JPS59104289A - Method and device for cutting steel plate by laser beam - Google Patents

Abstract

PURPOSE:To obtain a clean cut surface having no oxide, etc. sticking thereon in the stage of cutting a metal by using a laser beam and assist gas by preheating the cutting part to a high temp. and injecting inert gas to the front and rear surfaces of the cut part. CONSTITUTION:A laser beam 1 is condensed by a condenser lens 3 in a cutting head 2, and while gaseous oxygen is blown from an assist gas feed port 5, a work 7 is cut. The work prior to welding is preliminarily heated to a high temp. by an arc, gas burner, high frequency heating, etc.; at the same time the molten oxide remaining in the cut part is blown off from said part to the rear surface by the inert gas injected from the top surface to the cut part by the 1st auxiliary nozzle 10 and the inert gas injected to the rear surface from the 2nd auxiliary nozzle 20. The blown oxide is scattered by the gas injected from the nozzle 20. The object is thus cut to have the clean cut surface having no oxide sticking on the cut surface and rear surface in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for cutting an object using a laser beam and an assist gas.

Generally, when cutting, for example, a copper plate using a laser beam, the laser beam l is directed through a lens 3, as shown in FIG.
At the same time, the light is focused and irradiated onto the workpiece 7 (object).
Oxygen gas (first gas) is blown onto the workpiece 7 from a nozzle 4 coaxial with the laser beam 1, and the workpiece is fused and cut by utilizing the oxidation heat generation effect. This type of laser cutting method is non-contact processing, and the cutting direction is free.
It has many advantages such as narrow cutting width and less heat effect on the workpiece.

However, this method also has the following disadvantages.

That is, the molten oxide 9 generated during the cutting process descends along the cut surface 8 and hangs down on the lower surface of the cut portion 8 of the workpiece 7, as shown in FIGS. 2(a) and 2(d). Second
As shown in FIGS. (b) and (e), after the cut, the lower part of the cut may become blocked again by the molten oxide 9.

When such a phenomenon occurs, cutting accuracy may be reduced, and additional manufacturing steps such as grinding after cutting are required, resulting in increased costs.

Figure 4 shows the cross-sectional shape of the cut surface when 100% oxygen gas is injected from the cutting nozzle when the workpiece is in a high temperature state. The figure in the center shows the case when the temperature is room temperature, the figure in the middle shows the case when the temperature is 400°C, and the figure on the far right shows the case when the temperature is 800°C. 7' in Figure 4
is the test piece. As is clear from these figures, 40
As the temperature of the workpiece increases from 0°C to 800°C, the oxidative exothermic reaction due to oxygen gas from the nozzle increases, and the cutting speed becomes faster, but the cutting width becomes wider and the cut surface becomes less uniform. The generation of molten oxides also increases.

An object of the present invention is to provide a method for cutting an object using a laser beam that can cut with high precision and does not require post-processes such as grinding after cutting. By raising the temperature of the cutting part, the oxygen mixing ratio of the gas injected from the nozzle is lowered, reducing the oxidative exothermic reaction caused by oxygen scum, suppressing the generation of molten oxide, and making the cutting width narrower and the cut surface smaller. It is designed to perform uniform cutting.

In addition, by preheating, the wavelength absorption of the laser beam on the rust plate surface is increased, making it possible to generate keyholes (holes created by evaporation of the workpiece) using the laser with less energy. This is what I did. In addition, inert gas is injected into the vicinity of the cut portion from the front and back sides, respectively, to prevent the generated molten oxide from adhering to the cut portion.

The present invention will be explained below with reference to the drawings.

FIG. 3 is an explanatory diagram showing a longitudinal cross section of a cutting head and a workpiece according to the present invention. Reference numeral 1 denotes a laser beam, which is incident on the cutting head 2 from above.

Inside the cutting head 2, there is a condensing lens 3. An assist gas inlet 6 and the like are provided. The laser beam 1 passes through the interior of the cutting head 2, is focused by a condensing lens 3, and is irradiated onto the workpiece 7. Oxygen gas etc. from the gas inlet 6 to the assist 1 passes through the inside of the cutting head 2, passes through the cutting nozzle 4 provided at the bottom of the cutting head 2 and the main nozzle hole 5 at the tip of the cutting nozzle 4, and passes through the workpiece 7. is sprayed onto the same area as the laser beam irradiation position. This position is the cutting position.

Reference numeral 10 denotes a first sub-nozzle, and a first sub-nozzle hole 11 is formed at the tip (lower side) of the first sub-nozzle. The angle θl is made with respect to the surface. Further, 20 is a second sub-nozzle, which has an angle of θ2 with respect to the back surface of the workpiece 7 in order to inject gas onto the back surface of the workpiece 7. The gas is sprayed a distance L2 behind the position. Furthermore, this second sub-nozzle 20 may be made to have an angle with respect to the cutting line). 214 is the second item with one nozzle hole.

Further, in the explanatory diagram of the present invention shown in FIG. 5, numeral 30 is a preheating source that preheats 23 points in front of the laser beam irradiation point PO by R large nIL3. Also, in the case of the figure, T I
G +-- indicates H. 31 is an arc.

Note that this preheating source is, for example, a TIG arc or arc.

Gas burner, direct energization, high frequency heating, laser beam, etc.
Any heat source can be used.

In order to cut the workpiece (hereinafter referred to as chain plate V) 7 according to the present invention, as shown in FIG. Thus, 23 points in front of the cutting nozzle 4 are preheated. After that, when the copper plate 7 is moved and the preheating point reaches the mover of the cutting nozzle 4, the laser beam 1 and the center gas G1 are emitted from the main nozzle hole 5 of the cutting nozzle 4, and as a result, the chain plate 7 disconnected.

As the steel plate moves, this operation is repeated in two consecutive rows, so long steel plates can be cut. At this time, if the composition of the center gas G1 is a synthetic gas of oxygen and an inert gas such as nitrogen, the cutting efficiency will not be reduced, and there will be less generation of molten oxide due to the oxidative exothermic effect of oxygen, resulting in efficient cutting. can be done.

Further, in the present invention, during the above-mentioned cutting, an inert gas G2 is applied to the non-coagulating area near the cutting part from the sub nozzle. Injecting G3 is even more effective.

That is, as shown in FIG.
A second sub-nozzle 20 is provided below the first sub-nozzle.
The inert gas G2 injected from the sub nozzle 10 is as shown in Fig. 5P.
The inert gas G3 injected from the second sub-nozzle 20 is planted so as to be sprayed at the same point P2.

Therefore, the inert gas G2 from the first sub-nozzle 10 is directed into the cutting groove of the steel plate 7 which has been preheated by the preheating source 30 and further cut by the laser beam 1, and as a result, the inert gas G2 existing in the groove before solidification is Molten oxide is removed out of the groove.

On the other hand, the inert gas G3 injected from the second sub nozzle 20
is written at point P2 on the back side of chain plate 7, so the first
The molten oxide discharged to the outside of the cutting groove by the gas G2 from the sub nozzle 10 is scattered by the inert gas G3,
Does not adhere to the back side of the steel plate. Therefore, the cut portion becomes as shown in FIGS. 2(c) and 2(f), and maintenance such as grinding is therefore unnecessary.

Here, conditions suitable for carrying out the present invention are as follows.

Sample: Electromagnetic chain plate (813%), thickness 2mm; TI
Distance between G arc and laser irradiation position (L3): 10-2
0mmTIG7-'/: IOV, 100-300A laser output 2 Kw, 50-150mm/S Mixed gas component ratio of gas from cutting nozzle: Oxygen gas 60-8
0%.

Nitrogen gas 20-40% Angle of first sub-nozzle ((it): 30-60' Gas flow rate (Ql) from first sub-nozzle: 60-120 Q/min 1st
The gas spray of the sub nozzle is at the position (ff[?4] from the cutting point)
Li, 2~7 +nm Angle of second sub-nozzle (G2
): 5~20' Gas flow rate from the second sub-nozzle (G2)
: 80 to 14007 minutes The gas blowing from the second sub-nozzle is from the position F4.
L2: 3-10 mm The above conditions are fully applicable even when the workpiece is other than an electromagnetic saw plate.

Next, examples of the present invention will be shown.

Example 1. Output as a laser beam source 2. A 3% Si layer with a thickness of 2.0 mm was cut at a speed of 80 mm/sec using an OKw CO2 laser device. A TIG arc was used as a preliminary heating source, the IOV was set at 150 A, and a mixed gas of 70% oxygen gas and 30% nitrogen gas was injected from the main nozzle 4. As a result, it was possible to cut the cut surface sharply.

On the other hand, when other conditions were the same without preheating, cutting was not possible.

In addition, when 100% oxygen gas was injected from the main nozzle, cutting was possible, but there was more molten oxide than in the case of preheating with a TIG arc, and the cut surface was not sharp and required cleaning as a post-process.

Output 2. As a laser beam source that penetrates through the gap. Using OKw's CO2 laser device, a 2.5 mm thick plate containing 3.0% Si was heated to 80 mm.
Cutting was performed at a speed of m+n/sec. TIG as a preliminary heating source
Using a 7-meter, set it to 10V and 150A, and inject a mixed gas of 70% oxygen gas and 30% nitrogen gas from the main nozzle.
Nitrogen gas was injected from the first sub-nozzle at a flow rate of 80 Q/min, and nitrogen gas was injected from the second sub-nozzle at a flow rate of 120 Q/min. At this time, the inclination G1 of the first sub-nozzle is set to 4.
5°, the inclination 02 of the second sub-nozzle is 10'', the distance L1 between the cutting position P and the gas injection position P1 from the first sub-nozzle is 5 mm, and the gas injection from the position P1 and the second sub-nozzle is The distance L2 from the position P2 was adjusted to 3+nm. Also, the distance L3 between the cutting position P and the tip position (preheating position [) P3] of the preheating TIG arc was 10 mm.
The hole diameter of the sub-nozzle hole 11 was set to 2 mm, and the hole diameter of the second sub-nozzle hole 21 was set to 3III11.

As a result, the cut surface was not blocked by molten oxide, and the steel plate could be completely cut. Furthermore, the cut surface was sharper than when 100% oxygen gas was injected from the main nozzle. In addition, when cutting was performed under the same conditions as above with the supply of nitrogen gas from the first sub-nozzle and the second sub-nozzle stopped, molten oxide adhered to the cut surface, although it was less than when using 100% oxygen gas. It was seen.

Further, when only the supply of nitrogen gas from the second sub-nozzle was stopped, the cut surface was not blocked, but molten oxide was observed to adhere to the cut surface and the lower edge of the cut portion.

In addition, in the above explanation, an example was explained in which a TIG arc was used as a preheating source, but as explained earlier, as a preheating source, other preheating sources as well as a TIG arc,
For example, arc, gas burner, direct energization, high frequency heating,
Any heat source may be used, such as a laser beam.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of a device conventionally used to cut objects with a laser beam, and Figures 2 (a) and (d) are front views of the workpiece cut by the conventional method. 2(b) and (f) are a front view and a side view of the cutting section showing a workpiece cut according to the present invention, and FIG. 3 is a cutting head for implementing the present invention. FIG. 3 is a vertical cross-sectional view showing a sub nozzle, and a workpiece. FIG. 4 is a diagram showing the state of cutting when the steel plate is in a high temperature state. FIG. 5 is an explanatory diagram showing the configuration of the present invention. 1: Laser beam 2: Cutting head 3: Condensing lens 4: Cutting nozzle 5: Main nozzle hole 6: Assist gas supply lower: Workpiece 7': Test piece
8: Cut surface 9: Molten oxide 10: First sub nozzle 11: First sub nozzle hole 20: Second sub nozzle 21: Second sub nozzle hole 30: Preliminary heating source G1: Main nozzle gas G2: First sub nozzle gas G3: Second sub-nozzle gas Po: Laser beam irradiation position Pl: First sub-nozzle gas injection position P2: Second sub-nozzle gas injection position P3: Preheating position Ll: Distance between Po and P10 L2: Distance between pl and P2 L3: Po and P3 interval No. 3 Figure 1 Figure 2 Procedural amendment (method) April 4, 1980 Director General of the Patent Office Mr. Wainu Wakasugi■, Indication of the case Patent Application No. 213211 of 1988
, Title of the invention Method and apparatus for cutting steel plates using a laser beam 3, Relationship with the amended case Patent applicant address No. 3, 2-6 Otemachi, Chiyoda-ku, Tokyo Name (665) Representative of Nippon Steel Corporation Takeshi 1
) Yutaka 4, Agent 103 Phone: 03-864-60
52 Address: 2-27-6 Higashi Nihonbashi, Chuo-ku, Tokyo March 9, 1982 (Shipping date: March 29, 1982) 6.
Month of amendment Sξ Name of the invention in the specification 7, Contents of amendment

Claims (4)

[Claims] (1) In a method of cutting a steel plate by irradiating the steel plate with a laser beam and injecting a first gas in substantially the same direction as the laser beam, the cutting part is preheated by another heat source, and then the laser A method for cutting a steel plate using a laser beam, characterized by irradiating a beam. (2) A steel plate is cut by a laser beam according to claim (1), in which a second gas is injected onto the surface of the steel plate and a third gas is injected onto the back surface at an angle different from that of the laser beam in the vicinity of the cutting position. Cutting method. (3) A cutting nozzle that emits a laser beam and a first gas is provided opposite to the steel plate to be cut, and a preheating device is further provided on the cutting line in front of the cutting nozzle. Cutting device. (4) A sub-nozzle for injecting a second gas near the cutting part is arranged at an angle with respect to the cutting nozzle, and a sub-nozzle for injecting a third gas near the cutting part on the back side of the steel plate is arranged at an angle to the cutting nozzle. A steel plate cutting device using a laser beam as set forth in claim (3) provided below.