Molded Polymer Part with Oblong Orifices for Metal Frame Assembly
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Solution Overview
Problem
The integration of polymer parts into automobile body structures poses challenges due to differences in thermal expansion coefficients with metal parts, requiring a secure assembly method that can withstand high temperatures during corrosion treatments, while allowing for differential expansions.
Innovation Solution
A molded polymer part with a flat assembly zone and oblong assembly orifices is designed to be secured to a metal frame, allowing for welding and movement, with varying orifice diameters to accommodate differential expansions, and featuring a support contour that enables secure attachment and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer parts are assembled to metal frame using conventional methods, then assembly security is achieved, but thermal expansion differences cause stress and potential failure at high temperatures
Solution Approach 1:
The assembly orifices are designed with variable dimensions (oblong shape with different diameters along different axes) to allow dynamic adjustment and movement. This enables the polymer part to accommodate thermal expansion and contraction relative to the metal frame, transforming the rigid fixed-assembly into a dynamic system that adapts to temperature changes while maintaining secure attachment
Solution Approach 2:
The invention changes the geometric parameters of the assembly orifices (making them oblong with specific diameter ratios) to create clearance that accommodates dimensional changes. The orifice dimensions are specifically designed to allow movement in directions corresponding to thermal expansion, thereby resolving the conflict between secure assembly and thermal stress
2Weight of moving object
If polymer parts are used to replace stamped sheet metal parts, then vehicle weight is reduced, but assembly compatibility with metal structure becomes problematic
Solution Approach 1:
The polymer part is designed with locally differentiated properties: the support contour region contains assembly orifices with specific geometric characteristics (oblong shape, variable diameters) that enable metal frame attachment, while the central load-bearing surface maintains structural integrity. This local differentiation allows the single polymer part to simultaneously achieve weight reduction and assembly compatibility
3Area of stationary object
If large polymer parts are assembled to metal frame, then structural coverage is improved, but maintaining structural integrity at high temperatures becomes difficult
Solution Approach 1:
The connection between polymer part and metal frame is segmented into multiple discrete attachment points (multiple assembly orifices distributed around the support contour). Each orifice provides an independent connection path, so that thermal stress and potential failure are localized to individual connection points rather than compromising the entire assembly. This segmentation maintains overall structural integrity while allowing local thermal movement
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 solution enables the secure assembly of large polymer parts with metal structures, maintaining structural integrity and allowing for thermal expansion, thus facilitating the use of polymer parts in high-temperature treatments without compromising the assembly's stability.
Implementation Method 1
the assembly orifices being of oblong shape in the plane of the assembly contour, and being dimensioned so that a central portion of each orifice is of sufficient width to assemble together by welding, two sheets of the frame... allowing for differential expansions
Data Source
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AI summary
A motor vehicle bodywork structure comprises - a metal portion forming a frame (14), - a moulded part (1) defining a bearing surface (5) such as a container or floor, configured to be assembled to the frame (14) in such a way as to be surrounded by the frame (14), the moulded part (1) comprising: - a load-bearing central surface (5), - a substantially planar bearing contour (9). The bearing contour (9) of the moulded part (1) is traversed by a sequence of oblong assembly holes (20) formed when moulding the part, suitable for assembling together two metal sheets (15, 41) of the frame (14) by welding, each situated on a different surface of the hole (20), and touching through the hole (20).