The continuous casting process schematized in the plant 10 in FIG. 1 is an industrial production process of the melting type, in which the molten metal arriving from a furnace or a convertor is poured by means of a ladle 12 into a distribution container, called tundish 14, which has two tasks: the first is to block the slag that has formed during the melting process, the second is to regularize the flow of steel intended for subsequent processes. From the tundish 14 the metal passes due to gravitational force through a cylindrical snorkel 16 made of ceramic material to a permanent mold with an open bottom called mold 18. It can have different sections and sizes, depending on whether billets, blooms or slabs are to be produced. It is generally built of copper and cooled externally by water; this allows the alloy to solidify in the most external part of its section, while remaining liquid internally. Its continuous vertical oscillation also prevents the metal from adhering to the walls. The solidified skin that is formed provides sufficient stability to the cast piece to allow it to descend through a curved path 20 with a diameter of some meters, during which the forced cooling continues by means of sprays of water directly on its surface. Once it has reached the horizontal position, the metal is almost completely solidified and is ready to be sheared by means of an oxyacetylene blow torch or shears, into pieces of a suitable length to be sent to subsequent processes or for direct sale. Usually a continuous casting machine has several casting lines, each equipped with an ingot mold, a cooling path and oxygen shearing and fed by a single tundish.
In particular, in the passage of the molten steel through the ingot mold 18, the alloy must be kept constantly under a layer of casting powders 15, a granular mixture consisting mainly of carbon and silicon oxides, aluminum, sodium and calcium. The casting powders have many functions:                they lubricate the interstice that forms between the copper crystallizer and the first solidified skin consequent to the contraction of the steel due to cooling, thus reducing friction;        they prevent contact between the meniscus and the atmosphere, preventing oxidations of the alloy;        they reduce the upward heat dispersions, thus preventing the formation of surface solidifications.        
On ingot molds with a large section, the distribution of the powders is still made manually, obliging operators to work in a dangerous and hostile environment due to the possibility of the snorkel breaking, the liquid steel overflowing from the mold, of sprays of material that infiltrates between the slide gates 19 of the ladle, and also due to the high temperatures and environmental humidity found. Furthermore, the use of human operators does not allow a homogeneous and rapid distribution of the powders in the only zones where this is actually necessary.
Document EP-A-0.371.482 describes a continuous casting method that monitors the conditions of the surface of the molten bath in an ingot mold, in particular surface anomalies such as lumps and lack of powders or the formation of crust.
Document BE-A-1.016.114 describes an automatic control method to control the lubricant powder in a mold for continuous casting.
Document DE-C-3224599 describes a tool for the distribution of lubricant powder on a mold for continuous casting. The tool functions as a dosing device since it is provided with separation walls that define compartments for the powder having different depths and therefore a different capacity for containing the powder. The geometry is coordinated with the different areas of the mold on which the different quantities of powder are to be distributed, typically depending on the heat profile of the zones of the mold. The tool can be rotated around a longitudinal axis, so as to pour the different quantities of powder simultaneously onto the various zones of the mold to be serviced. Consequently, the tool cannot be used to cover the whole surface depending on needs, performing different types of powder distribution, such as various types of throwing or pouring, in a sequential manner in different zones of the mold that require variable approach dynamics. Furthermore, it cannot conserve, for each covering movement to be performed subsequently, an adequate and desired quantity of powder.
One purpose of the present invention is to achieve a robotized and automatic system to manage the distribution of the powders in a mold which increases safety for the operators, who are no longer obliged to work in high-risk places, which improves the quality of the product, keeping the free surface of the steel constantly under a layer of powder with a uniform thickness and as thin as possible, and allows to reduce the consumption of the casting powder.
Another purpose is to adopt a suitable viewing system to detect the zones to be serviced and a robot manipulator for the operations to distribute the powders.
Another purpose is to optimize the suitable distribution techniques of the casting powders.
Another purpose is to develop viewing algorithms able to identify quickly the zones of the bath where it is necessary to deliver material, called exposures.
Another purpose is to allow interaction with each other of the systems adopted, allowing to calibrate the viewing system, to detect the zones of the meniscus exposed to the air, to communicate the data to the robot controller, to load the casting powder and subsequently distribute it.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
USPTO Backgrounds
USPTO Backgrounds