Radial Press-Down Rollers for Round Billet Core Densification
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Solution Overview
Problem
Continuous casting round billets, especially large diameter ones, suffer from severe internal segregation, porosity, and shrinkage cavities due to low solidification speed, leading to defects like cracks, uneven wall thickness, and reduced yield, which existing technologies such as melt purification, low superheat pouring, and electromagnetic stirring are unable to fully address, especially in achieving multi-point press-down requirements for round sections.
Innovation Solution
A device and method involving multiple round billet radial press-down devices with specific hole profiles and staggered arrangements, allowing continuous press-down at multiple positions along the axial direction of round billets within a solid phase ratio range of 0.65 to 1, achieving a total press-down rate of 10%-60%, effectively reducing segregation and porosity by extruding and compacting the core of the billets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-casting-speed continuous casting is used, then the solidification speed is low and columnar crystals are developed, but internal segregation, porosity and shrinkage cavity become more serious
Solution Approach 1:
The patent divides the press-down process into multiple stages with different press-down forces applied at different solidification phases. The press-down device is segmented into multiple rollers that can independently adjust pressure, allowing differentiated treatment of the billet at various positions and stages of solidification.
Solution Approach 2:
The press-down operation is performed during the solidification process itself (when solid phase ratio is 0.3-0.8), before complete solidification occurs. This preliminary action prevents the formation of severe defects by compacting the semi-solid material while it still has plasticity, rather than waiting until after solidification when defects are already formed.
2Object-generated harmful factors
If melt purification technology is used, then central segregation and porosity are prevented by reducing S, P content, but defects caused by solute redistribution and liquid steel flow shrinkage during solidification remain unaffected
Solution Approach 1:
The press-down device acts as an intermediary mechanical intervention between the molten steel and the mold wall. By applying controlled pressure during solidification, it mediates the solidification process to prevent defect formation, complementing the chemical purification methods by addressing mechanical and physical aspects of defect formation.
Solution Approach 2:
The patent changes the physical parameter of applied pressure during the solidification process. By dynamically adjusting the press-down force based on solidification progress (solid phase ratio), it addresses defects that cannot be controlled by chemical composition alone, thereby expanding the range of defect types that can be prevented.
3Object-generated harmful factors
If low superheat casting is used, then equiaxed crystal develops and center segregation and porosity are prevented, but adverse effects on the continuous casting process occur
Solution Approach 1:
Instead of completely changing the casting temperature regime (which would cause adverse effects), the patent applies a partial intervention by using press-down force only during the critical solidification phase. This targeted action achieves defect prevention without the need to alter the overall superheat parameters that maintain process stability.
Solution Approach 2:
The patent replaces thermal control mechanisms (superheat adjustment) with a mechanical intervention (press-down force). This substitution allows defect prevention through mechanical compaction during solidification rather than relying solely on thermal parameters, avoiding the adverse effects of low superheat casting while still preventing center segregation and porosity.
4Object-generated harmful factors
If electromagnetic stirring technology is used, then surface and center quality are improved to some extent, but influence on solidification center quality of large-sized round billets is limited and defect reduction is not obvious
Solution Approach 1:
The patent introduces a new dimension of control by applying press-down force in the radial direction during solidification, rather than relying solely on electromagnetic stirring which acts in the tangential direction. This dimensional change in the applied force vector allows direct compaction of the solidifying material, achieving better results for large diameter billets where electromagnetic stirring effectiveness is limited.
5Ease of operation
If soft press-down at solidification end is used, then deformation is applied but the deformation is difficult to penetrate into the center of billets and cannot compensate solidification shrinkage
Solution Approach 1:
The patent makes the press-down system dynamic by adjusting the press-down force according to the solidification progress (solid phase ratio). The press-down force is increased as solidification progresses, allowing the deformation to penetrate deeper into the billet center at later stages when the material has sufficient strength to transmit the force, rather than applying constant soft pressure throughout.
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 solution significantly reduces central porosity and segregation levels, increases billet yield, and lowers production costs by ensuring uniform deformation and compactness across the round billet sections, meeting the unique forming requirements of continuous casting round billets.
Implementation Method 1
Each round billet radial press-down device comprises three press-down rollers distributed along a circumference of a central axis of the round billets in an array. A forming hole for extruding the round billets is formed between the three press-down rollers
Implementation Method 2
A forming hole for extruding the round billets is formed between the three press-down rollers of each round billet radial press-down device
Implementation Method 3
A water cutting plate is arranged at an outer side of each press-down roller, and a shape of the water cutting plate corresponds with a roller shape of each press-down roller
Data Source
AI summary
A device for achieving a core part press-down technology in a continuous casting round billet solidification process includes a plurality of round billet radial press-down devices distributed along an axial array of round billets outside a press-down interval of the round billets. The press-down interval is an area from 0.65 of a solid phase ratio of the round billets to solidification end points. Each round billet radial press-down device includes a plurality of press-down rollers. A forming hole for extruding the round billets is formed between the press-down rollers. Two adjacent round billet radial press-down devices are arranged in the manner of staggering. The device can effectively solve the defect problems of porosity, segregation and the like in the core of the continuous casting round billets, the yield of the continuous casting round billets is increased, and the production cost is reduced.