Research of process of cooling and crystallization of cast-iron grinding bodies of ellipsoid form on a konveyerno-kokilnoy
machine
The process of growing of raw material and materials shallow is widely used in different processing industries of industry.
Technology of crushing and growing of ores and other hard materials shallow - one of most scale and energoemkih, vsledstvii
this expensive. Grinding bodies are the basic type of materials, which are used for growing of iron-stone and ores of the
coloured metals, cement clinker shallow, uglya, build materials. Annual consumption of grinding bodies in Ukraine - more
than 35Î thousand of tons. The stake of grinding bodies from total expenses on growing of raw material shallow arrives
at 30%.
For the thin growing of abrasive and difficultly ground materials shallow drum (ball and bar) mills are used. In them
as grinding bodies for apply bars, balls, cylinders, paraboloids and ellipsoids. At the Makeevskom casting plant are developed
and made the cast-iron grinding bodies of ellipsoid form. The grinding bodies of ellipsoid form provide more effective process
of growing of raw material shallow, conditioned by the greater total area of surface of ellipsoids on comparison with balls
at the same mass, possess promoted wearproof related to more high by a volume hardness of cast-iron MT, allow to lower the
expense of grinding bodies on the ton of the ground down material and lower expenditures at making. For grinding bodies working
in the conditions of shock-abrasive, wear, the mainly white cast-iron alloyed by a chrome from 2 to 37% is applied. Table
of contents of carbon to 3 - 3,5%.
Duty properties of the cast-iron grinding bodies of ellipsoid form, poured off in opened kokili, rely on chemical composition
temperature of the inundated cast-iron, method of cooling of kokiley, underlying structure of founding, presence of usadochnih
shells and other technological factors.
One of lacks of opened kokiley is the rapid cooling of metal in overhead part of founding due to the radiation of heat
in surrounding one space. On the assignment clauses of heat intensity of cooling of the opened mirror of liquid metal is
proportional to the fourth degree of temperature, and intensity of taking of heat by heat conductivity from founding to
kokilyu is proportional to the first degree of temperature of metal. A wide difference in speeds of cooling results in
a volume, that a hard crust appears on the surface of mirror of metal, while central part of founding remains liquid. It
results in considerable difficulty of taking of gases from the liquid of the good poured off in an atmosphere and is instrumental
in formation of gas shells and usadochnoy friability into founding.
In addition, at the low temperatures (below 13000C) of the inundated cast-iron symmetry of grinding body is violated, I.e.
increase of angle of slope of foundation in relation to a longitudinal axis due to more early hardening of the opened surface
of metal on the sloping area of machine.
With the purpose of improvement of terms of gazovideleniya from a liquid metal in the process of crystallization a new
structural element is offered - mirror reflector which provides the management by the process of consolidation and crystallization
of founding in kokile, reduction of quantity of emptinesses and removal of defect of foundation of founding, that results
in the rise of their eksplutatsionnih descriptions (udarostoykost, wearproof and stability of form). Mirror reflector of
semicylindrical form with a well reflecting internal surface.
At passing of kokiley speed of cooling of the opened surface of liquid metal being found in the cells of kokilya due to
the reflection of thermal stream from the concave mirror surface of reflector back onto all overhead part of opened kokilya
with located in him cells with a liquid metal diminishes under a mirror reflector. The increase of duration of stay of
mirror of metal in the liquid state is instrumental in more complete deleting of gases from all volume of metal
and removal of defect of foundation of founding.
For determination of optimum sizes of mirror reflector computations of speed of consolidation of grinding bodies during setting
of mirror reflector above locomotive kokilyami on leaving on a horizontal area with the use of mathematical model of process
of crystallization of cast-iron grinding bodies of ellipsoid form were produced.Computations were executed for the grinding body of the type T9 with the diameter of foundation 60 mm at the initial temperature
of the inundated cast-iron 1400 0C. The best results are got at length of mirror reflector of making 0,20-0,25 lengths of horizontal part of conveyer. A reflector
is done mobile. His position on a conveyer relies on the temperature of the inundated cast-iron. This system is automated.
Because of only this eksplutatsionnie descriptions of founding (grinding bodies) due to the receipt of more dense
structure of metal and removal of defect of foundation of founding rise, the commodity type of cast-iron grinding bodies
of ellipsoid form gets better.