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
(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
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.
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
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.
(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.
(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.
(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.