Cylinder Rod Research Articles

Повышение эксплуатационных свойств поверхности штока гидроцилиндра аддитивными технологиями

Повышение эксплуатационных свойств поверхности штока гидроцилиндра аддитивными технологиями

Mathematical model of the dynamics change departure of the jib system manipulator with the simultaneous movement of its links

In order to increase the productivity and reliability of the manipulator according to the normative and technical documentation, which regulates the safe operation of the manipulators, it is allowed to combine movements with the simultaneous movement of several elements of the boom system. As a result, the paper methodology reviewed for constructing a mathematical model in the plane of the departure change of the boom system of a manipulator with a load. The mathematical model is constructed from the calculation of three simultaneous movements, namely, the simultaneous movement of the first jib section, the second jib section, the telescopic jib section and the oscillation of the cargo. The functions of changing the kinematic and dynamic characteristics of the boom system with the simultaneous movement of its links are calculated. The construction of a mathematical model is carried out using Lagrange equations of the second kind. Moreover, the generalized coordinates of the manipulator model are taken as the angular coordinates of the position of the links of the boom system and the angular deviation from the vertical of the cargo. And the mechanical characteristics of the hydraulic drive are presented in the form of square dependencies between the acting forces and the speeds of movement of the hydraulic cylinder rods. The control of the drive elements is presented in the form of equations of the flow rate of the working fluid with a change in the area of the flow cross-section of the hydraulic distributor according to a linear law. As a result, the equation of motion of the manipulator is obtained, taking into account the influence of the inertial component of each link of the boom system and the influence of cargo oscillations on the dynamic loads of metalware elements and hydraulic drive elements. The developed mathematical model allows one to theoretically determine the effect of simultaneous movement of the first jib section, the second jib section and the telescopic jib section on cargo oscillation, as well as the effect of cargo oscillation on dynamic loads that occur in the boom system and manipulator hydraulic drive elements.

Study on straightness prediction of centerless grinding of slender rod based on PCA and Markov

In order to optimize the processing parameters of slender rods and achieve high-precision machining, a method of straightness prediction of centerless grinding based on PCA and Markov is proposed. A straightness measuring device for slender rod is developed to collect data. The accumulated straightness data is divided into typical processing conditions. The parameters that affect the straightness of centerless grinding of slender rod are analyzed based on PCA. According to the correlation between the parameters and the degree of influence on the straightness, the construction of the processing conditions is further simplified. On this basis, the straightness prediction model based on PCA and Markov is established to predict the processing conditions of centerless grinding of slender rods. Taking the centerless grinding of the piston rod of a hydraulic cylinder as an example, the machining experimental research is conducted. The predictive value is compared with the actual measured value, and the result shows that the average error rate is 3.94%, which indicates the effectiveness of the prediction method and meets the needs of actual production. This study provided technical support for parameters optimization of centerless grinding of slender rods parameter optimization and high-precision machining.

Study on straightening quality control for slender rod based on digital twin

For the technical problems of slender rod straightening quality control in the mechanical industry, a straightening quality control method for slender rod based on digital twin is proposed. According to the characteristics of the slender rod straightening process system, straightness detection device for slender rod suitable for production site is developed. Combined with the straightening process of the slender rod, straightening stroke model is given. Straightening quality control system for slender rod is established based on digital twin technology. Taking the piston rod of a large hydraulic cylinder as an example, straightening quality is controlled. The result shows that the theoretical calculation error rate of the straightening stroke is less than 0.5%. Straightness data of piston rod with quality control system is compared with straightness data of piston rod without quality control system. The result shows that the straightness consistency of the piston rod by quality control is good, and it is controlled within the range of 0-0.5mm. Straightening pass rate increased from 30% to 100%. This proves straightening quality control system for slender rod based on digital twin is effective. It can meet the needs of actual production. This study provides technical support for the optimization of slender rod straightening process parameters and high-precision machining.

Study of the effects of relative humidity and velocity on the friction characteristics of pneumatic cylinders

The movement of a piston rod in a pneumatic cylinder is directly affected by the air humidity in the atmosphere, especially in the case of piston rods without any means of protection or grease on their surfaces. In a pneumatic cylinder system, the friction between the piston rod and the rod seal is sliding friction, and it has a significant value that varies with the variation in the moisture on the piston rod’s surface. In this paper, an investigation of the friction characteristics of piston rods and rod seals in a pneumatic cylinder was carried out with different humidity and velocity values to understand the effect of lubricants on the moving parts of pneumatic systems in humid environments, where the friction characteristics of the displacements corresponding to the static and dynamic friction forces were displayed on a measuring device. The research results showed that the static friction forces tended to decrease by [Formula: see text] and that the dynamic friction forces tended to decrease by [Formula: see text] when the relative humidity increased from 51% to 99% at different velocities between 5 and 100 mm/s.

Hydraulic Control Research of Working Device of Grab Arm Cleaning Machine for Heavy Load and Large Depth

In this paper, a kind of heavy-duty and deep cleaning machine working device is studied. The closed-loop vector method is used to establish the kinematics model of the hydraulic cylinder rod mechanism, and the Lagrange dynamics is used to establish the dynamic model of working device. MATLAB, AMESim and ADAMS are used to provide excitation signal for the servo valve, build the hydraulic simulation model, and carry out kinematics and dynamics simulation. Using different signal excitation, the displacement tracking of the working device and the change of hydraulic pressure are observed. The results show that the closed-loop vector method and Lagrange dynamics are used to establish the kinematics and dynamics model of the working device, which facilitates the study of the working device of the cleaning machine; the simulation interface is stable, and the co-simulation of control arithmetic is achieved, hydraulic system and structural dynamics; the hydraulic pressure is obtained through the co-simulation analysis. The effect of cylinder displacement tracking and the change of hydraulic pressure provided the basis for working device design and optimization.

Development of a wind retrieval method for low-speed low-pressure flows for ExoMars

Forced convective heat transfer from three horizontally inclined rectangular-based cylinders (rods) has been studied experimentally under representative Martian near-surface air flows in the Aarhus Wind Tunnel Simulator (AWTS), Denmark. The testing campaign was developed for the HABIT (Habitability: Brines, Irradiation and Temperature) instrument, European payload on board the ExoMars 2022 Kazachok surface platform. The average heat transfer coefficient was determined from steady CO2 flows at a pressure of 9.9 mbar, an ambient temperature of ∼25 °C, and for horizontal free-stream velocities between 0.8 and 12 m/s. A retrieval algorithm to derive the wind speed from the average heat transfer coefficient estimated at each of the three HABIT Air Temperature Sensors (ATS) rods was calibrated within the AWTS. The ATS rods are placed one at the front of the instrument structure (ATS2) and two on the sides (ATS1 and ATS3); and under Martian atmospheric conditions these rods serve as cooling fins. Several relationships between the Nusselt number and the Reynolds and Prandtl numbers reported in the literature were evaluated to model convective heat transfer from the ATS rods. Where needed, corrections to account for radiative heat transfer within the AWTS were implemented. The final retrieval method demonstrated that wind speed can be retrieved for frontal winds in the range of 0–10 m/s, with an error of ±0.3 m/s, using the cooling profile of the ATS rod 3, and for lateral winds in the range of 0–6 m/s, with an error of ±0.3 m/s, using the ATS rod 2 cooling profile.

Improving the use of multi-link tractor-transport trains

The use of multi-link tractor-transport units has become one of the most effective methods of increasing agricultural productivity. When turning these aggregates, an increase in the width of the transport corridor serves as a deterrent. (Research purpose) The research purpose is in improving the safety of multi-link tractor trains by optimizing the width of the transport corridor in the turn with the use of additional devices that contribute to the formation of safe driving conditions for tractor-transport units. (Materials and methods) Authors have developed a design of agricultural machinery, the use of which allows meeting the safety conditions. Based on existing methods, authors have created special methods for determining the effect of the proposed device on the angle of rotation of the drawbar relative to the tractor and trailer. The article presents analytical dependencies for determining the turnability coefficient and the transmission coefficient of the device's impact on the drawbar rotation angle. (Results and discussion) It was found that the change in the angle of rotation of the guide wheels of the trailer is greatly influenced by the length of the retractable rod of the hydraulic cylinder of the device. It was found by experimental studies that in the proposed device, there is a direct link between the length of the retractable rod of the hydraulic cylinder and the angle of rotation of the plan-washer. (Conclusions) To ensure the necessary transport corridor of the unit, it is necessary to adjust the angle of rotation of the drawbar of both trailer links. As a result of the conducted research, the existing relationships that arise during the operation of the proposed device are confirmed and it is proved that the coefficient of impact transmission in both cases is equal to one.

Frequency domain modeling, analysis and verification of electro-hydraulic servo steering system for heavy vehicles

The electro-hydraulic servo steering system is one of the core components of a heavy vehicle, and frequency response characteristics of this system are essential to guarantee the vehicle flexibility. However, it is difficult to establish frequency domain model directly for the frequency response characteristics analysis due to the strong nonlinearity of steering trapezoidal mechanism and hydraulic power system in electro-hydraulic servo steering system. This paper proposes a simplified linearization analysis method for the electro-hydraulic servo steering system. By variable substitution defining the load flow and load pressure, and linear fit between double tire angles and cylinder displacement, the original model is simplified to a frequency domain model. Based on this model, the essential frequency response characteristics and the effects of key parameters to electro-hydraulic servo steering system can be obtained. Through the sweep frequency response analysis, the linearized frequency domain model is compared with the nonlinear time domain model and the actual test system, respectively. As shown in Bode plots, the amplitude-frequency phase-frequency characteristic curves of models match well, which verifies linearization analysis method and linear frequency domain model. The key parameters affecting the system frequency domain characteristics are the valve flow gain, the area of cylinder rodless and rod chamber, and the linearization coefficient between the left and right tire angles and so on. The electro-hydraulic servo steering system bandwidth is only 7.38 rad/s (1.17 Hz). This research is helpful for the design and optimization of heavy vehicle dynamic steering system.

Modification and ionic stimulation of hollow fiber membrane by electric field for water treatment

AbstractHollow fiber membrane (HF) is considered one of the prevalent materials for water treatment; its effectiveness is controlled by permeation and mechanical characteristics. In this study, HF membrane surface was stimulated using electrochemical technique, where binary system of stainless steel cylinder and graphite rod electrodes was used into electrolytic solution of sodium acetate 0.1 M as electrolyte. Two pH of acidic medium (pH = 3.5) and alkaline medium (pH = 8.5) were prepared and different potential between 2 and 10 V were applied. EDX analysis of HF membrane surface revealed the formation of sodium ions on the surface of HF membrane with maximum content of Na+ ions 1.84%. Also, HF membrane surface showed variation of roughness (R a) as, HF membrane surface may undergo distortion by using aggressive conditions of high electric potential (7.5–10 V), The measured raw HF membrane (R a) was 34.8 nm, while, after electrochemical modification in alkaline medium R a showed higher values 36, 37, and 41 nm using 2, 2.5, and 5 V, respectively. While, after electrochemical modification in acidic medium (R a) showed 35, 39, 42, 49, 52 nm for 2, 2.5, 5, 7.5, and 10 V, respectively. Moreover, tensile strength Young's modulus, break stress and break strain were measured after electrochemical modification in both acidic and alkaline mediums and maximum porosity value 76.84% was observed after 30 min in acidic medium.

Effects of geometry on resistance in elliptical pipe flows

This paper considers the significant role of cross-sectional geometry on resistance in co-axial pipe flows. We consider an axially flowing viscous fluid in between two long and thin elliptical coaxial cylinders, one inside the other. The outer cylinder is stationary, while the inner cylinder (rod) is free to move. The rod poses a resistance to the axial flow, while the viscous fluid poses a resistance to any motion of the rod. We show that the equations for flow in the axial direction – driven by a prescribed flux – and for flow within the cross-section of the domain – driven by the motion of the rod – decouple in the asymptotic limit of small cylinder aspect ratio into axial Poiseuille flow and transverse Stokes flow, respectively. The objective of this paper is to calculate numerically the axial and cross-sectional resistances and to determine their dependence on cross-sectional geometry – i.e. rod position and the ellipticities of the rod and bounding cylinder. We characterise axial resistance, first for three reduced parameter spaces that have not been fully analysed in the literature: (i) a circle in an ellipse, (ii) an ellipse in a circle and (iii) an ellipse in an ellipse of equal eccentricity and orientation, before extending our geometric parameter space to determine the overall optimal geometry to minimise axial flow resistance for fixed cross-sectional area. Cross-sectional resistance is characterised via coefficients in a Stokes resistance matrix and we highlight the interdependent effects of cross-sectional ellipticity and boundary interactions.

Mathematical modeling of a hydraulic drive for leveling the support table of a robotic drilling platform

The principle of moving a hydraulic drilling platform is described. To study the dynamics of transient response processes of hydraulic drive for leveling, a mathematical model was created. The structural diagrams of mathematical models of the actuator and hydraulic control valve are given. The time dependences of the spool positions of the hydraulic control valve and the hydraulic cylinder rod are presented. The dependences of pressure changes in the rod and piston cavities of the hydraulic cylinder are presented.

Temperature stability of the transformer position transducer for pneumatic cylinder

This paper presents the analysis and design of a transformer position sensor for pneumatic cylinder considering temperature stability. Two solenoid coils as excitation coil and pick up coil around cylinder are used for position transducer. The effects of temperature of aluminum cylinder and iron rod with different ferromagnetic materials on position sensor performance are analyzed and measured. We found that the effect of temperature dependence of shell resistivity is dominant, while the effect of permeability change is negligible. Based on the simulations and measurement we suggest simple method of temperature compensation.

Объемный гидропривод с последовательным подключением исполнительных гидродвигателей

The aim of the proposed work is theoretical and experimental studies of the performance of a single-channel hydraulic drive with a series connection of executive hydraulic cylinders and the de-velopment of recommendations for predicting their characteristics. The authors of the paper carried out a set of experimental studies and obtained the numerical kinematic, speed and power characteristics of a single-channel hydraulic drive with five hydraulic cylinders connected in series. It is shown that the nature of the kinematic connection is determined by the differentiation of the hydraulic cylinders. The speed of advancement of the piston of an indi-vidual hydraulic cylinder is determined by its serial number in the chain of hydraulic cylinders, while the highest speed of the piston movement is developed by the first hydraulic cylinder. The relative unevenness of the piston movement in comparison with the speed of the piston movement of the first hydraulic cylinder is determined by the differentiation of the hydraulic cylinder, while the hydraulic drive with the differentiation D = 2 has the greatest unevenness. It is shown that by the selection of the differentiation of the hydraulic cylinders, their stepwise arrangement and the displacement of the location of the bottom of the hydraulic cylinder, that it is possible to realize complex forms of the total trajectory of the points of attachment of the hydraulic cylinder rods. In the hydrostatic (power) hydraulic drive in the rod cavities of the hydraulic cylinders, depend-ing on the serial number of the hydraulic cylinder, the thrust on its rod and the differentiation set different pressure levels, and the lowest pressure will be in the piston cavity of the last hydraulic cylinder. With uniformly loaded hydraulic cylinders, the pressure in the piston cavities depends only on the number of the hydraulic cylinder and its differentiation. In a hydraulic drive with hydraulic cylinders of equal power, the last hydraulic cylinder will develop the greatest force at the lowest piston speed. In addition, the work also shows that the reproducibility of the positions of unloaded rods of hy-draulic cylinders of equal differentiation is not less than 1%. As a result of the experimental studies, a method was developed for the design of a volumetric hydraulic drive with sequential switching on of executive hydraulic cylinders, which can be used to solve the problems of hydrofication of me-chanical engineering production (bending presses, sheet stamping), in shipbuilding (ship slipways), in flexible production systems, industrial and warehouse logistics.

Improving the design of hydraulic cylinders used in hydraulic equipment for irrigation and drainage

The purpose of work – development of practical recommendations for modernization of hydraulic cylinders, widely used in irrigation and drainage and other agricultural equipment design created at the invention level (RU2702205) and the calculations to substantiate its basic geometric parameters. Research methods – to achieve the goal, a modern method of calculating the forces created by the magnetic fields of permanent magnets used in sealing devices of hydraulic cylinder rods was used; practical recommendations are given on the need to use such devices in practice. Research results and novelty – research results are recommended by both domestic and foreign research institutes, design and production structures of agricultural engineering for further study, refinement and its possible practical implementation. Conclusions – analyzing the proposed directions for the modernization of sealing devices of hydraulic cylinder rods, it can be concluded that the developed technical solution allows to increase the operational reliability of hydraulic equipment not only for irrigation and drainage, but also for other purpose of agricultural machinery.

The interaction of the main actuators of hydraulic excavators

The operation modes of the main actuators of hydraulic excavators during their joint operation in the process of rock excavation are considered. It is shown that the main mechanisms for turning the boom of the handle and the bucket are part of hydromechanical units consisting of an engine (hydraulic cylinder) and a main mechanism in which the engine (the cylinder and the rod itself) and elements of the working equipment (boom, handle or bucket) are the links of the mechanism. It has been established that the relationship between the parameters of the mechanical energy of the engines and the power parameters implemented on the driven (output) links of the mechanisms depend on the magnitude of the extension of the hydraulic cylinder rod. Mathematical models of the main mechanisms are developed. A computational experiment was carried out to determine the actual values of energy-power parameters implemented on the cutting edge of the bucket (teeth) during excavation of rocks at characteristic points of the excavator's working area, as well as reactive loads in the rota-tion mechanisms of the boom and stick. The proposed methodology for determining the operational parameters of the main mechanisms will allow us to estimate the range of changes in the power parameters implemented on the cutting edge of the bucket in the working area and to identify the relationship between active and reactive loads in the mechanisms due to the serial connection of hydromechanical units.

Restoration of hydraulic cylinder rods by method of ESA

During the operation of equipment, its structural elements under the influence of frictional forces and the environment are exposed to various types of wear. To maintain the rolling stock in a working condition, it is necessary to systematically carry out a large set of measures, such as maintenance, current and overhaul repairs with periodic replacement and restoration of worn parts and assemblies. It is obvious that maintaining the performance of modern machines requires high technical knowledge and modern technology. It is not uncommon for special machinery, including tractors and various agricultural vehicles, to be equipped with hydraulic power systems to perform various heavy operations. The actuating mechanisms of such systems are hydraulic cylinders. One of the main features of their design and operation is that the main and very precise part - the rod in working order is in an unprotected environment, namely in the open air. The specificity of the work of heavy equipment is high dust content, gas pollution and the presence of various abrasive materials in the work area in the form of stones and soil. Under these conditions, the precision, polished rods are subject to significant wear. In this paper, the possibility of restoring hydraulic cylinder rods for small types of wear (scratches and dents of a depth of no more than 0,3 mm) is considered by the method of electrospark alloying (ESA), with the creation of coatings on their working surfaces that are identical in their characteristics to the new ones. Electrode materials and processing modes were selected. Research was carried out to determine the dynamic microhardness of the created coating.

Efficient analysis of metal and dielectric rods in rectangular waveguide with ferrite magnetized transversely

ABSTRACTThis paper presents a new analytical method based on mode matching technique for a waveguide full of anisotropic material with rods. It is proved that mode matching technique is applicable for the waveguide with anisotropic materials. The problem is considered as a 2D electromagnetic problem assuming no field variation normal to the waveguide length. Incident and scattered fields from circular cylinder rods in ferrite medium are expanded with cylindrical modes, and the fields in the waveguide ports are expanded using progressive and regressive modal summations. In both regions, extraordinary wave number is considered for the fields. Finally, the hybrid mode matching between guided and cylindrical modes is done by projecting continuity equations in the circular boundary containing the rod. The fast Fourier transform is used to solve the matching in the presented method. It is shown, that the new method runs faster than commercial software packages, with very good accuracy.

Systematic Study on Hydraulic Cylinder of Farmland DTH Drilling Machine

Connecting and unloading rod is one of the important processes in the drilling process of DTH drilling rig. The unloading device not only affects the operator’s labor intensity and safety, but also affects the efficiency of drilling rig and the service life of drilling rod. Therefore, the research and design of unloading rod structure is of great significance to improve the efficiency of DTH drilling rig. Firstly, the selection of unloading rod hydraulic cylinder is analyzed, including the calculation of main parameters, cylinder design, piston design and calculation, cushioning and exhaust device. Secondly, the clamp rod hydraulic cylinder is designed and calculated, including the structure of the clamp rod cylinder, the clamp force calculation of the clamp rod cylinder and the wall thickness calculation of the clamp rod cylinder. Finally, we set the structure and parameters correctly to increase the efficiency of the hydraulic cylinder of the down-the-hole drill in the field operation.

Structure and Tribological Properties of Chromium Coatings Formed by Electrodeformation Cladding with Flexible Tools

The paper contains results of investigations on structure and tribotechnical properties of chromium coatings formed by a method of electrodeformation cladding with flexible tools (EDCFT). The purpose of these investigations is to assess prospects for application of the coatings as an alternative to galvanic chrome plating which is widely used in manufacturing hydraulic cylinder rods of metal-cutting machines. Rotary metal brushes with a wire pile made of 65Г-steel and 03Х17Н14М2-stainless steel have been used as a flexible tool. A compacted bar obtained by sintering a mixture of pure chromium powders and a nano-sized diamond-graphite blend UDDG has been employed as a donor material for EDCFT. According to results of the research it has been established that alloying elements of wire pile such as chromium and nickel are added to a coating composition while forming coatings a stainless steel brush. So in the case of using brushes with wire pile of 03X17H14M2-stainless steel the amount of chromium and nickel in a clad coating layer is 5.3 and 9.6 times higher in percentage, respectively, in comparison with the coating formed by a 65Г-steel brush that can contribute to improvement of coating corrosion resistance. At the same time, surface relief of the coating has a developed rough structure consisting of chromium microparticles having various size that are tightly packed and elongated in the direction of brush rotation and there are no flaws in the form of discontinuities and delaminations. Tribological tests have been performed under conditions of “boundary lubrication” on a rotary friction machine that implements friction of a rubber indenter on a flat surface of a rotating disk. According to data of the tribotechnical tests it has been ascertained that under conditions of “boundary friction” for such paired samples as “coated disc – rubber roller” chromium coatings formed by the EDCFT method, have the lowest values of a sliding friction coefficient (fтр = 0.023) which are 7.5 times lower than chromium coatings obtained by electroplating. At the same time the wear of rubber rollers in pairs with electroplated chromium coatings has turned out to be less than in pairs with the coating formed by the EDCFT method.