Різання та інструменти в технологічних системах

Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/62923

Офіційний сайт http://rits.khpi.edu.ua/

У збірнику публікуються наукові статті, у яких висвітлюються актуальні питання в області механічної обробки сучасних матеріалів із застосуванням високопродуктивних технологій, нових методів та вимірювальних приладів для контролю якості оброблених поверхонь і високоефективних різальних інструментів. Висвітлюються аспекти оптимізації й математичного моделювання на різних етапах технологічного процесу.

Рік заснування: 1966. Періодичність: 2 рази на рік. ISSN 2078-7405 (Print)

Новини

Збірник «Різання та інструменти в технологічних системах» включено до Переліку наукових фахових видань України з технічних наук до категорії «Б» згідно Наказу МОН України №409 від 17.03.2020 р.

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  • Ескіз
    Документ
    Causec of different waves of machined surfaces after up and down end-milling
    (Національний технічний університет "Харківський політехнічний інститут", 2022) Dyadya, S.; Kozlova, Olena; Karamushka, D.; Kushnir, E.
    In modern industry, among the methods of surface treatment is widely used end-milling. Under certain conditions of its use there are self-oscillations, which significantly affect the quality of the treated surface. Various techniques are used to study this influence, in particular, the comparison of the basic fragments of the oscillogram obtained by cutting with the treated surface. It is established that it is formed by the first and last wave of self-oscillations during up and down milling, respectively. But depending on the direction of feed step and the height of the waviness on it have different meanings. Therefore, it is important to determine the reasons that lead to this result. This paper considers the features of each direction of supply that affect the formation of the treated surface. When superimposing fragments of the oscillogram obtained by up milling, it is seen that the deviation of the first wave of self-oscillations from the position of elastic equilibrium starts from the point of incision of the cutter in the part. Therefore, the pitch of the wave on the treated surface depends on the feed and the number of cuts required to cut the first protrusion on the cutting surface. The paper presents a formula for determining the length of the base of this speech. When using it, the discrepancy between the calculated wave step on the treated surface and the measured one does not exceed 4%. In the case of down milling, the last section with waviness on the cutting surface, which is cut and affects the shape of the treated surface, has a shorter base length than the opposite. This is the first reason why the pitch of the wave in the down milling is smaller than in the up. Also at formation of wave on the processed surface at down milling the feature in the form of shift on a phase of waves of self oscillations on each following cut is observed. This increases the cutting time and the length of the cutting surface. Each subsequent forming depression is shifted towards the treated surface with a decrease in its deviation from the position of elastic equilibrium. However, the phase shift direction is opposite to the feed direction. This is the second reason why the pitch of the wave on the machined surface after the down milling is less than after the up. The calculation of the step of the wave of the treated surface after the down milling according to the results of the study of fragments of oscillograms shows that the error does not exceed 12% compared to the measured one.
  • Ескіз
    Документ
    Simulation of the machined surface after end milling with self-oscillations
    (Національний технічний університет "Харківський політехнічний інститут", 2021) Dyadya, S.; Kozlova, Ye.; Germashev, A.; Logominov, V.
    Thin-walled parts are widely used in the aviation industry. It is mainly carried out with end mills and is accompanied by self-oscillation during rough milling.They negatively affect the quality of the machined surface. Therefore, it is important to model it taking into account the dynamics of the milling process to predict the accuracy. In the early works of the authors, the mechanism of the profile forming of the machined surface was determined. In this case, the identity of the shape of the cutting surface and the oscillogram of part’s oscillations during milling is taken as a basis. The first wave of self-oscillations takes part in the shaping of the machined surface during cut-up milling with self-oscillation, and during cut-down milling - the last wave. The change in the distances of the cut depressions to the position of the elastic equilibrium of the part is periodically repeated from the maximum value to the minimum. Based on this, when modeling the waviness pitch of the machined surface after cut-up milling, it is necessary to know the feed rate and how many cuts were made by the tool from the largest to the smallest depression. When modeling the machined surface after cut-down milling, you need to know the length of the cutting surface. It is calculated based on cutting speed and cutting time. The formula for determining the waviness pitch after cut-down milling is derived taking into account the tool feed. The waviness height of the machined surface after cut-up and cut-down milling is determined as the difference between the largest and smallest depressions. To determine the size of the pitch and the height of the waviness, formulas are derived for converting electrical and time values of oscillograms into linear ones. These formulas also allow you to determine areas of the oscillogram with oscillations of the part during cutting and the resulting surface areas on the profilogram. The methods for modeling machined surfaces were tested after cut-up and cut-down milling with self-oscillation. In this case, the pitch and height of the waviness on the profilograms were compared with those calculated from the results of measurements of the oscillograms. Based on their analysis, refined formulas for calculating the waviness height have been derived. The error between the measurements of the waviness pitch and height and the calculated values is within 6%.