共查询到20条相似文献,搜索用时 15 毫秒
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Engine pistons are generally cut with a copy machine or a CNC machine. In recent years, CNC machining has become more popular
due to the necessity for increased productivity and accuracy in piston machining. CL data are essential for CNC machining,
and such data are usually generated from a 3D CAD model. When using a 3D CAD model, the intersection curves between the surfaces
and the cross-sectional plane must be calculated, which is both time-consuming and imprecise. In this paper, a geometric equation
for the sidewall of a piston is proposed as a solution to this problem. The geometry consists of an ellipse, recesses, eccentricities,
and an offset. The equation for the sidewall of a piston is expressed in terms of the distance from the center. This equation
makes it possible to calculate CL data very quickly, and facilitates the compensation of tracking error. A specialized four-axis
CNC lathe, suitable for machining the sidewall of a piston, is also introduced. The proposed method has been tested by actual
turning using this four-axis lathe. The results demonstrate the practicality of the method in the manufacturing of pistons. 相似文献
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针对数控铣床不断老化导致刀具磨损预测模型误差较大,加工过程中动态数据难以在线采集等问题,提出一种数字孪生驱动的刀具磨损在线监测方法。采用神经网络对加工过程中的多源数据进行特征提取,建立考虑机床老化的刀具磨损时变偏差量化模型,并在此基础上提出数控铣削刀具磨损的在线预测方法;开发了面向刀具磨损的数控铣削数字孪生系统,在线感知加工过程中的动态数据并实时仿真刀具磨损过程;最后,将该方法应用于实际加工中并与其他的预测方法进行了对比,结果表明该方法有效降低了机床老化带来的误差,实现了刀具磨损的精确预测。 相似文献
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J. Gao D.T. Zheng N. Gindy 《The International Journal of Advanced Manufacturing Technology》2004,24(7-8):573-581
Feature-based CAD/CAM integration is a technology used to realise automatic transmission and conversion of component information among CAD, CAPP and CAM applications. A feature is the medium of information transmission in the integration. Since a process planning downstream application has a different viewpoint from the component designer, feature conversion or feature extraction methodology is used to create a machining feature model based on the design feature model. One of the major difficulties in generating machining features is the preservation of feature integrity because of feature interactivity. The most current research, therefore, focuses on the planar-type form feature conversion. This paper discusses the problem of feature interactivity and proposes a feature-based approach to generating hole-series machining features from a design feature model. Hole-series features are important machining features for gearbox components used in machine tools. These kinds of features cannot be obtained directly from a design feature database. A constraint-based method is developed in this paper to define a hole-series feature model based on the geometric and topological information extracted from the design database. In addition, a STEP file is generated to interface the converted machining feature model with the downstream CAPP application. The implemented feature conversion system is verified by considering its application to some component examples and the developed prototype CAPP system. This revised version was published online in October 2004 with a correction to the issue number. 相似文献
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论述了基于制造特征的高速加工技术,分析了目前普通数控加工中CAD/CAM/CNC系统信息集成的缺陷,针对高速加工提出了CAD/CAM/CNC集成解决方案,并给出具体的加工实例,生成STEP-NC数控程序。 相似文献
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基于UG实体模型的特征信息提取技术研究 总被引:4,自引:0,他引:4
CAPP系统用“制造特征”来产生与零件加工探作相关的信息。然而,这些制造特征信息在传统的CAD系统中并没有明确的包含。本文尝试着集成特征识别技术和基于特征的设计技术实现从设计特征模型中提取出制造特征。而且,随着“全息模型”技术的发展,产品的三维设计模型中逐步包含了一些CAPP系统所必需的零件信息,如零件表面粗糙度、几何公差和基准等。本文也提出一种方法将它们从零件模型的工程数据库中提取出来。 相似文献
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Extraction of manufacturing information from design-by-feature solid model through feature recognition 总被引:1,自引:1,他引:0
Mohammad T. Hayasi Bahram Asiabanpour 《The International Journal of Advanced Manufacturing Technology》2009,44(11-12):1191-1203
Feature recognition is the key to the computer-aided design (CAD) and computer-aided manufacturing (CAM) integration to build a computer-integrated manufacturing system. There are two approaches to CAD feature recognition: platform-dependent and platform-independent. In the platform-independent approach, the part’s geometrical data are extracted from a neutral file such as DXF, IGES, or STEP. In contrast, the platform-dependent approach extracts the information of the design features directly from a design-by-feature solid model through the object-oriented model of a part. This paper explains a platform-dependent approach which is implemented to translate design features into manufacturing information. This approach begins with simplification using the suppression of fillets, and clustering non-intersecting design features is done. Then, the rule-based method is employed in order to recognize machining features. Finally, the needed manufacturing information such as tool accessing direction, dimensions, material removal regions, and geometrical and topological data is recognized. The application of the proposed system would be exhibited in generating machine path code for rapid prototyping and CNC machines and providing a database for computer-aided process planning. The proposed system was implemented on Autodesk Inventor and successfully tested for many complex 3D models. 相似文献
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以柔性制造系统中数控设备为制造单元并作为控制对象,以实现CAD/CAM/CAPP智能化、集成化地制造.通过分析网络化环境下数控设备远程运行与故障诊断系统的特点,提出该系统的体系结构,使用BP神经网络进行数控设备的故障诊断,阐述了基于BP神经网络和专家系统混合的神经网络故障诊断专家系统的基本原理,并分析了基于EJB的数控... 相似文献
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Real-Time Prediction of Workpiece Errors for a CNC Turning Centre, Part 2. Modelling and Estimation of Thermally Induced Errors 总被引:3,自引:3,他引:0
X. Li 《The International Journal of Advanced Manufacturing Technology》2001,17(9):654-658
Real-time modelling and estimation of thermally induced error have very important contributions for precision machining. In
this paper, a novel radial basis function (RBF) neural network, which combines a regression tree and a radial basis function,
has been considered and selected to model the thermally induced errors of CNC turning centres. Then, a simple and low-cost
compact measurement system is applied to measure the time variant thermal errors of CNC turning centres. The thermally induced
errors are estimated in real-time using the trained RBF neural network. The application of the measurement system and the
novel RBF neural network are described in detail in this paper. The proposed approach is verified through some tests under
different cutting conditions. 相似文献
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开放式数控系统是为适应现代制造业发展的潮流而提出的,但是对传统的数控代码所代表的数控系统的改造,并不能适应网络化制造和数字化制造的需要,也不利于系统的开发。STEP-NC标准作为新一代数控标准,继承了STEP标准中的产品信息,同时具有开放性,可以作为CAD/CAM/CNC集成的桥梁。利用STEP-NC面向特征和面向对象的特点,建立各制造特征的加工工步,就可以开发相应的数控系统,实现面向制造特征的数控加工,从而达到CAD/CAM/CNC信息集成的目的。 相似文献
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质量控制图在线智能诊断分析系统 总被引:7,自引:2,他引:7
在计算机集成制造系统环境下,为了有效实现工序质量控制,提出了质量控制图的在线智能诊断分析系统框架,它由控制图模式识别、参数估计、专家诊断分析系统和加工参数调整系统四个模块组成。在该系统中,采用了一种适用于模式识别与分类的新型神经网络模型——局部有监督特征映射网络,将其应用于该系统的控制图模式识别和参数估计中。仿真实验和应用实例表明,识别和分类结果与实际相符,并可以保证实时性。 相似文献
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Hong Lu Zhi Liu Shaojun Wang 《The International Journal of Advanced Manufacturing Technology》2014,73(1-4):209-227
Nowadays, the demand for high-quality enveloping surface parts is increasing in machinery, aviation, military, and many other fields. Given the complexity of the surfaces, the enveloping surfaces parts are usually processed by grinding method. This grinding process is low in precision and poor in efficiency for lack of accurate digital CAD model of these parts. In this paper, a new modeling method for the complicated enveloping parts has been developed. The digital CAD model is constructed by using vector representation, transformation matrix, and spatial meshing theory. Next, a better computerized numerical control (CNC) machining code is generated based on the accurate digital CAD model, and a high-quality envelope surface could be machined on the basis of the code in CNC machining center. The normal vector algorithm is adopted to detect and avoid collision and interference during the processing. Finally, the digital CAD models of a planar double-enveloping worm and worm wheel famous at difficulty in modeling and CNC machining have been conducted as an instance. The machining experiment results show that the machining precision of the enveloping surface parts have been increased because the part’s digital CAD model is extraordinarily accurate. 相似文献
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从实体构造、特征识别系统原理出发,阐述了具有代知瞄的特征识别方法,并对其进行分析。运用基于边界匹配的特征识别方法设计一实例实现了特征信息的提取。 相似文献
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讨论了手绘CAD图形输入的识别问题,提出了手绘图形识别方法,对曲线进行线性逼近以抑制噪声并减少识别数据量,提取几何与非几何特征进行粗分段,在此基础上利用基于BP算法的神经网络分类器进行直线和圆弧的分离和识别,以正确实现分段识别并重构图形。 相似文献
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基于几何与公差信息的加工特征识别方法 总被引:1,自引:0,他引:1
为实现计算机辅助设计与计算机辅助工艺规划系统的有效集成,提出了一种同时利用几何信息和公差信息的加工特征识别新方法。建立了加工资源、加工表面和加工方法三类信息模型。提出了切削模式的概念及以之为基础的表面加工方法生成原理和过程。建立了表面加工方法优化选择模型。采用多目标模糊优化结合蚁群算法求解该模型,为每个加工表面选择最优加工方法,并将在同次装夹中采用同一刀具类型和加工条件进行加工的表面聚为加工特征。最后,通过实例测试,验证了该方法的正确性和有效性。 相似文献
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Kaiyong Jiang Changbiao Huang Bin Liu 《The International Journal of Advanced Manufacturing Technology》2011,54(1-4):187-194
Shape deposition manufacturing is an innovative rapid prototyping technology combining CNC machining and deposition processes and in which if a surface of the part is visible from the build direction it can be directly shaped into desired geometry on part material; if the part features are undercut or face away from the build direction, these part features will be sculptured into the support material in order to form a negative cavity at first, then the part material is deposited into this negative cavity in order to replicate these features into part material. This process is cyclically repeated until all segments have been built. Finally, the sacrificial material is removed, and the finished part is left. This innovative technology has the benefits of commercial rapid prototyping technology; meanwhile, it inherits the accuracy and high surface quality of traditional machining process. For this process to be realized, it is essential to decompose the CAD solid model into a series of manufacturable segments which have no undercut surfaces at the data pretreatment step. In this paper, a solid decomposing strategy is proposed with a detailed discussion on the classification of the segments based on the value of triangle face normal vector, and then an algorithm for auto-decomposing a CAD solid model in STL data format is developed. 相似文献