Ukrainian Journal of Mechanical Engineering and Materials Science

6

Authors: Ihor Hrytsay

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.

8

Authors: Lubomyr Borushchak, Stepan Borushchak, Oleh Onysko

Tightness is one of the parameters of the quality of pipe drill string. Consequently, the reduction of hydraulic costs and wear of the tool-joint tapered thread of the drill string can be achieved by changing the cutting part of the cut tools. It is precisely because of the reduction of the tightness we have bigger expense of hydraulic energy on the one hand and the wear on the surface of the thread is accelerated, since the drilling fluid together with the abrasive, moves along the screw threaded channel at a high speed (over 50 m/s) on the other side. To date, the tightness of tool-joint tapered thread provided in two ways. The second is the filling of the spiral channel, which is formed due to the standard gap between the box and the pin by a special lubricating and sealing filler. Typically, such fillers in the presence of significant pressure and untightness when contacting the ends of the box and pin are displaced from the channel. The authors of the article propose to reduce the cross-sectional area of the specified gap to achieve a sharp decrease in the speed of the drilling mud in the channel formed by the gap. As a result of the virtual experiment, actual data were obtained regarding the speed of the drilling mud, which became 40-50 times smaller in the case of a decrease in the height of the channel by 4 times and its width by 1.6 times. In the article it is shown that the existing sizes and tolerances for the gaps in the standard are of an optional nature and are presented for the design of a cutting tool for cutting. Consequently, the reduction of hydraulic costs and wear of the tool-joint tapered thread of the drill string can be achieved by changing the cutting part of the cut tools.

9

Authors: Jerzy Jaroszewicz, Olesya Maksymovych, Andrii Dzyubyk, Ihor Nazar

In the article, the algorithm for determination of stresses in anisotropic plates with elastic inclusions of another anisotropic material was developed on the basis of complex singular integral equations. The solving of integral equations has been carried out numerically using the method of mechanical quadratures. The strength analysis (calculation of strength) of composite plates with inclusions has been performed using the Hoffman criterion.

10

Authors: Vasyl Olshanskiy, Stanislav Olshanskiy, Maksym Slipchenko

A free oscillations of a system with one degree of freedom, caused either by the initial deviation from the stable equilibrium position or by the initial velocity provided by the oscillator in this position was considered. Analytical solutions of the nonlinear Cauchy problem for a second-order differential equation were constructed. The solutions are expressed in terms of Jacobi's periodic elliptic functions relating to occultation of special functions. Compact equals are derived for calculating the displacements of the oscillator and the oscillation periods for various methods of motion perturbation and for various variants of the elastic characteristic. The restrictions on the initial excitations for an oscillator with a soft elastic characteristic are determined, when its free oscillations are possible. The existence of a solution of the nonlinear dynamics problem in elementary functions is established. The behavior of an oscillator with a soft characteristic of elasticity under conditions of its freezing are studied. It is shown that from the derived equals, as special cases, the results known in the theory of linear oscillators, as well as oscillators with a purely quadratic nonlinearity, without a linear component, follow when the solution of the problem can be expressed in terms of Ateb-functions. The aim of the work was to derive new calculation equals for determining the displacements of a mechanical system with one degree of freedom under conditions of free oscillations, in the absence of friction. To achieve this objective, the representation of the second integral of the differential equation of motion due to the incomplete elliptic integral of the first kind were used. Using the known tables of the indicated integral, examples of calculations are given in which the probability of the derived equals is confirmed. According to the results of the study, it is also established that in the case of a quadratic elasticity characteristic of the linear component, the motion of the oscillator is described by the periodic elliptic Jacobi function, both in providing it with an initial deviation from the stable equilibrium position, and giving it the initial velocity in this position. In the case of a soft elasticity characteristic, free oscillations are possible only with certain restrictions on the initial perturbations of the system.

12

Authors: Volodymyr Biloborodchenko, Andrii Dzyubyk, Andrii Zabranskyi

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.

13

Authors: Anatoly Zhygalov, Vadym Stupnytskyy

Theoretical calculations and experimental studies of the influence of wear on the cutting process and the precision parameters of machining by hard alloys during milling are described in the article. The method of aerodynamic hardening is designed to increase the durability of tools, which are heterogeneous compositions of tungsten carbides, titanium and tantalum with cobalt ligature operating under severe process conditions with varying impact loads. The effect of hardening by the ADH method is achieved due to the influence of sound waves on the structure of hard alloys. The results of imitation studies of the wear process in the DEFORM system are described.