Reverse Acting Rupture Disc Laser Electropolished Weakness
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Solution Overview
Problem
Existing reverse acting rupture discs face challenges in achieving reliable full opening at low overpressures while preventing fragmentation, due to issues with manufacturing processes such as metal scoring, laser usage, and chemical etching, which affect surface finish, stress zones, and material corrosion resistance.
Innovation Solution
A reverse acting rupture disc with a laser-defined electropolished line-of-weakness recess is fabricated by pre-bulging, deflecting, and then returning a segment region to its original position, creating a smooth surface and altered grain structure for increased residual stress, and using electropolishing to form a W-shaped recess for reliable opening and extended service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal scoring is used to create a line of weakness, then the disc can open at a predetermined location, but the surface finish deteriorates and stress zones are created that reduce corrosion resistance
Solution Approach 1:
The patent replaces the mechanical scoring process with a laser-based process to create the line of weakness. The laser beam melts and vaporizes metal along the desired line, creating a precise opening path without the mechanical contact and surface damage associated with scoring dies. This substitution maintains manufacturing precision while eliminating the harmful effects of surface finish deterioration and stress zone creation.
Solution Approach 2:
The patent changes the physical state and properties of the line of weakness through controlled laser heating. By adjusting laser parameters (power, speed, pulse duration), the process creates a melted and resolidified metal line with altered grain structure and reduced yield strength, rather than mechanically deforming the metal. This parameter change achieves the opening function while maintaining surface integrity and corrosion resistance.
2Manufacturing precision
If laser is used to create a line of weakness, then manufacturing precision is improved, but surface oxidation occurs that impedes subsequent electropolishing
Solution Approach 1:
The patent applies a protective resist coating to the disc surface before laser processing. This preliminary action creates a barrier that prevents oxygen from reaching and oxidizing the metal surface during laser heating. The resist layer is then removed after electropolishing, revealing a clean, oxidation-free surface that responds well to the electropolishing process.
Solution Approach 2:
The resist coating serves as an intermediary substance between the laser beam and the metal surface. It allows the laser to heat and melt the metal for line of weakness creation while simultaneously protecting the surface from oxidation by blocking oxygen access. This intermediary layer is temporary and is removed after the protective function is complete.
3Reliability
If chemical etching is used to form a line of weakness, then the disc can open reliably, but the process time increases and material is removed that reduces disc thickness
Solution Approach 1:
The patent replaces the chemical etching process with a laser-based thermal process. Instead of using chemical reactions to remove metal, the laser beam directly melts and vaporizes material along the line of weakness path. This substitution dramatically reduces processing time while maintaining or improving opening reliability through precise control of the melting and resolidification process.
Solution Approach 2:
The patent utilizes phase transitions of metal (solid to liquid to vapor) under laser heating to create the line of weakness. The rapid heating causes localized melting and vaporization, and the subsequent rapid cooling creates a resolidified metal line with altered properties. This phase transition-based approach is much faster than chemical etching while providing reliable opening through controlled material removal and grain structure modification.
4Ease of operation
If a smooth surface is maintained for easy cleaning, then sanitation is improved, but creating a line of weakness becomes more difficult without affecting surface integrity
Solution Approach 1:
The patent uses laser processing to create the line of weakness without mechanical contact, preserving the smooth surface finish. Unlike scoring dies that physically scratch and deform the surface, the laser beam creates the opening path through controlled heating and melting, leaving the surrounding surface intact and smooth for easy cleaning.
Solution Approach 2:
The patent carefully controls laser processing parameters (power density, scan speed, pulse duration) to limit the heat-affected zone. By optimizing these parameters, the line of weakness is created with minimal thermal influence on the surrounding surface, maintaining the smooth finish required for sanitation while achieving precise opening characteristics through controlled material phase changes.
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
The solution ensures reliable full opening at a wide range of overpressure setpoints, prevents fragmentation, and maintains a smooth surface for easy cleaning, while extending the cycle service life and allowing for varied reversal pressure properties across multiple disc lots.
Implementation Method 1
A laser is employed to remove at least a portion of the layer of resist material corresponding to a desired line-of-weakness recess in the concave face of the bulged rupture disc
Implementation Method 2
The disc is then subjected to an electropolishing operation to remove metal from the lased area of the rupture disc, thereby forming a lustrous polished line-of-weakness recess in the disc
Implementation Method 3
The metal of the deflected and returned segment region exhibits higher residual stress than the disc material surrounding the initially deflected segment region resulting from initial plastic deformation of a localized segment region first in one direction, and then plastic deformation of that same localized segment region in the opposite direction
Data Source
AI summary
A reverse acting rupture disc is provided having a laser defined electropolished line-of-weakness recess, and an improved method of forming an electropolished line-of-weakness recess in a reverse acting rupture disc that assures full opening of the disc upon reversal. A rupture disc blank is pre-bulged, final bulged, and then provided with a layer of resist material. A laser is used to remove at least a portion of the layer of resist material corresponding to a desired line-of-weakness recess in the concave face of the bulged rupture disc. The disc is then subjected to an electropolishing operation to remove metal from the lased area of the rupture disc, thereby forming a lustrous polished line-of-weakness recess in the disc of desired configuration and of a predetermined depth that is related to material thickness. The electropolished line of weakness is defined by spaced opposed channel portions separated by a central raised crown portion wherein the channel portions are of greater depth than the crown portion. The burst/reversal pressure of the disc having an electropolished line-of-weakness recess may be selectively controlled by varying the pre-bulging pressure on the disc.