Anisotropic Rubber Tooling for Electromagnetic Welding Pressure Control
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Solution Overview
Problem
Existing methods for electromagnetic welding of molded parts, such as inflatable elements, struggle to apply uniform pressure effectively, leading to inferior weld quality and mechanical strength, especially in high-grade applications like the aviation industry, due to isotropic pressure distribution and the need for robust molds which are often impractical.
Innovation Solution
A tooling system with a rubber body and embedded stiff body that allows for anisotropic pressure distribution by varying thickness in different directions, using a pressurizing means to apply substantial pressure only where needed, while minimizing pressure on other areas, and incorporating pressure sensors for precise measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If inflatable elements are used to apply pressure on contacted surfaces, then pressure can be applied to the welding area, but the pressure distribution is isotropic (uniform in all directions) which prevents substantial pressure on specific areas while minimizing pressure on other areas
Solution Approach 1:
The rubber body is designed with varying thickness in different directions, creating local differences in pressure transmission. Thinner regions transmit more pressure to the contacted surfaces while thicker regions transmit less pressure, enabling selective pressure application to specific welding areas without uniformly pressurizing the entire tooling.
Solution Approach 2:
The tooling employs an asymmetric rubber body geometry where the thickness varies intentionally in different directions. This asymmetric design allows the inflatable element to generate different pressure levels in different regions, with substantial pressure applied to welding areas and minimal pressure on non-welding areas, resolving the contradiction between pressure application and pressure control flexibility.
2Stress or pressure
If robust rigid molds are used to contain inflatable elements, then sufficient pressure can be maintained, but the molds are heavy, complex, and not suitable for space-restricted applications
Solution Approach 1:
The patent replaces traditional robust rigid molds with a flexible rubber body that is inflatable. This flexible shell can maintain sufficient pressure for welding without requiring heavy rigid containment structures. The rubber body itself, when inflated, provides the necessary structural support and pressure containment, dramatically reducing device complexity and weight while maintaining pressure maintenance capability.
Solution Approach 2:
The tooling utilizes changes in the physical state of the rubber body through inflation. By transitioning from a deflated to an inflated state, the rubber body gains the necessary structural rigidity and pressure maintenance capability temporarily during the welding process, then returns to a flexible state afterward. This parameter change eliminates the need for permanently complex rigid mold structures.
3Stress or pressure
If metal molds are used for electromagnetic welding, then strong containment is provided, but the metal molds heat up easily in the induction field causing overheating
Solution Approach 1:
The patent employs a rubber body that can be easily replaced or reconfigured compared to permanent metal molds. The rubber body serves as a temporary containment structure during the welding process that does not suffer from induction heating issues. After use, it can be discarded or replaced without the thermal management problems associated with metal molds, effectively avoiding the overheating issue.
Solution Approach 2:
The invention replaces the metal mold system with an inflatable rubber body system. Instead of relying on metal structures to provide containment strength, the patent uses pneumatic pressure within the rubber body to achieve the necessary containment and pressure application. This substitution eliminates the thermal conductivity issue inherent in metal molds exposed to induction fields, preventing overheating while maintaining containment strength.
4Device complexity
If uniform pressure is applied across all areas, then simple tooling design is possible, but weld quality is inferior because substantial pressure is not concentrated on the contacted surfaces
Solution Approach 1:
The rubber body is designed with non-uniform thickness where thinner sections correspond to areas requiring substantial pressure for welding. This local variation in geometry creates concentrated pressure zones exactly where needed on the contacted surfaces, improving weld quality. The rest of the tooling remains relatively simple without complex pressure distribution mechanisms.
Solution Approach 2:
The tooling utilizes the physical parameter of rubber thickness as a pressure distribution mechanism. By varying the thickness parameter of the rubber body in different regions, the system automatically concentrates pressure where needed without requiring complex mechanical pressure distribution systems. This simple geometric parameter change achieves both good weld quality and tooling design simplicity.
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
Enables the creation of high-quality, mechanically strong welds with controlled pressure application, reducing the need for robust molds and preventing tooling displacement, allowing for efficient and rapid welding of molded parts without overheating or material degradation.
Implementation Method 1
pressurizing means for pressurizing the rubber body and applying pressure to the contacted surfaces
Implementation Method 2
generates an electromagnetic field in an induction-sensitive component of one or more of the molded part(s) to heat a thermally activated coupling means
Implementation Method 3
heating the induction-sensitive component by means of an inductor
Implementation Method 4
heat a thermally activated coupling means of the molded parts to above a melting temperature of the coupling means
Implementation Method 5
joining the molded parts to each other by the molten coupling means
Data Source
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AI summary
A tooling for use in a method for electromagnetic welding of two contacted surfaces of molded parts is described. The tooling comprises a rubber body and pressurizing means for pressurizing the rubber body and applying pressure to the contacted surfaces. The rubber body comprises an embedded stiff body shaped such as to define different rubber body thicknesses in different directions, which causes a different pressure build-up in said different directions. Also described is a method for manufacturing the tooling. The tooling may be used in electromagnetic welding of two contacted surfaces of molded parts by moving a joining inductor along the contacted surfaces, generating an electromagnetic field in an induction-sensitive component of the molded parts to heat a thermally activated coupling means of the molded parts to above a melting temperature of the coupling means.