Dust protection for working laser unit, induces longitudinal gas flow towards workpiece and exerts ambient pressure in working region

摘要

Ambient pressure is exerted in the working region (S'). A longitudinal gas flow towards the working region, is induced in a region (R1) located between the working region and the laser unit. An Independent claim is included for the corresponding apparatus. A further claim covers the entire laser processing apparatus with dust protection as described, and a workpiece feed system. Preferred features: During gas introduction, gas is removed from the neighborhood of the working region. The longitudinal gas flow is accelerated toward the working region. The region (R1) is located in a channel of a casing between the laser unit and the working region. The channel extends between a beam entrance opening and a beam exit opening of the casing. The process further includes supply of gas to, and its removal from the channel at separate internal locations, the quantity supplied being essentially that removed. The longitudinal gas flow is developed over the full cross section, and is directed towards the beam exit opening. A pressure obstruction is formed in a second region (R2) of the channel, between the first (R1) and the laser unit. Gas is supplied at opposed inlets perpendicular to the longitudinal axis in the first region, to form the longitudinal flow. Opposed inlets cover the entire cross section with flow. A separate peripheral gas flow is produced along the channel in the first region by at least one input. Flow is directed towards the working region. Gas is led off near the beam exit opening, preferably in at least two diametrally opposed directions. Lateral gas flow is produced in a third region (R3) of the channel, between the first region (R1) and the laser unit. The flow is produced between opposite openings in the side wall and covers a full cross section of the channel. Lateral flow takes place essentially perpendicular to the longitudinal central line of the channel. Gas is supplied and led away through opposed openings at essentially the same rates. Pressure is measured in at least one location in the casing and gas removal rate from the casing is controlled from the measurement. Pressure is maintained at ! 1 kPa relative to ambient, in the working region. The channel is non-circular in the first region. It is rectangular, especially square with openings in the corners. The channel constricts to cause flow acceleration.