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In the paper, the optical system of a precise bar length measuring comparator is analysed. The requirements for such a system are determined and systematized. The impact of the resolution, signal discretization frequency, image blurring, bar edge measurement indeterminacy and camera noise on measuring the bar width and establishing the bar position is discussed upon. Various algorithms have been analysed and finally a bar edge identification algorithm oriented to the scale calibration accuracy and the high processing speed was proposed. In the end of the paper, conclusions are provided.

The paper describes an establishment of dynamic characteristics of the newly created passive mechanical system for isolation of low-frequency (0.7 Hz–50 Hz) vibrations. The many metrological means are sensitive to mechanical vibrations and acoustic noise of low frequency. Such may appear both outside and inside a building, i.e. may be caused by wind, heating, aeration, air conditioning equipment, moving vehicles and other. In the paper, description of the theoretical and experimental tests is provided. The obtained dynamic characteristics (transmissibilities) of the passive mechanical low-frequency vibration isolation system show that such a system is able to isolate vibrations effectively in the frequency range of 0.7 Hz–50 Hz. The results of the experimental tests support the results of the theoretical research.

In this study, the theoretical and experimental investigations of the dynamics of complex passive low-frequency vibration systems are described. It is shown that a complex system consisting of a vibrating platform, an optical table and a vibration isolation system of quasi-zero stiffness loaded by a certain mass may isolate low-frequency vibrations in a narrow frequency range only. In another case, the system does not isolate vibrations; it even operates as an amplifier. The frequencies that ensure the top efficiency of the vibration damping system of quasi-zero stiffness were established.

The influence of acoustic field on vapor precipitation process taking place above the plating bath is analyzed in the article. Lateral exhaust hood was used to remove aerosol from open surface tank. It is shown that acoustic field generator generates sound waves with sound level of 130–140 dB at 1–4 kHz frequencies. Such acoustic field increases aerosol coagulation and its precipitation back to the liquid. This results in the reduction of aerosol concentration in the air, reduction of costs of air purification equipment and increase of its removal efficiency.

The object of this study is the acoustic field generated by aerodynamic acoustic generators of various types and designs. Six types of aerodynamic acoustic generators were studied experimentally and theoretically to determine the parameters of their generated acoustic field. It was established that the aerodynamic Hartmann type sound generator produces the necessary for acoustic particle agglomeration acoustic field and can be used in acoustic air cleaning equipment. It was established that classical theoretical calculation methods underestimate the design features of aerodynamic acoustic generators and cannot be used to calculate their characteristics.

This paper presents a numerical simulation of a pulsating flow generated inside an ejector; the flow is intended to oxidize ferrous iron (Fe2+) dissolved in drinking water to ferric iron (Fe3+). The pulsating flow ejector can be used in water treatment systems where the water is saturated with oxygen before being treated by filters. It is shown that the pulsating flow is generated due to fluctuations in the pressure, density, and velocity of the flow inside the ejector. It is established that the flow pressure inside the ejector varies from 0.513 to 0.0719 MPa, the flow density varies from 4.64 to 0.66 kg/m3, and the flow velocity varies from 0 to 590 m/s. Numerical simulation results have shown that an acoustic field is generated inside the ejector during the mixing of air with water, which accelerates the coagulation of iron particles. The obtained sound power level value of 100 dB shows that the pulsating flow ejector can be used for non-reagent water treatment.

This paper presents a novel concept of local push-pull ventilation system used to remove aerosol particles from open surface tanks. Sound waves generated by aerodynamic sound generator are introduced into the push air flow of lateral exhaust hood and used to agglomerate aerosol particles. Results of calculation of parameters of sound generator and aeroacoustic air flow are presented. It is established that 5–10 μm aerosol particles are aggregated better at frequencies below the ultrasonic range (1–5 kHz) and aerosols with a particle size of less than 5 μm are more effectively aggregated at ultrasonic frequencies. It was experimentally established that the relative air humidity measured above open surface tank is decreased up to 1.6 times in presence of acoustic field as compared with humidity obtained for conventional push-pull air removal system. It is also obtained that increase of the temperature of the liquid increases the aerosol removal efficiency of lateral exhaust hood enhanced by aeroacoustic air flow.

The article deals with changes in the density of pulsating water and air flow generated in pulsating flow ejector. Transformation of the fluid motion equation to Lighthill’s equation describing density change and acoustic radiation of the flow is presented. Calculation results demonstrate suitability of the ejector to cause acoustic agglomeration and effectively remove iron particles from potable water.

This article considers problems arising from conventional techniques used to diagnose faults in the rolling-element bearings of rotor-bearing systems, with dampers used in centrifugal milk processing machinery. Such machines include milk separators and related processing machinery. The article asserts that where the rotor-bearing system is equipped with vibration dampers, conventional fault diagnostic measurements produce inadequate results. Hence, for rotor-bearing systems of this type, this article suggests a different way to diagnose faults in bearings and monitor conditions.

The paper deals with the fault diagnostic system of centrifugal milk separator’s rotor bearings with vibration dampers. The diagnostic system consists of a number of accelerometers attached to the outer ring of the upper bearing of the rotor and the separator’s housing. Such a system allows measuring bearing outer ring vibrations directly and indirectly (through the housing) and at the same time it allows to evaluate the impact of bearing vibration dampers. Direct and indirect bearing vibration measurement results and the differences between them are presented in the paper as well as the relationship between the vibration acceleration and excitation force spectra.

The present paper describes the research of the optical device for two-dimensional straightness measurement of technological machines. Mathematical study of an optical device, operating on the phase principle and measuring transversal displacements of machine parts in two directions (X and Y) during their linear longitudinal motion in a machine (alongside the Z axis), is presented. How to estimate the range of travel along the Z axis is analytically shown. At this range, the measurer gives correct measurements of transverse displacement. The necessary distance from the objective focus to the image plane was defined mathematically. The sample results of measuring the displacement of the table of a technological machine by using the optical device are presented in the paper. This optical device for non-contact straightness measurement can be used for measurement straightness in turning, milling, drilling, grinding machines and other technological machines, also in geodesy and cartography, and for moving accuracy testing of mechatronic devices, robotics and others.

This paper presents a novel concept of cyclone separator, where sound waves are used to agglomerate fine particles. Sound waves generated by Hartmann acoustic generator are introduced into the secondary (core) air flow of cyclone separator. Results of numerical simulation of air flows inside conventional and acoustic cyclone separators are presented. It is shown that intensive pressure pulsations occur in acoustic generator's reflector. These pulsations generate an acoustic field. It is experimentally established that the average separation efficiency of conventional cyclone separator reaches 87.2% only, while separation efficiency of acoustic cyclone separator is approximately 97.5%. Obtained results show that air flows inside cyclone separator can be investigated numerically.

This paper deals with the problems encountered in the fault diagnosis in damped rotor-bearing systems used in centrifugal milk separators. It is shown that direct bearing vibration measurements are more reliable than indirect (through rotor housing) vibration measurements. However, in most cases it is not possible to measure bearing vibrations directly. The factors causing large diagnostic measurement errors, such as the influence of the vibration damping system, step-up gear and electric motor noise are discussed in the paper. It is established that vibration measurements of the damping system are noninformative and cannot be used to diagnose faults in bearings. It is proposed to use the vibration spectra correlation to predict bearing failures in rotor-bearing systems of this type.

This paper presents air flow velocity profiles obtained in conventional and acoustic cyclone separators. It is shown that vortex air flow is created in acoustical cyclone separator in presence of secondary countercurrent air flow. It is obtained that in acoustic cyclone separator air pressure pulses occur at frequency of 8 kHz and pressure amplitude reaches a value of 170 dB. Separation efficiency of acoustic cyclone separator was established experimentally.

This work investigates agglomeration process of aerosol particles in presence of acoustic field. It is shown that besides orthokinetic and hydrodynamic interaction mechanisms, tribological interaction occurs in presence of acoustic field. This interaction depends on dynamic viscosity of the gas mixture above the liquid surface. The influence of acoustic field on tribological interaction between the aerosol particles was investigated both numerically and experimentally. The obtained results show the positive influence of acoustic field on agglomeration of aerosol particles.

The paper presents the methods for reducing harmful aerosols from galvanic baths polluting the environment under conditions when air flow helps in forming an acoustic field above the bath. The findings show that the level of air humidy is the lowest when aerosols are removed with the help of a side exhauster. Side effects on acoustic coagulation may occur. Aerosol coagulates when elevated above the liquid and returns to liquid not dispersed in the evironment. The article introduces active suckers in accordance to their form and effectiveness collecting pollutants. The dependence of humidity on temperature is analyzed under the impact of external factors such as sucking, blowing and sucking or blowing, sucking and an acoustic field. The paper also discusses data on the dependence of sound pressure and looks at the level of frequency distribution. Santrauka Atliktas kenksmingų garų (aerozolio), patenkančių į aplinką nuo galvaninių vonių, tyrimas, kai jiems šalinti naudojamas aktyvintasis šoninis siurbtuvas su oro srautu, kuris suformuoja akustinį lauką virš vonios. Parodyta, kad oro drėgnumas kinta nereikšmingai esant skysčio temperatūroms iki 85 ºC, kai kartu su siurbimu naudojami aeroakustiniai srautai, dėl kurių pasireiškia akustinė koaguliacija. Nustatyta, kad aerozoliui pakilus virš skysčio, vyksta koaguliacija, ir jis, nepasklidęs į aplinką, sugrįžta į skystį. Aptariami aktyvintieji šoniniai siurbtuvai pagal formą ir efektyvumą surenkant teršalus. Analizuojama drėgnumo priklausomybė nuo skysčio temperatūros, veikiant išoriniams veiksniams: siurbimui; siurbimui ir pūtimui; siurbimui, pūtimui ir akustiniam laukui. Atlikta sukuriamo akustinio lauko parametrų analizė: garso slėgio intensyvumo ir garso slėgio lygio pasiskirstymas dažnio srityje. Raktiniai žodžiai: siurbtuvas; akustinis laukas; aerozolis

The essence of the considered problem is to improve line scale gauge calibration quality by studying vibrations that are induced during the calibration process. To assess the influence of vibrations it is necessary to solve a lot of scientific and technical tasks. Serious difficulties were confronted during the mathematical analysis - development of analytical model and determination of its coefficients. An in-depth analysis of line scale measurement means had to be performed to this aim, because only experimental measurements enabled to estimate the majority of coefficients.

Dependence of a comparator reading dynamic error on vibro activity of a carriage is analyzed in the paper. There is shown how change reading errors at action only carriage drive vibrations and at artificially provoked carriage vibrations at different frequencies. Results achieved enable to evaluate the influence of vibration components on reading errors.

Results of tribological research of mineral motor oil with and without twisted nematic liquid crystal additive (stearic acid cholesteryl ester) are presented in the article. Experimental research was performed by means of a “fixed segment – rotating roller” tribometer according to the central three-factor second-order rotatable factorial design. The following parameters were accepted as controllable factors: contact pressure (3.32–6.68 MPa), concentration of liquid crystal in lubricant (0.16–1.84 ) and the average height of surface roughness of contacting surfaces of roller and segment (2.5–37.5 μm). The friction coefficient and friction zone temperature were served as output parameters. Regression equations describing the friction process were obtained and tribological efficiency of liquid crystal additive was established.

This paper describes a technique and mechatronical system for testing drills of a small diameter at different stages of production. The goal is to realize a system for drill testing which automatically increases the load applied to a drill under testing conditions and measure the drill's breaking torsion moment and deflection angle before a break occurs. The system's apparatus part and algorithms for the control of actuators and data acquisition from sensors are explained in the article. Also, a testing technique was applied in theoretical investigations to define the stress concentrations in dangerous places of the drill. The proposed technique and system have been verified by testing the drills of a small diameter at different stages of production—after thermal, mechanical treatment, and for quality control of the finished product.

An analysis of the influence of the change of temperature of a rotor’s system with bearings of sliding friction to the work of a searching system is presented in this paper. Experimental research to gauge the clearance of change between a rotor and bearing subject to change of temperature and frequency of rotor’s rotating is also presented. A special rig and special implements of measurement for doing measurements is included. Experimental measurements done according to the specially made up methodology is in this paper. Also, the article describes and gives the principal system of measurement and analysis methodology to do the experiment and an analysis was done of results and the gauge of consistent pattern of changes of the searched parameters.

Lubrication and cooling of a high speed grinding process in the grinding machine as in a mechatronic system using technological liquids are analyzed in this paper. It is shown that in the case of high grinding speed, technological liquids undergo an aeration process and due to this their physical properties change. Reynolds equation, which estimates the aeration liquid, is derived. It is shown, that the application of such an equation is proper only in the finishing of grinding. Experimental research is also presented in the paper, which shows the influence of technological liquids to the temperature field of the grinding machine and to its automatic control.

This hydromechatronical testing system is used for workload simulation while testing technological machines to determine their dynamic characteristics. The authors have described structure and principles of operation of the created equipment and equations of balances of the hydrostatic bearings of the slider. Also, boring bar and equations of motion of the boring bar have been formed in the article. Analytical and graphical dependences of motion of the slider and boring bar have been determined after entering digital data into the computer.

This article presents a Mechatronic Hydrodynamic Bearings Testing System and describes its main functions. The System’s structure, control and principles of data input/output are given here. The System enables one to evaluate the quality of bearings by spectral analysis of oscillations and orbits of the rotor pivot. Potentials of the System and realization of diagnostic measurements by means of this System are described.

Various aspects of the improvement of the functioning of grinding accuracy are considered. Active methods of the control of grinding systems are proposed to ensure the quality required for finishing. It is pointed out that the quality of finishing is closely connected with the mutual position of the tool and the work piece in the grinding process. This position is appreciated by permissible state areas of the axis of the tool and the work piece. Analytical expression of this interaction is described by non-traditional mathematical model’s dependences. Mathematical models presented evaluate eccentricity between the tool and the work piece or between other elements of the system and enable one to better understand the appearance of the second and higher harmonics on the work piece processed or on the tool. They allow one to simulate the finishing not only of the cylindrical, but also of non-round profile work pieces, such as cams, eccentrics, etc. The mathematical dependences worked out allow one to build various modifications of the grinding systems and to evaluate the quality of their functioning. A circuit for the active control of the tool position is proposed, with the goal of quality improvement of finishing. For this purpose the usage of the adaptive spindle with tilting-pad journal bearings is suggested.

The problem of quality diagnostics of systems with hydrodynamic bearings is analyzed in the paper. In analyzing the problem, the analytical research of the change of friction coefficient, pressure, rotor rotation axis eccentricity in dependence on the wear magnitude between the rotor and the bearing are performed. The method of the analytical research is presented. Results of the analytical research and experimental measurements are depicted in graphs.

The hydrodynamic tilting-pad journal bearing with a mobile elastic element and choose of its geometry by calculating deformations are analyzed in the paper. It is shown here, that such bearings with elastic elements can use the kinetic energy of the oil, which appears in the incensement volume. When rotor oscillations appear elastic elements disturb the equilibrium of segments and diminish the influence of oscillation. Differential equations are derived for this aim and they allow choosing geometrical parameters of elastic elements independence on the load intensity and the oil temperature.

Systems “spindle – bearings” will inevitably have some errors and discrepancies in the dimensions and form of elements. These inaccuracies cause spindle’s run out. The run out is a complex periodic process which may include three types of frequency components: with frequencies exceeding the spindle’s rotary frequency, with frequency equal to the spindle’s rotary frequency and with frequencies lower that the spindle’s rotary frequency. Each individual frequency component may be caused by eccentricity or out-of-roundness of the inner race, out-of-roundness of the outer race, spread of ball diameters, and inaccuracy of their form. Self-adjustable pad-type bearings are sensitive to technological, service and construction perturbations. This is characteristic of vortex trajectories of the spindles. Character of these trajectories depends on the thickness of lubricant film over the pad supports and on the geometrical precision of the spindle journal and pads (segments). Geometrical precision under a high unbalance of the grinding wheel is crucial for functional quality, size and form of the orbit. Geometrical precision of trajectories and its state are subject to change depending on a number of parameters especially on the rigidity of the lubricant film and dynamic system.

The paper’s work examines opportunities of diagnostics of vibroinsulated mechanisms based on the measurement of mechanical vibration. Vibration insulation systems distort the diagnostic signal therefore direct diagnostics of vibration of vibroinsulated mechanisms is impossible. The work’s objective is to analyse the influence of vibration insulation systems on the diagnostics of such mechanisms and to identify the kinds of parameters on which this influence depends. A stand for tests is made for the achievement of this objective; by using the stand the vibration of a mechanism can be simultaneously measured both directly and via the vibration insulation system.

The created system of twist drill testing enables one to increase drill quality and provides for competitive ability in the market. The mechatronical system of drill testing consists of the sum total of apparatus and program means, i.e. the hydro station, control valves, an electronically controlled pressure regulator, control block, force and displacement transducers, a computer with a plate leading-in and a control for electrical signals and a plate of power amplifiers. The created program “Tools” is intended to control the testing equipment and to fix the drill acting load and the brake angle in the computer. The graphics of 6 mm diameter drill breakage parameters and breakage curve are presented in this article.

The measurement results of acoustic field parameters above electroplating bath, in presence of water vapour, are analyzed in this work. Suction was created by means of side exhausters. It is obtained that the sound field generator generated a sound level of 130–140 dB at frequency interval between 1 and 10 kHz. It is shown that aerosol coagulation and precipitation processes are intensified under the mentioned conditions. The concentration of vapour and other aerosols in removal air decreases as a result, therefore air cleaning equipment costs can be reduced and cleaning efficiency increased.

Iron is one of the most common natural elements. When iron concentration in water is more than 0,3 mg/l, it causes the formation of rust drain tag or changes the colour of the fabric during washing. Thus, the use of the acoustic field to improve water quality is a very relevant topic. Acoustic oscillations are currently widely used in various industrial sectors, including water treatment, metallurgy, chemical and food industry, equipment manufacturing and medicine. When materials are affected by acoustic fields, physical-chemical processes begin. Acoustic fields cause material dispersion, emulsification, coagulation and degassing (gas removal) as well as influence the crystallization and melting processes. Acoustic vibrations may also cause various chemical transformations such as oxidation, polymerization processes and depolymerisation. The utilization of acoustics to enhance water oxidation and precipitation of coarse impurities further extends the scope of the use of this physical method. Santrauka Lietuvos požeminiame vandenyje geležis yra svarbiausias komponentas, pažeidžiantis geriamojo vandens kokybės normatyvinius reikalavimus, todėl tiriamas akustinio lauko naudojimas šioms dalelėms sukibti skystyje. Šiuo metu garso virpesiai yra plačiai taikomi įvairiose pramonės šakose: metalurgijoje, chemijos ir maisto pramonėje, gaminant įrenginius ir medicinoje. Akustikos naudojimas oksidacijos procesui vandenyje sustiprinti, nusodinant stambiąsias priemaišas, dar labiau išplečia šio fizikinio metodo taikymo sritį. Raktiniai žodžiai: akustinis laukas; garso dažnis; koaguliacija

This work presents numerical investigations of the thermal behaviour of fire resistant multilayered structure consisting of two steel sheets, gypsum plate and stone wool layer. Simulation was performed using SolidWorks ® Simulation software. The numerical simulation results were compared with experimental data obtained from the fire resistance test. The simulation results were found to be in good agreement with experimental results. It is shown that thermal behaviour of such multilayered structures can be investigated numerically, thus avoiding costly and time-consuming laboratory experiments. DOI: http://dx.doi.org/10.5755/j01.mech.18.3.1878

This article explores the formation of spiral vortex and application of liquid aerators. Visually, the new method has been applied for three structures of the stream ejector. The paper shows that under the same traffic flow, the venturi tube with blade cup liquid creates maximum ejected liquid contact surface. It has been noticed that the flared shape of the ejector blade that is close to the form of the spiral vortex, creates improvements in a pulsation flow and thus increases the solubility of oxygen in the liquid. Santrauka Straipsnyje tyrinėjamas spiralinio sūkurio formavimas ir taikymas skysčio aeratoriuose. Vizualiniu metodu išbandytos trys naujos srautinių čiurkšlinių siurblių konstrukcijos. Parodyta, kad čiurkšliniu siurbliu su menteliniu skysčio užsukimu, esant tam pačiam darbinio srauto debitui, sukuriamas didžiausias siurbiamo skysčio sąlyčio paviršius. Pastebėta, kad mentelinio čiurkšlinio siurblio fakelo forma artima spiralinio sūkurio formai, kuri sukuria srauto pulsacijas, pagerinančias deguonies tirpumą skystyje. Raktiniai žodžiai: : aeravimas, čiurkšlinis siurblys, spiralinio sūkurio forma, srauto fakelas

This paper presents research dynamic properties of a calibration comparator which is used to calibrate high precision line standards of length. For this purpose, multi-body dynamic and mathematical models of a carriage system of the comparator were presented. Calculated amplitude-frequency responses and modes of oscillations allowed a determination of resonant frequencies of the system.

This paper analyzes tribological aspects of particle adhesion in presence of acoustic field. It is shown that acoustic field forces create favourable conditions for contact and adhesion between particles.http://dx.doi.org/10.5755/j01.u.66.3.653

This paper investigates precipitation process of small particles in the secondary air flow of the cyclone separator. It was established that in presence of acoustic field particles smaller than 5 um are stuck together, falling then to the bottom of conical section of the cyclone separator. http://dx.doi.org/10.5755/j01.u.66.1.267

An experimental investigation on the performance of an emulsion of mineral oil with twisted nematic liquid crystal (cholesteryl stearate) additive when turning steel with uncoated carbide lathe tool was carried out. Cutting fluid was applied by flooding the cutting zone from low pressure coolant system of conventional lathe. Machined surface roughness and flank wear of the tool were monitored during machining tests. Experimental investigation was carried out by means of a two-factor second-order full factorial orthogonal design. The concentration of liquid crystal in cutting fluid (0.1-0.5% by volume) and cutting speed (85-267 m/min) were chosen as independent variables and surface roughness Ra was chosen as response variable. It was found that surface roughness with the cutting fluid containing liquid crystalline additive was better (decreased 1.2-fold) that with the additive-free coolant. Tool life increased 25% as compared with additive-free coolant. Twisted nematic liquid crystals were also used as a dry-film lubricant of hand taps. It is established that liquid crystals reduce cutting torque up to 4 times as compared with grease. http://dx.doi.org/10.5755/j01.mech.17.5.738