DESCRIPTION

Field of the invention

The present invention generally regards the technical field of flexible hoses, and it particularly regards an apparatus and a method for manufacturing a flexible hose reinforced with at least one textile layer.

The invention also regards a reinforced flexible hose that can be manufactured by means of the aforementioned method and apparatus.

Definitions

In the present document, the expression "textile yarn" or its derivatives is used to indicate an elongated thread-like element of any shape and made of any material, as long as the dimension of the length considerably prevails over. For example, the textile yarn may be a polymeric yarn, which may have a unitary structure or it may in turn consist of the joining of several elementary yarns, or a textile band of any shape.

In the present document, the expression "knitted textile layer with chain stitches of the tricot type" and the like is used to indicate a layer consisting of at least two yarns or groups of yarns arranged on the load-bearing layer and mutually interweaved ("knitted") to form a plurality of chain stitches of the "tricot" type. Preferably, the "knitted textile layer with chain stitches of the tricot type" may be arranged on the layer which supports it so as to leave the portions thereof free.

In the present document, the expression "chain stitches of the tricot type" and the like is used to indicate the portion of textile yarn (or a set of yarns grouped in a single yarn) which is intertwined with adjacent wires to form a generally annular-shaped loop.

In the present document, the expression "row of stitches" and the like of a knitted textile layer with chain stitches of the tricot type is used to indicate the line defined by the "chain stitches of the tricot type" concatenated to each other.

In the present document, the expression "courses of stitches" and the like of a knitted textile layer with chain stitches of the tricot type is used to indicate the portions of textile yarn (or set of yarns grouped into a single yarn) mutually connecting two consecutive "chain stitches of the tricot type" along the same yarn.

In the present document, the expression "providing" or its derivatives is used to indicate the preparation of an element of interest to a process step of interest, thus including any preventive treatment aimed at the optimal execution of the step of interest, from simple collection and possible storage to heat and/or chemical and/or physical pre-treatments and the like.

In the present document, unless otherwise specified, the expression "inclination" or its derivatives of a textile layer or part thereof is used to indicate the inclination of the textile layer or part thereof with respect to the axis of the hose.

State of the Art

Flexible hoses comprising an inner layer susceptible to come into contact with the liquid to be transferred, an outer layer susceptible to be grasped by a user and, interposed therebetween, a knitted textile layer with chain stitches of the tricot type, are known.

The European patent EP-B1-062S776, on behalf of the Applicant, discloses an example of such hose, in which the rows of stitches and courses of stitches of the textile layer have mutually opposite inclinations with respect to the axis of the hose.

Besides having good anti-torsional properties, good malleability and relatively high burst pressure, such type of flexible hoses is also simple and quick to manufacture in line.

However, such known type of flexible hoses reveals the drawback lying in excessive dilatation under pressure, which is potentially dangerous especially at the joints of a fitting. As a matter of fact, in such point the excessive dilatation can lead to liquid leakages and/or failures.

Furthermore, the internal pressure stretches the textile yarns of the knitted layer in particular at the interweaving points between the stitches, which become potential weak points of the hose over time.

Still, such known flexible hoses can be improved in terms of aesthetic appeal and durability.

Summary of the invention

An object of the invention is to at least partly overcome the drawbacks outlined above, by providing an apparatus and/or a method for manufacturing a reinforced flexible hose and/or a reinforced flexible hose that is highly efficient and relatively economic.

Another object of the invention is to provide an apparatus and/or a method that allow to manufacture a reinforced flexible hose in a relatively simple and quick manner.

Another object of the invention is to provide an apparatus and/or a method that allow to manufacture a reinforced flexible hose that is durable over time.

Another object of the invention is to provide an apparatus and/or a method that allow to manufacture a reinforced flexible hose with high aesthetic appeal.

These and other objects that will be more apparent hereinafter, are attained by the apparatus, the method and the reinforced flexible hose according to what is described, illustrated and/or claimed herein.

Advantageous embodiments of the invention are defined according to the dependent claims.

Brief description of the drawings

Further characteristics and advantages of the invention will be more apparent in light of the detailed description of some preferred but non-exclusive embodiments of the invention, illustrated by way of non-limiting example with reference to the attached drawings, wherein:

FIG. 1 is a schematic view of an embodiment of apparatus 10 for manufacturing the reinforced flexible hose 1;

FIG.2 is a schematic view of an embodiment of a knitting station 12, with in FIG.2A is a front view of the knitting unit 22 part of such station;

FIG. 3 is a schematic view of an embodiment of a flexible hose 1 with a reinforcement layer 4;

FIG. 4 is an enlarged view of the reinforcement layer of the reinforced flexible hose 1 of FIG.1. Detailed description of a preferred embodiment

With reference to the aforementioned figures, the flexible hose according to the invention, indicated in its entirety with reference number 1, may consist of an inner load-bearing tubular layer 2, which for example may be made of plasticised PVC or an elastomer or a thermoplastic elastomer (TPE), an outer cover tubular layer 3, which may for example be made of plasticised PVC or an elastomer or a thermoplastic elastomer (TPE) and, interposed therebetween, at least one textile layer 4 which may for example be made of polyester yarn.

The inner load-bearing tubular layer 2, which may define the axis X of the hose 1, may be designated to come into contact with the liquid to be transferred, while the outer cover layer 3 may be designated to be grasped by a user.

In a preferred but non-exclusive embodiment of the invention, the hose 1 may comprise a textile layer 4 which may be of the type knitted with chain stitches of the tricot type, indicated with 6, 6', 6"... Thus, the textile layer 4 may have any number of rows of stitches 7, 7' and courses of stitches 8, 8'.

Even for the sake of simplicity, described in the present document is a single textile layer made of a single knitting unit, it is clear that the hose may include several textile layers provided by one or more knitting units. More generally, other additional layers, both textile and polymeric, may also be provided for between the aforementioned layers of the hose 1, without departing from the scope of protection outlined by the attached claims.

In the reinforcement textile layer 4 the courses of stitches 8, 8' may be equally spaced from each other, same case applying to the rows of stitches 7, 7'.

In other words, the distance R between two consecutive courses of stitches 8, 8' will be the same for all the courses of stitches of the reinforcement textile layer 4. Likewise, the distance F between two consecutive rows of stitches 7, 7' will be the same for all rows of stitches of the reinforcement textile layer 4.

Advantageously, the rows of stitches 7, 7' may be grouped into a first group of a rows of stitches 7 with narrow configuration and a second group of row of stitches 7' with wide configuration alternating with respect to each other.

Even though in the embodiment illustrated herein the rows of stitches are grouped into four groups with narrow configuration and four groups with wide configuration and each group consists of a single row of stitches, it is clear that the groups may vary in number and each group may consist of any number of rows of stitches without departing from the scope of protection of the attached claims.

Suitably, the row of stitches 7 of the first group may be arranged adjacent to the row of stitches 7' of the second group.

It is clear that in case of groups with several rows of stitches at least one row of the first group may be arranged adjacent to at least one row of the second groups, without departing from the scope of protection of the attached claims.

More in particular, the row of stitches 7 with narrow configuration may have a distance D1 between the mutual interweaving points 16', 16" of two consecutive stitches 6, 6', 6" considerably smaller than the distance D2 between the two mutual interweaving points 160', 160" of two consecutive stitches 6, 6', 6" of the row of stitches 7' with wide configuration.

Suitably, the ratio between the ratio between the distances D1 and D2 mentioned above may be at least 1 : 4, preferably at least 1 : 5 and even more preferably at least 1 : 6.

This will allow obtaining a hose having a good burst pressure, absolutely comparable to classic knitted hoses of the prior art considering the same number of textile yarns, and that maintains good malleability.

On the other hand, considering the same number of textile yarns, it has a markedly smaller number of stitches, this meaning a smaller number of potential breaking points and thus greater durability and reliability over time.

Furthermore, such characteristic entails greater control of the dilatation of the hose under pressure, thus avoiding problems related to potential leakages and failures at the fittings of the knitted hoses of the prior art.

Basically, the flexible hose 1 described above maintains all the advantages of a textile-reinforced hose and it also has a low radial dilatation, typical of the wired- reinforced hoses.

Furthermore, the visual aspect of the knitted layer 4, is particularly pleasant, hence conferring a high aesthetic appeal to the flexible hose 1. To this end, the outer layer 3 may preferably be made of optically transparent material or configured to expose the underlying textile layer 4 to view and/or touch.

In a preferred but non-exclusive embodiment, the rows of stitches 7, 7' and the courses of stitches 8, 8' may have substantially opposite inclinations a, b with respect to the axis X of the hose, so that the textile layer 4 has an overall spiral extension along the hose 1.

On the other hand, the textile layer 4 may be configured as a classic tricot stitch, with rows of stitches 7, 7' substantially parallel to the axis of the hose and courses of stitches 8, 8' substantially inclined with respect to the axis X.

On the other hand, the textile layer 4 may be configured according to the disclosures of the international patent application number PCT/IB2017/058257, on behalf of the Applicant, with rows of stitches 7, 7' substantially inclined with respect to the axis of the hose and courses of stitches 8, 8' substantially parallel to the axis X.

The flexible hose 1 may suitably also be particularly even though not exclusively used as an irrigation hose for domestic purposes, for example like the so-called garden hose.

On the other hand, depending on the configuration of the textile layer, and in particular even though not exclusively the pitch and/or the amount per linear metre and/or the textile yarns count, the flexible hose 1 may reach relatively high burst pressure, and thus be suitable for use for various purposes.

Advantageously, the first and the second material of the inner 2 and outer 3 tubular layer may be of the polymeric or elastomeric or thermoplastic polymeric type.

The first and the second material may suitably be both polymeric with a plasticised PVC (polyvinyl chloride)-based matrix. Both the first and the second polymeric material may have a Shore A hardness comprised between 40 and 100, preferably comprised between 60 and 90.

On the other hand, the first and the second material may be thermoplastic elastomers, for example TPE-U, TPE-O, TPE-V, TPE-S, TPE-E, or elastomers, come for example natural rubber, butyl rubber, EPDM rubber, Chloroprene rubber, SBR rubber, silicone rubber.

It is clear that even though hereinafter reference will be made to plasticised PVC for the sake of simplicity, the first and the second material of the inner 2 and outer 3 tubular layers may be of any type without departing from the scope of protection of the attached claims.

The flexible hose 1 may be obtained by means of the apparatus 10 illustrated in FIG.1.

Initially, introducing plasticised PVC into a first extruder 11 will allow to extrude, in a per se known manner, the inner tubular layer 2, designated to act as the load-bearing layer.

Then, the load-bearing layer will be introduced into a knitting station 12, suitable for obtaining - on the inner load-bearing tubular layer 2 - the textile layer 4.

Lastly, the reinforced tubular semi-finished element 13 thus obtained will be introduced into a second extruder 14, loading it from above with plasticised PVC, so as to extrude - in a per se known manner, on the upper surface of the reinforced tubular semi-finished element 13 - the cover layer 3, obtaining the finished hose 1 at the outlet 24 of the second extruder 14.

With the aim of obtaining textile layers 5, the knitting station 12 may comprise an inlet 21 for the inner load-bearing tubular layer 2 coming from the first extruder 11, a circular knitting unit 22 and an outlet 24' for the reinforced tubular semi-finished element 13, designated for the second extruder 14.

The arrow W in FIG. 2 indicates the direction of advancement of the load- bearing layer 2 through the circular knitting station 12, and it also defines a longitudinal axis coincident with the axis X of the hose. Externally to the knitting station 12 there may be provided per se known means for pulling the hose along the advancement line X.

The circular knitting unit 22 may have a set of needles 26, 27, fixed in a needle-holder cage 28, which are operatively connected to a distributor 38 and - by means of a per se known tensioning and idler means - a set of reels 32 of textile yarn 34, mounted on reel-holder supports 36.

In use, in a per se known manner the needles 26, 27 may pick up the respective textile yarn 34 from the corresponding reel 32 so as to intertwine it with the adjacent yarns to form stitches 6 of the tricot type.

The needles 26, 27 may be mounted on the needle-holder cage 28 preferably around the axis X, so as to form the textile layer 4 on the outer surface of the advancing inner load-bearing tubular layer 2.

As particularly illustrated in FIG. 2, the needles 26, 27 may have respective ends 26', 27' operatively coupled with cam means, generally indicated with 50, to promote the reciprocating motion thereof along respective directions substantially parallel to the longitudinal axis X.

In a per se known manner, the rotation of the cam means 50 will promote the reciprocating linear motion along axes parallel to axis X.

Furthermore, the possible rotation of the needle-holder cage 28 will drive the needles 26, 27 in rotation around the axis X.

Suitably, the number of knitting needles 26, 27 may vary in number, same case applying to the number of reels 32.

For example, 8 reels of textile yarn and 8 knitting needles can be used as regards the hose illustrated in FIGS.3 and 4.

In a per se known manner, the distributor 38 may have a minimum number of seats 38' equal to the number of reels 32 and/or to the number of crests of the cam means 50. Suitably, the number of reels 32 and the number of crests of the cam means 50 may be equal.

For example, as regards the hose illustrated in FIGS.3 and 4 each of the seats 38' of the distributor 38 may be operatively connected with a respective reel 32 so as to receive the relative textile yarn 34, with a number of reels 32 equal to the number of seats 38' of the distributor 38.

As mentioned above, as regards the hose illustrated in FIGS.3 and 4, 8 reels of textile yarn and a distributor 38 having 8 seats 38' could be used, each yarn being connected with a respective seat.

With the aim of obtaining the effect illustrated in FIGS.3 and 4, the needles 26, 27 may be grouped into a predetermined number of groups, for example four groups, equally distributed on the needle-holder cage 28. As particularly illustrated in FIG. 2A, each group may include two or more needles 26, 27 equally spaced from each other by a first mutual angular distance dl.

Furthermore, the two consecutive groups may advantageously have a second predetermined mutual angular distance d2 greater than the distance dl.

More in detail, the ratio between the angular distance dl and the angular distance d2 may be greater than 1.5, preferably comprised between 1.5 and 3 and more preferably comprised between 1.5 and 2.5.

For example, as regards the hose illustrated in FIGS.3 and 4, the needles may be grouped into four groups of two needles, spaced from each other by about 30°. The angular distance d2 between two groups of needles may be of about 60°.

In other words, preferably, each group may contain the same number of needles spaced by the angular distance d2, and each group may have a distance from the previous and subsequent group equivalent to the angular distance dl.

The mutual inclination of the rows of stitches 7, 7' and courses of stitches 8, 8' may be adjusted by the relative rotary motion of the needles 26, 27 and that of the needles 32 and of the distributor 38.

For example, as regards the hose illustrated in FIGS.3 and 4, the needles 26, 27 may rotate by means of special actuators acting on the needle-holder cage 28 around the axis X in a predetermined direction Vi, while the distributor 38 and the reels 32 may rotate by means of special actuator means around the axis X in a predetermined direction V ₂ opposite to the direction Vi.

On the other hand, in order to obtain a classic knitted hose of the tricot type, the needles 26, 27 may remain substantially stationary while the distributor 38 and the reels 32 may rotate.

Still, in order to obtain a textile layer 4 configured according to the disclosures of the international patent application number PCT/IB2017/058257, on behalf of the Applicant, with the rows 7, 7' substantially inclined with respect to the axis of the hose and courses of stitches 8, 8' substantially parallel to the axis X, the needles 26, 27 may rotate while the distributor 38 and the reels 32 may remain rotatably stationary.

Per se known actuator means, for example a motor with relative belt, may be provided with the aim of promoting the rotation of the aforementioned components.

In light of the above, it is clear that the invention attains the pre-set objectives.

The apparatus and the method of the flexible hose 1 are susceptible to numerous modifications and variants all falling within the inventive concept outlined in the attached claims. All details can be replaced by other technically equivalent elements, and the materials can be different depending on the needs, without departing from the scope of protection defined by the attached claims.

It is also clear that in a further aspect, there may be provided for a flexible hose reinforced with at least one polymeric or elastomeric inner load-bearing layer, at least one polymeric or elastomeric outer layer and a single textile layer interposed therebetween with chain stitches of the tricot type in which the courses of stitches are substantially parallel to each other and to the axis of the hose and the rows of stitches are inclined with respect to the axis of the hose.