A radial diffuser screw seat welding fixture and vacuum brazing process thereof

Abstract

The invention relates to a radial diffuser screw seat welding fixture and a vacuum brazing process thereof. The radial diffuser vacuum brazing process improves the filling method of the screw seat brazing material, changes the commonly used circumferential placement of the brazing material to lower end face placement and circumferential placement of a small amount, completely avoids the circumferential brazing material from melting and hanging upside down on the screw seat surface during the brazing process, and saves the brazing material cleaning process after welding; considering the brazing deformation, the overall brazing fixture is designed to be made of graphite material, and the brazing parts are constrained by an assembly method of pressing up and down, and the deformation and jump of the front and rear cover plates are controlled, thereby solving the problems of large end face brazing deformation of the radial diffuser and inverted hanging / stagnation interference of the screw seat brazing material; by using a combined detection method of visual inspection + metallographic inspection of furnace test pieces, hardness, shear strength, and pull-off force detection for two brazing seam quality inspections of the parts, qualified brazing parts can be effectively screened out.

Description

[0001] This application is a divisional application. The application number of the original application is: 202011483760.4. The name of the invention is: A radial diffuser vacuum brazing process and its quality inspection method. The application date is: 20201216. Technical Field

[0002] The invention relates to the technical field of aviation engine parts, in particular to a radial diffuser vacuum brazing process and a quality inspection method thereof. Background Art

[0003] The radial diffuser assembly consists of radial diffuser, screw seat and other parts, such as Figure 1 As shown, the radial diffuser includes an upper ring piece 1, a lower ring piece 3 and a plurality of guide vanes 2. The upper and lower ring pieces of the radial diffuser each have five evenly distributed screw seats 4. The screw seats 4 of the upper ring piece 1 correspond to the screw seats 4 of the lower ring piece 3. The screw seats 5 are connected to the upper and lower ring pieces of the radial diffuser by welding. Figure 2 As shown, the screw seat 4 includes a thin circular flange portion 42 and a cylindrical threaded portion 41, and the periphery of the flange portion 42 is used for welding. Patent application number CN202010633300.9, entitled A radial diffuser screw seat welding fixture and its use method, describes the fixture used in the welding of the radial diffuser screw seat and its use method, which solves the problem of position accuracy.

[0004] In the process of welding the radial diffuser and the screw seat mentioned above, our company adopts the vacuum brazing process, and vacuum brazing usually adopts the method of circumferential filling of brazing material. After heating and melting, the brazing material is sucked into the brazing seam through capillary action to achieve connection. However, this part has screw seats on both end faces. When entering the furnace for welding, one side of the screw seat must be upside down. If the screw seat brazing material is placed circumferentially, the brazing material will be upside down. Considering that the radial diffuser is thin-walled martensitic stainless steel, the front and rear cover plates are easy to deform and the end face runout is large after high-temperature brazing. Therefore, measures must be taken to solve the problems of large end face brazing deformation of the radial diffuser, upside down / accumulation interference of the screw seat brazing material, etc.

[0005] After the radial diffuser is welded to the blades and the screw seat, there are two structural forms of brazing seams, namely, a T-shaped weld between the blades and the inner wall of the corresponding upper ring piece or lower ring piece, and a flat lap weld between the screw seat and the outer wall of the corresponding upper ring piece or lower ring piece. The X-ray and ultrasonic testing in the prior art cannot simultaneously detect and judge the quality of the two welds. Therefore, it is necessary to design a brazing seam quality inspection method suitable for the radial diffuser assembly. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a radial diffuser screw seat welding fixture, as well as a radial diffuser vacuum brazing process with simple operation and high precision and a quality inspection method thereof.

[0007] In order to solve the above technical problems, the present invention provides a radial diffuser vacuum brazing process, comprising the following steps:

[0008] A. Insert the protruding positioning pins into each positioning pin hole, place the five screw seats into the five screw seat receiving grooves of the lower seat respectively, the threaded part of the screw seat extends into the cylindrical part, and the flange part of the screw seat is placed at the open end of the frustum part. Fill the brazing material between the outer ring side wall of the screw seat flange and the inner wall of the frustum part along the circumferential direction, and lay the brazing material on the end face of the flange part. The shallow arc groove of each screw seat flange is clamped into the positioning pin, and the screw seat is preliminarily positioned by the positioning pin.

[0009] B. Screw the positioning screws from the through-hole portion of each center through hole into the center through hole, so that the positioning screws are threadedly connected with the screw seat, and the screw seat is accurately positioned by the positioning screws and the positioning pins on both sides.

[0010] C. Sleeve the radial diffuser on the lower seat ring platform of the lower seat, so that the lower ring sheet of the radial diffuser is close to the positioning seat of the lower seat, and the brazing material on the end face of the screw seat flange is placed between the lower ring sheet and the screw seat.

[0011] D. Place the five screw seats into the five screw seat receiving grooves of the upper seat respectively, with the threaded portion of the screw seat extending into the cylindrical portion, and the flange portion of the screw seat placed at the open end of the frustum portion. Fill the brazing material circumferentially between the outer ring side wall of the screw seat flange portion and the inner wall of the frustum portion, and apply the brazing material on the end surface of the flange portion. The shallow arc groove of each screw seat flange portion is inserted into the positioning pin, and the screw seat is preliminarily positioned by the positioning pin; screw the positioning screw from the through hole portion of each center through hole into the center through hole, so that the positioning screw is threadedly connected to the screw seat, and the screw seat is accurately positioned by the positioning screw and the positioning pins on both sides.

[0012] E. Invert the assembled radial diffuser and lower seat so that the upper seat ring of the upper seat is inserted into the lower seat ring, and the upper ring of the radial diffuser is close to the positioning seat of the upper seat, and the brazing material on the end face of the screw seat flange is placed between the upper ring and the screw seat.

[0013] F. Rotate the upper seat so that the lower seat positioning hole of the lower seat is aligned with the angular positioning hole of the upper seat, and insert the angular positioning pin into the lower seat positioning hole and the angular positioning hole to ensure that the screw seat of the upper seat is aligned with the screw seat of the lower seat.

[0014] G. Rotate the radial diffuser and adjust the circumferential position of the radial diffuser so that the screw seat is in the preset assembly position of the radial diffuser. Screw in the radial positioning screw so that the radial positioning screw abuts against the guide vane to prevent the radial diffuser from rotating. Screw the clamping screw into the clamping screw hole of the upper seat and the clamping screw hole of the lower seat so that the upper seat and the lower seat fix the radial diffuser.

[0015] H. For the radial diffuser that has been clamped, each screw seat and the corresponding upper ring piece or lower ring piece are spot-welded and positioned through the spot welding grooves, and then the brazing material is welded and fused using the vacuum brazing process, so that the end face of the screw seat and the outer ring side wall of the flange are welded and fixed to the corresponding upper ring piece or lower ring piece through the brazing material; at the same time, three furnace test pieces are welded in the same furnace, namely the first furnace test piece of T-shape, the second furnace test piece of flat stepped shape, and the third furnace test piece after the screw seat is welded to the sheet.

[0016] Furthermore, the upper seat and the lower seat are made of graphite, which is resistant to high temperatures and not easily deformed.

[0017] Furthermore, the welded radial diffuser assembly, the first test piece, the second test piece and the third test piece are subjected to tempering heat treatment in the same furnace, the tempering temperature is 580-585° C., and the holding time is not less than 2 hours.

[0018] Furthermore, the first furnace test piece is used for dissecting and inspecting the metallographic structure, the second furnace test piece is used for inspecting the shear strength, and the third furnace test piece is used for inspecting the hardness and the pull-off force.

[0019] Furthermore, the quality inspection method of the radial diffuser after vacuum brazing comprises the following steps:

[0020] A. Take out the radial diffuser and the first, second and third test pieces that have been heat treated. After cooling, use a hardness tester to check the hardness of the screw seat flange of the third test piece.

[0021] B. Check the pull-off force between the screw seat and the sheet in the third furnace test piece.

[0022] C. Carry out metallographic examination on the first T-shaped test piece.

[0023] D. Carry out shear strength inspection on the flat stepped second furnace test piece.

[0024] Technical effects of the invention: (1) Compared with the prior art, the radial diffuser vacuum brazing process of the present invention first improves the filling method of the screw seat brazing material, and changes the commonly used circumferential placement of the brazing material to placement on the lower end face and a small amount of circumferential placement, which completely avoids the melting of the circumferential brazing material on the surface of the screw seat during brazing, and eliminates the brazing material cleaning process after welding; since the gap between the outer ring side wall of the screw seat flange and the inner wall of the cone part is small, the placement amount of the brazing material is effectively reduced, and the excess brazing material is prevented from affecting the screw seat during welding; (2) Considering the brazing deformation, the overall brazing fixture is designed to be made of graphite material, and the brazing parts are constrained by the assembly method of pressing up and down, so as to control the deformation and vibration of the front and rear cover plates. The problems of large brazing deformation of the end face of the radial diffuser and inverted / accumulated interference of the brazing material in the screw seat are solved; (3) Since the brazing material is placed on the lower end face of the screw seat and a small amount of brazing material is placed circumferentially on the flange, a weld in the form of a stepped flat structure is formed between the screw seat and the outer wall of the corresponding upper ring or lower ring, and a T-shaped weld structure is formed between the blade and the inner wall of the upper ring or lower ring. Since the welds of the two structures affect each other during inspection, the existing X-ray and ultrasonic inspections cannot simultaneously detect and evaluate the weld quality. Therefore, a combined inspection method of visual inspection + metallographic inspection of furnace test pieces, hardness, shear strength, and pull-off force inspection is designed for the brazing seam quality inspection of this part, which can effectively screen out qualified brazed parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0026] Figure 1 is a schematic diagram of the three-dimensional structure of the radial diffuser assembly;

[0027] Figure 2 It is a schematic diagram of the three-dimensional structure of the screw seat;

[0028] Figure 3 This is a schematic diagram of the structure of the upper seat;

[0029] Figure 4 It is a partial enlarged schematic diagram of the positioning seat;

[0030] Figure 5 It is a schematic diagram of the cross-sectional structure of the upper seat;

[0031] Figure 6 It is a schematic diagram of the structure of the lower seat;

[0032] Figure 7 It is a schematic diagram of the cross-sectional structure after the upper seat, radial diffuser and lower seat are assembled;

[0033] Figure 8 It is a schematic diagram of the structure of the positioning screw;

[0034] Fig. 9 It is a schematic diagram of the structure of the radial positioning screw;

[0035] Fig.10 is a schematic diagram of the first furnace test piece;

[0036] Fig.11 is a schematic diagram of the second furnace test piece;

[0037] Fig.12 This is a schematic diagram of the third furnace test piece.

[0038] In the figure: upper ring piece 1, guide vane 2, lower ring piece 3, screw seat 4, threaded portion 41, flange portion 42, upper seat 5, upper seat ring body 51, upper seat ring platform 52, positioning seat 53, angular positioning hole 54, radial screw hole 55, upper seat clamping screw hole 56, screw seat accommodating groove 6, spot welding groove 61, center through hole 62, positioning pin hole 63, receiving beam 64, frustum portion 65, cylindrical portion 66, through hole portion 67, radial positioning screw 7, lower seat 8, angular positioning pin 81, positioning screw 82, lower seat positioning hole 83, clamping screw 84. DETAILED DESCRIPTION Example

[0039] The radial diffuser vacuum brazing process of this embodiment requires the use of a radial diffuser screw seat welding fixture made of graphite material, such as Figures 3 to 9 As shown, the radial diffuser screw seat welding fixture includes an upper seat 5, a lower seat 8, and a positioning screw 82 threadedly matched with the screw seat 4, the upper seat 5 includes an upper seat ring body 51 and an upper seat ring platform 52 integrally formed, the upper seat ring body 51 is annular, and the upper seat ring platform 52 is protrudingly arranged at the front end of the upper seat ring body 51 so that an upper seat step is formed between the upper seat ring platform 52 and the upper seat ring body 51, and the lower seat 8 includes a lower seat ring body and a lower seat ring platform integrally formed, and the lower seat ring platform is concavely arranged so that a lower seat step is formed between the lower seat ring platform and the lower seat ring body, and the upper seat ring platform 52 and the lower seat ring platform can be sleeved and matched; the outer diameter of the lower seat ring platform is smaller than the inner diameter of the radial diffuser (i.e., the inner diameter of the upper ring sheet 1 and the lower ring sheet 3), so that when the radial diffuser is sleeved with the upper seat ring platform 52 and the lower seat ring platform, the upper seat ring platform 52 extends into the lower seat ring platform, and the outer wall of the lower seat ring platform and the inner wall of the radial diffuser are gap-matched.

[0040] Five radially protruding positioning seats 53 are evenly distributed on the side walls of the upper ring body 51 and the side walls of the lower ring body. A circular screw seat accommodating groove 6 is set through the center of each positioning seat 53. Each screw seat accommodating groove 6 is placed on the same circumference. A receiving crossbeam 64 is radially arranged in the screw seat accommodating groove 6. A central through hole 62 that matches the shape of the screw seat 4 is arranged at the center of the receiving crossbeam 64. The central through hole 62 includes a frustum portion 65, a cylindrical portion 66 and a through hole portion 67. The inner diameter of the open end of the frustum portion 65 is not larger than the outer diameter of the screw seat flange portion 42, and the inner diameter of the cylindrical portion 66 is larger than the outer diameter of the threaded portion 41. The through hole portion 67 is clearance-matched with the positioning screw 82, and fan-shaped spot welding grooves 61 are formed on both sides of the receiving crossbeam 64. Locating pin holes 63 are respectively provided on both sides of the central through hole 62, and shallow arc grooves are provided on both sides of the flange portion 42 of the screw seat 4. When in use, the threaded portion 41 of the screw seat 4 extends into the central through hole 62, and a locating pin is protruding from the locating pin hole 63, and the locating pin is inserted into the shallow arc groove of the flange portion 42. The locating screw 82 extends into the central through hole 62 and is threadedly connected with the screw seat 4. The screw seat 4 is limited by the locating pin and the locating screw 82, so that the flange portion 42 of the screw seat 4 is placed at the open end of the frustum portion 65, and the upper seat ring platform 52 of the upper seat 5 and the lower seat ring platform of the lower seat 8 are inserted into the radial diffuser, so that the upper ring plate 1 of the radial diffuser is tightly against the locating seat 53 on the upper seat 5, and the lower ring plate 3 of the radial diffuser is tightly against the locating seat on the lower seat 8.

[0041] In order to prevent the upper seat 5, the lower seat 8 and the radial diffuser from rotating after assembly, the radial diffuser screw seat welding fixture also includes a radial positioning screw, a radial screw hole that cooperates with the radial positioning screw thread is arranged on the upper seat ring platform, and an avoidance groove is arranged on the lower seat ring platform, so that after the upper seat ring platform and the lower seat ring platform are sleeved, the radial positioning screw can extend out of the upper seat ring platform and the lower seat ring platform and abut against the guide vane of the radial diffuser.

[0042] In order to ensure that the screw seats of the upper ring plate and the lower ring plate of the radial diffuser correspond one to one during assembly, the radial diffuser screw seat welding fixture also includes an angular positioning pin 81, an angular positioning hole 54 compatible with the angular positioning pin 81 is axially arranged on the upper seat ring platform 52, and a lower seat positioning hole 83 corresponding to the angular positioning hole 54 is arranged on the lower seat ring body, so that when the upper seat 5 and the lower seat 8 are placed at both ends of the radial diffuser after assembly, the angular positioning pin 81 is inserted into the corresponding angular positioning hole 54 and the lower seat positioning hole 83 to ensure the angular position relationship between the upper seat 5 and the lower seat 8.

[0043] The radial diffuser screw seat welding fixture also includes 6 clamping screws 84, 6 upper seat clamping screw holes 56 threadedly matched with the clamping screws 84 are evenly distributed on the upper seat ring platform 52, and 6 lower seat clamping screw holes corresponding to the upper seat clamping screw holes 56 are evenly distributed on the lower seat ring body, so that the upper seat 5 and the lower seat 8 can be threadedly connected by the clamping screws 84 after assembly to fix the upper seat 5 and the lower seat 8.

[0044] A radial diffuser vacuum brazing process comprises the following steps:

[0045] A. Insert the protruding positioning pins into each positioning pin hole 63, and place the five screw seats 4 into the five screw seat receiving grooves 6 of the lower seat 8 respectively. The threaded portion 41 of the screw seat 4 extends into the cylindrical portion 66, and the flange portion 42 of the screw seat 4 is placed at the open end of the frustum portion 65. Fill the brazing material circumferentially between the outer ring side wall of the screw seat flange portion 42 and the inner wall of the frustum portion 65, and lay the brazing material on the end surface of the flange portion 42. The shallow arc groove of each screw seat flange portion 42 is clamped into the positioning pin, and the screw seat 4 is preliminarily positioned by the positioning pin.

[0046] B. Screw the positioning screw 82 into the central through hole 62 through the through hole portion 67 of each central through hole 62, so that the positioning screw 82 is threadedly connected to the screw seat 4, and the screw seat 4 is accurately positioned by the positioning screw 82 and the positioning pins on both sides.

[0047] C. Sleeve the radial diffuser on the lower seat ring platform of the lower seat 8 so that the lower ring sheet 3 of the radial diffuser is in close contact with the positioning seat 53 of the lower seat 8, and the brazing material on the end surface of the screw seat flange 42 is placed between the lower ring sheet 3 and the screw seat 4.

[0048] D. Place the five screw seats 4 into the five screw seat accommodating grooves 6 of the upper seat 5 respectively, with the threaded portion 41 of the screw seat 4 extending into the cylindrical portion 66, and the flange portion 42 of the screw seat 4 being placed at the open end of the frustum portion 65, and fill the brazing material circumferentially between the outer ring side wall of the screw seat flange portion 42 and the inner wall of the frustum portion 65, and lay the brazing material on the end surface of the flange portion 42, and the shallow arc groove of each screw seat flange portion 42 is clamped into the positioning pin, and the screw seat 4 is preliminarily positioned by the positioning pin; screw the positioning screw 82 from the through hole portion 67 of each center through hole 61 into the center through hole 62, so that the positioning screw 82 is threadedly connected to the screw seat 4, and the screw seat 4 is accurately positioned by the positioning screw 82 and the positioning pins on both sides.

[0049] E. Invert the assembled radial diffuser and lower seat 8 so that the upper seat ring platform 52 of the upper seat 5 is inserted into the lower seat ring platform, and the upper ring plate 1 of the radial diffuser is close to the positioning seat of the upper seat 5, and the brazing material on the end face of the screw seat flange 42 is placed between the upper ring plate 1 and the screw seat 4.

[0050] F. Rotate the upper seat 5 so that the lower seat positioning hole 83 of the lower seat 8 is aligned with the angular positioning hole 54 of the upper seat 5, and insert the angular positioning pin 81 into the lower seat positioning hole 83 and the angular positioning hole 54 to ensure that the screw seat 4 of the upper seat 5 and the screw seat 4 of the lower seat 8 are aligned.

[0051] G. Rotate the radial diffuser and adjust the circumferential position of the radial diffuser so that the screw seat 4 is in the preset assembly position of the radial diffuser, screw in the radial positioning screw 7 so that the radial positioning screw 7 abuts against the guide vane 2 to prevent the radial diffuser from rotating, and screw the clamping screw 84 into the upper seat clamping screw hole 56 and the lower seat clamping screw hole so that the upper seat 5 and the lower seat 8 fix the radial diffuser.

[0052] H. For the radial diffuser that has been clamped, each screw seat 4 is spot-welded and positioned with the corresponding upper ring piece 1 or lower ring piece 3 through the spot welding groove 61, and then the brazing material is welded and fused by a vacuum brazing process, so that the end face of the screw seat 4 and the outer ring side wall of the flange portion 42 are welded and fixed with the corresponding upper ring piece 1 or lower ring piece 3 through the brazing material; at the same time, three furnace test pieces are welded in the same furnace, namely, a first furnace test piece in the shape of a T, a second furnace test piece in the shape of a flat step, and a third furnace test piece after the screw seat is welded to the sheet.

[0053] The welded radial diffuser assembly is subjected to tempering heat treatment, and a first T-shaped test piece, a second flat stepped test piece, and a third test piece are added. The tempering temperature is 580-585°C, and the insulation time is not less than 2 hours. The first test piece is used for dissection and examination of the metallographic structure, the second test piece is used for examination of the shear strength, and the third test piece is used for examination of the hardness and the pull-off force. Example

[0054] The quality inspection method of the radial diffuser vacuum brazing process described in Example 1 comprises the following steps:

[0055] A. Take out the radial diffuser and the first, second and third test pieces that have been heat treated. After cooling, use a hardness tester to check the hardness of the screw seat flange of the third test piece. The measured hardness is between 22HRC and 27.5HRC.

[0056] B. Check the pull-off force between the screw seat and the sheet of the third furnace test piece. The pull-off force between the screw seat and the sheet is not less than 9810N.

[0057] C. Carry out metallographic examination on the first T-shaped test piece to ensure that there are no surface defects such as cracks, bubbles, inclusions, etc.

[0058] D. Carry out shear strength inspection on the second stepped test piece which is laid flat, and the shear strength shall not be less than 196MPa.

[0059] By using the combined inspection method of visual inspection + metallographic inspection of furnace test pieces, hardness, shear strength, and pull-off force testing for the two brazing seam quality inspections of this part, qualified brazing parts can be effectively screened out.

[0060] Obviously, the above embodiments are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, these obvious changes or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims

1. A radial diffuser vacuum brazing process using a radial diffuser screw seat welding fixture, the fixture comprising an upper seat, a lower seat, and a positioning screw matched with the screw seat thread, the upper seat comprising an upper seat ring body and an upper seat ring platform integrally formed, the upper seat ring body is annular, the upper seat ring platform is convexly arranged at the front end of the upper seat ring body, so that an upper seat step is formed between the upper seat ring platform and the upper seat ring body, the lower seat comprises a lower seat ring body and a lower seat ring platform integrally formed, the lower seat ring platform is concavely arranged, so that a lower seat step is formed between the lower seat ring platform and the lower seat ring body, and the upper seat ring platform and the lower seat ring platform can be sleeved and matched; the outer diameter of the lower seat ring platform is smaller than the inner diameter of the radial diffuser, so that when the radial diffuser is sleeved with the upper seat ring platform and the lower seat ring platform, the upper seat ring platform extends into the lower seat ring platform, and the outer wall of the lower seat ring platform and the inner wall of the radial diffuser are gap-matched; It is characterized in that The radial diffuser vacuum brazing process comprises the following steps: A. Insert the protruding positioning pins into each positioning pin hole, place the five screw seats into the five screw seat receiving grooves of the lower seat respectively, the threaded part of the screw seat extends into the cylindrical part, the flange part of the screw seat is placed at the open end of the frustum part, fill the brazing material between the outer ring side wall of the screw seat flange part and the inner wall of the frustum part along the circumferential direction, and lay the brazing material on the end surface of the flange part, and the shallow arc groove of each screw seat flange part is clamped into the positioning pin, and the screw seat is preliminarily positioned by the positioning pin; B. Screw the positioning screws into the central through holes from the through hole parts of each central through hole, so that the positioning screws are threadedly connected with the screw seats, and the screw seats are accurately positioned by the positioning screws and the positioning pins on both sides; C. Sleeve the radial diffuser on the lower seat ring platform of the lower seat, so that the lower ring sheet of the radial diffuser is close to the positioning seat of the lower seat, and the brazing material on the end face of the screw seat flange is placed between the lower ring sheet and the screw seat; D. Place the five screw seats into the five screw seat receiving grooves of the upper seat respectively, with the threaded portion of the screw seat extending into the cylindrical portion, and the flange portion of the screw seat placed at the open end of the frustum portion. Fill the brazing material between the outer ring side wall of the screw seat flange portion and the inner wall of the frustum portion in the circumferential direction, and lay the brazing material on the end surface of the flange portion. The shallow arc groove of each screw seat flange portion is clamped into the positioning pin, and the screw seat is initially positioned by the positioning pin; screw the positioning screw from the through hole portion of each center through hole into the center through hole, so that the positioning screw is threadedly connected with the screw seat, and the screw seat is accurately positioned by the positioning screw and the positioning pins on both sides; E. Invert the assembled radial diffuser and lower seat so that the upper seat ring of the upper seat is inserted into the lower seat ring, and the upper ring of the radial diffuser is in close contact with the positioning seat of the upper seat, and the brazing material on the end face of the screw seat flange is placed between the upper ring and the screw seat; F. Rotate the upper seat so that the lower seat positioning hole of the lower seat is aligned with the angular positioning hole of the upper seat, and insert the angular positioning pin into the lower seat positioning hole and the angular positioning hole to ensure that the screw seat of the upper seat is aligned with the screw seat of the lower seat; G. Rotate the radial diffuser and adjust the circumferential position of the radial diffuser so that the screw seat is in the preset assembly position of the radial diffuser. Screw in the radial positioning screw so that the radial positioning screw abuts against the guide vane to prevent the radial diffuser from rotating. Screw the clamping screw into the clamping screw hole of the upper seat and the clamping screw hole of the lower seat so that the upper seat and the lower seat fix the radial diffuser. H. For the radial diffuser that has been clamped, each screw seat and the corresponding upper ring piece or lower ring piece are spot-welded and positioned through the spot welding grooves, and then the brazing material is welded and fused using the vacuum brazing process, so that the end face of the screw seat and the outer ring side wall of the flange are welded and fixed to the corresponding upper ring piece or lower ring piece through the brazing material; at the same time, three furnace test pieces are welded in the same furnace, namely the first furnace test piece of T-shape, the second furnace test piece of flat stepped shape, and the third furnace test piece after the screw seat is welded to the sheet.

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