Directional Crystallization of Castings With Thermal Imaging Control
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Solution Overview
Problem
Existing methods for directional crystallization of castings lack continuous and automatic control of the actual transverse temperature gradient and observation of the crystallization front, leading to casting defects due to large curvature and uneven crystallization fronts.
Innovation Solution
Utilizing a thermal imaging camera to continuously observe and control the transverse temperature gradient and position of the liquid-solid zone, combined with dynamic control of inert gas blowing and mould extraction speed, ensuring a homogeneous crystallization front.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mould is moved from the heating zone to the cooling zone at a predetermined constant speed, then the production efficiency is improved, but the transverse temperature gradient becomes uncontrolled leading to casting defects
Solution Approach 1:
The patent transforms the static, predetermined mould extraction speed into a dynamic control system. The mould extraction speed is continuously adjusted based on real-time transverse temperature gradient measurements from the thermal imaging camera, allowing the system to adapt to actual crystallization conditions while maintaining high productivity and precision simultaneously.
Solution Approach 2:
The patent implements a closed-loop feedback system where the thermal imaging camera continuously measures the transverse temperature gradient, and this information is fed back to the control system which adjusts the mould extraction speed accordingly. This feedback mechanism ensures both high production efficiency and precise control of the crystallization front uniformity.
2Productivity
If the transverse temperature gradient is reduced to minimize crystallization time, then the productivity is improved, but the control complexity increases due to the need for real-time temperature monitoring and adjustment
Solution Approach 1:
The patent replaces complex mechanical temperature control systems with optical measurement technology. The thermal imaging camera provides non-contact, real-time temperature field measurement, eliminating the need for physical thermocouples and complex mechanical adjustment mechanisms, thereby reducing device complexity while maintaining high crystallization speed.
Solution Approach 2:
The patent introduces a thermal imaging camera as an intermediary device that bridges the gap between the molten metal and the control system. This intermediary enables indirect but accurate measurement of the temperature field, simplifying the overall control architecture while achieving precise temperature gradient management for high productivity.
3Device complexity
If indirect temperature measurement using thermocouples is used, then the device complexity is reduced, but the measurement precision is insufficient to directly reflect the temperature gradient in the crystallization front area
Solution Approach 1:
The patent replaces mechanical thermocouple-based measurement systems with optical measurement technology. The thermal imaging camera provides non-contact, full-field temperature measurement, delivering superior measurement precision for the temperature gradient in the crystallization front area while maintaining relatively simple device architecture.
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
Enables high-throughput, energy-efficient production of turbine blades with consistent macro- and microstructure by minimizing crystallization time and maintaining a small transverse gradient, reducing casting defects.
Implementation Method 1
The measurement is made using contactless temperature meters... The thermal imaging camera enables continuous observation of the transverse temperature gradient... based on thermal radiation from the mould surface
Implementation Method 2
heat removal from the surface of the mould during this process through radiation, which takes place in the cooling zone below the thermal insulation partition
Implementation Method 3
regulate the flow rate or gas mixture composition... of inert gas flow rates when gas blowing supports the mould cooling process
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The subject of the invention is a method and a device for directional crystallization of castings with oriented or monocrystalline structure. The method is based on the fact that during the transfer of the mould (1) the shape of the crystallization front is observed using the thermal imaging camera (9) and the external temperatures Tzx of the mould (1) and the internal temperatures Twx of the mould (1) are recorded and transverse gradients are analysed. A device for the production of castings with an oriented or monocrystalline structure, equipped with the thermal imaging camera (9) stably attached to a fixed element of the furnace, the optical centre S and the horizontal optical axis O, directed inside the chamber, to the vertical axis P of the crystallizer (3), and the horizontal optical axis (O) of the camera (9) and the vertical axis P of the movable crystallizer (3) are located on one plane, and the observed measurement area (14) of the camera is at the height of the thermal partition (8) and covers the lower part of the heating zone (5) and the upper part of the cooling zone (7).