Buckling based laser forming process: Concave or convex

Abstract

Concave laser forming can be readily achieved, while convex forming may occur through buckling but the buckling direction heavily depends on the sheet surface and pre-strain condition. A new laser-scanning scheme is postulated, by which convex forming can be effected insensitive to the above mentioned initial conditions. The postulate is successfully validated by experimental and numerical results. The eifect-ef the scanning parameters on the certainty of the convex forming are further investigated experimentally and numerically. The simulation results are in agreement with experimental observations. The numerical simulation model developed is also used to study the transient temperature, stress, and strain-state and provide further insight to the convex forming process.

Making Light Work of Metal Bending: Laser Forming in Rapid Prototyping

“…Beyond predicting the bending direction, researchers have also developed ways to control the buckling direction. Such methods include pre-bending the metal sheet [52,59], or through judicious choice of the lasing parameters [60,61]. The ability to generate bidirectional bending expands the design space for laser forming [62,63], without the need for human input, i.e., flipping the work piece [50].…”

“…The early reports focused on using high power (>1 kW) lasers [40,60,61,70,71,[98][99][100][101][102][103], as the intent was to bend large sheets as part of the ship building process [35]. The laser forming of thinner substrates enables the use of lower power (<100 W) lasers, such as those found in commercial metal marking laser systems [57,63,67,76,85,88,93,104].…”

“…This instability is theoretically random but can be controlled by multiple factors, such as external loads [57,104], or the relaxation of internal stresses that exist because of the cold-working of common metal sheets [57]. The main reason to use the buckling mechanism is the downward bending, which greatly broadens the number of structures that can be laser formed [59,61].…”

Effect of Pre-Stress on Laser-Induced Thermoplastic Deformation of Inconel 718 Beams

“…Such a bending deformation is termed concave [16] or positive [15] in the literature. The opposite deformation is termed as convex [17] or negative [15]. Influence of external mechanical load on the effect of laser bending was investigated by Vollertsen and Rödle [18] under conditions of TGM.…”