Page 33 - Апрель

FOUNDRY PRODUCTION

The essence of the methodology for designing elements of cast parts is based on the
following basic provisions:
● scientifically grounded principles of designing elements of cast parts can be obtained only on the
basis of comprehensive studies of the crystallization process of alloys and structural properties
of cast parts. Taking into account only one of these factors leads either to an overestimation of
the mass of cast parts, or to a decrease in their strength and reliability during operation;
● it is recommended to carry out a comprehensive study of the crystallization process of alloys
and structural properties on model samples, including structural elements of cast parts;
● the quantitative relationship between the design of cast parts, their structure and mechanical
properties is the basis for the design of technological and reliable parts. This relationship should
take into account the composition of the alloy, the specific technology for making castings, the
magnitude and nature of the operating loads during operation.
A design engineer, developing a three-
dimensional model of a cast part from new alloys
for modern technology, transfers a computer
model of a part to a foundry technologist.
The model of the part shows surfaces to be
machined, holes, possible radii of curvature, and
various thickenings. The foundry technologist
determines the position of the model in the
mold, allowances for machining, outlines the
places of installation of risers, gating systems,
molding sands. Then computer modeling of the
casting manufacturing technology is carried
out: calculations of gating systems and metal
supply points; calculations of profits and places of their installation; possible defects and their
significance for the characteristics of strength, density and reliability of the finished part.
When developing a computer model of the design of a part, and then the casting technology
of its manufacture, it is necessary to take into account not only the chemical composition of the
alloy, its technological properties, but also the characteristic features of its crystallization and
solidification, the width of the solid-liquid zone during solidification. For example, for ductile
cast iron with spheroidal graphite - the amount of pre-shrinkage expansion, the rate of lowering
of the level of liquid metal in the head and the nature of the location of shrinkage porosity. To
solve these problems, it is necessary to take into account the thermophysical properties of the
molding mixture and the density of the mold packing, fluctuations in the pouring temperature
of the alloy and other factors affecting the quality of the casting as a whole. In this regard, the
approaches to solving the problems of manufacturing large iron and steel castings, namely, the
installation of risers and metal supply points, given in the works of Golod V.M. and Denisov V.A.
[1], Desnitsky V.V. [2,3], and others.

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