Use of device for incremental forming of round bars HDQT-R 30-12 for heat and thermo-mechanical treatment of steels
Today, industrial rolling mills use conventional longitudinal technology to reduce the diameter of round bars. Machines used in these rolling mills are mostly single-purpose and are not equipped by modules for the further heat treatment of the rolled steel after forming. The experimental device for incremental forming of round bars HDQT-R 30-12 is designed to reduce the diameter of bars by the technology of three-roll skew rolling, which is suitable for forming a wide range of steels – from carbon to noble tool steels as well as for materials which is difficult to form. The high modularity of the entire device makes it possible to incorporate the heat treatment step by means of various modules directly behind the forming. Due to the arrangement of the modules, after rolling the rolled products can be quenched to the desired temperature by water spray or in a water bath, or inserted into a furnace for reheating or holding at temperature. Due to this arrangement, the device is capable of producing cylindrical, conical and other rotationally symmetrical shapes with a straight longitudinal axis and with different heat treatments. Temperatures, forces and moments in the rolling mill and other data are collected during the passage of the workpiece through the whole machine. From these data it is possible to determine the exact sequence of the thermo-mechanical treatment and, if necessary, to propose a modification of the processing to achieve better mechanical properties of the material. The paper deals with the possibilities of thermo-mechanical processing of conventional 42CrMo4 steel and 42SiCr experimental steel using various methods of heat treatment after hot rolling.
Keywords: forming, heat treatment, AHSS, three-roll skew rolling