Patent Publication Number: US-11649081-B2

Title: Wrapping machine

Description:
The invention concerns machines for wrapping a load with a cold-stretchable plastic film or wrap and, in particular, concerns a wrapping machine with horizontal rotating-ring. 
     The known wrapping machines with horizontal rotating-ring comprise a main frame to which a secondary frame or supporting carriage is slidably connected, arranged for rotatably supporting a ring structure, or ring, to which a film unwinding equipment is attached. 
     The ring rotates about a vertical wrapping axis, while the supporting carriage linearly moves along a line parallel to the wrapping axis. In doing so, the film unwinding equipment is movable along, and about, the wrapping axis while the load to be wrapped remains fixed. 
     The unwinding equipment houses and supports a reel of film and is generally provided with a pair of pre-stretching rollers which unwind the film from the reel and stretch or elongate it, and one or more return rollers that divert the film towards the load. The latter is typically composed of one or more products grouped and arranged on a pallet. 
     The film unwound from the reel is wrapped around the load in such a way as to form a series of intertwined strips or bands of a helical shape thanks to the combination of the linear movement and the rotation of the unwinding equipment. 
     Suitable actuating means is provided for the vertical movement of the carriage and therefore of the ring, which comprises an electric motor that is located on the top of the main frame and acts on the carriage by means of suitable transmission means. 
     The placement of the electric motor on the top of the main frame prevents cluttering the lower part or base of the wrapping machine and allows for free movement of the load, its wrapping and the carrying out of operations on the film and/or load (fixing the end of the film, insertion of angular elements to protect corners, etc.). At the same time, its elevated position makes it possible to simplify the structure of the transmission means connecting the electric motor to the supporting carriage. 
     A disadvantage of this solution lies in the fact that carrying out maintenance on the engine and the transmission means is awkward and inconvenient for the operator, who must place himself at the top of the main frame. In some cases, for safety requirements imposed by national regulations, appropriate supporting structures such as platforms or balconies must be provided on the main frame which allow the operator to safely access and work on the engine and the transmission means. 
     However, in addition to being expensive these supporting structures are bulky and prevent, for example, closer placement of multiple wrapping machines in a line. 
     Document EP 1454827 illustrates a wrapping machine provided with a fixed frame that is supported by a base comprising four upright vertical columns along which a lifting frame is vertically movable, moved by a lifting motor. The lifting frame rotatably supports a supporting ring that is driven by a rotating motor to which a al quale is fixed a unit for supplying a wrapping film. The lifting motor  6  of the lifting frame and the rotary motor of the supporting ring are placed on the lifting frame. 
     An object of the invention is to improve the known wrapping machines arranged to wrap a load with a film of plastic material, in particular wrapping machines provided with a horizontal rotating ring fixed to a vertically movable supporting carriage. 
     Another object is to realize a wrapping machine provided with actuating means of the supporting carriage which is easily and conveniently accessible by an operator and at the same time reliable and safe. 
     A further object is to realize a wrapping machine which has a reduced overall size in plan view and allows for different arrangements in relation to the forward direction of the loads to be wrapped. 
     These and other objects are achieved by a wrapping machine according to one or more of the following claims. 
    
    
     
       The invention can be better understood and implemented with reference to the attached drawings that illustrate an embodiment, by way of non-limiting-example, wherein: 
         FIG.  1    is a schematic perspective view of the wrapping machine according to the invention; 
         FIG.  2    is a front view of the wrapping machine of  FIG.  1   ; 
         FIG.  3    is an enlarged sectional view along the line III-III of  FIG.  2   . 
     
    
    
     With reference to  FIG.  1   , a wrapping machine  1  according to the invention is schematically illustrated, arranged to wrap a load, not illustrated, with a plastic film  50 , in particular a cold-stretchable plastic film. 
     The wrapping machine  1  comprises a main frame  2  provided with at least two supporting columns  3 , for example two, having respective upper portions  3   a  interconnected by beam means  4 , and a supporting carriage  5  slidably supported by the main frame  2  and moved by first actuating means  10  along a working direction A, in particular substantially vertical. 
     The main frame  2  is also provided with a connecting tie rod  34  which connects the two lower portions  3   b  of the supporting columns  3  so as to structurally stabilise and strengthen the aforesaid main frame  2 . 
     A moving ring  6  is rotatably supported by the supporting carriage  5 , or carriage, and is driven by second actuating means  20  rotatably around a wrapping axis X that is parallel to the working direction A. The moving ring  6 , or ring, is therefore arranged horizontally, parallel to a supporting plane B of the wrapping machine  1 . 
     The latter comprises at least one unwinding unit  7  fixed to the moving ring  6  and provided with a reel  51  of film  50  and with roller means  52 ,  53  for unwinding and pre-stretching the film  50 . More precisely, the unwinding unit  7  comprises a pair of pre-stretching rollers  52 ,  53 , which unwind the film  50  from the reel  51  and stretch or lengthen it, and one or more return rollers that divert the film  50  toward the product or group of products forming the load to be wrapped. 
     The first actuating means  10  comprises a first actuator  11  mounted on said main frame  2  at a lower portion  3   b  of one of the supporting columns  3  at a defined distance H from the supporting plane B of the wrapping machine  1 . In particular, in the embodiment illustrated in the figures, the first actuator  11  is directly mounted on, and fixed to, a lower portion  3   b  of one of the supporting columns  3 . Alternatively, the first actuator  11  can be mounted on, and fixed to, the connecting tie rod  34 , at a lower portion  3   b  of one of the supporting columns  3 . 
     The first actuator  11  is arranged to actuate in rotation a driving shaft  12  about a respective longitudinal axis. The latter is rotatably supported by the beam means  4  and is provided with at least one driving pulley  13  engaged with a flexible element  14  connected to the carriage  5 . 
     The driving pulley  13 , by rotating with the driving shaft  12  actuated by the first actuator  11 , moves the flexible element  14  and therefore the carriage  5  along the working direction A. 
     More precisely and in the illustrated embodiment, the flexible element  14  comprises a first end  14   a  fixed to the supporting carriage  5  and a second end  14   b  fixed to a counterweight  15  slidably housed within one of the supporting columns  3 , in particular inside the supporting column  3  where the driving pulley is located. 
     In the embodiment illustrated in the figures, the driving shaft  12  comprises a pair of driving pulleys  13  positioned at opposite ends of the aforesaid driving shaft  12  and at the supporting columns  3 . 
     The driving pulleys  13  are engaged by, and move, respective flexible elements  14  having first end  14   a  connected to the carriage  5  and second end  14   b  connected to respective counterweights  15 , each of which is slidably housed within a corresponding supporting column  3 . 
     Each flexible element  14  comprises a toothed belt or a chain that engages or meshes with the corresponding driving pulley  13  provided with suitable teeth. 
     In a variant of the wrapping machine  1  of the invention, which is not shown in the figures, the first actuating means  10  of the supporting carriage  5  does not comprise counterweights, but at least one flexible element which is closed in a ring and wound around the respective driving pulley and around an opposite return pulley, for example housed in the lower portion  3   b  of the respective supporting column  3 . The supporting carriage  5  is therefore attached to the flexible element at one of its two straight segments interposed between the two driving pulleys and return pulleys and moves with it along the working direction A. 
     In another variant of the wrapping machine of the invention, which is not shown, the first actuating means  10  of the supporting carriage  5  does not comprise counterweights, but at least one flexible element in the form of a chain that winds with the teeth of the respective driving pulley and comprises a first end fixed to the supporting carriage  5  and a second free end which rests with its own weight on the opposite side with respect to the driving pulley. 
     The first actuating means  10  further comprises connecting means  16 ,  17  to connect or mechanically connect the first actuator  11  to the driving shaft  12 . The connecting means comprises, for example, a transmission shaft  16  and an angular gearbox  17 . The transmission shaft  16  is almost parallel to the working direction A and fixed to the supporting column  3 , which supports the first actuator  11 , so as to rotate about a respective longitudinal axis. The transmission shaft  16  connects the first actuator  11  to the angular gearbox  17 , which is in turn connected to the driving shaft  12 . 
     The first actuator  11  comprises a rotary electric motor able to rotate the transmission shaft  16  and therefore the driving shaft  12  and the driving pulleys  13 . 
     A speed reducer  18  of the first actuating means  10  is mounted on the main frame  2 , at the lower portion  3   b  of the supporting column  3 , interposed between the first actuator  11  and the transmission shaft  16  to reduce and control the speed of rotation of the latter and hence of the carriage  5 . 
     In a variant of the wrapping machine  1 , which is not illustrated, the first actuator can comprise a gearmotor wherein the electric motor and the speed reducer are integrated in a single unit. 
     In the embodiment illustrated in the figures, the first actuator  11 , provided with the speed reducer  18 , and the transmission shaft  16  are attached to an outer side of the supporting column  3 , on the opposite side with respect to an inner zone of the wrapping machine where the load is wrapped. 
     However the first actuator  11  and the transmission shaft  16  can be fixed to a side of the supporting column  3  closest to the inner zone of the machine in order to limit the external dimensions of the latter. 
     It should be noted that the first actuator  11  and the speed reducer  18  are positioned at a predetermined height H from the ground that allows an operator to easily access them for maintenance without the need to use ladders, scaffolding or similar. This significantly reduces the time required to carry out operations on the first actuator  11  and the speed reducer  18  and limits the risks to the operator&#39;s safety. 
     In a version of the wrapping machine  1  of the invention, that is not illustrated, the connecting means of the first actuating means  10  can comprise, for instance, a toothed belt or a chain which connect a first toothed pulley or wheel, mounted on the driving shaft  12 , to a second toothed pulley or wheel driven by the first actuator  11  or by the speed reducer  18  driven by the latter. 
     The carriage  5  is slidably mounted on the supporting columns  3  by means of guide means  9  of a known type which enables the translational motion of the carriage  5  and the ring  6  along the vertical working direction A in both directions with reduced friction. 
     The second actuating means  20  comprises a second actuator  21  mounted on the carriage  5  and arranged to operate or rotate the ring  6  by means of belt means  22 . More precisely, the second actuator  21  comprises a respective rotary electric motor which rotates, through a further speed reducer  23 , a driving pulley engaged to a belt of the belt means  22 , which can be wrapped around the ring  6 . 
     The beam means comprises a straight beam  4 , for example provided with a casing  31  defining a compartment  32  adapted to receive the driving shaft  12  and the driving pulleys  13 . A plurality of supporting elements  33  are fixed to the beam  4 , in particular inside the casing  31 , for rotatably supporting the driving shaft  12 . 
     The portal structure of the main frame  2 , provided with two supporting columns  3  which are opposite and facing each other, makes it possible to position the wrapping machine  1  with the supporting columns  3  adjacent to a supporting table or to a load conveyor, i.e. with the main frame  2  (i.e. the beam  4  and the tie rod  34 ) inclined or oblique with respect to a forward direction of the load through the machine  1 . 
     With this inclined placement, it is possible to place multiple wrapping machines  1  side by side in a line while minimising the overall dimensions. 
     In a version of the wrapping machine  1  of the invention, which is not illustrated, the main frame  2  can include three or four supporting columns  3 , in this case with the beam means comprising a plurality of beams fixed to the upper portions of the supporting columns and mutually interconnected to form an upper connecting frame.