Self-positioning welding fixture and welding method for turbomachine components

Abstract

The application discloses a self-positioning welding fixture for a turbine assembly, which comprises a first positioning assembly, a positioning shaft and a second positioning assembly; the first positioning assembly is provided with a first elastic positioning structure which can be radially folded under external force to clamp the outer ring surface of a first component so that the first component is coaxial with the first positioning assembly; the second positioning assembly is provided with a second elastic positioning structure which can clamp a third component so that the third component is coaxial with the second positioning assembly; the axis position of the first elastic positioning structure is provided with a shaft positioning structure which is radially positioned with the positioning shaft; and the axis position of the second elastic positioning structure is provided with a shaft mounting structure which is used for positioning and fixing the positioning shaft. By using the welding fixture, the first elastic positioning structure is matched with the first component, the second elastic positioning structure is matched with the third component, the first elastic positioning structure and the second elastic positioning structure are coaxial, and then the first component and the third component are coaxial, so that the coaxial degree requirement of the turbine assembly welding is guaranteed, the welding machining precision is improved, and the welding deformation influence is weakened.

Description

Technical Field

[0001] This invention relates to the field of turbine assembly welding technology, and in particular, to a self-positioning welding fixture for turbine assemblies. Furthermore, this invention also relates to a welding method using the aforementioned self-positioning welding fixture for turbine assemblies. Background Technology

[0002] The engine's turbine assembly includes a first component 1, a second component 2, and a third component 3, which are connected sequentially and are all in an annular shape; such as Figure 1 and Figure 2 As shown, the inner annular surface of the second component 2 has a tapered surface with a gradually decreasing outer diameter that protrudes towards the second end face. An annular protrusion 101 is formed on the edge of one end face of the first component 1. The inner annular surface diameter of the annular protrusion 101 matches the outer diameter of the second component 2. The inner annular surface of the first component 1 matches the maximum outer diameter of the tapered surface. The first component 1 covers the second component 2, and the end face of the annular protrusion 101 of the first component 1 abuts against the end face of the third component 3. The inner annular surface of the third component 3 protrudes towards the other end face, and its outer diameter gradually decreases outward. The first component 1 and the third component 3 are connected circumferentially by four 2cm long evenly distributed fillet welds. Figure 3 As shown, the coaxiality of the first component 1 and the third component 3 after welding must be 0.15.

[0003] In the prior art, to ensure the coaxiality of the first component 1 and the third component 3, a welding fixture is usually used for positioning, such as... Figure 4 and Figure 5 As shown, the positioning plate uses ΦD as the positioning reference. The contact surface ΦC between the first component 1 and the positioning plate is guaranteed to be coaxial with the positioning reference A by no more than 0.03. During the welding process, the first component 1 and the third component 3 are constrained at the same time to ensure coaxiality.

[0004] like Figures 3 to 5 As shown, due to the large tolerance zones of the first component 1 and the third component 3, under extreme conditions, a full-circle gap of 0.35mm will be caused between the first component 1 and the positioning plate 71. Even without considering the manufacturing precision of the tooling and the deformation of the parts after welding, a coaxiality of 0.15 cannot be guaranteed. Summary of the Invention

[0005] This invention provides a self-positioning welding fixture and welding method for turbine components to solve the technical problem that the coaxiality of turbine components does not meet the requirements due to existing welding methods.

[0006] The technical solution adopted in this invention is as follows:

[0007] A self-positioning welding fixture for a turbine assembly, the turbine assembly comprising at least a first component, a second component, and a third component connected sequentially and all being annular; the first component has an annular protrusion formed on the edge of its first end face; the first component covers the second component, and the annular protrusion of the first component abuts against the second end face of the third component for welding; the self-positioning welding fixture includes:

[0008] A first positioning component, a positioning axis, and a second positioning component;

[0009] The first end of the first positioning component is provided with a first elastic positioning structure. The first elastic positioning structure is used to radially retract to the outer ring surface of the first component under the action of external force to clamp the first component, thereby making the first component and the first elastic positioning structure located on the same axis.

[0010] The second positioning component has a cavity portion for accommodating the turbine assembly at one end facing the first positioning component; the second positioning component is provided with a second elastic positioning structure, which is used to radially retract onto the outer ring surface of the third component under the action of external force to clamp the third component and thereby make the third component and the second elastic positioning structure located on the same axis.

[0011] The first positioning component is provided with a shaft positioning structure at the axial position of the first elastic positioning structure, which radially positions and cooperates with the positioning shaft. The second positioning component is provided with a shaft mounting structure at the axial position of the second elastic positioning structure for radially positioning and fixing the positioning shaft.

[0012] In a preferred embodiment, the first positioning component includes a cylindrical or tubular positioning member and a tubular first clamping member that matches and is fitted onto the positioning member; the first elastic positioning structure includes clamping pieces formed on the end face of the positioning member, and a plurality of clamping pieces are evenly arranged in a ring along the edge of the end face of the positioning member; the inner wall surface of the closing end of the clamping piece is provided with a first step structure, the axial dimension of the first step structure is adapted to the thickness of the first component, and the inner ring surface of the first step structure is used to clamp the outer ring surface of the first component; the clamping piece protrudes from the outer wall surface of the closing end to form a slope structure, and the inner wall of the end of the first clamping member is formed with an inner conical surface that matches the slope of the slope structure of the clamping piece, so that when the first clamping member fitted onto the positioning member moves axially toward the large end direction of the slope structure, it drives the clamping piece to close radially.

[0013] As a preferred embodiment, the outer wall of one end of the first clamping member that clamps the first component has a welding window or welding notch located at the gap between two adjacent clamping plates for the welding gun to pass through.

[0014] In a preferred embodiment, the positioning member has a first pin hole in the radial direction, and the first clamping member has an oblong hole corresponding to the position of the first pin hole, which is used to restrict the relative rotation of the positioning member and the first clamping member and allow them to move relative to each other axially.

[0015] In a preferred embodiment, the first positioning assembly further includes a driving member for driving the first clamping member to move axially. The free end of the positioning member has a threaded section. The driving member includes a nut that is threadedly connected to the threaded section of the positioning member. The radially protruding part of the nut forms a pressure plate for pressing against the end face of the first clamping member, which, when the nut is tightened, drives the first clamping member to move axially toward the closing end of the positioning member.

[0016] In a preferred embodiment, the first positioning component further includes a stud, and the threaded section of the positioning member is provided with an internal thread at the axial position that is adapted to the stud. The inner end face of the large end of the stud is pressed against the free end face of the nut. The axial position of the stud is provided with a shaft positioning hole that is adapted to the outer diameter of the small end of the positioning shaft, for passing through and radially positioning the small end of the positioning shaft.

[0017] In a preferred embodiment, the second positioning component includes a base and a support cylinder. One end of the base has an open positioning cavity. The inner diameter of the support cylinder is adapted to the outer diameter of the large end of the positioning shaft. The support cylinder is used to radially limit the positioning shaft and is fixed to the positioning cavity of the base via a connector. The support cylinder is used to support the turbine assembly. The elastic positioning structure includes an elastic clamp disposed in the positioning cavity and a second clamping member connected to the open end of the base. The inner wall of the closing end of the elastic clamp is used to clamp the outer ring surface of the third component. The outer wall surface of the closing end of the elastic clamp protrudes to form an outer conical surface, and the inner wall of the second clamping member protrudes to form an inner conical surface that mates with the outer conical surface. This allows the elastic clamp to radially close when the second clamping member moves axially toward the large end of the inner conical surface.

[0018] As a preferred embodiment, the large end of the positioning shaft has a first shoulder, and the inner wall of the end of the support cylinder connected to the base is provided with a second step structure, the inner diameter and height of the second step structure being adapted to the outer diameter and thickness of the first shoulder, respectively.

[0019] As a preferred embodiment, the side wall of the base and the side wall of the elastic clamp are respectively provided with second pin holes at corresponding height positions. The second pin holes are used to insert cylindrical pins to prevent the second clamping member from driving the elastic clamp to rotate.

[0020] According to another aspect of the present invention, a welding method is also provided, using any of the welding fixtures described above, comprising the following steps:

[0021] S1. Use the second positioning component to position the large end of the assembly positioning shaft at the axial position of the second elastic positioning structure;

[0022] S2. Pass the small end of the positioning shaft through the turbine assembly, place the turbine assembly in the second positioning assembly, and clamp the third component by the second elastic positioning structure so that the third component is coaxial with the second elastic positioning structure;

[0023] Before step S1, S2, or S3, the first component is radially closed and clamped by the first elastic positioning structure of the first positioning component to make the first component coaxial with the first elastic positioning structure;

[0024] S3. The small end of the positioning shaft is inserted into the shaft positioning structure so that the positioning shaft is radially positioned and engaged with the first positioning component. The first positioning component, which clamps the first part, is engaged with the second positioning component, which contains the turbine component, so that the first part is pressed against the second part and the end face of the annular protrusion of the first part abuts against the end face of the third part.

[0025] S4. Weld the first and third components;

[0026] S5. Remove the first positioning component, the second positioning component, and the positioning shaft.

[0027] The present invention has the following beneficial effects: The first elastic positioning structure of the first positioning assembly radially converges and clamps the first component, making the first component coaxial with the first elastic positioning structure. The first positioning assembly is not affected by the radial dimensional tolerance of the first component, and there is no full-circumference gap on the clamping surface. The second positioning assembly radially positions and assembles the large end of the positioning shaft, allowing the small end of the positioning shaft to pass through the turbine assembly, placing the turbine assembly in the cavity of the second positioning assembly. The second elastic positioning structure radially converges and clamps the third component, making the third component coaxial with the second elastic positioning structure. The small end of the positioning shaft passes through the shaft positioning structure and radially positions and engages with the first positioning assembly. The first and second elastic structures are located on the same axis based on the positioning shaft, thus ensuring that the first and third components are on the same axis and are not affected by the radial dimensional tolerance of the two components. The radial dimensional tolerance of the component is affected; after the small end of the positioning shaft passes through the shaft positioning structure, the first positioning assembly clamping the first component cooperates with the second positioning assembly containing the turbine assembly, so that the first component is pressed against the second component and the end face of the annular protrusion of the first component abuts against the end face of the third component to complete the clamping, and welding can begin; by using this welding fixture, based on the tight cooperation between the first elastic positioning structure and the first component, the tight cooperation between the second elastic positioning structure and the third component, and based on the positioning shaft, the first elastic positioning mechanism and the second elastic positioning structure are located on the same axis, thereby making the first component and the third component located on the same axis, not only ensuring the coaxiality requirement during the welding of the turbine assembly, but also further improving the machining accuracy of the welding process and effectively reducing the influence of welding deformation of the parts.

[0028] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of a turbine assembly in the prior art;

[0031] Figure 2 This is an exploded view of the structure of a turbine assembly in the prior art;

[0032] Figure 3 This is a schematic diagram showing the dimensional specifications of a turbine assembly in the prior art;

[0033] Figure 4 This is a reference diagram of the usage status of welding fixtures in existing technology;

[0034] Figure 5 This is a schematic diagram of the positioning plate of the welding fixture in the prior art and the clamping and fitting of the turbine assembly;

[0035] Figure 6 This is a cross-sectional view of the welding fixture in use according to a preferred embodiment of the present invention;

[0036] Figure 7 This is a cross-sectional view of the first positioning component structure according to a preferred embodiment of the present invention;

[0037] Figure 8 This is a side view of the first positioning component according to a preferred embodiment of the present invention;

[0038] Figure 9 This is a cross-sectional view of the second positioning component for clamping and positioning the turbine assembly according to a preferred embodiment of the present invention.

[0039] 1. First component 101, Annular protrusion 2. Second component 3. Third component 4. Positioning shaft 41, First shoulder 5. Positioning element 51, Clamping piece 511, First step structure 512, Inclined surface structure 52, First pin hole 53, Threaded section 54, Shaft hole 6. First clamping element 61, Inner conical surface 62, Welding notch 63, Waist-shaped hole 7. Nut 71, Pressure plate 8. Base 9. Elastic clamp 91, Outer conical surface 10. Support cylinder 11. Connecting element 12, Second clamping element 13, Cylindrical pin 14, Stud Detailed Implementation

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Reference Figures 6 to 9 A preferred embodiment of the present invention provides a self-positioning welding fixture for a turbine assembly, wherein the turbine assembly includes at least a first component 1, a second component 2, and a third component 3 connected in sequence and all being annular; the end face of the first component 1 has an annular groove, the inner diameter of the annular groove is greater than the outer diameter of the second component 2 or the two are adapted to each other, the height of the annular groove is greater than the thickness of the second component 2 or the two are adapted to each other, the first component 1 covers the second component 2 and the annular protrusion 101 of the first component 1 abuts against the end face of the third component 3 and is to be welded, the inner annular surface of the third component 3 protrudes towards the first end face and the outer radial direction gradually decreases towards the outer end;

[0042] This self-positioning welding fixture includes:

[0043] The first positioning component, the positioning axis 4, and the second positioning component;

[0044] The first positioning component is provided with a first elastic positioning structure. The first elastic positioning structure is used to radially converge to the outer ring surface of the first component 1 under the action of external force and clamp the first component 1 so that the first component 1 and the first elastic positioning structure are located on the same axis.

[0045] The second positioning component has a cavity for accommodating the turbine assembly at one end facing the first positioning component; the second positioning component is provided with a second elastic positioning structure, which is used to radially converge to the outer ring surface of the third component 3 under the action of external force to clamp the third component 3 and thus make the third component 3 and the second elastic positioning structure coaxial.

[0046] The first positioning component is provided with a shaft positioning structure at the axial position of the first elastic positioning structure, which is radially positioned and cooperates with the positioning shaft 4. The second positioning component is provided with a shaft mounting structure at the axial position of the second elastic positioning structure for radially positioning and fixing the positioning shaft 4.

[0047] The working principle of this welding fixture is as follows: The first elastic positioning structure of the first positioning assembly radially closes and clamps the first component 1, making the first component 1 coaxial with the first elastic positioning structure. The first positioning assembly is unaffected by the radial dimensional tolerance of the first component 1, and there is no full-circumference gap on the clamping surface. The second positioning assembly radially positions and assembles the large end of the positioning shaft 4, allowing the small end of the positioning shaft 4 to pass through the turbine assembly, placing the turbine assembly in the cavity of the second positioning assembly. The second elastic positioning structure radially closes and clamps the third component 3, making the third component 3 coaxial with the second elastic positioning structure. The small end of the positioning shaft 4 passes through the shaft positioning structure and radially positions and engages with the first positioning assembly. The first and second elastic structures are located on the same axis based on the positioning shaft 4, thus placing the first component 1 and the third component 3 on the same axis, and unaffected by the radial dimensional tolerance of the two components. Radial dimensional tolerance affects the clamping mechanism. After the small end of the positioning shaft 4 passes through the shaft positioning structure, the first positioning assembly, which clamps the first component 1, cooperates with the second positioning assembly, which holds the turbine assembly, so that the first component 1 is pressed against the second component 2 and the end face of the annular protrusion 101 of the first component 1 abuts against the end face of the third component 3 to complete the clamping, and welding can then begin. By using this welding fixture, based on the tight cooperation between the first elastic positioning structure and the first component 1, and the tight cooperation between the second elastic positioning structure and the third component 3, and based on the positioning shaft 4, the first elastic positioning mechanism and the second elastic positioning structure are located on the same axis, thereby making the first component 1 and the third component 3 located on the same axis. This not only ensures the coaxiality requirement during turbine assembly welding, but also further improves the machining accuracy of welding and effectively reduces the influence of welding deformation of parts.

[0048] This fixture can be further applied to various types of welded parts with high coaxiality requirements and large tolerance zones.

[0049] Specifically, the first positioning component includes a cylindrical or tubular positioning member 5, a tubular first clamping member 6 sleeved on the positioning member 5, and a driving member for driving the first clamping member 6 to move axially; the first elastic positioning structure includes clamping pieces 51 formed on the end face of the positioning member 5, and multiple clamping pieces 51 are evenly arranged in a ring along the edge of the first end face of the positioning member 5; the inner wall surface of the closing end of the clamping piece 51 is provided with a first step structure 511, the axial dimension of the first step structure 511 is adapted to the thickness of the first component 1, thereby enabling clamping during the clamping process. The first component 1 is axially limited to facilitate clamping and fixing; the inner ring surface of the first step structure 511 is used to clamp the outer ring surface of the first component 1; the clamping piece 51 protrudes from the outer wall surface of the closing end to form a slope structure 512, and the inner wall of the end of the first pressing member 6 forms an inner conical surface 61 that matches the slope of the slope structure 512 of the clamping piece 51, so that when the first pressing member 6 sleeved on the positioning member 5 moves axially toward the large end direction of the slope structure 512, it drives the clamping piece 51 to radially close, thereby clamping it on the outer ring surface of the first component 1 and maintaining the same axis;

[0050] It should be noted that in this embodiment, a four-lobed clamping piece 51 is used, and the clamping piece 51 is preferably an arc-shaped piece, the curvature of which is adapted to the outer ring surface of the positioning member 5; similarly, the inner ring surface of the first step structure 511 is adapted to the outer ring surface of the first component 1 and should be slightly larger than the maximum size of its outer ring surface.

[0051] The first end of the first clamping member 6 has a welding window or welding notch 62 located at the gap between two adjacent clamping pieces 51 for the welding gun to pass through, which facilitates the welding operation after the fixture is clamped.

[0052] Based on the above technical solution, the positioning member 5 is radially provided with a first pin hole 52, and the first clamping member 6 is provided with an oblong hole 63 corresponding to the position of the first pin hole 52. This is used to limit the relative rotation of the positioning member 5 and the first clamping member 6 and to allow relative axial movement, that is, to maintain the relative position of the welding window / notch and the gap of the clamping piece 51, and to avoid interference caused by rotation. The oblong hole 63 is provided so that the pin inserted into the first pin hole 52 can move relative to the axial direction within the oblong hole 63, thereby allowing the first clamping member 6 to move axially relative to the positioning member 5 to press and close the clamping piece 51 or to release it, without relative rotation.

[0053] Specifically, the driving component includes a nut 7 threadedly connected to the free end of the positioning component 5. The radially protruding part of the nut 7 forms a pressure plate 71 for pressing against the end face of the first clamping component 6, which is used to drive the first clamping component 6 to move axially towards the closing end of the positioning component 5 when the nut 7 is tightened. It should be noted that, based on the setting position of the driving component, the radial dimension of the inclined surface structure 512 in this embodiment gradually increases from the free end of the positioning component 5 to the closing end. It can be understood that the end of the free end of the positioning component 5 has a threaded section 53, and the threaded section 53 is provided with an external thread that is adapted to the nut 7.

[0054] Furthermore, the shaft positioning structure includes a stud 14. The threaded section 53 of the positioning member 5 is also provided with an internal thread at the shaft center position that is adapted to the stud 14. The large end of the stud 14 radially protrudes an annular protrusion 101 that is similar to the aforementioned pressure plate 71, so as to press against the free end face of the nut 7. A shaft positioning hole is opened at the shaft center position of the stud 14 for passing through the small end of the positioning shaft 4 and adapting to its small end outer diameter. The stud 14 can further keep the positioning member 5 and the positioning shaft 4 on the same axis, thereby improving the positioning accuracy.

[0055] In this embodiment, the second positioning component includes a base 8 and a support cylinder 10. The base 8 has a positioning cavity with one open end. The inner diameter of the support cylinder 10 is adapted to the outer diameter of the large end of the positioning shaft 4. The support cylinder 10 is used to radially limit the positioning shaft 4 and is fixed in the positioning cavity of the base 8 through a connector 11. Multiple threaded holes are evenly arranged on the end face of the support cylinder 10 connected to the base. A countersunk hole is correspondingly provided at the bottom of the base 8. The connector 11 is a screw that passes through the countersunk hole and connects to the bottom end of the support cylinder 10. The second end of the support cylinder 10 is used to support the turbine assembly. The height of the support cylinder 10 is less than the height of the base 8, thus... A cavity is formed between the end face of the support cylinder 10 and the inner wall of the base 8; the elastic positioning structure includes an elastic clamping cylinder 9 disposed in the positioning cavity and a second clamping member 12 connected to the second end of the base 8; the inner wall of the second end of the elastic clamping cylinder 9 is used to clamp the outer ring surface of the third component 3; the outer wall of the second end of the elastic clamping cylinder 9 protrudes to form an outer conical surface 91, and the inner wall of the second end of the second clamping member 12 protrudes to form an inner conical surface 61 that cooperates with the outer conical surface 91, so that when the second clamping member 12 moves axially toward the large end direction of the inner conical surface 61, it drives the elastic clamping cylinder 9 to radially retract, thereby clamping it on the outer ring surface of the third component 3 and maintaining the same axis;

[0056] It should be noted that the outer wall of the second end of the base 8 is provided with an external thread, and the first end of the second clamping member 12 is provided with an internal thread to be threadedly connected to the base 8. The second clamping member 12 can be rotated to move axially relative to the base 8, thereby driving the elastic clamp 9 to retract radially. The side wall of the base 8 and the side wall of the elastic clamp 9 are provided with a second pin hole at a corresponding height position to insert a cylindrical pin 13 to prevent the second clamping member 12 from driving the elastic clamp 9 to rotate and thus driving the turbine assembly to rotate.

[0057] Specifically, the large end of the positioning shaft 4 has a first shoulder 41, and the shaft mounting structure includes a second step structure provided on the inner wall of the first end of the support cylinder 10. The inner diameter and height of the second step structure are adapted to the outer diameter and thickness of the first shoulder 41, thereby radially positioning and axially limiting and fixing the positioning shaft 4.

[0058] On the other hand, a preferred embodiment of the present invention also provides a welding method using the above-mentioned welding fixture, comprising the following steps:

[0059] S1. Use the second positioning component to position the large end of the assembly positioning shaft 4 at the axial position of the second elastic positioning structure;

[0060] S2. Pass the small end of the positioning shaft 4 through the turbine assembly, place the turbine assembly in the second positioning assembly, and clamp the third component 3 by the second elastic positioning structure so that the third component 3 is coaxial with the second elastic positioning structure.

[0061] It is understood that before step S1 or S2 or S3, the first component 1 is radially closed and clamped by the first elastic positioning structure of the first positioning component to make the first component 1 coaxial with the first elastic positioning structure.

[0062] S3. The small end of the positioning shaft 4 is inserted into the shaft positioning structure so that the positioning shaft 4 is radially positioned and engaged with the first positioning component. The first positioning component, which clamps the first part 1, is engaged with the second positioning component, which contains the turbine component, so that the first part 1 is pressed against the second part 2 and the end face of the annular protrusion 101 of the first part 1 abuts against the second end face of the third part 3.

[0063] S4. Weld the first component 1 and the third component 3;

[0064] S5. Remove the first positioning component, the second positioning component, and the positioning shaft 4.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-positioning welding fixture for a turbine assembly, the turbine assembly comprising at least a first component (1), a second component (2), and a third component (3) connected sequentially and all being annular; the first end face edge of the first component (1) has an annular protrusion (101), the first component (1) covers the second component (2), and the annular protrusion (101) of the first component (1) abuts against the second end face of the third component (3) and is to be welded, characterized in that, The self-positioning welding fixture includes: The first positioning component, the positioning axis (4), and the second positioning component; The first positioning component is provided with a first elastic positioning structure. The first elastic positioning structure is used to radially converge to the outer ring surface of the first component (1) under the action of external force and clamp the first component (1) so that the first component (1) and the first elastic positioning structure are located on the same axis. The second positioning component has a cavity portion for accommodating the turbine assembly at one end facing the first positioning component; the second positioning component is provided with a second elastic positioning structure, which is used to radially converge to the outer ring surface of the third component (3) under the action of external force and clamp the third component (3) so that the third component (3) and the second elastic positioning structure are located on the same axis; The first positioning component is provided with a shaft positioning structure at the axial position of the first elastic positioning structure, which is radially positioned and cooperates with the positioning shaft (4); the second positioning component is provided with a shaft mounting structure at the axial position of the second elastic positioning structure for radially positioning and fixing the positioning shaft (4). The first positioning component includes a cylindrical or tubular positioning element (5) and a tubular first clamping element (6) that matches and is fitted onto the positioning element (5); the first elastic positioning structure includes clamping pieces (51) formed on the end face of the positioning element (5), and a plurality of clamping pieces (51) are evenly arranged in a ring along the edge of the end face of the positioning element (5); the inner wall surface of the folding end of the clamping piece (51) is provided with a first step structure (511), and the axial dimension of the first step structure (511) is the same as that of the first component (1). The thickness of the first step structure (511) is adapted to the outer ring surface of the first component (1). The clamping piece (51) has a sloping structure (512) protruding from the outer wall surface of the closing end. The inner wall of the end of the first pressing member (6) has an inner conical surface (61) that matches the slope of the sloping structure (512) of the clamping piece (51). This is used to drive the clamping piece (51) to radially close when the first pressing member (6) sleeved on the positioning member (5) moves axially toward the large end of the sloping structure (512).

2. The self-positioning welding fixture for turbine assemblies according to claim 1, characterized in that, The outer wall of the first clamping member (6) clamping the first component (1) has a welding window or welding notch (62) for the welding gun to pass through, located at the gap between two adjacent clamping pieces (51).

3. The self-positioning welding fixture for turbine assemblies according to claim 2, characterized in that, The positioning member (5) has a first pin hole (52) in the radial direction, and the first clamping member (6) has a waist-shaped hole (63) at the position corresponding to the first pin hole (52), which is used to restrict the relative rotation of the positioning member (5) and the first clamping member (6) and allow them to move relative to each other axially.

4. The self-positioning welding fixture for turbine assemblies according to claim 1, characterized in that, The first positioning component further includes a driving member for driving the first clamping member (6) to move axially. The free end of the positioning member (5) has a threaded section (53). The driving member includes a nut (7) that is threadedly connected to the threaded section (53) of the positioning member (5). The nut (7) has a radially protruding pressure plate (71) for pressing against the end face of the first clamping member (6). When the nut (7) is tightened, the first clamping member (6) is driven to move axially toward the closing end of the positioning member (5).

5. The self-positioning welding fixture for turbine assemblies according to claim 4, characterized in that, The shaft positioning structure includes a stud (14). The threaded section (53) of the positioning member (5) is also provided with an internal thread that is compatible with the stud (14) at the axial center position. The inner end face of the large end of the stud (14) abuts against the free end face of the nut (7). The axial center position of the stud (14) is provided with a shaft positioning hole that is compatible with the outer diameter of the small end of the positioning shaft (4) for passing through and radially positioning the small end of the positioning shaft (4).

6. The self-positioning welding fixture for turbine assemblies according to any one of claims 1-5, characterized in that, The second positioning assembly includes a base (8) and a support cylinder (10). One end of the base (8) has an open positioning cavity. The inner diameter of the support cylinder (10) is adapted to the outer diameter of the large end of the positioning shaft (4). The support cylinder (10) is used to radially limit the positioning shaft (4) and is fixed in the positioning cavity of the base (8) by a connector (11). The support cylinder (10) is used to support the turbine assembly. The elastic positioning structure includes an elastic clamp (9) disposed in the positioning cavity. And a second clamping member (12) connected to the open end of the base (8); the inner wall of the closing end of the elastic clamp (9) is used to clamp the outer ring surface of the third component (3); the outer wall surface of the closing end of the elastic clamp (9) protrudes to form an outer conical surface (91), and the inner wall of the second clamping member (12) protrudes to form an inner conical surface (61) that cooperates with the outer conical surface (91), which is used to drive the elastic clamp (9) to radially close when the second clamping member (12) moves axially toward the large end of the inner conical surface (61).

7. The self-positioning welding fixture for turbine assemblies according to claim 6, characterized in that, The large end of the positioning shaft (4) has a first shoulder (41). The shaft mounting structure includes a second step structure provided on the inner wall of one end of the support cylinder (10) that is connected to the base. The inner diameter and height of the second step structure are respectively adapted to the outer diameter and thickness of the first shoulder (41).

8. The self-positioning welding fixture for turbine assemblies according to claim 6, characterized in that, The side wall of the base (8) and the side wall of the elastic clamp (9) are respectively provided with second pin holes at corresponding height positions. The second pin holes are used to insert cylindrical pins (13) to prevent the second clamping member (12) from driving the elastic clamp (9) to rotate.

9. A welding method for turbine components, characterized in that, The welding fixture described in any one of claims 1-8 comprises the following steps: S1. Use the second positioning component to position the large end of the assembly positioning shaft (4) at the axial position of the second elastic positioning structure; S2. Pass the small end of the positioning shaft (4) through the turbine assembly, place the turbine assembly in the second positioning assembly, and clamp the third part (3) by the second elastic positioning structure to make the third part (3) coaxial with the second elastic positioning structure; Before step S1 or S2 or S3, the first component (1) is radially clamped by the first elastic positioning structure of the first positioning component to make the first component (1) coaxial with the first elastic positioning structure; S3. The small end of the positioning shaft (4) is inserted into the shaft positioning structure so that the positioning shaft (4) is radially positioned and engaged with the first positioning component. The first positioning component, which clamps the first part (1), is engaged with the second positioning component, which contains the turbine component, so that the first part (1) is pressed against the second part (2) and the end face of the annular protrusion (101) of the first part (1) abuts against the end face of the third part (3). S4. Weld the first component (1) and the third component (3); S5. Remove the first positioning component, the second positioning component, and the positioning shaft (4).

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