Abstract:
A method and machine for packing a product—in the example shown, a group of cigarettes—in a blank of packing material, whereby the blank is fed to a first seat on a packing conveyor, the product is fed to a second seat on the same packing conveyor, and a relative movement is imparted to the two seats to form, in one of the two seats, a blank-product assembly.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method of packing a product. 
     BACKGROUND OF THE INVENTION 
     In the following description, reference is made purely by way of example to the packing industry, and in particular to cigarette packing machines for producing rigid hinged-lid packets of cigarettes, and on which a finished packet is normally formed by folding a preweakened blank of cardboard about a respective group of cigarettes wrapped in a sheet of foil material. 
     In the cigarette packing industry, it is common practice to us step-operated packing machines on which a blank is normally folded about a respective group of cigarettes as the group of cigarettes is transferred between the seats of successive packing wheels. In particular, a first folding operation, during which the blank assumes a substantially U-shaped configuration about the group of cigarettes, is normally performed by transferring the group of cigarettes from one seat on one wheel to a corresponding seat on a follow-up wheel, and by interposing the blank between the group and the seat on the follow-up wheel. 
     On step-operated packing machines, folding blanks about respective groups by transferring the groups between successive wheels is, mechanically speaking, fairly straightforward, seeing as the two corresponding seats of the two successive wheels are kept facing each other for a given time interval between successive operating steps of the wheels. Functionally speaking, however, folding the blanks as described above involves serious drawbacks on account of the ever-increasing operating speed of modern step-operated packing machines continually reducing the time interval and so increasing the likelihood of the blanks being damaged or folded incorrectly. 
     On continuous packing machines, folding the blanks by transferring the groups between successive wheels poses fewer operating problems, but seriously complicates the structure of the machine by requiring pairs of packing wheels comprising movable seats, and wherein each seat on each wheel is related dynamically to a corresponding seat on another wheel. That is, for a folding operation to be performed, two corresponding seats—one on one wheel and the other on a follow-up wheel—must be kept facing each other for a given length of time, while moving at least one of the two corresponding seats with respect to the relative wheel. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a packing method which is straightforward and cheap to implement in general, and in particular when using a continuous packing machine, and which at the same time provides for high-quality folding and high-speed performance. 
     According to the present invention, there is provided a method of packing a product in at least a first sheet of packing material; the method comprising the steps of feeding the first sheet to a first seat on a packing conveyor; feeding the product to a second seat on the same packing conveyor; and imparting a relative movement to said two seats to form, in one of said two seats, a first sheet-product assembly. 
     The present invention also relates to a machine for packing a product. 
     According to the present invention, there is provided a machine for packing a product in at least a first sheet of packing material, the machine comprising a packing conveyor; at least one first seat located on said packing conveyor to receive and retain said first sheet; at least one second seat located on said packing conveyor to receive and retain said product; and actuating means for imparting a relative movement to said two seats to form, in one of said two seats, a first sheet-product assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
     FIG. 1 shows a schematic partial front view, with parts removed for clarity, of a preferred embodiment of the machine according to the present invention; 
     FIG. 2 shows a larger-scale schematic view in perspective of a first detail in FIG. 1; and 
     FIG. 3 shows a larger-scale schematic view in perspective of a second detail in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Numeral  1  in FIG. 1 indicates as a whole a cigarette packing machine for producing rigid hinged-lid packets  2 . As is known, packets  2  are formed by folding a blank  3  and a collar  4  about a group  5  of cigarettes, which is normally wrapped in a sheet  6  of foil, and is normally in the form of an elongated parallelepipedon having two opposite, substantially parallel longitudinal ends  5   a.    
     Packing machine  1  operates continuously, and comprises a packing wheel  7  rotating about an axis  8  perpendicular to the FIG. 1 plane, and which is rotated continuously about axis  8  by a known actuating assembly  9 . Packing wheel  7  comprises a first and a second orderly number of peripheral seats indicated at  10  and  11  respectively; and each two adjacent seats  11  are located on either side of a seat  10 . 
     Each seat  11  receives and conveys a respective group  5  of cigarettes, while each seat  10  first receives and conveys a respective blank  3  partially folded substantially into a U, and later also receives and conveys a respective group  5  of cigarettes and a respective collar  4 . 
     As shown in FIG. 2, each seat  10  is formed on a respective support  12 , which is fitted to packing wheel  7 , and which is oscillated about a respective axis  13  parallel to axis  8  and according to a given law of motion by a known cam actuating device (not shown), which imparts to support  12  a given angular position about respective axis  13  for each angular position assumed by axis  13  about axis  8  as packing wheel  7  rotates. 
     Support  12  comprises a base body  14  with a number of through holes  15  connected to a known suction device (not shown) on packing wheel  7 ; and two lateral walls  16  parallel to axis  8  and on either side of base body  14 . Each lateral wall  16  defines a first arm of a respective rocker arm  17 , which is hinged to support  12  to oscillate, with respect to base body  14  and about a respective axis  18  parallel to axis  8 , between an open position and a closed position indicated respectively by a dash line and a continuous line in FIG.  2 . For this purpose, rocker arm  17  comprises a second arm  19  connected to a respective known link-block actuating device  20  controlled by a system of fixed cams (not shown) and activated by the rotation of packing wheel  7  about axis  8 . 
     When rocker arms  17  are set to the open position, the two lateral walls  16  of seat  10  form an obtuse angle with an outer surface of base body  14 , so that seat  10  has a section in the form of an isosceles trapezium with the shorter of the opposite sides coincident with the outer surface of base body  14 . Conversely, when rocker arms  17  are set to the closed position, the two lateral walls  16  of seat  10  substantially form a right-angle with the outer surface of base body  14 , so that seat  10  has a rectangular section substantially identical to that of a group  5  of cigarettes. 
     As shown in FIG. 3, each second seat  11  is associated with a respective pin  21  having an axis  22  parallel to axis  8 , and supported at opposite ends by two end plates  23  forming part of wheel  7  and perpendicular to axis  8 . Each seat  11  is defined by a respective gripping device  24  for engaging the opposite longitudinal ends  5   a  of a respective group  5  of cigarettes, and which comprises two rocker arms  25 , each of which is hinged about axis  22  and, in turn, comprises a central sleeve  26  fitted in rotary and axially-sliding manner to pin  21 , and two arms  27  and  28  extending radially from sleeve  26 . 
     The angular and axial positions of each sleeve  26  are controlled by a respective actuating and control device  26   a , which comprises a sleeve  26 ′ fitted in rotary and axially-sliding manner to pin  21  and contacting sleeve  26 . Sleeve  26 ′ comprises an arm  29  projecting radially from sleeve  26 ′ and fitted on the free end with a tappet roller  30  rotating about a respective axis perpendicular to axis  22 , and engaging a track  31  of a fixed cam  32  located between plates  23  and forming part of device  26   a . Device  26   a  also comprises known elastic members (not shown) for maintaining contact between each sleeve  26  and respective sleeve  26 ′. Track  31  extends about axis  8  to control the axial position of sleeve  26  along pin  21  alongside variations in the angular position of seat  11  about axis  8 . Each arm  27  is fitted on the free end with a respective cup-shaped half-shell  33 , which is positioned facing the half-shell  33  on arm  27  of the other rocker arm  25  to define respective seat  11 , and which provides for receiving a respective longitudinal end  5   a  of respective group  5  of cigarettes. Each arm  27  is of such a length that, by rotating arm  27  about axis  22  of pin  21 , respective half-shell  33  is movable into an unloading position in which half-shell  33  engages the seat  10  immediately upstream in the rotation direction of wheel  7 . 
     Actuating and control device  26   a  of each sleeve  26  also comprises a tappet roller  34  fitted in rotary manner to the free end of arm  28  to rotate about a respective axis, parallel to axis  22 , inside a respective track  35 , which is formed on cam  32  and extends about axis  8  to control the angular position of sleeve  26  about axis  22  of pin  21  alongside variations in the angular position of seat  11  about axis  8 . 
     Track  31  of cam  32  is so formed that, as wheel  7  rotates about axis  8 , the two rocker arms  25  of each seat  11  are moved, along axis  22  of respective pin  21 , between a position opening respective gripping device  24 —wherein the two half-shells  33  are separated by a distance greater than the length of a respective group  5  of cigarettes—and a position closing respective gripping device  24 —wherein the two half-shells  33  define respective seat  11  and provide for gripping and retaining a respective group  5  with the respective cigarettes oriented parallel to axis  8 . 
     Track  35  of cam  32  is so formed that, as wheel  7  rotates about axis  8 , the two rocker arms  25  of each seat  11  are rotated, about axis  22  of respective pin  21 , between a loading position—wherein respective gripping device  24 , traveling with wheel  7  along a substantially circular path P through an unloading station  36 , receives a respective group  5  of cigarettes from a known supply wheel  37 —and an unloading position—wherein respective gripping device  24  is positioned with respective half-shells  33  inside the seat  10  immediately upstream in the rotation direction of wheel  7 . 
     In addition to loading station  36 , path P—along which seats  10  also substantially travel—also extends through a further loading station  38 , where each seat  10  receives a respective blank  3  from a known supply wheel  39  comprising a number of conveying heads  40 , each for conveying a respective blank  3  and penetrating a respective seat  10  at loading station  38 . 
     Path P also extends through a further loading station  41  located on the opposite side of station  36  to station  38 , and where wheel  7  cooperates with a further supply wheel  42  having a number of conveying heads  43 , each for conveying a respective collar  4  substantially folded into a U, and for fitting collar  4  onto a respective group  5  at station  41 . 
     Path P also extends through at least one folding station  44  located downstream from station  41 , and where each blank is gradually folded in known manner (not shown) about respective group  5  to form a respective packet  2 ; and through an unloading station  45  where the substantially finished packets  2  are extracted successively in known manner from respective seats  10  by respective conveying heads  46  of a known unloading wheel  47 . 
     Operation of machine  1  will now be described with reference to one pair of adjacent corresponding seats  10  and  11  (i.e. a pair of adjacent seats  10  and  11 , in which seat  11  precedes seat  10  in the rotation direction of packing wheel  7 ), and as of the instant in which seat  10 , traveling with seat  11  about axis  8 , reaches loading station  38 . 
     As seats  10  and  11  travel through loading station  38 , wheel  39  rotates continuously about its own axis to feed a conveying head  40 , together with a respective flat blank  3 , through loading station  38  in time with and at the same speed as seat  10 , the lateral walls  16  of which are set to the open position. At station  38 , head  40  gradually penetrates seat  10  to gradually fold blank  3  into a U and deposit a central portion of blank  3  onto the outer surface of base body  14 , on which blank  3  is retained in the U-folded configuration by suction through holes  15 . 
     As seats  10  and  11  travel through loading station  36 , wheel  37  rotates continuously about its own axis to feed a group  5  of cigarettes through loading station  36  in time with and at the same speed as seat  11 . At station  36 , group  5  is gradually inserted between half-shells  33  of gripping device  24 , which is set to the loading position and closes gradually onto the opposite longitudinal ends  5   a  of group  5  to grip and remove group  5  off wheel  37 . Through station  36  also, the lateral walls  16  of seat  10  are kept in the open position. 
     As seats  10  and  11  subsequently travel between loading stations  36  and  41 , devices  26   a  move gripping device  24  and seat  11  from the loading to the unloading position, in which the two half-shells  33 , together with respective group  5 , are inserted inside seat  10  to form a blank-product assembly  48  wherein blank  3  is folded into a U and houses group  5  still located inside seat  11 . 
     Through station  41 —in which gripping device  24  is set to the closed position and the lateral walls  16  of seat  10  to the open position—assembly  48  is completed by the addition of collar  4 , which has already been folded partially into a U in known manner, and is gradually fitted onto a central portion, left free by half-shells  33 , of group  5  by a conveying head  43 , which travels through station  41  in time with and at the same speed as seat  10 . 
     At this point, gripping device  24  is opened and moved into the loading position to release group  5  inside seat  10 , while lateral walls  16  of seat  10  are moved into the closed position to retain group  5  and respective collar  4  inside seat  10 . Assembly  48  is then fed by wheel  7  through folding stations  44  to unloading station  45 . 
     Though machine  1  is advantageously a continuously-operating machine, the above also applies to noncontinuous machines, by providing, regardless of whether packing wheel  7  rotates continuously or not, for reducing the number of components by performing on one packing wheel operations which, on known machines, would require at least two successive packing wheels, thus reducing the size and cost of the machine in general. 
     Moreover, the particular structure of wheel  7 , and the possibility of feeding a blank  3  and respective group  5  into respective seats  10  and  11  on the wheel itself, and of inserting, on wheel  7  itself, each seat  11  inside the corresponding seat  10  to form assembly  48  inside seat  10 , provide for making the traveling speed of wheel  7  substantially independent of the speed at which group  5  of cigarettes is inserted inside respective blank  3 . 
     In a further embodiment, seat  10  is movable and seat  11  fixed with respect to packing wheel  7 , and a group  5  of cigarettes carried in seat  11  is inserted inside a blank  3  carried in seat  10  by moving first seat  10 . 
     In a further embodiment not shown, both seats  10  and  11  are movable with respect to packing wheel  7 , and a group  5  of cigarettes carried in seat  11  is inserted inside a blank  3  carried in seat  10  by simultaneously moving seats  10  and  11 . 
     Though seats  10  and  11 , in the embodiment shown, are carried on a packing conveyor in the form of a wheel defined by packing wheel  7 , other types of packing conveyor may be used, such as that described in Patent WO 97/03878 and defined by an endless belt. 
     Though designed in the embodiment shown for producing rigid hinged-lid packets of cigarettes, packing machine  1  may, in other embodiments, produce other types of packets, such as rigid non-hinged-lid packets of cigarettes (in which case, the collars are dispensed with), or soft packets of cigarettes (in which case, the collars are dispensed with and the blank is replaced by a sheet of wrapping material). 
     In one particular embodiment not shown, packing machine  1  is a cellophaning machine, in which case, the collars are dispensed with, the blank is replaced by a sheet of plastic wrapping material, and group  5  of cigarettes is replaced by a packet of cigarettes. 
     In further embodiments, movable walls  16  of seat  10  are replaced by fixed walls, and group  5  is retained solely by suction or by other mechanical means associated with seat  10 . 
     In yet a further embodiment, lateral walls  16  of seat  10  are movable, not by rotating about respective axes  18 , but by simply translating parallel to themselves.