ВЛИЯНИЕ СПОСОБА ОХЛАЖДЕНИЯ ЗОНЫ РЕЗАНИЯ НА УСЛОВИЯ СТРУЖКООБРАЗОВАНИЯ

The paper considers an influence of a cutting zone cooling method on the chip shape and thickening ratio while turning R35 steel with the hardness of НВ 1250 МРа. Cutting with various types of cooling - dry, compressed air and emulsion fog has been investigated in the paper. OPORTET RG-2 emulsol with emulsion concentration of 4% has been used as an active substation. Cutting tool is a turning cutter with a changeable square plate SNUN120408 made of Р25 hard alloy with multilayer wear-resistant coating, upper titanium nitride layer. Front plate surface is flat. Range of cutting speeds - 80-450 m/min, motions - 0,1-0,5 mm/rev, emulsion flow - 1,5-3,5 g/min and compressed air - 4,5-7,0 m3/h, cutting depth - 1,0 mm. In order to reduce a number of single investigations it is possible to use plans based on ЛПх-sequences.It has been shown that the method for cutting zone cooling exerts significant influence on conditions for chip formation. Regression equation describing influence of machining conditions on Ка-chip thickening ratio has been obtained in the paper. The range of cutting modes is extended while using emulsion fog for cooling. In the process of these modes chip is formed in the shape of short spiral fragments or elements. Favourable form of chips is ensured while using the following rate of emulsion - not more than 2 g/min. The investigations have made it possible to determine conditions required for cooling emulsion fog. In this case it has been observed minimum values in chip thickening ratio and chip shape that ensures its easy removal from cutting zone. While making dry turning values of Ка is higher not less than 15 % in comparison with other methods for cutting zone cooling.В статье рассмотрено влияние способа охлаждения зоны резания на форму и коэффициент утолщения стружки при точении стали R35 твердостью 1250 МПа. Исследовали резание при охлаждении всухую, сжатым воздухом и эмульсионным туманом. В качестве активной субстанции использовали эмульсол OPORTET RG-2, концентрация эмульсии - 4 %. Режущий инструмент - токарный резец со сменной квадратной пластиной SNUN120408 из твердого сплава Р25 с многослойным износостойким покрытием, верхний слой - нитрид титана, передняя поверхность пластины - плоская. Диапазон скоростей резания - 80-450 м/мин, подач - 0,1 -0,5 мм/об, расходов эмульсии - 1,5-3,5 г/мин и сжатого воздуха - 4,5-7,0 м3/ч. Глубина резания - 1,0 мм. Для сокращения количества единичных исследований можно использовать планы, базирующиеся на ЛПт-последовательностях.Показано, что способ охлаждения зоны резания оказывает существенное влияние на условия стружкообразования. Получено уравнение регрессии, описывающее влияние условий обработки на коэффициент утолщения стружки Ка.При охлаждении эмульсионным туманом расширяется диапазон режимов резания, при которых формируется стружка в виде коротких фрагментов спирали или элементная. Благоприятная форма стружки обеспечивается при расходе эмульсии не более чем 2 г/мин. В результате исследований определены условия охлаждения эмульсионным туманом, при которых наблюдаются наименьшие значения коэффициента утолщения стружки и форма стружки, обеспечивающая ее легкое удаление из зоны резания. При точении всухую значения Ка больше не менее чем на 15 % по сравнению с другими способами охлаждения зоны резания

3D Finite Element Modelling of Cutting Forces in Drilling Fibre Metal Laminates and Experimental Hole Quality Analysis

Machining Glass fibre aluminium reinforced epoxy (GLARE) is cumbersome due to distinctively different mechanical and thermal properties of its constituents, which makes it challenging to achieve damage-free holes with the acceptable surface quality. The proposed work focuses on the study of the machinability of thin (~2.5 mm) GLARE laminate. Drilling trials were conducted to analyse the effect of feed rate and spindle speed on the cutting forces and hole quality. The resulting hole quality metrics (surface roughness, hole size, circularity error, burr formation and delamination) were assessed using surface profilometry and optical scanning techniques. A three dimensional (3D) finite-element (FE) model of drilling GLARE laminate was also developed using ABAQUS/Explicit to help understand the mechanism of drilling GLARE. The homogenised ply-level response of GLARE laminate was considered in the FE model to predict cutting forces in the drilling process

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

Influence of some parameters of the electromachining on the state of the surface layer of elements of tool steel

Described in the paper investigations were aimed at determining the influence of the amperage, the time of discharge impulse and breaks between impulses in EDM processing of tool steel 56NiCrMoV7 on some parameters of the geometric surface structure. One stated that values of the impulse amperage and the time of discharge impulse had a significant influence on the state of the worked surface. The increase of these process parameters not only considerably worsening the surface roughness, but also generates existence of microcracks as a result of high temperatures in the discharges zone. Times of breaks between impulses didn't indicate the influence on parameters of the surface roughness and its topography.W procesie obróbki elektroerozyjnej(EDM) usunięcie materiału spowodowane jest wyładowaniami elektrycznymi pomiędzy elektrodą roboczą a przedmiotem obrabianym. Naddatek jest usuwany z przedmiotu obrabianego w wyniku oddziaływania zjawisk fizycznych spowodowanych wyładowaniami elektrycznymi. Najbardziej efektywnym obszarem zastosowania obróbki elektroerozyjnej jest obróbka materiałów o małej skrawalności. Na podstawie analizy literaturowej można stwierdzi, że największy wpływ na wydajno procesu DM i jako powierzchni obrobionej wielu materiałów konstrukcyjnych mają parametry elektryczne oraz niektóre inne parametry procesu. Celem badań było określenie wpływu natężenia prądu, czasu impulsu wyładowania i przerw między impulsami na wybrane parametry używane do opisu stanu powierzchni stali narzędziowych i nierdzewnych

Technological heredity when roller burnishing of ductile cast iron

559-565When processing EN GJSFP 450-10 ductile cast iron. The L18 Taguchi robust plan was used to optimize the processing conditions. The application of this method allowed determination of optimal conditions taking into account the conditions of pre-turning and burnishing. Due to optimization, the value of the S/N parameter increased by 25%. Best results were achieved when using a minimum turning and burnishing feed ratio, minimum turning speed, a large nose radius of the turning tool, maximum burnishing speed and indirect burnishing force in the presence of base oil. The phenomenon of technological heredity action was observed when roller burnishing, in other words, the influence of the pre-burnishing process conditions on the Ra surface roughness parameter after burnishing

On the Bonding Strength of Fe-Based Self-Fluxing Alloy Coating Deposited by Different Methods on the Steel Substrate

In the present paper, the bonding strength of Fe-based self-fluxing alloy coating deposited by plasma spraying, gluing and laser remelting and alloying on the steel substrate have been investigated. When flame melting, a globular structure is formed. Against the background of the solid solution carbide-boride phases are clearly distinguishable, between which the Fe-Fe2B and Fe-FeB eutectic colonies are situated. Laser remelting leads to the formation of metastable structures, reinforced with dendrites, consisting of alloyed Fe-α and Fe-γ. At the low laser beam speeds the coating is melted completely with the formation of a cast structure with the dendrites. When the laser beam speed is increased, the dendritic structure gets fragmented. Structures of coatings alloyed with B4C and remelted by the laser beam vary with the increase of the spot speed. The bonding strength of coating without subsequent remelting decreases by 4-5 times in comparison with remelted. The bonding strength of the reinforced glue coating has adhesive and adhesive-cohesive character. When the load increases in the coating, microcracks develop, which gradually spread to the center of the bonding surface. For plasma coatings after laser remelting without additional alloying, the maximum bonding strength is observed with the minimum laser beam speed. With increasing the laser beam speed it decreases almost 1.5 times. In glue coatings reinforced with B4C particulates by laser remelting, the bonding strength is lower by 1.2-1.4 times in comparison with plasma coating

The tribological studies of plasma-sprayed ceramic coatings

W artykule przedstawiono wpływ powłok ceramicznych Al2O3, Al2O3-B i Al2O3-Mo natryskiwanych plazmowo i rodzaju tarcia na właściwości tribologiczne, tj. współczynniki tarcia, zużycie, temperaturę węzła tarcia. Jako grubość powłok przyjęto 0,5-0,7 mm, materiałem, na który nakładano powłoki była stal C45.Plasma-sprayed coatings on the base of ceramic powders Al2O3, Al2O3-B and Al2O3-Mo were investigated. The thickness of coatings after processing was equal to 0.5–0.7 mm, the base material was steel C45. The analysis of metallographic samples of coatings allowed us to find that ceramic coatings consists of quasi-molten and then harden particles. The molten intensity of coating material Al2O3-B is more in comparison with other materials. Research using friction-wear machine of the Amsler type determined that values of the friction coefficient for coatings are practically equal when dry friction. The presence of gearbox oil decreases the friction coefficients of the researched coatings by about 3 to 4 times in comparison with dry friction conditions. During dry friction and friction with gearbox oil, the surface of Al2O3 coating abrades more quickly in comparison with coats alloyed. The relative solid wear of ceramic coating alloyed by boron is considerably smaller in comparison with other coatings. The presence of oil decreases relative solid wear of researched coatings more then 20 times in comparison with dry friction conditions according to the peculiarity of friction pair work. The presence of oil guarantees the removal of wear products successfully from the friction area

On the bonding strength of Fe-based self-fluxing alloy coating deposited by different methods on the steel substrate

In the present paper, the bonding strength of Fe-based self-fluxing alloy coating deposited by plasma spraying, gluing and laser remelting and alloying on the steel substrate have been investigated. When flame melting, a globular structure is formed. Against the background of the solid solution carbide-boride phases are clearly distinguishable, between which the Fe-Fe2B and Fe-FeB eutectic colonies are situated. Laser remelting leads to the formation of metastable structures, reinforced with dendrites, consisting of alloyed Fe-α and Fe-γ. At the low laser beam speeds the coating is melted completely with the formation of a cast structure with the dendrites. When the laser beam speed is increased, the dendritic structure gets fragmented. Structures of coatings alloyed with B4C and remelted by the laser beam vary with the increase of the spot speed. The bonding strength of coating without subsequent remelting decreases by 4-5 times in comparison with remelted. The bonding strength of the reinforced glue coating has adhesive and adhesive-cohesive character. When the load increases in the coating, microcracks develop, which gradually spread to the center of the bonding surface. For plasma coatings after laser remelting without additional alloying, the maximum bonding strength is observed with the minimum laser beam speed. With increasing the laser beam speed it decreases almost 1.5 times. In glue coatings reinforced with B4C particulates by laser remelting, the bonding strength is lower by 1.2-1.4 times in comparison with plasma coating

INFLUENCE OF CUTTING ZONE COOLING METHOD ON CHIP FORMING CONDITIONS

The paper considers an influence of a cutting zone cooling method on the chip shape and thickening ratio while turning R35 steel with the hardness of НВ 1250 МРа. Cutting with various types of cooling - dry, compressed air and emulsion fog has been investigated in the paper. OPORTET RG-2 emulsol with emulsion concentration of 4% has been used as an active substation. Cutting tool is a turning cutter with a changeable square plate SNUN120408 made of Р25 hard alloy with multilayer wear-resistant coating, upper titanium nitride layer. Front plate surface is flat. Range of cutting speeds - 80-450 m/min, motions - 0,1-0,5 mm/rev, emulsion flow - 1,5-3,5 g/min and compressed air - 4,5-7,0 m3/h, cutting depth - 1,0 mm. In order to reduce a number of single investigations it is possible to use plans based on ЛПх-sequences.It has been shown that the method for cutting zone cooling exerts significant influence on conditions for chip formation. Regression equation describing influence of machining conditions on Ка-chip thickening ratio has been obtained in the paper. The range of cutting modes is extended while using emulsion fog for cooling. In the process of these modes chip is formed in the shape of short spiral fragments or elements. Favourable form of chips is ensured while using the following rate of emulsion - not more than 2 g/min. The investigations have made it possible to determine conditions required for cooling emulsion fog. In this case it has been observed minimum values in chip thickening ratio and chip shape that ensures its easy removal from cutting zone. While making dry turning values of Ка is higher not less than 15 % in comparison with other methods for cutting zone cooling

On some mechanical properties and wear behavior of sintered bronze based composites reinforced with some aluminides microadditives

In the paper, the changes in some mechanical properties and wear behavior of CuSn10 sintered bronze and MMCs based on this bronze reinforced with composite ultrafine aluminide powders FeAl/15 % Al2O3, NiAl/15 % Al2O3 and Ti-46Al-8Cr are described. It was observed that the presence of aluminides in the MMCs leads to an increase in the hardness, but the flexural strength may increase or decrease depending on the type of aluminide. The presence of aluminides in the MMC reduces the wear rate considerably. It is decreased in the direction of FeAl/15 % Al2O3 → NiAl/15 % Al2O3 → Ti-46Al-8Cr aluminides and for the best MMC composition the advantage is about 20 times. In the MMCs wear process, micro-craters are formed on the contact surface and it is the principal reason of a decrease in the wear rate