5/12钢筋靠模式弯箍机构设计与参数计算

为有效提高钢筋自动弯曲成形精度和效率,引入靠模成型设计方法,提出了一种新型的箍筋模钢筋弯箍设计方案.基于弹塑性变形理论,建立了钢筋弯曲过程中弯箍转盘转角与钢筋弯曲成形角度之间的数模方程,推导了钢筋弯曲过程中弯曲力以及弯箍转盘的转矩和功率与钢筋弯曲角度的函数关系式,并详细分析了它们随弯曲角度的变化规律,较为详细的研究分析了系统的各个参数,提出了确定各系统参数的方法.结果表明,该机构设计合理,满足使用要求,便于实现自动控制.     

箍筋多边形成型建模及分析

为明确箍筋多边形成型过程中其成型状态与箍筋拉力的关系,将箍筋拉弯过程分成先大挠度弯曲变形后拉直两个阶段;首先建立箍筋大挠度弯曲变形的悬臂梁力学模型,分析自由端上的压力与成型参数的关系;然后建立箍筋拉直的力学模型,得出箍筋拉力与位移的关系。根据上述力学模型,计算得到了在成型参数一定的情况下成型状态与成型拉力的关系图,给出了保证箍筋成型的拉力值。拉力波动方程分析表明在多边形箍筋角速度一定的情况下拉力的波动对箍筋成型状态的影响较小可以忽略不计。仿真表明:将箍筋拉弯过程看成先大挠度弯曲变形后拉直两个阶段,是获得箍筋成型状态与箍筋拉力定量关系的有效途径,建立的成型状态与成型拉力的关系图对多边形成型具有理论指导意义。     

自动钢筋弯箍机的设计

提出了一种应用于钢筋弯箍的弯箍机器,可以实现对放在工作台上的钢筋进行弯箍处理。介绍了自动钢筋弯箍机的总体机械结构方案及相关的硬件电路,编制相应的软件程序。在原有钢筋弯曲机的基础之上,对其进行一系列的改进,以满足高水准建筑工程的需求。     

下弦节点预埋钢筋弯曲成形工艺及模具设计

正预埋钢筋是规格为φ32mm带有纵肋的月牙肋钢筋,纵肋高度为2.4mm,实际外径在φ33.7~φ35.2mm之间,零件长度为1200mm。为增加预埋钢筋的锚固力,设计弯曲面不在同一个平面上,其弯曲截面互相垂直。预埋钢筋3D模型如图1所示。1.零件工艺性分析(1)弯曲成形方式预埋钢筋技术条件要求采用机械冷弯方式,若不对钢筋进行加热,仅靠手工很难弯曲成形。采用车间3000kN摩擦压力机进行冲模压弯成形。     

多边形箍筋机液压驱动系统设计

多边形箍筋机是应用于建筑行业的一种自动化机械,可以实现对钢筋进行校直、弯曲成型和切断等加工工序,该文论述了一种多边形箍筋机的液压驱动系统设计,使得整个箍筋过程实现了自动化生产,提高了生产效率及箍筋的生产质量,缩短工作周期,使得工作效率得以提高.     

钢筋弯曲回弹试验及其数学模型校正

对不同材料,不同规格的钢筋进行不同角度弯箍试验,并对弯箍试验建立数学模型,将试验测量数据与理论计算结果对比,通过数据对比,对理论计算公式进行修订,使该理论计算公式得到进一步的优化,并广泛应用于设计、实际生产等具有重要的参考意义。     

超薄镀锌板辊弯成形回弹工艺分析

对于超薄镀锌板,厚度薄回弹量大难以控制是运用辊弯成形方法中的难点之一。基于ABAQUS有限元软件建立了超薄板辊弯成形仿真模型,以单波模型为例,运用正交试验方法分析了压型板的回弹,详细分析了相对弯曲半径变化对回弹的影响。研究表明,材料厚度增加、弯角半径减小时,回弹角度会减小;在一定范围内较少道次数也能减小回弹角度;板材回弹角度与r／t值成线性关系。     

高频感应弯板成形试验台设计

针对国内外高频感应弯板成形试验设备缺乏现状,设计了弯板成形试验台,用于进行高频感应弯板成形试验,进而有助于研究高频感应弯板成形规律。利用Ansys软件对弯板成形模型进行了有限元分析,并利用试验台进行了相同参数下板料成形试验,将有限元分析得到的折弯角度曲线与试验得到的实际折弯角度曲线进行了对比,结果表明:有限元分析得到的板料折弯角度曲线与试验得到的板料折弯角度曲线基本相同,二者折弯角度偏差小于12.1%。     

大弯曲半径管材推弯回弹有限元分析

大弯曲半径管材是在推弯机的推弯过程中成形的,因在推弯过程中,模具与管坯间各参数的相互影响导致管坯在推弯成形后,不可避免的产生回弹角,因而影响了管坯在后期应用中的精度和准确率。因此采用动态有限元平台ABAQUS/Explicit软件对大弯曲半径管材的推弯成形建立符合实际推弯参数的有限元模型,并通过有限元数值模拟对推弯过程中影响回弹角的主要因素:相对弯曲半径R/D、相对壁厚D/t、摩擦系数、以及材料的硬化指数和强度系数进行有限元分析,并得出这些参数对回弹角影响的规律曲线。     

工艺参数对管材激光弯曲成形影响规律的研究

管材激光弯曲成形是一种柔性金属塑性成形方法。将连续的激光光斑简化为一间歇跳跃的方形匀强面热源,并考虑材料性能参数与温度的相关性,建立了管材激光弯曲成形的热-机耦合有限元工艺仿真模型,对成形过程进行了数值模拟。有限元模拟结果表明:在其他条件不变的情况下,激光弯曲角度随激光功率的增大而增大,两者基本上成线性关系;弯曲角度随扫描速度的升高而减小,随光斑直径的减小而增大,但当光斑直径减小到一定程度后,弯曲角度开始减小;弯曲角度随扫描包角的增大而增大,当扫描包角为180°时,弯曲角度达到最大,弯曲角度随扫描包角的继续增大而减小;扫描次数与弯曲角度间成近似的线性关系,且第一次扫描管材产生的弯曲角度最大。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.