Based on mathematical modeling of the thermal and stress states of tuyere components, this study developed a protective design for the thermal insulation insert within the blast channel against natural gas combustion. The proposed solution involves shielding the insert with a perforated, truncated cone made of heat-resistant steel that is fixed to the tuyere flange inside the blast channel. The cone geometric parameters were determined to reduce the insert temperature and thermal stresses and minimize heat loss to the cooling water. These improvements were made while maintaining the same thermophysical parameters of the gas-air mixture as in the previous design, which used a heat-resistant ring to protect the flange-side face of the insert.
The influence of normal contact stress on the durability of rolls in the finishing stand of a hot-rolling mill is considered. In the given rolling conditions, contact stress of 1100–1230 MPa appears in the finishing stand. Changes in the rolling conditions and the tension between the stands is suggested so as to reduce the contact stress to 802 MPa and extend roll life.
The mechanism of combined control of the profile and flatness of cold-rolled strips using CVC (Continuously Variable Crown) and WRB (Work Roll Bending) systems has been investigated. It was established that the combination of these systems provides formation of various types of strip profile through controlled deformation across the width. An example of joint regulation by the CVC and WRB systems during rolling of strip on an industrial four-stand 2100 mill is presented, with control of the distribution of elongation (strain) across the width. It is shown that, based on measurements from the flatness-measuring rollers in the first stand, the CVC and WRB systems can operate jointly to equalize elongation across the width; in the intermediate stands—to stabilize stresses; and in the last stand of the mill—to finalize flatness formation. The obtained results provide a basis for the development of empirical research methods and mathematical descriptions of cold-rolled strip flatness, enabling a transition to predictive digital flatness models that improve the efficiency of rolling process control and subsequent technological operations.
Based on the results of computer simulation of the cold symmetrical and asymmetrical longitudinal rolling of strips on the 1700 mill of PAO Severstal, the changes in the length of the actual and geometric zones of deformation were assessed for each of the stands and for each rolling scheme. The influence of rolling speed, reduction, and the asymmetry of roll diameters on the position and angle of inclination of the neutral line relative to the vertical was demonstrated. It was established that the position of the neutral line can be evaluated based on the analysis of the changes in the mean stress values along the length of the geometric zone of deformation.
The method of injecting natural gas into the air passage of a tuyere with a heat-insulation lining influences the distribution and magnitude of thermal stresses within the lining. A computational analysis of the thermal stress state of tuyere components with natural gas injected through the flange holes revealed that the thermal stresses are maximum when the lining end is protected by a flange with inner diameter reduced on the lining side, whereas they are minimum when the lining end is protected by a ring.
