Semisolid Slurry Production Using Multiple Stirring Devices
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Solution Overview
Problem
Current methods for producing semisolid metal slurries face challenges in scaling up shot weights without increasing lead times, quality, and cost, particularly due to difficulties in managing the size and cooling of cast pieces in the Rheocasting process.
Innovation Solution
The use of multiple stirring devices with smaller cast metal pieces attached, rotating simultaneously around their central axes and a common axis, to enhance shearing and homogenization, allowing for increased shot weights without enlarging individual cast pieces, thus optimizing melting time and solid particle content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the weight of the cast piece on the stirrer is increased to achieve larger shot weight, then the shot weight increases, but the melting time of the cast piece increases and lead time increases
Solution Approach 1:
The invention divides a single large cast piece into multiple smaller cast pieces (first cast piece and second cast piece) that are attached to different stirring devices. This segmentation allows each small cast piece to melt quickly while collectively providing sufficient cooling to achieve the desired shot weight, thereby reducing lead time while maintaining productivity.
2Quantity of substance
If the weight of the cast piece on the stirrer is increased to achieve larger shot weight, then the shot weight increases, but the quality of the semisolid slurry decreases due to difficulty in breaking up dendritic networks
Solution Approach 1:
By using multiple smaller cast pieces instead of one large cast piece, the invention ensures that each small cast piece can be effectively surrounded by liquid metal and stirred, allowing dendritic networks to form and be broken up efficiently. This maintains slurry quality while achieving larger shot weights through the combined effect of multiple pieces.
Solution Approach 2:
The invention combines multiple stirring devices (first stirring device and second stirring device) working simultaneously in the same liquid metal bath. This merging of stirring actions creates enhanced turbulence and shearing effects that effectively break up dendritic networks from multiple cast pieces, maintaining high slurry quality even at larger shot weights.
3Quantity of substance
If the volume of the cast piece is increased to achieve larger shot weight, then the shot weight increases, but the surface area of the cast piece increases resulting in more local cooling and formation of solid shell
Solution Approach 1:
The invention segments the total cast metal volume into multiple smaller cast pieces with smaller individual surface areas. Each small cast piece experiences less local cooling and is less likely to form a thick solid shell, while the collective shot weight remains large. The smaller surface-area-to-volume ratio of each individual piece prevents excessive shell formation.
4Productivity
If only one stirring device is used, then the device complexity is low, but the productivity is limited and cannot efficiently produce larger quantities of semisolid slurry
Solution Approach 1:
The invention merges multiple stirring devices (first stirring device and second stirring device) to operate simultaneously in the same liquid metal bath. This combination multiplies the cooling capacity and stirring effectiveness, enabling efficient production of larger quantities of semisolid slurry while maintaining manageable system complexity through coordinated operation of the multiple devices.
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 results in a more efficient, cost-effective, and higher-quality semisolid slurry production by improving particle distribution and homogenization, enabling larger shot weights with shorter lead times and better control over solid particle content.
Implementation Method 1
The solid EEM has a lower temperature than the liquid metal bath and, combined with the endothermic melting of the EEM, the liquid metal bath is cooled and starts to solidify
Implementation Method 2
combined with the endothermic melting of the EEM, the liquid metal bath is cooled and starts to solidify
Implementation Method 3
By simultaneously using the mechanical stirrer to break up dendritic networks formed during the solidification
Data Source
AI summary
A method for producing a semisolid metal slurry, having the steps of providing at least two stirring devices, each having a first end and an opposite second end defining a central axis therebetween, wherein onto each first end a cast metal piece is attached; inserting the first end of each of the at least two stirring devices into a liquid metal bath such that each cast metal piece is submerged in the liquid metal bath; after insertion of the at least two stirring devices into the liquid metal bath, simultaneously rotating the at least two stirring devices with the attached cast metal piece around their respective central axis, and thereby rotating the cast metal pieces in the liquid metal bath; wherein the rotation is continued at least until a majority of the cast metal pieces are molten, such that a semisolid metal slurry is produced.