车用铝材分流模挤压过程温度场分析

Temperature field analysis on porthole die in extrusion process for automobile aluminum alloy

为了对汽车用铝材分流模挤压过程的温度场分布进行分析,根据刚塑性有限元基本原理,利用数值模拟技术对其进行评估。分析了挤压速度及摩擦因子对坯料截面不同方向(平行及垂直挤压方向)的温度场分布的影响,选取特征点对焊合区域的温度场分布进行研究。对数值模拟结果进行分析可知,当坯料初始温度为450℃,摩擦因子为0.3时,挤压速度由1增至3 mm·s-1时,温度最大值与最小值的差值在X方向上由7℃增至8℃、在Y方向上由9℃增加到10℃;通过对温度场的分析发现:具有良好散热条件的挤压筒壁附近的特征点温度出现一定程度的下降,而一些位于内部的特征点热损失很小,而且与坯料间具有不同程度的热交换,因此温度下降幅度小,在某些点上甚至出现了反常升高。

In order to analyze the temperature distribution of porthole die in extrusion process for automobile aluminum alloy, FEM was employed based on the principle of rigid plastic. The influences of extrusion speed and friction on temperature field in different directions （parallel and perpendicular to extrusion direction） were studied, and the feature points were selected in welding position to research its temperature distribution. The numerical results show that the difference between the maximum and the minimum temperature is from 7 to 8℃ in the X direction and from 9 to 10℃ in the Y direction respectively under an initial temperature of the billet 450 ℃, the friction factor 0. 3, extrusion speed from 1 to 3 mm · s^（-1）. Through the analysis on the temperature field, it is found that the temperature of the feature points near extrusion cylinder wall with good heat dissipation conditions declines to some extent. However, the temperature of some feature points in the internal declines a little, and there is different heat exchange between points and blank heat. Thus, the temperature declines slightly, and the abnormal rise happens in some points.