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Секция «Актуальные на учные проблемы в мире (глазами молодьш исследователей)»
УДК 621.923.9
СОВЕРШЕНСТВОВАНИЕ ТЕХНОЛОГИЧЕСКОГО ПРОЦЕССА АБРАЗИВНО-ЭКСТРУЗИОННОЙ ОБРАБОТКИ ДЕТАЛЕЙ
Д. Е. Амелько Научный руководитель - Л. П. Сысоева Руководитель по иностранному языку - О. В. Карчава
Сибирский государственный аэрокосмический университет имени академика М. Ф. Решетнева
Российская Федерация, 660037, г. Красноярск, просп. им. газ. «Красноярский рабочий», 31
Е-mail: [email protected]
Сформулированы основные направления совершенствования технологии абразивно-экструзионной обработки и рассмотрены некоторые принципы ее действия
Ключевые слова: абразивно-экструзионная обработка (АЭО), рабочая среда (РС), летательный аппарат, вязкоупругий, абразивное зерно, техпроцесс, течение, поток.
IMPROVEMENT OF TECHNOLOGICAL PROCESS OF ABRASIVE FLOW MACHINING OF DETAILS
D. E. Amelko Scientific Supervisor - L. P. Sysoeva Foreign Language Supervisor - O. V. Karchava
Reshetnev Siberian State Aerospace University 31, Krasnoyarsky Rabochy Av., Krasnoyarsk, 660037, Russian Federation Е-mail: [email protected]
The main directions of improvement of technology of abrasive flow machining are formulated and main principals of its functioning are considered.
Keywords: Abrasive Flow Machining (AFM), work medium, aircraft, viscoelastic, abrasive grain, technological process, flow
The share of the details with figurine surfaces sharply increased in modern mechanical engineering. Requirements to reliability of aircraft which details are operated in the conditions of high temperatures and hostile environment have been increased. And there appeared a necessity in improvement of quality of their processing. The most parts of difficult and high-load details of chemically resistant heatproof and heat-resisting alloys are made by hot investment casting and electro-erosion machining. The quality of such surface of work pieces is characterized by the raised roughness Ra = 20... 40 microns deep depth of thermally changed layer, existence of cracks, pores and gases in surface layer and high residual tensions. The details design complicates access of the cutting tool to the internal processed surfaces, causing the necessity of the use of non-standard methods of machining.
Today one of the most effective methods of machining of remote and figurine surfaces of details meeting requirements for accuracy, surface quality and productivity of processing is the method of the abrasive flow machining (AFM).
The AFM technology has a number of features considerably distinguishing it from traditional methods of finishing processing. The essence of the method consists of extrusion along the processed surfaces of the viscoelastic work mediums filled with abrasive grains.
Versus of cutting by the fixed abradant, the extrusive honing process has some features: part of the compressed abrasive mixture is in contact with the treated surface, equal to the area of the processed channel; the geometrical form of the tool and parameters of cutting change during the movement of abrasive "harness" along the processed surface owing to possible change of canal section and pressure of the medium; active grains are in long term contact with the processed surface, etc.
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The conducted studies of the various areas of AFM and developed theoretical bases of process defined real picture of current of the viscoelastic work medium (WM) allow to plan the main directions of improvement of technological process of AFM of details by improvement in productivity, reduction of the complexity of processing and achievement of uniformity of processing on length of the processed surface.
It is possible to reduce the complexity of the technological process of AFM due to change of design features of the devices creating the current of the medium by increasing the volume of a working chamber allowing to reduce quantity of operation cycles and auxiliary time for RM overpressing.
Stabilization of thermal balance of the system, for example by the heat exchanger, by cooling of the control system (oils in cylinders) and WM at the expense of volume increase of working chambers will allow to increase efficiency of WM because it was experimentally established that on AFM 56 % of heat allocated at friction, plastic deformation and cutting by active abrasive grains is spending on WM heating, and when heating WM above 40C cutting and edging of metal by micro and submicroasperities of abrasive grain stop and the process of its interaction with the processed surface passes into friction that affects efficiency of processing.
But reduction of extent of abrasive grain fixing at temperature increase of WM can be used for reduction of the AFM process complexity. Such mode consists of the use of one portion of one structure of WM (taking into account the necessary mass of WM for filling of each detail) at different stages of processing by changing its temperature.
The use of such a technology at the first stage of AFM operating allows to reduce surface roughness in ports from initial to Ra 0,8...1,1 microns, and at the second stage allows to reduce the extent of abrasive grains fixing - Ra 0,2.0,32 microns.
The proposed changes will provide a reduction of complexity of technological preparation and machining of aircraft details by 7,8 times.
When processing not rectilinear canals of variable lateral section and having the constructive elements causing local resistance there is a change of character of current WM and unevenness of surface treatment on canal length. The change of character of current of the medium changes the conditions of the abrasive grains contact with the treated surface. Sharp change of the shape or the size of section causes the emergence of considerable deformations in the medium and, therefore, change in conditions of machining. The application of special structures of WM, facilities and systems like the directing, leveling devices forming the demanded WM flow profile, blanch ducts, the devices creating adjustable counter-pressure and imposing vibrations on WM flow in the direction of its breakdown allow to regulate dynamical and technical characteristics of WM flow depending on the form and the size of section of the processed canal.
One of the main way of improvement of AFM quality and productivity of details of hardly processed materials is the development of new high-performance structures of WM providing the maximum productivity for specific conditions of processing: geometrical characteristics of the processed surfaces, state and qualities of the surface layer, demanded indicators of accuracy and a roughness by definition of optimum structure of components and their percentage ratio. In this way it is necessary to consider the use of polydisperse WM, various elasticizers, modifiers, SAS, CCF, chemically active substances, etc.
References
1. Levko V. A. Abrazivno-ekstryzionnaya obrabotka: sovremenniy yroven i teoreticheskie osnovi processa [Abrasive flow machining: modern level and theoretical bases of the process] : monograph. Krasnoyarsk, 2007. 228 p. (In Russ.)
2. Snetkov P. A. Sovershenstovanie tehnologii abrazivno-ekstryzionnoi obrabotki kanalov v detalyah letatelnih apparatov [Improvement of technology of abrasive flow machining of ports in details of aircraft]: thesis on competition of the Science degree. Candidate of Science. Krasnoyarsk, 2003. 181 p. (In Russ.)
3. Sysoyev S. K., Sysoyev A. S. Ekstryzionnoe honingovanie detalei letatelnih apparatov: teoriya, issledovaniya, praktika [Extrusive honing operation of aircraft details: theory, researches, practice]: monograph. Krasnoyarsk, 2005. 220 p. (In Russ.)
© AMenbKO fl. E., 2016
