Laser processing apparatus and laser processing method

Abstract

To provide a laser processing apparatus capable of stabilizing a liquid column and increasing a distance at which a laser is stably guided.SOLUTION: A laser processing apparatus 10 includes: a liquid supply chamber 16; a nozzle 17 including an ejection port 17b facing to the liquid supply chamber 16, and a liquid column forming chamber 17c connected to the ejection port 17b to allow a liquid column 41 generated from the ejection port 17b to pass through; an outlet pipe 21 through which the liquid column 41 passes and which is inserted into the liquid column forming chamber 17c; a liquid column discharge port 22 connected to the outlet pipe 21; a gas introduction channel 20 connected to an outer side of the outlet pipe 21 in the liquid column forming chamber 17c; and an optical lens 14 which focuses a laser on the ejection port 17b through the liquid supply chamber 16.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laser processing apparatus and a laser processing method. [Background technology]

[0002] An apparatus for generating a liquid jet into which a laser beam is guided is known (for example, Japanese Patent No. 5882927). This apparatus includes a fluid nozzle having a nozzle duct, an optical system for focusing on an inlet opening of the nozzle duct, a housing having a space, a gas inlet for supplying gas to the space, and a gas outlet nozzle having a gas outlet for discharging the gas in the space. The gas outlet is positioned downstream from the fluid nozzle. Summary of the Invention [Problem to be solved by the invention]

[0003] In conventional laser processing equipment, the liquid column can become unstable, which can shorten the distance from the processing head where the laser can be stably guided into the liquid column. An object of the present invention is to provide a laser processing apparatus and a laser processing method that can stabilize the liquid column and increase the distance over which the laser is stably guided. [Means for solving the problem]

[0004] A first aspect of the present invention is a liquid supply chamber; A nozzle, a nozzle facing the liquid supply chamber; a liquid column forming chamber connected to the nozzle and through which the liquid column generated from the nozzle passes; a nozzle having an outlet pipe through which the liquid column passes and which is inserted into the liquid column formation chamber; a liquid column outlet connected to the outlet pipe; a gas introduction passage connected to the outside of the outlet pipe within the liquid column formation chamber; an optical lens that focuses the laser on the nozzle through the liquid supply chamber; The laser processing device has the following features.

[0005] A second aspect of the present invention is The liquid column formed from the nozzle outlet is discharged from the liquid column discharge port. A laser is focused on the nozzle, a gas is made to flow from a lower end of the nozzle toward the nozzle, the gas swirls near the nozzle, the gas flows along the liquid column so as to wrap around the liquid column, and the gas is discharged from the liquid column discharge port; The workpiece is processed by the laser propagating through the liquid column. This is a laser processing method.

[0006] The laser processing device may include a laser oscillator that emits a laser. The gas introduction passage may be connected to the radially outer side of the outlet pipe. The connecting conduits may extend radially from the nozzle orifice. The conical portion may be directly connected to the cylindrical portion. The conical portion may be disposed closer to the nozzle hole of the cylindrical portion. The conical portion has a smaller diameter toward the nozzle hole. The conical portion may have a right circular cone shape.

[0007] The laser oscillator emits a laser, and the optical lens may focus the laser on the nozzle. Gas may be made to flow from the edge of the liquid column forming chamber of the nozzle toward the nozzle opening, causing the gas to swirl near the nozzle opening and then being discharged from the liquid column discharge opening via the outlet pipe. The gas flows so as to envelop the liquid column. The gas velocity is higher than the velocity on the surface of the liquid column. The gas also flows so as to envelop the liquid column inside the outlet tube and outside the laser head. [Effects of the Invention]

[0008] According to the present invention, the liquid column can be stabilized, and the distance over which the laser can be stably guided can be increased. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a longitudinal sectional view of a laser processing apparatus according to an embodiment of the present invention; [Figure 2] Cross section of line II-II in Figure 1 [Figure 3] Cross section of line III-III in Figure 1 [Figure 4] Vertical cross section of laser processing equipment when in use [Figure 5] Vertical cross section of laser processing equipment when in use [Figure 6] Vertical cross section of laser processing equipment when in use DETAILED DESCRIPTION OF THE INVENTION

[0010] As shown in Fig. 1, a laser processing apparatus 10 of this embodiment has a laser oscillator 31, a pump 33, a gas source 35, and a laser head 11. The laser head 11 has a head body 13, an optical lens 14, a window 15, a nozzle 17, a packing 18, and a cap 19. Fig. 1 is a cross-sectional view taken along line II in Fig. 2. The laser head 11 has a central axis 1 and a liquid column discharge port 22. The side of the laser head 11 facing the liquid column discharge port 22 along the central axis 1 is referred to as the tip. The side opposite the tip is referred to as the base.

[0011] The laser oscillator 31 oscillates a laser, which is preferably a pulsed laser. The pump 33 is, for example, a piston pump. The pump 33 is a liquid pump. The pump 33 pressurizes the liquid to 10 MPa to several tens of MPa. The liquid is, for example, water. The gas source 35 is an air compressor or a gas cylinder. The gas source 35 supplies compressed air or helium gas to the laser head. The laser oscillator 31, the pump 33, and the gas source 35 may be disposed outside the laser processing apparatus 10.

[0012] The head body 13 is columnar. The head body 13 has, in order from the base end, a laser passage 13a, a window chamber 13b, a liquid supply chamber 16, a nozzle chamber 13c, a cap chamber 13d, and an end surface 13g. The laser passage 13a, the window chamber 13b, the liquid supply chamber 16, the nozzle chamber 13c, and the cap chamber 13d are arranged along the central axis 1. The laser passage 13a is a right circular truncated cone. The window chamber 13b and the nozzle chamber 13c are right circular cylindrical. The nozzle chamber 13c may have a packing groove (not shown). The liquid supply chamber 16 has a U-shaped cross section and is a body of revolution centered on the central axis 1. The cap chamber 13d is right circular cylindrical and has a female thread 13f. The female thread 13f is arranged at the tip of the cap chamber 13d.

[0013] Nozzle 17 is disposed in nozzle chamber 13c. Nozzle 17 has a nozzle tip 17a and a liquid column formation chamber 17c. Nozzle tip 17a is, for example, a jewel. Hereinafter, jewels include artificial jewels and sintered bodies of artificial jewels. Nozzle tip 17a has an orifice 17b. Orifice 17b extends along central axis 1. Liquid column formation chamber 17c is disposed along central axis 1. Liquid column formation chamber 17c may have a cylindrical portion 17f and a conical portion 17d. Cylindrical portion 17f is disposed at the tip of nozzle 17. Cylindrical portion 17f is a right cylinder. Conical portion 17d is disposed in contact with cylindrical portion 17f. Conical portion 17d is disposed at the base end of cylindrical portion 17f. Conical portion 17d may have a right cone shape. The diameter of conical portion 17d decreases as it approaches orifice 17b.

[0014] The packing 18 is disposed in a packing groove (not shown) and seals the gap between the head body 13 and the nozzle 17.

[0015] The window 15 is disposed in the window chamber 13b. The window 15 is a right circular cylinder. The window 15 is, for example, a jewel plate. The laser passes through the window 15. The laser is focused onto the nozzle hole 17b by the optical lens 14. The optical lens 14 may include multiple lenses.

[0016] The cap 19 is fastened to the cap chamber 13d. The cap 19 has a right cylindrical shape. The cap 19 holds the nozzle 17. The cap 19 has a first surface 19f, a second surface 19g, an outer cylindrical surface 19c, a male thread 19b, a nozzle chamber 19d, a first gas introduction passage 20, a discharge pipe 21, a liquid column discharge port 22, a second gas introduction passage 24, a recess 25, and a gas outlet 26.

[0017] The first surface 19f and the second surface 19g are flat surfaces. The first surface 19f and the second surface 19g are end surfaces of the cap 19. The first surface 19f abuts against the bottom surface of the cap chamber 13d. The second surface 19g is substantially flush with the end surface 13g. "Substantially flush" includes surfaces where the distance between the surfaces is 0.5 mm or less.

[0018] The outer cylindrical surface 19c is a cylindrical surface and has a smaller diameter than the male thread 19b. The outer cylindrical surface 19c is arranged on the base end side of the side surface of the cap 19. A gap is provided on the radially outer side of the outer cylindrical surface 19c. The height of the outer cylindrical surface 19c is approximately 50% of the surface-to-surface distance between the first surface 19f and the second surface 19g. The male thread 19b is arranged at the tip portion of the cap 19. The male thread 19b fits into the female thread 13f.

[0019] Recess 25 is disposed on second surface 19g. Recess 25 has a right circular truncated cone shape centered on central axis 1. Recess 25 has bottom surface 25a and side surfaces 25b. Bottom surface 25a is a plane perpendicular to central axis 1. Side surfaces 25b are right circular cone surfaces centered on central axis 1. Side surfaces 25b have a diameter that decreases toward first surface 19f.

[0020] The nozzle chamber 19d is disposed so as to open to the first surface 19f. The nozzle chamber 19d is a right cylinder centered on the central axis 1. The tip portion of the nozzle 17 is housed in the nozzle chamber 19d. The bottom surface of the nozzle chamber 19d abuts against the bottom surface of the nozzle 17. The inner cylindrical surface of the nozzle chamber 19d abuts against the outer cylindrical surface of the nozzle 17.

[0021] 1 and 2, the first gas introduction passage 20 includes a first dispersion chamber 20a, a plurality of first connection pipes 20b, and a collection chamber 20c. The first gas introduction passage 20 is disposed on the first surface 19f. The first gas introduction passage 20 may be open to the first surface 19f. The first dispersion chamber 20a is hollow and disk-shaped. The collecting chamber 20c is hollow and disk-shaped. The outer diameter of the collecting chamber 20c is smaller than the inner diameter of the first dispersion chamber 20a. The collecting chamber 20c is disposed radially inward of the first dispersion chamber 20a. The depth of the collecting chamber 20c from the first surface 19f may be the same as the depth of the first dispersion chamber 20a from the first surface 19f.

[0022] Each first connecting pipe 20b connects the first dispersion chamber 20a and the collecting chamber 20c. The first connecting pipe 20b extends radially from the collecting chamber 20c. The cross section of the first connecting pipe 20b is, for example, rectangular. The depth of the first connecting pipe 20b from the first surface 19f may be the same as the depth of the first dispersion chamber 20a from the first surface 19f. The first connecting pipe 20b may be rotationally symmetric about the central axis 1. As shown in FIG. 2, the first connecting pipe 20b of this embodiment is eight-fold rotationally symmetric about the central axis 1. The first connecting pipe line 20b may be disposed in the nozzle 17. In this case, the collecting chamber 20c may be integral with the cylindrical portion 17f.

[0023] The outlet pipe 21 and the liquid column discharge port 22 are arranged on the central axis 1. The outlet pipe 21 is a hollow cylinder. The outlet pipe 21 extends from the upper surface of the collecting chamber 20c toward the nozzle 17. The outlet pipe 21 is arranged inside the liquid column formation chamber 17c. The outlet pipe 21 protrudes in the proximal direction beyond the proximal edge of the collecting chamber 20c. The liquid column discharge port 22 is arranged on the bottom surface 25a. The liquid column discharge port 22 is a cylindrical hole, and communicates with the inner surface of the outlet pipe 21. The inner diameter of the liquid column discharge port 22 is the same as the inner diameter of the outlet pipe 21.

[0024] As shown in FIGS. 1 and 3, the second gas introduction passage 24 includes a second dispersion chamber 24a, multiple second connection pipes 24b, and a gas supply chamber 24c. The second gas introduction passage 24 is disposed closer to the tip than the first gas introduction passage 20. For example, the second dispersion chamber 24a is defined by the outer cylindrical surface 19c and the cap chamber 13d. The second dispersion chamber 24a has a thin-walled cylindrical shape. The second dispersion chamber 24a is disposed radially outward from the first dispersion chamber 20a. The gas supply chamber 24c has a hollow disk shape. The gas supply chamber 24c is disposed closer to the tip than the collection chamber 20c. Each second connection pipe 24b connects the second dispersion chamber 24a and the gas supply chamber 24c. The second connection pipes 24b are disposed closer to the tip than the first connection pipes 20b. The second connection pipes 24b extend, for example, on a straight line passing through the central axis 1. The second connecting pipeline 24b may be rotationally symmetric (n=8 in FIG. 3) about the central axis 1. As shown in FIG. 3, the second connecting pipeline 24b of this embodiment is eight-fold rotationally symmetric about the central axis 1.

[0025] As shown in FIG. 1, multiple gas outlets 26 penetrate from gas supply chamber 24c toward bottom surface 25a. Gas outlets 26 extend parallel to central axis 1. As shown in FIG. 3, gas outlets 26 are cylindrical holes. Gas outlets 26 may be small-diameter holes. The diameter of gas outlets 26 may be 1 mm or less. For example, the diameter of gas outlets 26 is 0.4 mm to 0.8 mm. Gas outlets 26 are arranged rotationally symmetrically (n=8 in FIG. 3) about central axis 1. As shown in FIG. 3, gas outlets 26 of this embodiment are eight-fold rotationally symmetric about central axis 1. Gas outlets 26 may be arranged in the center of the radial width of gas supply chamber 24c.

[0026] As shown in Figure 4, when the pump 33 supplies liquid to the laser head 11, a liquid column 41 is formed from the nozzle 17b via the liquid supply chamber 16. The liquid column 41 passes through the liquid column forming chamber 17c, the outlet pipe 21, and the liquid column outlet port 22, and is then discharged from the laser head 11. The laser oscillator 31 oscillates a laser. The laser is focused on the nozzle 17b via the window 15 by the optical lens 14. The laser then propagates inside the liquid column 41.

[0027] When the gas source 35 supplies gas to the first gas inlet passage 20, the gas is dispersed evenly within the first dispersion chamber 20a. The gas flows almost evenly into the collection chamber 20c from the multiple first connecting pipes 20b. The gas then flows from the collection chamber 20c into the liquid column formation chamber 17c. The gas forms a swirling flow 42 within the liquid column formation chamber 17c. The gas flows along the periphery of the cylindrical portion 17f toward the nozzle 17b. The gas changes direction toward the central axis 1 at the conical portion 17d near the nozzle 17b. The gas then swirls from near the nozzle 17b along the liquid column 41 toward the tip, passes through the center of the liquid column formation chamber 17c, and enters the inside of the outlet pipe 21. The gas is then ejected from the liquid column discharge port 22.

[0028] From the vicinity of the nozzle 17b in the liquid column formation chamber 17c, the gas flows in a manner that wraps around the outer periphery of the liquid column 41. The liquid column 41 is enveloped by a swirling gas flow 42 and flows inside the liquid column formation chamber 17c together with the gas flow. In the section from the base end of the outlet pipe 21 to the liquid column discharge port 22, the gas also flows in a manner that wraps around the liquid column 41. The gas flow 43 ejected from the liquid column discharge port 22 flows together with the liquid column 41, wrapping around the liquid column 41. The swirling flow 42 and gas flow 43 flow at a higher speed than the liquid column 41. Gas has a lower viscosity than liquid. As the gas flows in a manner that wraps around the liquid column 41, the speed of the gas flowing around it increases more than the surface of the liquid column 41. As a result, the swirling flow 42 and gas flow 43 reduce the vorticity at the interface between the surface of the liquid column 41 and the gas. The swirling flow 42 and the gas flow 43 promote the rectification of the liquid column 41 .

[0029] The outlet pipe 21 extends along the central axis 1 inside the liquid column formation chamber 17c. The collection chamber 20c is connected below the liquid column formation chamber 17c. As a result, the gas flows from the periphery of the liquid column formation chamber 17c toward the nozzle 17b, swirls near the nozzle 17b, and flows along the liquid column 41. The generation of a swirling flow 42 inside the liquid column formation chamber 17c forms a tubular flow of gas around the liquid column 41 discharged from the nozzle 17b. This prevents the liquid column 41 from tilting or becoming turbulent inside the liquid column formation chamber 17c. The liquid column formation chamber 17c has a cylindrical section 17f located at its tip and a conical section 17d located at its base. This promotes the formation of the swirling flow 42.

[0030] The flow of the liquid column 41 begins to become turbulent as it moves away from the nozzle 17. At position 45 where the outer surface of the liquid column 41 becomes turbulent, the laser leaks from the liquid column 41 to the outside. The laser processing apparatus 10 can effectively cut the area between the end face 13g and position 45. The distance from the end face 13g to position 45 is called the effective cutting length 49. In this embodiment, the first gas introduction path 20 is disposed near the tip face of the nozzle 17. The length of the first gas introduction path 20 in the direction of the central axis 1 is short. The second gas introduction path 24 is formed in the shape of a thin disk. Therefore, the distance 48 from the tip face of the nozzle 17 to the end face 13g is short. This allows the effective cutting length 49 to be long.

[0031] The inner diameter of the liquid column discharge port 22 is the same as the inner diameter of the lead-out pipe 21. Therefore, the vorticity of the gas flow and the liquid column 41 is suppressed between the inlet (base end) of the lead-out pipe 21 and the liquid column discharge port 22. This suppresses turbulence in the liquid column 41 and increases the effective cutting length 49. It also suppresses laser attenuation within the liquid column 41. As a result, the processing capability of the laser processing apparatus 10 is improved.

[0032] The energy of the laser propagating through the liquid column tends to decrease as the distance 47 from the nozzle 17 increases. Therefore, it is preferable to bring the nozzle 17 as close as possible to the workpiece 3. With the laser head 11, the distance 48 is short, so the distance 46 (see Figure 5) between the workpiece 3 and the nozzle 17 can be made short.

[0033] As shown in Fig. 5, a workpiece 3 is machined by the laser machining apparatus 10 of this embodiment. The workpiece 3 has a surface 3a. When the liquid column 41 collides with the workpiece 3, the liquid column 41 bounces off the surface 3a, causing liquid 51 to bounce back. The rebounded liquid 51 becomes droplets 53 and adheres to the tip surface of the laser head 11.

[0034] According to the prior art, the droplets 53 could be attracted to the liquid column outlet 22. When the droplets 53 adhere to the liquid column outlet 22, the liquid column 41 is likely to be disturbed. When the liquid column 41 is disturbed, the energy of the laser propagating within the liquid column 41 is likely to decrease. Furthermore, dross generated during machining could adhere to the tip surface of the laser head 11 together with the droplets 53. When the dross is attracted to the liquid column outlet 22 together with the droplets 53, the liquid column outlet 22 could become clogged with the dross.

[0035] The laser processing apparatus 10 of this embodiment has a gas outlet 26. Because the diameter of the gas outlet 26 is small, the total cross-sectional area of ​​the gas outlet 26 can be reduced. Therefore, the flow rate of the gas ejected from the gas outlet 26 can be reduced. Furthermore, even if the gas flow rate is reduced, the flow velocity of the gas ejected from the gas outlet 26 can be increased. Because the gas flow rate is small, the impact of the gas ejected from the gas outlet 26 on the liquid column 41 is small. Therefore, turbulence of the liquid column 41 caused by the gas ejected from the gas outlet 26 can be reduced. The gas ejected from the gas outlet 26 breaks up the splashed liquid 51, promoting its scattering. This reduces adhesion of the splashed liquid 51 to the tip surface of the laser head 11. By increasing the gas flow velocity, adhesion of the splashed liquid 51 can be suppressed.

[0036] The laser processing apparatus 10 of this embodiment has a recess 25. The recess 25 has a bottom surface 25a. The gas outlet 26 is disposed on the bottom surface 25a. When gas is ejected from the gas outlet 26, droplets 53 adhering to the bottom surface 25a move toward the periphery. Most of the droplets 53 are then discharged from the side surface 25b through the second surface 19g and the end surface 13g. The outward inclination of the side surface 25b promotes the discharge of the droplets 53. The second surface 19g and the end surface 13g are substantially flush with each other, promoting the discharge of the droplets 53. This reduces the adverse effects of the splashed liquid 51 adhering to the laser head 11. Furthermore, clogging of the liquid column discharge port 22 by dross can be suppressed.

[0037] Liquids have viscosity and surface tension. As shown in Figure 6, as the distance 61 between the laser head 11 and the workpiece 3 is reduced, a liquid pool tends to form between the laser head 11 and the workpiece 3. With conventional technology, the space between the laser head 11 and the surface 3a of the workpiece 3 may become filled with liquid. In this case, the laser cannot be efficiently irradiated onto the processing point, resulting in a significant decrease in processing ability.

[0038] The laser head 11 of this embodiment has a recess 25. A gas outlet 26 is disposed in the recess 25. Gas is ejected from the gas outlet 26. The ejected gas promotes the discharge of liquid from between the laser head 11 and the surface 3a toward the periphery. This makes it easier to form a space filled with gas between the recess 25 and the workpiece 3. Then, a liquid column 41 reaches the surface 3a, promoting the processing of the workpiece 3.

[0039] The gas flow path to the recess 25 (for example, the second gas introduction path 24 and the gas outlet 26) may be replaced with a conventional technique (for example, a second conduit in European Patent No. 31054043).

[0040] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention, and all technical matters included in the technical ideas described in the claims are subject to the present invention. The above-described embodiments are preferred examples, but a person skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the appended claims. [Explanation of symbols]

[0041] 10 Laser processing equipment 11 Laser Head 14 Optical Lenses 16 Liquid supply chamber 17 nozzles 17b spout 17c Liquid column formation chamber 20 First gas inlet passage (gas inlet passage) 21 Outlet pipe 22 Liquid column outlet 31 Laser oscillator

Claims

1. a liquid supply chamber; A nozzle, a nozzle facing the liquid supply chamber; a liquid column forming chamber connected to the nozzle and through which the liquid column generated from the nozzle passes; a nozzle having an outlet pipe through which the liquid column passes and which is inserted into the liquid column formation chamber; a liquid column outlet connected to the outlet pipe; a gas introduction passage connected to the outside of the outlet pipe within the liquid column formation chamber; an optical lens that focuses a laser on the nozzle through the liquid supply chamber; A laser processing device having:

2. Further comprising a laser oscillator for generating the laser. The laser processing device according to claim 1.

3. the liquid column discharge port has the same inner diameter as the outlet pipe; 3. The laser processing device according to claim 1 or 2.

4. The gas introduction path is an annular dispersion chamber disposed radially outside the nozzle; an annular collecting chamber connected to the liquid column forming chamber; a plurality of connecting pipes connecting the dispersion chamber and the collection chamber; having The laser processing device according to any one of claims 1 to 3.

5. The plurality of connecting pipes are arranged rotationally symmetrically with respect to the central axis of the nozzle. The laser processing device according to claim 4.

6. The connecting pipe extends along a straight line passing through a central axis of the nozzle.

6. The laser processing device according to claim 4 or 5.

7. the liquid column formation chamber has a right cylindrical portion centered on the central axis of the nozzle, The collecting chamber is connected to the right cylindrical portion. The laser processing device according to any one of claims 4 to 6.

8. the liquid column formation chamber is disposed closer to the nozzle than the right cylindrical portion and has a conical portion connected to the right cylindrical portion. The laser processing device according to claim 7.

9. a cap having the liquid column discharge port, the cap further having a recess at a tip thereof; The laser processing device according to any one of claims 1 to 8.

10. The liquid column formed from the nozzle outlet is discharged from the liquid column discharge port. A laser is focused on the nozzle, a gas is made to flow from a lower end of the nozzle toward the nozzle, the gas swirls near the nozzle, the gas flows along the liquid column so as to wrap around the liquid column, and the gas is discharged from the liquid column discharge port; The workpiece is processed by the laser propagating through the liquid column. Laser processing method.

11. the liquid column is discharged from the liquid column discharge port via a discharge pipe, the gas is discharged from the liquid column discharge port via the outlet pipe. The laser processing method according to claim 10.

12. The gas is supplied to an annular gas dispersion chamber; the gas is uniformly supplied from the gas dispersion chamber to the tip of the liquid column formation chamber via a plurality of connecting pipes; The laser processing method according to claim 10 or 11.

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