Laser Assisted Forming for Ship Building

Laser forming has become a viable process for the shaping of metallic components, as a means of rapid prototyping and of adjusting and aligning. The process is similar to the well established torch flame bending used on large sheet material in the ship building industry but a great deal more control of the final product can be achieved. This paper outlines the process and mechanisms of laser forming and reviews the potential of the process for the ship building industry. Also outlined are experimental results of high powered 2D and 3D laser forming of thick section material, the results demonstrating the potential of the process for shipbuilding in terms of accurate net shape manufacture and the secondary distortion correction process. 1.0 Introduction The laser forming process (LF) has become viable for the shaping of metallic components, and as a means of rapid prototyping and of adjusting and aligning. Laser forming is of significant value to industries that previously relied on expensive stamping dies and presses for prototype evaluations. Relevant industry sectors include aerospace, automotive, shipbuilding and microelectronics. In contrast with conventional forming techniques, this method requires no mechanical contact and thus promotes the idea of "Virtual Tooling." It also offers many of the advantages of process flexibility associated with other laser manufacturing techniques, such as laser cutting and marking [1, 2, 3]. Laser forming can produce metallic, predetermined shapes with minimal unwanted distortion, investigations are also ongoing in the removal of unwanted distortion. The process has its origins in flame bending for ship construction, with the earliest work on LF beginning in the mid-1980s [4, 5]. The process has similarities to this well-established torch flame bending used on large sheet material in the shipbuilding industry [6, 7, 8 ,9], but a great deal more control of the final product can be achieved. The process employs a defocused laser beam to induce thermal stresses in the surface of a workpiece in order to produce controlled distortion, the exact mechanisms of the process are outlined in a later section. It can be argued that the use of a defocused laser to form could be replicated by cheaper more cost-effective means, e.g. a plasma torch [10], however it could also be argued that laser forming would be a secondary process when considering the costeffectiveness of a laser system, in that a system would be purchased for primarily a cutting or welding operation, proven to be cost effective and competitive, and used for laser forming as a bonus additional process. The specific advantages and capabilities of laser forming are outlined below.