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.     

高压水射流切割效能研究

高压水射流切割效能受到多方面的影响,针对目前使用的高压水射流设备和技术,分析了影响高压水射流切割效能的因素,并提出一些提高措施。     

Properties of cutting oils with additives of liquid crystals

The effect of liquid crystalline compounds on the behavior of cutting oils in friction and machining is demonstrated by experimental data. Improvement of the cutting characteristics and tool durability and reduction of the roughness of the machined surface are established.     

钴结壳水射流切削系统参数设计

为了避免刀具切削钴结壳时产生冲击载荷,提出了深海钴结壳水射流切削方法。采用仿真计算和实验测试研究了水射流系统参数与其切削性能的作用规律。仿真结果表明:水射流系统的工作压力、喷距和喷射角度是决定水射流切削能力的主要参数;其重要程度依次为工作压力、喷距和喷射角度;提高水射流系统工作压力是提高射流切削能力最有效的方法;在射流工作压力一定的情况下,为了提高射流的切削能力,射流的喷距宜小于4 mm(4倍喷嘴直径)内,射流的喷射角度约为13°。实验结果表明:提高射流的工作压力可以显著提高射流的切削能力,减小射流的喷距有助于提高射流的切削能力,射流的最优喷射角度约为13°。     

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。     

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.     

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.     

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.     

液体射流研磨循环系统设计

液体射流研磨技术是在水射流加工技术的基础上发展起来的。目前,制约该技术在高精度机械产品加工中广泛应用的主要原因是高压研磨系统的开发制造。介绍了一套前混合磨料液体射流研磨循环系统,分别论述了低压研磨液产生系统、高压液压油产生系统、高压研磨液产生系统等主要部分的作用及相关参数的选择原则。     

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。     

射流切割中高压缸的设计研究

基于高压缸的应力分布特点,由第四强度理论推导出了高压缸最大应力（缸筒内壁处）的出量应力的计算公式,建立了缸筒内压与缸筒径比及持久极限的量化关系。这些关系对于如何设计缸筒具有一定的指导意义。     

基于PMAC的水喷射加工机床开放式数控系统的开发研究

介绍了以PC机为平台、以PMAC为核心的水喷射加工机床开放式数控系统给出了该系统的硬件和软件结构及设计。     

An apparatus that analyzes the hydroabrasive wear of fiberglass pipes

A hydroabrasive wear analyzing apparatus has been developed which makes it possible to study wear resistance of various materials and coatings in hydroabrasive flow simulation. The paper shows efficiency of the developed apparatus for testing various materials and coatings being subject to hydroabrasive effect. After a 96-h test, the developed apparatus obtained comparative characteristics of the resistance to hydroabrasive wear of fiberglass pipes with and without polyurethane coating.     

基于MFC+STM32的数控裁床喷墨笔绘切割控制系统设计

针对数控裁床在裁剪形状类似以及面积较小制品时,生产者无法用肉眼快速区分制品的问题,研究了一套集喷墨、笔绘和切割于一体的控制系统.基于MFC开发了一套上位机控制系统应用程序,并结合基于STM32的下位机运动控制系统,最终实现将产品信息喷涂以及笔绘在制品上,方便生产者快速识别制品.并通过服装样片应用实例验证了系统设计的可行...     

Transient liquid jet breakup model and comparison with phase doppler measurements

A new liquid jet breakup model is developed based on the transient breakup mechanism and incorporated into the KIVA-II code. Liquid column is considered as a chain of balls. Rayleigh-Taylor instability and Kelvin-Helmholtz instability was applied to the liquid jet column. Liquid jet column is continuously surveyed to apply breakup mechanisms. Once liquid droplets are separated from the main liquid jet column, these droplets are subjected to the single breakup mechanism. When Bond number is greater than a critical Bond number, single droplets continue to break up by Rayleigh-Taylor instability or Kelvin-Helmholtz instability. Computational results were compared with the PDPA measurement data. Gross behavior of the spray and detailed droplet sizes and velocities predicted by KIVA calculations which include proposed drop breakup model are compared with those produced from droplet size/velocity measurements.     

Study of liquid jet instability by confocal microscopy

The instability of a liquid microjet was used to measure the dynamic surface tension of liquids at the surface ages of ≤1 ms using confocal microscopy. The reflected light from a laser beam at normal incidence to the jet surface is linear in the displacement of the surface near the confocal position, leading to a radial resolution of 4 nm and a dynamic range of 4 μm in the surface position, thus permitting the measurement of amplitude of oscillation at the very early stage of jet instability. For larger oscillations outside the linear region of the confocal response, the swell and neck position of the jet can be located separately and the amplitude of oscillation determined with an accuracy of 0.2 μm. The growth rate of periodically perturbed water and ethanol∕water mixture jets with a 100-μm diameter nozzle and mean velocity of 5.7 m s(-1) has been measured. The dynamic surface tension was determined from the growth rate of the instability with a linear, axisymmetric, constant property model. Synchronisation of the confocal imaging system with the perturbation applied to the jet permitted a detailed study of the temporal evolution of the neck into a ligament and eventually into a satellite drop.