Automated thermal forming of curved plates in shipbuilding: system development and validation

Abstract

This article presents an automated thermal forming system for use in the ship fabrication process. The system consists of scanning devices for measurement of plates, heating devices for plate forming, a computational unit for heating information and a gantry robot with six axes, which moves the scanning and heating devices. Two levels of measurement, pre-scanning and post-scanning, are introduced. A pre-scanning system using a multi-LVS (laser vision sensor) is installed on the gantry for detecting the position of the plate in the working area. Once the position is determined, a post-scanning device with a Local-LVS, installed at the robot arm, is employed to measure the plate accurately. A high-frequency induction heater is installed at the robot arm as a heating device. The computational unit computes heating information including heating locations and speed. The robot controls the position and orientation of the heater and the measurement devices to heat a plate following the computed heating information and to measure the shape of the plate accurately. The system was thoroughly evaluated with diverse test plates, and has been used in the actual fabrication process at a shipyard.