电火花和线切割在航空产品加工零件表面质量的控制

电火花和线切割在航空产品机械加工中有广泛的应用,本文主要分析了电火花和线切割对零件表面质量的影响,阐述了航空产品对电火花、线切割加工零件的质量标准,并提出了质量控制要求和方法,以确保零件加工表面的组织稳定,保证航空发动机的产品质量可控状态。     

电火花线切割拐角加工控制方法研究

在电火花线切割拐角加工中,拐角加工精度一直是电火花线切割加工领域所追求的重要性能之一。在分析电火花线切割拐角误差的原因的基础上,重点对于电火花线切割拐角加工控制方法进行研究,有利于提高电火花加工水平。     

浅析电火花线切割一般工艺

电火花线切割加工(Wire Cut EDM,简称WEDM)也叫数控线切割加工,它是在电火花成型加工基础上发展起来的一种新的工艺形式,电火花线切割加工自诞生以来,获得了极其快速的发展,已逐步成为一种高精度高自动化的加工方法。它在模具制造、成型刀具加工、难加工材料及精密复杂零件的加工等方面获得了广泛的应用。通过对电火花线切割加工的工艺浅析,提出一般工艺处理与编排,从而指导初学者实际加工过程,可使学者提高生产效率和零件表面加工质量。质量得到较大幅度的提高。     

电火花线切割机床组成及加工

本文通过对电火花线切割机床的组成及应用的介绍,让大家了解电火花线切割的加工原理,特点,分类机应用范围,并且对电火花线切割机床的组成部分有概括的认识,从而更好进行加工。     

不锈钢拉延件在电火花线切割加工中产生变形原因的分析及对策

本文通过分析不锈钢拉延件在数控电火花线切割产生变形的原因,探讨解决去除材料后工件变形而致的夹断丝、尺寸超差、短路等问题,进而提出一种有效减少加工变形的线切割工艺方法。     

模具零件线切割加工变形与控制

电火花线切割技术在加工具精密、微细模具零件方面具有不可替代的作用,在模具制造中应用越来越广泛。零件的变形与开裂是线切割加工容易出现的缺陷,影响零件零件的精度甚至导致零件报废。本文分析了模具零件线切割加工中零件变形的原因,从热处理、机械加工和线切割三个方面总结出了减小线切割变形的方法和措施。     

浅谈线切割工件质量的改善与提高

本文探讨了电火花线切割加工中电参数对工件表面粗糙度的影响。通过电参数的不同匹配,分析研究了影响表面加工质量的因素及规律。     

圆柱面电火花线切割加工技术

依据零件结构、尺寸要求等特点,选择合理的加工工艺方案,设计加工专用夹具,利用电火花线切割完成六圆柱面零件的加工。     

数控电火花线切割在板线内导体加工中的应用

分析了板线内导体在利用数控电火花线切割加工中所遇到的工艺技术难题．针对这些问题,作者根据数控快走丝线切割机床的特点,提出了有针对性的解决方案,包括加工参数的选择、加工路径的优化、起割点的合理选择、控制自重变形等方面,最终解决了板线内导体的加工难题．     

计算机模拟显示数控线切割加工轨迹

介绍用Basic语言编制国内常见的数控电火花线切割3B格式程序的计算机仿真程序。可实现在计算机上模拟显示线切割加工轨迹,从而可验证所编3B程序的正确性等。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.