ANALYSIS OF MECHANICS IN BALL SPINNING OF THIN-WALLED TUBE

Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain problem, slab method is used for the purpose of calculating the contact deformation pressure. The spinning force components, the torsional moment, the deformation power and the deformation work are calculated further as well. The influence of the two important process parameters such as the feed ratio and the ball diameter on the spinning force components is analyzed in order to further control the spinning force components by regulating the two process variables during the ball spinning process. The stress and strain state in deformable zone as well as mechanics boundary conditions in ball spinning are obtained. The effect of the three spinning force components on the formability of the spun part is analyzed and validated through the ball spinning experiments. The theoretical and experimental results show that the radial spinning component plays a significant role in ball spinning of thin-walled tube, and the mechanics situation in backward ball spinning contributes to enhancing the plasticity of the metal material, but that in forward ball spinning contributes to advancing the axial flow of the metal material.

AISI-304不锈钢薄壁管滚珠旋压工艺参数的正交优化研究

针对小直径不锈钢薄壁管滚珠旋压参数不当引发的一系列问题,选取φ6 mm×0.5 mm×10 mm的AISI-304不锈钢管为研究对象,建立其有限元模型,运用Abaqus软件对其成形过程进行仿真,分析了不同工艺参数(减薄量、进给比、旋压角)对其等效应力和均匀塑性应变的影响,最后运用正交试验法对工艺参数进行优化。结果表明:优化后的工艺参数组合为:减薄量0.2 mm、进给比0.05 mm/r、旋压角25°。在此工艺参数组合下,AISI-304不锈钢管的等效应力值和均匀塑性应变值达到最优,其值分别为642.22 MPa和0.06。

既有网架杆件外包钢管加固技术试验研究

针对既有网架结构中承载能力不足的构件,提出了一种外包钢管的加固方法,该方法通过将外包钢管与杆件两端球节点焊接,使其直接承担网架荷载,并在内外管中间设置衬管以促进二者的共同作用,进而提高加固后杆件的整体承载能力,该加固方法可有效针对网架承载能力不足的杆件进行加固,通过仿真和试验分析,该加固方法具有较好的加固效果和工程实施性。

水下油管挂送入管柱系统液控球阀技术研究

水下油管挂送入管柱系统为完井作业期间的主要井控安全屏障,在出现井下安全风险时可通过控制液控球阀实现水下管柱的应急关断,也可实现剪断连续油管、电缆和钢丝等柔性措施管串后实现紧急关断,提高井控反应的时间。球阀本体总成的设计与加工制造工艺是实现液控球阀剪断柔性措施管串后密封的关键技术。针对球阀本体总成的设计结构、选材和表面措施处理的工艺,阐述液控球阀实现剪切后密封关键技术,提供了一种可行的球阀总成结构及其制造工艺方案。研究成果对水下油管挂送入管柱技术国产化研究和现场应用具有指导意义。

大规模加砂压裂完井工具冲蚀定量模拟计算及工具优化

须家河致密砂岩气藏120 MPa超高压、长时间大排量加砂压裂作业对管柱冲蚀影响,导致完井管柱出现变形、断裂、球座磨损、分段球不到位等问题。基于冲蚀磨损理论,选择出分段管柱中四处冲蚀严重部位,利用Ansys软件进行建模,采用动静态结合方法,计算得到了大规模加砂压裂施工管柱变径处的冲蚀程度定量值,明确了油管短节与滑套球座为冲蚀严重位置,有针对性地对冲蚀最严重位置进行了结构优化及材质优选。油管变扣短节优选Q125钢级管材可兼顾强度及经济性;改进滑套上接头变径处台阶倒角控制在30°以内,滑套球座顶部优化设计为弧形结构,球座采用硬质合金材质,优化改进后的滑套冲蚀程度比原结构降低66.5%,经川东北须家河组YL15、YL171、YL6等多口井成功应用,优化改进的压裂管柱满足了超高压加砂压裂长时间施工需求。

General issues of FEM in backward ball spinning of thin-walled tubular part with longitudinal inner ribs

Backward ball spinning was applied for manufacturing thin-walled tubular parts with longitudinal inner ribs. Rigid-plastic finite element method(FEM) was used for simulating the backward ball spinning process in order to calculate the height of the inner ribs. With a view to guarantee a better simulation accuracy, it is essential to enhance and improve some general problems of FEM, such as generation of initial velocity field, choice of penalty factor, determination of boundary conditions, treatment of rigid region and description of convergence criteria. It is evident that whether the problems with respect to FEM are dealt with appropriately or not, they have a significant influence on the modeling accuracy and efficiency. By reasonable solving the general problems, rigid-plastic FEM can successfully simulate the height of the inner ribs and the calculated values are in good agreement with the measured values.

Selection of Parameters in Ball-Spinning

Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is stili unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the vvorking angle, the axial feeding rate, and the acceptable vvorking course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the bail diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.

A Theoretical Analysis of Ball Spinning

As a special method of manufacturing thin wall tubes, the ball spinning process has been used for nearly 30 years because of its less investment of equipment, higher precision, and more perfect properties of products. However, the application is limited since the process parameters are determined based on empirical data and laboratory experiments for lack of a whole theoretical analysis. In this paper, some basic parameters such as the force and power parameters have been studied based on an analysis of geometry and mechanics of the process. The calculation of forming forces and the selection of the working angle are carried out. At the end, a perfect comparison between the results of the experiments and the theoretical analysis is made.

Deformation Mechanism of Hot Spinning of NiTi Shape Memory Alloy Tube Based on FEM

As a successively and locally plastic deformation process, ball spinning is applied to manufacturing thin-walled Nickel-Titanium shape memory alloy （NiTi SMA） tube at high temperature. NiTi SMA tube blank belongs to the as-cast state which consists of a lot of dendritic grains and a few equiaxed grains. The compression tests of NiTi SMA were carried out at various strain rates at high temperature in order to obtain the constitutive model of NiTi SMA. Because NiTi SMA is sensitive to the strain rates at high temperature, rigid-viscoplastic finite element method （FEM） is used to simulate ball spinning of thin-walled NiTi SMA tube in order to analyze the deformation behavior of ball spinning of NiTi SMA tube. Stress fields, strain fields as well as velocity fields is obtained by means of rigid-viscoplastic FEM, which lays the profound foundations for studying the metal flow rule in ball spinning and forming perfect spun NiTi SMA tube.

球磨工艺对废玻璃管粒度及用于陶瓷结合剂的影响

采用控制变量法,通过改变球磨时间、转速、球料比和球的级配,探究球磨工艺对废玻璃管粉末粒径的影响。改变原料目数,烧结温度,原料构成,探究影响陶瓷结合剂和陶瓷磨具力学性能的因素。实验结果表明:当转数为450 r/min、球料比31、球的级配241时,对废玻璃管原料球磨0.5 h时,球磨效率最高。在陶瓷磨具体系中,加入1.93 wt%黏土,17.33 wt%长石,19.28 wt%玻璃粉末,61.44 wt%SG磨料和适量临时粘结剂,在1000℃下烧成的陶瓷磨具力学性能最好,其样条抗折强度,洛氏硬度和密度最大分别为48.42 MPa,52.52 HRB和2.54 g/cm^(3),此时孔隙率为45.62%。

滚珠旋压工艺中成形区接触压力的分析计算

针对滚珠旋压过程中成形区滚珠与管件接触压力的确定问题,提出利用平面应变状态下圆弧形冲头压入半无限体时平均接触压力来间接推出加工过程中成形区平均接触压力的方法,讨论了钢球压入半无限体时的平均接触压力与滚珠旋压时接触压力以及平面应变状态下圆弧形冲头压入半无限体时的平均接触压力之间的关系,并进行了实验验证.研究结果表明:以平面应变状态下圆弧形冲头压入半无限体时的平均接触压力推导出的滚珠旋压时滚珠与所成形管料的平均接触压力值的计算公式具有较高的实用性.

基于神经元网络的制粉系统球磨机负荷软测量

分析了制粉系统球磨机磨筒内负荷 (存煤量 )的各种影响因素及影响特性 ,提出了基于人工神经网络测量磨筒内负荷的软测量方法 ,给出了基于前向复合型神经网络的分工况学习的变结构式负荷测量模型及神经网络训练算法 ,正常工况下采用延时神经网络 ,而接近堵磨工况时则采用回归神经网络 ,工况的一种模糊划分方法同时被给出。离线训练及计算机仿真结果证实了所提神经网络软测量方法的可行性 ,为球磨机制粉系统的优化运行和自动控制奠定了基础。对某DTM3 5 0 / 60 0型球磨机的实测数据分析进一步证实了所提方法的有效性 ,且在计算结果的指导下 ,提高该球磨机制粉系统的出力约达 6t/h 。

基于RBF神经网络的球磨机负荷软测量

分析了球磨机负荷测量的现状 ,提出了基于并行 RBF神经网络测量制粉系统球磨机磨筒内负荷的软测量方法 ,给出了相应的系统结构和算法。

钢珠旋压工艺力能参数的分析及计算

针对滚珠旋压工艺的工艺参数即轴向进给量、壁厚减薄量、钢球直径大小对所成形的小直径薄壁管件(或筒件)精度、成形设备功率选择的影响,对钢珠旋压过程作了求解各向分力及其与成形工作角等工艺参数的理论推导,提出滚珠旋压时工作区的平均正压力可以通过钢球压入空间半无限体时成形区的平均压力近似相等的假设,得出了滚珠旋压成形力和成形功率的计算公式.认为滚珠旋压工艺中3个分力数值相差比较大,而且工作角对于各项工艺力呈指数关系.实验结果与计算结果对比表明所推导的公式具有较强的实用性.

滚珠旋压工艺的滚珠直径选择

滚珠旋压工艺参数的选择在滚珠旋压工艺中具有重要意义．根据滚珠旋压工艺参数对成形件质量的影响,通过实验研究与理论分析,提出滚珠的剥皮效应与旋压工作角有直接关系的假说,并得出工作角对成形件质量的影响图．依据最小变薄率的分析结果,对滚珠旋压工艺中滚珠直径的选择原则进行研究,提出了工程实践中滚珠直径的选择原则,实验表明,该选择原则具有较强的实用性．

肌腹下眶-球硅管连接术与肌腹下注射A型肉毒素治疗麻痹性斜视的效果对比

目的探讨在麻痹肌肌腹下行眶-球硅管连接术与肌腹下注射A型肉毒素治疗麻痹性斜视的疗效对比。方法收集36例(36眼)斜视患者,根据治疗方法不同分为两组,A组行肌腹下眶-球硅管连接术,B组行A型肉毒素眼外肌注射治疗,每组各18例(18眼)。记录术后1周与6 a时两组患者的临床效果、角膜散光、视功能及屈光度变化等情况。结果 A组患者术后均达到美容性眼位矫正;12例(66.7%)达到功能性眼位矫正;治疗1周后角膜前表面屈光度、散光值及散光轴向与治疗前相比明显增加,治疗6 a后角膜前表面屈光度、散光值及散光轴向基本恢复至术前水平;A组术后1周8例患者存在双眼视功能,随访6 a 14例存在双眼视功能。B组患者术后12例(66.7%)达到美容性眼位矫正;达到功能性眼位矫正者9例(50.0%);治疗1周后及随访6 a角膜前表面屈光度、散光值及散光轴向与治疗前相比差异均无统计学意义(均为P>0.05);B组术后1周6例患者存在双眼视功能,随访6 a 7例存在双眼视功能;两组治疗后1周近视度数相比差异无统计学意义(P>0.05),随访6 a,A组近视度数为(-3.52±2.82)D,B组为(-5.78±3.42)D,A组明显低于B组(P<0.05)。结论肌腹下眶-球硅管连接术与肌腹下注射A型肉毒素相比,在临床效果、角膜散光、视功能方面均有明显差异,眶-球硅管连接术是治疗麻痹性斜视的可行方法,值得推广。

滚珠丝杠副中滚珠与导珠管的接触碰撞分析

对滚珠丝杠副中滚珠进入循环导珠管时发生的接触碰撞进行研究分析,考虑滚珠和导珠管的几何外形、丝杠的转动速度等因素,建立了滚珠和导珠管碰撞接触的动力学模型.在此基础上,分析了滚珠丝杠转速、碰撞角与碰撞力、接触时间之间的关系,并讨论了空心滚珠结构和采用Si3N4的陶瓷材料作为滚珠材料以降低滚珠与导珠管间冲击的效果.这对于优化导珠管结构,改善和提高高速滚珠丝杠副的动态性能指标具有重要的理论意义.

振动磨DEM动力学分析模型

运用离散单元法建立振动磨动力学分析模型,研究了振动磨的动力学特性;介绍了DEM及运用DEM建立振动磨动力学分析模型的方法和过程.该模型可对振动磨的磨管和磨介的运动进行数字模拟,可用于对振动磨各种动力特性的定量分析.

球头硅胶管逆行泪道植管术治疗鼻泪道阻塞的疗效及影响因素分析

目的 探讨球头硅胶管逆行泪道植管术治疗鼻泪道阻塞的疗效及其相关影响因素。方法 回顾性选择本院眼科就诊的已接受球头硅胶管逆行泪道植管术的92例（92眼）鼻泪道阻塞患者,排除泪小管阻塞、泪总管阻塞、泪点外翻等情况,记录性别、年龄及术前病情、术后疗效,统计分析其相关影响因素。结果 经术后随访6~12个月,92例鼻泪道阻塞患者中治愈77例（83.7%）,均无明显手术并发症发生。单因素分析发现,治愈组和欠佳组患者的性别、年龄差异均无统计学意义（均为P〉0.05）,而术前合并不同病情的患者其手术治疗效果差异有统计学意义（P=0.042）。Logistic逐步回归分析发现,性别、年龄与手术治疗效果均无相关性（均为P〉0.05）,而术前病情的三组中,与泪道损伤史病例对比,单纯鼻泪道阻塞与手术治愈率具有相关性（OR=5.343,P=0.032）。结论 利用球头硅胶管逆行泪道植管术治疗鼻泪道阻塞,成功率较高,且无明显手术并发症。术前充分考虑各种病情对手术的影响,可以进一步提高手术成功率。

球磨机筒体的声辐射特性分析与噪声治理

以球磨机筒体为研究对象,推导了筒体在正常工作条件下所受到的载荷函数,采用有限元方法对筒体进行有限元模拟求得应力应变分布,确定筒体在受载状态下的脱离点和下落点的应力集中部位。然后利用声学仿真软件计算球磨机筒体的声辐射模态,确定了球磨机筒体的主要噪声频段为低频段。最后,根据声辐射模态分析结果采用悬吊吸声体和墙体吸声的方法对球磨机机房进行吸声处理,使机房内的噪声下降了6 dB,达到良好的效果。