Control method for a powder feed head and method and device for forming an erosion protection

Abstract

Control method of a powder feed head (128) comprising a double tube in which an inner-circumferential tube (130) which sprays a plating metal used for weld plating using a laser and an outer-circumferential tube (132) which is arranged on an outer circumference of the inner-circumferential tube (130) and sprays shielding air (206) overlap concentrically, and which feeds the plating metal to a plating section (46), wherein the method comprises: a spraying process (S100) of spraying the plating metal from the powder feed head (128) onto a test area (182) under specified conditions and of forming a line segment by the plating metal that is sprayed onto the test area (182) without emitting a laser onto the test area (182) during the spraying process (S100); a width measurement process (S102) of measuring a width (β) of the plating metal that is sprayed onto the test area (182); a determination process (S110, S112) in which, in a case where the measured width (β) of the plating metal is equal to or less than a permissible size, it is determined that the powder feed head (128) is usable, and in a case where the measured width (β) of the plating metal is greater than the permissible size, it is determined that the powder feed head (128) is not usable.

Description

Area

[0001] The present invention relates to a control method for a powder feed head and a method for forming an erosion protection, a method for manufacturing a rotor blade, a powder feed head and a weld cladding device. background

[0002] In a conventional turbine (e.g., a steam turbine), a rotor as a rotating shaft is rotatably supported by a casing. Rotor blades are installed on the outer peripheral portion of the rotor, guide vanes are arranged on the inner wall of the casing, and a plurality of rotor blades and guide vanes are alternately arranged in a steam passage. According to a process in which steam flows through the steam passage, the rotor blades and the rotor are rotated.

[0003] The rotor blade includes a blade root portion fixed to the rotor disk of the rotor, a platform integrally formed with the blade root portion, and a blade portion having a base end portion connected to the platform and extending to the front end portion. Furthermore, the base end portions of the plurality of rotor blades are fixed to the outer peripheral portion of the rotor disk so as to be arranged along the circumferential direction of the rotor disk.

[0004] For example, the rotor blades of a steam turbine rotate in a path through which steam flows. Furthermore, the steam around the final stage of a low-pressure steam turbine contains many fine droplets. Due to the impact of these high-speed water droplets, the leading edge portion of the leading end of the rotor blade can be eroded, and its thickness can be reduced.

[0005] As anti-erosion measures, for example, a method for forming an erosion barrier on the leading edge portion of the leading end of a rotor blade is known, as described in JP H10-280907 A and JP 2012-86241 A. In JP H10-280907 A, an erosion barrier is formed by weld cladding using plasma transferred arc welding. In JP 2012-86241 A, it is described that powder of a hard material is melted by high-density energy irradiation (with a laser or electron beam) and subjected to weld cladding to form a hard layer, and a portion of a member is locally replaced with the hard layer, thus providing an erosion preventive portion (erosion barrier).

[0006] US 2003 / 0206820 A1 describes a control method for a powder feed head comprising a double tube. The inner tube sprays plating metal used for weld cladding, while the outer tube sprays shielding air. In the control method, plating metal is fed from the powder feed head onto a test area under defined conditions, and the width of the sprayed plating metal is determined.

[0007] WO 2006 / 094935 A1 describes a method for forming an erosion protection on a leading edge of a steam turbine blade. SummaryTechnical problem

[0008] When forming an erosion barrier by arc welding, as described in JP H10-280907 A, cases may occur where defects are generated or the hardness is insufficient. Furthermore, as described in JP 2012-86241 A, forming an erosion barrier by means of clad processing by laser welding can improve the erosion barrier performance.

[0009] During laser welding plating, there may be cases where the anti-erosion material, i.e., the plating metal used for plating, is sprayed from a tube provided for feeding in a head. If the condition of the supplied plating metal supplied from a powder feed head equipped with a plating metal supply tube, varies, the plating process may be affected. There is room for improvement in the powder feed head equipped with the plating metal supply tube and in the control and management of the powder feed head.

[0010] In order to solve the problems described above, an object of the present invention is to provide a control method of a powder feed head capable of stabilizing the state of the plating metal to be fed, a method for forming an erosion preventer, a method for manufacturing a rotor blade, a powder feed head, and a weld cladding apparatus. Solution to the problem

[0011] This object is achieved by a control method having the features of claim 1, a method for forming an erosion protection device having the features of claim 5 or 8, a method for producing a rotor blade having the features of claim 6 or 9, a powder feed head having the features of claim 7, and a device for weld cladding having the features of claim 10. Preferred embodiments follow from the remaining claims.

[0012] According to one aspect, there is provided a control method of a powder feed head having a double tube in which an inner peripheral tube that sprays a plating metal used for weld plating and an outer peripheral tube that is disposed on an outer periphery of the inner peripheral tube and sprays shielding air are concentrically overlapped, and that supplies the plating metal to a plating portion, the method comprising: a spraying process of spraying the plating metal from the powder feed head onto a test area under predetermined conditions; a width measuring process of measuring a width of the plating metal sprayed onto the test area;a determination process in which, in a case where the measured width of the plating metal is equal to or smaller than an allowable size, it is determined that the powder feed head is usable, and in a case where the measured width of the plating metal is larger than the allowable size, it is determined that the powder feed head is not usable.;

[0013] According to one aspect, in the inner peripheral tube, an end surface on a side on which the plating metal is sprayed is worked as a surface perpendicular to an axial direction of the inner peripheral tube.

[0014] According to one aspect, the test area is provided with an adhesion promoter.

[0015] According to one aspect, the control method of the powder feed head further comprises an oxygen concentration measuring process of measuring an oxygen concentration of the test area during the spraying process, wherein, during the determining process, in a case where the oxygen concentration measured in the measured oxygen concentration is greater than the allowable value, it is determined that the powder feed head is unusable.

[0016] According to one aspect, a method for forming an erosion barrier on a leading end and / or a blade surface of a movable blade body comprises: a process of forming a boundary by removing at least a portion of a leading end and an end surface of a base body from which the movable blade is derived; a process of forming a deposition portion by laser welding on the boundary using a powder feed nozzle determined to be usable in the control method of a powder feed head according to any one of claims 1 to 4; and a process of performing finishing to remove a portion of excess thickness of the base body and a portion of the deposition portion.

[0017] According to one aspect, a method for manufacturing a movable blade comprises: a base body manufacturing process for forming a base body having an excess thickness portion on a movable blade; and a process for forming an erosion protector on a blade body according to the erosion protector forming method of claim 5.

[0018] According to one aspect, there is provided a powder supply head comprising: an inner peripheral tube that sprays a weld metal used for build-up welding; and an outer peripheral tube configured to concentrically overlap an outer periphery of the inner peripheral tube and spray shielding air, wherein, with respect to the inner peripheral tube, an end surface on a side on which the weld metal is sprayed is a surface perpendicular to an axial direction of the inner peripheral tube.

[0019] According to one aspect, a method for forming an erosion protection on a leading end and / or a blade surface of a movable blade body comprises: a process of forming a boundary by removing at least a portion of a leading end and an end surface of a base body from which the movable blade is formed; a process of forming a deposition portion by laser welding on the boundary using a powder feed nozzle having the powder feed head according to claim 7; and a process of performing a finishing process for removing an excess thickness of the base body and a portion of the deposition portion.

[0020] According to one aspect, a method for manufacturing a movable blade comprises: a base body manufacturing process for forming a base body having an excess thickness portion on the movable blade; and a process for forming an erosion protector on a blade body according to the erosion protector forming method of claim 8.

[0021] According to one aspect, a build-up welding apparatus comprises: a powder feed head according to claim 7; and a laser head that emits a laser beam, wherein the weld metal is fed via the powder feed head while a welding position is irradiated with the laser beam from the laser head. Advantageous effects of the invention

[0022] According to the present invention, the state of the supplied weld metal can be stabilized. Consequently, build-up welding can be performed with higher precision. Short description of the drawings Fig. Figure 1 is a schematic diagram showing the structure of a steam turbine provided with a movable blade. Fig. 2 is a perspective view illustrating a schematic structure of an embodiment of the movable blade. Fig. 3 is a sectional view taken along the AA plane of the Fig. 2 is taken. Fig. 4 is an explanatory view for explaining the shape of an erosion control device and a method for forming the same. Fig. 5 is a flowchart showing an example of the method for manufacturing a movable blade. Fig. 6 is a schematic view illustrating an example of a method for forming an erosion protector according to the method for manufacturing a movable blade. Fig. 7A is a schematic view showing a schematic structure of a build-up welding apparatus. Fig. 7B is a partially enlarged view showing the schematic structure of the build-up welding apparatus. Fig. 8 is a front view showing a schematic structure of a powder supply head. Fig. 9 is a sectional view showing the schematic structure of the powder feed head. Fig. 10 is a flowchart showing an example of a machining process of build-up welding. Fig. 11 is a flowchart showing an example of a control operation of the powder supply head. Fig. 12 is an explanatory view for showing an example of the control operation of the powder supply head. Description of embodiments

[0023] A suitable embodiment of the present invention will be described in detail below. The present invention is not limited to the embodiment. Where there are multiple embodiments, a combination of the embodiments is also included.

[0024] Fig. Fig. 1 is a schematic diagram illustrating the structure of a steam turbine provided with a movable blade according to an embodiment. The following describes the essence of the structure of a steam turbine 1 according to the embodiment with reference to Fig. Fig. 1 described.

[0025] As it is in Fig. 1, in the steam turbine 1, a casing 11 has a hollow shape, and a rotor 12 as a rotating shaft is rotatably supported by a plurality of bearings 13. Movable blades 15 and stationary blades 16 are arranged in the casing 11. A plurality of the movable blades 15 are arranged and fixed on the outer periphery of a disc-shaped rotor disk 14 formed on the rotor 12 along a circumferential direction thereof. A plurality of the stationary blades 16 are arranged and fixed on the inner wall of the casing 11 along a circumferential direction thereof. The movable blades 15 and the stationary blades 16 are arranged alternately along the axial direction of the rotor.

[0026] Furthermore, the movable blades 15 and the stationary blades 16 are arranged in the housing 11 to form a steam passage 17 through which steam passes. The steam passage 17 has a steam supply opening 18, which is designed as an inlet through which the steam is supplied, and a steam outlet opening 19, which is designed as an outlet from which the steam exits to the outside.

[0027] Next, the nature of the operation of the steam turbine 1 is explained with reference to Fig. 1. Steam supplied from the steam supply port 18 of the steam turbine 1 to the steam passage 17 expands as it passes through the stationary blades 16 and becomes a high-speed steam flow. The high-speed steam flow passing through the stationary blades 16 is blown toward the movable blades 15 and rotates the plurality of movable blades 15 and the rotor 12 to which the movable blades 15 are attached. For example, a generator or the like is connected to the rotor 12, and as the rotor 12 rotates, the generator is driven and power is generated. The steam passing through portions of the steam passage 17 in which the stationary blades 16 and the movable blades 15 are arranged exits to the outside from the steam outlet port 19.

[0028] Fig. 2 is a schematic view illustrating the movable blade of the embodiment. Fig. 3 is a sectional view taken along the AA plane of the Fig. 2. The structure of the movable blade 15 of the embodiment will be described with reference to Fig. 2 and Fig. 3. As described in Fig. 2, the movable blade 15 includes a blade root portion 21, a platform 22, and a blade portion 23. The blade root portion 21 is embedded in the rotor disk 14, thereby fixing the movable blade 15 to the rotor disk 14. The platform 22 is a curved plate-shaped member formed integrally with the blade root portion 21. The base end portion of the blade portion 23 is fixed to the platform 22, and the front end portion thereof extends toward the inner wall surface of the casing 11. There may be a case where the blade portion 23 twists along a blade longitudinal direction. Further, the movable blade 15 may be provided with a shroud fixed to the front end portion of the blade portion 23.The reinforcement is a member that can come into contact with the reinforcement of an adjacent movable blade 15 in order to fix the movable blade 15 or to suppress vibrations of the movable blade 15.

[0029] As it is in the Fig. 2 and Fig. 3, an erosion protector 25 is formed on a portion of the surface of a blade body 24 on the movable blade 15. The erosion protector 25 is formed on the leading edge portion of the movable blade 15, which corresponds to the upstream side of the steam flow when the movable blade 15 rotates and the steam flow occurs, that is, at a leading end 26 and a portion of the blade surface 27 on the leading end 26 side. The boundary line between the blade body 24 and the erosion protector 25 becomes a boundary 28. The erosion protector 25 may also be provided only in a certain area on a side away from the platform 22 in an extending direction of the movable blade 15, that is, in a direction away from the platform 22 of the blade portion 23.That is, the erosion protection 25 may also be formed only on a portion on one side that is radially outward during rotation. For example, a cobalt-based alloy with high wear resistance, such as Stellite (registered trademark), which primarily contains cobalt, may be used as the erosion protection 25. The erosion protection 25 may be formed by deposition machining by laser welding a workpiece (e.g., Stellite (registered trademark)) on the surface of the blade body 24. Furthermore, the blade body 24 is formed from a chromium-based alloy or the like.

[0030] Next, a more detailed form of the erosion protection, a method of forming the erosion protection and a method of manufacturing the movable blade incorporating the method are described with reference to the Fig. 4 to 12 described. Fig. 4 is an explanatory view for explaining the shape of the erosion control and a method for forming the same. Fig. 5 is a flowchart showing an example of the method for manufacturing the movable blade. Fig. 6 is a schematic view showing an example of the method for imaging the erosion control according to the method for manufacturing the movable blade. Fig. 7A is a schematic view showing a schematic structure of a build-up welding apparatus. Fig. 7B is a partially enlarged view showing the schematic structure of the build-up welding apparatus. Fig. 8 is a front view showing a schematic structure of a powder supply head. Fig. 9 is a sectional view showing the schematic structure of the powder feed head. Fig. 10 is a flowchart showing an example of a machining process of build-up welding.

[0031] As it is in Fig. 4, in the movable blade 15, the boundary 28 is formed by forming an edge for forming the erosion protection 25 in a base body 40 from which the blade body 24 is to be manufactured. Thereafter, a material for forming the erosion protection 25 is formed at the boundary 28 by deposition machining (deposition welding), and thereafter, an excess thickness of the deposition portion and an excess thickness of the base body 40 are removed, so that the front end 26, the blade surface 27, and a surface on the side opposite to the blade surface 27 are formed.

[0032] Here, the boundary 28 has a shape that approximates the surface on the side opposite to the blade surface 27, extending from an end portion on the side of the blade surface 27 to the end portion of the front end 26. Further, the boundary 28 is formed to include: a curve (first curve) R1 that is convex toward the inside of the blade body 24 at the end portion on the side of the blade surface 27, a curve (second curve) R2 that is provided closer to the side of the front end 26 than the first convex R1 and is convex toward the outside of the blade body 24, a curve (third curve) R3 that is provided closer to the side of the front end 26 than the second curve R2 and is convex toward the outside of the blade body 24, and a straight line provided between the third curve R3 and the surface on the side opposite to the blade surface 27. With respect to the boundary 28 of the embodiment, the first, second and third curves R1, R2 and R3 are soft anduniformly connected. With respect to the boundary 28 of the embodiment, the radius of curvature of the first curve R1 is smaller than that of the second curve R2. Furthermore, with respect to the boundary 28, the radius of curvature of the third curve R3 is smaller than that of the first curve R1.

[0033] As an example of the shape of the movable blade 15 of the embodiment, the radius of curvature of the first curve R1 is 6.5 mm, the radius of curvature of the second curve R2 is 10.0 mm, and the radius of curvature of the third curve R3 is 2.5 mm.

[0034] With respect to the boundary 28, the distance d1 between the contact between the second curve R2 and the third curve R3 and the surface on the side opposite to the blade surface 27 is 2.3 mm, and the distance d2 of the straight line provided between the third curve R3 and the surface on the side opposite to the blade surface 27 is 0.7 mm. With respect to the movable blade 15, the distance d3 between the blade surface 27 and the contact between the first curve R1 and the second curve R2 is 0.8 mm. The distances d4 and d5 between a surface of the base body 40 on the side of the blade surface 27 and the blade surface 27 are 1.0 mm. The distance d6 between a surface of the base body 40 on the side opposite to the side of the blade surface 27 and the surface of the movable blade 15 on the side opposite to the blade surface 27 is 2.0 mm.

[0035] Further, the distance L1 from the end portion of the base body 40 on the front end 26 side to the end portion of the boundary 28 on the blade surface 27 side becomes 12.5 mm, and the distance L2 from the end portion on the front end 26 side to the contact between the first curve R1 and the second curve R2 becomes 9.0 mm. The distance L3 from the end portion of the base body 40 on the front end 26 side to the end portion of the erosion preventer 25 on the front end 26 side becomes 1.0 mm. The distance L4 from the end portion of the base body 40 on the front end 26 side to the end portion of the third curve R3 on the front end 26 side becomes 2.7 mm. The distance L5 from the end portion of the base body 40 on the front end 26 side to the contact between the second curve R2 and the third curve R3 becomes 3.2 mm.

[0036] In the movable blade 15, since the shape of the boundary 28 between the blade body 24 and the erosion protector 25 is a shape close to the surface on the side opposite the blade surface 27, extending from the end portion of the blade surface 27 side to the end portion of the leading end 26, and including the first curve R1 and the second curve R2, the performance of the erosion protector 25 can be improved. Furthermore, the generation of defects of the erosion protector 25 in the blade body 24 can be suppressed, and the hardness of the erosion protector 25 can be improved (made harder).That is, since the erosion protection layer 25 formed by laser welding deposition and the blade body 24 have the above-described relationship, and the weld metal (metal of the erosion protection layer 25) is diluted with the base metal components (components of the blade body 24), the hardness of the erosion protection layer 25 is not increased (made harder), and deterioration in performance can be suppressed. Furthermore, since the weld metal is diluted with the base metal components, the initiation of cracking in the metal of the erosion protection layer 25 can be suppressed. Furthermore, the generation of welding defects such as loss of fusion between the erosion protection layer 25 and the blade body 24 and blistering can be suppressed.

[0037] Although the first curve R1 and the second curve R2 contact each other, a straight line portion may be provided between the first curve R1 and the second curve R2 in the embodiment. Further, in the embodiment, a curve may also be provided between the third curve R3 and the surface on the side opposite to the blade surface 27. Here, at the boundary 28, the first, second, and third curves R1, R2, and R3 are preferably smoothly connected, and thus the radii of curvature thereof are increased. As described above, by increasing the radii of curvature of all the curves of the boundary 28, a variation in the thickness of the anti-erosion member 25 in a direction along the boundary 28 can be reduced or smoothed, and thus the performance of the anti-erosion member 25 can be improved.

[0038] Regarding the movable blade 15, the distance d3 is shorter than the difference between the distance L4 and the distance L3. That is, in the erosion preventer 25, the front end 26 side is thicker than the blade surface 27 side. Consequently, while the thickness is increased on the front end 26 side where erosion is more likely to occur and a reduction in thickness is large, the thickness on the blade surface 27 side where a small reduction in thickness occurs can be reduced.

[0039] The distances d4 and d5 between the surface of the base body 40 on the blade surface 27 side and the blade surface 27, that is, the distance of an excess thickness portion on the blade surface 27 side, are set to 1 mm. Since the distance of the excess thickness portion on the blade surface 27 side is set to 1 mm, machining can be performed efficiently. This distance can be 1 mm or more, or it can be very large.

[0040] The distance d6 between the surface of the base body 40 on the side opposite to the blade surface 27 and the surface of the movable blade 15 on the side opposite to the blade surface 27, that is, the distance of an excess thickness portion on the surface on the side opposite to the blade surface 27, is set to 2 mm. Since the distance of the excess thickness portion on the surface on the side opposite to the blade surface 27 is set to 2 mm, machining can be performed efficiently. Therefore, the distance can be 2 mm or more, or it can be very large.

[0041] Next, the method for manufacturing the movable blade will be described with reference to the Fig. 5 and Fig. 6. According to the method for manufacturing the movable blade, the shape of the turbine blade base body 40 and a machining amount are determined based on the shape of a turbine blade (movable blade) to be manufactured (step S20). That is, as described in the above-described Fig. As shown in Figure 4, the shape of the specified base body 40, the distance between the base body 40 and the like are determined. Furthermore, the machining scope and machining order are determined based on the shape.

[0042] According to the movable blade manufacturing method, when machining conditions are determined, the base body 40 of the turbine blade is manufactured based on the determined conditions (step S22). That is, according to the movable blade manufacturing method, the base body 40, which is a workpiece 82 shown in Fig. 6, is manufactured. The base body 40 has a shape before the formation of the boundary 28, and in terms of shape, the excess thickness portions and a region closer to the front end side than the boundary 28 remain. The base body 40 is manufactured by casting. For example, in a set of an upper and lower mold machined to conform to the shape of the base body 40, a forging material (e.g., stainless steel) is heated to a recrystallization temperature or higher, and hot forging is performed. When the hot forging is completed, a forging having the shape of the base body 40 is formed.With respect to the manufactured base body 40, after the formed forging is cooled in a high-temperature state, unnecessary portions (burrs) are removed, and the forging is subjected to heat treatment so that residual stress generated in the forging during the preliminary processing (forging) and thermal stress generated in the forging during the cooling process are relieved. Thus, the base body 40 is manufactured.

[0043] According to the method for manufacturing the movable blade, when the base body 40 is manufactured, edge preparation for build-up welding is performed (step S24). That is, edge preparation is performed on the workpiece 82 in Fig. 6, so that a portion 44 of a base body 42 is removed and a workpiece 84 is formed. Consequently, a portion of the base body 42 at the front end side is curved along the boundary 28.

[0044] According to the method for manufacturing the movable blade, after the edge preparation for build-up welding is performed, build-up processing is performed by laser welding (step S26). That is, build-up welding is performed on the workpiece 84 in Fig. 6, so that a deposition portion 46 is formed on the base body 42 and a workpiece 86 is formed. The deposition portion 46 is formed from metal (welding metal) from which the erosion protection 25 emerges, and it is formed in a region containing a region 50 in which the erosion protection 25 is formed. Furthermore, deposition processing is carried out such that each pass in the extension direction of the movable blade 15, that is, a direction perpendicular to Fig. 6, is performed. In a case where one pass of job processing is performed and the subsequent pass of job processing is performed, a processing position moves in the direction of an arrow 52. That is, the job processing is performed from the end portion side of the area 50 on the blade surface 27 side to the surface on the side opposite the blade surface 27, with a gradual movement toward the front end 26 side.

[0045] According to the method for manufacturing the movable blade, an increase in the thickness of the region 50 is suppressed, and the weld metal can be formed for one pass (one layer) at each position because a surface of the base body 42 on which the deposited portion 46 is formed is the curve along the boundary 28. That is, by multi-layer deposit welding, the deposited portion 46 can be suppressed from being formed, so that a region with a reduced hardness can be suppressed from being exposed to the surface. Here, in the method for manufacturing the movable blade, one (exactly one) layer can be formed at each position of the deposited portion 46 by causing the thickness of the region 50 to be 2 mm or less. The region with a reduced hardness is a region where the base metal is introduced into the weld metal.penetrates, and is thus an area in which the performance (erosion resistance) of the erosion protection 25 provided by the weld metal is reduced.

[0046] Preferably, the deposition portion 46 has a dilution of 10% or less with the base metal (the material of the base body 42). According to the method for manufacturing the movable blade, as described later, a dilution of 10% or less with the base metal (the material of the base body 42) can be achieved by forming the deposition portion 46 through deposition machining using a laser. According to the method for manufacturing the movable blade, since the surface of the base body 42 on which the deposition portion 46 is formed is the curve along the boundary 28, ingress of the weld metal (the metal of the deposition portion 46 and the metal from which the erosion preventer 25 is formed) can be suppressed. Thus, the dilution with the base metal (the material of the base body 42) can be more reliably caused to be 10% or less.The deposition section 46 is formed such that adjacent weld beads, i.e., sections formed from adjacent passes, overlap. Furthermore, the weld beads are preferably formed such that, when the weld beads come into contact with the base body 42, the weld beads have more contact with the other weld beads than with the base body 42. The deposition processing by laser welding is described.

[0047] According to the method for manufacturing the movable blade, after the overlay machining is performed, finishing machining is performed to remove portions of excessive thickness (step S28). That is, the finishing machining is performed on the workpiece 86 in Fig. 6, and as illustrated with reference to the workpiece 88, a portion of excess thickness 60 on the blade surface 27 side, a portion of excess thickness 62 on the surface opposite the blade surface 27 side, and a portion of excess thickness 54 of the deposited portion 46 are removed. Thus, the movable blade 15, which includes the blade body 24 and the erosion barrier 25, is formed. Thereafter, the movable blade 15 is subjected to necessary heat treatments (e.g., solutionizing treatment and aging treatment) so that the movable blade 15 is imparted with necessary mechanical properties.

[0048] In the following, the order processing by laser welding in step S26 is described in more detail with reference to the Fig. 7A, Fig. 7B and Fig. 10. First, a schematic structure of the build-up welding device 100, which carries out the build-up processing by laser welding, is described with reference to the Fig. 7A and Fig. 7B. As described in Fig. As shown in Figure 7A, the deposition welding apparatus 100 includes a laser irradiation device 102 and a powder supply device 104. The deposition welding apparatus 100 further includes, in addition to the above structure, a position adjustment mechanism, a mechanism that moves a relative position relative to the base body 42, a mechanism that performs a welding position following operation, and the like.

[0049] The laser emitting device 102 includes a light source 112, an optical fiber 114, and a laser head 116. The light source 112 is a light-emitting source that emits a laser beam. The optical fiber 114 guides the laser beam emitted by the light source 112 to the laser head 116. The laser head 116 outputs the laser beam that has been transmitted through the optical fiber 114. As shown in Fig. 7B, the laser head 116 faces the welding position of the base body 42 and irradiates the welding position with a laser beam 202.

[0050] The powder supply device 104 includes a powder supply source 120, a powder supply line 122, an air supply source 124, an air supply line 126, and a powder supply head 128. The powder supply source 120 is a supply source that transports the weld metal. The powder supply source 120 transports the weld metal in the form of a flow mixed with air or the like to the powder supply line 122. The powder supply line 122 supplies the mixed flow of the weld metal and air supplied from the powder supply source 120 to the powder supply head 128. The air supply source 124 supplies an inert gas (e.g., nitrogen or argon), which is a shielding gas for the welding position, in this embodiment, 99.999% nitrogen gas. The air supply line 126 supplies the shielding gas supplied from the air supply source 124 to the powder supply head 128.

[0051] As it is in Fig. As shown in Figure 8, the powder supply head 128 is a double-tube nozzle in which an inner peripheral tube 130 and an outer peripheral tube 132 disposed on the outer periphery of the inner peripheral tube 130 are concentrically arranged. In the powder supply head 128, a region surrounded by the inner periphery of the inner peripheral tube 130 becomes a flow passage 134. The flow passage 134 is circular and includes the center of the concentric circles. In the powder supply head 128, a region surrounded by the inner peripheral surface of the outer peripheral tube 132 and the outer peripheral surface of the inner peripheral tube 130 becomes a flow passage 136. The flow passage 136 is annular.The powder feed head 128 sprays the mixed flow (powder) 204 of the weld metal and air supplied via the powder feed line 122 from the flow passage 134, and sprays shielding air 206 supplied via the air supply line 126 from the flow passage 136. As shown in . Fig. 7B, the powder supply head 128 faces the welding position of the base body 42 and sprays the powder 204 and the shielding air 205 onto the welding position.

[0052] Here, the powder 204 sprayed from the flow passage 134 is sprayed at a certain spread angle as shown in Fig. 9. Furthermore, in the powder supply head 128, an end surface (spray opening) 150 of the inner peripheral tube 130 on the spray side is a surface perpendicular to the central axis (extension direction) of the inner peripheral tube 130. That is, the end surface 150 of the inner peripheral tube 130 is not chamfered.

[0053] The build-up welding device 100 supplies the powder 204 while irradiating the welding position of the base body 42 with the laser beam 202, so that the weld metal contained in the powder 204 is welded to the base body 42. Furthermore, the build-up welding device 100 sprays the shielding air 206 onto the welding position, so that the atmosphere at the welding position becomes a specific atmosphere. In particular, the oxygen concentration at the welding position can be controlled.

[0054] In the build-up welding apparatus 100, since the end surface 150 of the powder feed head 128 has a shape that is not chamfered, the spreading angle of the powder 204 can be kept constant. That is, when the end surface 150 of the powder feed head 128 is chamfered, the spreading angle of the powder 204 is changed by the chamfered state, and thus the state of the powder to be supplied to the welding position by the powder feed head 128 changes. On the other hand, since in the powder feed head 128 of the embodiment, the end surface 150 of the powder feed head 128 has a shape that is not chamfered, the shape of the end surface 150 of the powder feed head 128 can maintain the same shape, and the occurrence of individual fluctuations can be suppressed. Thus, the spreading angle of the powder 204 can be kept constant, and thus the powder (weld metal) can be stably supplied to the welding position.

[0055] Next, an example of order processing workflows using laser welding with reference to Fig. 10. The process described in Fig. 10 can be carried out by automatic control using a program or the like.

[0056] According to the method for manufacturing the movable blade, a grinding process is performed (step S40) to treat the surface of a region where edge preparation is performed. By performing a grinding process, the weld metal welded by build-up welding enters a state where it can be easily welded to the surface (boundary) of the base body 42. According to the method for manufacturing the movable blade, after the grinding process is performed, a thickness measurement is performed (step S42). That is, according to the method for manufacturing the movable blade, the shape of a region where the erosion prevention member 25 is to be formed is measured.

[0057] According to the method for manufacturing the movable blade, after the thickness measurement is performed, a welding position tracking process is performed (step S44). By spraying the weld metal while emitting the laser beam, positions where weld beads are to be formed are specified. Thus, each path along which the head and the base body 42 are moved relative to each other is adjusted.

[0058] According to the method for manufacturing the movable blade, preheating and intermediate temperature adjustment are then performed (step S46). According to the embodiment, heating is primarily performed, or cooling is performed as needed to cause the base body 42 to reach a predetermined temperature within a range of 50°C or more and 100°C or less. According to the method for manufacturing the movable blade, build-up welding is performed (step S48) after the preheating and temperature adjustment are performed. Specifically, one pass of build-up welding is performed using the build-up welding apparatus 100.

[0059] After the build-up welding is performed, according to the method for manufacturing the movable blade, intermediate pass and interlayer cutting are performed (step S50). Specifically, melt, dirt, and the like adhering to the surface of the build-up portion 46 are removed. According to the method for manufacturing the movable blade, after the cutting is performed, it is determined whether or not the build-up welding is completed (step S52). That is, it is determined whether all the specified passes of the build-up welding have been performed and the build-up portion 46 can be formed.In a case where it is determined that the build-up welding is not completed (No in step S52), according to the method for manufacturing the movable blade, the process returns to step S44, and the processes thereafter are performed to perform the subsequent pass of the build-up welding.

[0060] In a case where it is determined that the build-up welding is completed (Yes in step S52), according to the method for manufacturing the movable blade, the surfaces of the weld beads are removed (step S54). Specifically, the melt, dirt, and the like adhering to the surface of the build-up portion 46 are removed. After performing the thickness measurement (step S56) to measure the shape of the build-up portion 46, the main processes according to the method for manufacturing the movable blade are completed.

[0061] By performing the laser welding custom machining according to the above-described procedures (custom machining), the movable blade manufacturing method can perform machining with high precision, and the generation of defects or the like can be prevented. By performing the procedures shown in steps S40, S46, S50, and S54, the movable blade manufacturing method can improve machining accuracy and prevent defects. However, these steps are not necessarily required.

[0062] Furthermore, according to the embodiment, the following process is performed for each pass. However, it is possible that the following process is performed only before the first pass of the build-up welding. In this case, the shape of the weld bead formed in each pass is determined by calculation, and a subsequent position is determined based on the shape. Furthermore, the welding position is preferably determined by a measuring instrument, and feedback control is performed based on the result. Consequently, positional deviation of the welding position can be prevented from occurring. A measuring position may be located on the upstream side of the welding position.

[0063] Furthermore, in the build-up welding apparatus 100, the laser beam is preferably positioned at approximately 90 degrees relative to the flat surface of the welding position of the base body and the tangential line connecting a convex portion and a convex portion. Since the laser beam is positioned at approximately 90 degrees relative to the flat surface of the welding position of the base body or the tangential line connecting the convex portion and the convex portion, near the welding position (for example, at a convex portion of the weld bead and a convex portion of the base body), welding defects can be prevented, and infiltration of the base material into the weld metal can be suppressed.

[0064] In the build-up welding device 100, the welding position can be oscillated. For example, during a ribbon-like feed of the powder to the welding position, a high-speed oscillation of the laser beam can be performed in a width direction (a direction perpendicular to the passages or paths).

[0065] Here, a high speed is a speed at which the energy density distribution of the laser beam at the welding position is not V-shaped but rectangular, thus making a portion that is thinned with the introduced base material thinner. Regarding the reciprocating motion according to the embodiment, the reciprocating motion is performed at a frequency of tens of Hz to hundreds of Hz. Consequently, the energy density distribution can be flattened, and a portion melted by the laser beam can be made thinner and wider.

[0066] Next, a control method of the powder feed head with reference to the Fig. 11 and Fig. 12. In the build-up welding apparatus 100 according to the embodiment, the end surface 150 of the inner peripheral tube 130 of the powder feed head has a shape that is not chamfered. However, cases may occur in which the shape of the inner peripheral surface of the tube 130 changes while the welding metal is being supplied as powder. The build-up welding apparatus 100 according to the embodiment performs the processes described in the Fig. 11 and Fig. 12 and regulates the condition of the powder feed head. Fig. 11 is a flowchart showing an example of a control operation of the powder supply head. Fig. Fig. 12 is an explanatory view showing an example of the control operation of the powder feed head. The time in which the process shown in Fig. 11 is not particularly limited. The process may be performed while order processing is being performed, while the powder feed head is being mounted, while the apparatus is starting up, or in a case where a process such as maintenance is scheduled.

[0067] According to the control method of the powder supply head, a powder is sprayed onto a test area (step S100).

[0068] In particular, as stated in Fig.12, a test unit 180 is installed at the welding position of the build-up welding apparatus 100. The test unit 180 includes a test element 182 and an oxygen concentration measuring device 184. The test element 182 is a flat member, such as a flat plate, and is arranged at a position spaced apart by a distance α from the powder feed head 128. The test element 182 acts as a test area onto which the powder is sprayed from the powder feed head 128. The test element 182 is provided with a material having an adhesive effect on a surface facing the powder feed head 128. For example, an adhesion promoter is applied to the surface of the test element 182 facing the powder feed head 128. Consequently, the test element 182 can hold the powder (welding metal) sprayed from the powder feed head 128 at the adhesive position.The oxygen concentration measuring device 184 measures the oxygen concentration in the test area (in the vicinity of the test area) onto which the powder is sprayed from the powder feed head 128. Preferably, the oxygen concentration measuring device 184 is configured such that a measuring point that measures the oxygen concentration is movable and located in an area through which no powder sprayed from the powder feed head 128 passes while the concentration is not being measured.

[0069] According to the test unit 180, by moving the powder supply head 128 and the test element 182 in a direction of an arrow 186, a position on the test element 182 that reaches the powder sprayed from the powder supply head 128 is moved in a direction, and it becomes a line having a width β in a direction perpendicular to the arrow 186 and receiving the powder.

[0070] According to the powder feed head control method, using the test unit 180 as described above, the powder is sprayed onto the test area, and a line segment is formed by the powder on the test area. When the line segment is formed on the test area, according to the powder feed head control method, the width of the area onto which the powder is sprayed, i.e., width β, is measured (step S102), and the oxygen concentration in the test area onto which the powder is sprayed is measured (step S104).

[0071] When the width and oxygen concentration of the area are measured, it is determined according to the control method of the powder supply head whether or not the width of the area to which the powder is sprayed is equal to or larger than a threshold value (allowable size) (step S106). The threshold value is a preset value. For example, the width β becomes 7 mm in a case where the distance α is 13 mm, the diameter of the inner peripheral tube 130 is 1.2 mm, the feed rate of the weld metal is 5 g / min, and the flow rate of the carrier gas that transports the weld metal is 3 L / min or more and 4 L / min or less. In a case where it is determined that the width β is the threshold value or larger (Yes in step S106), the flow proceeds to step S112 according to the control method of the powder supply head.In a case where it is determined that the width β is smaller than the threshold value (No in step S106), it is determined whether the oxygen concentration is within a specified range according to the powder feed head control method (step S108). In a case where it is determined that the oxygen concentration is within the specified range (Yes in step S108), it is determined that the powder feed head is usable as an object according to the powder feed head control method (step S110), and the main process is ended. In a case where it is determined that the oxygen concentration is not within the specified range (No in step S108), or in a case where Yes is determined in step S106, unusability is determined according to the powder feed head control method (step S112), and the main process is ended.According to the control method of the powder feed head, the result of the determination is preferably displayed on a monitor or output through a loudspeaker as a sound to inform a worker of the result.

[0072] According to the above-described powder feed head control method, the spread of the powder sprayed from the powder feed head is detected, and based on the result thereof, it is determined whether or not the powder feed head is usable, so that a change in the shape of the nozzle caused by wear and the like during use can be detected. Thus, the amount and density of the powder supplied to a head welding position can be maintained within predetermined ranges. Consequently, a change in the welding conditions can be suppressed, and stable machining can be performed. According to the embodiment, since build-up welding is performed by means of the powder feed head configured by the powder feed head control method, a build-up portion and an erosion preventer having a small number of defects and high hardness can be formed.

[0073] According to the above-described powder feed head control method, the oxygen concentration is detected, and based on the result, it is determined whether or not the powder feed head is usable, so that it can be detected whether or not the machining conditions are suitable. Thus, fluctuations in the welding conditions can be suppressed, and stable machining can be performed. According to the embodiment, since build-up welding is performed using the powder feed head configured by the powder feed head control method, a build-up portion and an erosion preventer with a small number of defects and high hardness can be formed.

[0074] According to the powder feed head control method, the determination is made using both the width and oxygen concentration of the area to which the powder is sprayed. However, the determination of whether or not the powder feed head is usable can be made based on only one of them.

[0075] Furthermore, according to the embodiment, a movable blade in a steam turbine was described as the object. However, the embodiment is not limited to this, and, for example, it can also be applied to a method for manufacturing a movable blade of another rotating machine, such as a gas turbine. List of reference symbols 1 steam turbine 11 housings 12 Rotor 13 camps 14 Rotor disc 15 Movable shovel 16 Stationary shovel 17 Steam passage 18 Steam supply opening 19 Steam outlet opening 21 Blade root section 22 Platform 23 Blade section 24 blade bodies 25 Erosion protection 26 front end 27 blade area 28 border 40, 42 base body 46 Order section 60, 62, 64 Section of excess thickness 82, 84, 86, 88 workpiece 100 build-up welding device 102 Laser emission device 104 Powder feed device 128 Powder feed head

Claims

[1] A control method of a powder feed head (128) having a double tube in which an inner peripheral tube (130) spraying a plating metal used for weld plating using a laser and an outer peripheral tube (132) disposed on an outer periphery of the inner peripheral tube (130) and spraying shielding air (206) concentrically overlap, and which supplies the plating metal to a plating section (46), the method comprising: a spraying process (S100) of spraying the plating metal from the powder feed head (128) onto a test area (182) under predetermined conditions and forming a line segment by the plating metal sprayed onto the test area (182) without emitting a laser onto the test area (182) during the spraying process (S100); a width measuring process (S102) of measuring a width (β) of the plating metal sprayed onto the test area (182); a determination process (S110, S112) in which, in a case where the measured width (β) of the plating metal is equal to or smaller than an allowable size, it is determined that the powder feed head (128) is usable, and in a case where the measured width (β) of the plating metal is larger than the allowable size, it is determined that the powder feed head (128) is not usable. [2] A control method of a powder supply head (128) according to claim 1, wherein in said inner peripheral tube (130), an end surface (150) on a side on which said plating metal is sprayed is worked as a surface perpendicular to an axial direction of said inner peripheral tube (130). [3] A method for checking a powder feed head (128) according to claim 1 or 2, wherein the test area (182) is provided with an adhesion promoter. [4] A method of controlling a powder feed head (128) according to any one of claims 1 to 3, further comprising: an oxygen concentration measuring process (S108) of measuring an oxygen concentration of the test area (182) during the spraying process (S100), wherein during the determination process (S110, S112), in a case where the oxygen concentration measured in the oxygen concentration measuring process (S108) is equal to or smaller than an allowable value, it is determined that the powder feed head (128) is usable, and in a case where the measured oxygen concentration is greater than the allowable value, it is determined that the powder feed head (128) is not usable. [5] Method for forming an erosion protection (25) on a front end (26) and / or a blade surface (27) of a rotor blade body (24), said method comprising: a process (S24) of forming a boundary (28) by removing at least a portion of a leading end and an end surface of a base body (40) from which the rotor blade (16) emerges; a process (S26) of forming a plating portion (46) by laser welding on the boundary (28) using a powder feed nozzle determined to be usable in the control method of a powder feed head according to any one of claims 1 to 4; and a process (S28) of performing a finishing process to remove a portion (60, 62) of excess thickness of the base body (40) and a portion (64) of the plating portion (46). [6] A method for producing a rotor blade (16), comprising: a base body manufacturing process (S24) for forming a base body (40) having a portion of excess thickness on a rotor blade (16); and a process for forming an erosion protection (25) on a blade body (24) according to the method for forming an erosion protection (25) according to claim 5. [7] A powder feed head (128) spraying a plating metal used for weld plating and operated by the control method of claim 1, comprising: an inner peripheral tube (130) that sprays the plating metal; and an outer peripheral tube (132) arranged to concentrically overlap an outer periphery of the inner peripheral tube (130) and spray shielding air (206), wherein with respect to the inner peripheral tube (130), an end surface (150) on a side on which the plating metal is sprayed is a surface perpendicular to an axial direction of the inner peripheral tube (130). [8] Method for forming an erosion protection (25) on a front end (26) and / or a blade surface (27) of a rotor blade body (24), said method comprising: a process (S24) for forming a boundary (28) by removing at least a portion of a leading end and an end surface of a base body (40) from which a rotor blade (16) emerges; a process (S26) of forming a plating portion (46) by laser welding on the boundary (28) using a powder feed nozzle having the powder feed head (128) according to claim 7; and a process (S28) of performing a finishing process to remove an excess thickness (60, 62) of the base body (40) and a portion (64) of the plating portion (46). [9] A method for producing a rotor blade (16), comprising: a base body manufacturing process (S22) for forming a base body (40) having a portion of excess thickness on the rotor blade (16); and a process for forming an erosion protection (25) on a blade body (24) according to the method for forming an erosion protection according to claim 8. [10] Device for welding cladding by irradiation with a laser beam, comprising: a powder feed head (128) according to claim 7; and a laser processing head (116) which emits the laser beam (202), wherein the plating metal is supplied via the powder supply head (128) while a plating section (46) is irradiated with the laser beam (202) from the laser processing head (116).

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