Investigation of closed cavity conditions in the bottom of cast rolls СПХН-60

Abstract

The paper investigates the possibility of preventing the occurrence of closed-type shrinkage shells in the lower necks of СПХН-60 iron rolling rolls by changing the thermophysical and dimensional parameters of the elements of the combined foundry mold, which is currently used in foundries. The research was carried out based on the results of thermography of real rolls of СПХН-60, adaptation of the obtained data and computer modeling of the process of hardening of cast iron rolls in the combined casting-sand mold, as well as the first developed parametric criterion of sequential hardening in the system of the lower neck of the roll and its barrel. The regularities of the complex influence of the diameters of the barrel and the lower necks of the rolls, the sizes and thermophysical parameters of the materials of the combined form on the sequence of solidification of these casting elements have been established. The obtained data indicate that increasing the level of thermophysical properties of the molding mixture for the lower neck of the roll within the limits of the use of currently known refractory non-metallic materials does not prevent the occurrence of a shrinkage shell in the lower neck of the rolls of СПХН-60 execution. Increasing the level of the heat-accumulating capacity of the forming mixture for the lower neck of the roll to 10000 Ws 0,5 /(m²С) will prevent the occurrence of a shrinkage shell in the lower neck of the rolls of СПХН-60 performance, but it is not expedient due to the appearance of a layer of bleached iron in the lower neck, which is unacceptable for any rolling mill. To solve this problem, it is recommended for СПХН-60 rolls to use shielding of the roll combined form at a certain moment of solidification of the melt in the barrel. Рurposeof the work is to investigate the possibility of preventing the occurrence of closed-type shrinkage shells in the lower necks of rolling rolls due to changes in the thermophysical parameters of their forming mixtures. Methodology.The work uses the method of thermography and computer modeling using the LVMFlow program. Originality.For the first time, the regularities of the complex influence of thermophysical and dimensional parameters of the elements of the combined foundry mold on the occurrence of a shrinkage shell in the lower neck of the СПХН-60 rolling rolls were established.