Flexible Heat Sink Tiles for Uniform Induction Welding
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Solution Overview
Problem
Induction welding of thermoplastic composites (TPC) parts results in uneven heating, with higher heat generation in areas closer to the induction coil than at the weld joint, necessitating a method to concentrate heating at the weld joint.
Innovation Solution
The use of a flexible heat sink composed of electrically non-conductive and thermally conductive tiles, spaced with gaps and joined by a flexible adhesive or mechanical hinges, to absorb and dissipate heat from the TPC parts, allowing the induction coil to focus heating at the weld interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an induction coil is used to heat TPC parts for welding, then the weld joint can be heated to melting temperature, but excessive heat is generated in areas closer to the induction coil rather than being concentrated at the weld joint
Solution Approach 1:
The patent applies local quality by using a heat sink with spatially varying thermal conductivity or heat capacity. The heat sink is designed with higher heat absorption capacity in regions closer to the induction coil and lower capacity near the weld joint, creating a gradient structure that locally adapts to the heating profile. This allows the system to absorb excess heat in high-temperature zones while maintaining adequate heat at the weld interface for proper fusion.
Solution Approach 2:
The heat sink acts as an intermediary component between the induction coil and the TPC parts. It mediates the heat transfer by absorbing excess thermal energy from the induction coil and redistributing it, thereby protecting the TPC parts from localized overheating while ensuring sufficient heat reaches the weld joint. The heat sink essentially serves as a thermal buffer that smooths out the uneven heat distribution.
2Temperature
If a rigid heat sink is used to absorb excess heat, then heat distribution can be controlled, but the heat sink cannot conform to curved or complex surfaces
Solution Approach 1:
The heat sink is segmented into multiple modular units or tiles that can be individually positioned and oriented. Each segment can independently conform to different portions of the workpiece surface, allowing the overall heat sink assembly to adapt to complex geometries. The segmented structure maintains thermal effectiveness while providing flexibility in configuration.
Solution Approach 2:
The patent employs flexible heat sink materials or thin-film heat dissipation layers that can elastically deform to conform to curved surfaces. These flexible structures maintain their heat absorption functionality while adapting to the workpiece geometry. The flexible nature allows the heat sink to be applied to non-planar surfaces without compromising thermal performance or requiring complex rigid structures.
3Temperature
If thermaly conductive material is used for the heat sink, then excess heat can be absorbed, but the material must be electrically non-conductive to avoid interference with the induction coil
Solution Approach 1:
The heat sink utilizes composite materials that combine thermal conductivity with electrical insulation properties. Examples include ceramic composites (such as aluminum oxide or nitrogen boron composites), polymer-ceramic composites, or metal-matrix composites with insulating coatings. These composite structures provide the necessary thermal management functionality while maintaining electrical isolation from the induction coil, preventing electromagnetic interference and ensuring reliable operation.
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 flexible heat sink concentrates heat at the weld joint, creating a uniform fusion bond while minimizing heat in other areas, enhancing the crystallization of semi-crystalline thermoplastics and improving the strength and integrity of the weld.
Implementation Method 1
The induction coil induces eddy currents in the inherently conductive carbon fibers disposed within the TPC parts, which generate heat and melt the thermoplastic
Implementation Method 2
Induction welding involves moving an induction coil along a weld line of the TPC parts. The induction coil induces eddy currents
Implementation Method 3
a flexible heat sink composed of electrically non-conductive and thermally conductive tiles, spaced with gaps and joined by a flexible adhesive or mechanical hinges, to absorb and dissipate heat from the TPC parts
Data Source
AI summary
A heat sink for use in induction welding includes a number of tiles, wherein the tiles are electrically non-conductive and have a thermal diffusivity of greater than about 25 mm2/sec. A joint flexibly joins the tiles together.