Wind Turbine Base Casting with Cold Water Cooling
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Solution Overview
Problem
Current casting techniques for megawatt wind turbine bases using ductile iron face challenges in reducing shrinkage cavities and oxidation dregs, failing to meet non-destructive testing standards due to complex geometry and material reactivity, leading to inefficiencies and increased costs.
Innovation Solution
A non-chill, non-riser ductile iron casting technique using furan resin sand molds with microseismic compaction, controlled pouring rates, and a filtering system to minimize shrinkage and oxidation defects, ensuring even solidification and reduced chemical reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If common sand molding processes are used for casting ductile iron bases, then the casting process is simple and cost-effective, but the casting quality of the bottom surface is poor with shrinkage cavities and disperse shrinkage
Solution Approach 1:
The patent applies preliminary action by pre-cooling the mold cavity with cold water circulation before pouring the molten iron. This preliminary cooling action creates a temperature gradient that directs solidification from the bottom surface upward, preventing shrinkage cavities in the bottom surface without requiring complex post-processing or additional molding equipment.
Solution Approach 2:
The patent changes the temperature parameter of the mold cavity by introducing cold water circulation at controlled temperatures (5-25°C). This parameter change creates a controlled thermal field that modifies the solidification pattern of the ductile iron, enabling high-quality bottom surface casting using standard sand molding procedures.
2Manufacturing precision
If chills are placed in hot spots to reduce disperse shrinkage, then shrinkage is reduced, but oxidation dregs and air holes are produced making magnetic particle testing ineffective
Solution Approach 1:
The patent changes the thermal parameters by using controlled cold water cooling instead of physical chills. This creates a gradual temperature gradient that reduces shrinkage without the localized extreme cooling that causes oxidation dregs and air holes associated with traditional chill placement.
Solution Approach 2:
The patent introduces cold water as an intermediary cooling medium that circulates through channels in the mold cavity. This intermediary approach provides controlled heat extraction without direct contact between solidifying metal and cooling elements, eliminating the oxidation and gas entrapment problems caused by traditional chills.
3Manufacturing precision
If insulating and exothermic risers are used to compensate for shrinkage, then shrinkage is reduced, but production rate decreases and production cost increases
Solution Approach 1:
The patent applies preliminary cooling action to the mold cavity before pouring, which pre-establishes the solidification pattern. This eliminates the need for additional risers that would require separate placement and increase cycle time, thereby maintaining high production rates while achieving shrinkage compensation.
Solution Approach 2:
The patent extracts the need for additional riser components by incorporating the cooling function directly into the mold cavity structure through cold water circulation channels. This eliminates extra parts and assembly steps, improving production efficiency while maintaining shrinkage control.
4Manufacturing precision
If liquid nitrogen cooling systems are used to reduce disperse shrinkage in thick cross-section castings, then dynamic performance is improved, but the system cost is very high
Solution Approach 1:
The patent uses inexpensive cold water instead of expensive liquid nitrogen as the cooling medium. The cold water circulates through reusable channels in the mold cavity, providing effective cooling without the high cost associated with liquid nitrogen production, storage, and handling infrastructure.
Solution Approach 2:
The patent changes the cooling medium from extreme cold (liquid nitrogen at -196°C) to moderate cold (cold water at 5-25°C). This parameter change is sufficient to create the necessary temperature gradient for shrinkage control while dramatically reducing system cost and energy consumption.
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
The technique effectively reduces shrinkage holes and oxidation dregs, enhancing casting quality to meet EN DIN standards, improving production efficiency and cost-effectiveness by ensuring defect-free surfaces and compliance with EN DIN12680 and EN DIN1369 standards.
Implementation Method 1
the sand mold undergoes microseismic compaction in large microseismic monitoring system (microseismic compaction lasts a few minutes to twenty minutes and is carried out during molding). This increases the strength of the mold to meet technical requirements.
Implementation Method 2
the molten iron is slowly cooled down in the mold to below 400° C., then taken out of the mold.
Data Source
AI summary
A method of casting a base of high-power wind turbines with low-temperature nodular graphite iron, using furan resin sand as the mold sand and having no risers or chills in the mold. The mold undergoes microseismic compaction and has no chills risers. The parting face of the mold is perpendicular to the ground. The molten iron in the mold is solidified evenly. Therefore, shrinkage holes and disperse shrinkages base are reduced greatly and the dregs and air are discharged easily for the base. The pouring system designed together with a reasonable pouring rate and time make the filtering system useful for blocking dregs.