Strip flotation furnace for the heat treatment of strips

Overview

The Strip flotation furnace for the heat treatment of strips performs continuous horizontal heat treatment of aluminium strips. Both the furnace and the air cooling sections operate on the strip flotation principle, with the running strip supported on an air cushion during heating, cooling and drying. The OTTO JUNKER nozzle system provides high heat input and non-contact transport, and patented centering nozzles ensure stable strip movement even at low strip tension. The system’s efficient heat transfer supports high throughput rates with minimal line length. Cooling is provided downstream of the furnace by the patented HiPreQ® quench, which allows precisely adjustable cooling rates depending on strip thickness and alloy; a mist quench function covers cooling rates between water and air cooling to achieve low-deformation cooling of thin strips. The furnace is normally integrated into a strip treatment line and can be tailored in arrangement and concept to space, layout, take-over and hand-over points and control system integration. Lateral recirculating fans allow installation without space requirements above or below the furnace platform. Heating can be by gas or electricity, with electrical heating offering the opportunity for CO2-free operation and gas heating using a combination of self-recuperating high velocity burners and cold air burners. Strong air recirculation provides high heating rates and homogeneous temperature distribution without local overheating while generating the supporting air cushion, and a patent-pending flow system avoids undesired pre-cooling before entry into the quench for alloys with long soaking times. Automation and process control include schematic visualization, continuous recording of process data for quality monitoring and the possibility of integration into higher-level IT systems (Level 3). An integrated process model (digital twin) calculates strip temperature in real time to optimize heat input, reduce heating-up time by utilizing temperature overshoot and improve power control and process repeatability; OTTO JUNKER can supply and retrofit this model with the required hardware and software. On-site services include supervision of installation, commissioning and delegation of installation personnel with tools and hoisting gear. Technology Centre test facilities are available for heating, cooling, flow and thermal investigations and can be adjusted to specific test questions. Strip width: max. 2,350 mm; Strip thickness: 0.6 - 7 mm; Material: aluminium strip in 2xxx, 5xxx, 6xxx, 7xxx alloys. Designed for continuous horizontal heat treatment of aluminium strips, the furnace supports non-contact annealing with almost zero strip tension and reproducible, continuous operation. The HiPreQ® quench enables precise, adjustable cooling rates to match strip thickness and alloy, including a mist quench mode for cooling rates between water and air to minimize deformation of thin strips. The system is intended for integration into complete strip treatment lines (including an optionally supplied pre-aging flotation furnace upstream of the recoiler), and its lateral fan arrangement permits installation above horizontal strip storage without requiring space above or below the furnace platform. The Technology Centre provides test facilities for process observations and flow and thermal investigations on heating and cooling when such investigations are required.