SU977103A1 - Two-layer ingot mould for casting ingots - Google Patents

Description

(54) TWO-LAYER CASTING DEPOSIT

one

The invention relates to metallurgy, namely to casting molds for steel.

Known molds for casting steel, made of cast iron 1.

For molds made of cast iron, the presence of concentration stresses on graphite inclusions, deep oxidation of the internal zones of cast iron, and low mechanical properties limiting the stability of the molds are typical.

Closest to the proposed technical essence and the achieved result are two-layer molds (steel-cast iron) 2.

Steel, in contrast to cast iron, has a much greater resistance to the formation of high and cracks. The peculiarity of the steel is its lower viscosity, i.e. increased tendency to stresses leading to distortion.

Significant temperature gradient in the cross section of the mold, increasing due to the limited thickness of the steel layer, the presence of two interfaces and the associated additional temperature difference, the difference in the coefficients of linear TILES

This expansion leads to the occurrence of significant thermal stresses during the operation of two-layer molds.

Due to the fact that the well-known statement does not provide for measures to protect them.

from stresses, this leads to their warping

or to cracks in the body, which reduces

durability of molds during operation.

The purpose of the invention is to increase the operational efficiency of molds.

This goal is achieved by the fact that in a two-layer mold for casting ingots containing an outer cast-iron body and an inner steel insert, protrusions are made along the entire length of the axis of symmetry on the side surfaces of the steel insert, and corresponding slots on the inner surfaces of the cast-iron body, at the same time, the steel insert is installed in a cast-iron casing with a gap of 205–0.01 half the length of the adjacent wall of the insert.

FIG. 1 shows the mold, vertical section; in fig. 2 the same cross section.

The mold contains a steel insert 1, a cast iron body 2, a gap 3 is formed between the body 2 and the insert 1, protrusions 4 are made on the side surface of the insert 1, and corresponding slots 5 are on the side surfaces of the body 1, the insert 1 is held in the cast iron body 2 pins 6.

If the gap is less than 0.005, then the difference in thermal expansion of the insert 1 and the housing 2 is larger than the gap 3, and the uncompensated thermal expansion causes the formation of contact thermal stresses that reduce the durability of the mold. The relative thickness of the gap 3, greater than 0.010, also exceeds the difference in thermal expansion of the insert 1 and the housing 2, the remaining gap 3 reduces the heat sink from the ingot and also creates the possibility of warping the insert 1.

With a relative gap width of 0.005-0.010, the expansion of the steel insert 1 is limited to the cast-iron casing 2, thereby eliminating the buckling of the insert 1.

The presence of grooves 5 and protrusions 4 with side faces on the side surfaces prevents deformation localization during heating and cooling of the mold during operation. The maximum possible deformation is not determined by the total perimeter of the insert 1, but only by separate sections delimited by adjacent grooves 5. Running the side surfaces of the grooves 5 in the direction of normal shrinkage eliminates the occurrence of deformations on these surfaces when moving during warming up and stroping the insert 1. steel insert in cast iron housing at the time of ingot extraction.

Example. In the manufacture of a mold on neutral sections (midpoints) of faces, depressions 5 are made, the side surfaces of which are made in the direction of normal shrinkage (i.e., towards the casting axis). As a result of cooling the cast steel insert 1, it shrinks and a gap 3 is formed between the insert 1 and the housing 2. The preheating of the housing 2, as well as its heating during the heat rejection, increases the size from which the shrinkage begins, thereby ensuring , taking into account the slowing down of shrinkage of the insert 1 by the rod, the size of the gap 3

between the insert 1 and the housing 2 in the range of 0.005-0.010.

Thus, in the process of manufacturing the mold, the size of the gap 3 between the body 2 and the insert 1 is regulated by shrinking the insert 1.

During the operation of the mold during the solidification of the ingot, the insert 1 and the housing 2 are heated, and the temperature of the insert 1 exceeds the temperature of the case 2. The heat transfer studies carried out through a two-layer wall showed that the difference in average temperatures of the insert 1 and the case 2 is 400-800 ° C. Under these conditions, the gap 3 is 0.005-0.010 half the length of the adjacent wall of the insert, compensating for the difference in thermal expansion of the insert 1 and the housing 2.

Thus, in the proposed mold, protection against the formation of a grid of heat and warp is provided, an increase in its durability is achieved.

The manufacture of the proposed molds is possible in modern specialized workshops for the production of molds from cast iron of the first heat with the production of steel in oxygen converters. The durability of the proposed molds is 5-6 times higher than the known industrial designs.

The economic effect of using the maximum volume of the proposed molds is 360 thousand rubles.

Claims (2)

1.Efimov V.A. Casting and crystallization of steel. M., “Metallurgists, 1976, p. 451-453. 2. "Foundry, 1978, № 8, p. 31-32.