The article describes an innovative post-weld surface finishing method, which is characterized by moving a specialized cutting tool along a butt weld. The aforementioned method is unique for the machining allowance, which is treated as the weld bead height and is removed in one step with one pass of the cutting tool. The tool is equipped on one side with linearly arranged tooth-shaped cutting elements, with the adjacent teeth height changing and increasing according to the direction of the feed. The non-standard geometry of the cutting tool enables the finishing of a heterogeneous post-weld surface with increased hardness. The results of studying the 2D profile parameters and the 3D stereometric characteristics of the surface roughness using the optical method are presented in the article. Test samples were made of S235JR steel and butt welded with the MMA, MIG, and TIG methods. Subsequently, the welding bead was ground and finished in accordance with the innovative method to flush the bead and the base metal’s surface. Additionally, residual stress analyses were performed using the X-ray diffraction method in the surface layers of the test samples. Based on the conducted research, the influence of the innovative finishing method on the surface quality is described.
The main idea of the work is to create a physical model of high speed broaching heat-resistant materials is used to study the parameters of the surface layer quality. Modelling is a method of mediated cognition, in which the object under study is in some correspondence with the model, and the object-model is capable in some way or another to replace the original at some stages of the cognitive process. Physical modelling is primarily distinguished by the fact that studies are conducted on models with physical similarity, i.e. preserving completely (or at least partially) the nature of the phenomena. The work of the broach can be likened to the work of a number of planning cutter displaced relative to each other by a small amount, which is called lifting (feed per tooth). Therefore, for experimental work, a planning cutter of a special geometric was designed and manufactured -a physical model of a broach, in which geometric, mechanical and dynamic similarity is realized. The article also presents an experimental justification for the use of the created physical model in the study of the surface quality parameters of the, tab grooves of turbine and compressors disks made of heat-resistant materials.
Powierzchnie elementów połączeń zamkowych w turbinie i sprężarce są jednymi z najbardziej obciążonych powierzchni podczas pracy silnika turbinowego. Obecność agresywnego środowiska (gorący gaz z popiołem i domieszkami znajdującymi się w paliwie), wysoka temperatura pracy, ciśnienie, obciążenia od działania sił odśrodkowych, gazodynamicznych oraz powstające drgania wywołują wiele procesów prowadzących często do uszkodzenia połączenia zamkowego, a w efekcie nawet awarii lub zniszczenia silnika turbinowego. Wymienione czynniki wpływające na powierzchnie połączeń zamkowych prowadzą do wzrostu naprężeń i napięć kontaktowych, aktywizacji procesów zużycia frettingowego, powodują również erozję i pękanie zmęczeniowe. Najczęściej stosowanym typem połączenia łopatki z tarczą wirników sprężarki jest zamek trapezowy lub tzw. "jaskółczy ogon", dla turbiny zaś-jodełkowe połączenie zamkowe. W procesie projektowania i wytwarzania zamka należy szczególnie uwzględnić stabilną pracę zespołu wirnikowego sprężarki i turbiny oraz żywotność całego silnika oraz wziąć pod uwagę: wysokie wymagania dotyczące składu oraz jakości materiałów tarczy i łopatek, niską obrabialność tych materiałów, skomplikowany kształt i wysokie wymagania dotyczące dokładności, a także wzajemnego położenia powierzchni oraz jakość warstwy powierzchniowej zamka. Takie wymagania można spełnić za pomocą różnych metod obróbki skrawaniem (przeciąganie, frezowanie), obróbki elektrochemicznej (ECM) lub elektroerozyjnej (EDM). Metoda obróbki elektrochemicznej zamka ma wiele zalet w stosunku do obróbki skrawaniem, m.in.: możliwość obróbki materiałów przewodzących prąd z różnymi właściwościami mechanicznymi, zapewnienie wysokiej jakości warstwy powierzchniowej, dużą produktywność przy długim okresie eksploatacji elektrody. Dokładność obróbki zamków metodą ECM jest jednak bardzo niska. Metoda przeciągania pozostaje więc jedną z najczęściej używanych, a na etapie wykańczania-jedyną możliwą metodą tworzenia dokładnego zamka z wysoką jakością warstwy powierzchniowej.
At present peristaltic pumps are widely used in many branches of industry and national economy. Simplicity of construction, processability and possibility of pumping liquids with big quantity of solid particles are the main advantages while using peristaltic pumps. Therefore development of methods of rational choice of parameters at designing of peristaltic pumps is the actual problem. To develop universal mathematical models of dynamic processes in peristaltic pumps for definition of rational technical parameters. In dynamic processes we propose to use differential equations of motion in the Lagrange form, where the angle of rotation of the pump rotor is taken as a universal coordinate. Mathematical model of dynamic processes in peristaltic pump with hydraulic drive has been created on the base of differential equation. The function of resistance forces caused by gravity forces of mixture particles in the hose reel has been determined. On the basis of the non-linear model of the resistance forces to the flow of the fluid Bingham method of constructing the dependence of the pressure drop on the angular velocity of the rotor to determine the resistance forces to the flow of the fluid has been proposed. The result of dynamic processes simulation is the determination of interrelationship of technological parameters of the device functioning: the velocity of the medium and pump performance is increasing at reducing the length of the diverting hose and reducing the height of its rise; a significant influence on the average speed has plastic viscosity of the environment; a significant change in the yield strength has an insignificant impact on the speed.
Modern cooling systems for large ships are quite complex. As a rule, such systems are common (combined) for the main and auxiliaries engines. With the auxiliary engines running constantly, even when parked, this system design allows to keep it warm and ready for a quick start of the main engines at any time. Currently, various schemes of such systems are used, including those that are irrational from our point of view. At the same time, there are systems whose schemes are quite consistent with our idea of the rational forms of such structures. It is important to note, and it is saying about it in an article, that such schemes may have a number of significant differences, but at the same time they will comply with the rationality principle if certain rules for the formation of such systems are followed. These schemes will have close compactness. It is also important that there is the possibility of further improvement of such schemes based on certain rules. This improvement is possible due to the introduction of additional heat dissipaters and the organization of appropriate chains of heat sources and heat dissipaters. The article discusses various options for rational schemes of the cooling system for the same ship power plant, as well as the possibility of further improvement of this scheme. It is shown that an increase in the number of coolants of the internal circuit coolant from one to three can reduce the total mass of the heat exchanger cores by 18 %.
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