WO1987007240A1

WO1987007240A1 - A method, a binder and a binding machine for closing hose or bag shaped packings, primarily tubular foodstuff packings

Info

Publication number: WO1987007240A1
Application number: PCT/DK1987/000064
Authority: WO
Inventors: Flemming Kroman; Erik Madsen
Original assignee: Emc-Tamaco A/S
Priority date: 1986-05-29
Filing date: 1987-05-27
Publication date: 1987-12-03
Also published as: EP0271536B1; FI880358A; PT84974A; CZ388687A3; JP2567009B2; CN1010850B; DE3750773D1; JPS63503376A; US4878702A; IE871376L; ATE114284T1; AU6846990A; ZA873869B; USRE36544E; FI84898B; CZ278122B6; IL82691A0; IE67068B1; KR880701200A; SK388687A3

Abstract

The closing of tubular casings containing foodstuffs by mounting a binder on a constriction of the casing involves the traditional problem of a high waste percentage due to the binders either damaging the casing material or sliding off the constriction. A method and a binder are disclosed which makes it possible to obtain a very strong clamping of the binder without damaging the casing material, and in connection with tight plastic casings it is even possible to hereby provide a ''super tight'' closure, viz. by arranging the constriction with an oblong cross section between opposed straight clamping beams, which are forced together so as to produce a controlled deformation flowing of the material.

Description

A method, a binder and a binding machine for

1 closing hose or bag shaped packings, primari ly tu ular foodstuff σackings.

The present invention relates to a method of closing hose or bag shaped packings, primari ly foodstuff packings, whereby a constricted portion of the packing is clamped by a ring shaped non-metallic 5 clamp binder, which is caused to be narrowed about the constriction by a closing pressure applied from opposite sides thereof and is fixed in its shape as attained when it is subjected to a c losing pressure.

10 .Typical packings wi ll be sausage articles, which have a porous sausage skin of a fibrous material, and bag or sausage shaped packings for other kinds of foodstuffs, e.g. soups, the packing material here being a tight, tubular plastic sheet material. The

15 sausage skin materials are porous because the products should be subjected to a smoking treatment, whereby they are given both a desired taste and a long durabi lity, whi le the plastic sheet material should be as tight as possible for rendering the packed products

20 as durable as possible.

In both cases almost the same problem exists, viz. that the binding of the constrictions should be effected very tightly such that in case of sausages the clamp binders wi ll not slide on the normally very slippery 25 sausage skins before and during the smoking, while the clamps when mounted on the plastic sheet envelopes should

A likewise be non-slidable, but also provide for an effective sealing against penetration of air. In both cases it is normally necessary to make use of clamping

30 forces which are so high that a potential danger of the sheet material being damaged wi ll exist, and in fact it is well known that in the relevant productions a most significant waste on this account is being experienced. For these types of bindings it has been customary, almost exclusively, to use binders of the metallic clip type, i .e. U- or C-shaped metal strips, which are introduced over a constriction area of the packing and bent by reasonably high clamping forces so as to be closed as a ring about the constriction. Much could be said about the advantages and disadvantages of these metal clips, but here it should just be mentioned that they are responsible for the said high waste, because they have a limited abi lity to hold the material tightly clamped, and that they show a major disadvantage in just being of metal. Generally, according to modern standards, any kind of metal is unwanted in connection with foodstuff articles. It is relevant to mention also that it has been found that the metal clips are simply unable to close the plastic sheet pac ings with any particularly high degree of tightness, at least not without an associated highly potential danger of damaging the material so that the closure will be untight anyhow. Through the recent years several extremely tight plastic sheet materials have been developed for increasing the storage durabi lity of the various foodstuff products, but it has been realized that these developments are in fact superfluous as long as the materials cannot be closed with the same high degree of tightness. Already for leaving the use of metal there have ^" been some attempts to make use of plastic binders, but the designs of these binders have not been suitable for use with large size packings, i .e. packings with relatively thick constriction areas. An advantage of the plastic binders, apart from their not being of metal, is that they may be provided with locking means such that they may be tightened about the constriction area and be fixed in a closed ring shape, whereby they

? may clamp the constriction area with high forces £ without these forces being limited by the ability

5 of the binder material to retain a bent shape against return-bending forces from the clamped const ri ction area .

The already known plastic binders, however, suffer from various drawbacks- whi ch should not be discussed

10 in great detail in the present context. Generally they are based on the same basic ideas as the metal clips, viz. that they should serve to surround the constriction area with sufficient tightness to be non-slidingly secured and to provide a high degree

15 of sealing of the constriction area. Most of the known plastic binders are unusable for large size packings because they comprise a U-shaped portion, the tegs of which are received in a hole in an opposed counter portion, whereby the constriction material w ll

20 be clamped against the edges of the receiver hole, and this may give rise to concentrated clamping forces which cause a rupturing of the sheet material.

There are not either, so far, any reports on plastic binders being applicable to effect any "super

25 sealing" of the relevant constriction areas.

In connection with the invention a major problem has been found in the fact that it is in no way ideal to effect a binding of a constriction, area by way of a circularly annular binder or a binder having major

30 portions shaped in this manner. Experiments and p calculations have shown that what happens is a peripheral compaction which forms a barrier against the clamping pressure being transferred to the inner portions of the constriction area. When a high

35 pressure is applied the relatively thin layer of the compacted peripheral material will be axially displaced by . lowing, but since the material is frictionally cohering with the inner material the latter will be axiatly drawn by such displacement and deformation of the outer materiεl; this drawing is effected based on the resiliency of the non- flowing material, and it may well happen that by an applied high clamping pressure the inner material next to the material in the zone of flowing material will hereby be stretched beyond its socalled rupture prolongation, i.e. the material will burst.

The above considerations apply to casing materials of plastic, but similar considerations may apply to casings of fibrous material, and in both cases the result will be that in fact none of the known binders are optimal with respect to creating a high clamping pressure in a safe manner, i.e. without damaging the casing material.

The said considerable waste should be seen on the background that apparently it has not earlier been realized what is really happening in the constriction area when a high clamping pressure is applied from binder portions of various configurations, and it is believed that the present invention represents a pioneer work in this respect. For the normal use of metal clips it is typical that some empiric tests are made at the beginning of a production, such that the waste can be held as low as possible and that an attempt to reduce the waste further by lowering the clamping pressure will only result in a similar or even worse waste, now not by rupturing the material but by the binders not being safely held on the casings. It is a traditional counter measure to mount two or more clips at each constriction, but the waste percentage will still be high, and as far as an extremely sealed closing is concerned such a series of clips will be of no help at all, as none of the clips wi ll have any chance of providing for a "super sealing".

As wi ll be apparent from the foregoing the main purpose of the invention is to provide a method and a binder which wi ll enable the constrictions to be bound by a relatively high binding pressure with a very low risk of the constriction material being damaged, such that the said waste can be reduced considerably or even be eliminated. Based on the same contri ution it is a further purpose of the invention to provide a method and a binder which wi ll be applicable for obta ning a "super sealed" closing of the constrictions, this of course also being of utmost importance. According to the new concept of the invention it has been found that for a practically ideal relation between a high clamping pressure and a low risk of damaging the casing material the constriction area should be clamped between opposed surface portions of substantially straight clamping beams of the binder clamp and be caused to be compacted into a final shape, in which it is cross sectionally oblong in the longitudinal direction of the substantially parallel clamping beams, preferably with a length at least twice the distance between the clamping beams. Obviously the applied clamping pressure and the size of the binder should sti ll be adapted to the particular production, but already with a conventional adaptation in this respect, i.e. by empirical selection of the conditions, the result will be a drastic reduction of the waste percentage, because with the said disposition of the constriction area between substantially parallel clamping beams a relatively very high clamping pressure can be applied without damaging the casing material. The invention is based on advanced studies of the behaviour of the casing material in the constriction area when exposed to a clamping pressure, and it has even been found that it is possible to select a correct binder and clamping pressure based on the known basic or starting parameters of the process, i.e. the dimensions and material constants of the casing material, thus without relying solely on empirical tests. It is believed, however, that in the present connection it will be unnecessary to elucidate the theoretical basis of the invention when the result thereof can be expressed in terms of concise and novel method and design conditions.

Briefly, the physical effect of applying the clamping pressure between straight and parallel clamping beams will be that the clamping pressure is transferred to the inner material portions n the constriction area without being hindered by any compaction taking place lengthwise of the clamping beams as would occur along curved clamping means, and the clamping pressure, therefore, will be taken up by the constriction area in a relatively very "soft" manner involving no drastic differences in the behaviour of the different neighboring layers of the material in the constriction area. Correspondingly, the physical effect of the constriction area being elongated in the said direction is that the degree of compaction of the constriction area will be relatively small, whereby it is ensured that the different material portions as frictionally engaging each other by the compression thereof will not give rise to substantial rubbing effects, such that the casing material is unlikely to be ruptured hereby. The required clamping together of two opposed clamping beams to a desired final position is achievable with the use of clamping beams, which are essentially rigid or stiff, and which are interconnected endwise through tensi le strong leg portions, of which at least one is adapted to be received in a receiver opening in the opposite clamping beam in a Length variable and fixable manner. In any production there wi ll be some variations in the general thickness of the constriction areas, and consequently the said leg portion wi ll intrude more or less in the receiver opening or even protrude more or less from the rear side of the said opposite clamping beam. Correspondingly, in order to limit the number of different standard binders it may be desirable, for a given production, to select a inder type which will give rise to such rearwardly protruding leg ends, and generally this wi ll be disadvantageous in that projecting binder portions wi ll present a tearing risk towards neighboring packings. In the prior art, as far as plastic binders are concerned, the same problem has existed, though to a much higher extent because of the larger displacement of the leg portion during the clamping operation, and it has been suggested in that connection that the problem of the widely rearwardly projecting leg ends may be solved by simply cutting away these protruding portions immediately at the rear side of the binder portion from which they project. This, however, has turned out to be an unacceptable solution of the problem, because in connection with the production of foodstuff products it is highly unacceptable to have loose cut off binder portions occuring together with the products themselves.

With the present invention it is ensured that a given binder type having a specific length of the said leg portion is usable in connection with an increased number of different products and their associated variations of the general thickness of the constriction areas, because with the said oblong configuration of the clamped constriction area the intrusion or protrusion of the leg portion into or beyond the receiver opening will vary relatively Little due to the associated small clamping displacement of the leg portion. It is practically possible, therefore, to entirely avoid the said cutting of the leg portions by prescribing either the use of such a thickness of the receiver clamping beam that the end of the leg por on wi ll remain inside the said receiver opening despite the occuring thickness variations of the constriction areas or - where the leg members wi ll protrude moderately from the rear sides of the receiving clamping beams - that the outer ends of the leg portions be smoothly rounded so that- these end portions wi ll not present any tearing risks. Hereby each standard binder type wi ll be applicable for the binding of both a variety of different products and for the binding of standard products showing a low tolerance with respect to the general thickness of the constriction areas, without the end portions of the leg members having to be cut away. While these results of the invention are highly important it may be still more important that the invention provides for a practical possibility of a "super sealed" closure to be obtained in a well defined and reproduceab le manner. It has been found that the main condition of a super tight closure s in fact rather simple to formulate and to realize based on the principles of the invention, while at the same time it has been made clear why such a closure is otherwise practically unachievable: In order to provide a full sealing all material portions across the constriction area should be pressed firmly together as well as firmly against the surrounding clamp. Inside the constriction area and on the surface thereof, due to wrinckles and foldings of the casing sheet, there wi ll exist a plurality of unclosed narrow channels, which wi ll not be closed merely by a pressure sufficient to force the sheet surface sub areas tightly together. In order to close these channels it is simply necessary to subject the material at each relevant place to such a high pressure that the plastic material is deformed, by a real deformation flowing, and because the wrinckles may occur all over the constricted area the condition of really producing a totally sealed closure wi ll be that each and all sub portions of the constricted area are subjected to such a high deformation pressure without any portion thereof hereby being fractured.

The building up of such a high and non-damaging pressure even inside the central portion of the area is generally possible with the use of the method according to the invention, whi le with the use of the conventional metal clips there are several sub areas in which the pressure wi ll be either too high or too low, or in other words it is impossible to avoid the situation that the pressure is suitable in some sub areas without being either too low or too high in other sub areas, whereby the result is bound to be unsuccessfu I .

Some of the already known plastic bi nders. cou Id be better suited for providing a less varying pressure in the constriction area, but here one problem is that the sheet material, as already mentioned, is forced against the edge of a hole so as to readi ly burst at this place by an applied high pressure, and another problem is that in the prior art it has generally been endavoured to produce a finally bound constriction area of approximately uniform thickness and width. It has now been found, both theoretically and experimentally, that a deformation pressure midways in the constriction area cannot in practice be built up without the remain¬ ing material being damaged, unless the thickness, i.e. the distance between the opposed clamping beams, is noticeably smaller than the width of the area. Likewise it is important that the binding is effected between substantially straight, opposed clamp portions.

In practice, in a given production, it should of course be ascertained that the clamping pressure is adjusted so as to be effective for the desired result to be obtained, i.e. high enough to cause an overall flowing deformation of the material, but without having caused damage to any part of the material. These functions cannot be directly observed, but test samples may be produced for being tested and inspected. The fulfilling of the said conditions for obtaining a "super sealed" closure according to the invention can be verified by removing the clamp and broadening out the tubular casing material of the constriction and then 1) inspecting the material for observable fractures and 2) measuring the sheet thick¬ ness all the way round to make sure that at every sub area the sheet material has undergone the said deformation flowing, this being inherently connected with an axial displacement of the material and therewith with a permanent thickness reduction thereof. Thus, when the material is unbroken and is of reduced thickness all the way over the former constriction area, then the applied pressure has been correct and applied correctly for providing the super sealing effect, and the production may start or continue with the same mounting conditions for mounting the binders of the particular selected type. With the -use of plastic binders it is inevitable that the binder after the fixation thereof and after the removal of the applied pressing tools wi ll expand somewhat under the influence of the resilient expansion forces in the compressed material in the constriction area. Normally this wi ll be acceptable, because it has been found that the high degree of sealing as having been achieved by the applied high clamping pressure w ll remain unchanging high even by a considerable pressure relief thereafter.

The fixation of the binder, i.e. the locking of the connector legs to the clamping beams, should be effected such that no significant return movement will occur after the relief of the clamping tool pressure. According to the above, however, a certain small amount of return movement may be acceptable anyway, which may largely faci litate the designing of well suited binders. For achieving a perfect sealing of or in the constriction area it wi ll normally be necessary to compress the material by some 10-50% all according to the cross sectional shape of the area and the E-module of the particular plastic sheet material, i.e. a quite considerable axial displacement of the material should be effected for making sure that all kinds of axial leaks have been sealed off. Particularly with the use of sheet materials of a tow E-module it may be disadvantageous for the integrity of the material to use a strongly binding ring member of small "height", i .e. of a smalt axial dimension, because the outermost material in the constriction area may then burst by the forceful clamping together of the correspondingly thin clamping beams of the binder. Ideally for this purpose a rather high or long binder should be used, which wi ll distribute the pressure over an enlarged outer area of the constriction and thus be more lenient to the sheet material. This material should sti ll be clamped sufficiently for an overall expansion in the axial direction, but with the use of a relatively long binder the axial expansion will be s oothened out and be partly suppressed in that the expansion forces wilt be taken up by counterresi I ient forces from the material portions frictionally -held by the binder adjacent the axial end portions thereof.

However, such Long binders will be correspondingly expensive, and for the invention it is an important recognition that a corresponding - resu It wilt be obtainable with the use of "short" binders, viz. by a suitable design of the tools used for the clamping actuation of the binders. Thus, this desired effect will be achievable by externally holding the material of the constriction area ust outside the binding area in such a manner that the held material cannot be freely axially displaced, this being effectable by means of special clamping tool portions, which, in conjunction with the clamping together of the binder, will clamp against the constricted material area just outside the opposed ends of the binder. Hereby there is provided a frictional resistance against the axial expansion of the material, what will correspond to an increase of the E-module in the actual binding area, such that high clamping forces may be applied to a "short" binder without the material being damaged. When the clamping pressure is relieved and the said clamping tool portions are removed the binding pressure may cause a certain post-expansion, but as already mentioned it will be unimportant whether an associated pressure reduction inside the bound area will occur, when it has only previously been ensured that a real compaction and axial displacement of all sub portions of the material in the binding area has been obtained.

It is important that the binder opening is beforehand disposed approximately in accordance with the cross sectional shape of the constriction area, such that the casing material by its compaction between the clamping beams shall not have to be widely laterally deformed in order to engage the cross leg connect ions between the clamping beams. The invention, which is more closely defined in the appended claims, wi ll now be described in more detai l with reference to the drawing, in hich:-

Fig. 1 is a perspective exploded view of a binder according to the invention, Figs. 2-4 are schematic views i llustrating the use of the binder.

Figs. 5 and 6 are a perspective and a sectional view, respectively, of a modified binder,

Figs. 7 and 8 are corresponding views of two other embodiments of the binder,

Fig. 9 is a perspective view of sti ll a further binder embodiment, shown preparatory to being -used.

Figs. 10-13 are plan views i llustrating the progress of a "super sealing" binding, Figs. 14-17 are corresponding longitudinally sectional views,

Fig. 18 is a schematic plan view of another modified binder,

Fig. 19 is a side view, partly in section, illustrating a binding operation with additional tools being used,

Fig. 20 is a corresponding perspective view,

Fig. 21 is a perspective view i llustrating the application of a binder onto a constricted packing portion, and

Fig. 22 is a corresponding top view, partly in section.

The binder shown in Figs. 1-4 consists of a U-shaped member 2 having a clamp beam 4 and two legs 6, and a relatively thick, loose clamp block beam 8 with two through-going holes 10 for the legs 6. The ends of the smooth legs 6 are provided with longitudinal slots 12 having slightly undulated side walls, and on each leg end is provided a wedge body 14, forwardly protruding .and held by an easily breakable connection 16 to the leg end such that the connection 16 is broken when the wedge body 14 is pushed into the slot 12, whereby the leg end portion will be laterally expanded. Also the lateral walls of the wedge body 14 are undulated.

The wedge bodies 14 are located such that they may be introduced into the holes 10, see Fig. 2, when the two binder parts 2 and 8 are brought together about a constriction 18 on a tubular packing having an outer sheet casing. By a further pressing together of the parts as i llustrated by pressure arrows in Fig. 3 the clamp beams 4 and 8 are caused to effect a desired, predetermined closing pressure on the constriction 18, which is hereby compressed to a certain thickness within a given tolerance range. For the particular production a clamp 2,8 has been selected, which is adapted to the total cross sectional area of the casing sheet such that in the final position the constriction 18 will fill out - entirely or just almost - the full space between the legs 6 when the binding area of the binder has adopted a shape which is oblong in the longitudinal direction of the parallel beams 4 and 8. Preferably the width between the legs 6 should be at least twice the distance between the beams 4 and 8.

When the binder assumes its final position between non-i llustrated clamping tools the wedge bodies 14 are pressed or beaten into the slots 12, see Fig. 4, whereby the end portions of the legs 6 wi ll expand inside the holes 10 and thus be locked against retraction therefrom. For improving this locking the holes 10 may diverge slightly rearwardly or be provided with a slightly narrowed entrance end.

If the product to be bound is of the sausage type. i.e. having a porous casing it wi ll be sufficient if the space between the legs 6 is just almost fi lled out by the constriction 18, whi le if a super tight closure of a plastic casing is wanted this space should be entirely fi lled out, as explained below in more detai l. However, in both cases the said oblong shape of the constriction area between the beams 4 and 8 wi ll condition a relatively high clamping pressure to be used without the casing material bursting, so in both cases an exeptionally firm holding of the clamp on the constriction is achievable.

Moreover it can be ensured in both cases that the free ends of the legs may be located entirely within the holes 10, such that they wi ll not form rearwardly protruding tearing members. This wi ll be a question of adapting the thickness of the block beam 8 to the expected or known tolerance of the total cross sectional area of the casing as forming the consecutive constrictions 18. In practice, of course, only a limited number of block beams 8 with different thickness wi ll be avai lable for a correspondingly limited number of different distances between the holes 10, but even so it has been found that relatively few different standard binder sizes wi ll be sufficient for the practical demand. It may happen that the leg ends wi ll protrude somewhat from the rear side of the block beam, irrespective of the manner in which the legs are fi ed to the block beam 8, and this may be acceptable if the free ends of the legs are shaped smoothely rounded to still not form regular tearing members and sti ll not require to be cut off.

The problem as to freely projecting leg ends might of course be overcome by using very thick block beams 8 as a standard, but any unnecessary oversize will imply empty costs, and this is important because binders for the discussed purposes are used in millions or rather billions.

As mentioned the opposed clamp beams 4 and 8 should ideally be straight and remain straight, though 5 a slightly arched shape could be acceptable. The constriction 18 will seek to expand and thus to bend the beams outwardly. The block beam 8, due to its enlarged thickness, wi ll not easily bend, but the beam 4 would have to be equally heavily designed if

10 it should resist any trace of bending out once the clamping tool pressure has been relieved. To avoid such overdimensi oning of this beam 4 the tool clamping pressure may be increased to somewhat above the desired final pressure, such that just this pressure

15 is established when the binder leaves the tools and the beam 4 is bent out slightly by the internal pressure of the constriction 18. Alternatively the clamping pressure could be applied between the block beam 8 and the local foremost end areas of the legs

20 6, i.e. on the outer ends of the beam portion 4, and this beam portion could extend slightly inwardly curved so as to be straightened out when the clamping pressure is applied to the foremost leg end areas only. Also, the clamping tool cooperating with the beam 4 may be

25 slightly curved to produce the same result.

In Figs. 5 and 6 is shown a binder, in which a metal pin 20 is preposi tioned in the respective end portions of the block beam 8 without from the beginning projecting into the respective holes 10. It

3.0 will be appreciated that the legs 6 are here lockable in their final positions by the pins 20 being forced towards each other so as to penetrate the leg end portions an intrude into the interior wall material of the holes 10, as shown in the left hand side of

35 Fig. 6. As shown in dotted lines in the right hand side thereof the free end of the legs may be smoothly rounded as suggested above, such that they need not be cut away even if they finally project somewhat beyond the rear side of the block beam 8.

In the binder shown in Fig. 7 the legs 6 are shaped with transverse middle slots 22, which may cooperate with a wedge member 24 associated with the respective end portions of the block beam 8, provided in a recess therein and operable to be pushed inwardly into the slot 22 for locking the leg ends by expansion thereof.

In Fig. 8 is shown a binder in which the beam portions 4 and 8 are permanently interconnected at one end through a leg portion 7, which constitutes or includes a hinge portion, whereby the two beams are closable from the opened position shown in full lines to the closed position shown in dotted lines. Hereby a free leg portion 26 on the beam 4 is int roduceab le into an apertured leg portion 28 on the free end of the beam 8, the aperture being designated 30. The leg portion 26 is provided with barb like protrusions 32 and the aperture 30 has corresponding, inverted barb portions 34, which wi ll effectively hold the leg portion 26 against retraction from the hole 30 once it has been introduced therein. In this case, as could be the case with the legs 6 of the foregoing Figures, the leg is not fixable exactly in the position in which it is left by the final clamping pressure on the beams 4 and 8, but as mentioned hereinbefore a small degree of retraction wi ll normally be acceptable. The beams 4 and 8 could be straight as in the other examples, but F g. 8 i llustrates that some slight curving of the beams may be acceptable, as it would even in the other Figures. When the length of the leg 7 is not adjustable the beams 4 and 8, in their final positions, may not be fully parallel, but again, a small deviation from the ideal circumstances will generally be allowable without the major advantages being sacrificed.

In Fig. 9 is shown a plastic binder comprising a U-shaped member 36 having a bottom beam 38 with forwardly protruding legs 40 and a loose cross beam 42 shaped with holes 44 for receiving the legs 40. It is indicated that the U-member 36 is inserted laterally over a constricted area 46 of a tubular packing 48, which may contain a rigid, semi rigid or liquid foodstuff. The outsides of the legs 40 are provided with small barbs 50 adapted to cooperate with corresponding holding ribs 52 on the outer side walls of each of the holes 44.

The binding of the constriction area 46 is effected by a simple forcing together of the beam portions 38 and 42 with the legs 40 received in the holes 44. The objective here is to effect a "super sealed" binding of the constriction area 46 of a very tight packing material designated 53 of plastic. It is not presupposed that this material is particularly orderly disposed in the constricted area by a controlled pleading or otherwise, but only that the material has been gathered together and is now located inside the opening of the U-member 36, whereafter this member is brought together with the cross beam 42.

In this initial phase, in w ich the ends of the legs 40 may only just reach the front ends of the holes 44 when the sheet material of the constriction 46 starts to resist the moving together of the beams 38 and 42, the sheet material 52 will thus still be only loosely packed together, and it will not even fill out the binder opening, see Fig. 10.

In a following second phase, see Fig. 11, the beams 38 and 42 are forced together until a full compaction has been established, i.e. unti l practically all axial passageways through the binder area have been closed, principally corresponding to the area of the binder opening now being almost equal to the total cross sectional area of the tubular material 52. The material 52 wi ll be subjected to the highest pressure in the areas thereof which are located directly adjacent the middle areas of the opposed clamping beams, while the pressure wi ll decrease towards zero adjacent the corner areas as long as the deformabte sheet material may sti ll seek outwardly towards these areas; just because the material is deformable it i ll hereby, in the areas of the said higher pressure, be somewhat axially expanded before an initial bui lding up of the pressure adjacent the corner areas, and when this happens the total cross sectional area of the sheet material will already be somewhat reduced compared with the same area in a free condition of the sheet materi a I .

The sheet material wi ll be pressed laterally outwardly against the middle portions of the legs 40 already before the material is pressed out into the corners of the binding opening, and at these places, therefore, a pair of opposed compression areas wi ll occur, which, via the internal friction in the material of the compacted constriction area, wi ll act as pressure bridges between the respective opposed end portions of the clamping beams 38 and 42. Hereby the applied clamping force on the clamping beams wi ll not be immediately transferred to the central area of the binding area, and also for this reason the provision of an initial pressure build up in each and every portion of the binding cross_, section wi ll require an already established, relatively considerable clamping force on the clamping beams, whereby a certain axial expansion will be applied to the sheet material located immediately next to the middle portions of the clamping beams 38,42 and the connector legs 40, respecti ely.

It is corresponding circumstances which, as mentioned, will make it impossible to obtain a sufficiently high closing pressure in a constriction area which is narrowed generally along a circular peripheral length or partial length, because an associated building up of a peripheral pressure bridge may simply prevent any considerable pressure build-up in the central area as long as the applied pressure is not so high as to damage the surface material.

The same will apply to the binder shown if the effective length of the legs 40 is larger than the effective length of the beams 38,42 or even larger than just the half of the latter Length. In that case the pressure bridges along the legs will be so pronounced that by a further clamping together of the beams it is impossible to build up an initial pressure in the central area of the constriction before the material in the said pressure bridges has been compressed to such a degree as to be damaged, whereafter a complete sealing is unachievable.

This is why it is important that the binding cross section be pronounced flat between the clamping beams. In order to provide for a complete sealing the beams 38,42 are forced further together, Fig. 12, whereby the constriction material will be positively deformed and axially expanded in each and every sub portion of the cross section. The degree of axial expansion wi ll not be the same all over the area, but this is immaterial if it has only been achieved that in all sub portions some expansion has taken place.

When the clamping tools are removed from the binder, Fig. 13, the beams may bulge out somewhat, but an associated pressure reduction in the deformed constriction area is well acceptable once the overall deformation has been obtained. Due to the barb portions 50,52 the U-member 36 is self locking in the position in which it was left by the removal of the clamping tools, but if the barbs are coarse a certain return displacement may take place, but again, this may be acceptable, particularly if the E-module of the material is low. For higher E-modules it will be preferable to use a binder of a stepless self-locking^' type, e.g. as shown in Figs. 1-7.

The pressure distribution in the middle area of the constriction is shown graphically in Figs. 14-17, in which partly common pressure levels designated a-d are shown. Level a_, which is practically zero, represents the pressure in the gathered together, but still non- compacted constrict ion_ (Figs. 9 and 10).

Level b, Fig. 15, represents the slightly increased pressure in the middle of the area when the clamp beams have advanced to the complete compaction of the material as discussed in connection with Fig. 11. It wilt be noted that the pressure next to the clamp beams is somewhat above level b.

Level c indicates the maximum pressure in the central area upon the pressure deformation of the materi a I, Fig. 12.

Level d, Fig. 17, indicates the final pressure upon the external clamping pressure being relieved, see Fig. 13. The vertical lines indicating the pressure conditions in the material may as well represent the degree of axial expansion of the material.

Fig. 10-13 show the situation that the legs 40 are brought to project considerably from the rear side of the clamp beam 42 and are cut off as illustrated by the dotted lines shown in Fig. 13. It should be emphasized, however, that it is both possible and highly preferential to make use of binders, which, as already discussed in connection with Figs. 1-6. are preadapted to the production so as to make leg cutting unnecessary. Fig. 18 shows still a further self-locking binder, the legs of which are smooth, while in the receiver holes sharp internal edges 56 are provided as barbs that wilt but into the leg sides and thus prevent the legs from retraction from the holes. It is essential that the binder legs do not draw the casing material into the receiver holes, i.e. the material should be kept away from the hole ends until the teg ends have been initially introduced into the holes, and the tegs and the holes should be disposed such that the inner sides of the legs engage the corresponding hole edges tightly, such that the casing material cannot, during the building up of the pressure, intrude into the slots between the tegs and the hole edges. Ideally the beams should be very long, such that in its final shape the constriction area is almost extremely elongated, but of course this would require the clamp beams to be very heavy for securing the required stiffness thereof. In practice the area wilt not need to be more flat than corresponding to a substantially rectangular area with a side proportion of 1:8, normally even just to some 1:4, while a final proportion of 1:2 will mostly be too large for the achievment of an effective compaction and deformation of the entire cross sectional area.

Based on the knowledge of the cross sectional area and the type of the casing to be bound it is thus possible to preselect a suitable binder size, viz. such that the final constriction area, when deformation compressed e.g. some 20-40% or as required, should be held in a rectangular opening having a side proportion normally somewhere between 1:2.5 and 1:6. Hereby the binder width (length of the clamp beams) can be at least provisionally determined. Hereafter the length of the legs 6 and 40 should be chosen such that the casing material in its loose condition (Figs. 2, 9, 10) can be held within the U-member 2,36 so as to allow the leg ends to be initially introduced into the holes 10,44 before a pressure build-up starts in the casing material. The remaining parameter will be the thickness of the block beam 8,42, which should ideally be selected such that the final clamping stage can be reached without the free leg ends projecting substantially from the rear side of the beam. Thus the thickness of these beams can easily be selected by a practical test.

In practice it is of course important to control the clamping such that the constriction area finally assumes the required size or thickness between the clamp beams. Inasfar as the clamping pressure should be high enough to effect flowing of the material it is necessary to either suddenly relieve the pressure when it has been measured that the effective deformation e.g. of said 20-40% has been obtained, or - preferably - to positively limit the working stroke of the clamping tool means such that the clamping displacement of the clamp beams is brought to stop when the predetermined final thickness of the constriction has been reached. The tool equipment is easy to provide with suitable adjustable stop means for this purpose.

Thus, the applied clamping pressure is not critical, when it is only high enough to effect the deformation. Normally a pressure of some 100 kp per mm of the effective width of the binder will be suffi ci ent . It has been found possible to set up certain theoretical and empirical expressions for an acceptable shape of the constriction area and a required minimum clamping pressure for obtaining the said super sealing, based on a thorough knowledge of all relevant material constants of the casing material and the binder, but it is deemed unnecessary in the present connection to treat this in more detail, inasfar as it is possible, as mentioned, to ascertain the correct conditions by adjustments based on practical tests.

Besides, it is even believed that there will be experts still better qualified to treat the matter from a physical calculation point of view once it has now been confirmed that based on the considerations of the invention it is, after all, possible to obtain the desired result. In other words, when the result is known to be obtainable this will incite the experts to investigate the matter further, and it will be found, then, that it is possible to scientifically verify the invention and produce prescriptions for a successful use thereof in the various production situations for obtaining a sealing effect at least 10-100 times better than so far obtained. As already mentioned it can be advantageous to^' provide for an exterior holding of the constriction material outside the binder for increasing the -resistance against the axial displacement of the material, whereby, particularly for a casing material of a low E-module, i.e. a relatively soft material, it will be possible to reduce both the required clamping pressure and the mutual clamping displacement of the opposed clamp beams. Hereby the clamp beams may have reduced thickness and the axial dimension of the binder may be kept low, such that a relatively cheap binder can be used. This technique is illustrated schematically in Figs. 19 and 20, where part-c lindrical clamp members 58 are shown to be forced against the casing constriction from opposite sides adjacent both ends of the binder. The clamp members belong to the tool equipment of a machine as also having the required tools, represented by arrows 60, for clamping together the clamp beams of the binder. Care should be taken, of course, that the clamp members 58 do not compress the material sufficient to damage it. Even here, though the clamp members are shown to be arched, they should preferably be planar elements operating in positions next to the respective binder beams.

In Figs. 21 and 22 it is shown that the mounting of the binder on the constriction 18,46 may be effected by moving the constric ion along a slot 62 between opposed guiding plates 64, such plates being provided both above and beneath the binding level. At the inlet end the^'slots 62 have widened portions 66 serving to narrow the constriction area by the introduction thereof. At the discharge ends of the slots 62 the U-member 2 or 36 is held by suitable holding and backing means 68 such that the free Leg ends thereof project slightly over the outer ends of the guiding plates 64. The constriction material is pushed along the slots by means of the block beam 8 or 42, which, itself, is moved by suitable driving means (not shown). Especially from the plan view of Fig. 22 it will be noted that with this arrangement it is ensured that the constriction material will be kept away from the holes in the block beam at the moment of introduction of the leg ends therein, while on the other hand it is also ensured that the material can be allowed to fill out the entire binder opening already before its initial compaction by the further clamping movement of the block beam towards the opposite beam 4,38. The bound area wi ll be laterally removable and the operation repeated. If clamp members 58 (Figs. 19,20) are used they should be arranged above and beneath the guiding plates 64, respectively.

Finally a few examples of providing a "super sealed" closing should be given:

Examp le 1 :

Casing material: BC-1, Cryovac, USA.

2 Yield point: 450 kp/cm .

2 E-module: 3.600 kp/cm .

Thickness: 0.059 mm.

Peripheral length: 500 mm.

Fracture prolongation: 135% Height of binder: 6 mm.

Effective width of binder: 7 mm.

Effective thickness of binder before deformation 4.2 mm

Effective thickness of binder after deformation 2.8 mm.

Clamping pressure applied: 700-800 kp (clamping stop at 2.8 mm).

Example 2:

Casing material: BT-1, Cryovac, USA.

2 Yie.ld point: 500 kp/cm .

E-module: 4.600 kp/cm . Thickness: 0.08 mm.

Peripheral length: 800 mm.

Friction coefficient (measured): 0.20.

Fracture prolongation: 130%

Height of binder: 7 mm. Effective width of binder: 12 mm.

Effective thickness of binder before deformation: 5.4 m

Effective thickness of binder after deformation: 2,5 mm

Clamping pressure applied: 1.200 kp.

In this example a critical magnitude of the deformation is approached, and for increased security it could be advisable to make use of external clamping means according to Figs. 19 and 20.

The examples are based on the nominal values of the various characteristics of the materials, and it has not been taken into account that at least some of these values may vary within inevitable tolerance limits.

Examp les 3 and 4

Material : Polyester Po lyethy lene

Yield point : kp/cm 800 130

E-module: kp/cm 13.200 2100

Th i ckness: mm 0. ,0175 0,095

Periphery: mm 400 800

Fri ct i on coeff .: 0,24 0 27

Fracture pro long. : 25% 410%

Binder:

Height mm 5 7

Width mm 4 16+

Thi ckness : Start mm 1,75 4,75

Stop mm 1,45 2,6

Pressure kp: 400 700

In Example 4 the binder width may be reduced with the use of external clamps 58, Figs. 19 and 20.

The binder itself may consist of DELRIN or a si ilar hard material.

Claims

C LAIMS

1. . A method of closing hose or bag shaped packings, primarily foodstuff packings, whereby a constricted portion of the packing is clamped by a ring shaped non-metallic clamp binder, which is caused to be narrowed about the constriction by a closing pressure applied from opposite sides thereof and is fixed in its shape as attained when it is subjected to a final closing pressure, characterized in that the constriction is clamped between opposed surface portions of substantially straight clamping beams of the binder clamp and is caused to be compacted into a final shape, in which it is cross-sect iona I ly oblong in the longitudinal direction of the substantially parallel clamping beams, preferably with a length at least twice the distance between the clamping beams.

2. A method according to claim 1, whereby the binder portions interconnecting the respective ends of the opposed clamping beams comprise at least at one end a leg member on one beam operable to be received in a lockable manner in a receiver passage in the opposite beam, the method being completed with the free leg member end left uncut and yet in a non-tearing condition, either by being entirely housed inside said passage or - if projecting substantially beyond the rear end of the passage - by having a smoothely rounded end portion.

3.^' A method according to claim 1, particularly for obtaining a very effective sealing of a constricted casing material of plastic, whereby the binder is selected and the constriction disposed in such a manner that in the said final shape of the binder the binder opening is entirely filled out by the constriction material,_, this material being subjected to such a compaction pressure between the clamping beams that in each and every part of the final constriction area the plastic material, is effect vely axially displaced to a degree below rupture prolongation and thus assumes an overall axially expanded condition.

4. A method according to claim 3, whereby the applied pressure is steadi ly sufficient to deform the constriction material and the opposed clamping beams are caused to be mechanically stopped at such a mutual distance, which corresponds to the effect ve distance between the clamping beams being of a size required for ensuring the overall axial expansion of the material.

5. A method according to claim 4, whereby in order to counteract a rupture prolongation of the axially expanding material with the use of a binder of relatively small axial length the constricted material portions just outside the opposed ends of the binder are mechanically clamped between clamp tool members and thus axially stabi lized while the clamping beams are forced into their final posi t ions.

6. A clamp binder for closing hose or bag shaped pack ngs by the method claimed in claim 1 or 3, consisting of a non-metallic material and comprising two opposed clamping portions and connector means therebetween for confining, together with the clamping portions, an annular binder structure, in which at least one of said connector means is operable to interlock the associated parts of the clamping portions with a mutual spacing therebetween upon the clamping portions being forced against a constricted packing portion from opposite sides thereof, characterized in that the opposed clamping portions are constituted by substantially straight clamping beams and that the connector means are arranged to as to enable the binder to be closed about a non-compacted constriction area and enable the clamping beams to be forced together to compress the constriction area into a final shape, in which the beams are substantially parallel and spaced from each other less than the spacing between the respective connector means.

7. A binder according to claim 6, in which one of the clamping beams is at each end provided with a laterally protruding leg member so as to form a rigid U-member with a straight bottom portion, while the outer clamping beam is provided with two individual holes for receiving the Let members, arresting means being provided in connection with each leg member and/or hole operable to lock the leg members against retraction from the hoLes.

8. A binder according to claim 7, in which the arresting means comprise wedge members projecting from the free ends of the leg members so as to be int roduceable into the holes along with the Leg ends and to be repressable from the opposite end of the holes for widening the cross sectional area of the Leg ends sufficiently to effect a retraction locking of the leg member in the hole.

9. A machine for mounting a clamp binder on a constricted packing portion in connection with the method claimed in claim 1,3 or 5, comprising means for forcing opposed binder portions against the constricted portion and characterized in further comprising clamping tool means operable to clamp the constricted material just outside the opposed axial ends of the clamp binder for stabilizing the mater al against exessive axial displacement in the area surrounded by the clamp binder.