Process for spooling the conduits and/or the hollow spaces of a laser machining machine

The present invention relates to a method of spuelen the conduit and / or hollow chamber of a laser machine with a suitable gas.

Laser cutting is subsidized by the addition of gas. Oxygen, nitrogen, argon or air is used as the cutting gas. Different gases are used depending on the type of laser machining.

At the time of gas exchange, it is necessary to push out or release the gas used up to that point as completely as possible and replace it with another gas. This is because the residue of the gas used first, that is, the residual gas, may adversely affect the subsequent laser machining.

Japanese Unexamined Patent Publication No. 2001-150172 discloses that the nozzle of a laser processing head is exhausted by a negative pressure before gas exchange. This configuration, however, is complex and expensive and requires additional equipment such as a pump.

It is also known to select a long scavenging time during continuous scavenging until the gas as a foreign substance no longer exists in the process gas. However, the scavenging time in this case is conventionally extremely long. A gas that flows constantly in the individual areas of the gas path between the gas valve and the cutting nozzle produces very little flow, and as a result, it is not possible to quickly and completely repel previously used gas. It is possible. That is, a short scavenging time causes a decrease in process quality, and a long scavenging time causes a decrease in productivity, and gas consumption inconveniently increases the cost.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-150172</text></patcit>

<p> Therefore, an object of the present invention is to improve the quality and the required time in the method of sweeping the pipeline and / or the hollow chamber of the laser machine with a suitable gas.</p>

<p> In this case, in the method of the present invention, in the method of sweeping the conduit and / or the hollow chamber of the laser processing machine with a suitable gas, the gas provided for the sweep is intermittently blown through the conduit and the hollow chamber. It was supplied at a pressure higher than the pressure existing in or one of them, and then expanded after the supply.</p>

<p> The method according to the invention provides similar purity in a significantly shorter time than pure scavenging with a gas used as a second gas. Today's scavenging time can only incompletely repel previously used process gas under unfavorable assumptions.</p><p> In practice, an unfavorably long scavenging time may be required to obtain the required purity. However, conventional purity can be obtained in a shorter time as a whole by the scavenging method according to the present invention. Moreover, the consumption of scavenging gas is reduced by the present invention.</p><p> Intermittent supply of scavenging gas can be made in simple and advantageous technical changes by performing multiple pressure gas impacts back and forth.</p><p> The cleaning effect is first aided by expanding the gas provided to assist the laser machining in the conduit and / or hollow chamber. As a result, atmospheric pressure is usually generated in the pipeline and / or the hollow chamber.</p><p> In order to achieve effective scavenging in conduits and / or hollow chambers with small diameters, it is advantageous to carry out more pressure gas impacts as the diameter of the laser machining nozzle is smaller.</p>

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a laser machining apparatus 1 for laser cutting, which includes a carbon dioxide laser 2, a laser machining head 4 (laser machining nozzle 4a), and a work table 5. The generated laser beam 6 is guided to the laser processing head 4 by using a transforming mirror, and is directed to the work 8 by the mirror.

The laser beam 6 must penetrate the work 8 before a continuous cutting groove is formed. The metal sheet 8 must be melted or oxidized in dots at one location and the melt must be blown out. The incision process can be performed quickly (ie, at full laser power) or slowly (via a so-called "lamp").

In the case of slow cuts with a lamp, the laser power can be gradually increased, reduced and kept constant over a predetermined time until the cut holes are created. Incisions and laser cuts are subsidized by the addition of gas. For example, oxygen, nitrogen, compressed air can be used as the cutting gas and / or the special gas depending on the use provided from the gas container 9, 9'. Which gas is ultimately used is related to what material is cut and what quality is required of the work.

When cutting with oxygen, processing is usually performed at a gas pressure of up to 6 bar. At the point where the laser beam 6 collides with the thin metal plate 8, the material is melted and most of it is oxidized. The generated melt is blown out together with iron oxide. The generated particles and gas can be sucked out from the suction chamber 11 by using the suction device 10 which is a discharge device. During the oxidation process (exothermic reaction), additional energy is generated to accelerate the cutting process. At material thicknesses where the same laser power can be used for oxygen cutting and nitrogen / high pressure cutting, work is performed at significantly higher cutting speeds when using oxygen as the cutting gas than when using nitrogen. It is possible to separate things or large material thicknesses. When gas exchange of cutting gas and / or special gas according to use is conditioned on the process, it is necessary to expel or release the gas used so far and change it to the gas used next. In this case, the gas residue of the gas used initially acts detrimentally to the subsequent laser machining. Therefore the process<u style="single">gas</u>At the time of replacement, it is necessary to exhaust the gas used up to that point as completely as possible.

According to the present invention, it is desirable that the scavenging process be carried out intermittently. First of all, a first short pressure gas impact (Gasdruckstoss) into the pipeline 12, the laser machining head 4 and the other hollow chamber is performed to sweep the conduit 12, the laser machining head 4 and the other hollow chamber. Will be done. In this case, a gas having a higher gas pressure than in the pipeline 12, the laser processing head 4, the other hollow chamber or the surroundings is supplied. The gas then expands in the conduit 12, the laser machining head 4 and other hollow chambers, and expands out of the laser machining head 4. In the pipeline 12, the laser machining head 4, and other hollow chambers, a mixture of residual gas and scavenging is formed under approximately atmospheric pressure. The second and subsequent pressure gas impacts reduce the composition of residual gas in the gas mixture. And again, the gas mixture flows out to atmospheric pressure. After multiple pressure gas impacts and multiple expansions and outflows, there is almost no residual gas or gas as a foreign substance (Fremd gas) in the pipeline 12, the laser machining head 4, and other hollow chambers. And the gas of the first laser machining was almost completely replaced with another gas.

FIG. 2 schematically shows a scavenger 16 for scavenging the pipeline 12, the laser machining head 4, and other hollow chambers. From the gas vessels 9, 9', the conduit 13 extends to the pressure regulating valves 14, 14', and these pressure regulating valves 14, 14'supply gas to the conduit 12, the laser machining head 4, and other hollow chambers. Control. Alternatively, a simple valve connected to the decompressor can be used instead of the pressure regulating valve. The first pressure regulating valve 14 is used to shut off the first used gas from the gas vessel 9 prior to gas exchange. At this time, the gas in the pipeline 12, the laser processing head 4, and other hollow chambers expands to almost the ambient pressure. The gas to be used is then selected via the second pressure regulating valve 14'. The conduit 12, the laser machining head 4, and other hollow chambers, the entire gas path, are filled with the highest possible pressure. The residual gas remaining in the pipeline 12, the laser machining head 4, and other hollow chambers is strongly diluted by this. This filling process typically lasts about 0.5 seconds. The gas is then shut off again, and the gas in the conduit 12 and the laser machining head 4 newly expands to approximately ambient pressure and flows out in the direction of arrow 15. After multiple fillings of the gas path and subsequent expansion, the required purity of the machining gas in the conduit 12, laser machining head 4 and other hollow chambers is obtained and laser machining can continue.

FIG. 3 shows the pressure course generated by the process in the arrangement form shown in FIG. The pressure course shown on the upper side in Fig. 3 is the time point t.₁To gas G₁Corresponds to the first scavenging by. In this case, a total of three pressure gas impacts are performed. Gas G after each pressure gas impact by gas pressure P₁Inflates. The pressure course shown at the bottom in Figure 3 is at time point t.₁Subsequent gas G₂Corresponds to the first scavenging by. In this case as well, a total of three pressure gas impacts are carried out. Gas G after each pressure gas impact by gas pressure P₂Also expands. In order to carry out the present invention, of course, any number of pressure gas impacts are possible. The smaller the diameter of the laser-machined nozzle, the more advantageous it is to increase the number of pressure gas impacts in order to achieve sufficient scavenging.

<figref num="1">It is a figure which shows the laser processing apparatus for laser cutting.</figref><figref num="2">It is a figure which shows the apparatus which sweeps the laser processing head and the gas supply path of a laser processing apparatus with at least one gas.</figref><figref num="3">It is a diagram which shows the pressure progress at the time of scavenging by the apparatus shown in FIG.</figref>

Code description

1 laser processing device, 2 laser, 4 laser processing head, 4a nozzle, 5 work support, 6 laser beam, 8 work, 9 gas container, 9'gas container, 10 suction device, 11 suction chamber, 12 pipelines, 13 tubes Road, 14 pressure regulating valve, 14'pressure regulating valve, 15 flow direction, 15'flow direction, 16 scavenger