Method for manufacturing a workpiece, workpiece, and processing device

Abstract

To provide a method for manufacturing workpiece which can improve surface strength while suppressing curvature.SOLUTION: A method for manufacturing workpiece includes: preparing a processing object 10 containing metal; and forming a plurality of first regions α and a second region β on a surface 10a of the processing object 10 by irradiation with a laser beam L. A tensile residual stress is imparted to the plurality of first regions α. In the second region β, a plurality of irradiation parts P separated from one another on the surface 10a of the processing object 10 are irradiated with the laser beam L to which a compressive residual stress is imparted. Each of the first regions α is formed so as to be separated from one another and be surrounded by the second region β when being viewed from a direction perpendicular to the surface 10a.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a workpiece, a workpiece, and a processing device. [Background technology]

[0002] Laser peening is a known method for processing the surface of a metal-containing workpiece (see, for example, Patent Document 1). In Patent Document 1, compressive residual stress is imparted to the workpiece by irradiating the surface of the workpiece with laser light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2003 / 0024915 Summary of the Invention [Problem to be solved by the invention]

[0004] Irradiation of a workpiece with laser light can cause plastic deformation in the workpiece. This plastic deformation imparts compressive residual stress to the workpiece. The application of compressive residual stress improves the strength of the workpiece. However, when plastic deformation is induced in the workpiece, metal flow occurs around the area where plastic deformation occurs. The cumulative effect of the metal flow causes the workpiece to bend after laser peening.

[0005] An object of one aspect of the present invention is to provide a method for manufacturing a workpiece in which the surface strength can be improved while curvature is suppressed.Another object of the present invention is to provide a workpiece in which the surface strength can be improved while curvature is suppressed.Another object of the present invention is to provide a processing device in which the surface strength of the workpiece can be improved while curvature of the workpiece is suppressed. [Means for solving the problem]

[0006] A method for manufacturing a workpiece according to one aspect of the present invention includes preparing a workpiece containing metal and forming a plurality of first regions and a second region along the surface of the workpiece by irradiating the workpiece with laser light. Tensile residual stress is imparted to the plurality of first regions. Compressive residual stress is imparted to the second region. The laser light is irradiated to a plurality of irradiation points spaced apart from one another on the surface of the workpiece. When viewed from a direction perpendicular to the surface, the first regions are formed so as to be spaced apart from one another and surrounded by the second region.

[0007] In one aspect of the present invention, the first regions to which tensile residual stress is applied are spaced apart from one another and surrounded by the second regions to which compressive residual stress is applied when viewed from a direction perpendicular to the surface. In this case, curvature can be suppressed by the influence of the first regions to which tensile residual stress is applied, while the compressive residual stress can improve the surface strength. Therefore, a workpiece can be manufactured that has improved surface strength while suppressing curvature.

[0008] In one aspect of the present invention, the laser beam may be irradiated onto a plurality of irradiation locations so that plastically deformed regions are formed at positions corresponding to the respective irradiation locations. The plastically deformed regions corresponding to the respective irradiation locations may be formed so as not to overlap with adjacent plastically deformed regions. In this case, curvature of the workpiece is further suppressed.

[0009] In one aspect of the present invention, the laser beam may be irradiated onto a plurality of irradiation locations so that metal flow regions are formed at positions corresponding to the respective irradiation locations. The metal flow regions corresponding to the respective irradiation locations may be irradiated so as to overlap with adjacent metal flow regions. In this case, metal flow occurs in the adjacent metal flow regions in directions facing each other, further improving compressive residual stress between the adjacent irradiation locations.

[0010] In one of the above aspects, the laser light may be irradiated simultaneously to the multiple irradiation locations. In this case, metal flow due to the irradiation of the laser light occurs simultaneously at positions corresponding to each irradiation location. Since metal flow simultaneously occurs in the adjacent metal flow regions in directions facing each other, compressive residual stress is further improved between the adjacent irradiation locations. Furthermore, the influence of metal flow in each metal flow region is offset by the metal flow in the adjacent metal flow region. Therefore, curvature of the workpiece due to metal flow is suppressed.

[0011] In the above-described one aspect, the object may include at least one of titanium and a titanium alloy. In this case, the thermal conductivity of the object is suppressed. As a result, a balance is achieved between the ratio of the first region to which tensile residual stress is imparted to the second region to which compressive residual stress is imparted.

[0012] In another aspect of the present invention, a workpiece includes a processed portion, the processed portion having a plurality of first regions containing metal and having tensile residual stress and a second region having compressive residual stress formed along a surface thereof, the plurality of first regions being spaced apart from one another and surrounded by the second region when viewed in a direction perpendicular to the surface.

[0013] In the above-described another aspect, the first regions to which tensile residual stress is imparted are spaced apart from each other and surrounded by second regions to which compressive residual stress is imparted when viewed from a direction perpendicular to the surface. In this case, the curvature is suppressed by the influence of the first regions to which tensile residual stress is imparted, while the surface strength can be improved by the compressive residual stress.

[0014] In the above-described another aspect, the processed portion may include plastically deformed regions formed at positions corresponding to a plurality of first regions when viewed from a direction perpendicular to the surface. The plastically deformed regions corresponding to each first region may be formed so as not to overlap with adjacent plastically deformed regions. In this case, a processed product with improved surface strength can be easily achieved.

[0015] In the above-described another aspect, the processed portion may include metal flow regions formed by metal flow at positions corresponding to the plurality of first regions when viewed from a direction perpendicular to the surface. The metal flow regions corresponding to each first region may be formed so as to overlap with adjacent metal flow regions. In this case, a processed product having further improved compressive residual stress on the surface is realized.

[0016] In the above-described another aspect, the processed portion may include at least one of titanium and a titanium alloy, in which case the ratio of the first region to which tensile residual stress is imparted to the second region to which compressive residual stress is imparted is balanced.

[0017] In yet another aspect of the present invention, a processing device includes a laser emitter, a position adjustment unit, and a control unit. The laser emitter emits laser light to be irradiated onto a surface of a workpiece containing metal. The position adjustment unit adjusts the position at which the laser light is irradiated relative to the surface. The control unit controls at least one of the laser emitter and the position adjustment unit to perform a laser peening process. In the laser peening process, a plurality of first regions to which tensile residual stress is imparted and a second region to which compressive residual stress is imparted are formed along the surface by irradiating the laser light. The laser light is irradiated onto a plurality of irradiation locations on the surface that are spaced apart from each other. The control unit controls at least one of the laser emitter and the position adjustment unit so that, when viewed from a direction perpendicular to the surface, the first regions are spaced apart from each other and surrounded by the second region.

[0018] In yet another aspect of the present invention, the control unit controls at least one of the laser emitting unit and the position adjusting unit so that the first regions are spaced apart from each other and surrounded by the second regions when viewed from a direction perpendicular to the surface. In this case, the curvature is suppressed by the influence of the first regions to which tensile residual stress is imparted, while the surface strength can be improved by the compressive residual stress.

[0019] In yet another aspect of the present invention, the control unit may control at least one of the laser emitting unit and the position adjusting unit so that plastic deformation regions caused by the irradiation of the laser light to the multiple irradiation locations are formed at positions corresponding to each of the irradiation locations, and so that the plastic deformation regions corresponding to each of the irradiation locations do not overlap with adjacent plastic deformation regions. In this case, curvature of the workpiece is further suppressed.

[0020] In yet another aspect of the present invention, the control unit may control at least one of the laser emission unit and the position adjustment unit so that metal flow regions are formed at positions corresponding to the plurality of irradiation locations by irradiating the laser beam onto the plurality of irradiation locations, and so that the metal flow regions corresponding to the plurality of irradiation locations overlap with adjacent metal flow regions. In this case, metal flow occurs in the adjacent metal flow regions in directions facing each other. Therefore, distortions caused by metal flow interfere between the adjacent irradiation locations. As a result, compressive residual stress is further improved between the adjacent irradiation locations.

[0021] In yet another aspect of the present invention, the control unit may control at least one of the laser emitting unit and the position adjusting unit so that the laser beam is irradiated simultaneously onto a plurality of irradiation locations. In this case, metal flow due to the irradiation of the laser beam occurs simultaneously at positions corresponding to the respective irradiation locations. Therefore, forces generated by the metal flow are canceled out.

[0022] In yet another aspect of the present invention, the control unit may include an acquisition unit and a determination unit. The acquisition unit may acquire information regarding the distribution of residual stress imparted to the workpiece by irradiating the laser light. The determination unit may determine the irradiation location to be irradiated with the laser light based on the information acquired by the acquisition unit. In this case, the processing device can perform laser peening processing in accordance with the preset information. As a result, the processing device can easily realize a configuration in which multiple first regions are spaced apart. [Effects of the Invention]

[0023] One aspect of the present invention provides a method for manufacturing a workpiece in which the surface strength can be improved while curvature is suppressed. Another aspect of the present invention provides a workpiece in which the surface strength can be improved while curvature is suppressed. Yet another aspect of the present invention provides a processing device in which the surface strength of the workpiece can be improved while curvature of the workpiece is suppressed. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic block diagram showing the configuration of a processing device according to an embodiment of the present invention. [Figure 2] FIG. 1A is a plan view illustrating the structure of the workpiece, and FIG. 1B is a cross-sectional view illustrating the structure of the workpiece. [Figure 3] FIG. 10 is a schematic block diagram showing the configuration of a processing device according to a modified example of the present embodiment. [Figure 4] 1 is a flowchart illustrating a method for manufacturing a workpiece. [Figure 5] FIG. 10 is a diagram for explaining irradiation of laser light. [Figure 6] FIG. 10 is a diagram for explaining multiple irradiations of laser light. [Figure 7] 1 is a flowchart showing a method for creating a dataset. [Figure 8] FIG. 10 is a diagram showing the residual stress distribution when a single irradiation point on an object to be processed is irradiated with laser light. [Figure 9] 10(a) and 10(b) are diagrams showing the estimated two-dimensional residual stress distribution. [Figure 10] 10(a) and 10(b) are diagrams showing the combined residual stress distribution. [Figure 11] FIG. 10 is a diagram showing a state in which an object to be processed is curved by irradiation with a conventional laser beam. [Figure 12] 10A to 10C are diagrams illustrating irradiation of laser light in a manufacturing method according to a modified example of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0026] First, the configuration of the processing device in this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic block diagram showing the configuration of the processing device in this embodiment.

[0027] The processing apparatus 1 performs a laser peening process on the surface 10a of the workpiece 10. The laser peening process by the processing apparatus 1 forms a desired residual stress distribution along the surface 10a. The thermal conductivity of the workpiece 10 is, for example, 20 W / m·K or less. The workpiece 10 contains a metal. The workpiece 10 contains, for example, at least one of titanium and a titanium alloy. The surface 10a is made of a metal. The surface 10a is made of, for example, at least one of titanium and a titanium alloy. In this embodiment, the workpiece 10 is made of, for example, titanium. The processing apparatus 1 includes a laser emission unit 2, a position adjustment unit 3, a stress measurement unit 4, and a control unit 5.

[0028] The laser emitter 2 emits laser light to be irradiated onto the surface 10a of the workpiece 10. In this embodiment, the laser emitter 2 adjusts the output energy and wavefront shape of the emitted laser light in response to instructions from the control unit 5. The laser emitter 2 has, for example, a laser system 21, mirrors 22, 23, and 24, and a spatial light phase modulator 25.

[0029] The laser system 21 emits a laser beam. The wavelength of the laser beam emitted by the laser system 21 is, for example, 500 nm to 1500 nm. The output energy of the laser beam emitted by the laser system 21 is, for example, 0.1 J to 1000 J. In this embodiment, the laser system 21 adjusts the output energy of the emitted laser beam in response to an instruction from the control unit 5. The output energy of the laser beam emitted from the laser system 21 is determined based on the setting of the spatial light phase modulation unit 25.

[0030] The laser light emitted from the laser system 21 is reflected by mirrors 22 and 23 and guided to the spatial light phase modulation unit 25. The laser light emitted from the spatial light phase modulation unit 25 is reflected by a mirror 24 and guided to the position adjustment unit 3.

[0031] The spatial light phase modulation unit 25 adjusts the wavefront shape of the laser light emitted from the laser emission unit 2. The spatial light phase modulation unit 25 includes, for example, a reflective spatial light phase modulator that modulates the phase of the incident laser light. In this embodiment, the spatial light phase modulation unit 25 modulates the phase of the incident laser light using liquid crystal in response to instructions from the control unit 5, thereby setting the wavefront shape of the emitted laser light. In other words, the spatial light phase modulation unit 25 shapes the laser light emitted from the laser emission unit 2 into laser light having a desired beam pattern in response to instructions from the control unit 5. For example, the spatial light phase modulation unit 25 shapes the beam pattern of the laser light emitted from the laser emission unit 2 so that the laser light is simultaneously irradiated onto multiple irradiation locations on the surface 10a of the workpiece 10.

[0032] "Simultaneous irradiation" means irradiation during overlapping time periods. The start and end of irradiation at multiple irradiation locations do not need to be strictly coincident. Hereinafter, simultaneous irradiation at multiple irradiation locations will be referred to as "single irradiation." In this embodiment, multiple irradiations are performed by moving the position at which the laser light is irradiated on the surface 10a. The output energy of the laser light emitted from the laser system 21 is determined according to the wavefront shape of the laser light emitted from the laser emission unit 2. For example, the more irradiation locations on the surface 10a that are irradiated with the laser light, the higher the output energy of the laser light emitted from the laser system 21.

[0033] The position adjustment unit 3 adjusts the position at which the laser light is irradiated onto the surface 10a of the workpiece 10. In this embodiment, the position adjustment unit 3 adjusts the position at which the laser light emitted from the laser emission unit 2 is irradiated onto the workpiece 10 in accordance with instructions from the control unit 5. The position adjustment unit 3 moves one workpiece 10 and the laser light relatively to adjust the position at which the laser light is irradiated onto the workpiece 10. The position adjustment unit 3 has, for example, a mirror 31, an imaging lens 32, a condenser lens 33, and a drive unit 34.

[0034] The mirror 31 reflects the laser light emitted from the laser emission unit 2 and guides it to the imaging lens 32 and the condenser lens 33. The imaging lens 32 and the condenser lens 33 irradiate the laser light having the desired wavefront shape adjusted by the spatial light phase modulation unit 25 onto the surface 10a of the workpiece 10. In other words, an image of the beam pattern adjusted by the spatial light phase modulation unit 25 is formed on the surface 10a by the imaging lens 32 and the condenser lens 33.

[0035] The driver 34 moves at least one of the laser light emitted from the laser emitter 2 and the workpiece 10 relatively. In this embodiment, the driver 34 drives the mirror 31, the imaging lens 32, the condenser lens 33, and the workpiece 10 in accordance with instructions from the controller 5. For example, when one workpiece 10 is irradiated multiple times, the driver 34 moves the workpiece 10 for each irradiation. For example, the driver 34 includes a robot arm or a movable stage that moves the workpiece 10.

[0036] The stress measuring unit 4 measures information related to the residual stress imparted to the workpiece 10. In this embodiment, the stress measuring unit 4 outputs the measured information to the control unit 5. The processing apparatus 1 does not necessarily have to include the stress measuring unit 4. The stress measuring unit 4 is, for example, an acoustic emission (AE) measuring instrument. The AE measuring instrument detects elastic waves generated in the workpiece 10 by the laser peening process. As a modification of this embodiment, the stress measuring unit 4 may be a laser Doppler vibrometer. When a laser Doppler vibrometer is used as the stress measuring unit 4, for example, a measurement laser beam is irradiated onto the workpiece 10, and the measurement laser beam reflected by the workpiece 10 is detected. This allows the force imparted to the workpiece 10 to be measured in a non-contact manner. The AE measuring instrument can measure residual stress repeatedly in a shorter time than a laser Doppler vibrometer.

[0037] The control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 to perform a laser peening process on the workpiece 10. In this laser peening process, a laser beam is irradiated onto the surface 10a of the workpiece 10. This laser peening process produces a workpiece 15 shown in FIGS. 2(a) and 2(b). FIG. 2(a) shows the residual stress distribution when viewed from a direction perpendicular to the surface 10a. FIG. 2(b) shows the residual stress distribution in a cross section perpendicular to the surface 10a. The workpiece 15 has a processed portion 16 having the surface 10a that has been subjected to the laser peening process. For example, the control unit 5 feedback-controls at least one of the laser emission unit 2 and the position adjustment unit 3 based on information measured by the stress measurement unit 4. The control unit 5 is, for example, a microcomputer.

[0038] The control unit 5 controls at least one of the laser emitting unit 2 and the position adjusting unit 3 so that a plurality of first regions α to which tensile residual stress has been imparted and a second region β to which compressive residual stress has been imparted are formed along the surface 10a by irradiating the surface 10a with laser light. At this time, the control unit 5 controls at least one of the laser emitting unit 2 and the position adjusting unit 3 so that, when viewed from a direction perpendicular to the surface 10a, the first regions α are spaced apart from one another and surrounded by the second region β. The laser emitting unit 2 and the position adjusting unit 3 irradiate the laser light onto each of a plurality of irradiation locations on the surface 10a. The control unit 5 instructs the laser emitting unit 2 on the beam pattern of the emitted laser light so that the first regions α and second regions β are formed.

[0039] The control unit 5 includes an acquisition unit 51, a storage unit 52, and a determination unit 53. The acquisition unit 51 acquires various information used in the laser peening process. The acquisition unit 51 acquires various information from at least one of the outside of the control unit 5 and the storage unit 52. The acquisition unit 51 acquires, for example, information about the material contained in the workpiece 10, information about the residual stress distribution imparted to the workpiece 10 by irradiation with laser light, information about the laser light irradiated onto the workpiece 10, and measurements measured by the stress measurement unit 4. The information about the residual stress distribution imparted to the workpiece 10 includes, for example, the compressive residual stress value imparted to the workpiece 10, the position on the surface 10a to be irradiated with the laser light, the area of the region on the surface 10a to be irradiated with the laser light in one irradiation, the arrangement of multiple irradiation points to be irradiated with the laser light, and the area of each irradiation point to be irradiated with the laser light. The information about the laser light irradiated onto the workpiece 10 includes, for example, parameters to be set in the laser emission unit 2. The parameters set in the laser emission unit 2 include, for example, the output energy of the laser light emitted from the laser device 21, the wavefront shape of the laser light output from the spatial light phase modulation unit 25, and the like.

[0040] The storage unit 52 stores various information used in the laser peening process. The storage unit 52 stores, for example, information acquired from the acquisition unit 51, as well as information acquired in advance. The information acquired in advance includes, for example, information relating to the residual stress distribution to be imparted to the workpiece 10 and information relating to the laser light to be irradiated onto the workpiece 10, and the like. For example, the storage unit 52 stores in advance information relating to the residual stress distribution to be imparted to the workpiece 10 and parameters to be set in the laser emission unit 2.

[0041] The determination unit 53 determines parameters to be set in the laser emission unit 2 based on the information acquired by the acquisition unit 51. The determination unit 53, for example, refers to the storage unit 52 and sets parameters associated with the information on the residual stress distribution acquired by the acquisition unit 51 in the laser emission unit 2. The determination unit 53 determines parameters to be set in the position adjustment unit 3 based on the information acquired by the acquisition unit 51. The determination unit 53, for example, determines irradiation positions on the surface 10a to be irradiated with laser light based on the information on the residual stress distribution acquired by the acquisition unit 51.

[0042] Next, a processing device according to a modified example of this embodiment will be described with reference to Fig. 3. Fig. 3 is a schematic block diagram showing the configuration of a processing device according to a modified example of this embodiment. This modified example is generally similar to or the same as the embodiment described above. This modified example differs from the embodiment described above in that it has an optical diffraction unit 28 instead of the spatial light phase modulation unit 25. Below, the differences between the embodiment described above and the modified example will be mainly described.

[0043] In this modified example, the laser emission unit 2 includes a laser system 21, mirrors 26 and 27, and an optical diffraction unit 28. The laser light emitted from the laser system 21 is reflected by the mirrors 26 and 27 and guided to the optical diffraction unit 28. The laser light emitted from the optical diffraction unit 28 is guided to the position adjustment unit 3. The position adjustment unit 3 includes a lens 36 and a drive unit 34. The laser light incident on the position adjustment unit 3 passes through the lens 36 and is irradiated onto the surface 10a of the workpiece 10. In this modified example, the drive unit 34 drives the lens 36 and the workpiece 10 in accordance with instructions from the control unit 5.

[0044] The light diffraction unit 28 diffracts the incident laser light and shapes it into a laser light having a desired beam pattern. The light diffraction unit 28 includes, for example, a diffractive optical element. The laser light incident on the light diffraction unit 28 is diffracted by the diffractive optical element. The laser light split by the light diffraction unit 28 is irradiated via the lens 36 onto a plurality of irradiation points on the surface 10a of the workpiece 10. In other words, the laser light split by the light diffraction unit 28 is irradiated onto the corresponding irradiation points P on the surface 10a.

[0045] In this modification, light diffraction unit 28 includes a plurality of diffractive optical elements that shape the incident laser light into different beam patterns. Light diffraction unit 28 switches the diffractive optical elements arranged on the light path in response to an instruction from control unit 5. For example, light diffraction unit 28 switches the diffractive optical elements arranged on the light path using an electric revolver. For example, laser light reflected by mirrors 26 and 27 passes through the diffractive optical elements arranged on the light path and is guided to lens 36.

[0046] Next, an example of a method for manufacturing a workpiece will be described with reference to Fig. 4 to Fig. 6. Fig. 4 is a flowchart showing the method for manufacturing a workpiece. Fig. 5 is a diagram for explaining irradiation of laser light. Fig. 6 is a diagram for explaining multiple irradiations of laser light.

[0047] First, a workpiece 10 containing metal is prepared (step S1). For example, the workpiece 10 is placed on a movable stage included in the driving unit 34. At this time, the workpiece 10 is placed so that the surface 10a is irradiated with laser light. In this embodiment, the surface 10a of the workpiece 10 in step S1 is made of metal and is exposed. The surface 10a is made of, for example, at least one of titanium and a titanium alloy.

[0048] Next, the control unit 5 acquires various information used in the laser peening process and determines information to instruct the laser emitter 2 and the position adjuster 3 (process S2). The control unit 5 acquires information from outside the control unit 5 and from the storage unit 52 using the acquisition unit 51. The information acquired from outside the control unit 5 is, for example, information input by a user. The control unit 5 acquires, using the acquisition unit 51, information on the material contained in the workpiece 10, the residual stress distribution imparted to the workpiece 10 by irradiating it with laser light, and information on the laser light to be irradiated onto the workpiece 10. The control unit 5 determines, using the determination unit 53, parameters to be set in the laser emitter 2 and the position adjuster 3 based on the information acquired by the acquisition unit 51. The determination unit 53 determines, for example, the output energy of the laser light emitted from the laser system 21 and the beam pattern to be shaped by the spatial light phase modulator 25 based on the information acquired by the acquisition unit 51. When the optical diffraction section 28 is used instead of the spatial light phase modulation section 25, the determination section 53 may determine an optical diffraction element to be placed on the optical path.

[0049] Next, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 to perform laser peening processing (process S3). For example, the determination unit 53 instructs the position adjustment unit 3 to set an irradiation position P to be irradiated with the laser light L based on the parameters determined in process S2 (process S31). Next, the determination unit 53 instructs the laser emission unit 2 to emit laser light based on the parameters determined in process S2 (process S32).

[0050] In the laser peening process, as shown in FIG. 5, laser light L is irradiated onto a plurality of irradiation points P. A laser spot of the laser light L is located at each irradiation point P. The laser light emitted from the laser emission unit 2 is guided to the position adjustment unit 3 and is irradiated onto each irradiation point P set in process S31. In this embodiment, the laser spot of the laser light L is located at each irradiation point P on the surface 10a. The plurality of irradiation points P are located in a matrix on the surface 10a. A plasma confinement layer may be provided on the surface 10a using flowing water or the like to confine plasma generated by ablation during laser irradiation and transmit the impact to the workpiece.

[0051] In process S3, the laser light L is simultaneously irradiated onto a plurality of irradiation points P, for example, under the control of the control unit 5. For example, in process S32, the laser emitting unit 2 shapes the beam pattern of the emitted laser light in the spatial light phase modulation unit 25 so that the laser light L is simultaneously irradiated onto a plurality of irradiation points P that are spaced apart from one another on the surface 10a of the workpiece 10.

[0052] In step S3, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that a plastic deformation region R1 due to plastic deformation is formed at a position corresponding to each irradiation location P by irradiating the multiple irradiation locations P with the laser light L. Plastic deformation occurs when shock waves generated by laser irradiation apply pressure exceeding the yield stress, causing metal crystals to dislocate. Metal crystals are dislocated in the plastic deformation region R1, causing compressive stress. Stress exceeding the yield stress is applied to the plastic deformation region R1. In this embodiment, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that the plastic deformation region R1 corresponding to each irradiation location P does not overlap with adjacent plastic deformation regions R1. The laser light L is irradiated to the multiple irradiation locations P so that a plastic deformation region R1 due to plastic deformation is formed at each irradiation location P. As a result, the plastic deformation region R1 corresponding to each irradiation location P is formed so as not to overlap with adjacent plastic deformation regions R1.

[0053] In step S3, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that, by irradiating the multiple irradiation locations P with the laser light L, a metal flow region R2 due to metal flow is formed at a position corresponding to each irradiation location P. In metal flow, a crystal flow without dislocations occurs. The crystal flow without dislocations is blocked by the surrounding stationary metal, causing elastic distortion. This elastic distortion imparts compressive stress to the metal flow region R2. In this embodiment, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that the metal flow region R2 corresponding to each irradiation location P overlaps with adjacent metal flow regions R2. The laser light L is irradiated to the multiple irradiation locations P so that a metal flow region R2 due to metal flow is formed at each irradiation location P. Metal flow occurs around the plastic deformation region R1. As a result, the metal flow region R2 corresponding to each irradiation location P is formed so as to overlap with adjacent metal flow regions R2. When adjacent metal flow regions R2 overlap, their elastic strains interfere with each other, resulting in a larger compressive stress.

[0054] As shown in Figures 2(a) and 2(b), by irradiating multiple irradiation locations P with laser light L, multiple first regions α to which tensile residual stress is imparted and second regions β to which compressive residual stress is imparted are formed along the surface 10a. The first regions α are formed at positions corresponding to each irradiation location P. The first regions α are formed in regions directly below the laser spots formed on the surface 10a of the workpiece 10. The first regions α are formed in regions extending from the laser spots on the surface 10a in the thickness direction of the workpiece 10. The edges of the first regions α on the surface 10a are formed along the edges of the laser spots formed on the surface 10a. The maximum width of the first regions α is equivalent to the maximum width of the laser spots on the surface 10a. The term "equivalent" includes a margin of error. The "maximum width" refers to the value of the longest portion of each first region α or each laser spot in a direction parallel to the surface 10a. For example, if the laser spots on the surface 10a are circular, the maximum width of the laser spots is the maximum diameter of the laser spots. The first region α may be formed slightly larger so as to include the laser spot when viewed from a direction perpendicular to the surface 10a, or may be formed slightly smaller so as to be included in the laser spot.

[0055] Tensile residual stress in each first region α is formed, for example, when a melted portion solidifies due to irradiation with laser light L. Compressive residual stress in the second region β is formed, for example, by plastic deformation due to irradiation with laser light L and compression due to metal flow. The second region β includes a plastic deformation region R1 and a metal flow region R2. Arrow A indicates the direction of metal flow. Irradiation of adjacent irradiation points P with laser light L causes metal flow in directions facing each other. In this case, compressive residual stress is also generated. The second region β is formed around each first region α. When viewed from a direction perpendicular to the surface 10a, the first regions α are formed so as to be spaced apart from each other and surrounded by the second region β. The residual stress value in the second region β is adjusted by adjusting the irradiation interval of the laser light L.

[0056] In this embodiment, steps S31 and S32 are repeated multiple times. In other words, the surface 10a of the workpiece 10 is irradiated with laser light multiple times. After the irradiation point P set in step S31 is irradiated in step S32, the control unit 5 determines whether or not to end the laser peening process. If it is determined that the laser peening process should be ended, step S3 is ended. If it is determined that the laser peening process should not be ended, steps S31 and S32 are performed again.

[0057] FIG. 6 shows an example of positions on the surface 10a where the laser light is irradiated when the surface 10a is irradiated with the laser light multiple times. In one irradiation, the laser light L is simultaneously irradiated to multiple irradiation points P in one unit region R5. The position of the unit region R5 is determined by the determination unit 53 in step S31. In FIG. 6, the unit region R5 is indicated by a dashed line. For example, by performing steps S31 and S32 multiple times, the laser light is irradiated to multiple unit regions R5. The size of the unit region R5 is determined by the determination unit 53 based on information on the residual stress distribution acquired by the acquisition unit 51. For example, by multiple irradiations of the laser light, first regions α are formed at several locations to tens of thousands of locations along the surface 10a.

[0058] In this embodiment, if the area of unit region R5 on surface 10a is S1, the area of one irradiation point P irradiated with laser light L is S2, and the number of irradiation points P irradiated in unit region R5 in one irradiation is N, then (N×S2 / S1)<0.5 holds. In other words, the total area of irradiation points P irradiated with laser light L in one unit region R5 is half or less of the area of one unit region R5. In this case, the proportion of the area of second region β in unit region R5 to which compressive residual stress is imparted is improved on surface 10a.

[0059] In this way, the workpiece 15 is manufactured. The workpiece 15 has a processing portion 16 including a surface 10a. The thermal conductivity of the processing portion 16 is, for example, 20 W / m·K or less. The processing portion 16 contains a metal. For example, the processing portion 16 contains at least one of titanium and a titanium alloy. As shown in FIGS. 2(a) and 2(b), the processing portion 16 has a plurality of first regions α and second regions β described above formed along the surface 10a. When viewed from a direction perpendicular to the surface 10a, the first regions α are spaced apart from one another and surrounded by the second region β. In other words, the plurality of first regions α are discretely formed along the surface 10a. "Discretely formed" means formed in a scattered manner.

[0060] The processed portion 16 includes a plastic deformation region R1 and a metal flow region R2. When viewed from a direction perpendicular to the surface 10a, the plastic deformation region R1 and the metal flow region R2 are formed at positions corresponding to multiple first regions α. The plastic deformation region R1 and the metal flow region R2 are included in the second region β. The plastic deformation region R1 and the metal flow region R2 surround the corresponding first region α. When viewed from a direction perpendicular to the surface 10a, the metal flow region R2 surrounds the plastic deformation region R1. The metal flow region R2 is formed around the plastic deformation region R1. The plastic deformation region R1 corresponding to each first region α is formed so as not to overlap with adjacent plastic deformation regions R1. The metal flow region R2 corresponding to each first region α is formed so as to overlap with adjacent metal flow regions R2.

[0061] The shortest distance between adjacent first regions α is, for example, (2π) of the maximum width of the first regions α. 1 / 2 In this case, (N×S2 / S1)<0.5 is satisfied. Furthermore, the shortest distance between adjacent first regions α is, for example, less than 10 times the maximum width of the first regions α. In this case, a configuration can be easily realized in which adjacent plastic deformation regions R1 do not overlap, but adjacent metal flow regions R2 overlap.

[0062] In this embodiment, in the workpiece 15, the first regions α are arranged in a matrix along the surface 10a when viewed from a direction perpendicular to the surface 10a. In this embodiment, the maximum width of the first regions α is 1 mm, the shortest distance between adjacent first regions α is 3 mm, and the multiple first regions α are arranged at equal intervals. "Equal intervals" includes the range of manufacturing error. The distance between adjacent first regions α means the distance between the centers of each first region α.

[0063] The position and size of the first region α are equivalent to the position and size of the irradiation point P. Therefore, the maximum width of the first region α is equivalent to the maximum width of the laser spot on the surface 10a. The shortest distance between adjacent first regions α is equivalent to the shortest distance between adjacent laser spots on the surface 10a. The sizes of the plastic deformation region R1 and the metal flow region R2 depend on the conditions of the laser irradiated onto the surface 10a. If the shortest distance between adjacent laser spots on the surface 10a is less than 10 times the maximum width of these laser spots, a configuration can be easily realized in which adjacent plastic deformation regions R1 do not overlap, and adjacent metal flow regions R2 overlap.

[0064] In a direction perpendicular to the surface 10a, the thickness of each first region α of the workpiece 15 is, for example, equal to or less than the maximum value of the surface roughness of the surface 10a. In a direction perpendicular to the surface 10a, the maximum thickness of each first region α of the workpiece 15 is, for example, 50 μm or less. In a direction perpendicular to the surface 10a, the maximum thickness of the second region β of the workpiece 15 is, for example, greater than the maximum thickness of each first region α. For example, in a direction perpendicular to the surface 10a, the maximum thickness of the second region β of the workpiece 15 is at least twice the maximum thickness of each first region α. For example, when a titanium workpiece 10 is subjected to a 60 GW / cm 2 When laser light L of this intensity was irradiated onto each irradiation point P, the thickness of each first region α of the workpiece 15 was 50 μm and the thickness of each second region β of the workpiece 15 was 500 μm in the direction perpendicular to the surface 10a.

[0065] In this embodiment, the residual stress value of the tensile residual stress in each first region α is equal to or less than the yield stress of the surface 10a of the object 10. For example, if the object 10 is made of titanium, the residual stress value of the tensile residual stress in each first region α is equal to or less than the yield stress of titanium.

[0066] Next, an example of a method for creating a data set used in a laser peening process will be described with reference to FIGS. 7 to 10. In step S2, the determination unit 53 of the control unit 5 determines parameters to be set in the laser emitter 2 and the position adjuster 3, for example, based on a data set previously stored in the storage unit 52 and information input by the user. FIG. 7 is a flowchart showing the data set creation method. FIG. 8 is a diagram showing the residual stress distribution when a laser beam is irradiated to one irradiation point P of a workpiece. FIGS. 9(a) and 9(b) are diagrams showing estimated two-dimensional residual stress distributions. FIGS. 10(a) and 10(b) are diagrams showing synthesized residual stress distributions. FIGS. 8, 9(a), 9(b), 10(a), and 10(b) show data when the workpiece is made of SUS304. In this case, the thermal conductivity of the workpiece is 20 W / m·K or less.

[0067] The data set includes, for example, information about the material contained in the workpiece 10, information about the residual stress distribution imparted to the workpiece 10, and information about the laser beam irradiated onto the workpiece 10. Various pieces of information are associated in the data set. For example, the data set includes the type of material of the workpiece, the compressive residual stress value imparted to the workpiece, the area of the unit region R5 in one irradiation, and the output energy of the laser beam emitted from the laser system 21. The data set may further include information about the settings of the spatial light phase modulation unit 25 or the light diffraction unit 28. The information about the settings of the spatial light phase modulation unit 25 or the light diffraction unit 28 includes, for example, information about the beam pattern of the laser beam emitted from the laser emitter 2 or information about the residual stress distribution formed in the unit region R5 in one irradiation. The created data set is stored in advance in the storage unit 52. In this embodiment, the data set is created separately before the workpiece is manufactured.

[0068] First, a processing object 70 is prepared (step S51). The processing object 70 prepared in step S51 has the same structure as the processing object 10 prepared in step S1. "The same structure" refers to a structure in which the same residual stress distribution is formed within the range of manufacturing error when irradiated with laser light under the same conditions. In step S51, the material contained in the processing object 70 may be stored in memory unit 52.

[0069] Next, one irradiation point is irradiated with laser light (process S52). In process S52, the irradiated laser light has the same beam diameter and intensity as the laser light L irradiated to one irradiation point P in process S3. The "beam diameter" refers to the beam diameter at the position where it is irradiated on the surface 10a. In process S52, information about the laser light irradiated to the workpiece 70 may be stored in the memory unit 52.

[0070] Next, the residual stress distribution is measured (step S53). The residual stress distribution is measured by the stress measurement unit 4. For example, the residual stress distribution is measured by an X-ray diffraction device. For example, the X-ray diffraction device measures residual stress value data at distances of 1 / 10 or less of the beam diameter of the irradiated laser light. FIG. 8 plots the measured data and shows the residual stress distribution measured in step S53. In the graph shown in FIG. 8, the horizontal axis indicates the distance from the center of the irradiation point P irradiated with the laser light, and the vertical axis indicates the residual stress value at each position. In FIG. 8, region γ is the region of the irradiation point P irradiated with the laser light on the surface 10a. In this embodiment, the residual stress distribution measured in step S53 is a distribution in a direction parallel to the surface 10a, that is, a one-dimensional distribution.

[0071] In this embodiment, positive residual stress values indicate tensile residual stress, and negative residual stress values indicate compressive residual stress. In Figure 8, tensile residual stress is imparted where the residual stress value is positive, and compressive residual stress is imparted where the residual stress value is negative. As shown in Figure 8, tensile residual stress is imparted to region γ irradiated with the laser light, and compressive residual stress is imparted to the periphery of region γ. The size of the plastic deformation region R1 also depends on the yield stress of the workpiece.

[0072] Next, based on the measurement results in step S53, a two-dimensional residual stress distribution when one irradiation point P is irradiated with laser light is estimated (step S54). For example, as shown in FIG. 9(a), the control unit 5 acquires reflection-symmetric data in the residual stress distribution measured in step S53, with the axis passing through the center of the irradiation point P irradiated with the laser light as the axis of symmetry. Next, the control unit 5 acquires data rotated around the axis of symmetry as a two-dimensional residual stress distribution. FIG. 9(b) shows the acquired two-dimensional residual stress distribution as viewed from a direction perpendicular to the surface 10a. In FIG. 9(b), the residual stress distribution is indicated by a color tone corresponding to the residual stress value. In this way, the control unit 5 estimates and acquires a two-dimensional residual stress distribution when one irradiation point P is irradiated with laser light, for example, based on the residual stress distribution measured in step S53.

[0073] Next, based on the estimation results of step S54, the residual stress distribution formed by irradiating the multiple irradiation locations P with laser light is estimated (step S55). For example, by combining the two-dimensional residual stress distributions acquired in step S54, the residual stress distribution when the multiple irradiation locations P are irradiated with laser light is estimated. The residual stress value in the second region β is adjusted by adjusting the irradiation interval of the laser light. FIG. 10(a) shows an example of the residual stress distribution estimated in step S55 as viewed from a direction perpendicular to the surface 10a. In the residual stress distribution shown in FIG. 10(a), the irradiation interval of the laser light is set so that the region to which the desired compressive residual stress value is imparted becomes wider. FIG. 10(b) is a graph showing the residual stress distribution designed in step S55. As in FIG. 8, in FIG. 10(b), the horizontal axis indicates the distance from the center of the irradiation location P irradiated with the laser light, and the vertical axis indicates the residual stress value at each position. In step S55, information regarding the estimated residual stress distribution may be stored in the memory unit 52.

[0074] Next, various pieces of information corresponding to the residual stress distribution estimated in step S55 are associated (step S56). For example, the material contained in the workpiece 70, the output energy of the laser light emitted from the laser emission unit 2, and the residual stress value in the residual stress distribution estimated in step S55 are associated with each other and stored in the storage unit 52. The output energy of the laser light emitted from the laser emission unit 2 is calculated from, for example, the intensity of the laser light irradiated onto the workpiece 70 in step S52, the number of irradiation points P to be irradiated with the laser light in the unit region R, etc.

[0075] A data set used in the laser peening process is created by changing various conditions and repeating steps S51 to S56. The various conditions to be changed include, for example, the material contained in the workpiece 70, the output energy of the laser light irradiated onto the workpiece 70, and the irradiation interval of the laser light adjusted in step S55. The created data set is stored in the storage unit 52 and read out by the acquisition unit 51 in step S3. For example, when the user inputs the type of material of the workpiece 10, the compressive residual stress value to be imparted, and the area of the unit region R5 in one irradiation, the acquisition unit 51 acquires the output energy of the laser light associated with the information input in the data set.

[0076] In this embodiment, steps S51 to S56 are performed by a device external to the processing apparatus 1, 1A. The above-mentioned step S52 may be performed by the laser emission unit 2 and the position adjustment unit 3 in response to an instruction from the control unit 5. The above-mentioned step S53 may be performed by the stress measurement unit 4 in response to an instruction from the control unit 5. The above-mentioned steps S54 to S56 may be performed in the control unit 5, for example.

[0077] Next, the effects of the above-described method for manufacturing a workpiece, the workpiece, and the processing device will be described.

[0078] When performing laser peening, irradiation with laser light LA causes metal flow in the workpiece. The accumulated effects of the metal flow may cause the workpiece 10 to bend. FIG. 11 shows the workpiece 10 bent by conventional laser light irradiation. Furthermore, when tensile residual stress is continuously imparted to a relatively wide area by continuous irradiation with laser light, the strength of the surface 10a decreases. For example, when the laser light LA is scanned along the surface 10a and continuously irradiated onto the surface 10a, areas imparted with tensile residual stress are continuously arranged. In this case, the strength of the surface 10a decreases, and deterioration over time is likely to occur.

[0079] In the above-described method for manufacturing a workpiece, the first regions α to which tensile residual stress is imparted are formed so as to be spaced apart from each other and surrounded by the second region β to which compressive residual stress is imparted when viewed from a direction perpendicular to the surface 10a. In this case, curvature is suppressed by the influence of the first regions α to which tensile residual stress is imparted, while surface strength can be improved by the compressive residual stress. Therefore, a workpiece can be manufactured in which curvature is suppressed and surface strength is improved. In particular, curvature can be significantly suppressed when the workpiece is a thin plate.

[0080] In the above-described manufacturing method, the laser light L is irradiated onto a plurality of irradiation locations P so that a plastic deformation region R1 due to plastic deformation is formed at a position corresponding to each irradiation location P. The plastic deformation regions R1 corresponding to each irradiation location P are formed so as not to overlap with adjacent plastic deformation regions R1. When the plastic deformation regions R1 do not overlap, plastic deformation is suppressed and deformation of the workpiece 10 in the direction along the surface 10a is also smaller than when the plastic deformation regions R1 overlap. Therefore, curvature of the workpiece is further suppressed.

[0081] In the above-described manufacturing method, the laser beam L is irradiated onto multiple irradiation locations P so that metal flow regions R2 due to metal flow are formed at positions corresponding to each irradiation location P. The metal flow regions R2 corresponding to each irradiation location P are irradiated so that they overlap with adjacent metal flow regions R2. In this case, metal flow occurs in the adjacent metal flow regions R2 in directions facing each other. Therefore, distortion due to metal flow interferes between adjacent irradiation locations P. As a result, compressive residual stress is further improved between adjacent irradiation locations P while suppressing the energy of the laser beam L. In addition, because the interference of distortion at positions away from the irradiation locations P is utilized, the region to which compressive residual stress is imparted can be expanded or maintained while reducing the energy of the laser beam L irradiated onto the workpiece. For example, the energy required to process the entire surface 10a of the workpiece 10 is reduced compared to when the laser beam L is scanned over the entire surface 10a.

[0082] In the above-described manufacturing method, the laser light L is irradiated simultaneously onto multiple irradiation points P. In this case, metal flow due to irradiation with the laser light L occurs simultaneously at positions corresponding to each irradiation point P. Because metal flow simultaneously occurs in the directions facing each other in the adjacent metal flow regions R2, compressive residual stress is further improved between the adjacent irradiation points P. In addition, the influence of the metal flow in each metal flow region R2 is offset by the metal flow in the adjacent metal flow region R2. This suppresses curvature of the workpiece due to metal flow.

[0083] In the above-described manufacturing method, the workpiece 10 includes at least one of titanium and a titanium alloy. In this case, the thermal conductivity of the workpiece 10 is suppressed. For example, the thermal conductivity of the workpiece 10 can be suppressed to 20 W / m·K or less. As a result, a balance is achieved between the size ratio of the first region α, to which tensile residual stress is imparted, to the second region β, to which compressive residual stress is imparted. Compared to when the workpiece 10 is made of other materials, the thickness of the first region α is formed smaller in a direction perpendicular to the surface 10a. Therefore, the size ratio of the first region α to the second region β is smaller than when the workpiece 10 is made of other materials.

[0084] In the workpiece 15, when viewed from a direction perpendicular to the surface, the first regions a to which tensile residual stress is imparted are spaced apart from each other and surrounded by second regions β to which compressive residual stress is imparted. In this case, the first regions a to which tensile residual stress is imparted suppress curvature, while the compressive residual stress can improve surface strength.

[0085] In the processed portion 16, the plastic deformation regions R1 corresponding to each first region α are formed so as not to overlap with adjacent plastic deformation regions R1, which makes it easy to achieve a processed product with improved surface strength.

[0086] In the processed portion 16, the metal flow regions R2 corresponding to each first region α are formed to overlap with the adjacent metal flow regions R2, thereby achieving a processed product with further improved compressive residual stress on the surface.

[0087] In the workpiece 15, the processed portion 16 includes at least one of titanium and a titanium alloy. In this case, the ratio of the first region α, which is provided with tensile residual stress, to the second region β, which is provided with compressive residual stress, is balanced. As a result, manufacturing costs can be reduced.

[0088] In the processing apparatus 1, 1A, the control unit 5 controls at least one of the laser emitting unit 2 and the position adjusting unit 3 so that the first regions α are spaced apart from each other and surrounded by the second region β when viewed from a direction perpendicular to the surface 10a. In this case, the curvature is suppressed by the influence of the first regions α to which tensile residual stress is imparted, while the surface strength can be improved by the compressive residual stress.

[0089] In the processing apparatus 1, 1A, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that plastic deformation regions R1 are formed at positions corresponding to each irradiation point P by irradiating the laser light L onto the multiple irradiation points P, and so that the plastic deformation regions R1 corresponding to each irradiation point P do not overlap with adjacent plastic deformation regions R1. In this case, curvature of the workpiece is further suppressed.

[0090] In the processing apparatus 1, 1A, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that metal flow regions R2 are formed at positions corresponding to each of the irradiation locations P by irradiating the laser light L onto the multiple irradiation locations P, and so that the metal flow regions R2 corresponding to each of the irradiation locations P overlap with adjacent metal flow regions R2. In this case, metal flow occurs in the adjacent metal flow regions R2 in directions facing each other. Therefore, distortion due to metal flow interferes between adjacent irradiation locations P. As a result, compressive residual stress is further improved between adjacent irradiation locations P.

[0091] In the processing apparatus 1, 1A, the control unit 5 controls at least one of the laser emission unit 2 and the position adjustment unit 3 so that the laser light L is irradiated simultaneously onto multiple irradiation points P. In this case, metal flow due to irradiation with the laser light L occurs simultaneously at positions corresponding to each irradiation point P. Since metal flow simultaneously occurs in directions facing each other in adjacent metal flow regions R2, compressive residual stress is further improved between adjacent irradiation points P. In addition, the influence of metal flow in each metal flow region R2 is offset by metal flow in adjacent metal flow regions R2. As a result, curvature of the workpiece due to metal flow is suppressed.

[0092] In the processing apparatus 1, 1A, the control unit 5 includes an acquisition unit 51 and a determination unit 53. The acquisition unit 51 acquires information regarding the residual stress distribution imparted to the workpiece 10 by irradiation with the laser light L. The determination unit 53 determines the irradiation position P to be irradiated with the laser light L based on the information acquired by the acquisition unit 51. In this case, the processing apparatus 1, 1A can perform laser peening processing in accordance with the preset information. As a result, the processing apparatus 1, 1A can easily realize a configuration in which multiple first regions α are spaced apart.

[0093] The above describes embodiments and modifications of the present invention, but the present invention is not necessarily limited to the above-described embodiments and modifications, and various modifications are possible without departing from the spirit of the present invention.

[0094] For example, in the above-described embodiment and modified examples, the parameters set in the laser emitter 2 are set in response to instructions from the control unit 5. However, the parameters set in the laser emitter 2 may be set in advance or set by the user, without depending on instructions from the control unit 5. For example, the output energy of the laser light emitted from the laser device 21 and the wavefront shape of the laser light output from the spatial light phase modulation unit 25 may be set by the user.

[0095] In the above-described embodiment, the laser light L is simultaneously irradiated onto a plurality of irradiation points P. However, the laser light L may be irradiated onto a plurality of irradiation points P sequentially.

[0096] In the above-described embodiment, the surface 10a of the object 10 is exposed, and the laser beam L is directly irradiated onto the surface 10a. As shown in FIG. 12 , a sacrificial layer 90 may be formed on the surface 10a of the object 10, and the laser beam L may be irradiated onto the surface 10a covered with the sacrificial layer 90. In other words, in steps S1 and S51, an object having the surface 10a covered with the sacrificial layer 90 may be prepared. In this case, the amount of heat applied to the surface 10a is adjusted depending on the material and thickness of the sacrificial layer 90. As a result, the size of the first region α to which tensile residual stress is imparted can be adjusted regardless of the material of the object 10.

[0097] In the above-described embodiment and modified examples, the creation of the data set is performed separately before the manufacture of the workpiece. However, the creation may be performed during the flow of the method for manufacturing the workpiece. In this case, step S51 is the same as step S1. For example, steps S52 to S55 are performed between steps S1 and S2.

[0098] The material of the object 10 may be a metal other than titanium, a titanium alloy, and SUS 304. In this case, in order to balance the ratio of the size of the first region α to which tensile residual stress is applied to the size of the second region β to which compressive residual stress is applied, it is preferable to use a metal having a thermal conductivity of 20 W / m K or less as the material of the object 10.

[0099] In the above-described embodiment and modified examples, the first region α is shown to have a circular shape when viewed from a direction perpendicular to the surface 10a. However, the shape of the first region α is not limited to this. For example, the first region α may have a rectangular shape when viewed from a direction perpendicular to the surface 10a.

[0100] In the above-described embodiment and modified examples, the surface 10a is irradiated with the laser light multiple times. However, the surface 10a may be irradiated with the laser light only once. In this case, the laser light L is irradiated to multiple irradiation points P simultaneously. [Explanation of symbols]

[0101] 1, 1A... processing device, 2... laser emission unit, 3... position adjustment unit, 5... control unit, 10... object to be processed, 10a... surface, 15... workpiece, 16... processing portion, 51... acquisition unit, 53... determination unit, L... laser light, P... irradiation location, R1... plastic deformation region, R2... metal flow region, α... first region, β... second region.

Claims

1. Providing a workpiece including a metal; and forming a plurality of first regions to which tensile residual stress is imparted and a second region to which compressive residual stress is imparted along the surface by irradiating a plurality of irradiation points spaced apart on the surface of the object with laser light, A method for manufacturing a workpiece, wherein the first regions are formed so as to be spaced apart from each other and surrounded by the second region when viewed from a direction perpendicular to the surface.

2. the laser light is irradiated onto the plurality of irradiation locations so that plastic deformation regions due to plastic deformation are formed at positions corresponding to the respective irradiation locations; The method for manufacturing a workpiece according to claim 1 , wherein the plastic deformation regions corresponding to the respective irradiated locations are formed so as not to overlap with adjacent plastic deformation regions.

3. the laser light is irradiated onto the plurality of irradiation locations so that metal flow regions are formed at positions corresponding to the respective irradiation locations; The method for manufacturing a workpiece according to claim 1 or 2, wherein the metal flow regions corresponding to the respective irradiation points are irradiated so as to overlap with the metal flow regions adjacent to each other.

4. The method for manufacturing a workpiece according to claim 1 , wherein the laser light is irradiated to the plurality of irradiation locations simultaneously.

5. The method for manufacturing a workpiece according to claim 1 , wherein the workpiece contains at least one of titanium and a titanium alloy.

6. a processed portion including a metal and having a plurality of first regions to which tensile residual stress is imparted and a second region to which compressive residual stress is imparted formed along a surface thereof; When viewed from a direction perpendicular to the surface, the plurality of first regions are arranged apart from one another, each of the plurality of first regions is surrounded by the second region, and the second region is located between the first regions adjacent to one another, the processed portion includes, when viewed from a direction perpendicular to the surface, metal flow regions caused by metal flow without crystal dislocation at positions corresponding to each of the plurality of first regions; A workpiece, wherein the metal flow regions corresponding to each of the plurality of first regions are formed so as to overlap with the metal flow regions corresponding to different first regions and adjacent to each other in the second region.

7. the processed portion includes plastically deformed regions formed at positions corresponding to the plurality of first regions when viewed from a direction perpendicular to the surface, The workpiece according to claim 6 , wherein the plastic deformation regions corresponding to the first regions are formed so as not to overlap with adjacent plastic deformation regions.

8. 8. The workpiece of claim 6 or 7, wherein the working portion comprises at least one of titanium and a titanium alloy.

9. 9. The workpiece according to claim 6, wherein the portion surrounded by the second region when viewed in a direction perpendicular to the surface does not include a welded portion.

10. 10. The workpiece according to claim 6, wherein the plurality of first regions are arranged two-dimensionally in a matrix so as to be scattered along the surface when viewed from a direction perpendicular to the surface.

11. a laser emission unit that emits laser light to be irradiated onto a surface of a workpiece including metal; a position adjustment unit that adjusts the position at which the laser light is irradiated on the surface; a control unit that controls at least one of the laser emitting unit and the position adjusting unit so as to form a plurality of first regions to which tensile residual stress has been imparted and a second region to which compressive residual stress has been imparted along the surface by irradiating the laser light to a plurality of irradiation points that are spaced apart on the surface, The control unit controls at least one of the laser emission unit and the position adjustment unit so that, when viewed from a direction perpendicular to the surface, the first regions are spaced apart from each other and surrounded by the second region.

12. The processing device according to claim 11, wherein the control unit controls at least one of the laser emission unit and the position adjustment unit so that plastic deformation regions due to plastic deformation are formed at positions corresponding to each of the irradiation locations by irradiating the laser light to the multiple irradiation locations, and so that the plastic deformation regions corresponding to each of the irradiation locations do not overlap with adjacent plastic deformation regions.

13. The processing device according to claim 11 or 12, wherein the control unit controls at least one of the laser emission unit and the position adjustment unit so that metal flow regions due to metal flow are formed at positions corresponding to each of the irradiation locations by irradiating the laser light to the multiple irradiation locations, and so that the metal flow regions corresponding to each of the irradiation locations overlap with adjacent metal flow regions.

14. The processing device according to claim 11 , wherein the control unit controls at least one of the laser emission unit and the position adjustment unit so that the laser light is irradiated simultaneously onto the plurality of irradiation locations.

15. 15. The processing device according to claim 11, wherein the control unit includes: an acquisition unit that acquires information regarding the residual stress distribution imparted to the object to be processed by irradiating the laser light; and a determination unit that determines an irradiation location to irradiate the laser light based on the information acquired by the acquisition unit.

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