Inductive Sensing for Ingot Position in Vacuum Metallurgy
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Solution Overview
Problem
Vacuum metallurgical systems face challenges in producing high-quality ingots of reactive or refractory metals with small cross-sectional dimensions, as they are prone to contamination, yield loss, and mechanical failure due to temperature gradients, and achieving homogeneity is difficult, especially when casting larger ingots.
Innovation Solution
A method and system that determine the position of an ingot within a segmented, water-cooled mold using an inductive sensory system, monitoring current amplitude or frequency in the induction melting coil, and adjusting the ingot position to maintain optimal melting conditions, ensuring the top of the ingot remains molten and homogeneous.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-cooled copper vessels are used to melt reactive or refractory metals, then contamination by oxide refractories is avoided, but thermal efficiency drops to only about 25%
Solution Approach 1:
The patent introduces an inductive heating system as an intermediary between the power source and the metal charge, using electromagnetic fields to heat the metal directly within the water-cooled copper vessel. This resolves the contradiction by maintaining the contamination-free advantage of water-cooled vessels while achieving high thermal efficiency through direct electromagnetic heating, eliminating the need for inefficient conductive heating through the vessel walls.
2Productivity
If larger ingots are cast to reduce the number of forging steps, then production time is reduced, but the grain size becomes larger and less homogeneous due to lower surface-area-to-volume ratio
Solution Approach 1:
The patent applies periodic inductive heating with stirring action to maintain molten metal homogeneity during casting of larger ingots. The periodic agitation and heating cycles prevent stratification and ensure uniform temperature distribution and compositional homogeneity throughout the molten metal, achieving fine grain structure even in large cross-sectional ingots while maintaining high productivity.
3Adaptability or versatility
If ingots are forged down to desired size from larger ingots, then flexibility in producing various shapes is achieved, but yield loss increases to 60-70% due to deformation of ingot ends
Solution Approach 1:
The patent performs preliminary casting of ingots at or near the final desired cross-sectional size using controlled inductive heating and casting parameters. This preliminary action optimizes the initial ingot dimensions and microstructure, minimizing the amount of material that must be removed during subsequent forging operations and reducing yield loss while maintaining shape flexibility.
4Manufacturing precision
If the top of the ingot is maintained in a molten state during casting, then homogeneity is improved, but energy consumption increases
Solution Approach 1:
The patent applies local inductive heating directly to the top region of the ingot where molten metal is required, rather than heating the entire ingot uniformly. This localized heating approach maintains the necessary molten state at the top for homogeneity and mixing while minimizing energy consumption by avoiding unnecessary heating of already solidified or cooled regions of the ingot.
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 allows for the production of high-quality ingots with reduced cross-sectional dimensions that are free of internal voids and require minimal post-formation clean-up, achieving better homogeneity and minimizing mechanical flaws, thereby improving yield and reducing processing time.
Implementation Method 1
heating the metal or alloy with an induction coil
Implementation Method 2
an sensor induction coil positioned to sense changes in electrical current
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A system and method for sensing the position of an ingot within a segmented mold of a vacuum metallurgical system. An inductive sensory system measures the variations in current between a power source and load of an induction heating coil. The system and method is particularly suitable for determining the position of an ingot within a melting system mold where the mold has a relatively reduced or small cross-sectional area.