Co-extruding Stiff Rubber Inserts in Tire Tread Profiles
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Solution Overview
Problem
Existing co-extrusion machines are unable to effectively extrude inserts made from elastomeric compounds that provide superior stiffness, as they require high extrusion pressures, leading to irregular cross-sections and inserts not flanked by the tread and sublayer, which are necessary for modern tire manufacturing needs.
Innovation Solution
A method for co-extruding complex rubber profiled elements with discontinuities in the tread and sublayer to insert a third material with higher stiffness, featuring a co-extrusion head with specific ducts and profiling blades that allow for precise extrusion and profiling across the co-extrusion width, creating longitudinal grooves and inserts with a triangular cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high extrusion pressure is used to extrude stiff elastomeric compound for inserts, then insert stiffness is improved, but manufacturing precision deteriorates due to irregular cross-sections and inserts not flanked by tread and sublayer
Solution Approach 1:
The method creates discontinuities in the tread and sublayer materials before the insert extrusion process. By pre-defining the spaces where inserts will be placed, the stiff elastomeric compound can be extruded at high pressure into these predetermined gaps without causing irregular cross-sections or positioning issues. The discontinuities act as prepared receptacles that guide the insert material into the correct position and shape.
Solution Approach 2:
The tread and sublayer are divided into continuous portions and discontinuous gaps through which inserts will be placed. This segmentation allows the insert material to be extruded independently into specific locations without being constrained by continuous surrounding material, enabling high pressure extrusion while maintaining precise cross-sectional geometry and ensuring inserts are properly flanked by the tread and sublayer.
2Manufacturing precision
If discontinuities are created in tread and sublayer for insert placement, then insert precision is improved, but device complexity increases due to multiple extrusion steps
Solution Approach 1:
The method combines multiple functions into a single co-extrusion process: creating discontinuities in tread and sublayer, extruding insert material into these discontinuities, and forming the final profile all occur in one integrated operation. The extrusion head is designed with multiple outlets that simultaneously produce the discontinuous tread/sublayer and fill the gaps with insert material, merging what could be separate steps into a unified process.
Solution Approach 2:
The solution moves from thinking about insert placement as a post-extrusion operation to integrating it into the extrusion process itself. By creating discontinuities in the extruded material stream and simultaneously extruding insert material into these gaps, the method adds a temporal dimension to the extrusion process, allowing multiple materials to be combined in a single continuous operation rather than requiring separate positioning steps.
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
Enables the production of complex rubber profiled elements with precise, high-stiffness inserts not flanked by the tread and sublayer, improving tire tread stiffness and grip performance while maintaining the quality of the co-extruded element.
Implementation Method 1
a main extruder having an extrusion head with at least two ducts for the flow of a sublayer rubber compound and of a tread rubber compound
Implementation Method 2
the extrusion head also includes at least one micro-extruder of a third, electrically conducting, rubber compound, and the extrusion head of this micro-extruder is equipped at its end with a nozzle
Data Source
Figure 1~5
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Figure 6~9
AI summary
The invention relates to a method for the co-extrusion of a rubber profiled element. The method consists in extruding and profiling the various rubbery materials of the co-extruded profiled element over a given co-extrusion width and in a longitudinal direction of co-extrusion perpendicular to the transverse plane (PT), the method comprising the following succession of steps consisting in: a) extruding a first material, this being performed discontinuously, b) first profiling of the first material, performed discontinuously, c) extruding a second material, this being performed discontinuously, d) profiling the first and second materials, creating at least one longitudinal groove (26) in the profiled element (20), and, jointly, at least an extruding of a third material next to each longitudinal groove (26) created in the profiled element (20), e) final profiling of the first, second and third materials to a final profile (P74) exhibiting no discontinuity across the co-extrusion width (L50).