Captive Bolt Mechanism for Planar Structural Assembly
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Solution Overview
Problem
Conventional structural assemblies face complexity and high manufacturing costs due to restrictive fastener requirements, difficulty in assembly and disassembly, and material deformation, especially when aiming for structural rigidity, which limits material choices and increases production costs.
Innovation Solution
A captive bolt mechanism that uses a T-shaped slot to secure a bolt or nut within planar structural members, allowing for easy assembly and disassembly without requiring secondary machining, maintaining structural rigidity and allowing for repeated use without material deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional fasteners are used to join planar members, then structural rigidity can be achieved, but the assembly process becomes complex and requires secondary machining
Solution Approach 1:
The fastening system is divided into separate components: a fastener member with a head and shaft, and a recess in the planar member. The shaft portion fits into the recess while the head remains external, allowing independent manufacturing and simplified assembly without secondary machining operations.
Solution Approach 2:
The shaft portion of the fastener member is nested within the recess of the planar member, creating an integrated joint. This nesting arrangement provides structural rigidity while maintaining simplicity in both manufacturing and assembly processes.
2Strength
If exacting manufacturing tolerances are used to achieve structural rigidity, then joint strength improves, but manufacturing costs increase
Solution Approach 1:
The fastener member is designed with a shaft portion that can be inserted into the recess with reasonable tolerances. The interference fit between the shaft and recess provides the necessary joint strength without requiring exacting manufacturing tolerances, thereby reducing manufacturing costs.
3Strength
If substantial material deformation is applied to achieve structural rigidity, then joint strength improves, but material choices are limited
Solution Approach 1:
The invention replaces mechanical deformation methods with an interference fit system. The shaft portion of the fastener member creates a press fit with the recess, achieving joint strength through friction and normal forces rather than plastic deformation, thus expanding material selection to include brittle and non-metalic materials.
4Strength
If threaded fasteners are used to join planar members, then structural rigidity is achieved, but secondary machining is required
Solution Approach 1:
The threading function is extracted from the fastener member itself and replaced by an interference fit system. The shaft portion with its external threading pattern creates a press fit with the recess, eliminating the need for secondary machining operations such as hole boring or tapping while maintaining structural rigidity.
Data Source
AI summary
A captive bolt mechanism joins planar structural members. In an exemplary embodiment, a first structural member has an opening defined there through. The head of a bolt is captured in a fastener slot within a second member, such that the threaded shaft of the bolt protrudes, in-plane, beyond the end of the second member. The threaded shaft is then passed through the opening in the first member and secured with a nut. As the nut is tightened, the underside of the bolt head is drawn against the interior surface of the fastener slot, binding the end of the second member against the surface of the first member. In an alternate embodiment, a nut is similarly confined within the fastener slot, and a bolt or screw is extended through the hole in the first member and the slot in the second member, and is then fastened to the nut.