JP5944963B2 - Laser processing head and laser processing machine - Google Patents

Description

  The present invention relates to a laser processing head or the like connected to an output end of a transmission fiber for transmitting laser light oscillated from a laser oscillator such as a fiber laser oscillator.

  The configuration of a laser processing head used in a laser processing machine such as a fiber laser processing machine will be briefly described as follows.

  The laser processing head includes a cylindrical processing head main body, and the processing head main body has a fiber holding portion (fiber holder) that holds the output end of the transmission fiber on the base end side. Further, the processing head main body has a nozzle capable of irradiating a laser beam and injecting an assist gas on the tip side, and the inside of the processing head main body can be connected to an assist gas supply source. A collimating lens is provided in the processing head main body, and this collimating lens converts laser light emitted from the emission end of the transmission fiber into parallel light. Further, a condensing lens is provided between the collimating lens and the nozzle in the processing head main body, and this condensing lens condenses the laser light converted into parallel light.

  Therefore, by operating the fiber laser oscillator and emitting laser light from the exit end of the transmission fiber, the laser light is converted into parallel light by the collimator lens, condensed by the condenser lens, and collected from the nozzle to the workpiece. Laser light is irradiated toward the cut portion. Further, simultaneously with the irradiation with the laser beam, the assist gas is supplied from the assist gas supply source to the inside of the processing head main body, whereby the assist gas is jetted from the nozzle toward the workpiece to be cut. Thereby, it is possible to cut the workpiece while melting the portion to be cut of the workpiece and removing the melt using the energy of the laser beam. A series of cutting processes can be performed on a plurality of workpieces by continuously repeating the above-described operation.

  Here, the processing mode of the cutting process can be divided into a non-oxidizing process (inert gas process) using an inert gas such as nitrogen as an assist gas and an oxygen process using oxygen as an assist gas. Non-oxidation processing can melt the workpiece only by the energy of the laser beam and prevent the cut surface of the workpiece from being oxidized. The workpiece is made of a thin plate of stainless steel, copper, aluminum, mild steel or the like having a thickness of 3 mm or less. Suitable for high speed cutting. Oxygen processing can melt a workpiece by oxidation reaction heat in addition to laser beam energy, and is suitable for cutting a workpiece made of a thick plate of mild steel having a thickness of, for example, 6 mm or more. In addition, a general-purpose condenser lens is used for non-oxidation processing, whereas in the case of oxygen processing, a ring-shaped laser beam (ring beam) can be formed to prevent burning (abnormal combustion). A special condensing lens incorporating a special axicon lens is used (see Patent Document 1 and Patent Document 2).

  In addition to Patent Literature 1 and Patent Literature 2, there are those shown in Patent Literature 3 as prior art related to the present invention.

JP 2013-75331 A WO2010 / 095744 A1 JP 2000-227576 A

  By the way, during a series of cutting processes, the processing form may be changed from non-oxidation processing to oxygen processing or from oxygen processing to non-oxidation processing for reasons such as changing the workpiece to be processed. In such a case, it is necessary to replace the laser processing machine, for example, by temporarily cutting the cutting process and changing from a general-purpose condenser lens to a special condenser lens. Therefore, a series of cutting processes are complicated, the work efficiency is lowered, and the interruption time of the cutting process becomes long, so that the productivity of the cutting process cannot be sufficiently increased.

  Accordingly, an object of the present invention is to provide a laser processing head or the like having a novel configuration that can solve the above-described problems.

In order to solve the above-mentioned problems, the inventor of the present invention has repeated trial and error, and as a result, an outer layer portion of the laser beam is formed by an aperture provided between the output end of the transmission fiber and the collimating lens in the processing head body. By cutting off under a proper cutting rate, burning can be prevented for workpieces made of mild steel with a thickness of 6 mm or more without using a special condensing lens incorporating an axicon lens. In addition to cutting by oxygen processing, new knowledge is obtained that high-speed cutting by non-oxidation processing can be performed on workpieces made of thin plates of stainless steel, copper, aluminum, mild steel, etc., for example, a thickness of 3 mm or less The present invention has been completed. This is a low energy that does not contribute to melting (cutting) of the workpiece in the outer layer of the laser beam, in other words, the laser beam, after sufficiently securing the power intensity of the laser beam in the workpiece cut portion as a processing point. This is considered to be due to the fact that this part was suppressed from irradiating the cut part of the workpiece. Here, the appropriate cut rate by the aperture means 2 to 10%.

  According to a first aspect of the present invention, in a laser processing head connected to an output end of a transmission fiber for transmitting laser light oscillated from a laser oscillator, a fiber holding portion (fiber A cylindrical machining head main body having a holder), a nozzle capable of irradiating a laser beam on the tip side and capable of injecting an assist gas, and having an inside that can be connected to an assist gas supply source, and the inside of the machining head main body A collimating lens that converts laser light emitted from the exit end of the transmission fiber into parallel light, and is provided between the collimating lens and the nozzle in the processing head body, and is converted into parallel light. A condensing lens for condensing laser light, and provided between the fiber holder and the collimating lens in the processing head main body; An aperture that has a circular opening for transmitting light, and that blocks (cuts) an outer layer portion (portion located on the outer peripheral side) of the laser light emitted from the emission end of the transmission fiber; The inner peripheral surface of the aperture has a tapered shape in which the inner diameter of the aperture gradually increases toward the traveling direction of laser light, and the taper angle of the inner peripheral surface of the aperture is determined by the opening of the aperture. The gist is that the angle is set to be larger than the spread angle of the transmitted laser beam.

  Here, in the specification and claims of the present application, "holding" means not only holding directly but also holding indirectly through another member, The phrase “provided” means that it is indirectly provided through another member in addition to being directly provided. In addition, the “inner diameter of the aperture” means the minimum inner diameter when the inner diameter of the aperture changes along the optical axis direction. Furthermore, “the laser beam cut rate by the aperture” refers to the ratio of the power intensity of the laser light blocked (cut) by the aperture to the power intensity of the laser light emitted from the exit end of the transmission fiber.

  According to the first feature of the present invention, the laser oscillator is operated to emit laser light from the exit end of the transmission fiber, whereby the outer layer portion of the laser light is blocked by the aperture, and then the laser Light is converted into parallel light by the collimating lens, condensed by the condensing lens, and irradiated with laser light from the nozzle toward the cut portion of the workpiece. Simultaneously with the irradiation of the laser beam, the assist gas is supplied from the assist gas supply source to the inside of the processing head main body, whereby the assist gas is jetted from the nozzle toward the workpiece to be cut. Thereby, it is possible to cut the workpiece while melting the portion to be cut of the workpiece and removing the melt using the energy of the laser beam. A series of cutting processes can be performed on a plurality of workpieces by continuously repeating the above-described operation.

  Applying the above-mentioned new knowledge, without using a special condensing lens, the workpiece made of a thick steel plate with a thickness of, for example, 6 mm or more is cut by oxygen processing while preventing burning, and stainless steel High-speed cutting by non-oxidation processing can be performed on a workpiece made of a thin plate having a thickness of, for example, 3 mm or less. Thereby, it is possible to change the processing mode of the cutting process from the non-oxidation process to the oxygen process or from the oxygen process to the non-oxidation process without changing the setup of the laser processing machine during a series of cutting processes.

  The second feature of the present invention is that the inner diameter of the aperture is set so that a cut rate of laser light by the aperture is 2 to 10%.

  According to the 2nd characteristic of this invention, there exists an effect | action similar to the effect | action by the 1st characteristic of this invention.

  According to the present invention, the processing mode of the cutting process is changed from non-oxidation processing to oxygen processing or from oxygen processing to non-oxidation processing without performing setup change of the laser processing machine during a series of cutting processing. Therefore, the complexity of the cutting process can be suppressed, the work efficiency can be improved, the interruption time of the cutting process can be minimized, and the productivity of the cutting process can be sufficiently increased.

FIG. 1 is a sectional view of a laser processing head according to an embodiment of the present invention, and also shows a part of a processing table. FIG. 2 is an enlarged view of the arrow II in FIG. FIG. 3 is a perspective view of the fiber laser processing machine according to the embodiment of the present invention. 4 (a) and 4 (b) are photographic views showing a burn pattern formed by irradiating an acrylic plate with laser light. FIG. 4 (a) shows a case where no aperture is attached to the laser processing head. FIG. 4B shows a case where an aperture is attached to the laser processing head. FIGS. 5 (a) and 5 (b) are photographic views showing a cut piece taken out by cutting by oxygen processing of a workpiece made of a thick steel plate having a thickness of, for example, 6 mm or more, and FIG. 5 (a) is a laser processing. FIG. 5B shows the case where the aperture is not attached to the head, and FIG. 5B shows the case where the aperture is attached to the laser processing head. FIG. 6 is a diagram showing the results of a laser beam reflection test performed when the aperture is mounted (Invention Examples 1 and 2) and when no aperture is mounted (Comparative Examples 1 and 2).

  An embodiment of the present invention will be described with reference to FIGS. 1 to 3.

  As shown in FIG. 3, the fiber laser processing machine 1 according to the embodiment of the present invention uses the laser light LB having a wavelength of 1 μm band oscillated from the fiber laser oscillator 3 to cut the workpiece W. It is a device to perform. Here, the configuration of the fiber laser oscillator 3 is, for example, a known configuration as shown in Japanese Patent Application Laid-Open No. 2012-24778.

  The fiber laser processing machine 1 includes a processing table (support frame) 5 that supports the workpiece W in addition to the fiber laser oscillator 3, and the processing table 5 extends in the X-axis direction (front-rear direction). And a plurality of support portions (not shown) for supporting the workpiece W by point contact, and clamp members (not shown) for fixing the workpiece W to the multiple support portions. Further, a gate-shaped X-axis movable frame 7 is provided on the machining table 5 so as to be movable in the X-axis direction via an X-axis guide rail (not shown) extending in the X-axis direction. The frame 7 is moved in the X-axis direction by driving an X-axis servomotor (not shown). Further, a Y-axis carriage 9 is provided on the horizontal portion 7a of the X-axis movable frame 7 so as to be movable in the Y-axis direction via a Y-axis guide rail (not shown) extending in the Y-axis direction. The shaft carriage 9 is moved in the Y-axis direction by driving a Y-axis servo motor (not shown).

  A laser processing head 11 is provided on the Y-axis carriage 9 so as to be movable in the Z-axis direction via a Z-axis guide rail (not shown) extending in the Z-axis direction (vertical direction). The laser processing head 11 moves in the Z-axis direction by driving a Z-axis servo motor (not shown), and moves in the X-axis direction integrally with the X-axis movable frame 7 by driving the X-axis servo motor. The Y-axis servo motor is driven to move integrally with the Y-axis carriage 9 in the Y-axis direction. Furthermore, the laser processing head 11 is connected to an emission end 13e of a transmission fiber (process fiber) 13 for transmitting the laser beam LB oscillated from the fiber laser oscillator 3. The specific configuration of the laser processing head 11 is as follows.

  As shown in FIGS. 1 and 2, the laser processing head 11 includes a cylindrical (hollow) processing head main body 15, and the processing head main body 15 includes a cylindrical upper processing head main body 17, A cylindrical lower processing head main body 19 provided detachably on the lower side of the upper processing head main body 17 and an annular jacket 21 provided detachably on the upper side of the upper processing head main body 17 are provided. . Further, on the upper side of the jacket 21, a fiber holder 25 as a fiber holding portion for holding the emission end 13e of the transmission fiber 13 via the connector 23 is detachably provided. In other words, the processing head main body 15 is The fiber holder 25 is provided on the base end side (upper end side).

  At the lower end of the lower processing head main body 19, there is provided a nozzle 27 capable of irradiating the laser beam LB and injecting an assist gas. In other words, the processing head main body 15 has a nozzle on the tip side (lower end side). 27. Further, the inside of the lower machining head main body 19 is connected to a gas cylinder 31 as an assist gas supply source via a gas supply pipe 29 and the like. Note that the gas cylinder 31 can be appropriately replaced according to the processing mode of the cutting process.

  A cylindrical upper lens holder 33 is detachably provided in the upper processing head main body 17. The collimating lens 35 is detachably held in the upper lens holder 33. In other words, the collimating lens 35 is detachably provided in the processing head main body 15 via the upper lens holder 33. The collimating lens 35 converts the laser light LB emitted from the emission end 13e of the transmission fiber 13 into parallel light. Here, the position of the collimating lens 35 in the optical axis direction (Z-axis direction) is set so that the focal position of the collimating lens 35 coincides with the position of the emission end 13 e of the transmission fiber 13.

  A cylindrical lower lens holder 37 is detachably provided in the lower processing head main body 19. Further, a condensing lens 39 is detachably held in the lower lens holder 37. In other words, the condensing lens 39 is provided between the collimating lens 35 and the nozzle 27 in the processing head main body 15. A condensing lens 39 is provided so as to be detachable via the lower lens holder 37, and condenses the laser light LB converted into parallel light.

  An aperture 41 is detachably provided on the inner side of the jacket 21, in other words, between the fiber holder 25 and the collimating lens 35 in the processing head body 15, and the aperture 41 extends from the output end 13 e of the transmission fiber 13. The outer layer portion (portion located on the outer peripheral side) LBo of the emitted laser beam LB is blocked (cut). The aperture 41 is made of a material having high thermal conductivity and has a circular opening 41a for transmitting the laser beam LB. The material having high thermal conductivity refers to, for example, aluminum, aluminum alloy, copper, or copper alloy.

  The inner peripheral surface 41i of the aperture 41 has a tapered shape in which the inner diameter of the aperture 41 gradually increases toward the traveling direction of the laser beam LB (collimating lens 35 side). Further, the taper angle θ1 of the inner peripheral surface 41i of the aperture 41 is set to an angle larger than the spread angle θ2 of the laser beam (laser beam emitted from the aperture 41) LB that passes through the opening 41a of the aperture 41. . The minimum inner diameter D of the inner peripheral surface 41i of the aperture 41 is set so that the cut rate (cutoff rate) of the laser beam LB by the aperture 41 is 2 to 10%, preferably 3 to 8%. The reason why the cut rate of the laser beam LB by the aperture 41 is 2% or more is that if it is less than 2%, it contributes to the outer layer portion LBo of the laser beam LB, in other words, melting (cutting) in the laser beam LB. This is because it becomes difficult to sufficiently suppress the low-energy portion that is not irradiated to the cut portion Wa of the workpiece W, and for example, burning or the like occurs during oxygen processing of a mild steel thick plate. On the other hand, the cut rate of the laser beam LB by the aperture 41 is set to 10% or less. If the cut rate exceeds 10%, the power intensity of the laser beam LB at the cut portion Wa of the workpiece W as a processing point decreases. This is because, for example, the cutting speed during the non-oxidation processing of a stainless steel sheet cannot be maintained at a high speed, and the cutting speed needs to be considerably reduced, which decreases productivity. A cut rate (2 to 10%) is required to achieve both oxidation processes. Note that the cut rate of the laser beam LB by the aperture 41 is preferably 3% or more and 8% or less, particularly in the case of non-oxidation processing, such as copper, copper alloy, aluminum, aluminum alloy, or mirror-finished stainless steel. When cutting a workpiece W made of a thin plate of a highly reflective material, the reflected light LB ′ toward the laser processing head 11 is sufficiently reduced, and the cutting speed is reduced to maintain productivity. Because.

  An annular reflection groove 41s having a substantially V-shaped cross section is formed on the surface of the aperture 41 on the fiber holder 25 side. In other words, the cross section of the peripheral portion 41m of the opening 41a of the aperture 41 on the fiber holder 25 side. Has an acute angle shape. Further, the taper angle θ3 of the inner reflection surface 41si of the reflection groove 41s of the aperture 41 is set to be larger than the taper angle θ4 of the outer reflection surface 41so. The portion 21 i on the fiber holder 25 side on the inner peripheral surface of the jacket 21 has a tapered shape in which the inner diameter of the jacket 21 gradually decreases toward the emission end 13 e side of the transmission fiber 13.

  An annular cooling water passage 43 for circulating cooling water is formed between the inner peripheral surface of the jacket 21 and the outer peripheral surface of the aperture 41. The cooling water passage 43 is connected to a chiller (cooling water circulation device) 49 that circulates the cooling water through a cooling water supply pipe 45 and a cooling water discharge pipe 47. A plurality of O-rings 51 for preventing water leakage from the cooling water passage 43 are provided at appropriate positions between the inner peripheral surface of the jacket 21 and the outer peripheral surface of the aperture 41.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  The laser processing head 11 is moved in the Z-axis direction by driving the Z-axis servo motor to adjust the focal position of the laser beam LB. Then, by operating the fiber laser oscillator 3 and emitting the laser beam LB from the emission end 13e of the transmission fiber 13, the outer layer portion LBo of the laser beam LB is blocked by the aperture 41, and then the laser beam LB is emitted. The light is converted into parallel light by the collimating lens 35, condensed by the condensing lens 39, and irradiated with the laser light LB from the nozzle 27 toward the cut portion Wa of the work W. Further, the assist gas is injected from the nozzle 27 toward the cut portion Wa of the workpiece W by supplying the assist gas from the gas cylinder 31 to the inside of the lower machining head main body 19. Further, in a state where the laser beam LB is emitted from the nozzle 27 and the assist gas is jetted, the laser processing head 11 is cut into the workpiece W by driving at least one of the X-axis servo motor and the Y-axis servo motor. It is moved along at least one of the X-axis direction and the Y-axis direction along the portion Wa. Accordingly, the workpiece W can be cut while melting the portion to be cut Wa of the workpiece W and removing the melt using the energy of the laser beam LB condensed at high density. . A series of cutting processes can be performed on a plurality of workpieces W by repeating the above-described operation continuously.

  Since the minimum inner diameter D of the aperture 41 is set so that the cut rate of the laser beam LB by the aperture 41 is 2 to 10%, the above-described new knowledge can be applied without using a special condensing lens. The workpiece W made of a thick steel plate having a thickness of, for example, 6 mm or more is cut by oxygen processing while preventing burning, and the workpiece W made of a thin plate having a thickness of, for example, 3 mm or less such as stainless steel is not oxidized. High-speed cutting can be performed while maintaining productivity by processing (nitrogen processing). Thereby, it is possible to change the processing mode of the cutting process from the non-oxidizing process to the oxygen process or from the oxygen process to the non-oxidizing process without performing the setup change of the fiber laser processing machine 1 in the middle of the series of cutting processes. .

  Since the minimum inner diameter D of the aperture 41 is set so that the cut rate of the laser beam LB by the aperture 41 is preferably 3% or more, the workpiece W is made of a thin plate made of a highly reflective material, and there is no cutting form. Even in the case of oxidation processing, the low-energy portion of the laser beam LB is suppressed from being irradiated to the cut portion Wa of the workpiece W, and the reflected light LB ′ toward the laser processing head 11 is sufficiently reduced. can do.

  Since the taper angle θ1 of the inner peripheral surface 41i of the aperture 41 is set to be larger than the spread angle θ2 of the laser beam LB that passes through the opening 41a of the aperture 41, the laser beam LB passes through the opening 41a of the aperture 41. It is possible to avoid interference with the inner peripheral surface 41 i of the aperture 41 during transmission.

  In the aperture 41, the cross section of the peripheral portion 41m of the opening 41a on the fiber holder 25 side has an acute shape, and the taper angle θ3 of the inner reflection surface 41si of the reflection groove 41s of the aperture 41 is larger than the taper angle θ4 of the outer reflection surface 41so. Since the region 21 i on the fiber holder 25 side on the inner peripheral surface of the jacket 21 has a tapered shape as described above, the outer layer portion LBo of the laser light LB blocked by the aperture 41 is emitted from the transmission fiber 13. Reflection to the end 13e side can be avoided.

  During cutting of the workpiece W, the chiller 49 is operated to circulate the cooling water in the cooling water passage 43, so that the aperture 41 can be cooled with water, and the temperature rise of the aperture 41 can be suppressed.

  Therefore, according to the embodiment of the present invention, the processing mode of the cutting process is changed from non-oxidation processing to oxygen processing or from oxygen processing without changing the setup of the fiber laser processing machine 1 during a series of cutting processing. Since it can be changed to oxidation processing, it is possible to improve the work efficiency by reducing the complexity of the work of the cutting process, and to improve the productivity of the cutting process by eliminating the interruption time of the cutting process as much as possible. it can.

  In addition, since the laser beam LB can be prevented from interfering with the inner peripheral surface 41i of the aperture 41 when passing through the opening 41a of the aperture 41, the beam quality of the laser beam LB is stabilized and the accuracy of the cutting process is improved. Improvements can be made.

  Further, even when the workpiece W is made of a thin plate made of a highly reflective material and the processing mode of the cutting process is non-oxidizing, the reflected light LB ′ toward the laser processing head 11 can be sufficiently reduced. Further, it is possible to sufficiently prevent the collimating lens 35 and the emitting end 13e of the transmission fiber 13 from being burned out. In particular, the aperture 41 blocks the reflected light LB ′, and the outer layer portion LBo of the laser light LB blocked by the aperture 41 can be prevented from being reflected toward the output end 13e of the transmission fiber 13, so that the output end of the transmission fiber 13 can be avoided. 13e can be prevented more sufficiently.

  The present invention is not limited to the description of the above-described embodiment. For example, a technical idea applied to the fiber laser processing machine 1 is a YAG laser processing machine that transmits laser light through a transmission fiber, a solid state The present invention can be implemented in various other modes such as application to a laser beam machine, a carbonic acid laser beam machine, and the like. Further, the scope of rights encompassed by the present invention is not limited to the above-described embodiment.

  An embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b) to FIG.

  When the laser processing head is irradiated with laser light from the nozzle of the laser processing head without forming an aperture on the laser processing head to form a burn pattern on the acrylic plate, as shown in FIG. It was confirmed that the outer layer portion of the laser beam was included. On the other hand, when a laser beam is irradiated to the acrylic plate from the nozzle of the laser processing head with an aperture (laser light cut rate 7%) attached to the laser processing head, and a burn pattern is formed on the acrylic plate, As shown in FIG. 4B, it was confirmed that the outer layer portion of the mist-like laser beam was cut from the burn pattern.

  When a workpiece made of a thick steel plate having a thickness of 10 mm is cut by oxygen processing without attaching an aperture to the laser processing head, and a cut piece is taken out from the workpiece, as shown in FIG. It was confirmed that burning occurred. In contrast, with a laser processing head fitted with an aperture (laser beam cut rate of 7%), a workpiece made of a 10 mm thick steel plate is cut by oxygen processing and cut from the workpiece. When the piece was taken out, it was confirmed that burning could be prevented as shown in FIG.

When the aperture is not attached to the laser processing head (in the case of Comparative Examples 1 and 2), and when the aperture (the laser light cut rate is 7%) is attached to the laser processing head (in the case of Invention Examples 1 and 2), copper When a laser beam reflection test was performed on a workpiece made of an alloy, results as shown in FIG. 6 could be obtained. That is, it was confirmed that the reflected light level can be significantly reduced in the case of Invention Examples 1 and 2 as compared with the case of Comparative Examples 1 and 2. In Comparative Example 1 and Inventive Example 1, the focal position of the laser beam is set to be higher by 0.5 mm than the upper surface of the workpiece. In Comparative Example 2 and Inventive Example 2, the focal point of the laser beam is set. The position was set to be 0.5 mm deeper than the upper surface of the workpiece.

LB Laser light LBo Outer layer portion LB ′ Reflected light W Work Wa Cut part 1 Fiber laser processing machine 3 Fiber laser oscillator 5 Processing table 11 Laser processing head 13 Transmission fiber 13e Output end 15 Processing head main body 17 Upper processing head main body 19 Lower processing Head body 21 Jacket 23 Connector 25 Fiber holder 27 Nozzle 29 Gas supply pipe 31 Gas cylinder 33 Upper lens holder 35 Collimating lens 37 Lower lens holder 39 Condensing lens 41 Aperture 41a Opening 41i Inner peripheral surface 41m Edge 43 Cooling water passage

Claims (4)

In the laser processing head connected to the output end of the transmission fiber for transmitting the laser light oscillated from the laser oscillator,
It has a fiber holding portion that holds the emission end of the transmission fiber, a nozzle that can irradiate laser light and inject assist gas on the tip side, and has a cylindrical shape that can be connected to an assist gas supply source. A processing head body;
A collimating lens that is provided in the processing head body and converts the laser light emitted from the exit end of the transmission fiber into parallel light;
A condensing lens that is provided between the collimating lens and the nozzle in the processing head main body and condenses the laser light converted into parallel light;
An outer layer of laser light emitted from the exit end of the transmission fiber, which is provided between the fiber holding part and the collimating lens in the processing head main body, has a circular opening for transmitting laser light. An aperture for blocking the portion,
The inner peripheral surface of the aperture has a tapered shape in which the inner diameter of the aperture gradually increases toward the traveling direction of laser light, and the taper angle of the inner peripheral surface of the aperture is determined by the opening of the aperture. The surface on the side of the fiber holding part in the aperture is set to an angle larger than the spread angle of the laser beam to be transmitted, and the cross section of the peripheral part on the side of the fiber holding part of the opening in the aperture has an acute shape. A laser processing head characterized in that an annular reflection groove having a V-shaped cross section is formed in the laser processing head. The laser processing head according to claim 1 , wherein a cooling water passage for circulating cooling water is formed between an inner peripheral surface of the processing head main body and an outer peripheral surface of the aperture. The laser oscillator, the laser processing head according to claim 1 or claim 2, characterized in that a fiber laser oscillator that oscillates laser light having a wavelength of 1μm band. In a laser processing machine that uses the energy of laser light oscillated from a laser oscillator to cut a workpiece,
A laser processing machine comprising the laser processing head according to any one of claims 1 to 3 .