球铁缸盖缩松原因分析与解决措施

针对某球铁缸盖铸造过程中出现的缩松问题,通过对缩松发生部位进行分析研究,结合铸造模拟软件对现有工艺进行优化,通过改进浇注方式、优化冒口设计、增加明出气孔等措施,最终解决了缸盖缩松问题,并实现了批量生产。     

大断面球铁轧辊冒口颈部疏松的控制

随着先进连轧机的引进，轧钢过程的平稳、不出轧制事故成为提高轧钢效率及板材质量的关键因素之一。为了提高轧辊辊颈强度，防止出现断辊等恶性事故，大断面离心轧辊芯部组织由灰铸铁改为球墨铸铁。但产品在加工检测时，发现冒口端辊颈有疏松现象，因此，解决这个问题成为提高产品质量的关键。     

6110车用柴油机蠕铁缸盖生产技术

简要地介绍6110车用柴油机蠕铁缸盖的熔炼、蠕化处理工艺和铸型工艺.1998年以前为冲天炉熔炼,分别采用过稀土硅铁合金出铁槽冲入法处理工艺、稀土硅化物出铁槽冲入法处理工艺和低镁稀土硅铁镁蠕化剂包内处理工艺,其时采用1410微震压实造型机造型,铸型工艺为侧面进铁,顶部设置冷冒口.用此工艺批量生产约15年,废品率一直维持在20%～25%.自1998年开始采用冲天炉与感应电炉双联熔炼,HWS静压线造型,MECANA全自动浇注机浇注,包内冲入-引爆法蠕化处理(稀土硅铁为蠕化剂,稀土硅铁镁为搅拌剂),铸型工艺进行了较大的改进:采用顶置长方形压边冒口,并经由冒口进铁.此工艺10年的生产实践表明,总废品率明显降低,一般稳定在7%左右.     

大断面球墨铸铁的新型优化工艺措施

球铁铸件壁厚大于50mm时即称为大断面球铁,大断面球铁因为凝固缓慢极易产生球化衰退、黑斑、缩松等缺陷,严重影响其强度和塑性(伸长率),因此必须采取必要的工艺措施:1.采用适量的钇基重稀土复合球化剂进行球化处理。2.加入锑、铋等微量元素[w(Ti)0.01%、w(Bi)0.01%],采用强制冷却,顺序凝固的工艺措施。3.提高大断面球铁的残余稀土、镁量[w(RE)0.06%、w(Mg)0.065%]。4.采用瞬时孕育、多次孕育强化孕育处理措施。     

悬浮浇注对大断面球铁石墨形态及凝固特性的影响

研究了悬浮浇注对模拟大断面球铁试块石墨形态及凝固特性的影响,并初步分析了悬浮浇注的作用机理。试验结果表明,悬浮浇注可明显改善大断面球铁的石墨形态和凝固特性。     

减少M3000R蠕铁缸盖气缩孔的措施

介绍了M3000R蠕铁缸盖的生产工艺,统计发现气缩孔主要出现在气门导管孔、螺栓孔等相对厚大的热节部位。分析"气"的来源主要有:造型材料发出的气体;熔炼过程带入的[N]、[O]在凝固过程析出N2、CO,浇注时卷入的气体。通过优化冲天炉配料和送风参数、严格控制蠕化剂的加入量、在导管孔处加外冷铁、在螺栓孔处加内冷铁等措施,M3000R缸盖的气缩孔废品率由2007年的9.9%下降到2010年的0.2%,总废品率也由2007年的15.9%下降到2010年的2.95%。     

蠕墨铸铁缸盖孤立热节区缩松缺陷分析及对策

随着商用车发动机功率和爆压增大,发动机缸盖承受的载荷愈来愈高,铸件材质从传统的HT300提升到RuT450,而复杂的产品结构和RuT450材料均使铸造工艺性变差。介绍某大马力发动机缸盖铸件在HWS静压造型线上一型两件立浇工艺条件下,针对RuT450材质及孤立热节区域缩松问题进行工艺研究与验证的情况,通过浇注系统的补缩改进、多种冷铁方案的应用、铁液蠕化率的管控等措施实施,有效解决了缸盖铸件喷油孔、导管孔、螺栓孔等孤立热节部位缩松问题。     

大断面铸态球铁的生产

大断面铸态球铁的生产捷华压缩机有限公司（浙江省余姚市３１５４００）陈荣良裘建军ＴｈｅｐｒｏｄｕｃｔｉｏｎｏｆＨｅａｖｅｙＳｅｃｔｉｏｎｅｄＡｓｃａｓｔＤｕｃｔｉｌｅＩｒｏｎＣｈｅｎＲｏｎｇｌｉａｎｇＱｉｕＪｉａｎｊｕｎ（ＪｉｅｈｕａＣｏｍｐｒｅｓｏ...     

基于NX及NOVACAST对大断面球铁件的数值模拟

在大断面球铁轴承座的工艺设计过程中,充分运用NX对铸件进行实体建模,并对其壁厚进行分析,通过对浇、冒系统计算,并采用NovaCast对其流场、温度场、缺陷进行预判以及工艺优化。经过实际生产验证,UT探伤及MT探伤均无问题,确保产品的质量。     

Production technique of vermicular graphite iron cylinder head of vehicle diesel engine

The 25 years＇ production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using cupola-induction furnace duplex melting and pour-over process with rare earth-ferrosilicon or rare earthsilicon compound as vermJcularizing alloy plus rare earth-magnesium-ferrosilicon as stirring alloy, is an optimal vermicularizing process for obtaining satisfied vermicularity. Using top kiss risers, enlarging kissing areas and expanding covering width and making ingates to freeze earlier are the effective measures to eliminate shrinkage, blowhole and oxide inclusions in the vermicular graphite iron cylinder heads.     

Development of thermal simulation system for heavy section ductile iron solidification

A new reliable thermal simulation system for studying solidification of heavy section ductile iron has been developed using computer feedback control and artificial intelligent methods. Results of idle test indicate that the temperature in the system responses exactly to the inputted control data and the temperature control error is less than ± 0.5 %. It is convenient to simulate solidification of heavy section ductile iron using this new system. Results of thermal simulation experiments show that the differences in nodularity and number of graphite nodule per unit area in the thermal simulation specimen and the actual heavy section block is less than 5 % and 10 %, respectively.     

地铁用电机端盖缩孔缺陷分析及预防

通过对球墨铸铁件电机端盖零件材料及热节的分析,合理设计保温冒口,消除热节处的缩孔,确保端盖铸件内部质量合格。     

Quantitative models for microstructure and thermal conductivity of vermicular graphite cast iron cylinder block based on cooling rate

The relationships of cooling rate with microstructure and thermal conductivity of vermicular graphite cast iron(VGI) cylinder block were studied, which are important for design and optimization of the casting process of VGI cylinder blocks. Cooling rates at different positions in the cylinder block were calculated based on the cooling curves recorded with a solidification simulation software. The metallographic structure and thermal conductivity were observed and measured using optical microscopy(OM), scanning electrical microscopy(SEM) and laser flash diffusivity apparatus, respectively. The effects of the cooling rate on the vermicularity, total and average areas of all graphite particles, and the pearlite fraction in the VGI cylinder block were investigated. It is found that the vermicularity changes in parabola trend with the increase of cooling rate. The total area of graphite particles and the cooling rate at eutectoid stage can be used to predict pearlite fraction well. Moreover, it is found that the thermal conductivity at room temperature is determined by the average area of graphite particles and pearlite fraction when the range of vermicularity is from 80% to 93%. Finally, the quantitative models are established to calculate the vermicularity, pearlite fraction, and thermal conductivity of the VGI cylinder block.     

An analysis of shrinkage defects in aluminium and aluminium-copper castings

The influence of casting parameters and alloy composition on the formation of shrinkage defects has been studied using a T-piece test casting. Macro shrinkage defects were found in pure aluminium and aluminium 0.4wt% copper castings, but not in aluminium 1, 2, and 4.5 wt.% copper alloys. The thermal data which were in general, reproducible to +/-5% showed that a negative temperature gradient prevailed in the pure and aluminium 0.4wt% aluminium alloy right up to the end of freezing. In the aluminium 1, 2 and 4.5 wt.% copper alloys the initial negative gradient changes to become positive after approximately one half of the total solidification time has elapsed. The gradient was only of the order of 2°C/mm. Variations in pouring temperature of about 50°C and filling times of a factor of three changed the solidification times by 10% only. Such variations did not change the relative freezing times at different locations in the uniform section castings. Solidification times for the 15 mm horizontal section of the castings (a/b = 0.6) were similar to those of the 25 mm sections (a/b = 1) showing that even in this simple case the modulus concept is invalid. The form of the cavities in the feeder heads is a function of the metal cast, the gas content and the grain structure. The results formed the basis of validation tests for a computer shrinkage model.**     

后辊中心距可调结构在大型型材弯曲机上的应用

以CDW24S-5500 cm3大型型材弯曲机为例,介绍了后辊中心距可调式大型型材弯曲机的技术性能及结构特点。采用两后辊中心距可调的结构形式,三个主轴采用双点支撑,两后辊采用分辊驱动,架体可拆分,使得整个机器结构新颖,受力合理,成形准确,安装运输方便,是大型型材弯曲机较为理想的一种技术方案。     

Construction and analysis of dynamic solidification curves for non-equilibrium solidification process in lost-foam casting hypoeutectic gray cast iron

Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve (DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation (TAL) and the start temperature of eutectic solidification (TES); double curves method to determine the temperature of the dendrite coherency point of primary austenite (TAC) and the temperature of eutectic cells collision point (TEC); the "technical solidus" method to determine the end temperature of eutectic reaction (TEN). For this purpose,a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction (fs) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting.Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process (from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting,the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer.     

Ni对厚大断面球铁显微组织和力学性能的影响

以不含Ni和含Ni的厚大断面球墨铸铁为研究对象,并对其进行低温两阶段退火处理(760℃+4 h和730℃+4 h)。采用光学显微镜、扫描电镜、电子万能试验机和布氏硬度计等研究了厚大断面球铁试样不同部位的显微组织和力学性能。结果表明:退火处理后,试样的铁素体含量达到了95%以上。随着凝固时间的增加,从试样表面到心部位置,出现了畸形石墨,导致力学性能急剧下降。与未加Ni相比,含0.6%Ni试样的石墨球细小圆整,基体组织得到细化,力学性能明显提高。     

安徽省巢湖市尖山铁矿北段地质特征及找矿标志

安徽省巢湖市尖山铁矿北段位于肥东新太古代—早元古代变质岩区浮槎山—大康集复背斜中段南东翼,铁矿体主要赋存于大横山岩组斜长片麻岩中,属沉积变质型铁矿床.基础地质和成矿作用研究工作揭示了该区具有寻找沉积变质型铁矿的良好前景,但本区铁质来源不够丰富,而且地壳振荡运动频繁,以致矿体范围较小;虽然矿层层数多,但单层薄,规模偏小....