Firing Pin Diameter Gradient for Powder-Actuated Tool Primer Ignition
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Solution Overview
Problem
Conventional hammer-drive powder-actuated tools suffer from misfires due to misalignment of the firing pin and accidental ignition of the primer when the tool is dropped, leading to safety concerns and reduced success rate in igniting the powder cartridge.
Innovation Solution
The design includes a firing pin with a diameter larger at the front end than the inner primer and smaller than the outer primer, and a pin holder with a through hole that gradually reduces in diameter, ensuring alignment and preventing accidental ignition by maintaining the firing pin away from the primer when not in use, along with a resilient member to bias the firing pin away from the cartridge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the firing pin head has a large diameter, then the firing pin can easily contact the powder cartridge, but misfire occurs when the central axis is inclined
Solution Approach 1:
The firing pin head is designed with non-uniform diameter distribution, featuring a larger front portion for reliable contact and a smaller rear portion for precise alignment, creating different functional zones on the same component
Solution Approach 2:
Instead of making the entire firing pin head large for contact reliability, the invention inverts the approach by making the front contact portion large while the rear alignment portion is small, reversing the conventional uniform design
2Stability of the object's composition
If a reed spring is disposed between the firing pin and powder cartridge to prevent accidental removal, then the cartridge is retained, but accidental ignition occurs when the tool is dropped
Solution Approach 1:
The reed spring component is completely removed from the design. Instead of using a separate retention component, the invention integrates retention function into the firing pin structure itself through the tapered through-hole design
Solution Approach 2:
The tapered walls of the through-hole act as an intermediary mechanism between the firing pin and cartridge, providing both retention and protection functions without requiring direct contact between the firing pin head and cartridge
3Productivity
If the firing pin is positioned close to the primer for easy ignition, then ignition efficiency is improved, but accidental firing occurs when the tool is dropped
Solution Approach 1:
The firing pin position is made dynamic rather than fixed. The resilient member allows the firing pin to move forward upon impact while maintaining a retracted position during normal handling, enabling both safe storage and efficient ignition
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 significantly increases the success rate of primer ignition and enhances safety by preventing accidental firing, even when the tool is dropped, by ensuring proper alignment and maintaining the firing pin away from the primer until activation.
Implementation Method 1
a resilient member biasing the firing pin away from the cartridge
Implementation Method 2
a hammer is operated to strike the externally threaded rear end of the firing pin
Implementation Method 3
ignite the powder cartridge to thereby drive forward movement of the piston
Data Source
AI summary
A hammer-drive powder-actuated tool includes a hollow tool body extending along a front-to-rear direction, and a firing device disposed within a rear end portion of the tool body. The firing device includes a pin holder having a through hole extending along the front-to-rear direction, and a firing pin movable forwardly and rearwardly relative to the pin holder. The pin has a firing end portion that is disposed at a front end thereof and that extends into the through hole in the pin holder, and a central axis aligned with that of a rimfire cartridge along the front-to-rear direction. A front end of the firing end portion of the firing pin has a diameter larger than the inner diameter of the annular primer and smaller than the outer diameter of the annular primer.