Rapid Quench Line for Low-Tension Hot Coil Processing
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Solution Overview
Problem
Current metalworking processes, such as continuous annealing and solution heat treatment (CASH) lines, require large footprints, specialized equipment, and result in significant metal strip wastage due to the need for long, circuitous paths and mechanical handling issues when thermally processing metal strips at high temperatures, which can lead to damage and inefficiencies.
Innovation Solution
A system comprising a low-tension unwinding unit, non-contacting hold-down devices, rapid quenching zones that cool the metal strip at rates of at least 100 °C per second, and a bridle unit for tension application, allowing for efficient cooling and handling of hot metal coils without mechanical contact, using insulation, magnets, and steam reclamation to maintain temperature control and reduce waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional CASH lines are used for annealing or homogenization, then desired metallurgical properties can be achieved, but the system occupies a very large footprint and requires many specialized pieces of equipment
Solution Approach 1:
The continuous annealing and solution heat treatment process is divided into separate functional zones: a heating zone with radiant heaters, a soaking zone for homogenization, and a cooling zone with quenching mechanisms. This segmentation allows each zone to be optimized independently and reduces the overall footprint by eliminating the need for a single long continuous furnace
Solution Approach 2:
The patent transitions from the traditional linear path through CASH lines to a three-dimensional coil-based approach. Metal strip is coiled, heated in a compact furnace while coiled, and then uncoiled into the soaking and cooling zones, utilizing vertical space and three-dimensional positioning to reduce the horizontal footprint
2Manufacturing precision
If traditional CASH lines are used, then thermal processing can be performed, but long and circuitous paths require large amounts of metal strip to be scrapped
Solution Approach 1:
The metal strip is coiled into a compact form before entering the heating zone. This preliminary coiling action allows the strip to be heated efficiently in a compact space and then uncoiled directly into the soaking and cooling zones, eliminating the need for long threading paths and reducing scrap from leading and trailing ends
Solution Approach 2:
The system maintains continuous processing by keeping metal strip in a coiled state throughout the heating and soaking phases, then uncoiling it continuously through the cooling zone. This continuous action eliminates interruptions and reduces waste from starting and stopping the process
3Ease of operation
If traditional handling methods are used at elevated temperatures, then metal strip can be processed, but physical contact with rollers or the like may harm the delicate metal strip
Solution Approach 1:
The patent replaces traditional mechanical contact handling (rollers, belts) with a coil-based handling system. The metal strip is held in a coiled state using a coil holder and uncoiled using a payoff reel, eliminating direct mechanical contact between rollers and the hot metal strip surface, thereby preventing damage to the delicate strip
4Productivity
If rapid quenching is applied to cool metal strip, then processing time is reduced, but the system requires precise temperature control equipment
Solution Approach 1:
The patent utilizes phase transition of water to steam in the quenching zone. Water is sprayed onto the hot metal strip, rapidly evaporating to steam and absorbing large amounts of heat. This phase transition provides extremely efficient cooling that achieves rapid quenching without requiring complex mechanical cooling systems
Solution Approach 2:
The system controls the quenching process by adjusting parameters such as water spray rate, spray pressure, and spray pattern. By changing these parameters, the cooling rate can be precisely controlled to achieve the desired metallurgical properties while maintaining a relatively simple equipment design
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 solution enables rapid quenching and recoiling of hot metal coils, reducing processing time and waste, while maintaining desired metallurgical properties and improving handling efficiency, thus saving time, expense, and capital expenditure compared to traditional methods.
Implementation Method 1
a non-contacting hold-down device positioned adjacent the low-tension unwinding unit to provide force on the metal strip towards the center of the metal coil during unwinding of the metal coil
Implementation Method 2
a set of quenching zones for cooling the metal strip, wherein the set of quenching zones provides sufficient coolant to reduce a temperature of the metal strip by a rate of at least 100 °C per second
Implementation Method 3
The low-tension unwinding unit can include insulation to retain heat within coiled portions of the metal coil
Data Source
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AI summary
A rapid quenching line can be suitable for use with hot coil at, or above the metal strip's recrystallization point. Hot coil can be uncoiled by a low tension uncoiler using a non-contacting hold-down device. The metal strip coming off the hot coil is rapidly quenched (e.g., at rates of at or above 100°C/s or 200°C/s) through multiple quenching zones. Coolant can be removed, such as with an air knife and/or a wiper (e.g., an ultra-compliant wiper). Steam can be collected from earlier quenching zones and be repurposed to provide humid air to the metal strip, such as at regions where the temperature of the metal strip is at or below the Leidenfrost point. The cooled metal strip can pass through a bridle to increase the tension in the metal strip before the metal strip is optionally lubricated and then recoiled or otherwise further processed.