【作者】 王芳；

【导师】 方敏；

【作者基本信息】 中北大学 ， 材料加工工程， 2012， 硕士

【摘要】 本课题涉及的零件为某航天机构上所使用，壁厚较薄，最薄处仅为1mm，而且对零件轻量化以及性能的要求比较高。如何能在满足性能要求的前提下，用质量更轻的镁合金代替钛合金或铝合金成形工件，这对于航天机构轻量化方面具有重要的意义。采用数值模拟结合实验试制的研究方法，分析零件的结构特征以及镁合金材料的性能，成形方式选择为等温挤压成形技术。考虑到生产效率以及对零件性能的要求比较高，拟定了两套成形工艺方案，即一次直接成形方案与增加镦粗预成形方案。对挤压件的壁厚、关键部位圆角半径等成形工艺参数进行模拟分析，得出挤压件在壁厚6mm，内凸缘圆角半径15mm，成形温度380℃，成形速度5mm/s左右，摩擦系数控制在0.2左右时成形性比较好。在此基础上设计制造出模具进行实验试制，结果表明：方案一在反挤压阶段出现裂口缺陷，分析原因为对铸坯的挤压变形量太大超过了其断裂阈值；方案二成形件精度不高，分析原因为凸模模具带有凹槽，润滑剂难以均匀涂抹。进而对方案二进行模拟优化，采用体积预分流方式，预成形时在难以成形的部位预留出一定的坯料，最终在现有设备条件下试制成功。结果表明：采用等温挤压工艺逐步成形工件，可以消除裂口缺陷；采用体积预分流的方式可以有效控制复杂部位金属的流动。优化工艺后试制的挤压件外形尺寸精度高，金属流动达到了预期效果，解决了成形定位的问题，生产效率高，挤压件的力学性能优异，满足其作为航天零件的要求，为批量化生产奠定了基础。更多还原

【Abstract】 This shell part is used on aviation equipment, which wall thickness is very small.Meanwhile it require lightweight and high performance. Under the premise of performancerequirements，we use magnesium alloy instead of titanium or aluminium alloy. This technologywill be very important for aviation equipment lightweight.By analyzing the structure of the part and the properties of Magnesium Alloy, Combinenumerical simulation with experimental trial, we using isothermal forging as the final process.Consider production efficiency and performance requirements, we draft two sets of formingprocess，one is direct forming，the other increasing the performing. Through the simulation ofdifferent wall thickness, fillet radius and process parameters, we find that the part can get bestperformance under the conditions of that the wall thickness is 6mm,fillet radius is 15mm,thetemperature is 380℃,the forming speed is about 5mm/s, and friction coefficient is 0.2.On thisbasis, design of mold and detection it. The results show: extrusion deformation of the slab isso large that exceed the fracture threshold, so the gap defects in the anti-extrusion stage offirst program; Punch mold with grooves, the lubricant is difficult to spread evenly, so formingpieces of precision is not high of the latter one. To optimize the second program , we have thevolume of pre-diversion way, and set aside some of the billets in difficult shape parts of theperform, Ultimately, a successful trial test in the conditions of existing equipment.The results shows that: It can eliminate the presence of cleft defects to form theworkpiece isothermal by extrusion process gradually. It can effectively control the flow ofcomplex parts of the metal using volume pre-shunt way. After the optimization trial processthe dimensions is precision and the metal flow can achieve the desired results. It not onlysolves the problem of forming positioning with high production efficiency but also the excellent mechanical properties can meet their requirements as aerospace parts for massproduction loading the foundation.更多还原