Practical Considerations For A Rated Speed Shop Balance

LecturePg. 87-94.The increasing availability of high speed balancing facilities requires the manufacturer and/or ultimate user to seriously consider a rates speed rotor balance. In addition, the development of the "influence coefficient" method of balancing as a complement to the modal technique has established increased balancing reliability. The present paper develops the aspects of flexible rotor balancing which should be evaluated when considering the necessity and benefits of a rated speed balance. Three classes of industrial turbomachine rotors are investigated using a "rotor response" and an "influence coefficient" computer balance program. These results illustrate the concepts established in the analysis and present a practical example of how the influence coefficient and modal balancing methods complement one another, resulting in a complete approach to balancing

The Influence of Selected Melting Parameters on the Physical and Chemical Properties of Cast Iron

This paper presents the problems related to smelting gray and ductile cast iron. Special attention is paid to the metallurgical quality of cast iron. It depends on the type of furnace, charge materials and the special combination of charge, overheating and holding temperature, melting time, modification and spheroidization method. The evaluation of metallurgical quality has been performed by using derivative-thermal analysis (DTA). During the smelting process and secondary metallurgy, the ITACA system was used allowing to obtain information on alloy characteristic temperatures (Tliquidus, TeMin, TeMax, Tsolidus), VPS value, recalescence value, IGQ coefficient, nucleation gauge, porosity etc. The results of investigations and calculations are displayed in the form of graphs and dependencies. It has been shown that the derivative-thermal analysis (DTA) is an effective complement of chemical analysis and it has been found that both the increase in temperature and metal holding time have a negative impact on the metallurgical quality of liquid metal. The metallurgical quality can be improved by using proper composition of charge materials and modifiers

The Impact of Composition and the Densification Level of Furan Molding Compounds on the Strength of Large-Size Casting Molds

The paper presents the test results of molding compounds, sand casting molds and their analysis. The subject of testing was compound containing furan resins prepared according to the following recipe: matrix – regenerate 90% + fresh sand – 10%, furanresin – 1.10% by weight, hardener – 0.40% by weight. The impact of adhesive type and its quantity (Quan = 0.90, 1.1 and 1.5%) on the strength indexes of molding compound subject to densification was analyzed. The publication presents the test results: tensile strength Rm, compressive strength Rc and flexural strength Rg, as well as compound permeability as function of its density. The analysis also covers the impact of density level on mold strength and the distribution of density level along the mold height. Based on the test results, it was found that the best method to obtain high strength molds made from compounds with chemical adhesives was to densify it by vibrating the system: match plate – molding flask – compound filling the mold. The effectiveness of this densification method depends on the amplitude and frequency of vibrations