Continuous Three-Layer Metallic Cord Rubberization
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Solution Overview
Problem
Existing methods for manufacturing three-layer metallic cords for tire reinforcement are discontinuous, leading to high rubber usage, overspill issues, and reduced production rates due to the high tack of uncured rubber, resulting in suboptimal corrosion resistance and fatigue endurance.
Innovation Solution
A method involving continuous in-situ rubberization of three-layer metallic cords, where the core is first sheathed with filling rubber, then wrapped with N wires, re-sheathed, and finally wrapped with P wires, using a twisting process to ensure uniform rubber distribution and minimize rubber quantity, utilizing two extrusion heads and twist-balancing to achieve optimal impermeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discontinuous manufacturing methods are used with multiple steps (creating intermediate cord, sheathing, cabling), then rubber penetration and corrosion resistance are improved, but productivity is reduced and manufacturing complexity increases
Solution Approach 1:
The patent combines multiple discrete manufacturing steps (core formation, intermediate layer assembly, outer layer assembly, and rubber sheathing) into a single continuous operation. The device simultaneously forms all three layers of the cord while continuously extruding rubber, eliminating the need for separate intermediate cord creation and sheathing steps, thus improving productivity without compromising rubber penetration.
Solution Approach 2:
The patent performs preliminary actions by pre-forming the metallic core and intermediate layer structure before the rubber extrusion step, allowing the rubber to be continuously applied in its uncured state throughout the entire cord formation process. This ensures complete rubber penetration into all layer interfaces while maintaining continuous manufacturing operation.
2Reliability
If high quantities of rubber are used during sheathing to ensure adequate penetration, then corrosion resistance is improved, but rubber overspill occurs and handling becomes difficult due to high tack
Solution Approach 1:
The patent changes the physical state parameter of rubber by extruding it in the uncured (liquid-like) state rather than in a cured or highly tacky state. This allows precise control of rubber quantity and distribution, ensuring complete penetration into cord capillaries without overspill, while the rubber remains manageable during the continuous formation process.
Solution Approach 2:
The patent maintains continuous extrusion of rubber in its uncured state throughout the entire cord formation process, ensuring consistent and complete rubber penetration without the need for large quantities that would cause overspill. The continuous process allows precise control of rubber application rate matching the cord formation speed.
3Ease of operation
If plastic interlayer film is used during intermediate spooling and unspooling operations, then rubber tack issues are avoided, but manufacturing complexity and production time increase
Solution Approach 1:
The patent extracts and eliminates the plastic interlayer film from the manufacturing process by performing all operations in a continuous configuration where rubber is extruded in its uncured state directly onto the forming cord. This removes the need for separate plastic film application, spooling, and removal steps, simplifying the device while maintaining ease of operation.
4Ease of manufacture
If conventional sheathing methods are used, then rubber application is simplified, but uniform distribution and compactness of the cord are reduced
Solution Approach 1:
The patent employs dynamic control of the extrusion process, adjusting rubber flow rate and extrusion pressure in real-time to match the continuous formation speed and cross-sectional area of the cord. This dynamic approach ensures uniform rubber distribution throughout the cord cross-section and along its length, achieving compactness without complicating the manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in a more compact, uniformly rubberized cord with improved longitudinal impermeability and reduced rubber overspill, enhancing the cord's endurance and manufacturing efficiency by ensuring better rubber penetration and reduced air permeability.
Implementation Method 1
a first sheathing step in which the core (C1) is sheathed with the filling rubber; a second sheathing step in which the core strand (C1+C2) is sheathed with the filling rubber
Implementation Method 2
a first assembling step by twisting the N wires of the second layer (C2) around the core (C1) thus sheathed; a second assembling step in which the P wires of the third layer (C3) are twisted around the core strand (C1+C2) thus sheathed
Data Source
AI summary
Method of manufacturing a metal cord with three concentric layers (C1, C2, C3), of the type rubberized in situ, i.e. incorporating a composition made of rubber in the uncrosslinked state referred to as “filling rubber”, the said cable comprising a first, internal, layer or core (C1), around which there are wound together in a helix, at a pitch p2, in a second, intermediate, layer (C2), N wires of diameter d2, N varying from 3 to 12, around which second layer there are wound together as a helix at a pitch p3, in a third, outer, layer (C3), P wires of diameter d3, P varying from 8 to 20, the said method comprising the following steps: a first sheathing step in which the core (C1) is sheathed with the filling rubber; a first assembling step by twisting the N wires of the second layer (C2) around the core (C1) thus sheathed in order to form, at a point named the “assembling point”, an intermediate cord named “core strand” (C1+C2); downstream of the said assembling point, a second sheathing step in which the core strand (C1+C2) is sheathed with the filling rubber; a second assembling step in which the P wires of the third layer (C3) are twisted around the core strand (C1+C2) thus sheathed; a final twist-balancing step.