Browsing by Subject "hot-distortion"

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Access status: Open Access ,
Impact of density degree and grade of inorganic binder on behavior of molding sand at high temperature
(AGH University of Science and Technology Press, 2017) Stachowicz, Mateusz; Paduchowicz, Patrycja; Granat, Kazimierz
This paper discusses the impact of high temperatures (up to 900°C) on molding and core sand with inorganic binders selected from among the group of unmodified grades of hydrated sodium silicate (water-glass). Molding sands with medium quartz sand were made under laboratory conditions and compacted at the different energy inputs necessary for obtaining various apparent densities (?0). Due to the different composition and apparent density of molding mixtures hardened via microwaves at a frequency of 2.45 GHz, it was possible to assess their deformation (L) at a high temperature above the binder's eutectic temperature. For this purpose, an apparatus for hot distortion tests was used whose construction and equipment allows us to measure the thermoplastic deformations in molding sand in many aspects; i.e., in its time of annealing. The article proposes new possibilities of interpreting the hot distortion phenomena in comparative studies of molding materials and mixtures. The application of this new measurement method revealed the differences between molding mixtures made with five inorganic binders with a molar module ranging from 2.0 to 3.4 and apparent density ranging from 1.34 to 1.57 g/cm$^{3}$. It was established that distortions under the influence of high temperatures last the longest in molding sand with a binder with the highest molar module (3.4). Research also revealed that the density of molding sand is significant for increasing/decreasing the rate of thermoplastic deformations following the heating of samples only if the molding sand includes binders with a molar module of between 3.0 to 3.4. For molding sand with binders with molar modules from 2.0 to 2.5, it was established that this is excessively susceptible to thermoplastic deformation.
Access status: Open Access ,
Measurement of molding sand elasticity
(AGH University of Science and Technology Press, 2018) Major-Gabryś, Katarzyna; Grabarczyk, Aleksandra; Dobosz, Stanisław Marian; Jakubski, Jarosław; Morek, Jan; Beňo, Jaroslav
The progressive mechanization and automation of industrial equipment is the driving force of progress, not only in the field of production but also in the measuring and control equipment. In mold production, the automation of processes such as forming molds and cores along with their assembly has led to increases in serial production, reductions in defects, and the shortening of molding times, among others. Thanks to automation in mold and core departments and the use of all sorts of manipulators, mold production in foundries has gained momentum. Unfortunately, in addition to the mentioned advantages, there are also new challenges as to the quality and properties of the molding and core sands used in highly automated foundries.This article presents recent research on molding sand elasticity. The topic was introduced as an attempt to answer the new needs of highly mechanized foundries. The article discusses a new method of measuring the resistance of molding materials to undergoing mechanical deformation (molding sand elasticity), with an additional analysis of the bending strengths of the tested samples. Precise measurements, test sample preparation, and interpretation of the received results are presented in the article.