Apparatus for the production of reels of extendable film prestretched longitudinally

Abstract

Apparatus for the production of reels of extendable film prestretched longitudinally and of varying weight, from normal reels of extendable film, characterized in that it comprises a container ( 1 ) closed by a cover ( 3 ) inside which means for rotatably supporting a reel (B) supplying the extendable film as well as parallel prestretching rollers ( 8, 108 ) and a spindle ( 15 ) for storing the prestretched film are arranged, these means being all operated by a centralized drive unit ( 7 ) and means being envisaged for programming the operation of the apparatus, for the production of reels of prestretched film with the weight required in each case.

1 ) Apparatus for the production of reels of extendable film prestretched longitudinally and of varying weight, from normal reels of extendable film, characterized in that it comprises a frame or container ( 1 ) closed by a cover ( 3 ) inside which means for rotatably supporting a reel (B) supplying the extendable film as well as parallel prestretching rollers ( 8 ,  108 ) and a spindle ( 15 ) for storing the prestretched film are arranged, these means being all operated by a centralized drive unit ( 7 ) and means being envisaged for programming the operation of the apparatus, for the production of reels of prestretched film with the weight required in each case.  
   
   
       2 ) Apparatus according to  claim 1) , in which the container ( 1 ) rests on the ground with special feet ( 2 ), is open upwards and is closed by a cover ( 3 ) wholly or partly made of transparent material for allowing viewing of the components inside the said container, this cover being hinged on one end ( 103 ) of the said container ( 1 ) and being provided at the other end with a gripping handle ( 203 ) for raising and lowering.  
   
   
       3 ) Apparatus according to  claim 2) , characterized in that when the cover ( 3 ) is in the position for closing the container ( 1 ), it is envisaged that it activates a safety microswitch ( 4 ) which automatically stops operation of the apparatus if the said cover is raised during a working cycle of the said apparatus in question.  
   
   
       4 ) Apparatus according to  claim 1) , in which the means for rotatably supporting about its horizontal axis the reel (B) supplying the extendable film consist for example of a pair of parallel and idle rollers ( 5 ) which are positioned transversely on the bottom of the container ( 1 ) and on which the said reel of film (B) is rested along its generatrix.  
   
   
       5 ) Apparatus according to  claim 1) , in which the means for rotatably supporting about its horizontal axis the reel (B) supplying the extendable film are equipped, for example, with bearing-type supports for supporting the ends of a spindle which is mounted axially inside the said reel (B).  
   
   
       6 ) Apparatus according to  claim 1) , in which, parallel to the axis of the reel (B) supplying the extendable film, the sidewalls ( 101 ) of the frame or container ( 1 ) rotatably support a shaft ( 6 ) which is keyed to the slow output of a gearmotor ( 7 ) which is bracket-mounted on the outside of a said sidewall ( 101 ), a rubber-coated roller ( 108 ) being keyed onto this shaft, and which has keyed, on one end, a small-diameter gearwheel ( 9 ) which meshes with a larger-diameter gearwheel ( 10 ) keyed onto the end of a rubber-coated roller ( 8 ) parallel to the preceding rubber-coated roller ( 108 ), positioned above the latter and rotatably supported by a shaft ( 11 ) which connects together a pair of parallel arms ( 12 ) mounted with the possibility of pivoting on the said drive shaft ( 6 ), it being envisaged that the film (Z) unwound from the supply reel (B) is conveyed around the top half of the slow rubber-coated roller ( 8 ) and then around the bottom half of the fast rubber-coated roller ( 108 ) so that, when passing from one roller to the other roller, the said film undergoes the desired longitudinal prestretching.  
   
   
       7 ) Apparatus according to  claim 6) , in which the gearwheels ( 9 ,  10 ) may be arranged inside a special associated casing or inside a lateral cavity of the container ( 1 ) so as to be protected, lubricated if necessary with suitable means and replaced if necessary if it is required to modify the relative rotational ratio of the rubber-coated prestretching rollers ( 8 ,  108 ).  
   
   
       8 ) Apparatus according to  claim 6) , in which as a result of the weight of the slow upper rubber-coated roller ( 8 ) and since the arms ( 12 ) which support this roller are preferably unable to go beyond the vertical position, the said rubber-coated roller ( 8 ) cooperates by means of gravity and tangentially with the reel (B) supplying the extendable film, so as to cause it to rotate about its axis at the appropriate speed and in the appropriate direction for supplying the film to the prestretching rollers.  
   
   
       9 ) Apparatus according to  claim 6) , in which special means are envisaged for keeping the slow upper prestretching roller ( 8 ) temporarily in the raised position when it is required to position a new reel (B) of film on the special support means ( 5 ).  
   
   
       10 ) Apparatus according to  claim 9) , in which the torque shaft ( 11 ) which rotatably supports the slow prestretching roller ( 8 ) projects with one end from a sidewall ( 101 ) of the container ( 1 ), for example through a curved slit ( 13 ) provided in this sidewall and having a centre of curvature about the drive shaft ( 6 ), and it being envisaged that this same projecting end of the said shaft ( 11 ) may be retained in the raised position by means of a latch ( 14 ) mounted externally on the said sidewall ( 101 ) which has the said eyelet ( 13 ).  
   
   
       11 ) Apparatus according to  claim 6) , in which the end of the prestretched film (Z) which leaves the fast prestretching roller ( 1   08 ) is fixed onto a tubular core (A) keyed onto a spindle ( 15 ) which with its ends is removably supported by a pair of pivoting parallel arms ( 16 ) keyed onto a torque shaft ( 17 ) rotatably supported by the sidewalls ( 101 ) of the container ( 1 ), all of which being arranged so that the said tubular core (A) tends to remain in contact with the said fast prestretching roller ( 108 ) by means of gravity so as to be rotationally driven by the latter, it being envisaged that this contact condition, which is particularly useful during the initial stage of the cycle when the said core (A) is empty and light, is ensured by special ballast weights which are intrinsic or associated with the spindle ( 15 ) and/or by special resilient means.  
   
   
       12 ) Apparatus according to  claim 11) , in which, in order to facilitate positioning and removal of the spindle ( 15 ) onto and from the associated pivoting support arms ( 16 ), it is possible to envisage the possibility of pivoting these arms upwards and causing them to rest against a stop ( 18 ) which is integral with at least one of the sidewalls ( 101 ) of the container ( 1 ).  
   
   
       13 ) Apparatus according to  claim 12) , in which special damping means may be envisaged for braking the downwards pivoting of the arms ( 16 ) which carry the spindle supporting the core (A) for storing the prestretched extendable film.  
   
   
       14 ) Apparatus according to  claim 1 , characterized in that it comprises an electric control panel ( 19 ) with an activation control device ( 20 ), a stop control device ( 21 ) and a timer ( 22 ) by means of which it is possible to select the activity time of the apparatus and consequently the quantity of prestretched film stored on the tubular core (A).  
   
   
       15 ) Apparatus according to  claim 14) , in which special optical and/or acoustic signalling means may be envisaged for signalling when the said apparatus has produced the reel of prestretched film of predefined weight, after the said timer ( 22 ) has stopped the gearmotor ( 7 ).  
   
   
       16 ) Apparatus according to  claim 6) , in which a pointer ( 23 ) may be fixed onto one end of the torque shaft ( 17 ) which projects from a sidewall ( 101 ) of the container ( 1 ), said pointer moving along a graduated scale provided on the outer face of the said sidewall ( 101 ), so as to indicate the weight or the diameter of the film stored on the tubular core (A).