Tubular Metal-Resin Joint Structure for Thermal Loosening Resistance
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Solution Overview
Problem
Existing methods for joining resin and tubular metal members in vehicle structures are prone to loosening due to thermal influences, as resin has a higher linear expansion coefficient than metal, leading to deformation and loosening of the joint.
Innovation Solution
A structure comprising a metal tubular first member, a resin second member, and a metal tubular third member, where the third member is tube-expanded and joined to the first member by press-fitting, with bulging portions formed on both sides, and the second member is injection-molded to the first member, ensuring similar linear expansion coefficients among the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin member is directly joined to a tubular metal member by press-fitting, then the joining method is simple, but the joint loosens due to thermal influence because resin has a larger linear expansion coefficient than metal
Solution Approach 1:
The patent introduces a tubular metal member as an intermediary component between the resin member and the base structure. This metal intermediary has a linear expansion coefficient closer to resin than the base metal structure, thereby reducing thermal expansion mismatch and preventing joint loosening while maintaining the simplicity of press-fitting assembly
Solution Approach 2:
The patent changes the material parameter (linear expansion coefficient) of the intermediary tubular member to match closer to the resin member. By selecting a metal alloy with appropriate thermal expansion properties, the patent reduces the differential thermal expansion between connected components, thereby maintaining joint integrity under temperature variations
2Strength
If a resin member is injection-molded directly to a long tubular member, then the integration is strong, but a large injection molding apparatus is required which reduces manufacturing flexibility
Solution Approach 1:
The patent segments the assembly process into two stages: first, the tubular metal member is inserted into the resin member; second, a separate cap member is injection-molded onto the assembled combination. This segmentation allows the use of a smaller injection molding apparatus while achieving strong integration through the combined mechanical insertion and molecular bonding
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 configuration suppresses loosening of the joint due to thermal influences by minimizing the difference in linear expansion coefficients between the materials, allowing for robust integration and varied design options for the third member.
Implementation Method 1
an elastic body is inserted into the third member, and the elastic body is pressurized in the tube axis direction to expand radially outward, thereby expanding the tubular member
Implementation Method 2
the second member is injection-molded to the first member
Data Source
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AI summary
A structure 10 includes: a first member 11 made of metal having a tubular shape, and having a through-insertion hole 11a; a second member 12 made of resin and joined to the first member 11; and a third member 13 made of metal having a tubular shape, and inserted through inside the first member 11. The third member 13 is tube-expanded toward the first member 11 and joined to the first member 11 by press-fitting.