Ukrainian Journal of Mechanical Engineering And Materials Science. – 2017. – Vol. 3, No. 2

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https://ena.lpnu.ua/handle/ntb/42871

Науковий журнал

Засновник і видавець Національний університет «Львівська політехніка». Виходить двічі на рік з 2015 року.

Ukrainian Journal of Mechanical Engineering and Materials Science = Український журнал із машинобудування і матеріалознавства : науковий журнал / Lviv Politechnic National University ; editor-in-chief Oleksiy Lanets. – Lviv, 2017. – Volume 3, number 2. – 118 p. : il.

Ukrainian Journal of Mechanical Engineering and Materials Science

Зміст (том 3, № 2)


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Content (Vol. 3, No 2)


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    Prospects of use of vibratory devices with electromagnetic drives for massive piece goods conveying
    (Lviv Politechnic Publishing House, 2017-10-19) Vrublevskyi, Igor; Hetman Petro Sahaidachnyi National Army Academy
    Vibratory conveying devices with electromagnetic drive are widely used in the different branches of industry. As a rule, they deal with relatively small piece goods and are not suitable for conveying of the large massive goods with high productivity. The conveying of massive piece goods needs the using of non-hopping modes of moving in which the high velocity can be reached only in the case of non-linear vibration trajectories of the conveying track, for example elliptical trajectories. Such trajectories are obtained by using of the independent drives of horizontal and vertical oscillations. Even greater velocity can be reached by using biharmonic vertical oscillation with particular optimal relations between amplitudes and phase differences of the component oscillations. These types of devices can be designed on a basis of three-mass oscillating system. Theoretical and experimental investigations show that the goods’ mass change significantly affects the vertical oscillations and weakly affects the horizontal oscillations. And at the certain relations between masses ratio and resonant tuning (ratio of frequencies of forced and natural oscillations) the vertical oscillations of active mass of two-mass vibratory device are insensitive to the change of goods’ mass. The sensitivity of vibratory conveying stability to the goods’ mass change was investigated for two-mass vibratory devices with elliptical oscillations. Three-mass oscillating systems with biharmonic oscillations in the point of view of the sensitivity to the goods’ mass changing were not considered. Analysis of different three-mass oscillating systems with electromagnetic drives of harmonic horizontal and biharmonic vertical oscillations allows determining two most preferable versions. The equations for amplitudes of components and frequencies of natural oscillations determining are derived. From the condition of insensitivity to conveying mass change the optimal relations between masses ratio and resonant tuning are obtained.
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    Substantiation of parameters and analysis of operational characteristics of oscillating systems of vibratory finishing machines
    (Lviv Politechnic Publishing House, 2017-10-19) Korendiy, Vitaliy; Zakharov, Viktor; Lviv Polytechnic National University; ISKRA PJSC
    The calculation diagrams of oscillating systems and operation features of vibratory finishing machines are considered. The mathematical models of three-mass and four-mass oscillating systems are presented. The amplitude values of the oscillating masses displacements are derived. The functions of inertial and stiffness parameters optimization are formed. The optimization problems are solved with a help of MathCAD software. On the basis of synthesized inertial and stiffness parameters, the amplitude-frequency characteristics of the oscillating systems of vibratory finishing machines are formed and analyzed. In order to verify the validity of the proposed theoretical approaches, the simulation of the mathematical model of the oscillating system motion is carried out by means of numerical solving of the system of differential equations of the oscillating masses motion. The proposed structural diagrams and the operation schemes of the vibratory finishing machine, as well as the derived analytical formulas may be used by designers, researchers and technologists while improving existent and developing new equipment for vibro-finishing treatment.
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    Optimization of welding modes for high-strength low-alloy domex 700 steel
    (Lviv Politechnic Publishing House, 2017-10-19) Dzyubyk, Andrii; Palash, Volodymyr; Khomych, Ivan; Hrynus, Stanislav; Lviv Polytechnic National University
    The microstructure and hardness of the weld joints of DOMEX 700 steel were investigated. As a result, the optimization of the parameters of robotic arc welding in the environment of protective gases was carried out taking into account the size of the energy per unit length. The optimum modes of welding were determined. The size of the deterioration area, where there is a decrease in hardness in comparison with the main metal, for a thickness of 6 mm is 2.36 mm, and for a thickness of 3 mm is 1.51 mm. The parameters of the robotic welding process in the arc mode in the environment of protective gases for the investigated thicknesses of the DOMEX 700 steel were recommended. As a result, the energy-saving conditions for welding performing were achieved ensuring the required technological strength.
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    Investigation of magnetically controlled electric arc
    (Lviv Politechnic Publishing House, 2017-10-19) Biloborodchenko, Volodymyr; Dzyubyk, Andrii; Zabranskyi, Andrii; Lviv Polytechnic National University
    In this work, the results of pad welding with the circularly rotating arc existing in an inert gas between a circle cathode with the diameter suitable to dimensions and geometry of a welded surface, with the kinematic characteristics of the motion provided (with the rest equal conditions) by the external magnetic field, are considered. It is shown that the strict theory of an electric arc is insufficient for the description of real physical processes occurred in it under the action of external exciting magnetic fields, and so it does not allow conducting satisfactory technological calculations of the parameters of the pad welding process performed by the arc moved by the external magnetic field. The main problem consists in determining the effectiveness and the direction of superposition of electrodynamic and mechanical forces in it, which resist arc interaction with the magnetic field. Therefore, the aim of the work is to investigate the influence of the induction value В of the transvers magnetic field of a solenoid inductor on predicted kinematic characteristics of the arc. The investigations were conducted with the use of experimental equipment (test bench) consisting of a toroidal inductor with a winding. On the inductor, a nonfusible water-cooled ring copper electrode is mounted. Electrode dimensions agree with the diameter of pad surface. The shielding gas is provided through the system of radially located nozzles with discreet valvular operation, whose work priority is agreed with the arc motion velocity by a control unit. Since the values of abovementioned forces directly conditioned by the presence of a magnetic field in an interelectrode gap, the investigation of its intensity by the electrodynamic method with the help of the measuring instrument for magnetic induction ИМИ-1 was carried out. The analysis of the superimposed surface of the impact of the magnetizing current and the arc gap, which are used at pad welding by magnetically controlled arc, on the field induction shows that the range of their influence as technological mode parameters is quite narrow. Accordingly, for optimal choice of model nomographic solutions and the description of the correlation of parameters of the arc gap and magnetizing current, which provide the technologically suitable induction, an experiment was conducted according to the matrix of simplex-summarized С-С2 design. The investigations of a model extremum shows the acceptable induction value of 850∙10-5Т for the length of the electrode gap of 4 mm and inductor magnetizing current of 6 A. As a result, the proposed design of the test bench satisfies the geometrical parameters of renovated workpiece and enables using the effective repeated thermal pad cycle per unit of the surface by the rotating arc in the stable magnetic field. Settings of the magnetically operated arc, which provide the necessary value of field induction in the inter-electrode gap, can be determined either by nomograph solution, or by the strict statistic models. The influence of the length of the inter-electrode gap on the choice of the induction value is limited by technologically suitable pad current and corresponding length of an arc column. The main setting and controlling parameter of the magnetic field mode is the inductor magnetizing current. The force of resistance to arc motion at the stage of arc development and at the stage of arc steady motion is directly proportional to the value of the pad current. Calculated values of the velocity of arc motion at given values of the pad current are in the range relevant to its steady motion and provide the processes of anode melting without thermal damaging the ring cathode.
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    Gears with asymmetric tooth profiles and new alternative method of their manufacturing
    (Lviv Politechnic Publishing House, 2017-10-19) Hrytsay, Ihor; Lviv Polytechnic National University
    The article presents a new gears cutting process – radial circular generating method and describes its multiple benefits for manufacturers of transmissions. The overall increase of efficiency is realized due to using a simple tool and the conventional gear tool machine for cutting gears of different types. In particular, this new method was used for cutting gears with the asymmetric profiles of wheel teeth, which allows considerably amplifying power transmission density, increasing load capacity, and reducing size and weight.