scholarly journals Thermal Camber and Temperature Evolution on Work Roll during Aluminum Hot Rolling

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1434
Author(s):  
Evangelos Gavalas ◽  
Spyros Papaefthymiou
Keyword(s):  
Steady State ◽  
Process Parameters ◽  
Hot Rolling ◽  
Work Roll ◽  
Temperature Evolution ◽  
Entry And Exit ◽  
Cooling Strategy ◽  
Roll Temperature ◽  
Significant Difference ◽  
Geometric Variation

Flatness is an important quality characteristic for rolled products. Modern hot rolling mills are equipped with actuators that can modify the uneven thickness distribution across the width of the strip (crown), taking into account online measurements of various process parameters such as temperature, force and exit strip profile, either automatically or manually by the operator. However, the crown is also influenced by many parameters that cannot easily be measured during production, such as work roll temperature evolution through thickness and roll geometric variation due to thermal expansion (thermal camber). These have an impact on the strip flatness. In this paper, a thermo-mechanical finite element model on LS-DYNA™ software was utilized to predict the influence of process parameters, and more specifically strip temperature, cooling strategy (application of cooling on the entry or entry and exit side simultaneously) and roll core temperature, on the evolution of roll temperature and thermal camber. The model was initially validated with industrial data. The results indicate that the application of both entry and exit cooling is ~30% more efficient compared to the entry cooling only, thus the thermal camber will be reduced by 2 μm. A hotter roll (380 K) is more stable compared to the cold roll (340 K), showing also an improvement of 2 μm. The hotter roll will also reach a thermal steady state on the surface faster compared to the colder one, without making a significant difference on the steady state temperature. Strip temperature plays a roll in the thermal camber evolution, but it is a less important parameter compared to cooling strategy and roll temperature.

scholarly journals Simulation of Thermal Stress and Fatigue Life Prediction of High Speed Steel Work Roll during Hot Rolling Considering the Initial Residual Stress

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 966 ◽  
Author(s):  
Kejun Hu ◽  
Fuxian Zhu ◽  
Jufang Chen ◽  
Nao-Aki Noda ◽  
Wenqin Han ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Fatigue Life ◽  
Hot Rolling ◽  
Work Roll ◽  
Roll Surface ◽  
Initial Residual Stress ◽  
Thermal Fatigue Life ◽  
Cooling Conditions ◽  
Roll Temperature

Considerable residual stress is produced during heat treatment. Compressive residual stress at the shell is conductive to improving the thermal fatigue life of a work roll, while tensile stress in the core could cause thermal breakage. In hot rolling, thermal stress occurs under the heating-cooling cycles over the roll surface due to the contact with the hot strip and water spray cooling. The combination of thermal stress and residual stress remarkably influences the life of a work roll. In this paper, finite element method (FEM) simulation of hot rolling is performed by treating the residual stress as the initial stress. Afterwards, the effects of the initial roll temperature and cooling conditions on thermal stress considering the initial residual stress are discussed. Lastly, the thermal fatigue life of a work roll is estimated based on the strain life model. The higher initial roll temperature causes a higher temperature but a lower compressive thermal stress at the roll surface. The surface temperature and compressive stress increase significantly in the insufficient cooling conditions, as well as the center tensile stress. The calculation of the fatigue life of a work roll based on the universal slopes model according to the 10% rule and 20% rule is reasonable compared with experimental results.

Inhomogeneity of temperature distribution through thickness of the aluminium strip during hot rolling

2011 ◽  
Vol 225 (12) ◽  
pp. 2938-2952 ◽  
Author(s):  
H R Rezaei Ashtiani ◽  
H Bisadi ◽  
M H Parsa
Keyword(s):  
Temperature Distribution ◽  
Hot Rolling ◽  
Work Roll ◽  
Three Dimensions ◽  
Temperature Fields ◽  
Temperature History ◽  
Rolled Strip ◽  
Fe Model ◽  
Temperature Inhomogeneity ◽  
Roll Temperature

Temperature distribution and inhomogeneity of its through thickness of the strip play an essential role in hot rolling processes, where both the strip and work-roll behaviour are affected strongly by these temperature fields and the microstructural and mechanical properties through thickness of hot rolled strip depend on this temperature inhomogeneity within the strip being deformed during hot rolling. In this investigation, a mathematical model was developed to predict the thermal history and inhomogeneity of temperature through thickness of an aluminium alloy strip undergoing single-stand hot plate rolling using the commercial finite element (FE) package, ABAQUS/Explicit in three dimensions. To estimate the reliability of the numerical analysis, the FE model was validated using experimental roll force and torque data and also temperature history at the centre-line of strip; good agreement was found between the two sets of predicated and experimental results. The effects of various process parameters, such as rolling speed, interface heat-transfer and friction coefficients between strip and work roll, initial thickness of the strip, and work-roll temperature and diameter on the temperature inhomogeneity, is considered.

scholarly journals Prediction and Control Technology of Stainless Steel Quarter Buckle in Hot Rolling

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1060
Author(s):  
Hui Li ◽  
Chihuan Yao ◽  
Jian Shao ◽  
Anrui He ◽  
Zhou Zhou ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Process Parameters ◽  
Hot Rolling ◽  
Shape Control ◽  
New Technology ◽  
Work Roll ◽  
Control Technology ◽  
Steel Strips ◽  
Prediction And Control ◽  
And Control

To obtain the good flatness of hot-rolled stainless-steel strips, high-precision shape control has always been the focus of research. In hot rolling, the quadratic wave (centre buckle and edge wave) can usually be controlled effectively. However, the quarter buckle of the strip is still a challenge to solve. In this paper, a prediction model of roll deflection and material flow is established to study the change rule and control technology of the quarter buckle. The effects of the process parameters on the quarter buckle are analysed quantitatively. The process parameters affect the quarter buckle and the quadratic wave simultaneously. This coupling makes the control of the quarter buckle difficult. The distribution of lateral temperature and the quartic crown of the strip have less effect on the quadratic wave but have a great effect on the quarter buckle. Finally, a new technology for work roll contour is developed to improve the quarter buckle. Through industrial application, the model and the new contour are proved to be effective.

Association of CYP2D6*10 (c. 100 C>T) Genotype with Z-END Concentration in Patients with Breast Cancer Receiving Tamoxifen Therapy in Indonesian Population

2019 ◽  
Vol 19 (8) ◽  
pp. 1198-1206 ◽  
Author(s):  
Yenny ◽  
Sonar S. Panigoro ◽  
Denni J. Purwanto ◽  
Adi Hidayat ◽  
Melva Louisa ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Steady State ◽  
Ultra Performance Liquid Chromatography ◽  
Cross Sectional Study ◽  
Threshold Concentration ◽  
Breast Cancer Patients ◽  
Cross Sectional ◽  
Significant Difference ◽  
Pcr Rflp ◽  
Liquid Chromatography Tandem Mass

Background: Tamoxifen (TAM) is a frequently used hormonal prodrug for patients with breast cancer that needs to be activated by cytochrome P450 2D6 (CYP2D6) into Zusammen-endoxifen (Z-END). Objective: The purpose of the study was to determine the association between CYP2D6*10 (c.100C>T) genotype and attainment of the plasma steady-state Z-END minimal threshold concentration (MTC) in Indonesian women with breast cancer. Methods: A cross-sectional study was performed in 125 ambulatory patients with breast cancer consuming TAM at 20 mg/day for at least 4 months. The frequency distribution of CYP2D6*10 (c.100C>T) genotypes (C/C: wild type; C/T: heterozygous mutant; T/T: homozygous mutant) was detected using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), the results of which were subsequently confirmed by sequencing. The genotypes were categorized into plasma Z- END concentrations of <5.9 ng/mL and ≥5.9 ng/mL, which were measured using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Results: Percentages of C/C, CT, and T/T genotypes were 22.4%, 29.6%, and 48.8%, respectively. Median (25-75%) Z-END concentrations in C/C, C/T, and T/T genotypes were 9.58 (0.7-6.0), 9.86 (0.7-26.6), and 3.76 (0.9-26.6) ng/mL, respectively. Statistical analysis showed a significant difference in median Z-END concentration between patients with T/T genotype and those with C/C or C/T genotypes (p<0.001). There was a significant association between CYP2D6*10 (c.100C>T) genotypes and attainment of plasma steady-state Z-END MTC (p<0.001). Conclusion: There was a significant association between CYP2D6*10 (c.100C>T) and attainment of plasma steady-state Z-END MTC in Indonesian breast cancer patients receiving TAM at a dose of 20 mg/day.

scholarly journals Modeling and Optimizing the Multi-Objective Portfolio Optimization Problem with Trapezoidal Fuzzy Parameters

2021 ◽  
Vol 26 (2) ◽  
pp. 36
Author(s):  
Alejandro Estrada-Padilla ◽  
Daniela Lopez-Garcia ◽  
Claudia Gómez-Santillán ◽  
Héctor Joaquín Fraire-Huacuja ◽  
Laura Cruz-Reyes ◽  
...  
Keyword(s):  
Steady State ◽  
Portfolio Optimization ◽  
Optimization Problem ◽  
Solution Process ◽  
Density Estimator ◽  
Nsga Ii ◽  
Spatial Spread ◽  
Multi Objective ◽  
Significant Difference ◽  
Portfolio Optimization Problem

A common issue in the Multi-Objective Portfolio Optimization Problem (MOPOP) is the presence of uncertainty that affects individual decisions, e.g., variations on resources or benefits of projects. Fuzzy numbers are successful in dealing with imprecise numerical quantities, and they found numerous applications in optimization. However, so far, they have not been used to tackle uncertainty in MOPOP. Hence, this work proposes to tackle MOPOP’s uncertainty with a new optimization model based on fuzzy trapezoidal parameters. Additionally, it proposes three novel steady-state algorithms as the model’s solution process. One approach integrates the Fuzzy Adaptive Multi-objective Evolutionary (FAME) methodology; the other two apply the Non-Dominated Genetic Algorithm (NSGA-II) methodology. One steady-state algorithm uses the Spatial Spread Deviation as a density estimator to improve the Pareto fronts’ distribution. This research work’s final contribution is developing a new defuzzification mapping that allows measuring algorithms’ performance using widely known metrics. The results show a significant difference in performance favoring the proposed steady-state algorithm based on the FAME methodology.

scholarly journals Determinants of mRNA stability in Dictyostelium discoideum amoebae: differences in poly(A) tail length, ribosome loading, and mRNA size cannot account for the heterogeneity of mRNA decay rates.

1988 ◽  
Vol 8 (5) ◽  
pp. 1957-1969 ◽  
Author(s):  
R A Shapiro ◽  
D Herrick ◽  
R E Manrow ◽  
D Blinder ◽  
A Jacobson
Keyword(s):  
Steady State ◽  
Dictyostelium Discoideum ◽  
Mrna Decay ◽  
Decay Rates ◽  
Time Dependent ◽  
Translational Efficiency ◽  
Cdna Clones ◽  
Dependent Manner ◽  
Significant Difference ◽  
Kinetics Of

As an approach to understanding the structures and mechanisms which determine mRNA decay rates, we have cloned and begun to characterize cDNAs which encode mRNAs representative of the stability extremes in the poly(A)+ RNA population of Dictyostelium discoideum amoebae. The cDNA clones were identified in a screening procedure which was based on the occurrence of poly(A) shortening during mRNA aging. mRNA half-lives were determined by hybridization of poly(A)+ RNA, isolated from cells labeled in a 32PO4 pulse-chase, to dots of excess cloned DNA. Individual mRNAs decayed with unique first-order decay rates ranging from 0.9 to 9.6 h, indicating that the complex decay kinetics of total poly(A)+ RNA in D. discoideum amoebae reflect the sum of the decay rates of individual mRNAs. Using specific probes derived from these cDNA clones, we have compared the sizes, extents of ribosome loading, and poly(A) tail lengths of stable, moderately stable, and unstable mRNAs. We found (i) no correlation between mRNA size and decay rate; (ii) no significant difference in the number of ribosomes per unit length of stable versus unstable mRNAs, and (iii) a general inverse relationship between mRNA decay rates and poly(A) tail lengths. Collectively, these observations indicate that mRNA decay in D. discoideum amoebae cannot be explained in terms of random nucleolytic events. The possibility that specific 3'-structural determinants can confer mRNA instability is suggested by a comparison of the labeling and turnover kinetics of different actin mRNAs. A correlation was observed between the steady-state percentage of a given mRNA found in polysomes and its degree of instability; i.e., unstable mRNAs were more efficiently recruited into polysomes than stable mRNAs. Since stable mRNAs are, on average, "older" than unstable mRNAs, this correlation may reflect a translational role for mRNA modifications that change in a time-dependent manner. Our previous studies have demonstrated both a time-dependent shortening and a possible translational role for the 3' poly(A) tracts of mRNA. We suggest, therefore, that the observed differences in the translational efficiency of stable and unstable mRNAs may, in part, be attributable to differences in steady-state poly(A) tail lengths.

scholarly journals Finite elements prediction of thermal stresses in work roll of hot rolling mills

2010 ◽  
Vol 2 (1) ◽  
pp. 707-716 ◽  
Author(s):  
D. Benasciutti ◽  
E. Brusa ◽  
G. Bazzaro
Keyword(s):  
Finite Elements ◽  
Hot Rolling ◽  
Thermal Stresses ◽  
Work Roll ◽  
Rolling Mills

scholarly journals Sex-Related Differences in the Maximal Lactate Steady State

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 154 ◽  
Author(s):  
Paul Hafen ◽  
Pat Vehrs
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Steady State ◽  
Respiratory Exchange Ratio ◽  
Time To Exhaustion ◽  
Distance Runners ◽  
Maximal Lactate Steady State ◽  
Training Tool ◽  
Significant Difference ◽  
Males And Females

The maximal lactate steady state (MLSS) is one of the factors that differentiates performance in aerobic events. The purpose of this study was to investigate the sex differences in oxygen consumption (VO2), heart rate (HR), and the respiratory exchange ratio (RER) at the MLSS in well-trained distance runners. Twenty-two (12 female, 10 male) well-trained distance runners (23 ± 5.0 years) performed multiple 30-min steady-state runs to determine their MLSS, during which blood lactate and respiratory gas exchange measures were taken. To interpret the MLSS intensity as a training tool, runners completed a time-to-exhaustion (TTE) run at their MLSS. The relative intensity at which the MLSS occurred was identical between males and females according to both oxygen consumption (83 ± 5 %O2max) and heart rate (89 ± 7 %HRmax). However, female runners displayed a significantly lower RER at MLSS compared to male runners (p < 0.0001; 0.84 ± 0.02 vs. 0.88 ± 0.04, respectively). There was not a significant difference in TTE at MLSS between males (79 ± 17 min) and females (80 ± 25 min). Due to the observed difference in the RER at the MLSS, it is suggested that RER derived estimates of MLSS be sex-specific. While the RER data suggest that the MLSS represents different metabolic intensities for males and females, the relative training load of MLSS appears to be similar in males and female runners.

The Comparison of Aerodynamic Performance Data Acquired From Thermal Measurements and a Torquemeter on a Compressor Impeller

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Natalie R. Smith ◽  
Timothy C. Allison ◽  
Jason C. Wilkes ◽  
Christopher Clarke ◽  
Michael Cave
Keyword(s):  
Steady State ◽  
Heat Loss ◽  
Performance Metrics ◽  
Aerodynamic Performance ◽  
Performance Data ◽  
Testing Time ◽  
Southwest Research Institute ◽  
Significant Difference ◽  
Thermal Measurements ◽  
Isentropic Efficiency

Full-thermal heat-soak of machinery is vital for acquiring accurate aerodynamic performance data, but this process often requires significant testing time to allow all facility components to reach a steady-state temperature. Even still, there is the potential for heat loss in a well-insulated facility, and this can lead to inaccurate results. The implementation of a torquemeter to calculate performance metrics, such as isentropic efficiency, has two potential advantages: (1) the method is not susceptible to effects due to thermal heat loss in the facility, and (2) a torquemeter directly measures actual torque, and thus work, input, which eliminates the need to fully heat-soak to measure the actual enthalpy rise of the gas. This paper presents a comparison of aerodynamic performance metrics calculated both from data acquired with thermal measurements as well as from a torquemeter. These tests were conducted over five speedlines for a shrouded impeller in the Southwest Research Institute Single Stage Test Rig facility. Isentropic efficiency calculated from the torquemeter was approximately 1–2 efficiency points lower than the isentropic efficiency based on thermal measurements. This corresponds to approximately 0.5–1 °C in heat loss in the discharge collector and piping. Furthermore, observations from three full-thermal heat-soak points indicate the significant difference in time required to reach steady-state performance within measurement uncertainty tolerances between the torque-based and thermal-based methods. This comparison, while largely suspected, has not yet been studied in previous publications.

Sign in / Sign up

Export Citation Format

Share Document