Eccentric machining of a crankshaft using feature-based simultaneous four-axis machining using STEP-NC

Currently, many CNC(Computerized Numerical Control) machine tools are controlled by ISO 6983, also known as G-code. This code only contains tool path information and is not easy to modify because the machining details are not read from the data. Therefore, STEP-NC (STandard for the Exchange of Product model data- Numerical Control), specified in ISO 14649, has been newly standardized internationally. STEP-NC contains machining information and can solve the G-code problem. However, it cannot represent the machining information of eccentric crankshafts due to the insufficient description of features and motions for multi-axis machining. This research proposes a new feature model for representing eccentric shapes in STEP-NC and new 4-axis machining strategies, which are the feature information of tool motion. A method for deriving NC data for eccentric machining of a 4-axis machine tool from the proposed STEP-NC data is also proposed. Using the created STEP-NC data, we demonstrate eccentric crankshaft machining that requires simultaneous 4-axis machining.