Papers by Keyword: STEP-NC

Abstract: Because of the difficult problem about exchanging and sharing products information between the CAX system and CNC machine, STEP-NC was proposed by EC（European Community）. The domestic research about STEP-NC was still in starting stage, the most of them were the second development of the software provided by the United States STEP Tools company. Based on the research about AP203 and STEP-NC standard, using VC + +6.0 as development platform, programmed directly to read AP203 file, extracted the geometry and topology information of the workpiece, automatically identified manufacturing features. It’s the foundation for the conversion from AP203 to STEP-NC programs.

Abstract: As the next generation of CNC standard, STEP-NC can be used to solve the current problem of information integration in digital manufacturing. With the characteristic of the STEP-NC data structure, the key technologies to approach the process planning by workingstep features based on STEP-NC are studied. Geometric information translating, feature information extraction, process planning, STEP-NC file generating are all involved. The detail of the lexical analysis of the AP203 files, the operating of the geometric information database and the translating from AP203 to geometric information database are studied. Applied the STEP-NC enabled technology, the system of process planning by features is established. The conclusion is useful for 3D process planning and the intelligent machining. The interoperable and integrated information between CAD/CAM is reached.

Abstract: STEP-NC is a promising data interface for CNC, by which a comprehensive set of information regarding the product to be manufactured can be conveyed for the first time to the shop floor. In this paper, the new data model is briefly overviewed and analyzed. Then functionalities and considerations as for implementation of STEP-NC controllers are identified, followed by a conceptual framework proposed for such STEP-NC controllers for a new breed of CNC machine tools featuring autonomy and cooperation. The proposed system is constituted with a planning agent and a machining agent. The former is designed to take responsibility to cooperate with the external systems, to prepare all the data needed in machining and schedule them into unit tasks, while the latter, as one of the planning agent’s local control modules in light of an excellent combination of functionality and reliability, controls the machine tools adaptively. The working mechanism of the whole system is also introduced with an illustration of the operational flow.

Abstract: STEP-NC provides a way for intelligent NC manufacturing and seamless connection of the computer systems in design and manufacturing industries. It also makes it a must for a new breed of CNC machines to interface directly with the new part programs in STEP format (ISO 10303-21). In this paper, the data model and structure of part programs based on STEP-NC (STEP AP 238) are overviewed. Available tools are discussed and a method of extracting the manufacturing information from STEP-NC physical files is presented, and corresponding software module are developed in ST-DeveloperTM environment. With the aid of the STIXTM and ROSETM C++ library, the general information, feature information, technological information are extracted from the STEP-NC file and organized in a tree structure according to the hierarchy of the data model, which is essential to further usage of the manufacturing data, such as process planning, tool-path generating etc.

Abstract: Feature-based modeling is one of key technologies to implement intelligent STEP compliant CNC, which can associate not only geometric and topological information, but also form features, tolerances, material properties and other information which may be used during the process planning and STEP-NC machining. This paper presents a machining feature-based modeler to build parts and exports them as the format of STEP AP224 file. The modeling system provides three main steps to construct a part: (1) selection of raw stock form stock library, (2) selection of predefined machining features according to ISO14649 to be subtracted from the part being designed, and (3) providing information to define the machining feature attributes such as feature size, position, orientation etc. This feature-based modeling system is implemented by using Microsoft C# and NX Open technology in UG NX6.0 environment.

Abstract: This paper presents a simulation system based on STEP-NC that can verify STEP-NC program and demonstrate the running of STEP-NC system (CNC system based on STEP-NC). NC Programs used in the STEP-NC system are in XML format. The overall architecture of the system which consists of feature extraction module, graphical modeling module, movement modeling module, feature library, simulation drive module and user interface is established. Some key technologies to implement simulation system are discussed in details. The simulation system shows great potential to the development and popularization of STEP-NC system.

Abstract: In order to realize STEP compliant NC manufacturing, STEP-NC (ISO 14649) has been developed over last decade by the International Standard Organization as a new data model for CNC programming. This paper proposes a framework for STEP compliant NC programming of the freeform surfaces. The system is supposed to read the CAD model produced by commercial CAD/CAM software and represented in STEP format, prepare the process information, and finally generate the STEP-NC compliant program. Major issues relating to CAD data extraction, toolpath calculation and NC program generation are presented.

Abstract: Today a new model of data transfer between CAD/CAM systems and CNC machines, called STEP-NC, is being developed by the ISO technical Committees. It overcomes the shortcomings of ISO 6983 by specifying machining processes rather than machine motion, using the object-oriented concept of working step. Although the STEP-NC contains abundant geometry information of part and associated process parameters, the tool path is general not included in the STEP-NC program. So before the beginning of the STEP-NC-compliant CNC machining, the tool path should be firstly designed. By analyzing the characteristic of STEP-NC data model for milling, a working step-oriented tool path planning method for milling was proposed in this paper, and the distributed artificial intelligence methods, namely collaborative multi-agent was employed to accomplish tool path planning. Firstly a multi-agent architecture was constructed to allow multiple agents to work cooperatively to realize automation of tool path planning, and then, the function of every kind of agent and the communication between the agents were all described in detail. At last, one test component was designed and simulated to demonstrate the capabilities of this research in the paper.

Abstract: Over the last decade a new data interface for CAM/CNC integration has been established to replace ISO 6983. The new standard, ISO 14649 (STEP-NC), provides a comprehensive data model that describes both geometrical and technological information in an object-oriented way. In order to bridge the gap between such rich-information programs and the legacy CNC systems, this paper presents a framework for manipulating the manufacturing data in STEP-NC part programs. The proposed system provides a basic platform for STEP-NC program interpretation, geometry visualization, micro-process planning and program re-generation. Major issues relating to the realization of manufacturing information extraction and shop-floor-level process planning are addressed in particular, and a prototype for STEP-NC turning process is implemented to demonstrate the feasibility of the approach.

Abstract: In this paper, Data model used in intelligent CNC system based on STEP-NC is presented. A multi-agent architecture of the intelligent CNC system based on STEP-NC is proposed. The architecture consists of fourteen functional agents, such as interpreter agent, process planning agent, simulation agent, tool path planning agent, monitoring agent, expert system agent, etc. Some key technologies to implement the intelligent control including simulation, online inspection and expert system are discussed detailed. As a result, the architecture and key technologies proposed in this paper will aid the development work of the intelligent STEP-NC system.