Modular Polymer Lower Receiver With Metal Inserts for Impact Strength
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Solution Overview
Problem
Conventional lower receivers for firearms are typically made from metal due to issues with polymer materials, such as sink formation, complex mold requirements, and structural integrity under impact loads, making polymer alternatives costly and difficult to implement.
Innovation Solution
A modular lower receiver design using polymer components with complementary engagement surfaces and threaded inserts, allowing for separate assembly of grip attachment bodies and bolt catch assemblies, which reduces molding complexity and weight while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If lower receivers are made from polymer, then weight is reduced and manufacturing cost decreases, but structural integrity under impact loads and shear stresses deteriorates
Solution Approach 1:
The patent employs a composite construction where a polymer lower receiver body is combined with metal threaded inserts and metal grip attachment bodies. This composite approach allows the polymer to provide weight reduction and cost benefits while the metal components supply the necessary structural integrity and strength under impact loads and shear stresses.
2Ease of manufacture
If lower receivers are made from polymer with thick sections, then manufacturing cost decreases, but sink formation occurs during injection molding
Solution Approach 1:
The patent divides the lower receiver into multiple segments: the polymer main body and separate metal components (threaded inserts, grip attachment bodies). This segmentation eliminates the need for thick polymer sections, preventing sink formation during injection molding while maintaining manufacturing cost efficiency through polymer usage.
Solution Approach 2:
The patent extracts the threaded features and grip attachment bodies from the polymer structure and implements them as separate metal components. This extraction eliminates the need for thick polymer sections that would cause sinking, while allowing the polymer body to be manufactured with optimal wall thickness for cost-effective injection molding.
3Adaptability or versatility
If lower receivers include small, deep holes, then functional features are achieved, but very small steel tools are required that would deflect or break
Solution Approach 1:
The patent incorporates threaded inserts and internal features into the polymer lower receiver body during the injection molding process itself, before final assembly. This preliminary action eliminates the need for subsequent machining operations with small, fragile steel tools, as the features are formed directly in the molding process.
4Adaptability or versatility
If lower receivers include slide actions on many angles, then functional features are achieved, but mold becomes expensive and complicated
Solution Approach 1:
The patent segments the lower receiver into a polymer main body and separate metal components that are assembled together. This segmentation allows complex functional features to be achieved through assembly of pre-formed components rather than through complex multi-angle slide actions in the mold, significantly simplifying the molding process and reducing mold cost.
5Adaptability or versatility
If lower receivers include threaded holes for attachments, then adaptability is improved, but thread-forming slide action tool details become expensive and complicated
Solution Approach 1:
The patent extracts the threaded features from the polymer molding process and implements them as separate metal threaded inserts that are integrated into the polymer body. This extraction eliminates the need for complex thread-forming slide action tools in the mold, reducing mold complexity and cost while maintaining attachment capability.
Data Source
AI summary
A lower receiver includes a polymer main body having an outer surface and defining an interior. The interior of the polymer main body defines a first socket. A grip attachment body is receivable, along a first axis, into the first socket of the interior of the polymer main body. The grip attachment body includes a first threaded insert that is configured to receive a fastener for securing a grip to the lower receiver.