Numerical Simulation Of Hot Rolling Forming Process Based On Casting Q235B Ring

With the widespread use of large rings and flanges in high-tech areas such as industrial manufacturing, aerospace and nuclear power, the demand for ring parts has been ever growing, and the requirements on properties and manufacturing technologies of ring parts have also become increasingly stringent. Therefore, energy conservation, cost reduction and improvement of quality and productivity have become inevitable trends in the development of ring production and equipment manufacturing industry. Precise short-flow metal ring casting-rolling compound forming technology is a breakthrough improvement to the traditional ring part production process, which has remarkable advantages such as short flow, energy and material conservation, high efficiency, low cost and environmental protection. This paper studies the effects of forming parameters on structure and properties of metal ring parts during their casting-rolling compound forming process from a macroscopic perspective, and microscopically studies the effects of forming parameters on hot forming recrystallization volume fraction, recrystallized grain size and average grain size by theoretical analysis, numerical simulation and comparative analysis using centrifugally and sand cast Q235 B steels.Through analog data analysis, the main research content of the thesis is as follows:(1) During the hot rolling forming, the higher the feed speed of mandrel, the more uniform the distribution of equivalent plastic strain, the more homogeneous the deformation of temperature field, and the greater the rolling force. When the mandrel feed speed is variable, equivalent strain and temperature field have decreased maximums, increased minimums and more uniform distributions, and the rolling force increases slowly during the initial stage. Comparative analysis of macroscopic deformation between centrifugally and sand cast slabs shows that under the same rolling parameters, distributions of equivalent plastic strain and temperature field are more uniform for the centrifugally cast slabs than the sand cast ones, but centrifugally cast slabs require higher rolling force.(2) As the mandrel feed speed increases, volume fraction of dynamic recrystallization decreases and becomes more uniform, recrystallized grain size becomes slightly smaller but increasingly uniformly distributed, and distribution of average grain size also becomes increasingly uniform. When the feed speed of mandrel is variable, distributions of dynamic recrystallization volume fraction, recrystallized grain size and average grain size are more uniform compared with the constant speed conditions.(3) It can be concluded from the analytal results that on the premise of meeting the operating conditions of ring rolling equipment, the use of centrifugally cast Q235 B slabs, mandrel feed speed of(initial acceleration at a rate of 2?/1.0 smma until reaching V=1.6mm/s, followed by 34 s of feeding at a constant speed, and a final deceleration at a rate of 2??/1.0 smma until zero), and initial temperature of 1150 ℃can allow the ring rolling deformation to be more uniform, grains to be more refined, and rolling quality and production efficiency to reach the desired levels.