Wear Analysis of Disc Cutters of Full Face Rock Tunnel Boring Machine

Wear is a major factor of disc cutters’ failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine（TBM） to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead（radius for installation）; in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians’ experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project（excavation length 173 m）. The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project（excavation length of 5621 m）. The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate（accuracy 16.12%） but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient（accuracy 41%, which is in agreement with the prediction of disc cutters’ life in the field）. This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

Theoretical prediction of wear of disc cutters in tunnel boring machine and its application

Predicting the cutter consumption and the exact time to replace the worn-out cutters in tunneling projects constructed with tunnel boring machine(TBM) is always a challenging issue. In this paper, we focus on the analyses of cutter motion in the rock breaking process and trajectory of rock breaking point on the cutter edge in rocks. The analytical expressions of the length of face along which the breaking point moves and the length of spiral trajectory of the maximum penetration point are derived. Through observation of rock breaking process of disc cutters as well as analysis of disc rock interaction, the following concepts are proposed: the arc length theory of predicting wear extent of inner and center cutters, and the spiral theory of predicting wear extent of gage and transition cutters. Data obtained from5621 m-long Qinling tunnel reveal that among 39 disc cutters, the relative errors between cumulatively predicted and measured wear values for nine cutters are larger than 20%, while approximately 76.9% of total cutters have the relative errors less than 20%. The proposed method could offer a new attempt to predict the disc cutter's wear extent and changing time.

Analytical Solutions for the Two-Dimensional Magnetic Fields in Disc-Type Permanent Magnet Machines

A two dimensional analytical method for predicting the magnetic field in the airgap/magnet region of a permanent magnet (PM) disc type machine is presented. The solutions of the governing field equations are given in both Cartesian and cylindrical coordinates. The expressions derived in this paper can be used conveniently for optimal design of machine. The computed results using the proposed 2D analytical method are validated by the more accurate, though a lot more complicated, 3D finite element analyses.

A Dual Closed-Loop Digital Twin Construction Method for Optimizing the Copper Disc Casting Process

The copper disc casting machine is core equipment for producing copper anode plates in the copper metallurgy industry.The copper disc casting machine casting package motion curve(CPMC) is significant for precise casting and efficient production.However,the lack of exact casting modeling and real-time simulation information severely restricts dynamic CPMC optimization.To this end,a liquid copper droplet model describes the casting package copper flow pattern in the casting process.Furthermore,a CPMC optimization model is proposed for the first time.On top of this,a digital twin dual closed-loop self-optimization application framework(DT-DCS) is constructed for optimizing the copper disc casting process to achieve self-optimization of the CPMC and closed-loop feedback of manufacturing information during the casting process.Finally,a case study is carried out based on the proposed methods in the industrial field.

Design Theory of Full Face Rock Tunnel Boring Machine Transition Cutter Edge Angle and Its Application

At present, the inner cutters of a full face rock tunnel boring machine (TBM) and transition cutter edge angles are designed on the basis of indentation test or linear grooving test. The inner and outer edge angles of disc cutters are characterized as symmetric to each other with respect to the cutter edge plane. This design has some practical defects, such as severe eccentric wear and tipping, etc. In this paper, the current design theory of disc cutter edge angle is analyzed, and the characteristics of the rock-breaking movement of disc cutters are studied. The researching results show that the rotational motion of disc cutters with the cutterhead gives rise to the difference between the interactions of inner rock and outer rock with the contact area of disc cutters, with shearing and extrusion on the inner rock and attrition on the outer rock. The wear of disc cutters at the contact area is unbalanced, among which the wear in the largest normal stress area is most apparent. Therefore, a three-dimensional model theory of rock breaking and an edge angle design theory of transition disc cutter are proposed to overcome the flaws of the currently used TBM cutter heads, such as short life span, camber wearing, tipping. And a corresponding equation is established. With reference to a specific construction case, the edge angle of the transition disc cutter has been designed based on the theory. The application of TBM in some practical project proves that the theory has obvious advantages in enhancing disc cutter life, decreasing replacement frequency, and making economic benefits. The proposed research provides a theoretical basis for the design of TBM three-dimensional disc cutters whose rock-breaking operation time can be effectively increased.

Enhanced wear prediction of tunnel boring machine disc cutters for accurate remaining useful life estimation using a hybrid model

In tunnel construction with tunnel boring machines(TBMs),accurate prediction of the remaining useful life(RUL)of disc cutters is critical for timely maintenance and replacement to avoid delays and cost overruns.This paper introduces a novel hybrid model,integrating fundamental and data-driven approaches,to enhance wear prediction of TBM disc cutters and enable accurate RUL estimation.The fundamental model is improved by incorporating composite wear mechanisms and load estimation techniques,showcasing superior prediction accuracy compared to single-mechanism models.Additionally,the hybrid model innovatively incorporates a data-driven supplementary residual term into the improved fundamental model,leading to a high-performance wear prediction model.Using actual field data from a highway tunnel project in Shenzhen,the performance of the hybrid model is rigorously tested and compared with pure fundamental and data-driven models.The hybrid model outperforms the other models,achieving the highest accuracy in predicting TBM disc cutter wear(mean absolute error(MAE)=0.53,root mean square error(RMSE)=0.64).Furthermore,this study thoroughly analyzes the hybrid model’s generalization capability,revealing significant impacts of geological conditions on prediction accuracy.The model’s generalization capability is also improved by expanding and updating the data sets.The RUL estimation results provided by the hybrid model are straightforward and effective,making it a valuable tool by which construction staff can monitor TBM disc cutters.

超声联合C臂机选择性神经根注射改善腰突致神经痛的效果观察

目的 观察超声联合C臂机选择性神经根注射治疗腰椎间盘突出致坐骨神经痛的临床效果。方法 180例确诊腰突致坐骨神经痛的患者分为观察组和对照组各90例,分别接受C臂机选择性神经根注射治疗和联合超声治疗。分别于治疗后1周、2周、1个月,统计两组患者的治疗优良率;采用视觉模拟评分法(VAS)评估患者疼痛,应用Oswestry功能障碍指数(ODI)评价下腰痛功能障碍。结果 观察组的透视次数、辐射剂量、穿刺时间均少于对照组,一次穿刺成功率(92.22%)高于对照组(63.33%),差异均有统计学意义(P<0.05)。治疗后1周、2周、1个月,观察组的治疗优良率分别为92.22%、88.89%、83.33%,与对照组(85.56%、83.33%、77.78%)差异均无统计学意义(χ^(2)=2.025、1.161、0.887,均P>0.05);2组的VAS评分、ODI指数均显著降低,差异有统计学意义(P<0.05)。结论 超声联合C臂机选择性神经根注射治疗腰突致坐骨神经痛,能够减少透视次数、辐射剂量、穿刺时间,提高一次穿刺成功率。

机器学习在腰椎间盘突出症诊治中的优势和应用策略

背景:基于机器学习的不同算法,如何借助各种算法模型开展腰椎间盘突出症的临床研究已成为目前智能化医学发展的趋势和热点。目的:综述机器学习不同算法模型在腰椎间盘突出症诊治中的特点,归纳相同用途的算法模型各自优势和应用策略。方法:计算机检索PubMed、Web of Science、EMBASE、中国知网、万方数据、维普及中国生物医学数据库中与机器学习在腰椎间盘突出症诊治中的相关应用文献,按入组标准筛选后最终纳入96篇文献进行综述。结果与结论:①机器学习的不同算法模型为腰椎间盘突出症的临床诊治提供了智能化、精准化的应用策略。②监督学习中的传统统计学方法和决策树在探究危险因素,制定诊断、预后模型方面简单高效;支持向量机适用于高维特征的小数据集,作为非线性分类器可应用于正常或退变椎间盘的识别、分割、分类,制定诊断、预后模型;集成学习可相互弥补单一模型的不足,具有处理高维数据的能力,提高临床预测模型的精度和准确性;人工神经网络提高了模型的学习能力,可应用于椎间盘识别和分类,制作临床预测模型;深度学习在具有以上用途的基础上,还能优化图像,辅助手术操作,是目前腰椎间盘突出症诊治中应用最广泛、性能最佳的模型;无监督学习中的聚类算法主要用于椎间盘分割和不同突出节段的分类;而半监督学习方式临床应用相对较少。③目前,机器学习在腰椎间盘的识别、分割,退变椎间盘的分类和分级,自动化临床诊断和分类,构建临床预测模型以及辅助术中操作方面具有一定临床优势。④近年来,机器学习的研究策略已向神经网络和深度学习方向转变,具有更强学习能力的深度学习算法将会是未来实现智能化医疗的关键。

基于图网络和网络药理学探讨名老中医治疗腰椎间盘突出症用药规律及作用机制

目的挖掘治疗腰椎间盘突出症常用中药,并探讨这些药物的作用机制,为新药开发和临床治疗腰椎间盘突出症提供指导。方法基于课题收集的名老中医治疗腰椎间盘突出症的临床病例,以Python语言调用相关包将机器学习算法模型的结果构建药物网络图;基于图数据模型在药物网络图上进行药物重要性判定,然后使用TCMSP与BATMAN数据库获取重要药物信息,使用DisGeNET、GeneCards与OMIM获取疾病信息,并对交集靶点进行后续研究。使用STRING、GO与KEGG数据库进行蛋白互作分析与富集分析,以了解其潜在治疗机制。结果本研究纳入476例符合要求的病例,共得到高频药物40味,高频药对81对。基于高频药对构建药物网络图,进行步长为7的无回退随机游走,共获得42503924条路径图。以每味药物作为起点,从所有路径中寻找基于每个起点的最短路径,共获得86条最短路径图,并基于最短路径图获得常用药物9个;根据网络药理学预测出常用药物活性成分共258个,与疾病的交集靶点基因共58个,GO分析共获得2324个条目,KEGG通路研究共获得144条具有统计学意义的相关途径。结论名老中医治疗腰椎间盘突出症主要从补肝益肾、祛风除湿、活血化瘀三方面组方,具有多方位、多靶点的特点。根据网络药理学预测结果,常用药物治疗腰椎间盘突出症的主要机制为炎症相关机制与脂质代谢相关机制。

4000m DISC深冰芯钻机概述

深冰芯钻探(Deep Ice Sheet Coring,DISC)钻机是美国冰芯钻探服务中心(ICDS)开发研制的一款机电钻机,设计取芯直径122mm,钻取深度4 000m.该系统由两部分组成,包括机械钻进系统和地面支撑系统.其中,机械钻进系统由钻机、电缆、钻塔和绞车四部分组成,钻机是该系统的钻探部分,由6个不同部件(刀盘、芯管、筛管、电机/水泵、钻机控制板和顶端)组成;地面支撑系统包括电源、控制系统、冰芯处理系统、钻井液处理系统、筛管清洗系统、辅助设备以及安全设备设施.2006年夏季ICDS在格陵兰Summit营地对该套钻机系统进行了成功试验,2011年12月31日在西南极冰原(WAIS Divide)成功获取3 405m深度的冰芯.实践证明,该套钻机能够满足目前钻探项目的科学需求.但是,在西南极冰原主冰孔不同深度钻取同深度副冰孔冰芯的过程中,钻刀无法在主冰孔壁上侧向钻取新的冰芯孔,未能如期获取复制的冰芯样品.

Efflcient machining of a complex blisk channel using a disc cutter

For rough machining of a complex narrow cavity,e.g.,a complex blisk channel on an aero-engine,the typically used cutting tools are the slender cylindrical cutter and conical cutter.Nevertheless,as neither of the two is particularly suited for rough machining,wherein the main purpose is to remove a large volume as quickly as possible,the machining efficiency is low,especially when the part materials are of hard-to-cut types(e.g.,Titanium-alloy)for which it often takes days to rough machine a blisk.Fortunately,disc machining provides a new and efficient roughing solution,since a disc cutter with a large radius enables a much larger cutting speed and thus a larger material removal rate.However,due to the large radius of the disc cutter,its potential collision with narrow and twisted channels becomes a serious concern.In this paper,we propose a novel twophase approach for efficiently machining a complex narrow cavity workpiece using a disc-shaped cutter,i.e.,3+2-axis disc-slotting of the channel by multiple layers(rough machining)+five-axis disc-milling of the freeform channel side surfaces(semi-finish machining).Both simulation and physical cutting experiments are conducted to assess the effectiveness and advantages of the proposed method.The experimental results show that,with respect to a same cusp-height threshold on the channel side surfaces,the total machining time of the tested part by the proposed method is about only 36%of that by the conventional approach of plunging-milling(for roughing)plus milling by a slender cylindrical cutter(for semi-finishing).

滚刀滑移状态下的受力与磨损仿真分析

为探究滚刀滑移状态下破岩的受力与磨损的变化规律,基于离散单元法,建立了同时考虑滚刀自转和绕刀盘公转的滚动圆周切割模型。定义了一个滑移率参数η用于描述滚刀的滑移状态,对不同滑移率工况下滚刀破岩受力和磨损进行了对比分析,并结合工程实例对数值仿真结论进行了验证,结果表明:数值仿真中垂直力F_(V)和滚动力F_(R)在CSM模型计算值附近波动,两者较为吻合,表明了本文模型的合理性。数值仿真结果表明,随着滑移率η的增大,垂直力F_(V)呈轻微减小趋势,滚动力F_(R)明显变大,从滚动破岩到滑动破岩,垂直力F_(V)降幅为23.6%,滚动力F_(R)增幅达83.7%,滑动破岩将导致滚刀偏磨。工程实测数据表明,刀盘上大量滚刀处于正常磨损状态时,主要表现为推力增大。大量滚刀处于偏磨状态时,主要表现为扭矩增大,其中偏磨滚刀占比19.05%和28.57%时,扭矩增幅分别为55.85%和261.51%。滚刀正常磨损和偏磨均大量存在时,表现为扭矩推力同步增大,其中偏磨滚刀占比21.43%时,扭矩增幅为80.89%。数值仿真和实测数据表现出较高的一致性。综合4次开仓换刀结果,可将刀盘扭矩增幅超过50%作为判定大量滚刀发生偏磨的重要依据。

基于销/盘试验机的摩擦噪声试验与仿真研究

为了研究摩擦噪声的产生机制和影响因素,利用销/盘试验机对以转子式压缩机曲轴-法兰材料制成的销/盘试样进行摩擦噪声试验研究;应用ABAQUS有限元软件,建立销/盘试验机有限元模型,利用复特征值分析方法预测该系统摩擦噪声的主频,并与试验结果进行对比;讨论相关参数对系统的稳定性和摩擦噪声的影响。结果表明:销与盘法向和横向振动的耦合是引起系统自激振动和摩擦噪声的重要因素;当系统摩擦界面处的摩擦因数大于系统临界摩擦因数时,系统开始出现不稳定振动,且摩擦因数越大,系统越不稳定,越易出现摩擦噪声;法向载荷对系统稳定性的影响不大;选择具有合适弹性模量的摩擦副材料可以抑制摩擦噪声的产生。

TBM窄刃刀与标准刀现场性能对比测试与分析

极硬岩条件下如何进行刀具选型,使TBM掘进速度和刀具消耗取得综合效益,是有待解决的具有争议性的问题。为此,依托新疆YE工程现场TBM实际掘进,在岩石单轴抗压强度为100~150 MPa的完整Ⅱ类凝灰岩条件下,对比测试刀盘主要区域窄刃刀和标准刀的掘进性能表现以及刀具消耗情况,探索降低滚刀刀圈刃宽,提升TBM贯入度和掘进速度的可行性与合理性。结果表明:1)使用窄刃刀破岩对贯入度和施工速度有着较为明显的提升,且随着围岩抗压强度的增加,窄刃刀对掘进速度的提升效果明显;2)与标准刀相比,窄刃刀消耗数量也有较大增加,但2种滚刀的失效形式占比情况大致相同,对TBM作业利用率影响极小;3)经综合成本估算,窄刃刀通过提升施工速度节省的成本远高于刀具消耗增加的成本。

金刚石砂轮盘轮廓精度检测及盘面精密修整方法

金刚石砂轮盘的轮廓精度检测及盘面精密修整是金刚石刀具制造领域的关键问题。首先为实现砂轮盘轮廓误差的高精度测量,提出一种基于激光三角测量的在位测量方法,实现了砂轮盘面误差亚微米级精度的高效检测。实验结果表明,该方法可以方便地评估不同精修参数下的修整精度。随后,采用单点金刚石修整法对青铜基金刚石砂轮盘进行了盘面精密修整工艺实验,分别探究了修整进给深度、主轴转速、主轴往复运动频率以及修整压力对盘面修整精度的影响,并优选了修整工艺参数,优选的工艺参数为:修整深度1µm,主轴转速3000r/min,主轴往复频率0.15Hz,接触压力14.7N。最后,不同修整精度的砂轮盘分别被用于研磨金刚石微楔形刀具。实验结果表明,所提出的砂轮盘精度检测和盘面精密修整方法对提高金刚石刀具的制造质量具有重要应用价值。

基于ADAMS的全断面竖井掘进机锥形刀盘载荷特性

全断面竖井掘进机锥形刀盘在竖井施工中具有导向性好、姿态调整方便等优点,滚刀作为竖井掘进机施工中最直接的破岩工具,获取其载荷分布规律对于竖井掘进机的刀盘刀具系统的合理设计和掘进过程中装备姿态的调整具有重要意义。基于ADAMS建立了全断面竖井掘进机锥形刀盘与岩体耦合模型,合理施加约束条件对正常掘进工况进行仿真,获取了竖井掘进机锥形刀盘刀具的载荷分布规律。结果表明:由于安装方式的不同,正滚刀所受到的侧向力和滚动力均大于中心滚刀,对正滚刀刀座与辐条之间的连接强度提出了更高要求;随着正滚刀在刀盘上安装半径的增大,其受到的垂直力也增大。中心滚刀所受到合力载荷稳定性较正滚刀明显较好,波动更小;随着滚刀在刀盘上安装半径的增加,滚刀所受到的合力载荷大小波动更大,载荷稳定性也更差。

航空涡轮盘拉削刀具健康监测系统设计

针对航空涡轮盘拉削刀具生产周期长、造价昂贵、监测困难以及易出现损伤等问题,设计并构建了拉削刀具健康监测系统。根据拉床行业的特点、痛点及实际需求等,提出了系统的总体框架。基于加速度传感器及振动监控器,设计了拉床在线、在位的振动信号采集系统,实现了拉削过程中刀具振动信号的连续、实时采集。基于C++语言与Qt开发平台,开发了刀具健康监测系统,实现了对振动信号的实时分析处理及刀具健康监测。

急停工况下的盾构机刀盘扭矩自适应滑模控制技术

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