WO2012038895A1

WO2012038895A1 - Machine, method for making reinforced irrigation pipes and pipe thus obtained

Info

Publication number: WO2012038895A1
Application number: PCT/IB2011/054122
Authority: WO
Inventors: Alessandro Mezzalira; Alessandro Cegalin; Valentino Vigolo
Original assignee: Fitt S.P.A.
Priority date: 2010-09-20
Filing date: 2011-09-20
Publication date: 2012-03-29
Also published as: ES1078458U; ITRA20100029A1

Abstract

A machine (15) for making irrigation or garden pipes (1) of the type having reinforcement stitchwork (3, 3A, 3B, 9) and a longitudinal axis (X), the machine comprising a first group (16) and a second stitchwork group (17), substantially similar to each other, except for the stitchwork and thread distribution head (20, 21), and arranged facing one another according to the axis (X) of the pipe (1), each stitchwork group (16, 17) processing a set of threads (4, 5) that form the reinforcement stitchwork (3, 3A, 3B, 9) the stitchwork groups (16, 17) comprising a respective stitchwork head (20), provided with needles (35) and with a distributor (33) for the threads, and a head stitchwork (21) equipped with only the distributor (34) for threads, the heads (20, 21) rotating with opposite rotation directions and cooperate with one another so as to form a reinforcement stitchwork (3, 3A, 3B, 9) with a single layer with a set of threads (4, 5) with opposite helicoidal extension; the invention also foresees a method for making the irrigation or garden pipe and the pipe thus obtained.

Description

"MACHINE, METHOD FOR MAKING REINFORCED IRRIGATION PIPES AND PIPE THUS OBTAINED" TECHNICAL FIELD OF THE INVENTION

The present invention concerns a machine, a method for making reinforced irrigation pipes and the pipe thus obtained. Specifically, the present invention concerns a machine, a method for making an irrigation pipe with a reinforcement stitchwork with a single layer and the pipe itself.

BACKGROUND OF THE INVENTION

From French utility certificate FR-2 849 148 an irrigation pipe is known comprising an inner pipe, a reinforcement stitchwork of the so called "tricot" type with chains, or loops, with axis parallel to the longitudinal axis of the pipe and with a further outer protection pipe. The lines of threads that constitute the reinforcement stitchwork are progressively moved diagonally according to inclined directions opposite with respect to the longitudinal axis of the pipe, forming two opposite helices.

Thanks to these characteristics, the reinforcement stitchwork of the pipe should be resistant so as to withstand relatively high pressure, the pipe should not twist when pressurised water is introduced, moreover, it should not be subject to squashing, that is to say forming folds, knots or chocking due to twisting of the pipe.

However, in FR-2 849 148 there is no indication of the geometrical and constructive parameters of the reinforcement stitchwork, like for example the pitch, the inclination and the density of the threads per unit length. It is not therefore possible to obtain the desired results both as far as the pressure resistance of the pipe, and the anti-twist properties are concerned.

Moreover, in FR-2 849 148 neither the method for making the pipe, in particular the reinforcement stitchwork, nor the machine for obtaining such a stitchwork is described.

PURPOSES OF THE INVENTION.

One purpose of the present invention is to improve the state of the art. Another purpose of the present invention is to have a reinforced irrigation pipe with resistance and anti-twist characteristics that are improved with respect to the state of the art. Another purpose of the present invention is to have a reinforced irrigation pipe that is cost-effective to make. Another purpose of the present invention is to have a method for making a reinforced irrigation pipe with resistance and anti-twist characteristics that are improved with respect to the state of the art. Yet another purpose of the present invention is to have a method for making a reinforced irrigation pipe that is simple and cost-effective. Another purpose of the present invention is to have a machine for making a reinforced irrigation pipe with resistance and anti-twist characteristics that are improved with respect to the state of the art. A further purpose of the present invention is to have a machine for producing a reinforced irrigation pipe that is versatile and fast at making pipes.

In accordance with one aspect of the present invention, a reinforced irrigation pipe is foreseen according to what is specified in claim 13.

In accordance with another aspect of the present invention, a method for making a reinforced irrigation pipe is foreseen according to what is specified in claim 9.

In accordance with a further aspect of the present invention, a machine for making a reinforced irrigation pipe is foreseen according to what is specified in claim 1. The dependent claims refer to preferred and advantageous embodiments of the invention .

BRIEF DESCRIPTION OF THE DRAWINGS. Further characteristics and advantages of the invention shall become clearer from the detailed description of a reinforced irrigation pipe, a method and a machine for making it, illustrated as an indication and not for limiting purposes, in the attached drawings, in which:

figure 1 is a front schematic view, with some parts removed and others enlarged, of an irrigation pipe according to the present invention;

figure 1A is a front schematic view, with some parts removed and others enlarged, of another version of the irrigation pipe according to the present invention;

figure 2 is a front schematic view, with some parts removed and others enlarged, of yet another version of the irrigation pipe according to the present invention;

figures 3A and 3B illustrate front schematic views, with some parts removed and others enlarged, of other versions of the irrigation pipe according to the present invention;

figure 4 is a schematic view of a machine for making the irrigation pipes according to the previous figures;

figure 5 is a schematic view of a portion of the machine for making the irrigation pipes according to the previous figures;

figures 6-9 are schematic views of a portion of machine according to the present invention which illustrate some manufacturing steps of the irrigation pipe according to figure 1; .

figure 10 illustrates a diagram of a portion of machine according to the present invention for making another version of the pipe according to figure 1A;

figures 11-13 are schematic views, of a portion of machine according to the present invention, which illustrate some manufacturing steps of the irrigation pipe according to figure 2 .

EMBODIMENTS OF THE INVENTION.

Figure 1 illustrates a first version of the irrigation or garden pipe 1 according to the present invention .

The irrigation pipe 1 has a longitudinal axis "X" and comprises an inner pipe 2 , intended to come into contact with irrigation water or with other liquids, and is therefore made in a material that is suitable for such a purpose: for example PVC (polyvinyl chloride) , PE (polyethylene) or an elastomer such as SBR rubber (styrene -butadiene rubber) , nylon, etcetera

According to what is illustrated in figure 1, a reinforcement stitchwork 3 with a single layer is fitted above the inner pipe 2. The stitchwork 3 is made with at least two sets of threads: one set 4, indicated in white in figure 1, and one set 5, indicated in black in figure 1.

A series of threads 4 has a helicoidal extension around the inner pipe 2 with a helix angle "A" with respect to the axis "X" of the pipe 1, whereas the other set of threads 5 has a helicoidal movement that is opposite to the helicoidal movement of the first set of threads 4. The set of threads 5 also has a helix angle "B" with respect to the axis "X" of the pipe 1 that is opposite to the helix angle "A" .

As illustrated in figure 1, the sets of threads 4 and 5 cross over each other and intersect one another, but always forming a single layer of reinforcement stitchwork.

The helix angles "A" and "B" are, moreover, function of the physical-mechanical characteristics of the threads of the reinforcement stitchwork 3, for example the modulus of elasticity and the percentage of elongation of the material or of the thread itself, for example in the case in which it is twisted thread which forms the stitchwork, of the pressure resistance characteristics and anti-twist properties which are desired to be given to the pipe 1. For these last two characteristics, we also speak about malleability of the pipe which is promoted by how the stitchwork 3 is made. The level of malleability of the stitchwork is directly proportional to the number of knots, i.e. the loops or chains, per unit surface of the stitchwork 3, and therefore to the bending or choking reaction of the pipe, while contrarily, the resistance to the bursting of the pipe is in inverse proportion to the number of knots, due to the fact that by increasing the pressure inside the pipe, the knots, i.e. the loops, tighten and allow an increased dilation of the pipe .

In particular, if the threads of the two sets are made with the same textile material, for example polyamide fibres, or the like, the helix angles "A" and "B" can substantially be equal to one another and comprised in a range of between 35 and 75 degrees, preferably in a range of between 50 and 60 degrees and even more preferably are 55 degrees.

"^" Above the stitchwork 3 there is an outer pipe, i.e. an outer covering protection or sheath 8 that protects the stitchwork 3 and the pipe 1 as a whole, such an outer pipe is generally made from transparent plastic material or rubber, but it can also be made from other flexible and protective non transparent material.

Figures 1A and 2 illustrate other versions of the pipe 1 comprising an inner pipe 1, an outer pipe or outer covering sheath 8, analogous to those of the previous version and reinforcement stitchworks 3A, 3B that are different from the previous reinforcement stitchwork 3, but substantially similar to one another.

In particular, in the pipe of figure 1A, there are less chains or loops 6 , they are, that is to say, halved with respect to the version of figure 1, because the chains or loops 6 of the sets of threads are alternatively replaced by rectilinear thread portions that therefore decrease the malleability of the stitchwork.

In figure 2, the chains or loops 6A, 7A, are made from both the sets of threads 4, 5 and are therefore identical to one another. It should be noted that the reinforcement stitchwork 3B has a malleability that is analogous to that of the pipe of figure 1, because it has a similar number of chains or loops per unit surface of the stitchwork.

Indeed, without affecting the inclination angle parameters, or spiral, and the count of the thread, the malleability of the stitchwork is directly proportional to the number of loops made per unit surface by a single thread - because the thread of the loops can yield and it allows a variation of the diameter of the pipe under the pressure of the inner fluid which passes through it - and it is in inverse proportion to the resistance to the pressure of the pipe, because a greater number of chains or loops, decreases the containment of the pressure of the pipe.

Of course, it is possible to control and adj.ust the rigidity, or the yield of the reinforcement stitchwork by varying the parameters: materials, dimensions of the thread and geometry of the stitchwork, type of stitchwork, as previously indicated for the reinforcement stitchwork of the tubes of figures 1, 1A and 2. In figures 3A and 3B other versions of the pipe 1 are illustrated comprising an inner pipe 2, an outer pipe or outer covering sheath 8, that are analogous to those of the previous version and comprising reinforcement stitchworks 9, that are different from the previous reinforcement stitchworks 3, 3A and 3B, which have some loops or chains 10 that are arranged with their "Y" axis that is inclined by an angle, which as an example can be comprised between more or less 10 degrees. The inclination of the "Y" axes of the chains as well as the dimensions of the loops themselves, contribute towards defining the pressure resistance characteristics and the anti-twist properties of the pipe 1.

It should also be noted that in order to obtain such an inclination of the chains it is sufficient to give a certain rotation speed - relatively low - to the group of needles, and increase the speed in a corresponding manner, i.e. the same speed, to the distributor of threads which rotates in the same direction as the group of needles and decrease the speed in a corresponding manner, i.e. the same speed, to the distributor of threads which rotates in the opposite direction with the group of needles. In such a way, it is ensured for there to be a perfect relative movement between the group of needles and the thread distributors.

As a non limiting example we provide, for pipes with a diameter of around 15-30 mm, some dimensions of the stitchwork which are valid for the versions of figures 1-3: the loops 6, 7 and 13, 14 have a length ^WH" of between 3 mm and 8 mm and a width "L" of between 2 mm and 5 mm.

Figure 4 illustrates a schematic view of a machine 15 for making reinforced pipes according to the present invention.

The machine 15 comprises a first group 16 and a second stitchwork group 17, substantially similar to each other and arranged facing one another according to the axis X of the pipe being made. Each stitchwork group 16, 17 processes a set of threads 4, 5 that form the reinforcement stitchwork. Since the sets of threads have an opposite helicoidal extension, also the stitchwork groups 16 and 17 which form the sets of threads have opposite rotation directions.

For such a purpose, the machine 15 comprises some motor means 18 which can be arranged in the base block of one of the stitchwork groups 16, 17. The stitchwork groups 16 and 17 comprise a respective stitchwork and thread distribution head 20 and 21. The stitchwork head 20, being the only one that bears the needles 35, actually carries out the stitchwork together with its thread distributor 33 rotating in one direction, whereas the head 21 comprises only one thread distributor 34 rotating in the opposite direction of the other distributor 34. Such heads 20, 21 are set in rotation with opposite directions, perfectly synchronised with one another with a 1:1 ratio, through transmission means 19 which transmit the motion of the motor means 18 to the same heads 20, 21. It should be noted that in order to invert the motion of one of the heads, motion inversion means are foreseen, for example a mechanical inversion gear box 22.

Overall, the transmission means 19 must ensure a very precise relative rotation of the heads 20, 21 which must move perfectly synchronised, as already mentioned above in the opposite direction with 1:1 ratio, so as to obtain the reinforcement stitchworks according to the present invention. It is also foreseen for there to be a device for the fine adjustment of the coupling of the two heads 20, 21 which makes it possible to vary even minimally the relative angular position of the two heads 20, 21. Such a device can comprise a mechanical adjustment mechanism which is actuated manually during the initial moment of preparing the production of a certain type of pipe, or such an adjustment mechanism can be assisted by servo-motors, for example electrical motors, so as to be able to carry out the adjustment through an electronic control unit (not illustrated) .

As an alternative to the transmission of the mechanical type, the transmission means 19 can be of the electrical type, making a so-called electrical axis between the stitchwork groups 16 and 17, through two electrical motors for actuating the respective stitchwork groups 16 and 17 and devices of the encoder type so as to verify the relative angular position between the two heads 20, 21.

Each stitchwork group 16, 17 also comprises a respective advancement device not illustrated so as to advance according to an advancement direction V of the inner pipe 2, above which the reinforcement stitchwork is made, and possibly the advancement direction can be in the opposite direction. Such advancement devices are coordinated and synchronised with one another and are not described in further detail since they are of the known type. Each stitchwork group 16, 17 also comprises supports 23, 24 for the shafts which bear the heads 20 and 21. As can be seen in figure 5 illustrating more in detail the group of the heads 20 and 21, each head comprises a reel-holding plate 25, 26 for a set of reels 27, 28 of thread 29, 30 suitable for making the reinforcement stitchwork. The sets of threads.4, 5 are formed by the threads 29, 30 and are respectively guided through tensioners 31, 32 and distributors 33, 34 up to a group of needles 35 that is shared by the two sets of threads 4, 5.

According to modalities that are described in more detail in the rest of the description, each needle 35 can slide within a respective guide which is in a stationary drum 36 and that allows an axial movement of the needles themselves. The needles 35, of the known type, comprise a closing hook and tongue that are suitable for crossing over and catching a thread, and are set in alternate axial motion by means of a cylinder 37, equipped with a groove with a regular undulated profile equipped with crests and valleys, which allow the aforementioned alternate movement of the needles. For example, such an undulated groove can have a sinusoidal profile, but of course also profiles that are different from the sinusoid can be foreseen as long as they determine an alternate movement of the needles. For the sake of simplicity of the figures the undulated groove is represented with a segmented line. The aforementioned cylinder 37, as illustrated in figure 5, rotates in accordance with the plate 25 and the distributor 34. The relative movement between the drum 36, which is stationary, and the cylinder 37 rotating with the undulated groove, determines the axial alternate movement of the needles 35. Of course, the needles 35 can be set in alternate axial movement even with other mechanisms of the mechanical or electric or magnetic or pneumatic type etcetera, for example with a crank-rod mechanism or through electric linear motors.

From figure 5 it should be noted that between the distributors 33, 34 for the sets of threads 29, 30 support and centring means are arranged, for example a bearing 38, since the aforementioned distributors 33, 34 face each other a short axial distance apart and counter-rotate, and for such a reason it is better if they are suitably supported and centred with one another and are furthermore guided so as to avoid any scraping or impact between them.

Figures 6-9 schematically illustrate two subsequent steps of forming the reinforcement stitchwork 3 illustrated in the pipe of figure 1, for greater clarity the reinforcement stitchwork 3 which is tubular, has been illustrated flattened on a plane, just like the plates 25, 26 and the distributors 33, 34.

In the illustrated example, a stitchwork is presented, made with eight overall threads, of which four are represented in white, with helical extension to the right and four, are represented in black, with helical extension to the left; the respective four white and black reels 27, 28 are on the two plates 25, 26 which counter-rotate in the same direction as the respective distributors 33, 34.

Of course, the number of threads and of the respective reels, holes in the distributor, needles, etcetera, can be any, and the number of eight that is described and illustrated here is only given as a non limiting example.

Figures 6-9, furthermore schematically represent also the profile of the cylinder 37 with the undulated groove, indicated with reference numeral 39, which determines the alternate axial movement of the needles 35. It should be noted that, since the purpose of the undulated groove 39 is to obtain the alternate axial movement of the needles 35, the cylinder 37 can rotate without distinction to the right or to the left in the same direction as one of the two plates 25, 26 and the respective distributors 33, 34, see the dashed lines of figures 8 and 9 which indicate the kinematic connection of the different elements.

Figure 6 illustrates a step in which the needles 35 cross over and catch the threads 29, 30, so as to form the stitchwork 3 illustrated further down in the same figure 6. In the illustrated example in figures 6-9, the number of crests and valleys of the undulated groove 39 is equal to the number of threads 29, 30 and to the number of the needles 35, i.e. eight, of which four needles 35, in an alternate manner, catch four white threads 29, and the other four needles 35 catch the four black threads 30.

In any case, it should be noted that, especially in the case in which pipes with a greater diameter, or with a smaller diameter are used, and to obtain the desired yield of the stitchwork and covering of the surface of the pipe, the number of needles, and of the relative crests and valleys of the undulated groove 39, can be greater, or in the case in which pipes with a smaller diameter are used, less, respectively, than the number of threads so as to obtain a greater number of loops 6, 7. In practice, irrespective of the number of threads, the loops 6, 7 must be at a certain distance from one another, so as to ensure the necessary yield and malleability of the stitchwork. Figure 7 illustrates a step, subsequent to that of figure 6, in which the needles 35 catching the threads 29, 30 enter into respective eyelets that were previously formed so as to form the respective loops 6, 7 illustrated also in figure 1, it should be noted that a possible transverse movement of the needle 35 makes it possible to obtain loops with their axis Yl or Y2 inclined.

Figures 8 and 9 illustrate two steps similar to those of figure 6 and 7 with the threads 29, 30 arranged in a different manner.

Figure 10, illustrates a variant of the reinforcement stitchwork of the previous figures, in which the knots, i.e. the chains or the loops 6, 7 are further away and are alternated with rectilinear portions that cross over the loops of the other sets of threads, so as to obtain a stitchwork that has less yield due to the lower number of knots, i.e. of loops 6, 7 per unit stitchwork surface. Another particularity illustrated in figure 10 purely as an example, is that the sinusoidal grooves for the needles which operate on the respective sets Of threads 4 and 5 and i.e. on the threads 29 and 30, are separated on two different cylinders 37A, 37B and are indicated with reference numerals 39A and 39B. Also in this case it is a simple alternative with respect to the solution with a single cylinder 37, which can be necessary in the case in which there is not enough space on a single cylinder to make a single groove for all the needles, or even to create intervention times that are different for the needles orienting the cams or the grooves during the set-up, or preparation, of the machine. It should also be noted that the grooves 39A and 39B comprise a section 40, 41 that is substantially rectilinear and that corresponds to the section of rectilinear thread that crosses over the loop of the other sets of threads .

Figures 11-13 illustrate subsequent steps for forming a reinforcement stitchwork 3A illustrated in figure 2. The steps are similar to those illustrated in figures 6-9.

It should be noted that the loops 6A, 7A are identical with one another since they are formed by both the threads 29, 30, therefore for the purpose of obtaining the aforementioned loops 6A, 7A, and according to what has been illustrated in figure 11 the needles 35 must simultaneously cross over and catch both the threads 29, 30.

In particular, in order to obtain this reinforcement stitchwork 3A it is necessary for the distributors 33, 34 to be perfectly synchronised through the aforementioned fine adjustment device of the relative angular position of the two heads 20, 21. It should be noted that figures 11-13 are the three steps of a single stitchwork type, i.e. taking the two threads while being crossed over by each needle, these steps being different from those illustrated in figures 6 and 7 in which each needle takes only one thread.

The pipe equipped with the reinforcement stitchworks according to the present invention has numerous advantages, thanks to the stitchwork with a single layer it is cost-effective to produce, and thanks to the possibility of varying the different parameters of the stitchwork it is possible to control and adjust, in an optimal manner, the resistance, the yield, or the malleability, and the anti-twist properties of the pipe, the regularity in the distribution of the stitchworks deposited on the pipe and the optimal interlacing between the right and left stitchworks. Also the machine and the method for making the irrigation pipe according to the present invention have analogous advantages.

The present invention thus conceived can undergo numerous modifications and variants all covered by the scope of protection of the claims.

Claims

1. Machine (15) for making reinforced irrigation pipes (1) having a longitudinal axis (X) and equipped with at least one "tricot" reinforcement stitchwork (3, 3A, 3B, 9), the machine comprising a first group (16) and a second stitchwork group (17), substantially similar to each other and arranged facing one another according to the axis (X) of the pipe (1), each stitchwork group (16, 17) being foreseen to process a series of threads (4, 5) that form said reinforcement stitchwork (3, 3A, 3B, 9), characterised in that said stitchwork groups (16, 17) comprise a respective stitchwork and thread distribution head (20, 21) , said heads being set in rotation with opposite directions and cooperating with each other so as to form a reinforcement stitchwork (3, 3A, 3B, 9) with a single layer with series' of threads (4, 5) with opposite helocoidal extension.

2. Machine according to claim 1, wherein each of said stitchwork heads (20, 21) comprises a reel- holding plate (25, 26) for a series of reels (27, 28) equipped with the series' of threads (4, 5) formed from threads (29, 30) suitable for making the reinforcement stitchwork (3, 3A, 3B, 9) , said threads (29, 30) being respectively guided through tensioners (31, 32) and distributors (33, 34) all rotating the same way as the respective stitchwork and thread distribution head.

3. Machine according to claim 1 or 2, wherein at least one of said stitchwork and thread distribution heads (20, 21) comprises a group of needles (35) shared by the sets of threads (4, 5) .

4. Machine according to claim 3, wherein said group of needles (35) is set in alternate axial movement on a stationary drum (36), so that each needle (35) can cross over and catch at least one respective thread (29, 30) of the series of threads (4, 5) .

5. Machine according to claim 4, wherein each needle (35) is set in alternate axial movement on the stationary drum (36) so as to simultaneously cross over and catch at least two respective threads (29 and 30) of the two sets of threads (4, 5) that form the reinforcement stitchwork (3A).

6. Machine according to one of the previous claims, wherein said stitchwork heads (20, 21) are set in rotation in opposite directions through transmission means (19) that receive the motion from motor means (18), said transmission means (19) comprising motion inversion means (22).

7. Machine according to one of the previous claims, wherein said stitchwork heads (20, 21) are coupled with one another through a fine adjustment device that allows the relative angular position of the two heads (20, 21) to be adjusted even minimally, said fine adjustment device being of the mechanical or electrical type, and manual or servo- assisted .

8. Machine according to one of the previous claims, wherein said stitchwork and thread distribution heads (20, 21) are supported and guided through support means (38), arranged between said heads .

9. Method for making reinforced irrigation pipes

(1) having a longitudinal axis (X), an inner pipe

(2) and being equipped with a tricot reinforcement stitchwork (3, 3A, 3B, 9), the method comprising making the reinforcement stitchwork (3, 3A, 3B, 9) in a single layer with at least two sets of threads (4, 5) with opposite helocoidal extension, characterised in that said stitchwork (3, 3A, 3B, 9) is obtained by winding said sets of threads (4, 5) with opposite directions of rotation, helicoidally and crossed over on said inner pipe (2) with helix angles "A" and "B", with respect to the longitudinal axis (X), that are substantially equal and opposite.

10. Method according to claim 9, wherein said step of winding the sets of threads (4, 5) comprises making stitchwork loops (6, 7; 6A, 7A) crossed over and suitable for allowing a certain yield or malleability of the stitchwork (3, 3A, 3B, 9) .

11. Method according to claim 10, wherein said step of making stitchwork loops comprises making loops (6A, 7A) comprising both of the sets of threads (4, 5) .

12. Method according to claim 9 or 10, wherein said step of making stitchwork loops (6, 7; 6A, 7A) comprises making loops with a longitudinal axis (Yl, Y2) arranged obliquely and in the opposite direction with respect to the longitudinal axis (X) of the pipe (1) .

13. Reinforced irrigation pipe (1) having a longitudinal axis (X) comprising an inner pipe (2) , a tricot reinforcement stitchwork (3, 3A, 3B, 9) wound on said inner pipe (2) , an outer pipe or outer covering sheath (8) for protecting the stitchwork (3, 3A) , characterised in that reinforcement stitchwork (3, 3A, 3B, 9) is in a single sheet and comprises at least two sets of threads (4, 5) wound helicoidally on said inner pipe (2) with helix angles "A" and "B", with respect to the longitudinal axis (X) , that are substantially equal and opposite.

14. Irrigation pipe according to claim 13, wherein said helix angles "A" and "B" are within a range of between 35 and 75 degrees, preferably within a range of between 50 and 60 degrees and even more preferably they are 55 degrees.

15. Irrigation pipe according to claim 13 or 14, wherein said stitchwork (3, 3A, 3B, 9) comprises stitchwork loops (6, 7; 6A, 7A) crossed over and suitable for allowing a certain yield of the stitchwork .

16. Irrigation pipe according to one of claims 13 to 15, wherein said stitchwork loops (6A, 7A) both comprise the sets of threads (4, 5).

17. Irrigation pipe according to one of claims 13 to 16, wherein said stitchwork loops (6, 7; 6A, 7A) have a longitudinal axis (Yl, Y2 ) arranged obliquely and in the opposite direction with respect to the longitudinal axis (X) of the pipe (1).

18. Irrigation pipe according to one of claims 13 to 17, wherein the inclination of the axes (Yl, Y2) is between +20 degrees and -20 degrees, and more preferably between +10 degrees and -10 degrees with respect to the longitudinal axis (X) of the pipe (1) ·