Pyrotechnical Igniter Case Weak Zone Stamping
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Solution Overview
Problem
The existing manufacturing process for pyrotechnical igniter cases requires a plane zone for forming a weak zone, which incurs additional tooling costs, reduces internal volume, and causes deformations, leading to potential tool wear and adverse performance in vehicle safety devices.
Innovation Solution
A process that forms a weak zone on the pyrotechnical igniter case by striking a punch in a single movement, eliminating the need for a separate plane zone step, allowing for precise and reproducible weak zone creation while minimizing deformations and tool wear, and maximizing the charging volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plane zone is formed on the case prior to creating the weak zone, then the precision of the weak zone is improved, but the internal volume of the case is reduced and additional tooling costs are incurred
Solution Approach 1:
The patent combines the formation of the plane zone and the weak zone into a single stamping operation. The punching tool simultaneously creates both the plane zone and the weak zone in one movement, eliminating the need for a separate plane zone formation step. This merging of operations preserves internal volume while maintaining manufacturing precision through proper tool design.
Solution Approach 2:
The patent performs preliminary positioning and alignment of the punching tool to ensure that the weak zone is formed with the required precision directly during the stamping operation, without needing to pre-form a plane zone. The tool is designed to account for material behavior and achieve the desired weak zone geometry in a single action.
2Manufacturing precision
If a plane zone is formed on the case prior to creating the weak zone, then the tolerances for material thickness are achieved, but the manufacturing process complexity and tooling costs increase
Solution Approach 1:
The patent merges multiple manufacturing operations into a single stamping process. The punching tool is designed to simultaneously create the plane zone and weak zone in one operation, reducing process complexity while maintaining tolerance control through integrated tool design and single-step execution.
Solution Approach 2:
The patent optimizes stamping parameters such as force, velocity, and tool geometry to achieve precise weak zone formation with controlled material thickness tolerances in a single operation. By adjusting these parameters, the process maintains precision without requiring additional manufacturing steps.
3Manufacturing precision
If the weak zone is struck on a plane zone, then the manufacturing precision is improved, but the outer case surface becomes deformed and tool wear increases
Solution Approach 1:
The patent segments the stamping operation into controlled phases within a single punching action. The tool design separates the functions of creating the plane zone and forming the weak zone into distinct but simultaneous operations, allowing each to be optimized without compromising the other. This segmentation prevents excessive deformation while maintaining precision.
Solution Approach 2:
The patent controls stamping parameters such as force distribution, striking velocity, and tool geometry to achieve precise weak zone formation without excessive deformation of the outer surface. By optimizing these parameters, the process maintains manufacturing precision while preserving case surface integrity and reducing tool wear.
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 process ensures a controlled and reproducible opening of the vent hole at a predetermined pressure, reducing tool wear and improving the performance and positioning of the igniter case in vehicle safety devices.
Implementation Method 1
striking the wall with at least one punch in a single movement of striking. The single movement of striking deforms at least the part of the inner surface facing the at least one weak zone
Data Source
Figure 1~2
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AI summary
A metallic case (200) for a pyrotechnical igniter of a gas generator for a vehicle safety device that includes a peripheral side wall (204), a closed end (206), and a weak zone (202) in the peripheral side wall. The weak zone extends along a continuous trace (208) having a first end portion (208A), a second end portion (208B), and an intermediate portion (208C)between the first and second end portions. The first and second end portions of the continuous trace both transition from a first point (A) having a first side wall depth to a second point (B) having a second side wall depth. The second side wall depth is greater than the first side wall depth. The weak zone is configured for opening a vent in the peripheral side wall in response to an increase of pressure within the metallic case.