Automatic control of the physical and mechanical properties of the raw sand‑clay molding mixture in the process of mixture preparation in the new developments of OJSC “BELNIILIT”

OJSC “BELNIILIT” specialists have developed a method and an automatic device for monitoring and managing the quality of raw sand‑clay molding blend, which is based on the integrated control – compaction of the molding blend principles, measurement of humidity and strength in the raw state, measurement of temperature directly in the process of mixture preparation. The equipment is integrated into existing automated mixture preparation complexes manufactured by OJSC “BELNIILIT”, it is possible to install on old design mixers.

Algorithms for controlling the preparation of molding mixtures

The formation of foundry and technological defects in castings is largely influenced by the quality of casting molds, which in most cases is determined by the composition and properties of the molding mixture. To ensure optimal parameters of the molding mixture, automation and optimization of control of technological processes of mixture preparation, algorithms for the functioning of process control systems have been developed. The description of the circuit and methods of control using process control system presented. It was shown that the algorithms provide the calculation of the generalized optimization parameter according to the values of the main physical, mechanical and technological properties of the components of the molding mixture, sequential analysis and search of the optimum by the simplex method of Nelder–Mead with restrictions on several parameters. Subsystems of the process control systems considered, which enable to change quickly the technology according to the criterion of minimum defectiveness. The algorithm for calculating the values of the generalized criterion of the quality of the mixture includes a mathematical model “composition – properties” of the mixture, linking the content of the component of the molding mixture (spent mixture, quartz sand, lignosulfonate, bentonite suspension, water) with the values of physical, mechanical and technological properties (compressive strength in the wet state, rammability, formability, gas permeability, binder content, fluidity, wetness and crumbling). The current values of the quality parameters of the mixture are determined as a result of express analysis in the shop laboratory and by automatic sensors. The proposed algorithm of optimization control of preparation of the molding mixture enables to develop recommendations of technological and organizational nature and to set recipes of the molding mixture that minimize the level of defectiveness of castings. An adapted version of the algorithm has been tested for use in the preparation of various brands of molding and rod mixtures, which indicates its versatility.

KINETICS OF DYNAMIC CHARACTERISTICS OF IMPACT LOADING OF THE MOLDING MIXTURE

This paper presents a material that allows us to quantify the dependence of the main characteristics of the dynamic loading of the molding mixture, and hence the degree of its compaction, on the parameters of the shaking mechanism of the molding machine (the mass of the collision of parts and their rigidity).

STUDY OF THE FORMATION OF THE STRUCTURE OF GRAY CAST IRON BY THE METHOD OF THERMOGRAPHIC ANALYSIS

The work is devoted to the study of the effect of an exothermic carbon-containing additive of a facing layer of a sandy-clay molding mixture on the eutectic transformation of cast iron. For this, the method of thermographic analysis was used and metallographic analysis of the metal under study was carried out. It is shown that the results obtained by thermographic analysis have a correlation with the structure of cast iron. The introduction of a carbon-containing additive into the composition of the facing mixture led to the formation of a favorable structure of the prototype, characteristic of gray cast iron.

INFLUENCE OF MICROSPHERES ON PROPERTIES OF AGGRESSIVE RESISTANT RUBBERS

The aim of the work is to study the effect of hollow corundum, glass and pomegranate ceramic microspheres on the rheometric characteristics of aggressive resistant rubber mixtures and the physicomechanical parameters of their vulcanizates to determine of the content of fillers of this type, which provides an improvement in the priority properties of products and, as a result, an increase in their durability. The objects of research were two rubber mixtures intended for compression molding and injection molding. The compression molding mixture is based on a combination of nitrile butadiene, isoprene and butadiene-α-methyl styrene caoutchoucs with colloidal silicic acids as the main fillers. And the injection molding mixture is based on a combination of synthetic isoprene and butadiene rubbers filled with chalk, P234 carbon black and carbon 100. We used hollow corundum (HMC-L), glass (MS-V), and pomegranate ceramic (MVMD-170) microspheres. The rheometric properties of the rubber compounds were evaluated by the values of the minimum and maximum torques, the duration of the induction period, the time to reach the technological optimum, and the maximum vulcanization rate. When testing vulcanizates, conditional tensile strength, elongation at break, tear resistance, hardness, abrasion and rebound elasticity were determined. Priority indicators were also determined that correlated to the greatest extent with the durability of the products during operation - relative changes in conditional tensile strength and elongation at break, hardness after heat aging in air and standard liquid SZhR-1, change in mass of samples after swelling in industrial oil I-20A and Nefras S-80/120. For a mixture for compression molding, the effect of the type of microspheres introduced at a dosage of 5 parts by mass per 100 parts by mass caoutchoucs, on the properties of unvulcanized mixtures and vulcanizates was studied. It was found that the rubber mixture with glass microspheres is somewhat below in vulcanization activity, and its vulcanizate in terms of abrasion resistance, heat aging, especially in air, is inferior to two mixtures and rubbers with corundum and pomegranate microspheres. In the second mixture, we tested corundum microspheres with a dosage of 3.0 to 7.0 parts by mass per 100 parts by mass of caoutchoucs while reducing by the appropriate amount of carbon black. It was found that with an increase in the dosage of microspheres, a decrease in the vulcanization activity of the mixture, minimum and maximum torques, and also their difference is observed, which indicates a slight decrease in the degree of crosslinking of rubbers. The consequence is an increase in relative lengtheningof the vulcanizates. To the least extent, this effect manifests itself with the introduction of corundum microspheres in a dosage of 3 parts by mass. Thus, the advantage of rubbers with microspheres is reduced abrasion, higher tear resistance while maintaining resistance to the action of physically and chemically aggressive environments at the level of rubbers that do not contain microspheres.

Impact of transportation on foundry coke quality

One of the ways to increase economic efficiency of the foundry is to reduce the product cost by reducing scrap, a significant proportion of which is formed due to 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 the 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 sand-clay layer. 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 takes into account the heat transfer between casting and mold, increase in mold dry layer, and the migration of moisture in layer of the sand-clay mixture. On the basis of mathematical modeling, we have made 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 humidity of 5 % expressed in terms of the average resistance to deformation under an obstruction element 100 mm long. It was established that increase in the above-mentioned factors, at a fixed time, increases the average value of deformation resistance. The quantitative relationship of the released heat with growth of the dry layer of the molding mixture is described. It was noted that dynamics of changes in the average temperature does not always coincide with increase in deformation resistance of the molding mixture.

FOR THE STUDY OF PECULIARITIES OF STRUCTURE FORMATION OF COMPOSITE BINDERS FOR NON-AUTOCLAVED AERATED CONCRETE

the basis of the modern market of cellular concrete is autoclaved gas silicate. At the same time, non-autoclaved aerated concrete is largely a more technological material, allowing the variation of its properties within a wide range, having a potentially wider field of application, less costly in the organization of production, which is of great importance for small and medium-sized businesses. The main problem of non-autoclaved aerated concrete is a higher cost of raw materials compared to silicate, and 20...30% lower strength performance. The proposed solution to this problem is the development of special composite binders with a limited content of clinker and mineral additives of various genetic types, taking into account the peculiarities of the two-stage structure formation of the material – gas porization and the formation of the microstructure of the stone. The article deals with some aspects of the interaction in the system “mineral additive – gypsum – by-products of the gas release reaction” in terms of the effect on the viscosity of the swelling mass and the strength of the stone at different times of hardening. Recommendations are given on the preferred compositions of composite binders and dosages of gypsum in the molding mixture when producing a material with an average density in the range of 500...700 kg/m3.

Porous aggregate development for lightweight concrete

The article presents the results of studies of a porous aggregate and lightweight concrete obtained using liquid glass and man-made materials (glass cullet, magnetite ore dressing waste, substandard rocks). Feasibility of a multicomponent feed mixture for pyroplastic swelling of granules is substantiated. Optimization of raw mix composition provided the possibility of combining various formation mechanisms of porous granules. A set of technological solutions has been developed aimed at improving the conditions of molding and hardening of raw granules. A method for preparing a raw material mass is proposed that minimizes structural defects of porous granules. Possibility of capacity reaction of a raw mixture due to mechanical activation of solid components and introduction of sodium additives is proved. Technological conditions for low-temperature expansion of a multicomponent mixture and production of porous granules with a density of not more than 300 kg/m3 are determined. The formula of molding mixture for obtaining lightweight concrete using a porous aggregate is proposed. The use of liquid glass as a binder in a concrete mixture is preferred. The temperature of concrete hardening is recommended. The technology of porous concrete developed implements multifunctional properties of liquid glass, provides the use of technogenic materials, saving of energy resources.

EVALUASI SIFAT FISIKA KIMIA DAN TANGGAP RASA TABLET HISAP DEKOKTA DAUN MENGKUDU (Morinda citrifolia L.) DENGAN VARIASI PEMANIS

ABSTRACTNoni leaf (Morinda citrofolia L.) has antioxidant compounds that can inhibit and counteract free radicals. Decocta Noni leaf to make more practice preparation of lozenges. This study aims to evaluate the physical chemical characteristics and taste response of lozenges with variations of sweeteners to cover the bitter taste of Noni leaves. Decocta mengkudu leaf is obtained by boiling at 90C for 30 minutes. Suction tablets made 9 formulas based on variations of sweeterners sucrose-water sweetener, sorbitol-sucrose-sugarcane water, and aspartame-sucrose-sugarcane water. The suction tablet is made by molding mixture method. Evaluation of physical chemical characteristics including hardness and solubility were analyzed statistically using one-way ANOVA with 95% confidence level, followed by tukey test, weight uniformity, taste response and thin layer chromatography analyzed descriptively. The results of the study was showed that influenced the increase in hardness and dissolution time and the results of the requirements physical lozenges The results of the TLC test of lozenges and decocytes showed an RF value close to Quercetin. The taste response test results showed formula I with variations of sugarcane-sucrose water sweetener, formula III with variations in sorbitol-sucrose-sugarcane-water sweetener and sugarcane water aspartame-sucrose was the most preferred by respondents of 85% - 95%.Keywords: leaf of morinda citrifolia l., lozenges, sorbitol, aspartame, sucrose, sugarcane water