New nozzle concept for cutting with high power lasers

Abstract

In the last few years cutting by lasers up to 5 kW has been well accepted in industry. The next generation of industrial lasers is offering higher output powers. These systems require, however, a cutting head without transmitting optics. In this paper, a new nozzle concept for cutting gas is presented where no transmitting optics are necessary. High efficiency is ensured due to the application of two-dimensional Laval nozzles producing a homogeneous gas flow. Both, larger values and larger variations of the distance between nozzle and workpiece are allowed without having such dramatic losses in stagnation pressure when using “standard” nozzles. The experiments presented were performed with a 1 and a 5 kW CO2 laser system on various metals (ferrous and nonferrous). Conical-cylindrical nozzles were compared with the new nozzle concept. Investigations of the gas flow of the nozzles show the necessity of well-conceived nozzle design. Cutting efficiency of the different nozzles is given as a function of cutting pressure. The reliability of the new nozzle has been successfully proved even in combination with an arm robot system.