Method for applying a wrapping material to a product

Information

  • Patent Grant
  • 6324817
  • Patent Number
    6,324,817
  • Date Filed
    Tuesday, July 6, 1999
    25 years ago
  • Date Issued
    Tuesday, December 4, 2001
    23 years ago
Abstract
A method for wrapping an elongated, substantially parallelepiped product (2) having two opposite longitudinal end bases (8), by engaging the bases (8) of the product (2) by a conveyor head (6) fed continuously by a conveyor (7) along a wrapping path (P1) and folding a sheet (3) of wrapping material into a U about the product (2) along a first portion of the wrapping path and further folding the material along a second portion of the wrapping path to stabilize the fold and form a tubular wrapping (10). The conveyor comprises a wheel (17) and a plurality of conveyor heads on the wheel, each head being movable with respect to the wheel (17) to cause the sheet (3) of wrapping material to cooperate, along the second portion of the wrapping path (P1), with at least one passive fixture (58, 61) operating on the sheet (3) to form the tubular wrapping (10).
Description




The present invention relates to a method of wrapping a product.




The present invention is particularly advantageous for use on machines for cellophaning packets of cigarettes, to which the following description refers purely by way of example.




BACKGROUND OF THE INVENTION




Known machines for cellophaning packets of cigarettes operate substantially in steps, i.e. as opposed to continuously, which seriously limits the maximum operating speed of the machine on account of the maximum acceleration the packets of cigarettes can safely be subjected to without being damaged. The aforementioned known cellophaning packets are constructively similar to the packing machine disclosed U.S. Pat. No. 4,144,695.




Continuous cellophaning machines have been proposed featuring a wrapping wheel comprising a number of conveyor heads, each for engaging a packet of cigarettes and a respective sheet of wrapping material; and, for each conveyor head, the wrapping wheel comprises a number of active and/or passive wrapping fixtures for folding and stabilizing the sheet of wrapping material to form a tubular wrapping about the product.




For example, GB-A-1,134,500 and GB-A-2,235,913 disclose continuous cellophaning machines of the type referred to above.




Known cellophaning machines of the above type, however, are expensive and difficult to produce on account of the complex design of the wrapping wheel, in turn due to the large number of moving components on the wheel.




Moreover, each conveyor head on known cellophaning machines of the above type is allowed only a limited degree of movement on account of the wrapping fixtures about the head, which restriction makes it extremely difficult to feed the product and respective sheet of wrapping material continuously to the head, and to continuously unload the product enclosed in the tubular wrapping off the head.




SUMMARY OF THE INVENTION




It is an object of the present invention to provide a method of wrapping a product, which provides for wrapping a product continuously, involves none of the aforementioned drawbacks, and at the same time is cheap and easy to implement.




According to the present intention, there is provided a method of wrapping, in a sheet of wrapping material, an elongated, substantially parallelepiped product having two opposite longitudinal end bases, the method comprising the steps of feeding said product to a conveyor head, which engages the product by said bases; feeding said conveyor head continuously, and by means of a conveyor, along a wrapping path and through a supply station for supplying said sheet of wrapping material, to assign said conveyor head and said product to said sheet of wrapping material; and, along said wrapping path, moving said conveyor head with respect to said conveyor so that said sheet of wrapping material cooperates with at least one passive wrapping fixture to form, about the product and with said sheet of wrapping material, a tubular wrapping at least partly enclosing said conveyor head.




The present invention also relates to a machine for wrapping a product.




According to the present invention, there is provided a machine for wrapping, in a sheet of wrapping material, an elongated, substantially parallelepiped product having two opposite longitudinal end bases, the machine comprising a conveyor head for engaging said product by said bases; a supply device for feeding said product to said conveyor head; a supply station for supplying said sheet of wrapping material; a conveyor for feeding said conveyor head continuously along a wrapping path and through said supply station to assign said conveyor head and said product to said sheet of wrapping material; at least one passive wrapping fixture for forming, about the product and with said sheet of wrapping material, a tubular wrapping at least partly enclosing said conveyor head; and first actuating means which, along said wrapping path, move said conveyor head with respect to said conveyor so that said sheet of wrapping material cooperates with said passive wrapping fixture.











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, partially sectioned side view of a preferred embodiment of the machine according to the present invention;





FIG. 2

shows a larger-scale view of a detail in

FIG. 1

;





FIGS. 3



a


and


3




b


show schematic, larger-scale views of a second detail in

FIG. 1

in different operating positions;





FIG. 4

shows a larger-scale view in perspective of a third detail in

FIG. 1

;





FIGS. 5



a


and


5




b


show larger-scale views in perspective of a fourth detail in

FIG. 1

in two different operating positions.











DETAILED DESCRIPTION OF THE INVENTION




Number


1


in

FIG. 1

indicates as a whole a continuous cellophaning machine for overwrapping packets


2


of cigarettes in respective sheets


3


of heat-seal wrapping material.




Packets


2


are fed by a known supply device


5


to an input conveyor


4


of machine


1


at an input station S


1


.




Conveyor


4


feeds packets


2


from input station S


1


to a transfer station S


2


with a spacing St


1


actually equal to approximately 180 mm; and, at station S


2


, each packet


2


is transferred to a respective conveyor head


6


fitted to a wrapping conveyor


7


to feed packets


2


successively along a wrapping path P


1


.




The spacing and the traveling speed of packets


2


along path P


1


substantially equal St


1


and V


1


respectively. However, due to certain movements performed, in use, by head


6


with respect to conveyor


7


and described in detail later on, the spacing and traveling speed of packets


2


along path P


1


vary temporarily about values St


1


and V


1


respectively.




As shown more clearly in

FIG. 4

, each packet


2


is elongated and substantially parallelepiped, and comprises two opposite longitudinal end bases


8


and a lateral surface


9


perpendicular to bases


8


; and each conveyor head


6


engages bases


8


of a respective packet


2


.




Along path P


1


, each packet


2


is paired with a respective sheet


3


of wrapping material, which is subsequently folded to form about packet


2


a tubular wrapping


10


, which has two opposite open ends


11


, and at least partially encloses respective conveyor head


6


.




Path P


1


terminates at a transfer station S


3


where each packet


2


is transferred to a wrapping conveyor


12


which feeds packets


2


, enclosed in respective tubular wrappings


10


, successively along a wrapping path P


2


and with a spacing St


2


smaller than spacing St


1


and actually equal to 120 mm.




Along path P


2


, the open ends


11


of each tubular wrapping


10


are closed and stabilized by sealing to complete the overwrapping of packets


2


in respective sheets


3


.




Path P


2


terminates at a transfer station S


4


where the overwrapped packets


2


are transferred to a known output section (not shown) which feeds packets


2


along a drying path P


3


and then to a known output (not shown) of machine


1


.




Packets


2


are therefore fed along conveyor


4


and, substantially, along path P


1


with spacing St


1


, and are fed along path P


2


with a spacing St


2


smaller than St


1


. To maintain a constant flow of packets


2


(i.e. the number of packets


2


processed per unit time) along machine


1


, the traveling speed V


1


of packets


2


along conveyor


4


and path P


1


must be greater than the traveling speed V


2


of packets


2


along path P


2


. In particular, to maintain a constant flow, the ratio between spacings St


1


and St


2


, which is actually 1.5, must equal the ratio between speeds V


1


and V


2


.




Input conveyor


4


comprises a belt


13


looped about two end pulleys


14


and having projections


15


equally spaced with spacing St


1


and for engaging respective packets


2


. One of the two pulleys


14


is mounted idly to rotate about a fixed axis


16


perpendicular to the

FIG. 1

plane, while the other pulley


14


is powered to rotate continuously about a further fixed axis


16


also perpendicular to the

FIG. 1

plane.




Conveyor


7


comprises a powered wheel


17


, which is mounted to rotate continuously about a fixed central axis


18


parallel to axes


16


, and which supports a number of conveyor heads


6


equally spaced about axis


18


.




As shown more clearly in

FIG. 4

, each conveyor head


6


comprises a pair of opposed gripping pads


19


, each of which engages a respective base


8


of a packet


2


and is fitted to a respective rocker arm


20


connected to wheel


17


by a respective arm


21


, which is fitted at one end—together with arm


21


of the opposite pad


19


—to a shaft


22


connected in rotary manner to wheel


17


and oscillated, with respect to wheel


17


and about a respective axis


23


parallel to axis


18


, by a known cam control device (not shown).




Each rocker arm


20


is hinged to respective arm


21


, at the end opposite the end fitted to shaft


22


, by means of a hollow shaft


24


fitted idly to arm


21


to rotate, with respect to arm


21


, about a respective axis


25


parallel to axis


18


, and to slide axially, with respect to arm


21


, along axis


25


.




Each rocker arm


20


comprises an arm


26


fitted on the end with respective pad


19


; and an arm


27


, which, as shown in

FIG. 2

, is connected at the end to a control device


28


comprising a sleeve


29


fitted idly to shaft


22


of arm


21


of the head


6


immediately upstream in the rotation direction (anticlockwise in

FIG. 1

) of wheel


17


. Sleeve


29


is also slid axially along said shaft


22


by a known cam control device (not shown). Device


28


also comprises a lever


30


integral with and extending radially from sleeve


29


, and the free end of which is hinged at


31


to the free end of arm


27


of rocker arm


20


.




Consequently, as each sleeve


29


slides axially along respective shaft


22


, respective pad


19


is moved to and from a closed position (

FIG. 5



a


) contacting respective base


8


of respective packet


2


; and, as a shaft


22


and respective arm


21


oscillate about respective axis


23


, respective rocker arm


20


oscillates about respective axis


25


, given the constant distance between respective hinge


31


and axis


23


of the arm


21


immediately upstream in the rotation direction of wheel


17


.




Each pad


19


comprises a cup-shaped body


32


projecting from pad


19


towards the opposite pad


19


, and the bottom surface of which is defined by respective pad


19


. Cup-shaped body


32


is axially and laterally open, and is defined by relatively thin metal plates


33


fitted to a lateral surface of respective pad


19


to contact, in use, lateral surface


9


of a respective packet


2


.




As shown more clearly in

FIGS. 5



a


and


5




b,


each pad


19


comprises a respective retaining member


34


for retaining sheet


3


of wrapping material in a given fixed position with respect to pad


19


. Retaining member


34


comprises a lever


35


hinged to respective rocker arm


20


and oscillated about an axis


36


crosswise to respective axis


25


by a known cam control device (not shown). Lever


35


carries an end pad


37


, which is movable with lever


35


from a rest position (

FIG. 5



a


) to a work position (

FIG. 5



b


) in which end pad


37


laterally contacts respective gripping pad


19


to retain sheet


3


of wrapping material against gripping pad


19


.




As shown more clearly in

FIG. 2

, machine


1


comprises a belt conveyor


38


located at transfer station S


2


, parallel to and facing conveyor


4


, and defining, together with conveyor


4


, a channel


39


for guiding packets


2


during transfer from conveyor


4


to respective conveyor heads


6


on conveyor


7


. To better perform said guide function, conveyor


38


comprises a projection


40


for engaging a respective packet


2


together with respective projection


15


of conveyor


4


.




Machine


1


comprises a supply station


41


for supplying sheets


3


of wrapping material, and which is located along an initial portion of path P


1


and in turn comprises a known supply unit


42


for feeding a sheet


3


of wrapping material in a direction perpendicular to and through path P


1


. Supply unit


42


receives a continuous strip


43


of heat-seal wrapping material, which is unwound off a reel (not shown) and is cut by a pair of cutting rollers


44


into portions, each defining a sheet


3


of wrapping material.




Machine


1


comprises a passive wrapping fixture


45


(i.e. a fixture having no moving parts) located in a fixed position along path P


1


, immediately downstream from supply station


41


, and which is defined by a folding channel


46


for folding a sheet


3


of wrapping material into a U about a respective packet


2


fed by a respective head


6


along path P


1


. Channel


46


is defined by a pair of facing walls


47


located on opposite sides of path P


1


and having respective folding brushes


48


.




Once folded into a U about respective packet


2


, each sheet


3


of wrapping material has two wings


49


and


50


projecting transversely and rearwards from packet


2


.




Machine


1


comprises an active wrapping fixture


51


(i.e. a fixture having at least one moving part) located along path P


1


, immediately downstream from folding channel


46


, to fold wing


49


through 90° onto packet


2


.




Active wrapping fixture


51


comprises a wheel


52


powered to rotate continuously about a fixed axis


53


parallel to axis


18


; and a number of wrapping tools


54


, each of which provides for folding wing


49


through 90° onto packet


2


, and is connected to the free end of a respective arm


55


. Each arm


55


is hinged to wheel


52


at the end opposite said free end, and is oscillated, with a given eccentricity and about an axis


56


parallel to axis


53


, by a known cam control device (not shown).




Wrapping tool


54


comprises a generating device


57


for generating an electrostatic field, which acts on wing


49


to polarize and enable wing


49


, once folded, to adhere at least temporarily to packet


2


.




Machine


1


also comprises a passive wrapping fixture


58


located in a fixed position along path P


1


, downstream from folding channel


46


, to fold wing


50


of sheet


3


of wrapping material through 90° onto respective packet


2


and partly onto the previously folded wing


49


to define respective tubular wrapping


10


.




Wrapping fixture


58


comprises a body


59


having a surface


60


, which defines a folding surface along which packet


2


is substantially rolled, by rotating respective head


6


about respective axis


25


, to fold wing


50


through 90°.




The bottom wall


47


of folding channel


46


extends beyond the top wall


47


and up to the beginning of surface


60


, with which it blends to keep the bottom portion of the U-folded sheet


3


in contact with respective packet


2


.




Machine


1


comprises a number of passive wrapping fixtures


61


, each of which is carried in a fixed position by wheel


17


, is associated with a respective conveyor head


6


, and is defined by a sealing device


62


for stabilizing a tubular wrapping


10


by on-edge sealing the superimposed portions of wings


49


and


50


folded onto respective packet


2


.




As shown in

FIG. 1

, wrapping conveyor


12


comprises a conveyor belt


63


moving continuously along path P


2


and having projections


64


spaced with spacing St


2


to engage and feed forward packets


2


. Path P


2


comprises a straight initial portion P


4


; a downstream straight portion P


5


connected to portion P


4


by a curved portion; and a circular end portion P


6


extending about a fixed axis


65


parallel to axis


18


.




Along circular portion P


6


, belt


63


extends about a wheel


66


powered to rotate continuously about axis


65


; and, at the opposite ends of portion P


4


, belt


63


extends about a pair of idle transmission rollers


67


rotating about respective axes


68


parallel to axis


65


.




Conveyor


12


comprises a channel


69


extending along portion P


4


and defined on one side by a fixed surface


70


and on the other side by conveyor belt


63


.




Machine


1


comprises a folding device


71


located along straight portion P


5


of path P


2


to fold the open ends


11


of each tubular wrapping


10


onto respective packet


2


as packet


2


travels along portion P


5


of path P


2


. Folding device


71


comprises a known first movable folding element (not shown) for making a first fold of open ends


11


; and two known fixed helical folding elements


72


(only one shown in

FIG. 1

) located on either side of path P


2


to engage respective open ends


11


of each tubular wrapping


10


.




Machine


1


also comprises a transfer unit


73


located between conveyors


7


and


12


at transfer station S


3


, and which in turn comprises a belt


74


looped about a pair of end pulleys (not shown) to guide packets


2


to an input


75


of channel


69


. Belt


74


comprises projections


76


spaced with spacing St


1


to engage and a feed forward packets


2


as packets


2


are transferred from conveyor


7


to conveyor


12


.




Wheel


66


comprises a number of pairs of sealing heads


77


(only a first head in each pair shown in FIG.


1


), which are equally spaced about axis


65


and provide for stabilizing, by sealing, ends


11


of each tubular wrapping


10


folded by folding device


71


. The heads


77


in each pair are positioned facing each other to simultaneously engage respective opposite ends


11


of a respective tubular wrapping


10


.




Operation of cellophaning machine


1


will now be described with reference to one packet


2


, and as of the instant in which packet


2


is fed by supply device


5


onto conveyor


4


at station S


1


and with spacing St


1


.




As shown in

FIG. 1

, conveyor


4


engages packet


2


by lateral surface


9


, leaving bases


8


free, and feeds packet


2


continuously to station S


2


where packet


2


is transferred to a respective head


6


which, rotating about axes


18


,


23


and


25


, feeds packet


2


along path P


1


.




As shown more clearly in

FIG. 2

, at station S


2


, respective control device


28


first positions pads


19


of head


6


facing and detached from bases


8


of packet


2


(FIG.


4


), and then moves pads


19


into said closed position (

FIG. 5



a


) in which respective cup-shaped body


32


of each pad


19


engages a respective longitudinal end of packet


2


.




The above passage of pads


19


into the closed position is completed as packet


2


travels along guide channel


39


, at the end of which, packet


2


leaves conveyor


4


and is conveyed solely by respective head


6


along path P


1


and through supply station


41


. At station


41


, supply unit


42


has already positioned a respective sheet


3


of wrapping material, still attached to strip


43


, perpendicular to path P


1


, so that, as packet


2


is fed along path P


1


, a portion


78


—frontwards in the traveling direction—of lateral surface


9


of packet


2


engages a corresponding portion of sheet


3


.




As packet


2


engages sheet


3


, said known cam control device (not shown) moves levers


35


of respective head


6


into said work position (

FIG. 5



b


) in which each respective end pad


37


laterally contacts respective gripping pad


19


to retain sheet


3


of wrapping material in a given fixed position against gripping pad


19


. Sheet


3


is detached from strip


43


by cutting rollers


44


as soon as sheet


3


is clamped by pads


37


.




At this point, as head


6


continues along path P


1


, packet


2


is fed into folding channel


46


, which folds sheet


3


into a U about packet


2


, about respective plates


33


, and partly about respective pads


19


. Folding sheet


3


into a U about plates


33


poses no problem on account of the relatively small thickness of plates


33


and the flexibility of packet


2


and sheet


3


.




In an alternative embodiment not shown, folding channel


46


comprises a generating device for generating an electrostatic field, which acts on sheet


3


to polarize and enable sheet


3


to adhere at least temporarily to packet


2


.




At the end of channel


46


, sheet


3


is folded into a U about packet


2


with wings


49


and


50


projecting crosswise and rearwards from packet


2


. As packet


2


continues along path P


1


, the top wing


49


is folded through 90° onto packet


2


, and in particular onto a surface


79


—rearwards in the traveling direction—of lateral surface


9


of packet


2


, by a respective wrapping tool


54


, which is caused to gradually engage wing


49


by the combination of wheel


52


rotating about axis


53


, and respective arm


55


oscillating about axis


56


.




In the course of the above folding operation, wing


49


is polarized by an electrostatic field, generated by generating device


57


fitted to tool


54


, to adhere, once folded, at least temporarily to packet


2


.




As shown in

FIGS. 2

,


3




a


and


3




b,


once wing


49


is folded, packet


2


is substantially rolled along folding surface


60


to fold the bottom wing


50


of sheet


3


of wrapping material through 90° onto surface


79


of packet


2


and partly onto the previously folded wing


49


to form tubular wrapping


10


. Packet


2


is rolled along surface


60


by rotating respective head


6


about respective axis


25


; which rotation is effected by said known cam control device (not shown) swinging respective arm


21


about respective axis


23


, and provides for moving packet


2


from a substantially tangential to a substantially radial position with respect to axis


18


.




As shown more clearly in

FIGS. 3



a


and


3




b,


on leaving surface


60


, surface


79


, on which wings


49


and


50


have been overlapped, is engaged substantially seamlessly by a work surface


80


of a respective sealing device


62


carried on wheel


17


and associated with respective conveyor head


6


. That is, on coming into contact with respective packet


2


, surface


80


is so located as to form a substantially seamless extension of surface


60


, thus preventing sheet


3


, and in particular the newly folded wing


50


, from springing back to its original configuration.




Surface


79


remains contacting sealing device


62


along a portion of path P


1


extending more than 90° about axis


18


, from the output end of folding surface


60


up to transfer station S


3


, and which is sufficient to seal the superimposed portions of wings


49


and


50


and so stabilize tubular wrapping


10


.




Before reaching station S


3


, tubular wrapping


10


is released by retaining member


34


, the pads


37


of which are restored to the rest position; and, at transfer station S


3


, packet


2


is restored to a substantially tangential position with respect to axis


18


by rotating respective head


6


about respective axis


25


, which rotation is achieved by said known cam control device (not shown) swinging respective arm


21


about respective axis


23


.




At station S


3


, packet


2


is engaged simultaneously by conveyor head


6


and by belt


74


of transfer unit


73


, which assists in guiding packet


2


into channel


69


where packet


2


is engaged by belt


63


and respective projections


64


.




On entering channel


69


, packet


2


is engaged by belt


63


, and in particular by projections


64


of belt


63


, and is released by conveyor head


6


, the two pads


19


of which are moved by control device


28


into an open position in which respective cup-shaped bodies


32


are separated by such a distance as not to interfere with packet


2


or respective tubular wrapping


10


.




Since packets


2


are fed by conveyor


7


along path P


1


at speed V


1


and with spacing St


1


, and are fed by conveyor


12


along path P


2


at speed V


2


and with spacing St


2


, which are respectively slower and smaller than speed V


1


and spacing St


1


, packets


2


undergo a change in speed at station S


3


, and in particular are slowed down during transfer from head


6


of conveyor


7


to conveyor


12


. In one embodiment, the above change in speed is effected gradually by counter-rotating head


6


about respective axis


23


to temporarily reduce the speed of packet


2


with respect the speed V


1


normally imposed by the rotation of wheel


17


.




The continuous movement of belt


63


feeds packet


2


along path P


2


and in particular through channel


69


to straight portion P


5


, along which the two opposite open ends


11


of tubular wrapping


10


are engaged by fixed helical folding elements


72


of folding device


71


and are folded onto bases


8


of packet


2


.




At the end of straight portion P


5


, the two bases


8


of packet


2


, onto which ends


11


of tubular wrapping


10


have been folded, are engaged simultaneously by respective sealing heads


77


in a respective pair of heads


77


on wheel


66


to stabilize, by sealing, ends


11


.




Bases


8


remain in contact with respective sealing heads


77


along a portion of path P


2


extending more than 90° about axis


65


, from the output end of folding device


71


up to transfer station S


4


, and which is sufficient to seal ends


11


and so complete the overwrapping of packet


2


in sheet


3


.




Path P


2


terminates at transfer station S


4


where the overwrapped packet


2


is transferred in known manner to said known output section (not shown), which feeds packet


2


along a circular drying path P


3


extending about an axis


81


parallel to axis


65


, and then to said known output (not shown) of machine


1


.




In an alternative embodiment not shown, machine


1


comprises an application station located along conveyor


4


and having an application device for applying a label and/or coupon to each packet


2


.




In a further embodiment not shown, folding surface


60


is provided with a respective generating device for generating an electrostatic field, which acts on wing


50


to polarize and enable wing


50


, once folded, to adhere at least temporarily, to packet


2


.




Machine


1


is therefore relatively straightforward and cheap to produce by comprising only three wrapping tools—two of which passive—which are shared by all of packets


2


; and by wrapping wheel


17


comprising a small number of moving parts (conveyor heads


6


) and only supporting passive wrapping fixtures (sealing devices


62


).




Moreover, machine


1


comprises two main sections defined respectively by wrapping conveyors


7


and


12


, and in each of which packets


2


are conveyed at a respective speed and with a respective spacing. More specifically, conveyor


7


feeds packets


2


along path P


1


at speed V


1


and with spacing PA


1


, while conveyor


12


feeds packets


2


along path P


2


at speed V


2


and with spacing PA


2


.




The above characteristic enables each section to operate with the spacing and/or at the speed best suited for the specific job performed by the section, and therefore provides for reducing cost and size for a given performance of machine


1


. That is, along path P


1


, the wider spacing provides for better arranging heads


6


about axis


18


, and the faster traveling speed of heads


6


for rapidly removing the U-folded sheet


3


from station


41


and so preventing wings


49


and


50


of sheet


3


from interfering with the next sheet


3


. Along path P


2


, on the other hand, the narrower spacing and slower traveling speed enable the use of a relatively small-diameter wheel


66


to reduce the overall size of machine


1


.



Claims
  • 1. A method of wrapping, in a sheet of wrapping material, an elongated, substantially parallelepiped product having two opposite longitudinal end bases, the method comprising the steps of feeding said product to a conveyor head; engaging the end bases of the product by said conveyor head; feeding said conveyor head and said product continuously by a conveyor, along a wrapping path and through a supply station while keeping said bases parallel to the wrapping path, said conveyor comprising a wheel and a plurality of conveyor heads on said wheel; supplying said sheet of wrapping material transversely to the wrapping path, engaging said sheet of material at the same time by said conveyor head and by said product; and, moving said conveyor head with respect to said wheel along said wrapping path so that said sheet of wrapping material is folded by at least one passive wrapping fixture to form, about the product and with said sheet of wrapping material, a tubular wrapping at least partly enclosing said conveyor head, wherein said wrapping path comprises a first and a second portion in series in a traveling direction of said conveyor head; said sheet of wrapping material being folded into a U about the product and about at least part of said conveyor head along said first portion of the wrapping path, and being further folded and then stabilized along said second portion of the wrapping path to obtain said tubular wrapping; said passive wrapping fixture being located along said second portion of the wrapping path.
  • 2. A method as claimed in claim 1, wherein said tubular wrapping is stabilized by sealing.
  • 3. A method as claimed in claim 1, wherein said passive wrapping fixture comprises a fixed passive fixture; said product being caused to cooperate with said fixed passive fixture by the combination of a first movement of said wheel along said wrapping path, and a second movement of said conveyor head with respect to said wheel.
  • 4. A method as claimed in claim 1, wherein said fixed passive fixture comprises a folding surface; the U-folded said sheet being brought gradually into contact with said folding surface by a movement of said conveyor head with respect to said wheel to fold through 90° and onto said product a wing of the sheet projecting transversely from the product.
  • 5. A method of wrapping, in a sheet of wrapping material, an elongated, substantially parallelepiped product having two opposite longitudinal end bases the method comprising the steps of feeding said product to a conveyor head; engaging the end bases of the product by said conveyor head; feeding said conveyor head and said product continuously by a conveyor, along a wrapping path and through a supply station while keeping said bases parallel to the wrapping path said conveyor comprising a wheel and a plurality of conveyor head s on said wheel; supplying said sheet of wrapping material transversely to the wrapping path, engaging said sheet of material at the same time by said conveyor head and by said product; and, moving said conveyor head with respect to said wheel along said wrapping path so that said sheet of wrapping material is folded by at least one passive wrapping fixture to form, about the product and with said sheet of wrapping material, a tubular wrapping at least partly enclosing said conveyor head wherein said passive wrapping fixture comprises a passive fixture fixed with respect to said wheel; said product being caused to cooperate with said passive fixture by a movement of said conveyor head with respect to said wheel.
  • 6. A method as claimed in claim 1, wherein said passive fixture comprises a sealing device against which said product and said sheet of wrapping material are maintained along a given portion of said wrapping path.
  • 7. A method as claimed in claim 1, wherein said conveyor head is moved with respect to said wheel to cause said sheet of wrapping material to cooperate with at least two passive wrapping fixtures to fold the sheet of wrapping material to form, about the product said tubular wrapping at least partially enclosing said conveyor head.
  • 8. A method as claimed in claim 7, wherein a first of said two passive wrapping fixtures is a fixed passive fixture and comprises a folding surface; the U-folded said sheet being brought gradually into contact with said folding surface by a movement of said conveyor head with respect to said wheel to fold through 90° and onto said product a wing of the sheet projecting transversely from the product.
  • 9. A method as claimed in claim 7, wherein a second of said two passive wrapping fixtures is a sealing device fixed with respect to said wheel and against which said product and said sheet of wrapping material are maintained along a given portion of said wrapping path; said product and said sheet being caused to cooperate with said sealing device by a movement of said conveyor head with respect to said wheel.
  • 10. A method of wrapping, in a sheet of wrapping material, an elongated, substantially parallelepiped product having two opposite longitudinal end bases, the method comprising the steps of feeding said product to a conveyor head, engaging the product by said bases by said conveyor head feeding said conveyor head and said product continuously by a conveyor, along a wrapping path and through a supply station; said conveyor comprising a wheel and a plurality of conveyor heads on said wheel; supplying said sheet of wrapping material transversely to the wrapping path; engaging said sheet of wrapping material by said conveyor head and by, said product; and moving said conveyor head with respect to said wheel along said wrapping path so that said sheet of wrapping material is folded by at least one passive wrapping fixture to form, about the product and with said sheet of wrapping material, a tubular wrapping at least partly enclosing said conveyor head; said sheet of wrapping material being first folded into a U about the product and about at least part of said conveyor head, the U-folded sheet of wrapping material having a first and a second wing projecting transversely from said product; folding said first wing through 90° onto the product by an active wrapping fixture; and folding said second wing onto said product and partly onto said first wing by said passive wrapping fixture; and subjecting said first wing to an electrostatic field by said wrapping fixture to adhere the first wing, at least temporarily, to said product.
  • 11. A method of wrapping, in a sheet of wrapping material, an elongated, substantially parallelepiped product having two opposite longitudinal end bases, the method comprising the steps of feeding said product to a conveyor head; engaging the product by said end bases by said conveyor head; feeding said conveyor head and said product continuously by a conveyor, along a wrapping path and through a supply station; said conveyor comprising a wheel and a plurality of conveyor heads on said wheel; supplying said sheet of wrapping material transversely to the wrapping path; engaging said sheet of wrapping material by said conveyor head and by said product moving said conveyor head along said wrapping path, with respect to said wheel so that said sheet of wrapping material is folded by at least one passive wrapping fixture to form, about the product and with said sheet of wrapping material, a tubular wrapping at least partly enclosing said conveyor head; said movement of said conveyor head with respect to said wheel including a first oscillation of said conveyor head about a first axis, and a second oscillation of said first axis about a second axis parallel to the first axis and integral with said wheel.
Priority Claims (1)
Number Date Country Kind
BO98A0417 Jul 1998 IT
US Referenced Citations (6)
Number Name Date Kind
2720738 Brightwell Oct 1955
4144695 Seragnoli Mar 1979
4866912 Deutsch Sep 1989
5533323 Osti et al. Jul 1996
5794413 Draghetti Aug 1998
5839253 Draghetti Nov 1998
Foreign Referenced Citations (2)
Number Date Country
1134500 Nov 1968 GB
2235913 Mar 1991 GB