Abstract:
Coupons are fed from a supply station to an assembly station forming part of a wrapping line, where they are associated each with a relative product. The coupons are engaged along one vertical edge by the lugs of a looped conveyor belt, pushed a set distance along a transfer line sliding internally of a guide channel, and released by the belt only after entering the assembly station, where the single coupon comes to rest interposed between a product and a relative wrapper blank.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a method of feeding elements of sheet material to a product wrapping line.  
           [0002]    The invention finds application to advantage in the tobacco industry, where the wrapping line of a packaging machine, typically a cigarette packer or cartoner, is supplied with slips of sheet material consisting in particular of “plain” coupons that appear as a single leaf, or “folded” coupons that present at least two mutually overlapping portions connected along one side; direct reference is made to this same field in the following specification, albeit with no limitation implied.  
           [0003]    It is standard practice in the tobacco industry for single packets or pluralities of packets to be furnished with a respective plain or folded coupon at an assembly station located along the wrapping line aforementioned; the coupons are drawn from a supply which, in view of the size and architecture of the packer or cartoner, is located at a given distance from the assembly station. In general, the coupons are directed from the supply to the assembly station along a transfer line by a conveying element that retains the single coupons by suction and feeds them in succession to the station, synchronously with the operation of the wrapping devices.  
           [0004]    Whilst the technology in question is simple and inexpensive to implement, it presents considerable problems in the event that the coupons fed to the wrapping line are folded, as the conveying element engages only one of the folded parts of the coupon by suction, whereas there is no positional control of any kind over the remaining folded portion or portions and these are liable to flutter freely, becoming detached from the portion held by suction.  
           [0005]    To overcome this drawback and develop a conveying technology suitable both for plain coupons and for folded coupons, the prior art embraces conveying elements consisting in mutually opposed rollers or belts by which the coupons are gripped positively and carried thus toward the devices of the wrapping line.  
           [0006]    This type of conveying technology betrays certain drawbacks nonetheless, deriving from the fact that the coupons can lose contact with the rollers or the belts and become incorrectly positioned along the transfer path. In the case of folded coupons moreover, this loss of contact can result in the overlapped portions shifting one in relation to another, so that the correct folded configuration of the actual coupon is disrupted.  
           [0007]    A further drawback stems from the fact that, in order to avoid contact with the wrapping devices, the conveying elements in question must necessarily release the coupons at a given distance short of the aforementioned assembly station; this means that the coupons are effectively pitched into the station and their flight is difficult to control.  
           [0008]    The object of the present invention is to provide a conveying method that will allow both plain and folded coupons to be transferred with no problems whatsoever.  
         SUMMARY OF THE INVENTION  
         [0009]    The stated object is realized according to the present invention in a method for feeding elements of sheet material to a product wrapping line, whereby elements of sheet material are conveyed from a supply station to an assembly station and united with relative products, comprising at least the step of pushing the elements of sheet material along a predetermined transfer line and through a predetermined distance into the assembly station.  
           [0010]    The aforementioned object is realized similarly in a unit according to the present invention for feeding elements of sheet material to a product wrapping line, by which elements of sheet material are conveyed from a supply station to an assembly station and united with relative products; the unit disclosed is equipped with pushing means such as will direct the single elements of sheet material along a predetermined transfer line and through a predetermined distance into the assembly station. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:  
         [0012]    [0012]FIG. 1 illustrates a unit embodied in accordance with the present invention for feeding elements of sheet material to a station of a packaging machine at which they are assembled with relative products, viewed schematically in perspective with certain parts omitted;  
         [0013]    [0013]FIG. 2 shows the unit of FIG. 1 in a schematic plan view, with certain parts omitted;  
         [0014]    [0014]FIG. 3 shows the unit of FIG. 1 in a schematic side elevation, with certain parts omitted;  
         [0015]    [0015]FIG. 4 shows an enlarged detail of the unit in FIG. 1 and FIG. 3, viewed schematically and in perspective;  
         [0016]    [0016]FIG. 5 shows a detail of FIG. 3, viewed schematically and in perspective;  
         [0017]    [0017]FIGS. 6 and 7 show a detail of FIG. 1, viewed schematically and in perspective and illustrated in two successive operating steps. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    Referring to FIG. 1 of the drawings,  1  denotes a unit, in its entirety, for feeding elements  2  of sheet material to a packaging machine of which the drawings show a wrapping line  3 .  
         [0019]    More exactly, the elements  2  of sheet material present a substantially rectangular outline and consist in coupons of either “plain” or “folded” type, which are drawn from a supply  4  serving as a distribution station and consisting in a stack  5  of the elements  2  of sheet material. The elements  2  are taken up by respective feed means  6  and placed at the infeed end of a transfer line  7  extending along a substantially horizontal first feed path P1 toward an assembly station  8  located at the entry point of the wrapping line  3 .  
         [0020]    This same assembly station  8  is in receipt of substantially parallelepiped products  9 , appearing in the example of the drawings as single packets of cigarettes  10  ordered into groups and directed thus along a second feed path P2 substantially parallel to the first feed path P1.  
         [0021]    Also directed into the assembly station  8 , along a substantially vertical third path P3 and through the agency of respective feed means  11 , are single sheets of wrapping material consisting in diecut blanks  12  taken from a stack  13  and destined each to provide the wrapper for a respective carton  14  emerging from the wrapping line  3 , which extends along a substantially horizontal fourth path P4 transverse to the first and second paths P1 and P2. The products  9  and the relative wrapper blanks  12  are brought together at the assembly station  8 , positioned one facing another transversely to the wrapping line  3 .  
         [0022]    Observing FIGS.  1  to  5  it will be seen that the feed means  6  comprise a rocking arm  15  anchored pivotably at one end to a shaft  16  of which the axis  17  extends parallel to the first feed path P1, mounted to a frame  18  and capable thus of angular movement about the axis  17  through the agency of a first motor  19  connected to the shaft  16  by way of a mechanical linkage  19   a  (FIGS. 2 and 5), between a first raised position indicated by solid lines in FIG. 3, and a second lowered position indicated by phantom lines in FIG. 3.  
         [0023]    The free end of the arm  15  carries a pneumatic holder  20  mounted to a respective shaft  21  of which the axis  22  extends parallel to the axis  17  first mentioned. The holder  20  consists in a block  23  keyed to the free end of the shaft  21  and equipped with a plurality of suction cups  24  able to attract and retain the elements  2  of sheet material.  
         [0024]    Referring to FIGS. 3, 4 and  5  in particular, the rocking arm  15  incorporates a first drive  25  comprising a wheel  26  mounted rotatably to the one shaft  16  and fixed relative to the frame  18 , also a pulley  27  (FIG. 4) keyed to the other shaft  21  and free to rotate relative to the arm  15 .  
         [0025]    The same first drive  25  also comprises a belt  28 , looped around the wheel  26  and the pulley  27  and tensioned by a jockey roller  29 . The arrangement of the drive  25  is such that in operation, when the shaft  16  is made to rotate (clockwise in FIG. 3) by the first motor  19  about the relative axis  17 , which lies remote from the plane occupied by the element  2  of sheet material, the wheel  26  remains stationary whilst the arm  15  is caused to rock, and the resulting movement induced in the belt  28  thus causes the pulley  27  to rotate (counterclockwise in FIG. 3) about the corresponding axis  22 , which lies substantially parallel to the plane occupied by the element  2  of sheet material.  
         [0026]    The function of the wheel  26 , accordingly, is to determine the orientation of the block  23  relative to the corresponding axis  22  whenever the shaft  16  is set in rotation.  
         [0027]    The pulley  27 , being keyed to the shaft  21  as mentioned previously, causes the block  23  also to rotate in the same counterclockwise direction and to move, as the arm  15  rotates, from the position illustrated by solid lines in FIG. 3, in which the suction cups  24  actively engage the bottom of the stack  5 , to the position illustrated by phantom lines in FIG. 3 in which the element  2  of sheet material is positioned vertically over the transfer line  7 .  
         [0028]    As discernible in FIGS. 2, 3 and  4 , the feed means  6  also include take-up and insertion means  30  serving to carry out a final step of transferring the elements  2  of sheet material from the suction cups  24  into a guide channel  31  extending along the feed path P1 followed by the transfer line  7 .  
         [0029]    The take-up and insertion means  30  comprise a first pair of rollers  32  mounted to the opposite ends of a shaft  33  extending parallel to the first path P1, carried between a pair of uprights  34  supported on the frame  18 , and a second pair of rollers  35  mounted freely to respective pivots  36  carried by the selfsame uprights  34  and operating in conjunction with the first rollers  32  in such a way as to take up the element  2  of sheet material from the suction cups  24 , with the aid also of a chute denoted  37 , and insert it into an infeed end of the guide channel  31 .  
         [0030]    The channel  31  presents a profile substantially of “U” shape when seen in section, composed of a front side wall  38 , a bottom track  39  and a rear side wall  40  (FIGS. 1 and 2), extending from the infeed end through a predetermined distance as far as the assembly station  8 , of which the front side wall  38  affords a slot  41  disposed parallel to the first feed path P1.  
         [0031]    Following the final transfer step effected by the rollers  32  and  35 , the element  2  of sheet material occupies the guide channel  31  with a first edge  2   a  disposed perpendicular to the bottom track  39  of the selfsame channel, addressing the infeed end, and a second edge  2   b  in contact with the track  39 .  
         [0032]    Observing FIGS.  1  to  4 , the unit  1  comprises pushing means  42  positioned alongside the guide channel  31 , such as will maneuver each element  2  of sheet material along the transfer line  7  from the infeed end of the channel  31  to the assembly station  8 .  
         [0033]    The pushing means  42  in question include conveyor means  43 , describing and capable of movement along a closed path comprising a forward leg that extends the full length of the channel  31 . In particular, the conveyor means  43  incorporate a belt  44  looped around two pulleys of which one, denoted  45 , is positioned at the infeed end of the channel  31  and mounted to the vertically disposed shaft  46  of a second motor  47 , and the other, denoted  48 , is positioned near the assembly station  8  and mounted to a shaft  49  disposed parallel to the shaft  46  of the motor  47 .  
         [0034]    The looped belt  44  is furnished with pushing elements appearing as equispaced projections  50 , and disposed with one branch  51 , extending along the aforementioned forward leg of the looped path, that runs breasted with and along the slot  41  in such a way that the projections  50  are able to pass internally of the channel  31 . The pushing elements afforded by the projections  50  are set in motion cyclically between a position of interception and contact with the aforementioned first edge  2   a  of an element  2  positioned at the infeed end of the guide channel  31 , and a position coinciding substantially with the assembly station  8 , at which the element  2  is released when contact between the projection  50  and the first edge  2   a  of the element  2  ceases.  
         [0035]    It will be observed (referring to FIG. 2), that the rollers  32  are set in rotation by the first motor  19 , independently of the second motor  47 , through the agency of a second drive denoted  52 , and (referring to FIGS. 1, 6 and  7 ) that the assembly station  8  is equipped with a push rod  53  reciprocating along the fourth path P4 and serving to advance each product  9  together with a relative wrapper blank  12 , between which an element  2  of sheet material is inserted transversely to the wrapping line  3 . Entry to the assembly station  8  is afforded by a pair of walls  54  and  55  positioned respectively above and below the wrapping line  3 , combining to function as the mouth  56  of a folding tunnel, and consequently as reaction means with which the group of packets  10  and the respective blank  12  are caused to interact after an element  2  of sheet material has been interposed between them. Thereafter, as readily discernible from FIG. 1, the operation of folding the blank  12  around the packets  10  and the element  2  of sheet material is completed along the wrapping line  3  by conventional folder means not illustrated in the drawings.  
         [0036]    The operation of the unit will be obvious to a person skilled in the art having read the foregoing description.  
         [0037]    It may usefully be reiterated nonetheless that, once the first edge  2   a  presented by the element  2  of sheet material is engaged by a projection  50  on the belt  44  of the conveyor means  43 , a situation of constant contact is established between the first edge  2   a  of the element  2  and the relative projection  50 , resulting in a pushing action that continues along the entire length of the transfer line  7  from the infeed end of the channel  31  to the assembly station  8 , terminating only at the release position when contact between the edge  2   a  and the projection  50  can no longer be maintained.