Effect Of Thin And Deep Drilling On Thermomechanical Behavior Of Mold Copper Plate For Continuous Casting

Mold is the core component of continuous casting machine.During the continuous casting process,the molten steel is cooled and solidified in the continuous casting mold to form the billet shell.The mold copper plate is thermally expanded,resulting in stress and strain under constraint.Drill holes with a diameter of 3-4 mm and a depth of 400 mm on the upper of the copper plate of the mold,and the central line of the drill holes is 17.5 mm away from the heated surface of the copper plate.Because the copper plate works in the high temperature environment,there is a large stress in the copper plate.The borehole structure changes the stress distribution of the copper plate,thus affecting the service life of the mold.In this paper,the influence of borehole on stress distribution and deformation of copper plate is analyzed by numerical calculation.Based on the geometric parameters of narrow copper plate in continuous casting mold of a steel plant,a three-dimensional model of copper plate is established in the Design modeler module of ANSYS Workbench.According to the data of cooling water flow rate and inlet and outlet temperature,the heat flux distribution function of copper plate heating surface is determined.The temperature distribution of copper plate is calculated in the Fluent module of ANSYS Workbench,and the calculated results are compared with the measured temperature of thermocouple.In ANSYS Workbench,the temperature distribution data of copper plate is introduced into mechanical module from Fluent module,and the stress distribution of copper plate is calculated by adding load and constraint conditions.The stress,strain and deformation distributions of copper plate without borehole and copper plate with 4 mm diameter borehole were compared,and the effect of borehole on thermal-stress behavior of copper sheet was analyzed.The stress,strain and deformation of copper plate with 3 mm,3.5 mm and 4 mm boreholes are calculated,and the influence of borehole diameter on the stress distribution of copper plate is analyzed by comparison.Calculate the stress and deformation of copper plate when the distance from borehole to hot surface of copper plate is 17.5 mm,15 mm and 12.5 mm respectively,and analyze the influence of the distance from borehole to hot surface of copper plate on the stress of copper plate.Finally,the stress and strain of copper plate in two boreholes are calculated,and the mutual influence of boreholes is analyzed when multiple boreholes are drilled.The main results are as follows:(1)The effect of drilling on the temperature of the copper plate is mainly along the thickness of the copper plate.Compared with the non-drilled copper plate,the temperature of the copper plate in the area between the drilled hole and the hot surface increases,and the temperature of the copper plate in the area between the drilled hole and the cold surface decreases.The effect of drilling on the temperature of the copper plate is small,and it is limited to the area near the drilling;(2)After the copper plate is heated,the copper plate is constrained by the wide-area copper plate,and the drilling and sink are squashed.The flattening of the front side of the borehole is more serious;the hot surface normal deformation of the projection area of the drilled copper plate with the borehole increases,but the increase is not obvious;(3)The effect of drilling on the equivalent stress of the copper plate is limited to a small area around the drilling;the front and back sides of the drilling are stress concentration areas,which have the same mechanism as the stress concentration at the root of the sink,but the range of the stress concentration area and the value of the stress is larger than the root of the sink;(4)Plastic deformation occurs at the stress concentration position of the borehole,and the maximum equivalent plastic strain is greater than the maximum elastic strain;(5)The larger the diameter of the borehole and the smaller the distance from the borehole to the hot surface of the copper plate,the larger the equivalent stress value at the location where the stress concentration on the borehole wall is;(6)When the copper plate has multiple holes,the normal deformation of the hot surface of the copper plate at the position between the two holes increases,and the equivalent stress on the hole wall surface decreases slightly.