Active Metal Casting with Bottom-Tapping and Velocity Control
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Solution Overview
Problem
Conventional casting methods using induction melting furnaces with water-cooled copper crucibles face challenges in reducing shrinkage cavities and improving yield, particularly for small-diameter ingots, due to increased complexity and production costs associated with vacuum casting, centrifugal casting, and directional solidification methods.
Innovation Solution
A casting method that employs a bottom-tapping, induction-heating type crucible with a water-cooled copper crucible, controlling the pouring rate of molten metal to achieve directional solidification from the bottom of the ingot mold, thereby reducing shrinkage cavities and enhancing the yield of non-defective products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum casting or centrifugal casting methods are used to reduce shrinkage cavities, then shrinkage cavity reduction is improved, but device complexity and production cost increase
Solution Approach 1:
The invention extracts and eliminates the need for complex vacuum or centrifugal casting systems by utilizing the simple bottom-tapping method with controlled pouring rate. The solution removes unnecessary equipment complexity while achieving the same shrinkage cavity reduction through a simpler process.
Solution Approach 2:
The invention changes the parameter of pouring rate (casting velocity) to achieve directional solidification from the bottom of the mold. By controlling the pouring rate to be slow, the molten metal solidifies gradually from the bottom, preventing shrinkage cavities without requiring complex vacuum or centrifugal equipment.
2Manufacturing precision
If directional solidification method is used to prevent shrinkage cavity generation, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
Instead of heating the upper part of the mold to achieve directional solidification from the bottom (as in conventional directional solidification methods), the invention inverts the approach by using bottom-tapping with controlled pouring rate. The molten metal is poured from the bottom at a controlled rate, naturally achieving directional solidification from the bottom without requiring complex temperature control systems.
Solution Approach 2:
The invention allows the molten metal to achieve directional solidification naturally through controlled pouring rate without requiring external temperature control systems. The process self-regulates the solidification direction based on the controlled introduction of molten metal from the bottom, eliminating the need for complex heating zones.
3Ease of operation
If conventional tilting crucible method is used, then ease of operation is maintained, but shrinkage cavity generation increases and yield decreases
Solution Approach 1:
The invention inverts the conventional tilting crucible method by using bottom-tapping instead. The crucible is not tilted to pour molten metal, but rather the metal is tapped from the bottom through a tapping hole. This inversion maintains operational simplicity while achieving directional solidification from the bottom, reducing shrinkage cavities and improving ingot yield.
4Productivity
If casting velocity is increased to improve productivity, then production speed is improved, but shrinkage cavity generation increases
Solution Approach 1:
The invention changes the parameter of casting velocity (pouring rate) to an optimal value that balances productivity and quality. By controlling the pouring rate to be slow enough to allow directional solidification from the bottom, the invention achieves both acceptable productivity and minimal shrinkage cavity generation. The tapping hole opening diameter is adjusted to control the pouring rate.
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 effectively reduces shrinkage cavities and improves the yield of non-defective ingots by slowing down the casting velocity, shifting the solidification process to occur predominantly from the bottom, resulting in a higher percentage of defect-free ingot production.
Implementation Method 1
electromagnetic induction which causes heating in the induction melting furnace
Implementation Method 2
water-cooled copper crucible
Implementation Method 3
electromagnetic induction which causes heating in the induction melting furnace also causes electromagnetic repulsion for stirring a molten metal
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
In this casting method for an active metal, in an induction melting furnace (3) using a water-cooled copper crucible (2), a thin ingot (S) of an active metal is cast by tapping a melt M from a tapping hole (5) provided in a base section of the crucible (2) into a mold (4), wherein, when casting is performed under casting conditions in which the ingot has a diameter (D) of at least 10 mm, the ratio (H/D) of the height H of the ingot to the diameter D of the ingot is at least 1.5, and the weight of the melt M tapped in casting is no more than 200 kg, the temperature of the melt M during casting is set to be higher than the melting point of the active metal and casting is performed while the casting velocity V (mm/s), which is the velocity at which the casting advances in the mold 4, is controlled so that the relationship with the height H of the ingot satisfies V ≤ 0.1H by adjusting the opening diameter of the tapping hole 5.