US 3631771 A
Stacking and withdrawal apparatus for a bagmaking machine for the delivery of carrier bags having handholes formed therein or welded-on handles by means of a plurality of conveyors provided with prongs having a cross section conforming to the shape of the handholes.
Description (OCR text may contain errors)
United States Patent  Inventors AugustSchwarzkopf;  ...B65h33/00 FriedhelmMundus,Lengerichof  93/93DP; Westphalia, both of Germany 214/8; 198/35, 40, 131  AppLNo. 868,022
 References Cited UNITED STATES PATENTS 5/1944 Decker......
 Filed Oct. 21, 1969 Jan. 4, 1972 214/8 UX 198/131 X 2,350,273 3,024,887 3/1962 lngham......................... Primary Examiner-Bernard Stickney Attorney-Fleit, Gipple & Jacobso  Patented  Assignee Windmoller & Holscher Lengerich of Westphalia, Germany  Priority Oct. 28, 1968 Germany P 18 05 724.4
 STACKING AND WITHDRAWAL APPARATUS FOR ABSTRACT: Stacking and withdrawal apparatus for a bag- BAGMAKING MACHINE making machine for the delivery of carrier bags having hand- 10 Chims, 9 Drawing Figs holes formed therein or welded-on handles by means of a plu- U S Cl 93/93 DP rality of conveyors provided with prongs having a cross seec Qu".u...-....n...h...a...-..uuunnu-uenun. l tlon conforming to the shape of the handho es Pmmmm 41912 3.631; 771
INVENTORS August SCHWARZKOPF Friedhelm MUNDUS their AT RNEYS miminm 41912 1631.771
SHEET 2 UF 5 FIGSQ FIG.5
INVENTORS August SCHWARZKOPF Friedhelm MUNDUS y ww/ MM their ATT NEYS PATENTEU JAN 41972 SHEET 3 [IF 5 INVENTORS August SCHWARZKOPF Friedhelm MU NDUS Y their ATT6RNEYS PATENTEU JAN 41912 3631.771
sumunrs INVENTORS ust SCHWARZKOPF Friedhelm MUN DUS y th eir AT NEYS Pmmmm A 1972 3.631. 771
SHEET 5 BF 5 'INVENTORS August SCHWARZKOPF F'riedhelm MUNDUS rthil" ATTNEYS STACKING AND WITHDRAWAL APPARATUS FOR BAGMAKING MACHINE The invention relates to stacking and withdrawal apparatus for a bagmaking machine delivering carrier bags having handholes formed in the bag material or defined by welded-on handles. The invention also extends to bagmaking machines incorporating such apparatus.
It is usual to provide bagmaking machines with depositing tables or belts on which the bags are superposed to form handy stacks containing a predetermined number of bags, the stacks then being taken away, for example to be packaged. The provision of such a depositing or stacking table calls for a short term standstill of the bagmaking machine so that a completed stack can be removed. The provision of an intermittently moved withdrawal belt calls for high accelerations if the completed stack is to be removed from the machine without stopping the latter and without interfering with the bags that are continually delivered by it. This is because the belt must be moved in the very short time interval between two successively delivered bags.
Known stacking apparatus of this kind works satisfactorily provided that the bags can be neatly superposed with the edges flush with one another to form stacks of any desired height. In this case the large area of contact between superjacent bags will prevent the bags from slipping and the stack from toppling over and, if the stack is sufficiently high, the standstill periods for the bagmaking machine can be kept to a commercially viable minimum. Even if an intermittently moved discharge belt is used instead of a stationary stacking table, the belt can be accelerated sufficiently fast to prevent slipping of the bags in the stack.
However, presently known stacking equipment is less suitable for cam'er bags which cannot be readily stacked to any desired height. The handles at the mouths of the bags interfere with stacking, especially if they are made from plastics material and welded to the mouth. Even if the handles are made by stamping holes in the bag material, difficulty will be caused by reinforcing tabs that are applied near the handles and by a flap that is often turned over at the mouth of each bag. The increased thickness caused by the tabs and/or flaps near the handles prevents intimate contact between superjacent bags and therefore even a small stack is liable to slip. Also, the increased thickness causes the bags in the growing stack to assume a constantly more oblique angle; this is another reason why the height of the stack must be kept small if the bags are not to slip off under gravity. Most important, the danger of slipping precludes the use of intermittently operated discharge belts because their rapid acceleration will almost certainly cause the stacks to topple. For all these reasons, it is usual for carrier bags to be delivered by the bagmaking machine in an overlapping scalelike arrangement so that an operator is required to pile the bags together like a pack of cards and then remove them in stacks of predetermined size. This manual operation is complicated by the presence of the handles and therefore calls for considerable labor and time.
The invention aims to provide a stacking and withdrawal apparatus for carrier bags, in which the bags delivered by a bagmaking machine can be automatically stacked and then withdrawn from a stacking station without the danger of slipping, whereafter an operator need merely lift off the withdrawn stacks, again without the danger of slipping.
According to the invention, a stacking and withdrawal apparatus for a bagmaking machine delivering carrier bags having handholes formed in the bag material or defined by welded-on handles comprises an intermittently operable stacking conveyor for receiving and stacking successively delivered bags while it is stationary at a stacking station and moving the bags away from the stacking station after a stack of predetermined size has been formed, the stacking conveyor being provided with a plurality of prongs which have a cross section conforming to the shape of the handholes and which are so disposed at a constant spacing from one another along the conveyor that, when the latter is stationary, one of said prongs is located at the stacking station to engage through the handholes of the successively delivered bags. Since the handholes are generally elongated and the prongs of the stacking conveyor are of complementary shape, the bags will be adequately guided while they are being threaded on the prongs and a stack of accurately superposed bags will be formed. There is no danger of slipping while the bags are held by the prongs, even if the stacks are then withdrawn at a high acceleration. Slipping is also minimized when the stacks are manually lifted off the prongs. The direction of each prong while it is located at the stacking station will of course depend on whether the carrier bags are delivered so that they dropon the prongs under gravity or whether special means are provided to place the bags over the prongs.
In a preferred form of the invention, the stacking and withdrawal apparatus is used in combination with a bagmaking machine which has a delivery conveyor for feeding the bags to the stacking station in a horizontal plane, the prong at the stacking station being vertically disposed below this plane and a vertical stop plate being provided in the path of the delivered bags so that each bag has its handhole in registry with the prong as it strikes the stop plate. The bags ejected from the bagmaking machine are braked by the stop plate and fall vertically onto the prong. To facilitate accurate positioning of the handholes of various sizes of bags in relation to the prong, the position of the stop plate is preferably adjustable lengthwise of the path of the delivered bags. By altering the standstill period of the stacking conveyor, stacks of various heights can be fonned, the number of bags in each stack being limited practically only by the height of the prongs. When the stacking conveyor is then moved, the stack is withdrawn while another prong is moved into position to take its place at the stacking station. In this way, stacks containing a constant number of bags can be formed continually and these stacks can be conveniently lifted off the prongs while the stacking conveyor is stationary.
In a very simple embodiment of the invention, a single horizontally operative conveyor is provided in which the bags simply drop on the prongs under gravity and the completed stacks are moved away to a convenient position where an operator can lift them off.
In contrast to the standstill period of the conveyor, which depends on the number of bags that is to form each stack, the time during which the conveyor is moved remains constant. Movement of the stacking conveyor must take place in the time interval between two successively arriving bags. For bagmaking machinery of high capacity, this time interval is very short indeed. Consequently, the stacking conveyor must be moved at high speeds and this calls for close observance by the operators who have to lift the stacks from the prongs. In addition, it is not always possible to meet the requirements for high speeds and high accelerations because, if the stacks are to be readily accessible and the operators are to be conveniently located in relation to the stacking apparatus, the stacking conveyor must extend over a large distance so that the completed stacks are withdrawn sufficiently far from the stacking station. On the other hand, movement of the stacks over relatively long distances in the short available time calls for accelerations which are no longer practicable. Thus, to avoid excessively high speeds and accelerations and the consequent danger of slipping when the stacks are removed from the prongs, in a preferred form of the invention the stacking conveyor is vertically operative to move the stacked bags downwardly away from the stacking station to an intermittently and horizontally operative second conveyor provided with vertical prongs secured thereto at intervals by brackets that extend laterally from the second conveyor. The prongs of the stacking conveyor are in the form of slotted sleeves through which the prongs and brackets of the second conveyor can pass, the arrangement being such that, when the second conveyor is stationary, one of its prongs is aligned vertically below the prong of the stacking conveyor at the stacking station so that, when the latter is operative, the prong of the stacking conveyor is moved from the stacking station and over and beyond the prong of the second conveyor whereby the stack is transferred to the second conveyor which can then transport the stack horizontally towards an operator. The time available for movement of the second conveyor is the entire stacking period during which the stacking conveyor is stationary, certainly long enough to avoid danger to the operator and also to avoid excessively high accelerations for exceptionally heavy horizontal conveyors. On the other hand, the vertically operative stacking conveyor needs to cover only a short distance to transfer a stack to the second conveyor and can thus be moved rapidly even if successive bags are delivered at short intervals by high-capacity bagmaking machines.
In the path of the successively delivered bags, there is preferably included a counting switch mechanism for starting the stacking conveyor after a preset number of bags have passed, i.e. after the stack of predetermined size has been formed. The stacking conveyor can then move one complete step until it has itself actuated a terminating switch to stop its movement, at which time another prong of the stacking conveyor will be located at the stacking station.
In the aforementioned construction of stacking apparatus which is intended for use with high-capacity bagmaking machinery and which is provided with a second conveyor, the terminating switch which is actuated by the stacking conveyor can also be adapted to start the second conveyor, a further switch being provided which is actuatable by the second conveyor to stop the latter when its next prong is aligned vertically below that prong of the stacking conveyor which is located at the stacking station.
Preferably, both the stacking conveyor and the second conveyor are in the form of endless chains, the vertical stacking conveyor being disposed within the confines of a horizontal loop defined by the chain of the second conveyor. In this way there is a saving of space and the fast-moving vertical conveyor is so to speak screened by the slow-moving horizontal conveyor from accidental contact by the operating personnel.
Further features of the invention will become evident from the following description with reference to an example illustrated in the accompanying drawings, wherein:
FIGS. 10 and lb are a composite view of a plan of a stacking and withdrawal apparatus placed at the outlet end of a bagmaking machine, the plan being broken at the vertical chaindotted lines in each of these figures;
FIGS. 2a and 2b are a composite view similar to FIGS. la and 1b but showing the apparatus and machine in side elevation;
FIG. 3 is an enlarged cross section on the line III-III in FIG. In;
FIG. 4 is a fragmentary plan view taken in the direction of the arrow IV in FIG. 2a;
FIGS. 5 and 5a are respectively a front and side elevation of a carrier bag with a welded-on handle, and
FIG. 6 is a front elevation of a carrier bag in which the handle is formed by a handhole stamped out of the bag material.
The illustrated stacking and withdrawal apparatus comprises an intermittently operable vertical conveyor 1 and an intermittently operable horizontal conveyor 2, both carried by a frame 3. The vertical conveyor is in the form of a chain conveyor. Its endless chain 4 runs in the direction of the arrow a (FIG. 3) over sprockets 5, 6 mounted in the frame, the lower sprocket 6 being intermittently driven by an electric motor 8 acting through an intermittent drive or gearing 7. At intervals I, the chain 4 carries supports or mountings 9 for prongs 10.
The cross section of each prong l conforms to the shape of handholes II or 11 in the respective carrier bags B or B shown in FIGS. and 6. The prongs are dimensioned so that they can pass freely through the handholes and, as best shown in FIG. 4, they are made from thin sheet metal in the form of a sleeve having a throughgoing longitudinal slot 12. One end of each prong is secured to U-shaped metal extension brackets 13 of the supports 9. The arrangement of the sup ports 9 along the chain 4 is such that the prongs 10 are disposed vertically in the downwardly moving run of the chain, their free ends being directed upwardly. The arrangement of the prongs on the brackets 13 is such that the longitudinal slots 12 face outwardly of the loop defined by the chain. In the downwardly moving run of the chain, lateral guide projections of the supports 9 slide in stationary guide rails l4, 14' so that the prongs 10 will be accurately guided whenever they are moved by the chain.
The horizontal conveyor 2 comprises an endless chain 15 which runs in the direction of the arrow b (FIGS. la and 4) over sprockets 16, I7, I8 and 19. The sprocket 16 is intermittently driven by an electric motor 21 acting through an intermittent drive or gearing 20. At a spacing t, the acting through an intermittent drive or gearing 20. At a spacing t, the chain 15 carries mountings or supports 22 for prongs 23. The cross section of each prong 23 conforms to the internal cross sec tion of the prongs 10 of the vertical conveyor 1. The prongs 23 are disposed vertically; their lower ends being secured to narrow lateral extensions or brackets 24 of the supports 22. The construction is such that, as best shown at the left hand side of FIG. 4, a sleeve-form prong 10 can be freely telescoped over and beyond a prong 23, at which time the narrow bracket 24 passes through the longitudinal slot 12 of the prong 10. The supports 22 are accurately glided along guide rails 25 which follow the course of the chain 15.
As most clearly shown in FIGS. la and 4, the vertical conveyor l is arranged within the confines of the loop formed by the chain 15 of the horizontal conveyor so that, when both conveyors are stationary, a prong 23 of the horizontal conveyor will be aligned vertically below a prong 10 of the vertical conveyor.
The drives 7, 20 of the two conveyors are each equipped with a suitable electromagnetic clutch (not shown) having a quick-action brake. The brakes are applied by terminating switches 26 (FIG. 3) and 26' (FIG. la after the respective conveyors l and 2 have moved a distance r and 1' respectively. The terminating switches are accurately adjustable in the conveying directions of the respective conveyors to ensure that, after each movement of the horizontal conveyor, one of its prongs 23 will be accurately disposed beneath one of the prongs 10 of the vertical conveyor. The terminating switches are actuated either by respective tripping cams 260, 260' provided at respective spacings z and I along the chains 4 and 15 (preferably provided on the supports 9 and 22, respectively), or by a rotary disc (not shown) of the respective drives 7 and 20.
The intermittent drive 7 for the vertical conveyor 1 is actuated by a counting switch mechanism 27 (Fig. la which may be photoelectric and which is disposed in the path of the successively delivered bags B, as soon as the number set on the counting mechanism has been attained. The drive 7 is so designed that the chain 4 will then advance by the distance I in the short time interval between two successively arriving bags.
The drive 20 for the horizontal conveyor 2 is switched on by the switch 26 (FIG. 3) that terminates movement of the vertical conveyor 1. The drive 20 is designed so that the chain 15 travels sufficiently slowly to present no danger to the operating personnel.
The frame 3 is provided with wheels and/or casters 28 so that the apparatus is mobile and can be conveniently moved to an operating position adjacent any desired bagmaking machine. The height of the frame is such that the horizontal conveyor 2 and its prongs 23 are at normal table height and an operator can conveniently lift stacked bags from the prongs 23.
As shown in FIGS. la, 1b and 2a, 2b, the stacking and withdrawal apparatus is located at the output end of a bagmaking machine 29 and releasably coupled thereto by means of a flange 30 so that a plane E-E (FIGS. 2a, 2b and 3) in which the bagmaking machine delivers bags is disposed above that prong 10f of the vertical conveyor which, when the vertical conveyor is stationary, is disposed at a stacking station in readiness to receive the delivered bags by engaging through their handholes. In relation to the longitudinal medial plane of the bagmaking machine, the stacking apparatus is arranged so that the longitudinal medial plane F-F (FIGS. 1a and lb) of the handholes ll of the carrier bags B delivered by the bagmaking machine coincides with the longitudinal medial plane of the prong at the stacking station. A stop plate 31 which is adjustable in position lengthwise of the path of the delivered bags is provided so that each delivered bag has its handhole in registry with the prong 10f as it strikes the stop plate.
The illustrated bagmaking machine 29 makes the carrier bags of FIG. 5 or FIG. 6 from a foil of plastics material which is folded over lengthwise to double thickness. The folded foil is indicated at A in FIG. lb By means of the machine, plastics handles T are then welded at intervals along the free edges of the folded foil as indicated in chain-dotted lines in FIG. lb, the handles defining handholes 11, or handholes such as 11 in FIG. 6 are formed at intervals in both layers of the folded foil to form handles. The foil is then intermittently moved through distance equal to the desired bag width 2 in the direction of the arrow c by means of feed rollers 32 so that a reciprocable welding bean 34 of welding apparatus 33 can apply transverse seam welds to the foil and therefore divide the latter into individual bag sections B which are torn from the foil by a faster double-belt conveyor 35 while the seam formed by the welding beam 34 is still soft, that is to say half of each seam remains on the bag that is torn off and the other half remains on the foil to form a side seam for the next bag section, each completed bag having a base (which may be gusseted) defined by the folded over portion of the foil a two welded sides formed by the welding beam 34 and an open mouth adjacent the handle T.
The conveyor 35 of the bagmaking machine also constitutes a delivery conveyor for the stacking apparatus. It delivers the severed bags along the plane E-E and throws them freely against the vertical stop plate 31 of the stacking apparatus, from which the bags drop under gravity to engage with their handholes over the prong 10f at the stacking station to form a stack St (FIG. 3). In the case of very flexible bag material, there may be a danger of the bags turning or folding over as they are flung towards the stop plate. To minimize this danger, a pair of interengaging circumferentially grooved rollers 36 is interposed between the conveyor 35 and the stacking station. These rollers temporarily form loose corrugations in the bags (see FIG. 5a), the peaks and roots of the corrugations extending in the conveying direction of the conveyor 35 so that each bag has additional stiffness imparted to it to counteract the tendency to buckle or turn over.
As soon as the number of bags set on the counting mechanism 27 has been threaded onto the prong 10f at the stacking station, the mechanism switches on the electric motor 8 and drive 7 for the vertical conveyor 1, the chain 4 of which will then rapidly move through a distance I so that the prong 10f and the stack St thereon are moved downwardly over a stationary prong 23 of the horizontal conveyor 2. During this telescopic engagement of the two prongs, the stack is transferred to the prong 23 in that the bracket 24 sweeps the stack off the prong 10f. Movement of the chain 4 is terminated by the switch 26 (FIG. 3) as soon as the next prong 10 has reached the stacking station, the prong 10f then being located below the horizontal conveyor 2 so as not to interfere with the movement thereof. The switch 26 simultaneously starts the motor 21 and drive for the horizontal conveyor 2, the chain 15 of which then slowly moves through a distance I so that the stack St of bags is safely transported in the direction of the arrow b away from the vertical conveyor 1. The stack of bags can then be conveniently removed from the prong 23 by an operator who can be safely located near that end of the con veyor 2 remote from the rapidly moving conveyor 1.
If the operating sequence of the bagmaking machine, or rather the time interval between two successive bags delivered by the bagmaking machine, is sufficiently long to permit the bags to be threaded directly on the prongs of the horizontal conveyor, then the vertical conveyor 1 can be dispensed with.
The stacking and withdrawal apparatus is of course also applicable to bagmaking machines from which the bags are ejected with the handles foremost. In that case, the bags would arrive at the stacking station in the direction of the chaindotted arrow X in FIG. 1a and the stop plate would be disposed as shown in chain-dotted lines at 31 We claim:
1. Stacking and withdrawal apparatus for a bagmaking machine delivering carrier bags in'a horizontal plane, the bags having handholes formed in the bag material or defined by welded-on handles, comprising an intermittently operable stacking conveyor for receiving and stacking successively delivered bags while stationary at a stacking station and moving the bags away from the stacking station after a stack of predetermined size has been formed, the stacking conveyor being provided with a plurality of prongs which have a cross section conforming to the shape of the handholes and which are so disposed at a constant spacing from one another along the conveyor that, when the latter is stationary, one of said prongs is located at the stacking station to engage through the handholes of the successively delivered bags, said one prong at the stacking station being vertically disposed below said plane,
a vertical stop plate provided in the path of the delivered bags so that each delivered bag has its handhole in registry with said one prong as the bag strikes the stop plate, and an intermittently and horizontally operative second conveyor provided with brackets that extend laterally therefrom and vertical prongs secured thereto at intervals by said brackets, the stacking conveyor being vertically operative to move the stacked bags downwardly away from the stacking station to said second conveyor, the prongs of the stacking conveyor being in the form of slotted sleeves through which the prongs and brackets of said second conveyor can pass, the arrange ment being such that, when said second conveyor is stationary, one of its prongs is aligned vertically below said one prong of the stacking conveyor so that, when the latter is operative, its said one prong is moved from the stacking station and over and beyond said one prong of said second conveyor whereby the stack is transferred to said second conveyor.
2. Apparatus according to claim 1, wherein the stop plate is adjustable in position lengthwise of the path of the delivered bags.
3. Apparatus according to claim 1, including a counting switch mechanism in the path of the successively delivered bags for starting the stacking conveyor after the stack of predetermined size has been formed and a tenninating switch adapted to be actuated by the stacking conveyor to stop the latter when another prong thereof is located at the stacking station.
4. Apparatus according to claim 3, wherein said terminating switch is adapted to start said second conveyor, a further switch being provided which is actuatable by said second conveyor to stop the latter.
5. Apparatus according to claim 4, including tripping cams carried by the conveyors for actuating the respective switches.
6. Apparatus according to claim 1, wherein the stacking conveyor comprises an endless chain to which the associated prongs are attached at equal spacings to be directed vertically upwardly in the conveying run of the chain.
7. Apparatus according to claim 1, wherein said second conveyor comprises an endless chain moving in a horizontal plane and guide rails following the course of the chain for guiding supports for the prong-securing brackets.
8. Apparatus according to claim 7, wherein the stacking conveyor is disposed within the confines of a loop defined by the chain of said second conveyor.
9. Apparatus according to claim 1, wherein the components are supported by a mobile frame.
10. A machine according to claim 1, including means downstream of the delivery conveyor for laying the successive bags into loose corrugations before reaching the stacking station, the peaks and roots of the corrugations extending in the conveying direction of the delivery conveyor.