基于移动窗比功率的主动式头枕控制算法

为减小追尾碰撞中乘员损伤,开发了一款基于加速度信号控制的主动式头枕。针对其控制系统,提出了移动窗比功率算法。通过与移动窗积分算法和比功率算法进行运算数据对比,分析了其抗干扰性和触发及时性,并开展了头枕台架试验和后碰撞台车试验。结果表明,该算法抗干扰性更强,触发更及时,其触发时刻误差在1ms以内,能有效避免误触发;头枕可在碰撞发生后52ms内完全展开,控制系统可在15ms内发出触发信号。     

嵌入式智能球铰链设计及研制

精密球铰链在并联机构中应用广泛,但其在被动运动中,其回转方位及回转角无法自知。基于磁效应,提出一种霍尔传感器与永磁体组合的回转方位辨识及角度测量新方法。在球头上嵌入永磁体,在球窝上植入霍尔传感器阵列,当球头回转时,霍尔传感器阵列测量磁感应强度的变化,反解出角度信息。在完成理论建模、仿真计算和可行性试验的基础上,完成了嵌入式样机的研制。在实现信号冗余计算的基础上,优化了反解算法,基本实现了球铰链多维回转角度的实时测量。球铰链也从单纯的精密传动部件转变为集传动和感测为一体的综合智能部件。随研究的继续,其精度将有大幅提高,有望应用到精密工程中。     

Microwear mechanism of head carbon film during head disk interface sliding contact

Thermomechanical sliding contact of head disk interface (HDI) causes critical wear on the carbon film of a head slider. An improved contact model accounting for both asperity and substrate deformation is applied to analyze the HDI contact behavior, while theories of frictional heat generation and heat transfer are used to investigate the change in HDI temperature. Based on actual HDI design and operation parameters, parametric study of thermomechanical HDI contact has been performed. It was found that severe wear of head carbon film would be significantly attributed to thermal degradation of carbon material during its sliding contact.     

汽车顶蓬搬运折断风险计算及应用

针对聚氨酯汽车顶蓬在生产搬运过程中容易折断的问题,在分析顶蓬搬运折断失效模式的基础上,对顶蓬及其搬运过程进行了假设和简化,把搬运中的顶蓬简化为简支梁,然后使用与FEA相同的基本数学模型,设计了一种计算顶蓬侧边折断风险的方法,并用MathCAD编制程序实现项蓬受力的计算和折断风险的评估.使用编制的程序对某E级车双天窗顶蓬进行了分析,结果表明此计算方法使用简便,计算结果准确、可靠.最后对顶蓬折断问题的改进提出了可行的建议.     

SAPV及API579凹坑评定标准用于尿素合成塔的保守度评价

分别运用SAPV和API579规范对某化肥厂含腐蚀凹坑尿素合成塔上封头进行安全评定，并与有限元极限分析结果和分析设计规范强度校核的结果进行了比较，对SAPV和API579两种凹坑安全评定方法的保守度进行了讨论，作者认为：API579及SAPV的球形封头凹坑安全评定方法均足够保守，SAPV球形封头凹坑评定规程用于外壁凹坑时安全裕度是恰当的，但用于内壁凹坑时显得过分保守，提出了球壳内壁凹坑安全评定时可适当降低安全系数的建议。     

基于AT89C52的探测头更换系统设计

介绍了一套以89C52单片机为核心,联合编码器和推拉电磁铁实现探测头自动更换的系统。以超声波作为检测信号源,采用探测头与探测头夹具配合以适应不同直径的回转体工件的检测要求,同时解决了传统检测控制系统中探测头更换与高精度定位的矛盾。     

Model-based operating recommendations for high-speed spindles equipped with a self-vibratory drilling head

The drilling of deep holes requires the chips to be evacuated using retreat cycles and lubrication, which is problematic for both productivity and the environment. An alternative response to the chip evacuation problem is the use of a vibratory drilling head, which enables the chip to be split thanks to the axial self-excited drill, and hence it can easily be evacuated from the hole. The vibratory drilling head is composed of a specific tool holder with adjustable axial stiffness. In this paper, a dynamic high-speed spindle/drilling head/tool system model is elaborated on the basis of rotor dynamics predictions. The dynamic properties of interfaces between system components are identified by the receptance coupling method and integrated into the model. The model is validated by comparing the numerical FRF with experimental results. Then adequate self-vibratory cutting conditions are established by integrating the model-based tool tip FRF into the chatter approach of Budak-Altintas. Spindle rolling bearing lifespan is also investigated in order to guarantee a rational use of the spindle-tool set with respect to industrial lifespan.     

Influence of blade wrap angle on centrifugal pump performance by numerical and experimental study

The existing research on improving the hydraulic performance of centrifugal pumps mainly focuses on the design method and the parameter optimization. The traditional design method for centrifugal impellers relies more on experience of engineers that typically only satisfies the continuity equation of the fluid. In this study, on the basis of the direct and inverse iteration design method which simultaneously solves the continuity and motion equations of the fluid and shapes the blade geometry by controlling the wrap angle, three centrifugal pump impellers are designed by altering blade wrap angles while keeping other parameters constant. The three-dimensional flow fields in three centrifugal pumps are numerically simulated, and the simulation results illustrate that the blade with larger wrap angle has more powerful control ability on the flow pattern in impeller. The three pumps have nearly the same pressure distributions at the small flow rate, but the pressure gradient increase in the pump with the largest wrap angle is smoother than the other two pumps at the design and large flow rates. The pump head and efficiency are also influenced by the blade wrap angle. The highest head and efficiency are also observed for the largest angle. An experiment rig is designed and built to test the performance of the pump with the largest wrap angle. The test results show that the wide space of its efficiency area and the stability of its operation ensure the excellent performance of the design method and verify the numerical analysis. The analysis on influence of the blade wrap angle for centrifugal pump performance in this paper can be beneficial to the optimization design of the centrifugal pump.     

加工方钻杆专用机床的铣头设计与分析

以加工方钻杆专用机床的铣头为研究对象,设计并分析其机械结构是否满足加工工件的需要。具体介绍铣头设计过程及结构布置形式,同时对其铣头结构进行有限元分析,建立铣头结构三维模型。对其模态分析后,得出了其铣头箱体的前六阶固有频率和振型,与铣头切削时的振动频率进行比较。分析结果为评定方钻杆机床的动态特性提供了依据,并且为具有与其相似结构的铣头提供了理论基础。     

In-Production Nondestructive Testing of Internal Stresses in Rails Using Acoustoelasticity Method

Results of an experimental study of internal stresses in selectively heat-strengthened rails by an acoustoelastic method using the electromagnetic-acoustic method of input-reception of shear waves are presented. Results of modeling the stressed-strained state of a rail with critical stresses present in its bottom and data of an experimental tensometric study of residual stresses in the rail bottom are considered. An analysis of the results has confirmed a spread in stresses across different sections within a single rail, and also revealed an excess over the critical level of stresses in the surface layer of the rail bottom under compressive stresses in its head and web. A rejection criterion for acoustoelastic testing is proposed that conforms with the requirements of GOST (State Standard) 51685 in the case of both web cutting and rail bottom tensometry.

     

"穿地龙"机器人转向机构虚拟样机研究

"穿地龙"机器人是一种特种机器人,主要由锥形头部、转向机构、冲击装置三部件组成,能够实现PE或PVC管、电缆、光缆等中、小直径管线的地下非开挖铺设,有广泛的应用前景和开发价值.文中介绍了"穿地龙"机器人的转向机构,叙述了该机构中头部的摆动原理,建立了头部质心的运动方程,并运用虚拟样机技术对转向机构进行了虚拟装配和对头部质心的运动进行了仿真研究,可得出虚拟装配无干涉和可实现头部质心的各种位姿变化,验证了该转向机构的可靠性,可为"穿地龙"机器人的总体设计提供参考.     

Automated Generation of Lifters for Injection Moulds

An algorithm for automated identification of undercuts and the creation of the lifter subassembly in plastic injection mould design is described. The algorithm is suitable for injection mould design in a 3D mode. The input to the software is a 3D part model, parting direction and lines, and a mould-base. The software then generates the lifter subassembly and places it properly in the mould-base. This is accomplished in four steps. First, the so-called virtual core and cavity are generated without considering any undercuts. Undercut faces on the part are then identified and undercut groups are formed. Secondly, the releasing direction of each undercut group is found. Thirdly, for each undercut group, a lifter head based on its releasing direction is created. Fourthly, other standard components of a lifter assembly are retrieved and attached to the corresponding lifter head within the mould-base at the correct location. A case study is presented that illustrates the efficacy of the technique for the automated design of lifters to fulfil a real industrial requirement.     

KSNP+ reactor vessel head drop analysis for a 5.5M free fall

The KSNP⁺ RV closure head drop analysis was carried out to assess the reactor core coolability in case of the RV closure head drop accident during the refueling operation. The analysis consists of a number of different RV head drop scenarios as the postulated accident events during refueling that include a concentric head drop case and three different cases of laterally offset head drop cases. The analysis was initiated due to the adoption of the IHA (Integrated Head Assembly) in the KSNP⁺ reactor design, which increases the weight of the RV closure head assembly. Four different analysis models were developed that correspond to the RV head drop analysis scenarios. An in-house dynamic analysis code was used for the RV head drop analysis. The entire reactor internals and fuel assemblies are modeled by using lumped masses and spring elements. Because of the extreme load exerted by RV head drop, most members experience stresses that are beyond the elastic limits. A separate elastic—plastic analysis for some members was carried out and the resulting load-deflection curve was used as the stiffness of the element. The effect of water above the reactor vessel in the refueling pool was ignored for the conservative estimation of the analysis. The analysis shows that the concentric head drop is the most severe case of loading condition. It also reveals that the local deformation of some reactor internals and the fuel assemblies is occurred; however the primary membrane stresses are within the bound of allowable stress limits. Consequently the reactor core remains in coolable state.     

相贯线处圆角半径对泵头体自增强性能的影响研究

为了研究压裂柱塞泵泵头体相贯线处圆角半径大小与其自增强性能的关系,以某型号的压裂柱塞泵泵头体为研究对象,利用有限元分析软件,建立了泵头体的参数化有限元模型,针对不同相贯线处圆角半径大小,对其进行了有限元分析。分析结果表明:相贯线处圆角半径为7mm时,泵头体极限载荷较大;相贯线圆角半径为6.35mm时,泵头体残余应力最大;在综合考虑相贯线圆角半径大小对泵头体极限载荷及自增强处理后的残余应力的影响,压裂柱塞泵泵头体相贯线处圆角半径最佳值为6.35mm。     

一种新型带电水冲洗设备喷头

设计了一种新型带电水;中洗设备喷头机构,结构紧凑、使用方便,解决了防静电、防水等防护问题,并成功运用于生产实践,极大地提高了喷头运动的灵活性和可靠性。     

开合式在线测量大电流的光纤电流互感器

介绍了一种可以用于在线测量、实时安装、拆卸的开合式光纤电流互感器方案。在传感头开启过程中,利用传感头内部一段橡胶骨架的弹性产生均匀变形,使绕制在上面的光纤应力变化较小。为了保证互感器的温度稳定性,传感头内部骨架主要为石英材料,由于石英骨架加工的误差比较大,所以采用长圆孔的支架将其固定在传感头结构上。信号处理部分基于全数字闭环检测,采用方波调制方案,并通过数字阶梯波反馈实现闭环检测。在开合过程后对开合式互感器进行测试分析,实验结果表明系统的变比稳定性可以达到了0.5%的精度,可以满足实际应用的要求。     

Functional Collapse of Designed Surface Texture for Stiction Prevention in Storage Disk Drives

Laser texture is widely used to prevent stiction in the head disk interface. The stiction protection depends on the effective height of the laser texture. The balance between the meniscus and mechanical deformation forces is described when lubricant migrates into the head disk interface. When the elastic deformation forces cannot balance the meniscus force, the laser texture bumps collapse and the protection against stiction is lost. A critical bump height is defined. Bump collapse is experimentally demonstrated by monitoring the capacitance between head and disk when lubricant migrates from the trailing edge of a slider into the head disk interface. An interface with high bumps shows a small capacitance increase since the mechanical deformation forces can balance the meniscus forces with only small bump compression. Consistent with a calculated capacitance increase under bump collapse, an interface with low bumps shows a large capacitance increase.     

Shape Optimization To Perform Prescribed Air Lubrication Using Genetic Algorithm

A shape optimization of magnetic head for magnetic recording device with rotating drum was studied. An optimization algorithm was developed based on genetic algorithms in conjunction with finite element method which analyzed interface phenomena between a magnetic tape and a magnetic head. The head shape was defined by a second order spline function. Three reference points and first order derivatives at a origin point were coded by the genetic algorithm. As a result, an applicability of genetic algorithms to the given optimization problem was verified.     

平面蜗轮副蜗杆专用磨头的设计和应用

介绍了一种新型的平面蜗轮副蜗杆专用磨头的设计原理和使用方法。磨头结构简单，操作方便，通用性强；对提高产品质量和劳动生产率有重要意义。     

中低比转速离心泵叶轮多目标优化设计

中低比转速离心泵效率普遍不高，主要因素是泵的损失过大，在减小泵的损失时，容易使汽蚀余量增大，扬程曲线产生驼峰，为提高泵效率，减少汽蚀余量，消除扬程曲线驼峰，本文论述了以中低比转速泵的能量损失最小，汽蚀余量最小及消除扬程曲线驼峰为多目标函数，以叶轮主要参数为设计变量的泵叶轮优化设计方法，通过优化，获得了满足一定扬程和流量的最优参数组合。