JPH02247097A - Laser beam cutting method and device for stainless steel plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method and apparatus for laser cutting a stainless steel plate.

(Prior Art) Various proposals have been made to reduce the amount of dross that adheres to the back surface of a metal plate cut with a laser beam.

For example, attempts have been made to blow gas from the side onto the back side of the cut part to blow off the dross that comes out on the back side (Nikkei Mechanical, July 2, 1984 issue, p.

118) There is also a dust collector as shown in Figure 6 that collects this blown dross. That is, this dust collection device 1 has an air outlet that partitions the inside of the dust collection box 2 into left and right sides on the inside right side of the dust collection box 2, which has a connection port 2a for an exhaust duct connected to an exhaust device (not shown) on the right side wall. A filter 2b is provided in a removable manner, and a suction duct 3 is placed on the top surface of the dust collection box 2. A cylindrical exhaust passage 3a is provided inside the suction duct 3 and extends vertically through the suction duct 3. A suction port 3b is formed at the upper end of the upper trapezoidal part of the exhaust passage 3a, and a V-shaped outlet hole 3c is provided on the left and right sides of the outer side of this suction port 3b, and the lower end of the outlet hole 3c is in communication. It further communicates with the compressed air connection plug 3d on the lower right side.

This dust collector 1 is provided below a cutout hole (not shown) of a table (not shown) on which a workpiece 5 is placed, and the dross attached to the lower surface of the cut workpiece 5 is removed from the blowout hole 3c.
The dust is dropped into the dust collection box 2 below by compressed air blown from the air.

However, with this method, although the dross attached to the lower surface of the workpiece 5 can be reduced to some extent, the dross moves in the direction of cutting progress and remains. This is thought to be because the compressed air blown from both sides collides and is decelerated at the lower surface of the cut section.

Therefore, in order to further reduce dross, there are methods as shown in Figures 5 and 6 (Proceedings of the Academic Lectures of the 1985 Autumn Conference of the Japan Society for Design, P. 685 and Proceedings of the same 1985, P. 6).
61).

This is done by blowing nitrogen gas onto the workpiece 5 as shown in Figure 5, then irradiating it with a laser beam 4, and then blowing compressed air 7 from the side and lower side of the workpiece 5 as shown in Figure 6. β1. By spraying at an angle of β2 (all within 30 degrees), the dross 5a adheres only to the left side, leaving the right side free of dross.

(Problem to be Solved by the Invention) However, although this method can be applied when cutting the workpiece 5 in a substantially straight line, it becomes impossible to follow the direction of the compressed air nozzle when the workpiece has a cut portion with a steep curvature.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a laser cutting method and apparatus for a stainless steel plate that can reliably cut a stainless steel plate without dross without forming an oxide film.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a laser cutting method in which a stainless steel plate is cut by irradiating laser light without supplying an inert gas to one side of the cutting part. At least 0.9Kg inside the provided suction pipe
By setting the pressure below f/ffl and sucking out the inert gas flowing from the cutting part to the other side, by using high-speed axial flow carbon dioxide gas as the laser beam and continuous wave output light from the laser device,
A method and apparatus for laser cutting a stainless steel plate that can cut a stainless steel plate without dross and with a fine surface roughness.

(Example) Hereinafter, an example of the method for laser cutting a stainless steel plate and the apparatus thereof according to the present invention will be described with reference to the drawings.

In FIG. 1, on the table (not shown) there is a thickness of 3.
A workpiece 5 made of a stainless steel plate with a diameter of
A letter-shaped suction pipe 11 is provided, and the upper end of a suction pipe 12 consisting of an outer cylinder 12a and an inner cylinder 12b is screwed into the lower end of this suction pipe 11. The outer cylinder 12a has an upper outer cylinder 12a and a lower outer cylinder 1.
2a2, a pipe 12c for supplying compressed air 7 is connected to the left side of the upper outer cylinder 12a1 via a joint, and a flange at the upper end of the lower outer cylinder 12a2 is connected to a dust collection box installed below. It is fixed at the top of 2.

In the laser cutting device configured as described above, when cutting the workpiece 5 on the table (not shown) with the laser beam 4, first open the valve (not shown) provided in the pipe 12c to direct the compressed air 7 into the suction pipe 12. At the same time, compressed nitrogen gas 6 is also sent into the laser nozzle, and the workpiece 5 is irradiated with laser light 4 to be cut. At this time, the nitrogen gas 6 is sucked by the compressed air jetting downward from the lower end of the outer cylinder 12a, and passes through the cut portion at high speed as a laminar flow as shown by the arrow 6a.
.

It is discharged downward as shown in 6b.

FIG. 6 is a diagram showing an example of the cutting result, and FIG. 3 is a comparative example of FIG. 1, showing the cutting result when the compressed air 7 of FIG. 1 is not supplied.

The cutting conditions are as follows: Laser light: 1.2 KIil high-speed axial carbon dioxide laser continuous wave, single mode (TEMOO) Cutting speed: 1
．． 6m/min Work material: Stainless steel plate (SUS304CP), 3
．． Focal length of 0m thick condensing lens: 12.7mm (focal point is at the bottom of the plate) Nozzle outlet diameter: 2mm Gap between the bottom of the nozzle and the workpiece = 1mm Inner diameter of the top end of the suction pipe: 130mm Gap between the top end of the suction pipe and the workpiece: Approx. At a supply pressure of 0.5+n+n nitrogen gas of 6 Kgf/af and a supply pressure of compressed air of 4 Kgf/d, the pressure on the lower surface of the workpiece inside the suction pipe 11 at this time was measured to be 0.9 Kgf/cJ.

In Figure 2, (a) is a photograph showing the cut workpiece, (b) is an enlarged photograph of the cut surface, and (C) is a stylus-type surface roughness measurement of the surface roughness of the central part of the cut surface in the thickness direction. This is the result measured with a device. As shown in Figure 2, stainless steel plate workpieces cut using this cutting method and its equipment not only have no dross on the back side, but also have no oxide film on the cut surface as shown in Figure (b). The cut surface was glossy as shown in (a) of the same figure, and had a fine surface roughness as shown in (C) of the same figure.

On the other hand, in the comparative example shown in FIG. 3, the figure (a).

As shown in (b), dross remains, and as shown in (c), the average value (Ra) is more than twice that of the surface roughness of the cut surface and the maximum value (Rmax) is approximately four times that of Figure 2. became.

The table shows the test results of examining the relationship between the supply pressure of nitrogen gas and the properties of the cut surface of the workpiece, with and without suctioning nitrogen gas from the back surface of the workpiece, and FIG. 4 is a graph thereof. In this way, when not suctioning from the back side of the workpiece,
For drossless cutting, which requires a nitrogen gas supply pressure of 8.2 Kgf/cJ or more, at least 4 Kgf/cJ from the back side.
By supplying compressed air of 6.d to create a negative pressure of at least 0.9 Kgf/d, the supply pressure of nitrogen gas is 6. OKgf
/d, and the surface was glossy without an oxide film, and it was found that the features of a high-speed axial flow type carbon dioxide laser processing machine could be demonstrated even on stainless steel plates.

=8- However, under the above conditions, if the cutting speed is faster than 1.6 m/min, it cannot be cut, and if the thickness is as thin as 1 m, it can be cut even if the speed is increased to 4.5 m/min. Under the above conditions, the cutting part vibrated and surface roughness could not be obtained, so the above cutting properties could be obtained by fixing with a jig.

Note that the above stainless steel plate with a thickness of 4.5n+m could be cut by lowering the cutting speed to 0.5m/min, but
Even if the pressure of nitrogen gas was increased to 8.6 Kgf/al, drossless cutting could not be achieved.

In addition, for mild steel plates, when using nitrogen gas, the plate thickness ratio is maximum 10 to 5.
At a height of 0%, dross remained, and when a release agent (boron nitland) was sprayed on the back side, it became dross-free. In addition, when it was 0□, an oxide film was formed on the cut surface, as is known.

In addition, even if suction is applied from the back side of an aluminum (A5052) plate, approximately 50% of the adhering area of dross remains compared to when suction is not performed.As a result, the laser cutting method and device of the present invention have a remarkable effect on stainless steel plates. In the above example, the suction pipe 12 was connected to the lower end of the suction pipe 11, but it is also possible to connect the suction pipe 12 directly to the underside of the workpiece 5 and move the workpiece 5 using the XY child table of the NC device. good.

〔Effect of the invention〕

As described above, according to the present invention, in a laser cutting method in which a stainless steel plate is cut by irradiating a laser beam while supplying an inert gas to one side of the cutting part, the pressure in the suction pipe provided on the other side of the cutting part is reduced. The pressure was set to at least 0.9 kgf/cJ or less to suck out the inert gas flowing from the cutting part to the other side, and the cutting was performed using continuous wave output light from a high-speed axial flow type carbon dioxide laser device as a laser beam. Thus, it is possible to obtain a method and apparatus for laser cutting a stainless steel plate, which can cut a stainless steel plate that is difficult to cut without dross with a cut surface having a fine surface roughness.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the laser cutting method for stainless steel sheets and the apparatus according to the present invention, and FIG. 2 is a diagram showing the operation of the laser cutting method for stainless steel sheets according to the invention and the apparatus. Figure 2 (a) is a photograph of the entire cut, Figure 2 (b) is an enlarged photograph of the cut part, Figure 2 (c) is a graph showing the roughness of the cut part, and Figure 3 is a laser cut of the stainless steel sheet of the present invention. A diagram showing a comparative example of one embodiment of a cutting method and its device,
Figures 4 and 5 are graphs showing the operation of the laser cutting method for stainless steel sheets and the apparatus of the present invention. 11 bags meet. 4... Laser light 5... Work 6...
Nitrogen gas as an inert gas 11...Suction pipe 12...Suction pipe (8
733) Agent: Yoshiaki Inomata, patent attorney (and 1 others)
Name) Procedural amendment (method)! Figure 7 1.8.4 Month, Day, 1998

Claims (2)

[Claims] (1) In a laser cutting method in which a stainless steel plate is cut by irradiating a laser beam onto the cutting section from one side while supplying an inert gas to one side of the cutting section, the pressure in the suction pipe on the other side of the cutting section is reduced. At least 0.9Kgf/cm^2
A method for laser cutting a stainless steel plate, in which the inert gas flowing from the cutting part to the other side of the cutting part is sucked, and cutting is performed using a continuous wave laser beam emitted from a high-speed axial flow type carbon dioxide laser device, as follows: . (2) In a laser cutting device in which an inert gas is supplied to one side and a laser beam is irradiated to the one side to cut a stainless steel plate, a high-speed axial flow carbon dioxide laser device that emits the continuous wave laser beam; A laser cutting device characterized in that a suction pipe is provided on the other side of the stainless steel plate and uses compressed air supplied to the intermediate portion to reduce the internal pressure to at least 0.9 Kgf/cm^2.