Technologies for high-temperature batch annealing of grain-oriented electrical steel: An overview

The production of grain-oriented, electrical steel consists of a series of processes that lead to a product with superior magnetic properties used in transformers due to the low core loss. The unique properties are gained during the process of secondary recrystallization and abnormal grain growth. The abnormal grain growth occurs during a process of special thermal treatment with careful control over the heating rate, pressure, and type of gas used as atmospheric pressure during the process. The process of thermal treatment is known as high-temperature annealing. Investigating of developing the process hardware is crucially important to sustain energy-efficient processes and to maintain excellent final product properties. This research presents an overview of the technology of high-temperature coil annealing (HTCA) furnaces used at Cogent Power Orb, UK. The research focuses on some specific details of running, managing, and controlling the operation of the HTCA furnaces during the annealing process. The research provides energy analysis of the annealing process at Cogent Power Orb. Different factors were examined to identify the main factors that contribute to the high energy consumption. Actual data were collected from the annealing furnace control system. The raw data were processed and analyzed carefully to examine different factors, namely, steel charge weight, furnace on-time, and furnace heating elements. The study focused then on one specific factor, namely, annealing cycle time, and investigated further the way that this factor affects the process energy consumption. It was found that one of the main reasons for the long cycle duration and the high energy consumption is the failure of the heating elements during the cycle. The research discussed the area of improvements in the process hardware with a particular focus on the furnace design and the potential of introducing convection currents to overcome failure in the heating elements and thus reduce the process on time

An Investigation on the Teeth Crowning Effects on the Transient EHL Performance of Large-Scale Wind Turbine Spur Gears

Crowning is applied to wind turbine gears, including spur gears, to ensure adequate stress distribution and contact localization in wind turbine main gearbox gears to improve the gear performance in the presence of misalignments. Each gear tooth is crowned along the face width using a parabolic curve that graduates from a maximum height at the edges and vanishes at the center of the tooth flank. This crowning transfers the elastohydrodynamic contact problem from a line to a point contact case where the surface curvatures and pressure gradient are considered in both directions of the solution space. A wide range of longitudinal crowning heights is considered in this analysis under heavily loaded teeth for typical large-scale wind turbine gears. Furthermore, the variation in the velocities is considered in the analysis. The full transient elastohydrodynamic point contact solution considers the non-Newtonian oil behavior, where the numerical solution is based on the finite difference method. This work is focused on the evaluation of the effectiveness of teeth’s longitudinal crowning in terms of the consequences on the resulting pressure distribution and the corresponding film thickness. The modification of the tooth flank significantly elevates the film thickness levels over the zones close to the tooth edges without a significant increase in the pressure values. Moreover, the zone close to the tooth edges from both sides, where the pressure is expected to drop to the ambient pressure, is extended as a result of the flank modification

Chemical resistance of NR/SBR rubber blends for surfaces corrosion protection of metallic tanks in petrochemical industries

In this work, a series of Natural Rubber (NR)/Styrene Butadiene Rubber (SBR) blends were formulated to protect metallic petrochemical storage tanks from corrosive media. Therefore, these blends tested against a 10% HCl solution for 72 hr at room temperature. Blends series were prepared with different ratios of NR/SBR; 25/75, 30/70, 35/65, 40/60, 45/55, 50/50, and 55/45. Three types of carbon black (N-330, N-660, and N-762) were added individually to the 45/55 blend. Hardness, tensile strength, modulus, and elongation properties were tested before and after immersion in the 10% HCl attack media. All these mechanical properties decreased after immersion action accept hardness property. Up to 45 phr NR content, the hardness increased linearly independent on immersion action, but HCl immersion gives higher hardness values. Tensile strength increased up to 40 phr NR content with and without immersion and the immersion action decreased tensile values. The highest elongation value obtained with 35/65 blend with and without immersion. The 45 phr NR content gives the higher modulus, while the lowest value obtained with the 30 phhr content. For 45/55 blend, the hardness increased as the carbon black particle size decreased and immersion action gives higher hardness values. The tensile strength decreased linearly with the carbon black surface area, while with the medium surface area, the highest modulus and lowest elongation obtained

A New Geometrical Design to Overcome the Asymmetric Pressure Problem and the Resulting Response of Rotor-Bearing System to Unbalance Excitation

Improving the bearing design helps in reducing the negative consequences related to errors in installation, manufacturing, deflections under severe loading conditions, progressive wear of machine elements, and many other aspects. One of the methods of such a design improvement effort is changing the bearing profile along the bearing width to compensate for the reduction in the geometrical gap between the shaft and the bearing inner surface due to the aforementioned causes. Since in all rotating machinery, unbalance usually exists at some level, this paper deals with the response of this modified bearing to unbalanced excitation to evaluate the effectiveness of such geometrical design on the dynamic characteristics of the rotor-bearing system. The numerical solution is performed using the finite difference method by assuming Reynolds boundary conditions to determine the cavitation limits, and the 4th-order Range-Kutta method is used to determine the time responses resulting from the unbalance excitation. The time responses to this type of excitation show that the rotor-bearing with the improved geometrical design is more stable, particularly at high speeds. In addition, this modification leads to an improvement in the lubricant layer thickness and the reduction in the levels of the generated pressure between the surfaces despite the presence of large deviations from the perfectly aligned bearing system. Furthermore, the suggested geometrical design overcomes the problem of asymmetricity in the pressure field resulting from the shaft deviation to a large extent. The results of this work (the enhancement in the level of the film thickness and the improvement in the dynamic response of the system as well as the reduction of the maximum pressure value) extend the range of misalignment in which the rotor bearing systems can operate safely which represents a significant step in designing the rotor-bearing system

Analysis of the Dynamic Response of Variable Bearing Design Under Impact Load Using Taguchi Method

In order to analyze the effect of using variable bearing profiles on the journal dynamic response under impact load, a Taguchi method-based model is established. The use of such profiles is performed to reduce the effect of shaft misalignment which is an unavoidable problem in the typical journal bearing applications. A 3D misalignment model is used and three forms of bearing profile are considered in the current work. The numerical solution is performed using the finite difference method and the equations of motion are solved by the 4th-order Rung-Kuta method. Results show that using a parabolic shape for the bearing profile at the positions of maximum misalignment effect (bearing edges) gives the best outcome in reducing the pressure levels and increasing the lubricant thickness. The critical speed is also enhanced in comparison with the ideal aligned design. Furthermore, using the optimized design, the response of the system to the impact load is also improved in terms of the X and Y displacement of the journal center

On the Use of Taguchi Method in the Analysis of the Dynamic Response of Variable Bearing Design under Impact Load

Optimizing the bearing design is an essential step to maintain safe operation and extend the bearing life. Taguchi method is one of the powerful methods in this direction, which can be used to assess the geometrical design parameters under shaft deviation. Shaft deviation is unavoidable in the industrial applications of journal bearing. It results from installation and manufacturing errors, bearing deformation, asymmetric loading, and many other sources. This work investigates the use of three bearing profiles with a wide range of geometrical characteristics to minimize the deviation negative effects. These designs modified the inner bearing surface in a linear, parabolic, or cubic shape. A general 3D deviation representation is considered in the analysis where the deviations in the horizontal and vertical directions are taken into consideration. The analysis is performed for a finite-length journal bearing using the Taguchi method to determine the optimal design characteristics. This analysis is achieved in terms of the rotor critical speed and the film thickness of the lubricant. Furthermore, the system response to an impact load is analyzed. The finite difference method is used in the analysis to solve the governing equations of the hydrodynamic problem, and the 4th-order Range Kutta solution is considered to solve the motion equations of the rotor under the impact load. Results show that using the suggested designs enhances the system’s critical speed, elevates the thickness of the lubricant layer, and extends the safe operation limits under impact load. The parabolic profile gives the most effective outcome where the shaft trajectory under impact excitation is very close to the ideal journal-bearing case. The suggested design reduces the maximum pressure by 17.07%, increases the minimum film thickness by 175.04%, and increases the critical speed by 23.42%