风电球墨铸铁件铸造工艺及组织数值模拟的优化

发布时间：2018-01-08 01:10

  本文关键词：风电球墨铸铁件铸造工艺及组织数值模拟的优化　出处：《山东大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 数值模拟分析 铸造工艺 石墨球 珠光体

【摘要】：由于化石能源数量有限,环保意识逐渐增强,风能作为一种取之不尽的清洁能源越来越受到人们的重视。风力发电设备,例如风电轮毂、底座、转轴等,体积都比较庞大,重量一般都在10t以上,在铸造生产过程中出现废品将会造成巨大的损失;风力发电设备工作环境也比较恶劣,一般都运行在室外寒冷的环境中,因此对其各方面的力学性能有较高的要求。对此,我国国家标准对该类球墨铸铁件的组织及力学性能都进行了严格的要求。在实际生产过程中,风电球墨铸铁件经常会产生一些缺陷,铸造工艺对其有着重要的影响,因此铸造工艺的设计是否合理就显得尤为重要。本文探究了铸造模拟仿真软件在该类铸件中的应用,确定出了模拟各阶段的参数设置,为铸造工艺设计的合理性提供了重要的参考依据;并且利用该软件对风电轮z@件当前的铸造工艺进行了模拟仿真,发现在铸件的顶部位置存有缩孔、缩松缺陷,这与实际生产过程中经常出现缺陷的位置比较吻合;经过分析,铸件顶部产生缺陷的主要原因为冒口颈的过早封死造成铁液补缩不足及冷铁排放的不合理所造成的;通过对冷铁的重新布置及冒口形式的改变可以完全消除铸件顶部产生的缺陷。风电设备器材属于典型的厚大断面球墨铸铁件,为了研究不同的壁厚对其组织性能的影响,在风电轮毂件上设计了附铸楔形试块。实验结果表明,在当前工艺条件下,整个附铸楔形试块的基体组织全部为铁素体基体;随壁厚的增大,组织中的石墨球的密度逐渐降低,石墨球尺寸逐渐变大,石墨球圆整度逐渐变差;壁厚达到一定程度(高温阶段的冷却速度为5.5℃/min,共晶反应平台时间51.7min),组织中会出现碎块状石墨,碎块状石墨的出现会极大地降低铸件的性能;在厚大断面处,由于冷却速度比较慢,有些Si元素会在石墨球周围富集,当石墨球周围Si元素的含量大于2.25%时,石墨球发生破裂的几率就会大大增加,出现碎块状等畸变石墨球。为了研究风电球墨铸铁件组织中珠光体与冷却速度的关系,利用DSC热分析仪对若干个试样分别以恒定的冷却速度对其进行冷却处理。结果表明,随着冷却速度的增大,珠光体的含量近似呈线性增加,根据此关系可以推出当冷却速度大于4.1℃/min时,组织中珠光体的量将大于10%;当冷却速度小于1.4℃/min时,组织中将全部为铁素体基体。并且以该实验数据为基础,建立了珠光体分解速率模型,经过实验验证,所建立的模型具有很高的准确性,这为风电球墨铸铁件生产过程中组织的判断提供重要的参考作用。
[Abstract]:Due to the limited amount of fossil energy and the increasing awareness of environmental protection wind energy as an inexhaustible clean energy has been paid more and more attention. Wind power generation equipment such as wind wheel hub base rotating shaft and so on. The volume is relatively large, the weight is generally more than 10 tons, in the foundry production process, the waste will cause huge losses; Wind power equipment working environment is also relatively bad, generally operating in the cold outdoor environment, so the mechanical properties of its various aspects of higher requirements. The structure and mechanical properties of this kind of ductile iron are strictly required by the national standard of our country. In the actual production process, some defects often occur in the wind power ductile iron. Casting technology has an important impact on it, so whether the casting process design is reasonable or not is particularly important. This paper explores the application of casting simulation software in this kind of castings. The parameter setting of each stage of simulation is determined, which provides an important reference for the rationality of casting process design. The software is used to simulate the current casting process of the wind turbine z. it is found that there are shrinkage holes and shrinkage defects at the top of the castings. This is consistent with the position where defects often occur in the actual production process. After analysis, the main reasons for the defects at the top of the castings are caused by the premature sealing of the riser neck and the unreasonable discharge of cold iron. The defects in the top of the castings can be completely eliminated by the rearrangement of the cold iron and the change of the riser form. The wind power equipment and equipment belong to the typical thick and large section ductile iron castings. In order to study the effect of different wall thickness on the microstructure and properties of the wheel, the tapered specimen was designed on the wind wheel hub. The experimental results show that under the current technological conditions. The matrix structure of the attached wedge-shaped specimen is all ferrite matrix. With the increase of wall thickness, the density of graphite nodule decreases gradually, the size of graphite sphere becomes larger, and the roundness of graphite ductile becomes worse. The wall thickness reaches a certain degree (the cooling rate at high temperature is 5.5 鈩，

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