LASER MICRO-PERFORATION 'ON-THE-FLY' AS AN ESSENTIAL STEP OF A NOVEL PROCESS COMBINATION FOR MICRO-SIEVE PRODUCTION

摘要

A novel two-step technique, capable of performing large bore matrices in thin stainless steel foils is maintaining high processing rates and bore widths < 5 μm. This process combination is initiated by high-speed single-pulse perforation "on-the-fly" with use of a fiber laser. This laser source combines ample output power with an excellent beam quality. The high drilling rate (> 10 000 bores/second) which can be achieved by use of this technique makes it an attractive option for the creation of large bore matrices and widths of less than 20 μm (fig.1). The second step consists of cold-roll forming of the previously laser micro-perforated foil. This mechanically induced plastic deformation leads to a bore size reduction perpendicular to the rolling direction with a minimum bore width of < 5 μm. Laser single-pulse perforation "on-the-fly" mainly determines the overall processing rate of the above described process combination, for that reason a novel high-speed laser-machining centre is being developed. A 300 Watt fiber laser source with excellent beam quality is integrated together with highly dynamical linear axes featuring a maximum feed rate of 2 m/s and acceleration of > 2 g. The experimental work is accompanied by theoretical analysis of the maximum obtainable drilling rate and thermal efficiency.