Cylindrical Bushings Research Articles

PROCEDURE FOR DESIGN OF DOWNHOLE DAMPING DEVICES USING ELASTOMERS

The article is devoted to the problem of combating vibration and shock loads in the oil production industry. Described is a method of reducing loads due to the use of dampers in the design of devices. It is indicated that for damping vibration loads in mechanical engineering a wide range of design solutions is used using hydraulic, pneumatic and mechanical systems and devices. The article compares the use of springs and elastomers as a damping element in mechanical structures of downhole devices. It is also indicated that it is recommended to use experimentally obtained dependencies to select the damping material of the elastomer: with vibration of forced vibrations from 13.5 to 23.5 Hz, the density of the material should be increased, and with forced vibrations from 25 to 50 Hz, on the contrary, the density of the material should be reduced.As a vibration-isolated object, the article considers the installations of electrically driven centrifugal pumps (ESP), in which, due to unstable operating conditions, modules are often divided with a fall («flight») at the bottomhole due to fatigue destruction of the connecting elements. Two patented structural solutions to combat vibration and impact loads due to inclusion of a damping module with an elastomer substrate made in one case with an external conical surface and in the other in the form of a cylindrical bushing are presented.In recent years, there has been a trend towards a decrease in the diameter of wells and, accordingly, casing pipes. Therefore, an ESP arrangement with a damping module with a substrate made in the form of a cylindrical sleeve is most acceptable. Since in this design it is possible to increase the damping capacity of the module by increasing the thickness of its substrate.For this damper design, a method for calculating the relative longitudinal compression strain of its elastic substrate has been developed. It is shown that in order to ensure radial extension of levers by the required value, it is necessary and sufficient to determine the maximum diameter of the deformed (compressed) cylindrical rubber bushing, which at the same time acquires a barrel-like shape with a curvature of the generatrix depending on the rubber material: density and tightening factor.

Parametric optimization of curved-rectangular shaped magnetorheological finishing tool for external cylindrical surfaces

Finishing of cylindrical surfaces in nano-scale roughness level is important to improve the surface structure of various industrial components. The nanofinishing not only enhances the surface quality but also improve the durability and reliability the components. In the present research, a new tool is developed i.e. curved-rectangular shaped magnetorheological finishing tool which is used for precise finishing of cylindrical materials made of non-ferromagnetic materials. The tool consists of two set of magnetic arrangement which is fixed at an angle of 90o by means of a tool bracket. The magnets placed inside the cylindrical bush moves to and fro as per the circumferential of workpiece. To check the performance of this tool, the design of experiments using design expert software is conducted with different process parameters i.e. workpiece rotational speeds (400 rpm, 600 rpm and 800 rpm), mesh sizes of SiC abrasives (600, 800 and 1000) and mesh sizes of EIPs (200, 300 and 400) against the percentage change in surface roughness value. The results concluded that the higher material removal in terms of Ra value as 77% is found with workpiece rotational speed 400 rpm followed by 600 mesh size of SiC abrasives and 200 mesh size of EIPs with finishing time as 40 minutes.

On the influence of the pipe outer coating nonuniformity on the contact stresses arising under rigid bushes

The work is devoted to the formulation and construction of a solution in analytical form for the mechanical problem of contact interaction between a finite system of rigid cylindrical bushes and a pipe with an external coating, which has longitudinal nonuniformity. In industry and mechanical engineering, the presence of such additional coatings is required, for example, for protection the pipe main layer from external aggressive media, for its electrical or thermal insulation, etc. The nonuniformity of such a layer may be due to various additional requirements, as well as the obtaining process of this layer. When analyzing the stress-strain state of the pipe interacting with the bushes, it is necessary to take into account all the features. The paper shows that the mathematical model of the above-described interaction problem is a system of mixed integral equations containing integral operators of different types. Moreover, the resulting system includes functions describing the variable properties of the outer layer in the area of interaction with the bushings. The special approach described by the main theses in this paper makes it possible to obtain a solution in a form in which all complex functions are allocated as separate multipliers. This makes it possible to perform calculations even in cases where the coating is highly heterogeneous or consists of different materials.

Учет влияния перекоса в зазоре между плунжером и втулкой на величину утечек в авиационном аксиально-плунжерном насосе

The subject of study in the article is the amount of leaks of the working fluid in the gap between the plunger and the bushing of an aircraft axial-plunger pump, depending on the position of the plunger relative to the bushing. The level of fluid leaks in the gap between the plunger and the cylinder block bushing is a component of volumetric losses, affects the thermal state, wear, the state of the plunger-bushing pair, as well as the level of pressure pulsations of the working fluid and, ultimately, the change in the efficiency of the axial-plunger pump. Researches deal with the influence of piston defects in a bushing on losses through a gap between them that is not discovered in existent literature. The aim of this work is theoretical research of the influence of piston defect on the leakage of working liquid through a gap between the piston and cylindrical bushing in aviation axial-piston pump under workloads. The tasks are: it is necessary to define the losses quantity for the three cases: the axes of piston and bushing coincide; piston is displaced (axes are parallel) with a maximal eccentricity ε = 0.99; piston is twisted in a bushing so that the edges of piston touch a bushing. For the problem-solving methods as follows were used. The task of thin film laminar flow in a gap between piston and bushing was solved by a numeral method in finite-element software. Losses on a piston are considered as a sum of the losses, related to the motion of the piston at a speed W and losses due to the pressure gradient dp/dz. The results are: to obtain the laws of geometrical parameters influence on the losses amount investigation for one piston was undertaken in the first part of the study. It is marked that most losses take place for piston displaced in parallel, and the least - for twisted. Total losses for the real pump on different operational behaviors are considered and volume loss-of-flows are obtained in the second part of the article. Conclusions. Dependences of losses through a gap at the different gap sizes and relative length of bushing for twisted piston are first time obtained. The results allow estimating the losses quantity in a pump on the efficiency of his work at planning and exploitation.

RESEARCH OF THE TECHNOLOGY OF OPENING HOLES IN COMPACT AND POWDER MATERIALS

This article is devoted to one of the important problems of mechanical engineering, including processing by cutting and deploying in sintered antifriction powder material in optimal modes with maximum performance. The study was conducted for small diameter cylindrical bushings. Processing of bushings was carried out by reamers from high-speed and carbide tools on materials from porous powder and cast iron. It is established that the temperature of the tools should not exceed the permissible upper limits, for pressing the bushings, it is necessary to use planting with small strains in the cold state. Keywords: engine valve, bushing, powder material, cast iron, reamer, cold pressing.

A new bubble generator for creation of large quantity of bubbles with controlled diameters

A novel bubble generator was proposed and studied. The generator provides a considerable enhance of the bubble formation in two-phase flow. The generator comprises a number of hollow cylindrical bushings sequentially installed in the flow and deployed relative to each other by 90°. Each bush has two holes of equal diameters which are located at its side surface in the central plane of flow channel. Air is supplied to each bush. The bubble diameters and velocities were measured using the Phase Doppler Particle Analyzer (PDPA) at constant water flow rate equal to 1.38×10−5 m3/s and air flow rate in the range 12.5×10−7−0.5×10−5 m3/s. The tests showed that the distribution of the bubble diameters and their velocities remain almost the same in spite of change in air flow rate by a factor of 4. The diameter of bubbles was 0.6–0.8 mm and has 2 maximum points, namely, in regions of 630 µm and about 800 µm which correspond to the bubble size at the outlet from air holes, and the second maximum is a result of bubble coalescence. Their average velocity at the measurement point is close to zero that indicates a high vorticity of the flow.

Design of an automated line for pressing cylindrical bushings with screws

In the automotive industry, automated production and assembly lines are now used for the production of individual components. In particular, specialized single-purpose machines can incredibly shorten production or assembly time. This article deals with the design of a single-purpose device that is used for automated assembly of a roller bush with a screw. This assembly is subsequently used in the automotive heavy industry, resp. in agricultural and construction machinery.

Mathematical Interpretation of Open-Pit Dump Trucks Diesel Engine Durability

The durability of internal combustion engines is determined by the engine operating time, which is established by the service life of the most critical parts and assemblies that undergo normal mechanical abrasion in the process of engine operation. Factory diesel repair is performed when there is a need to repair the crankshaft. Current maintenance involving disassembly of the cylinder-piston group is performed due to the wear of piston rings and cylindrical bushings.

Friction Drilling of Cast Aluminum Alloy A380 Without Significant Petal Formation and Radial Fracture

Cast aluminum alloy A380 is one of the most commonly specified alloys that has light weight and exhibits excellent resistance to hot cracking, which makes it necessary in many industrial applications. An idea is investigated to generate a cylindrical bushing without significant petal formation and radial fracture that are expected to be obtained by friction drilling of cast metals. Three materials; namely, 316 stainless steel, Al6060 aluminum alloy, and red copper alloy are used in which each of them is located on the upper and lower surfaces of A380 workpiece, so achieving the idea of the functionally graded material. The process parameters were studied for reducing the resultant axial force, the gap between surfaces, and achieving a longer bushing without petal formation and radial fracture. Lower feed rate achieves minimum axial force and gap thickness with maximum bushing length for all material sandwiches. An optimized decision making by the help of fuzzy logic techniques is performed, revealing that red copper sandwich exhibits the optimal multiple performance characteristic index based on axial force, bushing length, gap thickness, and gap divergence.

Упрочнение цилиндрических втулок поперечной обкаткой плоскими плитами

Упрочнение цилиндрических втулок поперечной обкаткой плоскими плитами

Extending sleeve life in a borehole pipe by thermocyclic treatment

The wear resistance of cylindrical bushes in borehole pumps may be improved by thermocyclic treatment of the cast Kh12 steel blanks, including 3–4 cycles over the range 25–950°C, with 30-min holding at the elevated temperature. In that case, a relatively hard martensite layer (HRC 65) is formed at the bush’s working surface. The martensite layer is also characterized by elevated impact strength. The wear resistance of the bush may also be increased by the formation of considerable compressive stress (500 MPa) in a (5–6)-mm layer at the bush’s working surface under the influence of martensitic transformation at the end of heat treatment.

Plane stress-strain state of a circular cylindrical bushing due to a finite out-of-plane shear

The paper deals with the determination of the stress-strain state due to a finite longitudinal shear in a circular cylindrical bushing manufactured from the Mooney–Rivlin material. Some expressions for the internal stresses and displacements in the plane perpendicular to the longitudinal shear are obtained.

Principle and simulation of a high voltage bushing for a repetitive electron accelerator

A cylindrical graded bushing for the electron gun of the ASTRA-M pulsed repetitive accelerator was developed and simulated. In previous tests of the cylindrical graded bushing, primary reasons of electrical breakdown and degradation of dielectric elements were determined. Computational software was used to analyze the electric fields and simulate processes in the voltage grading system of the cylindrical bushing. This enabled proper modification and correction to the insulator structure for known problems. The new bushing has a conical structure instead of cylindrical one. The voltage graduation system uses nonsymmetrical voltage dividing for equal potential distribution along the grading electrodes. The grading electrodes provide shielding of organic dielectric surfaces from accelerated electrons and ultraviolet irradiation. Transmitted energy losses of up to 10% have been estimated in the nonsymmetrical voltage divider of conical bushing by simulating of high voltage pulse of 600 kV amplitude and 400 ns duration.

On optimization of the insulation of high-voltage coaxial bushing

This paper considers ways to improve the electric strength of a high-voltage bushing by decreasing the maximum electric intensity. For a coaxial cylindrical bushing with radii r 0 and r m > r 0, which result in an insulation gap (r m –r 0) with permittivity e0, this problem is solved with the use of an additional layer of insulation. This layer, with permittivity e > e0, is limited by radii r 0 and r e < r m . A simple algorithm to calculate an optimal thickness of this layer was obtained; the algorithm minimizes the maximum intensity as a function of radii r 0 and r m and relative permittivity e/e0 > 1.582. The algorithm is also transformed into an algorithm of synthesis of the noted layer thickness providing minimum intensity E m . The optimal relative values of all the dimensions of a high-voltage bushing as a function of the layer permittivity and level of reduction in the intensity E m are given in a form that is convenient for practical use.

Nonlinear interaction of finite longitudinal shear with finite torsion of a rubber-like bushing

In the framework of nonlinear elasticity, an example of longitudinal shear and torsion of a cylindrical elastomer bushing pressed between two rigid holders is used to study the dependence of torsional rigidity on the longitudinal shear and the dependence of the longitudinal shear rigidity on the angle of torsion for two potentials of the strain energy. An analytic model of interaction between the longitudinal shear and the transverse torsion is proposed in the asymptotic approximation.

Phenomenon of Narrowing of Holes in Cylindrical Bushings of U8-6MA2 Mud Pump After High-Frequency Hardening

The results of study of the occurrence of the phenomenon of narrowing of holes in cylindrical bushings of U8-6MA2 mud pump after high-frequency induction hardening are cited. The study of the occurrence of narrowing of holes helps predict the magnitude of allowance for final grinding operation. The physical aspect of this phenomenon is explained. The obtained results are recommended for use while fabricating bushing type of parts.

Sensitivity Analysis Application for Multibody System Synthesis

Nowadays computational techniques utilization is essential part of the technical development. Visual form of data acquisition from simulations or solving of technical problems is the most effective approach. In the field of computer-aided design (CAD) 3D graphic visualization is certaintybecause it makes it possible to design a very complicated parts and devices at a short time. Furthermore it enable to trace how these parts behave during operating regimes and make an optimization of required parameters. In this paper the engineering design of gravity orienting part tool for cylindrical bushings will be presented. Each of 3D components was designed in CAD software Pro/ENGINEER and MSC.ADAMS virtual prototype was created in simulation software. Using the tools of parametric analysis for refining model parameters in software MSC.ADAMS optimization of selected design and dynamic parameters of given designed system was carried out.

Nanographite analyzer of laser polarization

85 In experiments with the use of highpower laser sources, one often has to monitor the radiation polar� ization. As a rule, wellknown polarization analyzers that consist of a polarizer, a photodetector, and an electrical measuring instrument are used for this pur� pose. Polarizers may have different designs. Polarizers that consist of optically transparent birefringent crys� tals are widespread. The operating principle of such polarizers is based on the spatial separation of ordinary and extraordinary rays owing to the birefringence effect. Calcite is most frequently used as a birefringent crystal. The optical transmission range for calcite is 220-2300 nm. Therefore, such polarizers and, conse� quently, analyzers cannot operate in the medium IR region. Moreover, ordinary silicon or germanium pho� todetectors (PDs) that are included in widespread polarization analyzers also cannot operate in the medium IR spectral region because of the relatively large width of the forbidden band. Abstract—An optical analyzer of laser polarization has been designed and manufactured. The principle of operation of this analyzer is based on the recording of the polarizationdependent surface photocurrents in nanographite films. The analyzer does not contain additional optical elements and consists of a cylindrical bushing with a gauge of its angular position, a nanographite film grown on a silicon substrate, two parallel measurement electrodes placed on the film surface, and an electrical measuring instrument. The nanograph� ite film is placed on the bushing obliquely so that the measuring electrodes are parallel to the axial cross sec� tion of the bushing, which is oriented perpendicular to the film tilt plane. The analyzer can operate in the wavelength range from 266 to 4000 nm.

An analogy between radially-loaded rubber bush mountings and axially-loaded bonded rubber blocks

Abstract The validity of the widely-quoted experimental data for the reduced radial stiffness of a cylindrical rubber bush mounting of finite length is discussed by proposing an analogy between such a bush and two tandem cylindrical rubber blocks of circular cross-section which are axially loaded. Previously-derived expressions for the radial stiffness of a finite-length cylindrical bush and the apparent Young’s modulus of an axially-loaded bonded rubber block of circular cross-section are exploited. This leads to an adaptation of the data that incorporates the possible failure of the bushes due to internal rupture. The analytically-derived values of this stiffness are demonstrated to have improved agreement with these appropriately modified data. Representative numerical results are presented for a range of bushes in tabular and graphical forms.

Repairing and extending life of replacement steel parts of high-pressure oil and gas drilling pumps

Promising methods of strengthening fast-wearing friction couples of drilling pumps are described. Advantage of application of plasma-jet powder hard-facing for extending the service life of cylindrical bushings and valve systems is shown. The results of laboratory and industrial tests of plasma-jet wearresistant coats (powders PN 50T45 and PG-SR4) on rods of NB32-NB125 type of pumps are reported.