Nock Bushing Retention via Non-Round Interference Fit
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Solution Overview
Problem
Existing archery arrow nock bushings require adhesives for retention, which can compromise concentricity and increase weight, and there is a need for improved retention and weight reduction.
Innovation Solution
A non-round nock bushing with a stop flange and lightening openings that uses an interference fit with the arrow shaft to secure itself without adhesives, ensuring concentricity and reducing weight through a square or similar non-round shape and strategically placed openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive, cement, or glue is used to secure the nock bushing in the arrow shaft, then retention is achieved, but concentricity of the bushing relative to the arrow shaft is reduced
Solution Approach 1:
The patent removes the adhesive layer from the system entirely, extracting the harmful element that causes concentricity degradation. The solution relies solely on the mechanical interference fit between the non-round bushing body and the round arrow shaft, eliminating the need for chemical bonding agents that compromise precision.
Solution Approach 2:
The bushing body is designed with a non-round cross-section (square, triangular, or hexagonal) that creates an asymmetric interference fit with the round arrow shaft. This asymmetry ensures proper orientation and concentricity while maintaining secure retention through the elastic deformation of the shaft during insertion.
2Reliability
If a traditional round nock bushing is used, then retention can be achieved through interference fit, but weight reduction is limited
Solution Approach 1:
The patent incorporates multiple lightening openings (holes) through the bushing body that create a porous structure. These openings reduce the material volume and weight of the bushing while maintaining structural integrity and the necessary interference fit dimensions for retention. The openings are strategically positioned to minimize impact on mechanical strength.
3Reliability
If adhesive is used to secure the bushing, then retention is improved, but the overall device complexity increases due to additional materials and steps
Solution Approach 1:
The patent eliminates adhesive, cement, and glue from the assembly process, removing the complexity associated with applying, positioning, and curing these materials. The solution uses only the mechanical interference fit between the non-round bushing and round shaft, simplifying the assembly to a single insertion step.
Solution Approach 2:
The bushing design enables self-retention through its non-round geometry creating an automatic mechanical lock with the round shaft. The elastic deformation of the shaft during insertion provides self-aligning and self-securing functionality without requiring external adhesives or additional fastening components.
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
The solution provides secure retention without adhesives, maintains concentricity, and reduces the weight of the nock bushing by utilizing the arrow shaft's elastic properties to apply retaining force, eliminating the need for adhesives and ensuring a lightweight design.
Implementation Method 1
The arrow shaft will want to return back to its original round shape and thus applies force to a portion of an outer perimeter of the non-round body
Data Source
AI summary
A improved nock bushing preferably includes a non-round body and a stop flange. The non-round body preferably has a square shape. A nock hole is formed through at least substantially all of a length of the non-round body to receive a projection from an arrow nock. A plurality of lightening openings are preferably formed through the non-round body. The stop flange extends from one end of the non-round body. A distance across the largest cross-section dimension of the non-round body is preferably greater than a diameter of a bushing hole in an arrow shaft. In use, the non-round body is inserted into a nock end of an arrow shaft, which flexes the nock end. The arrow shaft will want to return back to its original round shape and thus applies force to an outer surface of the non-round body.