Roll Position Research Articles

A multi-roller static model of the planetary roller screw mechanism considering load sharing

A multi-roller static model is proposed to calculate load sharing and load distribution in a planetary roller screw mechanism (PRSM) with axial loads and errors. Taking into the actual positions of rollers, the PRSM is discretized into a multi-roller spring system. The proposed model is validated by comparing the results from a finite element model. The load sharing, load distribution and elastic deformation behaviors of a PRSM under different part position errors and thread index errors are analyzed. The results show that load sharing is sensitive to the position errors of the screw and nut while being fairly insensitive to those of rollers. Part position errors and thread index errors have a great influence on the stiffness of the PRSM.

Are edger rolls useful to control the plate motion and camber in a reversing rolling mill?

In heavy-plate hot rolling, reversing rolling mills are typically used to reduce the thickness of steel slabs. Some reversing rolling mills are equipped with edger rolls to control the width of the rolled plate. At best, the straight plate centerline coincides with the lateral centerline of the rolling mill and the desired rectangular shape is exactly realized. In reality, lateral asymmetries like temperature gradients and thickness inhomogeneities cause a lateral movement, a camber, and a wedge-shaped cross section of the plate. These effects can reduce the product quality and entail collisions with the mill stand or other equipment along the roller table. To prevent this, active control of the lateral position and contour shape is desirable. In this work, a roughing mill where the roll gap adjustment is self-retaining, meaning that it can only be adjusted between rolling passes, is considered. As a control input during the rolling passes, the lateral position of the edger rolls is exploited. A mathematical model for both the lateral motion and the resulting shape of the plate is derived. The model is validated by measurement data recorded in an industrial plant. Based on the validated model, the question if edger rolls are useful to control the plate motion and shape is discussed. A two-degrees-of-freedom control concept composed of an optimization-based feedforward controller and a proportional feedback controller with Smith predictor is derived for the lateral motion and shape. The performance of the proposed control concept is demonstrated in simulation studies based on the validated model.

Establishment of Dynamic Model for Axle Box Bearing of High-Speed Trains Under Variable Speed Conditions

In this study, a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is established. In contrast to previous studies, the contact stress is simplified in the proposed model and the compensation balance excitation caused by the rotor mass eccentricity considered. The angle iteration method is used to overcome the challenge posed by the inability to determine the roller space position during bearing rotation. The simulation results show that the model accurately describes the dynamics of bearings under varying speed profiles that contain acceleration, deceleration, and speed oscillation stages. The order ratio spectrum of the bearing vibration signal indicates that both the single and multiple frequencies in the simulation results are consistent with the theoretical results. Experiments on bearings with outer and inner ring faults under various operating conditions are performed to verify the developed model.

Influence of panoramic cues during prolonged roll-tilt adaptation on the percept of vertical.

The percept of vertical, which mainly relies on vestibular and visual cues, is known to be affected after sustained whole-body roll tilt, mostly at roll positions adjacent to the position of adaptation. Here we ask whether the viewing of panoramic visual cues during the adaptation further influences the percept of the visual vertical. Participants were rotated in the frontal plane to a 90° clockwise tilt position, which was maintained for 4-minutes. During this period, the subject was either kept in darkness, or viewed panoramic pictures that were either veridical (aligned with gravity) or oriented along the body longitudinal axis. Errors of the subsequent subjective visual vertical (SVV), measured at various tilt angles, showed that the adaptation effect of panoramic cues is local, i.e. for a narrow range of tilts in the direction of the adaptation angle. This distortion was found irrespective of the orientation of the panoramic cues. We conclude that sustained exposure to panoramic and vestibular cues does not adapt the subsequent percept of vertical to the direction of the panoramic cue. Rather, our results suggest that sustained panoramic cues affect the SVV by an indirect effect on head orientation, with a 90° periodicity, that interacts with a vestibular cue to determine the percept of vertical.

Coupled DEM-MBD-PRM simulations of high-pressure grinding rolls. Part 1: Calibration and validation in pilot-scale

In spite of the important developments in mathematical modeling of high-pressure grinding rolls (HPGRs) in the last decade or so, predicting their performance for a wide range of geometries, wear conditions of the rolls and types of containment remains a challenge. Simulation using DEM coupled to multibody dynamics (MBD) of the floating roll appears as a viable alternative, but studies that demonstrate its validity are very scarce. Pilot-scale HPGRs, one with cheek plates and other with flanges, were tested in size reduction of iron ore pellet feed. Both have been simulated using DEM-MBD with a novel particle replacement model (PRM) in EDEM™. Simulations matched the throughput and the power demanded by the machines with very good accuracy. The predicted product size variations with operating conditions and along the axial roll position were in very good agreement with experiments, but only qualitatively, owing to the coarser sizes of particles simulated in comparison to those in the feed to the tests.

Preliminary modelling of power losses in roller chain drive: application to single speed cycling

A quasi-static chain drive model is proposed. This model, consistent with single speed cycling application, applies to simple two sprocket drives. The kinematics of the transmission is determined, including the capture and release positions of the rollers and the influence of the polygonal effect. The tensions into the links and the contact forces (between rollers and sprocket) are then calculated based on the results of the kinematic analysis. Both chain strands are assumed to be straight and their tension are considered as imposed. An estimate of the roller displacement is proposed using existing studies on the relationship between loading conditions and roller positions along the sprocket tooth profile. The presented model, is then used to assess the contribution of both meshing and roller motion on the global efficiency of the drive. Calculations show that the magnitude of both loss sources is similar for a wide range of gear ratios and loading conditions. According to the presented results, the relative motion between the rollers and the sprocket tooth profile should be considered in future studies dedicated to chain drive efficiency.

Optimal control of motion and camber of steel plates in a multi-pass reversing rolling process*

In flat steel rolling, roughing mills are used to roll slabs into thin plates within 5 to 7 consecutive reversing rolling passes with decreasing thickness. Some of these mills are equipped with edger rolls to control also the width of the plate. Edger rolls are usually mounted upstream of the roll gap. In the best case, a perfect cuboid-shaped plate without camber and thickness wedge leaves the roughing mill. In practice, however, lateral asymmetries like temperature gradients and thickness inhomogeneities may cause the plate to rotate in the roll gap with respect to the vertical axis and to form a camber or thickness wedge or both. In the worst case, these effects not just deteriorate the product quality but also jeopardize plant equipment like side guides. To improve the product quality and reduce wear of plant equipment, active control of the motion and camber of the plate is desirable. In this work, a mathematical model for both the planar motion and the resulting shape of the plate is briefly summarized. Based on this validated model, a model predictive control strategy that calculates optimal control inputs (roll gap tilt and lateral position of edger rolls) for all remaining rolling passes is developed. The performance of the proposed control concept is demonstrated in simulation studies.

Torsion and vibration reduction mechanism of roller PDC hybrid bit

In directional drilling, torque fluctuation generates a big shock when using polycrystalline diamond compact (PDC) bits, causing problems such as instability in vibration tools. This study presents a new type of composite bit with a roller on the blade. The mechanism of torsion reduction and vibration of the roller PDC hybrid bit is studied through a rock breaking experiment on the roller unit and a comprehensive drilling experiment on the composite bit. Six roller contour shapes, different pressures into the depth of the roller, six roller radial positions and the relative height of roller teeth, and PDC cutters that affect the novel hybrid torsion on bit (TOB) and weight on bit (WOB) are investigated. The equivalent friction coefficient of the roller and axial force per unit depth is used to evaluate the torsional and vibration reduction ability of the Roller. The results show that the equivalent friction coefficient of different contour Rollers is lower than that of PDC cutters, and the torsion reduction ability of the Rollers is higher than that of PDC cutters. The vibration reduction in the roller teeth in different radial positions was 1.59–9.17 times higher than that of PDC cutters, The torque of the roller PDC hybrid bit is 71.72%–98.33% of the conventional PDC bit. The roller shares 1.59%–23.06% of the WOB of the whole bit. As the cutter teeth and the PDC cutter's relative height decreases, the compound drilling torque decreases, the roller bit's weight proportion gradually increases, the torsional capacity decreases, and the damping capacity increases.

Electric Ducted Fan (EDF) Rocket Attitude Telemetry Using 2.4 GHz Radio Frequency

On a rocket, control requires monitoring to determine its position and attitude. Rocket stance includes roll, pitch, and yaw angles. Monitoring can be done manually without the help of tools while the object’s position is still within reach. It is difficult to carry out monitoring when the object is moving far and beyond the reach of the operator. This observation requires a monitoring system to monitor the object further. This research applies a telemetry system to a target tracking rocket. The measurement results from the IMU and GPS sensors on the rocket body will be processed by the ATMega 2560 microcontroller and sent via a 2.4 GHz RF signal. to Ground Control Station. The rocket telemetry data that has been sent to the GCS can be viewed by the operator through the GUI system in a computer program using the C# language in Visual Studio. Tests on latitude and longitude are carried out by tracking the trajectory of objects while testing for roll, pitch, and yaw angles is carried out by placing objects according to the reference angle. The results of the position obtained the values of altitude, latitude, and longitude of 0.5364 m, 0.000012°, and 0.000023°, respectively. An attitude tests for roll position, pitch, and compass heading have values of 0.35°, 0.07, and 2.90°, respectively. The telemetry data transmission distance test is still well-received at a distance of 200 with a test speed of 70 KM/hour.

Online Measuring Of Grain Flowrates and Its Measurement Sensitivities with Pitch and Roll Angles

A complete calibration test stand was constructed and instrumented to examine the effect of varying pitch and roll positions on the measurement errors of a microwave solid type flow sensor. Results indicated that measurement errors ranging from 2.50% to 6.82% and 1.80% to 8.86% were obtained by the changing of chute pitch (descending and ascending) and roll angle positions from 1.5° to 4.5°, respectively. Greater measurement errors were found at the low screw auger conveyor speed range. However, the magnitude of errors is within the acceptable margin for any typical wet paddy land topography.

A Critical Analysis of Finite-Element Modeling Procedures for Radial Bearing Stiffness Estimation

Different strategies are commonly employed by researchers in order to decrease the computational effort associated with the finite-element analysis of rolling-element bearings. The purpose of this work is to review and analyze the procedures and hypotheses that may be exploited to evaluate the nonlinear radial stiffness of these components. Techniques are utilized to develop a meshing procedure aimed at balancing the computational effort and the accuracy of the results, to define a robust approach to the problem. The geometry is reduced by taking advantage of the available symmetry planes, by removing unloaded rollers, and by substituting the shaft with an equivalent sinusoidal load. In addition, the element dimensions are adapted to the applied load depending on the size of the contact area as computed by means of the Hertz theory. The proposed methodology may be applied to all bearing types provided that symmetry conditions and contact area dimensions are properly assessed. The estimated stiffness is compared against analytical formulae retrieved from the literature. Influence of different element types, roller position, cage, and clearance on accuracy and computational time is discussed.

A 3D CFD simulation of oil spray-collection and delivery process in an aeroengine inter-shaft bearing

Under-race lubrication applied to the inter-shaft bearing of aeroengine is characterized by spray oil collection and oil delivery to the bearing via flow-path structure. Droplet splashing induced by the collision between spray oil and the scoop as well as oil flowing characteristics in the flow-path influence bearing lubrication efficiency. In previous investigations, the spray oil collection and oil delivery analysis were separated, and the effect of droplet splashing on bearing lubrication efficiency was not considered. Moreover, time-varying characteristics of oil delivered to the bearing were not accounted for. This is caused by time variations of the circumferential position of rollers and under-race feed holes. To overcome these limitations, a numerical model which integrates the spray oil collection and oil delivery analysis is proposed in this paper. The model is embedded with the function of calculating the flow rate of splashing droplets and analyzing time-varying characteristics of the oil fed to the bearing. Furthermore, the numerical model is validated by experimental investigation. The proposed numerical model facilitates the accurate calculation of bearing lubrication efficiency as well as the design of an efficient lubrication structure.

Analysis of a pipe conveyor's idler housing failure due to a missing roller in terms of contact forces

A missing roller in a hexagonal idler housing of the hose conveyor represents a failure that is often underestimated and overlooked. However, its consequences can often be serious and are manifested mainly on the conveyor belt or within the individual components of the hose conveyor. This type of failure is often identified late so there is no relevant method for its early identification. In most cases, this damage is registered by visual identification, which, however, is not easy to be performed on long transport routes. For this reason, it is therefore appropriate to identify such a type of failure by measuring force ratios. However, detailed research is needed to implement this approach. The paper presents research based on a series of experimental measurements to identify the interdependencies between a missing roller and subsequent changes in force ratios in the existence of such failures. A necessary condition for proper operation of pipe conveyors is the contact forces that arise between the guide rollers and the conveyor. The analysis of measurement results confirmed a strong dependence between the force ratios and a missing roller, which creates a precondition to identify existence of such a kind of failure in a hose conveyor. The observed differences in the magnitude of pressing forces are not constant and directly depend on the position in which the rollers are missing. The largest change in contact force was up to 407 N in a specific position compared to correct, error-free state. The results of measurements made allow to formulate exact dependencies and define mutual relations of force ratios between individual roller positions.

Automatic roller path tracking and mapping for pavement compaction using infrared thermography

AbstractCompaction is an important task in asphalt pavement construction. It ensures high quality of the pavement to provide required long‐term performance. Intelligent compaction (IC) integrated with global positioning system (GPS) is an innovative technology to help control the compaction quality of asphalt pavement by continuously providing the operator with the roller's current position and the number of rolling passes. However, the high equipment cost and signal disturbance are two identified issues when adopting the GPS for position estimation. This paper proposed a thermal‐based method for real‐time roller path tracking and mapping in pavement compaction operations. In this method, first, the incremental roller motion between each two consecutive frames was jointly estimated via calculation of the roller's heading direction by exploiting the pavement boundary information and the roller's translation using the optical flow technique. Then, the accuracy of the estimated incremental motion was optimized by incorporation of the roller's lateral position estimated by a position optimization model proposed by the authors. Finally, the roller's global location was estimated by chaining frame‐by‐frame roller motions recursively. Both laboratory and field validations were conducted to examine the performance of the proposed method, leading to the maximum mean absolute errors along the lateral direction to be 5.2 mm and 3.3 cm, respectively, and the maximum cumulative error rates along the longitudinal direction to be 0.85% and 0.73%, respectively. The validation results signified the method's potential as a low‐cost and applicable alternative to the GPS in the current IC technology for roller's position tracking and mapping.

Influence of differential reduction rate in adjacent roll reduction zone on internal cracks of high carbon bloom induced by mechanical soft reduction

To comprehensively investigate and alleviate internal cracks in high carbon bloom induced by mechanical soft reduction (MSR), a 3D thermal-mechanical coupled model, containing two adjacent pairs of reduction rolls, was developed to investigate the influence of differential reduction rate on evolution of stress concentration and displacement in as-cast bloom. In order to effectively provide theoretical basis for actual production, the reduction rate was calculated according to the appropriate reduction amount of each pair of reduction rolls, which can be adopted in the MSR to determinate the appropriate roll reduction amount in adjacent roll reduction zone. With the differential reduction rate of MSR increasing from −2.67 mm/m to 5.33 mm/m, the maximum equivalent stress of cracking area in as-cast bloom significantly decreased under first roll reduction position, the maximal displacement along the bloom width direction is significantly decreased with increasing of the differential reduction rate of MSR under end roll reduction position. According to the results of industrial experiment, the internal cracks were effectively alleviated and center shrinkage cavities were nearly eliminated by optimum designed experiments.

An experimental study on the anchoring characteristics of an innovative self-swelling Split-set

In order to improve the anchorage performance of conventional Split-sets, an innovative self-swelling Split-set is proposed in this paper. The structure of the rockbolt is introduced and the anchorage mechanism discussed. The self-swelling roll length, position and spacing are optimized based on laboratory pull-out tests. The experimental results indicate that the maximum load capacity and the energy absorption capacity at 200 mm displacement of the self-swelling Split-set are 92 kN and 16.8 kJ respectively when five 10 cm long self-swelling rolls with a 10 cm spacing are placed at the tail of the rockbolt. The time-dependent characteristics of the rockbolt using the optimized structure parameters show that the anchorage force of the rockbolt reaches 74.2% and 96% of the load capacity 12 and 24 h after installation respectively and the corresponding energy absorption capacity is 73.8% and 100% of the maximum energy absorption capacity respectively. The field pull-out test results show that the self-swelling Split-set provides an anchorage force of 92 kN 24 h after installation and the rockbolt can slide with a constant resistance. For comparison, a conventional Split-set of the same size provides only a maximum load capacity of 43 kN and its anchorage force decreases gradually once it slides. The results from the long-term monitoring of the surface displacement and axial force of the rockbolt in an experimental tunnel show that the rockbolt has a better anchorage performance than conventional Split-sets. The self-swelling Split-set takes the advantage of the radial expansion pressure induced by the hydration reaction of the self-swelling rolls to increase the contact force between the rockbolt and the borehole walls, which greatly improves the anchorage force and the energy absorption capacity. In addition, it is simple to install and the unit cost is low.

Field measurement of contact forces on rollers for a large diameter pipe conveyor

Abstract An intensive field measurement was carried out to assess the force acting on the rollers for a large diameter pipe conveyor. A special idler enclosing two dynamometers was designed and installed in the various roller positions. The forces on the rollers were metered while the conveyor was running with and without conveying material. The position of the two dynamometers was such allowing to derive the theoretical contact point of the belt onto the roller. The measurements were carried out in a straight section of the pipe conveyor and in the centre part of a horizontal curve. Obtained data are presented, analysed, and compared with the values from a six-point stiffness testing device. Further, the participation factor of the material load on the roller forces for a single roller is derived. The study concludes with a critical review of the findings comparing them with results presented in the literature.

Peningkatan Akurasi Sensor GY-521 MPU-6050 dengan Metode Koreksi Faktor Drift

GY-521 MPU-6050 Module is a core module MPU-6050, which is a 6 axis Motion Processing Unit. This sensor can be categorized as an Inertial Measurement Unit (IMU) sensor, which utilizes measurement systems such as gyroscopes and accelerometers to estimate the relative position, velocity, and acceleration of an object. A common accuracy problem in using IMU sensors, including the GY-521 MPU-6050, is the drifting phenomenon. This phenomenon results in a deviation between the actual conditions (position, angular velocity) and the sensor readings. Drift is caused by the accumulation of errors that arise from calculating the integral of the acceleration. This study proposes a drift error correction method at the sensor output using the calibration of the calculation of the average offset error sensor and the sensor fusion method between the information obtained from the gyroscope and accelerometer in the module, the tests were carried out using the Arduino Uno microcontroller. From the test results, it is found that the combination of the initial system calibration implementation and the use of the fusion sensor concept can provide better performance with the MSE analysis results for the roll position of 0.0029o and the pitch position of 0.0047o and the drifting error rate at the yaw angle position of 0 0082o / second or down 62.72%.

A robotic end-effector with rolling up mechanism for pick-and-release of a cotton sheet

In this paper we introduce a novel robotic end-effector for pick-and-release of a sheet of cotton cloth. One of the main operations in a factory for sewing cloth products is to pick up cloth parts, provide them to a sewing machine, and sew them together. Fabric products are assembled by performing this work in various processes. Each work starts with a lot of cloth parts stacked near a sewing machine. In the case of underwear, thin cotton cloth is the target of manipulation, but such cloth parts tend to stick to each other, and a certain skill or technical acuity is required for picking up. Therefore, this work is basically done manually in the present. The purpose of this study is to automate such manipulation, so we devise an end-effector that picks up only the top one of stacked cotton sheets. The proposed end-effector has a mechanism that is a cylindrical brush attached with a remover cloth on its surface. The cylindrical brush is grounded on a cotton sheet, and then is rotated to roll up only the cotton sheet. This mechanism makes it possible to release the sheet by rotating the brush in the reverse. We constructed hardware with this function and attached it to the tip of a robotic manipulator. In addition, we performed system integration so that the initial position of rolling up a cotton sheet could be automatically determined from images taken by a camera. We also conducted evaluation experiments.

Model-Based Dynamic Calibration of a Multi-Actuator Gap Leveler for Heavy Plates

Abstract A novel method to calibrate the work rolls of a precision leveler for heavy plates is proposed. During the leveling process, a sequence of bending steps is imposed on the plate by the work rolls of the leveler to eliminate flatness defects. The respective positions of the rolls define the intensity of the consecutive bends. Any deviation from the desired roll position may result in a suboptimal leveling process. Thus, an exact control of the position of the work rolls is required. Due to backlash, wear, tolerances, and elastic deformation, the roll positions cannot be determined from nominal parameters and dimensions. Therefore, the machine has to be calibrated and properly adjusted to find suitable reference positions for control. During calibration, the structure is prestressed with a suitable test force and the signals of force and displacement sensors are recorded. As a result, reference points for future control inputs are obtained. A major drawback of a frequently used calibration method for levelers is that the work rolls of multi-actuator gap levelers cannot be properly calibrated. In practice, the work rolls are manually adjusted by the maintenance personnel of the machine. In this case, backlash may cause the loaded work rolls to deviate from their intended positions. Thus, a new method to calibrate the position of the individually actuated work rolls is developed and tested.