Continuous Casting Strip Oxidation Control
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Solution Overview
Problem
Twin roll casting of metal strips results in rapid scaling due to oxidation at high temperatures, leading to uneven friction and mill loads, which causes steering issues and production inefficiencies.
Innovation Solution
A method involving a continuous casting apparatus with counter-rotating rolls and controlled enclosures downstream from the nip, where oxygen-containing gas is introduced to create an atmosphere with specific oxygen and humidity levels to selectively oxidize the strip surface, reducing friction and improving steering control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the strip is maintained in a sealed enclosure with controlled atmosphere to inhibit oxidation, then scaling is reduced, but uneven scaling still occurs causing uneven friction and steering issues
Solution Approach 1:
The invention changes the atmospheric parameters (oxygen concentration and humidity) in the enclosure from inert/low-oxygen conditions to controlled oxygen-containing conditions (0.5-15% oxygen with 3-10% humidity), transforming the oxidation process from harmful to beneficial by enabling uniform scale formation that improves steering control
Solution Approach 2:
The invention converts the harmful oxidation process into a beneficial one by controlling the atmosphere to produce uniform scale on the strip surface. The scale that would normally cause friction problems is now formed uniformly to provide consistent friction characteristics, improving steering and mill load distribution
2Object-affected harmful factors
If non-oxidizing gases are delivered to the sealed enclosure to inhibit oxidation, then scaling is minimized, but uneven friction and steering control problems persist
Solution Approach 1:
The invention fundamentally changes the atmospheric composition parameters by introducing controlled amounts of oxygen (0.5-15%) and humidity (3-10%), replacing the traditional non-oxidizing atmosphere. This parameter change transforms the oxidation outcome from uneven and harmful to uniform and beneficial for friction characteristics
Solution Approach 2:
The invention uses controlled oxygen as a strong oxidant to accelerate and uniform the oxidation process on the strip surface. By delivering oxygen-containing gas at controlled concentrations, the oxidation is enhanced to form uniform scale that provides consistent friction coefficients across the strip width
3Productivity
If the strip emerges at high temperatures from the caster, then casting is efficient, but rapid scaling occurs due to oxidation in air atmosphere
Solution Approach 1:
The invention changes the atmospheric parameters in the enclosure from ambient air composition to controlled oxygen-humidity conditions, creating an environment that promotes uniform scale formation rather than rapid, uneven oxidation. This allows the strip to be handled at high temperatures without suffering from uncontrolled scaling
Solution Approach 2:
The invention converts the harmful rapid oxidation that occurs at high casting temperatures into a beneficial controlled oxidation process. By delivering oxygen-containing gas at controlled concentrations with humidity control, the high temperature exposure is transformed into an opportunity for uniform scale formation that improves subsequent processing
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 decreases mill loads, produces smoother strip surfaces, and enhances steering control, reducing the risk of deformities and increasing production yield by maintaining a consistent scale thickness across the strip.
Implementation Method 1
directing oxygen-containing gas having a desired amount of oxygen through the inlets into the second enclosure to provide an atmosphere of 0.5 and 15% oxygen with humidity between 3% and 10% in the second enclosure to oxidize at least one surface of the strip to form a desired more even thickness of scale on the surface of the strip
Implementation Method 2
provide an atmosphere of 0.5 and 15% oxygen with humidity between 3% and 10% in the second enclosure to oxidize at least one surface of the strip to form a desired more even thickness of scale on the surface of the strip
Data Source
AI summary
A method of improving control of thin strip produced by continuous casting including the steps of assembling a continuous casting apparatus having a pair of counter-rotating cooling rolls, having a nip there between and at least one enclosure downstream from the nip, introducing molten metal to form a casting pool supported on the cooling rolls above the nip and counter-rotating the cooling rolls forming cast strip downwardly from the nip, guiding the strip through the at least one enclosure downstream from the nip, the at least one enclosure having gas inlets for directing oxygen-containing gas into the enclosure, and directing oxygen-containing gas having a desired amount of oxygen through the inlets into the enclosure to provide an atmosphere 0.5% and 15% oxygen with between 3 and 10% humidity to oxidize at least one surface of the strip a desired thickness of scale on the surface of the strip to provide less mill force and downstream control of the strip.