GB2214481A

GB2214481A - Package, method of packaging and packaging apparatus

Info

Publication number: GB2214481A
Application number: GB8819342A
Authority: GB
Inventors: Gerald Lightfoot
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-01-20
Filing date: 1988-08-15
Publication date: 1989-09-06
Also published as: GB8819342D0; GB8801245D0

Abstract

The package is formed from heat sealable longitudinally folded sheet material 38 and comprises a first folded edge portion 38 extending in a first direction and seams S1, S2 making an acute angle with the first direction and converging, travelling away from the edge portion 38. The package may be left open along the edge opposite the folded edge or closed by further seams S3, S4 parallel with the first edge portion 38 (Figs. 5 & 7). The package is made by a method using a heat sealing apparatus in which sheet material 28 is fed in a direction B to a heat sealing assembly having heat sealing bars 14 which can be pivoted towards and away from a support table 20. The bars are inclined at adjustable acute angles to either side of a line extending at right angles to the direction B and to the axis A about which the bars 14 are pivoted. One seam S1 may be sealed by the upstream bar 14 and the other seam S2 by the downstream bar. The package, apparatus and method are especially suitable for packaging generally triangular articles. <IMAGE>

Description

PACKAGE, METHOD OF PACKAGING AND PACKAGING APPARATUS This invention relates to a new packaging apparatus and a new method of packaging.

It is often necessary to wrap articles which are bulky and of generally triangular shape viewed in plan, for example bunches of drapes, cut flowers, sandwiches, and calabrese or broccoli. Apparatus commonly known as an L-bar sealer has been proposed for heat sealing packages, of heat sealable sheet material using an L-shaped sealing bar, one arm of which is parallel and the other at right angles to a feed direction of the sheet material.

However, the packages created using an L-bar sealer are of rectangular shape in plan and unsatisfactory for packaging articles which are of more triangular configuration.

One of the various objects of the present invention is to provide an improved package and, especially a package better adapted for packaging articles which are of generally triangular shape viewed in plan.

Another of the objects of the present invention is to provide an improved packaging apparatus and method for packaging articles.

According to one aspect the invention may be considered to provide a package formed from heat sealable sheet material comprising a first edge portion extending in a first direction and second and third edge portions each making an acute angle with said first direction and converging travelling along said second and third edge portions in a direction away from said first edge portion.

In a preferred package in accordance with the invention, the first edge portion is provided by a fold in a single sheet of heat sealable material and the second and third edge portions are formed by heat sealing superposed layers of heat sealable heat material. In one package in accordance with the invention the second and third edge portions intersect, the package so formed being of generally triangular configuration in plan. In another, preferred, package in accordance with the invention, a fourth edge portion is formed by heat sealing the superposed layers of sheet material generally parallel with the first edge portion, the fourth edge portion intersecting the second and third edge portions at a position remote from the first edge portion. In a most preferred package the fourth edge portion comprises two generally parallel but separately formed heat sealed seams.

In another aspect the invention may be considered to provide a method of packaging articles in a package comprising heat sealable sheet material and having a first edge portion extending in a first direction, the method comprising introducing the article between two layers of heat sealable sheet material and heat sealing the layers together along second and third portions at either side of the article by subjecting the layers to heat and pressure in a heat sealing assembly, said second and third portions each making an acute angle with said first direction and converging travelling along said second and third portions away from the first edge portion.

In one method the second and third portions intersect and are inclined to one another in a 'V' configuration. In another, preferred, method in accordance with the invention, the layers are also sealed together by subjecting the layers to heat and pressure at a fourth portion generally parallel with the first edge portion and intersecting the second and third portions at a position remote from the first edge portion. In carrying out a preferred method in accordance with the invention, the sheet material is moved intermittently past the heat sealing assembly in a feed direction (parallel with said first direction) and the sealing lines of the second and third portions are inclined at acute angles to a line extending at right angles to the feed direction.

In carrying out a method in accordance with the invention, use is preferably made of apparatus in accordance with the invention.

In carrying out a method in accordance with the invention one or two sheets of heat sealable sheet material may be used to form a package in accordance with the invention. Where only one sheet is used this may be folded at the mid point of the sheet width to provide the first edge portion, the sheet material being conveniently fed from a reel of ready folded material. Using this single folded sheet, the packages may be conveniently sealed if it is wished to have a completely closed package, as follows. The sheet material is fed from the supply to a position in which it is disposed in heat sealing apparatus, between support means and heat sealing bars thereof part, at least, of which is inclined at acute angles to either side of a line extending at right angles to the feed direction.An article to be wrapped is positioned between the two parts of the sheet with its broadest portion (viewed in plan) adjacent the first edge portion, upstream of the heat sealing apparatus but adjacent the most upstream of the heat sealing bars. The heat sealing bars are then operated to create a seal. An upstream one of the bars seals along one edge portion of the package e.g. the second portion and where appropriate part or all of a fourth portion, which is to be formed adjacent the article to be wrapped. The article to be wrapped and the sheet material is then drawn along the support means until the article is just beyond a downstream one of the heat sealing bars.The heat sealing assembly is again operated and in this case the downstream one of the heat sealing bars seals the sheet material adjacent the article along a third portion and where appropriate part or all of a fourth portion creating a complete package. Where the second and third portions intersect an apex of the package is at the opposite side of the sheet material to the apex between the two heat sealing bars. In carrying out these methods of packaging, the triangular shaped piece of material between each package is discarded.

Alternatively, using apparatus having two heat sealing bars positioned to form a 'V' where an open sided package is required, the article is placed between the two heat sealing bars with its narrowest point directed towards the apex of the heat sealing bars, and the heat sealing assembly is operated to form both sides of the package at once, leaving the side of the package open opposite the apex of the heat sealing bars.

In another method sheet material may be supplied from two reels, the material is fed through in face to face contact by the operator and, in this method, two open sided packages (for example for wrapping flowers) may be formed at the same time one being in the region between two sealing bars positioned to form a 'V' and the other being formed in two stages, a first stage being sealed by the upstream one of the sealing bars (with the smallest side of the article to be wrapped being at the opposite side of the sheet material to the apex of the sealing bars) and then the sheet material is moved to transport this article and its enwrapping sheet material downstream of the heat sealing assembly so that the other side of that package is sealed, in the next operation of the heat seal assembly by the downstream of the two heat sealing bars. Depending on the heat sealing bars provided and the type of package to the formed, various other ways of using the apparatus may be envisaged. Where using two separate sheet materials, if it is desired to form a closed package, a third heat sealing bar, conveniently extending parallel with the feed direction of the sheet material may be required to seal the material together at the first edge portion.

After material has been packaged using a method in accordance with the invention where the article to be wrapped is suitable the wrapped article may be passed through a shrinking oven of known configuration, to effect a heat shrinking operation on the sheet material to more firmly wrap the products. Of course this system may not be acceptable for certain articles which would be damaged by the heat.

In a further aspect the invention may be considered to provide packaging apparatus comprising a heat sealing assembly comprising two heat sealing bars mounted for pivotal movement about an axis between a lowered operative heat sealing position and a raised inoperative position, the heat sealing bars each having portions inclined at an acute angle to a line at right angles to the axis about which the bars are pivotted.

Preferably apparatus as set out in the last preceding paragraph further comprises means adapted to provide a supply of heat sealable sheet material in a feed direction parallel with said axis to the heat sealing assembly. Preferably the apparatus also comprises cooperating support means for the sheet material arranged to support the sheet material against pressure applied by the sealing bars during a sealing operation.

In another aspect the invention may be considered to provide package heat sealing apparatus comprising means for supplying heat sealable sheet material in a feed direction to a heat sealing assembly having two heat sealing bars mounted for movement towards and away from cooperating support means, the sealing bars being inclined at an angle of less than 1800 to one another and, in an operative position, the bars being inclined at acute angles to either side of a line extending at right angles to the feed direction.

Preferably, each of the heat sealing bars comprises, in addition, at an outer end a portion lying parallel with the feed direction. Suitably each of these end portions are oppositely directed, outwardly from the more widely spaced end portions of the bars; preferably the outer end portions are not aligned with one another.

Apparatus in accordance with the invention may, if desired, also comprise other sealing bars arranged parallel with the feed direction.

The sealing bar or bars parallel with the feed direction are of length appropriate to the purpose for which it or they are to be used, for example sealing the apex region of the package to ensure a tight seal may require only a short sealing bar, whilst sealing the edge of the package extending between the tips of the sealing bars will require a much longer parallel sealing bar.

Conveniently, a handle means is provided at the opposite end of the heat sealing bars from the pivot axis so that an operator can readily pivotally move the bars about the axis.

The bars may be, if desired, mounted on mounting means for movement to adjust the apex angle of the 'V' configuration in which the bars are disposed, conveniently in a pivotal movement; however this is not appropriate where the bars comprises outer end portions parallel with the feed direction. Where the bars are adjustable suitably means is provided for adjusting the angle between the bars while retaining them in the desired configuration with said perpendicular line bisecting the angle between the bars; the angle may be adjusted in accordance with the articles to be wrapped.

In a preferred apparatus embodying the invention, the bars are mounted on mounting means pivotally mounted for movement about an axis parallel with the feed direction so tha#t a line perpendicular to the axis about which the bars can be pivotally moved bisects the angle between the bars.

Preferably each of the bars is provided with means for heating a sealing surface of the bar to a suitable heat sealing temperature. Suitably, the means for heating the sealing surface may comprise a heated resistance wire secured on the face of the bar which contacts the sheet material in a sealing operation. Preferably a raised sealing surface is provided extending parallel with the wire. This may be a flat surface portion adapted to engage sheet material when the bar is moved to its operative position so that a double seal is provided by the sealing wire and the raised surface, improving the strength of the seal. Conveniently, in this case the sealing wire is arranged to also cut off the sheet material, thus separating the formed package from a supply of the material.Alternatively, the sealing surface may be provided by a second wire parallel to the first; in this case, the apparatus may be adapted so that in use the first and second wires are heated to different temperatures, one being effective to seal the package and the other to sever the material of the package from the remainder of the sheet material.

In a preferred apparatus in accordance with the invention, the support means cooperating with the bars is provided with a flat support surface, conveniently being provided with a non-stick coating.

Guide means may be provided to facilitate positioning to correctly locate seams. For example, if desired, downstream of a most downstream one of the two sealing bars, a depression may be provided within which an article to be wrapped may be located whilst the final seam of the package is being sealed by the downstream bar. In a preferred apparatus the depression is open at the side remote from the heat sealing assembly and the floor of the depression is provided by a belt conveyor.

Preferably the conveyor is arranged to be operative to transport a packaged article away from the heat sealing assembly when the sealing head is moved to its raised position and then to stop, so that a further article can be positioned in the depression for completion of packaging.

There now follows a detailed description to be read with reference to the accompanying drawings of two apparatuses and two packages embodying the invention, it will be realised that these apparatuses and packages have been selected for description to illustrate the invention by way of example.

In the accompanying drawings: Figure 1 is a diagrammatic front view of a first illustrative apparatus embodying the invention; Figure 2 is a diagrammatic plan view of the first apparatus embodying the invention; Figure 3 is a fragmentary view of a heat sealing bar of the first apparatus embodying the invention; Figure 4 is a plan view of a first package embodying the invention; Figure 5 is a plan view of part of a second apparatus embodying the invention; Figure 6 is a fragmentary view of a heat sealing bar of the second illustrative apparatus; Figure 7 is a plan view of a second package embodying the invention; and Figure 8 is a fragmentary front view showing part of the second illustrative apparatus.

A first package heat sealing apparatus embodying the invention is shown in Figure 1 of the drawings. This first illustrative apparatus comprises a frame 10 on which is mounted a heat sealing assembly 12. The heat sealing assembly comprises two heat sealing bars 14, mounted on a mounting block 16. The block 16 is mounted for pivotal movement on a rod 18 supported on the frame, about an axis A, towards and away from cooperating support means of the apparatus provided by a table 20 having a substantially flat surface. The table 20 is provided with a non-stick layer, for example of polytetrafluoro-ethylene.

The frame comprises a cradle portion 22 having mountings for a shaft 24. The shaft 24 extends through the centre of a supply reel 26 of heat sealable sheet material 28. The heat sealable sheet material is arranged to be drawn from the reel over a guide roller 30 and across the surface of the table 20, passing beneath the heat sealing bars 14 (shown in their raised position in dash line in Figure 1 and in full line in Figures 1 and 2 in their lowered, operative position). The sheet material is fed from the supply in a feed direction indicated by the arrow B, parallel to the pivotal axis A about which the sealing bars 14 may be pivoted.

As can be seen viewing Figure 2, the heat sealing bars 14 are disposed in a 'V' configuration and inclined at an acute angle to a line C (shown in chain dot line in the drawings) extending at right angles to the axis A, and to the feed direction B when the sealing bars 14 are in their operative position. This line C bisects the apex angle of the bars 14. The outer extremities of the bars 14 are connected by a handle 32 by which the heat sealing assembly may be pivoted about the axis A by an operator.

In the first illustrative apparatus the bars 14 are fixed to the mounting block 16 but, if desired, the bars 14 may be mounted for pivotal movement about parallel axes D, or a single axis, extending at right angles to the axis A.

Means (not shown) may be provided for clamping the bars in an adjusted position, to vary the apex angle of the bars depending on the material to be wrapped. Where the angle of the bars 14 is adjustable, means may also be provided for adjusting the length of the handle 32. In addition, adjustment means may be provided to move the two arms 14 equally so that the line C remains as a line bisecting the apex angle of the bars 14.

The two bars 14 are provided, on a surface portion intended to abut the sheet material 28, with a heat sealing wire 34, e.g. of about 5 mm diameter, of known construction. In addition (see Figure 3) bars may be provided with a raised surface portion 36 parallel with the sealing wires 34 and of height equal to the diameter of the sealing wires which will be heated sufficiently by conduction from the sealing wires 34 to effect a double seal of the sheet material.

The sheet material 28 is fed from the reel 26 in a doubled over layer being folded at the centre of the sheet to provide a first edge portion 38 (see Figure 2) which passes adjacent the rod 18 and the apex of the bars 14.

Conveniently, the mounting block 16 is provided with means (not shown) e.g. a light spring system by which the sealing arms are urged to the raised position when released by the operator so that they are clear of the surface of the table 20 whilst the operator is positioning the articles to be wrapped and feeding the sheet material 28 across the table.

In use of the apparatus, with the head assembly 12 in a raised position, articles 40 are introduced between the two layers of the folded sheet material 28 upstream of the most upstream of the two sealing bars 14. The articles are of generally triangular configuration viewed in plan and a narrowest point of the articles is conveniently directed away from the folded first edge portion 38. When an article 40 has been positioned upstream of the first of the sealing bars 14 the heat sealing assembly is pivoted about the axis A to move the sealing bars into an operative position where they engage the sheet material and press it against the table 20 to effect a heat sealing operation in known manner.First seam S1 is thus formed (see Figure 2); the sheet material is then moved in the direction of the arrow B by the operator, with the head assembly 12 in its raised position, past the assembly 12 to a second sealing position in which an article 40a is shown in Figure 2.

The illustrative apparatus is provided with a depression 42 by which the article 40a may be located and which assists in retaining it in a suitable position whist effecting a second seal S2 with the downstream one of the two sealing bars 14. The depression 42 may, if desired, be shaped to accommodate the article to be wrapped, for example the articles 40, 40a are heads of brocolli. A first finished package is shown in Figure 3, the first seam S1 to be formed being on the left, and the last seam S2, sealed by the downstream one of the bars on the right.It will be appreciated that once a first article 40 has been partially wrapped, a second article 40a may be introduced between the layers of sheet material 28 upstream of the heat sealing head, and the first seam S1 formed at the same time as the second seam S2 of the preceding package.

The first illustrative package formed by the first apparatus in carrying out a first illustrative method comprises the first edge portion 38 which extends in a first direction and second and third edge portions, namely seams S1, S2, each making an acute angle with the first direction and converging travelling along the seams in a direction away from the first edge portion 38.

The sheet material between the heat sealing bars in this first illustrative method of packaging using the first illustrative apparatus is waste. However, in other methods of using the first illustrative apparatus, articles may also be wrapped being included between the arms 14 so that both of the seams are sealed at once. In this method of use, the smallest width P of the article viewed in plan will be adjacent the folded side 38, and the side of the package opposite the apex of the arms 14 will be open. This may be convenient for wrapping flowers.

Other methods of operating the first illustrative apparatus may be devised, some of which are outlined previously. Where it is wished to form packages using two separate sheets of heat sealable sheet material, a second supply reel may be mounted above the first on an appropriate cradle (not shown) The heat sealable sheet material may be any suitable material, preferably a plastics film commonly used in heat sealing, for example a polyolefin film. If desired, the sheet material may be polyolefin shrink film and subsequent to the heat sealing operation the closed packages may be fed to a suitable heat shrinking oven where the film may be heat shrunk to more securely wrap the package.

When the heat sealing operation is effected using a plastics film, the heat sealing wire 34 is also effective to sever the plastics film thereby separating the package.

The second illustrative apparatus is generally similar to the first illustrative apparatus except as hereinafter described. The second illustrative apparatus comprises two heat sealing bars 14 which may be mounted on the mounting block of the second illustrative apparatus for pivotal movement about the axis A. The bars 14a are inclined at a acute angle to the line C (shown in dash line in Figure 5 of the drawings) which extends at right angles to the pivotal axis A and to the feed direction B when the heat sealing bars 14a are in their operative position in which they are shown in Figure 5 of the accompanying drawings.Bars 14a further comprise an integral outer end portion 50a, SOb, the outer end portion 50a, 50b being outwardly directed at the outer extremities of the parts of the bars 14a which are outerinclined atan acute angle to the line C. The parallel outer end portions 50a, 50b are not aligned with one another but are positioned so that the outer end portion 50a of the upstream one of the bars 14a is closer to the axis A then the outer end portion 50b of the downstream bar 14a.

The second illustrative apparatus also comprises a belt-type conveyor 52 shown in Figure 8 of the accompanying drawings and which is positioned to form the floor of the depression 42. As can be seen from Figure 8, in the second illustrative apparatus there is no wall or other obstruction at the downstream side of the depression 42 which would prevent the removal of a package by the conveyor 52 in the operation of the illustrative apparatus.

The second illustrative apparatus can be used in carrying out a second illustrative method generally similar to the first illustrative method described above, to produce a second illustrative package having a first edge portion 38 extending in a first direction and provided by folding a sheet of heat sealable plastics material along its longitudinal centre line, to produce two superposed layers of plastics material. In carrying out the second illustrative apparatus, the upstream of the heat sealing bars 14 is operative to form the seam S1 and a seam S3 parallel with the first edge portion 38.

After creating the seams S1, S3, the sheet material 28 and the partially wrapped article 40 are moved in the feed direction B to a position in which the article is just downstream of the downstream sealing bar 14a as indicated in Figure 5 by the article 40a. The seam S2 is then formed by the downstream one of the heat sealing bars 14a and a seam S4, parallel with the first edge portion 38 but positioned further from the first edge portion 38 then the seam S3, is formed by the outer end portion 50b of the downstream sealing bar 14a. Forming a double seal in this manner provides a much stronger and better sealed package.In the second illustrative apparatus the outer end portions soya, 50b of the sealing arms are preferably of different lengths, the downstream outer end portion SOb being longer than the upstream outer end portion 50 ; for example the upstream outer end portion 50a may be about 7.6 cm in length whilst the downstream outer end portion 50b may be about 12.7 cm in length. In the second illustrative apparatus the inclined portions of the sealing bars 14a are conveniently about 30 cm in length.

In the second illustrative apparatus the outer end portion 50a is provided with only one heat sealing wire heated to a temperature sufficient to seal together the superposed layers of plastic sheet material but not sufficient to sever the sheet material. The other sealing surfaces of the heat sealing bars comprise a first sealing wire 34 and a further raised surface of a similar height but, in the second illustrative apparatus provided by a second sealing wire 36a of the same diameter as the first wire 34.The wires 34, 36a are heated to different temperatures so that one of the wires merely effects a seal between the superposed layers of plastics material whilst the other wire not only seals the material but severs it to separate the package from adjacent parts of the sheet material 28; of course care must be taken that the appropriate one of the wires is heated to the higher temperature to ensure that the sheet material is severed at the right side of the article 40 to be packaged.

The head assembly may suitably operate at a speed of 400 to 500 packs per hour in the illustrative apparatuses.

If desired, the illustrative apparatuses may be automated, for example means being provided for drawing heat sealable sheetgmaterial automatically from the reel to the head assembly in steps of suitable length, and/or the head assembly may be arranged to be operated by power means e.g. a pneumatic cylinder to effect a seal when the sheet material is stationary. The articles to be wrapped may be inserted manually or automatically between the layers of sheet material.

The illustrative apparatus are better adapted for heat sealing packages of generally triangular products than the heretofore known L-bar sealer and are versatile in packaging goods of different dimensions with little adjustment necessary.

Claims

1. A package formed from heat sealable sheet material comprising a first edge portion extending in a first direction and second and third edge portions each making an acute angle with said first direction and converging travelling along said second and third edge portions in a direction away from said first edge portion.

2. A package according to claim 1 wherein said first edge portion is provided by a fold in a single sheet of heat sealable material.

3. A package according to claims 1 and 2 wherein said second and third edge portions are formed by heat sealing superposed layers of heat sealable sheet material.

4. A package according to claim 3 wherein said second and third edge portions intersect, the package so formed being of generally triangular configuration in plan.

5. A package according to claim 3 comprising a fourth edge portion formed by heat sealing the superposed layers of sheet material generally parallel with said first edge portion intersecting the second and third edge portions at a position remote from the first edge portion.

6. A package according to claim 5 wherein said fourth edge portion comprises two generally parallel separately formed heat sealed seams.

7. A method of packaging articles in heat sealable sheet material comprising introducing the article between two layers of heat sealable sheet material and heat sealing the layers together at either side of the article by subjecting the layers to heat and pressure in a heat sealing assembly, along sealing lines inclined to one another in a 'V' configuration, the sheet material being moved intermittently past the heat sealing assembly in a feed direction and the sealing lines being inclined at acute angles to a line extending at right angles to the feed direction.

8. A method according to claim 7 wherein the sealing lines of the second and third portions are inclined at acute angles to a line extending at right angles to the feed direction.

9. A method according to either one of claims 7 and 8 wherein the sheet material comprises a single sheet folded along a centre line to provide the first edge portion.

10. A method according to either one of claims 7 and 8 wherein the sheet material comprises two separate superposed sheets and the first edge portion is formed by sealing the sheets together adjacent one edge of the sheets.

11. A method according to any one of claims 7 to 10 wherein a seam along the second portion is first formed by an upstream sealing bar, the partially wrapped article is moved to an appropriate position and the seam along the third portion is formed by the downstream one of the sealing bars.

12. A method according to any one of claim 7 to 11 wherein the upstream sealing bar also forms a seam parallel with the first edge portion and intersecting the seams of the second and third portions.

13. A method according to claim 12 wherein a further seam parallel with the first edge portion is formed by the downstream one of the sealing bars.

14. A method according to claim 13 wherein the seam parallel with the first edge portion formed by the downstream sealing bar is disposed further from the first edge portion than the seam formed by the upstream one of the sealing bars.

15. A package heat sealing apparatus comprising means from which heat sealable sheet material may be supplied in a feed direction tt a heat sealing assembly having two heat sealing bars mounted for movement towards and away from cooperating support means, the sealing bars being inclined at an angle of less than 1800 to one another and, in an operative position, the bars being inclined at acute angles to either side of a line extending at right angles to the feed direction.

16. Apparatus according to any one of claims 15 to 18 wherein the heat sealing bars are mounted on mounting means pivotally mounted for movement about an axis parallel with the feed direction.

17. Apparatus according to either one of claims 15 and 16 wherein each of the heat sealing bars comprises an outer end portion lying parallel with the feed direction.

18. Apparatus according to claim 17 wherein the outer end portions are not aligned with one another.

19. Apparatus according to claim 18 wherein the outer end portion of the downsteam sealing bar is longer than the outer end portion of the upstream sealing bar.

20. Apparatus according to either one of claim 15 and 16 wherein the position of the bars on the mounting means may be adjusted to adjust the angle at which they are inclined at either side of said line extending at right angles to the feed direction.

21. Apparatus according to any one of claims 15 to 20 comprising means for heating a sealing surface of each heat sealing bar.

22. Apparatus according to claim 21 wherein the means for heating the sealing surface comprises a heated resistance wire secured on the face of the bar adapted to contact a sheet material to be sealed in a sealing operation.

23. Apparatus according to claim 22 comprising a further sealing surface extending parallel with said wire.

24. Apparatus according to claim 23 wherein the further sealing surface comprises a flat surface portion.

25. Apparatus according to claim 23 wherein the further sealing surface is provided by a second wire parallel with the first.

26. Apparatus according to claim 25 adapted to operate so that the first and second wires are heated to different temperature in the operation of the apparatus.

27. Apparatus according to any one of claims 15 to 26 comprising support means cooperating with the support bars in the operation of the apparatus to provide the seal.

28. Apparatus according to claim 17 wherein the support means is provided with a flat support surface on which the article can be supported.

29. Apparatus according claim 28 wherein the support surface has a non-stick coating.

30. Apparatus according to any one of claims 15 to 29 comprising guide means to facilitate positioning to correctly locate seams.

31. Apparatus according to any one of claims 15 to 30 comprising conveyor means positioned downstream of the downstream heat sealing bar adapted to remove packages which have been sealed.

32. Apparatus for heat sealing packages constructed arranged and adapted to operate substantially as hereinbefore described with reference to figures 1 to 4 of the accompanying drawings.

33. Apparatus suitable for use in forming packages from sheet material by heat sealing constructed arranged and adapted to operate substantially as hereinbefore described with reference to figures 5 to 8 of the accompanying drawings.

34. A method of forming a package from heat sealable sheet material substantially as hereinbefore described.

35. A package substantially as hereinbefore described with reference to figure 4.

36. A package substantially as hereinbefore described with reference to figure 7.