文章信息/Info

Title:

Real-time automatic control technology of rapid isothermal extrusion of aluminum alloy profile

作者:

李靜媛; 項勝前; 周春榮; 宋勇; 胡水平; 顧偉; 謝建新

(1.北京科技大學,北京 海淀 100083;2.廣東豪美鋁業股份有限公司;廣州 清遠 511540)

Author(s):

Li Jingyuan1 Xiang Shengqian2 Zhou Chunrong2 Song Yong1 Hu Shuiping1 Gu Wei1 Xie Jianxin1

(1. University of Science and Technology Beijing, Beijing 100083, China) (2. Haomei Aluminium Co. Ltd. Guangdong 511540, China)

關鍵詞:

等溫擠壓; 梯度水冷; 在線冷卻; 預測模糊控制

DOI:

10.7502/j.issn.1674-3962.2013.05.07

摘要:

介紹了國內外等溫擠壓技術的發展現狀，闡述了等溫擠壓的技術原理，開發了一種新的等溫快速擠壓三重實時自動控制系統，包括坯料梯度水冷系統、模具液氮在線冷卻系統和擠壓速度-出口溫度閉環控制系統。研究發現，采用有限差分離散求解坯料導熱微分方程，設定軸向溫度梯度，控制在線梯度水冷裝置施加冷卻，可抵消擠壓過程中部分溫升；通過出口溫度數據回歸獲得溫升模型，控制液氮通入量，可維持模具工作帶溫度恒定，延長模具壽命，并提高型材表面質量；根據采集的模孔出口型材溫度，依據預測模糊控制模型，進行閉環控制以調節擠壓速度，可提高型材溫度控制精度。通過三重控制系統聯動，最終實現模孔出口處型材溫度恒定。此系統的應用有利于提高型材擠壓速度，可保證型材沿長度方向上尺寸精度與組織性能穩定。對于擠壓速度較快的情形，可控制模孔出口處型材溫度波動在±10℃以內，對于擠壓速度較慢的工業型材，可控制模孔出口處型材溫度精度在±5℃之內；對于擠壓性能好的合金，擠壓速度最高可提升30%以上。

Abstract:

This paper introduces the research and progress of isothermal extrusion in the world, clarifies the control principle and method of this technology, and develops a new real-time automatic control system of rapid isothermal extrusion composed by the gradient water-cooling system of billets, the liquid nitrogen cooling system of mould and the closed loop control system of extrusion speed and outlet temperature. Studies have found that it can inhibit the temperature elevating of billet during extrusion through the gradient water-cooling device with the pre-produced axial temperature gradient of billet, which is controlled by the finite difference method and discretized heat conduction equation. Exit temperature regression model are adopted to control liquid nitrogen intake to cool the extrusion mold, which stabilizes the mold operating temperature, prolongs the mould life and improves the quality of profile surface. The temperature of the profile can be adjusted accurately by the predictive fuzzy model though adjusting extrusion speed using closed loop method. Consequently, the temperature of the profile at the extrusion exit would maintain constant due to the triple linkage control system. This system is also beneficial to improve the speed of extrusion, and ensure the accuracy of dimension and stability of microstructures and properties along the length direction of the profiles. For rapid extrusion, the fluctuations of profiles temperature at the exit can be limited within ± 10℃, and for slow extrusion speed producing industrial profiles, the temperature accuracy of the exit profile can be contained within ±5℃, also the extrusion speed can increase by more than 30% for the extrusion alloy with good performance