关键词： 电火花加工机床   加工行业   以柔克刚   里程   模具技术   微细型腔   模具寿命   模具材料  

摘要： 模具技术的发展使型面更加复杂，微细型腔更多。而且随着对模具寿命要求的不断提高，模具材料随之更硬。对此，电火花加工机床有其独特的优越性。

关键词： 特种加工   机械制造   技术变革  

摘要： 介绍了特种加工的涵义和优点,并阐述了特种加工的种类、使用方法以及适用范围,在此基础上,对特种加工给机械制造工艺所带来的影响进行了更进一步的探讨。

关键词： NiTi   Electro discharge machining   Design of experiments   Tool wear rate   Surface roughness, Material removal rate  

摘要： NiTi is an alloy of nickel and titanium with important characteristics such as shape memory, superelasticity, high electrical resistance, high corrosion resistance, long fatigue life, and vibration absorption. The unique features of this alloy have made it useful in all types of industries. However due to these same characteristics, it is difficult to perform machining and forming operations on this alloy by traditional methods. One of the machining techniques suitable for NiTi alloy is electro discharge machining. The electro discharge machining process is one of the most practical nontraditional machining methods which are not influenced by the hardness and physical properties of the workpiece. This research intends to study the effects of electro discharge machining parameters such as voltage, discharge current, pulse on time and pulse off time on the rate of material removal, tool wear, relative electrode wear and surface roughness of NiTi alloy. For the design of experiments, the Taguchi's method for the design of experiments, L18 orthogonal array and the 'Minitab' software program have been used. The experiments indicate that the parameters of discharge current, voltage, and pulse on time have a direct impact on material removal rate (MRR), and with their increase, MRR increases as well. Tool wear rate (TWR) diminishes with the increase of pulse off time and discharge current. The analysis of results obtained for surface roughness indicates that pulse on time and off time have the highest impact on the surface roughness of NiTi alloy.

摘要： Theoretical models are developed for the continuous-wave and pulsed laser incision and cut of thin single and multi-layer films. A one-dimensional steady-state model establishes the theoretical foundations of the problem by combining a power-balance integral with heat flow in the direction of laser motion. In this approach, classical modelling meth- ods for laser processing are extended by introducing multi-layer optical absorption and thermal properties. The calculation domain is consequently divided in correspondence with the progressive removal of individual layers. A second, time-domain numerical model for the short-pulse laser ablation of metals accounts for changes in optical and thermal properties during a single laser pulse. With sufficient fluence, the target surface is heated towards its critical temperature and homogeneous boiling or "phase explosion" takes place. Improvements are seen over previous works with the more accurate calcula- tion of optical absorption and shielding of the incident beam by the ablation products. A third, general time-domain numerical laser processing model combines ablation depth and energy absorption data from the short-pulse model with two-dimensional heat flow in an arbitrary multi-layer structure. Layer removal is the result of both progressive short-pulse ablation and classical vaporisation due to long-term heating of the sample. At low velocity, pulsed laser exposure of multi-layer films comprising aluminium-plastic and aluminium-paper are found to be characterised by short-pulse ablation of the metal- lic layer and vaporisation or degradation of the others due to thermal conduction from the former. At high velocity, all layers of the two films are ultimately removed by va- porisation or degradation as the average beam power is increased to achieve a complete cut. The transition velocity between the two characteristic removal types is shown to be a function of the pulse repetition rate. An experimental investigation valid

关键词： 微尺度金属零部件   微细电火花加工技术   微细电铸加工技术   微细电解加工技术   高能束加工技术  

摘要： 概述了微细电火花、微细电铸、微细电解和高能束四种类型面向微尺度金属零部件的特种加工技术的原理、应用及研究进展;总结指出,因固有的非接触加工属性,赋予微细特种加工技术工艺柔性好、无残余应力和变形等突出优势,使得在金属微加工/制造领域展现出独特的工艺优越性。

关键词： Femtosecond pulses   In field scattering   Laser machining   Laser materials   Negative refractive index   Optical elements  

摘要： The ability of 8 picosecond pulse lasers for three dimensional direct-writing in the bulk of transparent dielectrics is assessed through a comparative study with a femtosecond laser delivering 600 fs pulses. The comparison addresses two main applications: the fabrication of birefringent optical elements and two-step machining by laser exposure and post-processing by chemical etching. Formation of self-organized nano-gratings in glass by ps-pulses is demonstrated. Differential etching between ps-laser exposed regions and unexposed silica is observed. Despite attaining values of retardance (>100 nm) and etching rate (2 mu m/min) similar to fs pulses, ps pulses are found unsuitable for bulk machining in silica glass primarily due to the build-up of a stress field causing scattering, cracks and non-homogeneous etching. Additionally, we show that the so-called "quill-effect", that is the dependence of the laser damage from the direction of writing, occurs also for ps-pulse laser machining. Finally, an opposite dependence of the retardance from the intra-pulse distance is observed for fs- and ps-laser direct writing. (C)2012 Optical Society of America

关键词： 机床企业   激光加工   市场   加工行业   超快激光器   行业形势   激光技术   企业发展  

摘要： 2012年低迷的行业形势也影响到了钣金加工行业的发展，不过作为钣金加工行业的供应商，不少激光加工机床企业却在年底频频出手——百超（天津）激光技术有限公司在津开业、德国通快集团成立新公司进军超快激光器市场。种种迹象表明，激光加工机床企业对新一年的企业发展以及市场都抱有信心。

关键词： 微细电火花加工   电极损耗   电场强度   电磁场理论  

摘要： 应用电磁场理论对微细电火花加工(Micro Electrical Discharge Machining,Micro-EDM)损耗机理进行分析,建立了加工中工具电极电场分布的数学模型。应用Comsol Multiphysics软件对此模型进行了计算与模拟,分析了电场强度的变化对电极形状变化的影响,并指出在靠近放电点位置和底部电极形状改变后,集肤效应的作用被削弱。实验验证了仿真结果和所提出损耗机理的正确性,为电极损耗补偿策略和加工精度的提高提供了理论依据。

关键词： 高合金   硼元素   铸造   加工性   电火花   高比强度   机械性能   热机械处理  

摘要： 钛和钛合金具有高比强度和较高的刚度，广泛应用在航空领域。其中，Ti-6A14V合金的应用最为广泛。然而铸态下的口晶粒较大（约为2．5mm），不利于改善合金的机械性能。为了提高合金的性能，通常采用热机械处理来获取较小晶粒，需要较高的加工费，消耗大量时间。最近，研究者发现，添加少量硼元素会明显细化铸造Ti-6A1-4V合金的口晶粒，而且在晶界处形成的项链状TiB颗粒可提高合金的强度。