The present invention relates to a method and machine for forming a sealed wrapping about an article, and to a package so formed.
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.
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.
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Number 1 in
With particular reference to
Machine 1 (in
With reference to
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
Wrapping wheel 14 rotates in steps about an axis 15 perpendicular to the
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 (
Machine 1 (
Sealing device 20 (
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
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
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
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
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
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
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 (
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.
Number | Date | Country | Kind |
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BO2008A 000254 | Apr 2008 | IT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP09/54760 | 4/21/2009 | WO | 00 | 1/10/2011 |