LU87528A1 - Encasing plastic product - in casing formed of strip material having side edges in overlapping relation - Google Patents

Abstract

Strip material is formed into an elongate tubular casing with the side edges of the strip frictionally engaging and overlapping each other along an elongate seam, and a plastics product is introduced into the casing. The overlapped edges of the strip are sufficiently damp and are sufficiently overlapped to maintain the edges in overlapped relation and the strip in tubular form to contain the plastics product.

Description

r 1 B.

The invention relates to a wrapped product, and a method and apparatus for wrapping this product.

Currently known product wrapping devices include a push tube, a pump for passing a plastic product through the push tube, a rotary mandrel placed opposite the discharge end of the push tube, an apparatus for tying up the filled envelope, and an apparatus for arranging the bound products in loops In addition to the use of a rotary mandrel, some devices use a rotary push tube which rotates the pushed envelope before it is liga turée in the stringing machine.

In these prior devices, a tubular envelope is compressed in an accordion fashion on the push tube and has a bent end protruding beyond the discharge end of the push tube. When the product leaves the discharge end of the pushing tube, it fills the part of the envelope 20 projecting from the end of the tube, thus filling the envelope and propelling it away from the discharge end of the tube so that additional parts of the envelope are unfolded and driven beyond the end of the tube.

25 envelopes for the manufacture of skinless sausages, as well as edible envelopes for other types of sausages, are currently produced in a tubular form before being mounted on the end of the pushing tube. Due to its tubular shape, it is difficult to treat the envelope on both sides of the material constituting it. In addition, to allow mounting of a large length of casing on the tube, it is necessary to fold the casing (fripper it so that it is condensed to a short length) in a stick form so that a (considerable length of envelope can be placed on the horn, usually up to 30 meters or more.

This pleating operation is costly and long, and the envelope is bulky and fragile during transport.

5 During the pushing and tying operations, these pleated sticks or envelopes are placed on a push horn and rotated at high speed in order to facilitate twisting of the envelope at intervals after it has been filled for form strings.

/ S? ”- · -jo The method described above for the establishment of the envelope on the push tube, in a pleated form, also has the disadvantage that the length of the envelope is somewhat limited. When each envelope length has been fully used, it is necessary to stop the machine so that another pleated envelope stick can be placed on the push tube.

It is known that envelopes can be produced in the form of flat tape and supplied in rolls of several hundred meters in length. However, there has hitherto been no convenient means for placing this casing on the push tube in a form producing a cylindrical casing. This was impossible until the present invention since the envelope had to be turned to form a twisted ligature. Until United States Patent Application No. 644,218, filed August 24, 1984, there was provided no practical means for laying the envelope tape on the push tube while allowing 30 at the same time the envelope to be turned to form the twisted ligature. However, the adhesive used in the invention described in the aforementioned application and applied to the edges of the helical ribbon requires a very delicate and difficult operation.

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'‘3' i’ The main object of the invention is therefore to provide an improved wrapped product, as well as an improved method and apparatus for wrapping this product.

Another object of the invention is to provide an apparatus which forms a cylindrical envelope from a flat ribbon while allowing the cylindrical envelope to be filled simultaneously, rotated and twisted into several strings 10 sausages, the use of an adhesive on the tape is not necessary.

Another object of the invention is to propose an apparatus allowing this to form an elongated ribbon of envelope in several helical evenings, the lateral edges of the ribbon, inside each of the helical smi-res, bearing against the lateral edges helical turns adjacent to the ribbon and covering them in order to form a cylindrical envelope by the combined effect of the natural cohesiveness of the ribbon 2o in overlap and the outward pressure exerted by the material placed in the envelope.

Another object of the invention is to provide an apparatus which includes envelope supply means which can be adjusted in order to modify the angle of the helical turns. according to which the envelope surrounds the push tube.

A subject of the invention is also an apparatus for forming a cylindrical casing on a push tube from a continuous wrapping strip, whether the push tube is fixed or rotated! l txon.

Another object of the invention is to provide an apparatus which comprises fixed means of supply; ” envelope, means for rotating | The envelope after it has been filled, and ligating means which grip the filled envelope in rotation and allow it to twist to form a ligature.

Another subject of the invention is an apparatus in which the speed of advance of the tubular casing is established by the mechanism to be tied and the speed of rotation of the tubular casing determines the lateral or transverse movement of the ribbon d 'envelope.

Another object of the invention is to provide an apparatus in which the speed of rotation of the envelope and the longitudinal speed of the envelope can be modified in order to produce a tubular envelope of desired diameter and speed of rotation for obtain the desired number of helix turns from each strip of wrapper inside each ligature, and also to establish the desired length of sausage.

Another object of the invention is to provide an apparatus which reduces the cost of envelopes for the formation of sausage ligatures.

Another object of the present invention is to provide a method and an apparatus which make it possible to form an elongated ribbon of an envelope material the lateral edges of which touch and overlap to form a cylindrical envelope by the combined effect of the internal cohesion by friction of the covered ribbon and the pressure towards the outside of the material placed in the envelope, the cohesion being improved by the humidity of the ribbon.

Another object of the present invention is to provide a means for applying moisture to the tape, when the tape is introduced into the product wrapping machine.

Another object of the present invention is to provide a bound cartridge containing tape for use in wrapping this product, a predetermined amount of moisture being imposed on the tape in the sealed cartridge in which the humidity is maintained until the cartridge is opened for use in the product wrapping machine.

The present invention uses a product pump, a push tube connected to the pump, and tying means located beyond the discharge end of the tube f ‘* 5 fc.

/ pushing. In addition, an envelope feeder is mounted in close proximity to the push tube and is designed to provide the latter with an envelope in the form of a flat ribbon. The push cube can be fixed or can be a rotary push tube. In the case of the fixed push tube, additional means such as a rotary mandrel are provided for rotating the envelope after it has been filled and before it reaches the lic? .T: urer unit. This "" · "- 10 rotation movement is produced by the rotary push tube in the case of a machine having a rotary push tube.

; i. The envelope tape is mounted on an envelope feeder which can be in the form of a reel or a rotating drum in any other suitable form. The ribbon is advanced from the reel onto the outer surface of the push tube while being inclined at an angle relative to the longitudinal axis of this tube. The envelope surrounding liaisur-20 outer face of the push tube is rotated either by the rotary push tube (in the case of a rotary push tube), or by other means, jcon-venables such as a rotary mandrel (in the case of a fixed push tube). * ^ £ lgl | §r 25 A product pump discharges the material Flu.

product: in the pushing tube and inside ^ r ^ âejsl t the casing at the discharge end of the tube§ | Sec''i; for effect of pulling the envelope from 11 extremltéWduMtdbe -of pushing and to propel it towards 1 apparatus ^^^^^^^ yi-30 turer. Continuous operation of the pump ~ M '^ r ^ liit ^ a.àr. effect of pulling the envelope from '1' extxéâi ^^^^^ belü · - of continuous pushing and, consequentlyVWde ^^ (s ^ | x ^ reS ^ - · / continuous envelope tape of 1 ' apparatus ^^^ SËE ^ S ^ -Γ.- · ............. 'V-; * 1 6 r

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The tape feeder applies the tape to the outside surface of the tube at an angle to the longitudinal axis of the tube.

The rotation of the tube, in the case of a rotating tube (or. 5 the rotation of the mandrel in the case of a fixed tube), has the effect of surrounding the ribbon, in several helical turns, the outer surface of the tube . The angle of arrival of the ribbon on the tube and the width of the ribbon are chosen so that the edges of the ribbon overlap in the helical turns, thus forming an elongated cylindrical envelope. The overlapping edges of the envelope strip adhere to one another only by the natural cohesiveness of the parts of the overlapping envelope and by the pressure of the product to be wrapped to form a cylindrical envelope in one piece.

The preferred embodiment of the ribbon supply means comprises a reel or a reel i 1 mounted on a support frame so as to be able to pivot both around a horizontal axis and a vertical axis of 20 cal joint. The reel can pivot or journal freely around the vertical axis so as to be able to align itself on the push tube by forming a predetermined angle, under the effect of the traction pulling the tape of the reel. The angle formed by the reel with the longitudinal axis of the push tube can be modified by pivoting the support frame of the reel about a second vertical axis relative to the machine frame and by fixing the support frame of the machine. reel in a stationary position when the desired angle 30 is reached.

The push tube · according to the invention is of a particular design in that its discharge end carries several fingers extending radially outwards. These outwardly extending fingers 35 bear, at their ends, against the internal surface - - -

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. 7 ”of the envelope at several points. The distance between the ends of the fingers is such that the envelope is not stretched beyond its normal cylindrical circumference, but is rather deformed to take, in cross section, an approximately polygonal profile, each of the fingers forming a vertex of the polygon. These outwardly extending fingers produce a fraining or retaining effect on the longitudinal movement of the casing Ί0 as it is pulled from the discharge end of the push tube. This restraint or drag is important. aunt to ensure proper filling of the envelope, uniformly along its length.

The present invention uses a fixed mount to hold the reel or spool of the envelope tape, yet it allows the envelope to be turned at the end of the push tube to form twisted ties. In the case of a fixed push tube, a rotary mandrel or other means are provided in the immediate vicinity of the outlet end of the horn or tube in order to rotate the tubular section of the envelope at the appropriate speed to produce the desired number of twists per ligation. In the case of a rotary push tube, the tube itself communicates a rotation with the envelope passing over it.

Beyond the end of the push tube is a ligating device which clamps and tightens the envelope at set intervals in order to determine the exact location where the torsion is established in the tubular envelope as well as '' Establish the distance between the ties to determine the length of the sausages in strings.

The speed of advance of the tubular casing - 35 formed and filled is regulated by the tying mechanism / - 8 - r. ^ while the speed of rotation of the tubular casing determines the speed at which the casing tape is pulled from the tape supply means. By acting on these two speeds and using the correct width of ribbon, it is possible to produce a tubular casing of a desired diameter, which is rotated at the appropriate speed in order to produce the desired number of twists per ligation as well. than producing the desired length of sausage 10. These two movements combined determine the angle at which the tape is applied to the horn. The freewheel swiveling assembly of the envelope supply means allows the envelope roller to pivot automatically around a vertical axis and to follow the desired angle.

All of the foregoing aspects of the invention are represented and described in U.S. patents. No. 4,660,225, 4,709,447 and 4,727,625. The novelty of the present invention is the application of a sufficient amount of moisture to the material of the envelope to improve the cohesion by friction of these parts which overlap. The desired humidity can be imposed on the envelope or the material in the form of a strip, either at the moment when the material is introduced into the machine for wrapping a product, or at the time of manufacturing the material for the envelope which is then c placed in sealed cartridges to maintain the desired degree of humidity until it is used.

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 a perspective view of the apparatus according to the invention; Figure 2 is a plan view of the apparatus according to the invention; 35:. 9

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f Figure 3 is a front view of the apparatus according to the invention; * 'Figure 4 is a perspective view on an enlarged scale of a detail of the end of the pushing tube 5; Figure 5 is a detailed longitudinal section showing the arrangement of the casing on the end of the push tube; Figure ô is a section on the line 1 0 6-6 of Figure 5; Figure T is a partial section on an enlarged scale showing in detail the inlet end of the push tube; Figure 8 is a top plan view ^ 5 of the envelope feeder; Figure 9 is a section along line 9-9 of Figure 8; Figure 10 is an enlarged scale plan view of a detail of the discharge end of the push tube and the means for tying; H ·} Figure 11 is a section along line 11-11 of Figure 11; : Figure 12 is a view similar to that; h- •! * · -I of Figure 10, but showing an embodiment s.

Modified from the invention; ;: Figure 13 is a partial view in pers- j.j ·.

pective of part of the push tube during the; ·. i rolling of the ribbon material on this tube; ij "Figure 14 is a cross section along line 14-14 of Figure 13; Figure 15 is a longitudinal section?; along line 15-15 of Figure 14; and 'j; Figure 16 is a perspective view of a finished ligature sausage of wrapped material. I:, · r :: • J:. · !! _ 1: "7.S-TT '. Π r -—— -, „.. ... ------------ 10 w

In FIG. 1, the reference numeral 10 generally designates the pushing and tying machine according to the invention. The machine 10 comprises a table or a frame 12 on the upper surface of which 5 are mounted an assembly 14 for pumping of product, a tube support assembly 16, a push tube or horn 18 and an apparatus 20 for tying. An assembly 22 for supplying the envelope tape is also mounted on the table 12.

10 Ξη reference- in Figure 7, the product pump 14 is of conventional design and is therefore not shown in detail. The pump 14 includes an outlet 24 which communicates with the inlet end 26 of the pushing tube 18. The tube support assembly 16 15 includes a frame 23 which is mounted on the upper surface of the table or frame 12 and which contains several bearings 30 supporting the pushing tube 18 and allowing it to rotate about a horizontal axis . A belt pulley 32 is mounted 20 on the pushing tube 18 inside the frame 28.

A drive belt 36 passes over the pulley 32 as well as over another engine pulley 34. The pulley 34 is driven by a motor 38 in order to rotate the pushing tube 18 around its longi-tudinal axis.

The pushing tube 18 has a section 40 of enlarged diameter adjacent to its inlet end 26, and it also comprises an elongated section 42 of reduced diameter extending from the enlarged section 40 30 to the discharge end 44 pushing tube 18 (Figure 4).

As can be seen in FIGS. 4 and 5, the discharge end 44 has several fingers 46 each widening radially towards the outside up to a point 48. In the configuration shown in the figures 4 and 5, four fingers 46 are ψ · '' 11 vitilized, but one can also use a larger or smaller number of fingers without departing from the scope of the invention.

As can be seen in the figure. 5 6, each of the finger tips 48 bears against the interior surface of the envelope 50 in order to give the latter a substantially polygonal shape (a square shape in the case of the configuration shown in FIGS. 4 and 5), rather than the circular cross-sectional shape which is obtained around the reduced diameter section a2 of the pushing tube 18.

The flaring of the tips 48 outwards is chosen * so that the tips do not deform or stretch i. The envelope from its natural original form obtained by the fact that it surrounds the pushing tube 42 ’. In other words, the circumference of the envelope} I lop 50, in contact with the tips 48 of the fingers "i,? is the same and is not enlarged compared to that | of the envelope 50 when it surrounds the section 42 1 20 of reduced diameter of the pushing tube 18. With reference I to FIG. 6, the dimension X represents the distance | from the center of the cross section of the push tube

Isage up to the tips 48 tapered outwards.

If this distance X is chosen so as to be approximately 1 25 1.11 times the radius of the section 42 of reduced diameter of the pushing tube, this results in a deformation of the circular profile of the envelope by the fingers 48 without stretching or enlargement of the circumference of the envelope.

The result of the above configuration j of the fingers 46 flared outwards is that there is applied to the envelope a longitudinal drag or resistance opposed to the forward propelling movement communicated by the product leaving the 'extré i | 35 external unit 44 for discharging the push tube 18.

▼ • '12 μ ι The assembly 22 for supplying the envelope tape consists of an elongated bent frame 52 comprising an upper element 54 and a lower element 5 o connected by an elbow 58. L 'upper element 54 of the frame 5 consists of a single piece. The lower element 56 of the frame consists of two spaced apart arms 62. The latter and the upper element 54 of the frame are connected together by the elbow 53.

An envelope reel or coil 64.

- Ί0 supported by the elbow 58 by means of an axis 66 which passes through the center of the coil 64, is mounted so as to be able to rotate between the spaced arms 62. The axis 66 establishes the mounting in rotation of the coil 64 so that it can rotate around a horizontal axis.

An elongated wrapping tape 68, yes is wound on the spool 64, is flat and has opposite side edges 70 and 72 (Figure 13). The ribbon 68 is made of cellulosic material commonly used for casing sausages. Its thickness 2Q is approximately 0.03 mm and its width can vary; however, a width of 2.5 to 10 cm is satisfactory.

The lower end of the lower element 56 of the frame has a vertically oriented bushing 74 (FIG. 9) which is positioned between two vertically spaced jaws 76, 78 of a pivoting block 80. A pivot or bolt 82 descends through the upper and lower jaws 76, 78 and also passes through the bushing 74 in order to carry out the pivoting mounting of the angled frame 52 around a vertical axis.

As can be seen in FIG. 9, the length 30 of the socket 74 is slightly greater than the thickness of the lower element 56 of the frame so that this element 56 can pivot freely around the socket 74 without jamming against the upper and lower spaced jaws 76 and 78.

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The pivoting block 80 also comprises two spaced wings 83, 34 which frame a support block 86 rigidly mounted on the table or the frame 12. The pivoting block 80 is mounted so as to be able to pivot on the support block 36 by means of 'a bolt or pin 88 which passes through the wings 33 and 34 and also passes through the support block 36. Thus, the pivoting block 80 can pivot freely, author of the vertical axis 88.

'ί o' Jne plate 89 ie adjustment is rigidly mounted on the upper surface of block 86 this support.

The bolts 92, thus having the axis 88 which passes through the plate 39, prevent the latter from moving relative to the block 86.

Ί5 The plate 39 has a curved slot 90 which follows a curve centered on the pivot axis 88. The bolt 82 passes through the slot 90, then descends through the jaws 76 and 78 and the socket 84.

When the bolt 82 is tightened, it keeps the pivoting block 80 so that it cannot rotate around the axis 88, while allowing the angled frame 52 to pivot or rotate freely around the vertical axis 82. When it is desired to pivot the block 80 around the axis 88, it suffices to loosen the bolt 82 and to rotate the block 80 around the axis 88 to the desired position. The bolt 82 is then tightened and the block 80 is held so that it can no longer pivot;

A ribbon support pin 94 is mounted on the upper end of the upper frame member 54 (Figures 2 and 3). The shaft 94 has a sliding support surface for the tape 68 as it is pulled from the spool 64.

At its exit from the coil 64, the free end 35 of the ribbon rises on the axis 94, then is wound up!

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. , * 14 ψ fr- around the pushing tube 18, in a helix, in order to form an elongated cylindrical envelope designated Dar by the reference numeral 50. Sn reference to FIG. 15, each helical turn 68A comprises parts of overlapping 68B and 68C. The degree of overlap can vary, but it must be large enough so that the helical turns 68A do not separate under the effect of filling with the material. An overlap equal to half the width of the ribbon 68 is more than sufficient.

As can be seen in FIGS. 2 and 3, the axis 94 is positioned in front of the pivot axis 32. This arrangement places the spool 64 and the axis 94 on either side of the pivot axis 32 ^ When the ribbon 63 is pulled so as to pass 15 on the axis 94. it freely rotates the whole of the frame 52 around the axis 82 in order to automatically align the coil 64 with the angle of the helical turns formed by the ribbon on the pushing tube.

The mechanism 20 to be ligated is of conventional design and comprises two rotary chains 100 to be ligated carrying several V-shaped clamping elements 102 and several V-shaped holding elements 104. The chains 100 are mounted on toothed wheels. spaced 106 in two retaining brackets 108 25 are positioned so as to keep the chains spaced apart to establish between them a path 110 intended to receive the envelope 50 in rotation from the discharge end of the pushing tube 18 and to form ligatures twisted with the envelope rem-30 folds, in a conventional manner.

The embodiment shown in Figures 1 to 12 includes a rotary push tube 18. However, the present invention can also be used with a fixed push tube. Figure 35 12 illustrates a modified embodiment of the in- | '5

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♦ ♦ vention in which a fixed pushing tube 110 comprises, in the immediate vicinity of its discharge end, an assembly 112 with rotary mandrel. The mandrel assembly 112 is similar to the current rotary mandrels currently used in product wrapping machines. It comprises a rotary driven element 11 & having a longitudinal opening 116 of the mandrel from which project radially inwards several grooves 118 which are intended to bear 10 against the external surface of the envelope after it has been filled with the product. leaving the discharge end of the push tube 110. The rotary element communicates a rotation with the filled envelope so that the latter rotates when it is taken up by the mechanism 20 to be tied.

The operation of the device shown in Figures 1 to 11 will now be described. The operator first determines the angle at which he wants to bring the strip 68 into contact with the push tube 18. To this end, it loosens the bolt 82 and rotates the block 80 in the curved slot 92 to the desired angle. It then tightens the bolt 82 so that the pivoting block 30 can no longer move.

The free pivoting mounting of the bent frame 52 on the axis 82 allows the coil 64 to rotate freely around the vertical axis 82. This allows the coil 64 to align automatically under the action of the ribbon pulled j from the coil.

After choosing the correct setting for] 30 the swivel block 80, the operator pulls the free end

tape 68 upwards passing it along the J axis

94 as shown in FIGS. 3 and 4. It then wraps the envelope around the pushing tube 18, in a helix, as shown in FIG. 2, until a section of the envelope protrudes from the end j »î *» 16 f of discharge from the pushing cube. When the operator pulls the ribbon from the spool 64, the overlapping parts 683 and 68C tend to adhere by friction to each other in order to maintain the shape of the envelope 50. Thus, when the ribbon is wrapped around the pushing tube 18, the lateral edges 70, 72 overlap, come into contact and adhere to each other by friction, so that the ribbon takes the form of a. elongated cylindrical shell designated by the reference numeral 50 in the drawings.

The operator then starts the machine, so that the product pump 14 forces the product forcibly into the push tube and the latter is simultaneously rotated. When the pushing tube 15 rotates, the friction between this tube and the cylindrical casing 50 causes the latter to rotate with the tube. The product pumped through the push tube leaves the discharge end of the latter and fills the envelope which protrudes from the push tube 20 in order to form a filled sausage which is taken up by the mechanism to be spoiled, d in a conventional manner, as shown in FIGS. 10 and 11. The filling of the envelope exerts a force towards the outside against the helical turns 68A and causes a firmer grip and friction adhesion between the overlapping parts 68B and 68C.

The flared ends 48 of the fingers bear against the inner surface of the envelope while it is pulled from the discharge end of the pushing tube 30 and exert braking or drag on the axial movement of the envelope. This allows the envelope to be filled at least partially before making a ligature. The lateral speed _i of the ligating device establishes the final degree of i i. i 1 7 »r * * t filling as desired. The flared ends 43 of the fingers also facilitate the rotation of the envelope 50 under the effect of the rotation of the push tube.

The rotation of the pushing cube and the axial movement of the cylindrical casing 50 from the discharge end of the pushing tube have the effect of continuously pulling the ribbon 63 from the spool 64 and winding it up. helically around the push tube. wise 18.

19 Given that the angled frame 52 can pivot freely around the vertical axis of the bolt 32, / the coil 64 can align itself in a straight line relative to the line passing through the axes 32 and 38.

, If it is desired to modify the location 15 to which the ribbon is brought to the rotary pushing tube 18, the operator simply loosens the bolt 82 and rotates the block 80 to the desired position. This changes the position of the spool relative to the push tube, so that the point at which the ribbon begins to wind on the tube is also changed.

The angle of attack of the ribbon 68 and the width of the latter are chosen so that the edges of the ribbon are adjacent or overlap when it is wound on the pushing tube 18.

The result of the embodiment described above is that the roller formed by the envelope is mounted on the assembly 22 for supplying the envelope ribbon which is fixed relative to the pushing tube 30. Simultaneously, the present invention rotates the envelope 50 at the end of the horn, which is necessary to form the twisted ligatures using the mechanism 20 to be ligated.

The speed of advance of the tubular envelope formed is established by the ligating mechanism 18 ψ and by the speed at which the pumping assembly 14 forces the product from the end of the pushing tube. . The speed of rotation of the tubular casing determines the lateral or transverse movement of the casing tape. Consequently, by acting on these two speeds and using the correct width of ribbon, it is possible to establish the desired angle of attack of the ribbon and to produce a tubular casing of the desired diameter, yes turns at the speed "0 suitable for producing the desired number of twists per ligation and giving the desired length to each sausage between two ligatures.

In the variant of FIG. 12, the pushing tube 110 is fixed and does not have a flared end 15. However, rotation of the envelope is established by the rotary mandrel assembly 112 which engages the filled envelope in the immediate vicinity of the discharge end of the push tube. This has the effect of rotating the envelope on the pushing tube, thus producing the same pulling effect of the ribbon 63 of the supply assembly 22 and of forming the helical turns which constitute the cylindrical envelope 50.

It can therefore be seen that the present invention can be used both with a fixed push tube or a rotary push tube.

FIG. 17 shows another form of the invention comprising a housing or a cartridge 64A comprising the parts 64B and 64C saddled by an appropriate means whatever along a joint line 64D. The cartridge 64A contains a coil 64 in which the ribbon 68 has the desired degree of humidity imposed at the time of manufacture.

The ribbon 68 is then sealed in the cartridge 64A to maintain the humidity level in the ribbon until the ribbon is used as shown in Figures 1, 2 and 3.

FIG. 18 represents a fastener which can be made * f * * - 19 - on the machine of FIGS. 1, 2 and 3 allowing the addition of moisture to the ribbon 68 as it is introduced into the wrapping machine a product. The roller 22A 5 is mounted using a means suitable for the machine adjacent to the ribbon 68.

A cellular material 22B is attached to the outer surface of the roller 22A which is mounted on a central support 22 for rotation. The surface of the cellular material 22B 10 is suitable for contacting the strip 68 when the latter leaves the coil 64 as shown in FIGS. 1, 2 and 3. A tube 22D for supplying liquid or water connected to a controlled source of liquid terminates adjacent the periphery of the material 22B for depositing the liquid on the material 22B for subsequent deposition on the tape 68. The liquid may be water or a non-water based fluid adhesive. The amount of moisture or the moisture content to be imposed on the tape 68 will vary depending on the precise material thereof. However, sufficient moisture must exist to allow the overlapping edges of the tape to cohesion sufficient by friction to hold the envelope strip in a self-contained tubular envelope to contain a plastic product. The roll 22A can either contact the entire tape 68, or only the overlapping side edges.

Ribbon 68 can be formed from a conventional envelope material, such as hydrated cellulose, collagen or synthetic intestines which can be made, for example, from polyamide or polyester. The hydrated cellulose envelopes are produced by viscose coagulation and cellulose regeneration; they contain plasticizers, such as glycerol. While these conventional envelopes typically contain 6 to 15% water, they can contain up to 25% or more water. The water content of conventional envelopes, which are all tubular in shape, has nothing to do with the formation of these conventional envelopes, (see U.S. Patent No. 4,505,003, column 5, from 40 of the line 15) f * - 20 -

In addition, some conventional envelopes include an outer layer which is impermeable to water and water vapor which prevents their use in the present invention. This is due to the fact that the moisture content of the tape 68 is crucial to complete the friction adhesion of the tape when the envelope is formed.

Thus, the tape 68 of the present invention should have a moisture content of between 15 and 45 °, and preferably between 20 and 40% (by weight). If the moisture content is less than 15%, adhesion is weak or non-existent. If the moisture content is greater than 45%, the envelope is too wet and the humidity prevents the adhesion process by lubricating the surface of the tape.

Thus it can be seen that this invention will achieve at least all of the above-mentioned objectives.

Claims (12)

1. Apparatus for wrapping a plastic product, characterized by a support, an elongated strip for an envelope 5 having opposite lateral edges, a first means on said support for forming said strip into an elongated tubular envelope, the lateral edges of said strip engaging by friction and covering one or the other along an elongated joint, a second means on said support 10 for introducing said plastic product into said envelope, said edges overlapping the strip for the envelope being sufficiently moist by the presence of moisture and overlapping enough to maintain said side edges in a fixed covering position to maintain said envelope strip in the form of a self-contained tubular envelope to contain said product. 2. Apparatus according to claim 1, characterized in that said first means on said support comprises means for forming said strip in several helical revolutions, the lateral edge of said strip including each of the helical revolutions engaging by friction and covering the edges of said strip in the helical revolutions adjacent to a helical revolution so as to form an elongated tubular envelope. 3. Apparatus according to claim 1 or 2, characterized in that the strip for the envelope has a moisture content of 15 to 45% by weight. 4. The apparatus of claim 1 or 2, wherein said envelope tape has a moisture content of 20 to 40% by weight. 5. Method for wrapping a plastic product, characterized by the steps of taking an elongated strip of an elongated tape free of adhesive, of imposing sufficient moisture at least on the side edges of said tape so that said side edges will adhere to each other when they overlap, to form said elongated tape having opposite side edges into an elongated tubular casing so that the side edges of said tape engage by friction and overlap each other along 40 of an elongated joint to form an elongated tubular envelope i- / - 22 - to introduce the plastic product into the envelope, to cause the lateral edges of said ribbon to overlap enough to maintain said lateral edges-5 in a fixed covering position to hold the said ribbon in the form of a self-contained tubular envelope to contain the plastic product. 6. Method according to claim 3, characterized by the additional step of forming said elongated ribbon 2.0 having the opposite lateral edges in a plurality of helical revolutions, the lateral edges of said ribbon in one of the helical revolutions touching by friction and covering the lateral edges in the adjacent helical revolutions. 7. Method according to claim 5 or 6, characterized in that the humidity imposed on said tape is limited to values between 15 and 45 ° by weight. 8. Method according to claim 5 or 6, characterized in that the humidity imposed on said tape is limited to values between 20 and 40 ° by weight. 9. Enveloped product, characterized in that it comprises an elongated flexible envelope of substantially cylindrical shape along its length and forming a cavity for a product, a material for said product filling said cavity and maintaining said envelope in its cylindrical form said cylindrical shell being formed from an elongated strip of flexible material having opposite side edges in an overlapping state to create an elongated joint, said side edges ^, which overlap, and the strip for the the envelope being sufficiently moist by the presence of moisture and being sufficiently covered to create sufficient cohesion by friction to hold said strip of flexible material in the form of a self-contained flexible envelope which contains the material for the product. 10. Wrapped product according to claim 9, characterized in that the envelope is formed from an elongated layer of flexible material formed in a plurality of revolutions, each of said revolutions engaging by friction and covering the revolutions. adjacent. ο * '- 23 - 11. Product wrapped according to claims 9 or 10, characterized in that the envelope has a moisture content by weight of between 15 and 45%. 12. Product wrapped according to claims 9 or 10, characterized in that the envelope has a moisture content by weight of between 20 and 40%.