单晶硅成型加工刀具损耗建模分析与实验研究

放电成型加工中的刀具损耗直接影响着加工精度,在单晶Si放电加工可行性的基础上,分析了峰值电流、脉冲宽度以及脉冲间隔对刀具损耗的影响。采用RSM中的中心组合设计实验,建立了与峰值电流、脉冲宽度、脉冲间隔等工艺参数相关的刀具损耗预测模型,用Design-Expert 8.0对刀具损耗与工艺参数的2阶响应曲面进行了分析。方差分析结果表明,预测模型具有较好的拟合程度和适应性。采用满意度函数(DFA)获得了单晶Si放电加工刀具损耗的最佳工艺参数组合,最佳工艺参数下的实验结果与模型预测结果平均相对误差为5.1%。验证实验表明,该模型对刀具损耗的预测是准确的,并且能实现相应的半导体材料的放电成型加工过程中的刀具损耗预测。     

电火花成型加工Inconel 718电极损耗及材料去除率研究

采用正交实验方法用铜电极对Inconel718合金材料进行电火花加工研究,研究了不同的加工参数(电流、周率、效率、间隙电压)对电火花加工Inconel718材料过程中的电极损耗和材料的去除率的影响,并对实验结果进行了主效应分析以及方差分析。结果表明:材料去除率随着电流和周率的增大而增大,电极损耗随着周率的增大而减小。在加工参数电流为10A,周率为100μs,效率为80%,间隙电压20V时获得较高的材料去除率;加工参数在电流为4A,周率为200μs,效率为20%,间隙电压20V时获得较小的电极损耗。     

超声加工韧性材料的材料去除率模型

超声加工是现代超声技术的重要组成部分,在不同类型材料的加工领域都有着广泛的应用.由于在超声加工中脆性材料和韧性材料的材料去除机理完全不同,因此有必要建立韧性材料的材料去除率的数学模型.本文基于接触力学的理论建立了一个新的超声加工韧性材料的材料去除率模型.通过与引用的实验结果进行比较,发现该模型的理论预测值与实验结果十分...     

超声波铣削加工材料去除率的理论模型

超声波铣削加工适于硬脆材料复杂型腔的加工，加工中影响材料去除率的因素很多，为了优化加工参数以及更好地控制加工过程，研究了各种加工参数对材料去除率的影响规律。分析了工具的高频振动、旋转以及机床进给三种运动综合作用下超声波铣削加工的材料去除机理，在传统超声波加工机理以及材料去除率模型的基础上，基于压痕断裂理论，建立了超声波铣削加工材料去除率理论模型。该模型可用于仿真实验研究及预测超声波铣削加工中的材料去除率。     

基于ANSYS的超声振动辅助气中放电加工材料去除率计算

建立了超声振动辅助气中放电加工的有限元模型,使用ANSYS分析软件对其温度场进行了数值模拟,计算出了仿真条件下的材料去除率,并通过加工试验验证了模拟结果,发现与试验结果吻合较好。结果表明,用ANSYS来计算超声振动辅助气中放电加工的材料去除率是一种行之有效的方法。     

动密封环研磨中材料去除率建模及仿真研究

液体火箭的寿命主要受发动机影响,涡轮泵又是发动机的心脏,所以涡轮泵性能至关重要,其平稳运行对火箭发动机的安全运行意义重大。影响涡轮泵稳定运行的核心问题包括轴承和密封的磨损、变形及失效等。文中围绕涡轮泵密封性中的重要组成部件——动密封环的研磨工艺进行研究。对动密封环研磨中材料去除率进行模型构建,研究其去除机理。对材料去除模型工艺参数进行仿真计算,对照研磨试验结果,把研磨加工压力、研磨转速、研磨时间工艺参数作为要素核心。所得的仿真结果可对研磨试验起到预测作用,以提高动密封环加工研磨效率。     

SiCp/Al复合材料电火花加工材料去除率及电极损耗研究

SiCp/Al复合材料因同时具有铝基体和碳化硅颗粒的综合特性,因此在具有低密度,高导热率的同时还具备了高硬度等优良特性,在各领域中备受青睐。然而具有高硬度的脆性SiCp/Al复合材料,使得传统的接触加工方式因切削温度过高,刀具磨损严重和加工精度不满足要求等问题而难以进行,电火花加工通过电极与工件间的连续放电来蚀除材料属于非接触加工,因此常被用来加工SiCp/Al复合材料。在自行搭建的电火花加工试验台上,以SiCp/Al复合材料为对象开展工艺试验,研究了不同加工参数下材料蚀除率和电极损耗对加工过程的影响,并从复合材料的蚀除特性方面分析了影响加工的原因。     

汽中电火花加工技术研究

提出了一种汽中电火花加工技术,其加工介质为水蒸汽,蒸汽由蒸汽发生器获得,经管状电极喷向工件.试验结果显示:一般情况下,材料去除率随放电电流、脉冲宽度的增大而增大,随脉冲间隔的增大而减小,但一味地增大脉冲宽度和减小脉冲间隔会造成电火花加工稳定性变差,从而降低材料去除率;汽中电火花加工技术的工具电极相对损耗率相对较低,受脉冲宽度、脉冲间隔影响小,但在大的放电电流下,电极相对损耗率会有所增加,且汽中电火花加工的工件附着物较少.     

材料成型与控制工程中的金属材料加工分析

随着社会的发展以及科技的进步,我国的工业也迎来了新的发展机遇,各行各业对于金属材料的使用也逐渐提升,尤其是汽车白车身而言,必须要加强材料成型与控制工程中的金属材料加工分析,进而有效地提升金属产品的加工质量和效率的同时,提升汽车白车身的各项性能。     

线电极放电铣削凹坑的材料去除率规律研究

线电极放电铣削加工是一种新型电火花铣削技术，它的最大优点是可通过线电极的缓慢移动来补偿加工中的电极损耗。在其加工过程中，由于较多的参数影响（包括电参数和非电参数）及复杂的放电机理，要获得理想的加工效果相当困难。为此，本文通过试验对线电极放电铣削材料去除率进行了初步研究。     

基于Pareto前沿的单晶Si放电加工工艺参数优化

针对电火花加工复杂、时变、多参数的特点,在单晶硅Si放电成型加工可行性的基础上,对材料去除率和表面粗糙度等工艺目标进行综合评价。采用中心组合设计实验综合考察峰值电流、脉冲宽度、脉冲间隔对P型单晶Si放电成型加工过程中材料去除率以及表面粗糙度的影响程度,通过响应曲面法分别获得材料去除率和表面粗糙度的二次响应模型,方差分析结果表明模型具有很好的拟合程度和适应性。以提高材料去除率和降低表面粗糙度为目标建立工艺参数优化模型,设计遗传算法对优化问题进行求解并得到Pareto最优解集。实验结果表明,料去除率的实验结果与优化预测结果平均相对误差为5.8%,表面粗糙度的实验结果与优化预测结果平均相对误差为5.3%。表明该算法能有效快速的实现P型单晶Si放电成型加工过程的工艺参数优化。     

空气中微细电火花沉积与去除可逆加工技术研究

论述了一种新的电火花加工方法。它使用通用的电火花成形加工机床,利用常见的电极材料,在空气介质中,通过脉冲放电在工件表面上沉积生长电极材料,再通过反转极性和适当的轨迹控制对所生成的沉积材料进行有选择的去除加工,进而实现材料的生长与去除可逆加工。通过对电火花加工理论的研究,预测和论证了实现这一新加工方法的可能性和实现条件。通过试验成功地将钢、铜和钨三种电极材料沉积到工件上,形成直径为 100~240 mm、高度为1 000~2 500 mm的微小圆柱体。并对沉积物进行了选择去除,实现了在同一设备上的可逆电火花加工。对沉积材料的致密性、硬度及其与工件的结合强度等进行了系统的分析,表明沉积物组织致密、坚硬,可以满足功能材料的要求。     

EXPERIMENTAL STUDIES AND MODELING OF HEAT GENERATION IN METAL MACHINING

Heat generation in the cutting zones due to plastic deformation and friction in the cutting region governs insert wear, tensile residual stresses on the machined component surface and may give rise to undesired tolerances and short component life. Therefore, it is crucial that the heat generation is kept under control during metal cutting. In this study an analytical model for prediction of heat generation in the primary and secondary deformation zones is compared with results from finite element simulations and temperature measurements using IR-CCD camera. The used cutting data are altered to study the temperature influence from tool geometry and feed when machining stainless steel SANMAC316L and low carbon steel AISI 1045.     

电火花加工过程相对放电率统计建模及分析

通过对试验数据的采集和统计分析,研究了相对放电率与伺服控制变量之间的关系,表明正态分布是相对放电率较为合适的统计模型,揭示了模型参数与伺服控制变量之间的内在联系,利用这些联系可以预报不同控制变量下的加工状态。这一理论结果得到了试验证实。     

模具曲面抛光时表面去除的建模与试验研究

提出用表面去除廓形来描述模具表面在垂直于抛光轨迹方向的抛光去除量。在假设抛光工具与模具自由曲面的接触服从椭圆赫兹接触的前提下,利用提出的抛光去除系数推导了表面去除廓形的理论方程。仿真和试验结果揭示了抛光表面去除的规律,验证了表面去除廓形的理论模型。     

ELECTRIC DISCHARGE MILLING AND MECHANICAL GRINDING COMPOUND MACHINING OF SILICON CARBIDE CERAMIC

Silicon carbide (SiC) ceramics have been widely used in modern industry. However, the manufacture of SiC ceramics is not an efficient process. This paper proposes a new technology of machining SiC ceramics with electrical discharge milling and mechanical grinding compound method. The compound process employs the pulse generator used in electrical discharge machining, and uses a water-based emulsion as the machining fluid. It is able to effectively machine a large surface area on SiC ceramics with a good surface quality. In this paper, the effects of pulse duration, pulse interval, peak voltage, peak current and feed rate of the workpiece on the process performance parameters, such as material removal rate, relative electrode wear ratio and surface roughness, have been investigated. A L₂₅ orthogonal array based on Taguchi method is adopted, and the experimental data are statistically evaluated by analysis of variance and stepwise regression. The significant machining parameters, the optimal combination levels of machining parameters, and the mathematical models associated with the process performance are obtained. In addition, the workpiece surface microstructure is examined with a scanning electron microscope and an energy dispersive spectrometer.     

纳米加工和材料去除机理研究

针对钠米技术、微型机械在未来工程应用中对纳米级加工的要求,提出将扫描探针显微镜的技术和原理应用于纳米机械加工过程,实现纳米量级加工的可控性和加工结果的可观察性。给出了采用该方法进行纳米切削加工的试验结果,表明这一方法具有稳定、可靠的微加工性能。观察结果显示了材料去除加工的微观过程,被去除材料在刃前发生剪切变形前,与之约成90°的前刀面方向上切屑已充分变形。     

SURFACE INTEGRITY AND REMOVAL RATE OF SILICON SPUTTERED WITH FOCUSED ION BEAM

This paper investigates the micromachinability of (100) silicon by focused gallium ion beam sputtering at normal incident angle. Effect of the beam parameters (dose, aperture and accelerating voltage) and the beam scanning parameters (pixel spacing, dwell time, retracing time and scanning type) on the surface integrity and material removal rate were studied. Statistical models derived from factorial experiments were used to predict the sputtered depths and material removal rates of silicon. The sputtering depth increased with higher accelerating voltage, more ion dose, shorter pixel spacing, and longer dwell time. Similar trends were found for predicting the material removal rate. A surface roughness in the range 2-5 nm was achieved, and was found to be linearly dependent on the pixel spacing.     

MODELING THE PHYSICS OF METAL CUTTING IN HIGH-SPEED MACHINING

ABSTRACT

Physical modeling of metal cutting was carried out to provide an understanding and prediction of machining process details. The models are based on finite element analysis (FEA), using a Lagrangian formulation with explicit dynamics. Requirements for material constitutive models are discussed in the context of high-speed machining. Model results address metal cutting characteristics such as segmented chip formation, dynamic cutting forces, unconstrained plastic flow of material during chip formation, and thermomechanical environments of the work-piece and the cutting tool. Examples are presented for aerospace aluminum and titanium alloys. The results are suited for analysis of key process issues of cutting tool performance, including tool geometry, tool sharpness, workpiece material buildup, and tool wear.     

MODELING THE PHYSICS OF METAL CUTTING IN HIGH-SPEED MACHINING

Physical modeling of metal cutting was carried out to provide an understanding and prediction of machining process details. The models are based on finite element analysis (FEA), using a Lagrangian formulation with explicit dynamics. Requirements for material constitutive models are discussed in the context of high-speed machining. Model results address metal cutting characteristics such as segmented chip formation, dynamic cutting forces, unconstrained plastic flow of material during chip formation, and thermomechanical environments of the work-piece and the cutting tool. Examples are presented for aerospace aluminum and titanium alloys. The results are suited for analysis of key process issues of cutting tool performance, including tool geometry, tool sharpness, workpiece material buildup, and tool wear.