"METHOD FOR OBTAINING A HOSE FOR THE CONVEYANCE OF FLUIDS AND HOSE FOR THE CONVEYANCE OF FLUIDS"

TECHNICAL FIELD OF THE INVENTION

The present invention regards a method for obtaining a hose for the conveyance of fluids, if desired so-called spiral hoses for swimming pools, i.e. hoses with a helical reinforcing element, as well as a hose for the conveyance of fluids, e.g. a spiral hose.

STATE OF THE PRIOR ART

On the so-called spiral hoses, information is usually impressed such as the name of the article, identification data of the producer or trademarks, admissible work field, e.g. operating temperature and pressure, batch number or another code for facilitating the trackability in case of product quality problems.

Such information is marked on the external surface of the hose with various techniques.

The spiral hoses are generally used for mobile applications, e.g. for pouring off, or fixed installations, also underground, e.g. hydraulic plants for the swimming pools.

The external surface of the hoses can in part be abraded, during use or also during installation, with consequent loss of the information indicated in marking.

In addition, in some cases, especially in the case of hoses for swimming pools, the hose is underground and is part of permanent circuits, so that it is of essential importance for the installation company and/or plant manager to preserve the information impressed on the hose, even for many years (e.g. for 10 years), for the trackability of the product if operational problems thereof appear.

The main techniques used for marking the hoses are:

- ink jet: the obtained marking has considerable abrasion resistance limits, or considerable limits if the same comes into contact with solvent substances;

- laser techniques: marks are obtained with optimal resistance to the solvents, but mediocre abrasion resistance. GB2072134A, GB2468664A and US2014230997A1 teach respective solutions according to the state of the art.

OBJECTS OF THE INVENTION

Main object of the present invention is to provide a new method for making a hose for the conveyance of fluids, if desired for the conveyance of water, if desired into swimming pools.

Another object of the present invention is to provide a method for making a hose which allows obtaining a very resistant marking.

Another object of the present invention is to provide a method for marking a hose which is simple and quick to achieve.

Another object of the present invention is to provide a new hose for the conveyance of fluids which has a very resistant marking.

In accordance with one aspect of the invention, a method is provided according to claim 1, 2 or 6.

In accordance with another aspect of the invention, a hose is provided according to claims 14, 15 or 19.

The dependent claims refer to preferred and advantageous embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will be more evident from the description of embodiments of a hose, illustrated by way of example in the enclosed drawings in which:

- figure 1 is a perspective view of a portion of a hose according to the state of the art as well as a step of a method for making the same;

- figure 2 is a sectional view taken along the trace II-II of figure 1;

- figure 3 is a sectional view taken along the trace III-III of figure 1;

- figure 4 is an enlarged scale view and with details in section of a part of the hose of figure 1 ;

- figures 5 to 8 are views similar, respectively, to figures 1 to 4 with reference to a method and to a hose according to one embodiment in accordance with the present invention;

- figures 9 to 12 are views similar, respectively, to figures 1 to 4 with reference to a method and to a hose according to another embodiment in accordance with the present invention;

- figures 13 to 16 are views similar, respectively, to figures 1 to 4 with reference to a method and to a hose according to a further embodiment in accordance with the present invention;

- figures 17 to 20 are views similar, respectively, to figures 1 to 4 with reference to a method and to a hose according to another embodiment in accordance with the present invention;

- figure 21 is a perspective view of a portion of a hose according to a further embodiment in accordance with the present invention;

- figure 22 is a sectional view taken along the trace XXII-XXII of figure

21;

- figure 23 is an enlarged scale view and with details in section of a part of the hose of figure 21;

- figures 24 to 26 are views similar, respectively, to figures 21 to 23 with reference to a method and to a hose according to a further embodiment in accordance with the present invention.

In the set of drawings, equivalent parts or components are marked with the same reference numbers.

EMBODIMENTS OF THE INVENTION

With reference to figures 1 to 4, a hose A is illustrated according to the state of the art, which comprises an internal tubular layer B made by means of a plurality of first coils B l of extruded plastic material as well as an external tubular layer C applied on the internal tubular layer B and obtained by means of a plurality of second coils CI of extruded plastic material.

In addition, the external tubular layer C comprises a spiral reinforcing element C2 embedded in a matrix of plastic material C3.

In the present description, an element (face, surface, etcetera) defined as internal is intended in a more internal position or in any case closer to the through axial opening AO of the hose with respect to another (external) element, while with element (face, surface, etcetera) defined as external it is intended in a more external position or in any case further away from the through axial opening AO of the hose with respect to another (internal) element.

A hose for the conveyance of fluids according to the present invention instead comprises an internal tubular layer and/or at least one reinforcing element, made for example via extrusion or injection molding or via casting, an external tubular layer or second tubular layer applied, for example via extrusion or injection molding or via casting, around the internal tubular layer and/or a third tubular layer applied around the reinforcing element and also at least one inscription or image or marking or writing which, if the hose comprises an internal tubular layer and an external tubular layer, is arranged or applied or printed inside the first tubular layer and/or inside the second tubular layer and/or between the internal tubular layer and the external tubular layer, while if the hose comprises the third tubular layer and at least one reinforcing element, the inscription or image is arranged applied or printed inside the third tubular layer.

With reference now to figures 5 to 20, several embodiments are illustrated of hose 1 according to the present invention for the conveyance of fluids, which comprises an internal tubular layer or first tubular layer 2 for example made by means of a plurality of first coils or substantially circular sections or sections with parallelogram shape 3a of a first strip 3, substantially continuous, of plastic material, e.g. thermoplastic, such as PVC containing plasticizers (plasticized PVC or PVC P), thermoplastic elastomers (TPE) of any type such as TPE-U, TPE-O, TPE-V, TPE-S, TPE-E, preferably extruded, which if provided are each placed close to or in contact with the coils adjacent thereto and constrained to each other, in particular following the cooling of the coils, which then harden and are joined or "welded" at the respective edge so as to make an internal tubular layer 2 actually made in a single piece. The internal tubular layer could also be made differently and not be provided with coils. More particularly, the first coils 3a, if provided, are applied according to a substantially helical progression on a mandrel (for example, covered with suitable detaching material set to facilitate the detachment of the hose from the mandrel at the end of the method for making the hose) that is rotatable in one sense or in the 5 other around an axis x-x, hence first applying a first coil 3a and then progressively the other first coils, one next to the other, and with the respective internal and external faces substantially aligned.

The first coils 3a are extended around a respective longitudinal extension axis x-x, which constitutes the longitudinal or main extension axis of the internal i o tubular layer 2 and of the hose 1. The first coils 3a are then substantially coaxial and, preferably, with same internal and external diameter.

The internal tubular layer 2 comprises a substantially cylindrical body with an external surface 2a and an internal surface 2b delimiting the through axial opening AO of the hose 1 into which the fluid to be transported is conveyed. The

15 external surface 2a and the internal surface 2b are substantially continuous and without interruption or offsets points, not even at the zone of constraint between possible adjacent coils 3a. In addition, the internal tubular layer 2 advantageously has thickness substantially constant for the entire extension thereof.

The hose 1 then comprises an external tubular layer or third tubular layer 4

2 o applied on or enclosing the internal tubular layer 2, and such external tubular layer 4 can be made by means of a plurality of second coils or substantially circular sections or sections with parallelogram shape 5a of a second strip 5, substantially continuous, of plastic material, e.g. thermoplastic, preferably extruded, and such second coils 5a, if provided, are each placed close to or in contact with the second

25 coils 5a adjacent thereto and constrained to each other, in particular following the cooling of the coils which then harden and are joined or "welded" at the respective edge so as to make a layer actually made in a single piece.

The strip 5 can be composed of multiple layers, if desired of different composition, among which (as indicated hereinbelow) a reinforcing element is

30 preferably arranged. The strip 5 can be made by means of one or more layers constituted by thermoplastic materials such as PVC containing plasticizers (plasticized PVC or PVC P), thermoplastic elastomers (TPE) of any type such as TPE-U, TPE-O, TPE-V, TPE-S, TPE-E.

The external tubular layer 4 then comprises a substantially cylindrical body with an external face 4a and an internal face 4b and is wound around the external surface 2a of the internal tubular layer 2, so as to cover such layer in a substantially uniform manner and to adhere to the external surface 2a for the entire extension thereof. The external face 4a and the internal face 4b are substantially continuous and without interruption or offset points, not even at the constraining zone between possible adjacent coils or substantially circular sections 5a. In addition, the external tubular layer 4 can have substantially constant thickness or variable thickness, and in such case the external face 4a would preferably assume a corrugated appearance.

The second coils or substantially circular sections 5a are extended around the longitudinal extension axis x-x, which constitutes the longitudinal or main extension axis of the external tubular layer 4 and of the hose 1. The second coils 5a are therefore substantially coaxial and preferably have same internal and external diameter.

The hose 1 also comprises at least one inscription or image or marking or writing 6 arranged or applied or printed inside the internal tubular layer 2, i.e. in the thickness and not on the perimeter faces of the internal tubular layer 2, inside the external tubular layer 4, i.e. in the thickness and not on the perimeter faces of the external tubular layer 4, and/or between the internal tubular layer 2 and the external tubular layer 4. Preferably, the inscription or image or marking or writing 6 is applied on a face 3a2 (see figures 13 to 20), 3a3, 3a4 of the first strip 3, if provided, and/or on a face 5al (see figures 9 to 12), 5a3, 5a4 (see figures 5 to 8) of the second strip 5, if provided.

If desired, the inscription or image 6 is arranged or applied or printed between two adjacent first coils or substantially circular sections 3a of the internal tubular layer 2 and/or between two second coils or substantially circular sections 5a of the external tubular layer 4.

The inscription or image 6 can indicate the name of the article, identification data of the produce or trademarks, admissible work field, e.g. operating temperature and pressure, batch number or another code for facilitating the trackability in case of hose quality problems.

More particularly, each coil 3a, 5a, if provided, can have in cross section or in any case along a plane substantially orthogonal to the longitudinal extension of the coil 3a, 5a, a face 3al, 5al facing towards the interior of the hose, a face 3a2, 5a2 facing towards the exterior of the hose 1 and two edge or side faces, a rear face 3a3, 5a3 or face distal from the end la of the hose 1 which is made first or is of initial application of the internal tubular layer 2 on the or on a rotatable mandrel or of the external tubular layer 4 on the internal tubular layer 2 and a face 3a4, 5a4, front face or proximal to the initial application end la of the hose 1, and such edge or side faces 3a4, 5a4, during use, are each side-by-side, abutted against and constrained to an edge or side face 3a3, 5a3 of an adjacent and successive coil. Preferably, each side face is side-by-side and constrained to a side face of an adjacent coil for the entire respective extension, such that the same actually collimate for the entire respective extension.

The side faces 3a3, 3a4 of the first coils 3a are, preferably, tilted with respect to the longitudinal axis x-x by an angle between 10° and 80°, for example between 10° and 30° or between 30° and 60°. The side faces 5a3, 5a4 of the second coils 5a are, preferably, tilted with respect to the longitudinal axis x-x by an angle between 10° and 80°, for example between 10° and 30° or between 30° and 60°. Such angles are evaluated along a plane in which the longitudinal axis x- x lies, i.e. a plane of the beam or beam of planes having the longitudinal axis x-x as common line.

The or each inscription or image 6 according to a first embodiment can be made on a side face 3a3, 5a3, 3a4, 5a4, so as to be arranged between the front side face 3a4, 5a4 of a first coil 3a or of a front second coil 5a and the rear side face 3a3, 5a3 of a first coil 3a or of a rear second coil 5a, i.e. adjacent and successive or applied after the first 3a or second 5a front coil (see figures 5 to 8).

Alternatively, the or each inscription or image 6 can be applied or printed on a surface 2a of the internal tubular layer 2, during use external or facing 5 towards the external tubular layer 4 or better yet on the external face 3a2 of a coil 3a which constitutes the surface 2a, if the surface 2a is composed of coils 3a side- by-side and constrained, and/or on a face 4b of the external tubular layer 4, during use internal or facing towards the internal tubular layer 2 or better yet on the internal face 5al of a second coil 5a which constitutes the face 4b, if the face 4b is i o composed of coils 3a side-by-side and constrained (see figures 9 to 20).

According to the illustrated variant, the surface 2a is composed of or defined by the sequence of aligned external faces 3a2 of the first coils 3a coupled together, while the face 4b 2a is composed of or defined by the sequence of internal faces 5al of the second coils 5a coupled together.

15 If the marking or image or inscription 6 is applied or printed on the rear side face 3a3, 5a3 or front side face 3a4, 5a4 or on a face 4b of the external tubular layer 4, during use internal or facing towards the internal tubular layer 2, such image or inscription 6 will preferably (see the subsequent paragraphs on such matter) be specular, in the sense that the same will be applied in a specular

20 manner or to the contrary, in order to be readable or visible in the correct sense or trim from outside the hose 1.

In detail, with regard to the case in which the marking or image or inscription 6 is applied or printed on the rear side face 3a3, 5a3 or front side face 3a4, 5a4, the need to apply the image or inscription 6 in a specular manner clearly

25 depends on the tilt of the faces 3a3, 5a3, 3a4, 5a4.

More particularly, if the side faces 3a3, 5a3, 3a4, 5a4 are tilted so as to have internal edge distal from the end la and external edge proximal to such end la (embodiment illustrated in the figures), then the image or inscription 6 will preferably be specular if the same is applied or printed on the front side face 3a4

30 of one or more first coils 3a and/or on the front side face 5a4 of one or more second coils 5a.

If instead the side faces 3a3, 5a3, 3a4, 5a4 are tilted so as to have internal edge proximal to the end la and external edge distal from such end la (embodiment not illustrated in the figures), then the image or inscription 6 will preferably be specular if the same is applied or printed on the rear side face 3a3 of one or more first coils 3a and/or on the rear side face 5a3 of one or more second coils 5a.

The external tubular layer 4 will preferably transparent or translucent, in a manner such that the image or marking 6 is visible from outside the hose 1. If desired, the internal tubular layer 2 can be transparent or translucent, in particular if the image or inscription 6 is formed inside the internal tubular layer 2.

The first 2 and/or second 4 layer and hence, if provided, the first 3 and/or second 5 strip can also comprise a reinforcing element 7, e.g. helical or spiral, if desired obtained by means of extrusion of plastic material, e.g. thermoplastic which can be made of a material selected from the group constituted by polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyoxymethylene (POM), acrylonitrile-butadiene-styrene (ABS), styrene acrylonitrile (SAN), polybutylenterephthalate (PBT), polyethylene terephthalate (PET), polyphenylenoxide (PPO), polyphenylene ether (PPE), polyamide PA6, polyamide PA66, polycarbonate (PC), polycarbonate/acrylonitrile-butadiene- styrene (PC/ABS) or from mixtures thereof, embedded in a matrix 2c, 4c of plastic material, and such reinforcing element 7 in particular confers to the hose 1 resistance to depression, pressure and compression.

The reinforcing element 7 is preferably enbloc or made in a single piece, e.g. obtained via extrusion, and is advantageously extended over the entire extension of the hose 1, i.e. from one end of the same to the other, but alternatively, the reinforcing element could only affect one section of the hose, e.g. not extended at the ends of the hose, or multiple reinforcing elements could be provided, placed in succession one after the other along the longitudinal axis x-x.

The reinforcing element 7 can have circular, elliptical or polygonal section.

See for such purpose, for example, the European patent EP1117958B1, in particular the description of the state of the art.

According to another variant, the inscription or image 6 can be arranged or 5 applied or printed on the external wall of the reinforcing element 7.

The coils of the reinforcing element 7 are preferably extended around the longitudinal extension axis x-x. In such case, the coils of the reinforcing element 7 are, advantageously, substantially coaxial and, preferably, with same internal and external diameter.

i o In such case, the inscription or image 6 could also be arranged or applied or printed between faces of the internal tubular layer 2 or external tubular layer 4 delimiting the housing zone of the reinforcing element 7 or on the surface of the reinforcing element 7 in contact with the internal tubular layer 2 or external tubular layer 4 (see as an example also figures 24 to 26, which regard however an

15 embodiment with only one tubular layer).

If a reinforcing element 7 is provided, in particular if the same is embedded in the external tubular layer 4, this is preferably transparent or translucent.

The reinforcing element 7 can also be opaque, but in such case the mutual 20 position between the reinforcing element 7 and image or marking 6 must be such to allow seeing the image or marking 6 from outside the hose 1.

For such purpose, the coils of the reinforcing element 7 are spaced from each other so as to define zones or windows 8a, 8b for viewing the image or marking 6 from outside the hose 1.

25 In accordance with the embodiment illustrated in figures 5 to 8, according to which one or more inscriptions or images 6 is made on a side face 5a3, 5a4, so as to be arranged between adjacent second coils 5a, the viewing windows 8a are delimited in an area between one coil and the next of the reinforcing element 7.

Same discussion applies to the case (not illustrated) in which the inscription(s) 6 30 is/are applied between adjacent first coils 3a. In such case, a good visibility is obtained of the marking or image 6, in particular if the side faces 5a3, 5a4 are tilted with respect to the longitudinal axis x-x by an angle between 10° and 80°, for example between 10° and 30° or between 30° and 60°.

If one or more inscriptions or images 6 is made on a surface 2a of the internal tubular layer 2, during use external or facing towards the external tubular layer 4 and/or on a face 4b of the external tubular layer 4, during use internal or facing towards the internal tubular layer 2 (see figures 9 to 20), then viewing windows 8b are provided, delimited between one coil and the next of the reinforcing element 7.

In both embodiments just discussed and in particular according to the embodiments illustrated in figures 9 to 20, so as to ensure the visibility of the inscription or image 6 from outside, the reinforcing element 7 has width or diameter smaller than the width of a respective strip 3, 5.

In addition, the reinforcing element 7 could be non-centrally formed relative to a respective strip 3, 5, but rather it could be formed on the side or in any case offset with respect to the main extension axis of the strip 3, 5 in which it is embedded.

In substance, the inscription or image 6 is applied or printed on a surface not directly exposed towards the external or internal walls of the hose, such that the marking cannot be removed via abrasion or via solvation.

With reference now to figures 21 to 26, hoses are illustrated according to the present invention that are similar to those illustrated with reference to figures 5 to 8, but having at least one helical reinforcing element 7 lacking an internal tubular layer and an external tubular layer though provided with only one main tubular layer or third tubular layer or main body 24 including a matrix 24c in which the helical reinforcing element 7 is embedded.

In such case, the inscription or image 6, 6a would be arranged or applied or printed inside the third tubular layer 24, i.e. between the third coils 25a (see for example figures 21 to 23) thereof, if the layer 24 is obtained by means of coils side-by-side and constrained, and/or between the tubular layer 24 and the reinforcing element 7, i.e. on faces of the third tubular layer 24 for delimiting the housing zone of the reinforcing element 7 or on the surface of the reinforcing element 7 in contact with the third tubular layer 24 (see for example figures 24 to 26).

The tubular layer 24 could be formed as indicated above with reference to the internal tubular layer 2, for example the same can be made by means of a plurality of third coils 25a of a third strip 25, substantially continuous, of plastic material, e.g. thermoplastic, preferably extruded, which are each placed close to or in contact with the third coils 25a adjacent thereto and constrained to each other, in particular following the cooling of the coils which are thus joined or "welded" at the respective edge so as to make a third tubular layer 24 actually in a single piece.

More particularly, the third coils 25a, if provided, are applied according to a substantially helical progression on a mandrel (e.g. covered with a suitable detaching material set to facilitate the detachment of the hose from the mandrel at the end of the hose making method) that is rotatable in one sense or in the other around an axis x-x, hence applying first a coil 25a and then progressively the other coils, one next to the other, and with respective internal and external faces substantially aligned.

The first coils 25a are extended around a respective longitudinal extension axis x-x, which constitutes the longitudinal or main extension axis of the tubular layer 24 and of the hose 1. The first coils 25a are thus substantially coaxial and preferably with same internal and external diameter.

The tubular layer 24 then comprises a substantially cylindrical body with an external surface 24a and an internal surface 24b delimiting the through axial opening AO of the hose 1 into which the fluid to be transported is conveyed. The external surface 24a and the internal surface 24b are substantially continuous and without interruption or offset points at the constraining zone between adjacent coils 25a. In addition, the tubular layer 24 can have substantially constant thickness over the entire extension thereof or variable thickness, and in such case the external face 24a would preferably assume a corrugated appearance.

More particularly, each coil 25a can have in cross section, or in any case along a plane substantially orthogonal to the longitudinal extension of the coil 25a, a face 25al facing towards the interior of the hose, a face 25a2 facing towards the exterior of the hose 1 and two edge or side faces, a rear face 25a3 or face distal from the end la of the hose 1 which is made first or of initial application of the tubular layer 24 on the or on a rotatable mandrel and a front face 25a4 or face proximal to the initial application end la of the hose 1, such edge or side faces 25a4, during use, are each side-by-side, abutted against and constrained to an edge or side face 25a3 of an adjacent and successive coil. Preferably, each side face is side-by-side and constrained to a side face of an adjacent coil for the entire respective extension, such that the same in fact collimate for the entire respective extension.

The tubular layer 24 is preferably transparent or translucent, in a manner such that the image or marking 6, 6a is visible from outside the hose 1.

The tubular layer 2 or 24 preferably delimits an axial opening with circular cross section.

The hose can also have other layers, which can be obtained via co- extrusion or in pre- or post-extrusion with respect to the internal or external tubular layer.

A method for making a hose for the conveyance of fluids in accordance with the present invention comprises the following steps:

- forming, for example via extrusion or injection molding or via casting, an internal tubular layer or first tubular layer 2 and/or forming, for example via extrusion or injection molding or via casting, at least one reinforcing element 7,

- applying, for example via extrusion or injection molding or via casting, an external tubular layer or second tubular layer 4 around the internal tubular layer 2 and/or applying, for example via extrusion or injection molding or via casting, a third tubular layer 24 around the reinforcing element 7. In addition, if the forming of an internal tubular layer 2 and the application of an external tubular layer 4 are provided, the method comprises a step of applying or printing at least one inscription or image 6, 6a inside the first tubular layer 2 and/or inside the second tubular layer 4 and/or between internal tubular 5 layer 2 and external tubular layer 4, while if provision is made for forming a third tubular layer 24 about the reinforcing element 7, the method comprises a step of applying or printing at least one inscription or image 6, 6a inside the third tubular layer 24.

A method according to one embodiment of the present invention for i o making a hose for the conveyance of fluids, e.g. a hose 1 as described above, comprises the following steps:

- arranging a mandrel (not illustrated in the figures) and rotating it in one sense or in the other around an axis x-x, preferably in a continuous manner, always with the same rotation sense,

15 - producing or extruding a first strip 3 of plastic material,

- applying, on the mandrel according to a spiral or helical extension, the first strip 3 of plastic material, so as to form an internal tubular layer 2 made by means of a plurality of first coils or substantially circular sections 3a of the first strip 3 constrained to each other and each placed close to or in contact with the

20 coils 3a adjacent thereto, more particularly by first applying a first coil 3a and then progressively the other coils 3a, one next to the other, and with respective internal and external faces substantially aligned,

- producing or extruding a second strip 5 of plastic material,

- during or at the end of the formation of the internal tubular layer 2, but 25 maintaining the rotation of the or of a mandrel, or in any case rotating or maintaining the rotation of the internal tubular layer 2, applying the second strip 5 of plastic material around the internal tubular layer 2 according to a spiral or helical extension, so as to form an external tubular layer 4 made by means of a plurality of second coils or substantially circular sections 5a of the second strip 5, 30 each placed next to or in contact with the second coils 25a adjacent thereto and constrained to each other.

If desired, after one or each step of application of the strips 3, 5, a step is provided for cooling and hence hardening or solidifying the same.

The method also comprises a step of applying or printing an inscription or image 6, 6a inside the internal tubular layer 2, inside the external tubular layer 4 and/or between internal tubular layer 2 and external tubular layer 4. Preferably, the method comprises a step of applying or printing an inscription or image 6, 6a on a face of the first strip 3, if provided, and/or of the second strip 5, if provided.

Preferably, application or printing step is conducted by applying or printing the inscription or image 6 on a surface 2a of the internal tubular layer 2, during use external or facing towards the external tubular layer 4 and/or on a face 4b of the external tubular layer 4, during use internal or facing towards the internal tubular layer 2.

If the inscription or image 6 is applied or printed on an external surface 2a of the internal tubular layer 2, the application or printing step can be conducted during the making of the internal tubular layer 2 or after the making thereof. For such purpose, the inscription or image 6 can be printed or applied on the strip 3 before the application of the same on the mandrel or while the coils 3a thereof are wound on the mandrel and constrained.

If instead the inscription or image 6 is applied or printed on an internal surface 4b of the external tubular layer 4, then the application or printing step would be conducted during the making of the external tubular layer 4. For such purpose, the inscription or image 6 can be printed or applied on the strip 5 before or immediately before the application of the same on the internal tubular layer 2.

Alternatively or in addition to the cases indicated above, the application or printing step can be conducted by applying or printing at least one inscription or image 6 on a face 3a3, 3a4 of a first coil 3a, such that it is subsequently arranged between two adjacent first coils 3a and/or on a face 5a3, 5a4 of a second coil 5a, such that it is subsequently arranged between two adjacent second coils 5a.

For such purpose, the image 6 can be applied or printed before or during the making of the internal tubular layer 2 in the case of application between first coils 3a and/or before or during the making of the internal tubular layer 4 in the case of application between second coils 5a.

The two layers, between which the marking is placed, are set in contact during the production or making of the hose 1.

The above-proposed description relative to the geometric/structural characteristics of the tubular layers 2 and 4 as well as of the possible strips 3 and 5 of the respective coils 3a, 5a are also applied and are intended as described for the purpose of the contents of the present patent application to a method according to the present invention.

If desired, the first 2 and/or second 4 layer and hence, if provided, the first 3 and/or second 5 strip comprise a reinforcing element 7 embedded in a matrix of plastic material.

In such case, the step of applying or printing the inscription or image 6, 6a can be conducted by applying or printing it during the making of the first 2 or second 4 layer, for example of the respective strip 3 and/or 5, provided with reinforcing element 7, on the faces of the layer 2, 4 or of the strip 3, 5 delimiting the housing zone of the reinforcing element 7 or on the surface of the reinforcing element 7 in contact with internal surfaces of the layers 2, 3 or of one or more possible strips 3, 5.

Falling within the protective scope of the present invention is also a method similar to that described above for making a hose with at least one helical reinforcing element 7, but lacking an internal tubular layer and an external tubular layer, but rather provided with only one main tubular layer or third tubular layer or main body 24 in which the helical reinforcing element 7 is embedded.

One such method for making a hose for the conveyance of fluids, if the tubular layer 24 is made starting from an extruded strip 25, comprises the following steps:

- arranging a mandrel and rotating it in one rotation sense or in the other around an axis x-x, preferably in a continuous manner, always with the same rotation sense,

- producing or extruding a third strip 25 of plastic material with at least one reinforcing element 7 at the interior, e.g. helical, and

- applying, on the mandrel, the third strip 25 of plastic material according to a spiral or helical extension, so as to form a tubular layer 24 made by means of a plurality of third coils 25a of the third strip 25 constrained to each other and each placed close to or in contact with the third coils 25a adjacent thereto.

The method also comprises a step of applying or printing at least one inscription or image 6, 6a inside the third tubular layer 24, i.e. between the third coils 25a (see for example figures 21 to 23) or on faces of the third tubular layer 24 delimiting the housing zone of the reinforcing element 7 or on the surface of the reinforcing element 7 in contact with the third tubular layer 24 (see for example figures 24 to 26).

The step of applying or printing at least one inscription or image 6, 6a is conducted before or during the making of the third tubular layer 24, i.e. before the application of the third strip 25 on the mandrel or during such application step.

The step of producing or extruding a third strip 25 of plastic material with a helical reinforcing element 7 at the interior can be conducted by simultaneously extruding an external matrix and a reinforcing element 7 within the same or first extruding the reinforcing element 7 and then extruding, or making around the same, a matrix for containing or covering the reinforcing element.

Clearly, at the end of the above-described steps, the obtained hose is removed from the mandrel.

The techniques usable for applying the inscription can be:

- inkjet printing;

- laser techniques, for example via incision, removal of color, foaming, toning, carbonization;

- flexographic techniques, for example flexography with UV ink;

- techniques which provide for hot transfer application;

- hot surface incision; and - hot transfer belts with characters.

As it will be understood, with a hose and a method in accordance with the present invention, the inscription or image or marking is inside the hose, so that the same is protected from possible abrasions from dragging or from solvation.

With reference to the above discussed patent documents, GB2072134A teaches a method for applying a marking on a hose, according to which a negative marking is applied on a film made of transparent material and then the latter is applied on a base hose.

A protective layer or a nylon enclosing strip can be applied above the film of transparent material, but at the end of the method the protective layer and the enclosing strip are removed. Moreover, such layers are not made of transparent or translucent material and it would be groundless to obtain them in such manner, since the same should be removed and thus, in use, they would not conceal the marking.

Therefore, this document does not absolutely teach a transparent or translucent external tubular layer, taking also into account that the film of transparent material does not include a hose or tubular layer. This is clearly visible even in the figures of GB2072134A.

Thus, such English patent application does not teach a hose with a plurality of tubular layers having a marking between the tubular layers or in the tubular layers.

GB2072134A in fact teaches a hose with one tubular later only, and having a marking applied outside such tubular layer and with a film protective the marking, but the same document does not teach to form the marking between two tubular layers with a transparent or translucent layer for rendering the marking visible from the outside.

Moreover, the method taught by GB2072134A is not even applicable in a multilayer hose, if it is taken into account that the presence of the film and the marking would prevent from occurring a proper application and adhesion between two concentric layers of the hose itself. So far as instead GB2468664A is concerned, it relates to a method of applying a marking according to which an outer tubular layer is applied to an inner tubular layer and subsequently a portion of the outer tubular layer is removed and then a label is applied in the thus obtained cavity, which label is 5 possibly later covered with a transparent layer.

Clearly, this document does not teach a step of applying or molding a wording or image in a tubular layer and/or between an inner tubular layer and an outer tubular layer as provided by the present invention.

Modifications and variations of the invention are possible inside the l o protective scope defined by the claims.