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EN
The paper presents the results of preliminary research on the application of olivine moulding sands with hydrated sodium silicate containing 1.5 % wt. of binder to perform ecological casting cores in hot-box technology using a semi-automatic core shooter. The following parameters were used in the process of core shooting: initial shot pressure of 6 bar, shot time 3 s, the temperature of the core-box: 200, 250 and 300°C and the core curing time: 30, 60, 90, 120 and 150 s. The matrix of the moulding mixture was olivine sand, and the binder of the sandmix was commercial, unmodified hydrated sodium silicate with molar module SiO2/Na2O of 2.5. In one shot of the automatic core-shooter were formed three longitudinal specimens (cores) with a dimensions 22.2×22.2×180 mm. The samples obtained in this way were subjected to the assessment of the influence of the shooting parameters, i.e. shooting time, temperature and curing time in core-box, using the following criteria: core box fill rate, mechanical strength to bending RgU, apparent density, compaction degree and susceptibility to friability of sand grains after hardening. The results of trials on the use of olivine moulding sands with hydrated sodium silicate (olivine SSBS) in the process of core shooting made it possible to determine the conditions for further research on the improvement of inorganic hot-box process technology aimed at: reduction of the heating temperature and the curing time. It was found that correlation between the parameters of the shooting process and the bending strength of olivine moulding sands with sodium silicate is observed.
EN
The results of model investigations of the influence of the blowing process selected parameters on the distribution of the compaction of the core made by the blowing method, are presented in the hereby paper. These parameters were: shooting pressure, shooting hole diameter, amount and distribution of deaerating holes. Investigations were performed using the horizontal core box of the cuboidal cavity and the same core box into which inner inserts were introduced. These inserts were dividing the primary volume into three sectors differing in their direction, introduction conditions and the character of the core sand flow. As the compaction measure the apparent sand density was assumed. The density was determined in five measuring points in case of uniform cores, and in three measuring points in case of cores obtained in the core box with three separated sectors. The apparent density of the compacted core sand in the core box cavity was determined on the basis of the measurements of masses and volumes of samples cut-out from the determined core places by means of the measuring probe. Investigations were performed at three values of the working pressure equal 0.4, 0.5 and 0.6MPa for two diameters of the shooting hole: 10 and 20 mm. During tests the core box deaeration, controlled by an activisation of the determined number of deaerating vents placed in the core box, was also subjected to changes.
EN
Resin migration in a core can occur during the core production process performed by blowing methods in which the core sand is transported into the core box as a two-phase sand-air flux characterized by various working parameters (working pressure, shooting time, volumetric concentration). This migration is the result of the resin being blown off from the matrix grain surfaces by compressed air. The methodology of the investigation of this effect developed at AGH University of Science and Technology is presented in this paper. The results of the resin migration tests obtained for cores made with cold-box technology at various working parameters of the shooting process are also shown.
EN
The paper presents the results of preliminary research on the use of silica sands with hydrated sodium silicate 1.5% wt. of binder for the performance of eco-friendly casting cores in hot-box technology. To evaluate the feasibility of high quality casting cores performed by the use of this method, the tests were made with the use of a semiautomatic core shooter using the following operating parameters: initial shooting pressure of 6 bar, shot time 4 s and 2 s, core-box temperature 200, 250 and 300 °C and core heating time 30, 60, 90 and 150 s. Matrixes of the moulding sands were two types of high-silica sand: fine and medium. Moulding sand binder was a commercial, unmodified hydrated sodium silicate having a molar module SiO2/Na2O of 2.5. In one shot of a core-shooter were made three longitudinal samples (cores) with a total volume of about 2.8 dm3. The samples thus obtained were subjected to an assessment of the effect of shooting parameters, i.e. shooting time, temperature and heating time, using the criteria: core-box fill rate, bending strength (RgU), apparent density and surface quality after hardening. The results of the trials on the use of sodium silicate moluding sands made it possible to further refine the conditions of next research into the improvement of inorganic warm-box/hot-box technology aimed at: reduction of heating temperature and shot time. It was found that the performance of the cores depends on the efficiency of the venting system, shooting time, filling level of a shooting chamber and grains of the silica matrix used.
EN
The article presents conclusions drawn from analysis and research conducted in domestic foundries concerning currently used core shop equipment as well as determination of their needs within this area. Works within mechanization of core making process, conducted together by Ferro-Masz company, Łódź and Faculty of Foundry Engineering of AGH, Kraków, included analysis of available technologies, applied materials and requirements for mechanization of core making process with the use of blowing methods. Commercial offers from manufacturers of core making systems has been discussed together with presentation of own solution of universal core shooting/blowing machine, ensuring production of high-quality cores.
EN
The study investigates the key aspects involved in the flow of the air-sand stream from the machine chamber and in the core box filling in the core shooting and core blowing processes. The prevailing tendency to manufacture thin-walled castings with intricate channel structures has become the major determinant of castings quality and production rates. An important parameter of most core sand used in the shooting processes is the ability to eject from the machine chamber and the core-box filling capability. These properties are the key factors determining the feasibility of manufacturing intricate cores and the process efficiency. The research work outlined in this study focuses on establishing the performance criteria of core sand ejection from the machine chamber and of core box filling and sand compaction. The results given below were obtained for several new-generation core sand types, containing organic and inorganic binders, and designed to be used in hot-box, warm box and warm air processes.
PL
W publikacji przedstawiono zagadnienia związane z wypływem strumienia piaskowo-powietrznego z komory nabojowej i zapełnianiem rdzennicy metodami dmuchowymi z wykorzystaniem strzelarek i nadmuchiwarek. Tendencja do konstrukcji odlewów o coraz cieńszych ściankach i skomplikowanych kanałach, sprawia, że produkcja wysokiej jakości rdzeni jest nadal czynnikiem determinujacym jakość oraz wydajność produkcji odlewów. Ważnymi właściwościami ogółu mas rdzeniowych stosowanych w procesach dmuchowych jest ewakuacja masy z komory nabojowej maszyny dmuchowej oraz zdolność do zapełniania i zagęszczania masy w rdzennicy. Właściwości te, decydują często o możliwosci wykonania skomplikowanych rdzeni oraz o efektywności procesu technologicznego. Przedstawione badania dotyczą ustalenia kryteriów oceny ewakuacji masy z komory nabojowej oraz zdolność do wypełniania rdzennicy i zagęszczania kilku nowoczesnych mas formierskich, zarówno organicznych jak i nieorganicznych, pochodzących technologii hot box, warm box, warm air.
EN
The obtained effects of filling the core box cavity and moulding sand compaction in processes of core production by blowing methods (blowing, shooting) depend on several factors. The most important are: geometrical parameters of cavity and complexity of its shape, number, distribution and shape of holes feeding sands as well as the way of deaeration of a technological cavity. Values of individual parameters are selected according to various criteria, but first of all, they should be adjusted to properties of the applied core sand. One of the ways of a preliminary estimation of suitability of a core sand for filling the core box and for compaction by means of blowing methods is the determination of its fluidity and assessment how this parameter is changing when core sand is awaiting to be shot. Another criterion of suitability of core sands for the blowing process is their apparent density obtained at filling the testing core box of a complicated shape (Boenisch test). Various methods developed by several researchers, including the authors, allow to assess the tested property on the basis of special technological tests projecting the process into a laboratory scale. The developed criteria defining a degree or a filling ability factor provide a better possibility of assessing the core sand behaviour during flowing and core box filling, which indicate the value and structure of the obtained compacting decisive - after hardening - for strength and permeability. The mentioned above aspects were analysed - on the basis of authors' own examinations - in the hereby paper.
PL
W artykule przedstawiono badania rozkładu gęstości pozornej rdzeni sporządzonych przez nadmuchiwanie i wstrzeliwanie. Zastosowano trzy rodzaje osnowy w masach sporządzonych zgodnie z wymaganiami fenolowego procesu coldbox Ashlanda. Do oceny jakości realizowanego procesu zastosowano badania gęstości pozornej zagęszczonej masy rdzeniowej metodami tradycyjnymi, jak również za pomocą pomiaru prędkości propagacji fali ultradźwiękowej.
EN
The results of core sand density distribution inside the cores manufactured by blowing and shooting techniques have been presented in the article. Three kinds of silica basis were used in testing core sands prepared according to phenolic Ashland cold-box process. The measurement of core sand apparent density obtained inside core volume identified both by the traditional methods as by the ultrasonic valve velocity propagation have been adopted as a validation factors of process quality.
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