Patent Publication Number: US-2013232914-A1

Title: Wrapping module for a bundling installation

Description:
The invention relates to an improvement to installations for packaging products in plastic film, commonly called bundlers, and more particularly to an improvement to the wrapping station where a plastic film is wrapped around successive batches of products. 
     This type of installation, as described in particular in document EP 0 403 079, extends between a machine for preparing products, such as bottles for example, and a tunnel for heat-shrinking the plastic film surrounding each batch of products. 
     This machine comprises arrangements which allow grouping batches before the actual bundling operation is performed, and these batches are then sequentially introduced, at a given pace, into the station which is referred to as the wrapping station. This wrapping station receives the batch of products, and at the same time receives a sheet of the heat shrinkable plastic material. It is at this wrapping station that the batch is wrapped with said plastic sheet. 
     The wrapping station comprises a wrapping table, which receives the batch of products, and a cycler with wrap bars which takes the plastic film and wraps it around the batch as the batch advances on said wrapping table. 
     The wrapping table therefore acts as a conveyor; it comprises an endless belt, which advances at a speed which is synchronized with the speed of the bars of the cycler in order to perform this operation of wrapping the batch with plastic film. 
     This indispensable synchronization between the conveyor belt and the cycler imposes certain constraints on the belt concerning its advancement, which must occur in a very precise manner. To obtain this result, the belt is subjected to relatively high stresses. These stresses have the effect of including this belt among the wear parts which must be replaced, and in particular among the parts which are preferably changed systematically without waiting for them to wear out, as that could have serious consequences during the normal operation of the installation. 
     However, it is difficult to access this belt when it is installed in a wrapping table; it is enveloped by the cycler which means any interventions will be time-consuming and involve multiple operators, which of course impacts the use of the machine. 
     The invention proposes a novel arrangement of this wrapping station, with an original arrangement of the wrapping table itself, such that this operation of changing the belt can be done under acceptable conditions, within a relatively short time, and without requiring the involvement of multiple operators. 
     The wrapping module of the invention comprises, combined in a cradle having a transverse cross-section in the shape of a U,—a wrapping table of which the ends of its structure each comprise one or more rollers for guiding an endless belt, and—a cycler having bars mounted on endless chains in order to revolve all around said wrapping table, characterized in that the structure of said wrapping table consists of laterally arranged side members which are extended by extensions in the form of retractable arms whose ends carry said rollers, and said structure is secured, by easily removable means, to at least one of the side walls of said cradle, said wall being in the form of a frame pierced with a window opening onto said wrapping table, said window having a dimension, in the longitudinal direction, which is less than the total length of the table but which is greater than the length of said table after retraction of its end arms, which will allow the removal of said endless belt and/or the insertion of another belt. 
     Still according to the invention, the active upper portion of the conveyor belt slides on a bed made of several parts, said bed comprising:—a fixed central plate carried by the side members, and—supplemental plates carried by the retractable arms which support the end rollers serving to guide said belt. 
     In another arrangement of the invention, the retractable arms which support the end rollers serving to guide the belt, can be vertically moved to allow retraction of their supplemental guide plate for the belt, and to allow positioning these supplemental plates under the fixed central plate. 
     Still according to the invention, the side members of the structure of the wrapping table comprise longitudinal slots which act as rails and which guide the attachment means for the retractable end arms during their retraction movement which allows positioning their supplemental plate under the fixed central plate. 
     In another arrangement of the invention, the structure of the wrapping table is secured to the windowed frame by means of brackets, in the form of angle brackets, which are removable and which, after their removal, leave said table in a cantilevered arrangement, supported by attachment means which are placed between its structure and the other wall of the cradle. 
     In another arrangement of the invention, the lower portion of the endless belt is wound around a motorized roller by means of two supplemental rollers arranged above and on each side of said motorized roller in order to wind said belt around half the surface area of said motorized roller, said supplemental rollers being secured to the structure of the table by quick-disconnect assembly means, of the simple screw type, which directly engage with a respective shaft onto which each supplemental roller is mounted. 
     In another arrangement of the invention, the side plates carried by the end arms abut against the fixed central plate, and, on one side, at least one fine-tuning adjustment device is placed between said arms and the side members of the structure, said adjustment device allowing moving the corresponding supplemental plate forward or back to adjust its gap relative to the bars of the cycler and/or relative to the bed or to a next adjacent belt. 
     The invention also relates to the conveying table itself, used in a bundling installation for the wrapping operation. From GB 2 041 315 and EP 1 493 692, conveying tables are known which can be used in a bundling installation for the wrapping operation, and each comprising a structure which is equipped, on at least one of its longitudinal ends, with supporting arms for one or more guide rollers for an endless conveyor belt, said supporting arms being movable, longitudinally retractable, in a manner that reduces the longitudinal dimensions of said table by appreciable proportions, said belt comprising an active upper portion which slides on a bed made of several parts, one part comprising a fixed central plate carried by side members and one part comprising at least one supplemental guide plate which is carried by said retractable arms that support said end roller(s) serving to guide the belt, which allows adjusting the tension of the belt and/or facilitates removal and replacement of the belt. 
     The conveying table of the invention, of the known type presented above, is characterized by said retractable arms being vertically movable to allow retraction of their supplemental guide plate for said belt and to allow positioning their supplemental guide plate under the fixed central plate. 
     Advantageously, the side members of the table structure comprise longitudinal slots which act as rails and which guide the attachment means for the retractable arms during their retraction movement which allows positioning their supplemental guide plate under the fixed central plate. 
     The longitudinal dimensions of the conveying table can thus be reduced by an amount on the order of 10 to 25% for example. 
    
    
     
       The invention is explained in a sufficiently clear and complete manner in the following description to enable its execution. This description is accompanied by drawings, in which: 
         FIG. 1  schematically represents the wrapping module of the invention, viewed from the side where the endless conveyor belt is removed; 
         FIG. 2  is a schematic half-view of a cross-section along II-II in  FIG. 1 , primarily showing the cradle which groups the active elements of this wrapping module; 
         FIG. 3  represents the module, viewed from the side opposite the side in  FIG. 1 , specifically from the side where the drive means for the wrapping module belt are located; 
         FIG. 4  shows a detailed schematic perspective view of a quick-connect element for attaching the structure of the wrapping table to the windowed frame of the cradle; 
         FIGS. 5 and 6  show the different operations involved in the extraction and/or replacement of the endless belt of the wrapping module. 
     
    
    
       FIG. 1  shows the wrapping module  1 , which is placed between an upstream conveyor  2  supplying the batches of products, under which one will note the plastic film injection table  3 , and a downstream conveyor  4  which conveys the batch of products, wrapped in its plastic film, to the heat-shrink tunnel, not represented. 
     This wrapping module  1  comprises a cradle  5  which is partially apparent in the transverse half-section represented in  FIG. 2 . This cradle  5  rests on the general frame  6  of the bundling installation and is in the shape of a U of which the bottom  7  rests on said general frame with two side walls which form frames, it being possible for said frames to be similar or different as explained below; they are labeled differently: one, frame  8 , is directly visible in  FIG. 1 ; the other, frame  9 , is directly visible in  FIG. 3 . 
     The cradle  5  is arranged to receive, between its two frames  8  and  9 , the wrapping table  11  and the cycler  12  which is diagrammed in  FIGS. 1 and 3 . This cycler  12  is simply represented by dotted and dashed lines illustrating a portion of the path of the bars of this cycler  12 , said bars  13  appearing in  FIG. 2 . 
     Still in  FIG. 2 , the cycler  12  comprises endless chains  14 , which carry the bars  13 , said chains  14  being laterally arranged and their path being defined in particular by guides  15  located on the inside face of the frames  8  and  9 . The bars  13  surround the wrapping table  11  in their movement. To allow the bars  13  to pass between the ends of this wrapping table  11  and the ends of the upstream conveyor  2  feeding the batches of products and the downstream entrance to the conveyor  4 , an appropriate gap is left between each end of said table  11  and, respectively, the downstream end of said feed conveyor  2  and the upstream end of the conveyor  4  located downstream. 
     The total length of the wrapping table  11  is determined by the distance between the upstream passage for the bars  13  of the cycler  12 , at the entrance to the wrapping module  1 , and the downstream passage for these same bars, at the exit from said wrapping module  1 , said distance being measured at the surface where the batches of products travel. 
     The wrapping table  11  comprises a structure  21  constituting its central portion, and two side extensions  22  which extend out to the path of the bars  13 . 
     The structure  21  laterally comprises side members  23 , said side members being joined by a plate  24 , visible in  FIGS. 2 and 4 , said plate  24  acting as a bed for the endless conveyor belt  25  which extends between the entrance and the exit of the wrapping module  1 . 
     These side members  23  also comprise means for receiving the motorized roller  26  which drives the belt  25  and for receiving the two supplemental rollers  27 , said rollers  27  being located above the level of the axis of the motorized roller  26  and on each side of the motorized roller  26 ; they allow winding the belt  25  around slightly more than half of the motorized roller  26 . 
     One will note in  FIG. 1  that the structure  21 , with its side members  23 , is inside the window  28  arranged in the side wall of the cradle  5  which forms the frame  8 . It is the extensions  22 , on each side of the central portion of the structure  21 , which give the wrapping table  11  a longitudinal dimension which is greater than the longitudinal dimension of the window  28 . 
     These extensions  22  each consist of laterally arranged arms  32 , said arms  32  constituting a kind of extension of the side members  23  and carrying, at their end, the roller(s)  33  which serve to guide the winding of the wrapping module belt  25 . 
     The arms  32  are connected to each other by a plate  34  which also acts as a bed for the belt  25 . This plate  34 , visible in  FIG. 4 , abuts with the central fixed plate  24  in order to create continuity in the guiding of the wrapping belt  25 . 
     The fixed central plate  24  laterally comprises, at the side members  23 , longitudinal slots  36  which act to guide the attachment means for the arms  32 , said attachment means consisting for example, as represented in  FIG. 4 , of a pair of screws  37  which engage with the end of each arm  32  which is positioned under the plate  24  and against the corresponding side member  23 . 
     Considering the presence of the plate  34  which is carried by the arms  32 , in order to be able to retract the extensions  22  it is necessary to move this extension  22  vertically downwards in order to allow said plate  34  to pass under the central plate  24 , as represented in  FIGS. 5 and 6 . 
     The wrapping table  11  is supported by and assembled onto the cradle  1  by means of its structure  21 , and in particular by the side members  23  of this structure  21 . The side members  23  are supported, on the frame  8  and window  28  side, by parts  41  in the form of angle brackets which rest on a supporting shelf  42  arranged in said frame  8 , in the lower portion of the window  28 . 
     The lower portion of the window  28  is arranged, as represented in  FIG. 1 , to have a contour which corresponds to that of the side members  23  of the structure  21  but with a significant gap between the two. 
       FIG. 1  shows the window  28  of frame  8 , meaning the side from which an operator can access the belt  25  and remove it for replacement when necessary. 
       FIG. 3  shows the other side of the cradle  1  with frame  9 , said frame  9  possibly being, for reasons of simplicity, arranged similarly to frame  8  with the same type of window. One will note a wheel  43  in  FIG. 3  which is secured to the motorized roller  26 , said wheel  43  being driven by the same drive means as the chains  14  on which the bars  13  are mounted, so that the two are driven in a synchronized manner and the operation of wrapping the batch of products with plastic film is carried out. 
     The presence of the drive system for the belt  25  on the frame  9  side complicates the belt changing operations, and it is for this reason that these operations are performed from the other side, where an operator can work easily without needing to execute multiple operations in order to free the belt  25  which, of course, can be cut apart when changing a worn belt but when new forms an envelope which it must be possible to thread onto the wrapping table  11  without ruining it. 
     For this belt  25  changing operation, a first operation is performed, as represented in  FIG. 5 , which consists of removing the attachment means for the supplemental rollers  27  that guide the belt  25  on its motorized roller  26 , said attachment means consisting, for example, of screws  44  which secure two shafts which each have a respective one of said rollers  27  mounted to it. Next, the operation consists of loosening the screws  37  which attach the arms  32  to the fixed central plate  24 , to free the extensions  22  to move downwards in order to retract each of the plates  34  and to place them under said fixed central plate  24 . 
     The changing operation then consists of removing the angle brackets  41  which support the table  11 , said table then being supported in a cantilevered manner by the angle brackets  45  located on the other side, on the frame  9  of the cradle  5 , said angle brackets  45  being attached to the side members  23  of the structure  21  and to the supporting shelves  46  which are arranged on said frame  9 , in the lower portion of the corresponding window. 
     To be able to remove the belt  25 , the operator retracts the extensions  22  by sliding them under the fixed central plate  24 , as represented in  FIG. 6 . The removal of the angle brackets  41  leaves the passage area for the belt  25  unobstructed, so that said belt  25  can be extracted by the operator from the front simply by sliding the belt transversely on the table  11 , above the supporting shelves  42  and, in general, above the lower contours of the window  28 . 
     After having installed a new belt  25 , the operator performs the reverse operation by restoring the angle brackets  41 , the supplemental rollers  27 , and, lastly, the side extensions  22 , with the plates  34  abutting against the central plate  24 . 
     One will note that supplemental means may be installed for making positional adjustments, for example such as an adjustment between plates  24  and  34 . A fine-tuning adjustment system, not represented, may be installed which allows adjusting the position of the end of the extensions  22  relative to the passage traveled by the bars  13 , said adjustment also making it possible to improve the position of the ends of the belt  25  relative to the bed or to the adjacent belt located downstream or upstream from the wrapping module  1 .