Thermoplastic Stiffener Welding Device with Localized Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Welding a thermoplastic stiffener to a skin requires heating the interface to the melting point of the polymer matrix, which reduces mechanical strength and can cause the stiffener to collapse, necessitating complex and expensive tooling to manage thermal expansion and pressure.
Innovation Solution
A device with a metallic support, thermal insulation, and localized heating means, including a heating plate and conformal panel, allows for concentrated heating and pressure application only at the weld zone, reducing thermal impact on the surrounding areas and eliminating the need for extensive tooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interface between skin and stiffener is heated to the melting point of the polymer matrix, then welding is achieved, but the mechanical strength of the matrix is completely reduced and the stiffener is liable to collapse under its own weight
Solution Approach 1:
The patent applies localized heating only to the bearing surface of the stiffener foot and the receiving side of the skin at the weld interface, while the rest of the parts remain at ambient temperature. This is achieved through a heating plate that contacts only the bearing surface and thermal insulation means that confine heat to the local zone, thereby achieving welding without collapsing the stiffener structure.
Solution Approach 2:
The heating process is segmented into two distinct zones: a heated weld zone at the interface where temperature reaches the polymer melting point, and a cold support zone where the stiffener flange and surrounding areas remain at ambient temperature. This segmentation allows the weld interface to achieve bonding while the structural portions maintain their mechanical strength.
2Reliability
If the stiffener is heated to the melting point of the polymer, then welding is achieved, but the volume of the part must be strictly limited by tooling to prevent defects due to thermal expansion
Solution Approach 1:
The patent confines thermal expansion to a very small local zone at the weld interface by applying heat only to the bearing surface and receiving side. The thermal insulation means prevent heat propagation to the flange and surrounding areas, thereby eliminating the need for complex tooling to constrain overall part volume during heating.
Solution Approach 2:
The patent extracts the heating function from a global process and concentrates it only at the weld interface. Instead of heating the entire stiffener and skin assembly, only the specific zones requiring bonding are heated, removing the need for volumetric constraint tooling.
3Reliability
If complex tooling is used to manage thermal expansion and pressure during welding, then welding quality is maintained, but the cost of production and implementation increases
Solution Approach 1:
The patent replaces complex global constraint tooling with simple localized heating and insulation components. The heating plate and thermal insulation means are straightforward elements that confine heat to the weld zone, achieving reliable welding without expensive tooling for volumetric constraint.
Solution Approach 2:
The thermal insulation means and heating plate are designed to self-constrain the heat to the necessary zone through their physical arrangement, eliminating the need for additional complex constraint mechanisms. The system uses its own structure to achieve both heating and thermal management functions.
Data Source
AI summary
The invention relates to a device for welding a stiffener to a skin. The stiffener has a stiffener foot with a bearing surface parallel to the skin surface and a stiffener flange projecting away from the plane of the bearing surface. The device includes a metallic support includes a seating surface matching the shape of the receiving side; a groove which accommodates a flange of the stiffener inserted in the groove; an insulative supporting structure for positioning a bearing surface against the receiving side; and a conformal panel for applying pressure forcing said bearing surface against said receiving side. A heater temporarily raises the temperature of bearing surface of the stiffener and the adjacent receiving side of the skin to above the melting point of the matrix when pressure is applied thereby welding the stiffener to the skin.