Jacketed Core for Complex Internal Passages
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Solution Overview
Problem
Existing methods for forming components with internal passages are hindered by fragile ceramic cores, costly and time-consuming production processes, and the inability to create complex passage curvatures, particularly in components like gas turbine parts that require efficient cooling and lubrication.
Innovation Solution
A jacketed core is used, comprising a hollow structure and an inner core with a core channel, where the inner core is positioned within a mold to define the internal passage, and the hollow structure is made from a material that can be absorbed by the molten component material, facilitating easier removal and reducing fragility issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ceramic cores are used to form internal passages, then the internal passages can be formed in the component, but the cores are fragile and difficult/expensive to produce and handle without damage
Solution Approach 1:
The core is constructed as a composite structure with an inner core made of ceramic material surrounded by an outer jacket made of absorbable material (such as wax or plastic). This composite construction combines the heat resistance and structural integrity needed for the internal passage formation with the flexibility and durability of the absorbable jacket, eliminating the fragility problems of traditional solid ceramic cores.
Solution Approach 2:
The absorbable outer jacket acts as an intermediary protective layer during the manufacturing process. It protects the fragile inner core during handling, transportation, and injection molding, and can be easily removed after the component is formed, leaving only the desired internal passage. This intermediary layer solves the handling difficulty without compromising the core's functional integrity.
2Reliability
If ceramic cores are used in investment casting molds, then internal passages can be formed, but the cores lack sufficient strength to reliably withstand injection of wax material
Solution Approach 1:
The core uses a composite structure where the absorbable outer jacket provides the mechanical strength needed to withstand wax injection pressures, while the inner ceramic core provides the heat resistance and defines the internal passage geometry. This division of functional requirements between two materials allows the core to withstand injection forces without increasing overall structural complexity.
3Manufacturing precision
If conventional drilling processes are used to form internal passages, then passages can be created in components, but the process is time-consuming and expensive, and cannot produce required passage curvatures
Solution Approach 1:
The internal passage geometry is pre-formed within the core structure before the component manufacturing process begins. The core is manufactured with the exact desired passage shape (including complex curvatures) already embedded, so that when the component is formed around it, the passage geometry is automatically transferred. This eliminates the need for subsequent time-consuming drilling or machining operations.
Solution Approach 2:
The invention replaces the mechanical drilling process with a molding process. Instead of mechanically removing material to create passages, the passage geometry is formed by the negative space around the core during component molding. This substitution of the formation mechanism dramatically reduces production time and enables complex curvatures that would be difficult or impossible to drill.
4Shape
If ceramic cores with large length-to-diameter ratios or nonlinear shapes are used, then complex internal passages can be formed, but effective removal of the cores from the cast component is difficult and time-consuming
Solution Approach 1:
The outer jacket is made from an absorbable material that is intentionally designed to be temporary and easily removable. After serving its protective function during manufacturing, it can be rapidly removed by melting, dissolving, or mechanical breakdown, leaving no difficult-to-remove ceramic material embedded in the component. This disposable approach to the outer layer dramatically reduces core removal time.
Solution Approach 2:
The absorbable jacket material is selected to undergo easy parameter changes (such as melting point or solubility) that facilitate rapid removal after casting. By choosing materials that can be transformed from a solid protective state to a removable state through simple parameter changes like heating or chemical treatment, the core removal process becomes fast and efficient regardless of the core's shape or size.
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 method allows for the cost-effective formation of components with complex internal passages, reducing fragility and production time, and enabling the use of longer, heavier, or more complex cores, while ensuring efficient fluid flow for cooling and lubrication.
Implementation Method 1
introducing a component material in a molten state into a cavity of the mold, such that the component material in the molten state at least partially absorbs the first material from the jacketed core within the cavity
Data Source
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AI summary
A method (700) of forming a component (80) having an internal passage (82) defined therein includes positioning (702) a jacketed core (310) with respect to a mold (300). The jacketed core includes a hollow structure (320) formed from a first material (322), an inner core (324) disposed within the hollow structure, and a core channel (360) that extends from at least a first end (311) of the inner core through at least a portion of inner core. The method also includes introducing (704) a component material (78) in a molten state into a cavity (304) of the mold, such that the component material in the molten state at least partially absorbs the first material from the jacketed core within the cavity. The method further includes cooling (706) the component material in the cavity to form the component. The inner core defines the internal passage within the component.