RF Dielectric Heating for Uniform Tire Vulcanization
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Solution Overview
Problem
Existing methods for manufacturing three-dimensional molded articles, such as tires, face challenges in achieving optimal heating due to varying thicknesses and materials, leading to uneven vulcanization and increased production time.
Innovation Solution
A system and method utilizing radio frequency dielectric heating with a mold and electrodes that adjust spacing and temperature to ensure even heating across different regions of the article, using a bladder as both the inner mold and electrode, and an outer mold with thermally conductive materials to maintain consistent temperature and current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal conduction heating is used to vulcanize thick sections of tire, then the thick sections are properly heated, but the thin sections overheat and burn
Solution Approach 1:
The heating system is segmented into multiple independent heating zones corresponding to different thickness regions of the tire. Each zone has its own heater and controller, allowing independent temperature control for thick sections, medium sections, and thin sections, thereby preventing overheating of thin areas while ensuring adequate heating of thick areas.
Solution Approach 2:
Different heating intensities and control strategies are applied to different spatial locations of the tire based on local thickness characteristics. Thick sections receive higher heating power with longer duration, while thin sections receive lower heating power with shorter duration, achieving uniform vulcanization across the entire tire.
2Adaptability or versatility
If RF dielectric heating with large electrode spacing is used to accommodate tire size, then the tire can be heated, but the curing time increases and productivity decreases
Solution Approach 1:
The single large electrode system is divided into multiple smaller electrode segments that can be positioned closer to the tire sections they serve. This segmentation allows reduced spacing between electrodes and tire surface, intensifying the RF heating effect and reducing curing time while maintaining adaptability to different tire sizes.
Solution Approach 2:
The heating approach transitions from a single-dimension large-spacing model to a multi-dimensional arrangement where multiple electrode pairs operate at different locations and orientations, enabling closer electrode-to-tire spacing and more efficient energy coupling.
3Device complexity
If RF dielectric heating with fixed electrode spacing is used, then the system is simple, but sections with varying dielectric constants heat at different rates causing uneven vulcanization
Solution Approach 1:
The electrode system is segmented into multiple independently controllable units, each serving a specific tire region with characteristic dielectric properties. This allows the application of tailored heating parameters to compensate for variations in dielectric constant across different tire sections, achieving uniform vulcanization.
Solution Approach 2:
The heating system transitions from uniform fixed-spacing electrodes to locally-adaptive electrodes with variable spacing and controllable power output, matching the dielectric characteristics of different tire regions to ensure consistent heating rates across all sections.
4Temperature
If long heating time is applied to vulcanize thick tire sections, then thick sections are properly cured, but thin sections overheat and burn
Solution Approach 1:
The tire heating process is divided into multiple temporal and spatial stages, with each stage targeting specific thickness regions. Thick sections are heated in extended cycles with higher power, while thin sections are heated in shorter cycles with lower power, preventing thermal damage while ensuring adequate curing.
Solution Approach 2:
The heating regime is customized for each spatial location based on local thickness, with thick regions receiving prolonged high-temperature exposure and thin regions receiving brief low-temperature exposure, eliminating the harmful overheating effect while achieving proper vulcanization.
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 approach allows for rapid and uniform vulcanization of complex three-dimensional articles, reducing production time and ensuring consistent quality by maintaining temperature and current uniformity across varying thicknesses and materials.
Implementation Method 1
A generator is provided which applies an alternating electric field between the electrodes. The alternating electric field causes movement of polar molecules in the rubber components of the tire whereby friction resulting from this molecular movement translates into heat throughout the rubber components.
Implementation Method 2
The alternating electric field causes movement of polar molecules in the rubber components of the tire whereby friction resulting from this molecular movement translates into heat throughout the rubber components.
Implementation Method 3
The mold may be made of a thermally conductive material or coated with a thermally conductive material.
Data Source
AI summary
A system and method for molding complex three-dimensional articles is disclosed. The system includes a mold for receiving an article made of at least one moldable material and, in one example, the article comprises at least one flat region and at least one radial region. The mold comprises an inner bladder that conforms to an inner surface of the article when pressurized and an outer mold that contacts an outer surface of the article. The system also includes an inner electrode spaced from an outer electrode, and a generator operable to generate an alternating electric field between the electrodes and across the article in the mold to obtain substantially even heating of the moldable material in the flat region and the radial region at the end of the heating cycle.