Andrii Dzyubyk, Liudmyla Dzyubyk, Yaroslav Zinko, Stanislav Biruk
Lviv Polytechnic National University, Lviv, Ukraine
OPTIMIZATION OF CONDITIONS OF ELECTROSLAG WELDING
OF BANDINGS OF ROTARY UNITS
Received: November 22, 2016 / Revised: December 22, 2016 / Accepted: December 26, 2016
© Dziubyk A., Dziubyk L., Zinko Ya., Biruk S., 2016
Abstract. The design of banding shells of rotary units is analyzed. It is shown that combined welding and cast manufacturing of bandings is used in the case of large structural sizes. The basic materials (30, 35, 25 HSL and 30 HML), being used in this process, are characterized by the tendency of forming of hardening structures due to the thermal cycle of welding. As a result of this, the cracks in the heat-effected zone, which lead to the destruction of the connection under the influence of welding residual stresses. The analysis of literature sources has shown that the usage of electroslag welding is perspective during the manufacturing and welding of operational cracks. Thus it is important to define the correct parameters of the welding conditions. In the case of electroslag method they are different from the arc methods and are characterized by the larger amount.
In the paper the technological process of welding of banding (tread) ring with the external diameter of 4600 mm, wall thickness of 300 mm and wideness of 500 mm, which is made of steel 35. The defining of regime parameters is made using the following recommended techniques: taking into account the chemical composition of the basic metal; according to the nomogram depending on the ratio of the thickness of the metal to the number of electrode wires; using the calculation (design) method according to the conditions of electroslag welding of the banding.
Taking into account the tendency of the steel 35 to cracks forming (cracking), the evaluation of the structure and phase composition and mechanical properties of metal of heat-effected zone of the weld. In order to define the microstructure, the cooling rate of the metal in the range of structural transformations was determined and the diagram of anisothermal decomposition of austenite was used. The technique of determination of the metal cooling rate as a result of the influence of thermal cycle of electroslag welding is proposed in the paper. It is based on the usage of special nomograms which characterize the specific features of the process being studied. The cooling rate equals degrees per second when using the developed process parameters. Also the investigation of temperature distribution in the cross-section of the weld has been carried out. It is shown that there are no significant deviations of temperature when using the proposed regime parameters. This influences the reduction of the level of residual stresses along the thickness of the weld.
The analysis of the diagram of austenite transformation has shown that the structure of the steel 35 in the initial state is ferrite one with the mixture of pearlite and bainite. As a result of welding carrying out the structure will have a similar composition with slightly larger content of perlite and bainite. It was defined that their content in the heat-effected zone is as follows: 39 % for ferrite, 61 % for the mixture of perlite and bainite. At the same time, the investigated technology of electroslag process ensures the slow heating and cooling of the areas around the weld and obtaining of satisfactory mechanical properties of the metal.
Therefore, the combined usage of existent techniques of regime parameters determination is expedient. Also it is necessary to carry out the verification of physical and chemical properties of the metal of heat-effected zone in order to prevent the formation of hardening structures.
Keywords: electroslag welding, banding, rotary unit, shell, residual stress, arc-welding, hardening, cast, forge, crack.
Кількість посилань 14

Catherine Barandych, Sergey Vyslouh, Victor Antoniuk, Oleksandr Tymoshenko, Viktor Koval
National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine
LATHE TURNING MODE OPTIMISATION FOR PARTS WORKING UNDER CONDITIONS OF CYCLIC LOADING
Received: October 4, 2016 / Revised: November 24, 2016 / Accepted: December 26, 2016
© Barandych C., Vyslouh S., Antoniuk V., Tymoshenko O., Koval V., 2016
Abstract. This work is devoted to questions of technological cyclic durability maintenance, of the material for parts working under cyclic loading conditions, by lathe processing optimization. The analysis of the impact of the surface layer quality on fatigue characteristics is described for parts operating under cyclic loads. Survey of methods for evaluating cyclic durability is completed, which showed lack of information about the mathematical relation between the cyclic durability of the part’s material and technological conditions of its production. A fatigue experimental study was carried out, the results of which allowed to create a mathematical model of cyclic durability of the material from lathe processing mode and tension cycle. The complex objective function that takes into account the dependence of cyclic durability of turning from technological conditions of handling and processing was developed. It is proposed to determine tension cycle for the most unsafe parts of a constructive element with consideration of conditions of service using the finite element method. The mathematical model of lathe processing of parts working under conditions of variable cyclic loads is developed and represented by total complex target function and system of constraints, including set of constrains on: feed, speed, strength and power of cutting, cutting precision, tool life and roughness of the workpiece. In addition, this mathematical model takes into account the actual characteristics of the material and expands its use to other materials of alloyed chromium steel. Submitted multi-criteria task is solved by using the method of sliding clearance. Steel 40Х GOST 4543-71 was used as an example for the proposed mathematical model of the part turning process, part operates under cyclic loading, and best values for feed and cutting speed are calculated.
Keywords: cyclic loading, lathe processing, technological conditions, fatigue, handling, tension.

Кількість посилань 19

Petro Koruniak1, Vladyslav Shenbor2, Vitaliy Korendiy2,
Anatoliy Bezpalov2, Volodymyr Brusentsov2
1Lviv National Agrarian University, Dubliany, Ukraine
2Lviv Polytechnic National University, Lviv, Ukraine
WAYS OF IMPROVEMENT OF OPERATIONAL EFFICIENCY
OF HOPPER DEVICES
Received: August 22, 2016 / Revised: September 28, 2016 / Accepted: December 26, 2016
© Koruniak P., Shenbor V., Korendiy V., Bezpalov A., Brusentsov V., 2016
Abstract. The operation of hopper devices, which are used in industry, civil engineering, agriculture and transport, is analyzed on the article. The external factors, which influence the process of charging, storing and discharging of loose cargo (freights) from hopper tanks, are overviewed. The subject of research of presented paper is the improvement of mechanisms of fracturing of products hangs-up (bridges) in hoppers at the stage of designing and setting up of hopper devices. In order to solve the stated problem the schemes of bridges fracturing and the structures of devices for debarment of products bridging and their uniform outflow from the hopper tank are proposed. The proposed schemes are based on the principles used in development of vibratory machinery with mechanical, cam and electromagnetic vibratory principles of structures forming. For cam spring device of bridges fracturing the technique of calculation of stiffness of elastic system and of the necessary forces for performing of technological process of bridges fracturing is presented and the recommendations for choosing of the stiffness of the system of elastic elements are suggested.
For the hoppers with spring and electromagnetic blocks of bridges fracturing and of metered (batched) feeding of products the structural diagrams of devices are presented and the recommendations for usage of various modifications of devices are suggested. The influence of parameters of flat spring elements on the efficiency of devices operation is overviewed. The structural diagrams of devices with one-cycle and two-cycle electromagnetic vibration exciters and the modifications of elastic systems are considered. the structural diagram of the production prototype of the hopper feeder is presented.
The materials of the article, the proposed structural diagrams, the operation scheme of the hopper feeder and the derived analytical formulas may be used by designers, researchers and technologists while improving of existent and developing of new devices.
Keywords: hopper, device, elastic system, armature, electromagnet, stiffness, stabilizer, bridge, loose material, feeder.

Кількість посилань 16

Vadym Stupnytskyy
Lviv Polytechnic National University, Lviv, Ukraine
INVESTIGATION OF THE INFLUENCE OF MACHINING FACTORS
ON THE WORKPIECE DEFORMATION MODE
IN THE CHIP-FORMING ZONE BY THE FINITE ELEMENT METHOD
Received: October 8, 2016 / Revised: November 19, 2016 / Accepted: December 26, 2016
© Stupnytskyy V., 2016
Abstract. The results of studies of the impact strength, temperature factors and parameters of cutting tool geometry on the formation of the stress-strain and thermodynamic state of surfaces with different types of engineering materials in the cutting process are described in the article. Analysis of simulation modeling of power, temperature and deformation parameters is the basis for making of forecasting models of influence of the structure and process parameters on the formation of complex operational properties of the product.
Keywords: machining factors, strength, cutting tool, thermodynamic state, deformation.

Кількість посилань 11

Yurii Zalutskyi, Oleksandr Zhytenko, Ihor Kuzio
Lviv Polytechnic National University, Lviv, Ukraine
ANALYSIS OF MODERN INVESTIGATIONS OF VIBRATORY PROCESSES OF WHEELED VEHICLES
Received: November 19, 2016 / Revised: December 23, 2016 / Accepted: December 26, 2016
© Zalutskyi Yu., Zhytenko O., Kuzio I., 2016
Abstract. The history and modern tendencies of development of cushioning systems are analyzed in this paper. The development of mathematical modelling as a process is denoted, the methods and means are described and the necessary information of model choosing is presented. It is focused on the development of simulation modelling. The approaches of researchers, recommendations, indexes and specific features of evaluation of motion evenness are described.
The works of many scientists are dedicated to analysis of car vibrations, evaluation of motion evenness and vibration-proof features. Many of them are devoted to investigation of vibrations, to optimization of basic design parameters of the cushioning system of cars and to development of new cushioning systems which allow reducing of vibratory overloading of trucks of general purpose. Taking into account the problems of motion evenness from the point of view of vibration of cushioning parts, the works of scientists are based on the linear theory of cushioning and the simplest one-mass car models are considered. It is also established that the drawback of usage of such theory consists in the fact that it is impossible to overview separately the vibrations of cushioning parts, which weight transfers to elastic elements of the suspension, and non-cushioning parts. The overview of scientific works dedicated to investigation of dynamics of wheeled vehicles allows to show the limited possibilities of traditional passive suspension system according to continuously increasing requirements to modern structures and to substantiate the necessity of usage of controlled cushioning systems. Among the existing variants of controlled cushioning systems, the half-controlled systems, which are the most optimal from the point of view of motion evenness increasing, energy consumption, complexity of structural implementation and usage safety, are of the greatest interest nowadays.
On the basis of analyzed materials, it may be concluded that there exists a great amount of scientific investigations in the field of motor vehicles vibrations many of which are devoted to improvement of vibration-proof features of cars. Also a number of works are dedicated to investigation of vibratory overloading of industrial, construction and agricultural motor vehicles which are engaged in transportation of cargo of general purpose. However, too small attention is payed to development of techniques of determination of design parameters of cushioning systems of trucks which are engaged in transportation of cargo of special purpose, for example, cars transportation, where essentially greater attention should be payed to vibratory loadings which act upon such cargo during uneven motion.
Keywords: cushioning system, vibratory loading, simulation modelling, motion evenness, suspension system, wheeled vehicle.

Кількість посилань 34