Conveyor belt

Abstract

The present invention relates to a conveyor belt (100) comprising: a core (10) comprising carcass metal cables (11) extending in a longitudinal direction of the conveyor belt (100), said carcass metal cables (11) being coated in a first elastomeric matrix (15); a first reinforcement layer (20) arranged above the core, said first reinforcement layer comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt (100) and a second elastomeric matrix (25) coating said fabric and / or metal cables;and a second reinforcing layer (30) disposed above the first reinforcing layer (20), said second reinforcing layer (30) comprising a plurality of corrugated metallic reinforcing cables (31) in the plane of the conveyor belt (100), arranged parallel to each other in a longitudinal direction of the conveyor belt (100), and a third elastomeric matrix (35) encasing the reinforcing cables (31). Figure for the abbreviation: Fig. 1;

Description

Title of the invention: Conveyor belt technical field

[0001] The invention relates to a conveyor belt for transporting bulk materials in mines, docks, metallurgy, machinery, and warehouses. The invention also relates to methods for manufacturing such a conveyor belt. PRINCIPAL OF THE TECHNOLOGY

[0002] Conveyor belts are commonly used for transporting bulk materials in mines, docks, metallurgy, machinery, and warehouses. Conveyor belts are mainly composed of a core made up of main metal cables extending in the direction of belt circulation and a rubber matrix.

[0003] Such conveyor belts are subjected to harsh conditions and must withstand significant impacts. For example, the belts may be exposed to impacts from sharp objects, objects weighing several tens of kilograms, and loads falling onto the belt from a height of several meters, such as sharp stones or rocks. Thus, conveyor belts are frequently damaged by hard pieces that pierce the belt and often cause longitudinal tears.

[0004] To prevent and minimize damage to the conveyor belt during impacts, protective reinforcements can be integrated into the belt structure above the belt web, and in some applications also below the web.

[0005] However, these reinforcements lead to an increase in the flexural rigidity, particularly in transverse bending, of the belt, which can become problematic for ensuring good lateral guidance of the belt and good contact on the support rollers.

[0006] Two main families of protective reinforcements are distinguished: reinforcements based on textile fabrics, mainly polyamide, and reinforcements based on metal cables arranged in the transverse direction of the band.

[0007] Textile fabric reinforcements can be made of strong yarns that can stop cracks in the event of perforation by a penetrating object, thus effectively limiting the severity of the damage. This effect is due to the ability of polyamide yarns to stretch and gather at the base of the crack into a bundle that can become strong enough to stop the crack.

[0008] However, polyamide textiles have limited tear resistance, particularly in the case of impact by very sharp objects such as dolerite rock or slate.

[0009] Other types of reinforcement include transverse wire cables held in position by longitudinal metal or textile binding threads, for example, made of polyamide or polyester. Protective reinforcements based on wire cables typically have higher breaking strength than textile reinforcements. However, wire cables are less flexible than a textile reinforcement and therefore cannot gather at the bottom of a crack to create a thicker reinforcement in that position. Moreover, such reinforcements significantly increase the flexural stiffness of the conveyor belt. Summary of the invention

[0010] An object of the invention is to design a conveyor belt exhibiting improved resistance to breakage, allowing deformation to create a thicker reinforcement at the bottom of a possible crack, while retaining sufficient flexibility for transverse bending of the belt on the rollers.

[0011] To this end, the invention proposes a conveyor belt comprising: • a core comprising carcass metal cables extending in a longitudinal direction of the conveyor belt, said carcass metal cables being coated in a first elastomeric matrix; • a first reinforcing layer arranged above the core, said first reinforcing layer comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt and a second elastomeric matrix encasing said fabric and / or metal cables; and • a second reinforcement layer disposed above the first reinforcement layer, said second reinforcement layer comprising a plurality of corrugated metallic reinforcement cables in the plane of the conveyor belt, arranged parallel in a longitudinal direction of the conveyor belt, and a third elastomeric matrix encasing the reinforcement cables.

[0012] According to other advantageous but optional features, taken separately or in combination:

[0013] - the distance between the centers of two adjacent corrugated metal reinforcement cables is less than or equal to four times the diameter of each corrugated metal reinforcement cable, preferably twice the diameter of each reinforcement cable;

[0014] - the amplitude of the undulation of the reinforcing cables is between 3 and 8 mm, of preference of 5.5 mm;

[0015] - the wavelength of the reinforcing cables is between 10 and 20 mm, of preference of 14.5 mm;

[0016] - the ratio between the ripple amplitude and the ripple period is greater than or equal to 0.3;

[0017] - the reinforcing cables cover a central portion of the conveyor belt having a width greater than 30% of the width of the conveyor belt;

[0018] - the reinforcing layer (30) comprises a plurality of juxtaposed reinforcing layers in a single layer on an upper face of the core in a transverse direction of the conveyor belt, each reinforcement layer comprising corrugated metal reinforcing cables in the plane of the conveyor belt embedded in an elastomeric matrix;

[0019] - the width of each reinforcement layer is between 100 and 350 mm;

[0020] - each reinforcing cable comprises between 1 and 26 metallic monofilaments;

[0021] - the diameter of the reinforcing cables (31) is between 0.18 mm and 2 mm;

[0022] - the conveyor belt further comprises a third layer of reinforcement arranged below the core, said third reinforcement layer comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt and an elastomeric matrix encasing said fabric and / or metal cables;

[0023] - the conveyor belt further comprises a top coating and / or a lower coating made of an elastomeric material.

[0024] Another object of the invention relates to a method for manufacturing a conveyor belt, comprising: • the provision of a core comprising carcass metal cables extending in a longitudinal direction of the conveyor belt, said carcass metal cables being coated in a first elastomeric matrix; • the application of a first layer of reinforcement above the core, said first layer of reinforcement comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt and a second elastomeric matrix encasing said fabric and / or metal cables; • the deformation of a sheet comprising parallel metal cables so that the cables form undulations, said cables being coated in a third elastomeric matrix; • the realignment of the corrugated metal cables so that the corrugations are arranged in a plane; • the covering of the upper face of the first reinforcement layer by the second reinforcement layer, so that the corrugated metal cables extend in a longitudinal direction of the conveyor belt.

[0025] Said method may further include the application of a third layer of reinforcement on an underside of the core, said third layer of reinforcement comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt and an elastomeric matrix encasing said fabric and / or metal cables.

[0026] The covering of the upper face of the first reinforcement layer may include the laying of at least two reinforcement layers comprising identical corrugated metal cables in parallel in a longitudinal direction of the conveyor belt. BRIEF DESCRIPTION OF THE FIGURES

[0027] Other features and advantages will become apparent from the detailed description that follows, with reference to the accompanying drawings, on which:

[0028] - [Fig. 1] is a perspective view of a portion of a conveyor belt according the invention;

[0029] - [Fig. 2A] illustrates a first embodiment of the arrangement of monofilaments in a core cable;

[0030] - [Fig. 2B] illustrates a second embodiment of the arrangement of monofilaments in a core cable;

[0031] - Figure 3 illustrates a first reinforcing layer comprising a fabric made of polyamide;

[0032] - Figure 4 illustrates a first reinforcement layer comprising metal cables transversals;

[0033] - [Fig. 5] is a perspective view of the core cables and reinforcement structures of a conveyor belt according to the invention;

[0034] - [Fig. 6A] is a top view of the cables and wires present in a strip conveyor;

[0035] - [Fig.6B] is a cross-sectional view of the cables and wires of [Fig.6A];

[0036] - [Fig.6C] is a longitudinal cross-sectional view of the cables and wires of [Fig.6A].

[0037] - [Fig.7] is a detailed view of the second reinforcement layer of [Fig.6A];

[0038] - [Fig.8] illustrates the geometry of the corrugated cables.

[0039] For reasons of readability of the figures, the illustrated elements are not necessarily represented to scale. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0040] In this text, the terms "vertical", "horizontal", "upper", "lower" refer to the position of an object transported on the belt oriented in the direction of transport.

[0041] Figure 1 is a perspective view of a portion of a conveyor belt 100 according to the invention. The conveyor belt comprises a core 10 made of carcass wire ropes 11. The carcass wires 11 are the main wires of the conveyor belt and extend in a longitudinal direction 1 corresponding to the direction of belt circulation. By way of illustration and without limitation, the carcass wires 11 are typically multi-strand wire ropes, each strand comprising several monofilaments. Preferably, the monofilaments are arranged helix and the strands are arranged helix. By metallic, we mean a material consisting of at least 50% of its mass of a metallic material.

[0042] By way of illustration and without limitation, carcass cables 11A may be seven-strand cables 12 of seven monofilaments 13 per strand as illustrated in [Fig. 2A]. Such cables typically have a diameter of between 2 and 6 mm. Alternatively, with reference to [Fig. 2B], carcass cables 111IB may, for example, comprise seven strands 12 of nineteen monofilaments 13 per strand 12. Such cables typically have a diameter of between 4 and 14 mm.

[0043] The monofilaments of the carcass cables are, for example, made of steel, preferably pearlitic steel or carbon ferritic-pearlitic steel, or stainless steel containing at least 10.5% chromium. These monofilaments may have a coating comprising copper, zinc, pein, cobalt, or an alloy of these metals, for example, brass or bronze. Each individual metallic monofilament typically has a mechanical strength of 1000 MPa at 5000 MPa.

[0044] The mechanical resistance measurement is carried out according to ASTM D 2969-00 on a metal cable intended for tire reinforcement.

[0045] The initial section of the metal cable (So) is determined upstream of a tensile measurement.

[0046] The measurement is performed on a tensile testing machine that stretches the cable to the point of breakage in order to determine the breaking strength Fm of the wire rope as well as the force exerted during elongation. The elongation is measured with a mechanical extensometer that is in contact with the wire rope during the procedure.

[0047] The cable is held by clamps allowing the metal cables to be extended until the cable breaks outside the clamp's gripping area. Clamps with a gradual curve are therefore preferably used.

[0048] The tensile test begins with a load on the sample (called preload) corresponding to 1% of the estimated breaking force and allows the elongation measurement to be initiated (zeroing of the deformation).

[0049] This preload is estimated beforehand on the basis of 3 force measurements at break carried out with the same device.

[0050] The measurement consists of recording the force curve as a function of the cable elongation until the break occurs.

[0051] The measurement is considered valid when the place of the break is located in the area between the clamps, outside the gripping area of ​​the metal reinforcement.

[0052] The maximum mechanical resistance Rm is determined from the maximum force Fm and the initial section of the specimen So according to „ r, 1 _ F„In] . Km LJ — cr >1

[0053] The carcass cables 11 are arranged in parallel and coated with a first elastomeric matrix 15. The distance between the centers of two carcass cables 11 Da is typically between 10 and 19 cm.

[0054] The conveyor belt includes at least a first reinforcement layer 20 arranged above the core 10. With reference to [Fig.3], the first reinforcement layer 20 includes an internal structure such as a textile fabric and / or transverse metal cables, and a second elastomeric matrix 25 encasing said fabric and / or metal cables.

[0055] The internal fabric structures 23 comprise at least one longitudinal multifilament strand 22 of aromatic polyamide or aromatic copolyamide, aliphatic polyamide or polyester and have a density of up to 1.6kg / m2.

[0056] By aromatic polyamide multifilament strand or aromatic copolyamide, it is well known that it is a filament of linear macromolecules formed of aromatic groups linked together by amide bonds of which at least 85% are directly linked to two aromatic nuclei, and more particularly of poly (p-phenylene terephthalamide) (or PPTA) fibers, manufactured for a very long time from optically anisotropic spinning compositions.Among the aromatic polyamides or aromatic copolyamides, we can mention polyarylamides (or PAA, notably known under the trade name Ixef from the company Solvay), poly(metaxylylene adipamide), polyphthalamides (or PPA, notably known under the trade name Amodel from the company Solvay), or para-aramids (or poly(paraphenylene terephthalamide or PA PPD-T notably known under the trade name Kevlar from the company Du Pont de Nemours or Twaron from the company Teijin).

[0057] By multifilament strand of aliphatic polyamide, we mean a filament of linear macromolecules of polymers or copolymers containing functions Amides that do not contain aromatic rings and can be synthesized by polycondensation between a carboxylic acid and an amine. Examples of aliphatic polyamides include nylons PA4.6, PA6, PA6.6, and PA6.10, notably Zytel from DuPont, Technyl from Solvay, and Rilsamid from Arkema.

[0058] A multifilament polyester strand is defined as a filament of linear macromolecules formed from groups linked together by ester bonds. Polyesters are manufactured by polycondensation through esterification between a dicarboxylic acid or one of its derivatives and a diol. For example, polyethylene terephthalate can be manufactured by polycondensation of terephthalic acid and ethylene glycol. Among the known polyesters, we can mention polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polypropylene terephthalate (PPT), and polypropylene naphthalate (PPN).

[0059] Fabrics comprising such strands are designed to absorb and dissipate impact energy. The yarns of such fabrics are adapted to stop cracking in the event of perforation by a penetrating object, thus more effectively limiting damage to the conveyor belt. Textile reinforcements usually have an elongation at break of the order of 15 to 25%. It should be noted that the impact protection is essentially due to the transverse yarns 21 of the fabric. In these fabrics, the pitch d2 of the transverse yarns 21 is between 2 and 4 mm. Pitch refers to the distance between the centers of two adjacent yarns or strands. The tensile strength of the transverse yarns 21 of a polyamide fabric is typically on the order of 0.5 to 1 kN. The tensile strength of the fabric 23 in the transverse direction is between 125 and 800 N / mm.

[0060] When the internal structure includes wire cables, as shown in [Fig. 4], the wire cables 26 extend in the transverse direction to maintain the bending of the strip in the longitudinal direction. In this case, the first reinforcement layer further includes textile yarns 27 extending in the longitudinal direction. These textile yarns 27 are typically made of polyamide or polyester and help to hold the transverse wire cables 26 in position. The transverse wire cables 26 used usually have an elongation at break of approximately 4–8%. The distance between the centers of two adjacent transverse wire cables 26 is preferably between 4 and 20 mm.

[0061] With reference to [Fig. 1] and [Fig. 5], the conveyor belt comprises a second reinforcing layer 30 arranged above the first reinforcing layer 20. Preferably, with reference to [Fig. 6A], the second reinforcing layer 30 completely covers a central portion of the belt having a width LR greater than 30% of the width of the conveyor belt. Typically, the central portion The width of the belt covered by the second reinforcement layer 30 corresponds to 30% and 50% of the LB width of the conveyor belt. Thus, the second reinforcement layer 30 covers the area where impacts are most frequent during loading onto the conveyor belt.

[0062] The second reinforcing layer 30 comprises a plurality of metallic reinforcing cables 31. Metallic is defined as a material consisting of at least 50% of its mass of a metallic material. The reinforcing cables are embedded in an elastomeric matrix 35.

[0063] By way of illustration and not limitation, the reinforcing cables are monofilament cables or single-strand cables.

[0064] Preferably, the reinforcing cables are identical. Each reinforcing cable typically comprises between 1 and 26 metallic monofilaments. The monofilaments may have a diameter between 0.18 and 0.45 mm in both the case of a monofilament cable and in the case of a single-strand cable. For example, the reinforcing cables may be single-strand cables comprising four monofilaments with a diameter of 0.23 mm.

[0065] The monofilaments of the reinforcing cables may be made of a metal, preferably steel. The metal or steel used, whether in particular carbon steel or stainless steel, may itself be coated with a metallic layer that improves, for example, the handling properties of the wire rope and / or its constituent elements, or the performance properties of the rope and / or the conveyor belt itself, such as adhesion, corrosion resistance, or resistance to aging. In a preferred embodiment, the steel used is coated with a layer of brass (Zn-Cu alloy) or zinc.

[0066] With reference to [Fig. 7], the reinforcing cables 31 are corrugated in the plane of the strip. In other words, the reinforcing elements are arranged between two parallel planes separated by a distance of approximately the diameter of the reinforcing cables 31, these two planes being parallel to the plane of the strip.

[0067] By corrugation, it is understood that the cables follow a regular sinusoidal or sawtooth pattern with or without clipped crests. The corrugation of the cables prevents an increase in the rigidity of the conveyor belt due to the presence of the reinforcement layer 30. The orientation of this corrugation in the plane of the protective layer makes it possible to limit the thickness of the reinforcement layer 30 and thus limit the thickness of the conveyor belt.

[0068] A layer of corrugated cables in the plane is for example described in FR2518462 and FR2518463.

[0069] The reinforcing cables 31 are arranged parallel to each other in a longitudinal direction of the conveyor belt, i.e. that the undulations of the assembly Reinforcing cables 31 are aligned. This arrangement allows the corrugated cables to be placed at maximum density within the plane of the conveyor belt. The high density of corrugated metal cables provides highly effective protection against even the most severe impacts. This level of protection is significantly higher than that offered by textile reinforcement layers.

[0070] The reinforcing cables 31 preferably have a diameter between 0.18 mm and 2 mm. The distance Dr between the centers of two adjacent reinforcing cables 31 is less than or equal to four times the diameter d of each reinforcing cable, preferably close to twice the diameter of each reinforcing cable. For example, in the case of a diameter d of 0.54 mm for the reinforcing cables, the distance Dr between the centers of two adjacent reinforcing cables 31 can be approximately 1 mm.

[0071] The distance Dr between the centers of two adjacent reinforcing cables 31 is typically such that d + 0.2 mm < Dr < 2d.

[0072] Figure 8 schematically illustrates the geometry of the parallel corrugated cables. The amplitude A is defined as the distance between a crest of maximum 38 and a crest of minimum 38' in a direction perpendicular to the principal axis X of the corrugated cable. The amplitude A of the corrugation of the reinforcing cables 31 is typically between 3 and 8 mm, for example 5.5 mm.

[0073] The wavelength X corresponds to the distance between two maxima 38 of ripple. Typically, the wavelength X is between 10 and 20 mm, for example 14.5 mm.

[0074] The elongation capacity of the corrugated cable assembly depends on the ratio between the amplitude A and the wavelength X. Preferably, the cables exhibit an elongation of at least 20% in the direction of the conveyor belt, which corresponds to the typical elongation at break of the longitudinal wires of the first reinforcement layer 20, which provide the mechanical strength of the belt and are, for example, made of polyamide. The ratio between the corrugation amplitude A and the wavelength X is advantageously greater than or equal to A / X = 0.3 in order to obtain such an elongation of 20% in the second reinforcement layer.

[0075] An elastomeric matrix 35 encases the reinforcing cables 31. The spaces between the reinforcing cables 31 are thus filled with elastomeric material. The space between two respective layers, in particular between the wires and / or cables of the first reinforcing layer 20 and the second reinforcing layer 30, is also filled with an elastomeric material. The elastomeric material arranged between the cables of the two respective layers thus forms a decoupling layer separating the wires and / or cables of the first reinforcing layer 20 and the cables of the second reinforcing layer 30. This decoupling layer is made of the elastomeric material of the first layer of reinforcement and of the second reinforcement layer 30. The total thickness of the elastomeric material of the decoupling layer is between 0.2 mm and 3 mm, preferably between 0.5 mm and 1.5 mm.

[0076] In certain embodiments (not illustrated), the second reinforcement layer consists of several reinforcement layers, each with a width less than the second reinforcement layer 30. In this case, each transport layer comprises parallel corrugated reinforcement cables. The waviness amplitude A and the wavelength X are identical for all reinforcement layers within the same reinforcement layer. The reinforcement layers are placed side-by-side in the longitudinal direction of the strip in a single, parallel thickness, with adjacent layers brought as close together as possible. The undulations of the cables in two adjacent reinforcement layers are therefore in phase.

[0077] With reference to [Fig. 6B] and [Fig. 6C], the conveyor belt may further comprise a third reinforcing layer 40. The third reinforcing layer 40 is arranged below the core 10 of the conveyor belt. The third reinforcing layer 40 comprises an internal structure such as a textile fabric and / or metal cables extending in a transverse direction of the belt and an elastomeric matrix 45 encasing said fabric and / or metal cables.

[0078] The presence of the third reinforcement layer 40 increases the symmetry of the conveyor belt reinforcements and can thus improve the flexural behavior of the conveyor belt during use. The same types of internal structures already described above for the first reinforcement layer are generally used. The third reinforcement layer 40 may be identical to the first reinforcement layer 20 or have a different composition and / or arrangement.

[0079] As illustrated in [Fig.1], the conveyor belt may have a coating 50, for example of an elastic material, on its upper face and / or on its lower face.

[0080] The first elastomeric matrix 15, the matrices 25, 35, 45 of the reinforcing layers, and an optional coating 50 can be made of identical or different elastomeric materials. Advantageously, the respective matrices of a conveyor belt and, where applicable, the coating, are made of materials that facilitate the adhesion of the layers prior to vulcanization, and the assembly of the belt by co-vulcanization of several layers.

[0081] The compounds of the elastomeric matrices and the coating 50 may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the aforementioned compounds may also come from the recycling of materials already used, that is to say, they may be partially or totally derived from a recycling process, or even obtained from raw materials themselves derived from a recycling process. This includes, in particular, the matrix, reinforcing yarns, polymers, plasticizers, fillers, etc.

[0082] The compositions of the elastomeric matrices according to the invention and of the coating are based on at least one elastomer, a reinforcing filler, a crosslinking system.

[0083] Any type of reinforcing filler known for its ability to reinforce a rubber composition can be used, for example an organic filler such as carbon black, an inorganic reinforcing filler such as silica, alumina, or a blend of these two types of filler.

[0084] Preferably, the reinforcing filler content is in the range of 5 to 200 parts per cent, preferably from 20 to 160 parts per cent. The term "part per cent" means, for the purposes of this patent application, parts by weight per hundred parts of elastomers, as determined by the preparation of the composition before baking.

[0085] For the purposes of the invention, the reinforcing filler is preferably chosen from the group consisting of silicas, carbon blacks, and mixtures thereof. More preferably, the reinforcing filler is predominantly carbon black, preferably in a proportion ranging from 30 to 90 parts per cent. Also preferably, the reinforcing filler is predominantly silica, preferably in a proportion ranging from 30 to 90 parts per cent.

[0086] Any type of crosslinking system known to those skilled in the art for its ability to strengthen a rubber composition for the manufacture of conveyor belts can be used.

[0087] Preferably, the crosslinking system is a vulcanization system, i.e., based on sulfur (or a sulfur-donating agent) and a primary vulcanization accelerator. Various known secondary accelerators or vulcanization activators, such as zinc oxide, stearic acid or equivalent compounds, and guanidine derivatives (in particular diphenylguanidine), may be added to this basic vulcanization system, incorporated during the first non-productive phase and / or during the productive phase as described later.

[0088] Sulfur is used at a preferential rate of between 0.5 and 10 pc, more preferably between 0.5 and 5 pc, in particular between 0.5 and 3 pc.

[0089] The vulcanization system for the composition according to the invention may also include one or more additional accelerators, for example, compounds of the thiuram family, zinc dithiocarbamate derivatives, sulfenamides, guanidines, or thiophosphates. In particular, any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur may be used, especially thiazole-type accelerators and their derivatives, thiuram-type accelerators, and zinc dithiocarbamates. These Accelerators are most preferably chosen from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide (abbreviated "CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide (abbreviated "DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide (abbreviated "TBBS"), N-tert-butyl-2-benzothiazyl sulfenamide (abbreviated "TBSI"), zinc dibenzyldithiocarbamate (abbreviated "ZBEC"), and mixtures of these compounds. Preferably, a sulfenamide-type primary accelerator is used.

[0090] The elastomer can be chosen from the group consisting of diene elastomers and mixtures thereof.

[0091] By elastomer (or "rubber", the two terms being considered synonymous) of the "diene" type, it is recalled here that at least one (we mean one or more) elastomer derived at least in part (i.e., a homopolymer or a copolymer) from diene monomers (monomers bearing two carbon-carbon double bonds, conjugated or not) must be understood in a known way.

[0092] Diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". Generally, "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of diene motifs or units (conjugated dienes) greater than 15% (mole percent); thus, diene elastomers such as butyl rubbers or EPDM-type diene-alpha-olefin copolymers do not fall under the preceding definition and can be described in particular as "essentially saturated" diene elastomers (low or very low proportion of diene motifs, always less than 15%). In the category of "essentially unsaturated" diene elastomers, a "highly unsaturated" diene elastomer is defined in particular as a diene elastomer having a rate of diene origin motifs (conjugated dienes) which is greater than 50%.

[0093] Given these definitions, the term diene elastomer, which can be used in the compositions according to the invention, is understood more specifically as:

[0094] (a) any homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms;

[0095] (b) any copolymer obtained by copolymerization of one or more conjugated dienes between themselves or with one or more aromatic vinyl compounds having 8 to 20 carbon atoms;

[0096] (c) a ternary copolymer obtained by copolymerization of ethylene, an α-olefin having 3 to 6 carbon atoms with an unconjugated diene monomer having 6 to 12 carbon atoms, such as for example elastomers obtained from ethylene, propylene with an unconjugated diene monomer of the aforementioned type such as in particular hexadiene-1,4, ethylidene norbomene, dicyclopentadiene;

[0097] (d) a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, particularly chlorinated or brominated, of this type of copolymer.

[0098] Although it applies to any type of diene elastomer, those skilled in conveyor belt design will understand that the present invention is preferably implemented with essentially unsaturated diene elastomers, in particular of type (a) or (b) above.

[0099] Suitable conjugated dienes include, in particular, 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di(alkyl Cl-C5)-1,3-butadiene such as, for example, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, and chloroprene. Examples of suitable vinylaromatic compounds include styrene, ortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, and vinylnaphthalene.

[0100] The copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units. The elastomers may have any microstructure that depends on the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the quantities of modifying and / or randomizing agent used. The elastomers may, for example, be block, statistical, sequenced, or microsequenced, and may be prepared in dispersion or solution; they may be coupled and / or star-shaped or functionalized with a coupling and / or star-shaped or functionalizing agent. The term "functional" here preferably refers to a chemical group that interacts with the reinforcing charge of the composition.

[0101] Preferably, the elastomer of the composition comprises predominantly an essentially unsaturated diene elastomer. The elastomer of the composition is preferably selected from the group consisting of polybutadienes (abbreviated "BR"), synthetic (IR) or natural (NR) polyisoprenes, butadiene copolymers, isoprene copolymers, chloroprene copolymers (e.g., neoprene), and mixtures of these elastomers. Such butadiene and isoprene copolymers are more preferably butadiene-styrene copolymers (SBR) and isoprene-styrene copolymers (SIR), nitrile-butadiene copolymers (NBR), and neoprene, respectively.

[0102] More preferably, the major elastomer is chosen from the group consisting of polybutadienes (BR), butadiene-styrene copolymers (SBR), natural (NR) or synthetic (IR) polyisoprenes, and nitrile-butadiene copolymers. (NBR), chloroprene copolymers (e.g. neoprene) and mixtures of these elastomers.

[0103] The term "composition based on" should be understood as a composition comprising the mixture and / or the in situ reaction product of the various basic constituents used, some of these constituents being able to react and / or intended to react with each other, at least partially, during the various stages of manufacturing the composition, or during subsequent cooking, modifying the composition as initially prepared. Thus, the compositions as implemented for the invention may differ in the uncrosslinked and crosslinked states.

[0104] We will now describe a method for manufacturing a conveyor belt. Such a method typically begins by providing a core comprising the carcass steel cables embedded in a first elastomeric matrix. The carcass cables extend in a longitudinal direction along the belt.

[0105] The first layer of reinforcement and, where applicable, the third layer of reinforcement, are applied in a manner commonly known to those skilled in the art.

[0106] To prepare the second reinforcement layer, straight metal reinforcing cables are placed between two layers of calendered and pressed rubber. Typically, a composite comprising metal reinforcing cables embedded in an elastomeric material to form the second reinforcement layer is supplied as a reel and will subsequently be processed to manufacture the reinforcement layer 30.

[0107] The cables subsequently undergo plastic deformation to adopt a corrugated shape. Advantageously, said deformation is achieved by passing the straight cables, surrounded by layers of rubber, between two crenellated cylinders.

[0108] After deformation, the metal cables are reoriented to arrange the undulations in the plane of the layer so that the cable undulations are in phase. During this step, the elastomeric matrix 35 is not yet cross-linked and follows the reorientation of the cables. The composite consisting of the cables and the elastomeric matrix 35 is thus flattened, and the interstitial spaces between the respective cables are filled by the elastomeric material.

[0109] The width of the cable arrangement corresponds to the intended width of the reinforcement layer to be manufactured, for example, between 30% and 50% of the width of the conveyor belt to be manufactured. In some embodiments, the width corresponds to the width of a layer to be placed alongside other layers. In this case, the width of the cable arrangement is equal to a fraction of the width of the reinforcement layer to be manufactured. Typically, the width of such a fraction is between 100 and 350 mm which facilitates the manufacture and handling of the second layer of reinforcement and allows for sufficiently complete coverage of the strip.

[0110] The corrugated metal cables are thus coated in the elastomeric matrix 35 and form a reinforcing layer.

[0111] Following this step, the reinforcing layer is placed on a central portion of the web comprising the first reinforcing layer and, where applicable, the third reinforcing layer. In the case of multiple layers whose width is a fraction of the width of the second reinforcing layer, said layers are placed side by side in a single thickness on the central portion of the web in a parallel manner, minimizing the space between the respective adjacent layers.

[0112] The reinforcing layer(s) are then bonded to the first reinforcing layer to form the conveyor belt. The elastomeric material is brought to its solid state by crosslinking, for example, by vulcanization. Typically, the elastomeric matrices 15, 25, 35 are crosslinked, for example, vulcanized, only after the reinforcing layers and the belt core have been assembled. After the core and reinforcing layers are superimposed, the layers are pressed together, resulting in initial bonding due to the natural adhesion of the elastomeric matrices. The crosslinking, in particular the vulcanization, is carried out in several sections, for example, ten meters long. The elastomeric material of all the layers is crosslinked together in a single step per section. Each section is mechanically pressed to fix the reinforcing layers.Heat treatment can also be applied to the section during mechanical pressing. This procedure is repeated until the reinforcing layer is bonded along the entire length of the conveyor belt.

[0113] After the application of the second reinforcing layer, a coating, for example of an elastomeric material such as rubber, can be applied to the upper and / or lower face of the conveyor belt. Typically, such coatings are applied before the belt is cross-linked and cross-linked together with the core and the reinforcing plies. References

[0114] FR2518462

[0115] FR2518463

Claims

Demands

1. Conveyor belt (100) comprising: • a core (10) comprising carcass metal cables (11) extending in a longitudinal direction of the conveyor belt (100), said carcass metal cables (11) being encased in a first elastomeric matrix (15); • a first reinforcement layer (20) arranged above the core, said first reinforcement layer comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt (100) and a second elastomeric matrix (25) encasing said fabric and / or metal cables;and • a second reinforcement layer (30) disposed above the first reinforcement layer (20), said second reinforcement layer (30) comprising a plurality of corrugated metallic reinforcement cables (31) in the plane of the conveyor belt (100), arranged parallel to each other in a longitudinal direction of the conveyor belt (100), and a third elastomeric matrix (35) encasing the reinforcement cables (31).

2. Conveyor belt (100) according to claim 1, wherein the distance (Dr) between the centers of two adjacent corrugated metal reinforcing cables (31) is less than or equal to four times the diameter of each corrugated metal reinforcing cable (31), preferably twice the diameter of each reinforcing cable.

3. Conveyor belt (100) according to claim 1 or claim 2, wherein the amplitude of undulation (A) of the reinforcing cables (31) is between 3 and 8 mm, preferably 5.5 mm.

4. Conveyor belt (100) according to any one of the preceding claims, wherein the wavelength (X) of the reinforcing cables (31) is between 10 and 20 mm, preferably 14.5 mm.

5. Conveyor belt (100) according to any one of the preceding claims, wherein the ratio between the waviness amplitude (A) and the waviness period (X) is greater than or equal to 0.

3.

6. Conveyor belt (100) according to any one of the preceding claims, wherein the reinforcing cables (31) cover a central portion of the conveyor belt (100) having a width (Lr) greater than 30% of the width of the conveyor belt (100),

7. Conveyor belt (100) according to any one of the preceding claims, wherein the reinforcement layer (30) comprises a plurality of reinforcement plies juxtaposed in a single thickness on an upper face of the core (10) in a transverse direction of the conveyor belt (100), each reinforcement ply comprising reinforcing cables (31) of corrugated metal in the plane of the conveyor belt (100) embedded in an elastomeric matrix (35).

8. Conveyor belt (100) according to claim 7, wherein the width of each reinforcement layer (33) is between 100 and 350 mm.

9. Conveyor belt (100) according to any one of the preceding claims, wherein each reinforcing cable (31) comprises between 1 and 26 metallic monofilaments.

10. Conveyor belt (100) according to any one of the preceding claims, wherein the diameter of the reinforcing cables (31) is between 0.18 mm and 2 mm.

11. Conveyor belt (100) according to any one of the preceding claims, further comprising a third reinforcement layer (40) arranged below the core (10), said third reinforcement layer (40) comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt (100) and an elastomeric matrix (45) encasing said fabric and / or metal cables.

12. Conveyor belt (100) according to any one of the preceding claims, further comprising an upper coating and / or a lower coating of an elastomeric material.

13. Method of manufacturing a conveyor belt (100), comprising • providing a core (10) comprising carcass metal cables (11) extending in a longitudinal direction of the conveyor belt (100), said carcass metal cables (11) being coated in a first elastomeric matrix (15); • the application of a first reinforcement layer (20) over the core (10), said first reinforcement layer (20) comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt (100) and a second elastomeric matrix (25) encasing said fabric and / or metal cables; • the deformation of a sheet comprising parallel metallic cables (31) so that the cables form undulations, said cables being coated in a third elastomeric matrix (35); • the realignment of the corrugated metal cables (31) so that the corrugations are arranged in a plane; • the covering of the upper face of the first reinforcement layer (20) by the second reinforcement layer (30), so that the corrugated metal cables (31) extend in a longitudinal direction of the conveyor belt (100).

14. A method according to claim 13, further comprising the application of a third layer of reinforcement (40) on an underside of the core (10), said third layer of reinforcement comprising a textile fabric and / or metal cables extending in a transverse direction of the conveyor belt (100) and an elastomeric matrix encasing said fabric and / or metal cables.

15. A method according to claim 13 or claim 14, wherein the covering of the upper face of the first reinforcement layer (20) comprises laying at least two reinforcement layers comprising identical corrugated metal cables (31) in parallel in a longitudinal direction of the conveyor belt (100).

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