切削深度对微细轴类零件加工精度影响的实验研究

金属切削过程中，不同的切削参数对零件的加工精度影响是不同的。通过车铣和车削两种加工方法的对比，重点研究了切削深度对微细轴类零件加工精度的影响问题。通过对实验结果的分析显示，车铣加工和车削加工微细轴时切削深度的变化对加工精度的影响很小，一般情况下可以忽略。     

微细机械加工技术

随着微型机械的应用领域进一步拓展,微细机械制造加工技术得到了快速发展.在介绍了微细切削加工、微细电火花加工、微细蚀刻以及微细电解加工的基础上,对其加工特点和性能进行了比较,讨论了微细机械加工发展的方向与关键问题.     

基于车铣复合加工技术的微细丝杠切削研究

车铣复合加工技术能实现以铣代车或磨高速切削回转体零件。基于此技术的微细切削无论是在生产率还是在加工表面质量上,较其它加工技术而言,更适合于微细轴类零件和具有复杂型面的微小型零件的加工。通过微细车铣切削微细丝杠试验,从切削用量和加工质量及刀具磨损方面研究了车铣复合加工技术在解决微细丝杠加工中的应用。结果表明,基于车铣复合加工技术能够实现微细丝杠的高速切削。该技术非常适合于微细丝杠零件加工。     

微细超声复合电加工技术与应用

为进行微器件及零件表面微结构的精微制作,提出微细超声复合电加工技术。构建、完善加工参数可较大范围调节的微细超声复合电加工系统,进行复合电加工机理研究;用组合放电微细加工方法,制作出可满足试验及实际加工要求的多种截面、尺寸的微细工具电极;进行多参数超声复合电加工试验研究,结果表明微细超声复合电加工技术具有加工效率高、精度好及成本低的技术优势。分析储油微结构对摩擦副表面摩擦学特性的影响规律,用超声复合电加工技术制作摩擦副表面储油微结构,摩擦学试验证明储油微结构可使摩擦副表面摩擦因数减小,磨损量降低。     

微细轴切削加工特性分析

分别采用传统的车削方法和先进的车铣方法进行微细轴的切削加工试验,从切削方式、切削速度、切削力等9个方面对两种切削方法进行了比较。试验结果表明,车铣技术更适合于微细轴类零件的加工,它在改善微小型零件的切削状态、实现高速切削、降低切削力、延长刀具寿命、保证零件加工质量、提高加工效率等方面都具有明显优势,只要合理匹配车削主轴与铣削主轴的转速比,同时合理辅以其他切削用量,就可以加工出理想的微小型零件。     

高精密微细切削加工机床的研制

微细切削技术的发展离不开微小型化机床设计和制造技术的发展,然而微细切削加工的高精度对微细切削机床的性能和设计提出了更高的要求。因此,针对微细切削机床设计和研制的特点,自主研发了一台微小型切削加工机床,该机床可应用于微细车削、刨削、飞切等加工方式。其设计理念是,利用大理石气浮导轨结合精密直线电机技术,提高机床的精度和加工稳定性。     

精密及微细电火花加工(二)

2精密型孔加工实现精密和微细加工,除了制作合格的电极、具备相应的电加工机床和脉冲电源外,熟练地掌握合理的加工工艺是重要关键。     

业界动态

世界机床行业技术发展新动向复合化加工趋势明显。金属切削与特种加工复合有了新进展,激光、电加工与切削加工复合技术已经有了成熟的产品。复合加工技术的推广应用     

大长径比微细轴的车削工艺研究

微纳米级器件的加工是MEMS系统的开发、应用的关键技术之一。通过切削试验,设计出能加工最小直 径为7 μm的微细轴的金刚石车刀,其主要参数为:主偏角Kr=93°,副偏角Kr'=300°前角γ0=0°,后角α0=5°。 然后以加工直径20 μm的轴为例,分析了进给量、背吃刀量以及主轴转速对微细轴成形和表面粗糙度的影响。研 究结果表明,在微细轴的加工中,切削用量不仅对工作表面质量产生影响,而且关系到是否能够车削成形。在可 成形范围内,进给量与表面粗糙度值成正比,具有显著的影响;背吃刀量、主轴转速对表面粗糙度的影响较小。 最后试制了不同加工参数条件下的极限实例产品。     

超微细切削加工的技术难点及对策

分析了超微细切削加工的机理、特点及技术难点 ,并对最小切削厚度与刀具刃口圆弧半径的关系进行了量化分析。讨论了切削过程中的微振动、刀具的磨损和崩刃、材料的微量切削加工性、机床的动特性、加工环境的稳定性等因素对超微细切削过程的影响 ,并提出了解决措施。     

Research on improvement of machining accuracy of micro-rods with electrostatic induction feeding ECM

Micro-rods were machined by electrochemical machining using the electrostatic induction feeding method, with which ultra-short current pulse duration of several tens of ns can easily be obtained. A tungsten plate and stainless steel (SUS304) rod were used as the tool electrode and workpiece, respectively. To improve the machining accuracy, the machining characteristics when the workpiece is fed in the axial and radial directions were investigated using NaCl aqueous solution as the electrolyte. When fed in the axial direction, the machinable length of the micro-rods was found to peak at the optimum feed speed because of the influence of pitting corrosion and collision between electrodes. When the workpiece was fed in the radial direction, the influence of pitting corrosion decreased, however, the micro-rod was shortened with increasing feed distance in the radial direction because of the stray current flowing through the end of the micro-rod. The simulation results of the material removal process agreed qualitatively with experimental results. Next, machining characteristics were compared between the electrolytes, NaCl and NaNO₃ aqueous solutions, by feeding the workpiece in the axial direction. It was found that the influence of pitting corrosion was eliminated with the NaNO₃ aqueous solution, and there was no machinable length limitation with suitable feed speeds. In addition, the taper angle and gap width were smaller with the NaNO₃ aqueous solution, compared with those of the NaCl aqueous solution. Stainless steel micro-rods of 100 μm in diameter with a high aspect ratio of 20 were fabricated with the NaNO₃ aqueous solution. According to the preliminary research results, the machinable minimum diameter of the micro-rods was investigated and micro-rods with an average diameter of 9 μm and length of 78 μm were machined successfully.     

Research of micro EDM/ECM method in same electrolyte with running wire tool electrode

A micro rod machining method which can switch between electrical discharge machining (EDM) and electrochemical machining (ECM) by attaching/detaching a diode to/from a bipolar pulse generator in parallel to the working gap was newly developed using a wire electrode made of tungsten. The problem of the wire electrode wear was eliminated by the use of the wire electrochemical turning (WECT) method in which the tungsten wire electrode is continuously running. The ultra-short bipolar pulse current was generated by the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a feeding capacitance. The machining characteristics of three types of wire guide; disk-shaped WC guide, laminated wire guide and cylindrical acrylic guide, were studied. The experimental results showed that the cylindrical acrylic guide has the best machining characteristics without the influence of guide wear and with less stray current flowing through the working gap. Using the cylindrical acrylic guide, the influences of the feeding capacitance C₁, and the total amplitude of the pulse voltage on the machining characteristics were studied. Finally, a stainless steel SUS 304 micro-rod with a high aspect ratio of 14 was fabricated efficiently by using the EDM and ECM modes for rough and finish machining in sequence with the same setup, pulse generator, and neutral electrolyte.     

假肢接受腔阳模刀位插补方法及其误差比较

在分析假肢接受腔阳模数控加工特点的基础上,针对三坐标数控铣加工,讨论了直接法、退刀法、矢量法三种典型刀位计算方法在接受腔阳模加工中的应用,分析了加工误差的来源及其分布,并给出了逼近误差和刀具补偿误差的计算方法。通过加工实验,验证了三种刀位计算方法的有效性和误差分析方法的正确性。实验结果表明:直接法简单,但加工误差大,只适合于粗加工;退刀法复杂,加工误差大,不适用;矢量法复杂,误差小,适用于阳模加工刀位的插补计算。     

法向圆弧锥齿轮数控加工研究

研究了法向圆弧锥齿轮的数控加工原理与技术,设计了成形铣刀,给出了刀具与工件的接触条件以及刀具与工件之间的相对运动。斜航式法向圆弧锥齿轮数控加工实验表明,该锥齿轮数控加工原理正确,工艺简单,且加工精度较高。     

不同机加工表面微观形貌的特征分析

以机加工标准样块为对象,研究了不同机加工表面形貌粗糙度的差异,分析了不同机加工获得表面形貌的特征,以及观察了同种机加工方法获得的不同粗糙度表面形貌。结果表明：各种机加工方法获得标准样块的表面形貌及其粗糙度值都存在着不同程度的差异;不同机加工表面形貌微细结构致密度和轮廓高度峰值都各不相同,这与其加工机制有关;同种机加工获得不同粗糙度的表面形貌结构具有自相似性,而且具有典型的形貌结构特征,可用于区分不同机加工方法。     

开式三元叶轮高效率数控粗加工策略

论述了五轴数控粗加工的高效铣削策略和关键技术,对于影响数控粗加工效率的主要因素进行了分析,对于高速钢铣刀和硬质合金铣刀采用侧铣和插铣数控加工方法以及刀具选择进行了简要叙述,并且通过大量三元叶轮实际加工总结了一种面向三元叶轮加工特征、考虑刀具寿命的粗加工策略的原则,使三元叶轮的加工效率大大提高。     

数控电火花线切割加工工艺研究

通过分析数控电火花线切割加工的原理，介绍了数控电火花线切割加工的特点及其应用，对数控电火花线切割加工工艺进行了研究和探讨，并对数控电火花线切割中常见的问题，提出了处理意见。     

精密球超精密加工技术的研究进展

掌握精密球超精密加工过程中的球面研磨轨迹分布特性以及各工艺参数对加工结果的影响,对提高精密球加工精度与效率十分重要。对精密球超精密加工技术的发展及研磨均匀性的评价进行回顾,并根据精密球超精密加工技术的发展脉络,阐述当前主要精密球超精密加工技术的加工原理及加工实例。从材料去除率、加工精度、批一致性等方面对几种精密球超精密加工技术进行比较,并以提高加工精度及加工效率为目标,对精密球超精密加工技术的发展趋势进行预测。     

Optimization of cryogenic milling parameters for aluminum honeycomb treated by ice fixation method

This paper presents the first comprehensive investigation that aluminum honeycomb has inevitable machining defect in milling process, such as deformation, burr, and collapse. Ice fixation method was used to clamp workpieces, and inner-injection liquid nitrogen was employed for a series of cryogenic milling machining. In the machining process, the main machining parameters including in honeycomb orientation, milling width, cutting depth, cutting speed, and feed were executed experimental research. Meanwhile, the machining parameter optimization, range, and significant analysis were adopted to analyze the influence of machining parameters on the machining surface quality, as well as the optimal parameter combination and milling machining surface quality were predicted and verified. The results show that the ice fixation aluminum honeycomb method with cryogenic milling is much advanced than that of conventional ones, and many machining defects are effectively restrained. At the same time, the influence of machining parameters on machining qualities in descending order is cutting depth, cutting speed, honeycomb orientation, feed, and milling width. The minimum roughness value (Ra?=?0.356 μm) of the predicted machining surface is similar to the actual machining result (Ra?=?0.362 μm). It verifies the feasibility of the optimization method. Furthermore, it is proved that the ice fixation + liquid nitrogen cooling method has a positive effect on the high milling quality and implement efficiency for aluminum honeycomb and other difficult-to-machine materials.     

Investigation of electro-discharge micro-machining of titanium super alloy

Being a difficult-to-cut material, titanium alloy suffers poor machinability for most cutting processes, especially the drilling of micro-holes using traditional machining methods. Although electrical discharge machining (EDM) is suitable for machining titanium alloys, selection of machining parameters for higher machining rate and accuracy is a challenging task in machining micro-holes. The present research attempts to optimize micro-EDM process parameters for machining Ti-6Al-4V super alloy. To verify the optimal micro-EDM process parameters settings, metal removal rate (MRR), tool-wear rate (TWR), over cut (OC) and taper were chosen as observed performance criteria. In addition, four independent parameters such as peak current, pulse-on time, flushing pressure, and duty ratio were adopted for evaluation by the Taguchi method. From the ANOVA and S/N ratio graph, the significant process parameters and the optimal combination level of machining parameters were obtained. It is seen that machining performances are affected mostly by the peak current and pulse-on time during micro-electro-discharge machining of titanium alloy. Mathematical models have been developed to establish the relationship between various significant process parameters and micro-EDM performance criteria. In-depth studies have also been made to examine the influence of various process parameters on the white layer and surface topography through SEM micrographs of machined micro-hole.