Study on strip buckling in continuous annealing lines/hot galvanizing

In continuous annealing lines/hot galvanizing,strips are guided by upper and lower rolls in an alternate up and down vertical motion.This kind of process consisting of heating,soaking,and cooling furnaces(or zones) has several advantages in terms of productivity and product quality.Main problems encountered in continuous annealing lines are misguiding and formation of buckling.The strip buckling causes the strip to be rejected and,in the worst case,the strip breaks and the continuous annealing lines are compelled to stop.In this paper the elastic-plastic model of the strip traveling and the corresponding boundary condition were constructed dependant on the theory of mechanic.Simulations are performed in two steps.First,a homogeneous longitudinal tensile stress is applied at one end of the strip,the other end of the strip and the roll are restricted.In the second step,the applied tension remains constant.A uniform displacement is applied to the other end of the strip and a rotation to the roll. The transverse compressive stress,the buckling formation during strip traveling process,the location for the buckling taking place and the buckling criterion were investigated systematically.The result shows that the transverse compressive stress increases with the increase of the tensile stress and the crown of the tapered roll. Because the contact area between the tapered roll and the strip increase with the decrease of the crown,the tensile stress distribution is more homogeneous in the transverse direction of the strip.An additional transverse compressive stress is created and a buckling is also observed due to the friction during the strip motion in the second step.Once the buckling is appearance,it is very hard to be removed only through decreasing the applied longitudinal tension,because the strip wrinkle still keeps high level due to the effect of the buckled strip,the wrinkle would evolve into buckling eventually.The buckling formation process predicted by the finite element model is very similar to those observed in industrial processing lines.It takes place on the cylindrical part of the tapped roll and the buckling is moving to the middle part of the tapped roll with the increase of the crown,its width is about 2-4 mm.The criterion for the buckle occurrence is also discussed,in the prescribed situation,the transverse shell curvature increases with the strip displacement,if the transverse shell curvature reaches 0.1 mm^(-1), the buckling would take place.

Driving control technology for a continuous annealing line

This paper introduces AC variable-speed driving control technology application in the continuous annealing line,including the drive system configuration,the driving control characteristics of CAL and the main control functions of the drive system.Firstly introduces the main process of the continuous annealing line,the features of the 6SE70 series common DC bus drive system and the G150 series drive system. Secondly,for the continuous annealing line,there are more strict requirements for the continuity of production and more special requirements for the drive control characteristics.We do a lot of improvement and standardization for the driving control functions and the interfaces of the line automation control system. This paper discusses the communication interface specifications and the dimension transformation methods between the drive and the basic automation system.The detail dimension transformation methods and calculation method about the line speed setting and the actual roller dimension setting are given,and detail description for the calculation method of the reference speed in the drive.Article also emphasized illustrates realizing and testing methods of inertia compensation of equipment in the drives,and standardize the value of line accelerate and decelerate rate,and the inertia test method and inertia compensation coefficient calculation method is introduced in this paper.For the bridge rollers and furnace help rollers load balance control,this paper presents two different load balance control strategies,the load balance control principle for bridge rollers which data communicates from main station to slave stations by Simolink,and the load balance control principle for furnace help rollers which use droop control.The different characteristics of those two methods are stated in detail.

Study and Application of a New On-Line Titration Technique

A new on line titration method and device based on a new technique continuous flow titration is described. By the means of electronically controlled switching of a solenoid valve, the main component of the system, the equivalent point of the titration is easily determined. Several kinds of mixing tools were examined, whereby a self made mixing chamber with minimum volume gave best results and was therefore used in the device. The error of the titration is within 0.2% and the relative standard deviation (RSD) is below 1.2%. The results show no difference compared with a commercial device, meanwhile the new on line titration system is cheaper and fully automated and thus easy to hand and less solvent consumption.

关于《On right continuity of a family of two-parameter σ-fields》一文若干问题的探讨

探讨《Ｏｎｒｉｇｈｔｃｏｎｔｉｎｕｉｔｙｏｆａｆａｍｉｌｙｏｆｔｗｏ－ｐａｒａｍｅｔｅｒσ－ｆｉｅｌｄｓ》（刊登在杂志ＳｔｏｃｈａｓｔｉｃＰｒｏｃｅｓｓｅｓａｎｄｔｈｅｉｒＡｐｐｌｉｃａｔｉｏｎｓ，１９９７，６６：１０７～１１３）所讨论的问题，指出该文主要命题的证明推导过程存在实质性错误．

基于主线不停运的城轨支线独立运营改造方案

研究目的:针对大型铁路枢纽接入已运营轨道交通线路引起的既有线改造问题,为满足铁路枢纽与轨道交通连接线(支线)施工期间主线正常运营不受影响,对改造涉及的运营组织与接轨方案进行系统研究,并对土建、轨道、接触网、环网与动照、信号、综合监控与通信系统等的改造及影响进行深入研究,在统筹考虑实施难度、投资与工期的基础上,提出实施风险最小、技术最合理的改造方案。研究结论:(1)既有高架车站与区间改造影响范围较小且相对可控,可以实现主线正常运营情况下新建独立运营支线工程;(2)为最大程度保障主线运营不受影响,在现有技术水平条件下,应尽量避免在运营天窗期进行各类信号光电缆的割接;(3)支线独立运营方案,应尽量采取措施将新建支线与主线相连、轨道相通,以利于车辆检修与维保,并增加运营的灵活性;(4)桥梁浇筑与平移施工临近既有线,实施阶段应进一步完善工艺衔接与交叉施工统筹,增加既有线安全保障;(5)本研究结论可为类似工程提供参考。

桥梁预拱度对行车舒适性的影响及桥面线形调整

为研究成桥预拱度对连续刚构桥行车舒适性的影响,以多座主跨跨径为110~200 m的连续刚构桥为研究对象,首先,采用滤波白噪声法建立桥面时域模型,并与按余弦曲线设置的成桥线形叠加模拟成桥后的桥面不平度;其次,采用MATLAB/Simlink搭建车辆-桥面系统模型,以加速度均方根值(RMS)作为桥梁边跨、中跨桥面的行车舒适性评价指标,以最大瞬态振动值(MTVV)作为边跨峰值处短时内的行车舒适性评价指标;最后,分析采取经验法按照余弦曲线设置成桥预拱度的桥梁其跨径和设计时速对边、中跨RMS值的影响,以及成桥预拱度取值对边跨3L/8处MTVV值的影响。研究结果表明:在边跨、中跨处RMS值均小于0.315 m/s^(2),说明采取经验法按照余弦曲线设置成桥预拱度并不影响中跨处的行车舒适性;在边跨3L/8处MTVV值在短时内存在大于0.345 m/s^(2)的情况,说明在边跨峰值处短时内会产生一定不舒适感。提出了一种基于桥面铺装层施工优化边跨3L/8处和边墩墩顶桥面线形的方法,改善了边跨的行车舒适性。

大型连续绿茶精制加工生产线研发

茶叶加工技术与装备是茶叶产业发展的基础,对行业发展起着举足轻重的作用。为实现绿茶加工机械自动化生产,设计了大型连续绿茶精制加工生产线,阐述了该生产线系统结构、主要生产环节及安装调试应用。基于PLC控制的大型连续绿茶精制加工生产线,主要由鲜叶上料输送机、大型滚筒杀青机、冷却回潮机、四机协同联动式揉捻机组、并列连续预烘干机组、储料仓、计量分料装置、茶叶炒干与抛光机组、筛分装置、风选装置及配套的测控系统等组成。针对绿茶加工工艺的各个环节,采用模块化设计,根据茶叶加工企业的厂房实际情况,灵活安装组线,满足企业个性化需求。基于模糊PID温度控制的大型滚筒杀青机双模糊控制技术,解决了传统杀青温度与时间无法实现精确控制的难点问题。采用链式刮板输送智能加料装置与多机联动协同连续揉捻控制技术,实现多机协同联动式自动加料连续揉捻,边进料边揉捻,揉捻均匀度高。生产线上杀青机、理条机和烘干机各环节温度采用模糊PID控制,解决了茶叶加工温度、投叶量与杀青、理条、烘干时间实时配合的问题,输入不同等级、不同重量的鲜叶可输出相适应的杀青温度和时间,实现对茶叶生产过程的精确控制,减少人为因素的干扰,实现绿茶的智能化生产。近年来,生产线用户遍布皖、苏、浙、云、贵、川、豫、湘、鄂和陕等10多个省份200余家茶叶生产企业。该生产线的推广应用,实现了茶叶规模化生产,保证了茶叶品质,对茶产业发展具有重要意义。

组群贯通供电方式牵引变电所进线继电保护方案研究

针对组群贯通供电,分析其牵引变电所电源进线牵引侧的故障类型和继电保护配置。对于进线牵引所侧来说,当发生各种类型短路故障时,电网侧提供的短路电流受到牵引变压器限制;通过接触网绕送的短路电流受到接触网阻抗限制,牵引侧的短路电流一般较小。进线发生各种单相和相间短路,差动保护均能启动。如果无法安装纵联差动保护,当单相牵引变压器连接在电源进线AB相间时,应配置低电压启动的A相和B相功率方向保护,其中A相功率参考正方向由牵引变压器指向进线;B相功率方向参考正方向由进线指向牵引变压器。

基于主应力轨迹线的连续碳纤维复合材料3D打印路径规划方法

连续碳纤维复合材料3D打印成型零件的力学性能对纤维的铺设方向有需求,传统的路径规划方法基于零件的形状轮廓进行填充,不能满足零件的实际使用性能。针对这一问题,提出基于主应力轨迹线的连续碳纤维复合材料3D打印路径规划方法。基于连续碳纤维复合材料三维模型的有限元分析数据,通过材料力学计算得到相应的主应力轨迹线;通过连续碳纤维复合材料3D打印的打印参数对得到的主应力轨迹线进行调控,保证每一条轨迹线之间的间距契合3D打印要求;通过坐标变换调整有限元分析坐标系以及打印机坐标系;通过以上调控生成用于连续碳纤维复合材料3D打印的G code规划文件。通过路径规划仿真对比和打印拉伸实验,基于主应力轨迹线生成的连续碳纤维复合材料3D打印路径比传统直线碳纤维复合材料3D打印路径性能提高了4.5%,验证了基于主应力轨迹线的连续碳纤维复合材料3D打印路径规划方法的有效性。

大吨位连续梁上跨既有铁路转体施工技术研究

为解决既有铁路线上跨新建大吨位连续梁上转体施工难题,以京滨铁路JBSG–3标段连续梁为例,对上跨既有铁路线(大北环铁路)的转体施工难点及要点进行总结,该大北环铁路两侧转体桥梁重达7 700 t,并与大北环铁路相交交角为54°11',由于转体桥梁自重大及大北环铁路线繁忙、天窗时间短,现场转体施工难度极大。拟定采取水平转体法+球铰系统进行桥梁转体施工,通过现场严格控制球铰安装精度、梁体准确称重及配重、试转优化、转角刻度及梁面轴线对转体位置双控等多重措施并行,最终在48 min内安全、可靠、精准地完成既有铁路线两侧梁段的转体施工。

A filtering-based bridge weigh-in-motion system on a continuous multi-girder bridge considering the influence lines of different lanes

A real-time vehicle monitoring is crucial for effective bridge maintenance and traffic management because overloaded vehicles can cause damage to bridges,and in some extreme cases,it will directly lead to a bridge failure.Bridge weigh-in-motion(BWIM)system as a high performance and cost-effective technology has been extensively used to monitor vehicle speed and weight on highways.However,the dynamic effect and data noise may have an adverse impact on the bridge responses during and immediately following the vehicles pass the bridge.The fast Fourier transform(FFT)method,which can significantly purify the collected structural responses(dynamic strains)received from sensors or transducers,was used in axle counting,detection,and axle weighing technology in this study.To further improve the accuracy of the BWIM system,the field-calibrated influence lines(ILs)of a continuous multi-girder bridge were regarded as a reference to identify the vehicle weight based on the modified Moses algorithm and the least squares method.In situ experimental results indicated that the signals treated with FFT filter were far better than the original ones,the efficiency and the accuracy of axle detection were significantly improved by introducing the FFT method to the BWIM system.Moreover,the lateral load distribution effect on bridges should be considered by using the calculated average ILs of the specific lane individually for vehicle weight calculation of this lane.

城际铁路跨线连续梁转体设计及施工技术分析

转体施工技术是跨线连续梁施工的常用方法,具有施工过程安全、对既有铁路运营影响较小的优势。文中以如通苏湖城际铁路跨线转体连续梁建设工程为例,阐述转体结构设计,依次分析连续梁转体结构施工关键技术,从转体体系施工、称重配重、转体施工等方面总结跨线转体连续梁墩底转体施工技术重难点,为跨线转体桥施工提供参考。

A PRODUCTION-INVENTORY SYSTEM WITH AN UNRELIABLE CONTINUOUS TRANSFER LINE

This paper extends a production-inventory model with one unreliable machine to one that hasn machines in series, separated by finite buffers. It is shown how customer service levels and otherperformance measures can be calculated as a function of the availabilities of the machines and thesizes of the intermediate buffers.

连续梁桥影响线识别与承载能力快速评估试验研究

针对桥梁静载试验过程存在的重载静置、交通阻误等问题,利用桥梁影响线具有完整反映结构各截面抗弯刚度的优势,提出一种基于影响线的桥梁承载能力快速评估方法。该方法仅利用单辆重车移动加载获取包含桥梁影响线信息、结构动力成分和车辆多轴效应的桥梁时程响应,首先采用变分模态分解剥离桥梁时程响应中的动力成分;其次根据采样频率及车辆轴距构建桥梁影响线识别数学模型,从而剔除桥梁时程响应中的车辆多轴效应,利用Tikhonov正则化解得桥梁影响线的稳定解;然后通过在桥梁影响线上开展虚拟加载,重构桥梁虚拟静力响应,并采用传统校验系数法评价桥梁承载能力。通过三跨变截面连续梁桥数值算例验证影响线识别方法的有效性,建立误差指标定量评价影响线识别结果的准确性,从而对某三跨连续钢混组合梁桥开展静载试验与承载能力快速评估试验研究,在预设车道实施车辆移动加载,识别桥梁中跨跨中截面挠度、应变影响线,进而开展虚拟加载研究,进一步验证所提承载能力快速评估方法的可行性与实用性,为桥梁承载能力“轻量化”快速筛检提供方法支撑与案例借鉴。

连续酸洗机组7.0~8.0 mm厚规格酸洗产品拓展实践

近年来应用户需要,某连续酸洗机组开展了屈服强度350 MPa以下、厚度7.0~8.0mm、宽度800~1300 mm酸洗板拓展试验.通过对现有设备能力负荷计算、开展取样离线样板焊接验证以及多轮通板生产验证,确定了该机组具备7.0~8.0 mm厚规格酸洗产品的生产能力.经过生产验证,该机组生产稳定,无异常问题,7.0~8.0mm厚规格酸洗产品质量达到用户要求.

铝带连续退火机组设计与关键设备配置

文章结合某2350 mm铝带连续退火机组,对铝带连续退火机组的主要工艺参数、机组设备组成、关键设备要点等进行论述,以达到合理方案配置。

市域快线轨道技术标准和设计方案探讨

当前市域快线发展迅猛,但在轨道系统设计方面尚未形成统一的标准。文章通过分析市域快线轨道系统的特点,并与城际铁路和地铁进行差异对比,对影响线路平顺性和乘坐舒适性的关键技术标准进行研究,对市域快线轨道设计中应重点关注的内容进行综合论证,并提出设计建议如下:为保证线路的高平顺性,曲线超高、轨道铺设精度、土建沉降控制应尽量采用与城际铁路一致的技术标准;线路应优先采用长定尺钢轨;地下线和高架线宜优先选用无砟轨道;无缝线路宜采用全焊接方式;轨道减振措施应保证线路的稳定性和平顺性。此外,建议市域快线轨道设计还应重点关注不同速度区段车辆与线路条件的匹配,以避免轮轨异常磨耗等病害。

铁路隧道二衬纵向连续灌注施工技术研究

铁路隧道纵向灌浆施工通常是在隧道顶部预留垂直灌浆孔进行砼注入,易出现背后脱空、厚度不足和不密实等衬砌质量缺陷。为了解决上述技术难题,依托格莱村隧道工程,阐明了隧道纵向灌注施工工艺原理,梳理了施工关键技术,并结合现场实际施工效果和有限元数值模拟进行技术验证。结果表明:采用旋转式灌注孔堵头封堵装置,实现了退枪过程的带压封堵,确保了顶拱浇注的密实性;采用顶位水平连续后退漫淹式纵向连续灌注技术,使混凝土在重力作用下自流填充均匀密实,解决了传统工艺存在的厚度不足和脱空技术难题;数值模拟结果显示二衬各截面安全系数均大于规范值3.6,进一步验证了二衬纵向连续灌注施工技术的安全可行性。

浅析四篇关于门阀士族的研究名作

魏晋南北朝时期是以门阀士族为中心的时代,门阀士族是魏晋南北朝时期的一个重要统治阶层。门阀士族的形成、发展及其衰落是魏晋南北朝史研究的重要课题。唐长孺、胡如雷、韩昇、严耀中四位学者对此各抒己见,虽观点与侧重点各有不同,但又存在一脉相承、相互启发的关系。梳理他们的四篇名作,对于史学研究具有重要意义。

广角大断面连续截割工艺的创新与实践

传统综掘机受机身长度和运输联结装置影响,在大断面截割作业时,经常出现机体转载点落煤偏移和二运皮带偏离轨道现象,给安全带来隐患。针对这一问题,本文以冀中能源峰峰集团牛儿庄采矿公司为例,将综掘机运输联结装置进行加长、调高等一系列改进,使综掘机在进行拐线掘进时可自由调整前进角度、方向,机体可直接进入拐线巷道进行截割生产作业,实现了综掘机机体、运输皮带同轴自由旋转,保证了机体大幅广角摆动截割连续作业,解决了机体摆动受限、转载点运输掉煤砟、机体皮带掉道等系列问题。