Flexible Diaphragm Vacuum Sealing for Investment Casting
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Solution Overview
Problem
Current investment casting methods face challenges in achieving uniform and controlled atmospheres, often requiring complex setups and materials that can lead to geometry limitations, increased costs, and cracking issues during cooling.
Innovation Solution
A casting system utilizing a heat-resistant, flexible diaphragm that covers the casting mold and adheres to it under vacuum, combined with permeable layers to create a compound material that maintains vacuum and prevents cracking, along with a method that includes inflating the diaphragm with protective gas for optimal penetration and uniform gas distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional flasks and vacuum chambers are used for investment casting, then vacuum can be achieved, but geometry limitations and increased device complexity occur
Solution Approach 1:
The patent uses a flexible impermeable diaphragm as a vacuum seal instead of rigid flasks and vacuum chambers. The diaphragm can conform to various mold geometries while maintaining vacuum, eliminating the geometry limitations of traditional rigid systems and reducing overall device complexity.
Solution Approach 2:
The patent extracts the vacuum chamber function from the traditional flask-vacuum chamber combination by using the diaphragm itself as the vacuum barrier. This eliminates the need for separate vacuum chambers and complex sealing arrangements, simplifying the overall casting setup.
2Stability of the object's composition
If protective gas is introduced before vacuum to control atmosphere, then uniform gas distribution is improved, but loss of time occurs
Solution Approach 1:
The patent introduces protective gas into the casting mold before applying vacuum, allowing the gas to penetrate and saturate the porous ceramic structure in advance. This preliminary gas introduction ensures uniform atmosphere distribution throughout the mold, and the subsequent vacuum application maintains this uniformity without requiring additional gas introduction time.
3Reliability
If flammable cushioning sheets are used to create space, then vacuum sealing is improved, but loss of substance occurs
Solution Approach 1:
The patent uses a disposable combustible layer that is intentionally designed to be consumed during the casting process. This layer creates the necessary space between the mold and diaphragm, and its combustion is part of the intended process, eliminating the need for complex reusable cushioning mechanisms.
4Reliability
If complex sealing arrangements are used to prevent vacuum leakage, then vacuum reliability is improved, but device complexity increases
Solution Approach 1:
The patent uses a flexible impermeable diaphragm with an extended edge that can conform to the mold geometry and form a simple seal with the casting surface. This flexible membrane approach provides reliable vacuum sealing without requiring complex multi-component sealing arrangements, flanges, or rigid sealing mechanisms.
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 simplifies the casting process, reduces costs, eliminates geometry limitations, minimizes cracking, and allows for faster part release, enabling casting in an ultimate vacuum with uniform gas penetration and reduced ceramic consumption.
Implementation Method 1
application of vacuum to the sealed casting space through said at least one outlet causes the diaphragm to deform and shrink, thereby adhering to a portion of the casting mold
Implementation Method 2
said heat resistance coefficient is such that the diaphragm can melt when coming in contact with the molten casting material
Implementation Method 3
introducing, through said at least one ingress, gas into said sealed casting space at high pressure to cause said gas to permeate into said pores
Implementation Method 4
withdrawing gas from said sealed casting space via said at least one vacuum egress
Data Source
AI summary
A casting system includes a casting surface; a rim area disposed on the casting surface or associated therewith; a heat resistant impermeable diaphragm having an edge area. The diaphragm covers a portion of the casting mold when it is positioned on the surface so as to form a space defined by at least a base constituted by the surface, and at least a casting face constituted, at least partially, by the diaphragm; a sealing arrangement for sealingly engaging the rim and edge areas, thereby sealing the space; an outlet for withdrawing gas from the space; a heat resistance coefficient of the diaphragm is such that it can melt when coming in contact with the molten material. The diaphragm covers an area larger than that through which molten material is case so that, when the space is sealed, vacuum application causes the diaphragm to adhere to a portion of the mold.