掘进机截割速度变化过程分析

为更准确地探讨截割头对掘进机截割性能的影响规律,提高掘进机截割效率,延长截割头及截齿使用寿命,该文用显示动力学对掘进机截割头截割煤岩时过程进行分析。以Creo、ANSYS/LS＿DYNA为模拟计算程序,截割头平行截割工况下进行模拟,利用不同速度进行分析比较,通过观察截割头的应力云图及受力情况,做出了梳理及总结,为掘进机截割头的设计工作及使用效率优化提供了理论依据。     

纵轴式掘进机截割机构纵向随机振动的仿真研究

为了了解纵轴式掘进机的纵向振动特性,提高机器工作的可靠性,分析并确定截割头随机载荷的数学模型,利用拉格朗日方法建立了该型掘进机的纵向动力学模型,通过拉氏变换法对动力学方程解耦,得到了其3阶固有频率和振型.为进一步探究截割头与悬臂、悬臂与机体的刚度对截割头和悬臂振动的影响,利用虚拟激励法求得截割头、悬臂的纵向位移响应,并在ADAMS中对整机多刚体动力学模型仿真,验证了该方法的可靠性.研究结果表明：系统的纵向振动固有频率在6 Hz内,通过增加悬臂与机体的刚度能明显减小外随机激励作用下截割头和悬臂的振动.所得结论为改进掘进机设计和参数优化提供理论依据.     

基于FNN-PID的掘进机截割头升降控制算法研究

针对悬臂式掘进机截割头存在的升降操作控制精度不足的问题,该文建立了截割头升降控制系统数学模型,应用FNN算法对PID参数进行优化,同时用MATLAB对传统PID控制器、FUZZY-PID控制器以及FNN-PID控制器进行仿真试验,分别对比3种控制算法的控制性能指标。试验结果表明,FNN-PID控制器可以更好地满足截割头升降控制系统的控制要求。     

悬臂式纵轴掘进机截割头参数对截割性能的研究

悬臂式纵轴掘进机是被广泛应用于井下巷道掘进作业的一种综合性煤矿巷道掘进设备。本文针对悬臂式纵轴掘进机,重点研究了单个工作截齿截割时受力的受力情况,建立了截割受力的数学模型。此外,结合ebz-75型掘进机实际工作条件,对截齿受载进行了数值仿真,为改进和完善截割机构的设计,提高掘进机工作性能提供了理论参考。     

纵轴式掘进机截割头的设计

本文介绍了纵轴式掘进机截割头的设计原则,讨论了提高截割头截割效率的合理方案,提供了设计用的主要数据。     

截割头组件卧式镗铣床夹具的设计

通过对掘进机截割头组件的大量研究,总结出截割头体形状、截齿座位置共性。设计出截割头组件在卧式镗铣床上加工的通用夹具。     

掘进机截割头镐齿设计与有限元分析

按照掘进机截割头设计要求完成截割头运动规律分析，镐齿的空间排列与载荷计算，并对镐齿进行有限元分析。     

掘进机数字化自动截割系统

通过高精度矿用位移传感器采集截割头动作数值,可编程序控制器自动控制截割头动作,实现巷道立面的数字化切割。系统已成功应用于本公司EBH360型掘进机。     

掘进机截割头体、截齿座焊接组对工装的设计

在煤炭、铁路、公路、水利等行业高效自动化、智能化采掘的今天已广泛使用掘进机进行巷道掘进。截割头是掘进机进行截割煤岩、半煤岩、岩石的关键部件。随着研发人员对煤岩、半煤岩、全岩破岩机理的不断深入研究，对截割头的设计要求更加科学化、合理化，对制造的要求更为精细化。为适应不同型号截割头的设计要求，针对满足小批量多品种生产的需要。设计出满足各种参数要求的截割头体、截齿座焊接组对工装，解决了工装定位准确性、通用性的难题。     

截齿截割煤岩的LS_DYNA仿真模拟

研究应用LS_DYNA软件进行煤岩截割破碎仿真的程式与方法,对悬臂式掘进机截割头上镐形截齿截割煤岩进行仿真模拟,在hypermesh中建立有限元网格模型,调用LS_DYNA971求解器进行求解,研究不同切削角对截齿截割阻力的影响以及切削厚度与比能耗之间的关系,并与常用的截齿截割阻力公式计算结果相比较,仿真结果证明了建模...     

Bubble cutting circuits

An inhomogeneous applied field can cause an instability in a strip domain that can be used for the controlled generation of bubble domains. These instabilities have been studied experimentally and theoretically by means of a variational calculation. Good agreement is obtained between wall shape calculations and experimental data. Predictions of cutting current as a function of strip width deviate, however, for widths larger than ∼5.5h due to the limitations of the model and the experimental conditions.     

聚能切割技术在水平井连续油管切割中的应用

将环形聚能切割技术应用于水平井连续油管遇卡事故处理中,可以解决连续油管在水平井中的遇卡事故。针对2英寸连续油管的特点,设计了一种聚能切割弹及连接装置马笼头,主要从切割弹结构设计、药型罩结构设计、装药选择、马笼头结构设计及施工工艺等方面进行了研究。通过地面切割试验、现场应用,设计的聚能切割装置,及电缆传输工艺实现了水平井中遇卡连续油管的切割解卡,操作简便、施工安全。     

聚能切割技术在水平井连续油管切割中的应用

将环形聚能切割技术应用于水平井连续油管遇卡事故处理中,可以解决连续油管在水平井中的遇卡事故。针对2英寸连续油管的特点,设计了一种聚能切割弹及连接装置马笼头,主要从切割弹结构设计、药型罩结构设计、装药选择、马笼头结构设计及施工工艺等方面进行了研究。通过地面切割试验、现场应用,设计的聚能切割装置,及电缆传输工艺实现了水平井中遇卡连续油管的切割解卡,操作简便、施工安全。     

Study of cutting fiber-reinforced composites by using abrasive water-jet with cutting head oscillation

An experimental and theoretical research work on abrasive water-jet (AWJ) oscillation cutting of glass fiber reinforced polymer (GFRP) composite materials was conducted at the Water-jet Laboratory of the Industrial Research Institute of Swinburne (IRIS). The objective of this research work was to conduct a comparative study of the oscillation and normal (without head oscillation) cutting of GFRP composite materials and compare the performances the two processes. This new technique which is a variant of the traditional AWJ cutting technique, makes use of a back and forth motion of the cutting head which is superimposed on the normal linear motion to effect optimum loading of the cutting forces on the workpiece material and scan the cut-wall surface to also improve surface finish. The technique was used for cutting GFRP composites materials and the qualities of resulting surfaces were measured using stylus type equipment. A comparison of the results indicates that there is significant improvement in the quality of surfaces produced by head oscillation technique than normal AWJ cutting. In some of the samples, an improvement, in surface quality, as measured by R_a values, up to 20% was found.     

Critical rake angle and cutting forces prediction in the orthogonal cutting of polymers

An experimental investigation has been carried out into the machining of polymers which exhibit both anisotropic and normal stress sensitive characteristics. The cutting mechanism is analysed using a modified shear angle relationship based on the mechanical properties of the chosen polymers and the minimum energy criterion. From cutting tests, the material shear stress is estimated and hence cutting forces calculated. The presence of a critical rake angle at which the normal force equals zero has been confirmed. The value of critical rake angle can be estimated from force predictions. The coefficient of friction for polymers was found to decrease with increasing the normal force on the tool rake face.     

Comparative study of the effect of surface texturing on cutting tool in dry cutting

Recent researches in the field of dry machining have indicated that surface texture has the potential to influence tribological conditions. Researchers have studied the application of controlled surface microtextures on cutting tool surfaces to improve machining performance by changing the tribological conditions at the interfaces of tool–chip and tool–work piece. An experiment to study the performance of the microtextured high-speed steel cutting implement within the machining of steel and aluminum samples was performed. Surface textures were introduced using Rockwell hardness tester, Vickers hardness tester, and by scratching with diamond dresser on the face of single point cutting tool. Machining in dry conditions was applied on mild steel (EN3B) and aluminum (AA 6351) samples using lathe machine with microtextured and traditional cutting tool for the constant range of feed, depth of cut, and for varying range of cutting speeds. Measurement of cutting force, cutting temperature, and surface roughness of the work surfaces after machining were made. The results showed reduction in cutting forces and cutting temperature with textured tools in comparison with those of the untextured tool. Chips collected from different samples were studied under a microscope and the results showed that textures created on the tool surface by various methods exhibited variations in chip formation. Cutting tools without texture and with texture were comparatively studied and the outcomes of the experimental study are presented in this paper.     

Optimization of cutting fluid performance

This paper describes a new drilling test (Upton 1997) for the evaluation of cutting fluid. The technique is based upon a procedure which relies on gathering performance data from tests using the same drill with different fluids, or lubricant concentrations, rather than determining the lifetime or wear rate of individual tools. The results presented here, are used to illustrate the findings for changes in fluid concentration. This non lifetime method is useful because fluids can be quickly compared, and assessed by reference to cutting force analysis and component surface finish measurement. (Upton 1996) Alternative life tests tend to be more expensive because they require a greater volume of fluid, larger quantities of workpiece material and are time consuming. Despite the trends towards 'dry cutting' and low friction tool coatings, there is still a need for cutting fluids because of their ability to improve product quality, remove heat and swarf from the tool/workpiece interface and increase tool life. Improvements in cutting fluid performance are desirable because of ongoing costs associated with fluid use, maintenance and subsequent disposal. Increased environmental awareness and health and safety considerations also dictate that new formulations are introduced.     

Shear cutting of PET film

Poly (ethylene terephthalate) (PET) film was extruded and then successively biaxially stretched and thermofixed to obtain a high-strength film with stable dimensions. Next, the film was shear cut by two rotating circular knives. In the first part of this paper, a microscopic evaluation of the sheared edges of films, cut under a variety of parameters, i.e. cutting speed, film thickness and knife angle, is given. A particular cutting defect, namely the formation of fibres, is discussed. In the second part, a theory for the shear cutting process of PET film and the related fibre formation is presented. Special attention is paid to the influence of the film manufacturing parameters (applied in this study) on the behaviour of the material during shear cutting.