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Oil‐in‐water (O/W) emulsion has been used in industrial rolling mills for many decades, but its lubrication mechanism is still not adequately understood. There is a need to understand the role of chemical ingredients and emulsifier in lubrication and tribological characteristics of rolling oil. With this purpose, the authors selected three commercially available O/W emulsions of different generations and of known industrial performance. The aim is to understand the lubrication mechanism of these rolling oils and to correlate the laboratory findings with that of industrial rolling mills.

The lubrication mechanism has been studied with the help of an ultra thin film interferometry EHD test rig, an advanced experimental rolling mill and a Coulter LS 230 instrument. Film thickness, rolling parameters and droplet size were measured. The coefficient of friction was computed with the help of the measured values of rolling parameters. Emulsion stability and saponification value (SAP) of the selected emulsions were also determined. The results of film thickness, rolling parameters and droplet size have been presented. The lubrication mechanism of the emulsions has been explained on the basis of film thickness, droplet size, emulsion stability, SAP value and coefficient of friction.

Results of the present study reveal that chemistry of O/W emulsions plays an important role in their film forming and tribological behavior. Rolling emulsions of relatively low stability, higher droplet size and high SAP value are found to provide better lubrication and lower coefficient of friction. The results of the present study correlate well with the actual industrial experience except those obtained on EHD test rig.

Coulter LS 230 instrument was available with M/s LUBRIZOL CORP., USA. Only limited study on droplet size was carried. Although the study carried out has given good information but it would have been more practical if the emulsion samples taken from the experimental mill stand would have been studied for droplet size.

From understanding point of view of lubrication mechanism of O/W emulsion, it will be useful for oil technologists, tribologists and rolling mill users.

The study is original in nature and gives information on lubrication mechanism of O/W emulsions in steel cold rolling of steel strips.

Aiming at the high temperature, high speed, high precision and high surface quality of the copper belt cold rolling, the purpose of this paper is to develop a new type of lubricant for cold rolled copper belt.

The component of the developed oil was determined based on the physical and chemical properties of the base oil and the tribological properties, the oxidation resistance properties, the rust resistance properties, the anti-foam properties, the demulsibility and the other properties of the additives. The orthogonal experiment method was used to determine the optimum adding amount of the additives; finally, the developed oil formulation was determined.

The physical and chemical experiment results show that the developed oil has a good performance of oil film bearing capacity and oxidation resistance. The simulation of rolling experiment found that the developed oil can significantly reduce rolling pressure and effectively reduce the friction in the process of rolling.

The experimental results show that the developed oil has excellent performance and can meet the requirement of lubrication in the process of cold rolling copper belt.

The purpose of this paper is to synthesize a microemulsion and investigate its tribological properties as lubricant. Magnesium alloy warm rolling experiments were conducted. Surface morphology was observed and wear form was summarized. The composition of surface residues was analyzed, which sheds light on the lubrication mechanism of microemulsion.

A microemulsion was prepared with a proper amount of oil, surfactant, cosurfactant, water and other additives for magnesium alloy strip warm rolling. Tribological properties, such as maximum non-seizure load (P_B), friction coefficient (μ) and wear scar diameter (D) of the microemulsion were measured and compared with those of emulsion and rolling oil on an MR-10A four-ball tribotester. The extreme pressure anti-wear coefficients (O) were calculated and compared. Warm rolling experiments were carried out on a Ф 170/400 × 300 mm four-high rolling mill at 240°C to compare the finish rolling thickness and surface quality of rolled AZ31B magnesium alloy strip under four lubrication states, namely, no lubrication, rolling oil, microemulsion and emulsion. The surface morphology after warm rolling was observed with confocal laser scanning microscope and scanning electron microscope, respectively. The composition of surface residues was analyzed with energy dispersive spectrometry and X-Ray photoelectron spectroscopy.

Surface morphology indicated that pitting wear, adhesive wear and ploughing wear were three main forms of wear in magnesium alloy warm rolling. Microemulsion had excellent lubrication properties with less residual oil remaining. Two types of adsorption layers formed on magnesium alloy strip surface were responsible for lubrication properties. MgSO₄ and magnesium stearate in the reaction layer played a key role in anti-wear and friction-reduction in warm rolling.

The study is original and gives valuable information on lubrication mechanism of microemulsion in warm rolling of magnesium alloy strips.

The purpose of this paper is to conduct a comprehensive experimental study to achieve optimal surface roughness of aluminum rolled with freshly ground rollers of two high rolling mills.

Various rolling oils and processing conditions are applied in the rolling process. Resultant surface roughness is measured with a profilometer; and surface topography of aluminum after rolling is observed under scanning electron microscope. In order to examine the oil film thickness (the most critical factor in rolling process), a planimeter is used to measure the area of oil patch resulting from a precisely controlled oil droplet, which in turn allows calculation of outlet oil film thickness as an approximation to inlet oil film thickness in the deformation region.

The experimental results indicate that two major factors have dominant impacts on aluminum's surface roughness in the rolling lubrication process: reduction of roller; and viscosity of lubrication oil. Based upon analysis of the experimental data, optimal roller reduction is found to be within range (23%, 30%) and optimal oil viscosity should be chosen, such that the ratio between inlet oil film thickness in the deformation region and the combined surface roughness is around 1.

According to the authors' observations, the above parameter choices generally assure excellent surface quality of aluminum after rolling.

The last stage of the cold rolling process is skin-pass rolling and one of its most significant goals is to obtain appropriate topography on the surface of the sheet steel used extensively such as in automotive industry. The purpose of this paper is to investigate the effect of thickness change and various reduction ratios on roughness transfer of DC04 grade sheet material.

DC04 grade sheet materials with different reduction ratios and several thicknesses were subjected to skin-pass rolling process in the rolling equipment with a two-high roll. Some roughness parameters were determined as a result of roughness measurements from the surfaces of roughened sheet materials.

While the roughness transfer is higher in 1-mm thick material in reduction ratios up to 430 micrometers; in reduction ratios above 430 micrometers, it is higher for 1.5-mm thick materials. As the reduction ratio increases in DC04 grade sheet materials, the homogeneity of the roughness distribution in 1-mm thickness sheet material deteriorates, while the roughness distribution in 1.5-mm thickness sheet material is more homogeneous.

This paper demonstrates how material thickness and reduction ratio affect the roughness transfer in skin-pass rolling. The results obtained can be used by optimizing in manufacturing processes.

The purpose of this study is to focus on numerical simulation investigations of deformation analysis of asymmetric break-down rolling of a hollow steel, which seriously affects the service life of the final product.

The 3D rigid-plastic thermo-mechanical coupled finite element method (FEM) for a large strain was used to analyze metal deformation in the deformation zone for asymmetric rolling with different roller diameters.

The distribution of stress, strain and dimension accuracy for different diameters was obtained. The results show that the additional shear strain which is different from the normal compression deformation is generated in an asymmetric rolling process. The higher the ratio between upper and lower diameters, the greater the additional shear deformation.

Asymmetric rolling is an important factor affecting the dimensional accuracy of the hollow steel. This study can provide a theoretical basis for developing a reasonable rolling process of the hollow steel.

The lower density of powder metallurgical (PM) gears compared to solid steel gears leads to not only a lower weight but also a lower load-carrying capacity. Therefore, PM gears are cold rolled before hardening to increase the density in the highly stressed surface zone and, thus, the flank load-carrying capacity. A further approach to increase the flank load-carrying capacity is the reduction of friction and wear in the tooth contact. The purpose of this paper is to analyze the hard rolling process as a new manufacturing step in the PM process chain to influence the boundary layer.

The investigation includes the new process of hard rolling, the variation of the cooling lubricant in the hard rolling process and the evaluation of its influence on the material properties and the flank load-carrying capacity. Therefore, the additives of the cooling lubricant are varied regarding the sulfur and phosphorous content. The load-carrying capacity is evaluated on disk-on-disk test rig and the material properties are evaluated by metallographic tests and boundary layer.

The results of the specimen characteristics in the micro and nano range show a significant influence of hard rolling on the residual stresses and the chemical surface composition. Because of hard rolling, residual compressive stresses as well as roughness are reduced and the flank load-carrying capacity is increased by high phosphorous content of the cooling lubricant.

This paper investigates a new manufacturing step to increase resource efficiency by increasing the flank load-carrying capacity of spur gears.

This paper uses numerical methods to investigate the collision and skidding of rolling elements in a cageless ball bearing. This paper aims to analyse the effects of the rotational speed and number of rolling elements on the rolling element collision and skidding.

Based on Hertzian theory and tribological theory, the collision contact model of the rolling element was established. Based on the proposed model, the differential equations of motion of the two degrees of freedom rolling element were constructed. The fourth-order Adams algorithm solved the collision contact force between the rolling elements. The sliding velocity between the rolling element and the inner and outer races was calculated.

The collision frequency and slip of rolling elements can be reduced by increasing the rotational speed appropriately and reducing the number of rolling elements by one.

The developed model can reveal the collision and slip characteristics of the rolling elements for cageless bearings. This study can provide theoretical guidance for the design and manufacture of cageless ball bearings.

The purpose of this paper is to provide a theoretical conceptualization of how data envelopment analysis (DEA) can be applied to rail freight rolling stock in order to develop a tariff for track access charges which is functionally dependent upon the derived relative benchmark values of performance.

It is posited that track access charges should be differentiated to reflect differences in the performance of rolling stock and that this can be achieved purely on the basis of technical and other characteristics. The performance benchmarking of rolling stock is proposed as the basis for formulating and justifying a performance-based tariff structure. Using DEA, relative index measures of rolling stock performance can be derived, benchmark performance can be identified and a tariff structure can be developed.

A workable approach to implementing the concept, utilizing existing in-house databases, is found to be feasible and a template for tariff setting is established.

In the absence of access to in-house technical data on rolling stock, which is commercially sensitive, no empirical application of the concept is possible.

There are many ways to improve the efficiency of a railway system. Many are inherently long term and involve significant investment. Using Sweden as an example, this paper proposes the more immediate, simpler and cheaper approach of incentivising the use of better rolling stock through appropriate track access charging. Such an approach should reduce the number of problems arising on the rail network and the costs imposed on other rail users, the infrastructure providers and society. Ultimately, the implementation of this approach would support the objective of increasing long-term robustness and reducing disruptions to railways.

The purpose of this study is to improve the global optimization ability of the Tabu search (TS) algorithm, and then improve the calculation efficiency and accuracy of rolling schedule in tandem cold rolling.

A case-based reasoning–Tabu search hybrid algorithm (CBRTS) has been presented. First, the case-based reasoning technology was adopted to obtain high-quality initial solution and then the TS algorithm was used for global optimization.

The optimization effect of CBRTS is compared with that of the traditional TS algorithm, and the analysis result indicates that the CBRTS has a faster convergence rate than TS, and the optimization results are closer to the global optimal. Meanwhile, the rolling schedule calculated by CBRTS is more reasonable, which can increase the production efficiency while giving full play to the capacity of equipment.

A CBRTS hybrid algorithm is presented. The strong dependence of the TS algorithm on the initial solution has been solved. The rolling schedule multi-objective optimization functions are established. The proposed algorithm is applied in a 1,450-mm tandem cold rolling production line. The improved method can reduce about half the iterations compared with the traditional one.