3PE防腐层缺陷成因分析与防范

3PE防腐层被称为“完美”涂层。但是，由于其涂装技术相对比较复杂，如果生产工艺控制不严，将会产生多种防腐层缺陷；另一方面，剥离的聚乙烯层对阴极保护电流具有很强的屏蔽作用，3PE的某些缺陷有可能是致命的。本文对3PE防腐层缺陷产生原因进行了较为全面的介绍和分析，同时提出控制措施，与业内同行交流。     

Feasibility study of the minimum quantity lubrication in high-speed end milling of NAK80 hardened steel by coated carbide tool

High-speed milling of hardened steels generates high cutting temperature and leads to detrimental effects on tool life and workpiece surface finish. In this paper, feasibility study of the minimum quantity lubrication (MQL) in high-speed end milling of NAK80 hardened steel by coated carbide tool was undertaken. Flood cooling and dry cutting experiments were conducted also for comparison. It is found that cutting under flood cooling condition results in the shortest tool life due to severe thermal cracks while the use of MQL leads to the best performance. MQL is beneficial to tool life both in the lower speed cutting and the higher speed cutting conditions. A less viscous oil of MQL is essential in high cutting speed so that cooling effect can be effective. SEM micrograph of the insert shows that the use of MQL in high-speed cutting can delay welding of chips on the tool and hence prolongs tool life as compared with dry cutting condition. The application of MQL also improves machined surface finish in high-speed milling of die steels.     

15MnVN钢的氢致硬化和氢致软化

研究了不同氢含量、应变速率条件下１５ＭｎＶＮ钢氢致硬化和氢致软化现象。试验证实，氢的存在首先造成氢致硬化，而当塑性变形开始后又导致氢致软化。这一作用受钢中氢偏聚控制，并受应变速率的诱导作用。氢的存在对钢的抗拉强度无明显影响。     

Effects of laser beam energy and incident angle on the pulse laser welding of stainless steel thin sheet

This paper reports an experimental study of laser spot welding on stainless steel sheets. A pulsed Nd:YAG laser was used to weld the stainless steel specimen in the range of laser energy 0.6–1.2 J and incident angle 30–75° (the angle of the laser beam incident direction to the sheet surface). Metallography was applied to measure the cross-sectional size and shape of the welded spot. From the experimental results, it is found that as the laser energy increases, the penetration depth, bead length, and bead width of the welded spot increase. As the laser incident angle increases, the penetration depth and the bead width increase while the bead length decreases. The results illustrate that the shape and size of the welded spot depend not only on the laser energy, but also on the incident angle of laser beam.     

数控加工模具型腔中的数据处理

模具型腔在数控加工中需要一套控制刀具运动轨迹的算法，本文给出了从模具型面的几何描述，加工数据的生成到形成Ｇ格式指令进行数控加工这一生产过程的数据处理，实验和现场加工的结果表明：该数据处理算法成功地解决了模具型面的加工制造问题。     

脉冲电流对Al-4.5Cu合金定向凝固组织的影响

研究了脉冲电流对Al-4．5Cu合金定向凝固过程及组织的影响。结果表明，随着脉冲电流峰值和频率的增大，Al—4．5Cu合金柱状晶被熔断，形态由细条状变为不连续，失去其定向凝固的取向性；且柱状晶间距随电流峰值和频率的增大而减小。由脉冲电流的引入而产生的脉冲磁压力及焦耳热效应在固液界面处造成的强烈扰动是定向凝固组织失去取向性的主要原因。     

方坯连铸二冷热应力模拟

建立了方坯的应力计算模型，并通过采用有限元法求解，获得了铸坯在二冷段的应力和应变分布规律，为研究二冷对铸坯质量的影响提供了理论基础。     

A new on-line spindle speed regulation strategy for chatter control

A new on-line control method to suppress regenerative chatter vibration during the machining process by regulating spindle speed is proposed. The dynamic cutting force signal collected from a dynamometer is passed through a low pass filter, and then digitized. The fast Fourier transform is carried out to obtain the corresponding power spectrum. The chatter frequency is identified when the intensity at a certain frequency other than the spindle speed and tooth passing frequency exceeds a critical value. Based on the identified chatter frequency, a new spindle speed is computed by applying the principle of keeping the phase between the present and previous undulations to 90°. The new speed command is executed while the cutting proceeds. It is found from simulation that the chatter vibration can be suppressed by this approach in the shortest time. This method is also verified by experiments through actual cutting of various materials by a computer numerically controlled milling machine. The main feature of this approach is that the feed of the machine tool does not need to be halted during the change of spindle speed. Hence, tool wear can be reduced. Furthermore, no system identification of the machine tool structure is needed, and therefore it has great potential in actual applications.     

覆砂金属型工艺设计及其数值模拟

论述了覆砂金属型铸造工艺及其传热机理,对其数值模拟技术进行了分析,并利用ANSYS软件模拟了球铁曲轴的覆砂金属型铸造温度场,确定了其工艺参数.     

B对Al-13Si-0.3Mg合金流动性的影响

采用浇注螺旋型试样的方法测量了B对Al-13Si-0．3Mg合金流动性的作用；并通过温度校正的方法校正了浇注温度的误差对测量结果的影响。研究发现随B含量的增加，合金的流动性明显提高。采用对凝固中期的合金进行液淬的方法研究了该合金的凝固方式。根据合金凝固后的组织及合金凝固的方式分析了B影响Al-13Si-0．3Mg合金流动性的原因。