Session: Research Posters

Paper Number: 119268

119268 - Carbon Fiber-Reinforced Plastics Machining Using the Industrial Robots 

Carbon fiber-reinforced plastics (CFRPs) find many applications given their superior properties. These materials are usually formed using a near-net-shape method that requires secondary machining, such as drilling and trimming, after molding. Industrial robots are becoming increasingly popular machining tools in industries exhibiting high demand for CFRPs. However, it remains challenging to achieve high dimensional accuracy when using such robots and dynamic performance is poor. We experimentally investigated the dynamic properties of the tool tip according to the dominant robot posture during CFRP secondary machining. Based on the results, multi-layer perceptron models were developed to predict the dominant natural frequency and dynamic stiffness of the tool tip. Experimental investigations have been done considering the dynamic properties of tool tip in dominant mode for CFRP secondary machining processes with an industrial robot. Based on these results, the dominant natural frequency and dynamic stiffness of tool tip according to the robot posture were predicted utilizing MLP models. It indicated that the models can facilitate the improvement of machinability in CFRP robotic machining such as drilling and trimming processes by optimizing the dynamic performance of tool tip. The dynamic properties of tool tip are changed nonlinearly according to the robot configuration of each joints angles. Therefore, the dynamic properties of tool tips that change according to the robot posture were analyzed through the impact hammer test, and the performance of CFRP secondary machining processes was investigated based on the analysis results. As a result, it was confirmed that the dynamic stiffness of each axis of the toll tip affects the machining results such as hole defects in the drilling process and surface quality in the trimming process. In CFRP robotic drilling process, it was confirmed that the quality of the drilled hole in CFRP can be improved by increasing the Z-direction dynamic stiffness of tool tip. There is a redundant degree of freedom in serial robot, so the robot posture can be optimized using the redundancy. In the case of this paper, the robot posture can be changed controlling the angle of Rz in fixed the TCP of tool tip. Adjusting the Rz angle changes the angle of each joint, and the robot configuration changes accordingly to optimize the dynamic stiffness of the tool tip. It was confirmed that defects in the CFRP drilled hole decreased when drilling was performed in a robot posture with high stiffness while the direction of the axis (Z-axis of the tool) to proceed was fixed.

Presenting Author: Hyung Wook Park Ulsan National Institute of Science and Technology

Presenting Author Biography: Hyung Wook Park is a Professor of Mechanical Engineering at Ulsan National Institute of Science and Technology, South Korea. He received his B.S. and M.S. from the Seoul National University, Korea, and Ph.D. from Georgia Institute of Technology, USA. His research interests include machine tools, metal cuttings as well as non-traditional machining, surface texturing using metal cutting, FEM modelling and robot manufacturing.

Authors:

Hyung Wook Park Ulsan National Institute of Science and Technology