JPS58179589A - Laser machining method - Google Patents

Abstract

PURPOSE:To prevent the failure of the work and to improve laser machining accuracy by providing a dross removing means in tight contact with the surface of the work on the side opposite from the side to be irradiated with a laser beam and machining the work and the means simultaneously. CONSTITUTION:The work 6 and a dross removing means 14 are worked simultaneously with a laser beam 1'. The melt of the work 6 and the means 14 is pushed by a jet 8 and dross 15 sticks at the curving end of the means 14. If the means 14 is removed from the work 6 after the machining with the beam 1' is completed, the dross 15 is removed without sticking at the curved end of the work 6 and the damaging of the work 6 is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser processing method for drilling or cutting a workpiece by focusing a laser beam.

Generally, by focusing the laser beam emitted from a laser oscillation device with an external optical system, the beam spot at the laser beam focusing position has a size of approximately 50 μmφ to 5 μmφ.
It becomes a high power density of 1oW/c4 to 1oW/c.

Since this fine spot with high power density can instantaneously heat, melt, and sublimate the workpiece, the laser beam can perform fine surface treatment, welding, drilling, and cutting. Compared to other precision machining methods that involve mechanical drilling or cutting, laser beam machining is a non-contact process that does not come into direct contact with the workpiece, so it can process hard and brittle materials such as ceramics and precious metals. I can do it. In addition, unlike electron beam processing, there is no need for antistatic treatment or vacuum evacuation, so it is possible to process electrically insulating materials such as glass, fibers, fur, etc. Laser beam processing is similar to other precision processing methods. It has many advantages over the law.

The diameter of the laser beam emitted from a conventional laser device is about 10 mm, and when it is focused into a spot, the size of the laser beam spot is limited due to lens aberrations and diffraction aberrations in the focusing system. It is not possible to make the spot diameter smaller than 2 to 3 times the laser resonance wavelength, and in the case of a C02 laser, the spot diameter is about 60 μΦ.

YA (approximately 6μφ in the case of a laser.The power density distribution at the spot position is a distribution close to Gaussian, and in the tail portion where the power density is weak around the spot, the power density is sufficient to melt the workpiece. The problem arises that the molten material of the workpiece is not completely sublimated and becomes molten dross and adheres to the laser beam emission end side.

In particular, this molten dross is likely to adhere to (1)
When the workpiece is not completely melted due to insufficient laser beam power, or when the workpiece is too thick, (i+)
When the spot diameter of the laser beam is not small enough due to aberrations, (iiD When the material of the workpiece is a high melting point material, OV
) When the heat of vaporization of the material of the workpiece changes from a liquid phase to a gas phase is large; (V) When the material of the workpiece is sticky in a liquid phase and easily flows on the surface of the workpiece. A detailed explanation will be given below using the drawings.

FIG. 1 shows a conventional method of cutting a workpiece by focusing a laser beam emitted from a laser oscillator using a focusing system and moving the workpiece in a direction perpendicular to the plane of the paper. In the figure, 1 is the laser beam before being focused, and this beam 1 is fixed in the lens barrel 2 using a mount ring 3.
A spot i is connected on the workpiece 6. Perforation by laser processing.

When cutting, the image is focused so that the spot position is approximately at the center of the thickness of the workpiece 6, and the power density of the beam 1' is set to 106 W/cl or more at the processing position to increase processing efficiency. I have to.

In addition, in order to increase processing efficiency, jet gas 8 is generally introduced using a nozzle 7 to blow away the melt 9 of the workpiece generated at the processing position, or to facilitate the generation of reaction heat during melting. encourage.

At the tip of the nozzle, this jet gas 8 has a component that escapes from the gap between the nozzle tip and the surface of the workpiece 6.
The component 8" diffusely radiates on the laser beam emission end side, and it is not necessarily possible to blow away all of the melt 9 by the laser beam 1'. Figure 2 shows the power density distribution near the spot position of the laser beam 1'. This is an enlarged view showing the details of the cutting situation of the workpiece 6, and the numbers in the figure have the same meanings as those in Figure 1. Sublimation occurs in region a where the power density is sufficiently high, and the power density increases. low area.

At b', a molten layer that cannot be completely sublimated is formed, and the molten dross 9 is pushed out and adhered to the lower end of the kerf due to the jet gas (not shown). This is good for workpieces 6 such as thick metal plates, where the loss 9 can be mechanically removed by polishing with a brush after machining, but it is better for workpieces 6 such as thin metal plates or hard materials such as ceramics. When mechanically removing the molten dross 9 that adheres when processing a brittle material, defects such as deformation or damage to the original workpiece 6 occur.

In order to improve this defect, a method as shown in FIGS. 3a and 3b has conventionally been used. In other words, Figs. 3 a and b show that the molten dross is blown off from the outside or blown into the bed after laser processing when it is fluid, without applying mechanical force to the workpiece and destroying it. In the method of removal, the numbers in the figure have the same meanings as in FIG. 1. Figure 3a shows a method in which gas from a blower 10 is blown out from a nozzle 11 near the processing position to blow off molten dross generated on the back side of the workpiece 6. The figure shows an example in which the cutting is parallel to the plane of the paper. ing.

FIG. 3 shows a method for removing molten dross by sucking gas near the processing position using a suction pump 12 using an exhaust chamber 13. However, in the blowing method or suction method shown in Figures 3a and 3, it is necessary to install a nozzle 11 and a suction chamber 13 near the workpiece to remove the molten dross, which makes precision machining easier. However, it cannot be done at low cost.

The present invention solves the above-mentioned drawbacks and provides a laser processing method that is simple, low-cost, and capable of high-precision processing. This method uses a molten dross removal plate to perform drilling and cutting with a laser beam without causing molten dross to adhere to the workpiece.

FIG. 4 shows a first embodiment of the present invention.

In the figure, laser beam 1 is mounted inside lens barrel 2)
A condensing lens 6 fixed by IJ rings 3 and 4 irradiates the surface of the workpiece 6 with condensed light. At this time.

It is configured to use a nozzle 7 to spray jet gas 8 onto the surface of the workpiece.

A dross removing means 14 made of a plate or a film for removing molten dross 16 is installed on the laser beam emitting end side of the workpiece 6 in a state closely joined to the surface of the workpiece 6. This dross removing means 14 can be used as long as it has a plate or film thickness that can be sufficiently processed in the joined state. As for the material, it is suitable that it is made of the same material as the workpiece 6, but it does not necessarily have to be made of the same material as the workpiece, as long as it can efficiently absorb the laser beam 1'.
It may be made of metal or an insulator. For example, ordinary adhesive tape can also be used satisfactorily. This case is very significant in terms of low cost. The dross removing means 14 is provided on the surface of the workpiece 6 opposite to the side irradiated with the laser beam 1', and it can be held by mechanical force as long as it is in close contact with the surface of the workpiece 6. It does not matter whether they are inserted, fixed with adhesive, or physically connected by vapor deposition.

By arranging it in such a state, the laser beam 1
', the workpiece 6 and the dross removing means 14 are processed simultaneously. The dross generated during processing becomes a melt between the workpiece 6 and the dross removing means 14 and is pushed out by the jet stream 8, so that the dross 16 adheres to the kerf end of the dross removing means 14. If the dross removing means 14 is easily removed from the workpiece 6 after processing with the laser beam 1', the dross 15 from the molten layer of the workpiece 6 will adhere to the kerf edge of the workpiece 6. Therefore, laser processing with high cutting accuracy can be performed without damaging the workpiece 6 in any way.

As described above, the present invention relates to a laser processing method in which a laser beam generated from a CO2 gas laser device, a YAG solid-state laser device, etc. is focused by a condenser lens, and metals or non-metals are cut and drilled.

A dross removal means made of the same material as the workpiece or a material that can efficiently absorb the laser beam is closely stacked on the surface of the workpiece to be processed with the laser beam, opposite to the laser beam irradiation side. The workpiece and the dross removing means are simultaneously processed with a laser beam, and the dross removing means is then removed, without attaching dross to the back surface of the workpiece or damaging the workpiece.
It has the advantage of being able to perform high precision laser processing easily and at low cost.

[Brief explanation of the drawing]

Figure 1 is a sectional view explaining the conventional laser processing method, Figure 2 is an enlarged sectional view of the cut part of the workpiece in Figure 1, and Figure 3 a.
Figure 3 is an explanatory diagram of the conventional laser processing method using a blower to remove dross, Figure 3 is an illustration of the conventional laser processing method using a suction pump to remove dross, and Figure 4 is an illustration of the laser processing method of the present invention. It is a sectional view for explanation. 1... Laser beam, 2... Lens barrel, 3
, 4... Mount ring, 6... Condensing lens, 6... Workpiece, 7... Nozzle, 8... Jet stream Gas, 9.16...Dross, 14...Dross removal means. Name of agent: Patent attorney Toshio Nakao and one other person If
Figure 2 Figure f' Figure 13

Claims (1)

[Claims] A dross removing means is provided in close contact with the surface of the workpiece to be irradiated with the laser beam on the side opposite to the irradiation beam, and the dross removing means is removed after simultaneously processing the workpiece and the dross removing means. Laser processing method.