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| Biography |
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| Master's port |
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Tovarchi IgorFaculty mechanical engineering and machinery Speciality: "Technology of mechanical engineering" Theme of master's work: "Improving quality and efficiency of part process, which based on surface-plastic deformation and ultrasonic processes"Scientific adviser: Michaylov Alexander Abstract on final work IntroductionThe development of modern mechanical engineering is characterised by creation of constructions and bulks of machines intended for working in various service conditions. These problems can be solved according to the requirements of economic and social development providing a concentration on efforts on improvement of quality, reliability, profitability and productivity of the equipment, decrease materials volume and power consumption. The search of the new methods which allow providing of the high efficiency, demanded accuracy and quality of the processed surfaces is very important. In this sense, the theoretical workings out, new ideas and increasing of possibilities of known methods as well are of special value. More than 80 % of machine’s details and devices fail on a cause of wear and losses of operational qualities. From here follows the necessity of improvement of physicomechanical characteristics of metal and geometrical parameters of working surfaces of details. Besides, it is necessary to aspire increasing of productivity of processing and economy of metals while using of progressive technological processes. Constant development of technologies nowadays demands use of the details with thin walls (for the economy of the material and weight reduction of construction as a whole). Their quantity considerably increases in amount of the details subjected to machining. Thin-walled products which provide high durability and density of configuration find wide application in the various industries and that is especially important, in areas of plane and rocket production, the cryogenic technics, pneumo- and hydro-equipment, engine-building, refrigerating machinery, space and military-industrial workings out [5]. From the point of view of the function-oriented approach it is the most difficult to manage the process of formation of the operational properties of details of machines. For influence on process of formation of operational characteristics at is superficial-plastic deformation it is necessary to consider as the convenient tool rational application of energy of an ultrasonic field [1]. Main purposes: - Theoretical research of the factors influencing quality of strengthening processing of thin-walled products, by orientation of technological influences in zones of operational features of details. - Synthesis of technological maintenance for ultrasonic strengthening processing of thin-walled products ; - Working out of the device raising rigidity of installation of details and the adaptation for processing; - Selection of rational modes of processing of thin-walled products on the basis of use of the ultrasonic phenomena; - Research of influence of processing on a roughness of the processed surface; - The influence of processing on the geometrical deviations of the surfaces of thin-walled products; - Working out of recommendations about achievement of best conditions which provide the most economic reception of necessary parameters of an upper layer condition. Work urgency Operational reliability of machines is defined basically by a qualitative condition of working surfaces of the details formed on finishing operations of technological processes (the is intense-deformed condition of an upper level, technological residual pressure, dynamics of loads, physicomechanical properties of a material, macro- and microgeometry, geometrical accuracy). That’s why important and initial for technology of mechanical engineering is improving of well-known and working out of new, scientifically well-observed, technically accessible and economically expedient technological processes of machining of working surfaces of details for increase of their operational characteristics. Despite successes in these areas a number of the important theoretical and practical questions has not found the reflexion in the function directed technological processes of reception and maintenance of demanded quality parametres . The effective and non-polluting way of strengthening processing of details by ultrasound is one of the perspective methods which allow to solve tasks in view. The basis of method is a process of technology which allows, varying technological modes of processing, to receive a surface with necessary physicomechanical properties. During processing there is a formation of the favorable intense-deformed condition of the upper layer of a material in thin-walled products, technological residual pressure in them, the best roughness, working surfaces which provide improvement of operational characteristic. So, the complex research of process of processing, studying the interrelation of dynamics indicators of loads of surfaces with processing modes, operational characteristics of contacting surfaces is important. Technical and economic efficiency of processes of the processing based on superficial plastic deformation of metal, is provided by: - Increasing of productivity and decrease in work volume input of producing of preparations and high-precision processing of details as thus can be excluded operational development, honing, heat treatment and other low-productive processes; - Economy of metal as a result of approach of a configuration of preparation to the form of details and machining of surfaces of details without shaving removal; decrease in the cost price of preparations and details of machines and devices; - improvements of quality and operational properties of details (wear resistance, durability, resistance of creep, etc.) and knots; - Reduction of expenses by operation of machines and devices as a result of improvement of quality and operational properties of details. Ultrasound use in addition allows to intensify processing process. This masters work observes the machining of thin-walled products of "rotation bodies" type will be considered. Thin-walled products can be processed methods of plastic deformation. Finishing processing is carried out at small working pressure p≤1,5σт and allows to improve bearing ability of an initial roughness of a surface (to increase relative basic length from 1-2 to 15-20 %). Thus the technological heredity is expressed especially brightly. The degree (U H) and depth is considerably raised by strengthening processing made at р>3σт. The processing of intermediate wall-strengthening modes ( 1,5σт≤р<3σт ) allows to improve bearing ability of parametres of a roughness and a sinuosity and to raise initial superficial micro-hardness on small depth, that is in a complex to raise bearing ability of a blanket (to reduce complex parametre C x at 10-20 times). The energy of the ultrasonic fluctuations, making essential impact on character of contact interaction of the tool and preparation helps to reach effective hardening with reduction of power influence. While using ultrasonic influence on the tool essential reduction of a friction in the deformation centre is provided. The equation for calculation of intensity of wear process in normal deterioration at constant working conditions and physicomechanical properties of a material depending on upper layer parametres is deduced in work [7]. Experimental researches of [7] resistance of the weariness spent on samples from a steel 30ChGS (НRС 35-37) have shown that the limit of endurance of samples at reduction of their roughness with Rа =0,74mkm to Rа =0,22mkm on the average increases by 14 % and service period more than in 3 times. The increase of durability of products can be provided by ultrasound application, that’s why it is possible to consider expedient the introduction of this operation in technological process. A review of existing research and development Topics like this were considered in many literary editions so attempts to use the energy of ultrasonic (US) fields for an intensification of processes of machining are known from the end of 30th years of the XX-th century. Prominent feature of a current state of physics and technics of ultrasound is the variety of its usage covering a frequency range from the heard threshold to frequencies in few megahertz and area of capacities from shares of milliwatt to dozens of watt with use of modulation of fluctuations along by amplitude, frequency and a phase. Small length of a wave causes beam character of distribution of US waves. Due to it the focusing of US waves starts to be widely applied by means of acoustic lenses, reflectors and radiators of the concave form. The last allows to concentrate sound energy receiving in the environment high values of intensity of a sound which are impossible to receive on a surface of traditional radiators of fluctuations. Modern focusing systems allow to form definite characteristics of direction of ultrasonic fluctuations (USF) and to control them. Such processing in the scientific and technical literature is called finish-strengthening and is widely used for the purpose of increase of durability and reliability of details of machines that explains not only reduction of high-rise parameters of a roughness and increase in superficial micro hardness, but also creation of compressing residual pressure. The tool is pressed to processed preparation with force Р = 500 – 5000 Н while usual processing of the pilot tube (without USF) that does not allow to use it to produce thin-walled details. Fluctuations of a tip by US frequency allow reducing of Р up to few times. It is caused by the contact of the tool fluctuating by US frequency and a processed surface of preparation. There is a blow where instant values of the efforts of impulse character exceed the surpass values of static efforts of a clip. Prominent feature US finishing-strengthening processing is occurrence on a surface of preparation of quickly alternating deformations of compression and shift [2]. It is known that the increase of amplitude USF up to 4 – 6 microns while diamond polishing promotes increase in micro hardness and reduction of high-rise parameters of a roughness of a surface of processed preparation. Some loss of hardening of surface is observed while the further increasing of amplitude which appears as reduction of micro hardness and increase in high-rise parameters of a roughness at the expense of formation layers out. At the same time, the increase of the amplitude of fluctuations from above 4 – 6 microns provides increasing of compressing residual pressure in the upper level of preparation and their location depth. It was offered to apply USF, modulated for amplitude by an additional sinusoidal signal with goal to increase in USF amplitude without decreasing the hardening, compressing residual pressure and their location depth. Both, amplitude and frequency modulation of USF diamond polisher can be used for creation on surfaces of processed preparations of regular micro reliefs that in essential degree will promote increase of operational properties of friction pairs. Thus unlike well-known methods of creation of regular micro reliefs vibrating heads on frequencies to 5 – 10 kHz, the usage of modulated USF is not interfaced to probability of strengthening of vibrations but opposite accompanied with their damping and carried out at essentially smaller efforts the surface-plastic deformation (SPD). Literature
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