DK149266B - CUTTING HEAD FOR WORKING WITH A LASER RADIATION - Google Patents

Description

i 149266 o

The invention relates to a cutting head for machining, such as cutting a material by means of a laser beam supplied to a pressure chamber having an inlet opening for supply of pressure gas and an outlet nozzle for the laser beam and the pressure gas, which pressure gas is further supplied to the back of the radiation focusing element (s).

In a cutting head known from UK patent application no.

2,064,399 pressurized gas is supplied to a chamber delimited by a focusing lens and a nozzle, thereby providing a gas blowout at the cutting site, thereby improving the quality of the cutting. However, the lens limits how large the pressure in the chamber can be.

15

Pra US Patent No. 3,696,230 is known to supply compressed gas to both the front and back of the lenses in order to keep them clean.

According to the invention, a supply of pressurized gas of a higher pressure to both the front and the back of the radiation focusing element (s) in the pressure chamber is made possible by this chamber having a small light input opening, in which the externally supplied laser beam is focused, and at that the radiation focusing element (s) is located within the compressed air access chamber for both the front and rear.

To avoid any reflections returning to the laser beam, the light input port may advantageously be small relative to the exit nozzle opening. Thereby, the laser beam source does not "see" the subject.

The invention will be explained in more detail below with reference to the drawing, in which 1 shows a cutting head according to the invention containing a lens nozzle system; and FIG. 2 shows a cutting head containing a nozzle system with reflective focusing elements.

149266 2

The FIG. 1, for cutting a material, comprises a lens 2 for focusing a laser beam 1, which is thereby concentrated in a focal point. At this focal point, the laser beam passes a light input port 3 to a pressure chamber 4. Thereafter, the laser beam 1 is expanded again until it hits a lens system 5, consisting of one or more lenses. This optical system focuses the laser beam 1 in a new focal point 10 immediately outside the pressure chamber 4, the laser beam 1 passing out through a discharge nozzle 6. Pressure chamber 4 is simultaneously supplied to the pressure chamber 4, e.g. oxygen, argon or ordinary atmospheric air via an inlet port 7. Immediately below the outlet nozzle 6, the focused laser beam 15 in connection with a gas blowout from the chamber 4 can be used for machining, such as cutting in a metal plate, the plate being displaced relative to the outlet nozzle 6 perpendicular to the direction of propagation of the laser beam and gas beam.

The gas supply to both the front and back of the focusing lens system 5 can e.g. This is done via a branch, where there is possibly a control device in at least one of the branch pipes. The pressure in the chamber 4 can e.g. be at 25 atm.

A particular advantage of this very high pressure is that it thereby achieves a better cutting quality than previously known, and at the same time can cut at a greater speed, as the gas exhaust removes any melting drops and metal fumes.

Optionally, there may be some pressure regulation so that there is a smaller pressure difference between the front and back of the lens 5. Optionally, two different gases may be used, e.g. oxygen to the cutting side and atmospheric air to the input side.

35 For large effects, hole mirrors 8, 9 can be used as focusing elements, thereby avoiding loss of power in lenses.

FIG. 2 shows a cutting head containing two hole mirrors with suitable focal lengths. Here, the laser beam 1 is focused by the hole mirror 40 8 through an opening 10 to the pressure chamber and passes into the pressure chamber.

Claims (2)

149266 chamber 4. Here, hole mirror 9 focuses the divergent laser beam, which then passes out of pressure chamber 4 through the outlet nozzle 6. Here too, compressed gas is supplied through a gas supply 7, and also here the focused laser beam and the coaxial gas jet 5 can be used for machining. , such as cutting an item. The opening of the outlet nozzle 6 is preferably substantially greater than the distance to the blank, thereby providing a laminar gas flow in the shear zone, thereby avoiding any refractive effects of any shock waves and turbulent flows. In addition, it has been found that polarization is of great importance (since light refraction depends on polarization). In order to obtain the greatest cutting ability, the laser beam E-vector must be 15 parallel to the sectioning direction. Therefore, to obtain a more uniform cutting, circularly polarized light can advantageously be used. The laser used is typically a C02 laser that times infrared light. The laser power is approx. 200 - 5,000 w (typical). 20 The current cutting speeds in a 2 mm thick steel plate are around 5 m / min, which is apparently only approx. 15% of the theoretical maximum. The joint width can apparently be reduced to approx. 0.1 mm. The cutting head according to the invention makes it possible to cut at a much higher speed than previously known. In order to avoid any reflections from the workpiece working back on the laser beam source, it is possible to reduce the light transmission opening to the chamber less than the nozzle opening. However, other measures may also be needed. Claims. 35 --------------------- 1. Cutting head for machining, such as cutting a material