PRESSER APPARATUS

Abstract: During the formation of a container (C) from a blank, a pair of opposite end tabs of the partially erected container travelling on a conveyor (2) are closed against side walls at the front and rear of the container in the direction of travel by presser devices (18, 20) travelling with the container on their own conveying means (14a, 14b). The front and rear presser devices (18, 20) are mounted on separate units of the conveying means. The respective units can be driven at different speeds and are controlled so as to open the spacing between the presser devices at entry to and exit from the conveyor path and to close said spacing between said entry and exit to clamp the container tabs against said side walls.

Description: PRESSER APPARATUS This invention relates to container erection apparatus and is particularly concerned with apparatus which can operate on partly erected containers as they move along a conveyor path. When forming a container from a blank of sheet material such as paper or card, using sealing tabs that are folded over from one wall of a blank to be adhered to another wall transverse thereto, it is well known to perform such folding and sealing operations on lateral side walls and tabs as the container moves, along a conveyor path. Special precautions may be needed, however, if such tabs project to the front and/or rear of the container to avoid a sequence in which the folding and sealing tools would move into the path of the container. For example, by reorienting the partly formed container it is possible to fold anc seal these tabs in the same way as lateral side tabs, but that adds complication. Alternatively, the movement of the container can be temporarily halted while the tabs are secured, but that introduces another complication and slows the process of forming the container. In GB 1048796 a carton erection apparatus is described with a mechanism which engages front and rear flaps of each container in a stage of its erection while the container is ' being conveyed through the apparatus. For this purpose, front flap engagement elements project from one endless chain conveyor to engage each container as it moves along its path and, a little downstream of the point of front flap engagement a rear flap engagement element mounted on a second endless chain conveyor then comes into engagement with the container rear flap as it is brought around its conveyor return sprocket to run parallel with the container path. The movement of the conveyor chain around the return sprocket accelerates the rear flap engagement element relative to the front flap engagement element which is already travelling parallel to the container path. The container front and rear flaps are thereby gripped between the front and rear elements. The two chain conveyors extend to different points at the downstream end so that the front flap engagement element reaches the downstream return sprocket of its conveyor before the associated rear flap element reaches the corresponding return sprocket of its conveyor. As it moves around its return sprocket, the front flap element is therefore accelerated away from the rear flap element to release the container. It will be noted that this arrangement requires separate conveyors for the front and rear flap engagement elements and is therefore both complicated and space-consuming. According to one aspect of the present invention, there is provided apparatus for operating on a partly erected container entrained by a conveyor to close opposite tabs of the container against respective walls extending transversely from an end wall to the front and rear thereof in the direction of conveyor travel, comprising means for conveying respective front and rear presser devices for the front and rear tabs in the path of the container in the direction of conveyor travel, ' and means for retarding the entry of the rear presser device onto said path and/or accelerating the entry of the front presser device onto said path relative to their conveying means in order to provide an increased clearance between said devices for the introduction of the container between them, and for varying the speed of one or both devices thereafter relative to their conveying means to reduce said clearance and urge them against said tabs to press them against the associated container walls. Said presser devices can be mounted on a common endless conveyor means having a run parallel to said conveyor path along which the presser means act on the container tabs. In a preferred arrangement., similar presser devices are arranged to operate on front and rear tabs of the container respectively, the spacing between them being opened up by a temporary acceleration of the front device and retardation of the rear device and conversely being closed again by retarding the front device and accelerating the rear device. In an advantageous form, the or at least one presser device is mounted on endless conveyor means and comprising a pressing element mounted on a pivot connection having an axis transverse to the travel direction, and a control mechanism is arranged to swing said pressing element forwardly and rearwardly on its pivot connection for said acceleration and/or retardation. The required changes of speed of the pressing elements can then be obtained without altering the speed of their conveyor means. It is nevertheless preferred that front and rear presser devices are mounted on separate endless bands of the conveyor means, to facilitate adjustment of the elements relative to each other in the travel direction in order to match the spacing between them to the container front-to-rear dimension. The invention will be further described by way of example, with reference to the accompanying diagrammatic drawings, in which: Fig. 1 is a plan view showing the arrangement of an apparatus according to the invention in relation to a conveyor along which the partly erected containers are transported to be erected and filled, and Figs. 2 and 3 illustrate the form of the rear presser means of the apparatus in collapsed and operative states respectively. Fig. 1 shows an endless band conveyor 2 having an input drive 4 connected to a return wheel 6 of the conveyor around which extend conveyor bands 8. Pairs of flight bars 10 (only two pairs being shown) project transversely from the conveyor to clamp partly erected containers C between them. Extending along part of the length of the container conveyor is an auxiliary presser conveyor 12. A top run 12a of the auxiliary conveyor is aligned parallel to the adjacent run of the container conveyor immediately below the path of the flight bars 10 and moves at the same speed as the container conveyor. The auxiliary conveyor comprises four similar endless bands side by side, driven in pairs 14a, 14b by respective drive inputs 16a, 16b. Pairs of front and rear presser devices 18,20. are carried by the auxiliary conveyor, the front members on one pair of bands and the rear members on the other pair. Figs. 2 and 3 illustrate the rear presser device 20 in more detail. It comprises a presser plate 22 attached by a pivot 24 to a position control mechanism including a mounting bar 26 which is fixed to one of said pairs of bands 14a, 14b of the presser conveyor. A support element 28 is also fixed to the same pair of conveyor bands behind the mounting bar 26 in the direction of travel, the plate 22 and the support element 28 are also connected by links 32 attached to them through respective pivots 34,36 radially outwards (with respect to return wheels 42 of the auxiliary conveyor) of the pivot 24. The front presser device 18 is an exact mirror arrangement of the rear device 20 so does not need to be described further. Before reaching the auxiliary conveyor, the partly erected rectangular-section containers C are carried by the main conveyor 2 through stations where, by conventional means (not shown) , a bottom flap B of the container blank is folded up to the bottom edges of the container side walls and tabs T at the front and rear of the flap are glued in preparation for being secured to the front and rear side walls W. The function of the presser devices 18,20 is to engage those tabs and press them against the side walls so as to ensure a firm adhesive bond. To do this, the container bottom flaps B rest on a fixed guide 44 as they move along the auxiliary conveyor to ensure they are correctly positioned when the adhesive connection is made. Fig. 3 shows the rear device 20 in its operative position. The presser plate 22 at the front of the member is held perpendicular to the top run of the conveyor with its operative pressing face projecting above the level of the container guide to engage a rear tab T. Although not shown, the front presser device 18 similarly has at the rear a presser plate with a directly opposed pressing face engaging the front tab, the spacing of the two faces being matched to the front-to-rear dimensions of the container to clamp the tabs T against their associated container walls W. Because both presser plates 22 must project into the travel path of the container, it is necessary to • ensure that they do not foul the container before reaching their operative positions. But if the main and auxiliary conveyors travel at the same speed, as is required during the clamping operation, fouling will occur if the presser plates travel round the return rollers 42 in the radially extended position they have when clamping a container. In the illustrated arrangement, the control mechanism to which the presser plate 22 is pivoted causes it to swing about its pivot 24 between the collapsed position shown in Fig. 2, in which it lies close to the conveyor, and the operative position in Fig. 3, projecting perpendicularly from the conveyor when engaging with and disengaging from a container. The pivoting of the presser plates 22 of both devices between these positions is determined by the movement of the conveyor 14a, 14b bands around the return rollers 42 of the auxiliary conveyor. As the bands follow the curvature of a roller, because the presser plate mounting bar 26 and the support element 28 are fixed rigidly to spaced portions of the conveyor bands, they are splayed apart. The distance between the pivpts 24,36 is increased by this effect so that the links 32 draw the presser plate 22 towards the support element 28, ie. collapsing it radially inwards. The pivots 24,34,36 come almost into the same plane and the cranked ends of the links 32 provide clearance with the presser plate 22 and support element 28. In the case of the rear pressure device 20, as Fig. 2 shows, the presser plate 22 is kept out of the container path while it is moving around the arc of the rear roller. As the mounting bar 26 moves onto the planar top run 12a of the conveyor the splay between the bar and the support element 28 is rapidly lost. The presser plate 22 is therefore swung forwards, which movement is added to the conveyor movement as a sharp acceleration, until the presser plate is again travelling at the conveyor speed when the mounting bar and support element are both on the top run of the conveyor. A container C can thus be progressed by its conveyor 2 at the same speed as the presser conveyor 12 and reach the entry to the presser conveyor in advance of the presser plate, to then be engaged by the rear presser plate 22 when it is accelerated to its upright position. A shaft extending transversely through the support element 28 has respective cam followers 46 rotatably mounted on its projecting ends. As each presser device comes onto the top run of the conveyor the cam followers 46 engage and roll along the underside of fixed guide rails 44 at both sides of. the presser conveyor 12. The guide rails thereby provide a fixed reaction surface for the clamping force on the presser device in operation. Further fixed supports 48 lie immediately under the top run 12a of the conveyor to resist downward deflection. In this way it is possible to prevent deflection of the presser devices under load which would otherwise prevent adequate clamping of the conveyor tabs. The front presser device is similarly collapsed as it moves around the rear roller. In this case, however, because of its mirror image arrangement the presser plate 22 is collapsed forwards so that it is retarded as it begins to travel along the conveyor upper run 12a and swings upright. Thus, entering the upper run the front presser plate 22 is initially in advance of the container and reaches its operative position against the front face of the conveyor because it slows temporarily as it comes to the upright position. The previous entry of the front presser device into the arc of the conveyor has, of course, produced an acceleration of its presser plate to the collapsed position. The effective movement of the front and rear presser plates towards each other as a result of the acceleration of the rear plate and the retardation of the front plate not only ensures an initial clearance with the container but also allows the front and rear of the container to be gripped with some force as the plates come together. These effects can be, achieved without varying at any time the rate of advance of the container and the speed of either conveyor. It will be understood that on reaching the exit end of the auxiliary conveyor top run, the presser devices are again collapsed. At this stage the result is an acceleration of the presser plate of the leading device and a retardation of the presser plate of the rear device. They are therefore separated from the container between them at the same time as they collapse, so that ample clearance is also ensured for free passage of the container at the exit region of the auxiliary conveyor. Because the front and rear presser devices 18,20 are mounted on separate pairs of conveyor bands 14a, 14b, the spacing between them can be adjusted by relative displacement of the bands if it is required to accommodate containers of different sizes. By providing different drive chains for the respective drive inputs 16a, 16b, this is simply a matter of altering the relative timings of the drive chains, without affecting the drive inputs. In some circumstances it may be possible to operate by varying the speed of only one presser device in the manner described at the entry to and/or exit from the container conveying path.

Claims: CLAIMS 1. Apparatus for operating on a partly erected container (C) entrained by a conveyor (2) to close opposite tabs (T) of the container against respective walls (W) extending transversely from an end wall (B) to the front and rear thereof in the direction of conveyor travel, comprising endless conveyor means (12) for conveying respective front and rear presser devices (18,20) for the front and rear tabs into the path of the container in the direction of the container conveyor travel, characterised in that the or each rear presser device (20)- is displaceable relative to said endless conveyor means (12) to retard the entry of said rear presser device into said path and/or the or each front presser device (18) is displaceable relative to said endless conveyor means to advance the entry of the front presser device onto said path, thereby to provide an increased clearance between said devices for the introduction of the container between them, and one or both said front and rear presser devices being thereafter displaceable in the opposite sense relative to the conveying means to reduce said clearance in order to urge said devices against said tabs to press them against the associated container walls. 2. Apparatus according to claim 1 wherein said displacements of the or each presser device (18,20) on the endless conveyor means (12) are arranged to be made at opposite ends of a run (12a) of said conveyor means parallel to said travel direction of the container conveyor (2) , said devices being thereby arranged to act on the container tabs when moving along said run. 3. Apparatus according to claim 2 wherein at least one of said front and rear presser devices (18,20) is mounted on the endless conveyor means (12) through a first pivot connection (24) having, an axis transverse to the travel direction, and a control mechanism is arranged to swing said presser device forwardly and rearwardly about said pivot connection for said advancement and/or retardation. 4. Apparatus according to claim 3 wherein the control mechanism of the front presser device comprises a linkage which includes a further piyptal connection (36) to the conveyor means (12) forwards of said first connection and radially outwards thereof, and a pivot link (32) extending rearwards from said further connection to a second pivotal connection (34) of the device radially outwards of its first pivot connection. 5. Apparatus according to claim 3 wherein said control mechanism of the rear presser device comprises a linkage which includes a further pivot connection (36) to the conveyor means (12) rearwards of said first connection and radially outwards thereof, and a pivot link (32) extending forwards from said further connection to a second pivotal connection (34) of the device radially outwards of its first pivot connection. 6. Apparatus according to any one of the preceding claims wherein means are provided on each presser device to transfer at least some of the reaction to the tab pressing forces to a rigidly fixed member (44) . 7. Apparatus according to any one of the preceding claims wherein the front and rear presser devices (18,20) are mounted on respective parallel conveyor bands (14A,14B) and means are provided for relative displacement between the respective bands to adjust the spacing of said devices. 8. Apparatus for closing opposite side tabs of a partly erected container (C) against respective front and rear walls extending transversely from an end wall from which said tabs project, comprising conveying means (2) for said container and an auxiliary continuous-band conveyor (12) adjacent to said conveying means and having front and rear return rollers (42) to form at least one substantially straight run (12a) between said rollers generally parallel to the direction of movement of said conveying means, at least one pair of front and rear presser devices (18,20) spaced along said auxiliary conveyor to circulate therewith, characterised in that each presser device has an articulated mounting on the auxiliary conveyor, said, mounting comprising first and second elements (26,28) fixed to the auxiliary conveyor at spaced positions along its length a pressing element (22) and a pivot link (32) having respective pivot connections to said first and second elements extending parallel to the said roller axes, said pivot link has a further pivot connection (34) to said pressing element, relative to the return roller axes said further pivot connection being radially outwards of the pivot connection of the pressing element to its mounting, the front presser device has its pivot link extending forwards from its pressing element and the rear presser device has its pivot link extending rearwards from its pressing element, whereby during travel around a return roller the curvature of the travel path for the each device increases the distance between said pivot connections to the first and second elements to cause the pressing element of the front presser device to swing from a forwardly tilted position to a rear position to retard its forward movement as said device enters said straight run and to cause the pressing element of the rear presser device to swing from a rearwardly tilted position to a forward position to accelerate its forward movement as said device enters said run, thereby to bring the pressing elements closer together to urge them against said opposite tabs against the container front and rear walls. 9. Apparatus for operating on a partly erected container (C) entrained by a conveyor (2) to close a tab (T) of the container against a wall (W) extending transversely from an end wall (E) to the front thereof in the direction of conveyor travel, comprising means (12) for conveying at least one presser element (22) for said tab in the path of the container in the direction of conveyor travel, characterised in that means (24,32,34,36) are provided for accelerating said presser element relative to the conveying means during the entry of said element onto said path in order to provide an increased clearance for the introduction of the container behind said element, and for retarding said element thereafter relative to the conveying means to reduce said clearance and urge it against said tab to press it against the associated container wall. 10. Apparatus for operating on a partly erected container (C) entrained by a conveyor (2) to close a tab (T) of the container against a wall (W) extending transversely from an end wall (E) to the rear thereof in the direction of conveyor travel, comprising means (12) for conveying at least one presser element (22) for said tab in the path of the container in the direction of conveyor travel, characterised in that means (24,32,34,36) are provided for retarding said presser element relative to the conveying means during the entry of said element onto said path in order to provide an increased clearance between said device for the introduction of the container in front of said element, and for accelerating said element thereafter relative to the conveying means to reduce said clearance and urge it against said tab to press it against the associated container wall.

Inventors: HADDOW PHILIP GORDON, VERNON GEOFFREY WILLIAM, HADDOW, PHILIP, GORDON, VERNON, GEOFFREY, WILLIAM
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1995
Main classification: B31B5
IPC codes: B31B1, B31B5