Classifications

• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B5/00—Making ropes or cables from special materials or of particular form
  • D07B5/12—Making ropes or cables from special materials or of particular form of low twist or low tension by processes comprising setting or straightening treatments
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  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/16—Ropes or cables with an enveloping sheathing or inlays of rubber or plastics
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B3/00—General-purpose machines or apparatus for producing twisted ropes or cables from component strands of the same or different material
  • D07B3/02—General-purpose machines or apparatus for producing twisted ropes or cables from component strands of the same or different material in which the supply reels rotate about the axis of the rope or cable or in which a guide member rotates about the axis of the rope or cable to guide the component strands away from the supply reels in fixed position
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B7/00—Details of, or auxiliary devices incorporated in, rope- or cable-making machines; Auxiliary apparatus associated with such machines
  • D07B7/02—Machine details; Auxiliary devices
  • D07B7/14—Machine details; Auxiliary devices for coating or wrapping ropes, cables, or component strands thereof
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B7/00—Details of, or auxiliary devices incorporated in, rope- or cable-making machines; Auxiliary apparatus associated with such machines
  • D07B7/02—Machine details; Auxiliary devices
  • D07B7/14—Machine details; Auxiliary devices for coating or wrapping ropes, cables, or component strands thereof
  • D07B7/145—Coating or filling-up interstices
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  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
  • D07B1/0606—Reinforcing cords for rubber or plastic articles
  • D07B1/062—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
  • D07B1/0606—Reinforcing cords for rubber or plastic articles
  • D07B1/062—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration
  • D07B1/0626—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration the reinforcing cords consisting of three core wires or filaments and at least one layer of outer wires or filaments, i.e. a 3+N configuration
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/10—Rope or cable structures
  • D07B2201/1012—Rope or cable structures characterised by their internal structure
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2023—Strands with core
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2024—Strands twisted
  • D07B2201/2025—Strands twisted characterised by a value or range of the pitch parameter given
• • D—TEXTILES; PAPER
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  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2024—Strands twisted
  • D07B2201/2027—Compact winding
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2024—Strands twisted
  • D07B2201/2027—Compact winding
  • D07B2201/2028—Compact winding having the same lay direction and lay pitch
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2024—Strands twisted
  • D07B2201/2029—Open winding
  • D07B2201/203—Cylinder winding, i.e. S/Z or Z/S
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2024—Strands twisted
  • D07B2201/2029—Open winding
  • D07B2201/2031—Different twist pitch
  • D07B2201/2032—Different twist pitch compared with the core
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2038—Strands characterised by the number of wires or filaments
  • D07B2201/2039—Strands characterised by the number of wires or filaments three to eight wires or filaments respectively forming a single layer
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2015—Strands
  • D07B2201/2046—Strands comprising fillers
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2047—Cores
  • D07B2201/2052—Cores characterised by their structure
  • D07B2201/2059—Cores characterised by their structure comprising wires
  • D07B2201/2061—Cores characterised by their structure comprising wires resulting in a twisted structure
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2201/00—Ropes or cables
  • D07B2201/20—Rope or cable components
  • D07B2201/2047—Cores
  • D07B2201/2052—Cores characterised by their structure
  • D07B2201/2059—Cores characterised by their structure comprising wires
  • D07B2201/2062—Cores characterised by their structure comprising wires comprising fillers
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2205/00—Rope or cable materials
  • D07B2205/20—Organic high polymers
  • D07B2205/2075—Rubbers, i.e. elastomers
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2205/00—Rope or cable materials
  • D07B2205/20—Organic high polymers
  • D07B2205/2075—Rubbers, i.e. elastomers
  • D07B2205/2082—Rubbers, i.e. elastomers being of synthetic nature, e.g. chloroprene
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2205/00—Rope or cable materials
  • D07B2205/30—Inorganic materials
  • D07B2205/3021—Metals
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2207/00—Rope or cable making machines
  • D07B2207/20—Type of machine
  • D07B2207/204—Double twist winding
  • D07B2207/205—Double twist winding comprising flyer
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2207/00—Rope or cable making machines
  • D07B2207/40—Machine components
  • D07B2207/4072—Means for mechanically reducing serpentining or mechanically killing of rope
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2501/00—Application field
  • D07B2501/20—Application field related to ropes or cables
  • D07B2501/2046—Tire cords

Definitions

• the present invention relates to processes and devices for manufacturing two-layer metal cables, of M + N construction, used in particular for the reinforcement of rubber articles, in particular tires.
• a radial tire comprises in known manner a tread, two inextensible beads, two flanks connecting the beads to the tread and a belt circumferentially disposed between the carcass reinforcement and the tread.
• This belt consists of various plies (or “layers") of rubber reinforced or not by reinforcing elements (“reinforcements”) such as cords or monofilaments, metal or textile type.
• the tire belt generally consists of at least two superimposed belt plies, sometimes called “working” plies or “crossed” plies, whose reinforcing cords, generally of metal, are arranged substantially parallel to each other at the same time. interior of a web, but crossed from one web to another, that is to say inclined, symmetrically or otherwise, with respect to the median circumferential plane, of an angle which is generally between 10 ° and 45 ° depending on the type of tire considered.
• the crossed plies may be supplemented by various other plies or layers of auxiliary rubber, of variable widths depending on the case, with or without reinforcements;
• examples of simple rubber cushions include so-called “protection” plies intended to protect the rest of the belt from external aggression, perforations, or so-called “hooping” plies comprising reinforcements oriented substantially along the circumferential direction (so-called “zero degree” plies), whether radially external or internal with respect to the crossed plies.
• the third requirement is particularly strong for tire casings for industrial vehicles such as heavy vehicles, designed to be retreaded once or more when the treads they comprise reach a degree of critical wear after prolonged rolling.
• layered cords consisting of a central core and one or more layers of concentric threads arranged around this soul.
• the most widely used layered cables are essentially M + N or M + N + P construction cables, formed of a core of M wire (s) surrounded by at least one layer of N wires which may itself be surrounded by an outer layer of P son, the M, N or P son having generally the same diameter for reasons of simplification and cost.
• the two-layer cables most used today in tire belts are essentially M + N construction cables consisting of an inner core or layer of M yarns (in particular of 3 or 4 wires) and an outer layer of N wires (e.g., from 6 to 12 wires).
• the outer layer is relatively desaturated due to the high diameter of the inner layer provided by the presence of M core son, especially when the diameter of the core son is chosen to be greater than that of the son of the outer layer.
• This type of construction promotes, as is known, the external penetrability of the cable by the tire calendering rubber or other rubber article during the cooking of the latter, and consequently, it is possible to improve the endurance of the cables in fatigue and fatigue-corrosion, particularly with regard to the cleavage problem mentioned above.
• the construction cables 3 + N or 4 + N have the disadvantage that they are not penetrable to the core because of the presence of a channel or capillary in the center of the three or four core wires, which remains vacuum after impregnation with rubber and therefore conducive, by a kind of "wicking" effect, to the propagation of corrosive media such as water.
• This disadvantage is well known, it has been disclosed for example in patent applications WO 01/00922, WO 01/49926, WO 2005/071157, WO 2006/013077.
• the inner layer Ci by removing its son, through a unit core wire (or "core wire") and remove a wire from the outer layer; thus, the cable obtained, for example of construction 1 + 3 + (N-I), becomes penetrable from the outside to its center.
• the core wire should be neither too thin, otherwise it does not produce the desaturation effect that is targeted, nor too big otherwise the wire does not stay in the center of the cable.
• a 0.12 mm diameter core wire is used for 0.35 mm diameter C 1 and C 1 wire wires (see, for example, RD ⁇ Research Disclosure) August 1990, No. 316107, "Steel cord construction”. ).
• patent application US 2002/160213 for its part proposed the production of M + N type cables gummed in situ, M ranging from 2 to 4.
• the method proposed here consists of to be sheathed individually (that is to say, singly, "wire to wire") with rubber in the green state, upstream of the assembly point of the M son (or torsion point), one or preferably each M son to obtain an inner layer sheathed rubber, before the subsequent introduction of N son of the outer layer by wiring around the inner layer and sheathed.
• calendering consists in transforming the cable, by incorporation between two layers of rubber in the green state, into a metal rubberized fabric used as a semi-finished product for any subsequent manufacture, for example for the manufacture of a tire.
• the winding and the intermediate storage of the inner layer require, during the coil winding of the inner layer, the use of spacers and steps important slicing to prevent parasitic bonding between the wound layers and, for the same layer, between the turns.
• a first object of the invention is a method for manufacturing a two-layer (Ci, Ce) metal cable, of M + N construction, comprising an inner layer (Ci) consisting of M son of diameter d, coiled together in a helix according to a pitch pi, M ranging from 2 to 4, and an outer layer (Ce) of N son of diameter d 2 wound together in a helix in a pitch p 2 around the inner layer (Ci), said method comprising at least the following steps operated online: - A step of assembly by twisting the M core son, for forming the inner layer (Ci) at an assembly point; downstream from said assembly point of the M core wires, a step of sheathing the inner layer (Ci) with a diene rubber composition, called "filling rubber", in the green state; a step of assembly by twisting the N son of the outer layer (Ce) around the inner layer (Ci) and sheathed; a final balancing step of the twists.
• the invention also relates to an assembly device and in-line scrubbing, usable for implementing the method of the invention, said device comprising upstream downstream, according to the direction of advancement of the cable being formed:
• feeding means for the M core wires feeding means for the M core wires; first assembly means by twisting the M core son for forming the inner layer; means for sheathing the inner layer;
• FIG. 1 An example of an in situ twisting and scrubbing device that can be used for implementing the method according to the invention (FIG.
• FIG. in cross-section a construction cable 3 + 9 of the compact type that can be manufactured by the method of the invention (FIG. in cross-section, a conventional 3 + 9 construction cable, also of the compact type (Fig. 3); in cross-section, a 3 + 9 construction cable of the cylindrical layer type which can be manufactured by the method of the invention (FIG 4); - in cross-section, a conventional 3 + 9 construction cable, also of the cylindrical layer type (Fig. 5);
• any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e., terminals a and b excluded) while any range of values designated by the expression “from a to b” means the range from a to b (i.e., including the strict limits a and b).
• the method of the invention is intended for the manufacture of a two-layer metal cable (Ci, Ce) of M + N construction, of the "gummed in situ" type, comprising an inner layer (Ci) consisting of M son of diameter di wound helically together in a pitch p b M ranging from 2 to 4, and an outer layer (Ce) of N d 2 diameter son wound helically in a pitch p 2 around the inner layer (Ci), said method comprising at least the following steps operated online:
• a step of assembly by twisting the M core son for forming the inner layer (Ci) at an assembly point; then, downstream from said assembly point of the M core wires, a step of sheathing the inner layer (Ci) with a diene rubber composition called "filling rubber" in the green state (that is, say non-crosslinked); followed by a step of assembly by twisting the N son of the outer layer (Ce) around the inner layer (Ci) and sheathed; then a final balancing step of the twists.
• the wires are not twisted around their own axis, due to a synchronous rotation before and after the assembly point; or by twisting: in such a case, the yarns undergo both a collective twist and an individual twist around their own axis, which generates a detorsion torque on each of the threads.
• a first essential characteristic of the above method is to use, both for the assembly of the inner layer and for that of the outer layer, a twisting step.
• the M core wires are twisted together (direction S or Z) to form the inner layer Ci, in a manner known per se; the son are delivered by feeding means such as coils, a distribution grid, coupled or not to a joining grain, intended to converge the core son in a common point of torsion (or assembly point).
• the M son of the inner layer have for example a diameter d between 0.20 and 0.50 mm, in particular in a range of 0.23 to 0.40 mm; their not twisting Pi is for example between 5 and 30 mm.
• the pitch "p" represents the length, measured parallel to the axis of the cable, at the end of which a wire having this pitch performs a complete revolution about said axis of the cable.
• the inner layer (Ci) thus formed is then sheathed with filling gum in the green state, provided by an extrusion screw at an appropriate temperature.
• the filling rubber can thus be delivered at a fixed point, unique and compact, by means of a single extrusion head, without using an individual sheathing son upstream of the assembly operations, before forming the inner layer, as described in the prior art.
• This method has the significant advantage of not slowing down the conventional assembly process. It enables the complete operation of initial twisting, scrubbing and final twisting in one line, irrespective of the type of cable produced (compact layer cable as a cylindrical layer cable), all at high speed.
• the method of the invention can be implemented at a speed (running speed of the cable on the twisting-scrub line) greater than 70 m / min, preferably greater than 100 m / min.
• the tension stress exerted on the M threads is preferably between 10 and 25% of the breaking force of the son.
• the extrusion head may comprise one or more dies, for example an upstream guide die and a downstream die calibration. It is possible to add continuous measurement and control means of the diameter of the cable connected to the extruder.
• the extrusion temperature of the filling rubber is between 60 ° C. and 120 ° C., more preferably between 70 ° C. and 110 ° C.
• the extrusion head thus defines a cladding zone having the shape of a cylinder of revolution whose diameter is of course adjusted to the specific construction of the cable manufactured.
• the extrusion diameter is preferably between 0.4 and 1.2 mm, more preferably between 0.5 and 1.0 mm.
• the extrusion length is preferably between 4 and 10 mm.
• the inner layer Ci at any point of its periphery, is covered with a minimum thickness of filling rubber which is preferably greater than 5 ⁇ m, more preferably greater than 10 ⁇ m. for example between 10 and 50 microns.
• the amount of filling gum delivered by the extrusion head is adjusted to a preferred range of 5 to 40 mg per gram of final cable (i.e., gummed in situ).
• the amount of filling gum delivered be between 5 and 30 mg, more preferably still within a range of 10 to 25 mg per g of cable.
• the diene elastomer of the filling rubber is preferably chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), different copolymers of butadiene, the various copolymers of isoprene, and mixtures of these elastomers.
• a preferred embodiment consists in using an "isoprene" elastomer, that is to say a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR). , the synthetic polyisoprenes (IR), the various isoprene copolymers and the mixtures of these elastomers.
• the filling rubber is of the vulcanizable type, that is to say that it generally comprises a vulcanization system adapted to allow the crosslinking of the composition during its cooking, typically based on sulfur and one or more accelerators.
• the filling rubber may also comprise all or part of the usual additives intended for tire rubber matrices, such as, for example, reinforcing fillers such as carbon black or silica, antioxidants, oils, plasticizers, anti-eversion agents, resins, adhesion promoters, and cobalt salts.
• the filling rubber has, in the crosslinked state, a secant modulus ElO extension (at 10% elongation) which is between 5 and 25 MPa, more preferably between 5 and 20 MPa.
• the final assembly is carried out, always by twisting (S or Z direction), of the N wires of the outer layer (Ce) around the inner layer (Ci) and sheathed.
• the N threads come lean on the filling rubber, embed itself in it.
• the filling rubber moving under the pressure exerted by these external son, naturally has a tendency to fill, at least in part, each of the interstices or cavities left empty by the son, between the inner layer and the outer layer.
• the number N of wires of the outer layer N is, of course, a function not only of the respective diameters di and d 2 , but also of the number M of wires of the inner layer.
• M preferably equal to 3 or 4
• M preferably from 6 to 12.
• These N son have for example a diameter d 2 of between 0.20 and 0.50 mm, in particular in a range of 0.23. at 0.40 mm, d 2 can of course be identical to or different from the diameter di M soul son.
• the inner layer comprises 3 or 4 wires, more preferably 3 wires, and the outer layer preferably comprises 8, 9 or 10 wires.
• the inner layer has 3 wires and the outer layer has 9 wires.
• the twisting pitch p 2 is preferably between 10 and 30 mm, more preferably in a range of 12 to 25 mm. Preferably, there is the relation 0.5 ⁇ pi / p 2 ⁇ 1 which is verified.
• the method of the invention is implemented with pi and p 2 which are equal.
• the outer layer Ce has the preferred characteristic of being a saturated layer, that is to say that, by definition, there is not enough room in this layer to add at least one (N max + l) th wire diameter d 2 , N max representing the maximum number of windable son in a layer around the inner layer Ci.
• This construction has the advantage of limiting the risk of overflow of filling rubber at its periphery and of offer, for a given diameter of the cable, a higher resistance.
• the number N of wires can vary to a very large extent according to the particular embodiment of the invention, for example from 6 to 12 wires for an internal layer Ci of 3 wires, it being understood that the maximum number N max of wires N will be increased if their diameter d 2 is reduced compared to the diameter d of the M core wires, in order to preferentially preserve the saturated outer layer.
• the M + N cable can be of two types, namely of the compact type or the type with cylindrical layers.
• the son of the outer layer (Ce) are helically wound at the same pitch and in the same direction of torsion (that is to say in the direction S (provision "S / S"), or in the direction Z ("Z / Z" arrangement)) and the wires of the inner layer (Ci), for obtaining a layer cable of the compact type as schematized for example in Figure 2.
• the compactness is such that virtually no distinct layer of wires is visible;
• the cross-section of such cables has an outline which is polygonal and non-cylindrical, as illustrated for example in Fig. 2 (compact cable 3 + 9 gummed in situ) and Fig. 3 (compact cable 3 + 9 conventional, c that is, not gummed in situ).
• the cable M + N is not yet complete.
• the central channel delimited by the M core wires when M is equal to 3 or 4, is not yet filled with filling rubber, in any case insufficiently to obtain a watertightness property. the air is acceptable.
• M is equal to 2
• the filling rubber surrounds the inner layer without sufficiently penetrating between the two wires which remain in contact with each other, which can be detrimental in particular with respect to the risks of wear. possible by fretting.
• torsion balancing is meant here in known manner the cancellation of the residual torsional torques (or of the detorsion springback) exerted on each wire of the cable, in the inner layer as in the outer layer.
• Torsion balancing tools are well known to those skilled in the art of twisting; they may consist for example of "trainers” or “twisters” or “twister-trainers”, consisting of either pulleys for twisters or small diameter rollers for trainers, pulleys and / or rollers through which circulates the cable.
• the method of the invention exploits the rotation of the M core wires, at the final stage of manufacture of the cable, to naturally distribute, homogeneously, the filling rubber inside and around the inner layer (Ci), while perfectly controlling the amount of filling compound provided.
• This cable can be wound on a receiving reel, for storage, before being processed, for example, through a calendering installation, for preparing a metal / rubber composite fabric.
• the cable M + N can be qualified as airtight or impermeable to air: in the air permeability test described in paragraph II-1-B which follows, it is characterized by a flow rate average air less than 2 cm 3 / min, preferably less than or equal to 0.2 cm 3 / min.
• the method of the invention makes possible the manufacture of M + N cables which may be advantageously free (or virtually free) of filling gum at their periphery.
• an expression it is meant that no particle of filling compound is visible, with the naked eye, at the periphery of the cable, that is to say that the person skilled in the art does not make any difference at the output of manufacture, with the naked eye and at a distance of two or three meters, between a coil of M + N cable gummed in situ prepared according to the invention and a conventional M + N cable coil (that is, ie not erased in situ).
• An assembly device and scrub according to the invention usable for the implementation of the method of the invention described above, comprises upstream downstream, according to the direction of advancement of a cable being formed:
• supply means (110) deliver M (for example three) core wires (11) through a grid ( 12) of distribution (axisymmetrical distributor), coupled or not to an assembly line (13), beyond which the M core wires converge at a point of assembly or point of twisting (14), for formation of the inner layer (Ci).
• the inner layer Ci once formed, then passes through a cladding zone consisting for example of a single extrusion head (15) through which is intended to circulate the inner layer.
• the distance between the point of convergence (14) and the sheathing point (15) is for example between 50 cm and 1 m.
• the final cable M + N thus formed is finally collected on a rotary reception (19), after passing through the torsion balancing means (18) consisting for example of a twister-trainer.
• FIG. 2 schematizes, in section perpendicular to the axis of the cable (assumed rectilinear and at rest), an example of a preferred cable 3 + 9 gummed in situ, obtainable by means of the method according to the invention. previously described invention.
• This type of construction has the consequence that the internal (20) and external (21) wires form two concentric layers which each have a substantially polygonal contour (represented in dotted lines) (triangular for the Ci, hexagonal layer for the Ce layer), and not cylindrical as in the case of cables with cylindrical layers which will be described later.
• the filling rubber (22) fills the central capillary (23) (symbolized by a triangle) formed by the three core wires (20) by spreading them very slightly, while completely covering the inner layer Ci formed by these three wires. (20). It also fills each interstice or cavity (also symbolized by a triangle) formed either by a core wire (20) and the two external wires (21) which are immediately adjacent to it, or by two core wires (20) and the outer wire (21) adjacent thereto; in total, 12 interstices (helical capillaries, also symbolized by a triangle) are thus present in this cable 3 + 9, to which is added the central channel or capillary (23).
• the filling rubber extends in a continuous manner around the layer Ci it covers.
• Figure 3 recalls the section of a cable 3 + 9 (noted C-2) conventional (i.e., not gummed in situ), also of the compact type.
• C-2 conventional (i.e., not gummed in situ), also of the compact type.
• the absence of filling gum means that virtually all the threads (30, 31) are in contact with each other, which leads to a particularly compact structure, very difficult to penetrate (not to say impenetrable) of the outside by rubber.
• the characteristic of this type of cable is that the three core wires (30) form a channel or central capillary (33) which is empty and closed and thus conducive, by "wicking" effect, to the propagation of corrosive media such as that water.
• FIG. 4 schematizes another example of a preferential cable 3 + 9 according to the invention.
• this type of construction has the consequence that the wires are arranged in two adjacent and concentric layers (Ci and Ce), tubular, giving the cable (and the two layers) an outline (shown in dotted lines) cylindrical and not polygonal.
• the filling rubber (42) fills the central capillary (43) (symbolized by a triangle) formed by the three core wires (40) slightly apart, while completely covering the inner layer Ci formed by the three wires ( 40). It also fulfills, at least in part (here, in this example, totally) each interstice formed either by a core wire (40) and the two external wires (41) which are immediately adjacent to it (the nearest), or by two core wires (40) and the adjacent outer wire (41); in total, 12 interstices or capillaries are thus present in this cable 3 + 9, to which is added the central capillary (43).
• Figure 5 recalls the section of a cable 3 + 9 (noted C-4) conventional (i.e., not gummed in situ), also of the type with two cylindrical layers.
• C-4 conventional (i.e., not gummed in situ), also of the type with two cylindrical layers.
• the absence of filling rubber causes the three wires (50) of the inner layer (Ci) to come into close contact with each other, which leads to an impenetrable, closed and impenetrable central capillary (53). on the outside by rubber and propitious on the other hand to the propagation of corrosive media.
• the method of the invention also applies advantageously to 2 + N construction cables. Thanks to an optimized penetration of the cable, from the inside, by the filling rubber, it is no longer necessary to desaturate the outer layer to improve its penetrability from the outside, in particular by rubber. At identical wire diameters between the layers Ci and Ce, this advantageously makes it possible, for example, to replace 2 + 7 construction cables with 2 + 8 construction cables, which are more resistant for the same size.
• the process of the invention is used for the manufacture of construction cables 2 + 6, 2 + 7, 2 + 8, 3 + 7, 3 + 8, 3 + 9, 4 + 8, 4 + 9, 4 + 10, in particular, of the latter, those consisting of yarns having substantially the same diameter from one layer to another
• the method of the invention is of course not limited to the manufacture of preferential cables whose son have diameters between 0.20 and 0.50 mm, as indicated above.
• the process of the invention can be used for the manufacture of cables whose M and N wires have diameters di and d 2 smaller, for example in a range from 0.08 to 0, 20 mm, such cables being used, for example, for reinforcing parts of tires other than their crown reinforcement, in particular for reinforcing the carcass reinforcement of tires for industrial vehicles such as heavy goods vehicles.
• Fm maximum load in N
• Rm tensile strength in MPa
• At total elongation in %
• the modulus measurements are carried out in tension, unless otherwise indicated according to ASTM D 412 of 1998 (test piece “C"): it is measured in second elongation (ie after one cycle). accommodation) the secant modulus "true” (i.e., reduced to the actual section of the specimen) at 10% elongation, denoted ElO and expressed in MPa (normal conditions of temperature and hygrometry according to ASTM D 1349 of 1999).
• This test makes it possible to determine the longitudinal permeability to the air of the cables tested, by measuring the volume of air passing through a specimen under constant pressure for a given time.
• the principle of such a test is to demonstrate the effectiveness of the treatment of a cable to make it impermeable to air; it has been described for example in ASTM D2692-98.
• the test is here carried out either on cables extracted from tires or rubber sheets that they reinforce, so already coated with rubber in the cooked state, or on raw manufacturing cables.
• the raw cables must be previously embedded, coated from the outside by a so-called coating gum.
• a series of 10 cables arranged in parallel is placed between two skims (two rectangles of 80 x 200 mm) of a rubber composition in the raw state, each skim having a thickness 3.5 mm; the whole thing is then locked in a mold, each of the cables being kept under tension sufficient (for example 2 daN) to ensure its straightness when placed in the mold, using clamping modules; then the vulcanization (baking) is carried out for 40 min at a temperature of 140 ° C. and under a pressure of 15 bar (rectangular piston of 80 ⁇ 200 mm). After which, the assembly is demolded and cut 10 pieces of cables thus coated, in the form of parallelepipeds of dimensions 7x7x20 mm, for characterization.
• the test is carried out on 2 cm of cable length, thus coated by its surrounding rubber composition (or coating gum), as follows: air is sent to the cable inlet, under a pressure of 1 bar, and the volume of air at the outlet is measured using a flow meter (calibrated for example from 0 to 500 cm 3 / min). During the measurement, the cable sample is locked in a compressed seal (eg a dense foam or rubber seal) in such a way that only the amount of air passing through the cable from one end to the other, along its longitudinal axis, is taken into account by the measure; a preliminary seal check of the seal is made using a solid rubber specimen, ie, without a cable.
• a compressed seal eg a dense foam or rubber seal
• the measured flow rate is lower as long as the longitudinal imperviousness of the cable is high.
• measured values equal to or less than 0.2 cm 3 / min are considered to be zero; they correspond to a cable that can be described as airtight along its axis (ie, in its longitudinal direction).
• the amount of filling compound is measured by difference between the weight of the initial cable (thus erased in situ) and the weight of the cable (and therefore that of its threads) whose filling rubber has been eliminated by a suitable electrolytic treatment.
• a sample of cable (length 1 m), wound on itself to reduce its bulk, constitutes the cathode of an electrolyzer (connected to the negative terminal of a generator), while the anode (connected to the positive terminal ) consists of a platinum wire.
• the electrolyte consists of an aqueous solution (demineralized water) comprising 1 mole per liter of sodium carbonate.
• L 1 specimen, completely immersed in the electrolyte, is turned on for 15 min at a current of 300 mA.
• the cable is then removed from the bath, rinsed thoroughly with water. This treatment allows the rubber to be easily detached from the cable (if this is not the case, we continue the electrolysis for a few minutes).
• the eraser is carefully removed, for example by simply wiping with an absorbent cloth, while detaching one by one the son of the cable.
• the threads are again rinsed with water and then immersed in a beaker containing a mixture of deionized water (50%) and ethanol (50%); the beaker is immersed in an ultrasonic tank for 10 minutes.
• the threads thus devoid of any trace of gum are removed from the beaker, dried under a stream of nitrogen or air, and finally weighed.
• the rate of filling rubber in the cable is calculated, expressed in mg of filling rubber per gram of initial cable, and averaged over 10 measurements (10 meters of cable in total).
• CI cables as schematized in Figure 2 were manufactured according to the method according to the invention, using a device as described above and shown schematically in Figure 1.
• the filling rubber was a rubber composition conventional tire crown reinforcement, having the same formulation as that of the belt rubber web that the CI cable is intended to reinforce in the tire test that follows. This composition was extruded at a temperature of 90 ° C. through a calibration die of 0.700 mm.
• the rate of filling rubber measured according to the method previously indicated in paragraph II-1C, is 16 mg per g of cable.
• This filling gum fills the channel or central capillary formed by the three core wires slightly apart, while completely covering the inner layer Ci formed by the three son. It also fills, at least partially if not totally, each of the twelve interstices or empty channels formed either between a core wire and the two external wires which are immediately adjacent to it, or between two core wires and the external wire which is adjacent.
• C-5 cables as shown schematically in Figure 6 were manufactured according to a conventional method. They are free of filling gum.
• Each C-5 cable comprises a core wire (65) of very small diameter (0.12 mm); the three inner wires (60) and the eight outer wires (61) each have a diameter of 0.35 mm.
• the 3 wires of the inner layer are wound together in a helix (direction S) with a pitch pi equal to 7.7 mm, this layer Ci being in contact with a cylindrical outer layer of 8 wires themselves wound together in a helix ( direction S) around the core in a pitch p 2 equal to 15.4 mm.
• the core wire (65) by removing the wires (60) of the inner layer Ci and filling in some way the central channel formed by these three core wires (60), makes it possible to desaturate (by increasing the diameter of the inner layer Ci) the outer layer Ce (with identical thread diameters from one layer to another) and thereby increase the external penetrability of the cable (C-5) by rubber. Thanks to this construction, the C-5 cable becomes penetrable from the outside to its center.
• All the wires used for the manufacture of these cables are fine carbon steel wires, manufactured according to known methods, the properties of which are given in Table 2 below.
• the C-I and C-5 layered cords are then calendered to rubber skims made of a conventional rubber composition for use in the manufacture of radial heavyweight tire belt plies.
• This composition is based on natural rubber (peptized) and N33O carbon black (55 phr), it also comprises the following usual additives: sulfur (6 phr), sulfenamide accelerator (1 phr), ZnO (9 phr), stearic acid (0.7 phr), antioxidant (1.5 phr), cobalt naphthenate (1 phr); the ElO module of the filling rubber is approximately 6 MPa.
• This radial tire 1 comprises an apex 2 reinforced by a crown reinforcement or belt 6, two sidewalls 3 and two beads 4, each of these beads 4 being reinforced with a rod 5.
• the crown 2 is surmounted by a tread represented in this schematic figure.
• a carcass reinforcement 7 is wound around the two rods 5 in each bead 4, the upturn 8 of this armature 7 being for example disposed towards the outside of the tire 1 which is shown here mounted on its rim 9.
• the carcass reinforcement 7 is in known manner constituted by at least one sheet reinforced by so-called "radial” cables, that is to say that these cables are arranged substantially parallel to each other and extend from a bead to the other so as to form an angle of between 80 ° and 90 ° with the median circumferential plane (plane perpendicular to the axis of rotation of the tire which is located halfway between the two beads 4 and passes through the middle of the crown frame 6).
• this tire 1 also comprises, in a known manner, an inner rubber or elastomer layer (commonly called “inner rubber”) which defines the radially inner face of the tire and which is intended to protect the carcass ply from the diffusion of the tire. air from the interior space to the tire.
• the crown reinforcement or belt 6 is in known manner constituted by two triangulation half-plies reinforced by metal cables inclined by 65 degrees, surmounted by two sheets called “working plies" superimposed crossed. These working plies are reinforced by metal cables arranged substantially parallel to each other and inclined by 26 degrees (radially internal ply) and 18 degrees (radially external ply). The two working plies are furthermore covered by a protective ply reinforced with conventional metal cables (high elongation) inclined at 18 degrees. All angles of inclination indicated are measured relative to the median circumferential plane of the tire.
• the tires PI and P-5 are identical with the exception of the cables that strengthen their belt 6.
• the tires PI are reinforced by CI cables manufactured according to the method of the invention, the tires P-5 are reinforced by the cables C -5 which, because of their recognized performance, are particularly comparable to conventional 3 + 9 cables (wireless core unit), a witness of choice for this test.
• the test is conducted until the forced destruction of the tires.
• the tires PI reinforced by the cables resulting from the process of the invention have a significantly improved endurance: the average distance traveled is increased by 20% compared with the tires. witnesses already showing an excellent performance.
• the CI cables, manufactured with the method of the invention, were further subjected to the air permeability test (paragraph II-1B), by measuring the volume of air passing through the cables in 1 min (average of 10 measurements for each cable tested).
• In situ control gummed cables of the same 3 + 9 construction as the CI cables, were also manufactured by individually sheathing either a single wire or each of the three wires of the inner layer Ci. This sheathing was made using extrusion dies of variable diameter (320 to 420 microns) arranged this time upstream of the assembly point (sheathing and in-line twisting) as described in the prior art (US 2002/160213 application cited above); for a rigorous comparison, the amount of filling gum delivered was adjusted in such a way that the rate of filling rubber in the final control cables (ie between 6 and 25 mg per g of cable, as measured according to the method of II-1C), which is close to that of the cables of the invention.
• none of the above test leads can be qualified as an airtight cable along its longitudinal axis.
• the method of the invention allows the manufacture of M + N construction cables gummed in situ which, thanks to an optimal penetration rate by rubber, on the one hand can be implemented effectively under conditions industrial, especially without the difficulties associated with excessive overflowing of rubber during their manufacture, on the other hand have a tire belt endurance which is significantly improved compared to the best control cables known to date for such an application.

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