US3577865A - Wrapping machine method - Google Patents

Abstract

Method of enclosing an article is a heat-shrinkable foil wrapper by subjecting portions of the wrapping material progressively to heat, beginning with that portion of the material most remote from the closure area, and subjecting the closure area to heat just prior to closure to cause the removal of air.

Description

United States Patent I I 2] I Inventors Gottfried M. Hain Lehen Post Ramerberg an der Inn; Wolfgang B. Leonard, Graben Post Ramerberg an der Inn, Germany Appl. No. 638,213 Filed May 15, 1967 Patented May 11, 1971 Assignee Alpma Alpenland- Maschinenbaugesellschaft l-Iain & Co. KG. Rott Inn Rosenheimer Strasse, Germany Priority May 18, 1966 Germany AS2524 WRAPPING MACHINE METHOD 2 Claims, 1 Drawing Fig.

[1.8. CI 53/25, 53/24, 53/33, 53/39 Int. Cl B65b 55/14, B65b 51/12, B65b 63/08 Field of Search 53/24, 25,

References Cited UNITED STATES PATENTS 7/1928 McDonald l I 957 Sell 9/1959 Dreyfus.... 8/1965 Liedtke 9/1968 Howe.... I/1969 Stagna... 6/ I969 Teznka 6/ 1969 Teznka FOREIGN PATENTS 3/l960 Great Britain Primary ExaminerWayne A. Morse, Jr. Attorney-Christen & Sabol 53/25 53/30X 53/33 53/33 53/39 53/25X 53/25X 53/124 ABSTRACT: Method of enclosing an article is a heatshrinkable foil wrapper by subjecting portions of the wrapping materiaI progressively to heat, beginning with that portion of the material most remote from the closure area, and subjecting the closure area to heat just prior to closure to cause the removal of air.

INVENTORS GOTTFRIED M. HAIN WOLFGANG B LEONARD WRAPPING MACHINE METHOD This invention relates to a method of and apparatus for sealing wrappers around articles, for example, around portions of edible products, particularly, but not exclusively, by shrinking.

In the past articles wrapped in shrinkable foils have been sealed at a closure flap thereof and only then has the foil been shrunk, e.g. by passing the wrapped article through a hot air tunnel. Any air enclosed between the article and the foil cannot of course, escape if a tight seal of the wrapping is achieved, and even in the case of a leaky or inefficient seal only part of the entrapped air will be able to emerge. The shrunken foil itself prevents the unhindered emergence of the air at many points, principally in the case where the article is an angular body such as a triangular or wedge-shaped piece of cheese. Accordingly, with the prior wrapping, air pockets and even blisters occur.

' For many goods, such as slices of cheese and other perishable foodstuffs, hermetic and air-free packaging is of the utmost importance. An object of the invention is to achieve this by means of a simple method and complementary apparatus which can easily be carried into practice.

With this object in view, the present invention provides a method of sealing a foil wrapper around an article characterized in that prior to final closure or sealing of a closure flap or closure flaps of the wrapper, the article is subjected to heat treatment successively at its peripheral areas, commencing at that surface which is most remote from the closure flap or flaps, heating of the sealing face, which is that surface of the article on which the closure flap or closure flaps are sealed for shrinking and/or sealing being effected only at the conclusion thereof.

After the remote surface has been treated, one advantageous work cycle provides, in the case of a square or like article, for the front face and then the two other lateral faces to be treated, before it becomes the turn of the sealing face.

A preferred apparatus for carrying the method into effect comprises sliding channel whose walls that embrace the articles that are to be treated are formed at the treatment points from heating plates. Advantageously these heating plates are adapted to be pressed against the surfaces of the article. So as to prevent the articles from twisting or turning over during the treatment, the sliding channel preferably has a cross course and thrust pistons to convey the articles at the corners of the channel.

It has furthermore proved advantageous to press the heating plates onto the respective surfaces of the article under elastic, i.e. yielding pressure, for which pressure springs or compressed air are well suited. So as to annul the application of pressure during the shifting of the articles, the plates are advantageously cyclically controlled.

In the method of the invention, air is first expelled from the regions remote from the seal and then from the regions nearer to the seal. Moreover, since the heat treatment takes place at all surfaces under the application of pressure, any residual atmosphere is prevented. The foil attaches itself so tightly to the treated surface that it is impossible for the air to return. 011 the other hand, the still open wrapping seal facilitates the emergence of the air. The apparatus itself is simple and works reliably. It can be synchronized with the working cycle of a wrapping machine, and therefore, no loss of output need take place as a result of employment of the method.

The invention can be used to advantage not only in relation to shrinkable foils, but can be employed in conjunction with wrapping foils which bear a preservative, such as sorbic acid as a protective agent against mould, and which have to fit especially closely to the article with no air between.

A further advantage of the heat treatment on all sides in accordance with the invention, in relation to cheese is that cheese secretes a certain amount of grease through the action of the heat, and this results in a surface that reduces the formation'of mould.

A preferred practical embodiment of the apparatus of the invention is depicted diagrammatically in the accompanying drawing, in which the single FIG. is a plan view.

The apparatus comprises, basically, a sliding channel 1, which is advantageously defined by metal sidewalls. An article 10, such as a cubic mass of cheese or the like, is fed via guide plate 5 from a wrapping machine (not shown) ready wrapped and ready for sealing, but with a flap 15 not yet folded over onto the article, and passes through an intake port 2 into an antechannel 3 and then onto a thrust piston 4. Facing the intake port 2 is a heating plate 11 which is pressed by means of springs 12 against sealing countersurface 13 of the article 10 (that is to say that surface of the article which is most remote from the flap l5), heats the wrapping foil at this-surface and thereby shrinks it. Since the wrapper is not yet sealed, but a closure flap 15 of the foil still stands out, any entrapped air can escape during the contraction process. After this the article is shifted through the antechennel 3 by the piston 4, whereby the closure flap 15 is folded against the sealing face 17 of the article 10 by a folder designed on the channel wall without, however, sealing the closure.

At the end of the antechannel 3 there are heating plates 20 which are opposed to front surfaces 18 of the portion and the heat of which now acts on these from surfaces, shrinks the corresponding sections of the foil wrapper and, if necessary, seals the superimposed folding edges. For this purpose the heating plates 20 are pressed against the front surfaces by means of pneumatically operated plungers 21. A further thrust piston 22 then conveys the article into a cross channel 23, which provides heating plates 27 for the other two opposed lateral faces 25, 26. These heating plates 27 can likewise be pressed against the respective surfaces of the article by pneumatic plungers 28. After passing through this cross channel the article passes into a discharge channel 30 having a thrust piston 31. In this discharge channel 30 there is a heating plate 32 which, after all the surfaces of the article have successively been under the effect of heat, now shrinks the sealing side and finally seals the wrapper. So as 'to produce a pressure against the heating plate 32, more especially for the tight sealing of the closure flap 15, opposite channel wall 33 is designed to be flexible and movable in the direction of the heating plate 32 by means of a pneumatically operated plunger 34, so as to press previous articles 10' present in the discharge channel 30 against the heating plate. This heating plate 32 is somewhat longer than the others, so that the articles remain under its influence for a prolonged period, i.e. during two or three feed phases. At the end'of the discharge channel 30 there can be a cooling plate 36 which cools the heated surfaces fairly rapidly. The possibility also arises of arranging cooling plates in tunnel form for all the lateral faces of the article. From the discharge channel 30 the articles pass into a collecting channel (not illustrated), from which they can be removed in any desired manner.

The channel walls can be closed plates or, if desired, simply parallel rods 38. At the turning points these rods then lead to closed wall plates 39, so as to make possible an unhindered change in the feed direction.

Whilst it is sufficient to support the heating plate 11 flexibly by means of the springs 12, the other heating plates 20 and 27 and, if desired, also the pressure wall 33 of the heating plate 32 are periodically controlled, so as to cancel the pressure during the feed movements.

The discharge piston 31 can advantageously be uncoupled from its drive and operated as desired by hand, so that any articles which are present in the discharge channel 30 at the end of each application can be pushed out by hand, without actuating the remaining mechanisms.

It is particularly advantageous to fasten the sliding channel with all its parts and mechanisms to a mounting base 40, which in its turn can be releasably fastened by means of screws 41 to a wrapping machine which is provided with a suitable countermounting (not illustrated) and from which the sliding channel is fed directly. This releasable attachment makes it possible to exchange the channels according to the size and shape of the articles being wrapped.

In the drawing-the mounting base 40 is indicated by broken lines and for reasons of clarity the connecting elements and mounting supports for the components of the sliding channel have also been omitted.

The invention is not restricted to a rectangular sliding channel for quadrangular or cubical portions. Cylindrical, spherical or other polygonal or prismatic portions can be wrapped conveniently using the method of the invention, the heating plates corresponding to the curved surface having to be correspondingly curved for cylindrical articles, whilst in the case of a spherical article all of the plates must be correspondingly shaped. In this case it may be possible to reduce the number of heating plates. lf sector shaped or wedge-shaped articles are to be sealed, then only some of the heating plates, such as the plates and 27 need to be altered.

lclaim:

l. A method of sealing a foil wrapper around an article, such as a portion of edible foodstuff, having flat lateral faces,

wherein the foil is subjected to heat treatment for the purpose of contraction and/or obtaining a tight fit against the surfaces of the article as well as for sealing a closure flap or flaps of the foil, characterized in that prior to the sealing of the closure of the wrapper the article is subjected to heat treatment successively at its lateral faces, commencing at that surface which is most remote from the closure flap or flaps, heating of the sealing face, which is that surface of the article on which the closure flap or flaps are sealed, for shrinking and/or sealing being effected only at the conclusion thereof.

2. A method as claimed in claim 1, characterized in that, prior to folding of the closure flap or flaps the article which is generally quadrangular is subjected to heat treatment at the remote surface of the article then at its two front faces, then at its other two lateral faces and only subsequently at the sealing face.

Claims (2)

1. A method of sealing a foil wrapper around an article, such as a portion of edible foodstuff, having flat lateral faces, wherein the foil is subjected to heat treatment for the purpose of contraction and/or obtaining a tight fit against the surfaces of the article as well as for sealing a closure flap or flaps of the foil, characterized in that prior to the sealing of the closure of the wrapper the article is subjected to heat treatment successively at its lateral faces, commencing at that surface which is most remote from the closure flap or flaps, heating of the sealing face, which is that surface of the article on which the closure flap or flaps are sealed, for shrinking and/or sealing being effected only at the conclusion thereof.

2. A method as claimed in claim 1, characterized in that, prior to folding of the closure flap or flaps the article which is generally quadrangular is subjected to heat treatment at the remote surface of the article then at its two front faces, then at its other two lateral faces and only subsequently at the sealing face.

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