控制压力冒口在生产中的应用

为了消除球墨铸铁中的缩孔和缩松,保证铸件的内在质量,多年来对大多数中小件我们都按传统的顺序凝固工艺原则,用大冒口对铸件进行补缩。这样,既浪费金属液,工艺出品率又低。为此,我们将传统冒口改为控制压力冒口,取得了明显的经济效益。     

发热冒口在消失模铸造中的应用

采用EPC法生产铸件时,在工艺上一般都要安放冒口,以便解决铸件的补缩问题。但由于泡沫塑料模是在负压条件下边浇注边消失,金属液在充型过程中受到抽气造成的过冷影响,虽然安置了补缩冒口,却起不到应有的补缩效果,特别是铸钢件尤为明显。冒口的外观特征是四周和上端面平齐,这种无缩坑现象说明冒口被过早地冷却凝固和补缩不良。在解剖各种铸件时均发现有程度不同的缩孔缺陷,这是冒口补缩不到位的结果。针对这种冒口过早凝固而铸件得不到有     

控制压力冒口在球铁曲轴铸造工艺中的应用

本文运用球墨铸铁控制压力冒口的原理和方法,通过调整球墨铸铁曲轴有关的工艺因素,在紧实度较低的曲轴潮模砂型铸造工艺中,成功地采用了控制压力冒口,显著地降低了曲轴的缩松缺陷,大大提高了铁水的工艺出品率。     

锥形冒口在球铁件上的应用

介绍了球铁件锥形冒口的原理和设计方法。试验表明,锥形冒口比普通冒口更有效地消除铸件缩松缺陷,并提高金属补缩率。     

控制压力冒口在球铁件中的应用

近年来,随着机械设计对材料强度要求的不断提高,球铁件的需求量也不断增加。球铁大中件由于凝固时温度场分布较均匀,产品质量容易控制,但利用湿型砂生产小型厚壁球铁件是当前国内外生产的难题之一。与干型相比,用湿型生产厚壁球铁小件主要的困难是温度场分布不均,铸型强度低,易产生缩孔、缩松等铸造缺陷,如济南二机床集团有限公司铸造厂生产的DV106—02气缸,曾因缩松造成的废品率达90％以上,严重影响了产品的配套。席文介绍通过调整和控制工艺参数,利用湿型砂生产小型厚壁球铁铸件的工艺技术。     

消失模铸造冒口工艺改进的探讨及应用

在消失模铸造中为避免铸件产生气孔、夹渣、冷隔等缺陷，着重探讨将冒口改为大气压力冒口，并填入覆盖剂，使冒口除起补缩作用外，还有提高铸件保温、排气和集渣的作用，从而提高了铸件的成品率，并推荐了覆盖剂、砂芯基本材料和工艺配方案。     

Status quo and development trend of lost foam casting technology

Lost foam casting（LFC）technology has been widely applied to cast iron and cast steel.However,the development of LFC for Al and Mg alloys was relatively slower than that for cast iron and cast steel.The application of LFC to Al and Mg alloys needs more effort,especially in China.In this paper,the development history of LFC is reviewed,and the application situations of LFC to Al and Mg alloys are mainly discussed.Meanwhile,the key problems of LFC for Al and Mg alloys are also pointed out.Finally,the prospects for LFC technology are discussed,and some special new LFC technologies are introduced for casting Al and Mg alloys.In future,the development trends of green LFC technology mainly focus on the special new LFC methods,metal material,coating,heat treatment,new foam materials as well as purification technology of tail gas,etc.     

Porosity of aluminum alloy in lost foam casting process

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｌｏｓｔｆｏａｍｃａｓｔｉｎｇ (ＬＦＣ) ｐｒｏｃｅｓｓｉｓｃａｌｌｅｄａｓｔｈｅ 2 1ｓｔｃｅｎｔｕｒｙｔｅｃｈｎｏｌｏｇｙ .Ｉｔｓｆｏｒｍｉｎｇｉｓｄｉｆｆｅｒｅｎｔｆｒｏｍｔｈａｔｏｆｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｅｍｐｔｙ ｃａｖｉｔｙｃａｓｔｉｎｇｍｅｔｈｏｄ[1,2 ].ＦｏｒａｌｕｍｉｎｕｍａｌｌｏｙｉｎＬＦＣ ｐｒｏｃｅｓｓ,ｐｏｕｒｉｎｇｔｅｍｐｅｒａｔｕｒｅｏｆａｌｕｍｉｎｕｍｍｅｌｔｉｓｍｕｃｈｈｉｇｈｅｒｔｈａｎｔｈａｔｏｆｔｈｅｅｍｐｔｙ ｃａｖｉｔｙ…     

Heat transfer characteristics of lost foam casting process of magnesium alloy

1 Introduction The growing demand for mass reduction in aerospace and automotive industries has greatly increased the magnesium application. Currently, casting is the main industrial forming method for magnesium alloys, but the lag of research and develop…     

Effect of vibration frequency on primary phase and properties of grey cast iron fabricated by lost foam casting

The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.     

Effect of vibration frequency on microstructure and performance of high chromium cast iron prepared by lost foam casting

In the present research, high chromium cast irons (HCCIs) were prepared using the lost foam casting (LFC) process. To improve the wear resistance of the high chromium cast irons (HCCIs), mechanical vibration was employed during the solidiifcation of the HCCIs. The effects of vibration frequency on the microstructure and performance of the HCCIs under as-cast, as-quenched and as-tempered conditions were investigated. The results indicated that the microstructures of the LFC-produced HCCIs were reifned due to the introduction of mechanical vibration, and the hardness was improved compared to that of the aloy without vibration. However, only a slight improvement in hardness was found in spite of the increase of vibration frequency. In contrast, the impact toughness of the as-tempered HCCIs increased with an increase in the vibration frequency. In addition, the wear resistance of the HCCIs was improved as a result of the introduction of vibration and increased with an increase in the vibration frequency.     

涂料对消失模铝合金铸件孔隙率的影响

利用HST 2型消失模涂料高温性能测试仪研究了涂料组成、涂层厚度、透气性、温度等对聚苯乙烯热解产物通过消失模涂层的传输特性的影响。结果表明 :增加云母粉、珠光粉加入量及涂层厚度 ,涂层透气性下降 ,热解产物传输曲线的峰值上升 ,传输时间增长。探讨了模样热解产物通过涂层的传输行为对消失模铝铸件孔隙率的影响。研究发现 ,热解产物传输曲线峰值高、传输时间长 ,有利于减少铝件的孔隙率。当热解产物传输曲线的峰值及传输时间分别达到 0 .4 12kPa和 4 8.3s以上时 ,铝铸件的针孔率可达到一级。实验结果表明 ,自制的HW 1涂料的传输性能可与美国Ashland涂料的相当     

High Cr white cast iron/carbon steel bimetal liner by lost foam casting with liquid-liquid composite process

Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear,and consequently,the service life of the liner made from traditional materials,such as Hadfield steel ...     

Microstructure and mechanical properties of magnesium alloy prepared by lost foam casting

The microstructure and mechanical properties of AZ91 alloy prepared by lost foam casting(LFC) and various heat treatments have been investigated. The microstructure of the AZ91 alloy via LFC consists of dominant α-Mg and β-Mg17Al12 as well as a new phase Al32 Mn25 with size of about 5-50μm, which has not been detected in AZ91 alloy prepared by other casting processes. The tests demonstrate that the as-cast mechanical properties are higher than those of sand gravity casting because of chilling and cushioning effect of foam pattern during the mould filling. The solution kinetics and the aging processes at different temperatures were also investigated by hardness and electrical resistivity measurements. The kinetics of aging are faster at the high temperature due to enhanced diffusion of atoms in the matrix, so the hardness peak at 380℃ occurs after 10 h; while at the lower aging temperature(150℃), the peak is not reached in the time(24 h) considered.     

A study on the effect of coating''s sorption capacity on the porosity in lost foam aluminum alloy casting

Effects of coating constituent, coating density, coating layer thickness and temperature on coating sorption capacity for polystyrene decomposition products have been studied systematically. It has been found that the effect of attapulgite clay on sorption capacity is the largest among coating constituents. The sorption capacity of the coating with 2 %attapulgite clay is elevated by 81%. The relationship between casting porosity and coating sorption capacity has been studied. It has been pointed out that higher coating sorption capacity for polystyrene decomposition products is helpful to decrease the casting porosity. Results also show that the sorption capacity of self- developed HW- 1 coating for polystyrene decomposition products is as good as that of Ashland coating from America.