Hot Mold Casting Process with Vacuum Cooling
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Solution Overview
Problem
Existing metal casting processes often result in defects, particularly in thin parts like gas turbine blades, due to premature cooling and solidification caused by temperature differences between the metal and mold, leading to cracks and voids, and the use of preheating furnaces complicates the process and increases the risk of workplace accidents.
Innovation Solution
A foundry process where the mold is preheated to a first temperature and metal casting occurs at a higher temperature within the same furnace, with controlled cooling and solidification at a pressure below 0.1 Pa, reducing thermal shock and minimizing mold movement, and the mold's wall thickness is modulated to manage thermal contraction stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the mold is preheated in a dedicated furnace, then the thermal shock during casting is reduced, but the process complexity increases and the risk of workplace accidents increases due to additional mold movement operations
Solution Approach 1:
The patent combines the preheating function and casting function into a single furnace system. The furnace is equipped with both preheating zones and casting zones, eliminating the need for separate preheating furnaces and reducing mold transfer operations. This merging of functions directly addresses the contradiction by maintaining mold temperature control while simplifying the overall process and reducing workplace safety risks.
Solution Approach 2:
The mold is preheated to the required temperature before the casting operation begins, within the same furnace. This preliminary heating action ensures that when the molten metal is introduced, the thermal shock is minimized. The preheating is performed in advance within the integrated furnace system, avoiding the need for separate preheating equipment and subsequent mold handling.
2Temperature
If the mold is removed from the preheating furnace and transported to the casting site, then the preheating can be performed, but the mold starts to cool during transport, increasing the possibility of defects
Solution Approach 1:
By integrating the preheating and casting operations within a single furnace system, the patent eliminates the transport step entirely. The mold remains in the furnace throughout the entire process, maintaining its preheated temperature without exposure to ambient conditions during transfer. This directly prevents the cooling issue and associated defect risks.
Solution Approach 2:
The mold heating and casting operations are performed continuously within the same furnace environment. The mold is preheated, then the metal is cast into it without removal or transport interruption. This continuous process ensures the mold temperature is maintained throughout, preventing the cooling that would occur during transport and thereby eliminating the associated defect risks.
3Quantity of substance
If the temperature difference between the metal and mold is large, then the casting can be performed, but premature cooling and solidification occurs in narrow passages, causing cracks and voids
Solution Approach 1:
The patent carefully controls the temperature parameters of both the mold and the casting metal. The mold is preheated to an optimal temperature, and the metal is cast at a controlled temperature that maintains an appropriate temperature difference. This parameter control prevents excessive thermal gradients that would cause premature solidification in narrow passages, thereby preventing cracks and voids while still enabling successful casting.
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 effectively reduces defects by controlling cooling rates and thermal stresses, allowing for the production of high-quality, thin components like gas turbine blades with reduced risk of cracks and increased production efficiency.
Implementation Method 1
preheating the mold to a first temperature, the casting of a metal in the liquid state, at a second temperature higher than the first temperature
Implementation Method 2
the cooling and solidification of the metal in the mold is carried out while the mold is maintained in the main furnace
Implementation Method 3
cooling and solidification of the metal in the mold held in the main furnace at a pressure below 0.1 Pa
Implementation Method 4
the cooling and solidification of the metal in the mold is carried out while the mold is maintained in the main furnace at a pressure below 0.1 Pa at least since casting
Data Source
AI summary
The invention relates to the foundry field, and in particular to a foundry process comprising the preheating of a mold (1) up to a first temperature, the casting of a metal in the liquid state, at a second temperature above the first temperature, in the mold kept in a main furnace (100) at the first temperature since the preheating, the difference between the first temperature and second temperature being no more than 80° C., the cooling and solidification of the metal in the mold (1) kept in the main furnace (100) at a pressure of less than 0.1 Pa at least since the casting, the removal of the mold (1) from the main furnace (100), and the demolding of the solidified metal.