Development of An Integrated Framework For Optimization of Sheet Metal Work Through Bi-Directional Information Flow Between Design and Manufacturing Processes.

Abstract

Present day low quantity, high variety, and make-to-order manufacturing scenario demands concurrent product development. Major attributes required for concurrent product development are: seamless and bi-directional data flow among design, manufacturing and quality control cycles. This thesis documents research in to the field of generic feature based design and manufacturing process planning of discrete sheet metal bend parts. In this context sheet metal forming is subjected to various variations, due to which state of the art in sheet metal pressbrake forming is still recognized as a separate and vague island of automation. Formal integration of standards and specifications is required for knowledge retrieval, generated during manufacturing phase. Sheet metal pressbrake forming is subjected to various process and material variations and ultimate shape of a 3D formed part depends upon the capability and health of the equipment of a native manufacturing setup. Process planning and process parameters are optimized by altering some of the design attributes. Valuable knowledge generated during this activity is lost and is not communicated back to the upstream design stage. This research highlights several issues regarding feature based design and manufacturing of discrete sheet metal parts. Contemporary standards STEP (STandard for Exchange of Product data) and STEP-NC ( STandard for Exchange of Product data for Numerical Control ) are utilized to formulate a framework for feature based design and manufacturing of discrete sheet metal parts augmented with the capability of knowledge retrieval. Major contribution of this research is a proposed framework for feature based design and manufacturing of discrete sheet metal parts developed on the basis of STEP and STEP-NC standards. It outputs a generic feature based manufacturing process plan that could be mapped and optimized according to the capabilities of a native manufacturing environment. In the proposed framework STEP enabled manufacturing process plan communicates generic information independent of any vendor specific detailing which is mostly based on rigid data formats such as ISO 6983. Functional requirements of the framework are categorized into three independent modules for the CNC pressbrake process control unit: 3 (1) Feature based design development of discrete sheet metal parts (2) Generic feature based process planning of discrete sheet metal parts (3) Offline process plan optimization according to the capabilities of a native manufacturing environment. The framework was validated through experimentation on a CNC pressbrake with 3-axis back gauge locating capabilities. STEP & STEP-NC compliant framework for feature based design and manufacturing of discrete sheet metal parts provides a powerful tool for generating generic process plans and knowledge retrieval generated during final process plan optimization and execution. Prototype system using ST-Developer® Visual C++ libraries is developed to demonstrate the functionality of the proposed framework.