A Windows bitmap-based numerically controlled sculpture method and its application

Bitmap （BMP） is a widely used format in image processing. With the combination of the digital image processing and computer numerically controlled （NC） techniques, we developed a bitmap-based NC single-step and multi-dot method. An example was provided to illustrate the application and principle of this bitmap-based method in our newly innovated sandblasting glass NC sculpture system.

Bayesian zero-failure reliability modeling and assessment method for multiple numerical control(NC) machine tools

A new problem that classical statistical methods are incapable of solving is reliability modeling and assessment when multiple numerical control machine tools(NCMTs) reveal zero failures after a reliability test. Thus, the zero-failure data form and corresponding Bayesian model are developed to solve the zero-failure problem of NCMTs, for which no previous suitable statistical model has been developed. An expert-judgment process that incorporates prior information is presented to solve the difficulty in obtaining reliable prior distributions of Weibull parameters. The equations for the posterior distribution of the parameter vector and the Markov chain Monte Carlo(MCMC) algorithm are derived to solve the difficulty of calculating high-dimensional integration and to obtain parameter estimators. The proposed method is applied to a real case; a corresponding programming code and trick are developed to implement an MCMC simulation in Win BUGS, and a mean time between failures(MTBF) of 1057.9 h is obtained. Given its ability to combine expert judgment, prior information, and data, the proposed reliability modeling and assessment method under the zero failure of NCMTs is validated.

Effect of mandrel on cross section quality of thin-walled tube numerical controlled bending

The effect of mandrel with the structure of ball and socket on the cross section quality of thin-walled tube numerical controlled(NC) bending was studied by numerical simulation method, combined with theoretical (analysis) and experiment. Influencing factors of the mandrel include the count of mandrel heads, the diameter of mandrel and its position. According to the principle of NC tube bending, quality defects possibly produced in thin-walled tube NC bending process were analyzed and two parameters were proposed in order to describe the cross section quality of thin-walled tube NC bending. According to the geometrical dimension of tube and dies, the range of mandrel protrusion was derived. The finite element model of thin-walled tube NC bending was established based on the DYNAFORM platform, and key technological problems were solved. The model was verified by experiment. The effect of the number of mandrel heads, the diameter of mandrel and the protrusion length of mandrel on the cross section quality of thin-walled tube NC bending was revealed and how to choose mandrel parameters was presented.

Java Language for Numerical Control Simulation System Research

Java language is widely used in a variety of development platforms to develop all kinds of application software for its simple and efficient.The programming language owning platform independent is adopted to solve the image flicker,sound loading and other issues by the threading technology,multimedia technology,graphics and point by point comparison techniques.Dynamic real⁃time process simulation is implemented and a two⁃dimensional network of CNC machining simulation system is developed while Java applet application is as a carrier.The simulation results show that the system has a friendly interface and fast calculation speed,and platform portability has a certain practicality and application value.

Performance analysis of a class of networked control systems under data rate constraints

In networked control system (NCS) where control loop is closed over communication network, limited data rate may deteriorate control performance even destabilize the control system. In this paper, performance analysis of a typical second-order control system with data rate constraints is conducted, and the concept of critical data rate (CDR) is presented. In order to find the CDR in NCS, an approximate searching method is proposed to guarantee acceptable control performance.

Bayesian networks modeling for thermal error of numerical control machine tools

The interaction between the heat source location, its intensity, thermal expansion coefficient, the machine system configuration and the running environment creates complex thermal behavior of a machine tool, and also makes thermal error prediction difficult. To address this issue, a novel prediction method for machine tool thermal error based on Bayesian networks (BNs) was presented. The method described causal relationships of factors inducing thermal deformation by graph theory and estimated the thermal error by Bayesian statistical techniques. Due to the effective combination of domain knowledge and sampled data, the BN method could adapt to the change of running state of machine, and obtain satisfactory prediction accuracy. Ex- periments on spindle thermal deformation were conducted to evaluate the modeling performance. Experimental results indicate that the BN method performs far better than the least squares (LS) analysis in terms of modeling estimation accuracy.

Carbon Emission Modeling and Analysis in Manufacturing Process for Numerical Control Machine Tools

Reducing carbon emissions( CEs) is the urgent demand all over the world. In order to realize the low-carbon numerical control( NC) machining, the evaluation model of a part's manufacturing carbon emission with NC machine tools was built by considering the influences of the cutting tool geometrical parameters.The manufacturing CEs were produced by electric power,cutting tools,and cutting fluid consumed in manufacturing process. The parameters of cutting tools affected not only the CEs,but also the machining quality. Then the actual constraint models of the machine performance,machining quality were given in order to optimize the cutting parameters and achieve the low-CEs. Finally,a case was given to analyze the influences of the cutting tool angles on the manufacturing CEs. The results show that the CEs decrease as the rake angle and edge angle increase under the constraints of the machine specifications and machining quality.

基于通用五坐标数控机床螺旋锥齿轮NC加工研究

基于空间曲面共轭原理 ,确定齿轮切齿矢量关系 ,建立了螺旋锥齿轮的齿面矢量方程。利用空间坐标系的变换 ,确定出刀具相对工件的位置和姿态 ,实现刀具与工件的相对运动 ,从而将传统的螺旋锥齿轮机床加工调整参数转换为适合 NC机床加工的运动参数。进行了五轴加工的刀具扫描体计算。在计算机上 ,对螺旋锥齿轮数控加工进行了仿真 ,给出了相应的计算和实验结果。在通用五坐标数控机床上实现螺旋锥齿轮加工 ,确定出螺旋锥齿轮

FANUC数控机床远程监控DNC系统开发和研究

针对具有以太网功能的Fanuc数控机床和数字化检测设备,利用SQL Server数据库和.Net平台,开发一套基于Socket通信和多线程技术的数控机床和设备远程监控DNC(distributed numerical control)系统。系统可以对多台数控机床和具有通讯功能的质量检测设备同时进行数据的实时采集,并实现机床和设备的状态信息监控、数据集成管理、效能分析、远程故障诊断、车间生产管理和产品质量管控等功能,保障数据的完备性,实现了制造基础数据的集成。介绍了Fanuc数控机床远程监控DNC系统的系统架构设计,针对每一个功能模块的设计和实现方法进行了论述,并对系统程序的工作流程、数据的解析方法和报警监控机制进行了介绍。通过在制造工厂的实际应用,验证了系统的可靠性。

STEP-NC数控技术研究进展

为全面掌握STEP-NC标准的产生、发展与研究情况,分析和总结了近10年来相关领域的研究成果。在分析和总结过程中,将相关研究分为5个主要方向,分别总结了各个研究方向的研究情况和存在的问题,归纳出未来研究中的主要科学问题和技术难点;指出STEP-NC制造系统的核心技术;提出STEP-NC制造系统架构和STEP-NC数控系统的发展趋势。

基于 Dexel 模型的 NC 加工仿真和验证研究

对基于Ｄｅｘｅｌ模型的ＮＣ加工仿真和验证进行了研究。在物空间中模拟ＮＣ加工的材料去除过程及验证加工结果，使用独立的坐标系构造物体的Ｄｅｘｅｌ模型，以支持观察定义的动态改变，并通过“移动实例”来近似描述刀具扫描体，从而提高五轴ＮＣ加工仿真计算效率。

STEP-NC控制器及其刀轨规划方法研究

为实现产品模型数据交换标准—数控程序在传统数控机床上的应用,提出了产品模型数据交换标准—数控程序的刀轨规划方法。首先,概述了产品模型数据交换标准—数控程序控制器的类型及其3大核心功能模块,分析和研究了刀轨规划过程中坐标系转换问题,给出了利用产品模型数据交换标准—数控程序实体索引映射表规划加工特征刀轨的方法和步骤,着重分析了平面和型腔两个加工特征的加工策略,并基于上述方法给出了具体的规划方法流程图。最后,结合一个基于平面、孔和型腔3个加工特征的产品模型数据交换标准—数控程序实例,将所规划出的G代码程序在配备开放式数控系统HITCNC的3轴数控铣床上进行实际加工,实验结果证明,该刀轨规划方法是正确可行的,并具有一定的通用性。

NC代码翻译器检错模块的设计

在分析数控程序的组成和特点的基础上 ,提出了一种NC代码翻译器检错模块的设计方法 ,并给出了详细的模块分解图。经过实践证明 ,这种方法是切实可行的。

定制家具板件数控钻孔作业时间预测模型

【目的】为实现大规模定制家具更高效、更低碳的智能制造,有必要在自动化、连续化生产的基础上实施更精准的智慧生产决策,将生产管理由传统的批次级推进到板件级,以差异化的工序作业时间为基础开展生产调度。本研究通过分析数控钻孔作业时间的关键影响因素,构建可预测每一张板件数控钻孔作业时间的数学模型,在生产前获得较为精准的作业时间数据,解决定制家具板件差异化作业时间数据缺失的现实问题,为定制家具的板件级生产调度夯实数据基础。【方法】基于定制家具制造实际,从数控钻孔加工中心的作业逻辑着手,分析不同数据条件下影响数控钻孔作业时间的关键因素,通过MES(制造执行系统)从设备底层采集6万余条历史作业时间数据,构建解析程序提取关键影响因素,搭建使用Mish激活函数的3层人工神经网络模型,并引入动量和学习率衰减算法提高模型精度和运算效率,实现定制家具数控钻孔工序板件级作业时间的预测。【结果】不同数据条件下,人工神经网络模型可实现良好预测效果,其中基于数控程序提取的9维变量对平均作业时间的预测误差率为2.68%,具备对工序总体效能进行预测的能力;单一板件预测结果平均绝对误差为2.87 s,显著优于同等数据条件下的常规线性回归模型,对指导板件级精准调度具有实际意义。【结论】通过MES大量采集历史作业时间数据,构建解析程序,提取关键影响因素,基于制造大数据搭建3层人工神经网络模型,能够较精准预测板件级数控钻孔作业时间,为实现定制家具制造过程的设备与工艺优化、基于单张板件开展精准生产调度、构建家具制造数字孪生车间打下良好数据基础,推动智能制造在定制家具领域的实践。

基于STEP-NC的可互操作CAPP/CAM系统

通过分析STEP-NC数据结构,建立了基于STEP-NC的可互操作的计算机辅助工艺设计系统的总体结构。详细解释了AP203文件数据类型、C++数据类型和SQL Server数据类型的映射方法,以及AP203文件映射成几何信息库的方法。研究了AP203文件的词法分析过程、几何信息库的建立、操作过程、AP203文件和几何信息库的映射过程,以及基于ISO14649标准的STEP-NC程序生成过程。基于上述研究,开发了基于STEP-NC的可互操作计算机辅助工艺设计系统,并通过实例证明了系统的可行性。

基于DNC的网络制造技术的研究与应用

随着计算机技术、通讯技术和数控技术的发展以及制造自动化的需要,DNC技术得到越来越广泛的应用。目前,以CIMS为代表的企业信息化理念已经受到现代化企业越来越多的重视。DNC也逐渐由单一的程序传输演变为集分布式程序通讯、程序编辑与仿真、数控程序管理等强大功能于一体的综合系统,DNC成为MES等系统的最重要一环。文章讨论了基于DNC的网络制造技术在高校中的研究与应用,分析了基于DNC的网络制造系统的组成及特点,总结了网络制造系统实现的功能和关键技术,并强调了数字化设计与网络制造在先进制造技术中的地位及意义。

面向铣削加工的STEP-NC文件到G代码转换技术

为使STEP-NC能在传统的数控系统中得到应用,研究了面向铣削加工的STEP-NC数控文件到传统G代码程序的转换技术,提出了一种面向制造特征的刀具轨迹规划方法。首先对制造特征进行分类,然后为每类制造特征设计走刀轨迹模型,在进行G代码转换时,通过前置处理将制造特征的走刀轨迹模型转换成对应数控系统的宏程序,不但提高了G代码的转换效率,而且缩短了G代码程序的长度。论述了STEP-NC文件信息提取和信息处理技术,以及G代码程序自动转换过程。最后,以一个铣削类零件为例,对上述技术进行了测试和验证。

基于STEP-NC的相交特征识别技术

为有效识别2.5维相交特征,提出一种新的基于图和痕迹的相交特征识别算法。该算法首先对零件模型进行处理,提取加工特征面,识别时只考虑加工特征面,降低了零件图的搜索空间且不影响特征识别的正确率;通过建立相交特征拆分因子队列,并采用自动计算和交互式相结合的方式确定最优依赖特征面,能够比较准确地分离相交特征;根据特征基面对STEP-NC定义的制造特征进行编码,相对于子图匹配和规则匹配,该方法能够快速和有效地匹配特征。通过具体实例验证了算法的有效性和可行性。

面向网络化制造的DNC系统

为了提高系统对数控设备的利用率,通过研究网络制造模式下DNC系统的结构及其运行模式,提出了一种基于以太网的面向串行通信机床的DNC系统(PowerDNC)。系统以ZWORLD公司生产的BL2010单板机为DNC系统控制器,确定了DNC系统通信结构的构建方案,并对系统实现的关键(服务层和代理层)进行了深入的研究,为只具有串行通信接口的数控设备的联网提供了一条有效的途径。实践证明,具有重要的意义。

基于CNC实时监测数据驱动方法的钛合金高速铣削刀具寿命预测

针对车间内不同设备的数据结构不一致导致车间监控数据中存在大量的多源异构数据,难以通过单一的通信协议采集与监控的问题,研究了基于OPC-UA技术与MTConnect协议的刀具、机床的数据模型、通信架构及访问策略,解决了多源异构数据的采集问题。针对硬质合金刀具在高速铣削钛合金工件时磨损较快、刀具剩余寿命的实时预测难度大的问题,建立了一种基于PCA前置处理数据的神经网络模型,实现了基于刀具剩余寿命的刀具健康状态信息的实时监测和预测。