JPS59206189A - Laser beam cutting device - Google Patents

Abstract

PURPOSE:To enable cutting of a metallic material in a thickness direction with excellent dimensional accuracy of cutting in the case of cutting the thick metallic plate by a laser beam to a shape having a sharp angle by cooling the metallic plate from the rear side in the stage of cutting the sharp angled part. CONSTITUTION:A thick metallic plate 31 to be worked is connected on rollers 33 to an X-Y table 30 moved in X- and Y directions by the command from a pattern control part 35. The laser light 22 from an oscillator 21 is converged by a condenser lens 24 and is irradiated together with auxiliary cutting gas 28 such as O2 or N2 onto the plate 31 then the plate is cut to a target shape when the table 30 moves. If a sharp angled part exists in the shape to be cut in this case, a cooling liquid 38 is ejected in a form of mist from a nozzle 42 by high pressure gas 37 to cool the sharp angled cutting part from the rear in the stage of cutting said sharp angled part, by which the self-combustion effect of the sharp angled part by the laser light is eliminated and the uniformly cut surface is formed in the thickness direction. The cutting with high dimensional accuracy is thus accomplished.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a laser cutting device.

[Technical background of the invention and its problems]

Conventionally, it has been put into practical use to cut a steel plate by condensing a laser beam and spraying oxygen gas. A problem in this processing is that the cutting shape is (1) → (2) → (3) → (4) when cutting a triangle (TA) from a plate material (W), as shown in Figure 1. When the laser beam is scanned, the line (1) → (2) is cut once, and the line (3) → (4) is cut a second time.
As shown in Figure 2, the part close to the back surface of the acute angle inner region (D) that is cut when approaching the point (5) that changes to an acute angle is not cut faithfully to the scanning shape for laser beam cutting on the front surface and is damaged. Part (6) is formed.

This phenomenon tends to occur when the depth of focus of the focused laser beam is shallow, and it tends to occur when the energy of the laser beam is large in a deep part where the laser beam does not reach sufficiently. As shown in Figure 2, especially on the cutting surface of thick materials, there is a cutting area (9) that can be controlled by the laser beam and an area 0 (1) that cannot be controlled by the laser beam.
1 occurs. Therefore, when cutting thick plates with high precision, especially when machining angles where the value of θ is small, (4) → (3),
It is necessary to scan in the directions (1) -> (2) and (3) -> (2) to prevent the formation of sharp cutting ends and to take measures to prevent the formation of missing parts. As the plate thickness increases, cutting perpendicularly from the front surface to the back surface may result in a technically difficult cutting shape, so in practice, setting the cutting conditions requires changing the type of gas for spraying, from oxygen to g. Efforts are being made to reduce the power of the laser. However, creating a machining order program by specifying the cutting direction according to the cutting shape is inefficient, and there are also cases where it is not possible to continue machining the shape in one stroke. machining efficiency decreases. Even if the type of gas is changed, the equipment becomes complicated and the cutting results are not always satisfactory.

Conventionally, methods have been used to cool the surface by spraying a cooling medium around the laser beam irradiation point from the surface of the workpiece, and sometimes by heating gas before spraying. However, these methods aim to improve the cutting accuracy in the trenches near the surface where the laser beam can directly reach the cutting surface, or to improve the machining speed with fewer laser beams. A direct effect is an insufficient means to prevent the occurrence of a defect in the lower part when the depth of the laser beam becomes thick relative to the origin depth of the laser beam. In particular, if a cooling liquid is sprayed from the surface, the laser beam will be scattered at the condensing part, resulting in a decrease in the varnish bead, and there are several difficulties in putting it into practical use.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus that can eliminate non-uniformity in cutting line width due to cutting shape.

[Summary of the invention]

In the cutting process, the back surface of the workpiece is specifically cooled intensively at the acute angle portion of the cut portion.

[Embodiments of the invention]

Invention? The embodiment will be explained based on the drawings. Third
In the figure, Q】) is a YAG laser oscillator, CO.

Laser oscillator A laser oscillator selected from other laser oscillators emits processing laser light (24 is transmitted through a reflecting mirror Q31,
It is designed to be guided to a nozzle (c) which has a condensing lens C24) inside. (A) is a supply source of oxygen gas, nitrogen gas, etc., which are auxiliary gases for cutting, and the auxiliary gases are supplied into the nozzle (C) through a supply pipe. A solenoid valve (c) is installed in the middle of the supply pipe, and a laser oscillator Q
υ oscillation control device C! It is designed to open and close in synchronization with the control signal (g). (To) is an XY table, and a gripping body C3B that protrudes from this table on the X table or Y table side that is the upper part and holds the workpiece (31)
is installed. The workpiece el) is passed through the above nozzle (
5), the above-mentioned XY table (7)
It stands as if sliding on the roller (c) by scanning. (Foundation) is a drive source that scans the XY table (to) and outputs a drive signal to the XY table (to) based on the pattern control section (three commands). On the other hand, a device for cooling the back surface of the workpiece c31 is provided on the back side of the workpiece f (21).This cooling device is connected to the high pressure gas source ( 37) and coolant (to) by introducing high pressure gas.
Tank 09 equipped with a mechanism to atomize water, and tank (to)
It consists of an injection pipe (40) introduced into the tank, a suction pipe (0υ) immersed in the cooling liquid, and an injection tool (4) connected to the wing of the tank C3 and provided facing the back side. A solenoid valve (4) is provided in the middle of the curve of the injection pipe. The solenoid valve (4) is controlled to open and close by means of a pattern control section.

In the above configuration, the laser beam (A) is emitted in response to a command from the oscillation control device, and at the same time, auxiliary gas is introduced into the nozzle (C), and irradiation and injection are performed toward the cutting location of the workpiece C31). It will be done. Also, the delay circuit (a)
After drilling a hole in the workpiece CD by the action of , the pattern control section (to) is activated and a control signal is sent to the drive source (34). As a result, fi, the XY table (to) is driven based on the control signal. In the process of cutting a desired pattern by driving the XY table (2), a mist of cooling liquid is sprayed onto the back side of the workpiece 01) to cool the workpiece 01).

In addition, in this cooling, the acute angle part of the above pattern, that is, the first
Open the electromagnetic valve (49) from the position (8) in front of the part corresponding to the point 15) on the cutting line (3) → (4) near the area (D) in the figure. Preferably, the cooling is performed by jetting material.

Cooling on the back side eliminates the self-combustion effect, especially at sharp corners, making it possible to be more precise. Alternatively, cold air may be injected.

〔Effect of the invention〕

Since the cutting section is configured to cool and cut so as not to overheat the acute angle part with a small heat capacity, it is possible to cut and scan the bamboo strips without causing a decrease in efficiency, and the cutting line width can also be adjusted to the pattern shape. We were able to achieve uniform and accurate machining regardless of the problem.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing cutting scanning, FIG. 2 is a sectional view showing a part of a cutting section in a conventional cutting method, and FIG. 3 is a configuration diagram showing an embodiment of the present invention. 01)...Laser oscillator ff14)...Condensing lens (c)...Nozzle 00)...
・XY table C341...pattern control section (
Support)...High pressure gas source c37)...Cooling liquid G
Injuries: Agent for propellant, patent attorney Noriyuki Chika (and one other person)

Claims (2)

[Claims] (1) A device that focuses and irradiates laser light emitted from a laser oscillator onto the cutting portion of the workpiece, a device that supplies auxiliary gas to the cutting portion in conjunction with the irradiation of the laser beam, and the laser beam. A laser cutting device comprising a device for scanning the workpiece relative to the workpiece according to a desired shape, further comprising a device for cooling the back side of the workpiece during the relative scanning process. Laser cutting equipment. (2) The laser cutting device according to claim 1, wherein the cooling device is controlled so as to intensively cool the acute angle portion of the processed shape of the cut portion.