JPH02160194A - Head for laser cutting - Google Patents

Abstract

PURPOSE:To increase the pressure of an assist gas without adding a large pressurizing force to a lens and to increase the speed of laser cutting by supplying the assist gas of a high pressure from a high-pressure gas supply port into a high-pressure chamber in the state of pressurizing a middle-pressure gas. CONSTITUTION:The pressurizing gas of the middle pressure is first supplied from a middle-pressure gas supply port 14. The uniform pressurizing force is loaded by the principle of Pascal on the surfaces of a pressure partition wall 11 and the surface of the lens 7 by the supply of this middle-pressure gas. However, this pressurizing force is in the range of a permissible pressure and, therefore, the damage of the lens 7, and the pressure partition wall 11 is obviated. The assist gas of the high pressure is supplied from the high- pressure gas supply port 9 in the state of pressurizing this middle-pressure gas. The assist gas of the high pressure is ejected from an ejection hole 3 and pressurizes the surface of the lens 7. The lens 7 eventually receives the pressurizing force in the direction reverse from the pressurizing force of the middle- pressure gas by injection of the high-pressure gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a head for laser cutting. More specifically, the present invention relates to a laser cutting head that improves processing efficiency by increasing the pressure of assist gas used in laser cutting.

[Prior Art] Laser beam cutting involves narrowing a laser beam, irradiating the laser beam onto a sheet metal material, etc., and instantaneously melting and vaporizing the material to create and cut small diameter holes and narrow grooves. This melted and vaporized slag is physically removed from the laser irradiation side to the back side of the workpiece by spraying pressurized assist gas onto the melted portion. The type of assist gas is selected from oxygen gas, air, inert gas, etc. depending on the material to be cut, but it is generally known that increasing the pressure increases the cutting speed.

The assist gas is ejected from the tip of the head that irradiates the laser beam, that is, from the focus 2 part (see Figure 5).
The focus 2 portion is a space in which the lens 7 is held, pressurized assist gas is temporarily stored, and is ejected. The pressure of the assist gas is maintained by the space surrounded by the focus 2 portion and the lens 7 that refracts the laser beam, so that a pressing force is applied to the lens 7. To increase cutting speed,
The pressure resistance of the lens 7 is increased.

The material used for the lens 7 is a glass-based material doped with selenium, etc. that transmits laser light, and a metal material used for the focus 2, which has different pressure resistance strength.Normally, the lens 7 is weak, so the above-mentioned The pressure of the assist gas cannot be set higher than the allowable pressure resistance of the lens 7. A method of increasing the thickness of the lens 7 to increase the pressure resistance of the lens 7.
Improvements are being made to the materials. However, currently, this allowable pressure strength is usually around 5 to 6 kg/cm2, and it is not possible to increase the pressure of the assist gas any further. If this is ignored, the lens may be destroyed and toxic gases may be generated. There is also.

A method using two lenses in the head has also been proposed in order to increase the pressure of the assist gas. The structure of the head shown in Fig. 6 is an example of this (Proceedings of the 3rd International Laser Processing Conference).
international conference
on La5ers in sanufacL
uring%1986, Birsingham, P.
35)) The upper lens 7b focuses the laser beam, and the focused laser beam passes through the small hole 3a and irradiates the high-pressure assist gas chamber, and the lower lens 7a inside the high-pressure assist gas focuses the laser beam. Then, the focus is adjusted for further processing. This type of laser head has a small hole 3a,
High-pressure assist gas is ejected from the upper and lower parts of the ejection hole 3.

[Problems to be Solved by the Invention] The above-described structure for increasing the pressure of assist gas requires upper and lower lenses. Further, a small hole 3a is opened in the upper part of the lens barrel filled with high-pressure assist gas for transmitting laser light. Since the assist gas is ejected from this small hole 3a, the assist gas is wasted. Further, adjustment is difficult because the focus must be focused on the small hole 3a. The present invention was developed focusing on these problems, and achieves the following objects.

An object of the present invention is to provide a laser cutting head that improves the discharge pressure of assist gas.

Another object of the present invention is to provide a laser cutting head that improves cutting speed.

[Means for solving the above problems] In order to solve the above problem, the following measures will be taken.

The first method is to use a cylindrical lens barrel, a lens that is airtightly held and fixed in the lens barrel and refracts the laser beam, in laser beam cutting in which the workpiece is melted and vaporized and cut using a laser beam. A pressure partition hermetically fixed in the lens barrel in series with the lens, an intermediate pressure chamber formed in a space between the pressure partition and the lens, and a space surrounded by the lens and the lens barrel. This is a laser cutting head consisting of a high pressure chamber that is formed in a high pressure chamber that temporarily stores assist gas and ejects it to the cutting device.

In the first means, it is more effective if the pressure partition walls have a plurality of sheets and the spaces between the pressure partition walls are used as intermediate pressure chambers lower than the high pressure chamber to form a plurality of medium pressure chambers that are sequentially lowered to atmospheric pressure. be.

The second method is to use a cylindrical lens barrel and a laser beam that is held and fixed in such a way that an assist gas (described later) freely passes through the lens barrel. A lens that refracts light, a pressure partition airtightly fixed in series with the lens within the lens barrel, and a space formed between the pressure partition and the lens barrel to temporarily store assist gas. This is a laser cutting head characterized by comprising a high pressure chamber that ejects water at a cutting position.

In the second means, it is more effective to form a plurality of intermediate pressure chambers in which the pressure partition walls have a plurality of sheets and the spaces between the pressure partition walls are used as intermediate pressure chambers lower than the high pressure chamber and are sequentially lowered to atmospheric pressure. be.

[Function] First, medium-pressure pressurized gas is supplied from the medium-pressure gas supply port. By supplying this intermediate pressure gas, a uniform pressing force is applied to the pressure partition wall and the surface of the lens according to Pascal's principle.

However, this pressurizing force is within the allowable pressure range, so it will not damage the lens or the pressure partition wall.With this medium pressure gas pressurized, high pressure assist gas is supplied into the high pressure chamber from the high pressure gas supply port. .

The high-pressure assist gas is ejected from the ejection hole and pressurizes the surface of the lens. By injecting the high-pressure gas, the lens is subjected to a pressing force in a direction opposite to the pressing force of the intermediate-pressure gas. However, the pressurizing force per unit area is only the differential pressure between the pressurizing force of the high pressure assist gas and the pressurizing force of the intermediate pressure gas. Even if high pressure is used for this lick, assist gas,
No large pressing force is applied to the lens.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

What is shown in FIG. 1 is a sectional view of a portion of a lens barrel 1 that outputs laser light. The lens barrel 1 is a cylindrical tube and is made of a known metal material such as aluminum. A focus 2 is integrally formed at the tip of the lens barrel 1. The tip of the focus 2 is provided with a small ejection hole 3 through which laser light passes and which ejects assist gas, which will be described later.

A cylindrical lens holding tube 4 is inserted into the inner peripheral surface of the lens tube 1.

A groove is formed on the outer periphery of the lower end of the lens holding cylinder 4, and a groove is formed on the inner peripheral surface of the lens cylinder 1 to match this groove. A cooling chamber 5 is created by these two grooves. Temperature-controlled cooling water is supplied to the cooling chamber 5 from a supply port 6, and the lens barrel 1 is constantly cooled. A lens 7 is inserted into the lens holding cylinder 4. The lens 7 is a known laser beam lens that refracts the laser beam to create a focal point. A closed space surrounded by the lens 7 and the focus 2 forms a high pressure chamber 8.

This high pressure chamber 8 is a space for temporarily storing high pressure assist gas and ejecting it from the ejection hole 3.

High-pressure assist gas is supplied from the high-pressure gas supply port 9 . On the other hand, the lens 7 is in contact with one end of the cylindrical spacer 10 and is pressurized. The other end of the spacer 10 is in contact with the pressure partition 11 . The pressure partition wall 11 has a uniform thickness and transmits laser light, and its optical function is simply to transmit the laser light. The pressure partition wall 11 is
Furthermore, it is in contact with another spacer 12. The other end of the spacer 12 is fixed by means such as a screw (not shown), and pressurizes the pressure partition wall 11 and the lens 7 in the axial direction.

Airtightness is maintained between the lens 7, the pressure partition wall 11, and the spacer 10.12 by means such as an O-ring. The space between the lens 7 and the pressure partition 11 forms an intermediate pressure chamber 13. A gas whose pressure is lower than that of the gas supplied to the high pressure chamber 8 is supplied to the intermediate pressure chamber 13 from an intermediate pressure gas supply port 14 . Note that the gas supplied to the intermediate pressure chamber 13 does not have to have the same composition as the assist gas, and may simply be a pressurized gas lower than the high pressure assist gas. pressure bulkhead 11
On the opposite side of the intermediate pressure chamber 13 is an atmospheric pressure chamber 15.

The atmospheric pressure chamber 15 is a space containing unpressurized air, that is, air having the same pressure as atmospheric pressure.

[Second Example PA] What is shown in FIG. 2 is a sectional view of the lens barrel 1 showing a second example. This embodiment differs from the first embodiment in that a plurality of pressure partition walls 11 are provided. Between the high pressure chamber 8 and the atmospheric pressure chamber 15, intermediate pressure chambers 13a, 13b, and 13c are provided in multiple stages. The pressurizing pressure of the assist gas in the high pressure chamber 8 is Pn, and the pressure in the medium pressure chamber 13 is Pn.
The pressure of a is 23, the pressure of medium pressure chamber 13b is P2, and the pressure of medium pressure chamber 13 is
If the pressure of c is Pl, atmospheric pressure < PI < P2 < PS
The gas pressure is selected so that the relationship <Pn holds true.

The pressure applied to the lens 7 and each pressure partition 11 is not large because it is only the pressure difference between the pressure in the adjacent pressurizing chamber.For example, in the case of the second embodiment, the pressure applied to the lens 7 and each pressure partition 11 is not large. If the allowable pressure is 5 kg/cm'', the pressure of the assist gas can be increased to 20 kg/cm''. Note that the number of pressure partition walls 11 may be any number as required.

[Third Embodiment] In the first and second embodiments described above, the pressurizing force of the assist gas is also applied to the lens 7 itself. However, although the lens 7 is made of a reinforced material so as to be able to withstand the pressurizing force, its mechanical strength is weaker than that of the pressure partition wall 11 because it does not have a simple planar structure. However, when burned by laser beams, toxic gases may be emitted. The cross-sectional view of the lens barrel 1 of the third embodiment shown in FIG. 3 is an example in which the pressurizing force of the assist gas applied to the lens 7 is extremely small.

The through hole 2o, which is an example of providing the through hole 20 through which the assist gas can freely pass through the outer periphery of the lens 7, that is, the area through which the laser beam does not pass, is provided at the edge of the outer periphery integral with the lens 7 in this embodiment. However, other components such as a lens holding cylinder 4 may be provided as long as the pressures of the assist gas on the front and back sides of the lens 7 are kept at the same pressure.

The pressure of the assist gas is applied uniformly to the entire surface of the lens 7, which has the advantage that bending stress, which is the weakest in the lens, does not occur. Therefore, the life of the lens 7 is also extended.

[Fourth Embodiment] The cross-sectional view of the lens 7 in FIG. 4 shows a fourth embodiment, which is a combination of the third embodiment and the second embodiment described above, and a detailed explanation thereof will be omitted. The pressure of the assist gas can be increased without increasing the pressure applied to the lens 7.

Although each embodiment has been described above, the structure, position, and number of the cooling chamber 5, lens holding tube 4, spacer 10.12, each gas supply port 9.14, etc. in the above embodiments may be modified as necessary. It is clear from the foregoing description that various design modifications are possible, and these means are well known in the laser cutting art.

[Effects of the Invention] As described above in detail, the present invention can increase the pressure of the assist gas without applying a large pressing force, especially bending pressure, to the lens. As a result, the speed of laser cutting can be increased.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the lens barrel of the first embodiment, and Fig. 2 is a cross-sectional view of the lens barrel of the first embodiment.
3 is a sectional view of the lens barrel of the third embodiment, FIG. 4 is a sectional view of the lens barrel of the fourth embodiment, and FIG. 5 is a sectional view of the lens barrel of the prior art. 6 is a sectional view of a lens barrel showing still another conventional technique. DESCRIPTION OF SYMBOLS 1... Lens tube, 2... Focus part, 3... Ejection hole, 5... Cooling chamber, 7... Lens, 11... Pressure partition, 20... Through hole

Claims (1)

[Scope of Claims] 1. In laser beam cutting, in which a workpiece is melted and vaporized to be cut by a laser beam, a cylindrical lens barrel and a lens that is airtightly held and fixed within the lens barrel and refracts the laser beam are used. , a pressure partition hermetically fixed in the lens barrel in series with the lens, an intermediate pressure chamber formed in a space between the pressure partition and the lens, and an area surrounded by the lens and the lens barrel. A head for laser cutting processing characterized by comprising a high pressure chamber formed in a space where assist gas is temporarily stored and ejected to a cutting position. 2. In claim 1, the pressure partition wall has a plurality of sheets, and the space between the pressure partition walls is used as an intermediate pressure chamber lower than the high pressure chamber, and has a plurality of medium pressure chambers that sequentially lower the pressure to atmospheric pressure. Head for laser cutting processing. 3. In laser beam cutting, in which the workpiece is melted and evaporated to be cut using a laser beam, a cylindrical lens tube is used, and the lens tube is held and fixed so that the assist gas (described later) can freely pass through the lens tube, and refracts the laser beam. a lens; a pressure bulkhead airtightly fixed within the lens barrel in series with the lens;
A head for laser cutting processing, comprising a high pressure chamber formed in a space surrounded by the pressure partition and the lens barrel, and temporarily stores assist gas and ejects it to the cutting position. 4. Claim 3, characterized in that the pressure partition wall has a plurality of sheets, and the space between the pressure partition walls is used as an intermediate pressure chamber lower than the high pressure chamber, and has a plurality of medium pressure chambers that sequentially lower the pressure to atmospheric pressure. Head for laser cutting processing.