WO2013041948A1

WO2013041948A1 - Pipe for transferring abrasive materials such as concrete or similar or comparable materials, and method of production

Info

Publication number: WO2013041948A1
Application number: PCT/IB2012/001850
Authority: WO
Inventors: Nicola Pirri; Davide Cipolla; Massimiliano Valle
Original assignee: Cifa Spa
Priority date: 2011-09-23
Filing date: 2012-09-21
Publication date: 2013-03-28
Also published as: ITUD20110147A1

Abstract

Pipe for transferring abrasive material, such as concrete, comprising at least a tubular body (11) defining an external surface (17) and an internal surface (16) through which the abrasive material is suitable to flow, wherein the tubular body (11) is made of fiber-reinforced composite material and comprises a plurality of fibers (21, 22) overlapping each other and drowned in a polymer material (20) to define the thickness (S) of the tubular body (11). The polymer material (20) in turn also defines a uniform layer (23), substantially continuous, in correspondence with the internal surface (16) of the tubular body (11). Moreover, the polymer material (20) has high elasticity and low hardness, and is chosen from a group comprising at least polypropylene, polyamide, thermoplastic elastomers, polyurethane resins, epoxy resins.

Description

"PIPE FOR TRANSFERRING ABRASIVE MATERIALS SUCH AS CONCRETE OR SIMILAR OR COMPARABLE MATERIALS, AND METHOD OF PRODUCTION"

FIELD OF THE INVENTION

The present invention concerns a pipe for transferring abrasive materials such as concrete or similar or comparable materials, for example used for concrete mixer trucks, pumps transported on trucks or suchlike. Here and hereafter in the description and claims, the word pipe shall include pipes with a substantially straight development and also curved pipes.

The present invention also concerns the method used to make a pipe for transferring abrasive materials.

BACKGROUND OF THE INVENTION

Pipes for transferring concrete are known, made of metal material and which are subjected to suitable surface heat treatments, in particular on the internal surface, in order to increase their resistance to wear.

The heat treatments usually used are surface quenching, carbon-cementation, nitriding or other heat treatments suitable to increase the surface hardness of the pipes.

These known pipes, however, have the disadvantage that the hardening treatment has a very limited level of penetration, and therefore only a very limited thickness of the pipe, starting from the internal surface, has resistance to wear. Once this thickness has been removed, due to the process of abrasion, the use of the pipe is quickly compromised.

Furthermore, the above-mentioned surface hardening treatments are very expensive and time-consuming.

Pipes are also known, and in particular segments of pipes, that are greatly stressed, such as the curved parts, comprising inserts disposed on the internal surface and made of wear-resistant material such as cast iron, ceramic materials or composites, which are inserted in, or co-founded with, a covering layer made of lighter and softer material such as for example steel, aluminum or suchlike.

Pipes are also known that comprise an internal layer of great hardness and hence great resistance to wear, and a more outer layer made of non-metal material and resistant to knocks.

In both cases, it is possible to obtain a good resistance to wear in the internal part using inserts, and a good mechanical resistance and resistance to knocks in the external part, thanks to the covering layer; it is also possible to guarantee, at the same time, resistance to the flexional stresses to which the pipe is subjected due to its own weight and to that of the concrete passing through it, and due to the pressure exerted by the concrete when it is pumped.

The known pipes described above have the disadvantage that they are very heavy, and therefore conflict with the requirement of being light, as required for example for applications on articulated arms, pumps transported on trucks or suchlike, where increasingly long arms are required to be used, while keeping the overall weight below an acceptable threshold.

Pipes are also known, for example from US-A-2.973.783 and GB-A- 1.205.983, that are not directly applicable for transferring abrasive materials such as concrete, which are made of polymer material and are provided with a plurality of reinforcement fibers drowned in the polymer material.

In particular, US-A-2.973.783 describes a method in which the fibers are disposed oriented differently from each other in order to confer on the pipe a determinate resistance to internal pressures.

The fibers are short and are uniformly distributed throughout the whole thickness of the pipe.

These types of pipes are not suitable for transferring abrasive materials such as concrete, because the wear exerted by such materials would quickly cause the pipe to become unusable, since as soon as the abrasive particles of the concrete enter into contact with the fibers, the latter are removed, leaving zones where wear can be triggered.

One purpose of the present invention is to obtain a pipe and perfect a method for making a pipe for transferring abrasive material such as concrete, which is light and at the same time has resistance to wear and mechanical resistance at least comparable to, if not greater than, common pipes.

Another purpose of the present invention is to obtain a pipe for transferring concrete which is simple and economical to make.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, a pipe for transferring abrasive material such as for example concrete or similar or comparable materials, comprises a tubular cylindrical body defining an external surface and an internal surface through which abrasive material, such as for example concrete or similar or comparable material, is suitable to flow.

According to one feature of the present invention, the tubular body is made of fiber-reinforced composite material and comprises a plurality of fibers drowned in a polymer material. The tubular body has a determinate overall thickness and comprises, starting from the internal surface, a uniform layer without fibers, with a thickness at least equal to 20% of the overall thickness of the tubular body.

Some forms of embodiment provide that the fibers are uniformly distributed and concentrated only in an external zone in proximity to the external surface of the tubular body, while the fiberless internal layer is made in a single body with said external zone, and defines the anti-wear layer for the abrasive particles passing through.

The polymer material has both the function of winding and integrating the fibers with respect to each other, and also that of defining the overall thickness of the tubular body. The fibers confer on the pipe structural and mechanical resistance to the internal pressure that is exerted by the material flowing through. The fibers are bonded with each other and compacted in order to protect them from the possible action of abrasion exerted by the concrete. The polymer material, at least in proximity to the uniform layer, has limited hardness, great elasticity and is chosen from a group comprising polypropylene, polyamide, thermoplastic elastomers, polyurethane resins, epoxy resins or suchlike.

Some forms of embodiment provide that the uniform fiberless layer has a thickness comprised between 20% and 70% of the overall thickness of the tubular body, and this allows to obtain an adequate anti-wear effect on the material in transit, and to extend the working life thereof in efficient conditions, while still guaranteeing the effectiveness of the reinforcement obtained by the presence of the fibers.

In fact, the Applicant has found that, thanks to the great elasticity of the polymer material, as they pass through the pipe the abrasive particles impact on the internal surface and bounce off, so that their impact energy is damped. This damping action allows to attenuate the abrasive action and the surface removal of the pipe. If the fibers were distributed uniformly over the whole thickness of the pipe, as in the state of the art, the fibers themselves would limit the elasticity of the polymer material, limiting the damping effect on the abrasive particles. Furthermore, a minimum wear effect would lead to the fibers being uncovered, compromising the mechanical resistance and making the pipe unusable in a short time. The thickness of the uniform fiberless layer and facing toward the inside of the pipe is therefore necessary both to guarantee adequate elasticity and also to guarantee the pipe lasts over time.

On the contrary, in state-of-the-art pipes, with the hardening treatments or possible insertion or making of inserts or layers with great hardness, the particles of concrete discharge all their energy, during the repeated impacts, against the internal surface and thus progressively wear it.

According to another characteristic, the polymer material has a hardness comprised between 50 and 100 Shore A, preferably between 60 and 90 Shore A, more preferably between 70 and 80 Shore A.

In some forms of embodiment it is possible to provide that the uniform layer of polymer material has a thickness comprised from about 30% to about 60%, preferably between 40% and 50% of the overall thickness of the pipe.

According to another characteristic, the fibers are chosen from a group comprising glass fibers, basalt fibers, ceramic fibers, carbon fibers, or combinations thereof.

According to another characteristic, the tubular body comprises first fibers and second fibers disposed transverse with respect to the first fibers, to define a plurality of overlapping woven meshes.

In one form of embodiment the first fibers and second fibers are disposed with respect to each other by an angle of about 90°. In other forms of embodiment, the first and second fibers are disposed crosswise with respect to each other at an angle comprised between 20° and 70°, preferably between 30° and 60°, even more preferably between 40° and 50°.

To allow the joins to be coupled, the ends of the pipes must provide a suitable increase in the thickness of the pipe, for example by modifying the way the fibers are laminated.

In particular, it is possible to provide two different methods of making the ends, that is, with a fabric having deflected fibers and a fabric having winding fibers.

In order to make the ends with deflected fibers, another layer of fabric is interposed between one layer of fabric and the following one and in the end segment, having an extension equal to the thicker segment to be obtained. The fibers are in any case always drowned in the polymer material.

In order to make the ends with winding fibers, the end part of the fibers is suitably folded back upon itself, in a U-shaped conformation, toward the central part of the longitudinal extension of the pipe and for a determinate segment. In this case too, the fibers are drowned in the polymer material.

The present invention also concerns the method for making a pipe as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a perspective view of a pipe for transferring concrete according to the present invention;

- fig. 2 is a perspective view of a variant of fig. 1 ;

- fig. 3 is a schematic view in section of the pipe in fig. 1 ;

- fig. 4 is a schematic view in section of a variant of fig. 3;

- fig. 5 is a schematic representation of the disposition of the fibers in a pipe according to the present invention;

- fig. 6 shows a variant of fig. 5;

- fig. 7 is a schematic representation in section of a portion of fig. 1 ;

- fig. 8 is a variant of fig. 7; - fig. 9 is a variant of fig. 4.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DESCRIPTION OF SOME FORMS OF EMBODIMENT

With reference to fig. 1, a pipe for transferring abrasive materials, such as for example concrete, is indicated in its entirety by the reference number 10, and comprises a tubular body 1 1 with a substantially circular section and a substantially longitudinal development, provided with a first end 12 and a second end 13.

The tubular body 1 1 may develop longitudinally along an axis of development X, which is rectilinear (fig. 1).

The present invention is also applied in the same way to curved pipes 1 10 (fig. 2), that is, in which the tubular body 1 1 develops according to an axis of development X in an arc of a circle.

In other forms of embodiment, the tubular body 1 1 can also develop according to rectilinear, curved or mixed axes of development.

The tubular body 1 1 in this case has a substantially circular section, although in other forms of embodiment it may also have different shapes, such as rectangular, polygonal, elliptical.

The tubular body 1 1 is made of fiber-reinforced composite material which comprises an overlapping of several woven meshes 19, or woven fibers, which are completely drowned in a polymer material 20.

The polymer material 20, at least in proximity to the internal surface 16 of the tubular body 1 1, defines a uniform layer 23 with a substantially constant thickness of said polymer material 20, which is not affected by said woven meshes 19.

An external zone 18 is thus defined, uniformly affected by the woven meshes 19 which, from the external surface 17 of the tubular body 1 1 extends toward the internal surface 16 and for a determinate thickness. The innermost uniform layer 23 is disposed close up to the internal surface 16 of the tubular body 1 1, it is without fibers or meshes and is made in a single body with the external zone 18.

In fact, since the uniform layer 23 is made of the same polymer material 20 that integrates the woven meshes 19, it is substantially continuous with the polymer material 20 that integrates the woven meshes 19, that is, with the external zone 18.

The tubular body 1 1 has an overall thickness S comprised between 4 mm and 20 mm, in this case about 5-6 mm, which can vary in proximity to the ends 12, 13.

In one form of embodiment (fig. 4), the uniform layer 23 of polymer material

20 not affected by the woven meshes 19, on the side of the internal surface 16 of the tubular body 1 1, has a thickness T which is at least 20% of the overall thickness of the pipe. In one solution of the invention, the thickness of the uniform layer 23 is comprised between 20% and about 70% of the overall thickness S of the pipe 10, preferably between 30% and 60%, even more preferably between 40% and 50%.

In this way the uniform fiberless layer 23 has a sufficient thickness to allow it to exert, on the abrasive particles of concrete passing through, an elastic rebound action which attenuates the abrasive action.

Furthermore, a possible wear action keeps the fibers of the woven meshes 19 protected by the thickness of the uniform fiberless layer 23, and therefore the further process of wear as described in the state of the art is not promoted.

In particular, the uniform layer 23 of polymer material 20 has a thickness T that can vary from about 1 mm to about 10 mm, in this case between 2 and 2.5 mm.

The woven meshes 19 (figs. 5 and 6) comprise at least a plurality of first fibers

21 and a plurality of second fibers 22, woven transversely with respect to the first fibers 21 and in a succession of overlapping layers substantially adjacent to each other.

In particular, in a first form of embodiment (fig. 5), the first fibers 21 are disposed at an angle of weave a of about 90° with respect to the axis of development X of the pipe 10, while the second fibers 22 are disposed substantially parallel to the axis of development X.

In another form of embodiment (fig. 6), the first fibers 21 and the second fibers 22 are woyen at a reciprocal angle of weave β comprised between about 20° and 70° and, in this case, about 60°.

In a preferential form of embodiment, in order to obtain a uniform resistance along the extension of the tubular body 1 1 , both the first 21 and the second fibers 22 are disposed symmetrically with respect to the axis of development X of the tubular body 1 1.

The polymer material 20 has high elasticity, low hardness and is chosen from a group comprising polypropylene, polyamide, thermoplastic elastomers, polyurethane resins, epoxy resins or suchlike.

The polymer material 20 has a hardness between 50 and 100 Shore A, preferably between 60 and 90 Shore A, more preferably between 70 and 80 Shore A.

The woven meshes 19 are made of fibers chosen from a group comprising glass fibers, basalt fibers, ceramic fibers, carbon fibers, metal fibers, natural fibers, or a combination thereof.

The tubular body 1 1 thus made therefore has a thickness of polymer material 20 without fibers, toward its internal part which, having great elasticity, performs an anti-abrasion function with respect to the stream passing through.

In fact, when the abrasive particles impact against the internal surface 16 of the tubular body 1 1 , they are made to rebound by the polymer material which in turn, having a compact and uniform internal structure, absorbs the impact energy of the particles.

The woven meshes 19 confer the desired mechanical resistance on the pipe 10 and, by way of example only, the pipe 10 is able to resist levels of maximum internal pressure of about 140 - 170 bar.

Given that the woven meshes 19 are completely drowned in the polymer material 20, they are protected from the abrasive process of the particles.

The first end 12 and the second end 13 have a greater thickness than the tubular body 1 1 , in order to allow other pipes to be connected by means of substantially known connection means.

To obtain an increase in the thickness of the ends 12 and 13 (fig. 7) in proximity to the end, the woven meshes 19 are folded back on themselves in the direction of the central part of the tubular body 1 1. In the same way as described above, in this zone too the woven meshes 19 are completely drowned in the polymer material 20.

More specifically, each of the woven meshes 19 comprises a first segment 24a that extends substantially for the whole length of the pipe 10, a second segment 24b that extends transversely to the thickness of the pipe 10, and a third segment 24c that extends substantially parallel to the first segment 24a and externally with respect to the latter. Furthermore, the woven meshes 19, in alternation, are respectively folded back transversely toward the internal part of the thickness with a fourth segment 24d, or are interrupted in proximity to the third segment 24c. Each of the fourth segments 24d, or at least some of them, are in turn folded back parallel to the longitudinal extension of the pipe 10, with a fifth segment 24e, and extend along the extension of the pipe.

In this way it is possible to define a greater resistance to tearing in proximity to the ends when another pipe is connected to them.

In another form of embodiment (fig. 8), the increase in thickness in proximity to the ends 12, 13 is obtained by alternating with the layers of woven meshes 19 second layers of woven meshes 27, which extend only for a determinate length from the end 12, 13. This allows, in the same way as described with reference to fig. 7, to define the desired increase in thickness.

The present invention also concerns the method to make a pipe 10, which provides a step to define the tubular body 1 1.

In particular, a first sub-step is provided in which both the first fibers 21 and the second fibers 22 are woven on a female type mold to define the woven mesh 19.

The female type mold is made in two or more pieces, divided from each other and which define a cylindrical internal cavity with a mainly longitudinal development and having a diameter substantially equal to the external diameter of the pipe 10 to be obtained.

During this step several woven meshes 19 are superimposed, so as to determine the mechanical resistance of the pipe. More specifically, the woven meshes 19 are disposed adherent on the internal surface of the internal cavity of the mold to define what will subsequently be, once the polymer material has been injected, the external zone 18. Subsequently, during a second sub-step, the polymer material 20 is injected into the mold to drown the woven meshes 19 completely inside it, and to define at least the uniform layer 23 in proximity to the internal surface 16 of the pipe. There then follows a polymerization step to polymerize the polymer material injected, in order to confer a determinate bearing capacity on the tubular body 1 1 that is being made.

In some forms of embodiment of the method, it can be provided that, during the injection of the polymer material, the internal cavity of the mold is subjected to an internal pressure such as to keep both the polymer material and the woven meshes 19 as adherent as possible to the internal surface of the mold. The application of an internal pressure of this type allows to keep the woven meshes 19 overlapping, reciprocally adherent, in this way limiting any discontinuity, which is usually accentuated at the ends of the edges of each woven mesh 19, which can trigger the process of wear by the concrete.

During said first sub-step, it may also be provided to make the ends of the tubular body 1 1. In particular, during the first sub-step, it may be provided to fold back the terminal parts of the woven meshes 19 on themselves, as described with reference to fig. 7, or to dispose the woven meshes 19 and the second layers of woven meshes 27 alternately, as described with reference to fig. 8.

During the second sub-step, the polymer material injected defines both the tubular body 1 1 and also the ends 12 and 13.

According to a variant of the method, it may be provided to use a plurality of composite sheets made with basic monomers which, once polymerized, define the polymer material that makes up the pipe. The composite sheets are wound and superimposed with respect to each other to define the thickness of the pipe to be obtained. The woven meshes 19 are incorporated in at least some of the composite sheets. The overlapping of the composite sheets provided by the woven meshes 19 and those without woven meshes is defined as a function of the thicknesses and characteristics that the section of the pipe 10 to be obtained must have.

Subsequently, as described above, the basic monomers of the composite sheets are polymerized in order to confer the desired mechanical and structural resistance on the pipe. In this case too it may be provided that inside the mold an internal pressure is set such as to keep the composite sheets adherent to the walls during the polymerization step.

It is clear that modifications and/or additions of parts may be made to the pipe for transferring abrasive material and the corresponding method to make it as described heretofore, without departing from the field and scope of the present invention.

For example, it is possible to provide that at least the internal part of the tubular body 1 1, that is, at least the uniform layer 23, is subjected to a treatment to confer greater elasticity on the polymer material 20 and to increase the damping effect on the knocks caused by the particles of concrete.

Moreover, the step of making the cylindrical body 1 1 may be carried out with known filament winding techniques.

In other forms of embodiment it may be provided that in proximity to zones of the pipe 10 which during use are subjected to great stresses, there is an increase in the presence of fibers 21, 22, or a more concentrated overlapping of woven meshes 19.

Furthermore, in proximity to the ends 12, 13, instead of providing a thickening of the ends by increasing the presence of fibers, it may be provided to insert reinforcement inserts 30 made of hard material and disposed in the internal surface of the pipe 10, as shown in fig. 9.

More specifically, the reinforcement inserts 30 disposed in proximity to the ends 12 or 13 of the pipe 10 develop circumferentially for a determinate angular sector, in this case about 120°, and are at least partly integrated into the thickness of the uniform layer 23 of polymer material.

Each of the inserts 30 is in practice adherent to the uniform layer 23 so that, during the repeated knocks of the particles of concrete against the walls of the inserts 30, the uniform layer 23 exerts a damping effect on the inserts 30 and hence dissipates the impact energy possessed by the particles. This allows a consequent reduction in the wear exerted by the concrete on the inserts 30.

In this case the inserts, for example made of steel, guarantee the coupling with joining elements that are usually connected in said zones.

Claims

1. Pipe for transferring abrasive material, such as concrete, comprising at least a tubular body (1 1) having an external surface (17) and an internal surface (16), said tubular body (1 1) being made of fiber-reinforced composite material and comprising a plurality of fibers (21, 22) drowned in a polymer material (20), characterized in that said tubular body (11) has an overall thickness (S) and comprises, starting from the internal surface (16), a uniform layer (23), without said fibers (21, 22), with a thickness (T) equal at least to 20% of the thickness (S) of said tubular body (1 1), and in that said polymer material (20) has high elasticity and low hardness, and is chosen from a group comprising at least polypropylene, polyamide, thermoplastic elastomers, polyurethane resins, epoxy resins.

2. Pipe as in claim 1, characterized in that said uniform layer (23) has a thickness (T) comprised between 20% and 70%.

3. Pipe as in claim 2, characterized in that said uniform layer has a thickness (T) comprised between 30% and 60%, preferably between 40% and 50% of the thickness (S) of said tubular body (1 1).

4. Pipe as in claim 1, 2 or 3, characterized in that said polymer material (20) has a hardness comprised between 50 and 100 Shore A, preferably between 60 and 90 Shore A, more preferably between 70 and 80 Shore A.

5. Pipe as in any claim hereinbefore, characterized in that said fibers (21, 22) are chosen from a group comprising glass fibers, basalt fibers, ceramic fibers, carbon fibers, metal fibers, natural fibers, or combinations thereof.

6. Pipe as in any claim hereinbefore, characterized in that it comprises a plurality of first fibers (21) and of second fibers (22) disposed transverse to said first fibers (21) to define a plurality of overlapping woven meshes (19).

7. Pipe as in claim 6, characterized in that said first fibers (21) are disposed cross-wise with respect to said second fibers (22) at an angle equal to or less than about 90°, preferably comprised between 20° and 70°, more preferably between 30° and 60°, even more preferably between 40° and 50°.

8. Pipe as in any claim hereinbefore, characterized in that it comprises at least a first end (12), and a second end (13), both having a greater thickness than the thickness (S) of said tubular body (1 1), and in that, at least in correspondence with one of either said first end (12) or said second end (13), said woven fibers (21, 22) are disposed folded back on themselves toward the central part of said tubular body (1 1), and drowned in said polymer material (20).

9. Pipe as in any claim from 1 to 8, characterized in that it comprises at least a first end (12), and a second end (13), both having a greater thickness than the thickness (S) of said tubular body (1 1), and in that at least in proximity to said first end (12) and said second end (13) is provided with other layers of fibers (27) disposed alternate with said woven fibers (21 , 22) which extend in said tubular body (1 1).

' 10. Method to make a pipe for transferring abrasive material, such as concrete, comprising at least a step in which a tubular body (11) is made, made of a fiber- reinforced composite material having an external surface (17) and an internal surface (16), said method providing, in said step, to drown a plurality of fibers (21 , 22) in a polymer material (20), characterized in that said tubular body (1 1) has an overall thickness (S) and during said step, starting from the internal surface (16), a uniform layer (23) is made, without said fibers (21, 22), with a thickness (T) equal at least to 20% of the thickness (S) of said tubular body (1 1), said polymer material having high elasticity and low hardness, and being chosen from a group comprising at least polypropylene, polyamide, thermoplastic elastomers, polyurethane resins, epoxy resins.

1 1. Method as in claim 10, characterized in that said step of making the tubular body (1 1) comprises a first sub-step during which said fibers (21, 22) are woven on a female type mold so as to define an overlapping of several woven meshes (19), and a second sub-step during which said polymer material (20) is injected into said woven meshes (19), so as to drown the latter completely inside it and to define at least said uniform layer (23) of polymer material (20).

12. Method as in claim 10, characterized in that before said step of making the tubular body (1 1), said plurality of fibers (21, 22) are woven so as to define a woven mesh (19) and basic monomer elements are integrated with said fibers, which basic monomer elements subsequently define, after polymerization, said polymer material (20), said woven mesh (19) and said basic monomer elements defining a composite sheet, and in that said step of making the tubular body (1 1) comprises a first sub-step in which said composite sheet is disposed in a female type mold adhering to the internal surface of said mold, and a second sub-step in which said basic monomer elements are polymerized so as to make said polymer material (20).