Insert-Molded Polymer Tips for Hunting Projectiles
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Solution Overview
Problem
Hollow-point bullets designed for hunting often compromise on aerodynamic characteristics due to their central pit or hollowed-out design, leading to reduced accuracy and penetration, while also posing environmental concerns related to lead usage.
Innovation Solution
The development of an expanding projectile featuring an insert-molded polymer tip and a metal jacket surrounding a solid core, which deforms to increase kinetic energy transfer and form larger exit wounds, and is free of lead, utilizing an insert-molding process for improved retention and reduced drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hollow-point design with central pit is used, then kinetic energy transfer and stopping power are improved, but aerodynamic characteristics and accuracy deteriorate
Solution Approach 1:
The projectile features a dual-material construction where the polymer tip provides aerodynamic quality at the forward section while the metal core provides penetration and expansion capability. This local differentiation allows the projectile to have optimized properties in different zones - the polymer tip reduces drag and improves accuracy, while the metal core maintains stopping power through controlled expansion upon impact.
Solution Approach 2:
The projectile combines polymer and metal materials in a composite structure. The polymer tip is bonded to the metal core, creating a hybrid projectile that leverages the advantages of both materials: the polymer's aerodynamic benefits and the metal's penetration and expansion characteristics. This composite approach resolves the contradiction between aerodynamic performance and kinetic energy transfer.
2Ease of manufacture
If lead is used in the projectile, then manufacturing ease and cost are improved, but environmental harm increases
Solution Approach 1:
The invention changes the material parameter from lead to polymer, maintaining the projectile's functional properties while eliminating the environmental harm associated with lead. The polymer tip can be manufactured using injection molding techniques, which are efficient and cost-effective, thus preserving ease of manufacture while removing the harmful lead component.
3Strength
If a hollowed-out design is used, then expansion upon impact is improved, but aerodynamic characteristics and penetration deteriorate
Solution Approach 1:
The projectile is segmented into two functional zones: the polymer tip that maintains aerodynamic integrity during flight for optimal penetration, and the metal core that provides expansion capability upon impact. This segmentation allows the projectile to excel at penetration during flight while maintaining expansion strength upon target impact, resolving the contradiction between these two properties.
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 enhances stopping power, blood loss for faster kills, and tracking of wounded animals, while addressing environmental concerns and improving aerodynamic performance by maintaining accuracy and penetration.
Implementation Method 1
a liquid elastomer is injected into the converging tip mold thereby partially filling an interior cavity in the projectile with an elastomer portion
Implementation Method 2
A melted polymer may be subsequently injected into the converging tip mold, thereby filling a remainder of the interior cavity and the converging tip mold with the melted polymer
Implementation Method 3
the melted polymer solidifies to form the polymer tip
Implementation Method 4
the polymer tip and the elastomer portion have a different durometer, such that the elastomer portion is relatively softer than the solidified polymer tip
Data Source
AI summary
Aspects of the disclosure are directed to manufacturing an insert-molded expanding projectile. Aspects of the disclosure include locating a portion of a projectile body within a converging tip mold, the projectile body including a metal jacket extending from a tail portion to a nose portion and surrounding an interior solid core. The metal jacket and nose portion may be tapered in a forward direction to an annular forward edge defining an opening to an undercut interior cavity. Melted polymer may be injected into the converging tip mold and allowed to cool thereby forming a polymer tip having a main portion forward of the opening and a tip retention portion filling the undercut interior cavity and having a shape corresponding to the undercut interior cavity to retain the polymer tip in place.