This article, constituting continuation of the subject discussed in the first part, presents results of the experimental trial of water glass molding sands' curing method modification with application of fluid esters and innovative microwave heating. The research objective was to determine possibilities of microwave application for curing of water glass molding sands prepared with addition of hardening agents sold under the trade name of Mach. After initial chemical curing molding sands, prepared with addition of the above mentioned hardeners, have been heated with microwaves in order to determine their influence on changes of basic technological and strength parameters of the sands, and indirectly on the quality of quartz grains binding. Studies aimed at determination of water content changes in the sands have also been undertaken. As our studies demonstrated, microwave heating allows for quick reduction of water content, thus resulting in improvement of strength parameters such as bending and tensile strength. Application of the combined methods of ester curing and innovative microwave heating facilitates production of high quality foundry moulds and cores, while simultaneously improving mould and core preparation procedures at the foundries and as a result reduces their time to an indispensable minimum.
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This article presents results of the experimental trial of combination of the chemical method of water glass molding sands' curing, used in foundry industry, with an innovative microwave heating. The research objective was to indicate at new areas of microwave energy application. The sands prepared, according to recommendations for curing technology, with the use of ethylene glycol diacetate, have been subject to microwave influence. The attempt at determination of microwave influence on qualitative changes of the binding bridges created during the curing process concerned such parameters as: bending and tensile strength, permeability as well as wear resistance. Moreover, we also determined the influence of microwave curing on the phenomena accompanying the process as well as bond stability (storage time of the prepared molding and core sands). It has been found, basing on the result analysis, that the innovative microwave heating might constitute a very good supplementation of the ester curing method. The advantages of the combined chemical and microwave gelation process include, among others, improvement of the described resistance and technological parameters as well as significant decrease of preparation time of foundry moulds and cores. The subject discussed in this article will be continued in its second part.
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This work presents results of research on the influence of microwave heating time on the process of hardening of microwave cured molding sands. Essential influence of this drying process on basic properties such as: compression, bending and tensile strength as well as permeability and wear resistance, while supplementing and reinforcing influence of water glass addition on these parameters, known from practice as well as literature, has been found. A beneficial influence of hardening (drying) process has been observed in case of all available on the market kinds of this binding agent (including the most frequently used in foundry 145 and 149 kinds). It has been proved, that microwave heating guarantees obtaining very good, in comparison to traditional carbon dioxide hardening process, strength and resistance properties as well as technological characteristics of molding sand with only 1.0 up to 1.5% content of water glass. Microwave curing of water glass moldings sands guarantees, apart from a significant process time reduction, a full stabilization of their properties as well as considerable lower energy consumption and allows for amount reduction of the used binding agent and, as a result, improvement of knock-out properties of the sands. Microwave heating of water glass molding sands, through suitable process parameter selection, results in the possibility of forecasting and control of their properties.
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This work presents results of research on the influence of microwave heating time on the process of hardening of water glass molding sands. Essential influence of this drying process on basic properties such as: compression, bending and tensile strength as well as permeability and wear resistance, has been found. It has been proved, that all the investigated sorts of sodium water glass could be used as binding material of molding sands intended for curing with the microwave process heating. It has been found, while analyzing the results of property studies of microwave heated molding sands with 2.5% addition of water glass, that all available on the market kinds of this binding agent (including the most frequently used in foundry 145 and 149 kinds) after microwave heating guarantee very good compression, bending and tensile strength as well as permeability and wear resistance. Moreover, it has been determined that the optimal curing power of molding sands containing various kinds of water glass is 560 W. All values exceeding this result in stabilization of basic properties of molding sands. The use of microwave curing of water glass molding sands results in a significant decrease of hardening a process time, full stabilization of molding sands as well as much lower energy consumption.
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The presented work includes results of standing wave measurement for evaluation of microwave absorption efficiency by molding materials. Initial research has been conducted using microwave gap line. It has been demonstrated that foundry quartz sands have minimal microwave absorption capability. The following binders used for research: bentonite „Geco” and bentonite „Specjal”, demonstrated the highest absorption of Pabs microwave power output of over 60% Pin. It has also been demonstrated that water content, constituting component of synthetic molding sands, significantly influences change of microwave absorption. We have established that application of this kind of measuring device may allow for precise determination of characteristic features, such as microwave absorption factor k, of various foundry materials as well as determination of their suitability in foundry processes, e.g. microwave formation of foundry molds and cores. Microwave gap line may also serve as a device for precise determination of water content as well as other molding sand components and for their identification with the use of characteristic parameters, e.g. reflection factor |Γk|.
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This work presents results of research on the influence of microwave heating time on the process of hardening of water glass molding sands. Essential influence of this drying process on basic properties such as: compression, bending and tensile strength as well as permeability and wear resistance, has been found. It has been proved, that all the investigated sorts of sodium water glass could be used as binding material of molding sands intended for curing with the microwave process heating. It has been found, while analyzing the results of property studies of microwave heated molding sands with 2.5% addition of water glass, that all available on the market kinds of this binding agent (including the most frequently used in foundry 145 and 149 kinds) after microwave heating guarantee very good compression, bending and tensile strength as well as permeability and wear resistance. Moreover, it has been determined that the optimal curing time of molding sands containing various kinds of water glass is 240 seconds. After this time, all basic properties of molding sands are stable. The use of microwave curing of water glass molding sands results in a significant decrease of hardening process time, full stabilization of molding sands as well as much lower energy consumption.
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This work presents the results of investigation of microwave heating on hardening process of water glass molding sands. Essential influence of this heating process on basic properties such as: compression, bending and tensile strength as well as permeability and abrasion resistance has been found. It has been proved, that all investigated sorts of sodium water glass with a module between 2.0 and 3.3 can be used as a binder of molding sands in microwave curing process. It has been found during analysis of research results of sands with 2.5 % water glass addition that they are practically the same as in case of identical molding sands dried for 120 minutes at the temperature of 110°C, used for comparative purposes. Application of microwave curing of molding sands with water glass, however, guarantees reduction of hardening time (from 120 to 4 minutes) as well as significant reduction of energy consumption. Attempts of two stage hardening of the investigated water glass molding sands have also been carried out, that is after an initial hardening during a classical CO_2 process (identical sands have also been tested for comparison after CO_2 blowing process) and additional microwave heating. It has been found that application of this kind of treatment for curing sands with 2.5 % sodium water glass content and module from 2.0 up to 3.3 results in the improvement of properties in comparison to classical CO_2 process.
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This article contains description of a new programming method of PLC controllers, presently a fundamental tool in discrete process auto-mation. A PLC user, applying standard languages for programming of sequence processes, is forced to rely on intuitive methods as well as his own experience. For this reason, the authors attempted to work out a method, which would allow for simple execution of the program-ming process with no limits regarding number of steps and input and output signals. The result of these studies is a method named Graftech by its authors. The method consists in determination of a functional program in LD language, basing on process algorithm written with SFC network. The rules concerning determination of the functional program are also described. Application of Graftech method is illustrated with an example of automatic ejector of casting molds.
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