Increasing of Long Products Rolling Efficiency: Modernization of Stelmor Air Cooling Line to Obtain Sorbitized Wire Rod

Most national companies are seeking to reduce costs, improve technological processes and increase profitability. The steel industry is no exception - an example of cost reduction is a technology of sorbitized wire rod production. This technology can improve the performance characteristics of wore rod and reduce the number of patenting stages during metalware production. The developed technology has been tested in the CIS countries Stelmor lines, and its task is to eliminate the significant disadvantages of these lines: the absence of differential cooling on the conveyor width, insufficient cooling rate of air cooling sections, the lack of frequency regulated speed control for electric motors. Eliminating these disadvantages and developing new cooling modes using the software, based on the original mathematical model, allows for the production of sorbitized wire rod with high performance characteristics, provided with increased level of pearlite dispersion (1-2 points for at least 85% of area). Each intense and retarded cooling section has to be fitted with adjustable flaps controlled by electric motors, ensuring the alignment rod temperature at the roller conveyor width. Before the start of the reconstruction of the cooling line a detailed technical and technological audit is required to identify and eliminate the causes that lead to uncontrolled temperature deviations or wire rod laying deviations on the cooling conveyor.

Development of Intermediate Cooling Technology and Its Control for Two-Stand Plate Rolling

In a plate rolling production line, thermomechanically controlled processing is critical for plate quality. In this paper, a set of intermediate cooling equipment of a two-stand plate mill with super density nozzles, medium pressure, and small flow is developed. Based on a simplified dynamic model, a cooling control scheme with combined feedforward, feedback, and adaptive algorithms is put forward. The new controlled rolling process and the highly efficient control system improve the controlled rolling efficiency by an average of 17.66%. The proposed intermediate cooling system can also effectively inhibit the growth of austenite grain, improve the impact toughness and yield strength of Q345B steel plate, reduce the formation of secondary oxide scale on the plate surface and the chromatic aberration of the plate surface, and greatly improve the surface quality of the steel plate.

Experiments on Effects to Rock Bolt Pretension by Thread Rolling Accuracy

Pretension is a key factor affecting the performance of rock bolt. It is usually applied on the bolt by tightening the nut. The efficiency of the torque-to-pretension conversion is significantly influenced by the thread rolling accuracy. In this study, the influence of the thread rolling accuracy upon the pretension is investigated. Factors influencing the thread rolling efficiency, i.e., rock bolt material quality, rolling technic and equipments, are examined. To study the relationship between torque and pretension, a laboratory table was specially designed and a series of tests were carried out on the rock bolts with different thread accuracy. The result indicates that the higher the thread rolling accuracy, the higher the coefficient of torque-to-pretension conversion. And the coefficient can be improved by daubing lubrication oil on the thread. In China, the rock bolt thread encounters the issue of low rolling accuracy which results in coarse thread surface. As a result, the efficiency of the torque-to-pretension conversion is greatly reduced. In addition, the rock bolt is susceptible to break at the thread end. Essential approach to resolve these issues is to significantly improve the thread rolling accuracy by adopting advanced equipment.

Study on the Slab Rolling Force Based on Thermal-Mechanical Coupling Analysis

In order to increase rolling efficiency and production quality, adopted the finite element method, the rolling force analysis model of 3500mm rolling mill is established in this paper based on the thermal mechanical analysis theory, According to the rolling technology parameters in actual production, the rolling process of plate rolling is systematic studied, which thinks about the thermal stress caused by uneven temperature distribution. The law of technology parameters influencing rolling force is gained, which uses in the optimization of rolling process, improves production efficiency. it has important significance to reduce the energy consumption.

Effect of Different Compaction Methods on Bridge Pavement

In order to analyze the influence of different compaction methods on bridge deck vibration and bridge pavement compaction quality, the field test and laboratory test of oscillating compaction and vibrating compaction were carried out. The results demonstrated bridge deck vibration caused by the intrinsic exciting force of compactor contributed to vibrating compaction. On the pattern of oscillating compaction, the disturbance of bridge deck due to the exciting force of compactor is the main factor to induce bridge vibration. Furthermore, the vibration acceleration and amplitude in lateral, longitudinal and vertical direction, oscillating compaction are much smaller than that of vibrating compaction. Compared with vibrating compaction, the rolling efficiency of oscillating compaction is obviously higher and the final compaction degree also is much higher. Besides that, phenomenon of crushing the coarse aggregate is exists in the compaction construction, in which the effect of vibrating compaction on crushing the coarse aggregate is more obvious than oscillating compaction, and the range of crushing the coarse aggregate caused by vibratory compaction is larger than oscillating compaction.

Numerical Simulation on Rolling Process of Medium Plate

A 3-D thermal-mechanical model was built to simulate the hot rolling process of medium plate, with the aid of nonlinear commercial FE code MSC.SuperForm on a company's actual process parameters. The hot rolling process of single-pass which slab thickness is 180mm was simulated, and the influence of pass reduction on metal flow, stress-strain field, contact stress and rolling force were researched. The study revealed that pass reduction should be at least 20% by increase depress in pass in addition to rolling efficiency. As that, rolling efficiency be increased, roll contact stress be brought down, and its service life be prolonged. And metal plastic strain enhanced, metal flow increased, but its strain field non-uniformly distributed, metal flow and plastic deformation would be strengthen by increase pass reduction, and the lateral broadening in the head is bigger than that in the tail.

Numerical Simulation of Intermediate Cooling Temperature Field in Controlled Rolling

Air cooling may decrease rolling efficiency in controlled rolling for needing long holding time to obtain the correct rolling temperature because of small cooling rate. The intermediate cooling can increate the cooling rate, and improve rolling efficiency. Experiment was carried out to research the effect of intermediate cooling on rolling efficiency. The influence of different cooling mode on the temperature distribution and the temperature profile characteristics of different cooling strategy are analyzed with FEM. It shows that intermediate cooling can decrease the holding time effectively, and improve rolling efficiency; the temperature homogeneity in thickness direction can be improved by opening the header one after another and cooling the plate by oscillating cooling.

Critical but divergent roles for CD62L and CD44 in directing blood monocyte trafficking in vivo during inflammation

Using noninvasive in vivo imaging and experimental autoimmune uveoretinitis as a model, we show for the first time that the mechanisms controlling blood monocyte recirculation through peripheral and lymphoid tissues alter during inflammation. The recirculation of monocytes in mice with ocular inflammation but not controls was found to depend on the selectin CD62-ligand (CD62L) and on CD44. Not only was rolling efficiency ablated or markedly reduced in antibody-treated mice, but most of the labeled monocytes also disappeared from the circulation within seconds, anti-CD44–treated monocytes homing to the lymph nodes and anti–CD62L-treated monocytes homing to the spleen. Our data indicate that, although PSGL-1 has a partial role in the transmigration of monocytes into the inflamed retina, CD62L has a key role in regulating recruitment of monocytes to lymphoid tissue from the blood during inflammation and that CD44 is required to maintain CD62L+ inflammatory monocytes within the circulation during inflammation. This effect was systemic, because sequestered monocytes accumulated in mesenteric as well as draining cervical lymph nodes, and inflammation dependent, because depletion of circulating blood monocytes was much reduced or absent in normal mice and accumulations of adoptively transferred monocytes in the lymphoid tissues did not occur.