参数曲线应用数控加工的最大进给速度探讨

在数控加工过程中，选择最大进给速度能充分利用机床伺服系统潜能，实现安全高效加工。全面分析了影响数控轮廓加工进给速度选择的约束条件：伺服系统性能、待加工轮廓几何特性及加工精度要求等。给出了一个轮廓曲线加工算例，求取满足上述约束条件的最大进给速度。利用此速度进给加工时，可在满足伺服系统性能的前提下，充分利用其潜能。     

利用曲面曲率划分的高速数控加工进给速度修正

为保证数控加工中的切削效率和机床运动的平稳性,提出了基于曲面曲率划分的进给速度修正方法。以最大工作进给速度的变化比率为阈值,把零件表面的法曲率半径划分为不同的区域;在不同的曲率区域内,分别以恒定的刀触点速度对进给速度进行修正,修正后的进给速度随着零件表面曲率的变化而自适应变化;实例表明该方法具有合理性和有效性。     

盘形凸轮轮廓误差及其插补点的确定

论述了盘形凸轮在数控加工中直线插补拟合误差的分析表达式,推导了各种盘形凸轮机构的误差公式,据此建立了误差与凸轮转角之间的关系,既可实现等角度分割,又可实现变步长分割,为插补点的分割提供了科学依据.通过实例,在给定轮廓度公差±0.000 5 mm,等角度分割法角度间距为0.5°时,提出的误差一定法在推程及回程的插补次数分别为403次和307次,最大转角步长依次为0.615°和0.93°,最小转角步长依次为0.324°和0.3°,保证每次插补误差都为给定公差,且在满足精度的条件下插补次数最少,生产效率最高.为优质高效地设计及制造凸轮提供了科学依据.     

数控机床的结构特征及提高性能的措施

随着现代机械制造技术的飞速发展,精密和超精密加工技术已经成为现代机械制造的重要组成部分。数控机床作为机械制造中的重要工具,它的精度指标是影响工件加工精度的重要因素。本文阐述了数控机床机械结构的技术特征、对机械结构的技术要求等问题。本文提出了数控机床总体布局的合理选择、提高结构件的刚度机床抗振性、改善机床的热变形、保证运动的精度和稳定性等提高数控机床性能的措施。     

数控机床的结构特征及提高性能的措施

随着现代机械制造技术的飞速发展,精密和超精密加工技术已经成为现代机械制造的重要组成部分。数控机床作为机械制造中的重要工具,它的精度指标是影响工件加工精度的重要因素。本文阐述了数控机床机械结构的技术特征、对机械结构的技术要求等问题。本文提出了数控机床总体布局的合理选择、提高结构件的刚度机床抗振性、改善机床的热变形、保证运动的精度和稳定性等提高数控机床性能的措施。     

五轴联动机床动态误差与RTCP分析

在对零件加工进行研究的过程中,机床的动静态分析是主要的分析对象,机床的切削能力反应了机床的加工能力,不同的误差对机床的影响也不同,产生的精度影响也不同,误差仿真技术可以有效发现机床的误差源。动态性能会影响高精密机床的制造加工精度。该文分析了五轴精密加工机床的动态性能、机床的RTCP功能、影响机床加工精度的因素和机床误差的产生,同时对误差的影响因素进行了分析,通过减小机床的误差,保证机床的动态性能能够满足加工需求。     

机床主轴回转误差对加工精度影响分析

机床的质量取决于机床关键部件的质量,而机床主轴部件是保证机床加工精度的核心,主轴回转误差是影响机床加工精度的重要因素之一,直接影响到加工零件的形状精度、表面的粗糙程度和质量,实验结果表明:由主轴回转误差引起的精密     

对CA6150车床控制系统的数控化改造设计

为实现CA6150普通车床数控化,对机床的控制系统进行了设计、改造,改造后的普通车床能够满足具有准确定位、直线插补、圆弧插补、暂停等数控功能的要求。     

浅论机床夹具的类型和加工特点

应用机床夹具,可以保证工件的加工精度、稳定产品质量。本文主要阐述机床夹具的类型,以及数控加工夹具的特点。     

非圆回转曲面CNC 磨削加工轨迹直接插补技术研究

针对非圆回转曲面数控磨削加工轨迹插补特点,动用曲面直接插补（ＳＤＩ）思想,提出一种适合于非圆回转曲面类零件轨迹处理的集成式ＣＮＣ轨迹插补模式,并系统研究了实时插补中加工工艺余量智能决策方法和轨迹自生成原理等,成功地解决了非圆回转曲面磨削加工的轨迹实时插补控制问题。     

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.     

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.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.