A cast-welded structure water pump turbine seat ring and a water pump seat ring manufacturing method

Abstract

The present invention discloses a cast-welded structure water pump turbine seat ring and a method for manufacturing a water pump seat ring. The upper half of the seat ring and the lower half of the seat ring are respectively cast and processed as a whole with the semi-fixed guide vane and its circular root. The seat ring connection weld is set at the center line position of the water guide mechanism to avoid the high stress area. The reverse Z-shaped combination surface is used to avoid the fixed guide vane position. The upper half of the seat ring and the lower half of the seat ring are independently manufactured. The assembly dimensions of the two are controlled and adjusted by an assembly positioning device. At the same time, the weld between the upper half of the seat ring and the lower half of the seat ring and the weld between the seat ring plates are welded. The upper half of the seat ring and the lower half of the seat ring are assembled and welded into one by the above steps and methods. According to the transportation and installation conditions, the seat ring is transported to the construction site in multiple petals and finally welded into a whole. While reducing costs and increasing efficiency, the present invention improves the manufacturing quality of the seat ring product and the safety margin of operation.

Description

Technical Field

[0001] The invention relates to the field of water pump turbines, and in particular to a water pump turbine seat ring formed by welding and assembling independently manufactured seat ring upper half and seat ring lower half, and a method for manufacturing the water pump seat ring. Background Art

[0002] The high stress area of ​​the pump turbine seat ring and the pump seat ring is located at the root circle R part of the seat ring fixed guide vane. The stress amplitude decreases from the root circle R part to the seat ring plate and the two sides of the fixed guide vane. The stress ratio of the center line of the seat ring fixed guide vane water guide structure is △σ / △σmax<0.5. The traditional welded structure of the pump turbine seat ring and the pump seat ring adopts the T-joint welding form of the seat ring plate and the fixed guide vane. Its disadvantages are:

[0003] 1) The connecting weld is located at the circular R part of the root of the fixed guide vane. The high stress part of the seat ring and the weld connection part are highly overlapped. The residual stress of the weld is superimposed on the operating stress and acts on the weak link inside the weld, which brings risks to the safe and stable operation of the components.

[0004] 2) The seat ring plate is made of tear-resistant steel plate, the fan-shaped material has a low nesting rate and low material utilization rate. In addition, the weight of the seat ring welding deposited metal accounts for a high proportion of the component weight, so the overall manufacturing cost is high.

[0005] 3) There are many welds between the seat ring plate and the fixed guide vane, and the root circle R needs to be welded. The welding and grinding cycle is long, and the surface quality and grinding size accuracy of the root circle R weld flow channel area are not easy to guarantee.

[0006] 4) There is a cross between the weld of the seat ring plate and the T-shaped weld between the fixed guide vane and the ring plate, which makes it impossible to perform non-destructive testing on the weld of the ring plate after the overall welding heat treatment of the seat ring.

[0007] 5) There are many welds between the fixed guide vane and the ring plate and they need to be installed high, resulting in a large welding shrinkage rate. In addition, the unevenness of the welded structure ring plate causes a large change in the opening height of the seat ring after welding, making it difficult to ensure the hydraulic dimensions of the seat ring.

[0008] 6) Due to transportation and installation reasons, a radially split half structure is adopted for the seat ring. The fixed guide vanes at the combined surface need to be designed as a split half structure. In addition to welding the ring plate welds, the welds between the split half fixed guide vanes are also required for the on-site assembly of the seat ring, which increases the vertical welding position, increases the amount of on-site welding, and makes it difficult to control the radial and flatness dimensions of the seat ring on-site assembly.

[0009] 7) The welding form and position between the seat ring plate and the fixed guide vane are T-joints at the horizontal welding position and the flat fillet welding position, which are more difficult to weld than the horizontal butt joints at the flat welding position.

[0010] 8) During the assembly process of the seat ring plate and the fixed guide vane, the workload and difficulty of adjusting the assembly dimensions such as the guide vane indexing, placement angle, inlet and outlet water edge radius R1 and R2, chord distance L, assembly clearance, opening height H and high loading volume are relatively large, and there are no effective auxiliary tools and methods for precise assembly positioning.

[0011] 9) The in-factory welding of the seat ring and ring plate is a butt joint root cleaning weld. The welding and root cleaning work of thick plates is large, and the flatness of the ring plate is difficult to control after welding.

[0012] 10) The radial combination surface 5 of the seat ring is a simple centripetal plane. For a single-petal 180-degree two-petal site-welded structure seat ring, the on-site welding shrinkage is reflected in the large deformation of the seat ring radius perpendicular to the combination surface, while the deformation of the seat ring radius parallel to the combination surface is small. The overall ovality of the seat ring is difficult to control after on-site assembly welding.

[0013] In summary, the welding quality and dimensional deformation of the pump-turbine seat ring and the pump seat ring using traditional welding structure and manufacturing method are difficult to control, the welding and grinding workload is large and the cycle is long, the comprehensive manufacturing cost is high and the efficiency is low, and the safety margin of component manufacturing and operation is low. Therefore, it is necessary to develop a new pump-turbine seat ring and a pump seat ring manufacturing method. Summary of the invention

[0014] In view of this, the present invention adopts a new type of water pump turbine seat ring and a water pump seat ring manufacturing method, which can replace the water pump turbine seat ring and water pump seat ring of the traditional welding structure and manufacturing method, while reducing costs and increasing efficiency, and improving the manufacturing quality of the seat ring product and the safety margin of operation; the present invention is achieved through the following steps:

[0015] Step 1: Divide the seat ring into two parts, an upper seat ring half and a lower seat ring half, based on the center line of the water guide mechanism, and independently manufacture the upper seat ring half and the lower seat ring half. When independently manufacturing the upper seat ring half and the lower seat ring half, integrally arrange semi-fixed guide vanes on the upper ring plate of the upper seat ring half and the lower ring plate of the lower seat ring half;

[0016] Step 2: All surfaces of the upper half of the seat ring or the lower half of the seat ring are processed by single-piece CNC machining with allowance. For the seat ring with radial half-divided structure, an inverted Z-shaped combined surface is set, and welding grooves are set on the semi-fixed guide vane end face of the upper half of the seat ring and the semi-fixed guide vane end face of the lower half of the seat ring; welding grooves are set on the upper ring plate end face of the upper half of the seat ring and the lower ring plate end face of the lower half of the seat ring;

[0017] Step 3: The upper half of the seat ring and the lower half of the seat ring are assembled into one by accurately adjusting and controlling the assembly structure dimensions of the seat ring through the convex and concave assembly positioning device;

[0018] Step 4: After the upper and lower parts of the seat ring are assembled, the seat ring connecting welds between the semi-fixed guide vane end faces of the upper and lower parts of the seat ring and the splicing welds between the upper ring plates of the upper and lower parts of the seat ring or the lower ring plates of the lower part of the seat ring are welded simultaneously. Finally, the upper and lower parts of the seat ring are welded into one piece. Based on the transportation and installation restrictions, the seat ring is transported to the construction site in multiple petals and finally welded into a whole.

[0019] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, in the step one, the upper ring plate of the upper half of the seat ring or the lower ring plate of the lower half of the seat ring are respectively cast into one piece with the semi-fixed guide vane and its round root.

[0020] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, the inverted Z-shaped combination surface in step two is a seat ring combination surface approximately distributed in the middle position of two adjacent fixed guide vanes, and the water inlet edge and water outlet edge combination surfaces at both ends of the inverted Z-shape except the middle position are centripetal structures, and the inverted Z-shaped combination surface has no intersection with the position of the fixed guide vanes.

[0021] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, in the step 2, the welding groove between the semi-fixed guide vane end face of the upper half of the seat ring and the semi-fixed guide vane end face of the lower half of the seat ring is a double-sided U-shaped full penetration weld, and the welding groove between the upper ring plate end face of the upper half of the seat ring and the lower ring plate end face of the lower half of the seat ring is a large blunt edge non-full penetration weld.

[0022] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, the convex-concave assembly positioning device in step three is arranged between the lower plane of the upper ring plate of the upper half of the seat ring and the upper plane of the lower ring plate of the lower half of the seat ring, the assembly clearance D0 in the height direction of the convex block and the concave block of the convex-concave assembly positioning device is 5mm, the unilateral radial clearance D between the convex block and the concave block is 0.5mm, and the height H1 of the positioning device is 4mm more than the theoretical opening height H of the seat ring.

[0023] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, in the step three, the concave block of the convex-concave assembly positioning device is independently fine-machined on the lower plane of the upper ring plate of the upper half of the seat ring and the upper plane of the lower ring plate of the lower half of the seat ring, and then welded to the above-mentioned two fine-machined planes, the inner hole and the end face of the concave block are CNC-machined as a whole with the same reference as the upper half of the seat ring or the lower half of the seat ring, and the convex block is processed as a single piece.

[0024] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, in the step three, the convex-concave assembly positioning device is composed of two concave blocks and one convex block, and the method of using the convex-concave assembly positioning device is to first insert one end of the convex block into the inner hole of the concave block of the lower half of the seat ring and the concave block combination, and then align the concave block of the upper half of the seat ring and the concave block combination with the corresponding convex block center and insert it.

[0025] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, the seat ring assembly height dimension in step three is that the semi-fixed guide vane height H0 of the upper half or lower half of the seat ring is 1 mm more than half of the theoretical opening height H of the seat ring.

[0026] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, after the upper half of the seat ring and the lower half of the seat ring in step four are assembled, the height gap D1 between the semi-fixed guide vane end face of the upper half of the seat ring and the semi-fixed guide vane end face of the lower half of the seat ring is 1.5mm~2mm.

[0027] In the above-mentioned cast-welded structure water pump turbine seat ring and water pump seat ring manufacturing method, in the step 4, a radially split-half structure seat ring is used due to transportation and installation reasons, and no split-half fixed guide vanes welded on site are provided.

[0028] The beneficial effects of the present invention compared with the prior art are:

[0029] 1. The present invention enables the seat ring connection weld to avoid the high stress area of ​​the seat ring operation, thereby improving the manufacturing quality of the seat ring product and the safety margin of operation.

[0030] 2. The present invention not only reduces the difficulty of welding and grinding, but also greatly shortens the cycle and cost of welding and grinding.

[0031] 3. The surface quality and profile size accuracy of the circular R weld flow channel area at the root of the fixed guide vane of the present invention are higher, which is beneficial to enhancing the cavitation resistance of the circular root area under high water flow rate.

[0032] 4. The present invention greatly simplifies the seat ring assembly process and improves the seat ring assembly dimensional accuracy by using a special convex-concave assembly positioning device.

[0033] 5. The present invention independently casts and processes the upper and lower halves of the seat ring, thereby eliminating the processes of cutting and welding the seat ring plate and the fixed guide vane steel plate, thereby improving material utilization.

[0034] 6. The present invention avoids the need for semi-fixed guide vanes to be welded on site of the seat ring, and is more conducive to the control of ovality size after the seat ring is assembled and welded on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The utility model relates to a water pump turbine seat ring and a water pump seat ring of a traditional welding structure.

[0036] Figure 2 This is the ordering drawing for the upper half of the cast-welded seat ring.

[0037] Figure 3 This is the ordering drawing for the lower half of the cast-welded seat ring.

[0038] Figure 4It is a schematic diagram of the convex-concave assembly positioning device.

[0039] Figure 5 This is a schematic diagram of the lower assembly of the two-petal seat ring.

[0040] Figure 6 It is a schematic diagram of the assembly of the upper and lower parts of the seat ring.

[0041] Figure 7 This is a schematic diagram of the welding of the cast-welded structure water pump turbine seat ring and the 1 / 2 petal of the water pump seat ring.

[0042] Component description in the figure: 1-upper ring plate; 2-lower ring plate; 3-fixed guide vane; 4-half-fixed guide vane; 5-radial combination surface; 6-lower ring plate of the lower half of the seat ring; 7-semi-fixed guide vane; 8-round root; 9-welding groove between semi-fixed guide vanes; 10-convex block; 11-welding corner; 12-welding groove between ring plates; 13-large blunt edge non-full penetration weld; 14-lower half of the seat ring; 15-concave block; 16-reverse Z-shaped combination surface; 17-joining weld between ring plates; 18-adjacent lower halves of seat rings; 19-upper half of seat ring; 20-adjacent upper half of seat rings; 21-convex and concave assembly positioning device; 22-seat ring connection weld; 23-upper ring plate of the upper half of the seat ring. DETAILED DESCRIPTION

[0043] The present application is further described below in conjunction with the accompanying drawings.

[0044] Specific implementation method 1: Figure 1 As shown, the seat ring is a pump turbine seat ring and a pump seat ring having an upper ring plate 1, a lower ring plate 2, and a plurality of fixed guide vanes 3 arranged between the upper ring plate 1 and the lower ring plate 2. A cast-welded structure pump turbine seat ring and a method for manufacturing a pump seat ring provided in this embodiment are achieved by the following steps:

[0045] Step 1: If Figure 2 and Figure 3 As shown, the seat ring is divided into two parts, the seat ring upper half 19 and the seat ring lower half 14, with the center line of the water guide mechanism as the boundary, and the seat ring upper half 19 and the seat ring lower half 14 are manufactured independently. When the above-mentioned seat ring upper half 19 and the above-mentioned seat ring lower half 14 are independently manufactured, the semi-fixed guide vane 7 is integrally provided on the upper ring plate 23 of the above-mentioned seat ring upper half 19 and the lower ring plate 6 of the above-mentioned seat ring lower half 14; in this step, the seat ring is divided into two parts, the seat ring upper half 19 and the seat ring lower half 14, with the center line of the water guide structure as the boundary, and the purpose of independently manufacturing the seat ring is to make the seat ring connecting weld 22 avoid the high stress area of ​​operation, and the stress amplitude at the position of the connecting weld 22 is lower than 1 / 2 of the highest stress value at the position of the circular root 8 of the fixed guide vane 3, thereby improving the safety margin.

[0046] Step 2: If Figure 2 , Figure 3 and Figure 5As shown, all surfaces of the upper half 19 of the seat ring or the lower half 14 of the seat ring are processed by single-piece CNC with a margin. For the seat ring with a radial half-divided structure, an inverted Z-shaped combined surface 16 is provided, and a welding groove 9 is provided on the end face of the semi-fixed guide vane 7 of the upper half 19 of the seat ring and the end face of the semi-fixed guide vane 7 of the lower half 14 of the seat ring; a welding groove 12 is provided on the end face of the upper ring plate 23 of the upper half 19 of the seat ring and the end face of the lower ring plate 6 of the lower half 14 of the seat ring; in this step, the role of providing the welding groove 9 on the end face of the semi-fixed guide vane 7 of the upper half 19 of the seat ring and the end face of the semi-fixed guide vane 7 of the lower half 14 of the seat ring is to change the welding position from the horizontal welding position and the flat fillet welding position The T-joint is converted into a butt joint in a flat welding position, which reduces the welding difficulty, structural constraint and steel plate laminar tearing sensitivity, making it easier to ensure welding quality; the number of connecting welds between the fixed guide vane 3 and the upper ring plate 1 and the lower ring plate 2 is reduced from 2 to 1, and there is no round root 8. Its welding and grinding cycle is only 1 / 4 of that of the traditional seat ring structure and manufacturing method, and its welding and grinding cost is only 1 / 3 of that of the traditional seat ring structure and manufacturing method. At the same time, the surface quality and grinding size accuracy of the flow channel area of ​​the round root 8 of the fixed guide vane 3 are higher, which is beneficial to enhancing the cavitation resistance of the round root area under higher water flow rates.

[0047] Step 3: If Figure 5 , Figure 6 and Figure 7 As shown, the seat ring upper half 19 and the seat ring lower half 14 are assembled into one by accurately adjusting and controlling the various assembly structure dimensions of the seat ring through the convex-concave assembly positioning device 21; the role of using the special convex-concave assembly positioning device 21 to assemble the seat ring upper half 19 and the seat ring lower half 14 in this step is to greatly simplify the assembly and size adjustment process between the seat ring upper ring plate 1, the lower ring plate 2 and the fixed guide vane 3, reduce the difficulty, shorten the cycle and improve the accuracy.

[0048] Step 4: If Figure 7 As shown, after the seat ring upper half 19 and the seat ring lower half 14 are assembled, the seat ring connecting weld 22 between the end face of the semi-fixed guide vane 7 of the seat ring upper half 19 and the end face of the semi-fixed guide vane 7 of the seat ring lower half 14 and the splicing weld 17 between the upper ring plate 23 of the seat ring upper half 19 or the lower ring plate 6 of the seat ring lower half 14 are welded at the same time, and finally the seat ring upper half 19 and the seat ring lower half 14 are welded into one body, and according to the transportation and installation restrictions, the seat ring is transported to the construction site in multiple petals and finally welded into a whole. The welding sequence adopted in this step can better ensure the flatness of the seat ring plate after welding and the chord distance L between the adjacent fixed guide vanes 3 on both sides of the splicing weld 17 between the ring plates.

[0049] Specific implementation method 2: Figure 2 , Figure 3As shown, this embodiment further limits step one described in specific embodiment one. In this embodiment, the upper ring plate 23 of the seat ring upper half 19 or the lower ring plate 6 of the seat ring lower half 14 in step one are respectively cast into one piece with the semi-fixed guide vane 7 and its round root 8; the purpose of independently casting and processing the seat ring upper half 19 and the seat ring lower half 14 in this step is to eliminate the processes of cutting and welding the seat ring plate steel plate, thereby improving material utilization.

[0050] Specific implementation method three: Figure 5 , Figure 6 As shown, this embodiment further limits step 2 described in specific embodiment 1. In this embodiment, the inverted Z-shaped combination surface 16 in step 2 is a seat ring combination surface approximately distributed in the middle position of two adjacent fixed guide vanes 3. The water inlet and outlet combination surfaces at both ends of the inverted Z-shape except the middle position are centripetal structures, and the inverted Z-shaped combination surface 16 has no intersection with the position of the fixed guide vane 3; the role of arranging the inverted Z-shaped combination surface 16 in the middle position of adjacent fixed guide vanes 3 in this step is to avoid the on-site welding of the half-fixed guide vanes 4 across the seam; for the single-petal 180-degree two-petal on-site welded structure seat ring, the radial combination surface 5 of the seat ring is optimized from a simple centripetal plane to an inverted Z-shaped combination surface 16 approximately distributed in the middle position of two adjacent fixed guide vanes 3, which reduces and averages the welding shrinkage of the radius dimensions perpendicular to the combination surface and parallel to the combination surface after the seat ring is on-site welded, and the overall ovality of the seat ring is better after on-site welding.

[0051] Specific implementation method four: Figure 2 , Figure 3 As shown, this embodiment further limits step two described in specific embodiment one. In this embodiment, the welding groove 9 between the end face of the semi-fixed guide vane 7 of the upper half 19 of the seat ring and the end face of the semi-fixed guide vane 7 of the lower half 14 of the seat ring in step two is a double-sided U-shaped full penetration weld, and the welding groove 12 between the end face of the upper ring plate 23 of the upper half 19 of the seat ring and the end face of the lower ring plate 6 of the lower half 14 of the seat ring is a large blunt edge non-full penetration weld; the role of using large blunt edge non-full penetration welding for the splicing weld 17 between the ring plates in this step is to reduce the welding amount and eliminate the need for root cleaning, which is more conducive to shortening the welding cycle and controlling welding deformation.

[0052] Specific implementation method five, as Figure 4 , Figure 5 and Figure 6As shown, this embodiment further limits step three described in specific embodiment one. In this embodiment, the convex-concave assembly positioning device 21 in step three is arranged between the lower plane of the upper ring plate 23 of the upper half 19 of the seat ring and the upper plane of the lower ring plate 6 of the lower half 14 of the seat ring. The assembly clearance D0 in the height direction of the convex block 15 and the concave block 10 of the convex-concave assembly positioning device 21 is 5 mm, the unilateral radial clearance D between the convex block 15 and the concave block 10 is 0.5 mm, and the height H1 of the positioning device is 4 mm more than the theoretical opening height H of the seat ring.

[0053] Specific implementation method six, as Figure 4 , Figure 5 and Figure 6 As shown, this embodiment further limits step three described in specific embodiment one. In this embodiment, the concave block 10 of the convex-concave assembly positioning device 21 in step three is independently finished on the lower plane of the upper ring plate 23 of the seat ring upper half 19 and the upper plane of the lower ring plate 6 of the seat ring lower half 14, and then welded to the above two finished planes, the inner hole and the end face of the concave block 10 are integrally CNC-machined with the seat ring upper half 19 or the seat ring lower half 14 according to the same reference, and the convex block 15 is processed as a single piece.

[0054] Specific implementation method seven, as Figure 4 , Figure 5 and Figure 6 As shown, this embodiment further limits step three described in specific embodiment one. In this embodiment, the convex-concave assembly positioning device 21 in step three is composed of two concave blocks 10 and one convex block 15. The method of using the convex-concave assembly positioning device 21 is to first insert one end of the convex block 15 into the inner hole of the concave block 10 of the combination of the lower half 14 of the seat ring and the concave block 10, and then align the concave block 10 of the combination of the upper half 19 of the seat ring and the concave block 10 with the center of the corresponding convex block 15 and insert it.

[0055] Specific implementation method eight, as Figure 7 As shown, this embodiment further limits step three described in specific embodiment one. In this embodiment, the seat ring assembly height dimension in step three is that the semi-fixed guide vane height H0 of the seat ring upper half 19 or the seat ring lower half 14 is 1 mm more than half of the seat ring theoretical opening height H; in this step, by adopting the technical measure of increasing the height direction of the semi-fixed guide vane 7, the welding shrinkage in the height direction of the seat ring is reduced and homogenized, and the hydraulic dimensions such as the opening height H of the seat ring after welding are better.

[0056] Specific implementation method nine, as Figure 7As shown, this embodiment further limits step four described in specific embodiment one. In this embodiment, after the seat ring upper half 19 and the seat ring lower half 14 in step four are assembled, the height gap D1 between the end face of the semi-fixed guide vane 7 of the seat ring upper half 19 and the end face of the semi-fixed guide vane 7 of the seat ring lower half 14 is 1.5mm~2mm; in this step, by adopting the technical measure of reducing the assembly gap D1 between the seat ring upper half 19 and the seat ring lower half 14, the welding shrinkage in the height direction of the seat ring is reduced and homogenized, and the hydraulic dimensions such as the opening height H of the seat ring after welding are better.

[0057] Specific implementation method ten, this implementation method further limits step four described in specific implementation method one. In this implementation method, in step four, a radially split-half structure seat ring is used due to transportation and installation reasons, and a split-half fixed guide vane 4 assembled on site is not provided; the purpose of not providing the split-half fixed guide vane 4 in this step is to avoid welding the split-half fixed guide vane 4 on site, reduce the amount of on-site welding, and facilitate control of the radial and flatness dimensions of the seat ring assembled on site.

Claims

1. A cast-welded structure water pump turbine seat ring and a method for manufacturing a water pump seat ring, characterized in that: The method is implemented by the following steps: Step 1: Divide the seat ring into two parts, an upper seat ring half (19) and a lower seat ring half (14), with the center line of the water guide mechanism as the boundary, and independently manufacture the upper seat ring half (19) and the lower seat ring half (14). When independently manufacturing the upper seat ring half (19) and the lower seat ring half (14), a semi-fixed guide vane (7) is integrally provided on the upper ring plate (23) of the upper seat ring half (19) and the lower ring plate (6) of the lower seat ring half (14); Step 2: single-piece CNC machining is performed on all surfaces of the upper half (19) or the lower half (14) of the seat ring with a margin. For a seat ring with a radially divided half structure, an inverted Z-shaped combination surface (16) is provided, and a welding groove (9) is provided on the end surface of the semi-fixed guide vane (7) of the upper half (19) of the seat ring and the end surface of the semi-fixed guide vane (7) of the lower half (14) of the seat ring; a welding groove (12) is provided on the end surface of the upper ring plate (23) of the upper half (19) of the seat ring and the end surface of the lower ring plate (6) of the lower half (14) of the seat ring; Step 3: The upper half of the seat ring (19) and the lower half of the seat ring (14) are assembled into one piece by accurately adjusting and controlling the assembly structure dimensions of the seat rings through the convex and concave assembly positioning device (21); Step 4: After the seat ring upper half (19) and the seat ring lower half (14) are assembled, the seat ring connecting weld (22) between the end face of the semi-fixed guide vane (7) of the seat ring upper half (19) and the end face of the semi-fixed guide vane (7) of the seat ring lower half (14) and the splicing weld (17) between the upper ring plate (23) of the seat ring upper half (19) or the lower ring plate (6) of the seat ring lower half (14) are welded simultaneously, and finally the seat ring upper half (19) and the seat ring lower half (14) are welded into one piece, and according to the transportation and installation restrictions, the seat ring is transported to the construction site in multiple pieces and finally welded into a whole piece.

2. A cast-welded structure water pump turbine seat ring and a method for manufacturing a water pump seat ring according to claim 1, characterized in that: In the step 1, the upper ring plate (23) of the upper half (19) of the seat ring or the lower ring plate (6) of the lower half (14) of the seat ring are respectively cast into one piece with the semi-fixed guide vane (7) and its circular root (8).

3. A cast-welded structure water pump turbine seat ring and a method for manufacturing a water pump seat ring according to claim 1, characterized in that: In the step 2, the inverted Z-shaped combined surface (16) is a seat ring combined surface approximately distributed in the middle position of two adjacent fixed guide vanes (3), and the water inlet edge and water outlet edge combined surfaces at both ends of the inverted Z-shape except the middle position are centripetal structures, and the inverted Z-shaped combined surface (16) does not intersect with the position of the fixed guide vane (3).

4. A cast-welded structure water pump turbine seat ring and a method for manufacturing a water pump seat ring according to claim 1, characterized in that: In the step 2, the welding groove (9) between the end face of the semi-fixed guide vane (7) of the upper half (19) of the seat ring and the end face of the semi-fixed guide vane (7) of the lower half (14) of the seat ring is a double-sided U-shaped full penetration weld, and the welding groove (12) between the end face of the upper ring plate (23) of the upper half (19) of the seat ring and the end face of the lower ring plate (6) of the lower half (14) of the seat ring is a large blunt edge non-full penetration weld.

5. The cast-welded structure water pump turbine seat ring and the method for manufacturing the water pump seat ring according to claim 1, characterized in that: In the step three, the convex-concave assembly positioning device (21) is arranged between the lower plane of the upper ring plate (23) of the upper half (19) of the seat ring and the upper plane of the lower ring plate (6) of the lower half (14) of the seat ring, the assembly clearance D0 in the height direction between the convex block (15) and the concave block (10) of the convex-concave assembly positioning device (21) is 5 mm, the unilateral radial clearance D between the convex block (15) and the concave block (10) is 0.5 mm, and the height H1 of the positioning device is 4 mm greater than the theoretical opening height H of the seat ring.

6. The cast-welded structure water pump turbine seat ring and the method for manufacturing the water pump seat ring according to claim 1, characterized in that: In the step three, the concave block (10) of the convex-concave assembly positioning device (21) is independently fine-machined on the lower plane of the upper ring plate (23) of the upper half of the seat ring (19) and the upper plane of the lower ring plate (6) of the lower half of the seat ring (14), and then welded to the above-mentioned two fine-machined planes, the inner hole and the end face of the concave block (10) are integrally CNC-machined with the upper half of the seat ring (19) or the lower half of the seat ring (14) using the same reference, and the convex block (15) is processed as a single piece.

7. The cast-welded structure water pump turbine seat ring and the method for manufacturing the water pump seat ring according to claim 1, characterized in that: In the step three, the convex-concave assembly positioning device (21) is composed of two concave blocks (10) and a convex block (15). The method of using the convex-concave assembly positioning device (21) is as follows: first, one end of the convex block (15) is inserted into the inner hole of the concave block (10) of the assembly of the lower half of the seat ring (14) and the concave block (10), and then the concave block (10) of the assembly of the upper half of the seat ring (19) and the concave block (10) is aligned with the center of the corresponding convex block (15) and inserted.

8. The cast-welded structure water pump turbine seat ring and the method for manufacturing the water pump seat ring according to claim 1, characterized in that: In the step three, the seat ring assembly height dimension is that the semi-fixed guide vane height H0 of the upper half (19) or the lower half (14) of the seat ring is 1 mm more than half of the theoretical opening height H of the seat ring.

9. The cast-welded structure water pump turbine seat ring and the method for manufacturing the water pump seat ring according to claim 1, characterized in that: In the step 4, after the seat ring upper half (19) and the seat ring lower half (14) are assembled, the height gap D1 between the end surface of the semi-fixed guide vane (7) of the seat ring upper half (19) and the end surface of the semi-fixed guide vane (7) of the seat ring lower half (14) is 1.5 mm to 2 mm.

10. The cast-welded structure water pump turbine seat ring and the method for manufacturing the water pump seat ring according to claim 1, characterized in that: In the step 4, due to transportation and installation reasons, a radially split-half structure seat ring is used, and no split-half fixed guide vane (4) assembled and welded on site is provided.

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