Co-extruding Complex Rubber Profiles with Rigid Inserts
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Solution Overview
Problem
Existing coextrusion machines are inadequate for producing inserts with high rigidity in tire manufacturing, as they require excessive extrusion pressure and fail to achieve precise sectioning and enclosure within the tread and underlayer, leading to quality issues and variable insert dimensions.
Innovation Solution
A coextrusion process that includes discontinuities in the tread and underlayer to insert a third rubber material, using a coextrusion head with specific extrusion and profiling channels to extrude and profile the materials in a discontinuous manner, ensuring precise sectioning and enclosure, and creating longitudinal grooves for inserts with greater rigidity than the tread and underlayer materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a nozzle is used to extrude high rigidity elastomeric compound through existing coextrusion machines, then the insert provides greater rigidity, but excessively high extrusion pressure compromises the quality of the co-extruded complex profile
Solution Approach 1:
The extrusion process is segmented into multiple stages: first extruding the underlayer and tread materials, then creating discontinuities, and finally extruding the high rigidity insert material into the pre-formed gaps. This segmentation allows each material to be extruded at appropriate pressures without compromising overall profile quality.
Solution Approach 2:
The underlayer and tread materials are extruded first to establish the basic profile structure and create discontinuities. This preliminary action prepares the form into which the high rigidity insert material will be placed, avoiding the need to force all materials through restrictive geometries simultaneously at high pressures.
2Ease of manufacture
If existing nozzle design is used for extruding third material, then the process is simple, but the insert cannot achieve precise cross-section and proper enclosure within tread and underlayer
Solution Approach 1:
The solution moves from attempting to extrude the insert material through a restrictive nozzle in the longitudinal direction to extruding it into pre-formed transverse discontinuities. This dimensional change in the extrusion approach allows precise cross-sectional control by defining the insert geometry in the transverse plane rather than forcing it through a longitudinal nozzle.
Solution Approach 2:
The discontinuities in the underlayer and tread act as intermediaries that receive and contain the insert material. These pre-formed gaps serve as receptacles that guide the insert material into the correct position and shape, ensuring precise cross-section and proper enclosure without requiring complex nozzle designs.
3Productivity
If continuous extrusion of underlayer and tread is used, then the manufacturing process is efficient, but inserts cannot be properly positioned in discontinuities for enhanced rigidity
Solution Approach 1:
The extrusion process uses periodic action by creating discontinuities at specific intervals along the profile length. The underlayer and tread are extruded continuously, but with periodic gaps or discontinuities introduced at predetermined locations where inserts are required, allowing the high rigidity material to be placed only where needed while maintaining overall manufacturing efficiency.
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
This method allows for the production of complex rubber profiles with inserts having precise transverse sections and greater rigidity, improving tire stiffness and grip performance while maintaining the geometry of the extruded inserts.
Implementation Method 1
a main extruder (60) having an extrusion head (50) comprising at least two flow channels (64) of a rubbery underlayer mixture (22) and a rubbery tread mixture (24), said channels opening onto an extrusion orifice through which the two rubbery underlayer and tread mixtures (22, 24) are forced
Implementation Method 2
at least one micro-extruder of a third electrically conductive rubber compound, and the extrusion head of this micro-extruder is provided at its end with a nozzle, said nozzle passing through the two flow channels so that the third electrically conductive rubber compound is inserted into the rubber compounds of the underlayer and tread upstream of the extrusion orifice
Data Source
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AI summary
The invention relates to a method for co-extruding a complex rubber profile. Said method makes it possible to co-extrude a sub-layer of a first material and a tread of a second material with at least one insert (28) of a third material inserted into a discontinuity (D20) between the sub-layer and the tread. The method includes, in series, the steps of: a) discontinuously extruding the first material; b) profiling firstly the first material; c) discontinuously extruding the second material on the first material; d) discontinuously profiling the first and second materials and extruding the third material in each discontinuity (D20); and e) profiling finally the first, second and third materials with a longitudinal groove (26) in the profile (20) next to each insert (28) of the third material.