微磨料水射流精确送料装置设计及应用研究

针对微磨料水射流加工中磨料连续、均匀供给问题,利用螺杆泵送原理设计开发了微磨料精确送料装置。螺杆泵采用微型直流减速电动机驱动,通过相应的控制电器板控制电动机转速,从而实现磨料流量精确控制。根据实验测试数据,对磨料质量流量与电动机电压关系进行了线性拟合。计算表明,在10～24V范围,螺杆泵送磨料质量流量平均误差1·03g/min,最大误差为1·96g/min;平均相对误差0·2%,最大相对误差1·79%。该方程可以用于磨料流量精确控制方程。在现有水射流机床上应用该装置进行切割实验表明,工件切割断面的表面粗糙度平均值比传统自吸式供料系统提高2.64倍。微磨料水射流供料装置在精密加工领域具有广阔的应用前景。     

基于淹没环境的超高压后混合磨料水射流切割试验研究

利用超高压水射流切割试验系统,在80～280MPa压力范围内进行淹没磨料水射流切割试验研究,通过试验及数据分析,验证了后混合淹没磨料射流切割的可行性,得出了磨料粒径和质量流量、射流压力、靶距、切割横移速度等参数对射流切割性能的影响规律,对于脆性和塑性材料,试验中各参数对切割深度的影响基本一致.结果表明:在试验给出的工况条件下,磨料流量存在最佳值,在一定范围内切割深度随磨料流量增加而增加,当磨料流量达到一定值后,切割深度随流量增加反而下降;切割深度与射流压力基本呈线性增长关系;随着靶距的增大,切割深度逐渐减小;切割深度随切割速度的增加呈指数衰减趋势,并且相同试验工况下淹没射流切割深度要大于非淹没状态.试验结果为超高压淹没磨料水射流的实际应用和研究提供了参考.     

新型后混合式磨料水射流系统的研制

提出一种新型后混合式磨料水射流系统,是对传统后混合式磨料水射流系统的重大改进和发明。采用ANSYS Fluent对所提出的新型喷射系统进行了流场仿真,分析两个磨料入口都与大气相通和一个磨料入口与大气相通、一个磨料入口与浆体溶液相连,对这两种方式喷射系统流场进行了对比分析,并通过相应的试验验证了其流场仿真的正确性,为新型后混合式磨料水射流系统的研制提供了理论基础。然后,研制出了新型后混合式磨料水射流系统,该磨料水射流系统由供压系统、喷射系统、搅拌与输送系统组成,并进行了浆体溶液输入量测试和磨料混合效果测试,试验测试表明,该磨料水射流系统效果好、磨料混合均匀、能够实现磨料浓度的任意调节和精确控制。因此,该新型后混合式磨料水射流系统优于传统的后混合式磨料水射流系统,必将促进后混合式磨料水射流系统的更加广泛的应用。     

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.     

前混合磨料水射流切割金属火雷管研究

磨料水射流切割作业具有高能、冷态、点割、非接触等特点,在有防爆要求的危险场合下进行切割作业有独特的优势。分析磨料水射流切割雷管金属外壳的磨损机制,并分析磨料水射流切割雷管的安全性;运用前混合磨料水射流对工程中常见的金属火雷管进行冷切割实验,取得了预期的效果。     

基于稳健性设计的磨料水射流参数优化

磨料水射流加工技术是非传统的加工技术,它依靠高压、高水速和高速砂粒磨料作用在工件上去除材料,而在磨料水射流切割加工过程中存在切割深度和表面粗糙度较难控制的问题。基于稳健性设计理论、变量分析和信噪比,利用L9正交试验,对磨料水射流的压力、磨料流量、靶距和磨料粒径等加工过程参数进行优化。分析了加工参数的影响优先级,得出了磨料水射流加工参数的最优值,建立了切割深度信噪比回归模型并通过检验证明模型可靠。稳健性设计前后结果对比表明,切割深度和表面粗糙度比优化前有明显提升,从而提升了磨料水射流的加工质量。在实际加工不锈钢304中验证了结果的可靠性和该方法的可行性,为磨料水射流加工技术的推广提供了指导。     

磨料水射流工艺控制过程研究进展

综述了磨料水射流工艺控制过程的最新研究与进展;分别介绍了磨料颗粒吸入过程、水喷嘴状况和准直管工作状况以及磨损控制等方面的进展,并分析了各种方法的优缺点;提出了采用专家系统来监测切割过程中多个参数变化以优化切割过程的方法。     

高压水射流切割技术在反恐中的应用研究

介绍了高压水射流切割技术的主要原理,重点介绍了磨料高压水射流在反恐行动中的应用,并研究设计了一种在反恐行动中适用的前混合磨料高压水射流装置,为反恐行动的顺利进行提供一种行动上的保障。     

超高压磨料射流切割喷嘴装置研制及其应用

通过对水射流中磨料粒子运动形式的分析，认为结构设计参数主要是磨料射流内部靶距和磨料混合管长度，试验结果表明内部靶距为１２ｍｍ，混合管长度为５０ｍｍ切割效果较好，据此设计并研制磨料射流切割喷嘴装置，并验证了设计的合理性。     

基于模糊神经网络的磨料水射流切割质量的研究

基于模糊神经网络建立了磨料水射流精密切割的模型.工件厚度、磨料流量、加工表面的粗糙度和射流压力三个是模糊神经网络的输入,切割速度是模糊神经网络的输出.以JJ-Ⅰ水射流切割机床为实验装置,YL12硬铝作为试件材料进行实验研究,获取样本数据.试件表面粗糙度用TR200粗糙度仪测试.在MATLAB上用样本数据对模型进行训练.用训练好的模型计算给定条件下磨料水射流的切割速度,并以该速度进行线性切割.获得的切割表面粗糙度值基本符合给定的精度要求.     

微磨料水射流机床悬臂梁的有限元分析

微磨料水射流切割机床的切割精度与机床数控平台、数控系统精度以及水射流工艺参数直接有关,同时还与安装水射流切割头及其附件的悬臂梁刚度和绕曲变形有关.针对微磨料水射流机床的重要部件悬臂梁进行了Solidworks三维建模,基于ComsWorks进行了静态和模态分析.分析表明,微磨料水射流切割机床悬臂梁固有一阶、二阶、三阶和四阶频率分别为20Hz、31Hz、91Hz和104Hz.为了避免引起共振,负载频率应以一定幅度错开其固有频率.现有悬臂梁结构具有足够的刚度.     

A study on fine finishing of hard workpiece surfaces using fluidized elastic abrasives

Material removal and surface generation by erosion is the principle adopted in selected manufacturing processes like abrasive jet machining and abrasive water jet cutting. As the jet velocities involved in these processes are high, they are good for material removal. With low impinging velocities, it is possible to micro erode the surface of the workpiece to achieve good finish. To achieve low velocity impingement, abrasives could be fluidized and the target surface moved against them at the required velocities. This procedure has the limitation that fine abrasive particles are difficult or impossible to fluidize and this need to be addressed to achieve significant improvement in surface finish. For this fine abrasives could be embedded on a larger carrier particle of suitable size that is easy for fluidization. If this carrier is made of elastic material, impact erosion could further be reduced paving way for improved surface finish. In this paper, such abrasive-coated elastomeric spheres of average diameter 3 mm are termed as elastic abrasives. Based on mathematical modelling and experimental investigations, the influence of major process variables and optimal operating conditions has been arrived at. At optimum operating conditions, the surface roughness (Ra value) came down to 0.0267 μm from an initial value of 0.182 μm.     

磨料浆体射流切割机床及切割性能研究

将磨料浆体射流技术应用于切割领域，研制出相应的切割机床，避开了国外该项技术中的高压动密封问题，并对该机床的切割性能进行了正交试验，同时，将磨料浆体射流机床与前混合磨料水射流机床的切割性能进行了比较研究,　研究表明，影响磨料浆体射流切割性能的主要因素依次是切割速度、切割压力和靶距；在相同切割条件下，磨料浆体射流机床与前混合磨料水射流机床的切割力大致相同，但磨料浆体射流机床的切割质量明显好于后者，切割能耗大大低于后者。     

The optimal cutting times of multipass abrasive water jet cutting

Cutting is one of the most important applications of abrasive water jet. However, there are always some quality defects in the cross section cut by abrasive water jet. It is found that multipass abrasive water jet cutting can effectively improve the cutting quality. In this paper, two types of multipass water jet cutting were summarized and redefined clearly first. Then, taking AISI 304 stainless steel as the workpiece, the cross sections after cutting with different cutting times were analyzed and compared with that after single cutting. The overall roughness and the overall taper of the section were obtained by a reasonable method. Besides, in order to give consideration to both the cutting quality and the processing time, the concept of quality improvement rate was put forward. On this basis, with the improvement rate as the index, the optimal cutting times for cutting AISI 304 stainless steel with multipass abrasive water jet were analyzed from two aspects of surface quality and kerf taper, and the optimal cutting times of cutting other materials by multipass abrasive water jet can be studied according to the same idea. The study of this paper provides important reference for the application of multipass abrasive water jet cutting.     

PENETRATION ABILITY OF ABRASIVE WATERJETS IN CUTTING OF ALUMINUM-SILICON CARBIDE PARTICULATE METAL MATRIX COMPOSITES

This article presents a set of studies performed on aluminum-silicon carbide particulate metal matrix composites prepared by adding 5, 10, 15 and 20% of SiC in aluminum alloy and processed with abrasive water jets that are formed with garnet and silicon carbide abrasives of 80 mesh size. These studies are essentially meant to assess the penetration ability of abrasive water jets on different compositions of Al-SiC _p MMCs produced by stir casting method. Abrasive waterjet cutting experiments were conducted on trapezoidal shaped specimens of different composites as well on the constituent materials i.e., 100% aluminum alloy and 100% SiC specimens by varying water pressure, jet traverse speed and abrasive mass flow rate, each at three different levels. The percentage contribution of individual and combined effects of process parameters on penetration ability was analyzed by means of analysis of variance. Contribution of waterjet pressure and traverse speed on jet penetration in these meaterials are found to be more than abrasive flow rate. Among the interaction effects, waterjet pressure and jet traverse speed combinations contribute more to jet penetration. The results presented in this study can be used to build statistical models that can predict the depth of penetration of jet in different MMCs. This study also highlights the need to choose suitable abrasive mass flow rates and jet traverse speeds for effective processing of MMCs with abrasive water jets.     

磨料水射流切割断面质量的研究

磨料水射流(AWJ)在难加工材料切割中得到广泛应用，但由于切割断面存在斜条纹限制了AWJ的应用。研究了射流压力和切割速度对塑性和脆性材料切割断面质量的影响规律，通过对AWJ切割机理和切割过程的分析，探讨了AWJ切割断面的形貌特征及其形成机理，认为是射流断面磨料动能的分布不均和射流的偏转滞后造成了AWJ切割断面斜条纹和曲线及尖角处的尖端，可以通过喷头摆动进给和切割速度补偿两种控制设计方案来实现AWJ的高效切割。     

Studies on Recharging of Abrasives in Abrasive Water Jet Machining

The objective of this work is to find the effect of the recharging of local garnet abrasives (origin: southern India) while cutting aluminium using abrasive water jet machining. The influence of the specially formulated optimised abrasive test sample, pressure, traverse rate, and abrasive flowrate, on the American Foundrymen’s Society fineness number, depth of cut, top and bottom kerf width, kerf taper, and surface roughness are studied. The performance of the test sample has been compared with that of commercial grade abrasive with mesh size 80. Additionally, recharging studies are carried out after screening out particles of less than 90 μm. These tests help to determine the optimum recharging required.     

三相射流去毛刺工艺的试验研究

金属切削毛刺是影响精密零件棱边质量及使用性能的主要因素之一。三相射流去毛刺技术是一种柔性工艺方法。三相射流去毛刺的作用过程和机理非常复杂,不仅与射流及作用条件有关,而且与材料的性质及毛刺的形状密切相关。通过正交试验,分析了三相射流工作条件对材料去除量和冲蚀深度的影响,讨论了磨料粒度与加工表面粗糙度的关系。     

高压水磨料射流切割的力学特性与模型

通过理论分析与实验测定，分析和建立了高压水磨料射流切割的力学特性与模型；得到水射流的流量系数为０．７５，磨料射流的平均流速系数为０．９５；认为水射流主要通过水介质的滞止动压进行切割，磨料射流主要通过磨粒的冲击动压进行切割；给出了射流切断面积速度与材料破坏能量的关系曲线。     

磨料射流切割机的试验研究

本文介绍了前混合式磨料射流切割机的结构,工作原理以及用该机对金属和非金属材料进行的切割试验,指出射流工作压力、喷射靶距、喷嘴横移速度、磨料重量比浓度等是影响工作能力的主要因素,喷嘴直径及其内腔结构、磨料粒子尺寸等也是影响割缝宽度及表面形态的因素.试验对此表明,它比纯高压水射流和后混合式磨料射流切割机性能优越,是一种新型的、有广阔应用前景的工业切割设备.