一种新的数控现场自动编程方法

数控技术的飞速发展对数控编程的高效性、便捷性提出了更高的要求,为满足车间工程技术人员现场编程的需求,本文提出一种适用于数控现场自动编程的方法.根据不同的加工零件轮廓图形,该方法采用以DXF文件为对象的自动编程和图形尺寸直接输入自动编程两种编程方式,生成数控加工程序,并通过实验证明该方法能使数控编程更灵活、高效.     

集成于CAD系统的数控线切割自动编程系统

本文以具体例子说明了从CAD系统的零件描述中自动生成数控线切割程序系统的设计方法。读系统从提取CAD数据转换文件中的信息开始,自动识别零件的内外轮廓,确定切割方向和走刀路线,最终生成通用的数控程序,并利用后处理程序转换成特定数控加工程序。     

通用后置处理系统介绍

通用后置处理系统介绍北京航空航天大学李佳，朱心雄后置处理系统概况后置处理是数控加工自动编程的重要内容之一，它将计算程序计算出的刀具轨迹（或零件轮廓）数据、工艺参数及其它加工信息转换为数控加工程序。由于不同数控机床系统所使用的数控指令可能不同，机床的辅...     

基于几何特性的槽加工刀具选取算法

刀具选取是复杂零件数控加工编程的一项重要内容,为实现数控加工程序编制过程中自动选取加工刀具,提高数控加工及其编程效率和质量,结合飞机整体壁板数控加工编程及其粗加工特点,提出基于几何特性的槽加工刀具自动选取算法.在分析刀具与可切削区域间关系的基础上,对Voronoi Mountain定义域进行修正,建立切削轮廓45°拔模体;并给出刀具的可切削面积、残留不可切削面积,以及小刀具半径计算方法;最后根据整体加工时间最短的原则确定最优加工刀具.该算法已在"飞机壁板快速数控加工编程系统"项目中得以应用,结果证明了其是可行、有效的.     

循环程序在航空零件高效批量生产中的应用

零件加工在试制阶段与批量生产阶段是完全不同的加工模式,但是在实际加工生产过程中,往往发现批量生产的零件,依然采用试制阶段的加工模式。笔者通过应用研究,利用自动编程软件编制循环数控程序,把批量生产零件中的刀具规格、切削参数和走刀路线等固化在程序中,经过试验加工,证明循环数控程序减少了操作者的劳动量,提高了机床的使用率和零件的加工效率,尤其是在零件大批量生产过程中,这种优势更加明显。目前该循环数控程序加工模式已在笔者所在公司内盘类零件加工中得到了应用,并取得了很好效果。     

数控加工仿真系统的真实性研究

数控机床加工技术的程序编制,是采用数控自动编程软件对二维的零件图样进行三维造型设计,然后利用软件自动生成加工程序,并将生成的加工程序送到数控机床进行零件加工。目前常用的数控自动编程软件有MasterCAM、CAXA、NX和Pro／ENGIN旺R等软件。对复杂零件的加工,则大都是采用软件进行计算机建模和仿真,模拟数控机床实际的加工方法和加工路线。这不仅能检验数控代码的正确性,     

数控加工仿真系统的真实性研究

数控机床加工技术的程序编制,是采用数控自动编程软件对二维的零件图样进行三维造型设计,然后利用软件自动生成加工程序,并将生成的加工程序送到数控机床进行零件加工。目前常用的数控自动编程软件有MasterCAM、CAXA、NX和Pro/ENGINEER等软件。     

平面凸轮轮廓在数控铣床的磨削加工

本文以某公司铜线凸轮轮廓的磨削加工为例,经修整磨削,砂轮半径值吻合该凸轮的过渡半径值,采用$TC_DP6 [T,D]刀具半径补偿指令在数控铣床磨削加工程序中自动赋值。实际磨削加工证明,该凸轮轮廓的磨削加工工序合理,基于CAM自动生成程序,加入参数编程指令、$TC_DP6[T,D]刀具半径补偿指令磨削加工的方法可行、简便,确保了凸轮轮廓加工的质量及效率。     

凸轮轴靠模的CAD／CAM系统

本系统完成盘形凸轮轴靠模凸轮轮廓的设计和数控加工的ＮＣ程序编制，并利用所加工出的凸轮轴靠模在数控磨床上加工出符合图纸要求的凸轮轴零件。     

凸轮轴靠模的CAD／CAM系统

本系统完成盘形凸轮轴靠模凸轮轮廓的设计和数控加工的ＮＣ程序编制，并利用所加工出的凸轮轴靠模在数控磨床上加工出符合图纸要求的凸轮轴零件。     

Automated surface subdivision and tool path generation for -axis CNC machining of sculptured parts

As an innovative and cost-effective method for carrying out multiple-axis CNC machining, -axis CNC machining technique adds an automatic indexing/rotary table with two additional discrete rotations to a regular 3-axis CNC machine, to improve its ability and efficiency for machining complex sculptured parts. In this work, a new tool path generation method to automatically subdivide a complex sculptured surface into a number of easy-to-machine surface patches; identify the favorable machining set-up/orientation for each patch; and generate effective 3-axis CNC tool paths for each patch is introduced. The method and its advantages are illustrated using an example of sculptured surface machining. The work contributes to automated multiple-axis CNC tool path generation for sculptured part machining and forms a foundation for further research.     

Machine-vision-based identification of broken inserts in edge profile milling heads

This paper presents a reliable machine vision system to automatically detect inserts and determine if they are broken. Unlike the machining operations studied in the literature, we are dealing with edge milling head tools for aggressive machining of thick plates (up to 12 centimetres) in a single pass. The studied cutting head tool is characterised by its relatively high number of inserts (up to 30) which makes the localisation of inserts a key aspect. The identification of broken inserts is critical for a proper tool monitoring system. In the method that we propose, we first localise the screws of the inserts and then we determine the expected position and orientation of the cutting edge by applying some geometrical operations. We compute the deviations from the expected cutting edge to the real edge of the inserts to determine if an insert is broken. We evaluated the proposed method on a new dataset that we acquired and made public. The obtained result (a harmonic mean of precision and recall 91.43%) shows that the machine vision system that we present is effective and suitable for the identification of broken inserts in machining head tools and ready to be installed in an on-line system.     

基于图像检索的飞机零部件查询系统研究

在飞机维护工作中,广泛应用的交互式电子技术手册查询是依靠关键字或目录的方式。针对交互式电子技术手册查询对机务人员要求较高、效率较低等问题,提出了一种基于形状特征的飞机零部件图像检索方法。首先对待检索飞机零部件图像进行预处理,提取目标的形状轮廓特征,计算零部件轮廓的矩不变量;其次通过欧式距离进行待检索图像与数据样本集的特...     

Modelling and implementing circular sawblade stone cutting processes in STEP-NC

The paper presents a STEP-NC compliant implementation of circular sawblade stone cutting machining processes. Although some stone machining processes has been already covered in the STEP-NC research and standardization initiatives (as for instance stone machining through stone milling machines), there have not been yet, however, any detailed model proposal to cover circular sawblade stone cutting operations. Sawblade cutting technology for stone parts have several specific parameters with no clear equivalent technologies as defined in milling, turning, etc. The paper reviews main characteristics of the circular sawblade stone cutting machining operations, and proposes a STEP-NC extended model based on the selection and definition of new features and on the modelling of these stone cutting operations. The resulting model is the base for the development of the STEP-NC stone cutting CAM and CNC machine. The machine architecture is designed to be able to react to changes in the machining conditions, very common in this technology. The system is based on the definition of features to be communicated to the controller. The controller has the objective of machining the features, and it is able to re planning, on real time, the work to get them despite changing conditions in the stone or in the disc.     

Snake模型在雨滴边缘检测中的应用

数字摄像技术在降水粒子的自动观测中具有非常好的应用前景,如何在数字图像中准确地进行降水粒子的边缘检测是其中的一项关键技术。Snake模型具有很好的融合图像上层知识和底层特征的能力,能够实现目标轮廓的准确定位。结合雨滴图像自身的特点,提出了目标形心的自动标定方法,在此基础上改进了Snake模型初始轮廓点的选取方法,并通过贪婪算法进行迭代处理,实现了基于Snake模型的雨滴边缘检测算法。算法能够准确地对数字图像中的雨滴边缘轮廓进行检测,且具有较好的稳定性。与传统的边缘检测算子相比,该方法对雨滴图像获得了更好的边缘检测效果。     

A : A tool for identifying and repairing un-machinable shapes in designs

Providing early feedback on the manufacturability of a part design can greatly improve the quality of the product while reducing the time and cost of production. However, the necessary manufacturing knowledge is not always available. Computer tools that can provide this manufacturing knowledge by analyzing a design suggesting changes to improve its manufacturability would be a valuable asset to a designer. To this end, we present an approach to automatically generate redesign suggestions to improve the manufacturability of machined parts. Novel aspects of this approach include the ability to identify un-machinable shapes in a part and transform them into machinable features and to automatically identify the possible shape transformations based on properties of the machining equipment. This increases the scope of redesign generation tools by allowing them to be applied to parts that are not already machinable. We have developed a system called automated redesign for machined parts ( ) that assists users in repairing parts that contain un-machinable shapes.     

Digital Twin-driven machining process for thin-walled part manufacturing

Thin-walled parts are widely used in the aerospace, shipbuilding, and automotive industry, but due to its unique structure and high accuracy requirements, which leads to an increase in scrapped parts, high cost in production, and a more extended period in the trial machining process. However, to adapt to fast production cycles and increase the efficiency of thin-walled parts machining, this paper presents a Digital Twin-driven thin-walled part manufacturing framework to allow the machine operator to manage the product changes, make the start-up phases faster and more accurate. The framework has three parts: preparation, machining, and measurement, driven by Digital Twin technologies in detail. By establishing and updating the workpiece Digital Twin under a different status, various manufacturing information and data can be integrated and available to machine operators and other Digital Twins. It can serve as a guideline for establishing the machine tool and workpiece Digital Twin and integrating them into the machining process. It provides the machine operator opportunities to interact with both the physical manufacturing process and its digital data in real-time. The digital representation of the physical process can support them to manage the trial machining from different aspects. In addition, a demonstrative case study is presented to explain the implementation of this framework in a real manufacturing environment.     

基于机器视觉的FPC嵌入式检测系统

针对FPC(柔性印刷电路板)缺陷的特点,设计了基于机器视觉的嵌入式检测系统;该系统以线阵CCD为视觉传感器,DSP为处理器核心,完成图像的采集和存储;基于局部自动阈值分割后的二值化图像,采用多尺度的数学形态学抑制噪声,突显边缘细节;结合线宽评价和局部生长的图像匹配算法,准确实现产品缺陷定位识别功能;实验结果表明:系统能准确识别检测产品中存在的各种缺陷,图像检测速度达到了每秒20帧,具有良好的实用性.     

A novel methodology for cross-technology interoperability in CNC machining

In CNC part programmes, the lack of standardisation for representing part geometry and semantics of manufacturing operations leads to the necessity for existence of a unique part programme for each machine. Generating multiple programmes for producing the same part is not a value adding activity and is very time consuming. This wasteful activity can be eliminated if users are given the ability to write an NC program for a specific machine and robustly convert the program to syntax suitable for another CNC machine with a different structure. This, cross-technology interoperability, would enable for parts manufactured on old CNC machines using legacy code to be manufactured on new CNC machines by automatically converting the programmes. Every NC programme is written based on various categories of information such as: cutting tool specifications, process planning knowledge and machine tool information. This paper presents an approach for cross-technology interoperability by refining high-level process information (i.e., geometric features on the part and embedded manufacturing resource data) from NC programmes. These refined items of information stored in compliance with the ISO14649 (STEP-NC) standard may then be combined with new manufacturing resource information to generate NC code in a format that is compatible with machines based on different technologies. The authors provide a framework for this process of identification, semantic interpretation and re-integration of information. The focus of this paper is on asymmetric rotational components as the initial application area. To demonstrate the proposed cross-technology interoperability approach, a C-axis CNC turn–mill machine and a 4 axis CNC machining centre have been used with a simple test component.     

Algorithms for selecting cutters in multi-part milling problems

This paper describes geometric algorithms for automatically selecting an optimal sequence of cutters for machining a set of 2.5-D parts. In milling operations, cutter size affects the machining time significantly. Meanwhile, if the batch size is small, it is also important to shorten the time spent on loading tools into the tool magazine and establishing z-length compensation values. Therefore, in small-batch manufacturing, if we can select a set of milling tools that will produce good machining time on more than one type of parts, then several unnecessary machine-tool reconfiguration operations can be eliminated. In selecting milling cutters we consider both the tool loading time and the machining time and generate solutions that allow us to minimize the total machining time. In this paper we first present algorithms for finding the area that can be cut by a given cutter. Then we describe a graph search formulation for the tool selection problem. Finally, the optimal sequence of cutters is selected by using Dijkstra's shortest path planning algorithm.