面向智能制造的数控机床多目标优选法研究

考虑当前制造业智能化发展趋势以及数控机床在现代制造工程领域所发挥的关键作用,提出了一种集质量功能展开(QFD)、模糊线性回归和0-1目标规划优点于一体的数控机床多目标优选法。在研究智能制造对数控机床特定要求的基础上,运用QFD考察智能制造需求与数控机床性能之间的因果关系,采用质量屋将智能制造的需求有机地融入数控机床选型中。基于模糊线性回归法确定智能制造需求与数控机床性能在质量屋中的相互关联程度,运用层次分析法计算智能制造需求指标的权重系数,并采用0-1目标规划法在众多候选数控机床中做出最佳选择。以某智能制造平台搭建过程中的数控机床多目标决策问题作为应用案例,从5台候选数控机床中挑选出综合性能最好的1台。研究表明,所提出的面向智能制造的数控机床多目标优选法具有较高的工程实用性。     

家禽弃尸重制骨骼囊腔铸塑干教具的实验探索

本文笔者将解剖实验用后的家禽弃尸重新研制成实用的家禽骨骼囊腔铸塑干教具,不仅解决了实验动物尸体二次污染环境的问题,而且因为教具形态逼真、精细牢固而使解剖教学更形象生动,教学成果显著,同时还节省了很大一笔解剖教学实验经费。     

Development and application of a PCR-based 'molecular tool box' for the identification of Phytophthora species damaging forests and natural ecosystems

A PCR-based 'molecular tool box', based on a region of the ras-related protein gene Ypt 1, was developed for the identification of 15 Phytophthora species that damage forests and trees: P. cactorum , P. cambivora , P. cinnamomi , P. citricola , P. europaea , P. inundata , P. lateralis , P. megasperma , P. nemorosa , P. kernoviae , P. pseudosyringae , P. psychrophila , P. quercina , P. ramorum and P. ilicis . Most primers proved highly specific in blast analyses and in tests with DNA from 72 isolates of 35 species of Phytophthora and nine species representative of Pythium . Exceptions were primers designed for P. cactorum and P. ilicis , which cross-reacted with P. idaei and P. nemorosa , respectively. Amplification with Phytophthora -genus-specific primers before amplification with the various species-specific primers (nested PCR) increased the sensitivity of detection over amplification with species-specific primers only: detection limits ranged between 100 and 10 pg target DNA µ L⁻¹ in the latter, compared with 100 fg µ L⁻¹ in nested PCR. Using existing methods for rapid extraction and purification of DNA, single-round amplification was appropriate for detection of target Phytophthora species in leaves, but nested PCR was required for soil and water samples. The quarantine pathogens P. ramorum and P. kernoviae were detected in a number of naturally infected leaves collected in England and Wales, whereas P. citricola was commonest in water and soil samples from natural Scottish ecosystems.     

数控车削加工高精度圆弧

分析了在无半径补偿功能的数控车床上精加工圆弧或锥度时易产生误差的原因,指出为解决这一问题应在编写数控加工程序时对圆弧刀尖进行补偿计算,求得刀位点（假想刀尖点）在加工过程中的坐标值,从而有效地解决过切或欠切等问题。     

Assessment of wood particleboards milling by means of energy consumption tests

In this paper, an experimental procedure is proposed, in order to evaluate the machinability of different particleboards. A dedicated test stand has been built to measure the power consumption during the process for different typologies of particleboards. This methodology could constitute a quick particleboard grading system, in order to maximise the feeding rate during the working process, and, at the same time, minimise the tool wear and the loads on the shaft of the electrical spindle, with a considerable improvement in the overall production costs.     

凸轮廓线插补误差及插补点的分割

论述了在ＮＣ机床上加工凸轮廓线时轮廓插补误差的确定方法,指出了直线插补和圆弧插补的应用范围,建立了分割插补点的表达式     

型腔尖角的轨迹优化

在铣削型腔尖角加工过程中,当环切法加工的行间距离比较大时,型腔尖角处将会出现加工残余.由于刀具与工件的接触线增加,使得尖角处铣削力增大.因此,采用了双圆弧过渡来处理型腔中的尖角,该方法能保证以尽可能大的行距走刀,缩短了加工时问,提高了加工效率,同时还可以清除尖角处的残余留量.尖角处刀具轨迹进行合理优化后,刀具沿着改进的轨迹快速运行,满足了高速铣削型腔的加工要求.最后,实验验证了该方法的有效性.     

基于机器视觉的五坐标机床旋转轴误差检测方法

提出了一种利用机器视觉技术对五坐标机床旋转轴转角定位误差进行检测的方法。首先,通过制作特定的标志,用CCD相机获取标志图像;然后,通过数字图像处理技术对所获得的图像进行分析处理;最后,根据标志在不同位置处的相对转角偏差计算机床旋转轴的转角定位误差,实现五坐标机床旋转轴转角定位误差的辨识和测量。同时,将该方法与传统检测方法进行对比,实验结果表明,所提出的检测方法简单、高效,可以实现机床旋转轴误差的快速检测,并为五坐标机床旋转轴误差的补偿提供了计算依据。     

基于微分变化构造法的数控机床几何误差补偿方法

为了使得机床误差建模与补偿过程紧密联系,同时避免雅可比矩阵繁琐的计算,提出一种基于微分变化构造法的机床几何误差补偿方法。根据坐标系微分变化矩阵建立机床几何误差模型。基于机床正向运动链顺序建立各个运动轴微分变化矩阵,结合各个运动轴几何误差对应的微分运动矢量计算得到运动轴几何误差对刀具精度影响,相加得到刀具坐标下的综合微分变化矩阵,通过机床正向运动学模型将刀具综合误差转换到工作台坐标系下得到机床刀具位置误差。采用微分变化构造法提取各个运动轴微分变化矩阵相应子矩阵构造得到机床雅可比矩阵,计算刀具坐标系综合误差对应运动轴补偿量得到机床补偿加工代码,微分变化构造法无需额外计算,且重新使用建模过程建立的矩阵。在北京精雕Carver800T加工中心进行实验,补偿后工件总误差降低了30%左右,验证了基于微分变化构造法的几何误差补偿方法的有效性。     

埋钻事故分析及预防措施

本文对埋钻事故进行分析,提出了预防措施,结合工程实例,对埋钻事故分析更加清晰.