Ring machine for wrapping loads with stretch film

Abstract

The vertical and horizontal axis ring machine, for wrapping with stretch film usually palletized loads which are surrounded by the said ring and in which a suitable displacement between ring and load is envisaged so as to ensure that the latter is wrapped with film over the desired extension, comprises: a ring ( 5 ) with a diameter suitably greater than that of the maximum-size load (C) to be wrapped, which is made to rotate by drive means ( 9 ) mounted on a frame ( 2 ) which rotatably supports the said ring by means of support rollers ( 3 ) and containing rollers ( 4 ); there being mounted on the said frame ( 2 ) supporting the ring ( 5 ) means for supporting the reel ( 24 ) of stretch film and means for unwinding from it the film and for statically supplying it to: conveying means situated on the said rotating ring ( 5 ) and controlled by drive means situated on the said support frame ( 2 ), for collecting the film supplied from the said static supplying means, so as to keep it in the condition in which it is supplied by these means, so as to accumulate it in the form of annular turns superimposed on each other in an amount greater than that with which the innermost turn of this winding is supplied to the load to be wrapped (C), by supplying means situated on the said rotating ring ( 5 ); means ( 27 ) for temporarily retaining on the load to be wrapped the front end of the film unwound from the said last supplying means, abandoning the film when the wound turn is suitably fastened thereon, and which at the end of the load wrapping cycle intervene again in order to retain the new front end of the film, separating it from the tail end of the wound turn and fixing the latter onto the said wound turn performed.

1 ) Vertical and horizontal axis ring machine, for wrapping with stretch film usually palletized loads which are surrounded by the said ring and in which a suitable displacement between ring and load is envisaged so as to ensure that the latter is wrapped with film over the desired extension, characterized in that it comprises:  
     a ring ( 5 ) with a diameter suitably greater than that of the maximum-size load (C) to be wrapped, which is made to rotate by drive means ( 9 ) mounted on a frame ( 2 ) which rotatably supports the said ring by means of support rollers ( 3 ) and containing rollers ( 4 );  
     there being mounted on the said frame ( 2 ) supporting the ring ( 5 ) means for supporting the reel ( 24 ) of stretch film and means for unwinding from it the film and for statically supplying it to:  
     conveying means situated on the said rotating ring ( 5 ) and controlled by drive means situated on the said support frame ( 2 ), for collecting the film supplied from the said static supplying means, so as to keep it in the condition in which it is supplied by these means, so as to accumulate it in the form of annular turns superimposed on each other in an amount greater than that with which the innermost turn of this winding is supplied to the load to be wrapped (C), by supplying means situated on the said rotating ring ( 5 );  
     means ( 27 ) for temporarily retaining on the load to be wrapped the front end of the film unwound from the said last supplying means, abandoning the film when the wound turn is suitably fastened thereon, and which at the end of the load wrapping cycle intervene again in order to retain the new front end of the film, separating it from the tail end of the wound turn and fixing the latter onto the said wound turn performed.  
   
   
       2 ) Machine according to  claim 1) , in which the conveying means situated on the rotating ring ( 5 ) for collecting and accumulating the film supplied from the said static supplying means comprise a plurality of rollers ( 10 ,  11 ) which are parallel to the axis of the said ring, mounted rotatably at one of their ends on the said ring ( 5 ), with a height suitably greater than that of the film to be collected, and all or partly ( 10 ) having a side surface with a high coefficient of friction in relation to the wrapping film, for example a rubberized surface, and being connected together by means of a positive drive transmission and arranged in any suitable way so that they may all be rotated in the same direction and at a same appropriate speed by drive means ( 23 ) mounted on the said support frame ( 2 ) which in machines with a ring ( 5 ) having a vertical axis is actuated with a suitable raising/lowering movement.  
   
   
       3 ) Machine according to  claim 2) , in which the said final supplying means comprise at a short distance from one of the rubberized rollers ( 10 ) and kinematically connected to this roller a further pair of rubberized rollers ( 15 ,  115 ) which rotate with a speed ratio such as to subject the film which passes through them to a pre-stretching action of suitable magnitude.  
   
   
       4 ) Machine according to  claim 3) , in which the reel of stretch film ( 24 ), which may also have a large diameter, is arranged with a pair of first motor-driven pre-stretching rollers ( 25 ,  125 ,  26 ) on the said supporting and raising/lowering frame ( 2 ), in a position such that the film unwound from the reel and pre-stretched may be deposited on the cage formed by the said rollers ( 10 ,  11 ) supported by the ring, so as to form an accumulating store which allows the film subjected to the first pre-stretching the possibility of reacquiring elastic memory and being able to undergo a second pre-stretching (re-stretching) action upon passing through the said final second pre-stretching rollers ( 15 ,  115 ), upon leaving which the front end of the film is secured to known support means ( 27 ) situated on the side of the load to be wrapped.  
   
   
       5 ) Machine according to  claim 2) , in which the vertical-axis ring ( 5 ) is mounted rotatably underneath the support frame ( 2 ) and the rollers ( 10 ,  11 ) for collecting the film subjected to the first pre-stretching step are supported at one end by the said ring, are directed downwards and at the other end are interconnected by a second ring ( 12 ) which in turn may be connected by the upper ring to any internal structures in the form of a trellis.  
   
   
       6 ) Machine according to  claim 2) , in which the ring ( 5 ) has an external groove ( 105 ) on which at least one closed belt ( 6 ) is driven, said belt for a short section being separated from said ring and following a U-shaped path as a result of deflection by a pair of idle pulleys ( 7 ) and a driving pulley ( 8 ) keyed onto the shaft of a motor ( 9 ) supported by a cross-beam ( 102 ) of the said frame, which also supports the said idle pulleys ( 7 ).  
   
   
       7 ) Machine according to  claim 2) , in which the rollers ( 10 ,  11 ) which collect the film supplied from the static supplying means are of a number such as to form a cage which is polygonal in plan view and has a shape as close as possible to that of a circle and these rollers may all be rubberized or may alternately be rubberized and smooth and may all be motor-driven or motor-driven only partly, the remainder being idle.  
   
   
       8 ) Machine according to  claim 7) , in which the motor-driven rollers ( 10 ) are connected together at the top by means of pinions ( 13 ) and a chain ( 14 ) from which the last pair of rubberized pre-stretching rollers ( 15 ,  115 ) also obtains the driving movement via associated pinions ( 16 ,  116 ), respective pairs of pulleys ( 18 ) being keyed onto the shafts of the said motor-driven rollers and other idle pulleys ( 20 ) being situated for example on the shafts of the idle rollers ( 11 ) and a pair of closed and elastic belts ( 19 ) being driven on these pulleys, which belts for a short section follow a U-shaped path as a result of being deflected over pairs of idle rollers ( 21 ) and over a driving pulley ( 22 ) keyed onto the shaft of an electric motor ( 23 ) supported by the same side ( 102 ) of the supporting and raising/lowering frame ( 2 ) on which the said idle pulleys are mounted.  
   
   
       9 ) Machine according to  claim 7) , in which the motor-driven rollers ( 10 ) are connected kinematically by means of a ring with internal teeth which meshes with pinions keyed onto the shafts of the said rollers ( 10 ) and which has externally a groove so as to be able to be actuated by the static motor ( 23 ) by means of a belt, in the same way as the ring ( 5 ), it being envisaged that the final pre-stretching rollers ( 15 ,  115 ) obtain the driving movement from the closest of the rubberized rollers ( 10 ) or from a dedicated pinion, by means of a positive drive transmission.  
   
   
       10 ) Machine according to  claim 3) , in which means may be envisaged for ensuring that the motor ( 23 ) for rotation of the rollers ( 10 ) situated on the rotating ring ( 5 ) rotates at a constant speed or at a variable speed, so as to produce a variable supply of film from the final pre-stretching rollers ( 15 ,  115 ), depending on the characteristics and/or the shape and/or the size and/or the non-centred position of the load to be wrapped, it being envisaged that these variables may be entered via suitable means into the working program of the machine or that the latter may be equipped with means and an autodidactic program, at least as regards the shape, the size and the possible offset position of the load.  
   
   
       11 ) Machine according to  claim 10) , characterized in that, in order to ensure that the variations in speed of the motor ( 23 ) for rotation of the storage rollers ( 10 ,  11 ) cause corresponding variations in accumulation of the material on these rollers, special means may be envisaged for connecting together electrically the shafts of the said motor ( 23 ) and that of the motor ( 26 ) of the first pair of static pre-stretching rollers ( 25 ,  125 ) or for ensuring that these first pre-stretching rollers are actuated with take-off of the driving movement from the said motor ( 23 ).  
   
   
       12 ) Machine according to  claim 4) , in which a mechanical jockey device with one or more rollers may be envisaged downstream of any one or both the pairs of pre-stretching rollers ( 15 ,  115 ,  25 ,  125 ).  
   
   
       13 ) Machine according to  claim 10) , in which the weight created in an eccentric position on the ring ( 5 ) by the pair of final pre-stretching rollers ( 15 ,  115 ) and by the jockey device, where present, may be counterbalanced by a ballast weight ( 28 ) situated on an inner lug ( 305 ′) of the said ring ( 5 ), in a position diametrically opposite to the lug ( 305 ) with the said rollers ( 15 ,  115 ).  
   
   
       14 ) Machine according to  claim 4) , characterized in that, when a new reel ( 24 ) of film is loaded, at least during start-up of the said machine, means may be envisaged for activating a preliminary step during which the front end of the film is not fixed to the gripper ( 27 ), but is temporarily fixed to one of the final pre-stretching rollers ( 115 ), while the motor ( 23 ) is made to rotate at a speed such that the storage rollers ( 10 ,  11 ) do not rotate about their axes, so as to accumulate on these rollers a suitable quantity of film pre-stretched by the first pair of rollers ( 25 ,  125 ), so that the film has time to rest and reacquire sufficient elastic memory for the final re-stretching step, it being envisaged that only subsequently the front end of the film is fixed to the said gripper ( 27 ) and the machine is set to perform a normal wrapping cycle, with supplying of the film by the last pre-stretching rollers ( 15 ,  115 ).  
   
   
       15 ) Machine according to  claim 2) , in which the said rollers ( 10 ,  11 ) may be designed to support and to drive external belts ( 29 ) or a single band or web, so as to form a continuous-surface conveyor of the closed loop type and made of suitable material with a suitable coefficient of friction in relation to the film and on which the said film rests, thus being prevented from performing both transverse and longitudinal contracting movements.