SU660776A1 - Method of making castings - Google Patents

Description

one

The invention relates to foundry, in particular to the casting of mill rolls.

A known method of making castings involves pouring a metal into a linear form, purging it after forming a crystallized crust with gaseous reagents with the addition of active ingredients and then cooling it 1.

However, this method does not allow the production of rolling rolls with a wear-resistant working layer of adjustable thickness and with a viscous core of the required structure and high quality.

The purpose of the invention is to improve the quality and structure of the internal axial zones of the casting.

This goal is achieved by the fact that the blowdown is carried out after the formation of a crystallized crust with a thickness of 0.005-0.25 in thickness of the casting with simultaneous forced cooling of the crystallized crust at a rate of 0.5-50 ° C / min.

Purging melts from below with gaseous reagents with additives of active components is currently a widespread technological measure contributing to the improvement of the physicochemical properties of the metal (refining, modifying, oxidizing iron to steel, etc.). In the proposed method, after solidifying a certain volume of the initial melt, it is purged with gaseous reagents (natural, gas, air, oxygen, inert gases with the addition of active components (powdered Mg, Ca, Y, Li, Ce, Te, FeSi, Co, Ti , A1. Cr, Fe, C, Na, Si).

When purging the remaining part of the melt, a change in its physicochemical properties occurs. By intensive heat removal (water, air, vapor-air, evaporative, and other types of cooling) from the surface of the hardened outer layer or any other conditioned casting site, multi-layering or differentiated structures of the internal zones of the casting are achieved.

Claims (1)

After reducing the intensity of the purge and completely stopping it, the casting is completely solidified. The method allows to obtain bimetallic products with an outer layer of bleached cast iron, steel and other alloys, and the inner zones from raw alloys refined, modified, alloyed with various components and also from alloys obtained by oxidation processes, for example, oxidation of cast iron to steel . The melt can be purged through porous plugs, a vent, or a vent. It is also necessary to take measures to prevent solidification of the melt at the outlet openings of the gas supply until the moment of switching on, which is achieved, in particular, by using weakly heat-conducting mixtures in the vent installation area or by special ventilation arrangement. In order to improve the quality and structure of the internal zones of the casting, the molten molten after hardening at the casting site (barrel of the cast mill roll) of the outer layer equal to 0, 25 of the casting thickness was blown from the bottom with gaseous reagents with added active components with overpressure of the gaseous reagent over a column of liquid metal of 0.005-4 ati with cooling, nanometer, air, the surface of the hardened outer layer of the casting at a speed of 0.5-50 ° C / min. Below is an example of a specific embodiment of the casting of a mill roll with a barrel size of 250x500 mm. The manufacture of mold elements for casting is carried out by conventional foundry manufacturing methods. An L-shaped tube made of quartz glass with an inner diameter of 5 mm and with an outer thermal insulation of the long arm of a thin-walled (0.3 mm) steel tube and two layers of asbestos cord are placed in the form of the lower neck. The short end of the L-shaped tube with a knee length of 20 mm is fixed on the axis in the direction of the bottom of the form, at a distance of 90 mm from the lower end (bottom) of the form. Such a pipe (ventilation) installation scheme prevents the premature freezing of its outlet opening due to the advancement of the solidification front from the walls of the mold, as well as from premature filling of the opening of the tube with molten material. The tube inlet is closed with a stopper made of porous coke. After completion of pouring and holding the melt in the mold for 80-90 s to harden the outer layer with a thickness of mm, i.e. 0.006-0.0068, of the diameter of the roll barrel, compressed air under pressure is transferred to the supply system through the pressure sensor atm, which exceeds the specific pressure of the liquid metal column at the tube level by 0.5 atm. The coke plug is blown out of the tube orifice and air is blown through the melt bed for 7 minutes. Accelerated cooling of the surface layer of the roll is provided by blowing air through the gap between the casting and the chill mold for 1.5-15 minutes. To prevent the metal from leaving the mold through the supply tube (in case of air leakage from the system), a thick-walled steel tube is installed behind the quartz tube, which acts as a cooler. Claim manufacturing method, including pouring a metal into a casting mold, washing it after forming a crystallized crust with gaseous reagents with the addition of active components and subsequent cooling, characterized in that, in order to improve the quality and structure of the inner axial zones of the casting, blowing t after the formation of a crystallized crust with a thickness of 0.005-, 25 thickness of the molding with simultaneous forced cooling of the crystallized crust at a rate of 0.5-50 ° C / min. Sources of information taken into account during the examination 1. Patent of Germany No. 2040504, cl. 31/27/20, 1973.