Rotating Machine Parts Research Articles

A Bayesian Optimized Discriminant Analysis Model for Condition Monitoring of Face Milling Cutter Using Vibration Datasets

Abstract With the advent of industry 4.0, which conceptualizes self-monitoring of rotating machine parts by adopting techniques like data analytics, cloud computing, Internet of things, machine learning (ML), and artificial intelligence. The significant research area in predictive maintenance is tool condition monitoring (TCM) as the tool condition affects the overall machining process and its economics. Lately, machine learning techniques are being used to classify the tool’s condition in operation. These techniques are cost saving and help industries with adopting future-proof solutions for their operations. One such technique called discriminant analysis (DA) must be examined particularly for TCM. Owing to its less-expensive computation and shorter run times, using them in TCM will ensure the effective use of the cutting tool and reduce maintenance times. This article presents a Bayesian optimized discriminant analysis model to classify and monitor the tool condition into three user-defined classes. The data are collected using an in-house designed and developed data acquisition (DAQ) module setup on a Vertical Machining Center (VMC). The hyperparameter tuning has been incorporated using Bayesian optimization search, and the parameter that gives the best model was found out to be “linear,” achieving an accuracy of 93.3%. This study confirms the feasibility of machine learning techniques like DA in the field of TCM and using Bayesian optimization algorithms to fine-tune the model, making it industry ready.

Novel self-adaptive vibration signal analysis: Concealed component decomposition and its application in bearing fault diagnosis

Rolling Elements Bearing (REB) failures are the most common reason for breakdowns in rotating machine parts. The reduction of frequent catastrophes of such rotating components is essential to have maximum productivity. To have a successful prediction of health conditions, performance assessment, and fault diagnosis of rolling element bearing, a valid signal processing method is a basic need. This paper proposes a novel self-adaptive signal decomposition technique: Concealed component decomposition (CCD). The proposed decomposition preserves transitory evidence about perilous signal points and basis waves, with a transient objective equivalent to the timescale of extrema events in the signal. The method isolates and uses the intrinsic instantaneous amplitude in balance with other essential configuration features. The proposed CCD technique is utilized to develop a precise bearing fault diagnosis model. A practical mode selection criterion is also proposed. The selected mode function then undergoes the implementation of envelope spectrum analysis. The proposed model has been validated over different simulated and experimental datasets of different fault types. The proposed method demonstrates its superiority to other existing signal decomposition approaches on various grounds.

Radial deformation analysis of couple stress fluid operated multi-lobe hydrodynamic journal bearing

In high speed rotating machine parts the elasticity of the bearings supporting the journal plays key role. The present work is related to couple stress fluid (CSF) operated multi-lobe elastic hydrodynamic (HD) journal bearing. In this work the evaluation of radial deformation in the three dimensional elastic liner of bearing has been done. Here finite element method is used to solve the Reynolds equation along with the elasticity equation, to evaluate radial deformation in the liner. The iterative process used for the convergence of pressure in the rigid as well as in elastic case, however the present work focuses on the amount of radial deformation obtained while operating at different eccentricities. The results of radial deformation shows that increase or decrease in the amount of deformation is different for both upper and lower lobe with increase in couple stress parameter and eccentricity ratio. Further it directly influences the performance of bearing system by effecting the fluid flow zone. Hence the elasticity of the liner must be consider for better performance evaluation along with couple stress fluid. The radial deformation results of two lobe journal bearing presented in this work will lead to the better bearing designs by the bearing designers.

Friction coefficient and performance evaluation of plain journal bearing using SAE 5W-30 engine oil

Friction is a crucial parameter in tribological applications such as power transmission, crankshafts, gears, cams, bearings, and other rotating machine parts or components. Due to the relative motion of the shaft and bearing, friction needs to be analyzed according to all lubrication states of the journal bearing. The friction coefficient was significantly reduced using piezo-viscous SAE 5W-30 engine oil in this study. An adequate lubricant pressure is obtained using this approach to produce a suitable oil film thickness. Minimal variation in lubricant temperature was obtained which prescribes the sustainability of the lubricant. The bearing performance was observed through computational fluid dynamics analysis under different viscosities. The SAE 5W-30 lubricant-containing 0.052693 Pa s viscosity minimized bearing deformation and stress formation at 500, 750, and 1000 r/min. A new bearing material as gun-metal having good bearing properties and good resistance to corrosion has been proposed in this study.

Multi-Channel Real-Time Condition Monitoring System Based on Wideband Vibration Analysis of Motor Shafts Using SAW RFID Tags Coupled with Sensors.

While there is a wide range of approaches to monitor industrial machinery through their static components, rotating components are usually harder to monitor, since sensors are difficult to be mounted on them and continuously read during operation. However, the characteristics of rotating components may provide useful information about the machine condition to be included in monitoring algorithms, specially for long-term data analysis. In this work, wireless vibration monitoring of rotating machine parts is investigated using surface acoustic wave (SAW) radio frequency identification (RFID) tags coupled with sensors. The proposed augmented transponder solution, combined with low-latency interrogation and signal processing, enables real-time identification and wideband vibration sensing. On top of that, a multi-channel interrogation approach is used to compensate motion effects. This approach enhances the signal-to-noise ratio of low-power high-frequency components present on the vibration signatures and enables discriminant information extraction from rotating machine parts. Final feasibility is evaluated with induction motors and vibration measurements on rotating shafts are verified. In addition, a condition classification algorithm is implemented in an experimental setup based on different motor states. The results of this work open the possibility to feed predictive maintenance algorithms using new features extracted in real-time from wideband vibration measurements on rotating components.

Multi-probe system design for measuring the roundness and rotation error motion of a spindle using an error separation technique

Fourier model–based multi-probe-error-separation is an error separation method that is useful for precise measurement of the rotation error motion of spindles or roundness profile of rotating machine parts. However, it is not yet widely used, because it suffers from the critical problem of harmonic distortion. This study explores the phenomenon of harmonic distortion in detail and analytically clarifies the principles behind its occurrence. The position at which harmonic distortion occurs can be calculated exactly and easily using principles related not only to probe arrangement angles, but also to measurement conditions such as data length and undulation range of interest. Based on these principles, we propose multi-probe system design guidelines for the effective selection of probe arrangement angles and avoidance of harmonic distortion. The reliability and usability of the proposed design method are verified by simulation tests; stable multi-probe-error-separation can easily be achieved using the proposed design technique. We conduct experimental tests using a special measuring system based on four probes composed of two different probe arrangement sets and verify that this multi-probe-error-separation method can acquire rotation error motion or roundness profile precisely without harmonic distortion.

Analysis of the twist of ruled surfaces: application to strip machining

Flank milling of ruled surfaces is commonly applied to obtain rotating machine parts as defined using ruled surfaces. To this purpose, a wide range of positioning strategies had been studied to reduce interference between the cutting tool and the surface. Indeed, modelled ruled surfaces are non-developable meaning that they cannot be machined without interference. In order to minimise such interference, the positioning strategies studied tend to become increasingly complex, involving software programming using a dedicated language. To simplify matters and apply developed methods using standard software applications, it is proposed here to reduce interference by breaking the machined surface down into a number of sub-surfaces. The aim with this decomposition is to reduce the twist on each portion. A study of the global twist is presented showing nonlinearity with the length of the rule so that cutting methods can be demonstrated. [Received 28 November 2016; Revised 18 April 2017; Accepted 26 June 2017]

ANALYSIS OF THE TWIST OF RULED SURFACES. APPLICATION TO STRIP MACHINING

Flank milling of ruled surfaces is commonly applied to obtain rotating machine parts as defined using ruled surfaces. To this purpose, a wide range of positioning strategies had been studied to reduce interference between the cutting tool and the surface. Indeed, modelled ruled surfaces are non-developable meaning that they cannot be machined without interference. In order to minimise such interference, the positioning strategies studied tend to become increasingly complex, involving software programming using a dedicated language. To simplify matters and apply developed methods using standard software applications, it is proposed here to reduce interference by breaking the machined surface down into a number of sub-surfaces. The aim with this decomposition is to reduce the twist on each portion. A study of the global twist is presented showing nonlinearity with the length of the rule so that cutting methods can be demonstrated. [Received 28 November 2016; Revised 18 April 2017; Accepted 26 June 2017]

Computational analysis of turning G10530 steel to eliminate chip crowding using variable cutting speeds

The machining of axle hub flange housings manufactured using G10530 steel is described in this paper. The machining of axle hub flange housings can lead to the entanglement of chips around workpiece holding fixtures, which leads to a loss of productivity due to the interruption of the machining process to remove entangled machining chips in the vicinity of the chuck (chip crowding). The finite element (FE) method was used to predict machining characteristics in order to eliminate the phenomenon of ‘chip crowding’ around rotating machine parts that impede the effective machining of axle hub flange housings. The finite element method is compared to traditional analytical calculations to observe whether discrete computations can accurately predict machining characteristics and to visually predict the shape of chips to eliminate the possibility of ‘chip crowding’. From this study, it is shown that short chips can be created using variable cutting speeds and that the FE method can be used to analyze chip formations in order to optimize the turning of G10530 axle hub flange housings. For the current practice of machining axle hub housings, when fedge/tr = 0.25 (small cutting edge radius), the level of power required for chip formation is calculated to be 6400 W generating a maximum temperature at the onset of chip formation of ~563 °C, and when fedge/tr = 0.75 (large cutting edge radius), the level of power required for chip formation is calculated to be 3200 W generating a maximum temperature at the onset of chip formation of ~292 °C. When forming chips at variable cutting speeds, the best case condition is one that draws the least power and generates the lowest temperature at the chip tool interface. This is achieved when a large cutting edge radius tool (fedge/tr = 0.75) is used for machining axle hub flanges. Closed form solutions appear to describe the machining conditions at the steady-state conditions very accurately. However, the FE method tends to generate accurate values under the conditions of unsteady chip formation when cutting at variable speeds. The innovations presented in this paper are associated with providing the necessary information to machine axle hub flanges with variable cutting speeds that eliminate the occurrence of ‘chip crowding’ by naturally fragmenting the formation of long metal chips.

Magnetic Field Detection with an Advanced FBG-based Sensor Device

A high-performance fiber Bragg grating-based (FBG) sensor device has been developed for the detection of small magnetic fields. Based on a smart multilayer jacket around the fibre over the physical length of the FBG, magnetic fields generated by rotating machine parts, power generators or power cable can be easily detected, analysed and evaluated. Consequently, this innovative, on-line and non-contact inspection method results in an increase in quality and reliability of high-performing machine parts, devices and cables. The basic physical principle is based on a magnetostrictive multilayer system that strains the high-resolution FBG element in presence of magnetic fields. Subsequently, a fixed relationship between induced magnetic field and wavelength change of the FBG element describes the characteristic sensitivity curve. Intensive tests regarding characterisation of this magnetic field FBG sensor have been carried out and its performance has been evaluated.

New Methods of Noncontact Sensing of Blade Vibrations and Deflections in Turbomachinery

The paper is focused on new methods of non-contact sensing vibrations and deflections of rotating machine parts, especially blades of steam turbines. Special attention is paid to the induction and magnetoresistive sensors developed in the Institute of Thermomechanics for non-contact measurements of characteristics of rotating blades inside steam turbines under operation. Different principles of non-contact sensors based on measuring deflections or velocity components are described and compared, including new types of magnetoresistive sensors. Hitherto unpublished principles of sensors intended for shrouded blades are described and discussed.

An analytical approach towards EHD analysis of connecting-rod bearing

Elastohydrodynamic (EHD) journal bearings in rotating machine parts are subjected to very severe operat-ing conditions, leading to a reduction in the minimal thick-ness of the lubricating film which can generate premature wear of the contact. In this work, an analytical method of calculating the minimal thickness of the oil film was pro-posed. It takes into account the effect of the elastic defor-mations due to both hydrodynamic pressure and inertia. The elastic deformations are calculated analytically and simultaneously. The connecting – rod bearing body defor-mations was predicted under low and moderate engine regimes. The correction produced by the introduction of the effect of inertia, have shown a clear difference for the global behaviour. The method was applied for analysis of a General Motors connecting – rod bearing engine. DOI: http://dx.doi.org/10.5755/j01.mech.20.2.6935

A Radio Frequency Polarimetric Sensor for Rotating Machine Analysis

The analysis of rotating machines during their test and characterization phases provides information essential for their design. Afterward, the monitoring of rotating machines operating in production is increasingly popular for condition based maintenance programs. Typically, contact accelerometers or strain gauges are physically attached to rotating machine parts (rotors, stators, housing, etc.) and/or proximity sensors are mounted very near to rotating shafts to capture data on periodic motions and vibrations. Radio frequency signals offer a noncontact, remote-sensing alternative. The temporally changing polarization of a reflected or scattered radio frequency signal can be analyzed to provide suitable information for rotating machine analysis. This paper will present the theory and practical application for using radio frequency polarimetry in analyzing rotating machines. A common desktop fan will be measured in normal operating condition and in simulated faulty conditions to demonstrate this technology's remote-sensing capabilities.

과다 예압을 받는 테이퍼롤러 베어링의 수명단축효과에 대한 실험적 연구

Tapered roller bearings are core components of rotating machine parts and are simultaneously subjected to axial and radial loads. Life-shortening effect was particularly evident in the case of tapered roller bearings used in the input and output shafts of transmission; this shortening of life was a result of excessive axial pre-load, which is common in the transmission assembly line. In this study, we derived an equation for evaluating the life of tapered roller bearings subjected to excessive pre-load by using accelerated life test data. The DOE(Design Of Experiment) method and FEA(Finite Element Analysis) was used for determining the condition for performing an accelerated life test. This equation for evaluating the service life of the bearings was derived by analyzing the Weibull distribution of the test results. Using the derived equation the life evaluated was 6-7 times longer than that evaluated by the conventional bearing-life equation. The results of this study will be helpful in predicting the life of tapered roller bearings subjected to excessive pre-load and in designing reliable rotating machines.

Pattern formation in rotating fluids

Flows in nature and technology are often associated with specific structures and pattern. This paper deals with the development and behaviour of such flow pattern. Flow structures are important for the mass, momentum and energy transport. The behaviour of different flow pattern is used by engineers to obtain an efficient mass and energy consumption. Mechanical power is transmitted via the momentum of rotating machine parts. Therefore the physical and mathematical knowledge of these basic concepts is important. Theoretical and experimental investigations of principle experiments are described in the following. We start with the classical problem of the flow between two concentric cylinders where the inner cylinder rotates. Periodic instabilities occur which are called Taylor vortices. The analogy between the cylindrical gap flow, the heat transfer in a horizontal fluid layer exposed to the gravity field and the boundary layer flow along concave boundaries concerning their stability behaviour is addressed. The vortex breakdown phenomenon in a cylinder with rotating cover is also described. A generalization to spherical sectors leads then to investigations with different boundary conditions. The spherical gap flow exhibits interesting phenomena concerning the nonlinear character of the Navier-Stokes equations. Multiple solutions in the nonlinear regime give rise to different routes during the laminar-turbulent transition. The interaction of two rotating spheres results in flow structures with separation and stagnation lines. Experimental results are confirmed by numerical simulations.

Optical vibration and deviation measurement of rotating machine parts

It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer (LDV).

疲労 レインフロー法を用いた超小型実働ひずみ頻度計測装置の開発とその応用

A very small strain history recorder based on the rainflow method has been developed and was named the Mini Rainflow Corder. The Mini Rainflow Corder is installed with IC chips containing the Rainflow algorithm software, an amplifier circuit, automatic bridge balance, a standard small size memory card in which the decomposed strain history data is stored and batteries. The data obtained under service loading can be easily retrieved by a personal or laptop computer from the memory card. The performance of the Mini Rainflow Corder was tested using the fatigue testing machine in laboratory, and also by the specially designed cantilever type cyclic loading testing machine. The accuracy of data acquisition, reliability at low and high temperatures, and shock resistance were also examined. The advantage of the developed recorder in application to rotating machine parts without a slip ring is emphasized. The application to car wheels was demonstrated.

Comparison of Different Actuator Concepts forApplications in Rotating Machinery

Considerable improvements of machines can be expected in the near future through the use ofelectronics in combination with control techniques. A key position will be held by the actuator systems that finally have to accomplish the controlled energy transfer according to the objectives. For rotating machine parts this is usually done via the bearings. Basically, there are two possibilities to transmit the controlled forces; contact free via magnetic fields (magnetic bearings) or the traditional way via conventional bearings. To realize the regulating actions multiple physical effects can be employed. In this paper some of the promising types of actuators and their advantages and disadvantages will be discussed, as well as how effectively to use these active elements under different objectives. Questions concerning the practical realizations will be given high priority.

Contactless inductive current collector for checking rotating machine parts

Contactless inductive current collector for checking rotating machine parts