We have developed a new method of laser welding to produce honeycomb structures consisting of flat and corrugated metal sheets as shown in Fig.1. The experiments have been conducted using pulsed mode Nd-YAG lasers and CO2 lasers. Specimens are stainless steel sheets, high-alloy corrosion resistant steel sheets or the like, whose thicknesses are from about 50μ m to 1mm. In this method, a laser beam of low energy density, with high reflectance from steel surfaces, is irradiated into the wedge shape space which is formed from both the flat and corrugated metal sheets, and is automatically focused at the top of the wedge shape space by means of multiple reflection effects. Most of the energy of the laser beam can be converted to heat and used to weld the opposed walls of the wedge shape. This laser welding method increases the welding efficiency and improves the quality of the weld joints of the honeycomb panels which could be used for aircraft, super express trains and for the exhaust systems of the internal combustion engines of automobiles.
Usually honeycomb panels are produced by brazing or electro-resistance spot welding. However, those processes are complicated and expensive, and the productivity is very low. Using the multiply reflected laser beam welding method, it is possible to realize an effective manufacturing process for these all-welded high performance metal honeycomb panels.