超大孔径聚晶金刚石拉丝模具单向走丝电火花线切割加工工艺研究

基于试验研究,创新性地提出了采用单向走丝电火花线切割机床对超大孔径聚晶金刚石拉丝模具的孔形进行粗加工。以金刚石粒度为25μm的直径22 mm、厚度20 mm的超大孔径聚晶金刚石拉丝模具为例,进行单向走丝电火花线切割加工定径区、压缩区和安全角的工艺研究,得出了加工工艺曲线,确定了最优加工工艺参数,提高了粗加工效率,确保了良好的孔形精度。结果表明:选择脉冲宽度4μs、脉冲间隔40μs、峰值电流15 A、走丝速度10 m/min时,可获得较满意的加工效果。     

PCD刀具电火花线切割磨削机床的研制

研制了用于加工聚晶金刚石(PCD)刀具的电火花线切割磨削机床,完成了机床总体方案、各运动进给轴及单向走丝系统的机械结构设计。机床具有较高的位置精度和表面粗糙度,可广泛应用于各种复杂形状的PCD刀具制作,具有以割代磨的技术特点。     

电火花线切割机床技术发展方向的探讨

电火花线切割是精密金属零件加工重要手段之一。零件加工效率、精度等方面的变化以及智能制造将决定未来电火花线切割机床技术发展方向。把握电火花线切割机床未来技术发展的方向有利于行业整体技术水平的提升。     

电火花、线切割加工技术系列丛书征订

数控电火花线切割加工技术内容包括 :数控电火花线切割原理 ;电火花线切割机床 ;线切割编程 ;线切割微机编程 ;线切割控制 ;电火花线切割脉冲电源 ;电火花线切割工艺 ;电火花线切割机床的精度检验方法。本书由张学仁教授主编 ,刘晋春教授主审。本书 2 8.4万字 ,每本定价 14.50元 ,2 0 0 0年 2月出书。电火花加工技术讲述电火花加工的原理和机理 ,电火花穿孔、成型加工的机床、脉冲电源、控制系统、工艺规律及各类典型模具和零件的加工实例和要点。本书由赵万生教授主编 ,刘晋春教授主审。本书约 2 8万字 ,每本定价 14.50元 ,2 0 0 0年 5月出…     

特种加工机床行业“十二五”发展目标

特种加工机床行业的主要产品包括电加工机床、激光加工机床、快速成形机床等。根据中国机床工具工业协会特种加工机床分会编制的《特种加工机床行业十二五发展规划》,到十二五末,包括电火花成形机床、电火花线切割机床、电火花高速小孔加工机床、电化学加工机床等通用产品及各类专用设备在内的电加工机床年产值约73亿元,年产量约7万台;包     

征订及书讯

《电加工与模具》为双月刊,国内外公开发行。广大读者可在当地邮局订阅,也可直接向本刊编辑部邮购。每期定价5.50元,全年6期共33元。 　　邮发代号：28-36 　　地址：苏州市人民路531号 　　邮编：215005 　　电话：：0512-7274541 　　传真：0512-7778215 数控电火花线切割加工技术 　　内容包括：数控电火花线切割原理;电火花线切割机床;线切割编程;线切割微机编程;线切割控制;电火花线切割脉冲电源;电火花线切割工艺;电火花线切割机床的精度检验方法。本书由张学仁教授主编。 电火花加工技术 　　讲述电火花加工的原理和机理,电火花穿孔、成型加工的机床、脉冲电源、控制系统、工艺规律及各类典型模具和零件的加工实例和要点。本书由赵万生教授主编。 　　● 每本书定价加邮费均为18元 　　● 购书款请汇至：［215005］苏州市人民路531号 　　　　　　　　　　　　　　　　　　　　　《电加工与模具》编辑部     

往复走丝电火花线切割机床的发展动态

概述了电火花线切割机床的发展简况,着重分析了往复走丝电火花线切割机床在加工性能、加工范围、加工表面质量和加工精度等方面所取得的实质性进展,指出随着我国经济的持续发展,往复走丝电火花线切割机床的市场容量将不断扩大。     

进口电加工机床的初步调查分析(下)

三、进口电火花线切翻机床共性技术的初步分析我国电火花线切割机床的年产量现已达到2500台左右,在振兴国民经济中起了重要作用。近年来,国内引进了相当数量的电火花线切割机床。在模具加工中,特别是在较精密的模具制造中,起了一定的促进作用。与之相比,我国的线切割加工机床与工艺水平还有一定的差距。因此对进口的电火花线切割机床,包括高频电源、数控功能与切割工艺作一分析比较,使国内同行对此有比较具体的了解,对提高我国电火花线切割水平,发展电火花线切割的装备与工艺,或许     

往复走丝电火花线切割加工技术的发展与定位

40多年来,往复走丝电火花线切割机床已在各行业的加工中越来越广泛、大量地应用,其特有的工艺能力是其他加工手段难以替代的,同时因其价格低廉、运行成本低、切割厚度大,故应用量远大于单向走丝电火花线切割机床,市场潜力巨大,发展前景     

我国特种加工行业2014年十件大事

一、数控机床重大专项电加工新一轮课题实施
　　◆精密、高效、数控单向走丝电火花线切割机床：
　　（1）高效数控单向走丝电火花线切割机床;
　　（2）七轴联动数控电火花高速小孔加工机床;
　　（3）新一代飞机钛合金格栅网板数控电火花高效加工技术及专用机床。
　　◆航天复杂零部件超精密微细电火花加工装备与技术：
　　（1）大型精密六轴联动数控电火花成形机床;
　　（2）航天复杂零部件超精密微细电火花加工装备与技术。
　　◆电加工关键技术及工艺数据库与数控系统集成开发。     

聚晶金刚石电火花磨削加工效果预测和加工参数优化仿真系统

建立了聚晶金刚石电火花磨削加工效果预测及加工参数优化仿真系统，可以预测聚晶金刚石电火花磨削加工后的效果，具有较高的精度，并能实现加工参数的优化，进行优势因素分析。通过工艺数据库的建立，该仿真系统可以适用于各种材料的加工工艺，有助于进一步提高聚晶金刚石加工的自动化程度和开发智能化系统。     

Drilling of graphite/bismaleimide composite material

Drilling study of graphite/bismaleimide composite material was conducted by using different cutter materials (high-speed steel, carbide, and polycrystalline diamond) and drill geometries. It was found that polycrystalline diamond tools outperformed all other tools in terms of minimal surface damage, delamination, and fiber pullout. The drilling forces exerted in machining graphite/bismaleimide were recorded by using a dynamometer, and the morphology of drilled surfaces was evaluated with surface profilometry and optical and scanning electron microscopy. The drilling characteristics were evaluated in terms of cutting forces, tool wear, and surface morphology.     

PCD刀具加工强化复合地板中磨损行为的断裂力学研究

本文首先利用断裂力学的理论，分析了聚晶金刚石刀具切削过程中的沿晶和解理两种磨损特征及其形成过程。通过采用SYNDITE聚晶金刚石刀具对Al2O3颗粒表层强化复合地板的切削加工实验，验证了理论分析的正确性。研究表明聚晶金刚石刀具铣削Al2O3表层强化复合地板的过程中，刀具的磨损特征主要由沿晶磨损和解理磨损组成。并且，理论和实验结果表明刀具的磨损特征受到金刚石晶粒尺寸的影响。粗粒度聚晶金刚石易产生解理磨损形貌，细粒度的聚晶金刚石易产生沿晶磨损形貌。同时，研究表明微观裂纹特征对聚晶金刚石刀具的磨损起着重要的作用。     

Study on wear mechanisms and grain effects of PCD tool in machining laminated flooring

Polycrystalline diamond (PCD) tools have gained increasing application in woodworking industry for the phenomenal tool life and cutting finish compared with carbide tools. In the paper, machining experiments with PCD tools were conducted to mill laminated flooring with Al₂O₃ overlay. Four kinds of PCD products with different original diamond grain sizes were used to fabricate the cutters. Wear volume was measured by optical microscopy and wear morphology was examined by SEM and optical microscopy.The experimental results show that the wear mechanisms of PCD tools, in the machining process, involve inter-granular wear and partial cleavage fracture. The microcracks in PCD tools are a key reason for the wear of tools. By comparing the flank wear, the experiments reveal that PCD tools with middle original diamond grain size have long tool life. The influences of original diamond grain size on cutting edge and wear properties have also been discussed in detail.     

CVD金刚石薄膜涂层整体式刀具的制备与应用

化学气相沉积(chemical vapor deposition,CVD)金刚石薄膜具有硬度高、摩擦系数低、耐磨性强以及表面化学性能稳定等优异的机械及摩擦学性能,这使其在硬质合金工模具领域具有广阔的应用前景.本文采用热丝化学气相沉积法(hot filament chemical vapor deposition,HFC...     

Micro-cutting characteristics of EDM fabricated high-precision polycrystalline diamond tools

To fabricate three-dimensional microstructures, such as micro dimples, micro grooves and micro channels, on ceramic mold materials, tool fabrication with super hard materials is an essential step. In this work, micro electro discharge machining (EDM) was used to fabricate high-precision polycrystalline diamond end mills. Form accuracy and edge sharpness in one micron level were achieved by utilizing electro discharge induced graphitization of diamond grains under extremely low discharge energy conditions. The cutting performance of the fabricated tools was examined by machining micro dimples and micro grooves on tungsten carbide mold substrates. Results showed that using the EDM-fabricated tools, ductile mode machining of tungsten carbide was realized with a surface finish of 2 nm R_a, which is comparable to that produced by polishing.     

Comparative investigation of smooth polycrystalline diamond films on dental burs by chemical vapor deposition

Depositions of hot filament chemical vapor-deposited diamond on cobalt-cemented tungsten carbide (WC-Co) rotary cutting dental burs are presented. Conventional dental tools made of sintered polycrystalline diamond have a number of problems associated with the heterogeneity of the crystallite, decreased cutting efficiency, and short life. A preferential (111) faceted diamond was obtained after 15 h of deposition at a growth rate of 1.1 μm/h. Diamond-coated WC-Co dental burs and conventional sintered burs are mainly used in turning, milling, and drilling operations for machining metal ceramic hard alloys such as CoCr, composite teeth, and aluminum alloy in the dental laboratory. The influence of structure, the mechanical characteristics of both diamond grains and hard alloys on the wear behavior, as well as the regimen of grinding on diamond wear are considered. Erosion wear properties are also investigated under air-sand erosion testing. After machining with excessive cutting performance, calculations can be made on flank and crater wear areas. Diamond-coated WC-Co dental burs offered significantly better erosion and wear resistance compared with uncoated WC-Co tools and sintered burs. This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in St. Paul, MN.     

Nanocrystalline diamond coating tools for machining high-strength Al alloys

Diamond coating tools have been increasingly used for machining advanced materials. Recently, a microwave plasma-assisted chemical vapor deposition (CVD) technology was developed to produce diamond coatings which consist of nano-diamond crystals embedded into a hard amorphous diamond-like carbon matrix. In this study, the nanocrystalline diamond (NCD) coating tools were evaluated in machining high-strength aluminum (Al) alloy. The conventional CVD microcrystalline diamond coating (MCD) tools and PCD tools were also tested for performance comparisons. In addition, stress distributions in diamond coating tools, after deposition and during machining, were analyzed using a 2D finite element (FE) thermomechanical model.

The results show that catastrophic failures, reached in all except one machining conditions, limit the NCD tool life, which is primarily affected by the cutting speed. In addition, coating delamination in the worn NCD tools is clearly evident from scanning electron microscopy (SEM) and force monitoring in machining can capture the delamination incident. At a high feed, coating delamination may extend to the rake face. Furthermore, SEM observations of coating failure boundaries show intimate coating-substrate contact. Though the NCD tools are inferior to the PCD tools, they substantially outperform the MCD tools, which failed by premature delamination. The diamond coating tools can have high residual stresses from the deposition and stresses at the cutting edge are highly augmented. Further machining loading causes the stress reversal pattern which seems to correlate with the tool wear severity.     

PCBN刀具切削性能和磨损机理研究综述

聚晶立方氮化硼(PCBN)刀具是继聚晶金刚石刀具之后的又一种超硬刀具,以其独特的“以车代磨”、“硬态加工”、“干式切削”等方式被誉为21世纪的绿色环保刀具。PCBN刀具在金属切削方面具有广泛的应用,主要用来加工各种淬硬钢、耐磨铸铁等铁基材料。本文介绍了PCBN刀具成分、几何形状、切削参数等对其切削性能的影响,在此基础上分析了不同材料加工时刀具的主要磨损机理,还简单对比了硬质合金和PCBN刀具切削性能上的差异。      

High Speed Face Milling of a Aluminium Silicon Alloy Casting

High speed machining of aluminium silicon alloy castings has gained significant interest from automotive industry involved in the development of the new generation of lightweight vehicles. This paper investigates the influence of workpiece microstructure, namely the secondary dendritic arm spacing (SDAS), tool material and geometry on tool wear mechanisms, cutting forces and surface integrity when face milling at cutting speeds of 5,000 m min⁻¹. It was found that the SDAS is the parameter with the main influence on tool wear rate; higher SDAS values require polycrystalline diamond (PCD) tooling due to the lower wear rates when compared with carbide tools. Finite Element Analysis (FEA) was employed to study the influence of tool wear on temperature and shear stress distribution in the workpiece material.