The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2017-179332 filed in Japan on Sep. 19, 2017.
The present invention relates to a member joining method through which a plurality of members are joined by welding and to turbine components manufactured through the member joining method.
A turbine used in, for example, a gas turbine or a steam turbine is configured such that a plurality of vanes and a plurality of blades are alternately disposed in a casing along a direction in which combustion gas or steam flows. The vanes are each supported by a shroud mounted inside the casing. The blades are each supported by a rotor. In such a turbine, the combustion gas or the steam passes through the vanes and the blades, which drives to rotate the rotor (see, for example, Japanese Patent No. 3782637).
Turbine blades (vanes and blades) used in the turbine have three-dimensional complicated shapes. Thus, depending on the shape involved, a turbine blade may be divided into a plurality of members that are then manufactured by casting or forging and are joined with each other by welding. In this case, the members manufactured by casting or forging have low dimensional accuracy compared with members manufactured by machining. Thus, welding a joint by forming a groove thereat results in a groove shape varying. Thus, manual TIG welding having tolerances with respect to variation in form accuracy is employed. Because the TIG welding is a welding method involving a large heat input, however, welding deformation is large and a deterioration range (heat affected zone) of the base metal is wide. Thus, the method involves a risk of, for example, a crack occurring in the heat affected zone in, for example, a high strength member including the turbine blade.
Additionally, the TIG welding uses a welding rod for a filler material, however, it is difficult to produce a welding rod made of a high strength material used in, for example, turbine blades working in a severe operating environment. Thus, in the TIG welding, a filler material having a low strength (e.g., Inconel) is used instead of the same material. This limits spots to which welding is applied.
A member joining method according to an aspect of the present invention is for joining a first member with a second member by welding. The method includes performing welding of the first member and the second member from a side of high-temperature use environmental surfaces of the first member and the second member under a condition in which the first member abuts on the second member through hooked portions, each hooked portion being provided on an abutment surface, on which the first member and the second member under abutting, of each of the first member and the second member.
The following describes, with reference to the accompanying drawings, a member joining method and turbine components according to an embodiment of the present invention. The embodiment is not intended to limit the scope of the invention. The elements described with reference to the embodiment include those that can be easily replaced by those skilled in the art, those that are easy, and those that are substantially identical to each other.
The embodiment will be described for the member joining method as applied to a turbine vane joining method (turbine vane manufacturing method).
The airfoil 10 has, for example, a hollow shape. The airfoil 10 includes, under a condition in which the airfoil 10 is disposed in a turbine, a front end portion on the upstream side (left-hand side in
The airfoil 10 has an inside partitioned into a plurality of cavities by a bulkhead. The airfoil 10 has a plurality of cooling holes, not illustrated, that provide communication between the inside and outside. The cooling holes are provided at predetermined positions associated with respective cavities. The airfoil 10 includes a perforated plate disposed inside each of the cavities. The airfoil 10 is subjected to impingement cooling by cooling air supplied to each of the cavities. The cooling air is then jetted out from each cooling hole to thereby subject the airfoil 10 to film cooling.
The airfoil 10 is formed under a condition where the material used for an airfoil is deposited in one direction, for example, in a radial direction Dr. Thus, the airfoil 10 extends in the radial direction Dr. Specifically, an extending direction De of the airfoil 10 coincides with the radial direction Dr. The airfoil 10 has an end on a first side (lower side in
The fillet portions 14 are provided on the side of the outer shroud 30 in the radial direction Dr.
The inner shroud 20 and the outer shroud 30 each function as a gas path surface (high-temperature use environmental surface) forming member. Specifically, the inner shroud 20 has a gas path surface (high-temperature use environmental surface) 20a on a side adjacent to the airfoil 10. The outer shroud 30 has a gas path surface 30a on a side adjacent to the airfoil 10. The gas path surfaces 20a and 30a each assume, when disposed in the turbine, a surface in contact with the combustion gas and each have a temperature rising up to about 900° C. Non-gas path surfaces (low-temperature use environmental surfaces) that are back surfaces of the respective gas path surfaces 20a and 30a each assume, when disposed in the turbine, a surface not in contact with the combustion gas and each have a temperature rising up to about 300° C. to 400° C.
The inner shroud 20 extends in a direction extending along the gas path surface 20a. The direction extending along the gas path surface 20a will hereinafter be referred to as an extending direction Df of the inner shroud 20. Specifically, the extending direction Df of the inner shroud 20 is a direction angled with respect to the extending direction De of the airfoil 10 and is a direction including the axial direction Da and the circumferential direction Dc, and a direction having an axial direction Da component and a circumferential direction Dc component. The outer shroud 30 extends in a direction extending along the gas path surface 30a. The direction extending along the gas path surface 30a will hereinafter be referred to as an extending direction Dg of the outer shroud 30.
Specifically, the extending direction Dg of the outer shroud 30 is a direction angled with respect to the extending direction De of the airfoil 10 and is a direction including the axial direction Da and the circumferential direction Dc, and a direction having an axial direction Da component and a circumferential direction Dc component. It is, however, noted that extending directions of the outer shroud and the inner shroud are not limited to directions specified by reference numerals Df and Dg and are required only to be directions extending along the gas path surfaces 20a and 30a. In addition, although the outer shroud 30 will be exemplarily described as the shroud in the following, the same description applies to the inner shroud 20.
At the airfoil divided body forming step ST10, airfoil divided bodies constituting the airfoil 10 are formed by, for example, a three-dimensional deposition method. At the airfoil divided body forming step ST10, an airfoil divided body 15 as a divided body that constitutes a part of the airfoil 10 is also formed by, for example, the three-dimensional deposition method. Casting, forging, or machining such as cutting may be employed instead of the three-dimensional deposition method. At this time, the airfoil divided body 15 is formed so as to include positioning portions 16 and 17 (see
In the present embodiment, the airfoil divided body 15 is joined with the inner shroud 20 at positions outside the fillet portions 13 in the extending direction Df of the inner shroud 20. The airfoil divided body 15 is joined with the outer shroud 30 at positions outside the fillet portions 14 in the extending direction Dg of the outer shroud 30. Thus, the airfoil divided body 15 is formed so as to include at least the fillet portions 13 and 14.
Additionally, joint grooves 18 are formed at joint portions with the inner shroud 20 and the outer shroud 30. The joint grooves 18 are formed on sides corresponding to the gas path surfaces 20a and 30a of the inner shroud 20 and the outer shroud 30, respectively. The formation of the airfoil 10 and the shroud divided bodies completes the airfoil divided body forming step ST10.
At the shroud divided body forming step ST20, a plurality of shroud divided bodies of at least either one of the inner shroud 20 and the outer shroud 30 are formed individually by, for example, the three-dimensional deposition method. At this time, the shape of the shroud divided body is designed so that a dimension of a joint portion used for joining the shroud divided body is small. The shroud divided body is designed so that, for example, the joint portion is formed at a position at which a distance between a front edge side curved surface portion, a rear edge side curved surface portion, or a back side curved surface portion of the airfoil 10 and an end face 30b or 30c of the outer shroud 30 in the extending direction Dg is small. Additionally, joint grooves 48 (see, for example,
At the shroud joining step ST30, the shroud divided bodies are joined with each other. For the joining, the shroud divided bodies are correctly positioned with each other and the respective joint portions are mated with each other. Under the foregoing condition, the joint portions of the respective shroud divided bodies are welded with each other by, for example, the laser powder build-up welding method. The welding by the laser powder build-up welding method can achieve efficient and rigid welding of the shroud divided bodies. The joining of the respective shroud divided bodies forms joint bodies 25 of the inner shroud 20 and joint bodies 35 of the outer shroud 30.
At the airfoil joining step ST40, the airfoil divided body 15 is joined with the joint bodies 25 and 35. The airfoil joining step ST40 includes a fixing sub-step ST41, a positioning sub-step ST42, and an airfoil divided body joining sub-step ST43. At the fixing sub-step ST41, the positioning portions 16 and 17 of the airfoil divided body 15 are fixed to the first jig 50 and the joint bodies 25 and 35 are fixed to a second jig 60. At the positioning sub-step ST42, the airfoil divided body 15 fixed to the first jig 50 and the joint bodies 25 and 35 fixed to the second jig 60 are positioned correctly with each other. At the airfoil divided body joining sub-step ST43, the airfoil divided body 15 and the joint bodies 25 and 35 that have been positioned correctly with each other are joined with each other.
The airfoil divided body joining sub-step ST43 is performed after the airfoil divided body 15 has been positioned correctly with respect to the joint bodies 25 and 35.
The welding of the airfoil divided body 15 to the joint bodies 25 and 35 through the laser powder build-up welding method is performed in a plurality of sequences. For a first sequence, the welding condition is such that a depth of fusion is obtained and for second and subsequent sequences, the welding condition is such that a welding padding amount is obtained. Specifically, in the first welding sequence, small portions in bottoms of the joint grooves 18 and 48 are welded together and in the second and subsequent welding sequences, build-up welding is performed by weaving until a predetermined padding height is achieved at the joint grooves 18 and 48. Through the foregoing welding sequences, welds 40B are formed between the airfoil divided body 15 and the joint bodies 25 and 35 as illustrated in
The performance of the laser powder build-up welding method may result in the welds 40B bulging from the gas path surfaces 20a and 30a. In this case, bulges on surfaces of the welds 40B are removed so that, for example, the surfaces of the welds 40B are flush with the gas path surfaces 20a and 30a as illustrated in
The technical scope of the present invention is not limited to the above embodiment.
As illustrated in
The joint bodies 25 are placed around the airfoil divided body 15 on the base 201. At this time, the joint bodies 25 are placed on the respective auxiliary jigs 208 fixed to the base 201 and are then aligned with the airfoil divided body 15 in the vertical direction. The second jigs 205 are fixed to the base 201 under a condition in which the second jigs 205 contact outer surfaces of the joint bodies 25 on outer peripheries of the joint bodies 25. The third jigs 206 and 207 have first ends coupled with the column 202, intermediate portions clamping the airfoil divided body 15, and second ends coupled with an upper end of the column 203 by fixing pins 213 and 214. Then, at the positioning sub-step ST42 (see
The airfoil divided body joining sub-step ST43 (see
The performance of the foregoing welding step forms the weld 40B (see
The joint body 35 is placed around the airfoil divided body 15 on the base 201. At this time, the joint body 35 is placed on the corresponding auxiliary jigs 208 fixed to the base 201 and is then aligned with the airfoil divided body 15 in the vertical direction. The second jig 205 is fixed to the base 201 under a condition in which the second jig 205 contacts the outer surface of the joint body 35 on the outer periphery of the joint body 35. The third jigs 206 and 207 have the first ends coupled with the column 202, the intermediate portions clamping the airfoil divided body 15, and the second ends coupled with the upper end of the column 203 by the fixing pins 213 and 214. Then, at the positioning sub-step ST42 (see
The technical scope of the present invention is not limited to the above embodiment.
The turbine vane manufacturing method differs in the airfoil and shroud joining process. In the joining method in the present embodiment, the airfoil is joined with the shroud through a laser melting method. As illustrated in
It is noted that the cutouts 223 and 233 may be formed before or after the positioning of the airfoil divided body 15 and the joint body 25. In the present embodiment, no joint grooves are formed.
After the correct positioning having been made by the jig and after the cutouts 223 and 233 having been formed in the protrusions 222 and 232, the airfoil divided body 15 and the joint body 25 are subjected to welding by the laser melting method from the side of the gas path surface 20a as illustrated in
After the weld 243 and the build-up weld 244 have been formed, the jig is removed from the airfoil divided body 15 and the joint body 25.
In accordance with the member joining method in the present embodiment, in the member joining method that joins the airfoil divided body (first member) 15 with the joint body (second member) 25 or 35 by welding, the welding is performed from the side of the gas path surface (high-temperature use environmental surface) 20a or 30a in the airfoil divided body 15 and the joint body 25 or 35.
Thus, when the airfoil divided body 15 and the joint body 25 or 35 have varying thicknesses depending on different portions thereof, a melt-through bead defect can occur and formation of a favorable melt-through bead is difficult at all welds. Thus, the welding is performed from the side of the gas path surface 20a or 30a in the airfoil divided body 15 and the joint body 25 or 35, whereby the melt-through bead is prevented from being formed at the weld on the gas path surface 20a or 30a, and therefore quality is prevented from being degraded. As a result, the airfoil divided body 15 can be effectively joined with the joint body 25 or 35.
The member joining method in the present embodiment thus provides the joint groove 18 or 48 formed on the side of the gas path surface 20a or 30a in the airfoil divided body 15 and the joint body 25 or 35 and performs welding using the joint groove 18 or 48 from the side of the gas path surface 20a or 30a. Thus, the welding is performed using the joint groove 18 or 48 in the airfoil divided body 15 and the joint body 25 or 35 from the side of the gas path surface 20a or 30a, whereby the joint portion between the airfoil divided body 15 and the joint body 25 or 35 effectively melts and a sufficient depth of fusion is secured, and therefore burn-through is avoided.
Additionally, a sufficient welding padding amount can be obtained.
In the member joining method in the present embodiment, the angle of the joint groove 18 or 48 is set to a range from 20 degrees to 40 degrees. Specifically, the angle of the joint groove 18 or 48 is set so as to fall within an optimum range. This setting prevents lack of penetration, so that quality can be prevented from being degraded. The setting also prevents the amount of weld metal to be used from increasing, so that material cost can be prevented from increasing.
The member joining method in the present embodiment involves performance of welding from the side of the gas path surface 20a or 30a using the laser powder build-up welding method. Thus, the use of the laser powder build-up welding method reduces a deterioration range (heat affected zone) of a base metal at the weld, so that a welding defect including a crack can be prevented. The laser powder build-up welding method also involves a small heat input and thus can prevent deformation by welding.
In the member joining method in the present embodiment, the same material is used for the airfoil divided body 15, the joint body 25 or 35, and the powder used in the laser powder build-up welding method, or a material having higher strength is set. Thus, the use of the same material for the airfoil divided body 15, the joint body 25 or 35, and the powder, or the setting of the material having higher strength allows the strength at the weld to be effectively enhanced.
In the member joining method in the present embodiment, the joint surface between the airfoil divided body 15 and the joint body 25 or 35 is machined to achieve a predetermined thickness in the welding direction and then the welding is performed. The performance of welding after the joint surface between the airfoil divided body 15 and the joint body 25 or 35 has been machined to achieve the predetermined thickness prevents a welding defect from occurring, so that high product quality can be steadily maintained. A defect in the melt-through bead portion, such as underfill, is on the side of the gas path surface 20a or 30a, and thus the defect can be repaired by TIG welding for low strength materials.
In the member joining method in the present embodiment, the airfoil divided body 15 is provided with the positioning portions 16 and 17 and the airfoil divided body 15 is fixed at a position where the joint surfaces are in tight contact with each other, with the jigs 50 and 200 through the positioning portions 16 and 17, and the welding is performed under this condition. Thus, the welding is performed under the condition in which the airfoil divided body 15 is fixed at a position where the joint surfaces are in tight contact with each other, by the jigs 50 and 200 with the positioning portions. As a result the airfoil divided body 15 and the joint body 25 or 35 are readily positioned by the jigs 50 and 200, so that workability can be improved and welding accuracy can be enhanced.
In the member joining method in the present embodiment, the first member is the airfoil divided body 15 of the airfoil 10 having a shape long in a vertical direction, the second member is the joint body 25 or 35 of the inner shroud 20 or the outer shroud 30 disposed around the airfoil divided body 15, and the jig may be the first jig 50 or 204 that supports the positioning portions 16 and 17 formed on both ends in the vertical direction of the airfoil divided body 15, or the second jig 60 or 205 that supports the outer surface of the joint body 25 or 35. The foregoing configuration results in the first jig 50 or 204 supporting the corresponding end of the airfoil divided body 15 and the second jig 60 or 205 supporting the outer surface of the joint body 25 or 35. The airfoil divided body 15 and the joint body 25 or 35 can thus be positioned at proper positions, so that welding accuracy can be enhanced.
In the member joining method in the present embodiment, the jig 200 includes the third jigs 206 and 207 that support the periphery of the airfoil divided body 15. Thus, the third jigs 206 and 207 for supporting the periphery of the airfoil divided body 15 are provided. Accordingly, the third jigs 206 and 207 can prevent the airfoil divided body 15 from collapsing, so that positioning accuracy of the airfoil divided body 15 and the joint body 25 or 35 can be enhanced.
The turbine vane manufacturing method incorporating the member joining method in the present embodiment includes: the airfoil divided body forming step ST10 at which the airfoil divided bodies 15 constituting the airfoil 10 of the turbine vane 100 are formed by the three-dimensional deposition method; the shroud divided body forming step ST20 at which a plurality of shroud divided bodies of at least either one of the inner shroud 20 and the outer shroud 30 of the turbine vane 100 are formed individually by the three-dimensional deposition method; the shroud joining step ST30 at which the shroud divided bodies are joined with each other; and the airfoil joining step ST40 at which the airfoil divided body 15 is joined with the shroud divided bodies.
Thus, the formation of different components individually through the three-dimensional deposition method enables a substantial reduction in the amount of support members used, compared with formation of the airfoil and the shroud as a whole using the three-dimensional deposition method. Thus, time and labor required for the deposition step can be reduced and time and labor required for post-processing of the supporting can be reduced. Thus, the turbine vane 100 can be manufactured even more efficiently.
In the member joining method in the present embodiment, the airfoil divided body 15 includes the fillet portions 13 and 14 of the airfoil 10 and the airfoil joining step ST40 may include joining of the airfoil divided body 15 with the shroud divided body at positions shifted from the fillet portions 13 and 14. In this case, the turbine vane 100 can be manufactured efficiently, while quality is maintained.
The above embodiment has been described for an exemplary case in which the shroud divided bodies are formed for both the inner shroud 20 and the outer shroud 30. The exemplary case is, however, illustrative only and not limiting. For example, the inner shroud 20 and the outer shroud 30 may be formed integrally.
The above embodiment has been described, in the shroud joining step and the airfoil joining step of the turbine vane manufacturing method, for an exemplary case in which the divided bodies are welded together through the laser powder build-up welding method. The welding method is, however, illustrative only and not limiting. For example, the turbine vane manufacturing method may include a welding mode in which other types of welding method (e.g., TIG welding) are used instead of the laser powder build-up welding method. Additionally, the turbine vane may include a weld that is welded by other types of welding method (e.g., TIG welding) instead of the laser powder build-up welding method.
In each of the above embodiments, the airfoil divided bodies 15 constituting the airfoil 10 of the turbine vane 100 and the inner shroud 20 and the outer shroud 30 of the turbine vane 100 are manufactured through the three-dimensional deposition method. The method is, however, illustrative only and not limiting. After the airfoil and the shroud have been manufactured by casting or forging, a joint surface or an excess metal portion of the casting or forging may be finished by machining to form a groove portion. Alternatively, the airfoil and the shroud may be manufactured by cutting blocks by machining.
In each of the above embodiments, the first member is the airfoil 10 (airfoil divided body 15) of the turbine vane 100 and the second member is the inner shroud 20 and the outer shroud 30 of the turbine vane 100 (joint bodies 25 and 35). The specific components are, however, illustrative only and not limiting. The first member and the second member may be applied to other components. For example, the first member and the second member may be any other members that have the high-temperature use environmental surface and the low-temperature use environmental surface, such as for joining an inner cylinder with a transition piece in a gas turbine combustor.
A member joining method according to an aspect of the present invention is for joining a first member with a second member by welding. The method includes performing welding of the first member and the second member from a side of high-temperature use environmental surfaces of the first member and the second member under a condition in which the first member abuts on the second member through hooked portions, each hooked portion being provided on an abutment surface, on which the first member and the second member under abutting, of each of the first member and the second member.
Thus, when the first member and the second member have varying thicknesses depending on different portions thereof, a melt-through bead defect can occur and formation of a favorable melt-through bead is difficult at all welds. Thus, the welding is performed from the side of the high-temperature use environmental surface in the first member and the second member, whereby the melt-through bead is prevented from being formed at the weld on the high-temperature use environmental surface, and therefore quality is prevented from being degraded. As a result, the members can be effectively joined with each other.
Furthermore, the first member is joined with the second member under a condition in which the first member abuts on the second member through the hooked portions, so that even more rigid joining can be achieved.
In the member joining method, the high-temperature use environmental surface of each of the first member and the second member may have a joint groove on the side of the high-temperature use environmental surface, and the welding may be performed from the side of the high-temperature use environmental surfaces using the joint grooves.
Thus, the welding is performed using the joint grooves in the first member and the second member from the side of the high-temperature use environmental surface, whereby a joint portion between the first member and the second member effectively melts and a sufficient depth of fusion is secured, and therefore burn-through is avoided.
Additionally, a sufficient welding padding amount can be obtained.
In the member joining method, the joint grooves may have an angle set to fall within a range from 20 degrees to 40 degrees.
The setting of the angles of the joint grooves to fall within an optimum range prevents lack of penetration, so that quality can be prevented from being degraded. The setting also prevents the amount of weld metal to be used from increasing, so that material cost can be prevented from increasing.
In the member joining method, the welding may be performed from the side of the high-temperature use environmental surfaces by a laser powder build-up welding method.
Thus, the use of the laser powder build-up welding method reduces a deterioration range (heat affected zone) of a base metal at a weld, so that a welding defect including a crack can be prevented. The laser powder build-up welding method also involves a small heat input and thus can prevent deformation by welding.
In the member joining method, the first member, the second member, and powder used in the laser powder build-up welding method may be made of a same material.
Thus, the use of the same material for the first member, the second member, and the powder, or the setting of the material having higher strength allows the strength at the weld to be effectively enhanced.
The member joining method may include machining the first member and the second member so that thicknesses on joint surfaces of the first member and the second member become a predetermined thickness in a welding direction; performing the welding; and repairing machined portions and defective portions of melt-through beads by padding.
The performance of the welding after the joint surfaces between the first member and the second member have been machined to achieve the predetermined thickness and repairing by padding the machined portions and defective portions of the melt-through beads prevent a welding defect from occurring, so that high product quality can be steadily maintained. A defect in the melt-through bead portion, such as underfill, is on a side of a non-high-temperature use environmental surface, and thus the defect can be repaired by TIG welding for low strength materials.
In the member joining method, the first member may have positioning portions. The method may include fixing the first member at a position where joint surfaces of the first member and the second member are in tight contact with each other, with a jig through the positioning portions; and performing the welding under the fixing condition.
Thus, the welding is performed under the condition in which the first member is fixed at a position where the joint surfaces are in tight contact with each other, by the jig with the positioning portions. As a result, the first member and the second member are readily positioned by the jig, so that workability can be improved and welding accuracy can be enhanced.
In the member joining method, the first member may have a shape long in a vertical direction, the second member is disposed around the first member, the jig may be a first jig that supports the positioning portions formed on ends of the first member in the vertical direction, and the second member may have an outer surface supported by a second jig.
The foregoing configuration results in the first jig supporting respective ends of the first member and the second jig supporting the outer surface of the second member. The first member and the second member can thus be positioned at proper positions, so that welding accuracy can be enhanced.
In the member joining method, the first member may have a periphery supported by a third jig.
Thus, the third jig for supporting the periphery of the first member can prevent the first member from collapsing, so that positioning accuracy of the first member and the second member can be enhanced.
In the member joining method, either one or both of the first member and the second member may be formed by a three-dimensional deposition method.
Thus, the formation of either one or both of the first member and the second member individually through the three-dimensional deposition method enables a substantial reduction in the amount of support members used. Thus, time and labor required for a deposition step can be reduced and time and labor required for post-processing of the supporting can be reduced. As a result, the first member and the second member can be efficiently joined with each other.
In the member joining method, the first member may be an airfoil divided body constituting an airfoil of a turbine vane, the second member may include a plurality of shroud divided bodies constituting a shroud of the turbine vane, and the high-temperature use environmental surface may be a gas path surface.
Thus, the turbine vane can be efficiently manufactured.
A turbine component according to another aspect of the present invention is manufactured by the member joining method described above.
Thus, the turbine component can be manufactured even more efficiently.
While certain embodiments have been described, these embodiments are not intended to limit the scope of the inventions. The components in the embodiments include ones that a person skilled in the art can easily conceive of, ones that are substantially the same, or ones that fall in their equivalents. Furthermore, various omissions, substitutions, combinations, and changes may be made as appropriate to configurations of the components disclosed in the embodiments without departing from the spirit of the inventions.
Number | Date | Country | Kind |
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2017-179332 | Sep 2017 | JP | national |