基于MasterCAM 9.1的螺纹铣削工艺分析与编程

螺纹铣削加工在现代机械加工行业已逐步得到应用,但在许多企业、学校,还是通过宏程序或子程序的形式来编制铣削螺纹的程序,其工作量大,难于理解,容易出错。通过对螺纹铣削的成形原理、螺纹铣削的工艺分析,介绍了运用MasterCAM 9.1软件的螺旋铣削功能编制螺纹铣削加工程序的方法。经过实践证明,运用MasterCAM 9.1等软件编程,可很方便地加工铣削内外圆柱、圆锥螺纹,更容易在企业的生产实践中加以推广应用。     

基于伴随灵敏度的暂态稳定预防控制快速算法

针对已有算法难以适应现代电力系统在线预防控制的实时性要求的问题,研究了一种基于伴随灵敏度分析的暂态稳定预防控制快速算法,采用了约束转换技术来缓解大规模电力系统暂态稳定预防控制中的"维数灾"问题,提出了一种优化层-仿真层的双层结构以实现算法:优化层基于预测-校正内点法,利用近似海森矩阵的扩展生成方法以提高算法的准确性和收敛性;仿真层中采用伴随灵敏度方法实现了灵敏度快速计算,并使用非诚实牛顿法和雅克比矩阵重用技术以进一步提高计算速度。研究结果表明,该算法能够显著提高大规模电力系统的暂态稳定预防控制求解效率,且相较其他已有算法体现出极大的速度优势,完全能够达到现代电力系统在线预防控制对控制算法的实时性要求。     

Determining the effect of process parameters on particle size in mechanical milling using the Taguchi method: Measurement and analysis

Micro and nano-particles have been successfully and widely applied in many industrial applications. The mechanical milling process is a popular technique used to produce micro and nano-particles. Therefore, it is very important to improve milling process efficiency and quality by determining the optimal milling parameters. In this study, the effects of the main mechanical milling parameters: milling time, process control agent (PCA), ball to powder ratio (BPR) and milling speed in the planetary ball milling of nanocrystalline Al 2024 powder were optimized by the Taguchi method. Mean particle size (d₅₀) was used to evaluate the effect of process parameters on the mechanical milling process. The orthogonal array experiment is conducted to economically obtain the response measurements. Analysis of variance (ANOVA) and main effect plot are used to determine the significant parameters and set the optimal level for each parameter. The as-received and milled powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and a laser particle size analyzer, respectively. The results indicate that the process control agent significantly affects (84% contribution) the mean particle size (d₅₀) while other parameters have a lower effect (16% contribution). The developed model can be used in the mechanical milling processes in order to determine the optimum milling parameters for minimum particle size.     

基于VC和OpenGL实现虚拟数控铣床及加工过程

提出将虚拟现实技术应用于数控铣削加工仿真系统中,以Visual C 为开发平台,在虚拟场景中,根据数控铣床的结构特点和主要组成单元,以FANUC数控系统为背景,利用OpenGL技术构建出三轴数控铣床的三维虚拟模型,并设计出相应的数控铣削加工仿真系统,详细介绍人机交互界面和数控加工程序执行过程的实现方法,并给出逼真的仿真实例,效果较好,可以应用于数控加工程序的验证、数控技术的教学和培训等场合.     

时钟抖动下加速度测量值的数值双积分误差(英文)

采用蒙特卡洛分析法,对由于时钟抖动造成的加速度计定位误差进行了系统的分析.仿真结果表明,在存在时钟抖动的情况下,加速度测量值是渐近服从高斯分布的,这个结果与理论分析相吻合.对积分距离的方差与时钟抖动之间的关系进行了分析,理论及仿真分析结果都表明了噪声的数值双积分的积分误差与时钟抖动的大小成正比.当输入一个幅值为1g,周期为1 s的正弦波加速度信号时,1 s后数值双积分的积分误差与时钟抖动的比例系数为0.261 1.     

Optimization and sensitivity analysis of geometrical and process parameters to reduce vibration during end milling process

Selection of geometrical and machining parameters has great influence in machining performance. Predictive modeling can be used in optimization and control of process parameters. This study focuses on the optimization and sensitivity analysis of machining parameters, and fine-tuning requirements to obtain better machining performance. A statistical prediction model was developed in terms of tool geometrical parameters such as rake angle, nose radius, and machining parameters such as cutting speed, feed rate, and depth of cut. Central composite response surface methodology with five parameters and five levels was used to create a mathematical model, and the adequacy of the model was checked using analysis of variance. The experiments were conducted on aluminum Al 6351 with high-speed steel end mill cutter. Vibration in terms of acceleration amplitude during end milling was measured with two accelerometers—one in tool holder (channel I) and other in workpiece fixture (channel II) respectively. Optimizations of process parameters were performed using genetic algorithm. Sensitivity analysis was performed using developed equations to identify the parameter exerting most influence on vibration amplitude.     

基于灵敏度分析的龙门横梁多目标优化研究

为减轻横梁质量并提高其静动态特性,首先对横梁进行受力分析,通过灵敏度分析找出各设计变量对横梁质量和最大变形量的影响程度,然后综合考虑横梁的质量和最大变形量,利用响应面法构造回归方程,并对回归方程进行准确性验证,用优化工具箱对横梁进行多目标优化求解,得到最优的尺寸参数.将优化前后的参数进行对比分析.结果表明,优化后的横梁不但质量减轻,而且静动态特性都有所提高.     

基于BPMN的业务流程一体化建模方法

为了给业务分析员提供一种简单易懂、直接支持计算机仿真和执行的可视化业务流程建模方法,提出了业务流程一体化建模概念及方法。该方法以业务分析员为本,用业务流程建模符号可视化描述业务流程,用非结构化方式存储业务流程;基于元素语义细分设计理念,完善了业务流程建模符号规范图形元素的显示语义,引入非图形元素Node,以明确业务流程执行语义,设计了描述业务流程模型的元模型结构及计算机仿真与执行机制。通过实际研发业务流程管理系统,验证了该方法的可行性。     

基于灵敏度分析的某齿轮箱动力修改

为改善齿轮箱的振动特性,提出基于动态灵敏度分析的齿轮箱结构动力修改.通过对某船用齿轮箱进行灵敏度分析,讨论结构参数的变化对其振动模态影响,该方法和结论可以为齿轮箱动力修改提供参考.     

Improved numerical integration method for flowrate of ultrasonic flowmeter based on Gauss quadrature for non-ideal flow fields

Multipath ultrasonic flowmeters with large diameter are widely used in industry. And their measurement performances are sensitive to velocity profiles in conduits. Gauss–Jacobi and Optimized Weighted Integration for Circular Sections (OWICS) method are commonly applied in flow measurement of multipath ultrasonic flowmeters, both of which assume ideal flow in pipes. They are not proper for non-ideal flow measurement. Therefore, an improved numerical integration method for flowrate based on Gauss quadrature is proposed. With this method, optimum relative path heights and corresponding weights are determined according to specific disturbed flows. By comparison Gauss–Jacobi, OWICS with the improved method, the validity of the proposed method is verified for typical disturbed flows based on both theoretical analysis and experiments, and measurement performances of ultrasonic flowmeters are improved significantly.     

凹球面的数控铣削加工实证研究

以凹球面的数控铣削加工为例,详细阐述了利用宏程序编制凹球面加工程序时刀具的选择、刀具轨迹的处理以及刀具进刀的控制算法等问题,并最终编制出凹球面的数控铣削宏程序。同时,还以POWERMILL自动编程软件为背景,详细阐述了凹球面从造型、规划刀具路径到后处理生成加工程序的方法。结合实证研究总结出手工编制宏程序和自动编程的在实际应用中的优缺点。     

基于MATLAB的高速铣削加工再生型颤振的建模与仿真

针对国内高速铣削加工工艺参数选择存在的问题,基于动态铣削力建模和颤振稳定域分析计算,以MATLAB为开发工具,得到了铣削加工再生型颤振仿真算法.通过模态锤击实验获得频响函数,利用Visio Basic软件设计了圆柱立铣刀动力学仿真系统,对整个加工系统的颤振稳定域图形进行仿真,为铣削加工切削参数选择和优化提供了理论依据.实验验证了该仿真算法的有效性和准确性,并在实际应用中取得了良好的效果.     

基于小波分析和模糊控制理论的铣刀磨损监控方法

研制了一种铣刀磨损的监控方法.在该系统中信号采集采用声发射传感器,信号的特征提取采用小波分析的方法,将变换后的尺度系数和各个频段的小波系数作为特征,采用自行设计的Sugeno模糊控制系统进行状态识别,模糊控制系统的输出是刀具磨损的具体值.     

圆墙板专用数控铣床控制系统的设计

研制成功了XYB-Ⅱ型专用数控铣床，论述XYB-Ⅱ型圆墙板专用铣床数控系统的总体设计方案及微控机床工作原理，给出详细的单片机微控系统原理图和自动循环加工软件流程图。采用本机床加工可大幅度降低工人劳动强度，有效提高加工生产率和提高工件精度。     

An isogeometric numerical study of partially and fully implicit schemes for transient adjoint shape sensitivity analysis

Frontiers of Mechanical Engineering - In structural design optimization involving transient responses, time integration scheme plays a crucial role in sensitivity analysis because it affects the...     

多坐标数控铣削加工图形仿真

针对生产厂在多品种刀具生产中所使用的MAHO800C五坐标四联动数控加工中心,分析实现多坐标数控加工仿真系统的方法及其相关的关键技术.实践表明,所开发的仿真系统可有效地实现加工图形的动态显示.     

基于主轴电流的铣削力间接监测方法

实时准确地监测铣削状态对于提高加工质量与加工效率具有重要意义,切削力作为重要的加工状态监测对象,因其监测设备昂贵且安装不便而受到限制,为此提出一种考虑刀具磨损的基于主轴电流的铣削力监测方法.首先基于切削微元理论建立了考虑后刀面磨损的铣削力模型,并通过铣削实验进行铣削力模型系数标定;然后对主轴电流与铣削力的关系进行理论建...     

New predictor-corrector methods based on piecewise polynomial interpolation for milling stability prediction

Abstract

Chatter frequently occurs during cutting operations, which seriously restricts the machining productivity and workpiece accuracy. Consequently, accurate and efficient stability prediction is of great significance to determine stable machining parameters. A cubic Hermite–Newton approximation method which can determine the chatter stability boundaries more efficiently is presented in this paper. The milling dynamic system can be expressed as time-periodic delay differential equations (DDEs) with consideration of the regeneration effect. A typical benchmark example is provided to assess the convergence feature and stability lobes of the cubic Hermite–Newton approximation method and several existing methods. The results indicate that the cubic Hermite–Newton approximation method can achieve satisfactory results. For the sake of developing the cubic Hermite–Newton approximation method with higher convergence rate and computational efficiency, the tooth-passing period is further separated into two distinct phases according to whether the value of coefficient matrix equals to zero. Meanwhile, the linear interpolation polynomial is used to predict milling stability, and then piecewise polynomial interpolation was utilized in two adjacent time intervals to correct this prediction. By adopting the two benchmark examples, the effectiveness of the two new methods can be analyzed using existing methods. The results demonstrate that the two new methods have superior accuracy and efficiency.     

基于面向服务架构消息中间件的业务流程系统集成方法研究

通过分析企业信息化发展阶段及消息中间件和面向服务构架的特点,提出了将面向服务构架和消息中间件结合以解决企业业务流程集成问题的方法.该方法通过使用一种新型的面向服务构架的消息中间件,将其功能发布为Web服务,企业信息系统调用此Web服务可以方便灵活地实现业务流程的集成,为解决企业业务流程集成和设计消息中间件的架构提供了一个新方案,并在某企业的制造执行系统与企业资源计划系统集成中进行了应用.实践表明,本方法具有高效率、高可重用性、配置灵活和使用方便的特点.     

高效干式切法盘形齿轮铣刀铣削力的研究

利用干式盘形成形齿轮铣刀在铣齿机上加工齿轮是提高齿轮加工效率有效途径。铣削力是其中的关键因素。研究了齿轮铣削中的顺铣和逆铣两种工艺方法,推导了铣削力计算公式。实验验证,计算的铣削力与实际铣削力基本吻合,该铣削力计算公式可以为铣削工艺选择提供参考。