基于频域可变的大型钢结构钢板腐蚀电磁检测仪器的开发

钢板腐蚀是大型钢结构失效的主要原因之一.钢板构件往往面积巨大,且由于密闭空间或附属结构,使得单一检测方式难以完成有效检测.在分析漏磁检测、电磁超声检测和电磁超声导波检测技术特点及检测机理的基础上,提出基于频域可变的电磁检测理念.优化漏磁、电磁超声测厚和导波检测传感模块,实现三种检测模块的一体化设计,开发复合检测传感器.针对三种检测方法信号激励和采集的特点,研发一体化电路,开发了基于频域可变的电磁检测试验平台.针对不同工况需求,开发了储罐底板腐蚀在油检测仪和系列自动爬行电测检测仪.通过现场成功应用,验证了基于频域可变的电磁检测技术的有效性和巨大应用潜力.     

压力容器焊缝及其附近微裂纹的检测

压力容器安全运行是一项十分重要的安全工作,因此,加强压力容器焊缝及其附近微裂纹的检测就显得尤为重要.无损检测技术的应用在压力容器制造过程中显得十分重要,常规无损检测技术主要有:射线检测、超声波检测、渗透检测、涡流检测、磁粉检测.本文首先阐述了常用的无损检测方法及应用.其次,对压力容器焊缝及其附近微裂纹检测特点及步骤进行了深入的探讨,得出以下结论:只采用一种无损检测方法来检测压力容器焊缝及其附近微裂纹,无论那种检测方法如何的先进,如何的高效,进检测结果必然会存在很多局限和疏漏,容易造成漏检.压力容器焊缝及其附近微裂纹的检测应该综合运用各种无损检测方法,相互取长补短,做到合理科学地结合检测的压力容器实际情况来运用各种检测手段,确保压力容器安全运行.     

几种边缘检测算子的性能比较研究

边缘检测是图像处理和计算机视觉中的重要的环节.文章具体考察了7种常用的边缘检测算子.根据实验结果对其特点和性能进行了比较研究.分析了各种边缘检测算子的特点,以及在处理各种噪声时,对各种边缘检测算法的检测效果进行了分类比较.在对各种图像进行边缘检测时,为选择检测算子提供指导.     

一种块-点的分层自适应运动检测算法

本文提出了一类块检测-点检测的分层运动检测方法,在现有背景模型的基础上建立块模型进行粗检测,然后对检测出的块进行点检测,达到提高检测速度的目的.为了兼顾检测速度和精度的要求,构造目标函数,根据检测到的目标尺度对块-点尺寸做了自适应优化.实验证明了这种方法的有效性.     

车速检测系统的虚拟设计及应用

汽车速度检测是汽车安全检测项目的重要组成部分,在当前检测实践中,对于后置后驱、车速信号取自前轮的汽车,由于测试时由滚筒带动车轮转动,滚筒与车轮间存在的滑移情况未被考虑.致使车速检测结果产生较大误差.针对这种情况,基于虚拟仪器开发了车速检测系统.克服了传统车速检测原理的不足,应用于检测实践中,效果良好.     

基于交变漏磁的裂纹检测系统

交变漏磁检测技术结合了涡流检测和漏磁检测的优点,它可以实现对铁磁性材料表面裂纹的准确检测.文中介绍了交变漏磁检测的原理以及裂纹检测系统的软硬件设计.通过试验研究,依据检测的两路信号及其构成的缺陷环图,可以实现对裂纹缺陷的检测.     

一种基于分簇式双门限合作频谱检测算法

认知无线电作为一种未来解决频谱匮乏技术,获得了广泛的研究.频谱检测技术是认知无线电技术中关键技术之一.针对目前单点检测正确率低下的问题,结合目前深入研究的合作频谱检测技术,提出一种新的基于分簇式双门限的合作频谱检测算法.该检测算法通过设立双门限进行检测,并根据不同簇的检测能力不同引入信誉值进行二次数据融合.仿真结果表明该算法能够有效降低误警率和漏检率,提高了整体的检测性能.     

带有BA功能的汽车真空助力器性能检测装置研究

通过对带有刹车辅助(BA)功能的真空助力器结构的研究,在以往真空助力器检测台的基础上,研制出了带有BA功能的真空助力器性能检测装置.检测装置的设计包括硬件部分和软件部分.硬件部分包括检测台机械部分、控制部分、数据采集部分、驱动和连接部分等.软件部分是检测台的核心,采用Delphi作为编程语言,编制人性化操作界面,针对带有BA功能的真空助力器的特性,设置对应的检测项目.通过试验对该检测装置进行了验证.     

内花键棒间距检具的研制与应用

花键类产品是广泛应用于机械设备中的基础元件,主要起着联接及传递扭矩的作用.花键的检测是花键产品生产中的重要环节.一般来说,外花键的检测相对容易一些,而内花键的检测难度较大.以前,我公司在生产现场大多采用量棒及游标卡尺等传统量具来检测控制内花键齿槽宽用的棒间距,检测速度慢,检测精度低,难以满足高精度、大批量花键生产的检测要求.为此,很有必要研制开发一种检测精度高、操作方便快捷、成本低廉的专用内花键棒间距检具.     

具有补偿功能的线阵CCD辊型检测系统

设计了一种用于轧辊辊型非接触式检测的CCD传感系统,阐述了系统的检测原理、组成与检测过程.根据激光-线阵CCD检测技术原理,采用梯度强度均值法对检测信号进行处理,有效减小了噪音对成像质量的影响.利用插值法和数值滤波法处理数据,有效降低轴承振动和随机噪声的影响,提高了处理数据的速度.对辊型检测过程中易出现的轴线偏移现象,从垂直检测平面和平行检测平面2个方向采取补偿措施,有效地提高了系统检测精度.实验证明,系统的精度达到了实际生产过程辊型检测的要求,是一种快速、高精度的辊型检测方法.     

Modeling of on-line measurement for rolling the rings with blank size errors in vertical hot ring rolling process

The size errors of the ring blanks have a considerable effect on the vertical hot ring rolling process and the ring products’ dimensional precision. In this paper, the geometric relationship between the ring’s outer diameter and the measuring roll’s displacement is studied, and then, the influence of the blank size errors on this geometric relationship is analyzed. Subsequently, a modeling method of the measurement model for vertical hot ring rolling process is proposed, that is, the ring’s outer diameter can be measured indirectly through the relations of the ring’s outer diameter with respect to the measuring roll’s displacement and the ring blank’s outer diameter. Using this modeling method, the on-line measurement model of a certain type of vertical hot ring rolling mill was established, and the verification experiments were also conducted. The experiments showed that this on-line measurement model could calculate the ring’s outer diameter precisely, and the absolute errors of the formed rings were less than ±1.5 mm. The research results of this paper have general significance for the on-line measurement and process control of vertical hot ring rolling process.     

A modified Hertzian foil rolling model: approximations based on perturbation methods

Fleck and Johnson (Int. J. Mech. Sci. 1987;29:507) have developed a foil rolling model, which has been used subsequently as a temper rolling model, based on a modification of the Hertzian contact problem. It removes the restrictive assumption that the rolls remain circular in profile. A perturbation approximation of the Fleck and Johnson model equations for small reductions has been developed. This enables good approximations to the roll torque and roll force to be obtained in a small fraction of the time required for the full iterative solution and has potential for use in on-line control.     

测头半径对 1 级渐开线样板齿廓偏差测量的影响

按齿轮渐开线样板国家标准推荐,1 级齿轮渐开线样板的齿廓形状偏差需从展开长度 3 或 5 mm 开始计值,齿根部非计 值区间对应渐开线弧长仅为 0. 03~ 0. 18 mm,导致 1 级齿轮渐开线样板齿根部的渐开线齿廓难以精确测量。 为了能更好发挥 1 级齿轮渐开线样板的量值精准传递作用,分析了 1 级齿轮渐开线样板结构的特殊性以及测头半径对渐开线齿廓偏差测量结果 的影响,结果表明,在齿根展开角误差时,测头半径引入的测量误差会随着测头半径的增大而增大,并随着展开长度的减小而增 大,在基圆附近的测量误差可以达到齿廓偏差的 50% ~ 200% ;当仅渐开线齿面存在加工误差时,测头半径引入的测量误差和展 开长度受影响的范围会随着测头半径的增大和被测渐开线基圆半径的增大而增大,在齿根部展开长度 10% 的范围内测量误差 约齿廓形状偏差的 10% ~ 60% 。 通过选取测头半径 rp = 0. 5 和 2. 5 mm 的测头对同一齿轮渐开线样板验进行了测量实验验证了 上述结论。 研究为 1 级齿轮渐开线样板的精密制造、精密测量及使用展开长度区间选取提供了支持。     

立式轧环机轧制中环件运动学规律

提出在轧制过程中环件中心不在芯辊和驱动辊中心连线上的轧制几何模型，并基于此模型导出环件中心位移、速度、加速度、环件转动惯量及转速和转动加速度的计算公式，建立了环件的运动学参数与环件壁厚和轧制进给量之间的关系，为环件轧制过程的在线测量和控制提供理论依据。     

Experimental study for roll gap adjustment due to roll wear in single-stand rolling and multi-stand rolling test

To investigate a correlation between the amount of wear and roll gap (pass height) adjustment, we performed a single-stand reversible pilot groove rolling test as well as rolling test in an actual rod mill. In case of the pilot rolling test, we designed wear contour (profile) and machined it on the original roll groove (i.e., roll groove with no wear) to make the roll groove worn down. For the actual rod mill test, we developed a measuring device which can detect the actual wear profile. To determine the amount of roll gap adjustment, we propose a model for equivalent roll gap decrement which reduces the increased exit cross sectional area due to wear. We applied the proposed model to multi-stand rolling (roughing train of POSCO No. 2 Rod Mill) as well as single-stand reversible rolling. The wear profile of rolls worn down at each stand in mill yard was measured at different roll tonnage. The pilot hot rolling test shows that variation of exit cross sectional area is almost linearly proportional to roll gap change while the roll gap decreases from reference roll gap (6.5mm) to 3.5mm. In an actual rod mill which has consecutive rolling system, relationship between tonnage (total amount of tons that the produced rod weighs) and roll gap change at a stand is dependent on the rolling type (oval-to-round or round-to-oval) together with the cross sectional shape of incoming workpiece.     

Control Scheme Using Forward Slip for a Multi-stand Hot Strip Rolling Mill

Forward slip is an important parameter often used in rolling-speed control models for tandem hot strip rolling mills. In a hot strip mill, on-line measurement of strip speed is inherently very difficult. Therefore, for the set-up of the finishing mill, a forward slip model is used to calculate the strip speed from roll circumferential velocity at each mill stand. Due to its complexity, most previous researches have used semi-empirical methods in determining values for the forward slip. Although these investigations may be useful in process design and control, they do not have a theoretical basis. In the present study, a better forward slip model has been developed, which provides for a better set-up and more precise control of the mill. Factors such as neutral point, friction coefficient, width spread, shape of deformation zone in the roll bite are incorporated into the model. Implementation of the new forward slip model for the control of a 7-stand hot strip tandem rolling mill shows significant improvement in roll speed set-up accuracy.     

基于辊缝动力学的板带轧机垂直振动的研究

板形与板厚是衡量板带轧制成品几何精度的两大指标。而与这些指标直接相关的是轧机机座垂直方向的振动。本文将机座与轧件作为一个系统来研究 ,建立了基于辊缝动力学的 ,以分析板带轧机机座垂直振动对板形及板厚影响为目的辊缝动力学模型 ,提出了振动模态对板形及板厚影响的指标。得出的结论是 :板形与板厚控制的实质是辊缝的控制 ,在轧制状态下辊缝不仅与静力学因素有关 ,而且在很大程度上取决于辊缝动力学因素。本文所建立的模型考虑了阻尼因素及由辊缝动力学模型确定的非线性轧制力 P,使模型能更真实的模拟现场实际情况     

Study on the improved accuracy of strip profile using numerical formula model in continuous cold rolling with 6-high mill

The quality requirements for thickness accuracy in cold rolling continue to become more stringent. In cold rolling mill, it is very important that the rolling force calculation considers rolling conditions. The rolled strip thickness was predicted using calculated rolling force. However, the prediction of strip thickness in cold rolling is very difficult; in particular, for 6-high mill with shifted intermediate roll (IMR), the accuracy of thickness is not good. In this study, to improve the accuracy of rolled strip thickness, the roll gap flattening can be given based on Hertz contact theory, with contact between rolls and the smooth cylindrical rolls for the rolling elastic deformation. Also, the distribution of the roll gap flattening may be calculated using the contact force of unit transverse length. The strip profile at the continuous cold rolling is calculated by using the numerical analysis model considering the initial strip profile before cold rolling. Hence, we propose that the numerical model can predict the rolled strip profile more quickly and accurately and be applicable to the field. The results of the proposed numerical model were verified by FE-simulation and cold rolling experiments of 6-high mill with five stands.     

Analysis of flow and stresses in a tube stretch-reducing hot rolling schedule

Analytical expressions for the roll-pass geometry, velocity, strain, strain rate and stress components are obtained for steady-state tube stretch-reducing hot rolling. From these expressions the reduction in tube diameter and wall thickness, inter-stand tensions, roll load and rolling torque have been determined in relation to the roll gap opening and the inter-stand velocity increase ratio. The results have shown that increasing the interstand velocity increase ratio will increase the inter-stand tension while the roll load remains almost unchanged. The rolling torque increases with the increase of the back inter-stand velocity increase ratio and decreases with the increase of the ratio at the front. There is a limiting value for the inter-stand velocity increase ratio at which the rolling process will tend to become unstable. The analysis has been validated by comparing the theoretical results with on-line power measurements on an industrial tube stretch-reducing hot rolling mill.     

Mechanics of roll edge contact in cold rolling of thin strip

Simulation of cold rolling of thin strip due to roll edge contact with oil lubrication was performed successfully using a developed influence function method. Roll edge contact and related surface roughness was discussed in this paper. The calculated rolling force, intermediate force and work roll edge contact force increase significantly when the reduction increases. The strip profile becomes poor with a higher reduction, and the calculated rolling forces are consistent with the measured values. A modified edge shape of work roll determined from the roll edge contact length and roll edge flattening value is helpful to reduce the work roll edge wear and to extend the work roll life. Surface roughness and asperity of the rolled strip are characterized by surface profilometer and atomic force microscope. The research shows that the surface roughness reduces with a higher reduction or rolling speed. The effect of the strip width on surface roughness is not significant.