Laser processing machine and nozzle unit for laser processing machine

Abstract

To inhibit infiltration of a light shielding liquid into a processing range of a workpiece effectively in a laser processing machine.SOLUTION: A nozzle unit includes a first nozzle, a second nozzle, a second outlet, a third nozzle, and a third outlet. The first nozzle includes a first outlet. An assist gas is blown from the first outlet to a workpiece. An inner shield gas is blown from the second outlet to the workpiece to remove a light shielding liquid from between the first nozzle and the workpiece. An outer shield gas is blown from the third outlet to the workpiece to remove the light shielding liquid from between the first nozzle and the workpiece. A height of the third outlet relative to the workpiece is higher than a height of the second outlet relative to the workpiece. The height of the second outlet relative to the workpiece is higher than a height of the first outlet relative to the workpiece.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to a laser processing machine and a nozzle unit for a laser processing machine.

Background Art

[0002] A laser processing machine irradiates a workpiece with laser light from a nozzle to perform processing such as cutting on the workpiece. Most of the laser light irradiated on the workpiece is absorbed by the workpiece and melts the workpiece. However, a part of the laser light is reflected by the workpiece and scattered around. Therefore, for example, in the laser processing machine of Patent Document 1, a cover is provided to suppress the scattering of the laser light. The cover covers the moving range of the nozzle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above laser processing machine, the cover covers the moving range of the nozzle. Therefore, the laser processing machine becomes large-sized. In addition, since the laser light penetrates the workpiece and is reflected below the workpiece, there is a possibility that the laser light leaks to the outside. If a cover is provided below the workpiece to prevent such leakage of the laser light, the structure of the laser processing machine becomes complicated.

[0005] Therefore, the inventors of the present invention have devised a laser processing machine in which a workpiece is disposed in a liquid having light-shielding properties (hereinafter referred to as "light-shielding liquid"). The light-shielding liquid is, for example, an aqueous solution containing an additive such as carbon that absorbs light. The workpiece is disposed slightly below the liquid surface of the light-shielding liquid. Therefore, the surface of the workpiece is covered with the light-shielding liquid.

[0006] When the laser processing machine is in operation, it blows gas from the nozzle towards the workpiece. Thereby, the laser processing machine removes the light-shielding liquid from the surface of the workpiece and processes the workpiece with laser light. At that time, the portions outside the range where the gas is blown on the surface of the workpiece (hereinafter referred to as the "processing range") are covered with the light-shielding liquid. Therefore, with a simple structure, leakage of laser light is prevented.

[0007] On the other hand, in the above-mentioned laser processing machine, if the light-shielding liquid infiltrates into the processing range of the workpiece, the processing quality of the workpiece will deteriorate. Therefore, it is desirable to effectively suppress the infiltration of the light-shielding liquid into the processing range of the workpiece. The object of the present invention is to effectively suppress the infiltration of the light-shielding liquid into the processing range of the workpiece in a laser processing machine.

Means for Solving the Problem

[0008] The nozzle unit according to one aspect of the present invention is a nozzle unit for a laser processing machine that processes a workpiece disposed in a light-shielding liquid having light-shielding properties with laser light. The nozzle unit includes a first nozzle, a second nozzle, a second passage, a second outlet, a third nozzle, a third passage, and a third outlet. The first nozzle includes a first passage and a first outlet. Laser light and assist gas pass through the first passage. The first outlet is connected to the first passage. The first outlet blows out the assist gas toward the workpiece. The second nozzle is disposed outside the first nozzle. The second passage is provided between the first nozzle and the second nozzle. Inner shield gas passes through the second passage. The second outlet is connected to the second passage. The second outlet blows out the inner shield gas toward the workpiece to remove the light-shielding liquid from between the first nozzle and the workpiece. The third nozzle is disposed outside the second nozzle. The third passage is provided between the second nozzle and the third nozzle. Outer shield gas passes through the third passage. The third outlet is connected to the third passage. The third outlet blows out the outer shield gas toward the workpiece to remove the light-shielding liquid from between the first nozzle and the workpiece. The height of the third outlet with respect to the workpiece is higher than the height of the second outlet with respect to the workpiece. The height of the second outlet with respect to the workpiece is higher than the height of the first outlet with respect to the workpiece.

[0009] In the nozzle unit according to this aspect, the gases blown out from the first to third outlets flow through the space between the workpiece and the nozzle unit and toward the outside in the radial direction of the nozzle unit. Thereby, the intrusion of the light-shielding liquid into the processing range of the workpiece is effectively suppressed. Also, the heights of the first to third outlets with respect to the workpiece are in ascending order from the first to third outlets. In this way, as the positions of the first to third outlets with respect to the workpiece gradually increase, the gas flows smoothly from the center of the nozzle unit toward the outside. Thereby, even if droplets are present directly below the nozzle unit, the smoothly flowing gas can easily push the droplets outward. As a result, the intrusion of the light-shielding liquid into the processing range of the workpiece is effectively suppressed.

[0010] A laser processing machine according to another aspect of the present invention includes a liquid storage tank, a mounting table, a laser generator, a laser head, a driving device, and the nozzle unit described above. The liquid storage tank stores a light-shielding liquid. The mounting table is disposed in the liquid storage tank. A workpiece is placed on the mounting table. The laser generator generates laser light. The laser head is connected to the laser generator. The laser head is disposed above the mounting table. The driving device moves the laser head. The nozzle unit is attached to the laser head.

[0011] In the laser processing machine according to this aspect, leakage of laser light is prevented by the light-shielding liquid. Further, the nozzle unit effectively suppresses the intrusion of the light-shielding liquid into the processing range of the workpiece. Thereby, the processing quality of the workpiece is improved.

Effects of the Invention

[0012] According to the present invention, in a laser processing machine, the intrusion of a light-shielding liquid into the processing range of a workpiece is effectively suppressed. Thereby, the processing quality of the workpiece is improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a laser processing machine according to an embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of a laser processing machine 1 according to the embodiment. FIG. 2 is a schematic diagram showing the configuration of the laser processing machine 1. The laser processing machine 1 is a device that processes a workpiece W1 with laser light. As shown in FIG. 1, the laser processing machine 1 includes a liquid storage tank 2, a laser head 3, and a drive device 4.

[0015] The liquid storage tank 2 stores a light-shielding liquid L1 having light-shielding properties. The liquid storage tank 2 has a box-shaped configuration that opens upward. As shown in FIG. 2, a mounting table 11 and a sludge tray 12 are disposed in the liquid storage tank 2. A workpiece W1 is disposed on the mounting table 11. The mounting table 11 includes, for example, a plurality of plate members interconnected in a lattice pattern. The sludge tray 12 is disposed below the mounting table 11. The sludge tray 12 receives sludge generated when the workpiece W1 is processed by laser light.

[0016] The drive device 4 moves the laser head 3 above the mounting table 11. The drive device 4 moves the laser head 3 in the vertical direction (X), the lateral direction (Y), and the up-and-down direction (Z). The drive device 4 includes a first movable table 13, a second movable table 14, and a support table 15. The first movable table 13 is supported so as to be movable in the lateral direction (Y) with respect to the second movable table 14. The laser head 3 is supported so as to be movable in the up-and-down direction (Z) with respect to the first movable table 13. The second movable table 14 is supported so as to be movable in the vertical direction (X) with respect to the support table 15. The first movable table 13 is driven in the lateral direction (Y) by a first motor 16 shown in FIG. 2. The laser head 3 is driven in the up-and-down direction (Z) by a second motor 17. The second movable table 14 is driven in the vertical direction (X) by a third motor 18.

[0017] As shown in FIG. 2, the laser processing machine 1 includes a laser generator 19. The laser generator 19 generates laser light. The laser head 3 is connected to the laser generator 19. The laser generator 19 generates, for example, laser light by a fiber laser. The laser light has a wavelength of, for example, 0.7 μm or more and 10 μm or less. As shown in FIG. 2, the laser head 3 is connected to the laser generator 19 via a fiber cable 21. The laser head 3 includes a condenser lens 22. The laser head 3 condenses the laser light from the laser generator 19 onto the workpiece W1 by the condenser lens 22.

[0018] As shown in Fig. 2, the laser processing machine 1 is provided with a liquid level adjusting device 5. The liquid level adjusting device 5 changes the height of the liquid level of the light-shielding liquid L1 in the liquid storage tank 2 (hereinafter simply referred to as "liquid level"). The liquid level adjusting device 5 can change the liquid level between a position below the workpiece W1 shown in Fig. 2 and a position above the workpiece W1 shown in Fig. 3.

[0019] The liquid level adjusting device 5 includes a supply pipe 23 and a supply valve 24. The supply pipe 23 is connected to an external tank 25 and the liquid storage tank 2. The external tank 25 is arranged outside the liquid storage tank 2. The supply valve 24 is connected to the supply pipe 23. When the supply valve 24 is opened, the light-shielding liquid L1 is supplied from the external tank 25 to the liquid storage tank 2.

[0020] The liquid level adjusting device 5 includes an adjustment tank 26, a gas pipe 27, a pressure valve 28, and a pressure reducing valve 29. The inside of the adjustment tank 26 communicates with the inside of the liquid storage tank 2. The light-shielding liquid L1 can flow from the inside of the adjustment tank 26 into the liquid storage tank 2. Also, the light-shielding liquid L1 can flow from the inside of the liquid storage tank 2 into the adjustment tank 26. The gas pipe 27 connects the adjustment tank 26 and a gas supply source (not shown). The pressure valve 28 and the pressure reducing valve 29 are connected to the gas pipe 27.

[0021] When the pressure valve 28 is opened, gas is supplied into the adjustment tank 26. Thereby, as shown in Fig. 3, the light-shielding liquid L1 is pushed out from the inside of the adjustment tank 26 and flows into the liquid storage tank 2. Thereby, the liquid level in the liquid storage tank 2 rises. Also, when the pressure reducing valve 29 is opened, gas is discharged from the inside of the adjustment tank 26 to the outside. Thereby, as shown in Fig. 2, the light-shielding liquid L1 flows from the inside of the liquid storage tank into the adjustment tank 26. Thereby, the liquid level in the liquid storage tank 2 drops.

[0022] The liquid level adjusting device 5 includes an overflow pipe 31. The overflow pipe 31 is connected to the liquid storage tank 2 and the external tank 25. When the liquid level in the liquid storage tank 2 becomes equal to or higher than a predetermined upper limit height, the light-shielding liquid L1 in the liquid storage tank 2 is discharged to the external tank 25 through the overflow pipe 31.

[0023] The liquid level adjustment device 5 includes a discharge pipe 32 and a discharge valve 33. The discharge pipe 32 is connected to the liquid storage tank 2 and the external tank 25. The discharge valve 33 is connected to the discharge pipe 32. When the discharge valve 33 is opened, the light-shielding liquid L1 is discharged from the liquid storage tank 2 through the discharge pipe 32 to the external tank 25.

[0024] The light-shielding liquid L1 suppresses the transmission of the laser light described above. The light transmittance of the light-shielding liquid L1 in the wavelength range of 0.7 μm or more and 10 μm or less is, for example, 10% / cm or less. Preferably, the light transmittance of the light-shielding liquid L1 in the wavelength range of 0.7 μm or more and 10 μm or less is 5% / cm or less. More preferably, the light transmittance of the light-shielding liquid L1 in the wavelength range of 0.7 μm or more and 10 μm or less is 3% / cm or less.

[0025] In the present embodiment, the light-shielding liquid L1 is obtained by dispersing a light-shielding additive in an aqueous solution. The additive includes, for example, carbon black. However, the additive may be other substances having high light-shielding properties against laser light. The concentration of carbon black is, for example, 4.0 to 20.0% by weight. Preferably, the concentration of carbon black is 5.0 to 10.0% by weight.

[0026] The laser processing machine 1 includes a liquid level sensor 34 and a transmittance sensor 35. The liquid level sensor 34 detects the liquid level of the light-shielding liquid L1 in the liquid storage tank 2. The liquid level sensor 34 outputs a signal indicating the liquid level. The transmittance sensor 35 detects the transmittance of the light-shielding liquid L1 in the liquid storage tank 2 with respect to the laser light. The transmittance sensor 35 outputs a signal indicating the transmittance.

[0027] The laser processing machine 1 includes a controller 36 and an input device 37. The controller 36 includes a processor such as a CPU and a memory. The controller 36 stores a program and data for controlling the laser processing machine 1. The drive device 4 and the laser generator 19 are controlled by signals from the controller 36. The supply valve 24, the pressure valve 28, and the pressure reducing valve 29 are controlled by signals from the controller 36. The controller 36 receives signals from the liquid level sensor 34 and the transmittance sensor 35.

[0028] The input device 37 can be operated by the operator of the laser processing machine 1. The input device 37 includes, for example, a switch. The input device 37 may include a touch panel. The input device 37 may include a connection port for an external recording medium. The input device 37 may be an external computer. The operator can input processing conditions using the input device 37. The processing conditions include the plate thickness, material, processing speed, designed shape, etc. of the workpiece W1. The input device 37 outputs a signal indicating the processing conditions to the controller 36.

[0029] The controller 36 cuts the workpiece W1 into a desired shape by controlling the laser processing machine 1 according to the program and the processing conditions. The controller 36 controls the liquid level adjusting device 5 to change the liquid level of the light shielding liquid L1 in the liquid storage tank 2. The controller 36 controls the laser generator 19 to irradiate the workpiece W1 with laser light from the laser head 3. The controller 36 controls the drive device 4 to move the laser head 3 above the workpiece W1.

[0030] As shown in FIG. 3, the laser processing machine 1 according to the present embodiment performs processing on the workpiece W1 in a state where the liquid level of the light shielding liquid L1 is located above the workpiece W1. As shown in FIG. 4, a nozzle unit 6 is attached to the laser head 3. The laser head 3 irradiates the workpiece W1 with the laser light L2 from the nozzle unit 6.

[0031] Further, the laser head 3 blows gas from the nozzle unit 6 toward the workpiece W1. Thereby, the light-shielding liquid L1 is removed from the surface of the workpiece W1, and the workpiece W1 is processed by the laser beam L2. At this time, portions other than the processing range on the surface of the workpiece W1 are covered with the light-shielding liquid L1. Further, as shown in FIG. 2, a light-shielding cover 38 is attached to the laser head 3. Leakage of the laser beam upward from the processing range is prevented by the light-shielding cover 38. The processing range is the range on the surface of the workpiece W1 where gas is blown. The processing range includes the irradiation point of the laser beam L2 on the surface of the workpiece W1. The processing range includes at least the range facing the nozzle unit 6.

[0032] Hereinafter, the structures of the laser head 3 and the nozzle unit 6 will be described in detail. The nozzle unit 6 is attached to the tip of the laser head 3. FIG. 5 is a cross-sectional view of the laser head 3. As shown in FIG. 5, the laser head 3 includes a nozzle pedestal 41, a first gas port 42, a second gas port 43, and a third gas port 44.

[0033] The nozzle unit 6 is detachably attached to the nozzle pedestal 41. The nozzle pedestal 41 includes a mounting hole 45. The mounting hole 45 extends upward from the front end surface 46 of the nozzle pedestal 41. A part of the nozzle unit 6 is disposed in the mounting hole 45. The nozzle pedestal 41 includes a laser passage 47 and a gas passage 48. The laser passage 47 extends in the axial direction.

[0034] In the following description, the "axial direction" means the axial direction of the nozzle unit 6 and a direction parallel to the axial direction of the nozzle unit 6. The "radial direction" means the radial direction of the nozzle unit 6 and a direction parallel to the radial direction of the nozzle unit 6. The laser beam L2 from the laser generator 19 passes through the laser passage 47. The gas passage 48 is partitioned from the laser passage 47. The gas passage 48 is disposed outward in the radial direction of the laser passage 47.

[0035] The first gas port 42, the second gas port 43, and the third gas port 44 are connected to the nozzle pedestal 41. The first gas port 42 and the second gas port 43 communicate with a gas passage 48 inside the nozzle pedestal 41. A first gas pipe 51 is connected to the first gas port 42. A second gas pipe 52 is connected to the second gas port 43. The third gas port 44 communicates with a laser passage 47 inside the nozzle pedestal 41. A third gas pipe 53 shown in FIG. 2 is connected to the third gas port 44.

[0036] As shown in FIG. 2, the laser processing machine 1 includes a gas control device 7. The gas control device 7 controls the gas blown out from the laser head 3. The gas control device 7 includes a first gas valve 54 and a second gas valve 55. The first gas valve 54 and the second gas valve 55 are controlled by signals from the controller 36. The first gas pipe 51 and the second gas pipe 52 are connected to a gas supply source (not shown) via the first gas valve 54. Shielding gas is supplied to the laser head 3 through the first gas pipe 51 and the second gas pipe 52. The third gas pipe 53 is connected to a gas supply source (not shown) via the second gas valve 55. Assist gas is supplied to the laser head 3 through the third gas pipe 53.

[0037] In the case of processing mild steel or low-carbon steel, for example, oxygen is used as the assist gas in order to utilize the oxidation-reduction reaction. In the case of processing stainless steel, since the oxidation-reduction reaction cannot be utilized, for example, nitrogen is used as the assist gas in order to prevent the generation of oxides on the cut surface. Regarding the shielding gas, since it is used to remove the light-shielding liquid L1 from the surface of the workpiece W1, for example, inexpensive compressed air is used.

[0038] The nozzle unit 6 is detachably attached to the laser head 3. That is, the nozzle unit 6 is interchangeably attached to the laser head 3. In the following description of the nozzle unit 6, the direction from the base end to the tip of the nozzle unit 6 is defined as downward. Also, the direction from the tip to the base end of the nozzle unit 6 is defined as upward.

[0039] The tip of the nozzle unit 6 means the side facing the workpiece W1 among the ends in the axial direction of the nozzle unit 6. The base end of the nozzle unit 6 is located opposite to the tip of the nozzle unit 6 in the axial direction of the nozzle unit 6. FIG. 6 is a cross-sectional view of the nozzle unit 6. FIG. 7 is an enlarged cross-sectional view of the nozzle unit 6. The nozzle unit 6 includes a first nozzle 61, a second nozzle 62, and a third nozzle 63.

[0040] FIG. 8 is a cross-sectional view of the first nozzle 61. The first nozzle 61 is made of a conductive metal. For example, the first nozzle 61 is made of copper. However, the first nozzle 61 may be made of a metal other than copper. The first nozzle 61 includes a first through hole 64. The first through hole 64 penetrates the first nozzle 61 in the axial direction.

[0041] The first through hole 64 includes a main body hole portion 65 and a first Laval nozzle portion 66. The main body hole portion 65 extends downward from the base end 610 of the first nozzle 61. The main body hole portion 65 extends linearly in the axial direction. The first Laval nozzle portion 66 extends upward from the tip 611 of the first nozzle 61. The first Laval nozzle portion 66 includes a first inlet portion 661, a first intermediate portion 662, and a first outlet portion 663. The first Laval nozzle portion 66 has a shape that narrows at the first intermediate portion 662.

[0042] The first inlet portion 661 is connected to the main body hole portion 65. The inner diameter of the first inlet portion 661 is smaller than the inner diameter of the main body hole portion 65. The first inlet portion 661 is inclined so as to radially contract toward the tip 611 of the first nozzle 61. The first intermediate portion 662 is located between the first inlet portion 661 and the first outlet portion 663. The first outlet portion 663 is connected to the tip 611 of the first nozzle 61. The first outlet portion 663 is inclined so as to radially expand toward the tip 611 of the first nozzle 61.

[0043] The outer surface of the first nozzle 61 includes a first main body portion 67, a first tip portion 68, and a first stepped portion 69. The first main body portion 67 has an outer diameter larger than the outer diameter of the first tip portion 68. The first main body portion 67 extends downward from the proximal end 610 of the first nozzle 61. The first tip portion 68 protrudes downward from the first main body portion 67. The first tip portion 68 extends upward from the tip 611 of the first nozzle 61. The first stepped portion 69 is provided between the first main body portion 67 and the first tip portion 68.

[0044] The second nozzle 62 is disposed outside the first nozzle 61. The second nozzle 62 is made of an insulator. For example, the second nozzle 62 is made of ceramic. Alternatively, the second nozzle 62 may be made of other insulators such as resin. FIG. 9 is a cross-sectional view of the second nozzle 62. FIG. 10 is a perspective view of the second nozzle 62.

[0045] The second nozzle 62 includes a second through hole 71. The second through hole 71 penetrates the second nozzle 62 in the axial direction. The first tip portion 68 of the first nozzle 61 is disposed in the second through hole 71. As shown in FIG. 9, the second through hole 71 includes a nozzle connection portion 72 and a second Laval nozzle portion 73.

[0046] The nozzle connection portion 72 extends downward from the proximal end 620 of the second nozzle 62. The edge of the nozzle connection portion 72 is chamfered. The nozzle connection portion 72 is fixed to the first tip portion 68 of the first nozzle 61. The nozzle connection portion 72 is fixed to the first tip portion 68, for example, by press-fitting. Alternatively, the nozzle connection portion 72 may be fixed to the first tip portion 68 by other fixing means such as screwing. The nozzle connection portion 72 is in contact with the first tip portion 68. Thereby, the space between the first tip portion 68 and the nozzle connection portion 72 is sealed.

[0047] The second Laval nozzle portion 73 is connected to the nozzle connection portion 72. The second Laval nozzle portion 73 extends upward from the tip 621 of the second nozzle 62. The second Laval nozzle portion 73 includes a second inlet portion 731, a second intermediate portion 732, and a second outlet portion 733. The second Laval nozzle portion 73 has a narrowed shape at the second intermediate portion 732.

[0048] The second inlet portion 731 is connected to the nozzle connection portion 72. The second inlet portion 731 has an inner diameter larger than the inner diameter of the nozzle connection portion 72. The second intermediate portion 732 is connected to the second inlet portion 731. The second intermediate portion 732 has an inner diameter smaller than the inner diameter of the second inlet portion 731. The second outlet portion 733 is connected to the second intermediate portion 732. The second outlet portion 733 extends upward from the tip 621 of the second nozzle 62. The second outlet portion 733 is inclined so as to expand radially toward the tip 621 of the second nozzle 62.

[0049] The outer surface of the second nozzle 62 includes a second main body portion 74, a second tip portion 75, and a second stepped portion 76. The second main body portion 74 extends downward from the base end 620 of the second nozzle 62. As shown in FIG. 10, the second main body portion 74 includes a prism portion 77 and a cylindrical portion 78. The prism portion 77 has a polygonal column shape. The corners of the prism portion 77 are chamfered. In the present embodiment, the prism portion 77 has a hexagonal column shape. However, the prism portion 77 may have other polygonal column shapes.

[0050] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 7. The outer diameter of the cylindrical portion 78 is smaller than the diagonal length of the prism portion 77. The outer diameter of the cylindrical portion 78 is the same as the distance between the opposite sides of the prism portion 77. However, the outer diameter of the cylindrical portion 78 may be smaller than the distance between the opposite sides of the prism portion 77. The cylindrical portion 78 has an outer diameter larger than the outer diameter of the second tip portion 75. The second tip portion 75 protrudes downward from the cylindrical portion 78. The second tip portion 75 extends upward from the tip 621 of the second nozzle 62. The second stepped portion 76 is provided between the second main body portion 74 and the second tip portion 75.

[0051] The second nozzle 62 includes a plurality of holes 780. The plurality of holes 780 extend radially from the second through hole 71 of the second nozzle 62 to the outer surface of the second nozzle 62. The plurality of holes 780 extend radially from the second through hole 71 of the second nozzle 62. Specifically, the plurality of holes 780 extend from the second inlet portion 731 of the second nozzle 62 to the cylindrical portion 78. The plurality of holes 780 are arranged offset from the center of the second nozzle 62. Alternatively, the plurality of holes 780 may be inclined with respect to the radial direction. In the drawings, only some of the plurality of holes 780 are labeled with reference numeral 780, and the reference numerals of the other plurality of holes 780 are omitted.

[0052] FIG. 12 is a view of the second nozzle 62 as seen from the tip side. As shown in FIG. 12, the second nozzle 62 includes an annular groove 760 and a plurality of grooves 761. The annular groove 760 and the plurality of grooves 761 are provided on the second stepped portion 76. The annular groove 760 is disposed around the second tip portion 75. The plurality of grooves 761 extend radially from the annular groove 760 to the outer surface of the second nozzle 62. The plurality of grooves 761 extend radially from the annular groove 760. Specifically, the plurality of grooves 761 extend from the annular groove 760 to the cylindrical portion 78. The plurality of grooves 761 are arranged offset from the center of the second nozzle 62. Alternatively, the plurality of grooves 761 may be inclined with respect to the radial direction. In the drawings, only some of the plurality of grooves 761 are labeled with reference numeral 761, and the reference numerals of the other plurality of grooves 761 are omitted.

[0053] The third nozzle 63 is disposed outside the second nozzle 62. FIG. 13 is a cross-sectional view of the third nozzle 63. As shown in FIG. 13, the third nozzle 63 includes a third through hole 79. The third through hole 79 penetrates the third nozzle 63 in the axial direction. The first nozzle 61 and the second nozzle 62 are disposed within the third through hole 79. The third through hole 79 includes a third inlet portion 81, a third outlet portion 82, and a third stepped portion 83. The third inlet portion 81 extends downward from the proximal end 630 of the third nozzle 63. The third outlet portion 82 extends upward from the distal end 631 of the third nozzle 63. The third outlet portion 82 has an inner diameter smaller than that of the third inlet portion 81. The third stepped portion 83 is provided between the third inlet portion 81 and the third outlet portion 82.

[0054] The third nozzle 63 includes an outer cap 84, a shield 85, and an insulating guide 86. The shield 85, the outer cap 84, and the insulating guide 86 are integrated. The shield 85, the outer cap 84, and the insulating guide 86 are joined to each other, for example, by press-fitting or adhesion. Alternatively, the shield 85, the outer cap 84, and the insulating guide 86 may be joined to each other by screwing.

[0055] The outer cap 84 is made of an insulator such as ceramic. However, the outer cap 84 may be made of other insulators such as resin. The outer cap 84 includes a cap main body portion 840 and a cap tip portion 841. The cap main body portion 840 has a cylindrical shape. A part of the cap main body portion 840 is disposed within the mounting hole 45 of the nozzle pedestal 41.

[0056] The cap main body portion 840 includes a first concave groove 842. The first concave groove 842 extends in the circumferential direction on the outer peripheral surface of the cap main body portion 840. The first O-ring 56 shown in FIG. 5 is disposed in the first concave groove 842. The first O-ring 56 seals between the cap main body portion 840 and the mounting hole 45. The first O-ring 56 prevents the light-shielding liquid L1 from entering the inside of the laser head 3.

[0057] The cap tip 841 includes a tapered surface 843 that is inclined so as to radially shrink toward the tip 631. The angle between the tapered surface 843 and the tip 631 is rounded and smoothed. The cap tip 841 is exposed outside the laser head 3. The cap tip 841 is disposed on the outer periphery of the second tip 75 of the second nozzle 62.

[0058] The shield 85 is disposed inside the outer cap 84. The shield 85 is made of a conductive metal. For example, the shield 85 is made of brass. However, the shield 85 may be made of a metal other than brass.

[0059] The shield 85 includes a shield main body portion 851 and a unit connecting portion 852. The shield main body portion 851 is disposed inside the outer cap 84. The unit connecting portion 852 protrudes upward from the outer cap 84. The unit connecting portion 852 is exposed and disposed outside the nozzle unit 6. The nozzle unit 6 is attached to the nozzle pedestal 41 at the unit connecting portion 852. For example, a male screw is provided on the unit connecting portion 852, and a female screw is provided in the mounting hole 45. The male screw of the unit connecting portion 852 is screwed into the female screw of the mounting hole 45. Thereby, the nozzle unit 6 is fixed to the nozzle pedestal 41.

[0060] The insulating guide 86 is disposed inside the shield 85. The insulating guide 86 is disposed between the first nozzle 61 and the second nozzle 62 and the shield 85. The insulating guide 86 is disposed outside the first nozzle 61 and the second nozzle 62. The shield 85 is covered by the outer cap 84 and the insulating guide 86. The insulating guide 86 is made of a material having electrical insulation properties such as resin. Alternatively, the insulating guide 86 may be made of another insulating material such as ceramic.

[0061] The insulating guide 86 includes a guide main body portion 861 and a guide seal portion 862. The guide main body portion 861 is disposed within the shield 85. The guide seal portion 862 protrudes upward from the shield 85. The guide seal portion 862 is disposed so as to be exposed outside the nozzle unit 6. The outer peripheral surface of the guide seal portion 862 includes a second concave groove 863. The second concave groove 863 extends in the circumferential direction on the outer peripheral surface of the guide seal portion 862. A second O-ring 57 shown in FIG. 5 is disposed in the second concave groove 863. The second O-ring 57 seals the space between the third nozzle 63 and the mounting hole 45. The second O-ring 57 prevents leakage of the shield gas.

[0062] As shown in FIGS. 6 and 7, the nozzle unit 6 includes a first passage 91 and a first air outlet 92. The first passage 91 is formed by the first through hole 64 of the first nozzle 61. As shown in FIG. 5, the first passage 91 is connected to the laser passage 47 within the nozzle pedestal 41. The first air outlet 92 is connected to the first passage 91. The first air outlet 92 is provided at the tip 611 of the first nozzle 61.

[0063] The nozzle unit 6 includes a second passage 93 and a second air outlet 94. The second passage 93 is provided between the first nozzle 61 and the second nozzle 62. Specifically, the second passage 93 is provided between the first tip portion 68 of the first nozzle 61 and the second inlet portion 731, the second intermediate portion 732, and the second outlet portion 733 of the second nozzle 62. The second passage 93 has an annular shape. The second air outlet 94 is connected to the second passage 93. The second air outlet 94 is provided at the tip 621 of the second nozzle 62.

[0064] The nozzle unit 6 includes a third passage 95 and a third air outlet 96. The third passage 95 is provided between the first nozzle 61 and the third nozzle 63, and between the second nozzle 62 and the third nozzle 63. The third passage 95 has an annular shape. Specifically, the third passage 95 is provided between the first main body portion 67 of the first nozzle 61 and the third inlet portion 81 of the third nozzle 63. The third passage 95 is provided between the second main body portion 74 and the third inlet portion 81. As shown in FIG. 11, the corner of the prism portion 77 is in contact with the third inlet portion 81. The third passage 95 is provided in the gap between the side surface of the prism portion 77 and the third inlet portion 81. The third passage 95 is provided between the plurality of grooves 761 of the second nozzle 62 and the third step portion 83. The third passage 95 is provided between the second tip portion 75 and the third outlet portion 82. The third air outlet 96 is connected to the third passage 95. The third air outlet 96 is provided at the tip 631 of the third nozzle 63. The second passage 93 communicates with the third passage 95 through the plurality of holes 780 of the second nozzle 62.

[0065] The first air outlet 92 protrudes downward more than the second air outlet 94. The second air outlet 94 protrudes downward more than the third air outlet 96. FIG. 14 is a view showing the workpiece W1 and the nozzle unit 6 when the workpiece W1 is cut. As shown in FIG. 14, the height H3 of the third air outlet 96 with respect to the workpiece W1 is higher than the height H2 of the second air outlet 94 with respect to the workpiece W1. The height H2 of the second air outlet 94 with respect to the workpiece W1 is higher than the height H1 of the first air outlet 92 with respect to the workpiece W1.

[0066] FIG. 15 is an enlarged cross-sectional view of the vicinity of the first to third air outlets 92, 94, 96 of the nozzle unit 6. As shown in FIG. 15, the inclination angle θ2 of the second outlet portion 733 with respect to the axial direction is larger than the inclination angle θ1 of the first outlet portion 663 with respect to the axial direction. The third outlet portion 82 extends linearly in the axial direction. That is, the inclination angle of the third outlet portion 82 is 0 degrees.

[0067] The laser beam L2 from the laser generator 19 enters from the laser passage 47 into the first passage 91. The laser beam L2 passes through the first passage 91 and is irradiated from the first air outlet 92 toward the workpiece W1. Also, the assist gas enters from the laser passage 47 into the first passage 91. As shown in FIG. 7, the assist gas G1 passes through the first passage 91 and is blown out from the first air outlet 92 toward the workpiece W1.

[0068] The shielding gas enters from the gas passage 48 into the third passage 95. A part of the shielding gas enters from the third passage 95 through the plurality of holes 780 of the second nozzle 62 into the second passage 93 as the inner shielding gas G2. By passing through the plurality of holes 780, the inner shielding gas G2 forms a swirling flow. The inner shielding gas G2 passes through the second passage 93 and is blown out from the second air outlet 94 toward the workpiece W1. The remaining shielding gas passes through the third passage 95 as the outer shielding gas G3. By passing through the plurality of grooves 761, the outer shielding gas G3 forms a swirling flow. The outer shielding gas G3 is blown out from the third air outlet 96 toward the workpiece W1.

[0069] As shown in FIG. 2, the laser processing machine 1 is provided with a nozzle sensor 20. The nozzle sensor 20 detects the height of the first nozzle 61 with respect to the workpiece W1. Specifically, the nozzle sensor 20 detects the capacitance between the first nozzle 61 and the workpiece W1. The controller 36 calculates the height of the first nozzle 61 with respect to the workpiece W1 based on the capacitance. The controller 36 controls the drive device 4 to move the laser head 3 in the height direction based on the height of the first nozzle 61. Hereinafter, the control of the laser processing machine 1 by the controller 36 will be described.

[0070] First, as shown in FIG. 2, the work W1 is placed on the mounting table 11 with the liquid level of the light-shielding liquid L1 being below the mounting table 11. When the controller 36 receives a processing start command from the input device 37, it controls the liquid level adjustment device 5 to raise the liquid level of the light-shielding liquid L1. As shown in FIG. 3, the controller 36 raises the liquid level to a predetermined position above the work W1. Thereby, the work W1 is submerged in the light-shielding liquid L1. For example, the liquid level during processing is at a position several millimeters to a dozen or so millimeters above the work W1. Note that the controller 36 acquires the liquid level based on the signal from the liquid level sensor 34. The controller 36 detects the transmittance of the light-shielding liquid L1 based on the signal from the transmittance sensor 35.

[0071] Next, the controller 36 controls the drive device 4 to move the laser head 3 above the processing start position of the work W1. When the laser head 3 arrives above the processing start position, the controller 36 controls the gas control device 7 to blow out the assist gas G1, the inner shield gas G2, and the outer shield gas G3 from the nozzle unit 6 while lowering the laser head 3 toward the work W1. Thereby, the assist gas G1 and the shield gases G2, G3 are blown onto the surface of the work W1, and as shown in FIG. 4, the light-shielding liquid L1 is removed from the processing range on the surface of the work W1.

[0072] At this time, the flow rate of the inner shield gas G2 from the second blowout port 94 is faster than the flow rate of the outer shield gas G3 from the third blowout port 96. Also, the flow rate of the assist gas G1 from the first blowout port 92 is faster than the flow rate of the inner shield gas G2 from the second blowout port 94.

[0073] Based on the signal from the nozzle sensor 20, the controller 36 acquires the height of the first nozzle 61 from the workpiece W1. The controller 36 lowers the first nozzle 61 to a predetermined height position above the workpiece W1. The controller 36 starts processing the workpiece W1 with the laser beam L2 according to the processing conditions. The controller 36 controls the laser generator 19 to irradiate the workpiece W1 with the laser beam L2 from the laser head 3 to cut the workpiece W1. The controller 36 controls the drive device 4 to move the laser head 3 in the vertical direction (X) and the horizontal direction (Y). Thereby, the workpiece W1 is cut into a shape according to the processing conditions. When the transmittance of the light-shielding liquid L1 is equal to or higher than a predetermined threshold value, the controller 36 may issue an alarm without starting the processing even when receiving a start command.

[0074] When the processing of the workpiece W1 is completed, the controller 36 stops the irradiation of the laser beam L2 and the blowing of the gas. Further, the controller 36 raises the laser head 3 and moves it to a predetermined standby position. The controller 36 lowers the liquid level of the light-shielding liquid L1 to a position below the workpiece W1. Thereby, the cut workpiece W1 can be conveyed from the mounting table 11.

[0075] In the laser processing machine 1 according to the present embodiment described above, the gas blown out from the first to third blowout ports 92, 94, 96 flows between the workpiece W1 and the nozzle unit 6 and toward the outside in the radial direction of the nozzle unit 6. Thereby, the intrusion of the light-shielding liquid into the processing range of the workpiece W1 is effectively suppressed.

[0076] As shown in FIG. 14, the heights H3 of the first to third blowout ports 92, 94, 96 with respect to the workpiece W1 increase in the order of the first to third blowout ports 92, 94, 96. That is, the positions of the first to third blowout ports 92, 94, 96 with respect to the workpiece W1 are stepped up. Therefore, the assist gas G1 and the shield gases G2, G3 generate a gas flow F1 that smoothly flows outward from the center of the nozzle unit 6 along the workpiece W1. Thereby, even if droplets are present directly below the nozzle unit 6, the gas flow F1 easily expels the droplets outward. Thereby, the adhesion of the droplets to the first nozzle 61 can be suppressed. As a result, the change in the capacitance of the first nozzle 61 due to the adhesion of the droplets can be suppressed, and the erroneous detection of the height of the first nozzle 61 can be suppressed.

[0077] The first outlet portion 663 is inclined with respect to the axial direction. Thereby, as shown in FIG. 16, the assist gas G1 flows along the first outlet portion 663, making it difficult for the assist gas G1 to peel off from the first outlet portion 663. The second outlet portion 733 is inclined with respect to the axial direction. Thereby, the inner shield gas G2 flows along the second outlet portion 733, making it difficult for the inner shield gas G2 to peel off from the second outlet portion 733.

[0078] Further, the inclination angle θ2 of the second outlet portion 733 with respect to the axial direction is larger than the inclination angle θ1 of the first outlet portion 663 with respect to the axial direction. Thereby, as shown in FIG. 14, the gas flow F1 smoothly flows from the center of the nozzle unit 6 toward the outside. Thereby, even if droplets are present directly below the nozzle unit 6, the gas flow F1 can easily expel the droplets to the outside. Also, directly below the nozzle unit 6, vortices are likely to be generated by the assist gas G1 and the shield gases G2, G3. This vortex flows so as to lift upward the droplets that tend to move from the inner peripheral side to the outer peripheral side of the nozzle unit 6 on the surface of the workpiece W1 and return them to the inner peripheral side of the nozzle unit 6. However, in the laser processing machine 1 according to the present embodiment, the generation of vortices by the assist gas G1 and the shield gases G2, G3 is suppressed directly below the nozzle unit 6. Thereby, it is difficult for droplets to enter directly below the nozzle unit 6. For example, the inclination angle θ1 of the first outlet portion 663 with respect to the axial direction is less than 3 degrees. The inclination angle θ2 of the second outlet portion 733 with respect to the axial direction is less than 9 degrees.

[0079] The flow velocity of the inner shield gas G2 from the second outlet 94 is faster than the flow velocity of the outer shield gas G3 from the third outlet 96. Also, the flow velocity of the assist gas G1 from the first outlet 92 is faster than the flow velocity of the inner shield gas G2 from the second outlet 94. For example, the flow velocity of the outer shield gas G3 is 120 m / s, the flow velocity of the inner shield gas G2 is 75 m / s, and the flow velocity of the assist gas G1 is 50 m / s. Thereby, for example, the entrainment of droplets in the vicinity of the edge of the workpiece W1 after cutting is suppressed.

[0080] The third nozzle 63 includes a tapered surface 843. Therefore, the space directly below the third nozzle 63 is enlarged as compared with the case where the tapered surface 843 is not present. For example, the inclination angle of the tapered surface 843 with respect to the horizontal direction is greater than 45 degrees. Thereby, as shown in FIG. 14, the velocity of the gas flow F2 flowing backward along the surface of the third nozzle 63 is reduced. As a result, it is suppressed that droplets enter directly below the nozzle unit 6 due to the gas flow F2 flowing backward.

[0081] In the third nozzle 63, a round edge is provided at the corner between the tapered surface 843 and the tip 631 of the third nozzle 63. For example, the radius of the round edge is greater than 1 mm. Thereby, at the corner between the tapered surface 843 and the tip 631 of the third nozzle 63, a sudden change in the velocity of the reverse-flowing gas stream F2 is suppressed. As a result, the intrusion of droplets under the nozzle unit 6 by the reverse-flowing gas stream F2 is suppressed.

[0082] The third nozzle 63 has a triple structure including an outer cap 84, a shield 85, and an insulating guide 86. As shown in FIG. 17, the shield 85 suppresses the false detection of the change in the capacitance C2 due to the change in the position of the light-shielding liquid L1 as the change in the capacitance C1 between the first nozzle 61 and the workpiece W1. Further, the shield 85 is covered by the outer cap 84 which is an insulator and the insulating guide 86. Thereby, the adhesion of droplets to the shield 85 is suppressed. As a result, the false detection of the height of the first nozzle 61 is suppressed.

[0083] Also, since the outer cap 84 is made of ceramic, the resistance to sputtering generated during cutting by laser is improved. Since the insulating guide 86 is made of resin, the adhesion to the nozzle pedestal 41 is improved. Thereby, the leakage of the shielding gas is suppressed.

[0084] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0085] The configuration of the laser processing machine 1 is not limited to that of the above embodiment and may be changed. For example, in the above embodiment, the laser processing machine 1 cuts the workpiece W1 with laser light. However, the laser processing machine 1 may weld the workpiece W1 with laser light.

[0086] The laser generator 19 may be not limited to a fiber laser, but may be a solid laser such as a YAG laser, or other types of lasers such as a carbon dioxide laser. The configuration of the liquid level adjusting device 5 is not limited to that of the above-described embodiment and may be changed. For example, the liquid level adjusting device 5 may change the liquid level by controlling the supply amount of the light-shielding liquid L1 to the liquid storage tank 2.

[0087] The configuration of the nozzle unit 6 is not limited to that of the above-described embodiment and may be changed. For example, the dimensions of each part of the nozzle unit 6 described above are illustrative and not limited thereto.

[0088] In the above-described embodiment, the inclination angle of the third outlet portion 82 of the third passage 95 is 0 degrees. However, as in the first modification shown in FIG. 18, the third outlet portion 82 may be inclined with respect to the axial direction. For example, the inclination angle θ3 of the third outlet portion 82 with respect to the axial direction may be less than 9 degrees.

[0089] In the above-described embodiment, the outer peripheral side of the first tip portion 68 of the first nozzle 61 extends linearly in the axial direction. However, as in the second modification shown in FIG. 19, the first tip portion 68 may be inclined with respect to the axial direction. The first tip portion 68 may be inclined so as to expand in the radial direction toward the tip 611 of the first nozzle 61. Thereby, since the inner shield gas G2 flows along the first tip portion 68, the inner shield gas G2 is difficult to peel off from the first tip portion 68. For example, the inclination angle of the first tip portion 68 may be the same as the inclination angle of the second outlet portion 733.

[0090] In the above-described embodiment, the second tip portion 75 of the second nozzle 62 extends linearly in the axial direction. However, as shown in FIG. 19, the second tip portion 75 may be inclined with respect to the axial direction. The second tip portion 75 may be inclined so as to expand in the radial direction toward the tip 621 of the second nozzle 62. Thereby, since the outer shield gas G3 flows along the second tip portion 75, the outer shield gas G3 is difficult to peel off from the second tip portion 75. For example, the inclination angle of the second tip portion 75 may be the same as the inclination angle of the third outlet portion 82.

[0091] The shapes of the first to third passages 91, 93, and 95 are not limited to those of the above-described embodiment and may be changed. For example, as in the third modification shown in FIG. 20, the second passage 93 may have a curved shape such that the second air outlet 94 faces outward in the radial direction. The third passage 95 may have a curved shape such that the third air outlet 96 faces outward in the radial direction. In this case, the space where the gas flows backward toward the nozzle unit 6 is reduced. Thereby, the intrusion of droplets directly below the nozzle unit 6 is further suppressed.

Industrial Applicability

[0092] According to the present invention, in a laser processing machine, the intrusion of the light-shielding liquid into the processing range of the workpiece can be effectively suppressed. Thereby, the processing quality of the workpiece is improved.

Explanation of Reference Numerals

[0093] 2: Liquid storage tank, 6: Nozzle unit, 3: Laser head, 4: Driving device, 11: Mounting table, 19: Laser generator, 20: Nozzle sensor, 36: Controller, 61: First nozzle, 62: Second nozzle, 63: Third nozzle, 82: Third outlet portion, 91: First passage, 92: First air outlet, 93: Second passage, 94: Second air outlet, 95: Third passage, 96: Third air outlet, 663: First outlet portion, 733: Second outlet portion, L1: Light-shielding liquid

Claims

1. A nozzle unit for a laser processing machine that processes a workpiece disposed in a light-shielding liquid having light-shielding properties with a laser beam, A first nozzle including a first passage through which the laser beam and the assist gas pass, and a first outlet through which the assist gas is blown out toward the workpiece and connected to the first passage, A second nozzle disposed outside the first nozzle, A second passage provided between the first nozzle and the second nozzle through which an inner shield gas passes, A second outlet connected to the second passage and blowing out the inner shield gas toward the workpiece to remove the light-shielding liquid from between the first nozzle and the workpiece, A third nozzle disposed outside the second nozzle, A third passage provided between the second nozzle and the third nozzle through which an outer shield gas passes, A third outlet connected to the third passage and blowing out the outer shield gas toward the workpiece to remove the light-shielding liquid from between the first nozzle and the workpiece, comprising, The height of the third outlet with respect to the workpiece is higher than the height of the second outlet with respect to the workpiece, The height of the second outlet with respect to the workpiece is higher than the height of the first outlet with respect to the workpiece, Nozzle unit.

2. The second nozzle is an insulator, The nozzle unit according to claim 1.

3. The third nozzle is A conductive shield, An insulator covering the shield, including, The nozzle unit according to claim 1.

4. The first passage includes a first outlet portion inclined to expand radially toward the first outlet, The nozzle unit according to claim 1.

5. The second passage includes a second outlet portion inclined so as to expand in the radial direction toward the second blowout port. The nozzle unit according to claim 1.

6. The third passage includes a third outlet portion inclined so as to expand in the radial direction toward the second blowout port. The nozzle unit according to claim 1.

7. The first passage includes a first outlet portion inclined so as to expand in the radial direction toward the first blowout port. The second passage includes a second outlet portion inclined so as to expand in the radial direction toward the second blowout port. The inclination angle of the second outlet portion with respect to the axial direction of the first nozzle is larger than the inclination angle of the first outlet portion with respect to the axial direction. The nozzle unit according to claim 1.

8. A liquid storage tank for storing the light-shielding liquid, A mounting table disposed in the liquid storage tank on which the workpiece is placed, A laser generator for generating the laser light, A laser head connected to the laser generator and disposed above the mounting table, A driving device for moving the laser head, The nozzle unit according to any one of claims 1 to 7 attached to the laser head, A laser processing machine comprising the same.

9. A sensor for detecting the capacitance between the first nozzle and the workpiece, A controller for calculating the height of the first nozzle with respect to the workpiece based on the capacitance and controlling the driving device to move the laser head in the height direction, The laser processing machine according to claim 8, further comprising the same.

10. The flow velocity of the inner shield gas from the second gas outlet is faster than the flow velocity of the outer shield gas from the third gas outlet. The laser processing machine according to claim 8.

11. The flow velocity of the assist gas from the first gas outlet is faster than the flow velocity of the inner shield gas from the second gas outlet. The laser processing machine according to claim 8.

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