Rotary Lug Breech Cam Mechanism for Soft Cartridge Ejection
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Solution Overview
Problem
Rotary lug locks in machine guns experience significant accelerations and actuating forces during high firing rates, leading to reduced accuracy and reliability, as well as issues with ejecting tightly seated cartridge cases, which can result in jamming and decreased aiming precision.
Innovation Solution
The rotary lug lock design incorporates a cam section in the locking piece that interacts with a control section on the bolt head, converting rotary movement into a screwing motion to facilitate the ejection of cartridge cases with reduced jerk and increased force leverage, while also guiding the locking head with minimal friction to maintain accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the firing rate is increased to improve productivity, then the weapon can deliver fire faster, but the accelerations and actuating forces on the rotary lug lock increase, reducing accuracy and reliability
Solution Approach 1:
The locking lugs are designed with rounded edges that convert the rotary movement of the bolt head into a linear movement during locking and unlocking. This dynamic conversion reduces the accelerations and actuating forces on the locking mechanism, allowing high firing rates to be achieved without compromising accuracy and reliability
Solution Approach 2:
The geometry of the locking lugs is modified by rounding the edges, which changes the movement parameters from pure rotation to a combination of rotation and linear motion. This parameter change reduces the harmful dynamic effects during high-rate firing
2Device complexity
If conventional locking lugs are used, then the locking mechanism is simple, but tightly seated cartridge cases cannot be ejected, causing jamming
Solution Approach 1:
The rounded edges on the locking lugs create a wedging action during unlocking that converts rotary motion into linear extraction force. This dynamic mechanism allows the locking lugs to both lock securely and extract tightly seated cartridge cases reliably, without increasing device complexity
Solution Approach 2:
The rounded edges of the locking lugs act as an intermediary element between the rotary motion of the bolt head and the linear extraction force needed to remove tightly seated cartridge cases. This intermediary geometry enables both locking and extraction functions
3Manufacturing precision
If the locking lugs have sharp edges for precise locking, then locking is secure, but the release during unlocking creates rebound and jerk
Solution Approach 1:
The locking lugs are designed with rounded edges that convert the rotary movement into linear movement during unlocking. This dynamic conversion eliminates the rebound and jerk caused by sharp edges disengaging, while maintaining secure locking when engaged
Solution Approach 2:
The rounded edges, which might seem to reduce locking precision, actually convert the potentially harmful rebound effect into a beneficial smooth extraction action. The geometry transforms what would be a harmful discontinuous motion into a continuous, controlled linear movement
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 allows for 'soft' release of empty cartridges, increased extraction efficiency, reduced risk of cartridge case tearing, and enhanced aiming accuracy by minimizing recoil forces and internal friction, thereby improving the overall firing characteristics of the weapon.
Implementation Method 1
a cam section is formed in the locking piece, which interacts with a correspondingly formed control section on the bolt head
Implementation Method 2
The locking head is guided in the locking piece by a cylindrical shaft surface in its front area
Data Source
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AI summary
The invention relates to a rotary lug breech comprising: a breech carrier (1); a breach head (100) mounted therein and comprising a plurality of breech lugs (104); and a locking piece (200) comprising a plurality of locking lugs (204). A rearward facing cam section (208) is formed in the locking piece (200) on a locking lug (204). When the breech head (100) is released, said cam section converts a release motion, during which rear end faces (106) of the breech lugs (104) detach from front end faces (206) of the locking lugs (204), by means of a forward facing control section (132) correspondingly formed on a control breech lug (104h') into a screwing motion of the breech head (100) in order to release a cartridge case retained in the breech head (100) from a cartridge chamber, during which screwing motion the control section (132) is supported on the cam section (208). During locking, the cam section performs a pre-control function, which rotates a control pin (102) in a control gate (60) of the breech carrier (1) from an axial stop (70) into a control position in which the control gate (60) engages at a locking edge (62) with the control pin (102) and, when the breech carrier (1) moves forward relative to the breech head (100), exerts a rotary momentum on the breech head (100) and thus converts a linear feed motion of the breech head into a locking motion by means of screwing motion.