Patent Publication Number: US-2022227513-A1

Title: Unwinding apparatus for wrapping machine

Description:
The invention relates to apparatuses and machines for wrapping products with an extendable plastic film, and in particular it relates to an unwinding apparatus installable on a wrapping machine for unwinding, pre-stretching, selectively narrowing a band width of the film and deviating or directing the film towards a load to be wrapped. The latter generally consists of a product or a group of products, typically arranged overlapping on a pallet to form a so-called palletized load. 
     Unwinding apparatuses mounted on wrapping machines supporting a film reel from which the plastic film is unwound to be wrapped around the load so as to form a series of helix braided bands or strips, thanks to the combination of the vertical movement of the unwinding apparatus and the relative rotation between the latter and the load, are known. In particular, the unwinding apparatus and the load placed on the pallet rotate relative to each other with respect to a wrapping axis. 
     In wrapping machines equipped with a rotary table to support the load, the latter is rotated about a vertical wrapping axis, while the wrapping apparatus is moved vertically with alternating motion along a fixed column of the machine. 
     In ring or rotating arm wrapping machines, the load remains fixed during wrapping, while the unwinding apparatus, fixed to the ring or the rotating arm, is moved with respect to the latter both in rotation about and in translation parallel to the vertical wrapping axis. 
     The wrapping apparatus typically comprises a carriage that supports, in addition to the film reel, a pair of pre-stretching rollers arranged to unwind the film from the reel and pre-stretch or lengthen it, and one or more return rollers to deviate the film towards the load. By appropriately adjusting the difference between the rotational speeds of the pre-stretching rollers it is possible to pre-stretch the film by a defined amount or percentage and/or vary the unwinding speed of the film from the reel. 
     The plastic film is wrapped to completely wrap the load on all its sides. To stabilize the load when it is placed on a pallet it is also necessary to wrap the film around an upper portion of the pallet. If this is not done, the load could dangerously move relative to the latter during wrapping and/or subsequent transport. 
     In order to ensure adequate tension to the film and to ensure greater resistance to tensile forces caused, for example, by displacements or movements of the load, the film may advantageously be completely or partially wound in such a way as to reduce a band or strip width and at the same time create a film rope to be wrapped tightly around the load and in particular around an upper portion of the pallet. The rope, which is obtained by gradually wrapping or rolling a longitudinal edge of the film, allows a greater wrapping or pulling force than the full-band or full-strip film. 
     In order to wrap the film, in whole band or partially or totally rolled in a rope, around the upper portion of the pallet, in particular on the wrapping machines with rotating arm and on those with a rotating ring, suitable lifting means are provided capable of lifting the load to a height such that the film can also be wrapped around the upper portion of the pallet. The lifting means are inserted and associated with the conveyor that supports the load during the wrapping and allows it to be moved in and out of the machine. 
     Alternatively, unwinding devices are known that are mounted on the rotating arms or on the rotating rings of the machines so that they can be rotated, in particular oriented or tilted downwards so as to direct the film towards the upper portion of the pallet to be wrapped. 
     However, these known solutions have the disadvantage that they are quite complex and in any case expensive to be installed on wrapping machines. 
     WO2012/153285 discloses an unwinding apparatus associable with a machine for wrapping a load with a plastic film that includes a support element adapted to support a film reel, a set of rollers adapted to unwind and pre-roll the film, and a guiding roller capable of engaging and deviating the film leaving the rollers towards the load. The guiding roller is pivotally mounted on the support element so as to be tiltable by a defined tilting angle with respect to the rotation axes of the rollers to reduce a band width of the film wrapped around the load. 
     It is an object of the invention to improve the known unwinding apparatuses associable with wrapping machines and arranged to unwind, pre-stretch and narrow a band width of a plastic film to be wrapped around a load supported by a pallet. 
     Another object is to obtain an unwinding apparatus that allows to effectively and tightly wrap a load base to the pallet to optimally stabilize the aforementioned load. 
     A further object is to obtain an unwinding apparatus that allows a band width or width of the plastic film to be varied in a simple, rapid and effective manner during its wrapping around the load. 
     Still another object is to create an unwinding apparatus having simple and cost-effective construction. 
     These and further objects are achieved by an unwinding apparatus according to one or more of the claims set out below. 
    
    
     
       The invention can be better understood and implemented with reference to the attached drawings which illustrate some exemplifying and non-limiting embodiments thereof, wherein: 
         FIG. 1  is a front view of the unwinding apparatus associated with a wrapping machine, partially illustrated, and a load on a pallet, in an operating configuration; 
         FIG. 2  is a side view of the unwinding apparatus and the wrapping machine of  FIG. 1 ; 
         FIG. 3  is a plan view of the unwinding apparatus and the wrapping machine of  FIG. 1 ; 
         FIG. 4  is an enlarged view of the unwinding apparatus of  FIG. 1 ; 
         FIGS. 5 and 6  are front and side views of the unwinding apparatus associated with the wrapping machine and in a further operating configuration, respectively; 
         FIG. 7  is an enlarged view of the unwinding apparatus of  FIG. 5 ; 
         FIGS. 8 and 9  are front and side views, respectively, of the unwinding apparatus in the first operating configuration in a final phase of a wrapping cycle of the wrapping machine; 
         FIG. 10  is a top plan view of the unwinding apparatus and the wrapping machine of  FIG. 8 ; 
         FIGS. 11 and 12  are respectively front and side views of the unwinding apparatus in a phase of a wrapping cycle of the wrapping machine; 
         FIG. 13  is a front view of the unwinding apparatus associated with the wrapping machine, partially illustrated, in another operating configuration; 
         FIG. 14  is an enlarged detail of  FIG. 13  illustrating in particular first driving means of a guiding roller of the unwinding apparatus of the invention; 
         FIG. 15  shows an enlarged detail of  FIG. 10  showing in particular a first end portion of the guiding roller connected to supporting means and equipped with a roll. 
     
    
    
     With reference to  FIGS. 1 to 15 , an unwinding apparatus  1  is illustrated, associable with a wrapping machine  100  for wrapping a load  30  that includes, for example, a plurality of products arranged on a pallet  40  to form a palletized load, with a film  50  of extendable plastic material, having height or width L. 
     The wrapping machine  100  is, for example, a machine of the rotating arm type, known and therefore partially illustrated and described, provided in particular with a vertical arm  101  rotating about a vertical wrapping axis W and with vertical moving means  102  to support and move the unwinding apparatus  1  along the vertical arm  101  that is along a direction parallel to the wrapping axis W. The load  30  arranged on the pallet  40  is positioned on a roller conveyor or roller  103  of the wrapping machine  100 , said conveyor being able to move the load  30  with the pallet  40  in and out of the wrapping machine  100  itself. 
     It is to be noted that the wrapping apparatus  1  of the invention can also be mounted on a horizontal rotating ring type wrapping machine, or on a rotating platform and vertical support column wrapping machine. 
     The unwinding apparatus  1  comprises supporting means  2  for supporting a reel  60  of the film  50 , roller means  3 ,  4 ,  7  arranged to unwind and pre-stretch the film  50 , and a guiding roller  6  for engaging and deviating towards the load  30  the film  50  leaving the roller means  3 ,  4 ,  7 . The guiding roller  6  is rotatably mounted on the supporting means  2  so as to be tiltable with respect to longitudinal rotating axes X 1 , X 2  of the roller means  3 ,  4 ,  7  so as to reduce a band width of the film  50  wrapped around the load  30  and/or deviate the film  50  itself towards a supporting plane M adapted to support said load  30  and said pallet  40  during the operation of the wrapping machine  100 . 
     The roller means  3 ,  4 ,  7  comprise a first pre-stretching roller  3  and a second pre-stretching roller  4  cooperating to unwind and pre-stretch the film  50 . The pre-stretching rollers  3 ,  4  are rotated about respective longitudinal axes X 1 , X 2 , for example, by an electric motor  21  and a motion reduction and transmission assembly, or alternatively by respective electric motors. 
     The first pre-stretching roller  3 , called the fast roller, which is located downstream of the second pre-stretching roller  4 , called the slow roller, with respect to the movement of the film  50 , rotates about the respective longitudinal rotation axis X 1  faster than the second pre-stretching roller  4  (rotatable about the respective rotation axis X 2 ) so as to pre-stretch the film  50  by a defined amount or percentage. The roller means further include a plurality of return rollers  7 , parallel to the pre-stretching rollers  3 ,  4  and arranged to deviate the film  50  from the reel  60  towards the first pre-stretching roller  3  and the second pre-stretching roller  4  and from the latter towards the guiding roller  6 . 
     The unwinding apparatus  1  further comprises driving means  10  for tilting the guiding roller  6  with respect to the roller means  3 ,  4 ,  7  continuously in a plurality (theoretically infinite) of different operating positions along an adjustment stroke that is comprised between an initial operating position P 0 , in which the guiding roller  6  is substantially parallel to the longitudinal rotating axes X 1 , X 2  of the roller means  3 ,  4 ,  7  i.e. forms with said longitudinal rotating axes X 1 , X 2  a tilting angle equal to 0°, and a first operating position P 1 , in which said guiding roller  6  is tilted by a first tilting angle α 1  with respect to the longitudinal rotating axes X 1 , X 2 . 
     In the initial operating position P 0  the guiding roller  6  is parallel to the pre-stretching rollers  3 ,  4 , and the return rollers  7  and does not reduce a band width of said film  50  or deviate the latter towards the supporting plane M. 
     In the first operating position P 1  the guiding roller  6  is tilted by a first angle α 1  with respect to the longitudinal rotating axes X 1 , X 2  to reduce the band width of the film  50  and/or deviate it towards the support plane M on the load  30  and also on an upper portion  41  of the pallet  40 , when the unwinding apparatus  1  is arranged in a lowered position B in which it is closer to the supporting plane M. The first tilting angle α 1  is such as to allow to wrap an upper portion  41  of the pallet  40  having a height h between 40 and 60 mm, in particular equal to about 50 mm, with the film  50 . This wrapping height, or width, h, of the upper portion  41  of the pallet  40  allows, as demonstrated by numerous tests performed by the applicant, to secure the load  30  firmly to the pallet  40  to ensure greater resistance to tensile forces caused, for example, by displacements or movements of the load ( FIGS. 1-4 ). 
     The first tilting angle α 1 , in particular, is determined based on the type of wrapping machine  100 , the distance of the unwinding apparatus  1  from the load  40 , the dimensions and position of the latter with respect to the wrapping axis W, the physical characteristics of the wrapping film  50 , the pre-stretch percentage and the wrapping tension applied to the film  50 . 
     In the illustrated embodiment, the first angle α 1  is, for example, between 25° and 50°, in particular about 30°. 
     The guiding roller  6  includes a first end portion  16  rotatably connected to the supporting means  2  and an opposite second end portion  26  on which the first driving means  10  act. 
     More precisely, the first end portion  16  of the guiding roller  6  is mounted on a support element  15  that is rotatably fixed to the supporting means  2 . The support element  15  is rotatable around a transverse axis Y, in particular orthogonal, to a longitudinal axis X of the guiding roller  6  and substantially parallel to the supporting plane M. The first end portion  16 , i.e. the guiding roller  6 , is mounted neutrally on the support element  15  that is free to rotate around the longitudinal axis X. 
     The first end portion  16  is provided with a roll  8 , coaxial and rotatable with the guiding roller  6 , and provided with a groove  8   a  able to abut and partially roll up a longitudinal lower edge  50   a  of the film  50  leaving the roller means  3 , when the guiding roller  6  is tilted, in particular by the first angle α 1 , so as to realize a longitudinal rolled portion  51 . 
     More precisely, and as better explained in the following description, it has been surprisingly verified, after numerous tests carried out by the applicant, that tilting the guiding roller  6 , provided on the first end portion  16  of the roll  8 , in particular by the first angle α 1 , it is possible to wrap the load  30 , and also the upper portion  41  of the pallet  40 , with a film  50  in which the longitudinal lower edge  50   a  is partially rolled so as to form a longitudinal rolled portion  51  capable of conferring greater resistance to the film  50  in the wrapping. In fact, it occurs that, while leaving the roller means  3 ,  4 ,  7  the longitudinal lower edge  50   a  of the film  50  abuts the roll  8  and, besides being deviated, is also partially rolled thanks to the groove  8   a  ( FIGS. 5-7 ). 
     The unwinding apparatus  1  may also comprise folding means  5  interposed between the roller means  3 ,  4 ,  7  and the guiding roller  6 , movable and selectively activable to abut and roll at least the longitudinal lower edge  50   a  of the film  50  leaving the roller means  3 ,  4 ,  7  and realize a further longitudinal rolled portion  51 , the latter having larger dimensions than the longitudinal rolled portion  51  achievable with the roll  8  of the guiding roller  6 . 
     Thus, in one of the operating positions P 1 , P 2  of the guiding roller  6 , the latter is able to deviate the film  50  optionally provided with the longitudinal rolled portion  51  made by the roll  8 , in particular with the guiding roller in the first operating position P 1 , and/or the further longitudinal rolled portion  51 ′ made by appropriately activating and moving the folding means  5 , towards the load  30  and possibly also on the upper portion  41  of the pallet  40 . 
     In a variant of the unwinding apparatus  1  of the invention not illustrated in the figures, the folding means  5  interposed between the roller means  3 ,  4 ,  7  and the guiding roller  6  may be configured to abut and roll an upper longitudinal edge  50   b  of the film  50  and form an upper longitudinal rolled portion or be configured to abut both the upper longitudinal edge  50   b  and the longitudinal lower edge  50   a  of the film  50  and form the upper longitudinal rolled portion and the further lower rolled portion  51 ′. 
     With particular reference to  FIG. 4 , the folding means  5  comprise in the illustrated embodiment a folding element  25  interposed between the roller means  3 ,  4 ,  7  and the guiding roller  6  and selectively movable by second driving means  14 , of known type, along a narrowing trajectory so as to abut the longitudinal lower edge  50   a  of the film  50  and push it towards the upper longitudinal edge  50   b  of the film  50  so as to reduce a band width and at the same time create a longitudinal rolled portion  51 ′ of the film  50  in the form of a rope. With particular reference to  FIG. 14 , the first driving means  10  comprise a linear actuator, of an electrical or pneumatic type, connected to the supporting means  2  and acting on the second end portion  26  of the guiding roller  6 . 
     In the illustrated embodiment the first driving means  10  comprise, for example, a screw  11  and a nut screw  12 . The screw  11  has a first end  11   a  rotatably connected to the supporting means  2  and an opposite second end  11   b  rotated about a respective longitudinal axis by motor means  13 . The nut screw  12  is engaged with the screw  11  so as to move along the latter when the screw  11  is rotated by the motor means  13 . The nut screw  12  is pivotally connected to the second end portion  26  of the guiding roller  6 . The motor means  13  comprise an electric motor with integrated gear reducer. 
     The operation of the wrapping apparatus  1  of the invention, associated by way of example with the wrapping machine  100  with a rotating arm, provides for the rotation of said unwinding apparatus  1  slidably connected to the vertical arm  101  around the wrapping axis W and the rotation of the pre-stretching rollers  3 ,  4  to unwind the film  50  from the reel  60  and pre-stretch it by a fixed amount or percentage. 
     At an initial stage of the wrapping cycle, the guiding roller  6  can be arranged in an initial operating position P 0  in which it is parallel to the pre-stretching rollers  3 ,  4 , i.e. it forms the initial tilting angle α 0  substantially equal to 0° and in which the guiding roller  6  engages the film  50  without causing any narrowing or diversion towards the supporting plane M ( FIGS. 11 and 12 ). In this initial operating position P 0 , an width or height of the band or strip of film  50  wrapping the load  30  is substantially the same as the height or width L of the film  50  wrapped on the reel  60 , i.e., the height of the reel  60  itself. 
     To stabilize the load  30 , i.e. to wrap it more firmly, the guiding roller  6  may be tilted, in particular by the first angle α 1  in the first operating position P 1  so as to roll up the longitudinal lower edge  50   a  of the film  50  by the roll  8  provided with the groove  8   a  and realize the longitudinal rolled portion  51  in the form of a rope that allows for greater tensile strength of the film and obtaining a greater wrapping or pulling force on the load or pallet. 
     Alternatively or additionally, the folding means  5  may be actuated to allow the folding element  25  to abut and roll the longitudinal lower edge  50   a  of the film  50  leaving the roller means  3 ,  4 ,  7  and realize the further longitudinal rolled portion  51 ′. In other words, the longitudinal lower edge  50   a  may be rolled by the roller  8  of the guiding roller  6 , in particular in the first operating position P 1 , or by the folding means  5  or by the latter and the roll  8 . 
     It is noted that the longitudinal lower edge  50   a  of the film  50  may be wound in the form of a rope at any position of the unwinding apparatus  1  along the vertical arm  101 . 
     In particular, in the lowered position B of the unwinding apparatus  1 , the guiding roller, if tilted by the first driving means  10  by the first angle α 1  in the first operating position P 1 , is able to deviate the film  50  towards the load  30  and towards the upper portion  41  of the pallet  40  to secure the load  30  more firmly to the latter. In this configuration, the guiding roller  6  deviates towards the upper portion  41  of the pallet  40  the longitudinal rolled portion  51  of the film  50  made by the roller  8  so as to wrap the upper portion  41  of the pallet  40  with a plurality of turns ( FIGS. 1-6 ). 
     Note that due to the longitudinal rolled portion  51  and the tilting of the guiding roller  6  the band width of the wrapped film on the load and on the upper portion  41  of the pallet  40  is significantly less than the height or width L of the film  50  leaving the reel  60 . 
     After a predetermined number of wrapping turns, the folding means  5 , if used to roll the longitudinal lower edge  50   a  of the film  50 , are actuated so as to disengage the folding element  25  from the film  50  and the guiding roller  6  is repositioned from the first driving means  10  to the initial operating position P 0  with an initial tilting angle α 0  substantially 0° to allow the wrapping of the load  30  to be completed. 
     Alternatively, the guiding roller  6  may be tilted in one of a plurality of second operating positions P 2  of a respective second tilting angle α 2  to reduce the film band width in order to wrap a load having a height less than the height L of the reel  60  without the need to replace the latter. 
     At the end of the wrapping, the guiding roller  6  may be tilted in another of a plurality of second operating positions P 2  by a respective second tilting angle α 2  to reduce the film band width, for example to use gripping, cutting and welding means  105  of the wrapping machine  100  having reduced height and dimensions ( FIGS. 8, 9 and 13 ). 
     The second operating positions P 2  are therefore intermediate operating positions since the respective second tilting angles α 2  are between the initial tilting angle α 0  (equal to 0°) and the first tilting angle α 1  (for example equal to 30°). 
     As discussed above, the value of the second angle α 2  (i.e., the value of the reduction of the film band width) can then be determined from the height L of the film  50  leaving the reel  60 , from a height of the load  40  to be wrapped, or from the dimensions of the gripping, cutting and welding means  105  of the wrapping machine  100 . 
     Thanks to the unwinding apparatus  1  of the invention it is therefore possible to effectively and tightly wrap a load base  30  to the underlying pallet  40  to optimally stabilize said load  30  without using specific lifting means of the latter and/or without requiring rotation or tilting of the unwinding apparatus with respect to the support arm  101 . 
     It is also possible to easily, quickly and effectively vary a band width or width of the plastic film during its wrapping around the load and in particular vary it by a desired amount according to the specific needs, being able to position the guiding roller in a plurality of second operating positions P 2 . 
     It should be noted, in fact, that thanks to the first driving means  10  that allow to move and in particular tilt the guiding roller  6  continuously in a plurality (theoretically infinite) of different operating positions along the adjustment stroke, it is possible to position the guiding roller  6  rapidly and quickly, in addition to the first initial position P 0  (without deviating or reducing the film band width) and the first operating position P 1  (to reduce and deviate the film on the load  30  and on the upper portion  41  of the pallet  40 ), in a plurality of second operating positions P 2  to reduce the film band width by the desired amounts according to specific needs. 
     It should also be noted that the operating positions P 1 , P 2 , and in particular the first operating position P 1 , of the guiding roller  6  depend on a plurality of highly variable operating parameters and conditions, such as distance of the unwinding apparatus  1  from the load  40 , dimensions and position of the latter with respect to the wrapping axis W, characteristics of the film  50  (pre-stretch percentage and wrapping tension), but can be quickly and precisely identified in the unwinding apparatus  1  of the invention thanks to the first moving means  10 . 
     Finally, it should be noted that the unwinding apparatus  1  of the invention also allows to choose the type of cording to be applied to the base of the load  30  and/or to the upper portion  41  of the pallet  40  to optimally stabilize the load  30 . More precisely, for a firmer and more resistant wrapping, the folding means  5  can be used capable of abutting and rolling up a longitudinal lower edge  50   a  of the film  50  and creating a further longitudinal rolled portion  51 ′ on the film  50  having desired dimensions and therefore more or less resistant. 
     Alternatively, in the case, for example, of lighter load or of limited size, the folding means  5  may not be used, since the coaxial and rotatable roll  8  with the guiding roller  6  and provided with a groove  8   a  allows to realize a longitudinal rolled portion  51  having smaller dimensions than the further longitudinal rolled portion  51 ′ achievable with the folding means  5 , but still able to confer greater resistance to the film. 
     Alternatively, both the folding means  5  and the roll  8  of the guiding roller  6  may be used to abut and roll up the longitudinal lower edge  50   a  of the film  50 . 
     The unwinding apparatus  1  thanks to the use of the first driving means  10  comprising a screw-nut screw linear actuator also has a simple and cost-effective construction.