Research On The Technology Of Data Processing And Process Planning Of Turning System Based On STEP-NC

In modern manufacturing, the NC technology is a major contributor to the production capability of enterprises. Along with the enhancement of computer technology, NC technology has undergone a significant development. However, NC machines are still programmed based on the ISO6983, known as G&M codes, which describes the travel path of the cutter. Recent research shows that there are many problems with the interface of ISO6983. With the endless persuit for the quaility and efficiency and the widely usage of CAD/CAM in NC programming and machining area, G&M codes bottleneck the information integration between different systems and the further development of NC technology, even the whole manufacturing industry. Therefore, a new data interface called STEP-NC was proposed by western countries to instead the current interface. Harmonized with ISO10303, STEP-NC extends STEP into NC manufacturing and bridges the gaps between CAD, CAM and CNC. STEP-NC orgnizes the design and manufacturing data in an object-oriented way through a series of features and workingsteps. Therefore, through the information derived from STEP-NC program the CNC controller can be aware of not only "how-to-make" but also "what-to-make". It is very important to realize intelligent CNC systems. STEP-NC will bring profound influence on the NC technology and the e-manufacturing industry.This research, as a part of STEP-NC based intelligent turning system, emphasizes on program parsing, process planning and toolpath planning. It will be helpful to realize the forthcoming intelligent CNC controller.For a STEP-NC based CNC controller, the principal and also the basic function is to parse and translate the NC program. STEP-NC discards the traditional way of programming the cutter path, follows the style of the ISO 10303-21 file, harmonizes the STEP standard. And the STEP-NC program differs a lot from the G&M program. Consequently, in general, a piece of STEP-NC program is very prolix and complex. In this research, a scheme of a simple parser for STEP-NC turning program is proposed. Firstly, map the STEP-NC description language EXPRESS with Java programming language and translate the EXPRESS entities into Java classes. Then, the parser converts the program information into objects of Java classes and saves them in the memories. These objects can be used to distill the needed information. Additionally, a 3D viewer is developed to validate the final part shape. With the experiments of several pieces of STEP-NC program, this method is proved feasible.Besides, process planning and the tool path planning are also the vital tasks of CNC controller. Traditionally, the process planning and the tool path planning belong to CAM system. But STEP-NC breaks the old-fashioned pattern. In this resaerch, working-step is selected as the basic unit of planning. The relationship between working-step, operation and feature is studied firstly. Then, the method and principle of process parameters optimization are given. According to the structure of STEP-NC program, the simple steps of tool path planning are proposed. Finally, using the example program, the tool path planning technique is validated.