Traditional Rolling Research Articles

Study on surface properties of Ti-6Al-4V titanium alloy by ultrasonic rolling

In order to improve the surface performance of the key components of Ti-6Al-4 V titanium alloy and meet its requirements for surface performance and life in complex service environments, this study combines traditional mechanical rolling with high-frequency ultrasonic vibration, and achieves high-speed impact on the surface of titanium alloy and traditional rolling at the same time. Numerical simulation of ultrasonic rolling processing of titanium alloy workpiece is carried out, the residual stress and surface roughness of the workpiece after processing are analyzed, and the influence of different process parameters on it is explored. The results show that ultrasonic rolling processing can effectively improve the surface properties of Ti-6Al-4 V titanium alloy, so that the residual stress distribution of the workpiece is more uniform and increases with the increase of static force and amplitude. When the static force is 1000 N and the amplitude is 8 μm, the surface finishing effect is the best.

Constraining ring rolling of thin-walled conical rings with transverse ribs

As critical load-bearing components of aerospace equipment, thin-walled conical rings with inner transverse ribs (TWCRITR) are widely used for manufacturing rocket body, aircraft fuselage and space station shell et al., due to light weight, high strength and high load-bearing capacity. However, TWCRITR cannot be manufactured by traditional ring rolling (TRR), due to thin skin and high ribs. Aimed at this problem, a novel constraining ring rolling method (CRR) is proposed in this work to achieve the near-net-shape manufacturing of TWCRITR with high performance and efficiency. CRR innovatively uses a constraint roll and two baffles to fully constrain the diameter and height enlargement of ring, which ensures that the CRR process is still stable and the metal is enforced to flow axially to form high and wide ribs. Owing to the extreme geometry of TWCRITR and the complicated constraints of rolls in CRR of TWCRITR, the inherent relation between geometric and process parameters, stress state and metal flow is complicated, and it cannot be quantitatively determined by the FE simulation or experiment. Hence, the mechanical model which can determine the quantitative relation between geometric and process parameters, stress state and metal flow in CRR of TWCRITR is firstly established by using the slab method and upper bound method. Secondly, three new metal flow modes related with rib width in CRR of TWCRITR are found based on the established mechanical model. The first one is that the real-time height difference of two ribs slightly fluctuates and the two ribs almost grow synchronously when the width of two ribs is almost identical. The second one is that the rib with small width at the small end grows much faster than the rib with large width at the large end when the width difference of two ribs exceeds a critical value. The third one is that the rib with small width at the large end grows much faster than the rib with large width at the small end when the width difference of two ribs exceeds a critical value. Further, the quantitative relations between the metal flow resistance, divided-flow plane and rib growth under three metal flow modes are revealed theoretically, and consequently the mechanisms behind three metal flow modes in CRR of TWCRITR are clarified theoretically. Finally, the simulation and experiment for CRR of TWCRITR are conducted, and TWCRITR with 3 mm in skin thickness, 7 mm in rib width and 12.5 mm in rib height (the ratio of rib height to skin thickness is 4.16 and the ratio of rib width to skin thickness is 2.33) are stably rolled. Moreover, the roundness of rolled TWCRITR is good (it nearly approaches the inner surface roundness of constraint roll). The predicted values of rib height using the established mechanical model are in good accordance with the simulated and experimental ones, which validates the established mechanical model. Through analyzing the novel CRR process and complicated metal flow mechanisms, it is demonstrated that CRR is promising for manufacturing TWCRITR with high performance and efficiency.

Rolling Bearing Fault Diagnosis Based on Time-Frequency Compression Fusion and Residual Time-Frequency Mixed Attention Network

The traditional rolling bearing diagnosis algorithms have problems such as insufficient information on time-frequency images and poor feature extraction ability of the diagnosis model. These problems limit the improvement of diagnosis performance. In this article, the input of the time-frequency image and intelligent diagnosis algorithms are optimized. Firstly, the characteristics of two advanced time-frequency analysis algorithms are deeply analyzed, i.e., multisynchrosqueezing transform (MSST) and time-reassigned multisynchrosqueezing transform (TMSST). Then, we propose time-frequency compression fusion (TFCF) and a residual time-frequency mixed attention network (RTFANet). Among them, TFCF superposes and splices two time-frequency images to form dual-channel images, which can fully play the characteristics of multi-channel feature fusion of the convolutional kernel in the convolutional neural network. RTFANet assigns attention weight to the channels, time and frequency of time-frequency images, making the model pay attention to crucial time-frequency information. Meanwhile, the residual connection is introduced in the process of attention weight distribution to reduce the information loss of feature mapping. Experimental results show that the method converges after seven epochs, with a fast convergence rate and a recognition rate of 99.86%. Compared with other methods, the proposed method has better robustness and precision.

Integrated Optimization of Rolling Stock Scheduling and Flexible Train Formation Based on Passenger Demand for an Intercity High-Speed Railway

The key features of an intercity high-speed railway (IHSR) include its high frequency, the short intervals, and the short distances covered. The mode of rolling stock scheduling generally uses fixed segments. In view of the fact that intercity passenger demand has the characteristics of large fluctuations in terms of time and direction, the use of the traditional rolling stock scheduling plan with a fixed train formation will result in a mismatch between the train formation and passenger demand. In order to improve the matching of train formation and passenger demand and increase the utilization rate of rolling stocks, this paper puts forward the concept of flexible train formation by time period and constructs an integrated optimization model of the rolling stock scheduling and flexible train formation based on passenger demand. The model aims at minimizing the number of rolling stocks, the amount of coupling/decoupling necessary, and the deadhead time. The model takes into account constraints such as the connection method used, the source and destination of the rolling stock, the total amount of rolling stock, and the use of a flexible train formation. In addition, the Gurobi solver is used to accurately solve the problem through the linearization of the model. This paper also provides an example of the Beijing–Tianjin IHSR as a verification of the feasibility and effectiveness of the proposed model. The example compares the indicators in the fixed and flexible train formation modes. The results of the research show that, on the premise of meeting passenger demand, the flexible train formation mode can reduce the cost of rolling stock; increase the efficiency of rolling stock; improve the balance of rolling stock scheduling; and, consequently, provide a reference for the optimization of rolling stock scheduling plan with the background of “cost reduction and efficiency increase” in the railway industry.

Uterine torsion in Simmental crossbreed cow

This case report describes the treatment of uterine torsion in Simmental crossbreed cattle. The dam was five years old, twice parity, in nine months and ten days pregnancy. Based on the anamnesis, it is known that the cows show signs of restlessness, straining, more robust by the time. However, there was no visible edema in the vulva, no ruptured membranes, no legs and head of the fetus coming out of the dam's vulva. Tretment was carried out by traditional rolling until the maximum uterine lumen opening was obtained. The position of the fetus is head flexion posture, so to remove it vaginally, the head is repositioned first and then forced to pull it out until the fetus comes out. Post-treatment, the dam's condition was still weak, unable to stand up, did not want to eat, and only drank a little. The drugs given were analgesics-antipyretics (repeated in the afternoon), long-acting antibiotics, vitamin B1, and vitamins and minerals mixed. After a few hours, the dam was up and walking around, feeding and drinking, and the placenta completely separated. The fetus's condition was alive, female sex, weak condition, the condition improves after being given milk from the dam. It can be concluded that the case of uterine torsion in Simmental crossbreed cows has been successfully treated 24 hours after the signs of birth using the traditional rolling technique, and the fetus can be expelled vaginally. The condition of the dam and fetus after the treatment of uterine were torsion gradually became healthy.

An innovative constraining ring rolling process for manufacturing conical rings with thin sterna and high ribs

Conical rings with thin sterna and high ribs (CRTSHR) are key bearing-load parts of aerospace equipment, which are required to be manufactured with high performance and efficiency. Traditional ring rolling is the most preferred method for manufacturing high-performance ring parts, but it can hardly achieve the forming of CRTSHR due to the extreme geometry of CRTSHR. To solve this difficulty, an innovative constraining ring rolling process (CRR) is proposed in this paper to manufacture CRTSHR. To evaluate the proposed CRR and reveal its deformation behaviors, a thermomechanical coupled FE model for CRR of CRTSHR is established. Then, the experiment for CRR of CRTSHR is performed on a modified ring rolling machine, which proves that CRR of CRTSHR is feasible and the established FE model is reliable. Based on the reliable FE model, the metal flow mode in deformed CRTSHR is analyzed, and the deformation characteristics such as the stress state, strain distribution and the evolution of power parameters in CRR of CRTSHR are revealed. Finally, the influences of key parameters such as the friction factor between ring and molds, the diameter of idle roll and the feed velocity of idle roll on CRR of CRTSHR are investigated by FE simulation.

Temperature Influence on Section Uniformity of Casting Steel Rolled with the Hot-Core Heavy Reduction Rolling Process and Traditional Hot Rolling Process

Temperature Influence on Section Uniformity of Casting Steel Rolled with the Hot-Core Heavy Reduction Rolling Process and Traditional Hot Rolling Process

Rotordynamics of an Improved Face-Grinding Spindle: Rotational Stiffness of Thrust Bearing Increases Radial Stiffness of Spindle

Abstract The support is a key factor affecting performance of face-grinding spindle. However, advantage of traditional rolling element bearing is not highlighted when it is for large-size face grinding. This technical brief aims to develop a combined support for the face-grinding spindle consisting of a water-lubricated hydrostatic thrust bearing and two types of radial rolling bearings, and the flexible rotor dynamics of the spindle with the combined support is analyzed using the modified transfer matrix method. The results show that the rotational stiffness of water-lubricated hydrostatic thrust bearing can increase the radial stiffness of the face-grinding spindle, so the small-size rolling bearings can be utilized as the radial support for the spindle by aid of such rotational stiffness. A comparative study of comprehensive performance between the spindle supported by rolling bearings and the replacement spindle designed with our proposed combined support shows that the proposed one has technical advantage of large axial load-carrying capacity, low frictional power loss, low temperature rise, etc.

A Study on Early Stages of White Etching Crack Formation under Full Lubrication Conditions

The appearance of White Etching Cracks (WEC), not covered by the ISO 281 modified failure rate calculation, leads to difficulties in predicting bearing reliability. This uncertainty in bearing applications leads to a worldwide activity in order to understand and prevent this situation since the WEC failure mode deviates from the traditional Rolling Contact Fatigue (RCF) mode. Plenty of factors have been found to influence this phenomenon over the years, however the precise initiation of the WEC is still under debate. In order to understand the initiation and analyze the temporal evolution, interrupted tests on the same material were performed under conditions that were known to lead to WEC formation and RCF. To avoid the added complexity of boundary lubrication, a Deep Groove Ball Bearing (DGBB) test rig under full lubrication (Elastohydrodynamic Lubrication, EHL) was chosen. Within a standard operating mode, named Mode 1 (RCF), the bearings are solely subjected to a radial load. By suspending the tests at different time steps, a continuous progress of changes in the subsurface material structure seen as equiaxed grains with low dislocation densities, identified as ferrite, is observed. The bearings did not fail up to load cycles of 109. In contrast, a Mode 2 Electrical Charged Contact Fatigue (ECCF) test provoked the early formation of cracks and crack networks, first without WEA, then later with WEA. It became obvious when comparing Mode 1 (RCF) with Mode 2 (ECCF) that Mode 2 (ECCF) achieves far fewer load cycles until failure occurs.

A novel deep convolution multi-adversarial domain adaptation model for rolling bearing fault diagnosis

The traditional rolling bearing fault diagnosis methods are difficult to achieve effective cross-domain fault diagnosis. Therefore, a novel deep convolution multi-adversarial domain adaptation (DCMADA) model for rolling bearing fault diagnosis is proposed, which includes a feature extraction module, a domain adaptation module, and a fault identification module. In the feature extraction module, an improved deep residual network (ResNet) is used as the feature extractor to extract the transferable features from the raw vibration signals. In the domain adaptation module, the marginal and conditional distributions are adjusted using multi-kernel maximum mean discrepancy (MK-MMD) and multiple domain discriminators in the source and target domains, and an adaptive factor is designed to dynamically measure the relative importance of these two distributions. In the fault identification module, the classifier uses the extracted domain-invariant features to complete cross-domain fault identification. Experiments show that the model has superior transfer capability in cross-domain bearing fault diagnosis.

Mechanical properties and crystallographic texture of non-oriented electrical steel processed by repetitive bending under tension

Improving the magnetic properties of non-oriented electrical steel (NOES) through the optimization of crystallographic texture has been an on-going research activity for decades. However, using traditional rolling and annealing procedures, the obtained final textures were usually very similar, i.e., exhibiting the {111} (γ) and <110> (α) fibres, which were not the desired {001} texture (θ-fibre) for optimal magnetic quality. In the current work, a 1.8 wt% Si NOES was processed using a new sheet metal deformation method, i.e., repetitive bending under tension (R-BUT), also known as continuous bending under tension (C-BUT), to modify the texture of the electrical steel. The hot-rolled and annealed NOES plates were repeatedly bent and unbent when they were pulled under tension. The deformed plates were then heat treated at different temperatures for various times. Neutron diffraction and electron backscatter diffraction (EBSD) characterisation of the macro- and micro-textures proved that the R-BUT process significantly reduced the undesired {111} texture while promoting the {001} texture. The cube texture, which rarely formed after conventional rolling and annealing, was also seen in the R-BUT samples after annealing. It was shown that, the shear plastic deformation (induced by R-BUT) played a significant role in promoting the desired textures. In addition, the results indicated that the NOES processed by R-BUT could be deformed beyond its common formability limit, which may provide a method to address the poor workability challenge of high silicon electrical steels.

Shuffled rolling shutter for snapshot temporal imaging.

We propose a modification to the rolling shutter mechanism found in CMOS detectors by shuffling the pixels in every scanline. This potential hardware modification improves the sampling of the space-time datacube, allowing the recovery of high-speed videos from a single image using either tensor completion methods or reconstruction algorithms often used for compressive temporal video. We also present a design methodology for optimal sampling schemes and compare them to random shuffling. Simulations, and experimental results obtained by optically emulating the hardware, demonstrate the ability of the shuffled rolling shutter to capture images that allow reconstructing videos, which would otherwise be impossible when using the traditional rolling shutter mechanism.

The central deformation calculation and analysis of the heavy steel plate for the gradient temperature rolling

The traditional symmetrical rolling process may result in the insufficient central deformation of the heavy steel plate. The gradient temperature rolling (GTR) based on the ultra-fast cooling was adopted in order to improve the central deformation and keep the deformation along the thickness to be well distributed. The temperature and strain field of the gradient temperature rolling were obtained by the thermo-mechanical coupling finite element method combined with different surface heat transfer coefficient, plate thickness, work roll diameters and so on. The calculated results showed that the deformation was more likely to penetrate into the core compared with uniform temperature rolling (UTR). The central equivalent strain with GTR was increased by 44.3% maximum compared with UTR in the same case. The deformation along the thickness was well distributed compared to the UTR. The central deformation gradually increases with the increase of reduction rate, surface heat transfer coefficient, work roll diameters and speed ratio, while the central deformation almost unchanged with linear velocity. Furthermore, industrial application showed the deformation can penetrate into the core compared with the UTR and it can help to eliminate the band structure. In this study, the influencing law of equivalent strain along the thickness with different parameters was summarized. The fitting model to calculate the central equivalent strain after GTR was established according to the numerical results. It can provide reliable theory and technology support for the setting of various parameters for GTR.

Experimental fault detection of input gripping pliers in bottling plants

This paper presents a signal-based fault detection scheme for input gripping pliers of the blow molding machine in plastic bottling plants, using accelerometers data. The focus of the diagnosis is on the bearings that support the pliers movements on their mechanical cam. Therationale of the algorithm lies in interpreting the pliers\’ bearings as the balls in a traditional rolling bearing. Then, strategies inspired by bearing diagnosis are employed and adapted to the specific case of this work. The developed algorithm is validated with experimental tests, following a fault injection step, directly on the real blow molding machine

Investigation of a Vibrational Tillage Roller on Soybean Crops

Currently, one of the main tasks facing agricultural production is to provide the country’s population with high-quality food with a maximum reduction in the share of imports. To get stable and high yields, it is necessary to use modern equipment. Recently, the main emphasis has been on equipping machines with electronics, while less and less attention is paid to the design of agricultural machines. Despite the large number of mechanization means of soil rolling, they often do not ensure the fulfillment of agrotechnical requirements for soil rolling. (Research purpose) The research purpose is to test the effectiveness of using the developed vibrating roller in the field on soybean crops. (Materials and methods) The article presents the fundamentally new vibration roller, the distinctive feature of which is the presence of a passive drive of disbalancers mounted on the rotating axis of a hollow cylinder. In the field conditions, the quality of work of the developed vibrating roller and mass-produced rollers was compared using the coefficient of compliance with the standard. (Results and discussion) The use of a vibrating roller give a higher quality of soil rolling, a 42 percent better value of the optimization criterion compared to the KKZ-6 roller. The soybean seedlings are more harmonious compared to rolling in other rollers. (Conclusions) The rolling of soybean crops with the proposed vibrating roller allowed to increase its yield to 33.5 quintals per hectare (by 27.4 percent) compared to 26.3 quintals per hectare after rolling the crops with the KKZ-6 rollers mass- produced by the industry. The innovative features of the proposed vibrating roller make it possible, when implementing the traditional rolling technology, to obtain a large yield practically without increasing capital investments, thereby increasing the profitability of legume production.

Modelling of Deformation Resistance with Big Data and Its Application in the Prediction of Rolling Force of Thick Plate

The precision of traditional deformation resistance model is limited, which leads to the inaccuracy of the existing rolling force model. In this paper, the back propagation (BP) neural network model was established according to the industrial big data to accurately predict the deformation resistance. Then, a new rolling force model was established by using the BP neural network model. During the establishment of the neural network model, the data set of deformation resistance was established, which was calculated back from the actual rolling force data. Based on the data set after normalization, the BP neural network model of deformation resistance was established through the optimization of algorithm and network structure. It is shown that both the prediction accuracy of the neural network model on the training set and the test set are high, indicating that the generalization ability of the model is strong. The neural network model of the deformation resistance is compared with the theoretical one, and the maximum error is only 3.96%. Furthermore, by comparison with the traditional rolling force model, it is found that the prediction accuracy of the rolling force model imbedding with the present neural network model is improved obviously. The maximum error of the present rolling force model is just 3.86%. The research in this paper provides a new way to improve the prediction accuracy of rolling force model.

Effect of thermal cycles on the microstructure and mechanical properties of cold-resistant steel 09CrNi2MoCu during laser deposition

The formation of microstructure features of cold-resistant bainite-martensite steel 09CrNi2MoCu has been investigated. Thermal cycles during direct laser deposition were studied. The thermal cycles at different points of the deposited samples were investigated. The thermal cycles and CCT diagrams on microstructure formation and mechanical properties have been analyzed. The numerical calculation of the three-dimensional thermal conductivity problem by the finite element method is carried out. The received data of experimentally measured thermal cycles and the calculated data have shown good coincidence of temperature values. On the basis of the obtained data the calculated dependence of inter-layer temperature at depositing the sample with and without a pause is given. The microstructure and mechanical properties of the samples in the initial state and after heat treatment have been studied and compared with traditional hot rolling. The microstructure features at different pauses between passes in different parts of the obtained samples were revealed. The effect on static tensile and impact toughness at -40°C in the bred and heat-treated state was investigated.

Design and Modeling of 2 MW AMB Rotor With Three Radial Bearing-Sensor Planes

Active magnetic bearings (AMBs) provide reliable solution for high-speed rotors, where oil-free and reliable operation are crucial. In high-power applications benefits of AMBs, compared to traditional rolling element bearings or fluid film bearings, are highly valued. Typical AMB rotors comprise two radial AMBs, which are designed with compressor or generator wheels integrated on the rotor. AMB dimensions and locations are carefully selected for each new application. The system design is being iterated such that the nodes of the lowest frequency rotor bending modes are sufficiently far away from the AMB and sensor nodes to ensure robust AMB control. The design is very challenging and cost sensitive. This work focuses on electromagnetic design, modeling, and control of fully levitated AMB-rotor with three radial AMBs. The additional bearing ensures that the same design can be reused with different applications and regardless of the changes in locations of nodes of the first bending mode. The control plant is modeled based on flexible rotor dynamics; while bearing inductances and forces are modeled with 2-D and 3-D finite element method (FEM) electromagnetic simulations. The presented multi-input multi-output (MIMO) model-based control is coupled and centralized with three actuator-sensor pairs for radial suspension. The control design is verified in simulations using nonlinear engineering models. Additionally, experimental identification results are included.

Controlled Precipitation and Strengthening in a CuFeNiMn High-Entropy Alloy

A novel precipitation-strengthened CuFeNiMn high-entropy alloy without sigma-sensitive Cr and rare Co was prepared by traditional cast, homogenization, cold rolling and aging. The second phase was controllably precipitated by aging, which was identified as Cu-rich face-centered-cubic (FCC) phases, distributed dispersedly in the FCC-structured matrix. Two characteristic aging parameters were selected to study the precipitate features and corresponding tensile properties. After aging at 800 °C/1 h, the alloy exhibits a good integrated performance, i.e. tensile yield strength, ultimate tensile strength, and elongation of 825 MPa, 932 MPa, and 18%, respectively. Increasing the aging temperature to 900 °C, the yield strength is decreased significantly, but the work hardening rate and elongation are increased. The Cu-rich particles play a predominant part in strengthening by dislocation shearing, different from the by-pass mechanism of the hard ceramic and intermetallic precipitates.

Microstructure and high-temperature mechanical properties of RAFM steel processed by friction stir processing combined with tempering heat treatment

In this study, the microstructure and high-temperature mechanical properties of a 9Cr-1.5W reduced activation ferritic/martensitic (RAFM) steel processed by friction stir processing (FSP) combined with a tempering treatment were investigated. During the FSP, lath martensite microstructures containing needle-like M3C and nano-sized MX precipitates were formed in the steel owing to the severe plastic deformation and high cooling rate. The steel subjected to FSP and the tempering treatment at 700 °C for 60 min (FSP-T60) had a fine-grained microstructure consisting of ferrite and martensite, and a large number of M23C6 precipitates formed at the grain boundaries and within the grains. The FSP-T60 steel showed an increase of ∼100 MPa in the tensile strength at 600 °C and a high elongation of 26% as compared to the steel prepared via traditional hot rolling, normalizing, and tempering. The FSP-T60 steel also exhibited improved creep resistance with a creep rupture time of 4523 h at 600 °C/210 MPa. The increase in the strength and ductility of the steel can be attributed to its refined grain structure and the high density and dispersion of the M23C6 precipitates. Meanwhile, the homogeneous distribution and refinement of M23C6 carbides could reduce the growth rate of the Laves phase during creep, thus extending the formation time of the creep cavities and cracks and further increasing the creep rupture time of the steel.