钣金工艺中的激光加工技术

激光加工技术在钣金加工中起着重要作用,极大地提高了钣金加工的生产率并促进了钣金加工的发展。在钣金加工中,激光切割机可以大大缩短加工周期,提高加工精度,加快产品开发,降低成本。许多制造公司权衡这些优势。激光切割机越来越多地用于钣金加工。详细讨论了激光技术和激光技术的应用。分析了激光技术在钣金加工中的应用和优势。     

大孔径轧制机架的加工分析

介绍了大孔径钢管生产线机架的整套加工分析。加工前期,结合机架的结构特点,对比常规加工方式,分析加工难点,研发设计工装夹具,解决了加工难题;加工中期,通过实际生产制造,不断总结加工经验,形成系统化的问题解决措施,最终成功完成了设备的加工制造。该项目提高了公司的制造能力,开拓了新的加工领域,产生了较大的经济效益。     

球面轴承座内孔加工装置的设计

球面轴承座内孔加工装置的设计,是在充分保证混料机球面轴承座内孔加工质量和满足产品技术要求的前提下,实现了我国现有不同规格水泥混料机支撑轮轴承座的内孔球面加工。应用本球面轴承座内孔加工装置的设计技术,有效地解决了口径小、内球面直径大的轴承座类零件在普通设备上的难加工问题,使普通设备的加工质量达到了数控设备加工的水平,从而可以很大程度上代替了数控设备加工,保证了加工质量,降低了生产成本,提高了产品效率。     

针对H13芯棒的加工实例探讨细长轴的加工工艺

细长轴的加工一直是车床的加工难点,本文以H13芯棒加工为实例对细长轴的加工做出了详细阐述,提出了解决细长轴加工时弯曲变形问题的机械加工工艺措施,在芯棒加工中取得了良好效果。     

基于VERICUT的整体叶轮五轴数控加工仿真研究

针对五轴数控加工及碰撞干涉问题,通过建立加工工艺系统模型,将应用Siemens NX系统编制的加工程序导入VERICUT仿真软件,在进行加工之前,尽可能真实地在虚拟环境里模拟加工整个过程和加工的结果,对其整个加工过程进行仿真,避免了实际加工碰撞干涉现象,消除了实际加工事故隐患。     

环孔型加工工艺及装备

环孔型加工机床是高速二辊二线孔型轧管机轧辊加工的专用设备。上海第二铜管厂详细分析对比了机械加工,电解加工,电脉冲加工,电火花线切割加工多种方案,最后选用电脉冲技术并解决了四大技术关键,成功地研制出我国第一台数控双钼丝电火花线切割环孔型轧辊加工机床,填补了我国在长行程环孔型轧辊加工上的空白。该加工机床的特色是: 1.采用了双钼丝,高丝架,三座标,     

镁合金塑性加工新工艺

介绍了镁合金的性能及现状。综述了难变形镁合金的塑性加工新技术,包括氢化处理技术、电塑性加工技术及大塑性变形加工技术。对这几种新加工技术的特点及发展现状进行了详细介绍,最后,总结了这些技术针对镁合金加工的应用前景。     

隔膜泵中阀座加工工艺的改进

阀座是隔膜泵中的主要易损件之一,大约1个月左右就要更换一次。为了提高阀座的生产加工效率,解决设计改进后新结构阀座的加工难点,对阀座的传统加工工艺进行了改进,把传统工艺中的磨削加工改为车削加工,大大的缩短了生产周期、提高了加工效率、降低了生产成本、提高了产品精度及表面质量。     

铝合金支架加工变形控制方法

论述了铝合金框架类零件的加工变形控制方法,分析了加工变形产生的原因,提出了通过提高零件整体刚性来控制加工变形的方法,并根据零件特点,设计了专用工装,增强了零件的刚性,控制了加工变形,给铝合金框架类零件加工提供了技术支持。     

矿业机械数控加工技术水平的提升方式研究

近些年,国内的机械行业发展也逐渐进入到了高峰期,而矿业机械数控加工技术也得到了极大的发展进步,但在取得可观成绩的同时,机械数控加工技术仍然存在一些问题亟待解决,需要对机械数控加工技术加强研究。因此对机械数控加工技术水平的提升方式进行了深入的研究,分析了机械数控加工技术的概念、特点以及发展现状,并详细阐述了矿业机械数控加工技术存在的问题,从而提出了一些机械数控加工技术水平的提升的建议和方式。     

end5, end6, and end7: mutations that cause actin delocalization and block the internalization step of endocytosis in Saccharomyces cerevisiae

Four mutants defective in endocytosis were isolated by screening a collection of temperature-sensitive yeast mutants. Three mutations define new END genes: end5-1, end6-1, and end7-1. The fourth mutation is in END4, a gene identified previously. The end5-1, end6-1, and end7-1 mutations do not affect vacuolar protein localization, indicating that the defect in each mutant is specific for internalization at the plasma membrane. Interestingly, localization of actin patches on the plasma membrane is affected in each of the mutants. end5-1, end6-1, and end7-1 are allelic to VRP1, RVS161, and ACT1, respectively. VRP1 and RVS161 are required for correct actin localization and ACT1 encodes actin. To our surprise, the end6-1 mutation fails to complement the act1-1 mutation. Disruption of the RVS167 gene, which is homologous to END6/RVS161 and which is also required for correct actin localization, also blocks endocytosis. The end7-1 mutant allele has a glycine 48 to aspartic acid substitution in the DNase I-binding loop of actin. We propose that Vrp1p, Rvs161p, and Rvs167p are components of a cytoskeletal structure that contains actin and fimbrin and that is required for formation of endocytic vesicles at the plasma membrane.     

炼钢终脱氧工艺优化

针对炼钢终脱氧工艺长期以来用铝块作终脱氧剂,存在回收率低、成分波动范围大的弊端,根据终点碳和终点温度的碳氧平衡计算公式导出初始含氧量,并由Al-O平衡曲线导出目标座包铝含量的钢芯铝用量。将理论计算应用到了现场的终脱氧工艺中,对炼钢终脱氧工艺优化有指导作用。     

低磷低硅铁水180 t复吹转炉冶炼高磷钢的工艺优化

在统计分析了转炉前期炉渣碱度和钢水温度,终点炉渣碱度、终渣全铁含量和终点钢水温度对脱磷率影响的基础上,优化了0.29%Si,0.085%P铁水180t复吹转炉的高磷钢冶炼工艺。200炉冶炼结果表明,通过使用低枪位使钢水快速脱碳升温,控制前期炉渣碱度≥2.2、终点炉渣碱度2.8~3.2,终点炉渣全铁含量≤17%,转炉出钢温度1 650~1 680℃,可控制脱磷率≤60%,终点钢水磷含量均值为0.035%。     

End Depth–Discharge Relation at Free Overfall of Trapezoidal Channels

For steady flow near the free overfall (end section) of a horizontal trapezoidal channel, the velocity distribution is nonuniform and the streamlines are curved. An accurate relation between discharge rate and end depth was formulated including these effects. To determine these effects, the streamline pattern in the vertical plane of channel symmetry was determined using measured velocity components and the water surface profile. At the end section, the streamline pattern yielded the streamline curvature, which in turn provided the curvature correction required to predict the true static pressure head profile. The measured static pressure head distribution agreed well with the predicted static pressure head distribution for the end section. The pressure force at the end section was obtained on the basis of the measured static pressure distribution at the end section, and this information yielded a reliable relation between the end depth and the channel discharge rate. Analysis of present and past experimental data indicated that, the pressure head coefficient was the dominant parameter that influences the relationship between discharge rate and end depth in trapezoidal channels. Near the end depth, in the region above the maximum velocity point, the total energy determined from the measured velocity and pressure fields was essentially constant.     

单轴压缩试验中减弱端部效应新型方法研究

为了减弱端部效应对单轴抗压强度测量的影响,提出一种新型的单轴压缩试验方法。该方法采用与试件材质相同的岩石作为垫块进行单轴压缩试验,设置了（25+50+25）mm和（20+60+20）mm 2种试件高度组合进行试验,并与高度为50 mm、60 mm的单一试件的试验结果进行对比。结果表明：该新型试验方法可以降低单轴压缩试验中端部效应对测量岩石单轴抗压强度的影响,并得到更为均匀的径向应变;（25+50+25）mm和（20+60+20）mm组合试件相比高度为50 mm和60 mm的单一试件,单轴抗压强度分别降低了38.41%和39.69%,相比标准试件,单轴抗压强度也有所降低。数值模拟结果表明：无论有无端部摩擦,组合试件的单轴抗压强度均与理想状态下模拟所得的岩石试件的单轴抗压强度值接近;无端部摩擦时单个试件与组合试件具有均匀的径向应变;有端部摩擦时组合试件的径向应变较为均匀。数值模拟结果证明了该新型试验方法减弱了端部效应,但并未完全消除。     

轴承钢端面碎裂原因分析与改进

通过对轴承钢端面碎裂进行分析,认为钢材端部的异常组织是导致矫直后端部碎裂的主要原因。由于轴承钢采用摩擦锯进行定尺锯切,使端部受热,并且端部组织发生了组织转变而产生碎裂。针对分析结果,采取了使用进口锯片锯切的补救措施,解决了钢材矫直过程中的碎裂问题。     

Experiment on dephosphorization process of “remaining slag double slag” in combined blown converter

The dephosphorization process test was carried out in a domestic converter steel plant by using the “remaining slag double slag” process technology. The results show that with the increasing of dephosphorization rate in early stage of converter, the end point dephosphorization rate increases continuously. The silicon content in molten iron has the greatest influence on the dephosphorization rate in early stage. According to the composition of molten iron, properly reducing the oxygen supply intensity, reducing the gas solid oxygen ratio，adding an appropriate amount of lime and sinter in early stage of smelting are conducive to the improvement of dephosphorization rate in early stage. Adding lime of 4-8kg per ton of molten steel in the first turn down stage does not affect the tapping temperature, which can improve the dephosphorization rate in the first turn down to end point stage and the end point dephosphorization rate at the same time. From the control effect of the end point, the alkalinity of the end point slag should not be less than 3.0, the mass fraction of FeO in the slag should be 16%-20%, and the end point tapping temperature should be appropriately reduced to 1610-1630℃, which is conducive to the improvement of the end point dephosphorization rate. By strengthening of the stirring of molten pool and promoting the balance of the steel slag reaction, it is conducive to improvement of the end point phosphorus distribution ratio, so as to further improve the end point dephosphorization rate.     

100 t 顶吹氧气转炉石灰石造渣炼钢技术的分析和工艺实践

通过石灰石造渣前期成渣机理的分析和转炉热平衡计算得出石灰石消耗为6.0t/炉时,需增加铁水消耗2.1t/炉,减少2.5t/炉废钢消耗,可保证石灰石炼钢终点温度和石灰炼钢终点温度一致。生产试验得出,石灰石造渣炼钢转炉终点碱度(3.3),终点温度(1662℃)、终点[C](0.081%)、[P](0.016%)、命中率(90%)和普通石灰造渣炼钢工艺一致,但降低转炉炉料成本10.4元/t钢,取得良好的经济和社会效益。     

Scanning electron microscopic evaluation of the cleanliness of a new ultrasonic root end preparation

Recently introduced ultrasonic instrumentation techniques for root end preparation have revolutionized the field of endodontic surgery. The specially designed tips offer improved access to the root end and create more conservative root and preparations while decreasing the amount of retained debris. This study compared the cleanliness of root end preparations made using ultrasonic instrumentation with that of those prepared in a traditional manner using a microhandpiece bur. We used 10 extracted maxillary human premolars and molars. After cleaning, shaping, and obturation of the root canals, a 3 mm root end resection perpendicular to the long axis of the root was performed with a carbide fissure bur. The roots were randomly divided into two groups and root end preparations were made using the two aforementioned techniques. The roots were longitudinally split and sputter-coated with gold for scanning electron microscopic study. Three independent dentists used a standardized grading system to evaluate the cleanliness of the root end preparations. The ultrasonic preparation had significantly less superficial debris and a thinner smear layer than the microhandpiece preparation (p < 0.05). There were no significant differences between the canal and isthmus portions of the root end preparations within each group in either superficial debris or smear layer. This indicates that cleaner surfaces for root end cavities are created using ultrasonic retrotips than using microhandpiece burs.