Arrowhead With Shear Pin Blade Deployment
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Solution Overview
Problem
Existing mechanical broadhead arrowheads face challenges with aerodynamic drag, safety concerns due to exposed blades, and reliability issues related to blade deployment and retraction, which affect accuracy and effectiveness in hunting.
Innovation Solution
A tip-actuated expanding blade arrowhead design featuring a cylindrical ferrule, a tip, blades, a hinge pin, and a shear pin, where the shear pin retains the blades before impact and shears upon striking a target, allowing the blades to swing out and deploy for maximum hemorrhaging, while maintaining a more aerodynamic profile during flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blades are exposed and fixed during flight, then cutting capability is maintained, but aerodynamic drag increases and accuracy decreases
Solution Approach 1:
The patent implements deployable blades that transition from a retracted position during flight to an extended cutting position upon impact. The blades are mounted on pivot pins allowing them to swing from a streamlined configuration that minimizes aerodynamic drag to a deployed configuration that maximizes cutting capability when needed
Solution Approach 2:
The broadhead is divided into separate functional components: a body housing, pivot pins for blade rotation, deployable cutting blades, and a retention mechanism. This segmentation allows the blades to be independently controlled - retracted during flight and deployed during impact - resolving the contradiction between aerodynamic efficiency and cutting capability
2Reliability
If blades are exposed during flight, then cutting capability is maintained, but safety risks increase due to accidental injury
Solution Approach 1:
The blades transition dynamically between retracted and deployed states. During flight and handling, blades remain retracted within the body housing, eliminating exposure risks. Upon impact, the retention mechanism fails and blades deploy to their cutting position, ensuring capability is only activated when needed
Solution Approach 2:
The retention mechanism is designed to fail at a predetermined moment - upon impact with the target. This preliminary design ensures that blades remain safely retracted during all handling and flight operations, then automatically deploy when the broadhead strikes the animal, eliminating accidental injury risks
3Reliability
If frictional engagement is used to retain blades, then blade retention is achieved, but controllability and reliability of deployment are reduced
Solution Approach 1:
The retention system is segmented into discrete components including the retention mechanism, pivot pins, and shear pins. This segmentation allows for controlled failure modes where the shear pin breaks at a predetermined point upon impact, providing reliable and controllable blade deployment without relying on difficult-to-control frictional engagement
Solution Approach 2:
The retention mechanism uses a shear pin with specific mechanical properties designed to fail at a predetermined force threshold. This parameter-based design provides reliable blade retention during flight while ensuring predictable and controllable deployment upon impact, overcoming the limitations of friction-based retention
4Object-affected harmful factors
If blades are partially retracted, then some aerodynamic benefit is achieved, but full retraction is not attained and drag persists
Solution Approach 1:
The blades are designed to fully retract into the body housing during flight, achieving complete streamlining. The dynamic deployment mechanism ensures that upon impact, blades swing fully to their cutting position, eliminating partial retraction issues and maximizing aerodynamic efficiency during flight
Solution Approach 2:
The blades are nested within the body housing when retracted, with each blade fitting into a designated slot or compartment. This nesting arrangement ensures complete retraction and streamlined profile during flight, while allowing full deployment when the retention mechanism fails upon impact
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 design enhances aerodynamic efficiency, reliability, and safety by ensuring blades are retracted during flight and fully deploy upon impact, reducing drag and improving accuracy and effectiveness in hunting.
Implementation Method 1
positioning a shear pin through a bore in the ferrule and through a second aperture near the other end of the at least one blade... when the arrowhead strikes a game animal the shank of the tip is forced into the ferrule... to force the at least one blade to swing out from the ferrule on the hinge pin to shear the shear pin
Implementation Method 2
the at least one blade is retained in the ferrule before the arrowhead strikes a game animal but that when the arrowhead strikes a game animal the shank of the tip is forced into the ferrule... to force the at least one blade to swing out from the ferrule on the hinge pin
Data Source
AI summary
A broadhead arrowhead having retractable blades wherein a plunger of the tip of the arrowhead causes the blades to shear a shear pin and deploy when the arrowhead strikes a target. In an alternative embodiment, the blades are retained in the arrowhead by a friction fit that is overcome to deploy the blades when the arrowhead strikes a target.