Rotating Forging of Round Casting Strands to Reduce Core Porosity
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Solution Overview
Problem
Existing methods for reducing the cross-section of metallic casting strands in the final solidification area to prevent core porosity and segregation are limited by the depth effect of rollers, which can lead to cracking and do not effectively address core porosity issues.
Innovation Solution
The method involves using forging tools to perform a soft reduction by forming a longitudinal section corresponding to at least a quarter of the strand diameter before cross-sectional reduction, with the tools rotated between forming strokes around the axis of the casting strand to apply shear and compressive stresses, reducing core porosity without increasing the cross-sectional reduction risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rollers are used for soft reduction in the final solidification region, then cross-sectional reduction is achieved to prevent segregation, but the depth of reduction is limited and core porosity cannot be effectively addressed
Solution Approach 1:
The patent changes the fundamental parameter of the forming tool from rollers to forging tools, enabling deeper plastic deformation and more effective cross-sectional reduction. This parameter change allows the process to address core porosity while preventing segregation, resolving the contradiction between reduction depth and porosity elimination.
Solution Approach 2:
The patent employs helical grooves with curved geometry that wrap around the cast strand. This curvature enables the forging tools to apply continuous compressive forces along the strand length, achieving deeper and more uniform cross-sectional reduction compared to linear roller contact, thereby effectively eliminating core porosity.
2Object-generated harmful factors
If larger cross-sectional reduction is applied to eliminate core porosity, then porosity decreases, but the risk of cracking increases
Solution Approach 1:
The patent employs dynamic helical grooves that rotate or move along the cast strand during the forming process. This dynamic action distributes the compressive forces over time and space, gradually reducing porosity without applying excessive localized stress that would cause cracking, thus maintaining strength while eliminating porosity.
Solution Approach 2:
The helical grooves are designed to engage the cast strand before complete solidification, performing preliminary plastic deformation while the material is still ductile. This preliminary action reduces porosity in the softer material state, preventing crack formation that would occur if the same reduction were attempted on fully solidified material.
3Manufacturing precision
If forging tools are used with axial extension to improve depth effect, then plastic deformation depth increases, but the complexity of the forming device increases
Solution Approach 1:
The forging tools with helical grooves serve multiple functions simultaneously: they provide axial extension for deep deformation, create the necessary compressive stresses through their geometry, and can be rotated or moved to distribute forces. This multi-functionality achieves deep plastic deformation without requiring separate complex mechanisms for each function, thereby limiting overall device complexity.
Solution Approach 2:
The helical groove geometry is segmented into continuous spiral paths that wrap around the cast strand. This segmentation allows the single forging tool to engage multiple points along the strand's circumference and length, achieving deep deformation effects without requiring multiple separate tools or complex positioning mechanisms.
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 enhances the depth effect of plastic deformations, allowing for a noticeable reduction in residual porosity and effectively preventing core porosity by gradually reducing cavity sizes through helical processing, while maintaining the cross-sectional shape and avoiding cracking.
Implementation Method 1
enhances the depth effect of plastic deformations
Implementation Method 2
apply shear and compressive stresses
Implementation Method 3
gradually reducing cavity sizes through helical processing
Implementation Method 4
the tools rotated between forming strokes around the axis of the casting strand
Implementation Method 5
gradually reducing cavity sizes through helical processing
Data Source
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AI summary
The invention relates to a method for working a metal casting strand (17) that is round in cross-section, by means of a reduction in cross-section in the final solidification region with the aid of at least three forming tools which are distributed around the circumference and act simultaneously on the casting strand (17). In order to provide advantageous working conditions, according to the invention the casting strand (17) is formed by forging tools (2, 3) constituting the forming tools in a longitudinal portion for each forming stroke, which portion corresponds to at least a fourth of the strand diameter before the reduction in cross-section, and the forging tools (2, 3) are rotated by an angle step about the axis of the casting strand (17) between the forming strokes.