Technological tests of a multi-seat device for vibro-shock processing of long parts of complex shape

The article deals with the issues related to the possibility of ensuring the indicators of quality of long complex-shaped parts by using vibration-impact processing in the technological process of their manufacturing using a special multi-seat device. The analysis of the design of representatives of long parts and the requirements for the quality of their surface layer, as well as the operational properties, made it possible to formulate the basic requirements for the design of multi-seat tools and develop a prototype for technological tests. The device allows processing two fragments of long parts and was used to establish the possibility of processing full-sized products and to establish optimal processing modes. Elements of the helicopter spars, which have the most complex design in the class of the considered parts, were used as fragments. Particular attention is paid to the processing of the inner surface of a complex shape and variable cross-section. The test results showed the possibility of using a multi-seat device for vibration-impact hardening treatment, which ensures the achievement of the specified parameters of the surface layer: surface roughness and microhardness with high process productivity.

Nonlinear dynamic analysis of gear system in shearer cutting section under wear failure

Gear wear failure is one of the important failures of the gear system in the shearer cutting section. To reveal the influence mechanism of shearer cutting gear wear on the system dynamic characteristics, considering coupling factors such as time-varying meshing stiffness, dynamic gear clearance, internal error excitation, end load constraint and bearing radial clearance under wear failure, an improved dynamic model of shearer drive gear system is introduced to present an in-depth investigation of uniform wear of gear teeth effect. The dynamic meshing stiffness of gears under different degrees of wear is analysed. Furthermore, the bifurcation diagram is utilized to observe the motion state of the system experiencing different excitation frequencies, support damping as well as terminal loads. It is demonstrated that the gear surface wear could bring a change in gear dynamic transmission error, vibration impact state and amplitude, which is mainly manifested in increasing the unstable area and the vibration amplitude of the gear system, providing a method for monitoring and diagnosing of gear surface faults.

Efficient PDC Bit Designs Reduced Vibrational Impact While Drilling with Rotary Steerable Systems in the Geological Conditions of the Yamalo-Nenets Autonomous District

This article is a description of a comprehensive engineering approach to new designs of PDC (Polycrystalline Diamond Compact) Bits and bottomhole equipment for efficient horizontal wells drilling in the Yamal-Nenets Autonomous Okrug (YNAO) fields with Rotary Steerable Systems (RSS) Point the Bit (PTB) type. The paper represents an analysis of the efficiency of drilling rocks of various hardness depending on the bits, the bottom hole assembly (BHA), and type of vibrations. In the Yamal region fields a main constraint of sub horizontal sections drilling performance for liner run in hole is the occurrence of vibrations. The predominant vibration types are Stick and Slip (S&S) and High Frequency Torsional Oscillations (HFTO). These types of vibrations often had to be reduced by limiting drilling regime (weight on bit (WOB), drill pipe (DP) RPM, and flow rate), which directly affected on the rate of penetration (ROP). To find solutions to this problem for drilling performance improvement, geological and geomechanically modeling of rock properties and an analysis of burst-files of vibrations (modeled in specialized software) were carried out based on downhole data. The studies have found key factors that cause the high vibration impact and reasons for premature wear of the PDC bits, which served as a basis for identifying the shortcomings of previous bit designs. Test beam experiments were also performed to assess the bits wear while drill-out of the casing accessories. The results formed the basis for development of new PDC bits designs using specialized software. As an output new 155.6/152.4 mm bits designs with an innovative cutting structure that considers the geological features and technical aspects of drilling liner sections in YNAO fields were manufactured. The new bit designs have significantly reduced vibration levels, improved ROP performance in the liner section using RSS PTB, and decreased the overall well construction time. These solutions open wide opportunities for their further implementation on other projects both in Russia and in other CIS countries.

Choosing Damping Parameters for the Inertial Orientation System

The article discusses criteria for selecting the vibration protection for the spacecraft inertial orientation system. The considered vibration protection system allows providing acceptable amplitude acceleration for the gyroscopic device sensitive elements under vibration impact on the device body during the spacecraft launching and high angular stability of the position of the sensitive elements relative to the inertial coordinate system during a long period of operation (15 years) in orbit. The proposed vibration protection system consists of shock absorbers (springs) with stable high elastic characteristics under all factors of operation in the outer space and dynamic vibration dampers. The article presents a method for determining the parameters of dynamic vibration dampers taking into account the characteristics of the shock absorber, critical for the damping system of an inertial device. The proposed method for adjusting dynamic vibration dampers consists in suppressing vibrations at the natural frequency f1 of the shock absorption system and providing acceptable values of the gain coefficients of the structure resonant vibration amplitudes near the natural frequency f1. Certain characteristics of the damping system allow realizing the permissible vibration amplification coefficients at resonance, without significantly affecting the level of vibration suppression in the natural frequency zone of the vibration protection object

ANALYTICAL SUBSTANTIATION OF THE RATIONAL MODE OF VIBRATION IMPACT ON THE HONEYCOMB

Проблема и цель. Заключается в том, чтобы теоретически обосновать режим виброочистки воскового сырья, при котором происходит отделение частиц воска от перговых гранул. Методология. В результате вибрационного воздействия на соты с пергой действует вынуждающая сила, которая должна быть больше силы трения между перговой гранулой и восковой основой ячейки сота, для того чтобы гранулы перги отделились. Увеличить силу, действующую на гранулу, можно увеличением либо амплитуды, либо частоты колебаний. Управление частотой является более рациональным по сравнению с управлением амплитудой. Для расчета частоты и амплитуды вынуждающей силы используются следующие данные: 2h – толщина рамки с сотами, h = 0,01м; a – длина рамки с сотами, a = 0,3м; b – ширина рамки с сотами, b = 0,4м; ρ – плотность, ρ = 326 кг/м³; N – натяжение; g – ускорение свободного падения, g = 9,81 м/c²; E – модуль упругости, E = 206000 МПа; G – модуль сдвига, G = 74000 Мпа; ν – коэффициент Пуассона, ν = 0,3; υ – коэффициент вязкости. Моделирование исследуемого процесса выполняется в среде Mathcad встроенными средствами статистической обработки. При этом осуществляется математическое моделирование в определенных рамках технологического процесса. Результаты. При воздействии на рамки с сотами, в которых есть перга, гармоническими колебаниями, возникает резонанс на малых частотах, что помогает ускорять процесс очистки. Заключение. Для наиболее качественной очистки воскового сырья от примесей необходимо воздействие вибрации с частотой в диапозоне от 14 до 16 Гц. При этом возникает резонанс, который уменьшает затраты энергии на данный процесс. Problem and purpose. The aim of the study is to theoretical justify the mode of vibration cleaning of wax feedstock, in which wax particles are separated from beads. Methodology. As a result of the vibration action, a force force is exerted on the feather honeycombs, which must be greater than the frictional force, in order for the feather pellets to separate from the wax cells of the honeycombs. To calculate the frequency and amplitude of the force, the following data 2h are used - the thickness of the frame with cells, h = 0.01m; a is the length of the frame with cells, a = 0.3m; b is the width of the frame with cells, b = 0.4m; ρ - density, ρ = 326 kg/m3 ; N - tension; g - acceleration of free fall, g = 9.81 m/c2 ; E - modulus of elasticity, E = 206000 MPa; G - shear modulus, G = 74000 MPa; v is Poisson's coefficient, v = 0.3; υ - viscosity coefficient. Results. When acting on frames with cells in which there is a feather, harmonic oscillations, resonance at low frequencies occurs, which helps to accelerate the cleaning process. Conclusion. For the highest quality purification of wax raw materials from impurities, vibration is necessary with a frequency in the diapozone from 14 to 16. At the same time, a resonance occurs that reduces the energy consumption for this process.

Dynamic Analysis of Percussion Drilling System under Harmonic Impact

As a new efficient rock-breaking technology, harmonic impact drilling technology has received great attention, but the research on its rock-breaking mechanism is insufficient, which limits its development. Based on the theory of vibration, a simplified model of high-frequency harmonic vibration impact system is established in this paper. The numerical model was solved by Matlab and the motion equations of drill bit and rock at different stages of motion are obtained, respectively. Based on the factor analysis of the mathematical model, the dynamic characteristics of the impact system under harmonic excitation are studied. Finally, numerical simulations are carried out to further analyze the drilling effect of harmonic impact drilling and verify the correctness of the simplified model. The results show that when the excitation frequency equals the resonance frequency of rock, the vibration displacement of rock reaches the peak value. The drilling speed is greatly increased by harmonic impact drilling compared with conventional drilling.

ANALYSIS OF ACTIVE BUCKET DESIGNS OF OPEN-PIT AND CONSTRUCTION EXCVATORS

The designs of active buckets are analyzed. It is revealed that dynamic impact of buckets on the rock mass can be vibrational or impact. The entire bucket, its front wall, or individual vibration impact devices mounted in the front wall can serve as a dynamic actuator. The drive of the active elements can be electromagnetic, hydromechanical, pneumatic or hydraulic. It is noted that the most successful design of the active bucket is the impact teeth built into the bucket with a pneumatic drive. It is concluded that the most productive idea is an active bucket with built-in impact devices and a hydraulic drive.

Plastic Shaping of Concentrator-Waveguide Tip for Ultrasound Endovascular Ablation

One of the most effective methods of treating intravascular formations at present is the use of stepped ultrasonic waveguide systems of a tubular type (concentrators-waveguides) with a hollow spherical tip, the presence of which makesit possible to supply liquid media to the dislocation zone of an intravascular formation with the aim of additional cavitation effect and as efficiently as possible. destroy intravascular formations due to vibration impact. Based on the results of the analysis on the features of the existing shaping methods for obtaining a hollow spherical tip of the concentrator-waveguide, it is advisable to use methods of plastic deformation – expansion and crimping. The paper presents results of preliminary calculations, numerical modeling and experimental studies of tip shaping processes of the concentrator-waveguide by distribution and crimping. On the basis of the finite element method in the environment of the ABAQUS software package, modeling of the expansion and crimping of a pipe billet was carried out, which has made it possible to: evaluate the stress-strain state of the deformable conical section of the billet, the change in wall thickness during the forming process and calculate the length of the billet for the design of the conical section; to establish the patterns of the influence of geometric parameters on the power modes of the distribution process; to set the parameters of the modes of forming the tip of the concentrator-waveguide by the method of distribution and crimping, which ensure the formation of the required geometry. The obtained results of preliminary calculation, numerical modeling and experimental studies of tip shaping processes of the concentrator-waveguide by distribution and crimping have similar values, which confirms the correctness of using both the method of preliminary calculation and numerical modeling in the development of the technology for manufacturing the concentrator-waveguide.