Patent Publication Number: US-11377239-B2

Title: Process for operating a machine for wrapping products with a thermoplastic film

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to PCT International Application No. PCT/IB2018/053846 filed on May 30, 2018, which claims priority to Italian Patent Application No. 102017000060353 filed on Jun. 1, 2017, the entirety of the disclosures of which are expressly incorporated herein by reference. 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not applicable 
     BACKGROUND 
     The subject of the present invention is an operating process of a wrapping machine for products, in particular paper products, of non-woven fabrics or the like, for producing packages with a film of thermoplastic material unwound from a reel. 
     The machine subject of the present patent application has the aim of enabling a rapid packaging of products with efficient seals, thanks to the use of appropriate pressing devices provided in the sealing and transversal cutting assembly of the tubular film wrapping, said assembly being mounted on a mobile carriage which, with means adapted to move further away from and closer to the mandrel with tie elements that produces said tubular wrapping, with an operating sequence such that, while a new tubular package is pulled forward by the sealing and cutting assembly provided with pressing devices, sealing the head of said package and the tail of the package downstream, said new package is quickly filled with products by a pusher, avoiding the risk of the seal breaking due to the pressure of the air trapped in the same package in front of the product, thanks to the presence of one of the aforementioned pressing devices which isolates the seal from the effect of said pressure of the air. 
     However, the product packages made with the machine described above have the drawback that the film is relatively loose and therefore does not adhere to the packaged products in an optimal manner. 
     The present invention intends to overcome this drawback with an operating process that allows packages to be achieved wherein the tubular wrapping of film intimately adheres to the products placed within the package and this brings several advantages, and in particular a minimum use of film, an improved aesthetic appearance of the package and the possibility of packaging rigid products, such as for example, boxes for paper towels, without having to resort to a supplementary thermal shrinkage step, which is a step currently being used, with savings in production costs and a reduction in operating times. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the process according to the invention and the apparatus for its implementation, will become clearer from the following description made with reference to the five tables of figures of the attached drawings, wherein 
         FIGS. 1 and 2  are respectively schematic lateral elevation and top plan views of the components of the wrapping machine, illustrated during a first working step; 
         FIG. 3  is a schematic and transversal section view of an area of the mandrel that produces the tubular wrapping of film, shown along the line III-III of  FIG. 2  that illustrates the mandrel in a closed position, with a reduced transversal profile; 
         FIGS. 4 and 5  are respectively schematic lateral elevation and top plan views of a subsequent working step of the wrapping machine; 
         FIG. 6  is a transversal section of the mandrel shown along the line VI-VI of  FIG. 5 , which illustrates the mandrel in an open position having a wider transversal profile; 
         FIGS. 7 to 10  schematically illustrate subsequent working steps of the wrapping machine; 
         FIG. 11  schematically illustrates in a top plan view the working step of the machine of  FIG. 10 ; 
         FIGS. 12 and 13  are respectively schematic lateral elevation and top plan views which illustrate a further working step of the machine; 
         FIG. 14  is a transversal and schematic view of the mandrel of the machine that produces the film tubular wrapping. 
     
    
    
     DETAILED DESCRIPTION 
     With reference firstly being made to  FIGS. 1 to 3  of the drawings, the number  1  denotes a loading station of a known type, in which products P are placed, such as for example rolls of toilet paper, rolls of paper towels for the kitchen, packs of serviettes, paper towels, boxes for paper towels and the like, which are grouped and/or stacked together to form the bundle to be packaged. 
     Said station  1 , can be adjusted according to the shape of the packages to be produced, and is provided with means  2  for aiding to slightly compress the bundle of products so as to ease their insertion into the mandrel  3  that forms the tubular wrapping of film by means of an appropriate pusher, as will be better described in the following. 
     The mandrel  3 , is arranged immediately downstream of the loading station  1 , it is provided with means  4  shaped as a forming shoulder and is axially hollow with a preferably rectangular shaped transversal profile and can be adjusted with known means and, together with the forming shoulder  4 , for adapting to the shape/size of the packages to be made. 
     The film  5  coming from a reel not illustrated, thanks to known guide means, assumes a tubular shape  105  entering from the left end of the mandrel  3 , for those who are looking at the figures, running longitudinally and outside along the mandrel itself with longitudinal lengths of the film being partially overlapped and joined thanks to a longitudinal seal SL made by an appropriate sealing device  6  so that when the same film exits the mandrel it takes on the shape of the tubular casing. 
     A pusher  7 , thanks to appropriate actuating means, can slide horizontally for pushing the bundle of products P from the loading station  1  through the mandrel  3  and outside of the mandrel itself so as to arrive at the working area of a transversal sealing and cutting assembly  8 , mounted on a carriage  9  which is also horizontally mobile with appropriate means, said assembly also carrying pressing devices which pinch the ends of the tubular film casing for conveying the latter away from the mandrel. 
     Said assembly  8  is formed by two elements  108  and  208  both vertically mobile with a self-centering movement. 
     Downstream of the mandrel there is a conveyor  10 , the packages that exit the mandrel are arranged on the top branch of this conveyor and on said top branch, at the area of the vertical working plane of the elements  108 ,  208  of the sealing and cutting assembly  8  a transversal opening  11  is provided which, during the working steps of the machine can be open or closed due to the presence of a secondary carriage  12  mounted on the primary carriage  9  and provided with a horizontal movement independent from the movement of said primary carriage and capable of opening and closing said opening  11 . 
       FIGS. 1 and 2  illustrate the working step of the machine in which a bundle of products P is positioned in the loading station  1  and the mandrel  3  is closed, in the direction indicated by the arrows FC of  FIG. 3 , so as to have an appropriately reduced transversal section in respect to the overall transversal dimensions of the bundle. 
     For carrying out said adjustment of the mandrel  3  and its forming shoulder  4 , the same means are used, of a known type and not shown, for the adjustment of the mandrel itself according to the shape/size of the products to be packaged. 
     In this step, with the sealing device  6  in an active working position for performing the longitudinal seal SL of the superimposed edges of the film, the assembly  8  conveyed by the primary carriage  9  with the closed elements  108 ,  208  has arrived at the end stop position to the right, for those who are looking at the figures, dragging the newly formed tubular casing away from the mandrel  3  and performing the seal ST 2  and the transversal cut of the tail of a last completed package C and simultaneously performing the seal ST 1  of the head end of the tubular film casing, which is still empty and ready to house the new bundle present in the loading station. 
     In  FIGS. 4 and 5  a subsequent working step is illustrated wherein the elements  108 ,  208  of the assembly  8  are opened, the completed package C starts to move away from the top branch being unloaded from the conveyor  10 , the sealing device  6  is arranged in a rest position and the mandrel  3  opens transversally, in the direction indicated by the arrows FA of  FIG. 6 , by appropriately widening the length of the tubular film casing arranged outside the mandrel itself without encountering any risk of breakage due to the elastic properties of the thermoplastic film. 
     The means  2  which intervene in rapid succession and according to a known solution, perform a slight compression of the bundle of products P present in the loading station to an extent that allows them to be inserted in the mandrel thanks to the advancing of the pusher  7  as illustrated in the operating step of  FIG. 7 . 
     In said step, the secondary carriage  12  intervenes to almost completely close the transversal opening  11  of the top branch of the conveyor  10  so as to appropriately support the new package that will be subsequently produced and the primary carriage  9  and the assembly  8  connected thereto, start their step of retracting towards the mandrel  3 , while the finished package C is externally unloaded. 
       FIG. 8  illustrates an intermediate working step wherein the pusher  7  advances towards the right continuing the insertion of the bundle of products P inside the mandrel  3 , while the primary carriage  9  and the assembly  8  continue to retract back towards the mandrel  3 , with the opening  11  that remains in a closed position. 
     In  FIG. 9  a processing step of the machine is illustrated in which, the pusher  7  has arrived at the end stop pushing, during its advancing, the bundle of products P of the new package C 1  against the head end of the tubular film casing, closed by the transversal seal ST 1 , while the carriage  9  and the assembly  8  have arrived at the end of their retraction in proximity to the mandrel  3 . 
     In  FIGS. 10 and 11  a working step is illustrated wherein, the secondary carriage  12  goes to a backwards position towards the right, for widening the opening  11  of the top branch of the conveyor  10  thus freeing the operating space for the vertical and auto-centering movement of the elements  108 ,  208  of the sealing and cutting assembly  8  provided with pressing devices. 
     Before the intervention of said elements  108 ,  208 , on the sides of the tubular film casing between the mandrel and the new package C 1 , lateral folding units, which are not illustrated, intervene to make recessed bellows, as is known in the art. 
     In rapid succession the elements  108 ,  208  close with an auto-centering movement, by pinching the rear end of the new package C 1 . 
     In this step said elements  108 ,  208  can be partially closed, using only the pressing devices, which pinch the film, or can be completely closed, thus immediately achieving the seal ST 2  of the tail of the package C 1 , the seal ST 1  of the head of the new tubular film casing and the relative cut between said seals. 
     In the same operating step the mandrel  3  is transversally closed returning to the configuration illustrated in  FIG. 3  and the pusher  7  starts to retract through the mandrel itself so as to reach the position upstream of the loading station  1  of the products P. 
     In  FIGS. 12 and 13  a further operating step is illustrated wherein, the longitudinal sealing device  6  returns to its active working position and the elements  108 ,  208  in a closed position, advance towards the right, for those who are looking at the figures, dragging the empty tubular film casing and during said travel, in the case that the same elements are only partially closed, only by active pressing devices, the sealing and cutting operation of the film is carried out by means of appropriate components present in the same elements  108 ,  208 . 
     In the same working step, products P of a new bundle to be packaged are positioned in the loading station  1 , and the cycle is repeated by returning to the operating step of  FIG. 1 . 
     Purely by way of example in the drawings, a mandrel  3  is illustrated in a schematic manner, formed by four guide elements with angular profiles, but it should be understood that according to the shape/size of the products to be packaged, the mandrel can also be provided with further flat guide elements arranged at the centre of each side of the mandrel itself. 
     In the process, according to the present invention a preferred embodiment is described wherein for the forming of the tubular film casing with a reduced transversal profile, a movement of the elements that formed the mandrel  3  only in the transversal direction, as indicated by the arrows FC and FA in the  FIGS. 3, 6 and 14 , but it should be understood that according to a further implementation variation, for achieving an even narrower tubular film casing, said elements that form the mandrel can also be height adjusted, at least with its top components, as indicated by the arrows FH of  FIG. 14 . 
     The process according to the present invention can be used on a wrapping machine provided with both a mandrel formed by elements that do not provide channels, and with a mandrel with elements that provide longitudinal channels used to rapidly extract the pressurised air that tends to form in the package during the insertion therein of the products to be packaged. 
     Said second embodiment provides for the use of a mandrel provided with channels for expelling the air towards the outside of the packages, is subject of the patent application n. 102015000077005 in the name of the same applicant. 
     It should be understood that the process described herein can be subject to all these modifications, while remaining within the scope of protection of the present invention, as described, illustrated and as claimed in the following.