基于测量数据NC代码直接生成系统的研究开发

【作者】 龚友平；

【导师】 金涛；

【作者基本信息】 昆明理工大学 ， 机械制造与自动化， 2003， 硕士

【摘要】 20世纪90年代初，逆向工程技术开始引起各国工业界和学术界的高度重视，特别是随着计算机技术及测试技术的发展，利用CAD／CAM技术、先进制造技术来实现产品实物的逆向工程技术，已成为逆向工程技术应用的主要内容。 工业产品设计需要复制，目前基于实物的逆向工程技术应用最广的是进行产品复制和仿制，尤其是外观设计产品，因为不涉及到复杂的动力学分析、材料加工等技术难题，相对容易实现。目前基于CAD／CAM系统的数字扫描技术为实物逆向工程技术提供了有力的支持，在数字化扫描、完成实物的3D重建后，通过NC加工就能快速地制造出模具，最终注塑得到所需的产品，这个过程已成为沿海地区许多产品企业的产品开发模式。然而，整个开发过程中的各个环节，都需要专门的技术人员，且对于部分产品或产品的某一部分，有时并不需要产品的3D模型重建。因此，针对那些曲面相对简单、并要求尽快得到原型的零件，本论文提出由坐标测量数据直接生成NC代码的方法。 在实现由测量数据直接生成NC代码这个过程中，测量数据的获取是整个技术实现的基础；本论文提出了以NC代码直接生成作为后续的数据测量方法。目前，获取测量数据的重要工具为三坐标测量机，但是其种类繁多，所得数据文件格式不一，本论文提出采用中间格式文件的办法可以解决坐标测量机文件格式不一的问题。 三坐标数据的前处理技术是实现NC代码生成的关键技术，因为数据处理的好坏决定生成的NC代码是否正确。本论文提出在的数据处理包括对冗余数据的剔除，必要数据的插补、光顺处理、特征点的识别技术、以及简单图素的拟合技术。最后，生成可供NC代码生成模块使用的数据链表。 目前基于测量数据生成NC代码由两种典型算法：基于仿形测量数据的数控轨迹的生成和基于海量数据NC路径生成算法，本论文针对那些曲面相对简单的零件，直接将测量路径作为数控加工轨迹，可以轻松实现NC代码的转换。 目前有很多成熟的CAD软件都有NC代码生成模块，可以将测量数据输入这些CAD系统获得NC代码。由于测量数据只是单一的数据集合，对于每一个CAD系统来说，都有自己的数据文件，数据文件分图形数据文件、几何模型文件和产品模型文件几种。数据文件的格式与每个CAD系统自己的内部数据模式密切相关，而每个CAD系统自己内部的数据模式一般是不公开的，因而也各不相同。因此，用昆明理工大学硕士学位论文摘要户需要能够在不同的图形文件格式之间转换，即:能够读入其他系统的文件格式并被其他系统读入，从而出现了数据交换文件概念。DXF文件作为AutoCAD系列造型软件的文件接口进行了研究，具有很强的代表性，本论文研究将测量数据转换为DXF文件，并实现了STL观察软件的开发。 本论文根据理论研究结果，在Window NT/98平台上采用VisualC++ 6.0进行系统开发。实现了NC代码的直接生成，DXF文件格式的转换功能，使三坐标测量数据处理的效率和质量得以明显提高。更多还原

【Abstract】 In the beginning of 1990’s, Reverse Engineering technology arises highly attention of many countries’ industrial field and academic field. Especially with the development of computer and test technology, by using CAD/CAM and advanced manufacturing technology, have realized product material Reverse Engineering technology,which has become the main application field of Reverse Engineering technology.Industrial products design needs duplication , now Reverse Engineering based on the prototype applies broadly in products’ duplication and copy , especially products’ appearance , because of not being concerned with technical difficult problems such as complex dynamics analysis and material processing , we can realize relative easily. The digital scanning technology based on the system of CAD/CAM has offered strong support for the Prototype Reverse Engineering technology. After digital scanning and 3 D reconstruction of prototype, we can make mould fast through NC processing, eventually, pour to mould, and then get the product needed. This process has become the product development pattern of a lot of product enterprises in coastal area. However, every link of entire product development needs special technical people, and for partial products or some parts of products do not need 3 D mould reconstruction. So, aim at those parts which have simple curved surfaces and require prototype as soon as possible, the paper put forward the method which generate NC code directly by the coordinate measuring data.During the course of realizing NC code generation directly by measuring data, measuring data acquisition is the foundation of entire technology; This paper gives measuring method which aims at NC code direct generation .Now, the important tool of measuring data acquisition is 3 coordinate measuring machines, since its kinds are numerous, the data files forms are different. The paper give the method--using intermediate form file can solve the problem of different coordinate measure machine file forms.The pre-treatment technology of 3 coordinate data is the crucial technology to realize NC code generation, because it decides whether NC code is right or wrong. The pre-treatment technology includes deleting redundant data, interpolating necessary data, polishing process, distinguishing feature points, and fitting simple graphics, finally generating the data chain table that used for NC code generation.Now NC code generation directly based on measuring data has two typical algorithms: numerical loci generation based on measure data of profile modeling and numerical loci generation based on magnanimity data NC. According to those parts with relatively simple curved surfaces, the paper regard measuring route as the numerical locus, which can realize the conversion of NC code easily.Now, many CAD systems have NC code generation modular, we can put measuring datainto these CAD systems to get NC code. Since measuring data is simple data assemble, but for every CAD system, they have their own data file forms. Data file forms include graph data file, geometry model file and product model file. The own internal data pattern of every CAD system and the form of data file forms is related with their inner pattern closely, thus they are also different. Therefore user needs change between different data files’ form: Can read in the file form of other systems and is read in by other systems, so, there has arisen data exchange file concept. DXF file has very strong representative as the file interface of AutoCAD series modeling software, the paper has studied conversion between measuring data and DXF files and developed viewing software to STL file form.According to the theory research result, this paper has developed system by adopting Visual C + + 6. 0 on the platform of Window NT/98. The system has realized the NC code generation directly, and the conversion of DXF files’ format, and made 3 coordinate measuring data process’s efficiency and quality improved obviously.更多还原