Abstract

One of the ways to increase economic efficiency of the foundry is to reduce the production cost by reducing scrap, a significant proportion of which is formed due to the formation of hot and cold cracks during solidification and cooling in the casting-mold system. The formation of cracks occurs due to the force interaction of casting with mold. Currently, a number of approaches are used to determine the value of stress state in the casting material and, accordingly, to determine the value of force interaction. The paper considers the developed estimation of stress-strain state of a casting-mold system, which is determined by deformation resistance of the molding mixture. Change in deformation resistance of the molding mixture is complex due to the multi-factor nature of resulting stresses interaction with thermal and component composition of the layer of a sand-clay mixture. We have studied the influence of geometric parameters and thermophysical properties of the casting on deformation resistance of the molding mixture. A mathematical model was developed that considers the following: heat transfer between casting and mold, increase in mold dry layer, and moisture migration in layer of the sand-clay mixture. On the basis of mathematical modeling, we have performed a quantitative analysis of the influence of thermophysical properties of casting (thermal conductivity, volumetric heat capacity, heat of crystallization, geometric parameters) on ductility of raw sand-clay mold with a moisture of 5% expressed in terms of the average resistance to deformation under an obstruction element 100 mm long. It has been established that an increase in the above-mentioned factors at a fixed instant of time increases the average value of deformation resistance. The quantitative relationship is found between the released heat and the growth of the dry layer of the molding mixture. It has been noted that dynamics of changes in the average temperature does not always coincide with the increase in deformation resistance of a molding mixture.

中文翻译：

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铸件几何和热物理性质影响下生砂模的延性变化

摘要

提高铸造厂经济效率的方法之一是通过减少废料来降低生产成本，而废料的很大一部分是由于铸模系统中凝固和冷却过程中形成的热裂纹和冷裂纹而形成的。裂纹的形成是由于铸件与模具之间的力相互作用而产生的。当前，许多方法用于确定铸造材料中的应力状态的值，并因此确定力相互作用的值。本文考虑了已开发的铸模系​​统应力-应变状态的估计，该估计是由模塑料的抗变形性决定的。由于所得应力与砂-粘土混合物层的热和组分组成相互作用的多因素性质，因此模塑料的抗变形性的变化是复杂的。我们研究了铸件的几何参数和热物理性质对混合料抗变形性的影响。建立了一个数学模型，该模型考虑了以下内容：铸模和铸模之间的传热，铸模干层的增加以及砂土混合物层中的水分迁移。在数学建模的基础上，我们对铸件的热物理性质（导热系数，体积热容，结晶热，几何参数）对水分为5％的生砂模子的延展性表示为在100毫米长的障碍物下的平均抗变形能力。已经确定的是，在固定的时刻增加上述因素会增加抗变形性的平均值。在释放的热量和模塑混合物干层的生长之间发现定量关系。已经注意到，平均温度变化的动力学并不总是与模塑料的抗变形性的增加相一致。在释放的热量和模塑混合物干层的生长之间发现定量关系。已经注意到，平均温度变化的动力学并不总是与模塑料的抗变形性的增加相一致。在释放的热量和模塑混合物干层的生长之间发现定量关系。已经注意到，平均温度变化的动力学并不总是与模塑料的抗变形性的增加相一致。