Induction Welding Fixture With Separate Rams for Composite Flanges
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Solution Overview
Problem
Induction welding of thermoplastic composite workpieces with non-continuous sections, such as stiffeners with spaced flanges, requires precise temperature control to prevent surface burning while achieving a strong bond, as existing methods struggle to maintain uniform heating and prevent overheating.
Innovation Solution
A welding assembly and method using an induction welding fixture with adjustable components, including a bottom and top support structure, heat management devices, and actuators to secure and clamp workpieces, allowing for controlled heating and uniform fusion of thermoplastic composite workpieces with non-continuous sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If induction welding is used to bond thermoplastic composite workpieces, then strong bonds are achieved, but the top surface of the workpiece burns due to excessive temperature
Solution Approach 1:
The welding system is divided into multiple independently controllable induction coils, each responsible for heating specific zones (bond line vs. top surface). This segmentation allows differential temperature control where the bond line reaches melting temperature for strong bonding while the top surface is maintained below burning temperature through separate coil control or selective shielding.
Solution Approach 2:
Different thermal conditions are applied to different locations of the workpiece. The bond line area receives intense localized heating to achieve melting and strong bonding, while the top surface areas are either shielded, pre-cooled, or heated less intensely to prevent burning. This local quality approach ensures each region receives the appropriate thermal treatment for its function.
2Temperature
If uniform heating is applied across the workpiece, then the top surface burns, but the bond line does not reach melting temperature for proper bonding
Solution Approach 1:
The heating system is segmented into multiple independently controlled induction coils positioned to target different zones. One coil or set of coils is dedicated to heating the bond line to melting temperature, while another coil or shielding mechanism controls the top surface temperature to prevent burning. This segmentation eliminates the need for uniform heating across the entire workpiece.
Solution Approach 2:
The induction coils are operated in periodic or sequential cycles rather than continuously simultaneously. The bonding coil operates in pulses to heat the bond line to melting temperature, followed by cooling periods or reduced power to prevent top surface burning. This periodic action allows temperature differentiation between zones through time-based control.
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 solution enables efficient and uniform induction welding of thermoplastic composite workpieces with non-continuous sections, ensuring strong bonds and preventing surface damage by maintaining precise temperature control and compressive force during the welding process.
Implementation Method 1
performing a welding pass of an induction coil over the composite part that initiates while the composite part remains above ambient temperature, and that is performed by generating a welding magnetic field that heats the composite part
Implementation Method 2
The method includes preheating a composite part comprising a matrix of thermoplastic reinforced by fibers, from an ambient temperature to a preheat temperature that is below a melting temperature of the thermoplastic, performing a welding pass of an induction coil over the composite part
Data Source
Figure 1
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AI summary
A welding assembly (530) is disclosed. The welding assembly (530) includes a plurality of separately controllable actuators (570) (e.g., pneumatic, having an axially movable ram) to press a corresponding portion of a first workpiece (e.g., a discrete flange (512) of a first stiffener (510)) against a second workpiece (e.g., an outer skin (502)) for welding operations (e.g., via induction welding).