Stress state of billet – mandrel system during production of hollow steel billet in a unit of continuous casting and deformation. Part 1

The substantiation of the relevance of obtaining continuous cast steel pipe hollow billet is given from the position of improving the quality of pipes made of carbon and alloy steels is given. The article presents an assessment of the quality of the inner surface of pipes made of solid steel pipe billet. A new technology is proposed for the production of hollow steel pipe billets on a resource-saving unit of combined continuous casting and deformation. The photo of the continuous casting and deformation section of JSC Ural Pipe Plant is given, where a pilot unit of combined continuous casting and deformation is installed. The paper presents the results of a theoretical study of stress-strain state of the mandrel and sections of a pipe billet when it is compressed by the strikers of the unit of combined continuous casting and deformation. The authors discuss the general model of the mold – striker system. The initial data on calculation, dimensions of the hollow pipe billet and a description of the calibration of strikers for compression of a hollow steel billet are given. The temperature field of a hollow billet was determined. To simulate the stress-strain state of the metal in the roll pass and the mandrel, four contact pairs were considered. Calculations were made by the finite element method. The dimensions of the final element in the roll pass of hollow billet were determined. The authors established the values and patterns of changes in metal displacements and axial stresses in the roll pass during the production of hollow steel billets in the unit of combined continuous casting and deformation (strikers are made along a constant radius). The stress state of metal in the roll pass was assessed from the standpoint of improving the quality of hollow steel billets.