Repair method, program, and repair device

Abstract

A repair method according to the present disclosure includes: a step of forming a repair groove in a repair object by removing a crack-containing region including a crack from the repair object; a step of supplying a powder material to the repair groove and additively manufacturing a formed layer by melting the powder material in the repair groove; and a step of performing peening process which applies an impact to the formed layer to impart a residual compressive stress to the formed layer each time the formed layer is formed a certain layer thickness.

Description

Repair method, program, and repair device

[0001] This application claims priority to Japanese Patent Application No. 2024-069732, filed on April 23, 2024, the contents of which are incorporated herein by reference.

[0002] Turbine blades for gas turbines, aircraft engines, and the like are made of high-strength materials such as nickel-based superalloys. However, these materials have extremely low weldability. Therefore, hot cracking can occur in the turbine blades during weld repair.

[0003] Patent Document 1 discloses a repair method for repairing a turbine blade of a gas turbine. This repair method includes a notch forming step, a first welding step, and a second welding step. The notch forming step forms a notch by removing a crack. The first welding step fills the notch with a first welding material by overlay welding using a first welding material. The second welding step, after the first welding step, fills the notch with a second welding material by overlay welding using a second welding material. The second weld material has higher high-temperature strength than the first weld material. Furthermore, the first weld material has higher weldability than the second weld material. Therefore, the repair method of Patent Document 1 can absorb cracks due to residual stress after welding using the overlay portion of the first weld material, while ensuring the strength of the turbine blade through the overlay portion of the second weld material.

[0004] Patent No. 6734462

[0005] However, in the repair method of Patent Document 1, the strength of the buildup portion of the first weld material is low. Furthermore, because the first weld material and the second weld material are made of different materials from the turbine blade body, the strength may decrease compared to before the repair. Furthermore, because a heat treatment with a large heat input, such as Tungsten Inert Gas (TIG) welding, is performed, the turbine blade may not be repaired accurately. Therefore, there is room for improvement in terms of improving repair accuracy.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a repair method, program, and repair device that can repair an object to be repaired with high precision.

[0007] In order to solve the above problem, the repair method disclosed herein includes the steps of forming a repair groove in the repair target by removing a crack-containing area that includes a crack in the repair target, supplying powder material to the repair groove and melting the powder material in the repair groove to additively manufacture a modeling layer, and performing a peening process on the modeling layer each time the modeling layer is formed to a predetermined layer pitch, thereby imparting residual compressive stress to the modeling layer.

[0008] The program disclosed herein causes a computer to perform the following steps: forming a repair groove in the repair target by removing a crack-containing area that includes a crack in the repair target; supplying powder material to the repair groove and melting the powder material in the repair groove to additively manufacture a modeling layer; and performing a peening process on the modeling layer each time the modeling layer is formed to a predetermined layer pitch, thereby impacting the modeling layer and imparting residual compressive stress to the modeling layer.

[0009] The repair device according to the present disclosure comprises a groove forming device that forms a repair groove in the repair target by removing a crack-containing area that includes a crack in the repair target; an additive manufacturing device that supplies powder material to the repair groove and melts the powder material in the repair groove to additively manufacture a modeling layer; and a peening device that performs a peening process on the modeling layer by impacting the modeling layer each time the modeling layer is formed to a predetermined layer pitch, thereby imparting residual compressive stress to the modeling layer.

[0010] According to the repair method, program, and repair device disclosed herein, the repair target can be repaired with high precision.

[0011] FIG. 1 is a schematic configuration diagram of a repair device according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing an example of a peening device according to an embodiment of the present disclosure. FIG. 3 is a schematic diagram showing an example of a peening device according to an embodiment of the present disclosure. FIG. 4 is a control block diagram of a repair device according to an embodiment of the present disclosure. FIG. 5 is a flow diagram showing a procedure of a repair method according to an embodiment of the present disclosure. FIG. 6 is a flow diagram showing a procedure of a preparation process according to an embodiment of the present disclosure. FIG. 7 is a flow diagram showing a procedure of a peening process according to an embodiment of the present disclosure. FIG. 8 is a flow diagram showing a procedure of a finishing process according to an embodiment of the present disclosure. FIG. 9 is a schematic diagram showing an example of the flow of a repair method according to an embodiment of the present disclosure. FIG. 10 is a graph showing an example of residual stress of an additively manufactured part before a peening process according to an embodiment of the present disclosure. FIG. 11 is a graph showing an example of residual stress of an additively manufactured part that has been subjected to ultrasonic peening only once after formation of the additively manufactured part according to an embodiment of the present disclosure. FIG. 12 is a graph showing an example of residual stress of an additively manufactured part that has been subjected to ultrasonic peening for each layer pitch according to an embodiment of the present disclosure. FIG. 13 is a graph showing an example of residual stress of an additively manufactured part that has been subjected to shot peening only once after formation of the additively manufactured part according to an embodiment of the present disclosure. 1 is a graph showing an example of residual stress in an additively manufactured part subjected to laser peening according to an embodiment of the present disclosure; FIG. 2 is a graph showing an improvement in proof stress due to peening according to an embodiment of the present disclosure; FIG. 3 is a cross-sectional view showing an example of a repair groove according to an embodiment of the present disclosure; FIG. 4 is a hardware configuration diagram according to an embodiment of the present disclosure;

[0012] (Repair Device) A repair device 1, a repair method, and a program according to an embodiment of the present disclosure will be described below with reference to the accompanying drawings. The repair device 1 according to this embodiment is used to repair, for example, turbine blades of gas turbines and aircraft engines. Hereinafter, an object to be repaired by the repair device 1, such as a turbine blade, will be referred to as a repair target 2. The repair target 2 is formed, for example, from a metal material. Examples of materials for the repair target 2 include high-strength materials such as nickel-based superalloys.

[0013] Hereinafter, the three mutually orthogonal directions are defined as the X direction, the Y direction, and the Z direction. In one example of this embodiment, the Z direction is the "up-down direction." In this example, the +Z direction is the upward direction, and the -Z direction is the downward direction. In this example, the X direction and the Y direction are horizontal directions that are orthogonal to each other.

[0014] In the following, an embodiment will be described taking as an example a case where a crack 2a occurs on a surface of the repair target 2 facing the +Z direction, and the surface of the repair target 2 on which the crack 2a occurs extends in the X and Y directions. In addition, a region of the repair target 2 that includes the crack 2a is defined as a crack-containing region 2b.

[0015] As shown in FIG. 1 , the repair device 1 includes a stage 3 , a groove forming device 10 , an additive manufacturing device 20 , a peening device 30 , a sensor device 40 , a moving device 50 , and a control unit 60 .

[0016] (Stage) The stage 3 extends in the X and Y directions. The repair target 2 is placed on the surface of the stage 3 facing the +Z direction. The stage 3 may be fixed, or may be installed so as to be movable in the X, Y, and Z directions.

[0017] (Groove forming device) The groove forming device 10 forms a repair groove 5 in the repair object 2 by removing the crack-containing region 2b. The groove forming device 10 includes a cutting tool 11. The groove forming device 10 forms the repair groove 5 by scraping away the repair object 2 with the cutting tool 11. The repair groove 5 opens in the +Z direction. The repair groove 5 may be formed in a groove shape consisting of a flat surface, or may be formed in a curved surface shape.

[0018] (Layered Manufacturing Apparatus) The layered manufacturing apparatus 20 supplies the powder material 4 to the repair groove 5 and melts the powder material 4 in the repair groove 5 to layer-by-layer manufacture the manufacturing layer 6. The layered manufacturing apparatus 20 may be used not only for repairing the repair object 2 but also for manufacturing the repair object 2. The layered manufacturing apparatus 20 includes a powder supplying device 21 and a laser scanner 22.

[0019] (Powder Supply Device) The powder supply device 21 is disposed opposite the stage 3 in the Z direction. That is, the powder supply device 21 is disposed opposite the repair object 2 in the Z direction. The powder supply device 21 is disposed on the +Z direction side of the repair object 2. The powder supply device 21 contains the powder material 4 inside. The powder supply device 21 lays the powder material 4 in the repair trench 5 in the form of a thin layer. The powder supply device 21 moves in the X and Y directions while dropping the powder material 4 in the -Z direction. The powder supply device 21 scatters the powder material 4 inside the repair trench 5, and lays the powder material 4 uniformly within the powder (scattering type). The powder material 4 is, for example, a metal material.

[0020] (Laser Scanner) The laser scanner 22 is disposed opposite the stage 3 in the Z direction. That is, the laser scanner 22 is disposed opposite the repair target 2 in the Z direction. The laser scanner 22 is disposed on the +Z direction side of the repair target 2. The laser scanner 22 repeatedly selectively melts the powder material 4 by irradiating it with laser light 23 (modeling laser light) using one or more lasers, thereby forming a model from the powder material 4. In this embodiment, the laser scanner 22 irradiates the laser light 23 in the −Z direction toward the powder material 4 laid in the repair trench 5. Note that the laser scanner 22 does not necessarily irradiate the laser light 23 parallel to the −Z direction. For example, the laser scanner 22 may irradiate the laser light 23 in a direction inclined with respect to the −Z direction. The powder material 4 in the repair trench 5 is melted by the heat of the irradiation of the laser light 23, and a modeling layer 6 is additively manufactured in the repair trench 5. The modeling layers 6 are stacked in the Z direction to form an additively manufactured portion 7. This additively shaped part 7 is formed so as to fill the repair groove 5. Hereinafter, the stacking height h1 of this additively shaped part 7 in the stacking direction (Z direction) will be simply referred to as "stacking height h1."

[0021] (Peening Device) The peening device 30 is arranged opposite the stage 3 in the Z direction. That is, the peening device 30 is arranged opposite the repair object 2 in the Z direction. The peening device 30 is arranged on the +Z direction side of the repair object 2. The peening device 30 performs a peening process on the forming layer 6. The peening process is a process in which abrasive material 31 is sprayed onto the surface of the object to impact the forming layer 6.

[0022] Here, residual tensile stress is generated in the modeling layer 6 formed in the repair groove 5 when the molten powder material 4 solidifies. This residual tensile stress may cause cracks 2a, internal defects, etc. in the modeling layer 6. The peening device 30 applies residual compressive stress to the modeling layer 6 through the peening process, thereby reducing the residual tensile stress and suppressing the occurrence of cracks 2a, internal defects, etc. In this embodiment, the peening device 30 sprays abrasives 31 in the -Z direction to impact the surface of the modeling layer 6 facing the +Z direction. Note that the peening device 30 does not necessarily spray the abrasives 31 parallel to the -Z direction. For example, the peening device 30 may spray the abrasives 31 in a direction inclined relative to the -Z direction.

[0023] The peening device 30 performs peening on the surface of the modeling layer 6 in the +Z direction every time the modeling layer 6 is formed at a layering pitch h2. The layering pitch h2 here refers to the length period in the layering direction (Z direction) at which the modeling layer 6 is peened in the peeling process in step S2, which will be described later.

[0024] The method of peening can be selected appropriately depending on the situation. For example, the peening device 30 shown in FIG. 1 is a device that performs ultrasonic peening. This peening device 30 includes pins 31A that extend in the Z direction as abrasives 31. These pins 31A are formed, for example, from a metal material. The pins 31A are rod-shaped members that extend in the Z direction. The end face of the pins 31A in the −Z direction is formed into a curved surface that is convex in the −Z direction. Ultrasonic waves are applied to the pins 31A, causing them to vibrate in the Z direction. The peening device 30 applies an impact in the −Z direction to the modeling layer 6 by bringing the vibrating pins 31A into contact with the surface of the modeling layer 6.

[0025] 2, the peening device 30 may be, for example, a device that performs shot peening. In this case, the peening device 30 uses spheres 31B as the abrasives 31. The spheres 31B are, for example, hard balls. The peening device 30 applies an impact to the modeling layer 6 in the −Z direction by causing countless spheres 31B to collide with the surface of the modeling layer 6.

[0026] 3, the peening device 30 may be a device that performs laser peening, for example. In this case, the peening device 30 uses laser light 31C (peening laser light) as the abrasive 31. In laser peening, the laser light 31C is irradiated onto the surface of the modeling layer 6 with a liquid film 32 (e.g., a water film) spread over the surface of the modeling layer 6. This generates plasma 33 on the surface of the model. The vibration of the plasma 33 is then reflected by the liquid film 32 toward the surface of the modeling layer 6. This vibration of the plasma 33 applies an impact to the modeling layer 6 in the −Z direction.

[0027] (Sensor Device) The sensor device 40 acquires information about the repair target 2, such as the shape of the repair target 2, internal stress, and the presence or absence of scratches. For example, the sensor device 40 includes functional units such as a shape measurement sensor 41, a residual stress sensor 42, and a flaw detection sensor 43. The shape measurement sensor 41 measures the shapes of the crack 2a, repair groove 5, and modeling layer 6 that have occurred in the repair target 2, for example, by acquiring an image of the surface of the repair target 2 or measuring the distance in the Z direction at multiple measurement points on the surface of the repair target 2 using laser light (measurement laser light). The residual stress sensor 42 measures residual stress at each depth position (Z direction position in the illustrated example) by, for example, irradiating the repair target 2 with X-rays. The flaw detection sensor 43 detects scratches and defects inside the repair target 2 by irradiating and transmitting radiation through the repair target 2. The shape measurement sensor 41, the residual stress sensor 42, and the flaw detection sensor 43 may be provided integrally as one sensor device 40 as in the present embodiment, or may be provided separately. The sensor device 40 may also include a functional unit for acquiring information about the repair object 2 other than that described above.

[0028] (Moving Device) The moving device 50 has a guide 51, a first jig 52, a second jig 53, a third jig 54, and a fourth jig 55. The guide 51 and the stage 3 extend in the X direction and the Y direction.

[0029] The first jig 52 is attached to the guide 51. The first jig 52 extends from the guide 51 in the -Z direction. The first jig 52 is provided so as to be movable along the guide 51. The groove forming device 10 is attached to the first jig 52. As the first jig 52 moves along the guide 51, the groove forming device 10 moves in the X direction and the Y direction. The second jig 53 is attached to the guide 51. The second jig 53 extends from the guide 51 in the -Z direction. The second jig 53 is provided so as to be movable along the guide 51. The powder supplying device 21 is attached to the second jig 53. As the second jig 53 moves along the guide 51, the powder supplying device 21 moves in the X direction and the Y direction.

[0030] The third jig 54 extends from the guide 51 in the −Z direction. The third jig 54 is provided so as to be movable along the guide 51. The peening device 30 is attached to the third jig 54. As the third jig 54 moves along the guide 51, the peening device 30 moves in the X and Y directions. The fourth jig 55 is attached to the guide 51. The fourth jig 55 extends from the guide 51 in the −Z direction. The fourth jig 55 is provided so as to be movable along the guide 51. The sensor device 40 is attached to the fourth jig 55. As the fourth jig 55 moves along the guide 51, the sensor device 40 moves in the X and Y directions.

[0031] (Control Unit) As shown in FIG. 4 , the control unit 60 is connected to various devices constituting the repair apparatus 1, such as the groove forming device 10, the additive manufacturing device 20, the peening device 30, the sensor device 40, and the moving device 50. The control unit 60 is capable of transmitting and receiving information, signals, and commands to and from these devices constituting the repair apparatus 1. The control unit 60 controls these devices constituting the repair apparatus 1. For example, the control unit 60 transmits a command for an additive manufacturing process to the additive manufacturing device 20, and the additive manufacturing device 20 notifies the control unit 60 of the end of the additive manufacturing process. Furthermore, the control unit 60 transmits a command for a peening process to the peening device 30, and the peening device 30 notifies the control unit 60 of the end of the peening process. Furthermore, the control unit 60 controls the groove forming device 10, the additive manufacturing device 20, the peening device 30, and the moving device 50 based on information acquired by the sensor device 40.

[0032] (Procedure of Repair Method) An example of the repair method will be described below with reference to the flows in Figures 5 to 8 and the schematic diagram in Figure 9. Here, a rectangular plate-shaped test piece is used as the repair object 2, and the repair groove 5 is formed into a groove shape consisting of multiple flat surfaces, as shown in Figure 9. The depth of the repair groove 5 in the Z direction is set to 2.0 mm.

[0033] As shown in Fig. 5, a preparation process is first performed (step S1). In step S1, several pieces of data are acquired. Here, data are acquired using a test piece made of the same material and with the same shape as the actual repair target 2 used in steps S2 and later, and by forming a repair groove 5 of the same shape. It is desirable that the test piece used in step S1 be made of the same material and with the same shape as the actual repair target 2 used in steps S2 and later, but this is not necessarily the case. Similarly, for the repair groove 5, it is desirable that the repair groove 5 formed in step S1 be the same shape as the actual repair groove 5 formed in steps S2 and later, but this is not necessarily the case.

[0034] As shown in Fig. 6, in the flow of the preparation process (step S1), for example, first, the shape and material of the repair object 2, the additive manufacturing method, and the powder material 4 are set (step S10). Here, for example, the same powder material 4 as the material of the repair object 2 is selected. Furthermore, for example, the Powder Bed Fusion (PBF) method is selected as the additive manufacturing technology method. Furthermore, additive manufacturing parameters are set as shown in Table 1.

[0035]

[0036] For example, if the additive manufacturing device 20 forms the additive manufacturing portion 7 in the repair groove 5 using the parameters in Table 1, and the sensor device 40 acquires the residual stress of the additive manufacturing portion 7 formed in the repair groove 5 at each depth, residual stress data such as that shown in FIG. 10 is acquired. The data in FIG. 10 was acquired for the additive manufacturing portion 7 formed by forming multiple manufacturing layers 6, each having a thickness of, for example, several tens of micrometers, in the repair groove 5. In the example of FIG. 10 , residual tensile stress occurs throughout the entire depth range of the additive manufacturing portion 7, from 0 μm to 2000 μm. Specifically, residual tensile stress with a residual stress ratio of approximately +1 to +2 occurs in the depth range of 0 μm to 2000 μm. The residual stress ratio here refers to the ratio of residual stress to a reference value of tensile stress, for example, when tensile stress is positive and compressive stress is negative. Residual tensile stress may cause cracks 2a or internal defects in the additively manufactured part 7, so it is necessary to select an appropriate peening method and remove the residual tensile stress by peening.

[0037] After the additive manufacturing step S10, the peening method and peening conditions are set (step S11). In step S11, the peening method is selected by comprehensively assessing various conditions, such as the time and cost required for the peening, and the shape and material of the repair object 2. Below, the repair method will be described using an example in which ultrasonic peening is selected as the peening method in step S11.

[0038] After step S11, the sensor device 40 measures the penetration depth of the residual compressive stress caused by the peening process (step S12). In step S12, the peening device 30 performs peening once on the surface of the additively manufactured part 7 facing the +Z direction. The sensor device 40 then acquires the residual stress of the additively manufactured part 7 after the peening process for each depth. Here, the residual stress is acquired after the peening process is performed on the additively manufactured part 7 formed under the same conditions as the data in FIG. 10, for example.

[0039] For example, ultrasonic peening is performed on the surface in the +Z direction of the additively manufactured part 7 using the parameters shown in Table 2. Coverage indicates the percentage of the same area that is repeatedly processed, with the time spent peening the entire processing surface being set as 100%.

[0040]

[0041] As a result, residual stress data such as that shown in FIG. 11 is obtained. In the example of FIG. 11, residual compressive stress occurs in the additively manufactured part 7. Specifically, residual compressive stress with a residual stress ratio of approximately -2 to -4 occurs in the additively manufactured part 7 in the depth range of 0 μm to 500 μm. Furthermore, in the depth range of 500 μm to 2000 μm, the residual compressive stress decreases with increasing depth. At a depth of approximately 1500 μm, the residual compressive stress approaches 0. In the depth range of 1500 μm to 2000 μm, the residual compressive stress does not penetrate, and residual tensile stress remains. From FIG. 11, a penetration depth of approximately 1500 μm of the residual compressive stress due to ultrasonic peening is measured.

[0042] After step S12, the layer pitch h2 (the length period in the layering direction (Z direction) of the modeling layer 6 to which the peening process is performed) is set (step S13). In step S13, taking into account variations in the penetration depth of 1.5 mm and the influence of heat input during additive manufacturing, the control unit 60 sets the layer pitch h2 to a value greater than the melting depth of the modeling layer 6 already formed when the modeling layer 6 is formed, but smaller than the penetration depth of the residual compressive stress caused by the peening process. For example, the layer pitch h2 is set to 1.0 mm. With the above procedure, the flow of the preparation process (step S1) is completed.

[0043] 5, after the preparation process (step S1) is completed, the repair groove 5 is formed (step S2). In step S2, the groove forming device 10 removes the crack-containing region 2b including the crack 2a in the repair target 2, thereby forming the repair groove 5 in the repair target 2 (see the second row in FIG. 9).

[0044] After step S2, the control unit 60 evaluates the shape of the repaired groove 5 (step S3). In step S3, for example, the sensor device 40 acquires information such as the shape of the repaired groove 5, and the control unit 60 acquires information such as the uneven shape of the surface of the repaired groove 5 and the presence or absence of defects in the repaired groove 5 based on the information on the repaired groove 5 acquired by the sensor device 40. After step S3, the control unit 60 evaluates the stacking conditions (step S4). In step S4, for example, the control unit 60 calculates the thickness of one layer of the modeling layer 6 (layer thickness) and the number of layers based on the target value of the stacking height h1 of the additive manufacturing unit 7 and the information acquired in step S3. The thickness of one layer of the modeling layer 6 is, for example, approximately several tens of micrometers.

[0045] After step S4, the repair target 2 is set on the repair device 1 (step S5). In step S5, for example, fine adjustments of various parameters or fine adjustments of the positioning of the repair target 2 may be performed. Alternatively, step S5 may be omitted. After step S5, the control unit 60 sends a command for the additive manufacturing process to the additive manufacturing device 20, and the additive manufacturing device 20 performs the additive manufacturing process (step S6). In step S6, the additive manufacturing device 20 supplies the powder material 4 into the repair groove 5 and melts the powder material 4 in the repair groove 5 with the heat of the laser beam 23 to form the modeling layer 6. The additive manufacturing device 20 forms the modeling layer 6 up to a layer pitch h2 (here, 1.0 mm) (see the third row in FIG. 9 ). After step S6, the additive manufacturing device 20 sends a notification of the completion of the additive manufacturing process to the control unit 60, and the peening process is performed (step S7).

[0046] As shown in FIG. 7 , in the flow of the peening process (step S7), the control unit 60 first sends a peening command to the peening device 30, and the peening device 30 performs the peening process by impacting the modeling layer 6 (step S20) (see the fourth row in FIG. 9 ). Here, ultrasonic peening is performed using the parameters shown in Table 1. Step S7 imparts residual compressive stress to the modeling layer 6. After step S20, the sensor device 40 measures the peened surface (step S21). After step S21, the control unit 60 determines whether the peened surface is within quality control based on the information about the peened surface measured by the sensor device 40 (step S22). If the peened surface is not within quality control (step S22; NO), the process returns to step S20, and the peening process is performed again. If the peening-treated surface is within the quality control range (step S22; YES), the peening device 30 sends a notice of the end of the peening treatment to the control unit 60, and the flow of the peening treatment (step S7) ends.

[0047] In step S7, the peening process causes unevenness on the surface of the modeling layer 6, but in step S6, the additive manufacturing device 20 increases the heat input of the laser light 23, thereby suppressing the effect of the unevenness.

[0048] Returning to the flow of FIG. 5 , after the peening process (step S7) is completed, the sensor device 40 acquires information on the repair groove 5 and the modeling layer 6, and the control unit 60 determines whether the thickness of the modeling layer 6 has reached the required stacking height h1 based on the information acquired by the sensor device 40 (step S8). If the thickness of the modeling layer 6 has not reached the required stacking height h1 (step S8; NO), the process returns to step S5. Steps S5 to S8 are repeated until the thickness of the modeling layer 6 reaches the required stacking height h1 (see rows 5 and 6 of FIG. 9 ). In this manner, the peening process for each stacking pitch h2 (hereinafter referred to as the multilayer peening process) is performed. In this embodiment, the required stacking height h1 is 2.0 mm and the stacking pitch h2 is 1.0 mm, so steps S5 to S8 are executed twice.

[0049] When the thickness of the modeling layer 6 reaches the required stacking height h1 (step S8; YES), the modeling layer 6 is stacked up to the target stacking height h1, and the additive modeling part 7 is formed up to the surface of the repair object 2. After that, a finishing process is performed (step S9).

[0050] As shown in FIG. 8 , in the finishing process (step S9), for example, first, non-destructive testing is performed on the repair object 2 (step S30). In step S30, for example, a sensor device 40 irradiates the additively manufactured portion 7 with radiation to check for defects in the additively manufactured portion 7. After step S30, a heat treatment is performed on the repair object 2 (step S31). In step S31, stress within the repair object 2 is removed. After step S31, a finishing process is performed on the repair object 2 (step S32). In step S32, excess reinforcement is removed from the additively manufactured portion 7. After step S32, similar to step S31, non-destructive testing is performed on the repair object 2 (step S33). If the inspection fails in step S30 or step S33, for example, because a defect is detected, the additive manufacturing process and multilayer peening process are performed again using the same procedure. This completes the flow of the finishing process (step S9). Note that step S9 may be omitted in whole or in part as appropriate.

[0051] 5, after the finishing process (step S9) is completed, the repair method ends. With the above steps, the repair of the repair object 2 is completed.

[0052] After the repair is completed, residual stress data is acquired using the same procedure as in step S12, resulting in the results shown in Figure 12. In the example shown in Figure 12, it was confirmed that residual compressive stress was imparted throughout the entire depth range, and that residual tensile stress was reduced. It was also confirmed that the reduction in residual tensile stress prevented hot cracking and reheat cracking after heat treatment.

[0053] In the above repair method, ultrasonic peening is used as the peening process in step S11. However, shot peening may also be used as the peening process. In this case, when shot peening is performed on the surface of the additively manufactured part 7 in the +Z direction using, for example, the parameters shown in Table 3 in step S12, residual stress data such as that shown in FIG. 13 is acquired. In the example shown in FIG. 13, residual compressive stress occurs in the additively manufactured part 7. Specifically, residual compressive stress with a residual stress ratio of approximately -2 to -5 occurs in the depth range of 0 μm to 500 μm of the additively manufactured part 7. Furthermore, in the depth range of 500 μm to 2000 μm, the residual compressive stress decreases with increasing depth. At a depth of approximately 1500 μm, the residual compressive stress approaches 0. In the depth range of 1500 μm to 2000 μm, the residual compressive stress does not penetrate, and residual tensile stress remains. From FIG. 13, it is observed that the penetration depth of the residual compressive stress due to shot peening is about 1500 μm.

[0054]

[0055] Thereafter, taking into account that the penetration depth was 1.5 mm, the layer pitch h2 was set to 1.0 mm, and repair of the repair object 2 was performed using the same procedure as for ultrasonic peening. After the repair, residual stress data was acquired, and the data shown in Figure 14 was obtained. In the example of Figure 14, it was confirmed that shot peening also imparted residual compressive stress throughout the entire depth range, and that residual tensile stress was reduced. It was also confirmed that the reduction in residual tensile stress also prevented high-temperature cracking and reheat cracking after heat treatment.

[0056] Laser peening may also be selected as the peening process. In this case, in step S12, residual stress data such as that shown in FIG. 15 is acquired. In the example of FIG. 15, residual compressive stress occurs throughout the entire depth direction from 0 μm to 2000 μm in the additively manufactured part 7. Specifically, residual compressive stress of approximately −400 μm occurs near a depth of 0 μm in the additively manufactured part 7, and the residual compressive stress decreases as the depth increases. With laser peening, the residual compressive stress approaches 0 near a depth of 2000 μm. From FIG. 15, a penetration depth of approximately 2000 μm of residual compressive stress due to laser peening is measured.

[0057] Subsequently, considering the penetration depth of 2.0 mm, the layer pitch h2 was set to 2.0 mm, and repair of the repair object 2 was performed using the same procedure as ultrasonic peening. Because the layer height h1 and layer pitch h2 matched, peening was performed only once (single-layer peening). If the layer height h1 is 2.0 mm or greater, multi-layer peening is required, as with ultrasonic peening and shot peening. After the repair, residual stress data was obtained, and the data shown in Figure 15 was similar. Thus, it was confirmed that laser peening also imparts residual compressive stress throughout the entire depth range and reduces residual tensile stress. Furthermore, it was confirmed that the reduction in residual tensile stress also prevents hot cracking and reheat cracking after heat treatment.

[0058] Furthermore, as shown in FIG. 16 , an improvement in yield strength was confirmed by the peening treatment. FIG. 16 shows data when ultrasonic peening was performed as the peening treatment. Note that FIG. 16 shows the yield strength ratio after repair on the left side, and the yield strength ratio before repair on the right side. Here, the yield strength ratio refers to the ratio of the yield strength to a reference value, where the yield strength before repair is set as the reference value. The yield strength ratio in FIG. 16 is the ratio of the yield strength obtained at the repaired portion of the repair object 2. It can be seen from FIG. 16 that the yield strength of the repair object 2 improved after repair. This is thought to be because the peening treatment introduced plastic strain into the repair object 2, which promoted recrystallization during the heat treatment (step S31).

[0059] (Operation and Effects) The repair method having the above configuration has the following operations and effects.

[0060] The repair method of this embodiment includes the steps of forming a repair groove 5 in the repair target 2 by removing a crack-containing region 2b including a crack 2a in the repair target 2, supplying powder material 4 to the repair groove 5 and melting the powder material 4 in the repair groove 5 to additively manufacture a molding layer 6, and performing a peening process each time a molding layer 6 is formed at a predetermined layer pitch h2, in which an impact is applied to the molding layer 6 to impart residual compressive stress to the molding layer 6.

[0061] As a result, the repair device 1 can form the manufacturing layer 6 using additive manufacturing technology such as powder bed fusion (PBF). The heat input of PBF additive manufacturing technology is smaller than the heat input of build-up welding such as TIG (Tungsten Inert Gas) welding. This reduces residual stress in the repair object 2. Furthermore, the repair device 1 can repair the repair object 2 using the same high-strength powder material 4 as the repair object 2, thereby improving the strength of the repair object 2. Furthermore, the repair device 1 can perform a peening treatment on the surface of the manufacturing layer 6 at a predetermined layer pitch h2. As a result, the residual tensile stress is reduced throughout the entire manufacturing layer 6 by the residual compressive stress caused by the peening treatment. Therefore, the occurrence of cracks 2a is suppressed, and the repair device 1 can repair the repair object 2 with high precision. Furthermore, the peening treatment introduces plastic strain into the repair object 2, which promotes recrystallization during the heat treatment (step S31), thereby improving the high-temperature material properties.

[0062] The repair method of this embodiment further includes a step of setting the layer pitch h2 to be greater than the melting depth of the already formed forming layer 6 when the forming layer 6 is formed, and smaller than the penetration depth of the residual compressive stress due to the peening process.

[0063] As a result, the repair device 1 can prevent the peening-treated modeling layer 6 from melting when a new modeling layer 6 is formed. Furthermore, the residual compressive stress caused by the peening treatment is reliably imparted to the entire modeling layer 6. Therefore, the repair device 1 can reduce the residual tensile stress throughout the entire modeling layer 6 while minimizing time and costs.

[0064] In this embodiment, the method of the peening treatment can be selected appropriately depending on the situation. For example, the method of the peening treatment is selected by comprehensively judging various conditions such as the time and cost required for the peening treatment, the shape and material of the repair object 2, etc.

[0065] This allows the optimum peening treatment to be selected, improving work efficiency and reducing costs.

[0066] In the peening process of this embodiment, an impact can be applied to the modeling layer 6 by ultrasonic peening.

[0067] As a result, ultrasonic peening allows for simpler and lower-cost peening compared to other peening methods. Furthermore, ultrasonic peening can treat a wider area at once, thereby shortening work time. Furthermore, ultrasonic peening can reduce the surface irregularities of the modeling layer 6. Furthermore, ultrasonic peening uses a method of striking pins 31A. Therefore, compared to shot peening, which strikes countless spheres 31B, the abrasive material 31 does not scatter. Furthermore, unlike laser peening, there is no need to form a liquid film 32. Therefore, ultrasonic peening allows for more efficient repair work compared to other peening methods. Furthermore, the unevenness of the peened surface caused by ultrasonic peening is smaller than that caused by shot peening, thereby improving repair accuracy.

[0068] In addition, in the peening process of this embodiment, the forming layer 6 can also be impacted by shot peening.

[0069] As a result, shot peening can be performed more simply and at lower cost than other peening methods. Furthermore, because shot peening can treat a wide area at once, the work time can be shortened. In the case of shot peening, it is desirable to employ a spray method in which the powder material 4 is sprayed and supplied as described above, or to increase the heat input during additive manufacturing immediately after the peening process, as necessary.

[0070] In the peening process of this embodiment, the modeling layer 6 can also be impacted by laser peening.

[0071] As a result, compared to other peening methods, laser peening allows for finer peening and reduces deformation of the surface of the modeling layer 6. Therefore, laser peening can be performed even in areas where fine and high-precision work is required. Furthermore, the absolute value of the residual stress in the repair target after laser peening is smaller than that of other peening methods (see, for example, Figures 11, 13, and 15). Therefore, by selecting laser peening, the strength of the repair target is further improved.

[0072] The repair device 1 further includes a sensor device 40 that acquires information about the repair object 2, and a control unit 60 that controls the additive manufacturing device 20 and the peening device 30 based on the information acquired by the sensor device 40.

[0073] As a result, the repair device 1 can automatically and integrally control the additive manufacturing device 20 and the peening device 30 based on information about the repair object 2. This improves work efficiency. Furthermore, repair accuracy is maintained at a certain level or higher regardless of the skill of the worker. Therefore, quality improvement effects are expected.

[0074] In the above-described example of the repair method, the repair groove 5 is formed in a groove shape consisting of a flat surface, but the repair method is not limited to this. For example, as shown in Fig. 17, the repair groove 5 may be formed in a curved surface shape.

[0075] In this case, it is not necessary to form the repair groove 5 so that the repair groove 5 has a flat surface, and therefore it is possible to easily form the repair groove 5. Even if the repair groove 5 is formed to have a curved surface, the peening treatment can be performed for each layer pitch h2, so that the residual tensile stress is reduced and the occurrence of cracks 2a is suppressed.

[0076] (Hardware Configuration) The control unit 60 of the above-described embodiments is implemented in a computer 1100 as shown in Fig. 18. Fig. 18 is an example of a schematic block diagram showing the configuration of the computer 1100 in which the control unit 60 according to each embodiment is implemented. The computer 1100 includes a processor 1110, a main memory 1120, a storage 1130, and an interface 1140.

[0077] The operation of each functional unit of the control unit 60 and the above-mentioned processing (the processing of the repair method described above) are stored in the form of a program in the storage 1130. The processor 1110 reads the program from the storage 1130, loads it into the main memory 1120, and executes the above-mentioned processing (the processing of the repair method described above) in accordance with the program. The processor 1110 also allocates a storage area in the main memory 1120 in accordance with the program.

[0078] The program may be for realizing some of the functions to be performed by the computer 1100. For example, the program may be combined with other programs already stored in the storage 1130 or other programs implemented in other devices to perform the functions. Furthermore, the computer 1100 may include a custom large-scale integrated circuit (LSI) such as a programmable logic device (PLD) in addition to or instead of the above configuration. Examples of PLDs include programmable array logic (PAL), generic array logic (GAL), complex programmable logic device (CPLD), and field programmable gate array (FPGA). In this case, some or all of the functions realized by the processor 1110 may be realized by the integrated circuit.

[0079] Examples of storage 1130 include a magnetic disk, a magneto-optical disk, and a semiconductor memory. Storage 1130 may be an internal medium directly connected to the bus of computer 1100, or an external medium connected to computer 1100 via interface 1140 or a communication line. Furthermore, when this program is distributed to computer 1100 via a communication line, computer 1100 that receives the program may load the program into main memory 1120 and execute the above-mentioned processing. Storage 1130 may also be a non-transitory tangible storage medium.

[0080] The program may also be a program for realizing part of the above-described functions. Furthermore, the program may be a so-called differential file (differential program) that realizes the above-described functions in combination with another program already stored in storage 1130.

[0081] (Other Embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope that does not deviate from the gist of the present disclosure are also included.

[0082] In the above embodiment, the Z direction intersects with the up-down direction, but this is not limiting. The Z direction may intersect with the up-down direction.

[0083] In the above embodiment, the powder material 4 is the same as the material of the repair target 2, but this is not limiting. The powder material 4 may be a material different from the repair target 2 that imparts a new function, such as oxidation resistance or wear resistance, to the repair target 2.

[0084] In the above embodiment, the additive manufacturing technology may be a method other than PBF as long as the heat input is smaller than that of overlay welding such as TIG welding. The powder supply device 21 may lay the powder material 4 in the repair trench 5 by a blade method using a recoater instead of a spray method.

[0085] In the above embodiment, the control unit 60 automatically controls the groove forming device 10, the additive manufacturing device 20, the peening device 30, and the moving device 50 based on information acquired by the sensor device 40, etc., but this is not limiting. As in the present embodiment, the processes of the repair method, such as the lamination process and the peening process, may be performed consecutively in the same system, or the processes of the repair method, such as the lamination process and the peening process, may be performed in a batch manner in separate systems.

[0086] Furthermore, some or all of the steps in the repair method described above may be performed by an operator operating a repair device, and some of the steps, such as finishing, may be performed manually by an operator.

[0087] The above-described additive manufacturing method, peening method, material and shape of the repair target, shape of the repair groove, powder material, additive manufacturing parameters, and peening parameters are merely examples and may be modified as appropriate. The above-described repair device 1 does not need to include all of the components described above. For example, for convenience of various operations, the groove forming device 10, the sensor device 40, and other components may be separate devices. In this case, it is desirable to connect the repair device 1 and the separate devices via the control unit 60, but it is also possible to perform batch processing on each device and input the results into the control unit 60. Furthermore, step S1 does not need to include all of the steps shown in FIG. 6 each time. For example, when repairing a repair target 2 made of the same material multiple times, step S12 may be omitted by reusing the same data.

[0088] <Additional Notes> The repair method and repair device 1 described in each embodiment can be understood, for example, as follows.

[0089] (1) The repair method according to the first aspect includes the steps of forming a repair groove 5 in the repair target 2 by removing a crack-containing region 2b including a crack 2a in the repair target 2, supplying powder material 4 to the repair groove 5 and melting the powder material 4 in the repair groove 5 to form a molding layer 6, and performing a peening process each time the molding layer 6 is formed to a predetermined layer pitch h2, in which an impact is applied to the molding layer 6 to impart residual compressive stress to the molding layer 6.

[0090] As a result, the peening process is performed on the surface of the modeling layer 6 at a predetermined layer pitch h2. As a result, the residual tensile stress is reduced by the residual compressive stress caused by the peening process throughout the modeling layer 6. This suppresses the occurrence of cracks 2a, allowing the repair target 2 to be repaired with high precision.

[0091] (2) The repair method of the second aspect is the repair method of (1), and may further include a step of setting the layer pitch h2 to be greater than the melting depth of the already formed forming layer 6 when the forming layer 6 is formed, and smaller than the penetration depth of the residual compressive stress due to the peening treatment.

[0092] This prevents the peened modeling layer 6 from melting when a new modeling layer 6 is formed. Furthermore, the residual compressive stress caused by the peening is reliably imparted to the entire modeling layer 6.

[0093] (3) A third aspect of the repair method is the repair method of (1) or (2), in which the repair groove 5 may be formed in a curved shape.

[0094] According to this aspect, it is not necessary to form the repair groove 5 so that the repair groove 5 has a flat surface, and therefore it is possible to easily form the repair groove 5. Even if the repair groove 5 is formed to have a curved surface, the peening treatment can be performed for each layer pitch h2, so that the residual tensile stress is reduced and the occurrence of cracks 2a is suppressed.

[0095] (4) A fourth aspect of the repair method is any one of the repair methods (1) to (3), and the peening treatment may involve applying an impact to the modeling layer 6 by ultrasonic peening.

[0096] Compared with other peening methods, ultrasonic peening can be performed simply and at low cost. Furthermore, ultrasonic peening can treat a wide area at once, thereby shortening the work time. Furthermore, ultrasonic peening can reduce the unevenness of the surface of the modeling layer 6.

[0097] (5) A fifth aspect of the repair method is any one of the repair methods (1) to (4), and the peening treatment may involve impacting the shaping layer 6 by shot peening.

[0098] Shot peening is simpler and cheaper than other peening methods, and because shot peening can treat a wider area at once, it can shorten the work time.

[0099] (6) A sixth aspect of the repair method is any one of the repair methods (1) to (5), and the peening process may involve impacting the shaping layer 6 by laser peening.

[0100] Compared with other peening methods, laser peening can perform finer peening and reduce deformation of the surface of the modeling layer 6. Therefore, laser peening can be performed even in areas where fine and high-precision work is required.

[0101] (7) The program of the seventh aspect causes the computer 1100 to execute the following steps: forming a repair groove 5 in the repair object 2 by removing a crack-containing region 2b including a crack 2a in the repair object 2; supplying powder material 4 to the repair groove 5 and melting the powder material 4 in the repair groove 5 to additively manufacture a modeling layer 6; and performing a peening process on the modeling layer 6 each time the modeling layer 6 is formed to a predetermined layer pitch h2, thereby impacting the modeling layer 6 and imparting residual compressive stress to the modeling layer 6.

[0102] (8) The repair device 1 of the eighth aspect includes a groove forming device 10 that forms a repair groove 5 in the repair object 2 by removing a crack-containing area 2b including a crack 2a in the repair object 2, an additive manufacturing device 20 that supplies powder material 4 to the repair groove 5 and melts the powder material 4 in the repair groove 5 to additively manufacture a manufacturing layer 6, and a peening device 30 that performs a peening process on the manufacturing layer 6 by impacting the manufacturing layer 6 each time the manufacturing layer 6 is formed to a predetermined layer pitch h2, thereby imparting residual compressive stress to the manufacturing layer 6.

[0103] (9) The repair device 1 of the ninth aspect may further include a sensor device 40 that acquires information about the repair object 2, and a control unit 60 that controls the additive manufacturing device 20 and the peening device 30 based on the information acquired by the sensor device 40.

[0104] This allows the repair device 1 to automatically and integrally control the additive manufacturing device 20 and the peening device 30 based on information about the repair object 2.

[0105] According to the repair method, program, and repair device disclosed herein, the repair target can be repaired with high precision.

[0106] REFERENCE SIGNS LIST 1 Repair device 2 Repair object 2a Crack 2b Crack-containing area 3 Stage 4 Powder material 5 Repair groove 6 Modeling layer 7 Additive manufacturing unit 10 Groove forming device 11 Cutting tool 20 Additive manufacturing device 21 Powder supply device 22 Laser scanner 23 Laser light 30 Peening device 31 Abrasive material 31A Pin 31B Sphere 31C Laser light 32 Liquid film 33 Plasma 40 Sensor device 41 Shape measurement sensor 42 Residual stress sensor 43 Flaw detection sensor 50 Moving device 51 Guide 52 First jig 53 Second jig 54 Third jig 55 Fourth jig 60 Control unit 1100 Computer 1110 Processor 1120 Main memory 1130 Storage 1140 Interface h1 Stacking height h2 Stacking pitch

Claims

1. A repair method comprising: a step of forming a repair groove in the repair target by removing a crack-containing area that includes a crack in the repair target; a step of supplying powder material to the repair groove and melting the powder material in the repair groove to additively manufacture a modeling layer; and a step of performing a peening process on the modeling layer each time the modeling layer is formed to a predetermined layer pitch, in which an impact is applied to the modeling layer to impart residual compressive stress to the modeling layer.

2. A repair method as described in claim 1, further comprising a step of setting the layer pitch to be greater than the melting depth of the already formed forming layer when the forming layer is formed, and smaller than the penetration depth of the residual compressive stress caused by the peening treatment.

3. A repair method according to claim 1 or 2, wherein the repair groove is formed in a curved shape.

4. A repair method according to claim 1 or 2, wherein the peening treatment involves impacting the forming layer by ultrasonic peening.

5. A repair method according to claim 1 or 2, wherein the peening treatment involves impacting the forming layer by shot peening.

6. A repair method according to claim 1 or 2, wherein the peening treatment involves impacting the shaping layer by laser peening.

7. A program that causes a computer to execute the following steps: forming a repair groove in the repair target by removing a crack-containing area that includes a crack in the repair target; supplying powder material to the repair groove and melting the powder material in the repair groove to additively manufacture a modeling layer; and performing a peening process on the modeling layer each time a modeling layer is formed to a predetermined layer pitch, thereby impacting the modeling layer and imparting residual compressive stress to the modeling layer.

8. A repair device comprising: a groove forming device that forms a repair groove in an object to be repaired by removing a crack-containing area that includes a crack in the object to be repaired; an additive manufacturing device that supplies powder material to the repair groove and melts the powder material in the repair groove to additively manufacture a modeling layer; and a peening device that performs a peening process on the modeling layer by impacting the modeling layer to impart residual compressive stress to the modeling layer each time the modeling layer is formed to a predetermined layer pitch.

9. The repair device according to claim 8, further comprising: a sensor device that acquires information about the repair object; and a control unit that controls the additive manufacturing device and the peening device based on the information acquired by the sensor device.

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