QT450-10桥壳铸造工艺数值模拟及其优化设计

发布时间：2018-09-13 12:29

【摘要】：桥壳是安装差速器、减速器和轮毂的基础件，在使用过程中，要承受较大的冲击载荷及摩擦磨损，必须具备良好的综合力学性能。本文的主要目的是对树脂砂型铸造球墨铸铁叉车驱动桥壳的铸造工艺进行设计和研究，并运用华铸CAE模拟软件对铸件的充型和凝固过程进行模拟，分析铸件在铸造过程中产生缺陷的原因，以优化铸造工艺，，消除铸造缺陷，获得优质的桥壳铸件。首先，根据QT450-10桥壳的材质要求和铸件的结构特点，提出桥壳铸造工艺的初始方案，利用模拟软件对工艺方案下铸件的充型和凝固过程进行模拟，分析桥壳铸件流动场、温度场的变化规律。模拟结果显示桥壳铸件中在冒口补缩部位和半轴部位出现了较多的缩松缺陷，缩松总体积为79.33cc，在下部端盖厚壁部位和顶部凸台部位产生缩孔缺陷，缩孔总体积为0.07cm3。从改变冒口高度和冒口直径两个方面对初步的工艺方案进行了改进，并对改进工艺下桥壳的凝固过程进行模拟，结果表明：冒口高度、冒口直径的增加并不能有效的增加冒口的补缩效果，铸件上的缩孔、缩松缺陷未能得到彻底消除。进而采用改变冒口颈长度和冒口颈截面尺寸方法进行工艺改进，由模拟结果发现：通过减小冒口颈长度、增加冒口颈截面尺寸，使得冒口颈的凝固时间延长，扩大了补缩通道，提高了冒口的补缩效果，基本上消除了冒口补缩部位的缩松缺陷，铸件上的缩松总体积减为45.00cc，缩松缺陷主要出现在铸件半轴部位。通过在铸件半轴部位增加补贴，形成从半轴到冒口逐渐增加的温度梯度，增大了冒口的有效补缩距离，半轴部位的缩松缺陷基本上被消除，铸件缩松总体积减为10.43cc。进一步通过设置冷铁及出气孔的方法消除了铸件中的缩孔和气孔缺陷。桥壳铸件下部端盖厚壁处在凝固过程中易出现缩孔缺陷，通过在端盖厚壁处放置冷铁，提高了厚壁处的凝固速度，避免厚壁处凝固时出现孤立液相区，进而消除了端盖部位的缩孔缺陷。针对桥壳铸件顶部在凝固过程中出现缩孔、气孔的问题，采用在铸件顶部安放出气孔、出气片的方法，有效的消除了桥壳铸件顶部的缩孔、气孔缺陷。本文通过模拟分析和工艺改进得到了桥壳最优化的铸造工艺方案，桥壳铸件中的缩孔、气孔缺陷全部被消除，缩松总体积减为6.74cc。
[Abstract]:The axle housing is the foundation for the installation of differential, reducer and hub. In order to bear large impact load and friction and wear, it is necessary to have good comprehensive mechanical properties. The main purpose of this paper is to design and study the casting technology of the drive axle shell of the ductile iron forklift truck in resin sand casting, and to simulate the filling and solidification process of the casting by using the CAE software. In order to optimize the casting process and eliminate the casting defects, the causes of defects in casting are analyzed, and high quality castings of bridge shell are obtained. Firstly, according to the material requirements of QT450-10 bridge shell and the structural characteristics of casting, the initial scheme of bridge shell casting process is put forward. The filling and solidification process of the casting under the process plan is simulated by simulation software, and the flow field of bridge shell casting is analyzed. The variation of temperature field. The simulation results show that there are many shrinkage defects in the riser feeding part and half shaft part, the total volume of shrinkage is 79.33 cc. the shrinkage defect is produced in the thick wall part of the lower end cover and the top convex part, and the total volume of the shrinkage hole is 0.07 cm ~ 3. The preliminary technological scheme was improved from two aspects: riser height and riser diameter, and the solidification process of the bridge shell was simulated under the improved technology. The results show that the riser height, The increase of riser diameter can not effectively increase the shrinkage effect of riser, and the shrinkage hole and shrinkage defect on casting can not be completely eliminated. By changing the length of riser neck and the size of riser neck section, the simulation results show that by reducing the length of riser neck and increasing the size of riser neck section, the solidification time of riser neck is prolonged and the feeding channel is enlarged. The shrinkage effect of the riser is improved and the shrinkage defect of the feeding part of the riser is basically eliminated. The total volume of shrinkage on the casting is reduced to 45.00 cc.The shrinkage defect mainly occurs in the half shaft of the casting. By increasing the subsidy on the half shaft of the casting, the temperature gradient from the half shaft to the riser is gradually increased, and the effective feeding distance of the riser is increased. The shrinkage defect of the half shaft is basically eliminated, and the total volume of the casting shrinkage is reduced to 10.43 cc. Furthermore, the shrinkage and porosity defects in the casting were eliminated by setting cold iron and outlet holes. In the course of solidification, the thick wall of the bottom end cover of the bridge housing casting is prone to the defect of shrinkage holes. By placing cold iron at the thick wall of the end cap, the solidification speed of the thick wall is improved, and the isolated liquid phase zone is avoided when the thick wall is solidified. Furthermore, the shrinkage defect of the end cover is eliminated. Aiming at the problem of shrinkage and porosity in the top of the bridge shell castings during the solidification process, the method of placing air holes in the top of the castings is adopted, which effectively eliminates the shrinkage holes and blowhole defects at the top of the bridge shell castings. Through simulation analysis and technological improvement, the optimum casting process scheme of bridge shell is obtained. The shrinkage hole and pore defect are eliminated and the total volume of shrinkage is reduced to 6.74 cc.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TG255;TH242

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