No abstract

STEP-NC is a new CNC data interface proposed to replace ISO 6983, and has been partly formed into the draft international standard (ISO 14649). In this paper, the STEP-NC-based part program is analyzed, and the general methodology and tools for STEP-compliant application development are introduced. Then a framework for STEP-NC interpreter is proposed based on the SDAI method and the implementation solutions are presented. The EXPRESS compiler is used to convert the milling schema into C++ classes, and the information is extracted from the file in aid of data access tools. The said interpreter, which is fundamental to STEP-NC based machining, is also implemented with supporting tools in the ST-Developer environments. It is used to read the STEP-NC file into ROSE working form, and then extract and organize the manufacturing information in an object-oriented way.

MTConnect is a technical standard recently proposed to facilitate the organized retrieval of process information mainly from numerically controlled machine tools. In this paper, core components such as agent, client, adapter etc are overviewed. Considering the difference in manufacturing devices openness and capabilities, different application schemes of agent and adapter are designed according to MTConnect protocol. Agent is designed for data acquisition in different situations and different ways to use Adapters are mainly discussed. Finally, the client, a software function in the application is developed by using C#. And the application is applied to a NC machine tool. In terms of data request, collecting, transmission and detection from a working NC machine tool, the proposed architecture in this paper is verified successfully.

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.

To comply with STEP-NC (ISO 14649), a new paradigm for NC programming, many computer systems involved in NC manufacture are required to reshape in both functionality and structure. This paper reports a feature-based NC programming system for prismatic parts to be machined using STEP-NC machine tools. The proposed system consists of three functional modules, i.e. a feature-based modeler, a process planner and a part program generator. The modeler provides a graphical environment for the part model, which is created by adding manufacturing features on a 2.5 D sweep primitive shape. The process planner determines which operations are to be performed for the features, generates workingsteps and then produces a reasonable workplan. Finally both the geometrical and the process information are passed to the part program generator to form a complete ISO 14649-compliant file. The proposed system is demonstrated through the generation of the STEP-NC part program for an example part, and major issues such as the feature-operation mapping and the workingstep sequencing etc are also addressed in this paper.