数控立式加工中心在叶片制造中的应用实践

介绍数控立式加工中心在满足叶片加工功能的前提下其性能价格比的量化分析，并重点围绕设备具有的四联动功能，开发了叶片中间体、型面加工的新工艺。     

棕树型叶片汽道型线的数控加工

叶片是汽轮机的主要部件之一,尤其它的汽道部分决定了汽轮机的发电功率,直接影响到汽轮机产品的质量,也直接影响叶片的工作效果,进而直接影响整机的工作性能,叶片汽道型线部分是复杂空间三坐标数据点,加工精度要求很高,加工难度很大.本文通过对叶片的造型及数控编程,使大家对叶片类零件的数控加工过程有一个整体的了解.     

汽轮机叶片虚拟制造仿真研究

文章通过VERICUT平台,定制开发汽轮机叶片虚拟仿真控制系统,实现汽轮机叶片虚拟制造仿真.该仿真控制系统可提高汽轮机叶片数控加工程序的安全性、产品质量、制造系统的工作效率和数字化车间基础数据的准确性.     

汽轮机叶片的数学建模

应用B样条反求算法,对由离散型值点给出的汽轮机叶片,建立了型面造型、拟合计算和数控加工的数学模型。     

一种专用叶片型面的加工方法

从经济实用的角度,提出了一种专用的叶片型面加工方法,简单介绍了此种方法的数控加工工艺方案、加工机床结构、工件装夹及夹具、加工过程、叶片型面数学模型的建立及处理等,并提出了进一步改进的方法。     

数控加工在叶片叶身型面加工中的应用

叶片叶身型面是叶片零件的主要特征表面。叶身型面加工，难度大、工作量大、在整个叶片生产过程中，占有重要的地位。本文通过叙述数控加工在叶片叶身型面加工中的应用，探讨如何充分发挥数控机床的作用，以及分析叶片数控加工机床选用应考虑的原则。     

叶片型面误差分析改进

首先介绍了叶片型面误差的检测的现状，接下来介绍了改进的检测方案，通过扫描仪得到点云，把得到的点云与CAD模型对齐，计算叶片型面误差，然后送给机床，按照误差的大小来选择加工参数。因此，对提高叶片型面检测效率和叶片型面加工精度都有较强的指导意义。     

圆率法在汽轮机叶片型线光顺中的应用

本文从提高汽轮机叶片的光顺质量出发,就如何在汽轮机叶片的CAGD(计算机辅助几何设计)过程中将圆率法应用于叶片型线的光顺处理进行了探讨。本文的结果虽然是从现有汽轮机叶片复制过程中得出的,但对于汽轮机的设计和制造,同样有一定的参考价值。     

汽轮机叶片的三维几何造型方法综述

通过对汽轮机叶片汽道型面及叶根、叶冠部分几何造型特点的分析,介绍了应用CAD/CAM软件对汽轮机叶片进行三维几何造型的一般方法并指出了在叶片设计及制造过程中的应用。     

提高效率的先进汽轮机技术

本文介绍了ＡＢＢ公司近年来为提高汽轮机热效率而采用的先进技术，重点讨论了高温材料的开发，叶片型线的改型和制造工艺的现代化。     

活塞环内外仿凸轮分析设计软件的开发

本文通过对活塞环内外仿机床的仿形结构以及杠杆调节原理的介绍,指出了内外仿机床杠杆机构中凸轮型线与活塞环型线的关系,针对内外仿机床加工调节困难的问题,开发了一套活塞环内外仿凸轮分析设计软件,并在笔者研制成功的活塞环外圆数控仿形车床上成功地实现了内外仿的加工技术.     

非圆曲线型线数控加工自动编程的应用研究

随着科技的进步和发展,零件的复杂程度越来越高,数控加工的自动编程得到推进.本文针对活塞异形销孔非圆曲线型线数控加工问题,利用UG软件作为辅助开发的工具,自动生成加工程序源文件,通过后置处理,生成机床数控系统可识别的GM代码程序.该自动编程方法为活塞异形销孔非圆曲线型线的加工提供了一种新的思路.     

Transition metal carbides coupled with nitrogen-doped carbon as efficient and stable Bi-functional catalysts for oxygen reduction reaction and hydrogen evolution reaction

Developing non-precious metal catalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is crucial for proton exchange membrane fuel cell (PEMFC), metal-air batteries and water splitting. Here, we report a in-situ simple approach to synthesize ultra-small sized transition metal carbides (TMCs) nanoparticles coupled with nitrogen-doped carbon hybrids (TMCs/NC, including WC/NC, V₈C₇/NC and Mo₂C/NC). The TMCs/NC exhibit excellent ORR and HER performances in acidic electrolyte as bi-functional catalysts. The potential of WC/NC at the current density of 3.0 mA cm^?2 for ORR is 0.814 V (vs. reversible hydrogen electrode (RHE)), which is very close to Pt/C (0.827 V), making it one of the best TMCs based ORR catalysts in acidic electrolyte. Besides, the TMCs/NC exhibit excellent performances toward HER, the Mo₂C/NC only need an overpotential of 80 mV to drive the current density of 10 mA cm^?2, which is very close to Pt/C (37 mV), making it the competitive alternative candidate among the reported non-precious metal HER catalysts.     

SINUMERIK840D数控机床附件补偿程序的开发

大型数控设备为扩大其加工功能均配置了多个机床附件,且结构复杂,要充分发挥机床附件的作用,数控机床必须具备机床附件自动补偿计算功能,而国内数控机床厂家生产的这类带多个机床附件的设备又不具备附件自动补偿计算功能。该文以北京第一机床厂龙门移动式数控镗铣床附件补偿计算功能开发为例,详细介绍了SINUMERIK840D数控系统附件补偿计算程序设计方法及实例。     

SPG高压内缸的数控加工

简述了谏壁电厂7号、8号机组(国产300MW汽轮机)在改造过程中，高压内缸在数控立车上的加工工艺过程，开发了参数化数控加工程序，解决了齿形叶根槽、内部复杂型腔等的加工技术，扩大了数控加工程序的应用范围，为参数化编程提供了宝贵经验。     

N-doped carbon coated FeNiP nanoparticles based hollow microboxes for overall water splitting in alkaline medium

Stable, earth-abundant and efficient electrocatalysts for overall water splitting are urgently needed. In this work, we have reported the synthesis of FeNiP/NC hollow microboxes (FeNiP/NC) based bifunctional electrocatalyst via the phosphorization process using rationally designed cube-type metal-organic framework (FeNi-MOF) as both the template and carbon source. The FeNiP/NC, which were obtained by assembling the uniform FeNiP nanoparticals together through N-doped carbon, manifests outstanding catalytic performances for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in KOH solution. Notably, FeNiP/NC displays exceptional activity when it was utilized as both anode and cathode toward overall water splitting with potential of 1.54 V at a current density of 10 mA cm^?2 in alkaline electrolyte, which is much better than FeP/NC and Ni₂P/NC electrocatalyst. More importantly, the improvement of the catalytic activities of FeNiP/NC mainly benefits from the well dispersion of FeNiP nanoparticles on the surface of carbon support, the large active surface area and the doping of N and C derived from organic ligands. In addition, the enhanced electrocatalytic performance of FeNiP/NC for OER is closely related with the in-situ formed surficial MOOH (M = Fe, Ni) active sites, which has been confirmed by X-ray photoelectron spectroscopy (XPS) analysis.     

MnO nanoparticles loaded on three-dimensional N-doped carbon as highly efficient electrocatalysts for the oxygen reduction reaction in alkaline media

It is very important to develop non-noble metal electrocatalysts for oxygen reduction reaction (ORR) to replace noble metal electrocatalysts to promote the large-scale application of fuel cells. Here, three-dimensional (3D) N-doped carbon supported MnO nanoparticles (MnO/NC) are prepared by two-step pyrolysis method. The MnO/NC performs excellent catalytic activity comparable to 20% Pt/C for ORR, for instance, a positive onset potential (0.92 V), half-wave potential (0.82 V) and peak potential (0.76 V). The MnO/NC shows a strong tolerance to methanol and long-term stability in an alkaline media. The high ORR activity of MnO/NC owes to its unique property of fast electron transport, high specific surface areas and the synergistic effect between MnO and 3D NC support. This study projects an innovative strategy to construct electrocatalysts of 3D structure composites, which is expected to offer efficient non-noble metal electrocatalysts for ORR.     

Nitrogen doped carbon layer coated platinum electrocatalyst supported on carbon nanotubes with enhanced stability

Enhancement in durability of electrocatalyst is still one of the most important issues in polymer electrolyte fuel cells (PEFCs). Here, we report a structurally coated electrocatalyst supported on carbon nanotubes (CNT), in which platinum (Pt) nanoparticles are coated by nitrogen doped carbon (NC) layers. CNT/NC/Pt/NC shows comparable electrochemical surface area (ECSA) and oxygen reduction reaction (ORR) activity to the non-coated electrocatalyst (CNT/NC/Pt), indicating that NC layer on Pt nanoparticles almost negligibly affects the activities of electrocatalyst; while, CNT/NC/Pt/NC exhibits a higher Pt stability due to the unique structure, in which the Pt nanoparticles are stabilized by the NC layers and Pt aggregation is decelerated proved by TEM measurement. Maximum power density of CNT/NC/Pt/NC reached 604 mW cm^?2 with Pt loading of 0.1 mg_Pt cm^?2, which only decreases by 7% compared to CNT/NC/Pt (650 mW cm^?2). The electrochemical analysis and fuel cell test illustrate that NC layer on Pt nanoparticles enhances the durability without serious deterioration of fuel cell performance.     

ZnS,Fe, and P co-doped N enriched carbon derived from MOFs as efficient electrocatalyst for oxygen reduction reaction

Exploring electrocatalysts with low cost and excellent performance for oxygen reduction reaction is still a significant challenge. In this paper, we introduce a novel strategy to fabricate ZnS, Fe, and P co-doped N enriched carbon (ZnFeSP/NC) via the direct carbonization of PVP/ZIF-8 combined with absorption, sulphurization, and phosphorization processes. The as-synthesized ZnFeSP/NC was used as electrocatalyst for oxygen reduction reaction (ORR). We explored the influence of Fe, S, and P elements on the ORR activity of the catalysts. It can be found that ZnS nanoparticles were formed and attached on the surface of the ZnFeSP/NC nanoparticles. α-Fe and P element were well dispersed on ZnFeSP/NC nanoparticles. Fe, S, and P element can highly enhance the ORR activity of the catalysts. Compared to Zn/NC, ZnFe/NC, and ZnFeS/CN, ZnFeSP/NC shows the optimal ORR performance with the half-wave potential of 0.859 V and a current density of 3.33 mA cm⁻² at −0.85 V. Furthermore, ZnFeSP/NC also exhibits excellent long-term operation stability, effectively avoiding any ORR performance decay.     

One step pyrolysis synthesis of silver/nitrogen-doped carbon sheet for oxygen reduction in alkaline media

We developed the silver supported on nitrogen-doped carbon sheets (Ag/NC) synthesized by simple one-pot and in-situ thermal treatment as an efficient ORR catalyst. The Ag/NC exhibits higher activity than NC in terms of onset potential and half-wave potential. The kinetic parameters confirm 4e^? reaction pathway for ORR on Ag/NC. In addition, the Ag/NC also shows better methanol tolerance and superior durability than Pt/C in alkaline solution.