磨料水射流喷嘴收缩段锥角对磨料粒子混合程度的影响

介绍了磨料水射流的起源、用途、特点及抛光原理,针对混合腔内磨料粒子与高压水束混合不均匀而影响抛光表面质量及磨料砂管使用寿命的缺陷,通过对磨料水射流切割喷嘴结构的研究,建立了对称双管供料喷嘴几何模型,并运用CFD软件对喷嘴内部流场进行仿真研究,分析了喷嘴收缩段锥角对磨料粒子和高压水束混合均匀程度的影响。研究结果表明:选择30°和45°的收缩段锥角有利于延长砂管使用寿命及提高磨料粒子与水射流的均匀混合,从而在抛光加工中提高工件表面质量。     

几何结构参数对磨料水射流喷嘴磨损规律影响的模拟分析

建立了前混合磨料水射流喷嘴物理模型。基于FLUENT软件,采用颗粒轨道模型、Grant弹性恢复系数和E/CRC磨损模型对磨料水射流喷嘴内的磨损特性进行了数值模拟。结果表明:当喷嘴收缩角为20°以上时,喷嘴磨损呈现两个严重磨损区,分别在喷嘴圆柱段入口处前较短距离范围内和喷嘴圆柱段出口处前较短距离范围内;随着喷嘴收缩角的增大,磨料颗粒与喷嘴圆柱段壁面碰撞次数和速度增加,同时随着喷嘴长径比的增大,喷嘴圆柱段壁面磨损速率整体增加,严重磨损区范围扩大,结果均使喷嘴圆柱段的磨损加剧。以喷嘴壁面磨损速率的面积加权平均积分表征喷嘴整体的磨损程度。随着收缩角和长径比的增大,喷嘴壁面磨损速率的面积加权平均积分增大,喷嘴的磨损整体而言越严重。因此,从减小喷嘴磨损的角度而言,喷嘴的收缩角和长径比宜取小值。     

磨料水射流抛光技术及其发展

磨料水射流抛光技术是应用于表面抛光加工的新技术.利用含有细小磨料粒子的抛光液在高压作用下,与工件表面发生冲击、冲蚀而微去除材料,以达到抛光目的.论述了磨料水射流抛光技术的基本原理和特点,以及影响抛光效果的主要工艺参数,并对其发展趋势进行了展望.     

高压水射流切割技术发展及应用现状

作为一种高能束流加工技术,高压水射流切割因其独特的切割模式,被广泛应用于机械加工、食品医疗、海洋工程等领域。介绍了高压水射流切割技术的切割机制及磨料混合机制,并就其研究进展和应用现状做了相关总结和概括,为今后水射流技术的研究和发展提供了参考。     

一种磨料水射流试验工作台的研制

介绍了磨料水射流试验工作台的系统组成及其工作原理，通过分析磨料水射流加工的工作机理给出了喷射系统的结构及部分参数。试验表明，通过调整工艺参数，本磨料水射流试验工作台可对材料进行表面抛光、去毛刺、清洗、剥层、切割等加工和实验。     

磨料水射流切割面粗糙度研究

对在磨料水射流切割过程中进给速度和磨料流量两点进行了讨论。磨料颗粒采用直径为80目的石榴石。测量了切割不同深度的粗糙度。实验结果表明:对切割表面影响最大的是切割速度。同时也研究了切割面粗糙度和磨料水射流其他参数之间的关系。     

高压磨料射流中流体因素的影响研究

依据固液两相流理论,应用FLUENT流体分析软件对高压磨料射流喷嘴内外流场进行数值模拟和仿真,通过改变流体的黏度、流量、密度等,讨论了各参数对出口处的切削力和速度分布的影响。结果表明：增加流体的密度对射流速度和切削力的提高效果明显;而增加其黏度作用正好相反,由于流动阻力加大,使射流的出口速度快速衰减,出口界面切削力下降;工作介质流量的改变对入口速度和射流效果也有较大的影响;在工作环境和设备允许的情况下,可以适当提高进口流量。     

基于量纲分析法的一种磨料水射流打孔模型

水射流的加工过程中非常复杂,涉及到许多参数,对其模型的描述也较为困难。运用量纲分析法,选取对加工过程中影响较大的参数,忽略影响很小的因素,建立了水射流打孔过程的新数学模型,并通过试验验证该模型的误差仅为3%～10%。     

Characteristics of abrasive slurry jet micro-machining: A comparison with abrasive air jet micro-machining

Abrasive slurry jet micro-machining (ASJM) uses a well-defined jet of abrasive slurry to erode features in a solid target. Compared with abrasive water jet machining (AWJM), the present ASJM system operates at pressures that are roughly two orders of magnitude lower and uses a premixed slurry of relatively low concentration. The objective of the present study was to gain a better understanding of the mechanics of erosion in ASJM by comparing its performance in the micro-machining of holes and channels in borosilicate glass with that of abrasive air jet micro-machining (AJM), a process that is simpler and relatively well understood. A new ASJM system was developed and used to machine blind holes and smooth channels of relatively uniform depth that did not suffer from the significant waviness previously reported in the literature. The effect of particle velocity, particle concentration, jet traverse speed and jet impact angle were examined. A direct comparison of ASJM and AJM results was possible since novel measurements of the crushing strength of the aluminum oxide abrasive particles used in both experiments proved to be unaffected by water. Brittle erosion was shown to be the dominant material removal mechanism in both ASJM and AJM in spite of the significant flow-induced decrease in the local impact angles of many of the particles in ASJM. A new model of the rapid particle deceleration near the target surface helped explain the much smaller erosion rates of ASJM compared with those in AJM. The modeling of the erosion process during the micro-machining of channels showed that the effect of the local impact angle at the leading edge of the advancing jet was much more significant in ASJM than in AJM, primarily due to the narrower focus of the jet impact zone in ASJM. The differences in the water and air flow fields and associated particle trajectories were used to explain the steeper side walls and flatter bottoms of the holes and channels machined with unmasked ASJM compared to those with masked AJM. The respective structures of the water and air jets also explained the much sharper definition of the edges of these features using ASJM compared with maskless AJM. The results of the study show that ASJM can be used to accurately micro-machine channels and holes with a width of 350–500 μm and an aspect ratio of 0.5–1.3 without the use of masks.     

基于后混合式磨料水射流磨料颗粒运动研究

为了改善后混合式磨料水射流的切割性能,以固液两相流理论为基础,通过FLUENT模块对喷嘴内磨料的运动进行建模和数值分析。以聚焦管内的单个颗粒为研究对象,优化传统的颗粒相控制模型,获得磨料颗粒在喷嘴内基本的运动情况。研究表明,磨料颗粒吸入混合腔后通过各相之间的碰撞进入高压射流,形成液固两相流。两相流形成初期,磨料颗粒的速度在高压水射流的携带作用下迅速上升。由于混合腔内部结构突变等原因,颗粒相速度浮动较大且处于非稳态。当颗粒通过收敛段进入聚焦管后,颗粒相速度以指数形式逼近射流相速度并逐渐稳定。但由于存在沿程能量损失等因素,颗粒相速度与射流相速度始终存在滑移,最终颗粒相速度仍略小射流相速度。     

硬质合金刀片刃口钝化方法与实验研究

为了改善硬质合金刀片刃口钝化的质量,克服现有钝化方法的不足,根据磨料水射流作用下材料去除理论,分析磨料水射流对硬质合金刀片刃口钝化的材料的去除机制,提出了运用磨料水射流对硬质合金刀片刃口进行钝化的新方法,通过理论分析和实验验证该方法的可行性。该方法的运用能提高硬质合金刀具的效率、质量和寿命,确保刀片钝化参数的一致性,并取得了较好的效果,对硬质合金刀片刃口钝化具有重要的意义。     

不锈带钢磨料水射流除鳞工艺研究

除鳞参数的选择在很大程度上影响着除鳞效果,为了提高不锈带钢磨料水射流除鳞效果,在简述磨料水射流的除鳞机理和主要工艺参数的基础上,通过实验研究了不锈带钢磨料水射流除鳞系统参数与除鳞效果之间的关系,在尽量保证外部条件不变的情况下,采用参数依次寻优的方法进行实验,并应用图像处理技术和最小二乘法对实验结果进行处理分析,找出了不锈带钢磨料水射流最佳除鳞参数组合,包括系统压力、流量、带钢移动速度、靶距及磨料浓度。基于最优参数的除鳞系统既可以提高除鳞效果,改善产品质量和结构,也可以降低生产成本。     

高分子添加剂对磨料水射流切割质量的影响

通过磨料水射流和在磨料水射流中加入不同浓度高分子添加剂切割大理石的对比实验,测量了在不同工况下切缝表面不同位置测点的粗糙度。试验结果表明:在相同工况下,高分子添加剂磨料水射流较磨料水射流能减小切缝表面粗糙度,提高切缝表面质量;不同浓度高分子添加剂磨料射流对切缝表面粗糙度影响不一,存在最优浓度为3×10~(-4);磨料水射流切割中,走刀速度过慢和过快时获得切缝表面最小表面粗糙度的靶距较正常走刀速度大;高分子添加剂磨料射流切割中,不同走刀速度下获得切缝最小表面粗糙度的靶距趋向一致。     

磨料水射流喷嘴结构参数对流场性能影响的仿真与研究

建立后混合磨料水射流喷嘴可视化模型,利用FLUENT软件对喷嘴内固液两相流场进行仿真,分析管嘴内流场的速度以及管嘴结构对它的影响。为了达到理想的速度,混合腔长度应选择高压水喷嘴直径的40倍左右;聚焦管长度在60~70 mm之间最优;综合考虑速度及磨损,锥形角角度应选择在30°~45°之间。     

后混合磨料水射流切割系统的研究

后混合磨料水射流是极具发展前景的一种冷态加工工艺。对后混合磨料射流切割机的工作原理及主体组成进行了分析,并针对IE-B型超高压水射流切割机所存在的不足进行了改进。结果表明：改进后的磨料水射流切割机解决了原有设备密封性能差、可靠性低、维护成本高等多方面的问题。     

基于拟水平正交实验法的磨料水射流切割性能研究

磨料水射流切割作为一种新型的冷切割技术,凭借较强的切割能力和良好的切割质量,越来越多的应用到工程领域中。为了探究不同切割参数对磨料水射流切割性能的影响,采用拟水平法设计实验方案,进行钢板切割实验。实验结果表明:射流的切割能力与泵压和切割转速成正相关,喷嘴直径和切割靶距存在一个最佳范围,堆积作用和淹没状态都对切割性能有不同程度的影响。     

便携式磨料水射流系统切割X60钢的试验研究

磨料水射流切割技术能够满足油气储运设备设施应急抢修切割的需求。通过切割试验研究了便携式磨料水射流切割系统对管线钢的切割特性,得到压力、靶距和横移速度对切割深度的影响关系,提出了切割深度预测模型。结果表明:切割深度与切割压力成正比,与靶距和横移速度成反比。切割深度模型对切割结果预测的最大误差为15.04%,最小误差为0.87%,平均误差为5.98%,表明切割深度模型在一定参数范围内能够有效指导切割工艺的制定。     

Cryogenic wet-ice blasting—Process conditions and possibilities

In the present article frozen and deeply chilled water-ice particles, with a temperature of around −100 °C, act as a blasting abrasive. For accelerating cryogenic ice particles the process of injector blasting is used. The advantage of this abrasive at these low temperatures lies in the complete absence of residues after processing. Abrasive water-ice particles turn back to water by melting. Possible applications for this innovative process are especially complex components that can be easily deburred and cleaned. The production process of deep frozen ice particles will be described and first practical deburring test results will be shown.     

Experimental method for the investigation of the abrasive water jet cutting quality

The use of the declination angle for a prediction and control of the abrasive water jet cutting quality is presented in the paper. The term declination angle is defined and the method for its measurement is proposed. The relationship between the declination angle and cutting wall quality is explained in the theory resulting from former conclusions of Hashish, Zeng and Kim, Hlavá? and others. Experiments proving the theoretical base were performed. The values of the limit traverse speeds predicted from the theoretical equations were compared with values experimentally determined on selected samples. The data calculated from the theoretical models predicting the appearance of the striations on the cutting walls by cutting head tilting are compared with experiments as well.