An exploration of an abrasive water jet cutting front profile

Abrasive water jet (AWJ) now is used as a precision cutting tool. With this tool, dimension tolerance less than 0.1 mm is expected in the cutting process. This dimension tolerance is enough for some applications. However, higher precision is necessary in order to use AWJ in some other applications. To get higher precision in an AWJ cutting process, controlling AWJ beam more accurately is needed, and this further leads to understanding AWJ cutting front more accurately. This paper compared the current cutting front profile exploration methods and then provided a new method to collect AWJ cutting front information accurately. With this new method, a better understanding of the cutting front profile is possible, which further leads to higher precision cutting of AWJ. This paper also demonstrated that the AWJ cutting front profile could be fitted by parabolic curves accurately.     

磨料水射流切割工艺参数的实验研究

磨料水射流切割中影响切割深度的因素很多,各工艺参数的选择和合理搭配对切割结果有很大影响,并且难以用精确的数学模型来描述.以磨料水射流切割混凝土为例,考察了射流压力、进给速度、靶距、磨料流量、磨料粒径和材料性能等工艺参数对最大切割深度的影响.结果表明:(1)切割深度与射流压力呈线性增长关系;(2)在一定范围内切割深度随磨料流量增加而增加,但当磨料流量达到一定值后,切割深度随流量增加反而下降;(3)切割深度随磨料粒径的增加呈先增加后减小的规律,存在一极值点;(4)切割深度随切割速度的增加呈指数衰减;(5)存在一最佳靶距,超过这个界限值时,随着靶距的增大,切割深度急剧减小;(6)混凝土试件抗压强度的抗压强度越大,切割深度越小.     

微磨料水射流切割头装置设计与研究

传统磨料水射流切割头的磨料靠负压吸入,可靠性差、吸入不均匀、流量不能精确控制。采用螺杆泵输送原理,设计了一种新型微磨料水射流切割头装置及控制系统。该装置采用螺杆泵主动送料,螺杆由步进电机驱动,单片机发出的控制脉冲控制步进电机的转速,步进电机的转速与磨料流量一一对应,从而将磨料定量、连续地送到切割头混合腔,实现磨料流量的精确控制。在混合腔的排出通道上设置单向阀门,解决了喷嘴堵塞后高压水直接进入磨料罐引起磨料输送系统失效问题。     

Monitoring of abrasive water jet (AWJ) cutting using sound detection

Our main objective in the present work is to develop a methodology and create a system for the abrasive water jet (AWJ) machining process control. In the case of AWJ cutting, besides the cutting head traverse rate, the distance between the mixing tube and the workpiece, designated as the stand-off distance, has a predominant influence on the workpiece quality. The control of the traverse rate is performed by the machine controller. The stand off-distance control during the machining represents a problem because no effective on-line in real-time stand-off distance detection system has been developed yet. The detection of the stand-off distance during cutting enables better AWJ machining process control. order to monitor the stand-off distance, we measure the emitted sound generated during the AWJ straight cut operation and analyse its characteristic attributes. In order to verify the proposed stand-off distance monitoring methods, a set of experiments was carried out. The signal analysis was performed in both time and frequency domain. The obtained results show an evident influence of the stand-off distance on sound emission. Thus, efficient control of the AWJ cutting process through sound detection appears to be viable.     

磨料浆体射流切割中添加剂的性能及试验研究

结合高聚物添加剂的特性,讨论其在磨料射流切割中的作用。研究了使用高聚物添加剂后的切割效果、特点,首次分析了磨料浆体射流中比能耗的变化趋势,并进行了相关试验结果的机理分析。     

基于改进BP网络的磨料水射流切割质量研究

目前建立的磨料水射流切割质量数学模型,对厚板材切割时,其加工精度和表面质量较难控制.基于BP神经网络学习理论,通过对网络权值和阀值进行四种方法的改进,目的是改善网络误差反向学习性能,建立低误差收敛精度、快训练速度的最佳切割质量模型.在获取大量样本数据的基础上,对最佳改进BP网络模型进行训练、预测,结果表明该模型能够快速、准确、可靠地预测磨料水射流切割质量.     

应用模糊理论预测磨料水射流切深模型的建立

以理论为基础,应用磨料水射流切割加工时的工艺参数:水射流压力、射流横移速度和磨料流量等实验数据,建立一个模糊控制模型。这个模糊控制模型可以预测在任何给定一组加工参数时,可获得的切割深度。给出磨料水射流切割铝合金实例。     

淹没磨料水射流中磨料破碎状况分析

磨料水射流中的磨料在冲蚀破碎后,颗粒的分布在一定范围内表现出自相似的分形特征.对颗粒分布进行测定并分析,得出磨料水射流中磨料颗粒在喷嘴内有破碎发生,且颗粒愈大破碎愈强烈,分析得出颗粒的分形维度可作为磨料破碎状态的一个重要指标,应用于对颗粒破碎程度的评定.     

淹没磨料水射流与非淹没磨料水射流冲蚀破岩效果比对分析

磨料水射流的冲蚀能力主要依赖于磨料颗粒所获得的能量,对非淹没磨料水射流和淹没磨料水射流的冲蚀实验结果进行比对,从能量角度和磨料颗粒速度变化角度分析了造成非淹没磨料水射流和淹没磨料水射流的冲蚀效果差异的原因。     

磨料射流切割钻杆的喷嘴设计

在高含硫油气田中,为避免剪切闸板发生硫化物应力腐蚀开裂,采用前混合磨料射流替代剪切闸板切割钻杆.将S135钻杆51/2″作为研究对象,选取圆锥带圆柱段型喷嘴.通过分析磨料粒子在喷嘴内的加速过程,对喷嘴的结构参数进行了系统研究,得出啧嘴的加速性能和收敛性能达到最佳时的具体结构尺寸.并且计算出磨料颗粒与钻杆材料接触时的最大剪应力,校核了设定参数在理论上的可行性.     

Depth of cut models for multipass abrasive waterjet cutting of alumina ceramics with nozzle oscillation

An experimental study of the depth of cut in multipass abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented. It is found that this cutting technique can significantly increase the depth of cut by an average of 50.8% as compared to single pass cutting without nozzle oscillation under the corresponding cutting conditions and within the same cutting time. Predictive models for the depth of cut are then developed. The modelling process starts with single pass cutting using a dimensional analysis technique and the particle erosion theories applied to alumina ceramics, before progressing to the development of the models for multipass cutting. The models are finally assessed both qualitatively and quantitatively with experimental data. It is shown that the model predictions are in good agreement with the experimental data with the average deviations of about 1%.     

A new cutting depth model with rapid calibration in abrasive water jet machining of titanium alloy

Titanium alloys are widely used in the aeronautical and engineering fields as they show an excellent trade-off between the mass and mechanical properties, but as hard materials, they are difficult to machine using cutting tools. The abrasive water jet affords a good solution to produce titanium parts, especially slim ones. To do so, there is a need to adopt a modelling approach for the depth milled. However, a general methodology that takes into account all the parameters leads to complex models based on a large number of experiments. The present article proposes a depth of cut model combined with a rapid calibration method. The case addressed is that of open rectangular pockets on a Ti-6AL-4V titanium alloy. The approach introduces the machine configuration notion considering that a given machine, pressure level and abrasive impose the abrasive flow rate needed in order to obtain an optimal material removal rate. For a chosen configuration, calibration of the model is performed from a series of elementary passes and just three pocket machining passes. The method is rapid and effective as the accuracy of the models obtained over a number of configurations was to within the order of 5%.     

Depth of cut models for multipass abrasive waterjet cutting of alumina ceramics with nozzle oscillation

An experimental study of the depth of cut in multipass abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented. It is found that this cutting technique can significantly increase the depth of cut by an average of 50.8% as compared to single pass cutting without nozzle oscillation under the corresponding cutting conditions and within the same cutting time. Predictive models for the depth of cut are then developed. The modelling process starts with single pass cutting using a dimensional analysis technique and the particle erosion theories applied to alumina ceramics, before progressing to the development of the models for multipass cutting. The models are finally assessed both qualitatively and quantitatively with experimental data. It is shown that the model predictions are in good agreement with the experimental data with the average deviations of about 1%.     

Study and evaluation of abrasive water jet cutting performance on AA5083-H32 aluminum alloy by varying the jet impingement angles with different abrasive mesh sizes

This article describes the experimental investigation of abrasive water jet (AWJ) cutting on AA5083-H32 aluminum alloy. In this study, the influence of varying the jet impingement angles and abrasive mesh sizes with different water jet pressures, on the output parameters for the AWJ cutting of the aluminum alloy, was analyzed. The experimental results found that the output parameters, namely, the depth of penetration, top kerf width, kerf taper ratio, surface roughness, and abrasive contaminations, were strongly influenced by the combined effect of oblique jet impingement angles and abrasive mesh sizes on AWJ. Also, it is noticed that oblique jet impingement angles have more influence on the output cutting responses than the normal jet impingement angle, and consequently, each abrasive mesh size has an influence on the different output responses for the AWJ cutting of AA5083-H32. Scanning electron microscope and microhardness tester were used to examine the different cutting regions of the kerf wall surfaces. The Energy-dispersive X-ray spectroscopy analysis was used to confirm the amount of silicon particles embedded in the AWJ cut surfaces. The adequacy checking of the experimental data for the AWJ cutting performance models has been analyzed through the residual plots using the statistical software.     

磨料水射流除锈技术仿真研究

针对钢材的锈蚀广泛存在于工业生产中并造成了很大的经济损失这一问题,从磨料水射流除锈技术角度出发,采用ANSYS/LS-DYNA有限元软件,建立了多粒子侵蚀靶板模型,对多粒子连续冲击靶板过程进行了仿真模拟,分析研究了靶板材料去除机理.为磨料水射流除锈工艺提供了一定的理论基础.通过对各种不同算例进行仿真模拟,得到了不同冲击速度、冲击角度等情况下粒子对目标靶板侵蚀情况,通过对结果进行分析比较,研究了粒子冲击参数对冲蚀过程的影响.研究结果表明,材料侵蚀率随着冲击次数的增加而增加,但是经过一定次数冲击后,目标靶板去除量达到了一种相对稳定的状态.随着冲击角度的增加,侵蚀深度增加但是侵蚀面积减小.随着磨粒直径的增加,侵蚀深度及侵蚀体积均逐渐增加.     

Research on quality improvement of the cross section cut by abrasive water jet based on secondary cutting

A manufacturing system comprises production processes and building services, both of which are supplied by different energy carriers as well as raw materials and water. These resources interact according to complex relationships and are converted into products for sale and waste flows. Holistic resource accounting allows the analyst to consider the dynamic relationships between these components, including the strong interdependence between energy and water, which has been called the energy-water nexus. Exergy analysis is a method that accounts for mass and both the quantity and quality of energy, while allowing analysis on a common basis, and for this reason, it is used increasingly to analyse resource consumption in manufacturing systems; however, it has rarely been used to consider water flows alongside energy and material flows. The main contribution of this paper is the presentation of modelling water flows in terms of exergy in the context of sustainable manufacturing. Using this technique in combination with previously developed exergy-based methods, the result is a truly holistic resource accounting method for factories based on exergy analysis that incorporates water flows. The method is illustrated using a case study of a food factory in which a 4.1% reduction in resource use is shown to be possible by employing anaerobic digester in an effluent water treatment process. The benefits of this technology option would have been underestimated compared to the benefits of waste heat capture if an analysis based on mass and energy balances alone had been used. The scientific value of this paper is the demonstration of the relatively high exergy content of effluent flows, which should therefore be regarded as potentially valuable resources. The analytical method presented is therefore of value to a wide range of industries beyond the food industry.     

磨料水射流仿真分析与试验研究

为有效保持油田的稳产增产,磨料水射流技术逐渐被应用于油田生产.磨料水射流切割利用高速混砂液体的射流来完成切割作业,具有安全、多能、环保、便捷、高效的特点.本文对前混式磨料水射流切割的喷嘴结构进行了优化设计计算,采用计算流体力学的方法,利用CFD仿真软件,对不同喷嘴类型﹑喷嘴长度和不同锥角角度的喷头的工作情况进行数值模拟...     

Predictive depth of jet penetration models for abrasive waterjet cutting of alumina ceramics

A study of the depth of jet penetration (or depth of cut) in abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented and discussed. An experimental investigation is carried out first to study the effects of nozzle oscillation at small angles on the depth of cut under different combinations of process parameters. Based on the test conditions, it is found that nozzle oscillation at small angles can improve the depth of cut by as much as 82% if the cutting parameters are correctly selected. Depending on the other cutting parameters in this study, it is found that a high oscillation frequency (10–14 Hz) with a low oscillation angle (4–6°) can maximize the depth of cut. Using a dimensional analysis technique, predictive models for jet penetration when cutting alumina ceramics with and without nozzle oscillation are finally developed and verified. It is found that the model predictions are in good agreement with the experimental results with the average percentage errors of less than 2.5%.