Hollow Structural Section With Hinge-Folded Lid
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Solution Overview
Problem
Existing injection-molded structural components, such as automotive front end carriers, face challenges in achieving high stiffness and low weight due to the limitations of rib-reinforced U-sections, and the implementation of hollow structural sections is hindered by the inability to separate a hollow section from the injection mold.
Innovation Solution
An injection-molded structural component with a hollow section is created by using a section body with a cavity and a hinge-folded lid secured with fastening means, such as rivets or welding, to form a stiff and lightweight structure that can withstand dynamic loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hollow structural sections are used in injection-moulded components, then stiffness is improved and weight is reduced, but the component cannot be separated from the injection mold
Solution Approach 1:
The hollow structural section is divided into two segments: a section body with an open cavity and a separate section lid. The lid is hinged to the body, allowing the assembly to be injection-molded as a single piece that can be easily separated from the mold, while still forming a closed hollow structure when assembled.
Solution Approach 2:
The section lid is designed with a hinge connection that allows it to be in two states: open during injection molding for easy mold separation, and closed during use to form the complete hollow structural section. This dynamic configuration resolves the contradiction between mold separation ease and structural integrity.
2Ease of manufacture
If rib-reinforced U-sections are used, then manufacturing is simplified, but weight is increased and stiffness is limited
Solution Approach 1:
Instead of adding ribs to a U-section, the invention segments the structure into a U-shaped body and a lid that closes the opening. This creates a hollow closed-section structure that inherently provides higher stiffness without requiring additional reinforcement ribs, thus maintaining manufacturing simplicity while improving mechanical properties.
Solution Approach 2:
The hollow structural section combines the U-shaped body and lid into a composite structure that leverages the geometric advantage of closed sections for high stiffness-to-weight ratio, eliminating the need for rib reinforcements while maintaining ease of injection molding.
3Ease of manufacture
If rib-reinforced U-sections are used, then manufacturing is simplified, but weight is increased
Solution Approach 1:
The segmentation into body and lid allows formation of a hollow closed-section structure that achieves high stiffness without additional reinforcement ribs. This eliminates unnecessary material (the ribs) while maintaining manufacturing simplicity through single-step injection molding of the hinged assembly.
Solution Approach 2:
The hollow structural section utilizes thin-walled closed-section geometry formed by the body and lid assembly. This approach achieves high stiffness-to-weight ratio through geometric efficiency rather than material quantity, eliminating the need for heavy rib reinforcements while keeping the component lightweight.
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 approach allows for the manufacture of a hollow structural section that balances stiffness and weight, enabling the production of components that are both strong and lightweight, with the added benefit of being manufactured in a single injection molding step and avoiding warping.
Implementation Method 1
the fastening means comprises a circumferential welding seam
Implementation Method 2
the fastening means comprises a plurality of rivets; the rivets have welded rivet heads
Data Source
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AI summary
An injection-moulded structural component with a hollow structural section, said hollow structural section comprising a section body (24) having a cavity (30) with an opening (34), a section lid (26) secured to said section body via a hinge (28) and hinge-folded onto said opening, and a means (46) fastening the section lid (26) to the section body (24) such that the hollow structural section withstands dynamical load. Preferred application to automotive front end carriers.