 moves downstream from roller 40 to roller 42. The mounting plates 60 extend beyond the edges of clamp belt 50, as indicated in Figure 3, and are seated in opposed recesses 78 formed in the flanges of rollers 52 and 54 as the clamp arms are moved around the rollers. Positive engagement between the clamp arms and rollers supports the arms as they are brought up and into engagement with the under sides of lead ends of severed bundles to clamp the bundles against lower run 46 of belt 38, as illustrated more clearly in Figures 8-10 and described more fully below. The drive for belt 50 rotates roller 52 in the direction of arrow 80. As the clamp arms 58 are moved downstream from roller 52, the end of the base away from belt 38 is fed into a slot in longitudinal guide bar 82. At the same time the end of the base adjacent hinge 64 is brought into engagement on longitudinal support bar 84. Bars 82 and 84 extend along the length of the upper belt run 56. The bars 82 and 84 support arms 58 to insure bundles are properly clamped against the lower run of belt 38 during movement to the stacking stations 18 and 20. Each plate 72 has a close sliding fit between bars 82 and 84 to prevent longitudinal shifting of the clamp arms. Longitudinal shifting of the clamp elements could shift the plies in the multiply bundles and cause uneven stacks. As illustrated in Figure 2, roller 40 is located immediately downstream from the nip between knife roll 24 and anvil roll 28, and is located above driven roller 86. Plate 88 extends from the nip downstream past roller 86 and under the upstream end of run 46. Stacking stations 18 and 20 are spaced along bundle conveyor 6 under belt 38. Station 20 is located further downstream from rolls 14 than station 18 and includes a slotted stack support plate 90 movably mounted on a pair of vertical support rods 92 permitting vertical movement of the plate between full lowered and elevated positions indicated in Figure 3. Plate 90 is raised and lowered by a suitable drive, as will be described below. The upstream and downstream ends of the stacking stations are defined by adjustable upstream vertical guide plate 94 and downstream vertical guide plate 96. Plate 96 is mounted on frame 10 by eccentric vibrators 98 which vibrate or jog plate 96 for even stacking of bundles on the support plate. Stack shift comb 100 is mounted on a pair of parallel horizontal rods 102 and includes a number of spaced fingers 104 which extend upwardly through slots formed in the stack support plate 90. The comb is moveable along rods 102 and is connected to piston rod 108 of hydraulic cylinder 110 which, in turn, is mounted on frame 12. Cylinder 110 moves the fingers 104 from a retracted position where the fingers are located at the bottoms of the slots in plate 90, as shown in solid line in Figure 3, to an extended position where the fingers have been moved out of the slots in plate 90 and into slots formed in support plate 112 of takeaway conveyor 22. Ninety degree slotted guide plate 114 extends along the outer side of station 20 between plates 94 and 96 to assist in maintaining the orientation of the bundles during stacking. Plate 114 is slotted to permit movement of the fingers between the extended and retracted positions. Bundle support plate 95 extends upstream from the top of plate 94 under conveyor run 46 and includes a right angle upstream-extending portion of plate 94. The plate 95 supports trailing portions of bundles moved downstream by conveyor 16. The upstream end of plate 94 is located above plate 96 of stacking station 18. Station 18 is like station 20 and need not be described further. Plate 95 of station 18 extends upstream to roller 52, as illustrated in Figure 2. A pair of fixed stop or release fingers 116 associated with station 20 are mounted on a cross bar 118 extending between plates 34 and 36 and extend down from the bar to either side of the support plate 48 and clamp arm clamp members 74. The fingers 116 are located above vibrated end plate 96 at the downstream side of the stacking station. A pair of retractable stop fingers 120 are associated with station 18 are mounted on rotatable shaft 122 journaled in bearings in plates 34 and 36. An air cylinder 124 is mounted on a cross bar 126 extending between plates 34 and 36 and is connected to an end of radial arm 128 on shaft 122. Extension of cylinder 124 positions the stop fingers 120 to either side of the support plate 48, lower conveyor belt run 46 and clamp elements 74, as illustrated in Figure 6, where the ends of the stop fingers are in the path of downstream movement of the edges of product bundles clamped between elements 74 and lower conveyor run 46. See Figure 6. Retraction of cylinder 124 rotates and retracts the adjustable stop fingers 120 above the bottom of support plate 48, out of the path of downstream movement of the clamped bundles. Stack takeway conveyor 22 includes a pair of spaced apart sprocket gears 130, 132 and a drive chain 134 wound around the gears and having an upper run 136 located a short distance below plate 112. A plurality of spaced pusher fingers 138 are mounted at spaced intervals on chain 134. The fingers 138 on the upper run 136 extend upwardly through slot 140 in the plate and project above the plate to engage product stacks discharged from stacking stations 18 and 20 and onto plate 112 and move the stacks downstream to discharged belts 142 on takeaway conveyor extension 144. The operation of stacking machine 10 will now be described. The stacking machine operates continuously to sever successive bundles of folded web material from the lead end of a multiply rope fed in the direction of arrow 32 to cutoff rolls 14. The rope is fed downstream through the cutoff rolls 14 and onto plate 88. The downstream end of the rope 150 is fed between downstream rotating rolls 40 and 86 before the rope is severed to form a bundle. Belt 38 and roll 86 move downstream at a speed faster than the feed speed of the rope and the belt and roll slip on the top and bottom of the lead end of the rope until the bundle is severed, then engage the new bundle and accelerate the bundle away from the nip of cutter rolls 14. The severed bundle is then fed downstream between roll 86 and the conveyor belt 38 wrapped around the roll 40 at a speed greater than the speed at which the rope is fed downstream, creating gap 148 between the end of the rope and the bundle. The downstream fed bundle, confined between the conveyor belt 38, and plate 88 is fed past the end of plate 88 as shown in Figure 8. At this time a clamp arm 58 on belt 50 is rotated up around roller 52 and is raised up under belt run 46 and into contact with the downstream end of bundle 146 to positively clamp the lead end of the bundle against the downstream conveyor run 46, which, in turn, is supported by plate 48. Clamping occurs while the bundle is held between the belt and roller 86 and while the base of the clamp arm is positively supported in a notch 78 on roller 52 to increase the initial contact pressure between the clamp element 74 and the conveyor belt run 46. Positive clamping ensures that the bundle is held on the belt and moves downstream with the belt. Clamping occurs without longitudinal or lateral relative movement between belt run 46, bundle 146 and the clamp element 74. Gap 148 widens until the next bundle is severed from the rope. The lead ends of the rope and of bundles cut from the rope are positively held on the conveyor at all times prior to release at a stacking station, to insure proper feeding and to prevent fold back of the edges of the dry webs in the bundle. Rolls 40 and 86 are spaced a distance downstream from the nip of cutoff rolls 14 less the length of the bundle to insure that the bundle is captured prior to severing from the rope. Likewise, the position on conveyor 16 at which the lead end of the bundle is securely clamped against run 46 and plate 48 is located a distance downstream from rolls 40 and 86 less than the length of the bundle 146. The speed of conveyor 16 is greater than the speed at which rope 150 is fed to the cutoff rolls and insures a wide gap 148 between adjacent bundles so that bundles are dropped at stations 18 and 20 free of adjacent upstream bundles. After the lead end of a bundle has been firmly clamped between a clamp element 74 and the downstream moving run 46 the arm 58 is moved from notch 78 and downstream with run 46 to convey the clamped bundle downstream toward the stacking stations 18 and 20. A continuous stream of severed bundles are each clamped against run 46 and moved toward the stacking stations. Springs 66 hold the clamp elements up against the bundles. Clamped bundles 146 are moved downstream along conveyor 16 and are stripped from between the clamp arms and belt 38 at either stacking station 18 and 20, depending upon the position of adjustable stop fingers 120. Stripping of a bundle from between a clamped element 74 and lower conveyor run 46 occurs when the sides of the lead end of the bundle are brought into contact with a pair of stop fingers 116, 120 which are extended into the path of movement of the bundle. See, for instance, Figure 6. The clamped, moving bundle contacts and is stopped by the fingers. The lower conveyor run 46, and clamp element 74 on the arm 58 continue to move downstream past the stripped bundle. Stop fingers 116 and 120 are located above the downstream end plates 96 of stacking stations 20 and 18, respectively, so that stripped bundles fall down into the stations. When the fingers 120 are in the extended solid line position shown in Figures 6 and 7 the bundles are stripped from the arms and conveyor at stacking station 18 and are collected in a stack at station 18. When fingers 120 are retracted as shown in dashed lines in Figure 7 the bundles are conveyed downstream past station 18 to station 20 and are stripped from the arms and conveyor belt at station 20 by fixed stop figures 116 to be collected into a stack at station 20. Stacking machine 10 operates continuously feeding bundles 146 alternately to stations 18 and 20 to form bundle stacks 152 at each station and then discharge the stacks from the stations onto the takeaway conveyor 22 for discharge from the machine. During stacking a set number of successive bundles 146 are stripped from between the clamp arms and belt 38 at one of the stacking stations and fall down onto the station stack support plate 90. Before stacking begins, plate 90 is raised to an extended position illustrated in dashed lines in Figure 3, a short distance below lower belt run 46. The plate is automatically lowered as the stack height grows to maintain a constant drop distance for the bundles to insure uniform stacking. During stacking vibrators 98 are actuated to jog plates 96 and improve the quality of the stacks. The length of bundles 146 is slightly less than the spacing between end plates 94 and 96. Further, the width of the bundles is slightly less than the spacing between fingers 104 of comb 100, when retracted and guide plate 114. The geometries of the two stations 18 and 20 insure that the rectangular bundles fall down from conveyor 16 and are collected in a uniform stack 152 on descending support plate 90. After the proper number of bundles for making up full stack 152 have been collected at a first station 18, 20 cylinder 124 is actuated to either retract or extend arms 120 so that the bundle conveyor moves successive bundles to the other stacking station where the bundles are stripped from between the clamp arms and belt, fall down on raised plate 90 and form a second stack. At this time, the support plate at the first stacking station is fully lowered or has previously been lowered to the level of plate 112 of takeaway conveyor 22 as shown in Figure 3. Cylinder 110 for the station is then retracted to move the shift comb 100 from the extended solid line position to the retracted dashed line position shown in Figure 3 and shift the completed stack 152 from support plate 90 onto plate 112 between a pair of pusher fingers 138. The drive for takeaway conveyor chain 134 is then actuated to push the completed stack downstream along conveyor 22 and onto the takeaway belts 142 for subsequent operations, which conventionally include packaging of the stack. Cylinder 110 is then extended to retract the comb 100 and the plate drive is actuated to fully raise plate 90 and return the stacking station to position for receiving the first bundle of the next stack to be formed at the station. The drive for takeaway conveyor 22 is deactivated until another stack is placed on plate 112. Rope 150 may be formed from a number of plies of folded dry web material. These plies do not adhere to each other in the rope. The lead ends of the rope and of the bundles are confined during transfer from the cutting rolls to clamping on conveyor belt 38 in order to prevent displacement or fold back of the leaves or edges of the web material. Machine 10 operates at a high production rate and is capable of cutting and stacking as many as 480 to 600 21.6 cm (8.5 inch) long bundles per minute to form 16 to 20 full height stacks per minute. The bundles may have as many as six or more plies.

Claims: A stacking machine (10) of the type having a web cutter (24,28); a first article stacking station (18); a first endless conveyor belt (38) extending from the cutter (24, 28) to the stacking station (18); and a first drive (40) operable to move the first conveyor belt (38) downstream from the cutter (24, 28) to the stacking station (18); wherein a web fed downstream past the web cutter (24, 28) is cut into articles (146) which are fed downstream from the cutter (24, 28) to the stacking station (18) characterised in that the machine further comprises a plurality of spaced apart clamp members (58); and a second drive (50, 52, 54) including a second endless conveyor belt (50) located adjacent to and offset to one side of said first conveyor belt (38), said clamp members (58) being secured to said second conveyor belt (50) and positioned under the first conveyor belt (38), said second drive (50, 52, 54) being operable to move successive clamp members (58) up towards the first conveyor belt (38), and then move the clamp members (58) downstream with the first conveyor belt (38) to the stacking station (18) wherein the articles (146) fed downstream from the cutter (24, 28) are fed below the first conveyor belt (38) and the successive clamp members (58) engage and hold the articles (146) against the first conveyor belt (38) to convey the articles to the stacking station (18). A stacking machine according to claim 1 including springs (66) biasing the clamp members (58) toward the first conveyor belt (38). A stacking machine according to any preceding claim including an article support means (86, 88) located under the upstream end of the first conveyor belt (38). A stacking machine according to claim 3 wherein the article support element (86, 88) includes a driven roll (86) and a support plate (88) extending from the cutter (24, 28) to said driven roll (86). A stacking machine according to claim 4 wherein the cutter (24, 28) includes a two roll cutter and defines a nip, and said support plate (88) extends into the nip. A stacking machine according to any preceding claim wherein said first article stacking station (18) is located below the first conveyor belt (38) and includes a first stack support plate (90) and a first drive for moving the first stack support plate (90) towards and away from the first conveyor belt (38). A stacking machine according to claim 6 including a second article stacking station (20) located under said first conveyor belt (38) a greater distance away from the cutter (24, 28) than said first article stacking station (18), an article release member (116, 120) associated with each stacking station (18, 20) to disengage an article (146) from between a clamp member (58) and the first conveyor belt (38) at that stacking station, and a device (124) for deactivating the article release member (120) associated with the first stacking station (18); said second article stacking station (20) including a second stack support plate (90) and a second drive for moving the second stack support plate (90) towards and away from the first conveyor belt (38). A stacking machine according to claim 7 wherein each article release member (116, 120) is located in the path of downstream movement of an article (146) held between the first conveyor belt (38) and a clamp member (58), and said device (124) for deactivating the article release member (120) includes a drive (124) for selectively removing the article release member (120) associated with the first article stacking station (18) from the path of movement of the article (146). A method of forming stacks (152) of articles cut from a lead end of a web (150), including the steps of feeding the downstream end of the web (150) past a cutter (24, 28), cutting the web (150) to form successive downstream moving articles (146); moving the articles (146) downstream with a first endless conveyor belt (38) moving away from the cutter (24, 28) to a stacking station (18), releasing the articles (146) from the first conveyor belt (38) and collecting the articles (146) at the stacking station (18) to form a stack (152); characterised in that after passing the cutter each article passes under the first conveyor belt (38) and between the first conveyor belt (38) and a roller (86) which holds the downstream end of the article (146) against the first conveyor belt (38) and after the roller (86) spaced apart clamp members (58), secured to a second endless conveyor belt (50) located adjacent to and offset to one side of said first conveyor belt (38), are positioned against the articles (146) to clamp the articles (146) against the first conveyor belt (38) and the clamp members (58) and clamped articles (146) move together with the first conveyor belt (38) to the stacking station (18).

Inventors: MOLISON ROBERT E, MOLISON, ROBERT E.
Applicants: ELSNER ENG WORKS INC, ELSNER ENGINEERING WORKS INC
Application year: 1998
Main classification: B65H29
IPC codes: B65H33, B65H31, B65H29