A model relating tool torque and its associated power and specific energy to rotation and forward speeds during friction stir welding/processing

Torque (M) is a very important quantity in the friction stir welding (FSW) process but a satisfactory model relating M to the two major FSW parameters, rotation speed (ω) and forward speed (v), has not been well developed. In this work, a better model of the form, M=f(ω, v), was sought. Experimentally, FSW of an aluminium alloy was conducted over a wide range of ω and v values and M was measured. An exponential decay function has been found to fit all the M versus ω data well and is meaningful for any ω value. The effect of v on M can approximately be accounted for through linearly relating the model parameters to v. The model allows for a detailed evaluation of the sensitivity of M to changes in ω and v. The model decay and the pre-exponential parameters need to be adjusted to make predictions for different aluminium alloys in the low ω range. Both the model and experimental data demonstrate a diminishing alloy effect on material flow resistance as ω increases. Furthermore, models of tool power (P_Tool) and specific energy (E_s) can be derived from the model for M and give predictions that are also meaningful over the entire range of ω values. Finally, the dependences of P_Tool and E_s on ω and v and the relationship between E_s and the processing zone temperature will be discussed.     

Mechanically strong conducting hydrogels with special double-network structure

Mechanically strong conducting hydrogels composed of poly(acrylamide) (PAAm) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been synthesized through the construction of a special double-network (sDN) structure. The novelty of the sDN hydrogels lies in the introduction of PEDOT-PSS semi-interpenetrating polymer network (semi-IPN) hydrogel as the second network. Based on the experimental results and the double-network theory, an additional strengthening effect resulting from the formation of the PEDOT clusters in a three-step fracture process is proposed. The applicability of as-prepared PAAm/PEDOT-PSS sDN hydrogels in electromechanical actuators is also briefly discussed.     

四氟化碳生产技术与市场

介绍了四氟化碳的性能、用途和生产技术路线。评述了其国内外的市场变化、主要生产厂家规模及分布,从四氟化碳发展历程到今后趋势,说明四氟化碳在氟化工中的地位、我国发展四氟化碳的优势与不足。对打算进入此产品项目的企业,从技术开发、项目投资、产品生产销售等方面提出了建议。     

泥浆泵输污管路系统的合理化改造

安阳钢厂高炉煤气洗涤循环水处理站的泥浆泵输污管路系统在运行过程中,泵体及污泥输送管路系统经常发生吸气、振荡和堵塞的不良现象,经现场调查和理论分析,认为吸水、压水管路不合理的布置及相关设施的不完善是造成泵体不能正常运行的主要原因,同时给操作管理带来一些不便。通过进行一系列改造,如对吸水、压水管路增设有益、取消多余管件;把吸水管路分设,改普通弯头为三通弯头;减少压水管路的转向次数,选择大转弯半径的弯头,降低管线总长和增置高架流槽,不仅使系统运行更安全可靠、稳定高效,并且让操作管理和维修养护更方便,还节省了不必要的开支。     

用于精确焊接的智能视觉系统

通过与其它传感技术的对比,简要分析了激光视觉在焊接生产中得到成功应用的原因。分析了早期激光视觉系统的特征和当时面临的挑战。介绍了Servo-Robot激光视觉的关键技术和已取得的显著进步,阐述了集成激光视觉的移动式便携焊接机器人和激光视觉在焊缝质量检测中的应用。展望了激光视觉系统的未来和智能视觉在提高机器人性能方面发展的显著进步,包括改进机器人人工示教、离线编程及视觉辅助机器人示教。     

倒置式车削中心交流伺服电机的选型

文章以倒置式车削中心主传动系统和伺服进给系统电机选择为例,重点介绍伺服主轴电机和伺服进给电机的选择方法和选择原则。通过计算负载切削功率、转矩和惯量的方法找到负载特性和驱动电机参数的合理匹配,为机床数控化改造和新设计机床电机选型提供合理的依据。     

Weld line transverse energy density distribution measurement in laser transmission welding of thermoplastics

While laser beam profiling techniques are available for the measurement of a laser beam power profile, such techniques are difficult or impossible to use in order to characterize the power profile of the beam which has passed through the light-scattering semi-crystalline polymer (such as nylon). This paper presents a technique for measuring the scattering of the laser beam caused by the laser-transparent part in laser transmission welding. The technique is easy to implement and does not require specialized or expensive equipment. It relies on measurements of line widths for a sequence of lines left on the polymer surface by a rapidly moving laser beam at progressively increasing powers. The line width and power information is then used to obtain the distribution of the laser energy across the weld line. An application for a case of a high-power diode laser and (glass-reinforced and natural) polyamide 6 is presented.     

钢铁企业净循环冷却水系统设计

详细介绍了为某钢铁企业服务的敞开式净循环水系统的设计过程。包括工艺流程的选择、工艺参数的计算、主要设备的选型等。设计采用事故水塔和柴油机泵联合供水方式确保系统安全,并将仪表检测的参数进行集中显示和控制。系统自动化水平高,运行维护方便。     

《工业水处理》质量与学术影响力分析

依据中国知网开发的中国期刊全文数据库、中国引文数据库及中国科学院开发的中国科技期刊引证指标数据库,采用文献计量学方法对《工业水处理》杂志2004—2008年的载文、引文,2004—2007年的被引、学科影响力等进行调查研究及定量分析,客观揭示该刊在我国学术界的整体水平及主要影响。以期对期刊的发展提供客观依据。     

PP/PA6/APP/OMMT复合材料的湿热老化性能研究

采用熔融挤出插层制备聚丙烯(PP)/尼龙6(PA6)/聚磷酸铵(APP)/有机蒙脱土(OMMT)阻燃复合材料,研究温度80℃、湿度93.1%的湿热老化条件对复合材料性能的影响.结果表明,随着湿热老化时间的延长,复合材料的表面形貌变得很差,产生大量的粗糙白斑.当OMMT含量较低时,复合材料的拉伸强度随湿热老化时间的延长先上升后下降.而当OMMT含量较高时,复合材料的拉伸强度随着湿热老化时间的延长而下降.弯曲强度的变化规律与拉伸强度相似.缺口冲击强度则随着老化时间的延长而提高.引起复合材料破坏的主要原因并非是湿热老化反应导致的分子链断裂,而是复合材料内积聚的水泡和水分子渗入到各相界面引起界面粘结强度下降导致的结果.