Abstract:
A method for packaging a mattress in a package, comprising:
       retaining, in a first step of operation, a fixing element below a resting surface and causing the advancement of a mattress from a first conveyor toward a second conveyor for producing the wrapping of a sheet in a loop around the mattress and the perimetric closure by heat-sealing and cutting of the sheet and the formation of a first wrapping, which is separate from the sheet unwound from the reel,   lifting, in a second step, the sheet fixing element above the resting surface and transferring the mattress onto the advancement conveyor, returning, in a third step, the fixing element below the resting surface and   in a fourth step, producing the advancement of the mattress on the second receiving and transfer conveyor in order to wrap a second sheet around the first wrapping and perform consequent heat-sealing and cutting of the sheet, forming a second wrapping that is separate from the first one.

Description:
[0001]    The present invention relates to a method and an apparatus for packaging a mattress in a package composed of multiple wrappings arranged one inside the other. 
       BACKGROUND OF THE INVENTION 
       [0002]    Mattresses, in order to be protected against dust and during the handling that they undergo during sorting and transport operations, are currently contained in a package consisting of a sheet of plastic material that is closed hermetically and is usually transparent for making the characteristics of the contained product visible. 
         [0003]    However, the package, due to tearing caused by breakage or due to the dirt and dust that has deposited thereon during storage, often is scarcely acceptable to buyers and does not make the informational and advertising lettering, often provided on the outside of the package, fully visible. 
         [0004]    In order to obviate the above described drawbacks, it has already been proposed to protect mattresses by introducing the first wrapping of the package in a second outer wrapping. In this manner, if the outer wrapping is damaged in any way, it can be removed, so as to make the inner one, which is still intact, visible. 
         [0005]    However, the Applicant is not aware of any machines proposed on the market that are capable of forming continuously a double wrapping around a mattress. With known machines the outer wrapping is in fact applied separately, i.e., independently of the inner one, by using a secondary packaging machine onto which the mattress provided with a first wrapping is transferred. 
       SUMMARY OF THE INVENTION 
       [0006]    The aim of the present invention is to devise a method for packaging a mattress in a package composed of multiple wrappings arranged one over the other around the mattress. 
         [0007]    Within this aim, an object of the present invention is to provide a method for packaging a mattress in a package composed of two wrappings arranged one inside the other around the mattress, which consist of material in sheet form taken from at least one respective reel. 
         [0008]    This aim and this and other objects which will become better apparent hereinafter are achieved with a method for packaging a mattress in a package, which comprises: 
         [0009]    preparing a first conveyor for the advancement of the mattress and a second conveyor for receiving and transferring the mattress so as to form a mattress resting surface and form a separating opening between said conveyors, such that it can be bridged by a mattress that is moved from one conveyor to the other by way of adapted movement means, 
         [0010]    preparing above said conveyors a reel of a sheet that can be heat-sealed and one end of which is joined to a fixing element that is guided through said opening, 
         [0011]    providing means for engaging and actuating said sheet fixing element between a position that lies below said resting surface, in which said sheet remains stretched through said opening, and a position that lies above said resting surface up to such a height as to allow the passage of a mattress between said resting surface and said fixing element, 
         [0012]    providing, above said resting surface, heat-sealing and cutting means that can be operated synchronously with said fixing element and said mattress movement means for 
         [0013]    retaining, in a first step of operation, the fixing element below the resting surface and cause the advancement of the mattress from the first conveyor toward the second conveyor in order to produce the wrapping of said sheet in a loop around said mattress and the perimetric closure by heat-sealing and cutting of said sheet and the formation of a first wrapping, which is separate from the sheet unwound from said reel, 
         [0014]    lifting, in a second step, the sheet fixing element above the resting surface and transferring the mattress onto the advancement conveyor, 
         [0015]    returning, in a third step, said fixing element below the resting surface and 
         [0016]    in a fourth step, producing the advancement of the mattress on the second receiving and transfer conveyor in order to wrap a second sheet around the first wrapping and perform the consequent heat-sealing and cutting of the sheet, forming a second wrapping that is separate from the first one. 
         [0017]    Another object of the present invention is to provide an apparatus for performing the method described above. 
         [0018]    This aim is achieved with an apparatus for packaging a mattress in a package, characterized in that it comprises a first conveyor for the advancement of the mattress and a second conveyor for receiving and transferring the mattress, said conveyors forming a resting surface and being mutually separated by an opening, means for actuating said conveyors to transfer said mattress from one conveyor to the other by bridging said opening, a structure for supporting a reel of a sheet that can be heat-sealed above said conveyors, means for engaging an element for fixing the end of the sheet unwound from said reel, means for actuating and guiding said fixing element through said opening between a lower position, which lies below said resting surface and in which said sheet is stretched through said opening, and an upper position, which lies above said resting surface, up to such a height as to allow the passage of a mattress between said resting surface and said fixing element, heat-sealing means arranged above said resting surface, said means for actuating the fixing element, for heat-sealing and cutting and moving the mattress being functionally coordinated so that in a first step, with the fixing element arranged below the resting surface, the mattress is transferred from the first advancement conveyor toward the second receiving and transfer conveyor, thus causing the wrapping and closure in a loop by heat-sealing and cutting of said sheet around said mattress and the formation of a first wrapping; in a second step, the fixing element is raised above the resting surface and the mattress is returned onto the advancement conveyor; in a third step, the fixing element is again lowered below the resting surface so as to again stretch said sheet through said opening; in a fourth step, the mattress is again transferred onto the receiving and transfer conveyor and the wrapping of a second enclosure around the first enclosure, the heat-sealing and cutting of the sheet, with formation of a second wrapping that is not connected to the first one, are completed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Further characteristics and advantages of the present invention will become better apparent from the following detailed description of two embodiments of an apparatus for carrying through the method, which are illustrated by way of example in the accompanying drawings, wherein: 
           [0020]      FIG. 1  is a side elevation view of an apparatus according to the invention; 
           [0021]      FIG. 2  is a perspective view of the mattress advancement conveyor; 
           [0022]      FIG. 3  is a side elevation view of the mattress advancement conveyor, taken along the line of  FIG. 4 ; 
           [0023]      FIG. 4  is a plan view of the advancement conveyor; 
           [0024]      FIG. 5  is a perspective view of the conveyor for receiving and transferring the mattress and of the device for closing the package; 
           [0025]      FIG. 6  is a perspective view of the receiving and transfer conveyor, taken from the opposite position with respect to  FIG. 5 ; 
           [0026]      FIG. 7  is an enlarged-scale view of a detail of  FIG. 6 , related to the package closing device; 
           [0027]      FIG. 8  is a plan view of the receiving and transfer conveyor; 
           [0028]      FIG. 9  is a sectional view, taken along the line IX-IX of  FIG. 8 ; 
           [0029]      FIGS. 10 to 14  are views of the apparatus in successive operating steps for forming the first wrapping of the package; 
           [0030]      FIG. 15  is a side elevation view of a variation related to the formation of two wrappings provided by means of sheets taken from respective reels during the step for removing the sheet to form the first wrapping; 
           [0031]      FIG. 16  is a view of the step for removing the sheet to form the second wrapping; 
           [0032]      FIGS. 17 ,  18  and  19  are three perspective views of a means for locking the fixing element; 
           [0033]      FIG. 20  is a sectional view, taken along the line XX-XX of  FIG. 15 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    With reference to  FIG. 1 , the reference numeral  1  generally designates an apparatus, which can be assumed to be composed of two working assemblies  2  and  3 , designed to move a mattress M, between which a third working assembly  4  is arranged which is designed to close the two wrappings that compose the package. 
         [0035]    The first assembly  2 , shown in greater detail in  FIGS. 2-4 , constitutes an advancement conveyor (designated hereinafter by the same reference numeral  2  for the sake of convenience) and comprises a rectangular frame  5  that is composed of two lateral longitudinal members  6 , which are connected at their opposite ends by two cross-members  7 . The frame  5  rests on the ground, at one end, by means of uprights  8 , which are connected by longitudinal stringers  9  and transverse stringers  10 . In the two corners of the end that lies opposite the uprights  8 , there are provided respective feet  11 , shorter than the uprights  8 , by means of which the frame  5  is arranged on resting elements of the assembly  4 . The reference numeral  12  designates two bars, which are parallel to the longitudinal members  6  and whose opposite ends are fixed to the cross-member  7  and, by means of raised portions  12   a,  to the stringer  10 . 
         [0036]    Two series of parallel rollers  13  and  14  are pivoted in the bars  12  and in the longitudinal members  6  and form respective rolling surfaces, which allow the movement of the mattress during the formation of the package. An elongated opening  15  remains between the bars  12  and below them there are two beams  16 , which, at one end, hang down below the cross-member  7  and, at the opposite portion, rest and are fixed on the transverse stringers  10 . The beams  16  support sliding guides  16   a  for a slider  17  (see  FIGS. 3 ,  4 ), which is connected to a driving chain  18 , which is closed in a loop around a respective driving gear  19  and driven gear  20 , which are supported so that they can rotate on brackets  21  that are fixed on the beams  16 . Specifically, the driving gear  19  is actuated by a reversible gearmotor  21   a,  which is coupled by means of a flange below the cross-member  7 . A pusher  22  is fixed on the slider  17  and forms, with the rolling surfaces consisting of the rollers  13 ,  14 , the advancement conveyor  2 , which, by means of the closure assembly  4 , transfers the mattress toward the working assembly  3 , as will become better apparent in the further description. The pusher  22  consists in a bar  23 , which is parallel to the rollers  13 ,  14  and is fixed to an L-shaped arm  24 , which rises from the slider  17  on which it is fixed. With the actuation of the gearmotor  21   a,  the arm  24  moves along the opening  15 , while the bar  23  of the pusher  22 , by moving above the rollers  13 ,  14 , can push the mattress M to be packaged toward the assembly  3  once said mattress has been deposited on the rollers by a feeder conveyor  25 . 
         [0037]    The feeder conveyor  25  (see  FIGS. 2 ,  3 ) can be of any type. In the example shown, it advantageously consists of a frame  26  on which multiple parallel belts  27  are mounted, their upper portions being mutually coplanar so as to form a surface for conveying the mattress. The belts  27  are closed in a loop on respective guiding pulleys  28  and driving pulleys  29 , of which the driving pulleys  29  are keyed on a shaft  30  that is supported rotatably by the frame  26 . The shaft  30  is motorized, by means of a transmission  31 , by a gearmotor  32  mounted below the frame  26 . The conveyor  25  is fixed obliquely with respect to the frame  25  (see  FIG. 2 ) by brackets  33 , and its length is such as to overlap the driving pulleys  29  on the rollers  13 ,  14 , so as to be able to unload the mattress M in front of the bar  23  of the pusher  22 , which, due to the L-shaped configuration of the arm  24 , can return below the belts  27 . 
         [0038]    The advancement conveyor  2  described so far is completed by a further motor drive, which is designed so as to allow the free rotation of the rollers  13 ,  14  when the pusher  22  pushes the mattress M in the advancement direction A from the initial position (i.e., for receiving the mattress M from the feeder conveyor  25 ) toward the assembly  3  by way of suitable means. Vice versa, when the rollers  13 ,  14  are actuated positively, they entrain the mattress that arrives from the assembly  3  in the direction B for return of the pusher  22  toward the starting position. 
         [0039]    Said motor drive means consist of two shafts  34 ,  35  (see  FIGS. 2 ,  4 ), which are perpendicular to the rollers  13 ,  14  and can rotate within supports that are fixed below the lateral longitudinal members  6  and are actuated by respective gearmotors  36 ,  37  that are fixed to said longitudinal members by means of flanges. For transmitting the motion from the gearmotors  36 ,  37  to the rollers  13 ,  14  belts  38  are provided, which are closed in a loop around the shafts  34 ,  35  and around pulleys (not visible in the drawings) that are keyed to the ends of the rollers. 
         [0040]    Each mattress M deposited on the advancement conveyor  2  is transferred onto the assembly  3 , which in combination with the working assembly  4  stretches and wraps around the mattress M a first sheet  38  of plastic material, which is unwound from a respective reel  39  (see  FIG. 10 ) and is wider than the mattress. After the sheet  38  has been closed around the mattress M so as to form a first hermetic wrapping, the mattress is again returned to the advancement conveyor  2 , so to be able to start a second identical packaging operation for wrapping around the mattress a second sheet that is separate from the first one. 
         [0041]    The assembly  3  (see  FIGS. 5 ,  6 ,  8 ) consists of a frame  40 , which is composed of two lateral longitudinal members  41  connected by cross-members  42 . Two rollers  43 ,  44  are supported rotatably at the opposite ends of the longitudinal members  41 , and belts  45  which are mutually parallel and spaced are closed in a loop around said rollers. The upper portions of the belts are coplanar and slightly raised at the opposite ends by means of rollers  46 , which are keyed to respective shafts  47  supported within the longitudinal members  41  proximately to the rollers  43 ,  44 . Moreover, the upper portions of the belts  45  are in sliding contact with the top of a slab  48 , which is fixed on the frame  40  between the rollers  43 ,  44  and the lateral longitudinal members  41 . The function of the roller  43  is to drive the belts  45 . For this purpose, it is actuated by a gearmotor  49 , which is flanged to a longitudinal member  41  and is of the reversible type in order to actuate the belts in both directions A and B of sliding on the slab  48 . In this manner, the assembly  3  acts like a conveyor, which after receiving the mattress from the advancement conveyor  2  and after the formation of the first wrapping, transfers it onto the conveyor  2  in order to start the formation of the second wrapping. 
         [0042]    The opposite ends of the longitudinal members  41  rest on, and are fixed to, two cross-members  50 ,  50   a.  The cross-member  50  extends between two posts  52 , which are lateral with respect to the longitudinal members  41  and are mutually connected at the top by a cross-member  53 , which lies in a bridge-like arrangement above the belts  45 . The opposite ends of the cross-member  50   a  are fixed between the two columns  54  of a bridge-like frame  55  which is arranged between the assemblies  2  and  3  and constitutes the supporting structure of the closure assembly  4 . 
         [0043]    The structure  55  is strengthened by a beam  51  that extends between the tops of the columns  54  and is connected to the cross-member  53  by two upper beams  56  and two lower beams  57 . Two bearings  57   a  are fixed to each lower beam  57  in order to support two shafts  58 , which are parallel and perpendicular to the belts  45 . Corresponding sprockets  59  are keyed to the opposite ends of the two shafts  58  and mesh with a transmission chain (not visible in the drawing because it is covered by a housing  59   a ), which is wound around them and constrains the rotation of the shafts  58  in the same direction. Further, two pinions  60  are keyed to each shaft  58  and mesh with respective vertical racks  61 , which are fixed to vertical strips  63  that are kept guided between pairs of free rollers  62 , which are mounted below the cross-members  57  and to the lower end of which a panel  64  is fixed whose faces are flat and parallel to the underlying slab  48  and which forms with said slab a compartment for accommodating the mattress M. The opposite ends of two strips  64   a  (see  FIGS. 8 ,  9 ) are jointly connected above the cross-members  57  and two fluid-operated jacks  65  are supported between said strips, their stems being coupled to the panel  64 , and actuate the lifting and lowering of the panel  64  with respect to the slab  48 . The panel  64  acts as a presser designed to reduce the thickness of the mattress before the sheet  38  is closed so as to form the wrapping. 
         [0044]    Two transverse rails  66  are fixed below the lateral longitudinal members  41  of the frame  40 , and two supporting carriages  67 , for heat-sealing elements adapted to close hermetically at its sides the package that will be formed, can be arranged on said rails, one for each side of the frame  40  and so as to be mutually opposite. 
         [0045]    Each carriage  67  is composed of two elements  68 , which are substantially C-shaped and are mutually connected by strips  69 . Each one of the elements  68  comprises a lower arm which is provided with wheels  70  for the gliding of the carriage  67  on the rails  66  and an upper arm which protrudes in a cantilever fashion above the slab  48  and supports a fluid-operated jack  71 . The stems of the jacks  71  of each carriage extend downward and a heat-sealing bar  72  hangs down from them, parallel to the belts  45 , a bar  73  being arranged opposite the heat-sealing bar  72  in a lower region, fixed to brackets  73   a  of the carriage and acting as a contrast member for the heat-sealing bar to perform the heat-seals for the lateral closure of the wrapping. 
         [0046]    In order to allow the heat-sealing bars  72  to preserve their parallel arrangement relative to the respective contrast bars  73  when the jacks  71  are actuated, said jacks are provided with adapted mechanisms that constrain the stems of the pair of jacks  71  mounted on each carriage  67  so as to follow identical paths. In the illustrated example, these mechanisms are not shown, since they are assumed to be fully traditional, consisting of, for example, racks which are formed in the stems of the jacks and mesh with pinions that are keyed to the ends of a shaft  74   a  which can rotate in supports that are jointly connected to the upper arms of the carriage. Substantially, the mechanisms are similar to what is described above with respect to the elements  58 ,  60 ,  61  by means of which the vertical movements of the plate  64  are restrained kinematically. 
         [0047]    The advancement conveyor  2  and the receiving and transfer conveyor  3  are mutually spaced so as to form, between the roller  44  and the rollers  13 ,  14 , an opening  75  (see  FIGS. 1 ,  10 - 14 ) at which the structure  55  of the third operating assembly  4  is arranged which comprises the means that stretch the packaging sheet which is ready to be wrapped in a loop around the mattress and then complete its hermetic sealing in combination with the lateral heat-sealing performed between the heat-sealing bars  72 ,  73 . 
         [0048]    Said means (see  FIGS. 7-9 ) consist of a heat-sealing bar  76  and a corresponding contrast bar  77 , which extend transversely between the columns  54  of the structure  55 . The heat-sealing bar  76  is of the type that produces two parallel heat-sealing lines and a separation cut between the two heat-sealing lines. 
         [0049]    The heat-sealing bar  76  hangs down, at its opposite ends, from the stems of two jacks  78 , which are accommodated vertically in the columns  54  and of which only the cylinders are visible in the figures. In order to allow the heat-sealing bar  76  to maintain the horizontal arrangement during its actuation, the stems of the jacks  78  are mutually coupled by a mechanism that is identical to the one described earlier with respect to the stems of the jacks  71  that move the lateral bars  72 . Of this mechanism, it is possible to recognize in  FIG. 7  the longitudinal shaft  79  and the pinions  80 , which mesh with the respective racks provided in the stems of the jacks  78  and are concealed within the columns  54 . 
         [0050]    Two vertical guides  81 , for a slider  82  that can be actuated vertically by means of a pair of fluid-operated jacks  83  mounted on the beam  51 , are fixed to the opposed faces of the columns  54  and proximately to the heat-sealing bar  76 . The slider  82  is composed of a strip  84 , which is provided at its ends with brackets  85 , which support a roller  86  and are provided with sliders  87  that slidingly engage the guides  81 . By means of the jacks  83 , the roller  86  can be lowered onto a further roller  88 , which is supported so that it can rotate within the columns  54  at the height of the belts  45  and rollers  13 ,  14  and at the opening  75 , so as to provide an additional support for the mattress M during its transfer from the working assembly  2  to the other assembly  3 . The roller  86 , in the raised position, forms together with the roller  88  the inlet to the compartment for accommodating the mattress between the straps  45  and the plate  64 . Two profiles  89  are arranged adjacent to the guides  81  and form vertical channels in which the opposite ends of a cylindrical rod  90  are engaged slidingly (see  FIGS. 1 ,  7 ,  10 - 14 ), and the end edge of the sheet  38  of heat-sealing material designed to form the package and taken from the reel  39  is fixed to said rod so that it rotates jointly with said rod. The reel  39  rests so as to roll on two counter-rotating rollers  91 , which are supported by shoulders  92  that rise from the top of the columns  54 . One of the rollers  91  is actuated by a gearmotor  93  of the reversible type, which is mounted on a shoulder  92  and is adapted to control the unwinding of the sheet  38  from the reel  39 . It should be noted that in  FIGS. 5-9 , the reel  39 , the rollers  91  and the gearmotor  93  have not been shown for the sake of clarity of the drawing. 
         [0051]    The apparatus described so far is completed by a device for allowing the movement of the rod  90  from a height that lies below the resting surface of the mattress M on the advancement conveyor  2  and on the receiving and transfer conveyor  3 , i.e., the plane formed by the rollers  13 ,  14  and by the belts  45 , to a level that lies above the resting surface by a height that is at least greater than the thickness of the mattress. 
         [0052]    Said device comprises a pair of belts  94 , each of which is closed vertically in a loop around two pulleys  95 ,  96 , the upper ones  95  of which can rotate on the internal faces of the columns  54  and the lower ones  96  of which are keyed to the ends of a shaft  97  that is supported rotationally in brackets  98  fixed in a cantilever fashion to a base  99  of the structure  55 . The belts  94  are moved by a reversible gearmotor  100 , which is mounted on the base  99  and transmits motion to the shaft  97  by means of a transmission  101 . A vertical guide  102  for the sliding of a sliding block  103  is arranged to the side of each belt  94  and said sliding block is fixed in a cantilever fashion to a portion of the respective belt so that it can perform upward and downward strokes. A fluid-operated actuator  104  is incorporated in each sliding block  103  and is provided with stems  105  to which an engagement element is jointly connected which consists of a fork  106  (see  FIGS. 1 ,  7 ), which protrudes horizontally toward the guide  81 . By activation of the actuators  104 , the forks  106  can engage and disengage the ends of the fixing rod  90  of the sheet when it lies below the plane of the rollers  13 ,  14 . 
         [0053]    The operation of the apparatus is described hereinafter with reference to  FIGS. 10-14 . First of all, a portion of the sheet  38  is unwound from the reel  39  and its end is fixed to the rod  90 . The rod is then lowered below the plane of the rollers  13 ,  14  and engaged at the opposite ends by the forks  106  actuated by the actuators  104 , so that the unwound portion of sheet is stretched through the opening  75 . Conveniently, in the shoulders  92  that lie above the columns  54  there is a guiding roller  107 , which spreads the sheet on a vertical plane that passes through the channels  89  (see  FIG. 10 ). 
         [0054]    After unloading onto the rollers  13 ,  14  the mattress M to be packaged by means of the feeder  25 , the pusher  22  is activated and, from its position below the feeder  25 , pushes the mattress M in the direction A against the sheet  38 , forcing it between the plane of the belts  45  and the plate  64  of the presser (see  FIG. 11 ). 
         [0055]    With the insertion of the mattress in the compartment formed between the belts  45  and the plate  64 , a further portion of sheet  38  unwinds from the reel, so that when the mattress is fully transferred onto the belts  45 , the front, upper and lower faces of the mattress are covered by the sheet. 
         [0056]    Then (see  FIG. 12 ), after lowering the roller  82  into abutment against the roller  88  and thus moving mutually closer the superimposed flaps of the sheet, the transverse heat-sealing unit  76 ,  77  is actuated and joins the superimposed flaps of the sheet along two parallel and adjacent heat-sealing lines and cuts them along a line that is intermediate with respect to the heat-sealing lines, causing at once the formation of a first wrapping (which will be the inner one) which is closed around the mattress but is separated from the sheet, whose continuity is restored from the reel  39  up to the fixing rod  90 . After the heat-sealing bars  76 ,  77  have been opened, the actuators  104  are activated and release the rod  90  by retracting the forks  106 . Then, with the subsequent activation of the gearmotor  100 , by means of the shaft  97  and the belts  94 , the rod  90  is raised to a level that lies above the upper face of the mattress M (see  FIG. 13 ). At the same time, by means of the activation of the gearmotor  93  and the rotation of the rollers  91 , rewinding onto the reel  36  is provided for the portion of sheet that otherwise would be loose upon lifting of the rod  90 . Once these steps have been completed, the mattress M is advanced by means of the belts  45  and is positioned below the plate  64 , which, by activating the jacks  65 , moves downward, compressing the mattress M and reducing its thickness, so that at the end of the packaging operations the volume of the packaged mattress is reduced significantly (however, it is noted that in  FIG. 13  the mattress is not shown in the compressed position). Moreover, when the mattress M is in the compressed condition and the sheet  38  is closed in a loop around it, the lateral heat-sealing units  72 ,  73  are activated and, by heat-sealing the superimposed lateral flaps of the sheet, complete the perimetric closure of the sheet, providing a hermetically closed wrapping. 
         [0057]    As soon as the perimetric heat-sealing has been completed, the plate  64  is lifted again, thus releasing the mattress M so that by activating the belts  45  in the opposite direction B, the mattress, passing below the rod  90 , can be transferred onto the conveyor  2  (see  FIG. 14 ). At this point, the rod  90  is lowered again below the plane of the rollers  13 ,  14 , so as to stretch a new portion of sheet through the opening  75 , thus restoring the initial conditions that make it possible to form a second wrapping in the manner described above for forming the first wrapping. 
         [0058]    As can be seen, the invention achieves perfectly the intended aim and objects. In particular, it is noted that with the apparatus it is possible to obtain two separate wrappings, so that the outer one can be removed easily in case of damage or for various reasons, for example for reasons of presentability of the contained product, or in case of undergone damage and so forth. 
         [0059]    The described apparatus is susceptible of modifications and variations, all of which are within the scope of the appended claims. 
         [0060]    According to a second embodiment of the invention, shown more clearly in  FIG. 7  and adapted to ensure more exact and crease-free handling of the wrapping of the sheet around the mattress, a gear  108  is provided, which is keyed to one end of the fixing rod  90  and is arranged adjacent to the plane of advancement of the fork  106 , so as not to interfere with said fork. A pinion  109  is supported at the lower end of the channel  89  and is adapted to mesh with the gear  108  when said gear is positioned at the lower stroke limit. The pinion  109  is actuated by means of a gearmotor  110 , which is mounted on a post  111  jointly connected to the base  99 . The function of the gearmotor  110  is to impart to the gear  108 , once it has been meshed with the pinion  109  and at the end of the closure of each wrapping, a rotation by means of which a number of turns is transmitted to the rod  90  which is sufficient to rewind a portion of the sheet that might remain loose after heat-sealing and cutting and restore the spreading thereof that is necessary to ensure the wrapping of the sheet around the mattress. 
         [0061]    It should be noted that with this embodiment the portion wrapped around the rod  90  can be unwound on the belts  45  at the same advancement speed as the mattress, so as to avoid the sliding of the mattress on the underlying sheet portion and ensure perfect spreading of the sheet below the mattress. 
         [0062]      FIGS. 15 ,  16  illustrate a further embodiment, which makes it possible to provide packaging by using two sheets taken from two different reels and is therefore capable of forming two wrappings that have different aesthetic characteristics, or of providing an outer wrapping with stronger sheets or to function as a support for advertising messages and so forth. 
         [0063]    The variation provides, to the side of the first reel  36 , a second reel  112 , which is also supported by a pair of rollers  113  actuated by a gearmotor  114  mounted on the shoulder  102 . The second sheet  115  is wrapped around the reel  112 , its end being fixed to a second fixing rod  116 , whose opposite ends are guided in the same channels  89  in which the rod  90  is guided. 
         [0064]    Two actuators  117 ,  118  are associated with each shoulder  102 , below the rollers  91 , for the actuation of respective arms  119 ,  120  which are substantially horizontal. By activation of the actuators, the arms  119 ,  120  move between a position of engagement in the channels  89  and a position of extraction from them through adapted recesses formed in the shoulders of the channels. 
         [0065]    The actuators  117 ,  118  are actuated alternately for switching the drawing of the sheets from one reel to the other after formation of the first wrapping. 
         [0066]    After formation of the first wrapping with the sheet  38  in the manner specified above in  FIGS. 10-14 , the rod  90  for fixing the sheet  38  is lifted by the forks  106  to the height of the lower arm  120  and then retracted out of the channels  89  by the actuators  118 . 
         [0067]    Conveniently, the arms  119 ,  120  are curved upward, so that the rod  90  can continue to be retained on the arms  120 , allowing the forks  106  to be retracted and lifted to the height of the arms  119  on which the rod  116  was deposited earlier during formation of the first wrapping. At this point the forks  106  are activated to engage the upper rod  116  and the arms  119  are disengaged from the channels  89  by activation of the actuators  117 , so that by actuation of the belts  94  the rod  116  is lowered below the plane of the rollers  13 ,  14  for being able to proceed with the formation of the second wrapping and the completion of the packaging process. 
         [0068]    Advantageously, as shown in  FIGS. 17-19 , both rods  90  and  116  are each provided, at at least one end, with a gear  108 ,  121 , and at least the fork  106 , which is adjacent to the gears  108 ,  121  and therefore cooperates with the arms  119 ,  120 , has a toothed sector  122 , which is guided in a U-shaped member  123  that is fixed to one face of the fork  106 . The toothed sector  122  is connected to the stem of an actuator  124  that is fixed to the opposite face of the fork. Depending on the requirements, the toothed sector  122 , by engaging the set of teeth of the gears  108 ,  121 , can block the rotation of the rods  90 ,  116  during movements along the channels  89  or during the steps for wrapping and unwinding the sheets on the part of the elements  109 ,  111 . Conveniently, additional toothed sectors  125 ,  126  are jointly connected to the arms  119 ,  120  and, by actuation of the actuators  117 ,  118 , engage the gears  108 ,  121 , retaining the rods  90 ,  116  at the heights provided for pick-up by the forks  106 . 
         [0069]    The disclosures in Italian Patent Application No. BO2008A000614 from which this application claims priority are incorporated herein by reference.