Rivet Nut Bushing Sleeve for Thread Alignment and Anti-Cross-Threading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rivet nut systems lack an effective alignment apparatus between the internal threads of the rivet nut and the external threading of installation tools or fasteners, leading to issues like cross-threading and improper installation, especially during over-upset conditions.
Innovation Solution
Incorporating a bushing sleeve within the rivet nut that snugly fits into the counterbore cavity, providing alignment between the internal threads of the rivet nut and the external threading of the installation tool or fastener, and enhancing control over the formation of the annular bulb during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no alignment apparatus is provided in the rivet nut, then the device complexity is reduced, but cross-threading and improper installation occur leading to reduced reliability
Solution Approach 1:
A bushing sleeve is introduced as an intermediary component between the installation tool mandrel and the rivet nut internal threads. The bushing sleeve has an inner diameter that guides the mandrel and an outer diameter that fits within the rivet nut counterbore cavity, providing alignment and preventing cross-threading during installation.
Solution Approach 2:
The rivet nut is segmented into multiple functional zones: a counterbore opening, a counterbore cavity housing the bushing sleeve, and an internally threaded mating chamber. This segmentation allows each zone to perform its specific function - the counterbore cavity provides alignment guidance while the mating chamber provides the fastening function.
2Manufacturing precision
If a bushing sleeve is added to the rivet nut, then alignment and anti-cross-threading are improved, but the manufacturing complexity increases
Solution Approach 1:
The bushing sleeve is pre-installed into the counterbore cavity of the rivet nut before the actual fastening operation. This preliminary action ensures that the alignment function is already in place, guiding the installation tool mandrel correctly from the start of the installation process.
Solution Approach 2:
The bushing sleeve serves as a mediator between the installation tool and the rivet nut, providing the necessary alignment without requiring complex manufacturing processes for the rivet nut itself. The sleeve can be manufactured separately and pressed into the counterbore cavity, simplifying the overall manufacturing approach.
3Ease of manufacture
If the counterbore cavity has parallel walls, then the manufacturing process is simpler, but control over annular bulb formation during upset is reduced
Solution Approach 1:
The counterbore cavity has parallel walls for most of its length to simplify manufacturing, but the terminal end features a converging wall section that tapers to a point. This local variation in geometry provides the necessary control over annular bulb formation during the upset process without complicating the overall manufacturing process.
Data Source
AI summary
An apparatus providing mating alignment between internal threading of a rivet nut and the external threading of the mandrel of an unclaimed installation tool before anchoring the rivet nut in a hole in a substrate, or the external threading of an unclaimed threaded fastener after anchoring in the substrate hole. The improvements include a bushing sleeve seated in a counterbore in the rivet nut, for guiding the external threading of the mandrel or fastener to the internal threading of the rivet nut. The sleeve also enables play during upset of the rivet nut, and provides visual confirmation whether the rivet nut has been properly anchored in the hole of substrate.