侧铣式高速电弧放电加工工艺研究

侧铣式高速电弧放电加工利用电极侧面放电蚀除工件材料,能加工复杂的型腔、沟槽及直纹面等。为了探索这种新型电弧放电加工的工艺特性,探讨了峰值电流、脉宽和冲液压力等条件对工件材料去除率和相对电极损耗率的影响。实验结果表明:提高冲液压力和峰值电流均能增大工件材料去除率;相对电极损耗率随冲液压力的提高而增大,随峰值电流的提高而减小。在一定范围内,工件材料去除率随脉宽的提高而增大,相对电极损耗率随脉宽的提高而减小。     

镍基高温合金Inconel718的超高效电火花电弧复合加工

提出了一种超高效电火花电孤复合铣削镍基高温合金Ineonel718的加工方法．构建了一种新型大功率电源,主要由高压脉冲电源和低压大功率直流电源组成。在冲液和电极旋转的作用下得到了非连续电弧,材料去除率可达13421mm3／min,相对电极损耗率可达1．71％。进行了复合加工和电火花加工的对比实验研究,分析了电极转速对材料去除率和相对电极损耗率的影响,并对加工表面特性进行了研究。     

基于直流电源的短电弧铣削加工性能研究

为了探究直流短电弧铣削加工性能,分别以管状镀铜石墨为工具电极,45钢作为工件材料,分析电压、电极转速、加工深度对电极损耗率、材料去除率(MRR)和表面质量的影响规律.试验结果表明:增大电压可以有效提高MRR,但会降低工件表面质量;提高电极转速不仅能够改善工件表面质量,同时还能获得较高MRR;加大铣削深度能够大大提高MR...     

直流短电弧铣削加工GH4099的影响研究

为了探究直流短电弧铣削加工GH4099高温镍基合金的性能，采用空心管状石墨作为工具电极，以GH4099为工件材料，通过单因素试验分别分析输入电压、主轴转速以及冲液压力对GH4099的材料去除率(MRR)、工具电极损耗率(TWR)、表面质量和金相组织的影响规律。结果表明：随着输入电压和冲液压力的增大，MRR均呈现先增大后减小的趋势，TWR呈现先减小后增大的趋势；增大输入电压，热影响层变厚；适当提高冲液压力，能够降低加工中的短路现象、工件表面微裂纹和冲蚀孔洞的数量，有利于改善工件表面质量；随着的主轴转速的增大，工件表面质量也有所改善。     

紫铜电极负极性加工ZL302基础工艺试验研究

为实现铸造铝合金ZL302的高效电火花加工,在系统试验设计的基础上,进行了紫铜电极负极性加工ZL302的基础工艺试验,获得了材料去除率vm和电极损耗率vE与电参数之间的经验回归数学模型,并依此进行了工艺参数优化.研究结果表明,峰值电流ie、脉冲宽度ti是影响材料去除率vm和电极损耗率vE的主要工艺参数,电压Sv、脉冲间隔t0对材料去除率vm和电极损耗率vE等工艺指标也有影响.试验所得经验回归模型的置信度为95%,可用于指导实际生产.     

新型电火花加工电极——CVD金刚石

在电火花加工中,工具电极是一项非常重要的因素,电极材料的性能将影响电极的电火花加工性能（材料去除率、工具损耗率、工件表面质量等）,因此,正确选择电极材料对于电火花加工至关重要。     

水下电弧锯切割质量影响因子的研究

海洋、船舶、石油等领域有大量结构部件需在水下拆解。现有的水下切割方法存在效率低、结构复杂、工具或电极损耗大等局限,亟需探索新的切割方式。高速电弧放电加工具有加工效率高、电极损耗率低等优势,在难切削材料的加工中取得了良好效果。基于高速电弧放电加工原理,设计水下电弧锯切割实验装置,并对该装置极间流场进行仿真,得到不同主轴转速下极间流体流动情况。在此基础上,设计系列实验开展电流形式、主轴转速和电流值等因素对切割质量影响的研究。实验结果表明,采用高速电弧放电切割可实现工件的高效水下切割。此外,使用脉冲电流切割时的切缝质量优于直流,增大电流会改善出口处切缝宽度;主轴转速过低会影响极间排屑效果,加工中宜采用较高转速。     

工艺参数对电火花电弧高效复合加工性能的影响研究

电火花电弧复合加工解决了电火花加工效率低的问题,与电火花加工相比,其加工效率提高了数倍,针对某些材料,其加工效率甚至超过了传统机械加工,但也存在自动化程度低、电极损耗严重等缺陷。利用电火花电弧复合加工技术进行了大量实验,并以此为基础,分析了不同加工参数下的工件性能,得到在不同峰值电流、脉宽、电极主轴转速等参数下的工件加工效率、表面粗糙度及相对电极损耗率的变化规律,以期得出针对不同加工目的的最优工作参数。     

氧化锆陶瓷微孔钻削加工工艺试验研究

针对氧化锆陶瓷钻削微孔过程中出现的轴向力大和出口崩边严重的问题，使用直径为0.2 mm的金刚石涂层钻头钻削完全烧结的氧化锆陶瓷微孔，通过单因素试验方法，研究主轴转速、进给速度和步进距离对轴向力的影响，在此基础上开展啄钻工艺对比试验，探索变进给啄钻工艺对出口崩边尺寸的影响。结果表明：轴向力大小随着进给速度和步进距离的增加而增大，随着主轴转速的增加先降低后增大；采用变进给啄钻可以有效提高孔出口加工质量。     

SiC/Al功能梯度材料的电火花加工多目标参数优化及回归分析

采用正交试验与灰色关联分析相结合的方法,对Si C质量分数为5%的Si C/Al功能梯度材料进行电火花加工工艺试验,研究了工艺参数对材料去除率、电极相对损耗率的影响,同时建立了工艺参数对材料去除率、电极相对损耗率及综合指标的多元非线性回归方程。结果表明:对综合指标的影响由主到次分别为脉冲宽度、脉冲间隔、抬刀高度、加工电压、峰值电流,优化后的加工参数为峰值电流10 A、脉冲宽度200μs、脉冲间隔50μs、加工电压50 V、抬刀高度3 mm,与参数优化前相比,材料去除率降低约5.8%、电极相对损耗率降低约51.8%。建立的回归模型可为Si C/Al功能梯度材料的电火花加工试验研究提供理论指导。     

切削参数对子午线轮胎模具侧板切削比能及表面粗糙度的影响研究

以子午线轮胎模具侧板为研究对象进行铣削试验,着重研究主轴转速、每齿进给量、切削深度对轮胎模具侧板切削比能、材料去除率和表面粗糙度的影响规律。分析试验结果可知:切削比能随着切削参数的增大而减小,说明适当增大切削参数可以提高切削效率并节约能量;表面粗糙度随主轴转速增大呈先增大后减小的趋势,随切削深度和每齿进给量的增加而增大。结果表明:提高主轴转速既有利于降低切削比能(节能)也有利于改善表面粗糙度,增大每齿进给量和切削深度会降低切削比能但会恶化表面质量。因此,为同时达到高效节能和良好表面质量的要求,应尽量提高主轴转速。     

Thrust force, torque, and tool wear in drilling the bulk metallic glass

The thrust force, torque, and tool wear in drilling of Zr-based bulk metallic glass (BMG) material are investigated. Drilling the BMG at high speed generates the chip light emission, high tool temperature, and severe tool wear. At low spindle speed, the BMG work-material builds up at the major and margin cutting edges and may break the drill. A range of feasible spindle speed and feed rate for the efficient drilling of BMG without the detrimental chip light emission and cutting edge work-material build-up has been identified in this study. Under the same drilling condition, the WC-Co tool generally requires less thrust force and about the same torque than the high-speed steel tool. The progressive wear of the major and margin cutting edges for BMG drilling is examined. Severe drill wear is associated with the bright BMG chip light emission. Without chip light emission, the drill wear is visible but not severe. This study concluded that precision holes in BMG could be generated with proper selection of tooling and process parameters.     

Cutting performance of diamond tools during ultra-precision turning of electroless-nickel plated die materials

This study is an attempt (a) to observe the wear characteristic of diamond tool with 200 km cutting distance and to study the effects of wear on the surface roughness and cutting forces and (b) to optimize various cutting parameters such as depth of cut, feed rate, spindle speed and phosphorus content. The experimental results showed that tool wear was not so significant although some defects on rake face were observed after cutting 15.6 km. Further cutting showed that the surface roughness increases with cutting distance, and that the cutting forces were larger than thrust force at the beginning of cutting, but after cutting 130 km, thrust force became larger and increased rapidly. It was also observed that forces increase with the increase of depth of cut, spindle speed and feed rate, and decrease with the increase of phosphorus content of the plating. Depth of cut has no significant effect on surface roughness, while it increases with increase of feed rate and decreases with the increase of percentage of phosphorus content in the workpieces. In case of spindle speed, surface roughness decreases with the increase of spindle speed up to a certain value and then starts to increase with the increase of spindle speed.     

钻削B4C颗粒增强铝合金工艺参数对刀具磨损和孔尺寸精度影响的分析和优化

基于刀具磨损和钻孔尺寸误差等多个性能指标,对B4C颗粒增强铝合金切削加工参数进行评估和优化。通过Taguchi的L27,3水平4因子正交阵列进行实验设计。研究结果表明：磨粒磨损和积屑瘤一般在刀具磨损时形成,同时,边角磨损也具有重大意义。影响切削刀具的侧面磨损主要决定因素是合金中的颗粒质量分数,其次分别是进给速率、钻头的硬度和主轴转速。在所有使用的刀具中,有TiAlN涂层的硬质合金钻头在刀具磨损以及孔尺寸方面具有最佳性能。灰关系分析表明：钻头材料的影响比进给速度和主轴转速的影响更大。在最佳的钻探参数下可以得到最小的刀具磨损和孔直径误差。     

小直径磨棒磨削加工TiC颗粒增强钢基复合材料GT35

为探究TiC颗粒增强钢基复合材料GT35合理的加工参数和冷却润滑条件,研究其对切削力、表面质量及刀具磨损的影响规律,采用小直径磨棒以侧面磨削方式开展试验。结果表明：干磨削会引起磨棒烧伤,极压磨削油的润滑效果优于水基合成磨削液的;磨棒在极压磨削油润滑下,磨削工件12 min后进入稳定磨损状态,其主要磨损形式为磨粒破碎、磨粒磨耗和磨粒脱落;主轴转速对切削力的影响大于进给速度的,且转速越高,切削力越小;工件表面粗糙度主要与磨棒磨粒出露高度的平整度有关,受加工参数的影响较小。用小直径磨棒磨削加工GT35材料时,应选择极压磨削油润滑,高主轴转速、中速进给的加工方式,以获得良好的刀具寿命、工件加工表面质量及适当的加工效率。     

微沟槽织构对切削力和表面粗糙度的影响

为研究微织构对切削过程中产生的切削力和已加工表面粗糙度的影响,在聚晶立方氮化硼(PCBN)刀片前刀面制备与主切削刃平行的宽度为32.6μm的微沟槽织构。分别用微沟槽刀具和无织构刀具在主轴转速为450、500、600 r/min的条件下切削淬硬钢GCr15,分析切削力和已加工表面粗糙度。试验结果表明:微沟槽改善了刀具的切削性能,主切削力、进给力和切深力均小于无织构刀具;进给力、切深力随着主轴转速的增加均变大,主切削力表现为先减小再增大;用微沟槽织构刀具切削的已加工表面粗糙度大于无织构刀具,表明微沟槽不利于获得表面质量较好的工件;随着主轴转速增加,微沟槽刀具和无织构刀具切削的表面粗糙度均减小。     

Investigation of the effects of electrode orientation and fluid flow rate in near-dry EDM milling

This research investigates the effects of electrode lead and tilt angles and dielectric fluid flow rate on material removal rate, tool electrode wear ratio, and surface roughness in near-dry electrical discharge machining (EDM) milling process. Computational fluid dynamics (CFD) model is developed to predict the dielectric fluid flow rate and qualitatively compare with the experimentally measured EDM material removal rate. The optimum lead angle, which maximized material removal rate and minimized tool electrode wear ratio, was found. The decrease in the lead angle has a negative effect on the roughness of machined surface. The increase in tilt angle reduces the material removal rate and increases the tool electrode wear ratio. The change in tilt angle does not have a significant effect on the surface roughness and can be used to prevent gouging in finishing EDM milling. This study shows that the material removal rate is linearly proportional to the mass flow rate of air and kerosene mixture, the tool electrode wear ratio is inversely related to the mass flow rate of air and kerosene mixture, and the average surface roughness does not have a good correlation with the flow rate of the mixture.     

SiCf/SiC陶瓷基复合材料超声振动辅助切削试验研究

开展了SiCf/SiC陶瓷基复合材料的超声振动辅助切削试验研究,对比研究超声振动辅助切削及普通切削条件下切削参数对切削力的影响规律.结果表明:SiCf/SiC陶瓷基复合材料超声振动辅助切削时优选钎焊金刚石磨头,超声振动辅助切削相较于普通切削的切削力降低了10％～20％,主轴转速、进给速度、切削深度都会影响超声振动辅助切...     

CNC microturning: an application to miniaturization

Micromachining is the basic technology of microengineering for the production of miniature components. One group of tool based micromachining technology is CNC microturning. It is a conventional material removal process that has been miniaturized. The objective of this study is to asses the machinability of brass, aluminium alloy and stainless steel during external cylindrical longitudinal microturning process for different workpiece–tool combinations. Experiments were carried out by varying the depth of cut, feed rate and spindle speed. One parameter was varied while the other two were kept constant in order to identify the best combination of cutting parameters. Machinability assessment was done by force analysis, chip analysis and tool wear criterion. Microshafts were fabricated with brass, aluminium alloy and stainless steel. Finally, microturning process was successfully applied to fabricate compound shaped micropins of diameter less than 0.5 mm.