Ukrainian Journal of Mechanical Engineering and Materials Science
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Item Reducing the kinetic power of the crank press machine(Видавництво Львівської політехніки, 2023-02-28) Pasika, Viacheslav; Augousti, Andy; Lanets, Olena; Parashchyn, Oleh; Lviv Polytechnic National University; Kingston UniversityCrank presses belong to the class of machines in which the payload (stamping force) acts for a short period of time at the end of the working stroke. Since the power of a force is the product of the force times the speed, it is possible to reduce the power of a specific force only by reducing the speed of the point of action of the force. The kinematic characteristics of slider-crank mechanisms (SCMs), which are the main mechanism of crank presses, are qualitatively the same and cannot be changed. The speed of the slider, as a working body, is the most influenced by the rotation frequency and the crank's length. However, reducing the frequency of rotation leads to a decrease in the productivity of the press, and a decrease in the length of the crank is limited by the design possibilities and technological process of stamping. The purpose of this work is to reduce the kinetic power of the main working mechanism of crank presses by redistributing the start-up and run-out phases of the working body and designing the corresponding structural diagram of the SCM. Research methodology. A non-standard approach to reducing the kinetic power of crank presses is proposed. It is suggested to change the distribution of the run-up and run-out phases of the slider (punch) in order to reduce its speed in the range of the punching force to achieve this. To change the run-up and run-out time, a slider-crank mechanism with a programmable change in the length of the crank with a fixed cam is proposed. As a result of this research, an asymmetric cosine law of the movement of the slide was analyzed and it was synthesized into a variable crank length that ensures the movement of the slider according to the determined law. As far as we aware this is the first research that has been carried out on crank presses with the aim of reducing the kinetic power without reducing the value of the stamping force and press productivity. For a given punching force and an asymmetric cosine law for the punch motion, the kinetic power of the press is reduced by 31.4%. This will reduce the mass and/or radius of the flywheel. A list of planned further studies is: the influence of different functions for punch motion, functions for changing the punching force, and an investigation of the value and position of the force interval on the kinetic power of the press.Item Analysis of the influence of the displacement of the gear rack profile of the pair evolution gearing on the quality indicators of the transmission(Видавництво Львівської політехніки, 2023-02-28) Protasov, Roman; Magdolen, Ľuboš; Danko, Jan; Lanets, Olena; Vorontsov, Borys; Slovak University of Technology in Bratislava; Lviv Polytechnic National University; National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”The article is devoted to the study of the influence of the modification of the paired evolute gearing with convex-concave contact on the quality indicators of transmission, namely, the contact pressure and the speed of slippage in the engagement. Previous studies of evolute gears showed the presence of characteristic zones on the side surface of the tooth, which have worse values of quality indicators than in similar involute gear. One of the ways to remove these zones or to reduce their impact on the load capacity of the transmission is to modify the tooth profile, which will be implemented by shifting the profile of the processing gear rack. A displacement factor is added to the equation of the rail profile curve, which has the same value for the gear and wheel teeth, but the opposite sign. On the basis of the developed equation, the side profiles of the teeth of the gear and the wheel were constructed. Several values of the rack displacement coefficient with a positive and negative sign for the gear teeth are considered. The results of the research allow us to evaluate the influence of the amount and direction of the rail displacement on the curvature of the tooth profiles, the contact pressure in engagement along the height of the tooth, and the relative and absolute speed of sliding. Themodifications of the profile of the processing toothed rack proposed in thisworkwill expand the existence of paired evolute gears with a different set of quality indicators. This will make it possible to design gears with rational values of contact pressures and slip speeds when they are used in heavily loaded transmissions created for specific operating conditions. Gears with relatively high slip speeds can be used in road and construction equipment transmissions, which are characterized by lowshaft rotation frequency, in which the speed of slip between the teeth does not have a significant effect on the life or efficiency of the transmission. Otherwise, gears with relatively low slip speeds are very relevant when they are implemented in the transmission of modern and promising vehicles with a hybrid or fully electric power unit, especially in the case of passenger cars with high-speed electric motors.Item Influence of the ignition system parameters on the ecological indicators of the automobile gas-fueled engine(Видавництво Львівської політехніки, 2019-03-20) Brytkovskyi, Vasyl; Kachmar, Roman; Lanets, Olena; Lviv Polytechnic National UniversityThe structure of the automobile service, since the beginning of the independence of Ukraine, has changed acutely. The number of private vehicles, the quality of service of which depends on the owner only, has increased. In addition to already existing automobile transport enterprises which has at least some existing production facilities with available cars of post-Soviet production and Russian cars of the middle time of Ukraine's independence, a large number of private small motor vehicles companies without any production base have appeared (in the best occasion with the available storage area), technical condition of the movable composition of which does not meet the requirements of European countries and the main transporting direction of these enterprises was concentrated in the directions of post-Soviet countries. In order to maximize efficiency, the owners of such vehicles carry out the transformation of power supplies to the system supplied with gas fuel. Despite the sufficient number of advantages, such refurbishment requires the introduction of constructive modifications and adjustments also in the ignition system of motor vehicles. And here, in the absence of systematic state control, many of the car owners in pursuit of maximum economy, trying not to make changes, causing violations in the work of car systems, which leads not only to the growth of fuel consumption and reducing of the effective performance of the engine, but also to increasing of emission of toxic components with the exhaust gas flow of the car engines. In conditions of Ukrainian cities, where emissions of toxic components by transport sources are up to 90% of all harmful effects [11], the search for ways to improve the system of technical service of vehicles is relevant in order to control and reduce the level of environmental hazards from the operation of vehicles. Therefore, researches that focus on determining the influence of regulation of the ignition system of engines powered by gas fuel, on the example of the spark plug gap influence on the indicators of the content of the components of the exhaust gases, are relevant. The method of research on the influence of the spark plug gap on the change in the composition of exhaust gases was developed in the paper, the research was carried out on ZAZ Lanos 1.4 engine MeMZ 317, on which is an assembly of gas equipment of the 4th generation Stag 200 GoFast. All experiments were carried out on the equipment of the Training Center for Computer Diagnostics of Vehicles “Lviv Polytechnic – Bosch Academy”. A set of new Champion RN9YC spark plugs was used, the gap of which was changed from 0.6 to 1.4 mm with a pitch of 0.1 mm. According to the values of the gap between the electrodes of the spark plug, with the use of Bosch BEA 460 gas analyzer, the content of the following components of the exhaust gases CO, HC, O2 and CO2 is determined for two engine's crankshaft frequencies.Item Synthesis of structure and research of operation of resonance two-mass vibrating table with electromagnetic drive(Publishing House of Lviv Polytechnic National University, 2015) Lanets, Oleksiy; Borovets, Volodymyr; Lanets, Olena; Shpak, Yaroslav; Lozynskyy, VasylAn industrial necessity of creation of 100-Hz vibratory tables is grounded. The prospect of researches of just resonance electromagnetic vibratory tables is conditioned. The existing vibrating tables on the basis of electromagnetic drive are considered. It is noted that the stages and problems which arise during the creating of high-frequency two-mass vibration table of middle sizes constructed according to classic chart are oulined in the article. The principle scheme of an electromagnetic vibratory table which is to be developed is described. The basic analytical dependences for determining the coefficient of inflexibility of the resonance resilient system and hauling effort of the electromagnetic vibroexciters are obtained. The construction of the upper plate of vibrating table is grounded, and its first eigenfrequency is determmined in order to avoid the coincidence with its forced frequency. The construction of vibrating table is given: its spatial model is presented, and the general draft and the draft of the two-mass vibratory system are also given. The inertia parameters of the oscillating masses are determined. The parameters of stiffness and structural parameters of the resonance resilient system are determined. Checking of the resilient elements for durability is conducted. The parameters of stiffness and structural parameters of vibration isolators are determined. The results of calculation of vibroexciter, according to the hauling effort with the use of the specially developed program, are presented. The theoretical gain-frequency description of vibratory table and time dependences of motion of the oscillating masses are presented. The experimental gain-frequency description of vibratory table and time dependences of motion of the oscillating masses, which absolutely coincide with the theoretical, are presented.