共查询到19条相似文献,搜索用时 640 毫秒
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对高铝锌合金的线收缩和缩孔率进行了测定,并着重考察了该合金的底缩现象。试验结果表明,在砂型铸造条件下,产生底缩铸件的临界模数为1.25cm,加快铸件冷却是消除底缩的最有效途径,合金中加入微量的第ⅡA族元素也可消除底缩。 相似文献
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基于ProCAST的复杂泵体熔模铸造工艺模拟 总被引:1,自引:0,他引:1
《热加工工艺》2018,(23)
泵体结构较为复杂,壁厚变化,易出现缩孔缩松缺陷。设计了底注式与顶注式浇注系统,通过ProCAST软件模拟分析了流场、温度场、孤立液相区及缩孔缩松体积与分布。结果显示,与底注式浇注系统相比,顶注式浇注系统凝固时间少了(315.4 s从2843.45 s到2528.05 s),缩孔缩松体积减少了63%从8.41 cm~3到3.10 cm~3;耗费的金属液更少,且铸件品质更好。 相似文献
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TiAl基合金连杆件底漏式真空吸铸数值模拟 总被引:1,自引:0,他引:1
利用ProCAST数值模拟技术对TiAl合金汽车发动机连杆铸件底漏式真空吸铸过程的充型过程、凝固过程、缩孔缩松缺陷形成进行了模拟。研究了底漏式真空吸铸的几个主要参数,如吸口直径、浇注温度、浇注速度,对连杆铸件充型凝固过程和缩孔、缩松缺陷的影响规律,得到了TiAl合金底漏式真空吸铸的优化工艺参数图。 相似文献
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车用柴油机蠕墨铸铁缸盖铸造工艺探讨 总被引:2,自引:3,他引:2
采用底注或分型面侧注,顶置冷冒口、砂型、砂芯多开气眼等传统工艺方法不可能彻底消除缩孔、缩松、气孔和气缩孔等常见缺陷,是缸盖生产长期废品率高的主要原因。采用顶置热冒口,扩大冒口覆盖范围,铁液通过冒口进入型腔,提高浇注液流压力,利用冒口铁液压力进行液态补缩和阻止气体进入热节,是消除缩孔、缩松、气孔和气缩孔的有效措施。 相似文献
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分析XG5-1黄铜铸件缩孔缺陷的形成原因,通过调整工艺参数,采取底注式浇注系统和增设冒口的工艺措施,有效地解决黄铜缩孔、缩松等缺陷,取得经济效益. 相似文献
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ZA-27合金砂型铸造产生的底缩是凝固期中Zn的宏观偏析引起的。富锌合金液最后凝固,铸件先凝固部分的收缩处从底部供应补缩金属。用录像法观察了底缩现象后指出:缩孔产生于合金已凝固79~90%时。可以通过使用冷铁和冒口、控制铸件成分的宏观偏析,来解决底缩问题,同时,提出在设计铸件时,使用晶间液体流动的模似分析避免底缩。 相似文献
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通过分析轴套铸件铸造难点,确定合理铸造工艺:采用顶部环形冒口,使冒口延续度达到100%,避免缩孔、缩松产生;采用底部间接外冷铁工艺,延长冒口补缩距离,使铸件获得自下而上的顺序凝固,获得组织致密铸件;采用铸件表面全敷铬铁矿砂工艺,提高表面质量。通过对各化学成分精准控制,获得力学性能达标的铸件。 相似文献
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Central shrinkage crack is a common defect encountered in steel ingot casting. It is necessary to limit the degree of crack in case of further propagation in forging. A 234-t steel ingot was dissected to check the internal quality, and a central shrinkage crack band of 1,400 mm in height and 120 mm in width, was found at a distance of 450 mm under the riser bottom line. Then, thermo-mechanical simulation using an elasto-viscoplastic finite-element model was conducted to analyze the stress-strain evolution during ingot solidification. A new criterion considering mush mechanical property in the brittle temperature range as well as shrinkage porosity was used to identify the shrinkage crack potential, where the degree of shrinkage porosity is regarded as a probability factor using a modified sigmoid function. Different casting processes, such as pouring speed, mould preheating and riser insulation, were optimized with the simulation model. The results show that fast pouring, proper mould preheating and good riser insulation can alleviate shrinkage crack potential in the ingot center. 相似文献
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运用Procast软件对HSi80-3硅黄铜船用舵盖零件在两种浇注工艺方案下的凝固过程进行模拟计算,在此基础上分析探讨了该铸件可能产生缩孔或缩松的部位。模拟显示第一种浇注工艺会在零件主体部位产生严重缩孔,而第二种浇注工艺则能自下而上顺序凝固,避免缩孔或缩松的产生,据此确定了第二种铸造工艺方案,并采用试验进行验证。结果表明,此浇注工艺没有产生技术要求缺陷,证明了凝固模拟的可行性。 相似文献
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The current work presents a simulation and experimental study on the formation characteristics of sinking thin-walled copper tube with axially inner micro grooves (TCTAIG) through radial forging. A finite element (FE) model is established. The deformation of grooves, distribution of equivalent stress and strain, and the effects of process parameters are analyzed using a FE software. Experiments with the same parameter settings are compared with the simulations. The axial elongation and radial shrinkage of TCTAIG can be obtained. The grooves are twisted as helical lines in the sinking zone. The metal flows axially and tangentially. The maximal equivalent stress and strain occur at the bottom of the grooves. The equivalent strain increases as the step increases, and finally stays at a certain value: bottom of grooves, 0.9; outer surface, 0.8; and top of teeth, 0.3. The equivalent strain becomes more uniform, the force of dies reduces, and the elongation ratio decreases with increasing feed speed. The equivalent stress, force of dies, and axial pushing force increases rapidly with increasing shrinkage rate. Apparent collapse occurs and the surface quality of the forged part becomes worse at a low feed speed or a shrinkage rate of 50%. 相似文献