There are two processes for solidifying molten steel and casting it into a solid: one is the ingot mold casting method, and the other is the continuous steel casting method. The latter can directly cast the molten steel smelted in the induction furnace into solid steel such as billet, square billets and round billets, and then supply the billets to various rolling mills to produce steel products of various specifications.
Continuous casting is different from ordinary casting. It does not pour high-temperature molten steel into steel ingot molds one by one, but continuously pours high-temperature molten steel into one or several "living bottoms" (called dummy ingots) with forced water cooling. In the copper mold (called crystallizer) of the head), the molten steel quickly condenses with the "live bottom". After turning over the water and solidifying to a certain thickness, the movable bottom is pulled out from the lower end of the copper mold, so that the billet that has solidified to a certain thickness will be continuously pulled out from the water-cooled crystallizer, and continues to cool in the secondary cooling zone. Spray water to cool. A strand with a liquid core, which solidifies as it goes, until it is completely solidified. After the billet is completely solidified, the billet is cut into billets of a certain size with an oxygen cutting machine or a shearing machine. This new process of directly pouring high-temperature molten steel into billets is called continuous steel casting. Its appearance has fundamentally changed the primary rolling process of steel ingots that has dominated for a century.
The concept of continuous ingot casting of liquid metal was proposed as early as the mid-19th century.
In 1840, Cyrus of the United States obtained a patent for continuous casting of lead pipes. In 1846, Bessemer, the inventor of the converter, used a water-cooled rotary twin-roll caster to produce tin foil, lead plates and glass plates.
In 1872, Davey in England proposed the concept of continuous casting with mobile crystallizer. From 1886 to 1889, the design of the vertical continuous casting machine for vertical pouring was proposed. In 1921, the concept of crystallizer vibration was proposed to make continuous relative motion between the billet and the mold wall.
In 1933, the pioneer of continuous casting, the German Rong Hans, built the first 1700T/month vertical continuous casting machine with vibrating crystallizer. He first succeeded in casting copper and aluminum alloys, making continuous casting of non-ferrous metals available in the 1930s. in production.
In the 1940s, the first experimental continuous casting machine for pouring molten steel was built by Junghans in Germany. At that time, technologies such as vibrating water-cooled crystallizers, submerged nozzles and protective pouring were proposed, which laid the foundation for modern continuous casting machines. . Subsequently, intermediate test continuous casting machines were successively built in the United States, Britain, Austria, Japan and other countries, with a molten steel volume of 150kg~7.5t.
In the 1950s, continuous casting entered the stage of industrial experimentation, and several continuous casting machines were built one after another.
After the 1970s, it was a period of great development for continuous casting. The continuous casting machine has the possibility of cooperating with the large oxygen converter for industrial production. Continuous casting machine and process technology are becoming more and more perfect. Its representative technologies are:
Continuous casting machine can simplify the production process, increase the yield of metal, save energy consumption, and improve labor conditions to realize automation easily. Additionally, due to the fast-cooling speed of continuous casting and controllable and stable casting conditions, the internal structure of the casting billet is uniform, dense and stable in performance.