高速双螺杆挤出机螺杆轴断裂失效分析

某双螺杆挤出机的螺杆在运行过程中发生早期断裂,通过断口的宏观观察和扫描电镜观察、化学成分分析、显微组织观察、力学性能测试和有限元模拟,找出了螺杆轴断裂失效的原因。结果表明:螺杆轴发生了扭转疲劳断裂,裂纹起源于齿根,且有多个疲劳源;芯轴的花键齿根部是螺杆轴应力集中的部位;热处理工艺欠佳导致材料内部微孔聚集、组织不均匀,这些因素最终致使螺杆轴发生早期疲劳断裂。     

实时导向螺杆钻具钻柱螺纹动力学特性及优化设计方法

由于钻井过程中载荷具有冲击性、不稳定性，螺杆钻具联接螺纹失效率居高不下。为提高螺杆钻具使用寿命，利用ANSYS建立了2-7/8REG和4-1/2REG螺纹分别在压力、弯矩、转矩3种载荷条件下的三维有限元分析模型，建立了减应力槽、切削第一啮合齿、双台肩3种优化结构，在3种载荷条件下对3种优化结构的力学行为和优化效果进行了对比分析，为螺杆钻具螺纹不同主失效原因的结构优化提供了选择依据。研究表明：压力载荷条件下的应力集中仅双台肩结构发生降低，降低比例为40%左右；弯矩载荷条件下，降低应力集中程度由大到小的结构顺序为减应力槽、切削第一啮合齿、双台肩；转c3矩载荷条件下，减应力槽结构能够降低以4-¹/₂REG螺纹为例的大型螺纹的应力r集3中，比例为12.7%，但会加重以2-⁷/₈REG螺纹为例的小型螺纹的应力集中，此外，切削第一啮合齿和双台肩结构的降低程度均在10%左右。     

聚丙烯挤出机螺杆轴断裂失效分析

某聚丙烯挤出机在运行中发生螺杆轴断裂,采用断口宏观分析、扫描电镜观察、化学成分分析、显微组织检验、力学性能测试等方法对断裂轴开展失效分析。结果表明:螺杆轴的断裂为扭转疲劳断裂,裂纹起源于花键根部;螺杆轴的疲劳强度低、花键槽根部应力集中、材料内部微孔聚集、材料组织不均匀等原因共同导致螺杆轴发生早期疲劳断裂;建议采取改进热处理工艺、提高安装精度、检查表面缺陷等措施。     

基础螺栓损坏后的修复

设备基础螺栓损坏后,人们习惯用对接法修复,即将已损坏的螺纹段切除,再焊接一段完好的螺纹杆.由于焊口部位应力集中且不易保证同轴度,故修复效果不理想.我们用套接法修复基础螺栓,效果很好.l.一次性套接法修复基础螺栓(图1)(1)制做带孔螺杆.带孔螺杆内孔直径比待修复的基     

高强度螺纹

英国某大学研究小组发表一项科研成果,采用新设计法能降低螺纹牙的最大应力,从而提高连接强度。以往的螺杆与螺帽的大部份载荷由螺帽结合面附近的螺纹牙承受,因此,这种螺纹牙本质上会引起应力集中,限制了承受的负载。     

机械双螺杆传动变速器

本发明公开了一种机械双螺杆传动变速器，它主要由箱体、输入轴、中间轴、输出轴、相互啮合的主传动螺杆和从传动螺杆组以及轴承组成，螺杆传动副设在箱体中，输入轴上设有两个主传动螺杆，一个为主传动左旋螺杆，另一个为主传动右旋螺杆；中间轴两端各设有一个从传动螺杆，一个为从传动左旋螺杆，另一个为从传动右旋螺杆；输入轴上主传动螺杆与中间轴上的从传动螺杆相啮合；中间轴中间设有一对主传动双旋螺杆，并与输出轴的一对从传动双旋螺杆相啮合。     

螺杆空气压缩机排气含油量高原因分析和解决措施研究

喷油螺杆压缩机通过螺杆压缩空气将机械能转化为气体动能的机械设备，广泛应用于工业制造、矿产、化工、交通运输等行业。螺杆空气压缩机所用的润滑油可以在螺杆运转时起到润滑、密封和控制螺杆温度的作用，但同时也存在螺杆空气压缩机出现排气含油量高，影响用气端的压缩空气品质。本文简述螺杆空气压缩机的工作原理与油气分离原理，对排气含油量高现象进行简单分析，阐述其后果，并提出相应的改进策略，以期为相关人员提供参考。     

国内螺杆压缩机的发展现状

一．概况 螺杆压缩机广泛应用于矿山、化工，动力、冶金、建筑、机械、制冷等工业部门，在宽广的容量和工况范围内，逐渐替代了其他种类的压缩机。统计数据表明，全世界范围内，螺杆压缩机的销售量已占所有容积式压缩机销售量的80％，在所有正在运行的容积式压缩机中，有50％是螺杆压缩机。在我国，由于螺杆压缩机发展历程比较短，上述比例分别为40％和15％左右。今后螺杆压缩机的市场份额将不断扩大，特别是无油螺杆空气压缩机和各类螺杆工艺压缩机，会获得更快的发展。     

螺旋排屑器叶片模具

数控机床的排屑器一般分为螺旋式排屑器、链板式排屑器、磁性排屑器等几种类型，其中螺旋式排屑器应用最为广泛，其主要部件是螺杆，螺杆又分为空心螺杆和实心螺杆，这里仅以图1所示实心螺杆为例进行说明，螺杆由图2所示螺旋叶片与中间的心轴焊接而成。螺旋叶片加工质量的好坏直接影响螺杆的螺距、外圆直径、内圆直径的一致性，螺旋曲面的光滑与否，又决定排屑器排屑是否顺畅。     

螺杆转子加工的RTM方法

介绍了树脂传递模塑成型工艺RTM的成型原理，阐述了螺杆压缩机转子成型的RTM方法，包括：复合螺杆转子的材料；螺杆转子模具设计的三次样条曲线法；螺杆转子的模具制造；螺杆转子RTM加工过程等。     

M-LFM: a multi-level fusion modeling method for shape−performance integrated digital twin of complex structure

As a virtual representation of a specific physical asset, the digital twin has great potential for realizing the life cycle maintenance management of a dynamic system. Nevertheless, the dynamic stress concentration is generated since the state of the dynamic system changes over time. This generation of dynamic stress concentration has hindered the exploitation of the digital twin to reflect the dynamic behaviors of systems in practical engineering applications. In this context, this paper is interested in achieving real-time performance prediction of dynamic systems by developing a new digital twin framework that includes simulation data, measuring data, multi-level fusion modeling (M-LFM), visualization techniques, and fatigue analysis. To leverage its capacity, the M-LFM method combines the advantages of different surrogate models and integrates simulation and measured data, which can improve the prediction accuracy of dynamic stress concentration. A telescopic boom crane is used as an example to verify the proposed framework for stress prediction and fatigue analysis of the complex dynamic system. The results show that the M-LFM method has better performance in the computational efficiency and calculation accuracy of the stress prediction compared with the polynomial response surface method and the kriging method. In other words, the proposed framework can leverage the advantages of digital twins in a dynamic system: damage monitoring, safety assessment, and other aspects and then promote the development of digital twins in industrial fields.     

有限元分析技术在注塑机拉杆结构分析中的应用

拉杆是注塑机提供合模力的重要构件。这里用有限元法对拉杆进行了有限元分析，并对拉杆的关键部位进行了材料力学测试，表明拉杆螺纹处的应力集中现象比较明显，并在此部位容易形成裂纹。测试和计算结果可为注塑机拉杆结构的改进设计提供参考。     

高强度螺栓的应力测试

应用应变电测方法测试高强度螺栓的应力集中。为此，设计制造了专用的测力螺栓。实测表明，应用该方法行之有效，能满足工程设计的要求。     

机载装备紧固螺钉强度分析与设计改进

为了解决某机载装备内部滤波器模块的紧固螺钉在耐久随机振动过程中发生的断裂问题,对紧固螺钉开展了强度校核和应力仿真分析,给出了机载装备小尺寸螺钉在耐久随机振动中剪切应力和挤压应力的估算方法,并应用ANSYS Workbench仿真软件对紧固螺钉在振动过程中的受力情况进行了仿真分析。强度校核和仿真分析结果对比表明,螺钉承受的剪切应力和挤压应力均高于许用限值,在振动中存在断裂风险,与试验现象吻合。依据螺钉强度校核和仿真分析结果,在紧固螺钉的螺纹直径方面进行了设计改进。经整机试验验证,改进后的紧固螺钉可满足耐久随机振动试验的强度要求,改进措施有效,表明文中给出的强度校核和仿真分析方法具有一定可信度,可作为类似结构的设计参照。     

新型锥形双螺杆压缩机的结构和原理

介绍了一种全新结构的锥形双螺杆压缩机的工作原理、结构特点、几何理论、受力分析及优缺点,并推导了行程容积的计算公式.新型锥形双螺杆压缩机与圆柱形双螺杆压缩机相比,它的转子有一定的锥度,齿间面积沿压缩方向呈线性减小,能够有效增加压缩比,减小泄漏三角的面积和接触线的长度,减少泄漏量,使受力状况得到改善,并降低了功耗.     

Automatic twin statistics from electron backscattered diffraction data

A new computer code has been developed to automatically extract quantitative twin statistics from electron backscatter diffraction data. The new code is an improvement upon previous codes in that it handles materials of any crystal symmetry, type I, Type II and compound twins, and general stress states. Moreover, accuracy of the results has been greatly improved. In addition, twin statistics including number, area fraction, twin thickness and twinning dependencies on orientation, grain size and neighbourhood effects can be routinely analysed. The new code has been applied to scan data from deformed magnesium, zirconium and uranium, and can potentially be used for any twinning material for which reliable electron backscatter diffraction results can be obtained.     

Quantitative structural analysis of twin boundary in alpha-Zn7Sb2O12 using HAADF STEM method

The structure and composition of the 1/4{110} twin boundary in alpha-Zn7Sb2O12 have been determined by using quantitative high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) analysis. The noise in the experimental HAADF STEM images is reduced by using the maximum entropy method and average processing, and the parameters used in dynamical simulations are experimentally determined. From the analysis, it has been found that octahedral sites in the twin boundary slightly shift parallel to the [110] direction, and a reduction of the Sb concentration at the octahedral sites on the plane adjacent to the twin boundary was detected. The reduction was measured from three regions in the same twin boundary, and the Sb concentrations were 4 +/- 3, 8 +/- 3 and 19 +/-2 at% from 33 at%.     

高速双螺母滚珠丝杠副轴向接触刚度研究

对双螺母预紧的滚珠丝杠副进行了接触受力分析,推导出接触变形的公式,建立了滚珠丝杠副的轴向刚度计算公式。研究分析了影响滚珠丝杠副轴向刚度的几个主要因素,包括预紧力、螺旋升角、接触角等,给出了这几个因素与滚珠丝杠副轴向刚度对应的关系曲线,为新型高速滚珠丝杠的合理设计提供了理论基础。     

High resolution and conventional electron microscopy studies of repeated wedge microtwins in monoclinic rare earth sesquioxides

High resolution and conventional studies have been made on the inclined twin boundaries occurring near the tip of wedge microtwins in the case of repeated wedge microtwins occurring at twin intersections. These inclined boundaries appear to be continuous and all the atomic planes are also continuous so that we suggest the use of the term ‘inclined coherent boundaries’ instead of ‘incoherent’ which one generally employs, in analogy to the case of precipitates in a matrix. This is different from what occurs in the case of isolated wedge microtwins for the same material and for the same kind of twins where the inclined twin boundary is really not coherent, being made of non-inclined coherent regions separated by steps containing a dislocation. The coherent inclined boundaries of repeated wedge microtwins appear to be rotated about two perpendicular axes of the habit plane (tilt and twist) giving rise to a distribution of microdislocations whose role has been studied. The values of the tilt and twist angles are related to a minimization of the total energy by a mechanism that is likely to appear only in the case of thin foils. A comparative study of the different roles related to the different structures of inclined twin boundaries for isolated and repeated wedge microtwins has been made, and also a comparative study of the mechanisms of stress relaxation in each case. The studies have been made on (313) twins of a monoclinic samarium sesquioxide.     

转盘轴承螺栓连接特性分析

分析了转盘轴承连接螺栓的应力变形特性,推导出载荷正弦分布,连接螺栓圆周均布条件下的最大应力方程;对比螺栓应力试验测试值与理论计算值,并说明了在实际应用中将影响到连接螺栓应力的其他因素.