WO2007132330A1

WO2007132330A1 - A method and a device for wrapping products

Info

Publication number: WO2007132330A1
Application number: PCT/IB2007/001235
Authority: WO
Inventors: Eros Stivani; Sandro Salicini
Original assignee: Azionaria Costruzioni Macchine Automatiche A.C.M.A. S.P.A.
Priority date: 2006-05-17
Filing date: 2007-05-14
Publication date: 2007-11-22
Also published as: ITBO20060374A1; EP2024232A1; EP2024232B1; ATE529337T1

Abstract

In a method for wrapping products such as items of confectionery, each product (1) is first enveloped in part by a respective leaf (2) of wrapping material so as to create an intermediate wrap presenting a first flap (3) and a second flap (4), projecting from the product (1) on either side of one face (5) that remains exposed initially. The first flap (3) is then bent in a direction (Fl) causing it to rotate inwards and cover the exposed face (5) of the product (1), while also closing on the second flap (4) in such a way that an area (7) of mutual contact is established between the two flaps (3, 4), whereupon the first and second flaps (3, 4) are bent further in the same direction (F1) and flattened against an adjoining flank face (5a) of the product (1), so as to form a semi-finished tubular wrapper (8). Finally, the two ends (9) of the tubular wrapper (8) are sealed, preferably by fashioning twist closures (10).

Description

A method and a device for wrapping products

Technical Field

The present invention relates to a method and a device for wrapping products .

The invention finds application to advantage in the continuous packaging of edible products such as chocolates, sweets and the like, to which reference is made explicitly in the following specification albeit with no limitation in general scope implied.

Background Art

In prior art packaging machines, products advance at regular intervals and in ordered succession along a predetermined path toward a station where they are picked up by relative transfer components and carried first into a loading station, where each is paired with a respective leaf of wrapping material, then progressively through a series of folding stations in which each leaf is fashioned into a closed wrapper around each product.

Conventional devices generally comprise a wrapping drum with peripheral carrier units such as grippers or pockets by which the products, partly enveloped in respective leaves of wrapping material bent to a "U" profile around each one, are caused to advance along a set path and through dedicated folding stations. Each leaf bent thus to a "U" profile must undergo further folding steps in order to produce a closed wrapper, including a first step whereby the two parts of the leaf projecting from the side corner edges of the relative product are bent inward to form a semifinished tubular wrapper about the product . The open ends of the tubular wrapper are then secured, for example by fashioning twist closures.

A process of this type is disclosed in EP 0816229, which relates to a device for packaging small objects in respective wrappers with gathered ends. The patent device is designed to envelop a product partially in a leaf of wrapping material, forming an intermediate wrap folded about the product and presenting what is substantially a "U" profile. The product thus appears with one edge of the leaf of wrapping material projecting from each of two opposite faces, extending parallel and beyond the dimensional outline of the part-enveloped product. Thereafter, one only of the two edges is bent and flattened against a sealing area of the other edge, to which it remains attached. The other edge is then bent in the opposite direction, together with the attached portion of the first edge flattened previously, and pressed against this same first edge to form a seal. With these steps completed, both edges adhere closely to the product and the leaf of wrapping material forms a tubular wrapper, enveloping the product. Finally, the two ends of the tubular wrapper are pinched and gathered to form respective twist closures. The folding method briefly outlined is somewhat complex, given that the two edges projecting from the product must be bent in opposite directions. This means that the device by which the folding steps are performed must necessarily be equipped with elements capable of alternating motion, operating in different directions and orientations, a factor that tends both to complicate the structure and to impact negatively on the cost of building and maintaining the device. The object of the present invention is to provide a method and a device of the type in question, such as will be unaffected by the drawbacks described above.

In particular, it is an object of the invention to provide a method of wrapping products that can be accomplished quickly and easily.

A further object of the invention is to provide a device for wrapping products that can be rendered structurally simple, and therefore economic and efficient .

Disclosure of the Invention The stated object is realized according to the present invention in a method of wrapping products as recited in one or more of claims 1 to 18.

The stated object is realized likewise, according to the invention, in a device for wrapping products as recited in one or more of claims 19 to 28.

The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: -figures Ia-Ic illustrate a succession of steps by which products are wrapped employing the method in accordance with the present invention;

-figures 2a-2d show a variation on the succession of steps in figures Ia-Ic, employing the method of the present invention;

-figure 3a is a perspective view showing a product partially wrapped by the method of the invention; -figure 3b shows a product fully wrapped by the method of the invention;

-figures 4a-4f show portions of a device for wrapping products, in accordance with the invention, viewed in operating configurations assumed respectively during the steps of figures Ia-Ic; -figures 5a-5d show portions of the device as in figures 4a-4f, representing an alternative embodiment and viewed in operating configurations assumed respectively during the steps of figures Ia-Ic; -figure 6 is a perspective view showing the portion of the device in figure 5d;

-figures 7a-7d show a further variation on the succession of steps by which products are wrapped employing the method of the present invention.

With reference to the drawings, numeral 1 denotes a product wrappable by the method according to the present invention.

Such a product 1 might for instance be a chocolate, toffee or similar item of confectionery appearing parallelepiped in shape, albeit the shape in question is indicated by way of example and with no limitation implied. The product 1 might also be a sweet or candy of spherical or oval shape.

The product 1 is first enveloped partially in a leaf 2 of wrapping material, in such a way as to form an intermediate wrap presenting a first flap 3 and a second flap 4 projecting from the product 1 on opposite sides of a free face 5 presented by the selfsame product 1. ' In effect, the free face 5 is the one side face of the product 1 that will remain unassociated or at least not in direct contact with the leaf 2, when this first step of the method has been completed. Accordingly, the leaf 2 assumes a configuration presenting a substantially U-shaped profile, partly enveloping the product 1, with the free face 5 and the two opposite end faces 6 of the product 1 left exposed, albeit one only of these same faces is visible in the drawings (figures Ia and 2a) .

In the example of the drawings, the leaf 2 is associated with three side faces of the product 1, leaving the fourth side face exposed.

Referring to the sequence of figures Ia-Ic, the leaf appears, on completion of the partial enveloping step (figure Ia) , with the first flap 3 and second flap 4 extending away from one another in opposite directions, departing from respective opposite corner edges of the product 1 and occupying substantially the same plane as that occupied by the free face 5 of the product 1.

Referring to the sequence of figures 2a-2d, the leaf appears, on completion of the partial enveloping step (figure 2a) , with the first flap 3 and second flap 4 extending away parallel one to another and substantially perpendicular to the free face 5.

In the next step, the first flap 3 only is bent in a predetermined direction Fl (rotated anticlockwise as seen in figures Ia-Ic and 2a-2d) toward the free face 5 of the product 1 and toward the second flap 4, and offered flush to the second flap 4, thereby establishing an area 7 of contact between the first and second flaps 3 and 4.

This same area 7, which may be a portion of the first flap 3 or of the second flap 4, or of both, is gummed, or coated with a layer of cold glue, so that the resulting tubular sheath formed with the leaf 2 of wrapping material can be sealed longitudinally. Alternatively, the area 7 of contact might be sealed with hot melt glue, or welded.

In the sequence of figures Ia and Ib, the first flap 3 is rotated approximately 180° about a line parallel and adjacent to one corner edge of the product 1, to the point of covering the free face 5 of the product and uniting with the second flap 4 (figure Ib) .

In the sequence of figures 2a and 2b, a proximal portion of the first flap 3 is at first rotated through approximately 90° about the line parallel and adjacent to the corner edge, whilst a distal portion of this same flap 3 is united and thereupon rotated together with the second flap 4 into the same configuration as shown in figure Ib (figure 2c) . Once brought together, the first flap 3 and the second flap 4 will preferably be pressed one against the other along the area 7 of contact to complete the longitudinal seal . Referring to the succession of steps illustrated in figures Ia-Ic, the pressing step is effected while the two flaps 3 and 4 lie in flush contact with one another and parallel to the free face 5 (figure Ib) , or rather on completion of the step whereby the first flap 3 is folded against the second flap 4.

In the example of figures 2a-2d, the pressing step can be effected when the first flap 3 enters into contact with the second flap 4 (figure 2b) , or after the second flap 4 has been rotated finally into a position that produces the same configuration as in figure Ib (figure 2c) .

Thereafter, the first flap 3 and second flap 4 are bent further in the predetermined direction Fl and flattened against the product 1, so as to form a tubular wrapper 8 (figure 3a) .

As discernible in figures Ic and 2d, the first and second flaps 3 and 4 are bent together and flattened against a flank face 5a of the product 1 lying substantially perpendicular to the free face 5. The step of pressing the first flap 3 against the second flap 4, which in the preferred example of the drawings is effected before flattening the first and second flaps 3 and 4 together against the product 1, might equally well take place after this same step has been completed. Importantly, the sequence of steps described above might or might not be effected seamlessly, or rather with no break in continuity between one step and the next, and the foregoing description of distinct steps ^' is intended simply to detail the movements induced in the leaf 2 of wrapping material .

Finally, the resulting tubular wrapper 8 presents two ends 9 projecting longitudinally beyond the end faces of the product 1, which are pinched and sealed with cold glue or hot melt adhesive or by a welding operation, preferably with the formation of twist type closures 10 (figure 3b) , employing a familiar procedure not described further.

The method described thus far can be implemented by means of a device 11 according to the invention for . wrapping products I₇ which forms part of a wrapping machine not illustrated in its entirety.

The device 11 comprises a conveyor 12 presenting a plurality of slots 13 ordered in succession and caused to advance along a predetermined feed path 14 in a predetermined feed direction F2.

Referring to both of the examples illustrated in figures 4a-4f and 5a-5d, the conveyor 12 consists in a wrapping wheel carried by a bulkhead 15 of the packaging machine, set in rotation at a substantially constant angular velocity about a horizontal axis 16 normal to the bulkhead 15 and turning clockwise (as seen in the accompanying drawings) in the feed direction F2 aforementioned. The predetermined feed path 14 describes an arc to a circle. In alternative embodiments of the device (not illustrated) the feed path 14 might describe a different trajectory, for example rectilinear.

Each slot 13 is designed to admit a product 1 partly enveloped in the leaf 2 of wrapping material, and with the first flap 3 and the second flap 4 projecting from the slot 13.

In the preferred embodiment of figures 4a-4f, each of the single slots 13 is created between the pincer ends 17 of a respective main gripper 18. The main grippers 18 are mounted in angularly equispaced positions around the wrapping wheel 12, radiating from the axis 16 of rotation.

In the alternative embodiment of figures 5a-5d, the single slot 13 is afforded by a pocket 19 formed in the cylindrical surface of revolution presented by the wrapping wheel 12. Likewise in this instance, preferably, the pockets 19 are angularly equispaced. To enable the placement of each partially enveloped product 1 and the relative leaf 2 in a respective slot 13, the device 11 is equipped with a loading station 20 located on the predetermined feed path 14.

The loading station 20 comprises a push rod 21 set in motion transversely to the feed path 14 between a position distanced from the path 14 and a position close to the selfsame path 14, in such a way that each successive product 1 can be directed against a relative leaf 2 of wrapping material lying parallel to the feed path 14, occupying a position radially outside the compass of the slots 13 and facing one respective slot 13, then propelled into the slot 13. As the product 1 is inserted, the leaf 2 of wrapping material is driven forward and forced to wrap around three faces, remaining pinned between the product and the inside walls of the slot 13. The flaps 3 and 4 projecting from the slot 13 remain parallel to the predetermined feed path 14 and lie at least in part against peripheral bearing faces 22 of the wheel 12 interposed between the slots 13 and substantially parallel likewise to the path 14 aforementioned. This configuration of the "product 1 and leaf 2" assembly is as indicated in figure Ia.

In the preferred embodiment of figures 4a-4f, the bearing faces 22 are afforded by terminal portions of the grippers 18, whilst in the alternative embodiment of figures 5a-5d, the bearing surfaces 22 consist in portions of the conveyor 12 proper, or rather of the cylindrical surface of revolution presented by the wrapping wheel 12, interposed between the pockets 19. The device 11 also comprises a fixed restraint 23 positioned close to the predetermined feed path 14, such as will intercept the two flaps 3 and 4 of each leaf 2 in succession, bending the first flap 3 in a predetermined direction Fl opposite to the feed direction F2 , toward the free face 5 of the product 1 and into contact with the second flap 4.

In the example of the drawings, the restraint 23 is embodied as a plate presenting a curved surface 24 breasted closely with the bearing surfaces 22, and combining thus with these same surfaces 22 to delimit a passage 25 for the flaps 3 and 4. The plate 23 also presents a locating edge 26 positioned close to the bearing surface 22 and directed toward the loading station 20. The distance between the edge 26 and the bearing surfaces 22 is such that the first flap 3 of the leaf will be intercepted by the selfsame edge 26, bent back and flattened against the product 1 and the second flap 4 (figure 4c) . This configuration of the "product 1 and leaf 2" assembly is as indicated in figures Ib and 2c.

To keep the two flaps 3 and 4 positioned against the bearing surfaces 22 during the insertion of the product and until their interception by the plate 23, the device 11 is equipped with retaining means 27 operating on the endmost edges of the leaf 2 before it is bent and folded.

The means in question, not shown in figures 4a-4f, are indicated in figures 5a and 5b as two foils 28 positioned over the bearing surfaces 22, one on either side of a relative slot 13, whilst the slot 13 coincides with the loading station 20.

Such mechanical retaining means can be supplemented or substituted by vacuum type means. In the example of figures 5a-5d, for instance, the device 11 further comprises ducts 29 connected to a vacuum pump 29a (illustrated schematically) and opening onto a top surface 30 of the plate 23 adjacent to the locating edge 26. The top surface 30 is substantially flat and disposed parallel to the predetermined feed path 14 followed by the products 1 taken up at the loading station 20. The first flap 3 of the leaf 2 is held by the flat surface 30 before and during the insertion of the product 1 into the slot 13 together with the leaf 2. The top surface 30 and the curved surface 24 of the plate 23 converge toward the locating edge 26.

Also forming part of the device 11 is a sealing station 31 located along the feed path 14, at a point beyond the fixed restraint 23. The function of this station 31 is to secure the two flaps 3 and 4 one to another longitudinally, along the area 7 of mutual contact. In the examples illustrated, where the seal is effected by means of a cold glue, the flaps 3 and

4 are also pressed together at this same station 31.

In the first embodiment of figures 4a-4f, more particularly, the sealing station 31 comprises a pair of presser tools 32 and 33 capable of movement toward or away from one another in a direction transverse to the predetermined feed path 14 and engaging the two flaps on opposite sides of the area 7 of contact (figure 4d) . The presser tools 32 and 33 move in a radial direction, relative to the axis 16 of rotation of the wrapping wheel 12, and are positioned in such a way that the two united flaps 3 and 4 will pass between them. The device 11 might be equipped, for example, with a plurality of inboard presser tools 32 mounted to the wrapping wheel 12, each alongside a respective gripper 18, and just one radially outboard presser tool 33 located at the sealing station 31.

In the second embodiment of figures 5a-5d, the sealing station 31 incorporates a presser tool 34 associated with the bearing surfaces, such as will force the area 7 of mutual contact against one of the bearing surfaces 22, and the two flaps 3 and 4 one against the other. In particular, the presser tool 34 comprises a roller 35 installed preferably within a housing 36 afforded by a portion 37 of the plate 23 at the end remote from the locating edge 26 (figure 5c) . Again preferably, the roller 35 is also anchored to the plate 23 through the agency of spring means 38, by which it is biased toward the bearing surface 22. Retained by one of the surfaces 22, the two flaps 3 and 4 are caused by the rotation of the wrapping wheel 12 to pass under the roller 35, which presses them one against the other.

Also located along the feed path 14, beyond the fixed restraint 23 and the sealing station 31 in the feed direction F2 followed by the products 1, is a folding station 39 where the first flap 3 and the second flap 4 are bent together in the direction denoted Fl, that is to say in the original folding direction of the first flap 3, and flattened against the product 1. This configuration of the "product 1 and leaf 2" assembly is as indicated in figures Ic, 2d and 3a.

In the example of figure 4e, the folding station 39 is equipped with an auxiliary gripper 40 such as will retain the product 1 momentarily when released by the main gripper 18 during the folding step. The auxiliary gripper 40 is disposed transversely to the main gripper 18 and presents two pincer ends 41, one only of which is illustrated in figure 4e, placed so as to engage the end faces 6 of the product 1. The auxiliary gripper 40 is capable of movement between an operating position of close proximity to the main gripper 18, when the main gripper is in the folding station 39, and a non-operating position distanced from the wrapping wheel 12 so as not to interfere with the movement of the selfsame wheel. When in the operating position, the jaws 41a of the auxiliary gripper 40 straddle one pincer end 17 of the main gripper 18 with sufficient clearance to ensure there is no interference with this same end 17 when the pincer ends 41 close on the product 1. Numeral 42 denotes a folder capable of movement in a radial direction, transversely to the feed path 14, and penetrating between the open pincer ends 17 of the main gripper 18, in such a way as to engage the area 7 of contact and flatten it against one flank face of the product 1. Thus, on entering the folding station 39, the product is taken up by the auxiliary gripper 40 and released by the main gripper 18. The folder 42 can then slip between the product 1 and the pincer end 17 of the main gripper 18 situated on the side remote from the auxiliary gripper 39, engaging the flaps 3 and 4 and skimming the flank face of the product 1, with the result that the flaps 3 and 4 are flattened against the selfsame flank face.

With the tubular wrapper 8 formed, the product 1 is taken up again by the main gripper 18 and released by the auxiliary gripper 39 (figure 4f) . The product 1 is carried into a further station equipped with means of conventional type, not illustrated, by which the two ,ends 9 of the tubular wrapper 8 are secured. Such means will be designed preferably to form the ends into twist closures 10.

In the alternative embodiment of figures 5a-5d, the folding station 39 is equipped with a take-up gripper denoted 43, indicated in figure 5d, which operates in conjunction with an auxiliary push rod 44 housed slidably in the pocket 19. The auxiliary push rod 44 is capable of movement between a retracted position, lying at the back of the pocket 19, and an extended position occupying the mouth of the pocket 19. Each pocket 19 is equipped with a respective auxiliary push rod 44 which, when the pocket 19 draws into alignment with the loading station 20, moves from the extended position to the retracted position so as to accompany the movement of the product 1 into the pocket 19, and when the pocket 19 is aligned with the folding station 39, moves from the retracted position to the extended position so as to ease the product 1 out of the pocket 19 and between the jaws 45 of the take-up gripper 43. During this extending movement, one of the jaws 45 will operate as a folder, engaging the flaps 3 and 4 and flattening them against one flank face of the product 1.

More exactly, the folding station 39 lies next to the sealing station 31, immediately beyond the end portion 37 of the plate 23. This same end portion 37 presents a projection 46 extending radially away from the axis 16 of the wrapping wheel 12 and furnished with radial grooves 47 shaped to match corresponding members 48 presented by one jaw 45 of the take-up gripper 43 (figure 6) .

The take-up gripper 43 is capable of movement between a position distanced from the projection 46, and a position of engagement in which the members 48 are inserted in the grooves 47 to provide a uniform bearing surface for the product 1 wrapped partially in the leaf 2 of wrapping material. The projection 46 also combines with the members 48 to bend and flatten the flaps 3 and 4 against the product 1.

Following the transfer of the product 1, enveloped in its tubular wrapper 8, from the pocket 19 to the take-up gripper 43, the gripper will close firmly on the wrapper 8 and transfer the product 1 to a further station equipped with means designed to secure the two ends 9 of the tubular wrapper 8, for example by forming a twist closure 10 on each one.

With reference to the examples of figures 7a and 7b, which show another possible embodiment of the wrapper, the first and second flaps 3 and 4 are disposed mutually parallel and perpendicular to the free face 5 of the product. The leaf 2 thus assumes a configuration substantially of "C" profile, leaving one face 5 of the product 1 exposed (figure 7a) as in the examples described previously.

The two flaps 3 and 4 are then folded one toward the other, by rotating the first flap 3 clockwise and the second flap 4 anticlockwise, as viewed in figure

7a, at least partially, to the point at which the flaps 3 and 4 can be united and secured one to another by a hot or cold sealing step, along an intermediate area adjacent to the free face 5 and lying between an adjoining face 5b equivalent to the face 5a mentioned previously, and the face of the product 1 parallel and opposite to this same face 5b

(figure 7b) . The first flap 3 is then bent together with the second flap 4 in the same clockwise direction as previously, to the point at which the second flap 4 lies parallel to the formerly free face 5, between this same face 5 and the first flap 3 (figure 7c) . In the event of the flaps 3 and 4 extending beyond the corner edge of the face 5 against which they are flattened, the outermost portions of the flaps 3 and 4 can be bent further in the same clockwise direction as previously, into a position parallel with the adjoining face 5b of the product 1 (figure 7d) .

In practice, the flaps 3 and 4 can be sealed one to another not only at the step illustrated in figure 7b but also during the step illustrated in figure 7c or even the final step illustrated in figure 7d.

Claims

1) A method of wrapping products, characterized in that it includes the steps of :

- partly enveloping a product (1) in a respective leaf (2) of wrapping material, in such a way as to form an intermediate wrap presenting a first flap (3) and a second flap (4) projecting from the product (1) on opposite sides of a free face (5) presented by the selfsame product (1) ; - bending at least the first flap (3) in a predetermined direction (Fl) toward the surface (5) of the product (1) and against the second flap (4) , thereby establishing an area (7) of mutual contact between the first and second flaps (3, 4) ; - bending the first flap (3) and second flap (4) as one in the predetermined direction (Fl) and against the product (1) , so as to form a tubular wrapper (8) ;

- closing the ends (9) of the tubular wrapper (8) .

2) A method as in claim 1, wherein the step of partly enveloping the product (1) concludes with the first flap (3) and the second flap (4) extending in opposite directions one from another and aligned substantially within the plane occupied by the free face (5) of the product.

3) A method as in claim 1, wherein the first flap (3) and the second flap (4) are bent together as one against a flank face (5a) of the product (1) disposed substantially perpendicular to the free face (5) .

4) A method as in claim 1, wherein the first flap (3) and the second flap (4) are united at the area (7) of mutual contact so as to create a longitudinal seal along the tubular wrapper (8) .

5) A method as in claim 4, wherein the first flap

(3) and the second flap (4) are united by means of a cold glue, applied to the area (7) of mutual contact before the first flap (3) is bent against the second flap (4) .

6) A method as in claim 4 or 5, including the further step of pressing the first flap (3) against the second flap (4) at the area (7) of mutual contact.

7) A method as in claim 6, wherein the step of pressing the first flap (3) against the second flap

(4) is effected after the step of bending the first flap (3) against the second flap (4) .

8) A method as in claim 6, wherein the step of pressing the first flap (3) against the second flap

(4) is effected before the step of bending the first flap (3) and the second flap (4) together as one against the product (1) . 9) A method as in claim 1, wherein the step of partly enveloping a product (1) in a respective leaf

(2) of wrapping material is effected by: advancing a slot (13) along a predetermined feed path (14) in a predetermined feed direction (F2) ; positioning the leaf (2) of wrapping material facing the slot (13) and parallel with the predetermined feed path (14) ; directing the product (1) against the leaf (2) of wrapping material and into the slot (13); causing edges of the leaf (2) of wrapping material to be retained against bearing surfaces (22) lying adjacent to the slot (13) and substantially parallel to the predetermined feed path (14) , the edges of the leaf constituting the first flap (3) and the second flap (4) , placed on opposite sides of the free face (5) of the product (1) and lying externally of the slot (13) .

10) A method as in claim 1, wherein the step of bending only the first flap (3) in a predetermined direction (Fl) toward the face (5) of the product (1) and against the second flap (4) is effected by intercepting the first flap (3) through the agency of a fixed restraint (23) mounted adjacent to the predetermined feed path (14) and in close proximity to the bearing surface (22) .

11) A method as in claim 1, wherein the step of bending the first flap (3) and the second flap (4) together as one in the predetermined direction (Fl) and against the product (1) is effected by pushing the product (1) out of the slot (23) and intercepting the area (7) of mutual contact between the first and second flaps (3, 4) by means of a folder (45) .

12) A method as in claim 1, wherein the product (1) is retained in the slot (13) by means of a main gripper (18) with pincer ends (17) delimiting the slot (13) and engaging portions of the leaf (2) of wrapping material associated with the product (1) .

13) A method as in claim 12, wherein the step of bending the first flap (3) and the second flap (4) together as one in the predetermined direction (F2) and against the product (1) is effected by retaining the product (1) with an auxiliary gripper (40) , opening the main gripper (18) , and intercepting the area (7) of mutual contact between the first and second flaps (3, 4) by means of a moving folder (42) .

14) A method as in claim 9, wherein the first and second flaps (3, 4) are united with a cold glue and pressed one against the other by means of a pair of presser tools (32, 33) engaging opposite sides of the area (7) of mutual contact between the first and second flaps (3, 4).

15) A method as in claim 9, wherein the first and second flaps (3, 4) are united with a cold glue and pressed one against the other by pinning the area (7) of mutual contact forcibly against one of the bearing surfaces (22), utilizing a single presser tool (34) .

16) A method as in claim 1, wherein the ends (9) of the tubular wrapper (8) are sealed.

17) A method as in claim 1, wherein the ends (9) of the tubular wrapper (8) are sealed with cold glue.

18) A method as in claim 1, including the further step of forming twist closures (10) on the ends (9) of the tubular wrapper (8) .

19) A device for wrapping products, characterized in that it comprises

- a conveyor (12) affording a plurality of slots (13) ordered in succession and caused to advance along a predetermined feed path (14) in a predetermined feed direction (F2) , each proportioned to accommodate a product (1) partly enveloped in a leaf (2) of wrapping material with a first flap (3) and a second flap (4) projecting from the slot (13); a fixed restraint (23) installed close to the predetermined feed path (14) , serving to engage the flaps (3, 4) of each product (1) in succession and cause the first flap (3) to bend in a predetermined direction (Fl) , opposite to the feed direction (F2) , toward a free face (5) of the product and against the second flap (4) ; a folding station (39) located along the predetermined feed path (14) at a point downstream of the fixed restraint (23) , relative to the predetermined feed direction (F2) , at which the first flap (3) and the second flap (4) are bent together as one in the predetermined direction (Fl) and against the product (1) ;

- means by which to close the ends (9) of the tubular wrapper (8) .

20) A device as in claim 19, wherein the conveyor

(12) presents bearing surfaces (22) interposed between the slots (13) and disposed substantially parallel to the predetermined feed path (14) , in such a way that both of the flaps (3, 4) projecting from each product (1) can lie at least partly in contact with the bearing surfaces (22) before reaching the fixed restraint (23) .

21) A device as in claim 20, wherein each slot (13) is delimited by the pincer ends (17) of a respective main gripper (18) , and the bearing surfaces (22) are afforded by end portions of the grippers (18) .

22) A device as in claim 20, wherein each slot (13) is delimited by a respective pocket (19) and the bearing surfaces (22) are afforded by portions of the conveyor (12) interposed between the pockets (19) . 23) A device as in claim 19, wherein the conveyor (12) is embodied as a wrapping wheel rotatable in such a way that the predetermined feed path (14) describes an arc to a circle, and the fixed restraint (23) presents a curved surface (24) breasted with the wrapping wheel (12) .

24) A device as in claim 19, further comprising a sealing station (31) located along the predetermined feed path (14) between the fixed restraint (23) and the folding station (39) .

25) A device as in claim 21, further comprising a sealing station (31) located along the predetermined feed path (14) between the fixed restraint (23) and the folding station (39) , comprising a pair of presser tools (32, 33) capable of movement toward or away from one another in a direction transverse to the predetermined feed path (14) and engaging the two flaps (3, 4) on opposite sides of the area (7) of mutual contact .

26) A device as in claim 21, further comprising a sealing station (31) located along the predetermined feed path (14) between the fixed restraint (23) and the folding station (39) , comprising a presser tool (34) associated with the bearing surfaces (22) and positioned to force the area (7) of mutual contact against one of the bearing surfaces (22) . 27) A device as in claim 21, wherein the folding station (39) comprises an auxiliary gripper (40) serving to retain the product (1) when released by the main gripper (18) , and a folder (42) capable of movement transversely to the predetermined feed path (14) and insertable between the open pincer ends (17) of the main gripper (18) in such a way as to engage the area (7) of mutual contact between the first and second flaps (3, 4) .

28) A device as in claim 21, wherein the folding station (39) comprises a push rod (44) slidable internally of the pocket (19), serving to eject the product (1) from the selfsame pocket (19) , and a folder (45) located externally of the pocket (19) , positioned to engage the flaps (3, 4) at the area (7) of mutual contact .