Variable Spacing Induction Coil for Composite Tube Bending
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Solution Overview
Problem
Conventional methods for forming fiber-reinforced thermoplastic composite tubes with bends for aircraft components are complex and expensive, and standard thermoplastics lack the necessary strength characteristics for such applications.
Innovation Solution
An apparatus and method using induction heating with a variable turn-to-turn spacing induction coil to soften and shape thermoplastic composite tubes, allowing for controlled bending around a die and clamp, enabling the formation of bends in composite tubes with improved strength and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to form fiber-reinforced composite tubes with bends, then the tubes can be manufactured, but the process becomes complex and expensive
Solution Approach 1:
The induction coil is divided into multiple independently controllable zones along its length, allowing different heating rates and temperature profiles to be applied to different sections of the tube. This segmentation enables complex bending geometries to be achieved through a simplified, modular heating approach rather than requiring complex mechanical forming equipment
Solution Approach 2:
The patent replaces complex mechanical bending systems with an induction heating-based forming system. By using electromagnetic induction to locally heat and soften the composite tube, the material becomes pliable and can be bent into desired shapes without requiring complex mechanical presses, jigs, or multi-step forming equipment
2Strength
If standard thermoplastic materials are used for tubing, then the tubing can be manufactured, but they lack the necessary strength characteristics for aircraft applications
Solution Approach 1:
The patent employs fiber-reinforced thermoplastic composite materials that combine the structural strength of continuous fibers (such as carbon, glass, or aramid) with the formability and weldability of thermoplastic matrices. This composite structure provides the necessary tensile strength for aircraft applications while retaining the manufacturing advantages of thermoplastics
Solution Approach 2:
The invention utilizes controlled temperature parameter changes through induction heating to temporarily alter the rheological properties of the thermoplastic matrix. By heating above the glass transition or melting temperature, the matrix transitions from a rigid state to a pliable state, enabling bending operations, then cools to regain its structural strength
3Manufacturing precision
If induction heating is used to soften the tubing for bending, then controlled bending can be achieved, but the heating must be precisely controlled to maintain structural integrity
Solution Approach 1:
The induction coil is divided into multiple independently controllable zones along its length, allowing different heating rates and temperature profiles to be applied to different sections of the tube. This segmentation enables precise control over which portions of the tube are heated and to what temperature, allowing complex bending geometries to be achieved while maintaining structural integrity in unheated sections
Solution Approach 2:
The system incorporates temperature sensing and control feedback mechanisms that monitor the thermal state of the composite tube during induction heating. This feedback allows real-time adjustment of heating power to maintain the thermoplastic matrix within the optimal temperature window for bending, preventing overheating that would degrade the material or underheating that would prevent proper forming
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 the efficient and cost-effective formation of lightweight, fiber-reinforced thermoplastic composite tubes with controlled bends, addressing the strength and complexity issues of conventional methods while maintaining the structural integrity of the material.
Implementation Method 1
The induction coil is configured to cause the heating element to increase in temperature
Implementation Method 2
heating the heating element; heating a work region W of the composite tube
Implementation Method 3
heating a work region W of the composite tube... the composite tube is bent around the die forming a bend
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus for bending a composite tube (12) that includes an induction coil (40). Induction coil (40) includes multiple turns and the turn-to-turn spacing changes at least once along the length of the induction coil (40). There is a heating element (22, 26) positioned near the induction coil (40) and the induction coil (40) is configured to cause the heating element (22, 26) to increase in temperature.