磨料水射流加工技术的研究现状

磨料水射流加工是一种新型的特种加工方法，由于它具有无热影响、加工力小、多功能等优点，已越来越多地应用于一些难加工材料的切削加工中。文中综述了磨料水射流的切割性能、切割机理、切割模型的建立以及提高加工表面质量的方法。最后综述了磨料水射流在车削、铣削和钻削中的应用。     

Multiresponse Optimization of Abrasive Water Jet Cutting Process Parameters Using TOPSIS Approach

This paper describes how optimization studies were carried out on an abrasive water jet (AWJ) cutting process with multiresponse characteristics based on Multi Criteria Decision Making Methodology (MCDM) using the Technique for Order Preference by Similarity Ideal Solution (TOPSIS) approach. The process parameters water jet pressure, traverse rate, abrasive flow rate, and standoff distance are optimized with multiresponse characteristics, including the depth of penetration (DOP), cutting rate (CR), surface roughness (R_a), taper cut ratio (TCR), and top kerf width (TKW). The optimized results obtained from this approach indicate that higher DOP and CR and lower R_a, TCR, and TKW were achieved with combinations of the AWJ cutting process parameters, such as water jet pressure of 300 MPa, traverse rate of 120 mm/min, abrasive flow rate of 360 g/min, and standoff distance of 1 mm. The experimental results indicate that the multiresponse characteristics of the AA5083-H32 unit used during the AWJ cutting process can be enhanced through the TOPSIS method. Analysis of variance was carried out to determine the significant factors for the AWJ cutting process.     

Optimising the AWJ cutting process of ductile materials using nozzle oscillation technique

Striations and roughness on workpiece surfaces produced by abrasive waterjet (AWJ) have been the most persistent problems that stand in the way of wider applications of the technology in industry. This paper presents the experimental investigation on the impact of using nozzle oscillation cutting technique in minimising or reducing these AWJ cut surface irregularities. The technique was used for cutting ductile materials, i.e. mild steel and aluminium, at various traverse speeds, oscillation angles and frequencies of oscillation. The results show that by oscillating the nozzle during cutting, the improvement in surface finish as measured by centre-line average R_a can be obtained by as much as 30%.     

电火花线切割加工与磨料水射流加工质量的对比研究

针对快走丝电火花线切割加工和磨料水射流加工,笔者从尺寸精度、表面粗糙度及微观表面形貌等几个方面对两种加工方法进行了试验研究。分析结果表明,在试验条件下快走丝线切割φ20mm圆和20mm×20mm正方形的尺寸误差分别为0.08和0.04mm;磨料水射流切割同样尺寸试件的平均尺寸误差分别为0.09和0.1625mm,但磨料水射流切割加工试件存在一定的锥度。在试验条件下,快走丝线切割试件和磨料水射流切割试件表面粗糙度为Ra2.197μm。显微照片表明,电火花线切割样品表面有烧伤黑色区域、凸凹不平的小坑以及不同尺寸大小的熔融球状物,揭示出电火花线切割对材料熔化蚀除加工的本质;磨料水射流切割表面布满了小沟槽,揭示了高速流体和粒子流物理蚀除加工的机理。     

INVESTIGATION ON NEW TYPE OF DOUBLY BLENDING ABRASIVE WATER JET NOZZLE SYSTEM WITH HIGHER PERFORMANCE

Based on the two existing abrasive water-jet(AWJ) systems, the dia-jet (or pre-jet) and the post-jet, a new type of abrasive water-jet system is put forward, which combines the dia-jet's advantage, low operating system pressure, slender stream jet, and more concentrative abrasive in the blended stream, with merits of post-jet, the less sophisticate apparatus, successive supply of abrasives. The theoretic analysis is brought out in detail, and the nozzle system structure is concisely illustrated. Its relevant experiment results are demonstrated, proving that this new system is effective in various aspects, enlarging penetrating capability without raising system pressure, saving machining power supply, lessening energy loss, etc.     

前混合原理用于井下便携式水射流切割机设计中的特点分析

通过对前混合和后混合磨料射流能量传递过程和切割过程的分析,得出了前混合和后混合磨料射流切割能力的数学关系。通过前混合和后混合磨料射流切割的实验验证了其方程结果。得出了在相同输入条件下前混合磨料射流的切割能力是后混合的10倍以上的结果。     

基于人工神经网络的磨料水射流切割加工模型

作为一种冷态加工新工艺 ,磨料水射流 (AWJ)以其独特的优点得到广泛应用 ,但由于高速液固两相流本身的特性 ,AWJ切割加工是一个受多参数影响的复杂随机过程 ,很难建立一个适当的机理模型。基于人工神经网络理论 ,本文建立了切割厚度与主要工艺参数间的AWJ切割加工预测模型 ,模型预测结果与实验值及Zeng的经验模型进行了比较 ,该网络模型能可靠、准确地映射出AWJ的加工规律 ,可应用于AWJ切割加工过程的参数优化选择、加工规律计算机仿真及智能化控制中。     

Processes and apparatus developments in industrial waterjet applications

This paper is based on an abrasive waterjet cutting process that helps solve problems in processing of modern hard-to-cut materials, enabling wider industrial application. A detailed explanation of the recent developments in the main components of abrasive waterjet systems are given. Factors such as water pressure, grain diameters of abrasive feed rate, and traverse speed influencing surface roughness and depth of cut are studied using experimental data. Taking account of industrial applications, advantages–disadvantages, and limitations of the process are assessed.     

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.     

Advances in metals and alloys for joint replacement

Metals, ceramics, polymers, and composites have been employed in joint arthroplasty with ever increasing success since the 1960s. New materials to repair or replace human skeletal joints (e.g. hip, knee, shoulder, ankle, fingers) are being introduced as materials scientists and engineers develop better understanding of the limitations of current joint replacement technologies. Advances in the processing and properties of all classes of materials are providing superior solutions for human health. However, as the average age of patients for joint replacement surgery decreases and the average lifespans of men and women increases worldwide, the demands upon the joint materials are growing. This article focuses solely on advances in metals, highlighting the current and emerging technologies in metals processing, metal surface treatment, and integration of metals into hybrid materials systems. The needed improvements in key properties such as wear, corrosion, and fatigue resistance are discussed in terms of the enhanced microstructures that can be achieved through advanced surface and bulk metal treatments. Finally, far reaching horizons in metals science that may further increase the effectiveness of total joint replacement solutions are outlined.