JPS59142520A - Condensing lens cooling device of laser applied machine - Google Patents

Abstract

PURPOSE:To prevent the adhesion of a foreign matter by constituting a part of a condensing lens contact part of a lens holder, of a porous body, making an auxiliary gas pass through said part, jetting it from a nozzle, cooling it, and also forming an auxiliary gas curtain on the lower face of the condensing lens. CONSTITUTION:An auxiliary gas 12 in a lens holder 14 from a pipe 13 goes into a ring-like porous ring 19 through a communicating hole 23 from a ring-like gas passage 21. The upper face of a lens 18 is closed by a position control face 25, the gas 12 does not flow out to the upper face of the lens 18, and the gas 12 passing through the ring 19 is all jetted to the lower face from a gas jetting layer (d) formed by a projecting part 24. A part of the gas 12 passing through the inside of the ring 19 contacts directly to the lens 18, cools it, also the heat is exchanged with the ring 19, and the lens 18 is cooled indirectly, too. Also, the gas 12 jetted to the lower face of the lens 18 is brought to an adiabatic expansion and a gas curtain is formed on the lower face of the lens 18. In this way, simultaneously with cooling, it is prevented that a foreign matter adheres to the lower face of the lens 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to laser application machines such as laser processing machines and laser scalpels, and particularly to a cooling device for a condensing lens thereof.

For example, as is well known, laser processing machines can process metals, synthetic resins,
This process involves cutting, drilling, welding, scribing, etc. on workpieces such as wood, glass, or ceramics using laser light. It consists of a bender and a light guide path, and a light condensing section that has a built-in condenser lens that converges the laser light from the light guide path and irradiates it onto the workpiece. In this laser processing machine, the higher the power density of the focused laser beam, the more advantageous it is in terms of processing efficiency and processing accuracy.
Generally, the energy of the laser light incident on the condensing lens is several to
A high-energy light beam of several tens of kilowatts is used.

By the way, as the energy of such laser beams increases,
Condensing lenses are more likely to generate heat. In other words, when the laser beam passes through the condenser lens, energy is lost due to, for example, the anti-reflection layer coated on the condenser lens, very slight absorption in the condenser lens material, or scattering due to unevenness on the condenser lens surface. occurs, and this lost energy is converted into heat. Therefore, the higher the energy of the laser beam and the longer the irradiation time, the more susceptible the condenser lens is to the effects of heat.

If thermal deformation occurs as a result of heat generation, the irradiation position of the laser beam will shift, and the refractive index will change, leading to a decrease in processing accuracy due to an error in the focal length, or the focusing efficiency of the laser beam will decrease, resulting in a reduction in processing efficiency. This causes various problems such as a decrease in the durability of the condensing lens.

To solve these problems, conventional laser processing machines have been used in which a cooling fluid passage for cooling the focusing lens is formed in the focusing section, and the focusing lens is cooled by this cooling fluid. However, this conventional device has the drawbacks of a complicated and heavy structure due to the passages and piping for the cooling fluid, high cost, and poor operability.

Furthermore, as shown in FIGS. 1 and 2, Japanese Patent Application Laid-Open No. 102392 discloses that a condensing lens 2 that converges a laser beam 1 is held in a lens holder 4 having a cooling fin 3. The condenser lens 2 is cooled without using cooling water by cooling it with auxiliary gas that enters through the introduction pipe 5 and jets out from the nozzle 6. The auxiliary gas is a gas such as oxygen or nitrogen that is injected toward the workpiece at a high flow rate to force the workpiece melt, which has an extremely high absorption rate, to improve efficiency. However, in this cooling structure, only a portion of the auxiliary gas supplied from the introduction pipe 5 comes into contact with the cooling fins, and even if the number of cooling fins is increased,
Alternatively, even if fine irregularities are formed on the surface of the cooling fin,
Since a reliable cooling effect cannot be obtained, it is necessary to increase the heat capacity by using a large-diameter condensing lens, and it is still impossible to avoid an increase in size and cost.

Furthermore, when processing is actually performed using a conventional laser processing machine, the workpiece is instantly melted by the laser beam, so the molten workpiece and evaporated atoms from the melt are scattered around by the auxiliary gas and collected. It adheres to the bottom surface of the optical lens and causes contamination. This problem is the same in the laser processing machines having cooling fins as shown in Figs. This has a major practical drawback in that the condenser lens is inevitably damaged due to heat.

The present invention has been made to solve these problems, and includes a lens holder that holds a condensing lens, in which at least a part of the part in contact with the condensing lens is made of a porous material, and an auxiliary gas It is characterized in that it is ejected from a nozzle after passing through the porous body and the lower surface of the condensing lens. By directly cooling the condensing lens with the auxiliary gas passing through the porous body and then passing the auxiliary gas through the bottom surface of the condensing lens, a gas curtain of the auxiliary gas is formed on the bottom surface of the condensing lens, thereby removing foreign particles. This prevents the adhesion of

The invention will now be described with reference to the illustrated embodiments. FIG. 3 is a longitudinal sectional view showing the basic configuration of the condensing lens cooling device of the present invention. An introduction tube 13 for introducing auxiliary gas 12 from an auxiliary gas supply source (not shown) and a lens holder 14 are removably screwed together at the tip of the light guide tube 11 that guides the laser beam l. Further, a nozzle 16 having a nozzle throat 15 is removably screwed into the tip of the lens holder 1.4.

The lens holder 14 has an outer tube 17 screwed onto the light guide tube ti.
, an annular porous ring 19 that directly holds the condensing lens 18 , and a holding ring 2 that fixes the annular porous ring 19 to the outer cylinder 11 .
0, and an annular gas passage 21 communicating with the introduction pipe 13 is formed in the outer cylinder 17. The annular gas passage 21 communicates with an annular chamber 22 that accommodates the annular porous ring 19 through a plurality of communication holes 23 in the optical axis direction, and the auxiliary gas 12 is supplied from the annular gas passage 21 and the communication holes 23 through the annular porous ring. 19.

The annular porous ring 19 has a convex portion 24 that holds the lower surface (laser light emitting surface) of the condenser lens 18 . The convex portion 24 may be annular or may be divided into a plurality of parts in the circumferential direction. gas injection layer). The upper surface (laser light incident surface) of the condensing lens 18 is in contact with a 5-position regulating surface 25 provided integrally with the outer tube 17 . This position regulating surface 25 has the function of regulating the position of the condensing lens 18 and at the same time preventing the auxiliary gas 12 from flowing to the upper surface side of the condensing lens 18 .

The annular porous ring 19 is formed using a material with excellent heat resistance and air permeability. For example, it can be composed of a sintered body of metal materials such as aluminum, brass, stainless steel, tungsten, molybdenum, etc., and it can be made of not only metal sintered bodies but also glass beads and ceramics as long as it has an appropriate mesh. A solid body, a synthetic resin filter, etc. can be used. Note that IO indicates a workpiece.

Accordingly, in the present apparatus having the above configuration, the auxiliary gas 12 introduced into the lens holder 14 from the introduction pipe 13 enters the annular porous ring 19 from the annular gas passage 21 through the communication hole 23.

Since the upper surface of the condenser lens 18 is closed by the position regulating surface 25 as described above, the auxiliary gas 12 does not flow out to the upper surface of the condenser lens 18 and the annular porous ring 19
All of the auxiliary gas 12 that has passed through is injected onto the lower surface of the condenser lens 18 from the gas injection layer d formed by the convex portion 24 . In this process, a part of the auxiliary gas 12 passing through the annular porous ring 19 directly contacts the condensing lens 18 to cool it, and the auxiliary gas 12 that does not directly contact the condensing lens 18 also passes through the annular porous ring. The condenser lens 18 is indirectly cooled by exchanging heat with the condenser lens 19 .

Furthermore, after cooling the condenser lens 18 in this manner, the auxiliary gas 12 injected from the gas injection layer d expands adiabatically and forms a gas curtain on the lower surface of the condenser lens 18 . Therefore, the condensing lens 18 is further cooled by this gas curtain,
In addition, this gas curtain simultaneously prevents foreign matter from adhering to the lower surface of the condenser lens 18, thereby minimizing deformation of the condenser lens 18' due to heat generation and energy loss of the laser beam in the condenser lens 18. Therefore, processing accuracy can be maintained, damage to the condensing lens 18 can be prevented, and the diameter of the expensive condensing lens 18 can be made as small as the diameter of the laser beam l.

4 and 5 show other embodiments of the present invention. In this embodiment, the injection direction of the auxiliary gas 12 from the gas injection layer d is regulated by a presser ring 20, and the presser ring 20 has a protrusion 26 that closes the gas injection layer d, and a notch 27 that opens the gas injection layer d. Approximately 1806 of them are formed respectively. The rest of the structure is the same as that of the embodiment shown in FIG. 3, and the same parts are given the same reference numerals.

According to this embodiment, the auxiliary gas 12 is ejected in one direction from the notch 27 toward the protrusion 26, making the gas curtain stronger and preventing foreign matter from adhering to the lower surface of the condenser lens 18. This can be more completely prevented and the transmittance and light-gathering ability of the condenser lens 18 can be kept more constant. Of course, the angle and positional relationship between the protrusion 26 and the notch 27 are not limited to those in the embodiment, and can be modified as appropriate.

Furthermore, FIG. 6 shows an example in which the annular porous ring 19 is constructed from a combination. That is, the annular porous ring 19 in this embodiment has a three-layer structure in which a synthetic resin filter 19b is arranged between metal sintered filters 19'a, 19a, and the metal sintered filter 19a has a thickness of, for example, 5 to 50 microns. The synthetic resin filter 19b has a mesh of 0.0
The mesh should be between 5 and 0.5 microns. According to this coupling structure, it is possible to remove impurities in the auxiliary gas 12 by using a synthetic resin filter with a particularly fine mesh, and fresh auxiliary gas 12 is always supplied from the gas injection layer d.
can be adiabatically expanded and ejected. The annular porous ring 19 is to be replaced in a timely manner if it becomes clogged.

In the above embodiment, the annular porous ring 19 is in contact with the entire circumference of the condenser lens 18, and according to this example, it is possible to obtain a higher cooling effect. It is possible to obtain a certain cooling effect even if only the part in contact with the condenser lens 18 is made of a porous material. In particular, when forming a gas curtain on the lower surface of the condenser lens 18, it is not necessary to cover the entire circumference of the condenser lens 18. It is not necessary to hold it in a porous body. Furthermore, although the above embodiments apply the present invention to a laser processing machine, the present invention can also be applied to laser scalpels and other laser application machines.

As described above, in the present invention, at least a part of the lens holder of the condensing lens of a laser processing machine is made of a porous body, and an auxiliary gas is passed through the porous body to cool the condensing lens. The auxiliary gas that has passed through the mass is ejected from the bottom surface of the condenser lens to form a gas curtain on the bottom surface of the condenser lens, which simultaneously cools the condenser lens and prevents foreign matter from adhering to the bottom surface of the condenser lens. can be achieved. Therefore, damage to the condensing lens due to heat generation and adhesion of melted material or its evaporated atoms are prevented, the transmittance or light gathering ability of the condensing lens is always maintained constant, and the diameter of the condensing lens is It has an excellent effect in that it can be made to have a diameter as small as the beam diameter of the laser beam.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of the main part showing an example of a condensing lens cooling device of a conventional laser processing machine, and Fig. 2 is a section II-II of Fig. 1.
3 is a longitudinal sectional view showing an embodiment of the condensing lens cooling device of the present invention; FIG. 4 is a longitudinal sectional view of main parts showing another embodiment of the present invention; FIG. 5 is a sectional view taken along the line; 6 is a perspective view showing an example of a presser ring used in the embodiment of FIG. 4, and FIG. 6 is a longitudinal sectional view of a main part showing still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Laser light, 11...Light guide tube, 12...Auxiliary gas, 13...Introduction tube, 14...Lens boulder, 1
7...Outer tube, 1..Condenser lens, 19..Annular porous ring, 20..Pressure ring, 24..Convex portion, 26..
...Protrusion, 27...Notch. d... Auxiliary gas injection layer. Patent applicant: Asahi Optical Industry Co., Ltd. Agent: Kunio Miura Figure 3 Stirrup

Claims (1)

[Claims] (1) At the tip of the light guide tube that guides the laser beam, a condenser lens that focuses the laser beam onto the workpiece and a nozzle that injects auxiliary gas toward the workpiece are provided. In the provided laser application device, at least a portion of the lens holder holding the condenser lens in contact with the condenser lens is made of a porous body, and the auxiliary gas is supplied to the porous body and the condenser lens. A condensing lens cooling device for a laser application machine, characterized in that the condensing lens is ejected from the nozzle after passing through the lower surface of the lens. (2. In claim 1, the lens holder has an outer cylinder fixed to the light guide tube and a convex portion that holds the lower surface of the condenser lens, and has an annular shape inserted into the outer cylinder. A condensing lens cooling device for a laser application machine comprising a porous ring and a retainer ring that fixes the annular porous ring to the outer cylinder. (3) In claim 2, the retainer ring: A condensing lens cooling device for a laser application machine having a notch and a protrusion, which controls the size of an auxiliary gas injection layer formed by a convex portion of an annular porous ring. (4) Claims 1 to 5. In any of the above items, the porous body is a sintered body of metal such as aluminum, brass, stainless steel, or tungsten, a sintered body of glass beads, or a ceramic, or a synthetic resin filter, or a tb2 filter. A condensing lens cooling device for a laser application machine consisting of the above combination.