GB2212145A - Zig-zag stacking of paper webs - Google Patents

Description

1.

2 2 12 14 E) =, HOD OF AND APPARATUS FOR STACKING INTEBS OF PAPER OR THE LIKE IN ZIG- ZAG FORMATIONS The invention relates to methods of and apparatus for manipulating webs which consist of paper or a like material and wherein successive panels are connected to each other by weakened portions which can be formed by providing the webs with rows of transversely extending perforations, slots or the like. More particularly, the invention relates to improvements in a method of and apparatus for stacking panels of flexible webs in so-called zig-zag formations. Still more particularly, the invention relates to improvements in methods and apparatus of the type wherein, prior to stacking, successive pairs of panels each of a series of elongated webs are converted into loops.

Commonly owned U.S. Pat. No. 4,708,332 granted November 24, 1987 to Besemann discloses a method of and an apparatus for converting a continuous web of paper or the like into a successic of discrete stacks wherein the panels or sheets are folded over each other in zig-zaq formation. This is accomplished in that th continuous web is advanced to a stacking station where the panels are folded over each other in zig-zag formation. The web is severed between two neighboring panels when the stack has grown to full size (i.e., when the stack contains a desired number of superimposed panels). The separated stack is removed from the stacking station which then gathers the next stack. When fully grown, the next stack is separated from the nextfollowing panel, and so on. The step of repeatedly severing the web at the stacking station presents many problems regardless of whether the severing step is carried out by a sword or by tearing the web along the weakened portion which connects the topmost panel of a fully grown stack with the next-following panel of the continuous web.

In accordance with another prior proposal, a continuous web is subdivided into sections of predetermined length ahead of the stacking station, and such sections are delivered to the stacking station in the form of a row of immediately adjacent successive sections. The subdividing step includes tearing the 2.

continuous web along lines of perforations between successive sections or mechanically severing the web between successive sections. Such mode of converting a continuous web into a series of discrete sections ahead of the stacking station is acceptable in connection with certain types of zig-zag foldinc operations but not when the zig-zag folding is preceded by conversion of successive pairs of panels into loops in a manne and for the purposes as set forth in the patent to Besemann. The reason is that the making of discrete stacks as a result c folding of panels in successive sections of a severed web is not possible if the trailing end of a preceding section is immediately or closely adjacent the leader of the next-followi section.

-- A method of and an apparatus for severing fully grown stacks of sheets or panels in zig-zag formation from growing stacks of such sheets or panels is disclosed in commonly owned copending patent application Serial No. 110,289 filed October 1987 by Schlottke et al.

i 1 i 1 P i 1 1 1 i J i i One feature of the present invention resides in the provision of a method of zig-zag folding and stacking a row of closely adjacent successive discrete webs which consist of paper or a like flexible material and have panels connected to each other by transversely extending weakened zones and wherein successive pairs of panels form loops. The method includes the steps of transporting successive webs of the row in a predetermined direction along a predetermined path at a predetermined speed, and temporarily decelerating first loops of successive webs in apredetermined portion of the path so that the trailing end of the web preceding the temporarily decelerated first loop moves away from the decelerated first loop and defines therewith a gap as a result of temporary deceleration of the first loop. The decelerating step embraces temporarily arresting the first loops of successive webs.

The method can further comprise the steps of transporting the loops following the decelerated loop at the predetermined speed, and folding the panels of such loops in zig-zag formation on top of the decelerated loop to thus form an incipient stack of overlapping panels. Such method further comprises the step of conveying the decelerated loop and the incipient stack on top of it upon completion of the decelerating step. The conveying step can include advancing the decelerated loop and the incipient stack on it along the predetermined path at the predetermined speed. Such conveying step involves advancing the decelerated loop and the incipient stack on top of it into a second portion of the predetermined path, and the advancing Step is followed by the step of depositing the panels of remaining loops of the web which advances into the second portion of the path in zig-zag formation on top of the incipient stack so as to convert the entire web into a stack of superimposed panels in zig-zag formation.

Another feature of the invention resides in the provision of an apparatus for stacking a row of closely adjacent successive 4.

discrete webs which consist of paper or a like flexible material and have panels connected to each other by transversely extendinc weakened zones and wherein successive pairs of panels form loops The apparatus comprises means for transporting successive webs of the row in a predetermined direction along a predetermined path at a predetermined speed, and means for temporarily decele---r rating first loops of successive webs in a predetermined portion of the predetermined path so that the trailing end of the web preceding the temporarily decelerated first loop moves away from the decelerated first loop and defines therewith a gap as a result of temporary deceleration of the first loop. The decelerating means caninclude means for merely slowing down or actually arresting the first loops of successive webs.

-- The transporting means can include an endless foraminous conveyor and means for establishing a pressure differential between opposite sides of the conveyor so that the loops are attracted to one side of the conveyor. The means for establishing a pressure differential can include a suction chamber at the other side of the conveyor.

The decelerating means can comprise tongs and means for moving the tongs along the predetermined path in and counter to the predetermined direction. Such moving means can comprise a carriage for the tongs and a track (e.g., a rail) for the carriage. The moving means further comprises means for reciprocating the carriage forwardly and backwards along the track. The reciprocating means can include means for pulling the carria. in and counter to the predetermined direction, a driven cam and means for transmitting motion from the cam to the pulling means. The motion transmitting means can comprise a lever which is operatively connected with the pulling means and has means for tracking the cam. The pulling means can comprise an endless chain.

The apparatus preferably further comprises means for deactivating (when necessary) the motion transmitting means, and the deactivating means can comprise means for disengaging 5.

the tracking means from the cam. The disengaging means can comprise a fluid-operated (e.g., pneumatic) motor.

The decelerating means further comprises means for opening and closing the tongs. To this end, the tongs can comprise a first jaw and a second jaw which is movable relative to the first jaw between open and closed positions. The means for opening and closing the tongs comprises means for moving the second jaw relative to the first jaw. The means for moving the second jaw comprisies a second rotary cam and means for displacing the second jaw relative to the first jaw in response to rotation of the second cam. The means for displacing the second jaw preferably comprises a mobile output member which is couDled to the second jaw, and means for transmitting motion between the second cam and the output member. The motion transmitting means can include a linkage which is coupled to the output member and has follower means serving to track the second cam.

The apparatus preferably further comprises means for deactivating the motion transmitting means, and such deactivatinmeans can comprise fluidoperated motor means for disengaging thE follower means from the second cam. Means is preferably provideC for jointly rotating the two cams.

The apparatus an also comprise means for braking the loops which follow the temporarily decelerated first loop. Such brakir means can include means for gathering the panels which form part of the loops following the decelerated loop into an incipient stack on top of-the decelerated loop. In accordance with a presently preferred embodiment, the braking means comiDrises a foraminous conveyor and means for attracting the loops to the conveyor. The attracting means can include a suction chamber which cooperates with the f oraminous conveyor. A portion of the suction chamber is adjacent the foraminous conveyor and has at least one suction port which draws air across the conveyor and into the suction chamber. Means is preferably provided for drivi: the foraminous conveyor at a speed less than the vredetermined speed. The attracting means is preferably adjacent the path X 6 p upstream of and adjacent the tongs in an end position of the tongs.

The apparatus further comprises means for stacking the panels of successive loops of successive weebs in zig-zag formation in a second portion of the path downstream of the predetermined portion. The stacking means includes means for laying the panels of loops following the at least one loop in zig-zag formation on top of the respective incipient stack. In accordance with a presently preferred embodiment, the stackina means comprises a first support (e.g., a table) which is disposed beneath the second portion of the path, means for moving the support between-a raised position in which the suiDport supports a growing stack in the second portion of the Dath and a lowered position in which a fully grown stack can be removed from the support, and a second support which is movable to and from a position beneath the second portion of the path to support an incipient stack while the first support is away from the raised position.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawina.

r i FIG. 2 FIG. 1, with FIG. 3 1 FIG. 1 is a somewhat schematic front elevational view of an apparatus which embodies the invention, with a portion of the transporting means broken away and with the means for pulling the tongs indicated by phantom lines; is an enlarged view of a detail in the apparatus of the tongs shown in the starting position; is a view similar to that of FIG. 2 but showing the tongs in open position; FIG. 4 is a view similar to that of FIG. 2 or 3 but showing the tongs in engagement with the front loop of a web, the tongs being remote from its starting position; and FIG. 5 illustrates the structure of FIG. 4 but with the tongs-in open position so that the incipient stack is free to advance toward the stacking station.

8.

Referring first to FIG. lt there is shown an apparatus which is used to convert a row of closely adjacent webs (including the webs 6a and 6b) into discrete stacks 61 of panels 91, 92 which overlap each other in zig- zag formation. Each web 6 can consist of so-called computer paper which is customarily furnished in the form of stacks containing coherent panels folded on top of each other in zig-zag formation. Neighboring panels 91, 92 are connected to each other by transversely extending weakened portions 90 which are normally formed by providing the webs with rows of perforations, slits or in any other suitable manner. -Pairs of neighboring panels 91, 92 form loops 2 which develop during travel of successive webs through a channel between two endless belt conveyors 3 and 4 shown in the left-hand portion of FIG. 1. The speed of the conveyor 3 deviates from that of the conveyor 4 in order to establish the necessary circumstances for the formation of loops 2. The conveyors 3, 4 form part of a looping unit 1 which is or can be identical with that disclosed in commonly owned U.S. Pat. No. 4,708,332 granted November 24, 1987 to Besemann for "Method and apparatus for zig-zag folding webs of paper and the like". The disclosure of this patent is incorporated herein by reference.

FIG. 1 shows schematically a web severing device 101 which precedes, includes or follows the looping unit 1 and serves to subdivide a continuous web of paper or the like into a succession of closely adjacent discrete webs including the illustrated webs 6a and 6b. The trailing end TE (FIG. 3) of each preceding web (6a) is immediately adjacent the leader (foremost panel 91) of the next-following web (6b) when such discrete webs are separated from each other, e.g., by tearing the respective weakened portion 90 or by resorting to a knife or a like cutting tool which actually severs the continuous web intermediate the webs 6a and 6b. As a rule, the web severing device 101 will be installed ahead of the looping unit 1.

The conveyors 3, 4 of the looping unit 1 define a first 0 portion of an elongated path 7 which is or which can be a horizontal path and a second portion of which is defined by the upper reach 9a of an endless belt conveyor 9 constituting a means for transporting the webs 6a, 6b longitudinally in the direction of arrow 8. The upper reach ga of the conveyor 9 transports the webs into the range of a device 16 which serves to temporarily decelerate (e.g., bring to a full stop) the front loops 2a of successive discrete webs 6a, 6b. This is necessary because proper stacking of panels 91, 92 which form a succession of loops 2 is difficult or plain impossible if the trailing end TE of a preceding web is not separated from the foremost loop 2a of the nex t-following web by a clearance or gap 1 having a minimum width (see FIG. 4). A relatively narrow clearance a is shown in FIG. 1 to the right of the decelerating device 16.

The belt conveyor 9 is a foraminous conveyor and its upper reach 9a advances along the perforated top wall of a stationary suction chamber 209 which serves to attract the webs 6a, 6b to the upper side of the upper reach 9a in order to ensure a highly predictable transport of webs along the path 7 toward and beyond the decelerating device 16. The conveyor 9 is trained over pulleys 11, 12, 13 at least one of which is driven (note. the motor 109 for the pulley 9) at as predetermined speed. It is preferred to employ a belt conveyor 9 which is assembled of a plurality of relatively narrow endless bands disposed in parallel vertical planes and being separated from each other by clearances of selected width. Each of the pulleys 9, 11, 12 is or can be common to all endless bands of the conveyor 9.

As already mentioned above, the decele:rating device 126 serves as a means for temporarily slowing down or for actually arresting the front loop 2a (i.e., the leader) of a nextfollowing web 6b while the trailing end TE of the preceding web 6a continues to advance at the speed which is selected by the motor 109 so that the width of the clearance or gap a increases from zero or nearly zero to a value which is acceptabler satisfactory and practical for further processing of the webs, namely for I 10.

conversion of each web into a discrete stack 61 of panels which overlap each other in zig-zag formation. Temporary deceleration (e.g., fullstoppage) of the front loop 2a of each trailing or next-following web further entails the formation of an incipient stack 14 as a result of forward movement of loops 2 following the loop 2a, i.e., as a result of folding of successive panels 91, 92, 91, 92... on top of each other in zig-zag formation while a tongs 17 of the decelerating device 16 actually engages the loop 2a in order to ensure a widening of the clearance or gap 2, to the desired optimum value. The gathering of panels 91, 92 into an incipient stack 14 wherein the panels are in zig-zag formation involves a folding of the web 6b along successive weakened portions 91.

The tongs 17 of the decelerating device 16 is movable back and forth along the path 7 in directions which are indicated by a double-headed arrow 18. To this end, the tongs 17 can comprise a plurality of sections disposed in neighboring vertical planes so that the sections can extend through the spaces between neighboring endless bands of the conveyor 9. The illustrated tongs 17 comprises a fixed (non-pivotable) jaw l7b and a movable (pivotable) jaw 17a. The jaw l7b is rigid with a carriage 19 forming part of the means for moving the tongs 17 along the path 7 in and counter to the direction of arrow 8. The carriage 19 is reciprocable along a guide or track 21 which is mounted in the frame (not shown) of the improved stacking apparatus. The means for reciprocating the carriage 19 along the track 21 comprises an endless chain conveyor 22 or analogous means for pulling the carriage in directions which are indicated by the double-headed arrow 18. This conveyor comprises an endless chain 22a which is trained over sprocket wheels 23, 24, 26f 27. The reciprocating means further comprises a driven rotary disc cam 32 and means for transmitting motion'from the cam 32 to the chain 22. Such motion transmitting means comprises a bell crank lever 29 which is fulcrumed in the frame of the stacking apparatus, as at 31, and has a longer arm 29a attached to the chain 22a by a coupling 1 i i I I 1 11.

element 28. The shorter arm 29b of the lever 29 is provided with a roller follower 33 serving to track the periphery of the cam 32.

Since the tongs 17 is used only at certain intervals, i.e., whenever the front loop 2a of a next-following web approaches the gap forming station, the apparatus further comprises means for deactivating the motion transmitting means 28, 29, 33 between the chain 22a of the conveyor 22 and the cam 32, i.e., for interrupting the connection between the shaft 49 of the continuously driven cam 32 and the carriage 19 for the tongs 17.

The apparatus further comprises means for opening and closing the tongs 17-, namely for pivoting the mobile jaw 17a with reference to the fixed jaw 17b between an open position which is shown in FIGS. 3 and 5, and a closed position shown in FIGS. 1, 2 and 4. The means for opening and closing the tongs 17 comprises a coupling element 36 which is articulately connected to the jaw 17a as well as (at 37) to an elongated rod- or bar-shaped output member 38 of the means 39 for actually displacing the jaw 17a relative to the jaw 17b. The output member 38 is movable up and down to thereby pivot the jaw 17a relative to the jaw 17b. Reference may be had to commonly owned U.S. Pat. No. 4,334,608 granted June 15, 1982 to Fabrig for "Apparatus for transporting stacks of paper sheets or the like". The disclosure of this patent is incorporated herein by reference.

The displacing means 39 for the jaw 17a further comprises a four-bar linkage 39a, 39b, 39c, 39d, 39e and two links 41, 42 which cause the bars 39al 39e to pivot relative to the adjacent bars 39b, 39d in response to pivoting of a two-armed lever 44. This lever is fulcrumed in the frame at 43 and its longer arm carries a roller follower 46 which tracks the periphery of a second disc cam 47 on the shaft 49 for the cam 32. The longer arm of the lever 44 is further articulately connected to the link 42. The shorter arm of the lever 44 is articulately connected to the piston rod of a fluid-operated cylinder and piston unit (preferably a pneumatic unit) 48 serving as a means 12.

or temporarily disengaging the follower 46 from the cam 47 to thus maintain the pivotable jaw 17a of the tongs 17 in open or closed position. The common shaft 49 for the cams 32 and 47 receives torque from the main prime mover (not shown) of the machine which embodies the improved stacking apparatus.

In order to prevent the loops 2 which follow the temporarily decelerated loop 2a from being propelled beyond the loop 2ar i.e., from advancing beyond the locus of the incipient stack 14f the apparatus further comprises means for braking the loops 2 behind the loop 2a. Such braking means is shown in detail in FIGS.1 and 4 and comprises an endless foraminous belt conveyor_.54 trained-over pulleys 56r 57j, 58 at least one (see the pulley 58 in FIG. 4) is driven by a suitable electric or other motor-1 54 at a speed such that the speed of the conveyor 9 exceeds the speed of the conveyor 54. The braking means further comprises a stationary suction chamber 51 which is installed beneath the upper reach of the foraminous conveyor 54 and has a portion adjacent such lower reach and provided with at least one suction port 52 cooperating with openings or ports 53 in the upper reach of the conveyor 54 to slow down the loops 2 which follow a decelerated loop 2a in order to ensure a highly predictable formation of incipient stacks 14. The suction chambe 51 is located upstream of and close to the tongs 17 when the latter assumes the end position of FIG. 41 namely the position in which the jaws 17a, l7b of the tongs cooperate to hold the first loop 2a of the web 6b. Streamlets of air which flow downwardly into the openings 53 in the upper reach of the conveyor 54 and thence into the port or opening 52 of the suction chamber 51 produce a highly satisfactory braking or retarding action to thus ensure that the loops 2 following the decelerated loop 2a cannot be propelled beyond the optimum location of the incipient stack 14.

When the gap a reaches the desired widthr the jaws 17a, l7b of the tongs 17 release the foremost loop 2a (i.e., the lowermost panels 91, 92 of the incipient stack 14) so that the i 1 i 1 i i i 13.

stack 14 can advance at the speed of the conveyor 9 on toward and into a stackig station 59 in a further portion of the path 7. The station 59 comprises means for completing the conversion of the web 6b into a fully grown stack 61 which is then removed from the station 59 so as to provide room for the next incipient stack 14. The stacking mechanism at the station 59 can be similar to or identical with that described in commonly owned United States patent application Serial No. 195,075 filed May 17, 1988 by Peter et al. for "Apparatus for forming stacks of panels in zigzag formation". The disclosure of this application is incorporated herein by reference. Another apparatus is disclosed in commonly owned copending United States patent application Serial No. 100,289 filed October 19, 1987 by Schlottke et al. for "Method of and apparatus for gathering and manipulating stacked zig-zag formationos of paper sheets". The disclosure of this application is also incorporated herein by reference.

FIG. 1 shows a fully grown stack 61 which constitutes a converted web preceding the web 6a, and a still growing stack 61a which includes a number of panels 91, 92 forming part of the web 6a. The stacking mechanism includes a foraminous endless belt conveyor 62 having a lower reach advancing above the apertured bottom wall of a stationary suction chamber 65. The lower reach of the conveyor 62 attracts the loops 2 which advance beyond the discharge end of the conveyor 9 and deposits the panels of such loops on top of the uppermost panel of the incipient stack 14 while the later rests on a table-like support 63 movable along a horizontal path to and from the stacking station 59 so as to temporarily support or carry the oncoming incipient stack 14 as well as the growing stack 61a while another table-like support 67 is in the process of lowering a fully grown stack 61 onto a take-off conveyor 68 serving to advance the stack 61 in the direction of arrow 69. The means for moving the support 67 up and down relative to the path 7 and the conveyor 68 comprises an elevator mechanism 68 of the type described in the aforementioned copending patent applications of Peter et al. and Schlottke et al.

1 The mechanism at the stacking station 59 further comprises a rotary folding tool 64 which cooperates with the lower reach of the conveyor 62 to fold the panels 91, 92 relati to each other along the respective weakened portions 90. Accurate formation of stacks 61 is assisted by a rotary brush 6, which is installed downstream of the support 63 when the latter assumes the extended position of FIG. 1.

When the gathering of the stack 61a into a full stack E is completed, the support 67 is held in the raised position to accept the fully grown stack from the support 63, and the fully grown stack 61 is then lowered by the support 67 to be depositec on the take-off conveyor 68 and to be transported in the direct-' of arrow 69 to a packing station or elsewhere. The support 67 can accept a growing stack 61a and then remains in the raisec, position until the conversion of the web 6a into a fully grown stack is completed. The means for reciprocating the support 6-to and from the stacking station 59 are or can be identical witthose disclosed in the aforementioned copending patent applications of Peter et al. and Schlottke et al.

The cams 32 and 47 serve as a means for cyclically operating the tongs 17 at intervals which are required to ensure that the front loop 2a of each oncoming web is engaged and decelerated for an interval of time which suffices to establish gap A of requisite width.

FIG. 2 shows the tongs 17 in a starting position in which the jaw 17a is closed and the loops 2 of a web on the uppe reach ga of the conveyor 9 advance toward the stacking station 59. Such situation prevails while the front loop 2a of an oncoming web (6b) is in the process of advancing toward the decelerating device 16. At such time, the deactivating means including the fluid-operated motors 34 and 48 are operative to maintain the roller follower (tracking means) 33 out of contact with the rotating cam 32 and to maintain the roller follower 46 out of contact with the rotating cam 47.

FIG. 3 shows the next stage when the trailing end TE of 1 J 15.

the web 6a has arrived at the decelerating station and the jaw 17a has been pivoted to open position so that the jaws 17a, 17b are ready to engage the panels 91, 92 of the first loop 2a of the web 6b. The locus of separation of the trailing end TE of the web 6a from the first loop 2a of the next-following web 6b is shown at 71. The motors 34 and 48 are idle, i.e., the follower 33 tracks the cam 32 and the follower 46 tracks the cam 47. The tongs 18 advances in the direction of arrow 8 and opens in the course of such movement or even before the movement in the direction of the arrow 8 begins.

Referring to FIG. 4, the jaw 17a is already closed and cooperates with the jaw 17b to grip the loop 2a and to decelerate this loop in order to bring about a widening of the gap 2, to the desired-optimum value. At the same time, the braking means including the conveyor 54 and the suction chamber 51 ensures a highly predictable for-mation of an incipient stack 14 having panels 91, 92 which are folded over each other in zig-zag formation on top of the panels 91, 92 of the loop 2a.

FIG. 5 shows the tongs 17 in the process of releasing the loop 2a so that the incipient stack 14 can be advanced toward and into the stacking station 59 of FIG. 1 wherein the incipient stack grows into a stack 61a and the stack 61a grows into a stack 61. The incipient stack 14 has been accelerated to the speed of the conveyor 9 prior to being released by the jaws 17a, 17b of the tongs 17. The tongs 17 is then caused to return to the starting position of FIG. 2 and is ready to decelerate the first loop 2a of the next web. The motors 34 and 48 ensure that the tongs 17 will dwell in the position of FIG. 2 and that the jaw 17a will be closed until and unless a fresh loop 2a reaches the decelerating station. The tongs 17 completes a full cycle in response to one full revolution of

the shaft 49 and cams 32, 47. One such revolution of the shaft 49 takes up an interval of time which is required to advance a predetermined number of loops 2 (e.g., twenty-five loops) and hence a predetermined number of panels 91,- 16.

92 (fifty) past the decelerating station. The length of the webs 6a, 6b... is selected in such a way that the number of panels ireach web is a whole multiple of fifty. This ensures accurate synchronization of movements of the tongs 17 with the transport of loops 2 toward the stacking station 59. In other words, each of the cams 32, 47 assumes a predetermined angular position at the time the motors 34, 48 are actuated to ensure that the chain 22a can pull the carriage 19 for the tongs 17 in the direction of arrow 8 and that the coupling member 36 can move the jaw 17a to open position in good time for engagement of the first loop 2a of an oncoming web.

The means for operating the motors 34, 48 at proper intervals includes a control circuit 72 which is shown in FIG. 1 and receives appropriate signals from the web severing device 101 via c - onductor means 73. Signals which are transmitted via conductor means 73 denote that the device 101 has completed a severing operation, i.e.i that a loop 2a is in the process of approaching the decelerating station. Such signals are properly delayed in the control circuit 72 which further receives signals from a device 81 which monitors the angular position of the shaft 49 and hence the angular positions of the cams 32 and 47. When a loop 2a approaches the decelerating station, the outputs of the control circuit 72 transmit appropriate signals to servomotors 74, 76 which constitute means for actuating valves 77, 78. These valves.can connect the motors 34, 48 with a source 79 of pressurized fluid, e.g., with an air compressor. This results in a movement of the follower 33 into engagement with the periphery of the rotating cam 32 and in a movepent of the followel 46 into engagement with the periphery of the rotating cam 47. The monitoring device 81 e.g.t a conventional revolution counter transmits to the control circuit 72 a signal via conductor 82 when the shaft 49 completes a full revolution following a movement of the followers 33, 46 into engagement with the respective cams 32, 47 so that the control circuit 72 then causes the valves 77, 78 to initiate a disengagement of the followers 33, 46 from the respective cams.For example, the valves 76, 77 17.

then seal the cylinder chambers of the motors 34, 48 from the source 79 and connect such cylinder chambers with the atmosphere.

The arrangement is preferably such that the followers 33, 46 are maintained at a minimum distance from the most pronounced lobes of the respective cams 32, 47 when the tongs 17 is idle. This ensures that a cycle of the tongs 17 can begin in instant response to proper actuation of the valves 77 and 78.

The control circuit 72 can be replaced with a computer without departing from the spirit of the invention.

It is further possible to provide the decelerating device 16 with a loopengaging component other than the illustrated tongs 17'. For example, it is possible to replace the tongs 17 with one or more suction cups which are connected to a suction generating device when the control circuit 72 transmits a signal to start a cycle of the decelerating device.

It is also possible to omit the motors 109, 154 and to proVide motion transmitting connections from the main prime mover of the machine which embodies the improved stacking apparatus to one of the pulleys 9, 11, 12 and to one of the pulleys 56, 57, 58 so as to ensure that the speed of the conveyor 9 will exceed the speed of the conveyor 54.

It is further possible to enlarge the capacity of the apparatus by transporting two or more rows of webs side by side. It is then necessary to provide several decelerating devices and several stacking stations. A single conveyor 9 can be used to transport two or more rows of webs.

The webs may but need not necessarily., consist of paper, i.e., the apparatus can treat all kinds of webs which are to be converted into stacks wherein the panels are arrayed in zig-zag formation.

An important advantage of the improved method and apparatus is that the trailing end-of a preceding web cannot interfere with proper stacking of panels forming part of the next-following web, that the next-following web cannot interfere with proper stacking of panels at the trailing end of the 1 1 8.

preceding web, as well as that a stack (14) can be formed already during the interval which is needed to increase the width of the gap between two successive webs of a row of webs. Moreover, the incipient stacks 14 can be formed with a high degree of accuracy so that they need not be adjusted upon arrival at the stacking station 59.

The chain 22a of the conveyor 22 can be replaced with a toothed belt or with any other means which ensures a highly predictable movemen.t of the tongs 17 along the path which is defined by the track 21, i.e., which ensures that the means for pulling the carriage 19 cannot slip relative to the pulleys or sprocket wheels.

19.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.

20.

C LJL 11.1:

1. In a method of zig-zag folding and stacking a row of closely adjacent discrete webs which consist of paper or a like flexible material and have panels connected to each other by transversely extending weakened zones and wherein successive pairs of panels form loops, the steps of transporting successive webs of the row along a predetermined path at a predetermined speed; and temporarily decelerating first loops of successive defines therewith a gap as a result of temporary deceleration webs in a predetermined portion of said path so that the trailing end of the web preceding the temporarily decelerated first loop moves away from the decelerated first loop and of the first loop.

2. The steps of claim 1, wherein said decelerating step includes temporarily arresting the first loops of successive webs.

The steps of claim 1, further comprising the steps of transporting the loops following the decelerated loop at said speed, and folding the panels of such loops in zig-zag formation on top of the decelerated loop to thus form an incipient stack of overlapping panels.

4. The steps of claim 3, further comprising the steps of conveying the decelerated loop and the incipient stack an top of the decelerated loop upon completion of the decelerating step.

i i 1 1 i j i 21 5. The steps of claim 4, wherein said conveying step includes advancing the decelerated loop and the incipient stack thereon along said path at said predetermined speed.

6. The steps of claim 4, wherein said conveying step includes advancing the decelerated loop and the incipient stack thereon into a second portion of said path.

7. The steps of claim 6, further comprising the step of depositing the Panels of remaining loops of the web advancing into the second portion of said path in zig-zag formation on top of the incipient stack so as to convert the entire web into a stack of superimposed panels in zig-zag formation 22.

8. In an apparatus for zig-zag folding and stacking a row of closely adjacent successive discrete webs which consist of paper or a like flexible material and have panels connected to each other by transversely extending weakened zones and wherein successive pairs of panels form loops, the combination of means for transporting successive webs of the row in a predetermined direction along a predetermined path at a predetermined speed; and means for temporarily decelerati: first loops of successive webs in a predetermined portion of said path so that the trailing end of the web preceding the temporarily decelerated first loop moves away from the decelerated first-loop and defines therewith a gap as a result of temporary deceleration of the first loop.

9. The structure of claim 8, wherein said deceleratina means includes means for temporarily arresting the first loops of successive webs.

10. The structure of claim 8, wherein said transporting means-includes an endless foraminous conveyor and means for establishing a pressure differential between opposite sides of said conveyor so that the loops are attracted to one side of said conveyor.

11. The structure of claim 10, wherein said means for establishing the pressure differential includes a suction chamber at the other side of said conveyor.

1 1 i j 12. The structure of claim 8, wherein said decelerating means comprises tongs.

23.

13. The structure of claim 12, wherein said deceleratina means further comprises means for moving said tongs along said path in and counter to said predetermined direction.

14. The structure of claim 13, wherein said moving means comprises a carriage for said tongs and a track for said carriage.

15. The structure of claim 14, wherein said moving means further comprises means for reciprocating said carriage forwardland backwards along said track.

16. The structure of claim 15, wherein said reciprocating means includes means for pulling said carriage in and counter to said predetermined direction.

17. The structure of claim 16, wherein said reciprocating means further comprises a driven cam and means for transmitting motion from said cam to said pulling means.

18. The structure of claim 17, wherein said motion transmitting means comprises at least one lever operatively connected with said pulling means and having Imeans for tracking said cam.

19. The structure of claim 18, further comprising means for deactivating said motion transmitting means.

21j.

20. The structure of claim 19, wherein said deactivatinc means comprises means for disengaging said tracking means from said cam.

21. The structure of claim 20, wherein said disengaging means comprises a fluid-operated motor.

22. The structure of claim 16, wherein said pulling mean-w comprises a chain.

- 23. The structure of claim 12, wherein said decelerating means further comprises means for opening and closing said tone 24. The structure of claim 23, wherein said tongs comprises a first jaw and a second jaw movable relative to said first jaw between open and closed positions, said means for opening and closing said tongs including means for moving said second jaw relative to said first jaw.

i i i 25. The structure of claim 24, wherein said means for moving said second jaw comprises a rotary cam and means for displacing said second jaw relative to said first jaw in response to rotation of said cam. 71 26. The structure of claim 25, wherein said means for displacing said second jaw comprises a mobile output member coupled to said second jaw and means for transmitting motion between said cam and said output member.

9P 27. The structure of claim 26, wherein said motion transmitting means includes a linkage coupled to said output member and having follower means arranged to track said cam.

28. The structure of claim 27, further comprising means for deactivating said motion transmitting means.

- t 29. The structure of claim 28, wherein said deactivating means includes fluid-operated motor means for disengaging said follower means from said cam.

30. The structure of claim 25, further comprising means for moving said tongs along said path in and counter to said predetermined direction, said means for moving said tongs including a second rotary cam coaxial with the cam of said means for moving said second jaw and further comprising means for jointly rotating said cams.

31. The structure of claim 8, further comprising means for.braking the loops which follow the temporarily decelerated first loop.

32. The structure of claim 31, whereinTsaid braking mean includes means for gathering the panels forming part of loops that follow the decelerated loop into an incipient stack on top of the decelerated loop.

2 (-'.

33. The structure of claim 31, wherein said braking means comprises a foraminous conveyor and means for attractinc loops to said conveyor.

34. The structure of claims 33, wherein said attractinc means comprises a stationary suction chamber.

35. The structure of claim 34, wherein said suction chamber has a portion which is adjacent said conveyor and at least one opening in said portion.

36. The structure of claim 33, further comprising mean for driving said conveyor at a second speed less than said predetermined speed.

37. The structure of claim 33, wherein said deceleratimeans comprises tongs and means for moving said tongs in and counter to said predetermined direction along a portion of said path to and from an end position, said attracting means being adjacent said path upstream of and adjacent said tongs in the end position of the tongs.

38. The structure of claim 8, further comprising means for stacking the panels of successive loops of successive webE in zig-zag formation in a second portion of said path downstre of said predetermined portion.

f- j.

39. The structure of claim 38, further comprising means for gathering the panels forming part of at least one loop following the decelerated loop into an incipient stack on top of the decelerated loop, said stacking means including means for laying the panels of loops following the at least one loop in zig-zag formation on top of the respective incipient stack.

40. The structure of claim 39, wherein said stacking means comprises a first support which is disposed beneath the second portion of said predetermined path, means for moving said support between a raised position in which the support supports a stack in said second portion of said path and a lowered position in which a stack can be removed therefrom, and a second support movable to and from a.position beneath said second I said path to support an incipient stack while the portion o. first support is away from said raised position.

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