Method And Machine For Forming A Sealed Wrapping About An Article, And Package So Formed

Abstract

A method of forming a sealed wrapping about an article, whereby a sheet of wrapping material is folded and sealed about the article to form a substantially tubular partial wrapping having two open ends, and a sealing flap projecting outwards crosswise to the partial wrapping; the sealing flap is folded onto a major lateral portion of the partial wrapping; and the open ends of the partial wrapping are then gripped and sealed.

Description

TECHNICAL FIELD

The present invention relates to a method and machine for forming a sealed wrapping about an article, and to a package so formed.

BACKGROUND ART

On packing machines, a sealed wrapping is formed about an article using a wrapping unit, which is fed with a succession of articles for wrapping, and with a continuous strip of normally airtight, heat-seal wrapping material.

The sealed wrappings about the respective articles are normally formed by sealing the free longitudinal edges of the strip to define a tubular wrapping about the articles; transversely sealing the tubular wrapping at the ends of each article to form a respective “pillow pack”; and then separating the individual sealed wrappings.

Though widely used for its simplicity, the above method has serious drawbacks, by being normally inaccurate in terms of both handling of the articles during the wrapping process, and the look of the finished sealed wrappings. That is, it is difficult to achieve a sealed wrapping that adheres firmly about the article; which problem is further compounded when working with delicate, fragile articles.

Various methods have recently been proposed comprising a number of folding steps and seals, but have proved unsuccessful, on account of certain steps involving folding and/or heating a large number of superimposed layers of the wrapping material; in which case, folding and/or heat transmission to stabilize and seal the wrapping prove/s unsatisfactory.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a method, machine, and package designed to eliminate at least some of the drawbacks of the known art, and which at the same time are cheap and easy to implement.

According to the present invention, there are provided a machine, a method, and a package as claimed in the accompanying independent Claims, and preferably in any one of the Claims depending directly or indirectly on the independent Claims.

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 side view, with parts removed for clarity, of a machine in accordance with the present invention;

FIGS. 2 to 7 show successive steps in a method of forming a wrapping about an article in accordance with the present invention;

FIG. 8 shows a schematic top plan view of parts of the FIG. 1 machine in two different operating positions (indicated by a dash line and a continuous line);

FIG. 9 shows a schematic front view of parts of the FIG. 1 machine in two different operating positions (indicated by a dash line and a continuous line);

FIG. 10 shows a schematic front view of parts of the FIG. 1 machine;

FIG. 11 shows a schematic side view of parts of the FIG. 1 machine;

FIGS. 12 to 15 show schematically, with parts removed for clarity, a number of steps in forming the wrapping at part of the FIG. 1 machine;

FIG. 16 shows the FIG. 13 step from a different perspective;

FIG. 17 shows a larger-scale portion of FIG. 1.

PREFERRED EMBODIMENTS OF THE INVENTION

Number 1 in FIG. 1 indicates as a whole a machine for forming a sealed wrapping 2 about a substantially parallelepiped-shaped article 3.

With particular reference to FIG. 2, article 3 comprises two opposite end walls 4 (only one shown in FIG. 2); two opposite major lateral walls 5 (only one shown in FIG. 2) crosswise (in particular, perpendicular) to end walls 4; and two opposite minor lateral walls 6 crosswise (in particular, perpendicular) to end walls 4 and major lateral walls 5.

Machine 1 (in FIG. 1) forms wrapping 2 from a sheet 7 of wrapping material in the steps shown in FIGS. 2 to 7, and as article 3 is fed along a path P. Sheet 7 is substantially rectangular and preferably made of airtight, heat-seal material.

With reference to FIG. 7, the wrapping 2 formed about article 3 substantially adheres to article 3, and comprises two major lateral portions 8; two minor lateral portions 9 crosswise to major lateral portions 8; and two end portions 10 crosswise to major lateral portions 8 and minor lateral portions 9. Wrapping 2 is sealed hermetically about article 3 along three sides by means of respective seals: one at a major lateral portion 8, and the other two at respective end portions 10. Wrapping 2 and article 3 together define a package that may either undergo further processing or be retailed as it is.

In the embodiment shown, major lateral portions 8 have a larger surface area than minor lateral portions 9. In variations not shown, major lateral portions 8 have substantially the same surface area as minor lateral portions 9.

As shown in FIG. 1, machine 1 comprises a conveyor 11 for feeding article 3 to a folding device 12 comprising a push unit 13 and a wrapping wheel 14.

Wrapping wheel 14 rotates in steps about an axis 15 perpendicular to the FIG. 1 plane, and comprises a number of pockets 16 equally spaced about axis 15, and each for receiving a respective article 3 at a loading station 17, and conveying article 3 along a semicircular portion of path P to an unloading station 17′.

Push unit 13 feeds article 3 in a direction A crosswise (in particular, perpendicular) to axis 15, so article 3 engages sheet 7 and is inserted together with sheet 7 inside respective pocket 16. As article 3 is inserted inside pocket 16, sheet 7 is folded into a U, so that two pairs of flaps 18, at opposite ends of article 3, and a pair of flaps 19, 19′ of sheet 7 project from the free sides of article 3. The flaps 18, 19 and 19′ in each pair face each other and are substantially parallel (FIG. 2). Flaps 18 project, parallel to axis 15, from respective end walls 4 of article 3; flaps 19 and 19′ project, crosswise to axis 15, from a minor lateral wall 6; and flap 19 is wider than flap 19′.

Machine 1 (FIGS. 1 and 17) also comprises a sealing device 20 for superimposing and sealing flaps 19 and 19′ to form a substantially tubular partial wrapping 21 having two open ends 22, and a sealing flap 23 projecting outwards crosswise to partial wrapping 21 (FIG. 3). Partial wrapping 21 comprises major and minor lateral portions 8 and 9, which are connected to one another by respective lateral edges 24; and sealing flap 23 projects outwards from, and extends along, a respective lateral edge 24.

Sealing device 20 (FIGS. 1 and 17) comprises a substantially fixed member 25 at loading station 17; and a member 26 which is movable, in a direction crosswise to direction A, between an open position (shown by the continuous line in FIG. 17) and a closed position (shown by the dash line in FIG. 17). At least one of members 25, 26 is a heat-seal member (i.e. for transferring heat to sheet 7 to seal flaps 19 and 19′). Advantageously, both members 25, 26 are heat-seal members. In actual use, when inserting article 3 inside pocket 16, member 26 is in the open position; and once article 3 is inside pocket 16, member 26 is moved towards member 25 to fold flap 19 onto flap 19′, so flaps 19 and 19′ are gripped between members 25 and 26.

Sealing device 20 also comprises a heat-seal member 27, downstream from loading station 17 and upstream from unloading station 17′, for preferably fluidtight sealing flaps 19 and 19′ to each other to form sealing flap 23. In actual use, member 27 oscillates about a respective axis (not shown) substantially parallel to axis 15, to contact flaps 19 and 19′ when wheel 14 is stationary.

In a variation not shown, machine 1 comprises a number of members 27 arranged successively between loading station 17 and unloading station 17′.

In an embodiment not shown, machine 1 has no member 27, and flaps 19 and 19′ are sealed to each other by members 25 and 26 at loading station 17.

In other variations, neither of members 25, 26 is a heat-seal member, and flaps 19, 19′ are sealed to each other by member/s 27.

Machine 1 also comprises a folding device 28 for folding sealing flap 23 onto a major lateral portion 8. Folding device 28 comprises a known fixed plate (not shown) located along the periphery of wheel 14 to fold sealing flap 23 crosswise (in particular, perpendicularly) to respective major lateral portion 8; and a pusher 29 to feed article 3 in a substantially radial direction with respect to axis 15, so sealing flap 23 is folded onto respective major lateral portion 8 by contrast with a fixed folding member 30. Pusher 29 is located at unloading station 17; and folding device 28 also comprises a heating head 31 located at a stabilizing station 32 along path P, and which is movable crosswise to path P to engage and stabilize sealing flap 23 on major lateral portion 8.

Machine 1 also comprises a conveyor 33 for feeding article 3 in direction A along a substantially straight portion of path P from stabilizing station 32; through a closing station 34 where open ends 22 of partial wrapping 21 are closed to form sealing flaps 35; to a folding station 36 where sealing flaps 35 are folded.

Conveyor 33 comprises a belt (shown partly in FIG. 1) having a work branch 37 and looped about two known pulleys (not shown) rotating about respective axes parallel to axis 15. Articles 3 are positioned on conveyor 33 with open ends 22, sealing flap 23, and minor lateral portions 9 crosswise to direction A.

On each side of conveyor 33 at closing station 34, a retractor 38 deforms a respective open end 22 of partial wrapping 21 to form two facing flaps, and a sealing device 39 grips and preferably fluidtight seals the facing flaps to form respective closed end portion 10 and relative sealing flap 35, which projects from and defines a seal of end portion 10.

Retractor 38 comprises two arms 40 movable between a closed rest position (shown by the dash line in FIG. 8), and an open taut position (shown by the continuous line in FIG. 8).

Sealing device 39 comprises a gripper unit in turn comprising two heat-seal jaws 41 movable between an open rest position (shown by the dash line in FIG. 8), and a closed sealing position (shown by the continuous line in FIG. 8).

In actual use, when arms 40 are moved into the open taut position inside respective open end 22, jaws 41 are moved up. And just before jaws 41 reach the closed sealing position, arms 40 are returned to the closed rest position, so a complete seal is formed along the whole of sealing flap 35.

With particular reference to FIGS. 10 and 11, machine 1 also comprises a folding device 42 at folding station 36, to fold sealing flaps 35 onto respective end portions 10. Folding device 42 comprises a conveyor 43 for feeding article 3 along a substantially straight portion of path P; and two substantially fixed plates 44 (only one shown) located on opposite sides of path P to fold sealing flaps 35 onto respective end portions 10 (as shown particularly in FIGS. 12, 13 and 16).

More specifically, conveyor 43 comprises an elevator 45 for moving article 3 crosswise to major lateral portions 8 in a direction, in particular a substantially vertical direction, crosswise to direction A.

In the embodiment shown, sealing flaps 35 are of such a length that, once folded, each extends up to a respective edge 24′ connecting respective end portion 10 to a major lateral portion 8 (as shown particularly in FIGS. 6 and 7). In variations not shown, sealing flaps 35 are shorter and fall short of respective edges 24′.

Once folded onto respective end portion 10, each of sealing flaps 35 comprises two tabs 46 projecting from opposite sides of respective end portion 10.

Folding device 42 also comprises four flip-over rails 47, each designed so that each tab, as it slides along respective rail 47, is folded roughly 180° onto respective end portion 10 (as shown particularly in the FIGS. 13 to 15 sequence).

More specifically, each rail 47 comprises a first portion 48 for folding respective tab 46 roughly 90° into a position substantially perpendicular to respective end portion 10 (FIG. 14); and a second portion 49, after portion 48, for folding tab 46 onto end portion 10 (FIG. 15).

Machine 1 also comprises a conveyor 50, downstream from folding device 42, to feed article 3, crosswise to minor lateral walls 6, along a substantially straight, horizontal portion of path P from folding station 36 to an output station 51. Two known heating plates (not shown) are located on opposite sides of the conveyor to stabilize sealing flaps 35 and tabs 46 on respective end portions 10.

Operation of machine 1 will now be described as of when article 3 is located inside respective pocket 16, and sheet 7 is folded into a U about article 3. At this point, member 25 folds flap 19 onto flap 19′, and wheel 14 moves a first step forward to bring article 3 up to heat-seal member 27, which moves into contact with sealing flap 23. During this movement, said plate (not shown) folds sealing flap 23 by contrast into a position perpendicular to respective major lateral portion 8.

When article 3 reaches unloading station 17′, pusher 29 expels article 3 from pocket 16 onto conveyor 33. As article 3 is fed onto conveyor 33, sealing flap 23 is folded onto major lateral portion 8 by folding member 30, and is stabilized in that position by heating head 31.

At this point, retractors 38 deform open ends 22; sealing devices 39 form end portions 10 and sealing flaps 35; and conveyor 33 feeds article 3 to folding device 42.

When article 3 reaches folding station 36, elevator 45 moves article 3 upwards, so each sealing flap 35 is intercepted by respective plate 44 and folded onto respective end portion 10. As article 3 is raised, tabs 46 slide along, and are folded roughly 180° by, respective rails 47.

At this point, conveyor 50 feeds article 3 between two known heating plates (not shown) to stabilize sealing flaps 35 and tabs 46 on respective end portions 10 and so obtain package 2.

The advantages of the present invention with respect to the state of the art will be clear from the above description.

In this connection, it is important to note, for example, that the location of sealing flap 23 on major lateral portion 8 provides for particularly good sealing of open ends 22. If sealing flap 23 were to be located on one of minor lateral portions 9, deformation by retractor 38 and sealing by sealing device 39 would be more problematic, on account of the greater thickness of the wrapping material involved, and there would be more risk of sealing flap 23 becoming detached from respective minor lateral portion 9 (especially when deforming open ends 22).

Also, rails 47 for folding tabs 46 roughly 180° are particularly advantageous in terms of faster production and compactness.

Claims

1. A method of forming a sealed wrapping (2) about an article (3), the method comprising the steps of:

folding a sheet (7) of wrapping material about the article (3), so the folded sheet (7) has a pair of facing, substantially parallel, projecting flaps (19, 19′);

superimposing and sealing the pair of flaps (19, 19′) to form a substantially tubular partial wrapping (21) having two open ends (22), and a first sealing flap (23) projecting outwards crosswise to the partial wrapping (21);

folding the first sealing flap (23) onto an outer surface of the partial wrapping (21);

successively gripping and sealing the open ends (22) of the partial wrapping (21);

deforming at least one of the open ends (22) of the partial wrapping (21) by means of a retractor (38), to form two facing flaps; and gripping and sealing the facing flaps to form a respective closed end portion (10) and a second sealing flap (35), which projects from the end portion (10) and defines a seal of the end portion (10);

folding the second sealing flap (35) onto the end portion (10) so that two tabs (46) of the second sealing flap (35) project laterally from the end portion (10) and on opposite sides of the end portion (10); and

folding each tab (46) onto the end portion (10).

2. A method as claimed in claim 1, wherein the sheet (7) of wrapping material is folded and sealed about the article (3) so that the partial wrapping (21) comprises two major lateral portions (8) on opposite sides of the article (3); and two minor lateral portions (9) which are located on opposite sides of the article (3), are crosswise to the major lateral portions (8), and are connected to the major lateral portions (8) by respective lateral edges (24); the first sealing flap (23) extending substantially along a respective lateral edge (24), and being folded onto one of the major lateral portions (8) of the partial wrapping (21); and the open ends (22) of the partial wrapping (21) being closed and sealed by gripping them to form two second sealing flaps (35) substantially crosswise to the first sealing flap (23) and to the minor lateral portions (9).

3. A method as claimed in claim 2, wherein the first sealing flap (23) is first folded to project substantially perpendicularly to the relative said major lateral portion (8), is maintained in that position, and is subsequently folded onto the relative major lateral portion (8).

4. A method as claimed in claim 2, wherein the article (3) comprises two substantially opposite end walls (4); two substantially opposite major lateral walls (5) crosswise to the end walls (4); and two minor lateral walls (6) crosswise to the end walls (4) and to the major lateral walls (5);

the sheet (7) being folded and sealed so each major lateral portion (8) of the partial wrapping (21) is located at a respective major lateral wall (5), and each minor lateral portion (9) of the partial wrapping is located at a respective minor lateral wall (6).

5. (canceled)

6. (canceled)

7. A method as claimed in claim 1, wherein the tabs (46) are folded onto the end portion as the sheet (7), folded about the article (3), is fed in a direction substantially parallel to said end portion (10) and to said tabs (46), and in particular crosswise to the major lateral portions (8).

8. A method as claimed in claim 1, wherein the tabs (46) are substantially folded roughly 180° onto the end portion (10), by each sliding along a respective rail (47) of a folding device (42).

9. A package comprising an article (3), and a sealed wrapping (2) folded about the article (3); the wrapping (2) comprising two major lateral portions (8), two minor lateral portions (9) crosswise to the major lateral portions (8), and two end portions (10) crosswise to the major and minor lateral portions (8, 9); the wrapping (2) being characterized by comprising a first seal at one of the major 5 lateral portions (8), and second seals which are crosswise to the first seal and each located at a respective end portion (10);

the first seal comprising a first sealing flap (23) folded onto the respective major lateral portion (8); and each second seal comprises a second sealing flap (35) folded onto the respective end portion (10).

10. (canceled)

11. A package as claimed in claim 9, wherein each second sealing flap (35) comprises two tabs (46) folded onto the respective end portion (10).

12. A package as claimed in claim 9, wherein the wrapping (2) is obtained using a method that includes:

folding a sheet (7) of wrapping material about the article (3), so the folded sheet (7) has a pair of facing, substantially parallel, projecting flaps (19, 19′);

superimposing and sealing the pair of flaps (19, 19′) to form a substantially tubular partial wrapping (21) having two open ends (22), and a first sealing flap (23) projecting outwards crosswise to the partial wrapping (21);

folding the first sealing flap (23) onto an outer surface of the partial wrapping (21);

successively gripping and sealing the open ends (22) of the partial wrapping (21);

deforming at least one of the open ends (22) of the partial wrapping (21) by means of a retractor (38), to form two facing flaps; and gripping and sealing the facing flaps to form a respective closed end portion (10) and a second sealing flap (35), which projects from the end portion (10) and defines a seal of the end portion (10);

folding the second sealing flap (35) onto the end portion (10) so that two tabs (46) of the second sealing flap (35) project laterally from the end portion (10) and on opposite sides of the end portion (10); and

folding each tab (46) onto the end portion (10).

13. A machine for forming a sealed wrapping (2) about an article (3), the machine (1) comprising:

a first folding device (12) for folding a sheet (7) of wrapping material into a U about the article (3), so the folded sheet (7) has a pair of facing, substantially parallel, projecting flaps (18, 19, 19′) on each free side of the article (3);

a first sealing device (20) for superimposing and sealing the flaps (19, 19′) in one pair to form a substantially tubular partial wrapping (21) having two open ends (22), and a first sealing flap (23) projecting outwards crosswise to the partial wrapping (21); a second folding device (28) for folding the first sealing flap (23) onto an outer surface of the sheet (7);

a second sealing device (39) for sealing the open ends (22) of the partial wrapping (21);

at least one retractor (38) for deforming at least one of the open ends (22) of the partial wrapping (21) to define two facing flaps; the second sealing device (39) gripping and sealing said facing flaps to form a respective closed end portion (10) and a second sealing flap (35), which projects from the end portion (10) and defines a seal of the end portion (10); and

a third folding device (42) for folding the second sealing flap (35) onto the relative end portion (10) so that two tabs (46) of the second sealing flap (35) project laterally on opposite sides of the end portion (10); the third folding device (42) also folding each tab (46) onto the end portion (10).

14. A machine as claimed in claim 13, wherein the first folding device (12) and the first sealing device (20) fold and seal the sheet (7) about the article (3) so the partial wrapping (21) comprises two major lateral portions (8) on opposite sides of the article (3); and two minor lateral portions (9) which are located on opposite sides of the article (3), are crosswise to the major lateral portions (8), and are connected to the major lateral portions (8) by respective lateral edges (24); the first sealing flap (23) extending along a respective lateral edge (24); the second folding device (28) folding the first sealing flap onto one of the major lateral portions (8) of the partial wrapping (21); and the second sealing device (39) comprising at least 10 one gripping unit for closing and sealing the open ends (22) of the partial wrapping (21) to form two second sealing flaps (35) crosswise to the first sealing flap (23) and to the minor lateral portions (9).

15. A machine as claimed in claim 14, wherein the gripping unit comprises two heat-seal jaws (41).

16. A machine as claimed in claim 13, wherein the first folding device (12) comprises at least one pocket (16); and a push unit (13) for feeding the article (3), crosswise to the sheet (7), into the pocket (16), so the sheet (7) is pushed into the pocket (16) by the article (3) and folded into a U about the article (3).

17. (canceled)

18. (canceled)

19. A machine as claimed in claim 16, further comprising a conveyor (43) for feeding the article (3), in a direction crosswise to the second sealing flap (35) projecting from the end portion (10), along a portion of a feed path (P), which portion is located downstream from the second sealing device (39) and at the third folding device (42); the third folding device (42) comprising at least one substantially fixed member (44) which intercepts the second sealing flap (35) to fold the second sealing flap (35) onto the end portion (10).

20. A machine as claimed in claim 13, wherein the third folding device (42) comprises at least two rails (47) designed so that each tab (46), as it slides along the relative rail (47), is folded roughly 180° onto the relative end portion (10).

21. A method as claimed in claim 1, wherein a rail (47) comprises a first portion (48) which folds a respective tab (46) approximately 90° into a position substantially perpendicular to respective end portion (10); and a second portion (49), after portion (48), for folding tab (46) onto end portion (10).

22. A method as claimed in claim 1, wherein a folding device (42) is provided for folding the tabs and comprises four flip-over rails (47), each designed so that each tab, as it slides along respective rail (47), is folded roughly 180° onto respective end portion (10).