YC6113柴油机蠕墨铸铁缸盖铸件的质量控制

通过合理选择炉料配比,并在冲天炉出铁时脱硫,可以有效得到满足蠕墨铸铁生产的低硫原铁液,同时正确选择控制化学成分、熔炼工艺及蠕化处理方法,并使用长方形压边冒口工艺,使牌号为RUT340的柴油机缸盖铸件的蠕化率≥75％,金相组织中珠光体体积分数稳定达到98％以上,石墨长度为4级,硬度≥160HBS,铸件综合废品率低于8％,满足相关技术和质量控制要求。     

侧浇工艺在汽缸盖类铸件上的应用

汽缸盖类铸件的传统浇注工艺大多采用铸件大平面朝下或朝上的平浇底注或硕注工艺,而侧浇工艺使铸件大平面处于侧立位置。主要介绍了侧浇工艺的特点及在汽缸盖类铸件上的应用,大量生产实践证明：采用侧浇工艺,可提高铸件品质,提高生产率,节约生产成本。     

YCZA30汽缸盖铸件顶面气孔成因及其对策

通过对YCZA30缸盖顶面气孔缺陷的成因进行分析,针对性地制定了防止措施。使用发气量小的芯砂,防止整体浸涂过程中堵塞排气通道,以及使用砂芯替代铸型形成铸出孔的工艺,能有效地解决缸盖类铸件的顶面气孔问题。     

Compliance based assessment of stress intensity factor in cracked hollow cylinders with finite boundary restraint: Application to thermal shock part I

The evaluation of mode I stress intensity factor associated with the creep-free thermal shock (TS) of finite length elastically/thermo-elastically restrained cracked hollow cylinders is a problem of interest. Among existing evaluation methodologies, the mechanical weight function approach is often perceived to be an optimal compromise between simplicity and accuracy for and more generalised K_I evaluation. However, to confidently apply a mechanical weight function methodology in such circumstances requires the derivation of different weight functions for each potential boundary restraint configuration, i.e. free, flexible or rigid boundary conditions. In this article, the traditional mechanical weight function philosophy is complimented with an elastic compliance analysis, enabling the mechanical weight function and geometry factors for an equivalent semi-infinite cracked hollow cylinder to be used to evaluate associated with a wide range of finite length elastically/thermo-elastically restrained cracked hollow cylinders. The need for deriving different weight functions is therefore removed and the proposed Compliance Adjusted Weight Function (CAWF) approach becomes more ‘user-friendly’. The targeted cracked hollow cylinders are assumed to exhibit an exterior circumferential edge crack or an exterior circumferential semi-elliptical surface crack.     

Effect of FGM coating thickness on apparent fracture toughness of a thick-walled cylinder

This study describes the effect of FGM coating thickness on apparent fracture toughness (AFT) of a thick-walled cylinder containing two diametrically-opposed edge cracks emanating from the inner surface of the cylinder. The incompatible eigenstrain developed in the cylinder due to nonuniform coefficient of thermal expansion because of cooling from sintering temperature is taken into account. Based on a generalized method of evaluating stress intensity factor (SIF) addressed in a previous study, an approach is developed to calculate AFT. Some numerical results of AFT are presented for a TiC/Al₂O₃ FGM coating at the inner surface of an Al₂O₃ thick-walled cylinder.     

阳极导杆液压夹具的结构设计与实践

主要介绍了一种新型的油缸竖置式阳极导杆液压夹具,并对油缸的重要部件进行了校核分析,此种液压夹具针对以往油缸横置式液压夹具进行了全新的改进,具有结构简单、维修方便、定位准确等优点。在工作过程中,不但提高了更换新旧阳极碳块组的速度,还可减轻的工人劳动强度,提高生产效率,目前已经在国内多家铝厂应用。     

梅钢1420mm冷轧机液压压下系统的设计计算

液压压下系统是现代高速冷连轧机的核心设备。在梅山钢铁公司1420 mm酸轧机组自主集成建设过程中,根据产品的质量和生产要求,在对以往引进轧机压下系统深入剖析的基础上,通过理论计算最终确定了压下缸、伺服阀的型号,以此为重点完成了1420 mm轧机液压压下系统的设计,并在随后的调试和使用中验证,达到了设计效果。     

伺服阀共用电源的潜在隐患

在进行控制系统设计时,考虑到成本因素,经常会在备用设备中采用共用电源,本文通过酒钢中厚板轧机的AGC系统中互备伺服阀采用的共用电源带来的故障,阐述了共用电源对系统运行带来的潜在隐患。     

掘进机液压执行元件的爬行研究

为了改善悬臂式掘进机执行元件的爬行现象,增强掘进机的系统稳定,文章以回转液压缸为代表实例进行受力分析,得到了导致回转液压缸爬行现象产生的因素,通过改变系统可变参数,解决了回转液压缸产生爬行的问题,通过此实例可以解决掘进机液压系统中执行元件的类似爬行现象。     

砂岩孔道试样压拉应力下强度和破坏的研究

 为研究岩石压拉应力下的强度和破坏,对外径50 mm、孔道6～25 mm的孔道圆柱试样进行不同轴压下的内压致裂试验,对外径50 mm、孔道4.6～20.0 mm的圆环进行巴西劈裂试验。试验结果表明：轴向应力低于单轴压缩强度80%时孔道试样在内压下拉伸破裂,压力与轴向应力没有明显关系;试样承载的孔道内压随孔道直径的增加而减小,孔壁的最大拉应力也随孔道直径的增加而略有减小,试样承载的平均切向应力随孔道直径明显增加;孔道试样能够承受的拉应力远大于巴西劈裂强度,如内孔直径25 mm 的试样可以承载10 MPa的内压,切向拉应力在内壁为17 MPa左右、外侧面为7 MPa左右,而6个完整圆盘的巴西劈裂强度最大值仅为6.17 MPa。内孔直径小于20 mm 的试样,因内压增大孔壁处岩石拉伸变形增大到极限、引起裂纹扩展,最终破裂成2块;而内孔直径25 mm 的试样,在内孔压力达到破裂压力时,孔壁处材料没有达到断裂所需要的变形,因而只有试样外侧也达到屈服应力才能整体断裂。承载非均匀应力的岩石结构需要考虑载荷和变形2个破坏指标。