CH649684A5 - COMPACT ENVELOPE FOR FOOD PRODUCTS AND METHODS OF MAKING SAME. - Google Patents

Description

The invention relates to a compacted envelope for food products, the envelope itself being mounted on a rigid tubular core, in a pleated and compressed form and forming with it an assembly which will be called here compacted envelope.

Obtained, compared to what was possible hitherto, a significantly increased packing length having a more stable and more resistant structure and having the additional characteristic of allowing the adaptation of envelopes currently commercially available in dimensions data, for use on tamping mandrels with a larger passage section.

Artificial food wrappers, used in the processing of a wide variety of meats and other food products, for example sausages of various types, cheese rolls, turkey roasts and the like, are commonly prepared from regenerated cellulose and other cellulosic materials. The envelopes exist in several different types and in several dimensions in order to suit the different categories of food products to be prepared and they are available in reinforced or unreinforced form, the reinforced or fibrous envelopes comprising a fibrous reinforcing sheet embedded in their wall.

A characteristic common to many processed products, in particular meat products, is that the mixture of edible ingredients is introduced or stuffed into a pressure envelope and the processing of the food product takes place after it has been thus placed in the envelope. The food product can also be stored and transported while it is wrapped, although in many cases and in particular in the case of small sausages such as frankfurters, the envelope is removed from the food product at the end of treatment.

The expression “small envelopes for food products” generally designates the envelopes used for the preparation of small sausages such as frankfurters. As this expression suggests, this type of envelope for food products has, when packed, a small diameter, the diameter in the expanded state generally being between about 13 and about 40 mm, and this envelope is the more generally supplied in the form of tubes with thin wall, not reinforced, of very great length. To facilitate handling, these envelopes, which may be 20 to 50 m in length or even more, are pleated and compressed to form pleated envelopes 20 to 60 cm in length. U.S. Patents Nos. 2983949 and 2984574, among others, describe pleating machines and the products they produce.

The expression “large food envelopes”, designating envelopes used for the preparation of relatively large food products such as salamis and mortadella, meat loaves, cooked and smoked ham heels and the like, are produced so as to have, when packed, diameters of 40 to 200 mm or even more. In general, these envelopes have a wall approximately three times thicker than that of small envelopes and they have a fibrous reinforcing sheet embedded in their wall, although they can be prepared without this reinforcing element. For many years, large tubular casings have been supplied to food processing companies in the flattened state, cut to predetermined lengths from 0.6 to 2.2 mm. However, more recently, large envelopes, both of the fibrous type and of the unreinforced type, have been and still are supplied in the form of pleated envelopes comprising up to approximately 65 m of envelopes to be stuffed with devices working at high speed.

When preparing and using artificial envelopes for food, it is very important to control the moisture content of the envelopes. Although the pleated cellulosic envelopes of the type used in the invention must have a moisture content of at least 13% of the total weight of the envelope, the moisture content may be higher.

When small envelopes of regenerated cellulose are produced, it is generally preferable that their water content is between 14 and 18% of the total weight of the envelope to allow the execution of tamping operations without deterioration of the envelope. This relatively narrow range of moisture content is also important, since excessive envelope ruptures have occurred during packing at lower moisture contents, and higher moisture contents have the effect of imparting excessive plasticity to the envelope material and, therefore, to cause excessive stuffing.

The large envelopes as described above have recently been improved in that pleated and compressed envelope sections are available in the prehumidified state so that the long operation has now been eliminated. and difficult to soak these envelopes immediately before the tamping operation. The moisture contents of larger envelopes, of the type with fibrous reinforcement, supplied in the pleated and pre-humidified state, are generally between 16 and 35% of the total weight of the envelope.

The particular moisture content can be chosen to suit the requirements or preferences of the user. If the moisture content is high and a long storage period is planned before tamping, it is advisable to take measures to prevent the growth of mold or bacteria. A known method consists in limiting the activity of the water added before or during the stuffing by means of sufficient quantities of solutes such as propylene glycol or glycerin. These materials also assume useful functions of plasticizers or humectants in envelopes to be pleated and compressed.

The envelope pleating techniques described above with reference to the aforementioned patents, as well as in other patents, can be generally described as consisting in continuously advancing a section of flat food envelope, for example from a coil, in order to introduce it into a pleating machine where it is inflated with a low pressure gas, usually air. The inflated envelope passes through a group of pleating rollers which pleat it against a retainer mounted on the mandrel or around the pleating mandrel until the predetermined pleated length is obtained. In the case of a pleating machine of the floating mandrel type, as described, for example,

in U.S. Patent No. 3,766,603, the pleated casing is then transferred beyond or away from the retaining member against which pleating was performed and onto an extension of the mandrel where it is compressed to a desired length. In the case of a shrink-fit pleating machine, as described, for example, in U.S. Patent No. 2583654, the pleating mandrel, on which the pleated casing remains, is turned toward another position in which the pleated envelope is compressed to the desired length.

Normal compression makes it possible to obtain an envelope the length of which can be between 1.0 and 1.2 or 1.3% of the initial length of the envelope.

5

10

15

20

25

30

35

40

45

50

55

60

65

649,684

4

U.S. Patent No. 2001,461, for example, describes how an envelope with an initial length of 1006 cm is reduced to a length of less than 10 cm. It is further indicated in the aforementioned patent that the lower practical limit to which it is probably possible to bring down the ratio of the length 5 of the pleated envelope to the length of the initial envelope is around 1 / 130. However, the aforementioned patent does not recognize the problems encountered when attempting to produce a pleated and highly compressed envelope of commercially practical length, and it ignores the importance of the dimension 10 of the opening of the envelope.

In industry, to date, the ratios of the initial length of the envelope to the length of the pleated envelope have generally been 70 to 100. Such a ratio is referred to as "compression ratio" or "compression ratio". reduction ”and it is the reverse of the report described in the patent No. 2001461 cited above.

Another way to quantitatively express the amount of compression of the initial envelope lengths is through compression efficiency. The compression efficiency is defined as the ratio of the volume of the pleated and compressed envelope, of unit length, to the volume which would be occupied by the full envelope of the same unit length, and it can be determined by the relation next:

PE

Lc x (2 x FW x te) | (OD2 - ID2) x Ls

PE = compression efficiency Lc = envelope length Ls = length of the pleated envelope FW = flat width of the envelope tc = thickness of the envelope wall OD = outside diameter of the pleated envelope ID = diameter inside the pleated envelope This calculation automatically takes into account the density and / or density of the material of the envelope. An examination of the relationship shows that the ratio is in fact the volume occupied by the flat envelope in the pleated envelope, divided by the volume of a hollow cylinder having the same dimensions as the pleated envelope. The importance of the increase in compression efficiency is therefore measured by its approximation of one (1), namely the unit.

Since the compression ratio is the ratio Lc to Ls, another means for expressing the compression efficiency is given by the following relation:

30

40

45

PE = (compression ratio)

2 x FW x tc | (OD2 - ID2)

It can be seen that for a given compression efficiency, the compression ratio varies with the difference between the outside diameter and the inside diameter of a pleated envelope of given size. In addition, since the outside diameter is necessai-reemnt limited by the flat width (FW) of the envelope, an increase in the difference in diameter to increase the compression ratio must decrease, at the end of account, the size of the opening or the inside diameter. Although the objectives of a maximum opening of the pleated envelope and a maximum compression ratio are antagonistic, the fact remains that the compression yield is maximized at a given compression ratio when the internal diameter of the pleated envelope is maximized.

It is generally desirable to use the tamping mandrel having a maximum dimension bore (maximum internal section) 65 with an envelope of given dimension, in part to maximize the production throughput and minimize the tamping pressure. Another reason for using a maximum size mandrel is the elimination of the risk of "degreasing". Degreasing is a phenomenon which occurs when the meat emulsion is passed through a stuffing mandrel at a sufficiently high shearing speed to cause the emulsion to decompose and allow the water and the fat to separate. Water and fat then accumulate between the surface of the finished sausage and the cellulosic food shell during processing, resulting in an unsatisfactory sausage, with an unacceptable visual appearance. The shear rate decreases as the inside diameter of the tamping mandrel increases.

The aims sought in pleating technology consist in producing a pleated envelope which can be unfolded and stuffed on a tamping device, continuously, without mechanical defects or breakdowns, in order to ensure continuous production, the pleated envelope itself even having a structural and mechanical integrity, that is to say a coherence, sufficient to support the loads to which it is normally subjected during packaging, storage, handling and positioning on the tamping device, and it is also desired to compress, into a pleated envelope of given length, an envelope to be stuffed as long as it is technically possible in order to use it on a tamping mandrel whose channel is as large as possible.

Consequently, the ideal pleated envelope is a pleated envelope of high consistency, associating a large envelope length per unit length of the pleated envelope (high compression ratio) with a large internal diameter or a large opening dimension. (high compression efficiency).

U.S. Patent No. 3,528,825 describes an earlier means for calculating the compression ratio and efficiency. The description, from line 75 of column 5 to line 5 of column 6, relates to a pleated envelope in which an envelope 30 m in length has an outer diameter when inflated of 1.75 cm for a wall thickness of 0.0254 mm. This envelope is pleated to have an outside diameter of 2.22 cm, an inside diameter of 1.27 cm and a length of 41.28 cm. Using these data and the preceding formula giving the compression efficiency, it appeared that the envelope of the prior art, described in the aforementioned patent No. 3528825, has a compression efficiency of 0.374. The compression ratio of this anterior envelope is 70, namely a length of 30 m reduced to 41.28 cm by pleating and compression.

The consistency of a pleated envelope on the core is determined by the measurement of the bending moment, in N / cm at the time of the breaking of a stick. A pleated envelope is wedged on two supports with V-notches, fixed on a base plate and spaced by a distance (D) equal to 80 to 90% of the length of the pleated envelope tested. A pressure element, comprising spacers with V-notches spaced apart by a distance D - 10 cm, is lowered centrally on top of the pleated casing. Downward pressure is exerted using a hand-operated handle, a rack and pinion linkage on a dynamometer (such as the Hunter force measurement device of type "L-IM model"). "With" a maximum holding device ") which is fixed centrally on the pressure element. Increasing force is applied until the pleated envelope breaks. The force P indicated in newtons is noted. The bending moment, in newtons / centimeter at the time of the rupture occurring on the device is equal to P / 2 x 5 cm and, consequently, the force P displayed is equal to the value, in N / cm, of the bending moment breaking the pleated envelope. In general, a consistency of at least 14 N / cm is necessary, and a consistency of at least 28.25 N / cm is particularly suitable and preferred.

Since the relationship between the useful diameter of the opening of the pleated envelope and the diameter of the tamping mandrel is a most significant measure of the operability of the envelope, a free fall test was designed on rod to which the pleated envelopes are subjected. To simulate the placement of a pleated envelope on a tamping mandrel and thus measure the useful internal diameter of the pleated envelope, we designed a test in which a pleated envelope is placed on the end

5

649,684

of a vertical stainless steel rod, of length greater than that of the pleated envelope, and then the pleated envelope is allowed to fall freely under the effect of its own weight, around the rod, to its end lower. In particular, the rod can be arranged vertically on a table. The pleated envelope is placed on the upper end of the rod, then released. If the pleated envelope falls to the table surface, the free fall test is satisfactory. There is a set of rods whose diameters increase by 0.254 to 0.254 mm and, for certain ranges of envelope dimensions, rods have been produced whose diameters increase in steps of 0.051 mm. The pleated envelope is tested on each rod, starting from the smallest rod and passing over rods of increasing size until it can no longer fall freely over the entire length of the rod. The rod of larger diameter on which the pleated envelope falls freely over its entire length indicates the useful internal diameter of the pleated envelope, that is to say the rod diameter in the free fall test.

In the manufacture of pleated cellulosic envelopes, the size of the opening varies slightly from one pleated envelope to another, partly as a result of the irregularities presented by the projections of the pleats inside the opening of the envelope pleated. This is the reason why, during tests, it is necessary to submit several pleated envelopes, for example at least 10, to the free fall test, and the arithmetic mean is used to determine the functional character of the assembly. of the group with regard to the adjustment on the tamping mandrel. As indicated previously, the rod diameter means in the free fall test are preferably calculated with an accuracy of 0.025 mm, and the requested tolerance is defined with this degree of precision. For example, if the requested value is at least 12.446 mm, an average drop test of 12.4206 mm would be unacceptable, since a large number of pleated envelopes of the group represented by the average measurement in the drop test of 12, 4206 mm would not be functional on a 12.446 mm diameter tamping mandrel.

One of the most important factors in the pleating of a small food envelope is the quality of the consistency, that is to say the stability of the pleated envelope as a self-supporting article. The consistency of the pleated envelope is particularly important when determining the suitability of such pleated envelopes for use with automatic food stuffing equipment, for example the machine used for the preparation of products such as sausages. Frankfurt. A gap or cut in a pleated envelope before it is mounted on a tamping mandrel makes it unsuitable for use on such automatic tamping equipment. Consequently, any treatment of the tubular food envelope, which can be put in the form of a pleated envelope, should not harm the coherence of the pleated envelope, but should on the contrary tend to increase it.

Significant efforts have been made recently in the envelope industry for food products, in particular small envelopes, on the development of systems for producing highly coherent pleated envelopes. These efforts include, among other things, chemical treatments such as that described, for example, in U.S. Patent No. 4,137,947.

Conventional pleating on modern pleating machines gives pleated envelopes with a visible angular offset between a plane perpendicular to the longitudinal axis of the pleated envelope and a plane in which a pleat is formed. This offset is called the fold angle. A conventional pleated envelope, devoid of the core element according to the invention, and having a pleat angle of this nature has a consistency and a structural integrity notably superior to those of an envelope of the same type which has been pleated with so that the folds are perpendicular to the longitudinal axis, because the overall length of the pleated envelope is substantially equal to that of a stack of cones nested one inside the other and connected together.

It has been discovered, in particular for smaller envelopes used for the manufacture of Frankfurt sausage type products, that, when a conventional pleated envelope (without core) is strongly compressed so that its compression ratio is maximized, the consistency or structural integrity of the pleated compressed envelope deteriorates to the point of rendering it unusable. In other words, the pleated envelope is made fragile, breaks easily and cannot therefore be mounted on a tamping mandrel. This effect is believed to occur when the large longitudinal compressive forces tend to flatten the geometry of the "nested cones" produced during the pleating operation.

It has now been discovered that when a tubular casing is subjected to the pleating operation (i.e. transformed from a flattened tubular form to a pleated and compressed form, as described above), it appears in the pleated envelope resulting from the significant forces, acting radially inwards, when high compression yields are obtained. The amplitude of these great forces was not known before strongly compressing pleated envelopes on core elements, and it appeared that substantially rigid cores would experience some loss of diameter over time. It has hitherto been known that the inside diameter of conventional pleated envelopes (without tubular core) showed a sudden decrease in withdrawing (unloading) from the pleating mandrel immediately after compression, and that a further more gradual reduction seemed to continue during about a week or more after removal of the mandrel, the magnitude of the forces causing this loss of diameter is not recognized in the prior art. It has further been discovered that the magnitude of these radially inwardly directed forces is proportional to the longitudinal compressive force used to compress the envelope to the initial compressed length that the envelope has immediately before being discharged. of the mandrel. In other words, the forces exerted radially inwards increase with the longitudinal compression force.

British Patent No. 1167377 describes a pleated tubular casing which is carried by a hollow gauge (core) configured and dimensioned to fit around a tamping mandrel. It is stated in the aforementioned patent that a friction adjustment is made inside the pleated envelope to prevent decompression or sliding of the latter out of the gauge. It is indicated that the size can be made of any desired material, for example synthetic plastic or thin cardboard. According to a particular embodiment of the size described in the aforementioned patent, this size is made of extruded polyvinyl chloride to form a cylinder whose wall has a thickness of about 0.25 mm. The article described in the aforementioned patent was marketed in the form of a tubular sheet of polyvinylidene chloride, pleated on a cellulose acetate core with an internal diameter of 25 mm and a wall thickness of about 0.292 mm. The object described in the aforementioned British patent has never been used with a pleated cellulosic tubular envelope.

In addition to the above use, the use of a hollow core or a central tube, as a support for pleated envelopes of large dimensions, has been known for many years. However, all the applications, known so far, of the concept of a core with pleated cellulosic envelopes have been aimed at ensuring integrity and preventing the increase in dimensions during imbibition. Rods with an envelope of small dimensions were used for transport and handling, before the development of coherent envelope sticks. The pleated envelope was slid out of the rods so as to pass over the tamping mandrels during use.

In recent years, the technique of cellulosic food envelopes has turned away from the use of inner tubes intended to hold and support the envelopes in order to direct towards external means of holding and support such as nets or shrink films. or elastic in the case of envelopes of intermediate and large dimensions. Small envelopes are used in pleated form, without other means of support.

5

10

15

20

25

30

35

40

45

50

55

60

65

649,684

6

The object of the invention is to create a compacted envelope which does not have the drawbacks mentioned. To this end, the compacted envelope according to the invention is arranged as defined in claim 1.

It has appeared, according to the invention, a new use for cores, different from that of the prior art and according to which the cores are intended to reduce the effects of the force exerted radially inwards on the envelope pleated to such an extent that not only are compression ratios substantially greater than those obtained in the prior art obtained (pleated sticks without a core, compressed and pleated under the same conditions), but that these higher compression ratios can be obtained with envelopes having usable opening dimensions equivalent to or even greater than those possible with comparable pleated envelopes without the aforementioned core. This is contrary to the forecasts of those skilled in the art, that is to say the forecasts which considered that a soul would occupy space and therefore reduce the useful opening of the envelope. Therefore, it was expected that a core would have a negative effect on the compression ratio. Contrary to this forecast, the high density and core cellulosic envelope according to the invention can have a significantly higher compression ratio, without reducing the size of the usable opening. Another characteristic of the envelope according to the invention is that it has structural integrity and improved resistance.

In one embodiment which is particularly useful with a stuffing apparatus for packaging pieces of meat, such as whole boneless hams and the like, the core itself is used in place of a stuffing mandrel. It should be noted that such a device is the subject of United States patent application No. 261313.

Another embodiment of the invention comprises a pleated envelope with high density and core, the latter being able to be used selectively as a support tube intended to be slid over a tamping mandrel of a tamping device or, alternatively, as tamping mandrel proper, comprising a calibrating element of one type or another, mounted on the core and disposed inside a stretched section of the pleated envelope. It should however be noted that such a pleated envelope is the subject of United States patent application No. 273180.

In general, the cellulosic food envelope is determinedly humidified, having a moisture content equal to at least 13% of the total weight of the envelope, this section of envelope being pleated and strongly compressed on the core. , at a high compression ratio and at a compression efficiency not lower than 0.50, the compression ratio and efficiency being also and respectively greater than those obtained with the same length of envelope, pleated and strongly compressed, under the same pleating and compression conditions, but without a core, thus generating a significant expansion force, oriented towards the inside of the envelope. The core must be rigid enough to resist deformations and size reductions in its opening under the effect of the significant force of expansion exerted inward. By way of comparison between pleated and compressed envelopes with core and without core, it can be noted that the envelope without core has no external longitudinal retaining element.

In a preferred practical form of the invention, the compression efficiency is maintained at 0.60 and above.

In a preferred embodiment of this coherent compacted envelope, based on a comparison of the falling tests, the core has an interior opening whose dimension is at least as large as that of the interior opening of the same pleated envelope. and strongly compressed, under the same pleating and compression conditions, but without a core. In a preferred embodiment, the envelope is of the unreinforced cellulose type, of small size, having an inflated diameter of less than 40 mm, and it is compressed at a compression ratio of at least 100.

The invention also relates to the methods of manufacturing an envelope; these methods are defined in claims 18 and 24.

The particular preferred moisture content for different types of envelopes may vary. In particular, the moisture content of pleated fibrous envelopes, humidified in a controlled manner and included in the range of large dimensions, is preferably from 16 to 35% of the total weight of the envelope.

The preferred range of moisture content for intermediate size envelopes can also be 16 to 35% of the total weight of the envelope.

The envelopes of smaller dimensions, used for the manufacture of products of the Frankfurt sausage type and others, advantageously have moisture contents of 14 to 18% of the total weight of the envelope.

The tubular core must be rigid enough to resist deformation and the reduction in the size of its opening under the effect of the force exerted towards the inside of the envelope, knowing that a slight deformation and a slight decreases in opening occur but remain acceptable if not excessive. The diameter of the core can vary from 9.5 mm to 12.5 cm, depending on the size of the envelope and the requested opening dimension. The thickness of the wall of the core can vary to suit the article with a particular envelope, as well as its adaptation and use and, moreover, according to the material used for the core. However, in general, it can be considered that the thickness of the wall of such a tubular core is comprised between 0.051 cm and 0.254 cm.

The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting examples and in which:

fig. 1 is an elevation of an apparatus which can be used to produce a compacted envelope according to the invention, by implementing the method of the invention, this view showing the pleating operation performed on a section of advancing envelope continuously;

fig. 2 is an elevation showing the pleating operation completed and the pleated envelope section transported to the compression station of the apparatus of FIG. 1;

fig. 3 is a partial elevation showing the application of the compression force to produce the pleated casing according to the invention on a core mounted on an extension of the pleating machine;

fig. 4 is a perspective view, with partial cutaway, of the pleated and compressed envelope placed on a hollow tubular core;

fig. 5 is a perspective view, partially broken away, of a variant of the compacted envelope according to the invention intended to be used as a stuffing horn on a stuffing device intended for the treatment of products in the form of pieces of meat;

fig. 6 is a perspective view of an embodiment of the compacted envelope according to the invention particularly suitable for stuffing medium-sized products, the core being able to be used as a support intended to be slid over a stuffing horn or else , alternatively, as a stuffing horn for the device itself;

fig. 7 is a partial elevation of an embodiment of the compacted envelope according to the invention suitable for stuffing small sausages, the core replacing the stuffing horn on the stuffing machine during manufacture;

fig. 8 is a graph showing the rod diameter of the test in free fall as a function of the compression ratio for pleated envelopes without core and with core, formed from a non-fibrous envelope of 48 m in length and of small diameter (size 25, i.e. 21 mm);

fig. 9 is a graph showing the coherence as a function of the compression ratio for pleated envelopes without a core formed from a non-fibrous envelope 48 m in length and of small diameter (size 25, ie 21 mm);

fig. 10 is a graph showing the free fall test as a function of the compression ratio for pleated envelopes without

5

10

15

20

25

30

35

40

45

50

55

60

65

7

649684

core formed from small diameter cellulose envelopes (sizes 17, 21 and 27, ie diameters of 15.5, 18.9 and 22.6 mm in the inflated state), without fibrous reinforcement, all envelopes of a particular dimension having the same length;

fig. 11 is a graph showing the coherence as a function of the compression ratio in the case of pleated envelopes without a core indicated in FIG. 10;

fig. 12 is a graph showing the maximum compression ratio that can be obtained with pleated envelopes without a core and with a core, formed from fibrous envelopes of intermediate dimensions, included in the range of sizes from 43 to 60, to adjust on a 27.25 mm packing horn, and fig. 13 is a graph showing the same relationship as in FIG. 12, for fibrous envelopes of intermediate dimensions, the sizes of which are between 70 and 100, so as to fit on a stuffing horn of 39.52 mm.

The drawings, and more particularly figs. 1 and 2 show a typical pleating machine of the floating mandrel type, generally designated at 11 and comprising a pleating mandrel 13 which passes through a pleating head 15. An inflated casing 17 is advanced on the mandrel 13 by means of two supply rollers 19 and two complementary supply strips 21. The pleating head 15 comprises several pleating wheels 23, usually three wheels, between which the inflated casing 17 passes, these wheels pleating the casing by cooperating with retaining bands 25. The pleating wheels are of the general type described in United States patent No. 3461484.

The advance of the pleated envelope 17 on the mandrel 13 is braked by a set of retaining bands 25 so as to cause formation of substantially regular folds and the production of a pleated envelope partially compressed. After the initial pleating and folding action, the envelope is transferred by the retaining bands downstream on the mandrel and in the direction of a first collar 27.

To effect the transfer of the pleated envelope onto the hollow and substantially rigid tubular core and complete its compression on this core, in accordance with the invention, the first collar 27 is tilted out of the stroke followed by the envelope and advances a pleated section, by hand, or by any conventional automatic device, to the position shown in fig. 2 until it bears against a second collar 29. In this position, the pleated envelope section is arranged on the hollow tubular core 31 placed on a necked or reduced section of the mandrel 13, as shown in FIG. . 3 which is an enlarged and detailed view on the right side of FIG. 2. The final compression of the envelope 17 on the hollowed tubular core 31 is carried out using a compression device 33 which moves linearly towards the second collar 29 until one obtains l pleated envelope having the desired length. A disc or a retaining washer 35 can advantageously be inserted between the end of the casing 17 and the second collar 29 so that, when the article is removed, the casing is fixedly held on the hollow tubular core and cannot slip out of the end of this soul.

When a high density envelope is completed in accordance with the operations described above, the second collar 29 is removed from its retaining position and the finished pleated envelope is removed.

The compacted envelope according to the invention can be assembled, for example, by transferring the pleated and partially compressed envelope onto its hollow tubular core 31, in the manner described above. Fig. 3 shows the section of pleated and partially compressed envelope which is brought linearly onto a core arranged coaxially with the pleating mandrel 13, the core being advanced on a section of reduced diameter of this mandrel, then the final compression force being exerted by means of a compression device 33.

Other methods can be implemented to place a pleated envelope on a core. For example, in a pleating machine of the floating mandrel type such as that described above, the pleated casing can be completely compressed on the mandrel of the machine, then discharged onto a tubular core. It is also possible to completely remove the pleated and partially compressed envelope section from the pleating machine 11 by passing it over a transport bar or over a support mandrel, and to move the entire envelope section towards a independent compression device where the pleated envelope section is placed on a core and compressed. Alternatively, the core can be placed on the floating mandrel, then positioned so that the envelope is pleated on this core, the pleated envelope, comprising the core, then being completely compressed on said core and the envelope thus formed. and completely compressed on the core then being discharged from the mandrel.

Another pleating system, implementing a pleating machine with withdrawal mandrel, is described in the aforementioned patent N ° 2583654. This type of pleating system can be used in the manufacture of the compacted casing according to the invention and it allows the pleating of the casing directly on a core on which the casing can then be compressed. In one embodiment, the core is placed on the pleating and removal mandrel and it is positioned on the latter so that the envelope is pleated on the core, the pleated envelope then being completely compressed on the core and the envelope thus formed and completely compressed and the core then being discharged from the mandrel. In another embodiment, the casing can be pleated and compressed on the withdrawal mandrel in the conventional manner, and the pleated and compressed casing can be slid from the mandrel onto the core. In another embodiment, the envelope can be pleated and partially compressed on the withdrawal mandrel, the latter is then brought into a new position in which it is coaxial with the core, the pleated and partially compressed envelope is slid of the mandrel on the core, and the pleated envelope is then completely compressed on the core. It is also possible to completely remove the pleated and partially compressed envelope section from the pleating apparatus with withdrawal mandrel by unloading it on a transport rod or on a support mandrel, then transferring the pleated and partially compressed envelope compressed from the transport rod or the support mandrel on the core which is mounted in an independent compression device where the pleated envelope is then completely compressed on the core.

Obtaining the maximum possible compression ratio with the compacted casing according to the invention requires the application of a high compressive force which itself induces significant forces, exerting radially inwards in the 'pleated envelope. Since the preferred method of preparing the compacted envelope according to the invention consists in compressing the pleated envelope while it is in place on its core, it will be appreciated that a low coefficient of friction between the envelope and the soul is desirable. Example 7 (described in more detail below) shows that a high compression ratio can be obtained with a core made of a material such as high density polyethylene, having a relatively low coefficient of friction, compared to polypropylene or polystyrene with higher coefficients of friction.

Fig. 4 shows a compacted envelope according to the invention, in particular a section of humidified cellulosic food envelope 17, pleated and compressed on a substantially rigid tubular core 31 at a ratio and at a compression efficiency higher than those conventionally obtained. Fig. 4 also shows holding discs 35 which can be optionally arranged at the two ends of the pleated envelope section in order to keep it in the compressed state on the core.

Fig. 5 shows a presently preferred embodiment of a high density pleating on a core, carried out on the removable tamping mandrel which is the subject of patent application of the United States of America No. 261313. In this embodiment , a tilting element 37 for retaining the envelope is mounted on the hollow tubular core 31, inside an unthreaded section of the en5

10

15

20

25

30

35

40

45

50

55

60

65

649,684

veloppe 17, this section having been pulled from the length of pleated and compressed envelope, on the tilting retaining element and on the end of the tamping mandrel and of the tubular core, so that the unfolded section can be closed using a tie to constitute a ligature for the product to be stuffed. A flange 39 is used, as shown, at the opposite end of the envelope in order to facilitate the mounting of the latter on the tamping device.

Fig. 6 shows the compacted envelope according to the invention, suitable for an envelope holder or support sleeve intended to be slid over the tamping mandrel of a tamping device. When so used, a flange 39 can be connected to a mechanism that is part of the tamping machine and communicates reciprocating motion to the entire sleeve to perform release operations when necessary during the tamping process. An embodiment very similar to that shown in FIG. 6 can be used, as a variant, as a sleeve which contains a calibrating or retaining element, in which case an unfolded section of the casing must be pulled over this calibrating or retaining element and over the end of the tubular core , and this unfolded section must be closed with a tie to retain the product during stuffing.

Fig. 7 shows a compacted envelope according to the invention designed to be used when stuffing small sausages. This compacted envelope comprises a mounting adapter 41 which is arranged so as to fit directly on a tamping machine, the hollow tubular core 31 thus replacing the conventional tamping mandrel. In this case, the envelope 17 is partially unfolded, pulled on a calibration element 43 and on the end of the tube-mandrel where it is closed to form a ligature preventing the passage of the product during the tamping operation. It is particularly advantageous to provide long lengths of envelopes for stuffing small sausages, since these articles are produced to a large extent on automatic stuffing machines working at high speed. The use of the compacted casing according to the invention allows the use of substantially longer casing lengths, which increases the operating efficiency of such equipment and, at the same time, meets the dimensional criteria of high precision. (for example their straightness) and the structural integrity (consistency) required of the envelopes to be used on such equipment.

Fig. 7 also represents the angle 0 of the fold of the envelope compacted in accordance with the invention. Conventional pleating on modern pleating machines gives pleated envelopes which have a visible angular offset between a plane perpendicular to the longitudinal axis of the envelope and a plane containing the folds resulting from pleating. A soulless envelope with such a pleat angle is found to have significantly greater structural integrity and integrity than a similar type of envelope would have if pleated so that the pleat angle is perpendicular to the axis. longitudinal, since the entire envelope is substantially similar to a stack of cones nested one inside the other. The core provides sufficient structural rigidity so that the consistency no longer depends on the angle of the fold.

One of the reasons why envelopes compacted according to the invention may have a certain fold angle 0 is the resistance to the longitudinal growth of the envelope. Pleated envelopes, immediately after being discharged from the pleating and / or compression mandrel, tend to show some growth, which is the tendency of the pleated, compressed and unrestrained envelope to elongate. In the case of pleated and compressed envelopes without a core, there is another growth of the pleated envelope radially inward in the opening of the stick, this phenomenon increasing in proportion to the restraint of the longitudinal growth of the envelope.

The tendency of a pleated and compressed envelope to grow radially inward against the core produces an additional effect of blocking the folds of the envelope against the outer surface of the core. With this advantageous effect, the tendency of the pleated and finished envelope to grow longitudinally is substantially reduced by the friction occurring between the plies, as well as by the frictional forces occurring between the plies and the core, so that it a minimum additional longitudinal restraint is sufficient to stabilize the dimensions of the envelope.

Example 1:

A section of large fibrous envelope, 76.22 m in length and size 10, in commercial designation, having an average flat width of 19.18 cm and a wall thickness of 0.10 mm, is pleated using pleating means very similar to those described in the aforementioned patent N ° 3461484. The envelope has a moisture content of approximately 20% based on the total weight of said envelope. A mineral oil-based lubricant is conventionally used. Oil is used inside to reduce the friction on the mandrel and oil is also used outside to prevent deterioration of the envelope during pleating and excessive wear of the pleating rollers. The mineral oil-based lubricant is applied internally at a flow rate of approximately 28 mg of oil per 100 cm2 of envelope surface, and externally at a flow rate of approximately 15.5 mg of oil per 100 cm2 of envelope surface, these quantities having no apparent harmful effect on the properties of the finished envelope. The envelope is compressed from one end onto a tubular core of high density polyethylene, having an internal diameter of 9.53 cm and a wall thickness of 0.16 cm, so that an envelope is obtained. pleated with a length of 58.42 cm. The envelope is prepared on a pleating machine of the floating mandrel type, in a manner described above, the pleated envelope being transferred, after pleating and slight compression, onto a core which is arranged coaxially with the pleating mandrel, on a section of reduced diameter of the latter, before being finally compressed in position on the core and discharged. A high density pleated envelope is thus obtained, comprising a core, in accordance with the invention and having a compression ratio of 130.4 and a compression efficiency of approximately 0.757.

To make a comparison with a control sample, a section of normal envelope of the same size and of the same type, commercially available, having a length of 45 m, is pleated and compressed until one obtains the same length of the pleated envelope of 58.42 cm, without core and that one also obtains a compression ratio of 78 and a compression efficiency of 0.390, with a lower opening diameter of 92 mm. Other coreless control samples, having a higher compression ratio and yield, yield non-functional articles as a result of an excessive reduction in the opening due to inward radial growth.

Example 2:

The fact that very high forces are exerted towards the inside of the opening of the envelope as a result of the pleating operation is demonstrated by experimental work consisting of pleating and compressing at high compression ratios and yields, samples of a small cellulose envelope, namely of size 25 (21 mm in diameter in the inflated state), without fibrous reinforcement, having a wall thickness of approximately 0.0254 mm. During the experimental work, lengths of 25.61 mm of cellulose envelope of size 25, each constituting about 5 samples, are pleated using pleating means very similar to those described in the aforementioned patent No. 3461484, at the same time that a twist is applied to the pleated envelope as described in the aforementioned patent N ° 3397069. The pleated envelope is then compressed under a force of approximately 180 daN on tubular cores having a wall thickness of 0.254 mm, 0.508 mm, 0.762 mm, 1.016 mm and 1.27 mm. The core compacted envelopes are produced on a pleating machine of the floating mandrel type, as described in more detail in this specification, except during the final compression exerted

8

5

10

15

20

25

30

35

40

45

50

55

60

65

9

649,684

on the core, the core 31 being able to slide freely through the rear collar 29 (FIG. 3), which causes effective compression of the envelope simultaneously at the two ends. All tabular cores have an inside diameter of 1.30 cm and compression, after pleating, is performed on a section of compression mandrel of 1.27 cm in diameter over which the cores can slide. The moisture content of all pleated samples is approximately 16.5% by weight and a mineral oil is used as the internal lubricant (at a rate of approximately 2.17 to 3.1 mg / 100 cm2) and as an external lubricant (up to approximately 10.85 mg / 100 cm2). The amounts of lubricant are not critical, but these values represent the amounts usually used on the particular pleating machine and the particular type of casing involved.

The upper part of Table I indicates the values of the internal diameters of the cores immediately after they have been loaded or withdrawn from the mandrel, and at least 1 d and up to 20 d after this operation. The reduction in the internal diameter of the cores is due to the great expansion force exerted towards the inside of the envelope and resulting from the high compression ratios and yields. It should be noted that the degree of reduction of the opening of the core is a function of the diameter of the tube as well as the amplitude of the forces exerted inward and the creep resistance of the core ( that is to say, a large envelope requires a core whose thickness is greater than that required by a small envelope to withstand the same force exerted inwards, per unit of area). It should be noted that the relatively low creep resistance of high density polyethylene allows a 0.254 mm thick web to compress until the inside diameter of this web (12.19 mm) is effectively less than the opening of the soulless sample. The opening of the envelope is obviously larger [12.19 + 2 (0.254) = 12.698],

Table I

Inward compression force effects

Wall thickness

0.254

0.508

0.762

1.016

1,270

of the soul (mm)

trained

conical upright

conical upright

conical upright

conical upright

conical

Compression ratio of core samples

Tablet Unloaded Later

133.4

115.5 114.8

140.8 125.0 121.3

134.9 122.5 116.8

132.3 121.5 118.8

127.1

114.7

109.8

125.1 •

120.2 119.2

115.3 113.5 109.8

124.1

115.2 112.1

123.0 119.7 118.7

116.5 111.4 122.4

Useful inner diameter of the core (mm)

Unloaded Later

12.09 11.81

12.52 12.19

12.19 12.12

12.32 12.32

12.24 12.19

12.45 12.37

12.42 12.24

12.45 12.45

12.45 12 ", 32

12.52 12.50

Compression efficiency Later

0.55

0.68

0.58

0.70

0.57

0.73

0.59

0.73

0.67

0.76

Soulless samples

Soulless samples

trained

conical

trained

conical

Compression ratio in compressed state Compression ratio at unload Compression ratio later

136.5 111.7 90.1

141.5 125.4 114.7

Opening diameter, unloaded Opening diameter, later Compression efficiency, later

0.532 0.509 0.44

0.519 0.487 0.63

The lower part of table I gives data relating to a sample of envelope of the same size, namely size 25, pleated and compressed on a mandrel of 14.605 mm, but without core. Although a high compression ratio and compression efficiency are obtained with "conical" folds (114.7 and 0.63, respectively), there appears to be an excessive reduction in the size of the opening (as determined by fall adjustment) and this reduction is unacceptable from a commercial point of view. It is not appropriate to compare these data directly with those of the core article indicated in Table I, since each of the samples comprising a core is compressed on a support core having an outside diameter which varies according to of the thickness of the wall of this core. 60

Two pleat angles are used during the pleating tests shown in Table I. The term "erect" means a pleat pleat angle greater than about 15, and the term "conical" means a pleat pleat angle of approximately 45 '". The" upright "pleated samples are pleated using pleating means or rollers analogous to those described in United States Patent No. 2984574. The compression ratio in the compressed state of the sample with conical folds without core is to be compared with that of the sample without core of 63 m indicated in table II, where the envelope is unusable due to the lack of coherence.

The material used for the core during the tests indicated in Table I is high density polyethylene. For convenience, the cores are machined in thick-walled tubing and the resulting rough exterior surface significantly reduces the compression ratio that can be achieved. An examination of Table I shows that for cores made of high density polyethylene a significant deformation of the opening of the envelope appears even when the thickness of the core reaches 1.270 mm. Table I also shows that, for a constant compressive force (180 daN in this example), the final compression ratio obtained decreases in proportion to the increase in the thickness of the core (i.e. increasing the outside diameter of the core). However, the compression efficiency also increases. To maximize the compression ratio, the fit on the tamping mandrel and the compression efficiency, the core design must take into account:

a) of the creep of the core under the effect of the great forces exerted towards the inside of the envelope as well as the final opening dimension requested,

10

649,684

b) the reduction in the compression ratio which would occur if a core with an excessively thick wall were used, and c) the cost of the material of the core.

Other materials tested for the core give similar results with regard to the deformation of the core. Cores made of ABS tube, namely an acrylonitrile-butadi-ene-styrene copolymer, behave satisfactorily for wall thicknesses significantly less than those of high density polyethylene cores, but the cores in ABS are less economical .

Example 3:

The advantages offered by the high density and core cellulosic envelope, with regard to the yield and the compression ratio, are demonstrated by an experimental work consisting of pleating and compressing, at high compression ratios and yields, samples of 'cellulose envelope of size 25 (21 mm in diameter in the inflated state), without fibrous reinforcement, having a wall thickness of 0.0254 mm. The moisture content of the envelope as folded is about 16.5% by weight, and a lubricant consisting of a mineral oil is used as indicated in Example 2. The pleating means of the type used in the industry and the like described in the aforementioned patent N ° 3461484 are used to crease the envelope, while a twist is imposed on the pleated envelope, as described in the aforementioned patent N ° 3397069. Each envelope is then compressed on tubular polypropylene cores (polypropylene reinforced with 20% talc) in order to be compared to an envelope pleated by the same pleating methods, but compressed without a core. The high density envelopes on the core are produced on a pleating machine of the floating mandrel type, described in detail in the present specification, except that during the final compression carried out on the core, the core 31 to slide freely through the rear collar 29 (fig. 3), so as to effectively compress the core simultaneously by the two ends. In addition, to obtain a more uniform compression, over the entire length of the pleated envelope stick, we compress about 24 m of envelope at a time (compression in stages). Coreless samples and some of the core samples are designed to have a 12.45mm free fall test. Other core samples are designed so that the tubular core can be used as a disposable tamping mandrel. In these cases, the inside diameter of the core effectively equals the inside diameter of a tamping mandrel of 12.70 mm outside diameter, and the pleated article does not require any particular test value in free fall relative to to the tamping mandrel. For all samples, the pleated envelope is compressed so as to form a final envelope with a length of approximately 51 cm. About 10 samples of each of the core configurations and of each of the coreless configurations are prepared, consisting of envelope lengths between 48 and 68 m.

The results of this test work are collated in Table II. For soulless articles with an envelope length of 63 m and more, poor consistency leads to envelopes which break and no fall adjustment is possible after a week. For soulless articles made of envelope lengths of 58.2 to 60.5 m, forces exerted radially inwards, due to the growth of the envelope (after 1 week), reduce the size of the envelope openings pleated to such a point that they no longer meet the 12.45 mm free fall test requirement. By way of comparison, the best pleating methods available give a core-less envelope consisting of a pleated envelope 48 m long, with an average compression ratio (out of ten samples) of 94.6 and an average compression yield d 'about 0.491. A compacted pleated and compressed, high density cellulose core with a core according to the invention, designed to have a free fall test of 12.45 mm, is produced by the same pleating process. A compacted envelope is thus obtained, the internal opening of the core of which is equal to approximately 59% of the diameter of the envelope in the inflated state. This compacted envelope contains 60 m of envelope and has an average compression ratio (out of ten samples) of 116.46 and an average compression efficiency of 0.653.

(Table at the top of the next page)

5

These data also illustrate a preferred embodiment of the invention in which, on the basis of a comparison of the free fall test, the core has an internal opening dimension at least as large as that which the same envelope would have if io it was pleated and strongly compressed in the same pleating and compression conditions, without core, and at the same compression ratio. In particular, the dimension of the opening of the core of articles having an average compression ratio of 116.46 is 12.62 mm. In comparison, the dimensions of pleated, core-less pleated envelope openings, having compression ratios of 113.1 and 120.0, are 11.94 and 11.81 mm, respectively, which is significantly less the size of the comparable article comprising a core.

A second series of high density samples, comprising a core, is produced, the core of the pleated article being used as a tamping mandrel to be discarded after use, having an admissible flow rate effectively equivalent to that of a normal mandrel. 12.70 mm outside diameter packing (11.07 mm inside diameter). An article is thus obtained in which the internal opening of the core 25 is equal to approximately 51% of the diameter of the envelope in the inflated state. This article comprises 69 m of envelope having an average compression ratio (out of ten samples) of 133.4 and an average compression efficiency of 0.617.

The test was continued to determine the quality of the articles with a pleated and compressed envelope of this example 3 (both with core and without core), this quality being demonstrated by the number of pits present in the pleated envelope . Five envelopes of each type of sample were tested for pitting by filling the envelope with water and putting it under internal pressure. The results given in Table II show a general tendency to increase pitting deterioration as the total length of the shell of the coreless article increases. However, no pinholes were found in the samples with a core tested.

In summary, Example 3 shows that it is not possible to prepare a typical pleated and compressed cellulosic envelope, of small size, without core, at a compression efficiency of at least 0.5, without unacceptable reduction of the opening (diameter). On the other hand, this result is easily obtained with the envelope compac-45 ted according to the invention and, in fact, the preferred compression yield which is at least 0.6 is exceeded.

Example 4:

Another advantage of the pleated envelope with high density and core 50 according to the invention is that it reduces the tendency to deterioration of the envelope, that is to say the formation of pitting, compared to the same envelope pleated and compressed in the same conditions, but without soul. This is due to the fact that the core reduces longitudinal growth as a result of surface friction and lower compression is required to maintain a particular compression ratio compared to a pleated stick without a core. Since the formation of pits increases with compression, the compacted envelope according to the invention makes it possible to reduce or avoid the possible problem of the deterioration of the envelope.

60 In addition, the core makes it possible to maintain and fix the compression ratio in the fully compressed state and it makes it possible to raise the compression ratios even more without damage by pitting.

This compression relationship between pleated envelopes with 65 core and without core is illustrated by a series of tests in which lengths of 48 m of non-fibrous cellulosic envelope, size 25, are pleated and compressed in an equivalent manner, with and soulless, up to 38 cm in length and at an initial ratio of

11,649,684

Table II Small envelopes

Soulless

With soul

For chuck

For test

to throw away

For 12.45 mm free fall test

free fall

equivalent

12.45 mm

to a 12.70 mm chuck

Com section diameter

pressure (mm)

14.605

14.48

12.45

Diam. ext. x diam. int. of

the tubular core (mm)

-

14.48 x 12.95

12.45x11.18

Envelope length (m)

48

56.2

59.5

60.5

63

65.2

67.5

60

69

Length of the envelope. (cm)

Compressed

48.23

48.26

48.26

45.72

45.72

43.81

43.81

50.49

49.68

Dump

51.61

51.43

52.09

50.52

51.46

50.60

51.03

51.10

50.34

1 week

51.56

51.92

52.55

51.43

52.25

51.92

52.40

52.35

52.55

Rapp. compression

the envelope

Compressed

101.10

118.4

123.2

135.0

140.0

151.3

156.5

120.72

141.10

Dump

94.50

111.1

114.1

122.2

124.4

131.0

134.4

119.20

138.55

1 week

94.60

110.1

113.1

120.0

122.5

127.7

130.9

116.46

133.40

Diam. exterior of the enclosure

lopp (mm)

Compressed

N / A

N / A

N / A

N / A

N / A

N / A

N / A

24.59

25.02

Dump

24.00

24.13

24.38

24.71

24.84

25.58

25.73

24.61

24.82

1 week

23.93

23.82

24.13

24.13

24.38

24.69

24.94

24.38

24.99

Adjust. falling from envy

lopp (mm)

Dump

12.04

12.83

12.78

12.39

11.76

12.06

11.94

12.70

10.92

1 week

12.55

12.19 *

11.94 *

11.81 *

BC *

BC *

BC *

12.62

10.79

Compression efficiency

of the envelope (after

1 week)

0.491

-

-

-

-

-

-

0.653

0.617

Holes in a group of

5 samples

1

0

• 1

0

1

2

2

0

0

BC = broken envelope.

NA = no data available.

* = envelope not functional, as it does not meet the 12.45 mm free fall test requested.

pressure of 128. After unloading, the folded envelopes, with core and without core, are allowed to grow for a period of 7 d, without additional longitudinal support. At this stage, the envelope with core has a longitudinal growth of only 10.16 mm (compression ratio after growth of approximately 125), while the envelope without core has a growth of 35.5 mm (ratio 50 compression after growth of approximately 117). If the objective had been a final compression ratio of 125, a higher initial compression force would have been required in the case of the pleated, soulless stick.

The advantage of the lower tendency to deteriorate the envelope can be used in another way. If the user indicates a maximum compressive force that can be applied without causing deterioration of the envelope upon application of this force, the core article can be formed at a higher compression ratio and a yield of higher compression than the soulless article.

Example 5:

A series of tests is carried out based on the teachings of the aforementioned British patent No. 1167377, and the m results thus obtained are compared with the pleated cellulose envelope with high density and core according to the invention.

Based on the indications given in the aforementioned British patent, use is made of a polyvinyl chloride tube with an internal diameter of 40.97 mm and a core having a wall thickness of 0.254 mm, and a fibrous-reinforced cellulose envelope, of size 2.5 (about 6.1 cm in diameter in the inflated state) is pleated by a pleating device similar to that described in the aforementioned patent No. 3461484, then compressed to a length of 30.5 cm. The tube with an internal diameter of 40.97 mm and the fibrous envelope of size 2.5 are chosen for this test, because the tube is the smallest polyvinyl chloride tube available at the time of the test. The samples of compacted envelopes are prepared on a pleating machine of the floating mandrel type, as described in more detail above, the pleated envelope being transferred, after pleating, onto a core arranged coaxially with the pleating mandrel, on a section of reduced diameter of the latter, then finally compressed as described in Example 1, and discharged. These samples have a moisture content, in the pleated state, of about 20% and a lubricant consisting of mineral oil is used inside (at a rate of about 31 mg / 100 cm2) and inside. outdoor (up to 16.5 mg / 100 cm2). The envelope is used in three different lengths: 22.5, 30 and 37.5 m. Based on the compacted envelope, different compression ratios are obtained. The articles obtained are then the subject of a measurement intended to determine the internal diameter of the core by the method of the free fall test described above. In the case of the sample with a compression ratio of 75,

649,684

12

the dimension of the test in free fall is 40.39 mm, which indicates pressure, but without core, and at the same compression ratio in the state a reduction in the dimension of the diameter of the core of 0.584 mm. compressed. For example, with the envelope of size 2.5, the dimension In the case of the sample having a compression ratio of 100, average of the opening of the envelope without core, which is the dimension of the test in free fall is 39.12 mm, indicating a 39.12 mm, is slightly less than the average dimension of the ou-decrease in the diameter of the core by 1.854 mm. In the case of 5 inner lining of the envelope with core, which is 39.29 mm,

the sample having a compression ratio of 125, the dimension even so the final compression ratio of this last article of the test in free fall is less than 38.10 mm. However, the key soul is significantly higher (138 instead of 114). Simi-deforms at one end immediately after the envelope has been laired, with the envelope of size 4, the average size of the open-compressed and discharged from the mandrel. This shows the closability of the coreless envelope, which is 39.29 mm, is substantially holding the compacted, pleated cellulosic envelope with high density and "> less than the average dimension of the opening of the core envelope according to the invention by following the indications given in the bre- with core, even if the final compression ratio of this British vet mentioned above, the latter is higher (138 instead of 128).

The sample of 22.5 m in length still adjusts on the man- A comparison of the results of the tests described above with drin of stuffing of 39.52 mm of outside diameter, but makes it- those obtained in the Example 5 shows that the British compression patent is only 0.43. The 30 m samples of 15 No. 1167377 cited above neither indicate nor even suggest the use of a length present such a significant reduction in their opening soul in a way allowing the simultaneous obtaining of the three ca-they cannot be adjusted on the chuck. The core of the sample of advantageous characteristics of the cellulosic envelope and core according to 37.5 mm in length completely closes. the invention: a high compression ratio, a high compression efficiency and a limited deformation-reduction of the opening of Example 6: 20 the core.

The fibrous cellulosic envelopes of dimensions similar to (Table at the top of the next page)

those of the sample of the type described in Example 5, prepared in Example 7.

in accordance with the aforementioned British patent No. 1,167,377, a series of tests are carried out using a pleating machine in accordance with the invention and compared with samples of the type described in the aforementioned patent No. 3461484, at the same time core in order to determine the compressibility limits as established that a twist is applied to the pleated envelope, as described by the deterioration of the envelope. Envelopes of size 2.5 (in- in the aforementioned patent No. 3397069. During these tests, about 6.1 cm in diameter are prepared in the inflated state) and of size 4 (about 7.1 cm of the pleated cellulosic envelopes of small diameter, high den-diameter in inflated state) are pleated by a seated pleating machine, with core, using, for the souls, different materials. Analogous to that described in the aforementioned patent N ° 3461484. Content core articles are produced on a moisture-type pleating machine of samples of size 2.5 and size 4 envelopes, 30 floating mandrel, as described in detail herein, in the pleated state , is around 20%. A mineral oil is used except that during the final compression carried out on the core, one as lubricant in the following way: allows the core 31 to slide freely through the rear collar 29

size 2.5: approximately 31 mg / 100 cm2 (interior) and approximately (fig. 3), which allows effective compression of the envelope

15.5 mg / 100 cm2 (exterior); tanely by its two ends. The materials used for size 4: approximately 26 mg / 100 cm2 (interior) and approximately 35 cores during these tests are polypropylene (reinforced with

14 mg / 100 cm2 (exterior). 20% talc), polystyrene and polyethylene to

The core envelopes are compressed on high density chloride cores, each core having an external diameter of 12.70 mm of polyvinyl, in a manner identical to that used for the envelopes and a wall thickness of 0.635 mm. The envelope used is a loppers from Example 5. The samples are compressed up to a size 25 cellulose envelope (without fibrous support), and each length of 30.5 cm, at a compression ratio of 150, which re-envelops 60 m in length. On all the samples, the content of the highest compression ratio obtainable, humidity in the pleated state is approximately 16.5% and oil mined - without deterioration of the size envelope. 2.5. All line samples are used as a lubricant, inside (about 2.2 to are made so as to fit on a 3.1 mg / 100 cm2 stuffing mandrel) and outside (up to 11 mg / 100 cm2).

39.52 cm in diameter. The cores used have an outer diameter The results of the tests, grouped in Table IV, show 43.51 mm and a wall thickness of 1.27 mm. The samples 45 which the relatively lower coefficient of friction of the core in core are retained so as not to be able to expand longitudi- high density polyethylene makes it possible to compress the envelope ply-nally by means of a tenon, and the coreless samples are resided at a compression ratio considerably higher than that obtained (only in part) by being housed in a cardboard box. held with the other constituent materials of souls.

The results of the tests are given in Table III. The envelopes- According to the work of the tests described in Examples 2 to 7, there are loppes of size 2.5, comprising a core, have a dimension 50 can see that the design of a core for the envelope according to the final opening of the core slightly too small to be able to maintain is based on the properties of the material constituting the core, to be adjusted on the mandrel, but nevertheless greater than that of such as the mechanical resistance, the modulus of elasticity and the resis-opening of articles without a core, even when articles with a core tend to creep. These properties determine the thickness required to present a compression ratio of approximately 138, while giving them to the wall of the core to resist the forces of expansion envelopes without a core have a compression ratio which is not that 55 being exerted towards the inside of the envelope and tending to deform and re-about 114. In practice, a compression ratio slightly reduces the dimension of the opening of the core. The coefficient of friction-lower would have allowed the core to adjust properly to the ment of the material of the core determines the amplitude of the mandrel forces. The articles of size 4, comprising a core, are function- compression longitudinal which it is necessary to exert to compress the en-nels (with regard to the compression ratio) after 15 d to a veloppe in order to reach ratios of compression extremely compression ratio of 138.46. Articles of size 4 without soul 60 high.

show a reduction in opening making them unsuitable for use. It appears that many factors are to be considered in the reading after 15 d, with a measured compression ratio of 128.48. choice of the material of the core, these factors including the coefficient

Example 6 also illustrates, in the case of reinforcements of friction, the creep resistance, the modulus of elasticity, the availability of fiber and core, a preferred embodiment of the invention nibility in the form extruded, cost, formability, in which, based on a comparison of free fall tests, "weldability and availability in enhanced form." The fina-core material has an interior opening dimension that is also at least also chosen may differ according to different applications. Po-large as that which would have the same pleated fibrous envelope and high-density polyethylene and polyvinyl chloride are suitable compressed under the same pleating conditions and as large envelopes according to the invention.

13

649,684

Table III

Fibrous envelope (for 39.52 mm diameter tamping mandrel)

Envelope size 2.5 (6.1 cm in diameter when inflated)

Envelope size 4 (7.1 cm in diameter when inflated)

with soul without soul with soul without soul

Outside diameter x inside diameter of the tubular core (mm)

43.51 x 40.97

-

43.51 x 40.97

-

Envelope length (m)

45

45

45

45

Number of samples

9

17

9

17

Envelope compression ratio (average) 2 days 15 days

138.46 138.46

114.28 113.92

138.46 138.46

130.91 128.48

Envelope free fall test (average mm) 2 days 15 days

39.73 39.29

39.42 39.12

40.21 40.18

39.37 39.29

Table IV Small envelope

Tubular core ... 12.70 mm outside diameter x 11.43 mm inside diameter (for use as tamping mandrel)

Envelope ... size 25; cellulose; 60 m in length

Soul material

Polypropylene reinforced with talc

Polystyrene

High density polyethylene

Compression ratio of the compacted envelope

Tablet

149.3

148.0

174.0

Discharged

139.5

142.0

158.7

1 week

137.1

140.4

150.9

Free fall test of the compacted envelope

Unloaded (mm)

10.67

10.92

10.92

1 week (mm)

10.67

10.92

10.92

Example 8: 50

Another series of tests is carried out on envelopes with high density and core, similar to those described in Example 3 and grouped in Table II. The only difference is that, instead of carrying out a final compression by the two ends, the compression is carried out by one end, in the same way as that used for the pleated and soulless envelopes, given in table II, and the pleated and compressed envelopes are transferred to the core.

The results of these tests on high density and core envelopes, comprising a non-fibrous cellulosic envelope of size 25, are grouped in Table V and they are to be compared with the data given on a coreless envelope, indicated in Table II. . The high density and core envelope, intended to present a drop test of 12.45 mm, has an average compression ratio (on 15 samples) of 129.2 and an average compression efficiency of 0.67. The high density and core envelope, intended to serve as a tamping mandrel with an external diameter of 12.70 mm, has an average compression ratio (on 15 samples) of 140.1 and an average compression yield of 0, 64.

In summary, while Example 3 shows that it is not possible to prepare a typical pleated and compressed cellulosic shell, of small dimensions and without core, having a compression efficiency of at least 0.5, by proceeding at compression by a single end, without showing a large and unacceptable reduction in the opening, this result is easily obtained with the compacted envelope according to the invention and, in fact, the preferred compression yield, which is at least 0.6, is exceeded. No equipment was available for compression by the two ends of compacted, coreless envelopes.

(Table on next page)

Example 9:

Another series of tests is carried out, tests in which a size 25 cellulose envelope (without fibrous reinforcement) is used for the preparation of compacted pleated envelopes of high density, without core and with core, at various compression ratios, these envelopes being examined with regard to the free fall test (fig. 8) and consistency (fig. 9). All compacted envelopes are prepared from 48 m of envelope and the envelopes

649 684 14

Table V Small envelopes pleated and compressed have different lengths which depend on the compression ratio. The moisture content of the envelope as folded is about 16.5% by weight, and mineral oil is used as the internal lubricant (about 2.2 to 3.1 mg / 100 cm2 of internal surface) and as an external lubricant (up to approximately 11 mg / 100 cm2 of external surface) during pleating.

Pleating means of the type described in the aforementioned patent No. 3461484 are used to pleat the envelope, while a twist is applied to the pleated envelope, as described in the aforementioned patent No. 3397069. The envelope is fully compressed in the conventional manner, from one end, over the compression section of the mandrel of a pleating machine of the floating mandrel type, as shown generally in FIG. 3. After compression, the folded envelope is discharged directly onto a tubular core. The latter is made of polyvinyl chloride and has an outside diameter of 14.22 mm and an inside diameter of 12.85 mm. During a first group of tests, a mandrel having a compression section of 14.60 mm in diameter is used. For the other group of tests, the diameter of the compression section of the mandrel is 15.11 mm.

The free fall test and the consistency of pleated articles with high density, without core and with core, are measured, as well as the compression ratio, 7 after unloading, and the data thus obtained are indicated according to the ratio of compression in fig. 8 and 9.

Fig. 8 shows that the free fall test for pleated and compressed envelopes without a core (formed on mandrel compression sections of 14.60 mm, as indicated by curve A, and 15.11 mm, as indicated by curve B) decreases continuously when the compression ratio increases in the range from 95 to 120, the compression ratio being indicated on the abscissa and the test rod diameter in free fall being indicated on the ordinate, in millimeters. Since the minimum acceptable size of the opening of a size 25 envelope (diameter of 21 mm when inflated) is 12.45 mm (horizontal dotted line), the maximum compression ratio that can be can use with the chuck

14.60 mm is approximately 99. It should be noted that by using a larger mandrel (15.11 mm), the minimum opening dimension can be achieved with a slightly higher compression ratio (approximately 103) , but this increases the risk of deterioration of the envelope by the formation of holes. In addition, when using increasingly large mandrel sections, greater than 14.60 mm for a size 25 envelope, the risk of blockage on the mandrel, production interruption and percentage is gradually increased. of waste. In other words, it is recognized by those skilled in the art that, in the field of pleating, the optimal setting to allow pleating without problems of an envelope of a particular size is that using the smallest mandrel giving the opening of desired dimension.

In comparison with the limitation, indicated above, of the compression ratio of a pleated envelope without a core, due to the dimension requested for the opening (this limiting ratio being 99), FIG. 8 shows that for an envelope of size 25, comprising a core, the so test in free fall is constant when the compression ratio rises to a value of 124 and that the same mandrel of 14.60 is used. mm (curve A). If the compression ratio is further increased, the interior opening of the core begins to deform inward under the effect of the excessive force exerted inwardly by the pleated envelope. Consequently, the value 124 represents a practical upper limit of the compression ratio for this particular embodiment in which the diameter of the envelope in the inflated state is approximately 21 mm, the compression ratio is greater than 100 and the drop test rod diameter is at least 12.45 mm 60.

It has been unexpectedly discovered that when the compression ratio of pleated envelopes without a core, made up of a cellulosic envelope (with a fibrous reinforcement) is in the range of the compression ratio that can be obtained with the envelope at 65 core according to the invention, the coherence of the envelopes without core gradually decreases when the compression ratio increases. This is contrary to expectations, because at lower compression ratios such as those used in industrial practice, it is known that

For a chuck

For the test

to throw away

free fall

equivalent

12.45 mm

to a 12.70 mm chuck

Compression section diameter (mm)

14.60

13.00

Outside diameter x inside diameter of the tubular core (mm)

14.22 x 12.95

12.70x11.43

Envelope length (m)

60

60

Compacted envelope length (mm)

Tablet

432

381

Discharged

473

434

1 week

472

435

Compression ratio of the compacted envelope

Tablet

141.2

160.0

Discharged

128.8

140.3

1 week

129.2

140.1

Outer diameter of the compacted envelope (mm)

Tablet

N / A

N / A

Discharged

24.97

23.85

1 week

24.87

25.07

Free fall test of the compacted envelope (mm)

Discharged

12.65

10.92

1 week

12.55

10.74

Compression efficiency of the compacted envelope

(after 1 week)

0.67

0.64

NA = no data available

35

40

15

649,684

the consistency of the same coreless envelope gradually increases with the compression ratio.

This unexpected discovery, according to which the coherence decreases when the compression ratio increases in the case of pleated cellulosic envelopes without a core, is illustrated in FIG. 9 for an envelope of size 25, the consistency being given on the ordinate and the compression ratio on the abscissa. It should be noted that for a 14.60 mm mandrel, the consistency decreases almost constantly and drops rapidly from around 56 N / cm (compression ratio of 100) to a value at least as low as 17 (ratio of compression 125). The last compression ratio is only slightly higher than the minimum commercially acceptable consistency, which is 14 N / cm, and it is significantly less than the preferred consistency, which is 28 N / cm. On the other hand, with the pleated envelope with high density and core according to the invention, no limitation is imposed on the consistency, since the pleated and compressed envelope is supported by the outer wall of the core with which it is in functional contact.

It is believed, without fully understanding it, that the aforementioned relationship between coherence and compression ratio, in the case of pleated and soulless cellulose envelopes, depends on the degree of compression of the folds of the envelope. One possible explanation is that, in the lower range of the compression ratios, the compression of the folds generates a narrower interlocking of the cones into each other, which increases the contact surface between the adjacent cones and, therefore, the consistency . However, when the compression is further increased to achieve even higher compression ratios, the strong compression can break the interlocking of the cones, which reduces consistency. This possible explanation is in accordance with the experimental observation that, when the compression ratio of pleated cellulosic envelopes without a core is gradually increased, the consistency rises initially to a maximum value, then gradually decreases. The possible explanation is also consistent with the experimental observation that larger envelopes have higher coherences, at higher compression ratios, than smaller envelopes (fig. 11 described below) . This may be due to the larger areas through which adjacent cones are in contact with each other in envelopes of relatively large dimensions.

The data concerning the envelope of size 25, 48 m in length, indicated in figs. 8 and 9 also support the main criteria requested according to the invention, namely that the core article must have a compression efficiency which is not less than 0.50, and that its compression ratio and its compression efficiency are respectively greater than those of the same envelope length, pleated and strongly compressed under the same pleating and compression conditions, but without a core. In particular, the characteristics presented by the samples after 7d:

a) the core article having the highest compression ratio which satisfies the minimum free fall test of 12.45 mm requested,

b) the soulless article which is pleated and compressed under the same conditions as sample a, and c) the soulless article having the highest compression ratio, which also satisfies the same minimum free fall test requested , are as follows:

Sample

Free fall test

Compression ratio

Compression efficiency a) article with core

12.70 mm

124

0.66

b) soulless item

11.68mm

116

0.54

c) soulless item

12.70 mm

98

0.44

These data show that the free fall test, the compression ratio and the compression efficiency of sample a are all higher than those of sample b. In addition, sample b does not constitute an acceptable product, since the envelope shows growth towards the inside of the opening, this growth being such that the envelope of sample b does not satisfy the fit. in minimum fall requested. Knowing this defect in the opening of the sample b, the article without core c constitutes the best pleated envelope without core which could perform the same function as the article with core a. On this basis, the sample a represents an improvement of 26% with regard to the compression ratio and 50% with regard to the compression efficiency.

Example 10:

Another series of tests, similar to the tests of Example 9 relating to a size 25 envelope, is carried out with three different sizes (smaller and larger) of cellulose envelopes, without fibrous reinforcement. These envelopes are of size 17 (diameter of 15.5 mm in the inflated state and wall thickness of 0.025 mm), of size 21 (diameter of 18.5 mm in the inflated state and wall thickness of 0.025 mm) and size 27 (diameter 22.6 mm when inflated and wall thickness 0.025 mm). A difference compared to the tests of Example 9 is that, instead of using the same length of envelope and preparing different lengths of the envelopes according to the compression ratio, in these tests, the length of the envelope and the envelopes are compressed so as to have substantially the same final length for each envelope size (7 d after unloading). In the case of the size 17 envelope, the final length of the stick is approximately 40.5 cm, while this length is approximately 52.1 cm in the case of the sizes 21 and 27 envelopes.

Another difference between these tests and those of Example 9 is that no core articles are prepared from a size 17, size 21 or size 27 envelope. However, in another test similar, a high density pleated cellulosic and core envelope is prepared from a size 21 envelope and this article has the following characteristics: a compression ratio of 119.8; a compression efficiency of 0.66, and a dimension of the interior opening of the core of 10.72 mm. Consequently, this pleated core casing is suitable for use on the tamping mandrel provided, the outside diameter of which is 10.31 mm. As shown by the curves corresponding to the pleated stick without a core for the size 21 envelope, in FIGS. 10 and 11 (described below), these remarkable characteristics cannot even be approached by the pleated, soulless envelope of the prior art.

Except for the aforementioned differences, high density pleated and soulless pleated sticks are prepared from envelopes of sizes 17, 21 and 27, in the same manner as for high density pleated and soulless envelopes of size 25. After unloading and storage for 7 d without longitudinal restraint, the envelopes obtained are subjected to free fall and consistency test measures. The data are summarized by the curves in fig. 10 (fall adjustment) and fig. 11 (consistency), depending on the compression ratio.

An examination of fig. 10 shows that, as for the envelope of size 25 (FIG. 8), the tests in free fall of the three sizes of envelopes decrease progressively and in a substantially constant manner when the compression ratio increases, the test in free fall being indicated on the ordinate, in millimeters, and the compression ratio on the abscissa. In the case of the size 17 envelope, the minimum acceptable fall adjustment is 9.14 mm (indicated by the dotted horizontal line), so that from the point of view of the free fall test, the maximum ratio of compression which can be achieved with the pleated envelope without core of the prior art is approximately 80. Likewise, with the envelope of size 21 the minimum acceptable free fall test is 10.41 mm, of so that the maximum compression ratio that can be obtained with the pleated, soulless envelope of the prior art is approximately 98. Finally, with the envelope of size 27, the minimum acceptable free fall test is 13.46 mm, so that the maximum compression ratio

5

10

15

20

25

30

35

40

45

50

55

60

65

649,684

16

achievable with the pleated, soulless envelope of the prior art is 130.

If we now consider the curves giving coherence as a function of the compression ratio, in FIG. 11, it can be seen that all these curves show the unexpected relationship, described above, according to which the coherence decreases when the compression ratio increases in the upper range of the compression ratios for each envelope size. For size 17, the consistency is weak over the entire range tested for compression ratios 60-125, knowing the minimum acceptable value of 14 N / cm (horizontal dotted line). In the case of the pleated, soulless envelope of size 17, the maximum compression ratio that can be achieved, taking into account the consistency, is also around 80. For size 21, the consistency is also low over the entire tested range of compression ratios of 70-120, and based on the minimum acceptable value of coherence which is 14 N / cm, the maximum compression ratio that can be achieved, taking into account the coherence, is d 'about 102.

In the case of the pleated, soulless envelope of size 27, the full range, mentioned above, of relationship between the coherence and the increase in the compression ratio is illustrated. In other words, for compression ratios up to about 120, the consistency increases as the compression ratio increases. However, beyond the compression ratios of approximately 122, the coherence decreases at an approximately constant and relatively accentuated rate.

Figs. 10 and 11 show that the requested free fall test and the coherence required impose significant restrictions on the use of high compression ratios with pleated, coreless envelopes of the prior art, formed from cellulosic envelopes of sizes 17, 21 and 27. In each case, the envelope according to the invention makes it possible to achieve substantially higher compression ratios with an acceptable opening dimension of the core and a higher coherence, and also with a lower tendency to the deterioration of the envelope by the formation of pitting. In particular, a pleated envelope of size 17, with core, according to the invention, consisting of an envelope having a diameter of approximately 15.5 mm and having a free fall test of at least 9.14 mm, has preferably a compression ratio greater than 80. In addition, a pleated envelope of size 21, with core, according to the invention, comprising an envelope of approximately 18.54 mm in diameter in the inflated state and having a test in free fall of at least 10.41 mm, preferably has a compression ratio greater than 98. Finally, a pleated envelope of size 27, with core, according to the invention, comprising an envelope having a diameter of approximately 22, 6 mm in the inflated state and having a free fall test of at least 13.46 mm, preferably has a compression ratio greater than 130.

Example 11:

The advantages of compression ratio and performance of the embodiments of the invention, constituted by envelopes of the fibrous reinforcement type, of intermediate dimensions, are demonstrated during another series of tests relating to samples with core. and soulless. Envelopes of sizes 43, 47 and 60, with flat widths of 58.5 to 83.8 mm, are used for the preparation of pleated and compressed envelopes, with and without core, intended to fit on a tamping mandrel with an outside diameter of 27.25 ± 0.127 mm. Envelopes of sizes 70, 80 and 100, having flat widths of 95.25 to 139.7 mm, are used for the preparation of pleated and compressed envelopes, with and without core, intended to fit on a tamping mandrel with an outside diameter of 39.52 ± 0.127 mm. The wall thickness of the envelope of each of the samples is approximately 0.0787 mm. The moisture content of the envelope as folded is approximately 20%, and a mineral oil is used as an internal lubricant (at a rate of approximately 6.8 mg / 100 cm2 of internal surface) and as an external lubricant (up to '' at approximately 4.6 mg / 100 cm2 of external surface). The inflated diameters of these fiber-reinforced envelopes are as follows:

Cut

Diameter when inflated (mm)

43

37.59

47

40.33

60

52.40

70

60.63

80

70.41

100

88.52

During these tests, envelopes of different lengths are compressed in order to obtain compacted envelopes having substantially the same length, at all compression ratios, for a particular envelope size. These lengths presented by the compressed envelopes are as follows: 26.7 cm for size 43; 25.4 cm for size 47; 22.9 cm for size 60; and 30.5 cm for sizes 70, 80 and 100.

All the samples of compacted envelopes are prepared on a pleating machine of the floating mandrel type as described above. The pleating means are of the type used in industry and similar to those described in the aforementioned patent No. 3461484. Multiple samples are prepared under each of the conditions. The coreless samples are pleated and compressed from one end on the mandrel to the maximum allowable compression ratio without deterioration of the envelope and at lower compression ratios. The maximum compression ratio "without deterioration" is determined by tests aimed at detecting the presence of holes and consisting in filling the envelope with water and applying internal pressure to it. When deterioration is detected, other samples are prepared at slightly lower compression ratios and are subjected to the water test for pitting detection, as indicated. The cycle is repeated until a compression ratio is obtained giving intact envelopes, and this ratio constitutes the maximum compression ratio.

After compression on the mandrel, the coreless samples, sizes 43, 47 and 60, are transferred from the pleating machine onto a small diameter plastic tube (27.9 mm) for handling and, after approximately 1 hour, they are removed from the tubes and introduced into a net. The latter is tied at both ends and the wrapping net, thus tied at the ends, constitutes the industrial practice used to facilitate handling. This arrangement gives a slight restraint opposing longitudinal growth. The coreless samples, sizes 70, 80 and 100, are transferred directly from the pleating machine into a polyvinyl chloride film which envelops them and which exerts very limited extreme restraint. This operation also constitutes a commercial practice intended to facilitate handling.

The cores are made of rigid polyvinyl chloride. In the case of envelope sizes 43, 47 and 60, the outside diameter of the core is 31.24 mm and the thickness of the wall of the core is 1.27 mm. In the case of envelopes of sizes 70, 80 and 100, the core has an outside diameter of 43.51 mm and a wall thickness of 1.27 mm also.

After pleating, the samples to receive a core are moved longitudinally from the mandrel onto cores which are arranged coaxially with the pleating mandrel, around a section of reduced diameter of the mandrel, as described above and illustrated in FIG. 3. The pleated envelope is then compressed on the core, by one end, to the desired compression ratio, then it is discharged. Core samples are compressed to compression ratios equivalent to those used for core samples.

After unloading, the pleated core casing receives means equivalent to the holding discs 35, mounted on the core and to the

5

10

15

20

25

30

35

40

45

50

55

60

65

17

649684

flange 39 (as shown in fig. 6), placed at opposite ends of the pleated envelope to maintain the length unloaded during the storage period of 7 d. This extreme degree of restraint in the longitudinal direction is not ensured in the case of envelopes without a core, since the latter may then deform or grow inwards sufficiently so that they cannot be adjusted to the desired tamping mandrel. . Consequently, the net and the wrapping plastic film used with the coreless envelopes do not provide significant longitudinal retention.

The lengths of the envelopes are measured before unloading, both in the case of samples without a core and in that of samples with a core, and they are again measured after the storage period of 7 d. The results of these measurements are given in FIG. 12 for the fiber-reinforced envelopes of sizes 43, 47 and 60, and in FIG. 13 for fibrous envelopes of sizes 70, 80 and 100, with compression ratios given as a function of the flat width of the envelope, the compression ratios being indicated on the ordinate and the flat width of the envelope being given on the x-axis, as well as the size of the envelope.

In fig. 12 and 13, the lower curve A represents the pleated and compressed envelope, without a core, after 7 d of storage. The middle curve B represents the pleated and compressed envelope, with core, also after 7 d of storage, and the upper curve C (in dotted lines) represents the pleated and compressed envelope, with core, immediately after compression. This last curve is indicated because it represents a state which it is possible to obtain with the invention, but which cannot be obtained with a pleated and soulless envelope of the prior art. In other words, by "blocking" the opposite ends of the envelope with core after compression, but before unloading, for example by means of extreme longitudinal retaining elements, the initial (and highest) compression ratio can be maintained without losing other essential characteristics of the stick. For example, the reduction in the size of the opening is minimal, since the core prevents the compressed envelope from growing radially inward. However, if extreme longitudinal retaining elements were used with a coreless envelope, immediately after unloading, the initial compression ratio, which is the highest, would be retained, but additional growth would occur inward. of the opening, this growth exceeding that occurring in the absence of any extreme longitudinal restraint. Since the user employs the smallest possible pleating mandrel for optimal results (for the reasons stated above) in all likelihood, the additional internal radial growth would result in an opening whose size would be too small to allow an adjustment on the planned tamping mandrel.

More particularly, fig. 12 shows that, if we base ourselves on a comparison of the values of the compression ratios after 7 d for an envelope with fibrous reinforcement of size between 43 and 60, without core and with core (the two lower curves), the smallest improvement is obtained with the envelope of size 43 and, in this case, the difference is approximately 78 minus 60, i.e. an increase in the compression ratio of approximately 30% when using the envelope with soul. The greatest improvement is obtained with the size 60 casing and, in this case, the difference is 129 minus 79, which is approximately a 63% improvement in the compression ratio using the casing with core. The theoretical maximum improvement, based on the comparison of the compression ratio after 7 d of a coreless envelope (lowest curve) with the highest initial compression ratio (curve in dotted lines, at the upper part), is significantly larger. For example, with a size 43 envelope, the difference is 97 minus 60, which is 62% higher compression ratio, and with a size 60 envelope, the difference is 146 minus 79, or about 85%.

A comparison of the compression yields and the compression ratios for the pleated fibrous envelopes, without core and with core, of sizes 43, 47 and 60, as described in example 11, is established as follows:

Envelope size

Compression efficiency (and compression ratio)

Soulless (7d)

With soul (7 d)

With soul (initial)

43

0.54 (60)

0.74 (78)

0.78 (82)

47

0.53 (66)

0.76 (95)

0.81 (102)

60

0.45 (79)

0.75 (130)

0.85 (147)

Fig. 13 shows that, based on a comparison of the values of the compression ratios after 7 d for a fiber reinforced envelope, of size 70-100, without core and with core, the improvement in the compression ratio is less than that obtained with the envelope of size 43-60, but it remains significant. The smallest improvement is obtained with the envelope of size 80 and, in this case, the difference is 166 minus 154, or approximately 8%. The theoretical maximum improvement, based on a comparison of the compression ratio, after 7 d, of the coreless envelope with the highest initial compression ratio for the envelope of size 80, is 180 less 154, or approximately 17%.

A comparison of the compression yields and the compression ratios for the pleated fibrous envelopes, without core and with core, of sizes 70, 80 and 100, as described in example 11, is established as follows:

Envelope size

Compression efficiency (and compression ratio)

Soulless (7 d)

With soul (7 d)

With soul (initial)

70

0.66 (129)

0.77 (141)

0.82 (150)

80

0.63 (154)

0.71 (166)

0.77 (180)

100

0.50 (167)

0.59 (187)

0.70 (220)

While consistency is as important with fiber-reinforced cellulosic envelopes, it does not cause as serious problems as those encountered with small, unreinforced cellulosic envelopes. This is partly due to the fact that the former are, by their nature, more resistant due to the presence of the fiber reinforcement, but also to the differences presented by the tamping device used for each of these envelopes.

Cellulose envelopes of small diameter are generally packed using a high-speed, fully automated machine, in which the next envelope to be used is automatically advanced to the tamping position when the previous envelope is exhausted. Poor consistency can cause the envelopes to rupture, which can cause the envelope to rupture or tear during insertion or rotation of the automated tamping mandrel. In this case, a large amount of food emulsion spreads around the machine before it can be stopped, and it takes a long time to clean and remove the broken envelope.

On the other hand, with large diameter fibrous envelopes, the machine speed is usually lower and the next envelope is positioned manually in order to be used by the operator. In the event of the envelope breaking (which is less likely due to the presence of the fibrous reinforcement), the machine can be stopped before a significant quantity of food product has passed, and the stopping time is more short.

5

10

15

20

25

30

35

40

45

50

55

60

65

R

5 sheets of drawings

Claims (26)

649684 1. Compacted envelope for food products, characterized in that it comprises a tubular core (31) and a humidified cellulosic food envelope (17) having a moisture content of at least 13% of its total weight, this envelope being pleated and compressed on the core and thus attached to it with a compression efficiency not falling below 0.50, the ratio and the compression efficiency also being respectively greater than those of the same pleated and compressed envelope, in the same pleating and compression conditions, but without the core, so as to generate an expansion force towards the inside of the envelope, the core being rigid enough to resist deformation and reduction in size of its opening under the effect of the force exerted towards the inside of the envelope. 2. Compacted envelope according to claim 1, characterized in that the compression efficiency is not less than 0.60. 2 3 649,684 pleated and compressed velvet to pass it from the second end of the mandrel onto the outer surface of the core, thereby generating the force exerted towards the inside of the envelope. 3. Compacted envelope according to claim 1, characterized in that the envelope contains a fibrous reinforcement and has a moisture content of 16 to 35% of the total weight of the envelope. 4. Compacted envelope according to claim 1, characterized in that the envelope has, in the inflated state, a diameter between 3.8 and 9.9 cm, in that the outside diameter of the tubular core is included between 2.54 and 5.08 cm, and in that the compression ratio of the non-pleated length to the pleated length of the envelope is between 50 and 360, the tubular core having a wall thickness of between 0 , 10 and 0.15 cm. 5. Compacted envelope according to claim 1, characterized in that the diameter of the envelope in the inflated state is less than 3.6 cm and the moisture content of the envelope is between 14 and 18% of the total weight of the envelope. 6. Compacted envelope according to claim 1, characterized in that, on the basis of a comparison according to the free fall test on rod, the core has an internal opening whose dimension is at least as large as that of the interior opening that the same envelope would have if it were pleated and compressed, under the same pleating and compression conditions, without the core, the envelope being an unreinforced cellulosic envelope having a diameter in the inflated state of less than 40 mm , the compression ratio being at least 100. 7. Compacted envelope according to claim 1, characterized in that the diameter of the envelope in the inflated state is between 10.2 and 13.44 cm, in that the outside diameter of the tubular core is between 7.6 and 12.7 cm and in that the compression ratio of the length of the non-pleated envelope to the length of pleated envelope is between 100 and 190, the tubular core having a wall thickness of between 0.127 and 0.19 cm. 8. Compacted envelope according to claim 1, characterized in that the thickness of the wall of the tubular core is at least 0.05 cm. 9. Compacted envelope according to claim 1, characterized in that the tubular core consists of high density polyethylene or polyvinyl chloride. 10 10. Compacted envelope according to claim 1, characterized in that the compression ratio is not less than 70. 11. Compacted envelope according to claim 10, characterized in that the compression efficiency is not less than 0.60. 12. Compacted envelope according to claim 1, characterized in that the diameter of the envelope in the inflated state is between 6.6 and 10 cm, in that the outside diameter of the tubular core is between 5 and 8 cm and in that the compression ratio of the non-pleated length to the pleated length of the envelope is between 100 and 200, the tubular core having a wall thickness between 1.0 and 2.0 mm. 13. Compacted envelope according to claim 1, characterized in that the envelope is an unreinforced cellulosic envelope, having a diameter, in the inflated state, comprised of 12.70 and 38.10 mm, having an internal diameter of aperture which is at least 40% the diameter of the envelope in the inflated state, and a core having a thickness of between 0.25 and 1.27 mm, the compression efficiency being at least 0.60. 14. Compacted envelope according to claim 13, characterized in that the compression ratio is at least 100. 15 15. Compacted envelope according to one of claims 13 or 14, characterized in that the internal diameter of the opening of the core is equal to at least 50% of the diameter of the envelope in the inflated state. 16. Compacted envelope according to claim 13, characterized in that the compression ratio is at least 120. 17. Compacted envelope according to claim 13, characterized in that the diameter of the envelope in the inflated state is approximately 15.5 mm, the compression ratio is greater than 80 and the rod diameter in the test free fall is at least 9.14 mm, or in that the diameter of the envelope in the inflated state is approximately 18. A method of manufacturing the compacted envelope according to claim 1, characterized in that it consists in using a cellulosic food envelope (17) having a moisture content of at least 13% of the total weight of the envelope, sliding the inner circumferential surface of the cellulosic food wrap over a first end of a mandrel (13) having a reduced diameter at its second end, pleating the cellulosic food wrap over the mandrel, using a hollow core ( 31) arranged coaxially and contiguously to the extreme section of reduced diameter of the mandrel, this core being sufficiently rigid to resist deformation and the reduction in the size of its opening under the effect of a force exerted towards the inside of the envelope as a result of the compression of this envelope, to move the pleated envelope linearly on the mandrel to pass it over the external surface of the core arranged coaxially, and to comp rhyme the pleated envelope on the core, so as to generate the force exerted towards the inside of the envelope. 18.5 mm, the compression ratio is greater than 98 and the rod diameter in the free fall test is at least 10.41 mm, or in that the envelope diameter in the inflated state is d '' about 21.1 mm, the compression ratio is greater than 100 and the rod diameter in the drop test is at least 12.45 mm, or in that the diameter of the envelope in the state swollen is about 19. The method of claim 18, characterized in that the compression efficiency is not less than 0.50. 20 20. The method of claim 18, characterized in that the compression ratio is at least 70. 21. The method of claim 20, characterized in that the compression efficiency is not less than 0.60. 22. The method of claim 21, characterized in that the compression ratio is at least 100, the food envelope being a cellulosic envelope without fibrous reinforcement, and the internal diameter of the opening of the core being equal to at least 50% of the diameter of the envelope in the inflated state. 22.6 mm, the compression ratio is greater than 130 and the rod diameter in the drop test is at least 13.46 mm. 23. The method of claim 22, characterized in that the compression ratio is at least 120, the food envelope being a cellulosic envelope without fibrous reinforcement, and the internal diameter of the opening of the core being equal to at least 40% of the diameter of the envelope in the inflated state. 24. A method of manufacturing the compacted envelope according to claim 1, characterized in that it consists in using a cellulosic food envelope (17) having a moisture content of at least 13% of the total weight of the envelope, sliding the inner circumferential surface of the cellulosic food wrap over a first end of a mandrel (13), pleating and compressing the cellulosic food wrap on the mandrel, using a hollow core (31) which is sufficiently rigid to resist deformation and reduction of the size of its opening, under the effect of a force exerted towards the inside of the envelope as a result of the compression of this envelope, and to move the linearly in5 25. The method of claim 24, characterized in that the core is supported by a second mandrel and in that the pleated envelope is transferred to the core and to the second mandrel. 25 30 35 40 45 50 55 60 65 26. The method of claim 24, characterized in that the pleated cellulosic food envelope, supported by the mandrel, is brought into a second position before being moved from the second end of the mandrel onto the core.