Shaft Surface Research Articles

Abrasive jet machining for the microprofile control patterning of herringbone grooves

Fluid bearings have features of high speed and high rotation accuracy, and therefore, they are used in spindle motors of hard disk drives, cooling fans of central processing units, and other devices. Further, these bearings have microherringbone grooves on the shaft or sleeve inner surface that help generate dynamic pressure in the lubricant fluid around the shaft. Although the depth of the groove is constant, dynamic pressure can be increased by decreasing the depth from both ends to the central corner of each groove on a micron scale. This study aims to verify the effect of sloped herringbone grooves using computational fluid dynamics (CFD) analysis and to develop a new microfabrication method for manufacturing microsloped herringbone grooves on the shaft surface using abrasive jet machining. The generated dynamic pressure is analyzed using CFD; the results indicated that the sloped herringbone grooves result in an increase in the dynamic pressure at the groove tips and cause a decrease in the fluctuations in dynamic pressure in the circumferential direction.

Subsurface Compressor System Improves Gas Production in Unconventional Reservoirs

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 201138, “Liquid Removal To Improve Gas Production and Recoverable Reserves in Unconventional Liquid-Rich Reservoirs by Subsurface Wet Gas Compression,” by Lukas Nader, SPE, David Biddick, SPE, and Herman Artinian, SPE, Upwing Energy, et al., prepared for the 2020 SPE Virtual Artificial Lift Conference and Exhibition—Americas, 10–12 November. The paper has not been peer reviewed. This paper describes an artificial lift technology, a subsurface compressor system (SCS), that simultaneously removes liquids, increases gas production, and improves recoverable reserves in gas wells. The subsurface compressor can reverse the vicious cycle of liquid loading, which decreases gas production from a gas well and leads to premature abandonment, by creating a virtuous cycle of increased gas and condensate production. The first field trial of the technology in an unconventional shale gas well supports the mechanism of subsurface gas compression and its benefit to unconventional gas production. The SCS This paper focuses on the latest deployed design. As with all SCS systems, this unit has three major components (Fig. 1). High-Speed Motor. The motor is a four-pole, high-speed, permanent-magnet (PM) synchronous topology. The motor maximum operating speed is 50,000 rev/min, with a 55,000-rev/min overspeed. Surface-mounted PMs are retained on the shaft surface. A sine filter is also used to minimize harmonic losses in the rotor, eliminating the need for active cooling flow in the rotor cavity. With the motor housing hermetically sealed from the environment and maintaining a low pressure within the housing, a minimum life of 20 years is expected from the electrical motor section. The motor rotor is levitated with passive magnetic bearings, requiring no lubrication or a pressurized air source, to support the high-speed rotating shafts. Magnetic Coupling. The magnetic coupling consists of three major components: the male and female ends of the magnetic coupling as well as the isolation can in between. The female end of the magnetic coupling is attached directly to the motor. The isolation can is used to seal the female magnetic coupling section hermetically within the body of the PM motor from the environment. Using a magnetic coupling to transmit torque through an isolation can is one of the key features of the protectorless, rotating, sealless motor system to ensure reliability of the motor. Hybrid Wet Gas Compressor. The compressor is a multistage hybrid axial flow wet compressor. The key advantage of this proprietary compressor design is its relatively straight flow path compared with those of centrifugal compressors. When the flow path is straight, with little change of direction, the heavier constituents, including liquids and solids, will follow the gas phase because there is little or no centrifugal force to separate the high-density phases from the low-density one. Also, erosion of the compressor parts is minimized by the straight flow pattern because of the lower probability of impingements of solid particles on the compressor internal surfaces compared with the torturous internal paths of centrifugal compressors. The remainder of the system, as well as the deployment, is very similar to an electrical submersible pump.

Analysis on Active Hydromagnetic Journal Bearing using Ansys

In this study Active hydromagnetic journal bearing is designed and analysed by using ANSYS tool. Active Hydromagnetic journal bearing is a combination of Hydrodynamic journal bearing & Active magnetic bearing. We know that hydrodynamic journal bearing used to low speed and high load carrying capacity & its drawback is at high-speed shaft surface is come in contact and there wear also happen. In this condition hydrodynamic bearing also damages from contaminants as dirt or ash, also in the rise in temperature. In the active magnetic bearing is used to high speed and low load carrying capacity. When increasing load carrying capacity of active hydromagnetic bearing, it also increases design of active hydromagnetic bearing. When combining Hydrodynamic journal bearing & Active magnetic bearing it reduces drawback of both bearing. It working on high speed and high load carrying capacity. When combining both bearing considering main parameter is clearance in hydrodynamic journal bearing & Air gap in active magnetic bearing.

The analysis of fretting fatigue in forced-in joint with the induction-hardened shaft

Subject to the analysis was a tribological kinematic pair consisting of shaft and sleeve, both made of C45 steel. The elements were joined by pressing with the 0.02 mm tolerance. The shaft was subjected to the finishing and strengthening treatment consisting in induction hardening. The tribological kinematic pair made in such way was tested on a fatigue testing machine, which permitted obtaining a rotational bending moment. Macroscopic investigations of the unhardened shaft demonstrated, on the shaft surface, the traces of fretting wear in the form of a ring of the uniform width comprising the entire axle seat circumference. Based on the test results, it may be concluded that the use of the shaft induction hardening process has caused the reduction of fretting wear development compared to shafts without additional treatment. In this case, Wear traces in the form of small diameter ring comprising the entire shaft circumference are observed on one side of the shaft axle seat.

Laboratory Investigation of Hollow and Solid Shaft Helical Soil Nail by Displacement Controlled Pullout Testing

A sequence of laboratory pullout tests was conducted to examine the installation and pullout behavior of hollow and solid shaft helical soil nails. The methodology involves installation and corresponding pullout testing of 12 mm, 14 mm, 16 mm and 18 mm hollow and solid shaft helical soil nails with varying number of helical plates between single to triple and shaft surface roughness from smooth to rough using a displacement-controlled apparatus. A total of 18 different helical soil nail combinations were investigated under surcharge pressures 5 kPa, 12.5 kPa, 25 kPa, and 50 kPa to examine the influence of shaft dimeter, shaft roughness, number of helices, pitch, interaction friction angle, embedment depth ratio on both installation and pullout capacity. Using the pullout capacities and corresponding installation torque, capacity-to-torque ratio (Kt) relationship was also established which yielded ranges of 19 m−1 to 61 m−1 and 23 m−1 to 58 m−1 for hollow and solid shafts, respectively. Moreover, interaction friction angles depicted that with similar number of helices, an increase of 25% in diameter of hollow shaft helical soil nail renders equivalent reinforcing action to a corresponding solid shaft. Also, for both hollow and solid shafts, double helical soil nails were observed to show the maximum efficiency, while the effect of number of helices was found to diminish beyond the embedment ratio of 11. Within the pitch range of 30–35.5 mm, pullout response for both hollow and solid shafts were found to be linearly dependent on its installation.

Wear on radial lip seals: a numerical study of the influence on the sealing mechanism

In this paper a numerical approach is applied to analyse the influence of wear on the lubrication and sealing mechanism of radial lip seals. A three-dimensional multi-scale mechanical model is presented. This allows to simulate the macroscopic deformation of the entire radial lip seal and the microscopic deformations in the contact area between the sealing edge and the shaft surface. Furthermore, different wear band widths and surface roughness of sealing edges can be analysed efficiently. In the context of this paper, measurement results of radial lip seals in different wear states out of test runs are applied. The simulation results of the different sealing edges are compared. This allows drawing conclusions about the influence of wear on the performance of radial lip seals. This leads to a better understanding of the potential failure mechanisms of radial lip seals.

An Investigation of Shaft Failure on Induced Draft Fan in A Steam Power Plant

A failure phenomenon on induced draft fan (IDF) shaft became a crucial attention in Power Plant with capacity 350 MW because the failure is catastrophic without early warning information. Also, the failures on the IDF shaft occurred in a short period within two months. This paper reported an investigation and evaluation of the root cause of the failure by vibration data monitoring and material analysis. The objective of the investigation and evaluation is to identify the main root cause and specific symptoms of IDF shaft failure. According to the data collection and analysis result, each phenomenon indicated an identical vibration pattern, however, the duration of each step is different. A series of tests of shaft samples was carried out to get comprehensive information, such as chemical composition test, tensile test, hardness test, microstructural examination (SEM), and fractography examination. The shaft repair procedure was also evaluated. The results were showed that multi initial of micro-scratch and martensitic embrittlement played an important role in the shaft failure. Micro-scratch triggered high-stress concentration on shaft surface. Martensitic embrittlement was found on weld metal and heat-affected zone.

Mathematical model of a radial sliding bearing with a porous layer on its operating surface with a low-melting metal coating on shaft surface

The paper considers the steady flow of a liquid lubricant and a melt of a low-melting metal coating of the shaft surface, which have viscous rheological properties in the operating clearance of an endless radial sliding bearing, as well as in the body of the porous coating of the surface of bearing bush. In order to solve this problem, the authors used the equation of the movement of viscous lubricant for a thin layer, the equation of continuity and also the equation describing the radius of the molten contour of the fusible coating of the shaft surface, taking into account the rate of dissipation of mechanical energy. Having averaged the acceleration of the movement of the liquid lubricant in the operating clearance, the authors obtained the dependence for the contour of the molten coating of the shaft surface. As a result of the integration of the obtained dependence, the expression was found that allowed solving the function characterizing the contour of the molten surface of the coating by the method of successive approximations. Using the well-known method of finding an exact self-modal solution, the velocity field and pressure in the lubricating and porous layer, as well as the load capacity and friction force, were found. On the basis of the performed theoretical studies, the experimental study was carried out taking into account the parameters characterizing the melt of a low-melting metal coating, as well as a porous coating on the surface of the bearing bush and the rheological properties of a viscous lubricant. As a result, the original expression was obtained for the calculation of the load capacity of a radial bearing and the magnitude of the friction force in the range under the following loading conditions v=0.5÷3 m/s, σ=2÷7 MPa. The research results can be used in mechanical engineering, aircraft construction, instrument engineering, where the supply of lubricant is associated with great difficulties.

An Experimental Study of Contact Temperatures at Sealing Interface against Varying Shaft Surfaces

Increased temperatures at the sealing interface between the seal and shaft can reduce the working life of a seal through elastomer aging, swelling and increased friction. Degradation of the seal due to increased temperatures can cause pre-mature failure, wear and leakage. There is no such thing as a perfect seal; each application has requirements to cater to the needs of each system. For radial oil seals in helicopter gearboxes, the contact temperatures at the sealing interface are a critical parameter to consider. In this manuscript, investigating the factors that influence the temperatures at the contact interface shed light on the operating parameters that cause an increase in contact temperatures. Four varying shaft coatings are tested against three seal spring loads for a range of sliding velocities between 5–25 ms−1 to reproduce conditions of the gearbox. The study reveals an optimum seal spring of 12 oz, with a circumferential load of 3.34 N for lowest temperatures at the interface. Higher springs of 14 oz and lower springs of 8.5 oz both cause increased temperatures at the interface. Additionally, the need for surface coatings on the shaft is re-enforced through experimental evidence demonstrated by comparing temperatures reached between a plain stainless steel shaft and three surface coated shafts. Chrome plating shafts are undesirable due to the ‘polishing’ in effect they experience. The results of this study build on this by showing that chrome plated shafts have higher temperatures at the interface, aggravating any wear or polishing in of that surface. Contact temperatures with Tungsten carbide and Chrome oxide coatings remain within the expected temperature rise. Lastly, microscopically ‘rougher’ surfaces result in increased temperatures in contrast to surface coatings within the specified range of roughness as provided by DIN 3760/61/ISO 6194.

A Model of Diameter Measurement Based on the Machine Vision

If the shaft diameter can be measured in-situ during the finishing process, the closed-loop control of the shaft diameter processing process can be realized and the machining accuracy can be improved. Present work studies the measurement of shaft diameter with the structured light system composed of a laser linear light source and a camera. The shaft is a kind of part with rotationally symmetric structure. When the linear structured light irradiates the surface of the shaft, a light stripe will be formed, and the light stripe is a part of the ellipse. Therefore, the in-situ measurement of the shaft diameter can be realized by the light stripe and the rotational symmetry of the shaft. The measurement model of shaft diameter is established by the ellipse formed by the intersection of the light plane and the measured shaft surface. Firstly, in the camera coordinate system, normal vector of the light plane and the coordinates of the ellipse center are obtained by the calibration; then, the equation of oblique elliptic cone is established by taking the ellipse as the bottom and the optical center of the camera as the top. Next, the measurement model of shaft diameter is obtained by the established oblique elliptic cone equation and theoretical image plane equation. Finally, the accuracy of the measurement model of shaft diameter is tested by the checkerboard calibration plate and a lathe. The test results show that the measurement model of shaft diameter is correct, and when the shaft diameter is 36.162mm, the speed is 1250r/min, the maximum average measurement error is 0.019mm. The measurement accuracy meets the engineering requirement.

ХМАРНА АВТОМАТИЗОВАНА СИСТЕМА ІНТЕЛЕКТУАЛЬНОЇ ПІДТРИМКИ ПРИЙНЯТТЯ РІШЕНЬ ДЛЯ ТЕХНОЛОГІЧНИХ ПРОЦЕСІВ

Праця присвячена вирішенню завдання оптимізації технологічного процесу відновлення й зміцнення поверхонь валів зі сталі шляхом реалізації методу й узагальненої моделі ланцюга абстрактних технологічних процесів у вигляді хмарної автоматизованої системи інтелектуальної підтримки прийняття рішень. Означене дає можливість розв’язати задачу побудови оптимізованого ланцюга технологічного процесу відновлення й зміцнення поверхонь валів із вибором раціонального процесу серед альтернативних згідно з завданням. У роботі проаналізовано абстрактний технологічний процес, його властивості, методи переходу до конкретного технологічного процесу, інформаційну модель та методи її одержання, абстрактні експертні системи, формалізацію підмножини абстрактних експертних систем, рекомендаційних систем, а також розглянуто технологічні аспекти реалізації інтелектуальної підтримки прийняття рішень технологічного процесу як хмарного сервісу, перевірки відповідності реальних характеристик, властивостей, поведінки автоматизованої системи очікуваним.

Method of Real-Time Wellbore Surface Reconstruction Based on Spiral Contour

A wellbore surface is an irregular surface structure. The distribution of points on the wellbore surface measured based on the drilling diameter is not uniform. Thus, the conventional modeling method based on a point cloud cannot satisfy the needs of real-time measurement updating and wellbore display. This study proposes a spiral profile method for drilling shaft surface reconstruction. Scattered data along the drilling diameter are measured, and an inverse distance weighting cylindrical space surface algorithm with iterative interpolation is used to obtain the spiral angle and pitch of a relatively homogeneous helical contour line along the surface of the shaft. Using sets of four adjacent points in the spiral, quadrilaterals are formed, and then all obtained quadrilaterals are used to form the wellbore inner surface structure. This method can further construct the outer surface spiral contour line to advance the quadrilateral surface to the spatial hexahedron structure. The caliper and gamma measurement data obtained from the calibrated wellbore were used to verify the real-time surface reconstruction and fusion while drilling. The homogenized reconstructed surface profile is more than 99.5% similar to the actual measurement. Proved by experiment and application, this method has very high real-time performance, and the three-dimensional stereo imaging wellbore with additional gamma attributes has good visual effects.

Helicopter Shaft Heating Parameters for Polyamide-11 Coating

In this study, the heating parameters required for polyamide-11 (P11) coating of the helicopter shaft were investigated. The torsion value created by the force applied to the middle of the helicopter's shaft is measured. Heating before coating affects the torsion value of the shaft. A new heating mechanism has been designed to cover the shaft surface without changing the torsion value of the shaft. Thus, the coating surface is left inside the furnace and the torsion measurement area outside of the furnace. Taguchi method was used to determine heating parameters such as furnace type, initial temperature and heating time. The heating process was performed by connecting K type probes to the shaft surface and temperature changes were recorded. It has been determined that with the fanless furnace, the coating surface does not reach the required minimum temperature, the shaft surface reaches the sufficient temperature with the fanned furnace, and PA11 coating can be applied effectively.

Determination of the cutting force components while milling cylindrical surfaces with an oriented tool

Purpose. Construction of a general modular mathematical spatial model of the removal allowance process and shaping when milling round surfaces of rotation, such as camshaft necks, cylindrical surfaces of gearbox shafts and others. Determination of the components of the cutting forces when machining with crossed axes of the milling cutter and part in order to use the results when assigning machining modes. Methodology. Theoretical development of a modular mathematical model of the removal allowance process and shaping during milling of cylindrical surfaces was carried out using a matrix apparatus for converting coordinate systems. Unified modules were developed: instrumental, orientation and shaping, which allowed us to describe the processing of the part more clearly. All calculations were performed in the mathematical package Mathcad. Using the functions available in the package, a graphical representation of the mathematical model of the tool and machined surfaces was obtained. Using the logical blocks developed in the program, the characteristics of the treated surface were investigated, such as roughness in the axial and radial planes. The influence of the tool orientation angle and the number of cutter teeth on the roughness of the machined surface was investigated. The known formulas for calculating the cutting forces during milling are specified. Findings. A general modular mathematical spatial model is constructed of the removal process of an allowance and formation at milling by the oriented tool of round surfaces of rotation, such as necks of camshafts, cylindrical surfaces of shafts of transmissions and others. The roughness parameters of the treated surface are determined. The outflow of the tool characteristics and the angle of its orientation on the geometric roughness in the axial and radial sections is investigated. The area of the layer cut off by one tooth of a mill is defined. The calculation formulas are specified for finding the components of cutting forces during milling. Originality. A modular spatial model of the process of milling cylindrical surfaces with an oriented tool is proposed, on the basis of which the components of cutting forces are calculated, which can be used in designing new tools and improving machining conditions by the existing ones. Practical value. Based on the use of modern computer facilities and software, the developed calculation program allows controlling the process of forming cylindrical surfaces during their milling with an oriented tool. It also allows predicting the initial machining accuracy by determining the parameters of geometric roughness in axial and radial sections. This makes it possible to choose the optimal tool orientation angle, milling cutter parameters and cutting modes to achieve high productivity and processing quality.

A Thermo-Hydrodynamic Model for Thermal Energy Flow Management in A (Semi) Floating Ring Bearing System for Automotive Turbochargers

Abstract Oil-engine lubricated turbochargers (TCs) operate at high temperature and must withstand large temperature gradients that produce severe thermomechanical stresses in the TC mechanical components. Thus, an insight into the thermal energy flows and an effective thermal management are paramount to ensure reliable TC operation. The paper analyzes the transport of energy and heat flows in semifloating ring bearings (SFRBs) for automotive TCs with integrated heat and fluid flow models for both (turbine and compressor sides) radial bearings and thrust bearings to produce a complete thermohydrodynamic analysis predictive tool. The model couples the energy transport equations and the lubrication Reynolds equations in the inner and outer films of an SFRB and the adjacent thrust films to a three-dimensional heat conduction in the floating ring and along with thermal soaking into the TC casing. Cold lubricant, supplied at a specific temperature and pressure, flows to fill the films of the radial bearings, and then the thrust bearings. The lubricated bearings, radial and axial, support shaft loads, static and dynamic, and produce drag power losses. The streams of lubricant warm up as they take away a sizable portion of the heat flow from the hot shaft plus that due to viscous shear drag. Another fraction of thermal energy flow sinks into the floating ring, which presents a distinct temperature field varying along the radial, circumferential, and axial directions. The computational analysis contemplates a TC operating at shaft speeds (Ω) ranging from 30 krpm to 240 krpm (4 kHz) and an SFRB supplied with engine oil at PSUP = 3.0 bar and TSUP = 120 °C. The analysis focuses on a brass-made turbine bearing (TB) as it is the one that disposes most thermal energy flow since the shaft surface is hot at Ts = 213 °C (just below the lubricant flash point temperature at 230 °C) while the casing temperature is TC = TSUP. The ring with length/diameter = 1.6 has radial bearings with four equally spaced feed holes and four axial grooves, and the ratio outer film clearance/inner film clearance equals 5.3 at room temperature. As shaft speed increases (= 100 m/s max. surface speed), the inner film temperature increases proportionally; albeit the heat flow from the shaft into the inner film decreases while the viscous drag power raises rapidly. The outer film heats to just a few degrees above TSUP since the nonspinning ring does not generate viscous shear drag. The ring heats unevenly, radially with a ∼20 °C temperature gradient from its inner to outer diameters (ID and OD), and axially with up to a ∼50 °C difference from the thrust bearing side that also produces a drag power loss. At a low shaft speed (45 krpm), heat flowing from the shaft overwhelms the drag power loss induced by shearing the inner film; whereas as shaft speed increases (240 krpm), the contribution from the drag power loss to the total energy flow disposed increases significantly, from 3% to 63%. The lubricant flows, inner plus outer, advect most of the thermal energy flow, 74% to 81%, over the range of shaft speeds, low to high. The floating ring conducts a sizeable portion of thermal energy flow, 39% to 49% of the total, though varying little with shaft speed. Similarly does the fraction of heat, 9% to 13% of the total, conducted into the TC casing. A more conductive ring material or an outer film with a longer length conduct more heat into the ring although the lubricant flows still carry most of the thermal energy flow generated by viscous drag losses and heat from the shaft. The results demonstrate the importance of designing an SFRB system with adequate clearances and proper materials to offer an adequate thermal management and avoiding too high temperatures that could varnish, even flash and burn, the engine oil. The improvements in the energy transport and heat flow modeling of an SFRB system will produce significant savings in TC performance.

Mathematical model for producing machine parts

In the article, the object of research is the development of a technology for improving the operational properties of cast parts from steel 45, obtained by the method of electroslag remelting. Based on the research results, the modes of heat treatment of the shaft-gear part in an aqueous medium water-oil, heat treatment to increase the service life of the product, and energy-saving melting technology by the method of electroslag remelting were developed. Particular attention is paid to the development and analytical implementation of the mathematical model of the developed technologies by the methods of linear algebra by drawing up the Lagrange interpolation polynomial. Functional dependencies have been obtained for determining the amount of oxygen in the melt depending on the diameter of the electrode and the aluminum content in this electrode for any diameter of the mold, the hardness of the shaft surface depending on its diameter, the oxygen content (amount) in the melt depending on the aluminum content in the electrode for different mold diameters. Based on the developed and analytically implemented mathematical models of the investigated technological process, it seems possible to simplify experimental studies. In other words, based on analytical studies, it is possible to predict the results of subsequent experiments. Based on the developed and analytically implemented mathematical models of the investigated technological process, it seems possible to simplify experimental studies. In other words, based on analytical studies, it is possible to predict the results of subsequent experiments.

Саlculation of heat transfer processes at canlendering of polyethylene sheets

Introduction. The technological limitations of the calendering process include the condition of leaving the sheet from the calender in the presence of a middle layer of melt, or a sufficient value of the average temperature of the sheet, which determines the flatness of the sheet with subsequent cooling and glazing in a flat state on the roller conveyor. The process of vitrification of the polymer melt has a wide temperature range, which greatly complicates the calculations.Materials and methods. Processing of high density polyethylene (HDPE) on a calender with three rolls is considered. A series of numerical experiments was performed.Results and discussion. Boundary conditions for the mathematical model of sheet cooling and conditions for numerical integration of the equation of nonstationary thermal conductivity taking into account the heat of crystallization are formulated, the equation is presented in finite differences, using a grid with a step along the sheet length.The letter from HDPE in the physical model is conditionally expanded, the following assumptions are made:1. the thickness of the sheet is much smaller than the diameter of the shafts of the calender, so the orthogonal coordinate system is used;2. the transition of the melt from the initial thickness of the workpiece to the final occurs at the same linear velocity (the melt does not slip on the shaft);3. the thermal conductivity of HDPE is much less than the thermal conductivity of the shaft material, so the temperature of the sheet at the point of contact with the shaft is equal to the temperature of the shaft;4. reduction of sheet thickness in the second gap does not occur;5. energy dissipation in the gaps does not affect the temperature fields in the melt;6. heat transfer along the sheet due to thermal conductivity is absent;7. the width of the sheet is much larger than the thickness, so the model of the cooling process is simplified to one-dimensional, without heat transfer across the sheet.For the surface of the sheet, which is cooled by air by free convection, the method of control volume (heat balance method) was used for the boundary layer with a thickness of half a step of the grid along the thickness of the sheet.Numerical experiments were performed for the following conditions: HDPE performance 500 kg / h; initial melt temperature 235°C; diameter of calender shafts 0,25 m; sheet thickness 1.0; 2.0; 3.0; 5.0 mm. Sheet width 1.0 m. The temperature of the first shaft 125°С, shaft temperatures №2 and №3 were selected under the condition of the average melt temperature at the outlet of the calender 125°С, ambient air temperature 20°С, heat transfer coefficient from the sheet and the shaft to air 25 W / (m2K).An example of the results of numerical integration by the Runge – Kutta method (temperature fields and average melt temperature) is shown in the figures.The theoretical analysis of heat exchange processes during calendering of sheets from high density polyethylene melt is carried out, the technological parameters of calendering and their influence on the main quality parameters are analyzed.For the conditions of the numerical experiment, it was found that when calendering sheets with HDPE with a thickness of 1.0 to 2.0 mm will have to choose a high-temperature coolant, which greatly complicates the system of thermal stabilization of the shafts. A 1 mm thick sheet will not have gloss due to the high temperature of the shafts, and the temperature inhomogeneity of the shaft surface due to the high heat flux density can lead to the formation of a central strip on the surface of the sheet without gloss. Calendering of sheets with HDPE with a thickness of 5 mm or more for the conditions of numerical experiment causes difficulties due to the possible "blasting" of the sheet up (behind the hot shaft).Conclusions. It is established that when calendering sheets of smaller thickness, the heat load on the middle shaft increases, and it may be necessary to use high-temperature coolants. The optimal temperature of the calender shafts is in a narrow range, so when designing new equipment, thermal calculation is important.

Kaplama Yapılmış Enjektör Gövde Millerinin Fiziksel Özelliklerinin Araştırılması

Diesel engines have an important place in today's internal combustion engines. Although use of the engines has decreased due to exhaust emissions, the engines continue to be used in different fields such as marine vehicles, generators, rail system and water vehicles. One of the most important equipment of diesel engines is the fuel system, especially such as common rail system with wide usage area. High pressure pump and injectors parts are manufactured very precisely in diesel fuel systems. Common-Rail injectors operate under very high pressure (1400-2000bar). This can cause easy damage injector parts such as nozzle, needle, shaft and valve. In this study, the effects of coating the common rail injector were investigated. For this purpose, different coatings were made on 3 diesel injectors which used in commercial vehicle engines and then fuel injection values and wear on the shaft surface after operation were compared with the standard injector. Body shafts covered with ALTiN and TiN are coated using the PVD arc method. Three injector body shafts were coated with Cr, TiN, ALTiN, respectively and working tests were performed with standard injectors. Cr coated shaft is coated using liquid immersion method. After the coating, the shaft roughness values were measured. The injectors were continuously tested by creating a cycle for 90 hours. As a result, it was determined that the coated shafts provided the original injector catalogue values, the spray quantities were within the ± tolerance range and the coating was suitable for use in injectors.

On the Effect of Supplied Flow Rate to the Performance of a Tilting-Pad Journal Bearing—Static Load and Dynamic Force Measurements

Abstract Rotating machinery relies on engineered tilting-pad journal bearings (TPJB) to provide static load support with minimal drag power losses, safe pad temperatures, and ensuring a rotor-dynamic stable rotor operation. End users focus on reducing the supplied oil flow rate into a bearing to both lower operational costs and to increase drive power efficiency. This paper presents measurements of the steady-state and dynamic forced performance of a TPJB whilst focusing on the influence of supplied oil flow rate, below and above a nominal condition (50% and 150%). The test bearing has five pads, slenderness ratio L/D = 0.4, spherical pivots with pad offset = 50%, and a preload –0.40, with a clearance to radius ratio (Cr/R) ≈ 0.001 at room temperature. The bearing is installed under a load-between-pads (LBP) orientation and has a flooded housing with end seals. The test conditions include operation at various shaft surface speeds (32 m/s–85 m/s) and specific static loads from 0.17 MPa to 2.1 MPa. A turbine oil lubricates the bearing with a speed-dependent flow rate delivered at a constant supply temperature. Measurements obtained at a steady thermal equilibrium include the journal static eccentricity and attitude angle, the oil exit temperature rise, and the pads' subsurface temperatures at various locations, circumferential and axial. The rig includes measurement of the drive torque and shaft speed to produce the bearing drag power loss. Dynamic force coefficients include stiffness, damping, and virtual-mass coefficients. As expected, the drag power and the lubricant temperature rise depend mainly on shaft speed rather than on applied load. A reduction in oil flow rate to 50% of its nominal magnitude causes a modest increase in journal eccentricity, a 15% reduction in drag power loss, a moderate raise (6 °C) in pads' subsurface temperatures, a slight increase (up to 6%) in the direct stiffnesses, and a decrease (up to 7%) in direct damping coefficients. Conversely, a 1.5 times increase in oil flow rate causes a slight increase (up to 9%) in drag power loss, a moderate reduction of pads' temperatures (up to 3 °C), a maximum 5% reduction in direct stiffnesses, and a maximum 10% increase in direct damping. The paper also presents comparisons of the test results against predictions from a thermo-elastohydrodynamic (TEHD) lubrication model. In conclusion, a 50% reduced oil flow rate only causes a slight degradation in the test bearing static and dynamic force performance and does not make the bearing operation unsafe for tests with surface speed up to 74 m/s. As an important corollary, the measured bearing drag power differs from the conventional estimate derived from the product of the supplied flow rate, the lubricant-specific heat, and the oil exit temperature rise.

Patterns of form error inheritance during machining

The paper studies modeling of quality parameters formation during machining on metal cutting machines. It was demonstrated that operational properties of parts are created not only at finishing operations, but rather formed throughout the entire technological process. At the same time, some characteristics and properties are inherited from operation to operation, i. e. copying of workpiece form errors to the machined part in the form of the same errors. The nonlinearity of the workpiece corresponds to the nonlinearity of the part. The extent of operational copying of nonlinearity (shaft surface runout in the middle section) was studied. A mathematical model of such error inheritance was developed with consideration of the nonlinear approximation of depth of cut variation along the workpiece circumference (per one revolution of the part). For existing tool materials, the exponent x at the cutting depth in the formula of the cutting force P is in the range of 0.7–0.9. As the depth of cut decreases, the refinement coefficient decreases. Therefore, when switching from rough operations (large cutting depths) to finishing (small cutting depths), the refinement coefficient becomes smaller.