【作者】 王琼；

【导师】 杜之明；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 铝及其合金是有色金属中用途较广的轻金属之一,具有高的比强度、比刚度、塑性好、导电与导热性好、且具有较好耐蚀性,是制造航天和航空装备的理想材料。对锻造无法加工成形的复杂制件,若采用机加工的方法则浪费材料,且加工周期长,成本高;若用铸造的方法,则制件性能得不到保证。半固态金属加工是一种新发展的一次近净成形复杂形状制件技术,其制件力学性能接近锻件,为复杂制件成形开辟一条新路。本文以6061铝合金为研究对象,通过应变诱导法(SIMA法)制造半固态坯料,研究其半固态压缩状态下的力学特性,然后以保险阀壳体件为试验对象,对其各种方式的触变成形过程进行数值模拟,为该零件的触变成形研究提供参考和依据。在前期工作中,应用镦粗法制备6061铝合金半固态坯料,并通过半固态压缩实验建立该材料真应力-真应变模型;第二阶段应用三维造型软件对成形薄壁壳体件所需的模具进行了参数化实体造型,然后在Deform3D平台上对该零件的各种成形方法和过程进行了数值模拟,研究了模具结构和成形方法对成型结果的影响;第三阶段通过半固态模锻实验验证数值模拟的结果,对保险阀壳体件的半固态成形工艺进行初步的探索和研究。通过显微组织观察证明利用镦粗法可以一定程度细化晶粒;通过半固态等温压缩实验研究了6061铝合金在半固态下的压缩力学行为,证明挤压后冷变形态6061铝合金可以在较小的力下实现较大的变形,且均具有温度和应变速率的敏感性;通过不同成形方法的数值模拟实验,证明目前的模具结构下采用两侧推挤触变模锻法成形带侧凹的保险阀壳体件会造成夹料的现象,从而无法完全充型;如果用顶部正挤压法则可以实现液态模锻成形,但是无法实现半固态触变成形;如果改变分型面的位置,采用正挤压法则可以成形不带侧凹的保险阀壳体零件;如果将零件的颈部去掉,使用改变分型面后的正挤压法可以成形。通过实际的成形实验验证了数值模拟的结果,并与数值模拟的结果很吻合。本试验提出最终解决问题的方法,改变模具结构,使用正挤压法成型出去掉颈部的壳体件,再使用机加工的方式去掉颈部多余的材料。更多还原

【Abstract】 Aluminium alloy is a kind of light colored metal which is widely used, it has high specific strength and high specific rigidity; it also has good electric conductivity and good conductivity for heat and its strain resistance is good too, so it is a ideal material for aviation equipment. In general, machining is used to fabricate complicated parts that can not be made by forging process. A quantity of raw material is thus wasted in a very long process cycle, resulting in high manufacturing cost. Semi-solid metal working, a newly developed process for near-net shaping complicated parts, with mechanical properties approach to those of forging parts, will establish a new method for making such complicated parts. Taking 6061 aluminium alloy as object, made it’s billet by SIMA ( Strain Induced-Melt Activation ) method. The mechanical character and the simulation of it’s shapping process are then studied which could be a reference of the thixo-mold experiment.In the first period, the semi-solid billet was preparated by SIMA method, and then it’s equivalent stress and equivalent strain model was set up by compression tests. During the second period, mould of the shell shapped part in three dimension was set up using Pro-Engineer(Proe)software, and then the shapping process of the part was simulated by using the Deform3D software, so the effect of the mould fabric and the forging method to shapping the part was then gained. During the last period, the forging experiments were done which proved the results of the simulation, and the primary research on the forging process of the valve was finished.By observing the microstructure of the billet which was cold upsetted we found that cold upsetting method could fine the grain size on some degree. Through a large number of compression tests in 6061 aluminium’s semi-solid state, mechanical behaviors during semi-solid deformation process for the 6061 aluminium alloy were investigated, and found that a larger deformation was realized under less force for cold upsetting state billet and this kind of billet is sensitive to temperature and strain rate. Through a lot of simulation tests, the extruding from the two side method can’t forming the valve for the material extruded from the top method, the valve can be formed in liquid state but can’t be formed in semi-solid state. If change the parting plan, then the valve without side hollows can be formed by direct extrusion method, if get rid of the cervix, then it can be formed by direct extrusion method with the parting plane in the biggest diameter position.The last solution is: form the valve without cervix by direct extrusion method and then machine the unwanted material.更多还原