Horizontal continuous casting refers to the type of continuous
steel casting in which the molten steel is poured horizontally into
a horizontally placed crystallizer, and the solidification process
of the billet and movement in the caster until it reaches the
horizontal state of the cooling bed. This method can simplify the
process, improve production efficiency, facilitate automation and
improve casting quality.
The crystallizer is a key component of the continuous casting
equipment and its quality is directly related to the continuous
casting technology's effectiveness and economic benefits. Graphite
material has the characteristics of high temperature resistance,
oxidation resistance, chemical resistance, self-lubricating and
excellent thermal conductivity, and is the most ideal material for
making crystallizers. It is generally believed that graphite
crystallizer (also known as continuous casting graphite) has many
advantages compared with metal molds, such as not being eroded by
molten metal, the friction coefficient is low when the casting is
moving, and it is easy to process, and no cold septum is produced
on the casting surface (especially Continuous casting of large flat
copper pieces), as well as the continuous casting surface without
processing. Therefore, XRD graphite has given considerable
attention to the research and production of graphite materials for
continuous casting, continuously improving the structure of
continuous casting graphite and increasing its service life.
Horizontal continuous casting machine use multi-stages, ie copper
sleeves are used in the front section and graphite sleeves are used
in the rear section. The function of the graphite sleeve at the
back of the crystallizer is mainly to act as a lubricant under high
temperature, and it also has the function of secondary cooling of
ordinary casters. The billet first cools and solidifies in the
copper jacket, and after the initial solidified shell is formed, it
enters the graphite sleeves to cool more slowly. Since the graphite
has self-lubricating properties at high temperatures, the length of
the copper sleeve that is easily bonded to the blank shell is very
short, so that the casting resistance of the entire crystallizer
inner sleeve can be ensured to be small. In order to reduce the
effect of air gap on heat transfer, the copper sleeve and the
graphite sleeve have corresponding taper. The heat flux density of
the copper jacket in the front section of the crystallizer is
estimated to be 1.5 to 1.8 MW/m on average, which can reach **3.8
to 4.5 MW/m in the vicinity of the separation ring, and only 0.5
MW/m in the graphite sleeve. The graphite sleeve of the rear
section of the horizontal continuous casting mold is longer, and
the billet is thicker (****5mm) after the casting mold emerges from
the crystallizer, and it is no longer necessary to continue the
spray cooling. The slab thus obtained has a uniform cooling and
good quality.
The choice of graphite sleeve material must be suitable for the
characteristics of the copper alloy produced. The fitting
tolerances of graphite sleeve and water-cooled copper sleeve must
be appropriate, and the appearance roughness should be small. The
high density graphite materials such as XRD Graphites XRD*5 have
good strength, small coefficient of thermal expansion, high wear
resistance and good self-lubricity, and are ideal materials for
making crystallizer graphite sleeves. Graphite sleeve working
surface can also be processed by coating or electroplating, which
can not only improve the surface quality of the slab, but also
prolong the service life of the graphite sleeve.