【作者】 段亚利；

【导师】 张治民；

【作者基本信息】 中北大学 ， 材料加工工程， 2007， 硕士

【摘要】 本文以AZ31镁合金挤压薄壁管材为研究对象,讨论了模具结构、工艺参数对挤压过程的影响,并分析了挤压比对试制管材力学性能和显微组织的影响。通过对管材不同挤压成形方法的分析,结合镁合金的热变形特点,确定选用了等温正挤压全润滑的成形方法。应用MSC/Superform有限元模拟软件,对镁合金薄壁管材的挤压成形过程进行模拟。讨论了凹模锥角、挤压温度、挤压速度、摩擦条件及挤压比对变形中等效应力、等效应变和挤压力的影响,确定出了合理的变形工艺参数和模具结构。模拟结果显示,凹模最佳锥角为45°、挤压温度为380℃、挤压速度为0.1 mm/s和摩擦系数为0.1的条件下具有较小挤压力、合理的等效应变、等效应力分布,有利于该零件成形。在对数值模拟结果进行分析的基础上,制订了镁合金薄壁管材的挤压成形工艺,并进行了模具设计,在模具结构设计方面着重考虑了壁厚差的控制问题。在以上研究工作的基础上,对AZ31镁合金挤压薄壁管材进行了试制,获得了尺寸精度高、粗糙度小、壁厚差小的管材;并对组织和性能进行了测试分析,由结果可知,管材组织细密,抗拉强度和延伸率明显提高,有强的承压能力。本文验证了数值模拟和物理实验结果的正确性以及该工艺成形镁合金薄壁管材的可行性。更多还原

【Abstract】 The thin-wall extruded tube of magnesium alloy AZ31 is selected as research object in this paper. The influence of the structure of the mold and the process parameters on the extrusion course is discussed and influence of extrusion ratio on the mechanical properties of tube and microstructure is also analyzed.According to analyses the different extrusion forming methods, the forming method of isothermal forward extrusion full lubrication is defined with hot deformation behaviors of magnesium alloy.The extrusion course of thin-wall extruded tube of magnesium alloy is simulated by using the numerical simulation of finite element method (FEM). The cone angle, extrusion temperature, extruding velocity, friction conditions and extrusion ratio are discussed which impact equivalent stress, equivalent strain and extrusion force and determining the reasonable process parameters and the structure of the mold. The simulation results show that the relatively small extrusion force, reasonable distribution of equivalent strain and equivalent stress can be get when the cone angle 45°, extrusion temperature 380℃, extruding velocity 0.1 mm/s and friction coefficient 0.1, which benefit forming.The forming process of thin-wall extruded tube of magnesium alloy is established based on analyzing the results of numerical simulation and designing mould. Emphasis is put on the control of wall thickness difference in designing the structure of the mold.Based on above research, the tube with precise size, low roughness and little wall thickness difference is received during the trial - manufacture of the thin-wall extruded tube of magnesium alloy AZ31. Testing analyzing properties and microstructure, the result show that the tube has impact microstructure and strong bearing capability and the tensile strength and elongation improve obviously.The correctness of numerical simulation and physics experiment and feasibility of the thin-wall extruded tube of magnesium alloy forming by this process are verified.更多还原