EDM Wire Scoring for Rupture Disk Manufacturing
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Solution Overview
Problem
Traditional methods for manufacturing rupture disks require precise and costly hard tooling, which can be damaged easily and necessitate frequent heat treatment, making it difficult to produce large sizes and maintain tolerances, and often require new tooling for changes in disk profiles or geometry.
Innovation Solution
The method involves using electrical discharge machining (EDM) to rotate a rupture disk blank and move an EDM wire relative to it, allowing precise scoring on the convex side of the dome near the transition to the flange in a controlled pattern, using standard EDM equipment that can handle multiple sizes and materials with minimal tooling changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard tooling is used for scoring rupture disks, then scoring precision can be achieved, but tooling is easily damaged and requires frequent heat treatment
Solution Approach 1:
The patent replaces traditional mechanical hard tooling with electrical discharge machining (EDM) technology. Instead of using physical contact between hard tooling and the rupture disk material, the invention uses electrical discharges to erode and score the disk precisely. This substitution eliminates the wear and damage issues associated with mechanical hard tooling while maintaining scoring precision.
Solution Approach 2:
The invention changes the fundamental parameter of the scoring process from mechanical force to electrical energy. By controlling electrical discharge parameters (current, pulse duration, electrode geometry), the system achieves precise scoring without the mechanical contact that causes tooling damage. This parameter change allows the same process to work on large sizes without the heat treatment distortions that affect hard tooling.
2Ease of manufacture
If hard tooling is used for scoring, then scoring can be performed, but heat treatment is required which distorts tooling beyond acceptable tolerances
Solution Approach 1:
By replacing mechanical hard tooling with EDM, the invention eliminates the need for heat treatment entirely. The electrical discharge process can be performed on standard, non-heat-treated tooling, avoiding the thermal distortion that compromises tooling tolerance. This substitution resolves the contradiction between manufacturing capability and precision maintenance.
3Productivity
If traditional scoring methods are used, then rupture disks can be manufactured, but changes in disk profile or geometry require new tooling
Solution Approach 1:
The invention introduces dynamic adaptability through programmable EDM parameters. Instead of static hard tooling that must be physically redesigned for each disk variation, the system uses controllable electrical discharge parameters (current, pulse width, electrode movement patterns) that can be dynamically adjusted via programming. This allows the same physical setup to accommodate different disk profiles and geometries by changing process parameters rather than physical tooling.
Solution Approach 2:
The invention changes the approach from physical tooling modification to parameter modification. By controlling electrical discharge parameters through programming, the system can adapt to different disk profiles, geometries, and materials without requiring new physical tooling. This parameter-based adaptability resolves the contradiction between maintaining manufacturing capability and achieving tooling flexibility.
4Ease of manufacture
If hard tooling is used for scoring, then scoring can be performed, but tooling must be rebuilt and replaced when worn or damaged
Solution Approach 1:
By replacing mechanical hard tooling with EDM, the invention eliminates tooling wear and damage issues. The electrical discharge process uses eroded material removal rather than mechanical cutting, so the electrode tooling does not suffer from the same wear mechanisms. This substitution dramatically reduces maintenance requirements and eliminates the need for rebuilding and replacing worn tooling.
Solution Approach 2:
The EDM electrode can be considered a disposable or easily replaceable element compared to expensive hard tooling. When electrode wear does occur, it can be replaced more easily and economically than rebuilding hardened steel tooling. This approach trades the high cost and complexity of hard tooling maintenance for simpler, more economical electrode replacement.
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 approach enables precise and efficient scoring of rupture disks with reduced tooling wear and distortion, allowing for consistent production across various sizes and materials without the need for frequent heat treatment, thereby improving manufacturing efficiency and flexibility.
Implementation Method 1
wire electrical discharge machine forms a score or cut that extends a partial distance through the outer surface of the disk concave convex portion
Data Source
AI summary
The present invention provides an improved method of manufacturing a rupture disk and specifically of forming a score on a rupture disk. The method of the present invention includes the rotating of a rupture disk blank relative to an electrical discharge machining or “EDM” cutting wire and the simultaneous moving of the EDM cutting wire toward the axis of the disk while maintaining the wire in a selected position such as generally parallel to the disk peripheral skirt or flange. The rotation of the disk and the movement of the EDM wire can be precisely controlled with the motion system of a commercially available EDM machine. With the present invention, a precise score is cut a partial distance through the disk thickness and preferably on the convex side of the dome, near the transition from the dome to the flange and in a generally “c” shaped pattern. The formed score creates a pattern of weakness so that the disk will open in either of the forward or reverse buckling direction. Score patterns other than the “c” shaped pattern could be cut.