Manufacturing method of mixed-flow rotating wheel

Abstract

The invention relates to a manufacturing method of a mixed-flow type runner, which comprises the following steps of: providing an upper crown leaf disc forging blank which comprises an upper crown leaf disc as well as a long blade upper part and a short blade upper part which are integrally formed on the upper crown leaf disc; providing a lower ring blade disc forging blank, wherein the lower ring blade disc forging blank comprises a lower ring blade disc, a long blade lower part and a short blade lower part, and the long blade lower part and the short blade lower part are integrally formed on the lower ring blade disc; the long blade upper portion, the long blade lower portion and the long blade middle portion provided through hot press forming are installed and welded to form the long blade of the mixed-flow type rotating wheel; and the short blade upper part, the short blade lower part and the short blade middle part provided by hot press molding are assembled and welded into the short blade of the mixed-flow rotating wheel. And after welding, relief grinding and overall machining are carried out on welding seams and surfaces of the long blades and the short blades.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of a mixed-flow runner. Background Art

[0002] A high-head mixed-flow runner is a core component of a hydraulic machinery widely used in hydropower stations. It can effectively convert the kinetic energy and potential energy of water flow into mechanical energy, and then drive a generator to generate electric energy. The design and manufacture of such a runner are key links in hydropower generation technology, and its performance directly affects the power generation efficiency and operation stability of hydropower stations.

[0003] Water flow radially enters from the outer periphery of the runner of a high-head mixed-flow runner through the penstock or spiral case of the hydropower station, and flows out axially after passing through the runner. Under the guidance of long blades and short blades, the water flow gradually changes from radial flow to axial flow.

[0004] The runner structure of a mixed-flow water turbine generally includes: a crown disk, a band disk, a number of long blades and a number of short blades. The crown disk is located at the top of the mixed-flow runner and is fixed to the main shaft of the mixed-flow water turbine in an anti-torsion manner on the inner side. The radial outer edge of the crown disk is closer to the top of the mixed-flow runner than the radial inner edge of the crown disk. The band disk is located at the bottom of the mixed-flow runner. The radial inner edge of the band disk is closer to the bottom of the mixed-flow runner than the radial outer edge of the band disk. The long blades are evenly distributed along the circumferential direction of the mixed-flow runner. The upper end of each long blade is integrally formed with the crown disk and the lower end is integrally formed with the band disk, thereby forming a flow passage between every two adjacent long blades. Among them, the radial outer edge of the crown disk, the radial outer edge of the band disk, and the upstream front edges of two adjacent long blades form the top radial inlet of the flow passage, and the radial inner edge of the crown disk, the radial inner edge of the band disk, and the downstream rear edges of two adjacent long blades form the bottom axial outlet of the flow passage. The short blades are evenly distributed along the circumferential direction of the mixed-flow runner. The upper end of each short blade is integrally formed with the crown disk and the lower end is integrally formed with the band disk, thereby dividing the flow passage where the short blade is located into corresponding sub-flow passages starting from the upstream front edge of the short blade, and the downstream rear edge of each short blade terminates inside the flow passage.

[0005] The blade flow passages of such a runner are long and the space is narrow. It is manufactured by the method of casting and welding. The whole manufacturing process is mainly divided into four stages: blank preparation, rough machining, welding, and finish machining. When preparing the blank, based on the flow passage profile, the crown blank casting, the band blank casting, and the blade blank casting are respectively prepared. In the rough machining stage, rough machining of the non-flow surfaces of the crown and the band and finish machining of part of the flow surfaces are carried out, and the blade blank is machined or dressed according to the profile. After the rough machining of the crown, the band, and the blades is completed, they are welded together, and after the weld inspection and heat treatment are completed, dressing and overall finish machining are carried out.

[0006] Since the blanks of the upper crown, lower ring and blades are realized by casting, a series of defects related to casting exist. First, the production of castings requires custom-made templates, resulting in relatively high manufacturing costs and long manufacturing cycles. Second, there are many processes for the liquid metal forming during the casting process and it is difficult to precisely control, making the quality of castings unstable. In addition, the liquid forming structure of castings is loose, the crystal grains are coarse, and defects such as shrinkage cavities, shrinkage porosity, and air holes are easily generated inside. The defects of castings will lead to repair welding or even scrapping, thus increasing the manufacturing cycle and cost.

[0007] When welding the runner blades to the upper crown and lower ring together, the following defects may also exist: First, due to the relatively narrow internal flow passage space, the operations of assembly, welding, grinding, and non-destructive testing are extremely difficult. Second, during welding assembly, the position of the blades cannot be precisely placed, and the position deviation will cause eccentricity of the runner, generating an unbalanced torque. The unbalanced torque of the runner will cause vibrations and bearing overheating to the shafting of the unit during operation. It is necessary to reduce the unbalanced torque through precise balance tests and multiple weightings. Moreover, during the welding process, the high heat generated by the extremely large welding amount will deform the runner, resulting in a large deviation between the relative positions of the blades and the flow passage profile and the theoretical positions and profiles, thus affecting the hydraulic performance of the runner. In addition, the welding positions include the fillet corners where the front and rear edges of the blades are respectively connected to the upper crown and lower ring, which are basically consistent with the high stress areas of the runner. In this way, due to the possible weld defects and residual welding stresses in the welding itself, when superimposed with the working stresses during operation, it will bring risks to the safe and stable operation of the runner.

[0008] Chinese Patent Application for Invention CN116652535A discloses a method for manufacturing split runner blades of a low specific speed Francis turbine. Among them, the lower ring of the runner is manufactured by split rings, including the upper crown disk, inner lower ring disk, outer lower ring disk, and short blades that are respectively independently manufactured and numerically controlled. Half-length blades and short blade root transition steps are arranged on the upper crown disk. Short blade root transition steps are also arranged on the inner lower ring disk and outer lower ring disk respectively. Each part of the long blade is connected by the following connecting welds: the radial split weld of the long blade between the upper crown disk and the inner lower ring disk, the radial split weld of the long blade between the outer lower ring disk and the upper crown disk, the axial split weld of the long blade between the outer lower ring disk and the inner lower ring disk; each part of the short blade is connected by the following welds: the weld between the short blade and the upper crown disk, the weld between the short blade and the inner lower ring disk, the weld between the short blade and the outer lower ring disk, the axial split weld of the short blade between the outer lower ring disk and the inner lower ring disk. The outer lower ring disk and the inner lower ring disk are connected by a circumferential butt weld.

[0009] Chinese Patent Application CN115533460A discloses a Francis runner with a crown and a band at the blade root and a manufacturing method thereof. Among them, the crown and the crown blade root of the runner, and the band and the band blade root are respectively manufactured from the same blank, without material differences and manufacturing defects. Since the height of the crown blade root relative to the crown blade is very low, and the height of the band blade root relative to the band is also very low, it is easy to machine these two blade roots, ensuring the accuracy of the roots. The crown blade and the band blade are respectively formed by a subsequent additive manufacturing welding process on the end faces of the crown blade root and the band blade root. Near-net-shaped upper blades and lower blades are formed by the arc additive manufacturing method, thereby forming an upper lobe composed of the crown, the crown blade root and the upper blade, and a lower lobe composed of the band, the band blade root and the lower blade. Then, the upper lobe and the lower lobe are respectively machined and welded together to form the runner, and the manufacturing of the Francis runner is completed through steps such as overall heat treatment, finish machining and polishing of the runner. Summary of the Invention

[0010] To this end, the present invention provides a manufacturing method of a Francis runner, including the following steps: providing a forged blank of a crown disk, the forged blank of the crown disk including the crown disk of the Francis runner and upper parts of long blades and upper parts of short blades integrally formed on the crown disk at positions corresponding to each of the long blades and short blades and extending towards the band disk; providing a forged blank of a band disk, the forged blank of the band disk including the band disk of the Francis runner and lower parts of long blades and lower parts of short blades integrally formed on the band disk at positions corresponding to each of the long blades and short blades and extending towards the crown disk; dividing each long blade of the Francis runner into two regions, in the first region of the long blade, welding the upper part of the long blade and the lower part of the long blade to each other, and in the second region of the long blade, welding the upper part of the long blade and the lower part of the long blade to a centrally arranged long blade middle part provided by hot pressing respectively, so as to combine the upper part of the long blade, the long blade middle part and the lower part of the long blade into the long blade of the Francis runner; dividing each short blade of the Francis runner into two regions, in the first region of the short blade, welding the upper part of the short blade and the lower part of the short blade to each other, and in the second region of the short blade, welding the upper part of the short blade and the lower part of the short blade to a centrally arranged short blade middle part provided by hot pressing respectively, so as to combine the upper part of the short blade, the short blade middle part and the lower part of the short blade into the short blade of the Francis runner; after welding, grinding the welds and surfaces of each long blade and short blade and performing overall machining.

[0011] In this manufacturing method, the upper crown disk and the lower ring disk are provided in the form of forgings, and the middle parts of the long blades and the middle parts of the short blades are provided by hot pressing. The weld positions avoid the stress concentration areas where the long and short blades are connected to the upper crown disk and the lower ring disk. In particular, the fillet joints between the front and rear edges of the long and short blades and the upper crown disk and the lower ring disk are no longer welded, thus avoiding the adverse effects of welding defects.

[0012] The machining process is carried out in the order of rough machining, semi-finishing machining and finishing machining. Preferably, before welding, rough machining and heat treatment are carried out on the forging blanks of the upper crown disk and the forging blanks of the lower ring disk. The machining scope of rough machining includes the runner shape, the blade profile, the fillets between the front and rear edges of the blade and the upper crown and the lower ring, and the welding groove and the assembly positioning section between the upper and lower parts of the long and short blades; and rough machining is carried out on the middle parts of each of the long blades and the middle parts of each of the short blades. The machining scope of rough machining includes the blade profile, the welding groove and the assembly positioning section between the upper and lower parts of the long and short blades. The purpose of heat treatment is to eliminate the stress imbalance generated during the machining process. When selecting the heat treatment temperature, it should be considered that it is 20-40°C lower than the tempering temperature of the forging.

[0013] Preferably, the rough machining adopts a symmetric position machining method to reduce the large deformation of the blank caused by a large amount of material removal.

[0014] According to a preferred implementation form of the manufacturing method of the mixed-flow runner of the present invention, in the area adjacent to the front edge of the long blade, the upper part of the long blade is directly welded to the lower part of the long blade. In the area adjacent to the rear edge of the long blade, the upper part of the long blade and the lower part of the long blade are respectively welded to the upper edge and the lower edge of the middle part of the long blade arranged in the middle. The division method of the weld should achieve the purpose of reducing the welding amount and comprehensively consider the machining feasibility. For example, the above-mentioned weld division method requires the welding tool to weld two welds from the axial outlet side of the runner, that is, to weld the upper edge and the lower edge of the middle part of the long blade. That is, a Y-shaped weld with an opening facing the axial outlet of the runner of the mixed-flow runner is formed on the corresponding long blade. This is beneficial for operation under the normal condition that the diameter of the axial outlet of the runner is larger than the radial inlet of the runner.

[0015] Of course, the division of the weld can be based on the machining capacity of the equipment and the convenience of approaching the machining position, and any appropriate technical solution can be obtained by considering the diameter of the runner, the profiles of the blades and the runner, and the blank utilization rate.

[0016] For example, in an alternative embodiment, in the region adjacent to the leading edge of the long blade, the upper part and the lower part of the long blade are respectively welded to the upper edge and the lower edge of the middle part of the long blade arranged in the middle. In the region adjacent to the trailing edge of the long blade, the upper part and the lower part of the long blade are directly welded together. Thus, contrary to the above-described embodiment, a Y-shaped weld seam with an opening facing the radial inlet of the flow passage of the mixed-flow runner is formed on the corresponding long blade.

[0017] In another alternative embodiment, in the region adjacent to the leading edge of the long blade and the region adjacent to the trailing edge of the long blade, the upper part and the lower part of the long blade are directly welded together. In the middle section region between the leading edge and the trailing edge of the long blade, the upper part and the lower part of the long blade are respectively welded to the four peripheral edges of the middle part of the long blade arranged in the middle. At this time, the upper part and the lower part of the long blade are directly welded together at both ends of the long blade, while in the middle section region, they are welded to the entire circumference of the middle part of the long blade.

[0018] Obviously, the embodiments of the present invention also include that the long blade blank includes more than one middle part of the long blade, and the upper part, the lower part of the long blade and each middle part of the long blade are welded together to form the final shape of the long blade, as long as the upper part and the lower part of the long blade are directly welded together in a part of the section.

[0019] For example, if two middle parts of the long blade are provided and they are respectively arranged in the region adjacent to the leading edge of the long blade and the region adjacent to the trailing edge of the long blade, it is also feasible. In this embodiment, in the middle section region of the long blade, the upper part and the lower part of the long blade are directly welded together, while in the region adjacent to the leading edge of the long blade and the region adjacent to the trailing edge of the long blade, the upper part and the lower part of the long blade are respectively welded to the upper edge and the lower edge of the corresponding middle part of the long blade arranged in the middle.

[0020] Obviously, the long blade can also be directly welded by the upper part of the long blade extending to the crown disk and the lower part of the long blade extending to the stay ring disk without the middle part of the long blade.

[0021] The above various alternative embodiments of the long blade are also applicable to the short blade.

[0022] In a preferred embodiment of the manufacturing method of the mixed-flow runner according to the present invention, in the region adjacent to the leading edge of the short blade, the upper part of the short blade is directly welded to the lower part of the short blade, and in the region adjacent to the trailing edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the upper edge and the lower edge of the middle part of the short blade arranged in the middle. That is to say, a Y-shaped weld seam with an opening facing the axial outlet of the flow channel of the mixed-flow runner is formed on the corresponding short blade.

[0023] In an alternative embodiment, in the region adjacent to the leading edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the upper edge and the lower edge of the middle part of the short blade arranged in the middle, and in the region adjacent to the trailing edge of the short blade, the upper part of the short blade is directly welded to the lower part of the short blade.

[0024] In another alternative embodiment, in the region adjacent to the leading edge of the short blade and the region adjacent to the trailing edge of the short blade, the upper part of the short blade is directly welded to the lower part of the short blade, and in the middle section region between the leading edge and the trailing edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the four peripheral edges of the middle part of the short blade arranged in the middle.

[0025] Obviously, the embodiments of the present invention also include that the short blade blank includes more than one middle part of the short blade, and the upper part of the short blade, the lower part of the short blade and each middle part of the short blade are welded to each other.

[0026] For example, if two middle parts of the short blade are provided and they are respectively arranged in the region adjacent to the leading edge of the short blade and the region adjacent to the trailing edge of the short blade, it is also feasible. In this embodiment, in the middle section region of the short blade, the upper part of the short blade is directly welded to the lower part of the short blade, and in the region adjacent to the leading edge of the short blade and the region adjacent to the trailing edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the upper edge and the lower edge of the corresponding middle part of the short blade arranged in the middle.

[0027] Obviously, the short blade can also be directly welded by the upper part of the short blade extending to the crown disk and the lower part of the short blade extending to the band disk without the middle part of the short blade.

[0028] At the same time, it should also be noted that the division methods of the long and short blades are relatively independent and can be arbitrarily combined. For example, the weld seam of the long blade can be in the shape of a Y with an opening facing the axial outlet, while the weld seam of the short blade can be in the shape of a Y with an opening facing the radial inlet.

[0029] Different from the design concept of forming upper and lower blades by additive manufacturing such as surfacing on the end faces of the root parts of upper crown blades and lower ring blades in the prior art, in the above preferred embodiments of the present invention, since the upper and lower parts of the long and short blades are integrally formed with the upper crown disk and the lower ring disk by forging respectively, they have better strength and structural characteristics.

[0030] Compared with the technical solution in the prior art of dividing the lower ring disk into an inner ring and an outer ring, in the above preferred embodiments of the present invention, the lower ring disk itself and even part of the long and short blades are integral, and through an appropriate weld division method, better structural strength is obtained and the welding is more convenient. Brief Description of the Drawings

[0031] The embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings:

[0032] Figure 1 A mixed-flow runner under the prior art is schematically shown;

[0033] Figure 2 A longitudinal sectional view of a mixed-flow runner according to the present invention is schematically shown, and the trailing edge of the short blade blocked by the long blade is shown by a dashed line;

[0034] Figure 3 A perspective view of a mixed-flow runner according to the present invention is schematically shown;

[0035] Figure 4A A perspective view of a forging blank of the upper crown disk of a mixed-flow runner according to the present invention is schematically shown;

[0036] Figure 4B A bottom view of a forging blank of the upper crown disk of a mixed-flow runner according to the present invention is schematically shown;

[0037] Figure 5A A perspective view of a forging blank of the lower ring disk of a mixed-flow runner according to the present invention is schematically shown;

[0038] Figure 5B A top view of a forging blank of the lower ring disk of a mixed-flow runner according to the present invention is schematically shown;

[0039] Figure 6 A perspective view of the middle part of a long blade or a short blade of a mixed-flow runner according to the present invention is schematically shown.

[0040] In the drawings, for clarity, the same or functionally similar components are denoted by the same reference numerals. Detailed Description of the Embodiments

[0041] Figure 1Schematically shows a Francis runner under the prior art. The upper end 5" of the long blade 4' is welded to the crown disk 1, and the lower end 5' is welded to the band disk 2. The radial outer edge of the crown disk 1, the radial outer edge of the band disk 2, and the upstream front edges of two adjacent long blades 4' form the top radial inlet of the flow passage. The radial inner edge of the crown disk 1, the radial inner edge of the band disk 2, and the downstream rear edges of two adjacent long blades 4' form the bottom axial outlet of the flow passage. The short blade 3' is arranged between adjacent long blades 4', and extends from the front edge of the short blade 3' to the rear edge terminating inside the flow passage. The short blade 3' divides the flow passage where it is located into corresponding sub-flow passages. The rear edge of the short blade 3' is shown by a dashed line in the figure. The joints between the front edge and the rear edge of the long blade 4' and the crown disk 1 are machined into rounded corners 8 after welding. The joints between the front edge and the rear edge of the short blade 3' and the band disk 2 are machined into rounded corners after welding.

[0042] Figure 2 Schematically shows a longitudinal sectional view of a Francis runner according to the present invention, and the rear edge of the short blade blocked by the long blade is shown by a dashed line. The Francis runner is divided as shown in the figure into a crown disk forging blank, a band disk forging blank, and the middle part 4 of the long blade and the middle part 3 of the short blade. The long blade and the short blade are thus respectively divided into three parts divided along the inlet dividing line 5, the crown dividing line 6, and the band dividing line 7, and they are assembled into one body by welding. The crown disk forging blank includes a crown disk and the upper part of the long blade and the upper part of the short blade integrally formed on the crown disk and extending towards the band disk. The band disk forging blank includes a band disk and the lower part of the long blade and the lower part of the short blade integrally formed on the band disk and extending towards the crown disk. The crown disk forging blank and the band disk forging blank are respectively integrally forged.

[0043] Weld the upper part of the long blade and the lower part of the long blade to each other along the inlet dividing line 5, and weld the upper part of the long blade and the lower part of the long blade to the middle-arranged middle part 4 of the long blade provided by hot pressing respectively along the crown dividing line 6 and the band dividing line 7. Similarly, weld the upper part of the short blade and the lower part of the short blade to each other, and weld the upper part of the short blade and the lower part of the short blade to the middle-arranged middle part 3 of the short blade provided by hot pressing respectively.

[0044] After welding, the weld seams and surfaces of each of the long blades and short blades are machined to obtain the final geometric shapes of the long and short blades.

[0045] Figure 3 Schematically shows a three-dimensional view of a Francis runner according to the present invention, wherein the crown disk forging blank, the band disk forging blank, and the corresponding middle parts of the long blade and the short blade have been welded into one body along the inlet dividing line 5, the crown dividing line 6, and the band dividing line 7.

[0046] Figure 4A and Figure 4B Schematically shows a perspective view and a bottom view of the upper crown vane disc forging blank of a Francis runner according to the present invention. Figure 5A and Figure 5B Schematically shows a perspective view and a top view of the lower ring vane disc forging blank of a Francis runner according to the present invention. According to Figures 4A to 5B It can be intuitively understood the shapes that the upper crown vane disc forging blank and the lower ring vane disc forging blank should reach by forging before being welded to the middle parts of the long blades and the short blades. In the figure, in particular, the upper parts 11 of the long blades and the upper parts 12 of the short blades, as well as the corresponding lower parts 21 of the long blades and the lower parts 22 of the short blades are shown.

[0047] Figure 6 Schematically shows a perspective view of the middle part of a long blade or a short blade of a Francis runner according to the present invention. The middle part 4 of the long blade has welding grooves 41 along the upper crown dividing line 6 and the lower ring dividing line 7, and assembly positioning sections 42 for positioning and connecting with the corresponding upper part 11 of the long blade and the lower part 21 of the long blade before welding. Similarly, the middle part 3 of the short blade has welding grooves 31 along the upper crown dividing line 6 and the lower ring dividing line 7, and assembly positioning sections 32 for positioning and connecting with the corresponding upper part 12 of the short blade and the lower part 22 of the short blade before welding.

[0048] Therefore, an implementation form of the manufacturing method of a Francis runner according to the present invention includes the following steps:

[0049] Provide an upper crown vane disc forging blank 10, which includes the upper crown vane disc of a Francis runner and the upper parts of the long blades and the upper parts of the short blades integrally formed on the upper crown vane disc at the positions corresponding to the respective long blades and short blades and extending towards the lower ring vane disc.

[0050] Provide a lower ring vane disc forging blank 20, which includes the lower ring vane disc of a Francis runner and the lower parts of the long blades and the lower parts of the short blades integrally formed on the lower ring vane disc at the positions corresponding to the respective long blades and short blades and extending towards the upper crown vane disc.

[0051] Provide the hot-pressed middle parts of the long blades and the short blades, which are suitable for being welded to the above-mentioned upper crown vane disc forging blank 10 and lower ring vane disc forging blank 20 to form a Francis impeller in subsequent steps.

[0052] Rough-machine the upper crown vane disc forging blank 10 and the lower ring vane disc forging blank 20 respectively. The machining range of the rough machining includes the runner shape, the blade profile, the fillets between the front and rear edges of the blades and the upper crown and the lower ring, as well as the welding grooves and the assembly positioning sections between the upper and lower parts of the long and short blades.

[0053] The middle part 4 of the long blade and the middle part 3 of the short blade are respectively rough-machined, and the rough-machined machining range includes the blade profile, the welding groove between the upper part and the lower part of the long and short blades, and the assembly positioning section.

[0054] Next, in a part of each long blade, the upper part and the lower part of the long blade are welded to each other along the corresponding welding grooves, and in the remaining area of ​​each long blade, the upper part and the lower part of the long blade are respectively welded to the middle part 4 of the long blade arranged in the middle along the corresponding welding grooves, so that the upper part of the long blade, the middle part of the long blade and the lower part of the long blade are combined into the long blade of the mixed flow runner. In a part of each short blade, the upper part and the lower part of the short blade are welded to each other along the corresponding welding grooves, and in the remaining area of ​​the short blade, the upper part and the lower part of the short blade are respectively welded to the middle part 3 of the short blade arranged in the middle along the corresponding welding grooves, so that the upper part, the middle part and the lower part of the short blade are combined into the short blade of the mixed flow runner. Among them, the positioning between the various components is achieved by the assembly positioning section processed in advance. They are first assembled and spot welded together with the help of the assembly positioning section and other auxiliary tooling thereon, and are formally welded together after the size and profile inspection are qualified. After welding and grinding, heat treatment and corresponding non-destructive testing are carried out. After passing the inspection, the remaining parts in the rough-machined parts (such as the welds and surfaces of the long blades and short blades) are fine-machined to meet the requirements of the drawings and complete the manufacture of the mixed flow impeller.

[0055] Although some embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various combinations, changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0056] Reference numerals list

[0057] 1 Upper crown leaf disc

[0058] 2 Lower blisk

[0059] 3 short blade middle

[0060] 4 long leaves in the middle

[0061] 5 Import Dividing Line

[0062] 5'Leaf bottom

[0063] 5” blade top

[0064] 6 Crown dividing line

[0065] 7 Lower Ring Dividing Line

[0066] 8Rounded corners between blade and crown

[0067] Round corner between the 9 blades and the lower ring

[0068] 10 Forged blank of upper crown blade disc

[0069] 11 Upper part of long blade

[0070] 12 Upper part of short blade

[0071] 20 Forged blank of lower ring blade disc

[0072] 21 Lower part of long blade

[0073] 22 Lower part of short blade

[0074] 31 Welding groove

[0075] 32 Assembly positioning section

[0076] 41 Welding groove

[0077] 42 Assembly positioning section

Claims

1. A method for manufacturing a Francis runner, characterized in that: The manufacturing method of the mixed flow runner comprises the following steps: Providing an upper crown blade disk forging blank, the upper crown blade disk forging blank comprising the upper crown blade disk of the Francis runner and the upper parts of the long blades and the short blades integrally formed on the upper crown blade disk at positions corresponding to the long blades and the short blades and extending toward the lower annular blade disk; Providing a lower annular blade disk forging blank, the lower annular blade disk forging blank comprising the lower annular blade disk of the Francis runner and the lower parts of the long blades and the short blades which are integrally formed on the lower annular blade disk at positions corresponding to the long blades and the short blades and extend toward the upper crown blade disk; Each long blade of the mixed flow runner is divided into two regions, wherein the upper portion of the long blade and the lower portion of the long blade are welded to each other in the first region of the long blade, and the upper portion of the long blade and the lower portion of the long blade are welded to the middle portion of the long blade provided by hot pressing, respectively, in the second region of the long blade, so that the upper portion of the long blade, the middle portion of the long blade and the lower portion of the long blade are combined into the long blade of the mixed flow runner; Each short blade of the Francis runner is divided into two regions, wherein the upper portion of the short blade and the lower portion of the short blade are welded to each other in the first region of the short blade, and the upper portion of the short blade and the lower portion of the short blade are welded to the middle portion of the short blade provided by hot pressing, respectively, in the second region of the short blade, so that the upper portion of the short blade, the middle portion of the short blade and the lower portion of the short blade are combined into the short blade of the Francis runner; After welding, the weld seams and surfaces of the long blades and short blades are ground and machined as a whole.

2. The method for manufacturing a Francis runner according to claim 1, wherein: Before welding, the upper crown blade disk forging blank and the lower ring blade disk forging blank are subjected to rough machining and heat treatment, and the rough machining processing scope includes the flow channel shape, blade profile, the fillet between the front and rear edges of the blade and the upper crown and the lower ring, and the welding groove and assembly positioning section between the upper and lower parts of the long and short blades; and the middle part of each long blade and the middle part of each short blade are subjected to rough machining, and the rough machining processing scope includes the blade profile, the welding groove and assembly positioning section between the upper and lower parts of the long and short blades.

3. The method for manufacturing a Francis runner according to claim 2, wherein: Rough machining adopts symmetrical position machining method.

4. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: In the area adjacent to the front edge of the long blade, the upper part of the long blade is directly welded to the lower part of the long blade, and in the area adjacent to the rear edge of the long blade, the upper part of the long blade and the lower part of the long blade are respectively welded to the upper edge and lower edge of the middle part of the long blade arranged in the middle.

5. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: In the area adjacent to the front edge of the long blade, the upper part of the long blade and the lower part of the long blade are respectively welded to the upper edge and lower edge of the middle part of the long blade arranged in the middle, and in the area adjacent to the rear edge of the long blade, the upper part of the long blade and the lower part of the long blade are directly welded and connected.

6. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: In the area adjacent to the front edge of the long blade and the area adjacent to the rear edge of the long blade, the upper part of the long blade is directly welded to the lower part of the long blade, and in the middle area between the front edge and the rear edge of the long blade, the upper part of the long blade and the lower part of the long blade are respectively welded to the four peripheral edges of the middle part of the long blade arranged in the middle.

7. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: The long blade blank comprises more than one long blade middle portion, and the long blade upper portion, the long blade lower portion and each long blade middle portion are connected to each other by welding.

8. The method for manufacturing a Francis runner according to claim 7, wherein: In the middle area of ​​the long blade, the upper part of the long blade is directly welded to the lower part of the long blade, and in the area adjacent to the front edge of the long blade and the area adjacent to the rear edge of the long blade, the upper part of the long blade and the lower part of the long blade are respectively welded to the upper edge and lower edge of the middle part of the long blade arranged in the middle.

9. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: In the area adjacent to the front edge of the short blade, the upper part of the short blade is directly welded to the lower part of the short blade, and in the area adjacent to the rear edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the upper edge and lower edge of the middle part of the short blade arranged in the middle.

10. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: In the area adjacent to the front edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the upper edge and the lower edge of the middle part of the short blade arranged in the middle, and in the area adjacent to the rear edge of the short blade, the upper part of the short blade and the lower part of the short blade are directly welded and connected.

11. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: In the area adjacent to the front edge of the short blade and the area adjacent to the rear edge of the short blade, the upper part of the short blade is directly welded to the lower part of the short blade, and in the middle area between the front edge and the rear edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the four peripheral edges of the middle part of the short blade arranged in the middle.

12. The method for manufacturing a Francis runner according to any one of claims 1 to 3, wherein: The short blade blank comprises more than one short blade middle portion, and the short blade upper portion, the short blade lower portion and each short blade middle portion are connected to each other by welding.

13. The method for manufacturing a Francis runner according to claim 12, wherein: In the middle area of ​​the short blade, the upper part of the short blade is directly welded to the lower part of the short blade, and in the area adjacent to the front edge of the short blade and the area adjacent to the rear edge of the short blade, the upper part of the short blade and the lower part of the short blade are respectively welded to the upper edge and lower edge of the middle part of the short blade arranged in the middle.

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