Extensible flexible hose, and method and production line for continuously manufacturing thereof

Abstract

A hose that includes an inner layer and an outer layer made of an elastic polymeric material, and a textile reinforcement layer interposed between the inner and the outer layers. The inner layer and the outer layer are reciprocally coupled to form a unitary tubular member, within which the textile reinforcement layer is embedded. The unitary tubular member has an elasticity such to automatically elongate under the working pressure given by the liquid flowing therethrough to increase its original length and to automatically recover once the working pressure stops. The textile reinforcement layer is adapted to move from a rest configuration when the working pressure stops to a working configuration when the unitary tubular member elongates under the working pressure, and vice versa.

Claims

1. An extensible flexible hose for transporting liquids, particularly water, comprising: at least one inner layer made of a first elastic polymeric material; at least one outer layer made of a second elastic polymeric material; at least one textile reinforcement layer interposed between said at least one inner layer and at least one outer layer; wherein said at least one inner layer and said at least one outer layer are reciprocally coupled to form a unitary tubular member, said at least one textile reinforcement layer being embedded therein; wherein said unitary tubular member has an elasticity that causes said unitary tubular member to automatically elongate and enlarge upon a working pressure given by a liquid flowing therethrough to respectively increase an original length and diameter of said unitary tubular member and to automatically recover once the working pressure stops for assuming again said original length and diameter; wherein said at least one textile reinforcement layer is adapted to move between a rest configuration that is present when no liquid flows through the unitary tubular member and a working configuration that is present when said unitary tubular member elongates and enlarges under the working pressure; and wherein said first and said second elastic polymeric materials are elastomers or thermoplastic elastomers, said unitary tubular member having a Shore A hardness measured according to ASTM D2240 of 30 ShA to 50 ShA.

2. The hose according to claim 1, wherein the automatic elongation and enlargement of said unitary tubular member (50) promotes a moving of said at least one textile layer (30, 40) from the rest configuration to the working configuration, the automatic recovery of said unitary tubular member promoting a retreat of said at least one textile layer from the working configuration to the rest configuration.

3. The hose according to claim 1, wherein said at least one textile reinforcement layer and said unitary tubular member are reciprocally configured so that said at least one textile reinforcement layer captures said unitary tubular member upon an elongation and enlargement of said unitary tubular member so as to define a maximum length and diameter thereof.

4. The hose according to claim 1, wherein said at least one textile reinforcement layer is disposed on an outer surface of said at least one inner layer so as to leave thereon a plurality of uncovered areas, said at least one outer layer and at least one inner layer being reciprocally coupled in correspondence of said uncovered areas.

5. The hose according to claim 1, wherein said unitary tubular member has the original diameter and the original length when said at least one textile reinforcement layer is in the rest configuration, said unitary tubular member being enlarged and elongated when said at least one textile reinforcement layer is in the working configuration.

6. The hose according to claim 5, wherein said at least one textile reinforcement layer comprises at least one first textile reinforcement layer and at least one second textile reinforcement layer, said at least one first textile reinforcement layer and said unitary tubular member being reciprocally configured so that the at least one first textile reinforcement layer captures the unitary tubular member upon an elongation of the unitary tubular member so as to define the maximum length, said at least one second textile reinforcement layer and said unitary tubular member being reciprocally configured so that the at least one second textile reinforcement layer captures unitary tubular member upon an enlargement of the unitary tubular member so as to define the maximum diameter.

7. The hose according to claim 6, wherein said second textile reinforcement layer is externally placed with respect to said first textile reinforcement layer, said at least one first textile reinforcement layer being in a form selected among the group consisting of knitting, weaving or knotting, said at least one second textile reinforcement layer being a spiral or a braiding.

8. The hose according to claim 1, wherein said unitary tubular member and said at least one textile reinforcement layer cooperate each other so that under a working pressure of 2 bar the hose increases its length of at least 1.5 times with respect to its original length.

9. The hose according to claim 1, wherein said unitary tubular member once elongated and enlarged by the working pressure recovers back to its original length exclusively thanks to its elasticity, without any other biasing means.

10. The hose according to claim 1, further comprising at least one restriction or at least one flow restrictor to create within the hose the working pressure adapted to promote an elongation and an enlargement of the hose, said at least one restriction or at least one flow restrictor being internal to the hose or connected therewith.

11.-18. (canceled)

19. A method for continuously manufacturing an extensible flexible hose, comprising the following steps: a) providing at least one inner layer made of a first thermoplastic polymeric elastic material; b) elongating of said at least one inner layer with respect to its original length; c) disposing, on said at least one elongated inner layer, at least one textile reinforcement layer so as to obtain a semifinished hose; and d) extruding at least one outer layer made of a second polymeric thermoplastic elastic material on said semifinished hose; wherein said step d) of extruding said at least an outer layer includes a step of reciprocally coupling said at least one outer layer to said at least one inner layer so as to obtain a unitary tubular member, so that said at least one textile reinforcement layer remains embedded therein; wherein said unitary tubular member has an elasticity such to automatically elongate and enlarge upon a working pressure given by a liquid flowing therethrough to respectively increase an original length and diameter of said unitary tubular member and such to automatically recover once the working pressure stops for assuming again said original length and diameter; wherein said at least one textile reinforcement layer is adapted to move between a rest configuration that is present when no liquid flows through the unitary tubular member and a working configuration that is present when said unitary tubular member (50) elongates and enlarges upon the working pressure; and wherein said first and said second elastic polymeric materials are elastomers or thermoplastic elastomers, said unitary tubular member having a Shore A hardness measured according to ASTM D2240 of 30 ShA to 50 ShA.

20. The method according to claim 19, wherein said steps c) of disposing said at least one textile reinforcement layer and said step d) of extruding said at least one outer layer (20) are accomplished while said at least one inner layer is elongated with respect to its original length.

21. The method according to claim 19, wherein said step b) of elongating said at least one inner layer is carried out by a drawing thereof.

22. The method according to claim 21, wherein the drawing is accomplished by at least two rotating devices adapted to convey and press said at least one inner layer, a first rotating device pressing said at least one inner layer before said step c) of disposing said at least one textile reinforcement layer, a second rotating device pressing said at least one inner layer after said step d) of extruding said at least one outer layer, said second rotating device rotating faster than said first rotating device to continuously elongate said at least one inner layer.

23.-26. (canceled)

27. A production line for continuously manufacturing an extensible flexible hose by a method according to claim 19, comprising: an inlet for at least one inner layer of a first elastic polymeric thermoplastic material; elongating means for elongating said at least one inner layer with respect to an original length thereof; at least one station for disposing on said at least one inner elongated layer at least one textile reinforcement layer, so as to obtain a semifinished hose; an extruding station for extruding on said semifinished hose at least one outer layer of a second polymeric thermoplastic elastic material to produce a finished flexible hose; an outlet for the finished flexible hose; wherein in said extruding station said at least one inner layer and said at least one outer layer are mutually coupled to each other to define a unitary tubular member, said at least one textile reinforcement layer being embedded therein; wherein said unitary tubular member has an elasticity such to automatically elongate and enlarge upon a working pressure given by a liquid flowing therethrough to respectively increase an original length and diameter of said unitary tubular member and to automatically recovery once the working pressure stops for assuming again said original length and diameter; wherein said at least one textile reinforcement layer is adapted to move between a rest configuration that is present when no liquid flows through the unitary tubular member and a working configuration that is present when said unitary tubular member elongates and enlarges under the working pressure; wherein said elongating means include at least two rotating devices for conveying and pressing said at least one inner layer, a first rotating device being upstream of said station for disposing said at least one textile reinforcement layer, a second rotating device being downstream of said station for extruding said at least an outer layer, said second rotating device rotating faster than said first rotating device so that said at least one inner layer is continuously elongated; and wherein said first and said second elastic polymeric materials are elastomers or thermoplastic elastomers, said unitary tubular member having a Shore A hardness measured according to ASTM D2240 of 30 ShA to 50 ShA.

28. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Further features and advantages of the invention will be apparent upon reading the detailed description of a preferred, non-exclusive embodiment of an extensible flexible hose 1 and a line 100 for manufacturing thereof, which are described as non limiting examples with the help of the annexed drawings, in which:

[0092] FIGS. 1 to 3 are schematic view of an embodiment of the hose 1 during use;

[0093] FIG. 4 is a schematic side view of an embodiment of the hose 1 at rest;

[0094] FIG. 5 is a schematic side view of the embodiment of the hose 1 of FIG. 4 under pressure;

[0095] FIG. 6 is a schematic side view of an embodiment of the line 100;

[0096] FIG. 7 is a radial sectional view of the embodiment of the hose 1 of FIG. 4;

[0097] FIGS. 8 and 9 show two examples of woven textile reinforcement layer;

[0098] FIG. 10 shows an example of a knotted textile reinforcement layer.

DETAILED DESCRIPTION OF SOME PREFERRED EMBODIMENT

[0099] With reference to the above figures, the extensible hose 1 is advantageously used for the transport of liquids. In particular, the flexible hose 1 may be a irrigation hose or garden hose for the transport of water.

[0100] As particularly shown in FIGS. 4, 5 and 7, the extensible hose 1 may include an inner polymer layer 10 and an outer polymer layer 20.

[0101] Internally to the inner layer 10, a detaching film 11 may be provided susceptible to come in contact with the liquid to be transported, the function of which will be clear later.

[0102] The extensible flexible hose 1 may further include a first inner knitted textile layer 30 with a tricot-type chain knits and a second braided textile layer 40, mutually overlapping. The pitch of the spirals of the second braiding textile layer 40 may be relatively short, for example of 1 mm to 3 mm.

[0103] The extensible flexible hose 1 may further include one intermediate polymeric layer 15 interposed between the textile reinforcement layers 30 and 40 for the separation thereof.

[0104] It is understood that although in the follow there is described a flexible hose 1 with the above structure, the hose according to the invention may include a minimum of three layers, according to which is defined by the appended claims.

[0105] For example, a single textile reinforcement layer may be provided, or one or more further polymeric layers internally or externally to the above layers.

[0106] It is further understood that although in the follow a flexible hose 1 with the above structure is described, the technical features here described are applicable to a hose which includes at least three layers, according to which is defined by the appended claims.

[0107] It is further understood that although hereinafter reference is made to a garden hose for the transport of water, the extensible flexible hose 1 can have any destination and can transport any liquid, according to which is defined by the appended claims.

[0108] In a preferred but not exclusive embodiment, inner layer 10, intermediate layer 15 and outer layer 20 may be made of a styrene-based thermoplastic elastomer (TPE-S) having a matrix based on polypropylene (PP), for example the Nilflex SH (Taro Plast SpA), having a Shore A hardness measured according to ASTM D2240 (3) of 40. Such a material has a tensile strength measured according to ASTM D412/C of about 6.5 MPa and an elongation at break measured according to ASTM D412/C of approximately 880%.

[0109] Indicatively, the inner layer 10 may have a thickness of 1.5 mm to 2.5 mm, preferably 1.6 mm-2 mm. On the other side, the film 11 may have a thickness of 0.05 mm to 0.4 mm, preferably 0.1 mm-0.3 mm.

[0110] Preferably, the detaching film 11 also may be made of the same material described above, to which may be added a small percentage of lubricant-release additive agent.

[0111] For example, the material may be added about 1% by weight total of CRODAMIDE (CRODA Polymer Additives), a migrant agent who has the aim to decrease friction and blocking of the material on itself.

[0112] In a preferred but not exclusive embodiment, the textile reinforcement layers 30 and 40 may be made of polyester (PET)-based yarns, for example the Brilen GLE (Brilen Tech SA) having a linear density of 550 dtex. Such yarns have an ultimate tensile strength, measured according to BISFA (Chap 7) of 42,7+/4,2 N, an elongation at break measured according to BISFA (Chap 7) of 12,5+/2,5% and toughness measured according BISFA (Chap 7) of 75,5+/7 cN/tex.

[0113] The first textile reinforcement layer 30 may be placed on the outer surface 12 of the inner layer 10 so as to leave thereon a plurality of open areas 13, which are directly facing to the corresponding portions of the inner surface 16 of the intermediate layer 15.

[0114] On the other hand, the second textile reinforcement layer 40 may be placed on the outer surface 12 of the intermediate layer 15 so as to leave thereon a plurality of open areas 13, which are directly facing to the corresponding portions of the inner surface 21 of the outer layer 20.

[0115] Suitably, the inner layer 10, intermediate layer 15 and outer layer 20 may be reciprocally bonded in correspondence with the respective uncovered areas 13, 13.

[0116] The bond between the inner layer 10, intermediate layer 15 and outer layer 20 may be assured by the use of materials compatible with each other or by a layer of adhesive material interposed between them.

[0117] To effect such a coupling, the inner layer 10, intermediate layer 15 and outer layer 20 form a unitary tubular member 50, inside of which the reinforcing textile layers 30 and 40 may be integrated or embedded.

[0118] The possible choice of the same material for all the polymeric layers of the hose makes homogeneous the mechanical behavior of the unitary tubular member 50, and ensures maximum compatibility between the materials.

[0119] As particularly shown in FIGS. 1-3, at the ends 51, 52 of the hose 1 appropriate mutual union elements may be provided.

[0120] For example, respective couplers 60, 61 may be provided.

[0121] In a preferred but not exclusive embodiment, the coupler 60 may be e.g. a female coupler, and may be adapted to connect the hose 1 to a point of use, for example a tap R. On the other hand, the coupler 61 may be a male coupler, and may be adapted to connect the hose 1 to one or more sprinkler accessories D, for example a lance or a sprinkler.

[0122] In another embodiment, the end 52 of the hose 1 may be fixedly coupled to the sprinkler accessory D, for example a lance or a sprinkler. In this case, the hose 1 does not include the coupler 61, and cannot be coupled to more sprinkler accessories. At the other end 51 the coupler 60 may be provided for connecting the hose 1 to a point of use, for example a tap R.

[0123] Thanks to the above features, the extendable hose 1 may be susceptible to be automatically expanded by the working pressure imparted by the water that flows internally it, thus increasing its original length and diameter.

[0124] To do this, in a per se known manner, at least one restriction inside the hose or connected therewith may be provided.

[0125] In a preferred but not exclusively embodiment, in per se known manner, the at least one restriction may be defined by a flow restrictor located inside the coupler 61.

[0126] On the other hand, the hose 1 may internally include one or more restrictions, such as thickened portions or the like.

[0127] The at least one restriction may also be provided in the sprinkler accessory D, for example a lance or a sprinkler.

[0128] The at least one restriction may create a pressure drop such that the pressure upstream thereof acts internally to the hose 1, thus axially elongating it along the axis X and radially enlarging it perpendicularly to the same axis X.

[0129] In practice, once connected to the hose 1 to a point of use, for example to a tap R, upon the opening of the tap the water that passes through the hose 1 promotes the axial elongation and the radial enlarging thereof, as shown in FIGS. 2 and 3.

[0130] In other words, the water flow promotes the passage of the hose 1 from an original length and diameter (FIG. 1), that the same hose 1 has when no water passes through it, to a working length and the diameter (FIG. 3).

[0131] The transition from the original diameter and length to the working diameter and length occurs gradually, passing through an intermediate stage, shown in FIG. 2, in which the hose starts to enlarge and elongate under the thrust of the water pressure.

[0132] By contrast, upon the closing of the tap R the hose 1 automatically retracts, thus returning to its original length and diameter.

[0133] In order to achieve the above, the unitary tubular member 50 and the textile layers 30, 40 can cooperate with each other.

[0134] More precisely, the unitary tubular member 50 may have an elasticity such as to lengthen automatically under the working pressure imparted by the water and such as to retract automatically once the working pressure stops.

[0135] Moreover, thanks to its elasticity, under the working pressure the unitary tubular member 50 may radially enlarge to increase its original diameter and then automatically retract once the working pressure stops.

[0136] On the other hand, the elongation and the enlargement of the unitary tubular member 50 promotes the passage of the textile reinforcement layers 30, 40 from a rest configuration, shown in FIG. 4, which have when no water flows through the hose to a working configuration, shown in FIG. 5, which have under the working pressure.

[0137] Conversely, when the working pressure stops the automatic retraction of the unitary tubular member 50 returns the textile reinforcement layers 30, 40 in their rest configuration.

[0138] Under the working pressure, in addition to the increase in the length and diameter of the hose, a thinning of the whole thickness thereof further occurs. With the configuration and the materials shown above, the wall thickness under pressure decreases by about half.

[0139] Suitably, the first textile reinforcement layer 30 may be configured so as to intercept the unitary tubular member 50 upon its elongation so as to determine the maximum length.

[0140] Similarly, the second textile layer 40 may be configured so as to intercept the unitary tubular member 50 upon its enlargement or radial expansion in order to determine the maximum diameter.

[0141] To do this, the yarn of the textile reinforcement layers 30, 40 and the materials of the unitary tubular member 50 may be suitably selected, for example as described above.

[0142] Suitably, the second textile reinforcement layer 40 may be placed externally with respect to the first textile reinforcement layer 30.

[0143] In fact, because of its configuration the latter tends to restrain the axial elongation but to yield in the radial direction. By contrast, the second textile reinforcement layer 40 tends to restrain the radial enlargement but to yield in the axial direction. The cooperation of the two textile reinforcement layers 30, 40 allows to restrain the expansion of the hose in both axial and radial directions, thus determining the maximum length and diameter.

[0144] Alternatively to the knitted configuration, the first textile reinforcement layer 30 may be a weaving or knotting. FIGS. 8 and 9 show two examples of textile reinforcement woven layer, different each other for the orientation, the number and configuration of the yarns. FIG. 10 shows an example of a textile reinforcement knotted layer.

[0145] On the other hand, the second textile reinforcement layer 40 may consist of one or more spirals, in other words of one single spiral or by a braiding.

[0146] Suitably, the unitary tubular member 50 and the textile reinforcement layers 30, 40 may cooperate with each other so that under a working pressure of 2 bar the flexible hose 1 is susceptible to increase its length at least 1,5 times with respect to the its original length, preferably at least 2 times with respect to its original length and more preferably of at least 2,5 times with respect to its original length.

[0147] For example, with a hose having the structure described above and manufactured in the above materials, with an inner diameter at rest of 9 mm, outer diameter at rest of 14 mm and weight of 80 g/mt, the elongations at different Internal working pressures are provided in table 1 below.

TABLE-US-00001 TABLE 1 Working pressure (bar) Length under pressure:original length 2 2 3 2.2 4 2.4 5 2.4 6 2.5

[0148] For such a hose, the radial expansion with respect to the diameter at rest at the working pressure of 3 bars is 0.8 mm, whereas at the working pressure of 5 bar is 1 mm.

[0149] It is understood that these data may change depending on the materials and/or the features of the hose, such as the inner or outer diameter or the weight/mt thereof.

[0150] Advantageously, the radial enlargement of the inner diameter of the hose of the present invention under a working pressure of 5 bar may be less than 20% with respect to the value of the inner diameter at rest, and preferably less than 15% with respect to the value of the inner diameter at rest.

[0151] In a preferred but not exclusive embodiment, the outer layer 20 may be a protective film which weight per meter may be 3% to 10% of the total weight of the unitary tubular member 50, for example 5% of the total weight of the unitary tubular member 50.

[0152] Preferably, the film 20 may be made in accordance with the teachings of the application PCT/IB2014/067091, which is referred to for proper consultation.

[0153] Indicatively, the film 20 may have a thickness of 0.05 mm to 0.4 mm, preferably 0.1 mm-0.3 mm.

[0154] This film 20 has the purpose of protecting the underlying layers, in particular the textile layers, and to give the appearance to the hose. It is also important for the resistance to external agents and the sliding of the hose on the ground. In fact, it minimizes fouling of the hose as a result of the use on muddy grounds or in a garden.

[0155] Similarly, the intermediate layer 15 may also be a film having the same features of the outer film 20.

[0156] The extensible flexible hose 1 can be manufactured by means of a line 100, which works continuously.

[0157] The line 100 can be fed by the inner layer 10, which can for example be extruded through a first extruder 110 at the inlet 101 of the line 100.

[0158] In a per se known manner, the extruder 110 may coextrude the inner layer 10 and the detaching film 11, which may then pass through a first pair of faced rotating rollers 120 susceptible to press the hose.

[0159] Subsequently, the inner layer 10 and the detaching film 11 may pass through a first station 130 for making the textile reinforcement layer 30, so as to obtain a first semifinished product 25.

[0160] Advantageously, the station 130 may include a knitting machine 131, of a per se known type, to make the first textile knitted layer with knits of the tricot type 30, for example of the plain stich type.

[0161] Subsequently, the first semifinished product 25 may pass through a second pair of faced rotating rollers 121 susceptible to press the hose.

[0162] Advantageously, the rollers 121 may rotate faster than the roller 120. Advantageously, the ratio between the speed of the first upstream roller 120 and the one of the second downstream rollers 121 may be of 1:2 to 1:5, and more preferably of 1:3 to 1:5.

[0163] In this way, the two pairs of rollers 120, 121 continuously elongate the inner layer 10 with the inner film 11, so that the textile reinforcement layer 30 is made on the elongated inner layer 10.

[0164] Subsequently, the semifinished product 25 may pass through a second extruder 135, which extrudes a film constituting the above intermediate layer 15. Advantageously, in accordance with the teachings of the application PCT/IB2014/067091, the extrusion head 136 of the extrusion station 135 may be placed under vacuum by a vacuum pump 137, for example at a pressure of 250-400 mmHg.

[0165] The second semifinished product 25 at the outlet of the second extruder 135 passes through a third pair of faced rotating rollers 122 susceptible to press the hose. Advantageously, the rollers 122 may rotate at substantially the same speed of the rollers 121, or slightly higher.

[0166] In this way, the film 15 is extruded on the textile reinforcement layer 30 in the elongated working configuration.

[0167] Subsequently, the second semifinished product 25 at the outlet of the rollers 122 passes through a fourth pair of faced rotating rollers 123 susceptible to press the hose. Advantageously, the rollers 123 rotates more slowly than the roller 122.

[0168] Advantageously, the ratio between the speed of the fourth upstream rollers 123 and that of the third downstream rollers 122 may be of 2:1 to 5:1, and more preferably of 3:1 to 5:1.

[0169] In this way, the semifinished product 25 returns in a rest configuration, in which the layers 10, 11 and 15 have the original length and the textile reinforcement knitted layer 30 is in the rest configuration.

[0170] The semifinished product 25 in the rest configuration may be fed to a second station 140 for making thereon the textile reinforcement layer 40.

[0171] Advantageously, the station 140 may include a pair of spiraling machines 141, 142, to make a corresponding pair of spirals one in a clockwise direction and the other one in the opposite direction. The set of the two spirals constitutes the textile reinforcement layer 40.

[0172] The third semifinished product 25 at the outlet of the station 140 may then be fed to a third extruder 150, which may make the film 20. Similarly to what has been described for the second extruder 135, in accordance with the teachings of the application PCT/IB2014/067091, the extrusion head 151 may be placed under vacuum by a vacuum pump 152, for example at a pressure of 250-400 mmHg.

[0173] Upon extrusion, the inner layer 10, the intermediate film 15 and the outer film 20 adhere to each other in correspondence with the uncovered areas 13, 13 to form the unitary tubular member 50. In this way, the textile reinforcement layers 30, 40 remain embedded therein.

[0174] Thanks to the fact that the intermediate film 15 and the outer film 20 are made in accordance with the teachings of the application PCT/IB2014/067091, the same intermediate film 15 and the outer film 20 have a uniform thickness and adhere strongly to the underlying layer, as shown in FIG. 7.

[0175] This minimizes material waste and gives an optimum aesthetic finish to the hose 1.

[0176] The hose 1 thus produced may then pass through a fifth pair of faced rotating rollers 124 susceptible to press the hose.

[0177] Advantageously, the rollers 124 may rotate at substantially the same speed of the rollers 123, or slightly higher.

[0178] In this way, the second textile layer 40 and the film 20 are made on the semifinished products 25 and 25 in the rest configuration.

[0179] The detaching film 11 allows the detachment of the inner wall of the hose 1 after pressing immediately upon passage through the rollers 120, 121, 122, 123 and 124.

[0180] In a preferred but not exclusive embodiment, the second textile layer 40 and the film 20 can also be made on the semifinished product 25 in the elongated configuration. To do this, the rollers downstream the station 140 and the extruder 150 rotate faster than the ones upstream thereof, preferably in the above ratios.

[0181] In this case, the inner diameter of the elongated semifinished product 25 may preferably be brought to the inner diameter of the hose at rest by blowing air at adequate pressure.

[0182] To do this, suitable means may be provided for blowing air, of a per se known type, at the outlet 102 of the line 100.

[0183] Advantageously, the rollers 120, 121, 122, 123 and 124 may be mutually configured so that the air blown at the outlet 102 goes back up through the hose in correspondence of the rollers 121.

[0184] It is understood that in the line 100 in place of the rollers 120, 121, 122, 123 and 124 any rotary conveying device may be employed without departing from the scope of the appended claims.

[0185] From the above description, it is apparent that the invention fulfils the intended objects.

[0186] The invention is susceptible of numerous modifications and variations, all falling within the inventive concept expressed in the attached claims. All the details may be replaced with other technically equivalent elements, and the materials may be different according to requirements, without departing from the scope of the invention.

[0187] Although the invention has been described with particular reference to the attached figures, reference numbers used in the description and in the claims are used to improve the intelligence of the invention and do not constitute any limitation of the claimed scope.