【作者】 王其军；

【导师】 刘化民；

【作者基本信息】 吉林大学 ， 材料加工工程， 2008， 硕士

【摘要】 镁合金在低于200℃以下的温度范围内塑性较差,在高于400℃时,由于镁合金极易氧化,不适合塑性加工。镁合金的锻造温度范围窄,而其导热系数大约是钢的2倍。锻造时如果模具温度低,则坯料降温快,塑性降低,变形抗力增大,变形率低,变形过程中坯料易形成裂纹,所以镁合金一般采用等温锻造。本课题介绍镁合金锻造原理以及数值模拟在锻造成形中的应用;介绍刚塑性有限元理论及锻造数值模拟中的关键技术,在三维造型软件UG的CAD平台下进行自行车曲柄锻件模具和坯料的CAD参数化实体三维造型,并建立AZ31镁合金材料模型,最终构建自行车镁合金曲柄成形的有限元模型;根据刚塑性有限元法基本原理,利用数值模拟软件DEFORM-3D,对镁合金曲柄锻件的成形过程进行模拟仿真,并优化其工艺参数;根据模拟结果,分析锻件的金属塑性成形过程,得出影响成形的主要影响因素及影响规律,研究成形参数对成形过程的影响,金属流动规律等;优化其工艺参数及模具型腔,获得能够锻出合格锻件的工艺及模具参数;最后对自行车曲柄零件进行工艺分析及模具设计,根据数值模拟结果进行锻造参数的计算,模具图的绘制等。更多还原

【Abstract】 In the process when the bicycle enterprise are pursuing product lightweight magnesium alloy gradually receives the manufacturer and consumer’s favor because of its outstanding specific tenacity and compared to the rigidity. Furthermore the magnesium alloy that applied on the bicycle also has other unique outstanding performance:①Prominent character that hasn’t the memory of wearily;②Good dynamics performance;③Better carrying capacity compareed to the plastic parts;④Better antivibration characteristic compared to the metal parts such as steel and aluminum;⑥Easy to be recycled.Magnesium is the lightest commercial construction metals being used in practice at present. At the same time,magnesium alloys have lower density, the highest strength to weigh ratio, good thermal conductivity , electrical conductivity, damping capacity, and good electromagnetic interference shielding property, the property of being easy to manufacture and recyclable. The magnesium alloy has a narrow forging temperature rang , but it has a high thermal conductivity which is about twice more than steel. Therefore we generally choose isothermal forging method for magnesium alloy.In this paper,using the finite element numerical simulation soft DEFORM-3D, simulate the forming processes of crank forge piece, According the numerical simulation rusults, bring foreword influence crank shape’s processes parameters, analysis and study some mostly influence factor of forging part shaping rule, optimize and gain possibility forge up to qualified forging part’s processes and die parameters. The result plays guidance to the production of crank forge piece. The actual content is as follows:(1) Introduced the magnesium alloy forging and its domestic and foreign present research situation, gave some elaborate introductions on the isothermal forging and precision forging craft characters of the magnesium alloy. (2) Introduced the rigid-plastic finite element method and critical technical in the numerical simulation of forging forming. through the UG software, designed the forging and die’s 3D model, established AZ31 magnesium alloy material model. provided the finite element model for the following simulation and analysis.(3) Using the numerical simulation software DEFORM-3D, Carried on the numerical simulation of the forming process, in-depth and meticulous analyzed the flow pattern of the metal in the forming process, obtained the distributive rule of the corresponding speed, stress, strain and curve of load-distance, understood the general rule of the metal in the forming process of the crank. Established the different models and has carried on the numerical simulations using the main formed parameter. Inspected the influence that the formed parameters such as working temperature, working speed and lubrication to the distortion.(4) Calculated die forging process technological parameter of the bicycle crank, determined the technical process of the crank and the specification of the semifinished materials and designed the model designed the heat device and hydraulic jacking equipment of the isothermal forging.更多还原