Roller Misalignment Research Articles

Web Wrinkle Defects due to Temperature Profile in Roll-to-Roll Manufacturing Systems.

The roll-to-roll manufacturing system is extensively used for mass producing products made of plastic, paper, and fabric in several traditional industries. When flexible substrates, also known as webs, are heated and transported inside the dryer, an inconsistent temperature distribution occurs on the material in the machine direction (MD) and cross-machine direction (CMD). If rollers are not aligned in parallel on the same plane in the roll-to-roll web handling process, or if roller misalignment exists, strain deviation occurs in the web, resulting in lateral displacement and web wrinkles. Therefore, this study examined a wrinkle, which is a thermal deformation that occurs when an inconsistent web temperature distribution is formed on the material inside a dryer. The changes in the elastic modulus and thermal expansion of the web were also examined. Experiments were conducted using a PET film, and its elastic modulus and thermal expansion were examined. The results showed that the presence of a web wrinkle defect can cause a thickness deviation in the functional layer manufactured on the web. Moreover, an appropriate operating speed should be set to reduce the CMD temperature deviation, thereby reducing instances of wrinkle defects.

Моделирование движения ленточного конвейера с учетом угла наклона и натяжения канатов става

Introduction. The relevance of the work is caused by the need to eliminate the arising automatic vibration processes of the pendent roller of the conveyor linear sections relative to roller pendant and minimization of vibration synchronization processes of a significant number of pendent rollers, leading to a conveyor stop. Previous studies have established that the most effective way to transport coarse material in underground mining is a belt conveyor. These studies have identified the disadvantages of conveyor transportation.The most common ones include the auto-vibration of the pendent roller of the conveyor linear sections relative to roller pendant. The manifestation of roller automatic vibrations increases the energy intensity of the process and reduces the performance of the belt conveyor. Objective. To set the angle of the conveyor belt inclination and the tension of the ropes of the load-bearing structure with the lowest amplitude vibrations of the pendent roller in order to reduce the energy intensity of the transportation process during the deposit development and increase the operational performance of the conveyor. Task. Modeling the possibility of manifestation and causes of occurrence, as well as the circumstances of long-term preservation of roller automatic vibrationson conveyors. Materials and methods of research. The object of the study is a conveyor belt with different angles of inclination (transportation).The authors conducted analysis and summary of previously performed own research; comparison with newly obtained experimental results; as well as a generalization of theoretical and experimental studies carried out by scientists in this field; synthesizing literature and patent data. Reliabilityis confirmed with application of actual state standards and approved research methodology. Boundary conditions are accepted: conveying of ordinary medium- and small- sizedmaterials is carried out; there is a constant unit load on the belt during transportation. Two types of connection are considered: the presence of an anchoring branch of roller with the ropes; absence of an anchoring branch that is the hinged connection of roller with the ropes. Research results. It has been established that when the belt moves with a load, the pendent roller deflects along the direction of the belt movement, regardless of the type of anchoring. The angle of the side roller inclination is calculated through the sliding velocity relative to the belt. The characteristics of sliding friction or change in sliding friction coefficient are modeled. The influence of the pendent roller mass on the process of automatic vibrationsat various angles of conveyor inclination has been evaluated. The reason for the occurrence of automatic vibrationsis established. Conclusion. Design changes that prevent side roller misalignment are recommended to reduce the likelihood of automatic vibrations.The side roller misalignment angle interval, beyond which stable conveyor operation is achieved, is determined. Resume. The results of the research can be useful in designing the conveyor when transporting the extracted raw materials.

Binocular Alignment Changes Between Sitting and Supine Positions in Patients with Dizziness.

Vertical and torsional ocular misalignment can occur from mild traumatic brain injuryor inner ear pathology, which may vary depending on head position. Here, we evaluate differences in a behavioral measure of binocular alignment in both upright and supine head position. Ocular perception of vertical and torsional alignment was measured using the torsional and vertical alignment nulling (TAN, VAN) task in N = 52 veterans with dizziness (N = 38 with traumatic brain injury), N = 41 civilians with vestibular schwannoma resection (UVD), and N = 33 healthy controls for both positions. The interquartile range within each group, regardless of head position, was greater for torsional compared to vertical misalignment. We use generalized estimating equations to compare average TAN (torsional) scores and VAN (vertical) scores between groups and test position. Compared to the healthy controls, TAN was significantly increased by + 0.4186° in veterans (P = 0.030) and by + 0.5747° in UVD (P = 0.010), but there was no difference with head position. For VAN, no difference was found between the three groups, but the misalignment did worsen by 0.0888° (P = 0.0070) as the head position moved from upright to supine. Head position had negligible effects on this behavioral measure of vertical and torsional binocular misalignment, and torsional misalignments were worse than controls in both veterans with dizziness and patients with vestibular nerve resection although neither reported torsional diplopia. Our data suggests that the tolerance for roll misalignment may be abnormally large in patients with dizziness. Alternatively, perceptual roll misalignments may be a manifest cause for dizziness, and therefore a useful proxy for distinguishing differences in putative otolith function in veterans with dizziness.

Advancement of Roll-Gap Control to Curb the Camber in Heavy-Plate Rolling Mills

The quality of steelwork products depends on the geometric precision of flat products. Heavy-plate rolling mills produce plates for large-diameter pipes and for use in shipbuilding, mechanical engineering, and construction. This is why the precision requirements are so stringent. Today’s Mills 5000 produce flat products of up to 5 m in width; the operation of these units shows ‘camber’ defects and axial shift of the roll at the stand exit point. This induces greater loss of metal due to edge trimming and involves a higher risk of accidents. These defects mainly occur due to the asymmetry in the roll gap, which is in turn caused by their misalignment in rolling. As a result, the feed varies in gauge, and the strip moves unevenly. The paper’s key contribution consists in theoretical and experimental substantiation and development of a set of control methods intended to address roll-gap asymmetry. The methods effectively compensate for the asymmetry resulting from the “inherited” wedge, which preexists before the strip enters the stand. They also compensate for the “ongoing” roll misalignment that is caused by the difference in force on the opposite side of the stand during rolling. This comprehensive approach to addressing camber and axial displacement of the feed has not been found in other sources. This paper presents a RAC controller connection diagram that ensures that the roll gap is even across the feed. The paper notes the shortcomings of the design configuration of the controller and shows how it could be improved. The authors have developed a predictive roll-gap asymmetry adjustment method that compensates for the deviations in gauge during the inter-passage pauses. They have also developed a method to control gap misalignment during rolling. The paper showcases the feasibility of a proportional-derivative RAC. The methods have been tested by mathematical modeling and experimentally. The paper further shows oscillograms sampled at Mill 5000 after implementing the developed solutions. Tests confirm far better precision of the screw-down mechanisms on the opposite sides of the stand. This reduces the variation in gauge across the feed and thus curbs the camber defect. As a result, the geometry of the flat improves, and less metal is lost in trimming. The paper further discusses how the RAC controller interacts with the automatic gauge control system. The conclusion is that these systems do not interfere with each other. The developed systems have proceeded to pilot testing.

High-Precision Roller Supported by Active Magnetic Bearings

Magnetic bearings support rotors in a non-contact way using magnetic force. Therefore, there is no friction and it is possible to measure and control the position of a rotor in the air gap. In this study, the rotational vibration of a roller was minimized using magnetic bearings, and a precision roller capable of automatic alignment using the position control function of magnetic bearings was proposed. A rotation accuracy of approximately 4.6 μm (peak-to-peak) was observed, even under a rotation of 30 rev/min and a radial force load of 300 N. The rotor position control experiment for magnetic bearings showed that 1-μm resolution position control is possible. To further improve the accuracy, the automatic alignment algorithm was proposed using magnetic bearings for the roller misalignment condition, and it was confirmed that alignment is possible at a level that the pressing force difference between both ends of the roller is within 0.3 N. Through this study, it was confirmed that rollers with magnetic bearings can be applied to precision equipment. It is expected that the implementation of the automatic alignment function will simplify the equipment configuration and maintenance compared to conventional rollers with ball bearings.

Material analysis of the fatigue mechanism of rollers in tapered roller bearings

Rolling contact fatigue is the main failure mechanism of tapered roller bearings. This study investigated the fatigue mechanism of rollers in a tapered roller bearing that failed in a run-to-failure test. Roller microstructure and crack morphology were investigated through scanning electron microscopy. A microhardness test was performed to investigate the strain hardening of the roller material induced by rolling contact fatigue. Results showed that microcavities and holes are important influential factors of crack initiation and propagation. Crack propagation angle affects crack morphology and propagation mode. Material strain hardening accelerates crack growth. Furthermore, roller misalignment causes uneven hardenability and severe damage to roller ends.

Numerical Simulation of Bulging Deformation for Wide-Thick Slab Under Uneven Cooling Conditions

In the present work, the bulging deformation of a wide-thick slab under uneven cooling conditions was studied using finite element method. The non-uniform solidification was first calculated using a 2D heat transfer model. The thermal material properties were derived based on a microsegregation model, and the water flux distribution was measured and applied to calculate the cooling boundary conditions. Based on the solidification results, a 3D bulging model was established. The 2D heat transfer model was verified by the measured shell thickness and the slab surface temperature, and the 3D bulging model was verified by the calculated maximum bulging deflections using formulas. The bulging deformation behavior of the wide-thick slab under uneven cooling condition was then determined, and the effect of uneven solidification, casting speed, and roll misalignment were investigated.

Final focus system tuning studies towards Compact Linear Collider feasibility

In this paper we present the latest results regarding the tuning study of the baseline design of the final focus system of the Compact Linear Collider (CLIC-FFS). CLIC aims to provide collisions to the experiments at a luminosity above ${10}^{34}\text{ }\text{ }\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. In order to deliver such luminosity in a single pass machine, the vertical beam size at the interaction point (IP) is reduced to about 1 nm, which imposes unprecedented tuning difficulties to the system. In previous studies, 90% of the machines reached 90% of the nominal luminosity at the expense of 18 000 luminosity measurements, when considering beam position monitor errors and transverse misalignments of magnets for a single beam case. In the present study, additional static imperfections such as roll misalignments and strength errors are included. Moreover both ${e}^{\ensuremath{-}}$ and ${e}^{+}$ beamlines are properly simulated. A new tuning procedure based on linear and nonlinear knobs is implemented to effectively cure the most relevant beam size aberrations at the IP. The obtained results for single and double beam studies under solely static imperfections are presented.

Elastic buckling analysis of webs transported through rollers with misalignment

Emerging flexible electronics industries, such as solar cells and RFID tags manufactures, adopt the roll-to-roll (R2R) technology to improve their production efficiency. However, the flexible webs used in these fields wrinkle easily due to their tiny thickness and complex structure. Moreover, the webs are easily buckled if the rollers are misaligned. Therefore, it is desired to introduce an efficient method which can help to determine the critical buckling conditions of the webs when there is misalignment of rolls during their production. The current research presents a model based on the Kirchhoff plates buckling theory to determine the critical buckling misalignment and tension for webs transported through misaligned rollers. Webs are modeled as tensioned Timoshenko beams to obtain their stress distributions. The critical buckling conditions are calculated using the Galerkin method in the current research. Results indicate that the calculated critical conditions are close to the practical ones considering the parabolic variation of shear stress and the linear variation of bending stress. The results also indicate that the critical misalignment increases with the increase of the span ratio and tension, and critical misalignment decreases with the increase of the elastic modulus and web width. Moreover, the critical tension increases as the thickness and elastic modulus increases. The presented model provides a useful method to design and maintain R2R equipment.

An integrative approach to spatial mapping of pressure distribution in microrolling

Microrolling is an advanced manufacturing process for the mass production of miniaturized components. At the micrometer scale, small deviation in material thickness or roll misalignment can lead to significant variation of the pressure distribution across the product, resulting in dimensional inaccuracy of the imprinted texture. To address this problem, an embedded sensing system has been developed to monitor in situ the spatial pressure distribution across the tool–workpiece interface. A key element of the sensing system is a pressure reconstruction algorithm, which determines the deformation across the roll structure from a limited number of sensing points, and converts the data subsequently into pressure distribution across the workpiece. This paper investigates how backprojection and interpolation can be integrated synergistically to improve the accuracy and robustness of pressure reconstruction. Specifically, interpolation is performed as a pre-possessing step to increase the resolution in capacitance variation estimation and improve the robustness of back-projection in solving the inverse problem of capacitance–pressure conversion. Experimental study confirmed the performance of the developed method.

A Vibration Energy Approach Used to Identify Temperature Trending in Railroad Tapered-Roller Bearings

Bearing temperature trending is a phenomenon that has plagued the railroad industry for decades and has resulted in costly train stoppages and non-verified bearing removals. Initial experimental studies conducted at The University of Texas-Pan American to explore this troubling phenomenon identified potential sources for the abrupt changes in temperature exhibited by some railroad bearings. The authors hypothesize that vibration-induced rollermisalignment is the root cause for bearing temperature trending. Hence, subsequent research focused on providing validation for the proposed hypothesis through vibration monitoring techniques. To that end, dynamic testers were used to run railroad bearings at the various speeds and loads that they experience in the field. A “trigger” bearing with a known cup raceway defect was used as a vibration source to induce roller misalignment on neighbouring defect-free bearings. Results show that the vibration energy of a bearing would decrease prior to an increase in temperature. In theory, misaligned rollers would vibrate less, leading to a decrease in the overall vibration energy, while also generating sufficient friction to account for the observed temperature increase. Typically, rollers realign themselves through geometrical thermal expansions or changes in the operating conditions, thus, returning to normal temperature and vibration levels. This paper outlines the research findings.

SU‐E‐J‐28: Assessment of Rotational Misalignment in Cervical Spine Treatments and Potential for 6DOF Couch Corrections

Purpose:To quantify the magnitude of angular misalignments that may arise during spinal radiosurgery for metastases to cervical vertebrae and assess the ability of six‐degree of freedom (6DOF) alignment systems to apply appropriate corrections.Methods:A retrospective analysis of the distributions of rotational misalignments of cervical vertebrae based on planning CT and CBCT acquired for verification of patient positioning was performed. Fifteen patients being treated for cancers of the head and neck were immobilized using Type‐S head‐only thermoplastic masks mounted to an overlay board. Rigid registration was performed using commercially available software for individual vertebrae of each patient. Distributions of rotations were tabulated across all patients and vertebrae, modeled with a normal distribution, and 95% confidence intervals were estimated. Dosimetric consequences of maximal and 6DOF correctable misalignments are simulated.Results:Across all patients and vertebrae, 2/105 pitch rotations were >3° (1.9%), including 2/15 (13%) patients. Upper and lower 95% confidence intervals for pitch, yaw, and roll misalignments were [−2.3°, 3.3°], [−1.8°, 1.4°], and [−2.6°, 2.2°], respectively. Rotations for each vertebra were also considered. The greatest need for rotation appears to be for pitch correction of vertebra C4, with misalignment of 0.2° ± 1.9° observed, which predicts that a rotation >3° would be necessary 11.5% of the time that this vertebra is of interest.Conclusion:Empirical and model data presented here suggest that approximately 2–4% of vertebrae would require a rotation >3° in the sagittal plane, with some vertebrae more prone to rotational misalignments than others. Uncorrected rotational misalignment has the potential to alter dose distributions with respect to both treatment volumes and organs at risk and rotations >3° may require physical repositioning of the patient. Implementation of six‐degree of freedom couch systems may facilitate clinical flow after rotational misalignment is detected, and allow expeditious, automated setup corrections.Varian and Dartmouth‐Hitchcock Medical Center are parties to a customer acceptance evaluation agreement regarding the Varian 6 degree of freedom couch.

시각피로 모형: 카메라의 회전오차, 촬영 거리, 수렴 조건이 입체 시각피로에 미치는 영향

3차원 영상이 유발하는 입체 시각 피로를 이해하기 위해서는 이미 제작된 콘텐츠가 유발하는 시각피로 뿐 아니라 영상이 생성되는 촬영 시점에 영상을 결정하는 카메라 파라미터가 시각피로에 미치는 영향에 대한 연구가 필요하다. 본 연구는 카메라 파라미터인 회전 오차, 촬영 거리, 수렴 조건이 입체 시각 피로에 미치는 영향을 검증하고 모형화 하였다. 연구 결과 회전 오차, 촬영 거리, 수렴 조건이 모두 입체 시각 피로에 영향을 미치며 특히 카메라 오정렬 관련 파라미터인 회전 오차는 상대적으로 낮은 화면 시차에서 입체 시각 피로에 큰 영향을 미치는 것을 확인할 수 있었다. In order to understand 3D visual fatigue, it is necessary to examine the visual fatigue induced by camera parameters as well as that induced by a pre-existing 3D content. In the present study, we examined the effects of camera parameters, such as roll misalignment error, shooting distance and vergence condition on 3D visual fatigue and we modelled it. The results indicate that roll misalignment error, shooting distance and vergence condition affect 3D visual fatigue and the effect of roll misalignment error on 3D visual fatigue is evident specifically when screen disparity is relatively small.

The Estimation of Angular Misalignments for Ultra Short Baseline Navigation Systems. Part I: Numerical Simulations

Ultra Short Baseline (USBL) navigation systems are often faced with positioning errors arising from misalignments between sensors. This paper proposes a line survey method for USBL angular alignment calibration. In the scheme of USBL line survey, mathematical representations of positioning error arising from heading, pitch and roll misalignments are derived, respectively. The effect of each misalignment angle and how the differences can be used to calibrate each misalignment angle in turn are presented. An iterative algorithm that takes advantage of the geometry of position errors resulting from angular misalignments is developed for USBL calibration. Numerical simulations are provided to demonstrate the effectiveness of the USBL line survey approach. In addition, the effect of measurement error on the estimation of roll alignment error is evaluated and discussed.

The Estimation of Angular Misalignments for Ultra Short Baseline Navigation Systems. Part II: Experimental Results

An algorithm of alignment calibration for Ultra Short Baseline (USBL) navigation systems was presented in the companion work (Part I). In this part (Part II) of the paper, this algorithm is tested on the sea trial data collected from USBL line surveys. In particular, the solutions to two practical problems referred to as heading deviation and cross-track error in the USBL line survey are presented. A field experiment running eight line surveys was conducted to collect USBL positioning data. The numerical results for the sea trial data demonstrated that the proposed algorithm could robustly and effectively estimate the alignment errors. Comparisons of the experimental result with the analytical prediction of roll misalignment estimation in Part I is drawn, showing good agreement. The experimental results also show that an inappropriate estimation of roll alignment error will significantly degrade the quality of estimations of heading and pitch alignment errors.

Pressure Reconstruction for Microrolling Process Monitoring

Microrolling is an advanced manufacturing process for the mass production of miniaturized components. At the micrometer scale, small deviation in material thickness or roll misalignment may significantly alter pressure distribution across the product, resulting in variations in the imprinted texture dimension. An embedded sensing method has been developed to monitor the pressure distribution across the workpiece. A key component of the sensing method is a pressure retrieving algorithm that determines deformation across the roll structure from a limited number of sensing points and converts the data subsequently into pressure distribution, based on the theories of interpolation and back-projection. In this paper, a combination of interpolation (Bezier Curve, Thin Plate Spline, and Kriging) and Tikhonov regularization have been used to resolve the inverse problem.

Numerical and experimental analysis for the skew phenomena on the flexible belt and roller contact systems

The thin, flexible, flat belt system is frequently employed for power transmission, conveyor systems, and various manufacturing process equipments, such as printers, elevators, and automated teller machines. In general, some critical problems can happen during operation, since a thin flexible belt on rollers can easily skew. This is especially serious for high-speed belt operations. In this skewed situation, due to possible relative roller misalignment, roller deflection, and/or belt non-uniformity itself, a thin flexible belt can move along the perpendicular direction to the travelling direction. In this investigation, an efficient analysis method for simulating skewing phenomena of thin flexible belt systems is presented using the complete integration of large deformable finite element methods and multibody dynamics. A 4-node shell element is used to describe a thin flexible belt and two rigid cylindrical bodies describe the roller. Each cylindrical body is fixed with a pin joint and the positions of the rollers are adjusted to impose a tension to thebelt. For the interactions between the belt and the rollers, an efficient contact search algorithm based on a compliant contact force model is presented in this study. The contact search algorithm is composed of a pre-search and a detailed search to identify points of contact between the belt and the rollers. In the pre-search, a simple algorithm is used to identify lines on the belt that are close enough to the rollers that there might potentially be contact between them. The detailed search is performed by making efficient two-dimensional (2D) comparisons of the cross-section of the roller with a 2D projection of the belt lines identified in the pre-search. Afterwards, the contact force is generated by a compliant force model that uses a stick–slip frictional algorithm. The simulation model is validated against experimental measurement systems for thin flexible belt and rollers. It shows a good agreement with the numerical results. Furthermore CPU time with commercial software ANSYS Workbench is compared to check the performance of the algorithm. The proposed method is more than 10 times faster compared with ANSYS Workbench.

Theoretical and Experimental Investigation into Generation of Wrinkling and Slip in Plastic-Films under Transportation

In the transport processes of plastic-films, wrinkling is sometimes generated due to misalignment of roller. To avoid the wrinkling, it is effective to reduce the web tension. However, under the low web tension, the traction inevitably falls as transport velocity increases due to air entrainment and is accompanied by the onset of slip. This paper examined such a trade-off relation between the wrinkling generation due to roller misalignment and onset of slip. At first, the prediction models for slippage and wrinkling are formulated based on the contact mechanics. Moreover, the observation method of wrinkling generation and slip was presented and the critical misalignment angle, critical web tension to generate wrinkling and slip onset velocity were measured for various operation conditions. Five types of PET (polyethylene terephthalate) films were used for measurements. From the experimental and theoretical results, the effects of roller velocity, anisotropic Young's modulus and film thickness on the relation between the roller misalignment and web tension were made clear. As a summary of experimental and theoretical works, the stable transportation map was newly introduced for protecting both wrinkling and slip.

Theoretical and Experimental Investigation into Generation of Wrinkling and Slip in Plastic-Films under Transportation

In the transport processes of plastic-films, wrinkling is sometimes generated due to misalignment of roller. To avoid the wrinkling, it is effective to reduce the web tension. However, under the low web tension, the traction inevitably falls as transport velocity increases due to air entrainment and is accompanied by the onset of slip. This paper examined such a trade-off relation between the wrinkling generation due to roller misalignment and onset of slip. At first, the prediction models for slippage and wrinkling are formulated based on the contact mechanics. Moreover, the observation method of wrinkling generation and slip was presented and the critical misalignment angle, critical web tension to generate wrinkling and slip onset velocity were measured for various operation conditions. Five types of PET (polyethylene terephthalate) films were used for measurements. From the experimental and theoretical results, the effects of roller velocity, anisotropic Young's modulii and film thickness on the relation between the roller misalignment and web tension were made clear. As a summary of experimental and theoretical works, the stable transportation map was newly introduced for protecting both wrinkling and slip.

In-situ alignment calibration of attitude and ultra short baseline sensors for precision underwater positioning

Positioning accuracy of an ultra short baseline (USBL) tracking system is significantly reduced with the increase of alignment errors in the installation of sensors. Although techniques for sensor alignment calibration have been developed, they are either complex or lacking in rigor. This study proposes an algorithm to estimate the angular misalignments of a USBL transceiver relative to attitude sensors. The numerical algorithm is based on the positioning errors caused by heading, pitch, and roll misalignments, respectively, when running a circular survey around a seabed transponder. The positioning errors introduced by the angular misalignments outline an iterative scheme of estimating the roll alignment error first, next the heading alignment error, and then finally the pitch alignment error. This makes possible the efficient estimation of all angular misalignments with a high degree of accuracy. With the consideration of measurement error and executing a non-centered and non-perfect circle around the true transponder position, numerical simulations are performed to validate the effectiveness of the proposed algorithm. The simulation results show that the proposed algorithm is robust to the effects of measurement error, non-centered circles, and non-perfect circles. Moreover, the estimates converge fairly quickly, and can be achieved with good accuracy in only a few iterations.