Conveyor belt

Abstract

The present invention relates to a conveyor belt (100) comprising: a core (10) comprising metal carcass cables (11) extending in a longitudinal direction of the belt (100), said metal carcass cables (11) being embedded in a first elastomeric matrix (15), and a reinforcing layer (30) covering at least partially the upper face of the core (10), said reinforcing layer comprising a plurality of metal reinforcing cables (21) arranged parallel to each other in a transverse direction of the belt, each reinforcing cable (21) comprising a plurality of metal monofilaments (23) wound helically around an arch, and a second elastomeric matrix (25) embedding the monofilaments (23). Figure for the abstract: 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 an elastomeric 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 when impacted by very sharp objects such as dolerite or slate. Furthermore, despite their stretchability, such reinforcements significantly increase the rigidity of the conveyor belt.

[0009] Other types of reinforcement include transverse metal cables held in position by longitudinal metal or textile binding threads, for example, made of polyamide or polyester. Protective reinforcements based on metal cables typically have a higher breaking strength than textile reinforcements. The transverse metal cables used have an elongation at break of approximately 4-8%. Despite this high value for a metal cable, such supports increase the rigidity of the conveyor belt more significantly than textile reinforcements. Thus, conveyor belts with such support are rigid in bending, which can disrupt the belt's behavior and, in particular, its stability on the transport rollers. Furthermore, metal cables are less flexible than a textile reinforcement and therefore cannot organize themselves at the bottom of a crack to create a thicker reinforcement in that position. Summary of the invention

[0010] One object of the invention is to design a conveyor belt exhibiting improved resistance to breakage, 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 strip, said carcass metal cables being embedded in a first elastomeric matrix and • a reinforcing layer covering at least partially the upper surface of the core, said reinforcing layer comprising • a plurality of metal reinforcing cables, arranged parallel to each other in a transverse direction of the strip, each reinforcing cable comprising a plurality of metal monofilaments wound helically around an arch, and • a second elastomeric matrix coating the monofilaments.

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

[0013] - the reinforcing cables have a total elongation at break greater than 8%, the total elongation at break being measured according to ASTM D 2969-00;

[0014] - the reinforcing layer comprises a plurality of reinforcing layers juxtaposed in a single thickness on one upper face of the core in a longitudinal direction of the strip;

[0015] - the distance between two adjacent reinforcing cables is less than or equal to 4 mm, of preference of 2.2 mm;

[0016] - each reinforcing cable has a monofilament diameter Df and a radius of helix curvature Rf such that: 9 < Rf / Df < 30, and the arch is defined by a radially internal cylinder tangent to each monofilament, said cylinder having an arch diameter Dv such that 1.30 < Dv / Df < 4.5;

[0017] - each reinforcing cable comprises between 3 and 10 monofilaments, preferably 5 monofilaments;

[0018] - each monofilament has a diameter Df between 0.1 and 0.5 of preference 0.35 mm;

[0019] - each reinforcing cable (21) has an external diameter between 0.9 and 2.1, preferably 1.9 mm, and / or an internal arch diameter between 0.4 and 1.3, preferably 1.2 mm;

[0020] - the reinforcing cables extend over a width less than or equal to the width of the conveyor belt, preferably between 95% and 100% of the width of the conveyor belt;

[0021] - the conveyor belt further comprises a top coating and / or a lower coating made of elastomeric matrix;

[0022] - the conveyor belt further comprises a reinforcing layer arranged on one face inferior of the soul.

[0023] 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 strip, said metal cables being coated in a first elastomeric matrix; • the provision of a plurality of reinforcement cables, each reinforcement cable comprising a plurality of metallic monofilaments wound helically around an arch; • the arrangement of the reinforcement cables in a parallel manner in a plane; • the encasement of all the reinforcing cables in a matrix elastomeric so that each monofilament is embedded in the elastomeric matrix; • the covering of the upper face of the core by a plurality of reinforcing layers in the longitudinal direction of the strip, the reinforcing cables extending in a transverse direction of the strip.

[0024] Said method optionally includes covering the underside of the core with a plurality of reinforcing layers as described above. BRIEF DESCRIPTION OF THE FIGURES

[0025] Other features and advantages will become apparent from the detailed description that follows, with reference to the accompanying drawings, on which:

[0026] - Fig. 1 is a perspective view of a portion of a conveyor belt according to the invention;

[0027] - [Fig. 2A] illustrates a first embodiment of the arrangement of monofilaments in a core cable;

[0028] - [Fig. 2B] illustrates a second embodiment of the arrangement of monofilaments in a core cable;

[0029] - [Fig. 3] is a perspective view of a reinforcing layer for a strip conveyor according to the invention;

[0030] - [Fig. 4] is a perspective view of the core cables and reinforcing cables of a conveyor belt according to the invention;

[0031] - [Fig. 5A] is a top view of the metal cables present in a strip conveyor;

[0032] - [Fig.5B] is a cross-sectional view of the cables of [Fig.5A];

[0033] - [Fig.5C] is a longitudinal cross-sectional view of the cables of [Fig.5A];

[0034] - [Fig.6] is a perspective view of a plurality of open reinforcing cables;

[0035] - [Fig.7] illustrates the arrangement of monofilaments in a hyperelastic wire.

[0036] For reasons of readability of the figures, the illustrated elements are not necessarily represented to scale. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0037] In this text, the terms "front" and "rear", "anterior" and "posterior" refer to the direction of movement of the conveyor belt during its use. The terms "vertical", "horizontal", "upper", and "lower" refer to the position of an object transported on the belt oriented in the direction of transport.

[0038] 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 metal cables 11 embedded in an elastomeric matrix, preferably rubber. The carcass cables 11 are the main cables of the conveyor belt and extend in a longitudinal direction x corresponding to the direction of the tape's circulation. By way of illustration and not limitation, carcass cables are typically multi-strand metallic cables, 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.

[0039] By way of illustration and without limitation, the 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. In another example, with reference to [Fig. 2B], the carcass cables 11B may, for example, comprise seven strands 12 of nineteen monofilaments 13 per strand. Such cables typically have a diameter of between 4 and 14 mm.

[0040] The monofilaments of the carcass cables are, for example, made of steel, preferably pearlitic steel, carbon ferritic-pearlitic steel, or stainless steel containing at least 10.5% chromium. The monofilaments may have a coating comprising copper, zinc, pein, cobalt, or an alloy of these metals, for example, brass or bronze. Each metallic monofilament typically has a mechanical strength of 1000 MPa to 5000 MPa.

[0041] The mechanical resistance measurement is carried out according to ASTM D 2969-00 on a metal cable intended for tire reinforcement.

[0042] The initial section of the wire rope (So) is determined upstream of a tensile measurement.

[0043] 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.

[0044] The cable is held by clamps allowing the metal cables to be extended until they break outside the clamp's gripping area. Clamps with a gradual curve are therefore preferably used.

[0045] 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).

[0046] This preload is estimated beforehand on the basis of 3 force measurements at break carried out with the same device.

[0047] The measurement consists of recording the force curve as a function of the cable elongation until the break occurs.

[0048] 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.

[0049] The maximum mechanical resistance Rm is determined from the maximum force Fm and the initial section of the specimen So according to „ rup i _ -^4^] . - laugh

[0050] The carcass cables 11 are arranged in parallel and coated with an elastomeric matrix 15. The distance between the centers of two carcass cables Da is typically between 10 and 19 mm.

[0051] The conveyor belt further comprises at least one reinforcing layer 30, 40. A first reinforcing layer 30 is typically arranged on the upper face of the web. A second reinforcing layer 40 may be arranged on the lower face of the web. The use of two reinforcing layers arranged on opposite faces of the web protects the belt against stress on both sides. The symmetry of the reinforcing layers can also improve the flexural behavior of the conveyor belt during use.

[0052] Typically, each reinforcement layer 30, 40 covers between 95% and 100% of the width of the core 10 to maximize the coverage of the conveyor belt and provide good protection over the entire width of the belt, without exceeding the edges of the conveyor belt.

[0053] Each reinforcement layer comprises a plurality of reinforcing cables 21 arranged parallel to each other in a transverse direction t of the strip. The reinforcing cables 21 are therefore perpendicular to the carcass cables 11. Advantageously, in order to provide optimal protection against impacts and cracking, the distance Dr between two adjacent reinforcing cables 21 is less than or equal to 4 mm, for example 2.2 mm as illustrated in [Fig. 3].

[0054] The reinforcing cables 21 are embedded in an elastomeric matrix 25.

[0055] Preferably, each reinforcement layer 30, 40 comprises a plurality of reinforcement plies 20 placed side by side in the longitudinal direction x of the belt in a single thickness. Typically, a reinforcement ply 20 has a rectangular shape with a width less than or equal to the width of the reinforcement layer 30, 40. The length of each reinforcement ply is typically identical for all reinforcement plies 20 of the conveyor belt and is, for example, between 0.5 and 5 times the width of the ply. In this case, each reinforcement ply 20 comprises a plurality of reinforcement cables 21 embedded in an elastomeric matrix. Figure 3 schematically illustrates such a reinforcement ply. The plies are placed side by side along the entire length of the conveyor belt so that the reinforcement cables are arranged in the transverse direction of the belt.

[0056] Figure 4 illustrates the arrangement of the carcass cables 11 and the reinforcement layers 30, 40 in the conveyor belt. The reinforcement cables 21 have a smaller diameter than the carcass cables 11 and are oriented perpendicularly to the carcass cables. With reference to Figure 5A, the distance Dr between the reinforcement cables 21 is less than the distance Da between the carcass cables 11, thus preventing objects from penetrating between the carcass cables.

[0057] With reference to [Fig.5B] and [Fig.5C], the carcass cables 11 and the reinforcing cables 21 are arranged in separate layers, with a vertical spacing between the respective layers.

[0058] Preferably, the vertical distance Dz in the z direction between the carcass cables 11 and the reinforcing cables 21 is between 1 and 3 mm, preferably 1.5 mm. This space is filled by a portion of the elastomeric matrix of the core 10 and a portion of the elastomeric matrix of the reinforcing layer 30 and 40.

[0059] The space between the carcass cables 11 and the reinforcing cables 21 is completely filled by one or more elastomeric materials.

[0060] The conveyor belt may have a coating 50, for example in an elastomeric matrix, on its upper face and / or on its lower face.

[0061] The open reinforcing cables are metal cables, preferably hyperelastic metal cables. By hyperelastic, it is understood that the total elongation at break is greater than 8%, for example on the order of 10%.

[0062] The measurement of the total elongation at break is carried out according to the ASTM D 2969 - 00 standard on a metal cable intended for the reinforcement of tires.

[0063] The measurement is carried out using one or more cable samples extracted from a conveyor belt. Each cable sample has an arch filled with vulcanized elastomeric material.

[0064] 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 an extensometer, preferably a mechanical extensometer that is in contact with the wire rope.

[0065] 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.

[0066] The 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).

[0067] This preload is estimated beforehand on the basis of 3 force measurements at break carried out with the same device.

[0068] The measurement consists of recording the force curve as a function of the cable elongation until the break occurs.

[0069] 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.

[0070] The elongation measured at the point of rupture is called the total elongation At and is calculated as follows: [O071]

[0072] with:

[0073] Lt = The distance between the arms of the extensometer at the time of rupture in mm,

[0074] Lo = The initial distance between the arms of the extensometer in mm.

[0075] The result of the test is the value measured on a single test specimen.

[0076] 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 conveyor belt cable 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.

[0077] Figures 6 and 7 illustrate an assembly of open reinforcing cables 21 in a reinforcement layer. Each open reinforcing cable 21 comprises a single layer made up of N metallic monofilaments 23, N being an integer, typically between three and ten. Preferably, the layer consists of five monofilaments 23. Each metallic monofilament has a diameter Df.

[0078] A monofilament is defined as an element extending longitudinally along a principal axis and having a cross-section perpendicular to the principal axis, the largest dimension G of which is relatively small compared to the dimension L along the principal axis. Relatively small means that L / G is greater than or equal to 100, preferably greater than or equal to 1000. This definition covers both monofilaments with a circular cross-section and wire elements with a non-circular cross-section, for example, a polygonal or oblong cross-section. Most preferably, each metallic monofilament has a circular cross-section.

[0079] The monofilaments 23 are wound in a helix with a helix radius of curvature Rf. The helix radius of curvature is equal to Rf=P / (jr-sin(2a)) with P the pitch of each metallic monofilament and a the helix angle of each metallic monofilament. Thus, each metallic monofilament describes a helical trajectory around a principal axis substantially parallel to the principal axis of the cable. Referring to [Fig. 7], the external diameter D of the set of N monofilaments 23 corresponds to the external diameter of each helix. The monofilaments 23 define an internal arch 27 of the cable. The reinforcing cable 21 therefore lacks a central metallic core. The internal arch 27 of the open reinforcing cable 21 is delimited by the monofilaments 23.

[0080] The preforming and the internal vault provide the cable, once assembled, with relatively significant ventilation, in other words, a relatively large space between each pair of adjacent monofilaments compared to the diameter of the monofilaments.

[0081] Preferably, the internal arch 27 has the shape of a right circular cylinder (also called a right circular cylinder). In this case, the internal arch 27 corresponds to a radially internal cylinder tangent to each monofilament. The diameter of said cylinder is equal to the arch diameter Dv.

[0082] The helix diameter Dh is calculated according to the relation Dh=P x Tan(a) / ir in which P is the pitch at which each metallic monofilament is wound, a is the helix angle of each monofilament and Tan is the tangent function.

[0083] In a cross-sectional plane perpendicular to the main axis of the open reinforcing cable 21, the distance Dh / 2 between the center C of each metallic monofilament and the main axis of the cable is substantially constant and equal for all the metallic monofilaments in the layer. This distance Dh / 2 is equal to half the helix diameter Dh.

[0084] The open reinforcing cable is single helix. By definition, a single helix cable is a cable in which the axis of each metallic monofilament of the layer describes a single helix, unlike a double helix cable in which the axis of each monofilament describes a first helix around the axis of the cable and a second helix around a helix described by the axis of the cable.

[0085] In a particularly advantageous manner, each reinforcing cable has a monofilament diameter Df and a helix bending radius Rf such that: 9 < Rf / Df < 30. Preferably, the internal arch diameter Dv is such that 1.30 < Dv / Df < 4.5.

[0086] Preferably, each monofilament has a diameter Df between 0.1 and 0.5, preferably 0.35 mm.

[0087] Each reinforcing cable may have an external diameter between 0.9 and 2.1, preferably 1.9 mm.

[0088] The internal arch diameter is advantageously between 0.4 and 1.3, preferably 1.2 mm.

[0089] The relative radial clearance Jr can be defined by Jr = N / (ir-(D - Df)) • (Dh • Sin(ir / N) - (Df / Cos(a • ji / 180))), where N is the number of metallic wire elements in the layer. This parameter represents the distance separating each pair of adjacent metallic monofilaments relative to the length available for positioning the metallic monofilaments on the layer. Thus, the higher the relative radial clearance Jr, the greater the space separating two adjacent metallic monofilaments relative to the maximum number of metallic monofilaments that the layer could accommodate. Conversely, the smaller Jr, the smaller the space separating two adjacent metallic monofilaments relative to the maximum number of metallic monofilaments that the layer could accommodate.

[0090] Advantageously, the relative radial clearance is such that 0.10 mm < Jr < 0.25 mm, allowing the number of metallic monofilaments present in a layer to be maximized and thus the reinforcement capacity of the cable to be maximized, without however deteriorating the capacity to accommodate longitudinal compression deformations.

[0091] Generally, the elastomeric matrix 25 of the reinforcement layer 20 encases all the monofilaments 23 included in the open reinforcement cables 21. The internal vault 27 of each reinforcement cable 21 is therefore also filled by the elastomeric material of the matrix 25.

[0092] An open reinforcing cable comprising a single layer of helically wound metallic monofilaments and a method for manufacturing such a cable are described in FR3099191A1. Such cables are also known as "open cord" in Anglo-Saxon terminology.

[0093] Alternatively, an open reinforcing cable in the reinforcing layer can be a multi-strand of open reinforcing cables as described above.

[0094] Table 1 shows a comparison of the different types of conveyor belt reinforcement. The measurements were taken on an isolated reinforcement strip, not assembled to a conveyor belt. The right-hand column presents the values ​​of an example of a reinforcement layer according to the invention made with open reinforcement cables with the following parameters:

[0095]

[0096]

[0097]

[0098] Diameter of a monofilament Df = 0.35 mm External diameter of the open reinforcing cable D = 1.9 mm Diameter of the internal arch Dv = 1.2 mm Number of monofilaments N = 5.

[0099] Polyamide fabric of known material Fabric with transverse metal cables Reinforcement with open metal cables Example Breaking strength of transverse reinforcements: 0.5-kN 1.2-3.8kN 0.5-2kN 1kN Elongation at break of transverse reinforcements: 15-25% 4-8% 8-15% 10% No transverse reinforcements: 2-4mm 4-20mm 2-4mm 2.2mm Transverse strength: 150-800N / mm 120-800N / mm 200-1000N / mm 500N / mm Interlacing of protective reinforcement: yes yes No no

[0100] The breaking strength of a reinforcement layer with open reinforcing cables is therefore greater than or equal to the breaking strength of a reinforcement layer comprising a polyamide fabric reinforcement. The range of breaking strength values ​​of a conveyor belt according to the invention overlaps with the values ​​corresponding to a reinforcement layer with transverse wire cables. The reinforcement layer according to the invention can therefore withstand the same impacts as known belts.

[0101] The transverse resistance of a reinforcement layer comprising open reinforcing cables is comparable to the transverse resistance that can be obtained for reinforcement layers comprising polyamide fabric or transverse metal cables.

[0102] The use of a reinforcement with transverse open reinforcing cables makes it possible to avoid a disturbance of the transverse flexibility of the conveyor belt while allowing sufficient deformation of the reinforcing cables in any crack areas, thanks to the optimized modulus of elasticity of the open reinforcing cables.

[0103] A reinforcement layer using such open reinforcement cables has a reduced thickness of protective reinforcement compared to polyamide textile fabrics.

[0104] Compared with a known reinforcement layer using transverse metal cables held in position by binding wires, the density of open reinforcement cables can be higher than the density of metal cables in a known reinforcement layer.

[0105] The open reinforcing cables exhibit very high mobility within the elastomeric matrix, which results in high resistance to breakage of the strip, particularly against longitudinal cracks.

[0106] The cables also exhibit very high compressibility in the event of transverse force under impact, for example due to the fall of a sharp object. This prevents excessive local overloads that would lead to cable breakage.

[0107] The transverse arrangement of the open reinforcement cables allows the longitudinal flexibility of the conveyor belt to be maintained.

[0108] The first elastomeric matrix of the core 15, the matrix 25 of the reinforcing layer, 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.

[0109] The compounds of the elastomeric matrices 15, 25 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 previously used materials, that is to say, they may be partially or totally derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, the matrix, reinforcing yarns, polymers, plasticizers, fillers, etc.

[0110] The compositions of the elastomeric matrices according to the invention and of the coating are based on at least one elastomer, a reinforcing filler, and a crosslinking system.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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 primary accelerator of the sulfenamide type is used.

[0118] The elastomer can be chosen from the group consisting of diene elastomers and mixtures thereof.

[0119] 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.

[0120] 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 diene-alpha-olefin copolymers like EPDM do not fall under the previous definition and can be specifically described as "essentially saturated" diene elastomers (low or very low content of diene-derived motifs, always less than 15%). Within the category of "essentially unsaturated" diene elastomers, a "highly unsaturated" diene elastomer is defined as one with a content of diene-derived motifs (conjugated dienes) greater than 50%.

[0121] Having given these definitions, the term diene elastomer capable of being used in the compositions according to the invention is understood more particularly as:

[0122] (a) any homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms;

[0123] (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;

[0124] (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;

[0125] (d) a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, particularly chlorinated or brominated, of this type of copolymer.

[0126] 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.

[0127] 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.

[0128] 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 The quantities of modifying and / or randomizing agents used. Elastomers can be, for example, block, statistical, sequenced, or microsequenced, and can be prepared in dispersion or solution; they can be coupled and / or star-shaped or functionalized with a coupling and / or star-shaped or functionalizing agent. Here, "functional" preferably refers to a chemical group that interacts with the reinforcing charge of the composition.

[0129] 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.

[0130] More preferably, the major elastomer is chosen from the group consisting of polybutadienes (BR), butadiene-styrene copolymers (SBR), natural (NR) or synthetic (IR) polyisoprenes, nitrile-butadiene copolymers (NBR), chloroprene copolymers (for example neoprene) and mixtures of these elastomers.

[0131] 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. Conveyor belt manufacturing

[0132] 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 coated in a first elastomeric layer. The carcass cables extend in a longitudinal direction along the belt.

[0133] A second step is the preparation of the reinforcement layer. For this purpose, open reinforcing cables are arranged parallel to each other in a plane. Each open reinforcing cable comprises a plurality of helically wound metallic monofilaments, so as to define an internal arch within the cable. The cables are embedded in an elastomeric matrix so that each monofilament of Each cable is embedded in the matrix. To achieve this embedding, the cables are typically pressed between two layers of pre-calendered elastomeric material. The elastomeric layers are unvulcanized and undergo plastic deformation during pressing. This allows the elastomeric material to completely fill the space between and within the cables.

[0134] During this step, the internal vault of each respective cable is also filled with the elastomeric material of the matrix.

[0135] The open reinforcing cables and the matrix are subsequently cut into a plurality of layers. Each layer has, in a longitudinal direction of the reinforcing cables, a length L corresponding to 95% to 100% of the width of the conveyor belt. The layers are then placed side by side to form a reel with a width corresponding to 95% to 100% of the width of the conveyor belt, with the cables arranged transversely.

[0136] Preferably, the tablecloths are of rectangular geometry.

[0137] Following this step, part of the upper surface of the core is covered by the reinforcing layers, so that the open reinforcing cables in the reinforcing layers are arranged transversely to the conveyor belt. If necessary, the lower surface of the same part of the belt can also be covered with reinforcing layers.

[0138] Typically, the matrices are cross-linked, for example vulcanized, only after the reinforcement plies and the core of the strip have been assembled. After the core and reinforcement layers are superimposed, all the layers are pressed together, resulting in initial bonding due to the natural adhesion of the elastomeric matrices. The plies stacked on the core are typically vulcanized under appropriate pressure and curing temperature. Cross-linking is carried out on the stack in several sections, for example, ten meters long.

[0139] The coating, curing, and pressing steps are repeated on subsequent sections until cross-linking is achieved, preferably vulcanization of the core and the reinforcing layer over the entire length of the strip. The elastic material inside the core of each reinforcing cable is cross-linked together with the elastomeric matrices of the respective core and reinforcing layer.

[0140] When the core is completely covered with reinforcing plies, a coating, for example of an elastic material, 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

[0141] FR3099191A1

Claims

Demands

1. Conveyor belt (100) comprising: • a core (10) comprising carcass metal cables (11) extending in a longitudinal direction of the belt (100), said carcass metal cables (11) being embedded in a first elastomeric matrix (15) and • a reinforcement layer (20) covering at least partially the upper face of the core (10), said reinforcement layer comprising • a plurality of metal reinforcement cables (21), arranged parallel to each other in a transverse direction of the belt, each reinforcement cable (21) comprising a plurality of metal monofilaments (23) wound helically around an arch, and • a second elastomeric matrix (25) embedding the monofilaments (23).

2. Conveyor belt (100) according to claim 1, wherein the reinforcing cables have a total elongation at break greater than 8%, the total elongation at break being measured according to ASTM D 2969-00.

3. Conveyor belt (100) according to claim 1 or claim 2, comprising a plurality of reinforcing plies (20) juxtaposed in a single thickness on an upper face of the core (10) in a longitudinal direction of the belt (100).

4. Conveyor belt (100) according to any one of the preceding claims, wherein the distance (Dr) between two adjacent reinforcing cables (21) is less than or equal to 4 mm, preferably 2.2 mm.

5. Conveyor belt (100) according to any one of the preceding claims, wherein each reinforcing cable (21) has a monofilament diameter Df and a helix bending radius Rf such that: 9 < Rf / Df < 30, and the arch is defined by a cylinder radially internal and tangent to each monofilament, said cylinder having an arch diameter Dv such that 1.30 < Dv / Df < 4.

5.

6. Conveyor belt (100) according to any one of the preceding claims, wherein each reinforcing cable (21) comprises between 3 and 10 monofilaments (23), preferably 5 monofilaments.

7. Conveyor belt (100) according to any one of the preceding claims, wherein each monofilament (23) has a diameter Df between 0.1 and 0.5, preferably 0.35 mm.

8. Conveyor belt (100) according to any one of the preceding claims, wherein each reinforcing cable (21) has an external diameter of between 0.9 and 2.1, preferably 1.9 mm, and / or an internal arch diameter of between 0.4 and 1.3, preferably 1.2 mm.

9. Conveyor belt (100) according to any one of the preceding claims, wherein the reinforcing cables (21) extend over a width less than or equal to the width of the conveyor belt (100), preferably between 95% and 100% of the width of the conveyor belt.

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

11. Conveyor belt (100) according to any one of the preceding claims further comprising a reinforcing layer arranged on an underside of the core.

12. A method for manufacturing a conveyor belt (100), comprising: • providing a core comprising carcass wire ropes (11) extending in a longitudinal direction of the belt (100), said wire ropes (11) being embedded in a first elastomeric matrix (15); • providing a plurality of reinforcement wires (21), each reinforcement wire (21) comprising a plurality of metallic monofilaments (23) wound helically around an arch; • arranging the reinforcement wires (21) parallel to each other in a plane; • embedding all the reinforcement wires (21) in an elastomeric matrix (25) such that each

13. monofilament (23) is coated in the elastomeric matrix (25); • the covering of the upper face of the core by a plurality of reinforcing layers (23) in the longitudinal direction of the strip (100), the reinforcing cables (21) extending in a transverse direction of the strip (100). Method according to claim 12, further comprising covering the underside of the core with a plurality of reinforcing layers (30).

Images