热镀锌钢板锌流纹缺陷成因分析与消除方法

分析了热镀锌带钢表面锌流纹缺陷的产生原因及其影响因素,包括带钢与气刀之间的振动、气刀调整参数、带钢运行速度、锌液成分、带钢入锌锅温度、带钢出锌锅后表面的粗糙度等.介绍了消除锌流纹缺陷的方法及其应用效果.     

粗轧铜带"振纹"的分析

粗轧铜带时 ,在带材表面上产生振纹。作者对振纹现象进行了测试、试验并对振纹现象进行了分析 ,找出了解决问题的方法     

连续退火板表面鱼鳞纹缺陷形成机理分析及改进措施

采用扫描电镜及聚焦离子束分析对连续退火板表面鱼鳞纹缺陷的形貌及微观组织进行了分析。结果表明,鱼鳞纹缺陷的实质是一类表面微擦伤,其形成机理是因板温计水冷套漏水,导致带钢表面在高温下形成局部氧化,氧化部位在带钢张力作用下与炉辊辊面形成微擦伤。通过聚焦离子束技术在缺陷处沿截面切开后观察到组织中有大量纳米级亚晶结构的形成,证实了带钢表面受急冷并氧化的推断。微观组织分析结果为缺陷的现场排查和解决提供了理论依据。     

液压衬板技术在宝钢CM04机组平整机上的应用

平整机在加工带钢过程中,由于轧机振动,带钢表面经常产生“振痕”。宝钢采用液压衬板技术,减少带材“振痕”。使用二年,满足了汽车板用户的要求。     

Analysis and Treatment of Finishing Mill Stand Oscillation of FTSR in BX STEEL

本钢FTSR精轧机F2机架在轧制厚度规格小于2.5mm时经常出现较强振动,尤其是轧制1.6mm薄规格集装箱板,机架振动更明显.振动不仅使该机架上的机械设备受到影响,机架振动严重时导致带钢表面出现振纹,下机轧辊出现横向的不均匀磨损,造成产品质量缺陷,并且机架的振动伴有高分贝的噪音,严重影响生产顺行.     

极薄带钢冷轧过程振动纹成因分析及抑制

本文针对0．18mm极薄规格巧料的振动纹问题,从理论上分析了带钢厚度、轧制速度、辊缝中摩擦系数、带钢张力以及轧制润滑条件对冷轧过程自激垂直振动的影响。通过优化轧制工艺参数和调整乳化液性能指标,成功解决了1420mm冷连轧机900m／min左右高速轧制T5料时第5机架的振动问题,抑制了带钢表面振动纹的产生。     

光整延伸率对烘烤硬化钢180BD+Z表面波纹度的影响

对烘烤硬化钢180BD+Z镀锌后进行了不同光整延伸率的处理,研究了光整延伸率对其表面波纹度的影响。结果表明,随着光整延伸率的增加,带钢表面的波纹度值先降低后增加,降低是由于光整消除了锌流纹等表面缺陷,而随着光整量的进一步增大,光整辊的波纹度向带钢表面复制占主导因素,带钢波纹度增大。光整延伸率为1.4%时,180BD+Z带钢表面波纹度值最优。此外,试验得出冲压后带钢波纹度增大的因素主要来自其锌层的变形。     

热轧带钢尾部横裂纹形成原因分析

针对邯宝钢铁公司热轧带钢尾部上表面出现横裂纹现象,进行了金相检验,发现裂纹根部无扩展,裂纹两侧组织存在差异,结合现场生产实际,确定横裂纹的产生与中间坯尾部局部过冷有关。从而采取提高板坯出炉温度和板坯尾部温度、严格控制中间坯尾部翘头和除鳞制度的措施,基本杜绝了带钢尾部横裂纹现象。     

热轧宽带钢生产疑难问题及对策

介绍了热轧宽带钢生产中常遇的关键问题及解决办法。从宽带钢板形、内应力、冷弯型纹及板带表面缺陷等几个方面进行了分析,并提出了相应的对策和解决办法。通过对各种影响因素的合理控制,可改善热轧宽带钢的板形及性能,提高市场的竞争力。     

非下采样Contourlet变换在带钢表面缺陷图像去噪中的应用研究

目的对带钢表面图像中的噪声进行有效滤除,以获取较清晰的带钢表面图像,为通过带钢表面图像检测带钢表面缺陷提供良好的源图。方法利用非下采样Contourlet变换具有精细分解的特性,对获取到的带钢表面图像进行尺度分解,获取图像的高、低频系数。在最大后验概率框架的基础上,以噪声图像系数的方差为判断条件,构建了自适应去噪模型,对带钢图像进行前级去噪。为了进一步去除带钢表面图像中的噪声,利用非局部均值方法对前级去噪后的带钢表面图像进行处理,以达到对带钢表面图像中的噪声进行有效滤除。结果仿真实验结果显示,与对照组方法相比,采用所设计方法去噪后的带钢表面图像不存在阶梯效应等不足,具有更高的峰值信噪比及结构相似度。结论本文所提方法能有效去除带钢表面图像中夹杂的噪声,可获取较清晰的带钢表面图像。     

冷连轧机带钢表面振纹实测研究

针对某厂2180mm冷连轧机在轧制汽车面板时出现的振纹问题,进行了现场连续综合测试.基于对轧制周期内振动信号的分析、比较,掌握了该轧机的振动特征和振动形态,确定了轧机的起振次序.结合轧机的机械固有特性,找到了导致轧机振动的主要来源,即减速机中齿轮1和齿轮2的啮合冲击,据此提出了振纹的抑制措施.生产实际表明,抑振措施对振动及振纹的消除具有较好效果.     

Process monitoring to assist the workpiece surface quality in machining

The paper reports on research which attempts to correlate the quality of the machined surface after broaching and the output signals obtained from multiple sensors, namely acoustic emission, vibration, and cutting forces. The quality of the machined surface was estimated in terms of geometrical accuracy, burr formation, chatter marks and surface anomalies. Cutting conditions were varied based on an orthogonal array with cutting speed, coolant conditions, and tool settings as factors. Each orthogonal array was repeated at three levels of the tool wear.The results show that the cutting force signals are sensitive enough to detect the geometrical deviation of the machined profile, burr formation and to a lesser extent the chatter marks. The vibration signals were found sensitive to detect the chatter marks while the acoustic emission signal proved to be efficient for the detection of small surface anomalies such as pluckings, laps, and smeared material. However, up to now, no clear distinction between the different types of the surface anomalies could be made using the analysis of the acoustic emission signal.Time and frequency domain analysis of the output signals were carried out in order to develop appropriate techniques for qualitative/quantitative evaluation of the machined surface quality.It was found that each sensory signal is rather limited to a narrow field of application where certain surface features are detectable. The limitations of the employed sensory signals/analysis methodologies used to assess the workpiece surface quality, and their applicability in the industrial machining conditions are also discussed.     

轧机工作辊磨削振纹检测与控制

研究分析轧辊磨削振纹产生原因,通过对设备、砂轮、磨削工艺、操作等方面进行改进优化,研制了专用的辊颈振纹检测方法和分级控制规则,有效控制了磨削振纹的产生。     

Magnetorheological fluid-controlled boring bar for chatter suppression

An innovative chatter suppression method based on a magnetorheological (MR) fluid-controlled boring bar for chatter suppression is developed. The MR fluid, which changes stiffness and undergoes a phase transformation when subjected to an external magnetic field, is applied to adjust the stiffness of the boring bar and suppress chatter. The stiffness and energy dissipation properties of the MR fluid-controlled boring bar can be adjusted by varying the strength of the applied magnetic field. A dynamic model of a MR fluid-controlled boring bar is established based on an Euler–Bernoulli beam model. The stability of the MR fluid-controlled boring system is analyzed, and the simulation results show that regenerative chatter can be suppressed effectively by adjusting the natural frequency of the system. Experiments in different spindle speeds utilizing a MR fluid-controlled boring bar are conducted. Under a 1 Hz square wave current, chatter can be suppressed, as evidenced by the elimination of chatter marks on the machined surfaces and the reduction in the vibration acceleration at the tip of the boring bar.     

Chattering detection in cylindrical grinding processes using the wavelet transform

This paper presents a technique for chattering detection on ground cylindrical parts. Chattering is a defect caused by vibration during the grinding process and is best described as waviness in the surface of a workpiece. In this work, such waviness is measured with a mechanical stylus profiler featuring a diamond tip, and then converted into height values with the help of a precision displacement transducer. The output signal is later converted to digital form and transformed to the time–frequency domain by means of the wavelet transform, allowing its coefficients to grow as a function of surface defects and highlighting chatter marks. The method was validated experimentally with actual production parts and it was found to adequately measure the amplitude and to give location information of the chatter marks on the analyzed surface. Results show that this method can be used objectively to identify and quantify surface quality and that it is feasible to effectively integrate it into production processes for manufacturing control.     

Low vibration control system in turning

This paper presents a system developed for on-line vibration control on a CNC lathe. The on-line vibration control system is composed of two subsystems, namely, the vibration monitoring subsystem, and the vibration reduction subsystem. A simple chatter criterion was adopted in the vibration monitoring subsystem in order to detect the occurrence of chatter as soon as possible. The vibration reduction subsystem is then triggered to suppress vibrations when chatter was detected. It was shown that chatter can be detected by comparing the standard deviation of signal collected on-line to an off-line experimentally determined value. The vibration reduction subsystem provides possible ways to reduce vibrations by adjusting cutting parameters including cutting speed and feed rate. Series of experimental tests were conducted to verify the feasibility of the proposed system. It was shown that the proposed system can generally detect the occurrence of chatter and reduce vibrations effectively when chatter occur.     

基于小波包分解和奇异谱分析方法的立铣加工颤振监测

在立铣加工过程中,颤振是加工过程失稳的一个最重要的原因。颤振将会严重影响工件表面质量和材料去除率,加剧刀具磨损和恶化工作环境。虽然大部分颤振监测系统可以监测到颤振发生,但颤振发生时已经对工件和刀具产生了严重的损伤,因此,需要提前监测到颤振特征。在颤振发生过程中,振动信号具有在时域中不断增大,在频域中能量频移的特性。考虑这两个振动信号特征,提出了一种颤振特征提取方法。提取颤振发生频带中振动信号的能量比和奇异谱熵系数作为两个颤振特征,并通过人工神经网络模型实现切削颤振的识别。文中提出的颤振监测系统包括特征提取和分类,能够精确辨识立铣加工中的稳定、过渡和颤振状态。     

Experimental research on cutting force variation during regenerative chatter vibration in a plain milling operation

A plain milling operation is characterized by a transient and intermittent cutting process, in which undeformed chip thickness varies continuously. The reverse is the case in variations of undeformed chip thickness in the processes of up- and down-milling. In the present study, the property of regenerative chatter vibration in a plain milling operation is investigated from the viewpoint of cutting force variation. With primary chatter vibration, the vibration energy supply is closely related to the collision of the cutting tool flank against the workpiece surface during vibration, which is induced by the bending vibration or the torsional vibration of the arbor. In addition to this factor, the regenerative effect is considered to be one of the main causes of the chatter excitation in regenerative chatter vibration. The simulation result of the cutting force variation during regenerative chatter vibration agrees well with the experimental result, when considering these factors. It is shown that the regenerative chatter vibration in the-down-milling process occurs more easily than in the up-milling process.     

基于空化效应的功率超声珩磨再生型颤振研究

功率超声珩磨加工过程中的颤振影响因素很多,不仅包含物理磨削过程和机械振动环节,还包含了高频振动和超声波传动系统,是一个非常复杂的复合振动系统。通过建立珩磨颤振动力学模型,重点研究珩磨中空化泡溃灭产生辐射声压对再生型颤振的影响,结果表明:决定功率超声珩磨再生型颤振的主要原因为磨削厚度;空化泡溃灭产生的辐射声压会加剧系统颤振的频率,但对系统颤振的时域图变化趋势和振幅的大小基本没有影响。     

Causes of chatter in a hot strip mill: Observations, qualitative analyses and mathematical modelling

Severe vibrations, known as chatter, occur often in both hot and cold rolling of steel. A recent chatter outbreak at the second stand of hot strip mill in Hastings, Australia, prompted an investigation into the causes of chatter by a literature review, the development and deployment of mathematical models, and a rigorous analysis of plant observations. The investigation suggests that the frictional conditions in the roll gap are the principal cause of chatter in this mill, though residual chatter marks on work rolls can occasionally cause it. The frictional conditions appear to be associated with the thickness and properties of oxide formed on rolls.