Ukrainian Journal of Mechanical Engineering and Materials Science

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Author: search.filters.author.Karpenko, MykolaHas files: Yes

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    Experimental improvement of the technology of cutting of high-pressure hoses with metal braid on hand cutting machine
    (Publishing House of Lviv Polytechnic National University, 2016) Karpenko, Mykola; Bogdevicius, Marijonas; Prentkovskis, Olegas
    In the article the review of the problem of improvement of technology of high pressure hoses cutting on the hand cutting machines is analyzed. Different methods of cutting of high pressure hoses into the billets are overviewed and the quality of edge cuts of hoses is analyzed. The comparison of treatment on automatic cutting machines and on hand cutting machines is carried out. Different experimental techniques of improvement of the quality of edges cutting of high pressure hoses are presented. On the basis of experimental method, a new cutting technology which consists in maximally close fixation of high pressure hoses to the cutting disc is proposed. In the basic design of the hand cutting machine, the only supports are provided, so that the cutting of the edge section of high pressure hoses causes the metal braid loosening. The proposed technology excludes the scrolling and bending of high pressure hoses during cutting, so that the loosening of metal braid is also excluded. In the paper it is shown that the scheme of distribution of cutting forces during the cutting of high pressure hoses is presented and the mathematical model of determination of normal and tangential cutting forces is formed. With a help of tensiometric table the values of components of cutting forces during free and fixed cutting of high pressure hoses were defined and their comparison was performed. As a result of the use of this technology the edges of the cut off high pressure hoses meet the necessary requirements without using of complicated technological processes.
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    The hydro-automatic damping system against dynamic vibrations
    (Publishing House of Lviv Polytechnic National University, 2015) Pelevin, Leonid; Karpenko, Mykola; Lavryk, Stanislav
    A review and analysis of the developed hydraulic system for quenching dynamic oscillations has been carried out. A mathematical model for determining the operation delay time of the hydraulic system of the dynamic quenching of oscillations has been created. A period’s calculation of cleavage of the soil and the operation delay time of quencher dynamic oscillations from which it is possible in theory to establish the ability of the hydraulic system of dynamic quenching of oscillations to operate in due time is performed. A hydraulic system of dynamic quenching of oscillations that occur inside the working unit to prevent the transmission of vibrations to the base of the machine is developed. The analysis of the damper’s means and the method of dynamic damping was conducted, based on which hydraulic system for dynamic quenching of oscillations has been developed. A mathematical sequence for determination of the operation delay time of the quencher was created. The parameters allow us to construct experimental model of hydraulic system for dynamic quenching of oscillations. The basic idea is the presence of feedback from the hydraulic system in the form of reed switch, which allows us in due time to turn on a pump and supply additional portion of hydraulic fluid for more efficient operation of the quencher. A hydraulic damping system which allows full vibroisolation is developed. At the expense of that, the average speed of operation is between 10–20 % of the period of soil cleavage.