纳米TiN改性金属陶瓷刀片的铣削性能

制备了两种纳米TiN改性金属陶瓷可转位铣刀片ToolA和ToolB。研究了这两种新型面铣刀在切削正火态45#钢时的铣削性能及其失效机理。试验结果表明,两种试验铣刀片在Vc=294m/min,fz=0.16mm/z,ap=0.5mm条件下铣削45#钢时,均未发现“崩刃”现象,并全都以“磨损”的形式失效,刀具寿命较长。此外,在同样切削条件下,ToolA具有良好的抗氧化磨损性能,而ToolB有更高的耐机械冲击能力;高温扩散和氧化磨损成为导致纳米TiN改性铣刀片磨损失效的主要原因。     

两坐标数控立式铣削欠切现象及其防止

在两坐标数控立铣削加工中,欠切是常见的异常加工现象,严重的影响了加工质量及加工效率。文中将欠切现象归纳为工艺系统引起的欠切、数控系统功能引起的欠切、工艺安排及编程引起的欠切三个大类,分析了十五种主要欠切形成的原因,并提出了控制欠切的措施。     

45SiMnCrMo铸钢磨球强韧化的研究

利用Formastor-Digital全自动相变测量仪测定了ZG45SiMnCrMo钢的临界点,研究了该钢的余热淬火温度、回火温度对强韧性的影响和淬硬层分布.结果表明,45SiMnCrMo铸钢采用900℃淬火,300℃回火,强韧性最佳.     

High-speed milling of titanium alloys using binderless CBN tools

The performance of conventional tools is poor when used to machine titanium alloys. In this paper, a new tool material, which is binderless cubic boron nitride (BCBN), is used for high-speed milling of a widely used titanium alloy Ti–6Al–4V. The performance and the wear mechanism of the BCBN tool have been investigated when slot milling the titanium alloy in terms of cutting forces, tool life and wear mechanism. This type of tool manifests longer tool life at high cutting speeds. Observations based on the SEM and EDX suggest that adhesion of workpiece and attrition are the main wear mechanisms of the BCBN tool when used in high-speed milling of Ti–6Al–4V.     

金属型铸造高铬白口铸铁磨球的复合变质处理研究

研究了复合变质处理对金属型铸造的高铬格白口铸铁磨球组织及性能的影响。结果表明，采用ＲＥ、Ｂ、Ｖ、Ｔｉ元素复合变质处理，可有效细化磨球结晶组织，改善碳化物的形态与分布，并显著提高冲击韧性和耐磨性能。     

矿山磨光球用钢XK5159H的生产试制

XK5159H钢连铸连轧棒材用于制造矿山磨光球，对于钢的纯净度、低倍组织、探伤结果及DI值等均有严格的要求，很难控制。我们通过制定内控化学成分及合理的工艺路线，使生产试制一次成功。     

3300mm轧机辊缝位置控制系统的研制

介绍3300mm中厚板可逆热轧机辊缝调整机构的组成,设计了3300mm轧机辊缝位置控制系统控制方案,给出了该方案中压下电机调速系统的设计过程,最终依据设计方案研制了辊缝控制系统,并在实际生产中运行使用。现场运行结果表明,用有准备切换逻辑无环流控制系统控制压下电机的辊缝位置,性能稳定,定位迅速,控制精度达到±0.3mm。宝钛集团使用该设备生产的钛及钛合金中厚板、镍板、锆及锆合金板等质量达到国际同类产品的先进水平。     

提高高铬白口铸铁磨球冲击抗力的技术关键

当高铬白口铸铁含铬量为18%～28%,Cr/C值是8￣9,铸铁的显微组织是回火马氏体 少量残余奥氏体(<5%) M7C3碳化物,则磨球具有高的冲击韧性和断裂韧性K1C,具有高的冲击抗力,表现出低的冲击剥落量。     

Tool deflection compensation in peripheral milling of curved geometries

This paper presents compensation of surface error due to cutting force-induced tool deflections in a peripheral milling process. Previous research attempts on this topic deal with error compensation in machining of straight geometries only. This paper is concerned with peripheral milling of variable curvature geometries where the workpiece curvature changes continuously along the path of cut. In the case of curved geometries, both process geometry and the cutting forces have shown to have strong dependence on workpiece curvature and hence variation of surface error along the path of cut. This calls for a different error compensation strategy than the one which is normally used for machining straight geometries. The present work is an attempt to improve accuracy in machining of curved geometries by use of CNC tool path compensation. Mechanistic model for cutting force estimation and cantilever beam model for cutter deflection estimation are used. The results based on machining experiments performed on a variety of geometries show that the dimensional accuracy can be improved significantly in peripheral milling of curved geometries.     

Feedrate optimization and tool profile modification for the high-efficiency ball-end milling process

Trend in die/mold machining is to produce highly quailed surface using the high-speed hard machining with the ball-end cutter. The ball-end milling is, however, less efficiency than the flat end milling. It is important to optimize the feedrate that gives the maximum material removal rate constrained by an allowable surface roughness. The state-of-art of the CBN ball-end cutter technology allows increasing the tooth feed for high-speed and high-efficiency machining. However, because the spherical shape of the cutter can result in the scallop-liked cusps on the machined surface, the surface roughness consideration makes a feedrate limitation to the CBN cutter. In this paper, the optimization of the feedrate by considering the generated-scallop effect of the ball-end cutter has been studied. It was found that the tooth feed must be kept within one third of the path pick in order to keep the feed-interval scallop height not over the path-interval scallop height. Therefore, the potential capability of the CBN cutter for the larger tooth feed (i.e. high efficient) machining can not be fully exploited. It was found a notch-cut on the center of the ball-end cutter reduced the feed-interval cusp height, thus allowing an increased feedrate of more than 50% compared with the standard ball-end cutter. If the parameters of the notch-cut profile can be optimized, it is believed that the feedrate can be further increased.