镁合金温控轧辊的温度场研究

Study on temperature field of temperature controlled roll for magnesium alloy

摘要:

镁合金板材轧制对工作辊的温度有特殊控制要求,本文采用导热油循环流动传热的方式对轧辊进行温度控制,基于有限差分法建立了轧辊、导热油传热过程的差分模型,利用FLUENT建立了导热油加热轧辊的流固耦合传热模型,并辅以相应的实验验证,给出了其传热过程中轧辊的温升曲线、辊身表面及横截面温度分布。结果表明：在不同的加热条件下,其表面温度分布呈现操作侧温度高、驱动侧温度低的特点,两端的温差范围在5-12℃,且流体温度与速度对其影响较小；轧辊内壁与外壁的最大温差6℃,可近似认为径向温度分布均匀；随着加热时间的增加,轧辊表面温度均呈速率减小的趋势上升,流体温度升高及速度增大时,轧辊温升变快；轧辊停止加热后,其表面温度不会立即下降且持续增长一段时间,这段时间约为5-8分钟,流体的温度和速度对延长的时间影响较小；轧辊表面平均温度的计算值与实验值吻合较好,最大相对误差为8.3%,表明该模型可正确预测轧辊表面的平均温度,作为镁合金板材轧制模型的一部分,利于轧制过程中轧辊的“等温”控制,实现“镁合金板材的等温轧制”控制。

Abstract:

Magnesium alloy sheet rolling has special control requirements for the temperature of the work rolls, in this paper, the temperature control of the rolls was controlled by fluid-solid coupled heat transfer. Based on the finite difference method, a differential model for the heat transfer process of roll and thermal oil was established, which was complemented by the corresponding experimental verification. A fluid-solid coupling heat transfer model was also established by FLUENT, giving the roll temperature rise curve, the surface temperature and the cross-section temperature distribution during the heat transfer process. The results showed that the temperature near the roll operating side is the highest and the temperature decreases gradually from the operating side to the driving side, and the temperature difference range between the operating side and the driving side is 5-12°C and is almost unaffected by the fluid temperature and speed. The maximum temperature difference between the inner wall and the outer wall of the roll is 6°C, which can be considered that the radial temperature distribution is even. Under different fluid temperature and velocities, the temperature of the roll rises with trend of decreasing rate, and when the fluid temperature rises and the velocity increases, the temperature rise of the roll becomes faster. After the roll stops heating, its surface temperature does not begin to drop immediately and continue for a period of time, which was about 5-8 minutes, and the temperature and speed of the fluid have less effect on the extended time. The calculated values of the average roll surface temperature agree well with the experimental values, the maximum relative error is 8.3%, which verifies the correctness and effectiveness of the finite differential model, and as part of the magnesium alloy plate rolling model, it is conducive to the isothermal control of the roller in the rolling process and realizes isothermal rolling control of magnesium alloy plate.