Experimental study on the influences of cutter geometry and material on scraper wear during shield TBM tunnelling in abrasive sandy ground

When shield TBM tunnelling in abrasive sandy ground,the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling efficiency.However,the influence mechanism of cutter parameters on scraper wear remains unclear due to the lack of a reliable test method.Geometry and material optimisation are often based on subjective experience,which is unfavourable for improving scraper geological adaptability.In the present study,the newly developed WHU-SAT soil abrasion test was used to evaluate the variation in scraper wear with cutter geometry,material and hardness.The influence mechanism of cutter parameters on scraper wear has been revealed according to the scratch characteristics of the scraper surface.Cutter geometry and material parameters have been optimised to reduce scraper wear.The results indicate that the variation in scraper wear with cutter geometry is related to the cutting resistance,frictional resistance and stress distribution.An appropriate increase in the front angle(or back angle)reduces the cutting resistance(or frictional resistance),while an excessive increase in the front angle(or back angle)reduces the edge angle and causes stress concentration.The optimal front angle,back angle and edge angle for quartz sand samples areα=25°,β=10°andγ=55°,respectively.The wear resistance of the modelled scrapers made of different metal materials is related to the chemical elements and microstructure.The wear resistances of the modelled scrapers made of 45#,06Cr19Ni10,42CrMo4 and 40CrNiMoA are 0.569,0.661,0.691 and 0.728 times those made of WC-Co,respectively.When the alloy hardness is less than 47 HRC(or greater than 58 HRC),scraper wear decreases slowly with increasing alloy hardness as the scratch depth of the particle asperity on the metal surface stabilizes at a high(or low)level.However,when the alloy hardness is between 47 HRC and 58 HRC,scraper wear decreases rapidly with increasing alloy hardness as the scratch depth transitions from high to low levels.The sensitive hardness interval and recommended hardness interval for quartz sand are[47,58]and[58,62],respectively.The present study provides a reference for optimising scraper parameters and improving cutterhead adaptability in abrasive sandy ground tunnelling.

Virtual straightening of scraper conveyor based on the position and attitude solution of industrial robot model

The movement of the floating connecting mechanism between a hydraulic support and scraper conveyor is space movement;thus,when the hydraulic support pushes the scraper conveyor,there is an error between the actual distance of the scraper conveyor and the theoretical moving distance.As a result,the scraper conveyor cannot obtain the straightness requirement.Therefore,the movement law of the floating connecting mechanism between the hydraulic support and scraper conveyor is analyzed and programmed into the Unity3D to realize accurate pushing of the scraper conveyor via hydraulic support.The Coal Seam?Equipment Joint Virtual Straightening System is established,and a straightening method based on the motion law of a floating connection is proposed as the default method of the system.In addition,a straightening simulation of the scraper conveyor was performed on a complex coal seam floor,the results demonstrate that the average straightening error of the scraper conveyor is within 2-8 mm,and is in direct proportion to the fluctuation of the coal seam floor in the strike of the seam with high accuracy,the straightness of scraper conveyor is more affected by the subsidence terrain during straightening than by the bulge terrain.And some conclusions are verified by experiment.Based on the verification of the relevant conclusions,a comparison and analysis of Longwall Automation Steering Committee(LASC)straightening technology and default straightening method in the simulation system shows that the straightness accuracy of LASC straightening technology under complex floor conditions is slightly less than that of the default straightening method in the proposed system.

CFD studies of scraper built in SPA clarifying tank based on mixture solid-liquid two-phase flow model

In the industrial process of producing the strong phosphoric acid(SPA),clarification of the solution is essential to the ultimate product.However,the large viscosity of sediment and the induced interface interaction result in difficulties when the SPA is clarified.CFD numerical methodology was applied to simulate internal flow field and performance of the low speed scraper based on Mixture solidliquid two-phase flow model.Sediment deposition was generated by loading solid particles at the bottom of clarifying vessel.The moving mesh and RNG k-εmodel were used to simulate the rotational turbulent flow in clarifying tank.Variables studied,amongst others,were the scraper rotation speed and the mounting height,which could affect the solid suspension height.Features of flow field and solid volume fraction distribution in computational domain were presented and analyzed.The numerical reports of the scraper torque and velocities of inlet and outlet filed were obtained.It seems the torque value of rotatio-nal axis and particle suspending height augment with an increasing rotating speed.Meanwhile,a high revolving speed is good for the deposition discharge.The particle fraction distribution in meridional surface and horizontal surface at fixed rotation speed were analyzed to determine the corresponding optimal installation height.The simulating results reflect the flow field is marginally stirred by the scraper and proper working parameters are obtained,in which case the comprehensive properties of the scraper and the clarifying tank are superior.

Theoretical and Experimental Studies of the Effect of Inclined Scraper on Removal of Raw Cotton from Mesh Surface

The present manuscript deals with theoretical and experimental studies of the effect of inclined scraper on removal raw cotton from mesh surface. The mathematical model of the problem and theoretical studies of the motion of cotton mass on plane of scraper is derived taking into account material point by accomplishing plane motion in the mesh surface. Graphs of the experiment shows that performance of scraper inclined to the radius of the disk by the value α=30° to the surface mesh β=110°, optimally allows to reduce the formation of technological defects of raw cotton. The presence of zero-pressure portion on the mesh surface of separator may provide complete removal of cotton from its surface and to eliminate grid clogging.

Thermal analysis and tests of W/Cu brazing for primary collimator scraper in CSNS/RCS

To the transverse beam collimation system in a rapid cycling synchrotron,an important component is the primary collimator,which improves emittance of the beam halo particles such that the particles outside the predefined trajectory can be absorbed by the secondary collimators.Given the material properties and power deposition distribution,the beam scraper of the primary collimator is a0.17 mm tungsten foil on a double face-wedged copper block of 121.5 mm x 20 mm.The heat is transferred to the outside by a φ34 mm copper rod.In this paper,for minimizing brazing thermal stress,we report our theoretical analysis and tests on brazing the tungsten and copper materials which differ greatly in size.We show that the thermal stress effect can be controlled effectively by creating stress relief grooves on the copper block and inserting a tungsten transition layer into the copper block.This innovation contributes to the successful R&D of the primary collimator.And this study may be of help for working out a brazing plan of similar structures.

Case of pancreatic metastasis from colon cancer in which cell block using the Trefle^■ endoscopic scraper enables differential diagnosis from pancreatic cancer

Endoscopic transpapillary brush cytology and forceps biopsy during endoscopic retrograde cholangiopancreatology are generally used to obtain pathological evidence of biliary strictures. Recently, the new endoscopic scraper Trefle~? has been reported and demonstrated high cancer detectability in malignant biliary strictures. This device is used to scrape the stricture over the guidewire, and, in the original method, the tissue and/or cell samples obtained are subjected to histological and/or cytological analysis separately. However, discrimination of chunks of tissue is hampered by the opacity of the surrounding fluid. We have developed a cell block technique for the Trefle~? device without dividing obtained specimens into tissue and cellular components, which is the simplest method and enables immunohistochemical analysis. We present a case of obstructive jaundice diagnosed immunohistochemically as pancreatic metastasis from colon cancer using cell block sections obtained with the Trefle~? device, which procedure is as easy as conventional brush cytology.

Modelling and Simulation of Scraper Reliability for Maintenance

A scraper conveyor is a kind of heavy machinery which can continuously transport goods and widely used in mines, ports and store enterprises. Since scraper failure rate directly affects production costs and production capacity, the evaluation and the prediction of scraper conveyor reliability are important for these enterprises. In this paper, the reliabilities of different parts are classified and discussed according to their structural characteristics and different failure factors. Based on the component＇s time-to-failure density function, the reliability model of scraper chain is constructed to track the age distribution of part population and the reliability change of the scraper chain. Based on the stress-strength interference model, considering the decrease of strength due to fatigue failure, the dynamic reliability model of such component as gear, axis is developed to observe the change of the part reliability with the service time of scraper. Finally, system reliability model of the scraper is established for the maintenance to simulate and calculate the scraper reliability.

Decommissioning analysis of the scrapers in the NSRL Linac using depth profiling

For a high-energy electron facility, estimates of induced radioactivity in materials are of considerable importance to ensure that the exposure of personnel and the environment remains as low as reasonably achievable. In addition, accurate predictions of induced radioactivity are essential to the design, operation, and decommissioning of a high-energy electron linear accelerator. In the case of the 200-MeV electron linac of the National Synchrotron Radiation Laboratory(NSRL), the electrons are accelerated by five acceleration tubes and collimated by copper scrapers. The scrapers, which play a vital role in protecting the acceleration cavity, are bombarded by many electrons over a long-term operation, which causes a significant amount of induced radioactivity. Recently, the NSRL Linac is the first high-energy electron linear accelerator in China to be out of commission.Its decommissioning is highly significant for obtaining decommissioning experience. This paper focuses on the measurement of induced radioactivity on the fourth scraper, where the electron energy was 158 MeV. The radionuclides were classified according to their half-lives. Such a classification provides a reliable basis for the formulation of radiation protection and facility decommissioning. To determine the high-radioactivity area and to facilitate the decommissioning process, the slicing method was applied in this study. The specific activity of60 Co in each slice was measured at a cooling time of ten months, and the results were compared with the predictions generated by Monte Carlo program FLUKA. The trend of the measured results is in good agreement with the normalized simulation results. The slicing simulation using Monte Carlo method is useful for the determination of high-radiation areas and proper material handling protocols and, therefore, lays a foundation for the accumulation of decommissioning experience.

超长柔性悬挂固体充填刮板输送机异常工况表征及自主调控方法

固体充填刮板输送机是固体充填开采技术的关键装备,其高效智能化的程度制约着固体智能充填开采技术的进步,暂难突破超大采长、大功率、高可靠性的瓶颈,运行状态受地质条件、充填工艺等主控因素影响显著,异常工况自主调控问题亟待解决。总结了固体充填刮板输送机特征;构建了固体充填刮板输送机位姿形态与运输状态表征方法;通过分析异常工况的形成机理,选取异常工况判别指标,结合位姿与运输状态表征方法,给出了其空间位姿、牵引状态等异常工况判别准则与典型异常工况的调控路径,揭示了多工况状态下固体充填刮板输送机运载调控机制,提出了实时调控充填材料运输量、直线及水平程度组合的异常工况自主调控方法。全国首个260 m工作面长固体充填工程案例表明:通过异常工况自主调控,平均最大水平偏移距每减少100 mm,刮板链牵引力可减少85 kN,输送功率损耗可减少55 kW;平均最大垂直偏移距每减小100 mm时,输送功率损耗可减少7.2 kW;单位长度货载运量每减少100 kN/m,刮板链牵引力可减少31.9 kN,输送功率损耗可减少38.2 kW。所提出的异常工况自主调控方法可显著提升固体充填刮板输送机的输送效能,可助力实现固体智能充填开采。

导向式活鱼分级装置设计及试验

鱼类养殖过程中的大小分级有利于生长管理和饲料控制,提高养殖效益。针对目前国内活鱼分级劳动强度大、效率低等问题,设计了一种导向式活鱼分级装置,介绍了该分级装置的结构组成及工作原理,并对鱼体输送机构进行力学分析和参数设计。基于鱼类体质量和体型参数关系,测定了试验鲫鱼形态数据,并运用幂函数拟合方法得到鲫鱼体厚与体质量关系方程,作为分级通道间距设定依据。分级时通过调节分级通道两侧导鱼板之间的间距,设定分级通道适合待分级鱼的规格要求,利用鱼的体厚,通过分级通道实现分级。开展了活鱼分级性能试验,分级鱼体质量范围为0.14~0.33 kg,鱼体厚度范围为30~39 mm,并对进鱼输送速度为0.15、0.20、0.25 m/s三种条件下分别进行分级测试和效果分析。试验结果显示,在正常条件下分级准确率可以达到90%以上,合适的输送速度和分级通道间距设定效率更高。研究表明,该导向式分级装置能够快速、准确地对活鱼进行分级,提高养殖过程机械化作业效率。

刮板输送机技术发展历程(一)——国外技术

刮板输送机是井下采煤工作面的“脊梁”装备,它经历了6次技术变革,持续推动采煤工艺变革及生产效率持续提升。刮板输送机第1次技术变革发生于1900-1940年,诞生了可拆卸刮板输送机,煤矿开启半机械化开采时代;第2次技术变革产生于1940-1950年,创制了可弯曲刮板输送机,煤矿进入机械化开采时代;第3次技术变革形成于1950-1985年,创设了可自移刮板输送机,煤矿跨入综合机械化开采时代;第4次技术变革出现在1985-2000年,已发展成为重型化刮板输送机,煤矿走向高产高效综采时代;第5次技术变革形成于2000-2010年,研发出自动化刮板输送机,煤矿迈向数字化综采时代;第6次技术变革始于2010年,创新推出智能化刮板输送机,煤矿开启少人化智采时代。英国和德国为刮板输送机初创做出巨大贡献,研制出多种早期的刮板输送机机型。苏联对刮板输送机的系列化,以及对机械化采煤机的配套起到重要的创新推动作用。在此基础上,1954年,英国把安德顿滚筒采煤机与垛式支架、可弯曲刮板输送机组合为综合机械化采煤机组,建成世界上第一个综采工作面。21世纪以来,世界煤炭开采的重心逐步转向我国,国外刮板输送机研发与制造影响力逐年衰减,我国逐渐成为刮板输送机的制造强国。

刮板输送机技术发展历程(四)——智能化成套装备

采煤工作面机器人群包括智能刮板输送机,它不仅要自适高效输送煤流而且要引导智能采煤机沿着工作面截割煤炭、牵引智能液压支架安全支护岩层顶板,因此刮板输送机智能性直接影响采煤机组智能性。认为,断链监测与保护技术、链张力实时感控技术、煤流量在线监测技术和机身自动调直技术是智能刮板输送机的关键感控要素,目前这些技术已达到成熟应用,为刮板输送机无人化运行提供了重要保障。自2010年起,我国刮板输送机智能化技术创新加速,研发成功超大功率、超长运距智能刮板输送机,以此构建了超级智采工作面。指出,未来刮板输送机永磁电机智能驱动、智能力感刮板链、全耐磨整体成型中部槽、数字孪生控制系统将成为新一代高级智能刮板输送机的发展方向,进而推进煤矿智采工作面进入高级智能化层次。

基于ABAQUS刮板链轮有限元分析及优化

以石窑店矿业有限公司所用刮板输送机链轮为研究对象,分析了可能对链轮疲劳破坏产生影响的因素。采用SolidWorks进行刮板链轮链环模型的创建,使用ABAQUS软件进行链轮的有限元仿真,得到了链轮链环应力集中区域。为了研究不同因素影响刮板链轮疲劳破坏的重要程度,进行了“4因素、3水平”正交试验,对试验结果进行了极差与方差分析。结果表明:齿根圆弧半径是影响链轮疲劳破坏的关键因素,而齿形圆弧半径、短齿厚度和链窝弧半径对链轮疲劳破坏的影响较小。

钻装机扒装机构斗齿根与主刀板焊接强度分析

通过SYSWELD对扒装机构斗齿齿根与主刀板焊接部分进行残余应力分析,在保持统一的焊接参数下,采用ZG22CrMnMo代替ZG25CrMnMo制造斗齿,对仿真结果进行分析,得出ZG22CrMnMo焊接变形小。通过改变焊接电流、焊接电压,得到焊接仿真结果。采用ZG22CrMnMo作为钻装机扒装机构斗齿材料满足扒装机构工作强度,在焊接电流200 A、电弧电压24 V时,焊接件的内部残余应力最小,对扒装机构的影响最小,可以增加扒装机构铲斗的使用寿命。

旋转式水稻苗床平地机设计与试验

针对标准化育秧大棚置床平地作业效率低,苗床平地精度差等问题,设计一种双旋转式叶片结构的水稻苗床平地机工作装置。确定工作装置结构参数和工作参数,分析关键部件运动参数和受力情况。通过Workbench软件分析,结果表明:关键部件的最大应力处应力为104.59 MPa;最大的总体变形仅为1.903 8 mm;前6阶固有频率在66.22~113.94 Hz之间,满足设计要求。田间试验结果表明:苗床床面最大高程差从15.8 cm下降至4.7 cm,地面相对高程标准偏差值从3.95 cm下降至0.98 cm,且作业后绝对差小于1.5 cm的测量点占比为92%,改善床面平整情况,满足当地棚室育秧需求。

打板式小区育种花生脱壳机设计与试验

针对小区育种花生量小、品种多、荚果大小不一,脱壳效率低、损伤率高、脱净率低等问题,研制了一款打板式小区育种花生脱壳机。整机主要由脱壳、清选、提升等装置组成。对关键部件参数设计进行了优化,结合打板与花生荚果的碰撞模型,通过Hertz理论分析花生荚果受到的碰撞力学特性,并结合仿真试验优化打板棱角半径为3 mm的圆角。以育种花生中的大、中、小尺寸品种花生青花Y14、花育22和白沙为试验材料,对喂入量、滚筒转速、最小脱壳间隙进行单因素试验。以脱净率和损伤率为试验指标进行回归正交组合试验,优化得到最优参数组合。试验结果表明:大、中、小尺寸花生荚果的喂入量分别为178、173、169 g/s,脱壳滚筒转速分别为356、347、375 r/min,最小脱壳间隙分别为23、22、22 mm,得到最大脱净率分别为95.43%、93.36%和94.07%,种仁损伤率分别为5.48%、5.79%和5.35%。根据得到的最优参数调整喂入量、更换凹板筛、改变脱壳间隙等步骤满足多品种种用花生的脱壳适应性。

特大型硫磺储运系统粉尘防控技术应用总结

普光天然气净化厂设计硫磺产能2.4 Mt/a,是亚洲最大的硫磺生产基地。针对该厂特大型硫磺储运系统存在的皮带输送单元落地硫磺粉尘扩散、地下廊道硫磺粉尘超标、装车单元粉尘闪爆等安全隐患,围绕固体硫磺仓储、输送、装车环节开展粉尘风险防控难题攻关,研究皮带机集成清扫、地下廊道粉尘消减及粉尘闪爆综合治理技术,形成了特大型固体硫磺储运系统全流程粉尘防控关键技术,实现了安全清洁生产,提高了装置本质安全水平。

基于MCGS的刮板链螺栓自动紧固速度控制系统研究

针对刮板链螺栓紧固的局限性,设计了一种刮板链螺栓自动紧固设备,根据刮板链螺栓紧固的工艺流程,采用SolidWorks对刮板链螺栓自动紧固设备进行几何建模。在紧固过程中,由于步进电机转速太快时力矩不足,转速太慢时,紧固时间较长,效率太差。因此设计了一种基于MCGS的刮板链螺栓自动紧固速度控制系统,通过对步进电机矩频特性和螺栓拧紧曲线进行分析,得到了步进电机转速与旋转角度的关系,从而推出步进电机速度当量与紧固时间的关系。通过对螺栓紧固时间内速度当量值进行离散,采用MCGS设计硬件和编写软件脚本,同时对人机交互界面进行组态,将设计的控制系统进行联机调试。结果表明:该速度控制系统在15 s的紧固时间内,将速度当量值从3000离散至1000,达到了螺栓紧固的力矩要求,在简化紧固过程的同时,缩短了紧固时间,实现了刮板链螺栓的自动紧固,保证了设备运行的可靠性与稳定性,提高了工作效率。

基于刮板运输机木粉小计量喂料装置研究

刮板运输机是一种用于生产运输的常用装备。针对刮板运输机运输木粉精准度不高的问题,设计可编程控制器(Programmable logic Controller,PLC)控制木粉送料的计量装置,能够实现公斤级木粉喂料。通过对装置进行改造,分为2部分,粗送料过程利用传送带进行,细送料过程由定量喂料机构完成。通过开放性生产控制和统一架构(OPC Unified Architecture,OPC UA)实现控制过程中的数据交互和人机交互过程。通过仿真验证可行性,试验得到的误差小于2%,实现装载过程中对木粉的自动准确计量。该计量装置所产生的误差较小,并且还能够实现对数据的实时显示,这对于实现定量木粉运输,加强物料定量运输作业管理有着重要的意义。

刮板输送机多永磁电机串联驱动新模式及关键技术

装备智能化是煤炭行业高质量发展的必然趋势,伴随着煤矿超大采高、超长工作面的建设,刮板输送机不断朝着重型长运距的方向发展,并且永磁直驱已逐渐取代“异步电机+减速器”成为刮板输送机的主要驱动方式,而传统双驱动刮板输送机存在停机率高、煤流分布不均且能耗大、跟踪性能差的问题,尤其长运距下链条张力波动大造成驱动电机电路涌动,已成为制约我国刮板输送机智能化发展的主要难题。根据刮板输送机面临的主要问题和发展需求,提出了刮板输送机多永磁电机串联“驱动-传动”输送新模式,并阐述了多永磁电机串联驱动刮板输送机这一研究领域涉及的关键技术研究现状,包括刮板输送机故障诊断与状态识别技术、多电机串联驱动“机-电”耦合动力学特性、多永磁电机同步控制技术、多智能体自适应协同控制,对于多驱动刮板输送机的设计研发具有一定的适应性和借鉴性;针对刮板输送机多永磁电机串联驱动系统研究面临的难题,将该系统分为4项关键科学技术:①多驱动刮板输送机新构型设计;②多驱动刮板输送机非线性机-电耦合动力学建模;③多驱动刮板输送机链条张力脉动与主动控制;④串联驱动刮板输送机主动容错与自适应协同控制;从结构设计与优化、整机运维控制实现刮板输送机多永磁电机串联驱动系统技术攻关,提高刮板输送机的智能化水平,促进煤机高端装备的水平和发展。