Method, a binder and a binding machine for closing hose or bag shaped packings, primarily tubular foodstuff packings

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 proposed 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 provide a "super tight" closure, by ranging 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 casing material.

Description

BACKGROUND OF THE INVENTIONThe present invention relates to 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 closing pressure.Typical packings will 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 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 durability, while the plastic sheet material should be as tight as possible for rendering the packed products as durable as possible.In both cases almost the...

AI Technical Summary

Problems solved by technology

In both cases almost the same problem exists, namely that the binding of the constrictions should be effected very tightly such that in case of sausages the clamp binders will not slide on the normally very slippery sausage skins before and during the smoking, while the clamps when mounted on the plastic sheet envelopes should likewise be nonslidable, but also provide for an effective sealing against penetration of air.

In both cases it is normally necessary to make use of clamping forces which are so high that a potential danger of the sheet material being damaged will exist, and, in fact, it is well known that in the relevant productions a most significant waste on this account is being experiment.

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 high waste, because they have a limited ability to hold the material tightly clamped, and that they show a major disadvantage in just being of metal.

It is relevant to mention also that it has been found that the metal clips are simply unable to close the plastic sheet packings 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 incoming the storage durability 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 area.

The already known plastic binders, however, suffer from various drawbacks which will not be discussed in great detail in the present context.

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

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 portions shaped in this manner.

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.

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 casing.

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 scaled closing is concerned such a series of clips will be of no help at all, as none of the clips will have any chance of providing for a "super sealing".

Correspondingly, in order to limit the number of different standard binders it may be desirable, for a given production, to select a binder type which will give rise to such rearwardly protruding leg ends, and generally this will be disadvantageous in that projecting binder portions will present a tearing risk towards neighboring packings.

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 occurring together with the products themselves.

Some of the already known plastic binders could 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 really burst at this place by an applied high pressure, and another problem is that in the prior art it has generally been endeavored to produce a finally bound constriction area of approximately uniform thickness and width.

Particularly with the use of sheet materials of a low 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 small 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.

When the clamping pressure is relieved and the 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 ensued that a real compaction and axial displacement of all sub portions of the material in the binding area has been obtained.

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