JP7114518B2 - LASER PROCESSING APPARATUS AND LASER PROCESSING METHOD - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a laser processing apparatus and a laser processing method.

Laser processing is a technique for processing an object by focusing laser light on the object. A laser beam emitted from a laser oscillator is focused on the surface of an object through an optical system such as a lens and a mirror. Laser processing enables welding, cutting, or surface modification (peening, hardening, etc.) of objects.

Among them, peening (laser peening) irradiates a target object with a pulse laser and imparts residual stress to the target object by ablation. In this case, it is common to apply a coating film such as black paint to the surface of the object in order to confine the metal plasma generated by the ablation. Compressive stress can also be applied by irradiation.
As the light source used for laser peening, a YAG laser fundamental wave with a wavelength of 1064 nm or a harmonic wave of a YAG laser with a wavelength of 532 nm that is half the fundamental wavelength is used, and a laser oscillator with a nanosecond pulse width is used. There are many. There are also cases of laser peening using ultra-short pulse lasers such as sub-nanosecond and femtosecond lasers.

Japanese Patent No. 3373638

Laser processing machines are commercially available and are used in processing fields such as welding and cutting. In recent years, laser peening devices have also become commercially available, and are used in combination with industrial robots for deformation processing (peen forming) of turbine blades and thin plates.

Here, in the process of irradiating a material with a pulsed laser to generate plasma, such as laser peening, the construction is performed using, for example, pulse energy, spot diameter, and pulse density as main parameters. Appropriate setting of these parameters requires know-how, and even if the same construction equipment is used, it often has to be selected based on experience.
SUMMARY OF THE INVENTION An object of the present invention is to provide a laser processing apparatus and a laser processing method that facilitate setting of laser peening working conditions.

A laser processing device according to one aspect includes a laser irradiation device, an input unit, a storage unit, and a selection unit. The laser irradiation device applies a pulsed laser to the object to be processed to apply residual stress. The input receives information on the material to be constructed and the desired residual stress. The storage unit stores residual stress data representing the relationship among materials, construction conditions, and residual stress. The selection unit selects the construction target material and construction conditions corresponding to the desired residual stress based on the residual stress data. The selection unit selects a material close to the construction target material from the residual stress data when the construction target material cannot be found in the residual stress data.

INDUSTRIAL APPLICABILITY The present invention can provide a laser processing apparatus and a laser processing method that facilitate setting of conditions for laser peening.

1 is a schematic diagram of a laser processing apparatus according to an embodiment; FIG. It is a schematic diagram which shows a laser irradiation pattern. It is a schematic diagram which shows an example of physical-property data. It is a schematic diagram showing an example of residual stress data. It is a schematic diagram showing an example of residual stress data. It is a schematic diagram showing an example of residual stress data. It is a flowchart showing the procedure of the laser processing method. 1 is a schematic diagram of a laser processing system according to an embodiment; FIG.

A laser processing apparatus according to an embodiment will be described below with reference to the drawings.
(First embodiment)
A first embodiment will be described with reference to FIGS. 1 to 7. FIG. FIG. 1 is a conceptual diagram showing a laser peening device 10 according to the first embodiment.
The laser peening apparatus 10 has a laser oscillator 11, an optical transmission section 12, a light collecting section 13, a holding/moving section 14, and a control section 15 (input section 16, DB storage section 17, calculation section 18, drive section 19).

A laser oscillator 11 oscillates and emits laser light L (pulse laser). The laser light L emitted from the laser oscillator 11 passes through the light transmission section 12, is condensed by the condensing section 13, and is irradiated onto the surface of the object O to be worked.
By controlling the laser oscillator 11, the pulse energy can be adjusted.

A giant pulse YAG laser oscillator is preferably used as the laser oscillator 11 for laser peening. As will be described later, if the second harmonic of the YAG laser (wavelength: 532 nm) is used in underwater construction, the laser light output can be transmitted with almost no attenuation.
However, a laser oscillator 11 other than the giant pulse YAG laser oscillator can also be used. It suffices that plasma is formed on the surface of the object O to be processed by the pulsed laser emitted from the laser oscillator 11, and laser ablation can be performed.

The light transmission unit 12 is a light transmission mechanism that transmits the laser light L emitted from the laser oscillator 11 to the light collection unit 13. have By arranging optical parts and an adjustment mechanism on the base, the laser light is transmitted to the condensing section 13 .
The optical transmission unit 12 may have an optical fiber and transmit the laser light L over a long distance.

The condensing part 13 is a condensing mechanism for condensing the laser light L onto the object O to be worked, such as a lens. The laser light L is condensed on the construction target O by the condensing unit 13, and a spot of the laser light L is formed. The condensing unit 13 may be composed of a plurality of optical components (for example, a plurality of lenses, a mirror for changing the angle).
The spot diameter of the laser light L can be adjusted by controlling the condensing part 13 (for example, changing the distance between the lens and the object O to be processed).

The object to be processed O is the object to be processed by laser peening and is held by the holding/moving unit 14 .
It is preferable that the surface of the object O to be applied has a liquid (for example, water) of 0.1 mm or more. This is for confining plasma generated by laser ablation.
For this reason, a nozzle or the like for supplying a liquid (such as water) to the surface of the object O to be applied may be provided.
Further, a nozzle for ejecting liquid may be provided at the tip of the condensing section 13 . Stable laser peening is facilitated by sending the liquid ejected from the nozzle to the object O coaxially with the laser beam L.
As already mentioned, when the liquid is water, it is preferable to use the second harmonic of the YAG laser.

The holding/moving unit 14 is a mechanism for holding and moving the construction target O. As shown in FIG. The holding/moving unit 14 moves the construction target O during construction, so that the construction target O can be scanned with the laser light L.
By using the holding/moving unit 14, as shown in FIG. 2, the laser spot Sp can be moved along the laser light drive locus T, and the working range A can be processed with the laser.
By changing the moving speed of the holding/moving unit 14, the irradiation density (pulse density: density of pulse laser irradiation per unit area) in the working area A can be adjusted. The irradiation density (pulse density) is determined by the pulse cycle of the laser oscillator 11 and the moving speed of the object O to be processed.

Note that the laser beam L may be moved without using the holding/moving unit 14 (the object O to be worked is not moved), or both may be moved. Moreover, the irradiation angle of the laser beam L with respect to the surface of the construction target O may be configured to be changeable. In this case, the optical transmission section 12 and the light condensing section 13 can be moved. For example, an optical fiber is used for the optical transmission section 12, and a movable laser irradiation head including the laser light emitting end of the optical fiber and the condensing section 13 is provided. If the construction target O is moved relative to the laser beam L, scanning of the laser spot Sp becomes possible.

The control unit 15 controls the entire laser peening apparatus 10 (the laser oscillator 11, the optical transmission unit 12, the light collecting unit 13, the holding/moving unit 14). , a drive unit 19 .

The input unit 16 is input means for inputting the material (identification information described later) and physical property parameters of the construction target O, or data reading means. Input means are, for example, a keyboard and a touch panel. The data reading means is, for example, a drive that reads data from a medium such as a memory or disk.
The input unit 16 can also be used to input data (for example, residual stress measurement data) to the DB storage unit 17 .

The DB storage unit 17 is storage means such as a memory or a hard disk, and stores a database relating to laser peening.
The database contains information such as:
・Physical property data (see Fig. 3)
・Residual stress data (residual stress profile, see Figures 4 to 6)

As shown in FIG. 3, the physical property data includes the material (here, SUS316L, pure Al, 12Cr steel, Alloy625, 718, 600) and its physical properties (for example, density, Young's modulus, Poisson's ratio, bulk modulus, shear elastic modulus, specific heat, thermal conductivity) are expressed correspondingly. This material name (for example, SUS316L) is identification information for identifying the material.
The physical properties of these materials can be used to calculate residual stress from impact pressure (step S22 in FIG. 7), which will be described later.
In addition, it is preferable that the physical property data include yield stress. This is because the yield stress information is used in the selection of the impact pressure (step S21 in FIG. 7), which will be described later.

The residual stress data represents the corresponding relationship among the material of the object O to be worked, the working conditions of laser peening, the residual stress imparted to the object O to be worked, and the depth of the object O to which the residual stress is imparted. Here, the residual stress data is represented by a residual stress profile representing the relationship between the depth of the construction target O and the residual stress. 4 to 6, the horizontal axis indicates the depth from the surface of the object O, and the vertical axis indicates the measured residual stress.
The residual stress in the depth direction of the object O can be measured by an X-ray method (combined with etching), a perforation method, or the like. In the former, electropolishing is used to polish the surface of the object O so as not to cause stress release as much as possible, and the residual stress is determined by X-ray diffraction.

4 to 6 show the relationship between material, application conditions (pulse energy, spot diameter, and irradiation density), residual stress, and depth (distance from surface).
In FIG. 4, pulse energy, spot diameter, and irradiation density are changed for 12Cr steel (graphs G11 and G12).
G11: Stress measurement results of 12Cr steel subjected to laser peening with a pulse energy of 70 mJ, a spot diameter of φ0.7 mm, and an irradiation density of 27 pulses/mm ² G12: A laser with a pulse energy of 70 mJ, a spot diameter of φ0.7 mm, and an irradiation density of 45 pulses/ ^mm Stress measurement results of peened 12Cr steel

In FIG. 5, the pulse energy, spot diameter, and irradiation density are varied for the 706 alloy (graphs G21 to G24). However, the pulse energy is relatively high.
In FIG. 6, for the 706 alloy, the pulse energy and spot diameter are fixed and the irradiation density is changed (graphs G31 to G34). However, the pulse energy is relatively low.

G21: Stress measurement results of 706 alloy subjected to laser peening with a pulse energy of 300 mJ, a spot diameter of φ0.8 mm, and an irradiation density of 200 pulses/mm ² G22: Laser with a pulse energy of 300 mJ, a spot diameter of φ0.8 mm, and an irradiation density of 100 pulses/mm ² Stress measurement result of peened 706 alloy G23: Stress measurement result of laser peened 706 alloy with pulse energy of 200 mJ, spot diameter of φ0.6 mm, irradiation density of 100 pulses/mm ² G24: Pulse energy of 200 mJ, spot diameter of φ0.6 mm, irradiation Stress measurement results for 706 alloy laser peened at a density of 50 pulses/ ^mm2

G31: Stress measurement results of 706 alloy subjected to laser peening with a pulse energy of 20 mJ, a spot diameter of φ0.3 mm, and an irradiation density of 720 pulses/mm ² G32: A laser with a pulse energy of 20 mJ, a spot diameter of φ0.3 mm, and an irradiation density of 360 pulses/ ^mm Stress measurement result of peened 706 alloy G33: Stress measurement result of 706 alloy subjected to laser peening with pulse energy of 20 mJ, spot diameter of φ0.3 mm, irradiation density of 200 pulses/mm ² G34: pulse energy of 20 mJ, spot diameter of φ0.3 mm, irradiation Stress measurement results for 706 alloy laser peened at a density of 100 pulses/ ^mm2

The calculation unit (selection unit) 18 determines (selects) construction conditions (step S15 described later).
That is, by using a plurality of residual stress profiles with different materials and construction conditions (pulse energy, spot diameter, irradiation density), the material of the construction target O and the desired residual stress conditions (desired residual stress, desired depth It is possible to determine (select) the construction conditions according to the

As will be described later, the calculation unit 18 also calculates impact pressure corresponding to residual stress conditions (desired residual stress, desired depth), calculates construction conditions, and determines whether construction is possible (steps S21 to S26). The details of this will be described later.
The calculation unit 18 can be configured from hardware such as a processor (for example, CPU: Central Processing Unit) and software such as a program.

The driving unit 19 drives and controls the laser oscillator 11, the optical transmission unit 12, the light collecting unit 13, and the holding/moving unit 14 according to construction conditions.
The driving unit 19 drives and controls the laser oscillator 11, the optical transmission unit 12, the light collecting unit 13, and the holding/moving unit 14, so that the construction conditions (pulse energy, spot diameter, irradiation density, etc.) can be changed. can.

Note that the laser peening apparatus 10 may include a display device (for example, a liquid crystal display device, an EL display device) for displaying information. The display device can be used to present construction conditions and setting conditions, which will be described later, to the user.

FIG. 7 is a flow chart showing the procedure of the laser peening method using the laser peening apparatus 10. As shown in FIG. This procedure is described below.

(1) First, input the material information of the construction target O (step S11). Next, a residual stress condition to be applied is input (step S12).

This material information is, for example, identification information for identifying the material (for example, the name of the material) and physical property information of the material. The physical property information is all or part of the density, Young's modulus, Poisson's ratio, bulk modulus, shear modulus, specific heat, thermal conductivity (yield stress if necessary) shown in FIG.
Depending on the case, a) identification information only, b) identification information and physical property information, or c) physical property information only can be appropriately selected and input. The input unit 16 receives identification information of the material of the construction target O, for example.

The residual stress conditions include the residual stress to be imparted and the depth of the object O to which the residual stress is imparted.
Optionally, a) residual stress only, b) residual stress and depth, and c) depth only can be selected and input as appropriate. The input unit 16 receives, for example, desired residual stress (desired depth, if necessary) information.

(2) It is determined whether or not the input material information exists in the physical property data (step S13).
For example, if the input material information is identification information, the identification information in the physical property data is searched.
If the determination is "Yes", the input material information is used. On the other hand, if the determination is "No", information on materials close to the input material information is selected from the physical property data (step S14).

Whether or not the materials are close to each other is determined by comparing the physical property values of the materials. If the difference in physical property values between the materials is less than the reference value, the materials may be considered close. If there are multiple nearby materials, the closest material is selected.

Here, since materials have a plurality of types of physical property values, there is a problem in comparing materials. Here, density is preferentially used among physical properties. Density has a large effect on laser peening and is easy to measure. Even if all the physical property values of the construction target O are unknown, the density can be easily measured.
When there are a plurality of materials having densities close to those of the construction target O, other physical property values can be used to determine the degree of proximity between the materials.

In addition, although some physical property values of the material of the construction target O are known, if it is insufficient for the calculation of the residual stress (step S22) described later, the physical property data can be approximated based on the known physical property values. You can choose the material you want.

When a material close to the construction target O is selected from the physical property data based on the physical property values, it is not necessary to use all the physical property values of the selected material as they are. That is, if a part of the physical property value of the material of the construction target O is known, the physical property value may be used to correct the physical property value of the selected material. For example, the physical property value of the selected material is corrected based on the difference in physical property value between the material of the construction target O and the selected material.

(3) It is determined whether or not the construction condition corresponding to the input residual stress condition can be selected from the residual stress data (whether it exists in the residual stress data) (step S15).

Whether the construction condition can be selected from the residual stress data (whether it exists in the residual stress data) is determined, for example, as follows.
If the material is 12Cr steel and the maximum compressive stress value is -500 MPa or more, either of the conditions of graphs G11 and G12 in FIG. 4 may be used. On the other hand, when the depth of compressive stress is 1000 μm, there is no construction condition within the range of residual stress data.

In the 706 alloy shown in FIGS. 5 and 6, the depth of compressive stress can be selected with a certain degree of freedom from the range of 400 μm to 1000 μm or more by changing the pulse energy, spot diameter, and irradiation density.
If the conditions are within the range shown in FIG. 5, the conditions for a depth of 1000 μm or more can be selected.
In addition, within the condition range shown in FIG. 6, it is possible to select conditions under which a compressive stress of −1000 MPa or more can be applied at a compressive stress depth of 500 μm or less. For example, it is useful when the thickness of the object O to be applied is thin and it is desired to prevent deformation due to laser peening.

(4) If the determination in step S15 is "Yes", construction conditions are selected based on the residual stress data. After that, based on the construction conditions, setting conditions for each construction means (laser oscillator 11, optical transmission unit 12, light collecting unit 13, holding/moving unit 14) are determined (step S16), setting conditions are input, and construction is performed. is performed (steps S17 and S18).
The selected or determined construction conditions and setting conditions may be presented to the user as necessary. That is, the laser peening apparatus 10 can be equipped with a display device that displays such recommended information.

(5) When the construction condition corresponding to the residual stress condition does not exist in the residual stress data (when the judgment in step S15 is "No"), the construction condition is determined based on the analysis (steps S21 to S25). .

That is, the residual stress that can be imparted is analytically obtained based on the physical property values of the material. At this time, repetitive calculations (a kind of convergence calculation) are performed to identify the impact pressure that satisfies the residual stress condition (steps S21 to S24).

1) Selection of impact pressure (step S21)
The calculation unit 18 selects an impact pressure equal to or higher than the yield stress of the object O to be constructed.
This impact pressure refers to the pressure applied to the surface of the object O during laser ablation. As a result of applying the impact pressure to the object O, stress remains in the object O after the laser ablation (after the impact pressure disappears) (residual stress is applied).

A value equal to or higher than the yield stress of the construction target O is selected for the impact pressure. This is for imparting residual stress to the surface of the object O to be applied. If the impact pressure is smaller than the yield stress, the construction target O returns to its initial state after the impact pressure disappears, and no residual stress is applied.

However, the impact pressure selected here may be a provisional value. As will be described later, the residual stress (and the depth if necessary) is calculated based on the impact pressure (step S22), and if these values satisfy the residual stress condition (step S23), the selected impact pressure is appropriate. There will be
That is, the initially selected impact pressure is an initial value, and its accuracy is not critical. For example, the yield stress may be multiplied by a constant greater than 1 to obtain the impact pressure.

2) Calculation of residual stress (step S22)
The calculator 18 calculates the residual stress based on the impact pressure.
This calculation can be performed by numerical calculation using a linear dynamics model. That is, the energy introduced into the material by laser peening is small and localized. Therefore, the strain induced in the material is very small, and macroscopic deformation does not occur. Therefore, the residual stress can be calculated by approximate linear calculation.

For example, using the physical property values in the physical property data, numerical calculations are performed by the finite element method or the like for a dynamic model with impact pressure as a boundary condition. As a result. It is calculated how the impact pressure applied from the surface of the object O propagates therein and how it remains after the impact pressure disappears (residual stress, depth).

3) Determining whether residual stress conditions are satisfied (step S23)
The calculator 18 determines whether the calculated residual stress satisfies the residual stress conditions (desired residual stress, depth).

Whether or not the residual stress condition is satisfied can be determined by whether or not the difference D between the calculated residual stress or the like and the desired residual stress or the like is smaller than the reference value St. If the absolute value of this difference D is smaller than the reference value St (|D|<St), it can be determined that the residual stress condition is satisfied.

When both the residual stress and the depth are problematic, the differences D1 and D2 between the calculated values and the desired values are obtained for both, and if these absolute values are smaller than the respective reference values St1 and St2 (|D1| , and |D2|<St2), it can be determined that the residual stress condition is satisfied.

If this judgment is "Yes", it means that the impact pressure that satisfies the required residual stress condition has been obtained.
On the other hand, if the determination is "No", the impact pressure is changed (step S24), the residual stress is calculated, and it is determined again whether the residual stress condition is satisfied (steps S21 to S23).

Normally, the initial value of the impact pressure is set to a relatively small value, and the impact pressure is gradually increased. However, if the calculated residual stress is too large, it is preferable to reduce the impact pressure. For example, by changing the impact pressure based on the difference between the calculated residual stress and the desired residual stress, the number of times it takes to reach the impact pressure that satisfies the residual stress condition can be reduced (acceleration of convergence).

This change in impact pressure, calculation of residual stress, and judgment as to whether the residual stress condition is met are repeated until an impact pressure that satisfies the required residual stress condition is obtained.

(6) Calculation of construction conditions based on impact pressure (step S25)
The calculator 18 calculates construction conditions based on the obtained impact pressure.
For this calculation, various calculation formulas (formulas (1) to (4) described later) showing the relationship between the impact pressure and the laser peening conditions can be used.

It is known that the impact pressure due to laser ablation is generally represented by formula (1) (reference: for example, Lindl, Phys. Plasma 2. 3933 (1995))
P=860×(I/10 ¹⁴ W/cm ² ) ^2/3 ×(λ/1 μm) ^−2/3
... formula (1)
Here, I: Focused intensity of laser beam L (10 ¹⁴ W/cm ² )
λ: Laser wavelength (μm)

Also, under the following conditions, the impact pressure is expressed by the formula (2) Laser intensity: 3×10 ⁻⁶ to 7×10 ¹³ W/cm ²
Pulse width: 1.5ms~500ps
Wavelength: 10.6 μm to 248 nm
Pulse energy: 100mJ to 10kJ

P=b×(I′λ√τ) ⁿ ×I′ Formula (2)
Here, I': Laser intensity (GW/cm ² )
λ: Laser wavelength (μm)
τ: Laser pulse width (ns)
b, n: Material constants (changes depending on the material)

When plasma generated by ablation is confined using a medium such as water, the generated pressure P' is expressed by the following equation (3).
P′=0.01×(α/(2α+3)) ^1/2 ×Z ^1/2 ×I ^1/2 Equation (3)
Z (g/cm ² s): Impact impedance α: Percentage of internal energy obtained by laser irradiation that is converted to thermal energy

When water is used as the medium, the impact pressure P' _W (GPa) is represented by Equation (4).
P′ _W = 1.02×I ^1/2 Formula (4)
In other words, for underwater laser peening, the impact pressure that can be introduced from the material surface can be calculated by determining the laser intensity. Also, based on this formula, the impact pressure corresponding to the medium can be calculated.

In this manner, the condensed intensity of the laser beam L that can generate the selected impact pressure can be calculated. The calculation unit 18 obtains the focused intensity of the laser beam L by calculation based on the selected impact pressure, and determines working conditions such as pulse energy, spot diameter, and irradiation density that can theoretically generate the selected impact pressure. to decide.

(7) Judgment of workability (step S26)
The calculation unit 18 determines whether the construction conditions calculated in this way can be constructed by the hardware of the laser peening apparatus 10 (the laser oscillator 11, the optical transmission unit 12, the light collection unit 13, and the holding/moving unit 14). .

That is, the calculation unit 18 calculates the operating means (laser oscillator 11, optical transmission unit 12, light collecting unit 13, holding/moving unit 14) based on the calculated operating conditions (pulse energy, spot diameter, irradiation density, etc.). Determine the setting conditions for each. Then, it is determined whether or not this set condition exceeds the constraint conditions of the laser oscillator 11, the optical system (the optical transmission unit 12, the light collecting unit 13), and the like.
More specifically, the constraint conditions are the energy of the laser oscillator 11, the speed of changing the relative position and angle between the object O and the laser beam L, the movable range and possible postures of the object O and the laser beam L, and the laser beam. Interference with the construction target O of the irradiation head and surrounding structures, etc. can be mentioned. When the construction target O is a plate material, etc., the movable range and interference are not so much of a problem, but when construction is performed on a complex-shaped surface of the construction target O, or when the construction target O is a device installed at the site, etc. Range and interference can be constraints.

If this judgment is "Yes", input of setting conditions and implementation of construction are performed (steps S17 and S18).
On the other hand, if the determination is "No", the process returns to step S12 and the residual stress condition is re-input. That is, the user is presented with the fact that it is impossible to apply the originally input residual stress condition, and is prompted to input a different residual stress condition (residual stress review request).

If the calculated construction conditions, and thus the set conditions of the construction means, are not within the workable range, the user may be allowed to input the set conditions within the workable range. In this case, for example, it is presented to the user that construction cannot be performed under the calculated construction conditions, and prompts the user to input different construction conditions (request to review the construction conditions).
For example, if the maximum pulse energy of the laser oscillator 11 is 400 mJ, the user can input in the range of 400 mJ or less in step S17 (a restriction is added so that a value exceeding 400 mJ cannot be selected).

As described above, when it is determined in step S15 that the working conditions cannot be selected, laser peening is performed using materials and working conditions that are not shown in the stored residual stress data. In such a case, the residual stress of the newly constructed object O is measured, input from the input unit 16 as a residual stress profile, accumulated in the DB storage unit 17, and the residual stress data can be further enriched.

(Second embodiment)
A laser peening system according to a second embodiment will be described with reference to FIG.
In the laser peening system, a plurality of laser peening devices 10(1) and 10(2) are connected to a master control unit 31 via an internet line C.

The master control unit 31 has a master database 32, and can transmit, receive, and manage data with all the laser peening devices 10 connected via the Internet line C. FIG.

The master database 32 can collect and accumulate physical property data, residual stress data, etc. from the DB storage units 17 of all the laser peening apparatuses 10 connected by the Internet line C. FIG.

Further, when the master control unit 31 issues permission, the control unit 15 of the laser peening apparatus 10 can access the master database 32 via the Internet line C. That is, it is possible to download and utilize physical property data and construction conditions corresponding to residual stress data that are not stored in the DB storage unit 17 .

(Third embodiment)
A laser peening system according to a third embodiment will be described with reference to FIG. This embodiment differs from the first embodiment particularly in the processes of steps S12 and S26.

In step S12 of the present embodiment, different residual stress conditions can be set depending on the part of the object O to be worked (worked part). For example, if the object O has a complicated shape, if the properties and materials differ depending on the part (for example, a welded part), or if a specific part of the object O is placed in a particularly severe environment, the residual stress varies depending on the part. is sometimes desired.
Also, even when trying to apply the same residual stress, if the construction target O has different properties or materials in the middle (for example, a welded portion), or if the constraint conditions are different (for example, most of them can be irradiated with the laser beam L at a vertical angle. However, there may be cases where it is necessary to obliquely irradiate the laser light L on some parts due to circumstances such as the surrounding environment, and the same spot shape cannot be obtained.
In such cases, it is necessary to change the construction conditions during construction. In order to change the construction conditions during construction, for example, the irradiation density is changed by changing the relative position change speed of the construction target O and the laser light L, the irradiation angle of the laser light L is changed, and the light collecting unit 13 is changed. The spot diameter is changed by control.

Next, in step S26 of this embodiment, it is also determined whether the construction conditions can be changed during construction. For example, assuming that residual stress conditions A and B are included in one construction process, and construction conditions A and B (first and second construction conditions) corresponding to these are calculated in step S25, construction condition A , B is not only determined whether construction is possible, but also whether or not the construction conditions during the transition from construction conditions A to B exceed the constraint conditions.
For example, when changing the construction condition from A to B by changing the irradiation angle, the angle change speed and the angle that cannot be realized under transitional conditions (the movable range of the laser irradiation head, the laser irradiation head and the construction target) O interference). In addition, it is determined whether or not the compressive residual stress applied under the construction conditions during the transition from construction conditions A to B poses no problem (for example, whether it falls outside the preset allowable range).

According to this embodiment, it is possible to automatically calculate the construction conditions or determine whether construction can be performed for construction processes including different residual stress conditions. In addition, it is possible to determine whether or not construction can be performed even when the construction conditions are changed in response to changes in the residual stress conditions, which is a transitional period at the time of the change. Thus, even if each of the construction conditions determined based on different residual stress conditions and the like is a workable construction condition, it is possible to prevent the construction from falling into an unworkable state in the middle of changing the construction conditions.

While several embodiments of the invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the scope of claims and its equivalents.

In order to simplify the explanation, the spot of the laser beam L is circular unless otherwise specified in each embodiment, and the spot diameter is a parameter of the construction conditions, but the shape of the spot is not limited to this. Depending on the irradiation angle and the optical components used in the condensing section 13, the shape may be elliptical or nearly rectangular. What is important is the energy density determined by the pulse energy and the area of the spot, and the working condition is the area of the spot rather than the diameter of the spot.

10: laser peening device, 11: laser oscillator, 12: optical transmission unit, 13: light collecting unit, 14: holding/moving unit, 15: control unit, 16: input unit, 17: DB storage unit, 18: calculation unit , 19: drive unit

Claims (13)

A laser irradiation device that applies a pulse laser to a construction target to impart residual stress;
an input unit that receives information on the material to be constructed and the desired residual stress;
a storage unit that stores residual stress data representing correspondence relationships among materials, construction conditions, and residual stress;
a selection unit that selects a construction condition corresponding to the construction target material and the desired residual stress based on the residual stress data;
and
The selection unit
If the material to be worked cannot be found in the residual stress data, selecting a material close to the material to be worked from within the residual stress data.
Laser processing equipment. the input unit receives information about the material to be constructed, the desired residual stress, and a desired depth at which the residual stress is applied;
wherein the residual stress data represents a correspondence relationship between material, construction conditions, residual stress, and depth;
2. The laser processing apparatus according to claim 1, wherein the selection unit selects construction conditions corresponding to the construction target material, the desired residual stress, and the desired depth based on the residual stress data. A laser irradiation device that applies a pulse laser to a construction target to impart residual stress;
an input unit that receives information on the material to be constructed and the desired residual stress;
a storage unit that stores residual stress data representing correspondence relationships among materials, construction conditions, and residual stress;
a selection unit that selects a construction condition corresponding to the construction target material and the desired residual stress based on the residual stress data;
and
If the selection unit cannot find the construction condition corresponding to the material and the desired residual stress in the residual stress data, the impact pressure corresponding to the desired residual stress is calculated, and construction is performed based on the impact pressure. A laser processing apparatus further comprising a calculator for determining conditions. the input unit receives information about the material to be constructed, the desired residual stress, and a desired depth at which the residual stress is applied;
wherein the residual stress data represents a correspondence relationship between material, construction conditions, residual stress, and depth;
The selection unit selects construction conditions corresponding to the construction target material, the desired residual stress, and the desired depth based on the residual stress data.
4. The laser processing apparatus according to claim 3 . The calculation unit
Selecting an impact pressure equal to or higher than the yield stress of the construction target,
calculating the residual stress applied to the construction object based on the impact pressure;
determining whether the calculated residual stress corresponds to the desired residual stress;
5. The laser processing apparatus according to claim 3 , wherein when the calculated residual stress corresponds to the desired residual stress, the impact pressure is set to the impact pressure corresponding to the desired residual stress. The calculation unit
changing the impact pressure if the calculated residual stress does not correspond to the desired residual stress;
recalculating the residual stress applied to the construction object based on the changed impact pressure;
6. The laser processing apparatus according to claim 5, wherein when the recalculated residual stress corresponds to the desired residual stress, the changed impact pressure is set to the impact pressure corresponding to the desired residual stress. The storage unit further stores physical property data representing materials and physical properties in correspondence,
The calculation unit
Based on the physical property data, select physical properties corresponding to the material to be constructed,
calculating the residual stress imparted to the construction object based on the impact pressure and the selected physical properties;
The laser processing apparatus according to claim 5 or 6. The calculation unit
8. The laser processing apparatus according to claim 7, wherein if the material to be processed cannot be found in the physical property data, physical properties of a material close to the material to be processed are selected from the physical property data. The calculation unit compares the determined construction conditions with the constraint conditions to determine whether or not construction is possible. requesting a review of conditions or a review of the desired residual stress entered in the input unit;
The laser processing apparatus according to any one of claims 3 to 8. The calculation unit determines a first construction condition as the construction condition for the first construction site to be constructed, determines a second construction condition as the construction condition for the second construction site to be constructed, and determines the first construction condition as the construction condition for the second construction site to be constructed. Regarding the construction condition, the second construction condition, and the construction condition in the middle of transition from the first construction condition to the second construction condition, it is checked against the constraint conditions to determine whether construction is possible.
The laser processing apparatus according to claim 9. 11. The laser processing apparatus according to any one of claims 1 to 10, wherein when the residual stress data does not contain the material of the construction target, a measurement result of the residual stress in the construction target is added to the residual stress data. . A laser processing method for imparting residual stress by irradiating a laser beam to a construction object,
inputting information on the material to be constructed and the desired residual stress;
selecting a construction condition corresponding to the material to be constructed and the desired residual stress based on residual stress data representing the relationship between the material, construction conditions, and residual stress;
and
In the step of selecting the construction conditions, if the material to be constructed cannot be found in the residual stress data, a material close to the material to be constructed is selected from the residual stress data.
Laser processing method. A laser processing method for imparting residual stress by irradiating a laser beam to a construction object,
inputting information on the material to be constructed and the desired residual stress;
selecting a construction condition corresponding to the material to be constructed and the desired residual stress based on residual stress data representing the relationship between the material, construction conditions, and residual stress;
and
In the step of selecting the construction conditions, if construction conditions corresponding to the material and the desired residual stress cannot be found in the residual stress data, an impact pressure corresponding to the desired residual stress is calculated, and the impact pressure determine the construction conditions based on
Laser processing method.

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