Continuous casting machine (MNLZ), it is also the installation of continuous steel casting (UNRS) – a metallurgical unit, the introduction of which fundamentally changed the technology of production and subsequent processing of steel. To date, MNLZs operate at metallurgical enterprises that differ in the power and design of the machine, the type of cast workpiece. But in any installation there is a most important functional node – a water -cooled crystallizer. The name itself indicates its purpose: in the crystallizer there is an initial process of hardening the ingot. Imagine the process: the liquid steel of a continuous stream enters the form, where its first portion hardens and immediately, by the movement of a special tick, a new incoming metal is “stretched” behind it and thus increasing the ingot, the length of which is limited only by the dimensions of the reception equipment. During the time in the crystallizer, the surface of the ingot freezes in the form of a sufficiently dense crust, leaving the molten metal inside.
What is required for the normal functioning of the crystallizer? First of all: the height, thermal and resistant to thermal deformation material of the cooling system, providing at the output the formation of a sufficiently hardened workpiece.
Its height is usually from 500 mm for small square blanks to 1,500 mm. for larger square, round, rectangular ingots. The material for the manufacture of the walls of the crystallizer is copper and heat -resistant heat -resistant steel. There are also made exclusively from a solid copper block with a wall thickness of 150-175 mm. and holes for cooling water. But prefabricated devices consisting of copper (up to 20mm thick) and steel plates are more common, between which cooling water is passed. Water consumption depends mainly reaches 280 – 300 m3/h and depends on the structure of the crystallizer and the cross section of the workpiece. To ensure uniform promotion of the metal and prevent billet ruptures, the system is equipped with a swing mechanism (reciprocating movement) of a crystallizer with an amplitude of up to 40 mm, and a frequency of 10 cycles per minute and above. Movement parameters are synchronized with the operation of the pulling tick. The wear resistance of this device is mainly determined by the operational resistance of copper walls and joints between them, which largely depends on the technology of production and quality of maintenance at the enterprise of ferrous metallurgy.
In the production of copper crystallizers or before starting their operation, a protective coating is applied to their inner surface, and during operation the walls are covered with grease. Lubricant can serve as paraffin, burdock and rapeseed oil, etc. To restore worn copper plates, mechanical processing (shotgun cleaning or renewal) with the subsequent application of coatings is used.
The use of continuous steel casting, in countries where metallurgy is quite developed, is about 95 %, but in Russia only 50 % of products are poured into MNLZ.