A machining process for a runner chamber of a water turbine with a segmented multi-petal connectionless flange structure

Abstract

The present application relates to the technical field of water turbine runner chamber, and discloses a machining process of a segmented multi-petal runner chamber without connecting flange structure, which comprises the following steps: providing a multi-petal straight cylinder section flow channel and a multi-petal circular arc section flow channel; combining each into an integrated whole; marking a line; aligning the line, rough milling and fine milling each joint surface; welding a connecting plate at the joint of the outer cylinder, aligning the outer shape and combining into an integrated whole; marking a line again; rough turning, semi-fine turning and fine turning; milling: assembling the multi-petal straight cylinder section flow channel, the multi-petal circular arc section flow channel, the vertical rib, the ring rib and the flange into an integrated whole; and hoisting and replacing the old runner chamber by combining and welding the multi-petal straight cylinder section flow channel and the multi-petal circular arc section flow channel together. The present application has the advantages of high installation efficiency, good overall strength and small deformation.

Description

Technical Field

[0001] This invention relates to the field of turbine runner technology, specifically to a machining process for a segmented, multi-lobed turbine runner without connecting flanges. Background Technology

[0002] The runner chamber, a crucial component of a hydroelectric turbine, primarily functions to uniformly and symmetrically introduce water flow into the guide vanes, creating circulation before the guide blades while minimizing hydraulic losses. Working in conjunction with the seat ring, the runner chamber bears the axial load of the hydroelectric generator unit and transfers the load to the concrete foundation. It is typically located within the intake system, forming a flow channel with the seat ring. Its design aims to ensure water enters the runner with minimal output loss, thereby achieving efficient water energy conversion. However, in long-term operation, the runner chamber may experience problems such as leakage, cavitation, wear, or weld cracking. These issues can affect the safe and stable operation of the turbine. Conventional repair methods involve on-site welding and grinding, which are difficult, require limited operating space, have poor stress relief, and fail to meet drawing requirements for flow channel dimensions. In severe cases, this can lead to uneven water flow, impacting the safe and stable operation of subsequent units.

[0003] Chinese patent document CN114770322B discloses a method for replacing the runner chamber of a vertical turbine unit in sections. The background art describes that, generally, the runner chamber of a vertical turbine unit is cast in a concrete pit and is made of carbon steel. During operation, the runner chamber is prone to cavitation, leading to excessive clearance between the runner chamber and the internal runner blades, and a decrease in the efficiency of the vertical turbine unit. Minor runner chamber cavitation can be filled with composite materials, but severe cavitation necessitates the replacement of the entire runner chamber. This method for replacing the runner chamber in sections ensures efficient replacement and inspection of the inner wall of the runner chamber, allowing for precise control of the runner chamber parameters. The method includes the following steps: fabrication of a new runner chamber, cutting the new runner chamber into sections, installing the sections, and grouting.

[0004] During the renovation and installation of the turbine runner chamber, the runner chamber is filled with concrete. Therefore, when replacing the runner chamber, it is necessary to remove the concrete of the old runner chamber and then pour grout again after replacing it with the new runner chamber. This process takes a long time. In the traditional integral or flange-connected runner chamber replacement scheme, if the old concrete is not removed, the new runner chamber cannot be directly installed due to structural or dimensional issues. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a machining process for a segmented, multi-lobed, flangeless turbine runner chamber, comprising the following steps: Step 1: Prepare multi-lobed straight cylindrical section flow channels and multi-lobed arc section flow channels; Step 2: Align the multi-lobed straight cylindrical section flow channel and the multi-lobed arc section flow channel with their respective shapes, find the alignment lines and horizontal alignment lines, and combine them into one unit. Step 3: Draw horizontal correction lines at both ends, correction lines for the joint surface, center cross line, and processing lines for both ends, as well as correction circles, inner circle processing lines, outer circle processing lines, and joint surface processing lines respectively. Step 4: Align with the line and perform rough and fine milling on each joint surface; Step 5: Weld the process connecting plate at the joint of the outer circumference of the two flow channels, align the outer shape and assemble them into one piece; Step 6: Redraw the horizontal correction lines at both ends, the correction lines for the joint surface, the center cross line, the processing lines for both ends, the correction circle line, the inner circle processing line, the outer circle processing line, and the joint surface processing line; Step 7: Remove burrs, sharp edges, and grind the joint surface to meet the roughness requirements of the drawing. Then, assemble the blanks and align the inner and outer shapes. Step 8: Rough turning, semi-finish turning, finish turning; Step 9: Draw a central crosshair and mark ±X and Y. The marks are located on the outer circumference of the cylinders of the two flow channels. Draw machining lines for each hole. Step 10: Use a dial indicator to align the flange plane and the outer circle of the stop, and drill the threaded holes to the dimensions shown in the drawing. Step 11: Machine tap each thread to the dimensions shown in the drawing; Step 12, Milling: Step 12.1: Before processing each group of welded parts, reinforce the impeller chamber with anti-deformation supports; Step 12.2: Mill off the welds at the process connection plates on the outer circle of the cylinder; Step 12.3: Grind the unprocessed areas of the weld and disassemble it into segments; Step 12.4: Use a dial indicator to align the joint surface and mill the weld bevel at the joint surface to the dimensions shown in the drawing; Step 13: Assemble the multi-lobed straight cylindrical section flow channel, multi-lobed arc section flow channel, vertical ribs, ring ribs and flanges into one piece; Step 14: Weld the multi-lobed straight cylindrical section flow channel and the multi-lobed arc section flow channel together and hoist them to replace the old impeller chamber.

[0006] Preferably, the multi-lobed arc segment flow channel is a concave arc flow channel, and the vertical ribs, ring ribs and flange ends are located on the same plane.

[0007] Preferably, in step 8, rough turning involves clamping the outer circle, aligning the circle line and end face line, CNC programming, and rough turning one end face and inner curved surface; adjusting the surface involves clamping the outer circle, aligning the machined inner circle and end face, and rough turning the other end face, inner conical surface, and stepped plane.

[0008] Preferably, in step 8, the semi-finish turning and finish turning are performed as follows: clamping the outer circle, aligning the machined inner circle and plane, semi-finish turning and finish turning one end face, each outer circle, inner curved surface, weld corner at the chamfered inner circle, inner circle, stop, step plane, groove, and chamfer; adjusting the surface, aligning with the leveling pile, clamping the outer circle, aligning the machined inner circle, semi-finish turning and finish turning the other end face, inner conical surface, weld corner at the chamfered inner circle, step plane, and chamfer.

[0009] To improve installation accuracy and eliminate deformation, the number of lobes in the multi-lobed straight cylindrical section flow channel is greater than the number of lobes in the multi-lobed arc section flow channel.

[0010] Preferably, the straight cylindrical section of the flow channel has 4 lobes, and the arc section of the flow channel has 3 lobes.

[0011] Preferably, in step 13, the inner fitting structure of the multi-lobed straight cylindrical section flow channel and the multi-lobed arc section flow channel is assembled into one piece.

[0012] To improve accuracy, in step 6, the already machined joint surfaces are rough and finish milled, and the joint surface machining lines are redrawn.

[0013] The present invention has the following beneficial effects: 1. This invention modifies and replaces the old and new turbine chambers. Without demolishing the original civil engineering, the turbine chambers are separated and assembled in sections using different straight cylindrical sections and arc-shaped sections. This ensures that the new turbine chamber can be directly hoisted without changing the original concrete structure, resulting in high installation efficiency. It solves the problem that the new components cannot be installed in the limited concrete space due to the connecting flanges and external structural protrusions of the original turbine chamber. At the same time, this application adopts an internal clamping structure for connection and assembly, and the connection and cooperation with the process connecting plate further reduces the overall volume of the turbine chamber, which is convenient for hoisting and ensures overall strength.

[0014] 2. The overall structural deformation of the present invention is small. Due to the use of different flow channels, the deformation resistance of the straight cylindrical section flow channel is different from that of the arc section flow channel. The straight cylindrical section flow channel has strong deformation resistance, while the arc section flow channel has weak deformation resistance. After being welded and assembled separately, it is then welded and assembled as a whole, resulting in small overall deformation while ensuring strength. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating an embodiment of the machining process for the turbine runner chamber of the segmented, multi-lobed, flangeless turbine structure of the present invention. Figure 2 for Figure 1 Side view. Detailed Implementation

[0016] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: 1. Straight cylindrical section flow channel; 2. Arc section flow channel; 3. Flange; 4. Vertical rib; 5. Ring rib; 6. Inner clamping structure; 7. Bolt; 8. Nut; 9. Positioning bracket; 10. Process connection plate.

[0017] Example 1 like Figure 1 and 2 As shown, a machining process for a segmented, multi-lobed, flangeless turbine runner chamber includes the following steps: Step 1: Prepare 1 / 4 straight cylindrical section flow channel group 1 welded half blank and 1 / 3 circular arc section flow channel group 2 welded half blank; Step 2: Align the multi-lobed straight cylindrical section flow channel 1 and the multi-lobed arc section flow channel 2 with their respective shapes, find the alignment lines and horizontal alignment lines, and combine them into one unit. Step 3, draw lines: 3.1 Check the horizontal correction lines at both ends and the correction lines on the machined surface of the joint surface based on the re-marking of the outer circle of the unmachined cylinder. The alignment error should be within 1mm. 3.2 Draw the center cross line, the machining lines of the two end planes, the correction circle line, the inner circle machining line, and the waist line. Each machining part should be aligned with the others to ensure that the allowance of each machining surface is uniform. 3.3 Mark the machining lines for the joint surface of each straight cylindrical section flow channel 1 (1 / 4); mark the machining lines for the joint surface of each arc section flow channel 2 (1 / 3); Step 4: Align with the line and rough and fine mill each joint surface; Straight cylindrical section flow channel 1: Mill one end of the mating surface, leave the other end unmilled; Arc section flow channel 2: Mill only one end of the mating surface of the two 1 / 3 group weld blanks, leave the other end unmilled, retain machining allowance, and leave the joint surfaces on both sides of the remaining 1 / 3 group weld blank unmachined. Step 5: Remove burrs, flash, and chamfer the edges, and grind the joint surface to meet the roughness requirements of the drawing. Then, assemble the two parts together, align the inner and outer shapes, and weld the process connecting plate 10 at the joint of the outer circle of the cylinder to align the outer shape and assemble them into one piece. Step 6: Redraw the horizontal correction lines at both ends, the correction lines for the joint surface, the center cross line, the processing lines for both ends, the correction circle line, the inner circle processing line, the outer circle processing line, and the joint surface processing line; Step 7: Remove burrs, sharp edges, and grind the joint surface to meet the roughness requirements of the drawing. Then, assemble the blanks and align the inner and outer shapes. Step 8, Rough Turning: Clamp the outer circle, align the circle line and end face line, program the CNC, and rough turn one end face and inner curved surface; Adjust the surface, clamp the outer circle, align the machined inner circle and end face, and rough turn the other end face, inner conical surface, and stepped plane. Semi-finish turning and finish turning: Clamp the outer circle, align the machined inner circle and plane, semi-finish turning and finish turning one end face, all outer circles, inner curved surfaces, weld corners at the chamfered inner circle, inner circle, stop, stepped plane, grooving, and chamfering; adjust the surface, align with leveling stakes, clamp the outer circle, align the machined inner circle, semi-finish turning and finish turning the other end face, inner conical surface, weld corners at the chamfered inner circle, stepped plane, and chamfering; Step 9: Draw a central crosshair and mark ±X and Y. The marks are located on the outer circle of the cylinder. Draw machining lines for each hole. Step 10: Use a dial indicator to align the flange plane 3 and the outer circle of the stop, and drill the threaded holes to the dimensions shown in the drawing; Step 11: Machine tap each thread to the dimensions shown in the drawing; Step 12, Milling: Step 12.1: Before processing each group of welded parts, reinforce the impeller chamber with anti-deformation supports; Step 12.2: Mill off 10 welds on each process connection plate on the outer circumference of the cylinder; Step 12.3: Grind the unprocessed areas of the weld and disassemble it into segments; Step 12.4: Use a dial indicator to align the joint surface and mill the weld bevel at the joint surface to the dimensions shown in the drawing; Step 13: The multi-lobed straight cylindrical section flow channel 1 and the multi-lobed arc section flow channel 2 are assembled by the inner clamping structure 6 consisting of bolts 7, nuts 8 and positioning brackets 9. Through the inner clamping structure 6 consisting of bolts 7, nuts 8 and positioning brackets 9, the multi-lobed straight cylindrical section flow channel 1, the multi-lobed arc section flow channel 2, the vertical rib 4, the ring rib 5 and the flange 3 are assembled into one piece, and the bolts are tightened. The connection parts are welded firmly according to the drawing requirements. Step 14: Weld the multi-lobed straight cylindrical section flow channel 1 and the multi-lobed arc section flow channel 2 together and hoist them to replace the old impeller chamber.

[0018] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A segmented, multi-lobed, flangeless turbine runner chamber for a water turbine. The machining process is characterized by, Includes the following steps: Step 1: Prepare multi-lobed straight cylindrical section flow channels and multi-lobed arc section flow channels; Step 2: Align the multi-lobed straight cylindrical section flow channel and the multi-lobed arc section flow channel with their respective shapes, find the alignment lines and horizontal alignment lines, and combine them into one unit. Step 3: Draw horizontal correction lines at both ends, correction lines for the joint surface, center cross line, and processing lines for both ends, as well as correction circles, inner circle processing lines, outer circle processing lines, and joint surface processing lines respectively. Step 4: Align with the line and perform rough and fine milling on each joint surface; Step 5: Weld the process connecting plate at the joint of the outer circle of the cylinder, align the outer shape and assemble them into one piece; Step 6: Redraw the horizontal correction lines at both ends, the correction lines for the joint surface, the center cross line, the processing lines for both ends, the correction circle line, the inner circle processing line, the outer circle processing line, and the joint surface processing line; Step 7: Remove burrs, sharp edges, and grind the joint surface to meet the roughness requirements of the drawing. Then, assemble the blanks and align the inner and outer shapes. Step 8: Rough turning, semi-finish turning, finish turning; Step 9: Draw a central crosshair and mark ±X and Y. The marks are located on the outer circle of the cylinder. Draw machining lines for each hole. Step 10: Use a dial indicator to align the flange plane and the outer circle of the stop, and drill the threaded holes to the dimensions shown in the drawing. Step 11: Machine tap each thread to the dimensions shown in the drawing; Step 12, Milling: Step 12.1: Before processing each group of welded parts, reinforce the impeller chamber with anti-deformation supports; Step 12.2: Mill off the welds at the process connection plates on the outer circle of the cylinder; Step 12.3: Grind the unprocessed areas of the weld and disassemble it into segments; Step 12.4: Use a dial indicator to align the joint surface and mill the weld bevel at the joint surface to the dimensions shown in the drawing; Step 13: Assemble the multi-lobed straight cylindrical section flow channel, multi-lobed arc section flow channel, vertical ribs, ring ribs and flanges into one piece; Step 14: Weld the multi-lobed straight cylindrical section flow channel and the multi-lobed arc section flow channel together and hoist them to replace the old impeller chamber.

2. The machining process of the turbine runner chamber with a segmented, multi-lobed, flangeless structure as described in claim 1, characterized in that: The multi-lobed circular arc section flow channel is a concave circular arc flow channel, with the vertical ribs, ring ribs, and flange ends located on the same plane.

3. The machining process for the turbine runner chamber of the segmented multi-lobed flangeless turbine structure according to claim 2, characterized in that: In step 8, rough turning: clamp the outer circle, align the circle line and end face line, CNC program, rough turn one end face and inner curved surface; surface adjustment: clamp the outer circle, align the machined inner circle and end face, rough turn the other end face, inner conical surface and stepped plane.

4. The machining process of the turbine runner chamber with a segmented, multi-lobed, flangeless structure as described in claim 3, characterized in that: In step 8, semi-finish turning and finish turning: clamp the outer circle, align the machined inner circle and plane, semi-finish turning and finish turning one end face, each outer circle, inner curved surface, weld corner at the chamfered inner circle, inner circle, stop, step plane, groove, and chamfer; adjust the surface, align the leveling stakes, clamp the outer circle, align the machined inner circle, semi-finish turning and finish turning the other end face, inner conical surface, weld corner at the chamfered inner circle, step plane, and chamfer.

5. The machining process of the turbine runner chamber with a segmented, multi-lobed, flangeless structure according to claim 4, characterized in that: The number of lobes in a multi-lobed straight cylindrical section flow channel is greater than the number of lobes in a multi-lobed circular arc section flow channel.

6. The machining process of the turbine runner chamber with a segmented, multi-lobed, flangeless structure according to claim 5, characterized in that: The straight cylindrical section of the flow channel has 4 lobes, while the arc section of the flow channel has 3 lobes.

7. The machining process for the turbine runner chamber of the segmented multi-lobed flangeless turbine structure according to claim 6, characterized in that: In step 13, the inner fitting structure of the multi-lobed straight cylindrical section flow channel and the multi-lobed arc section flow channel is assembled into one piece.

8. The machining process of the turbine runner chamber with a segmented, multi-lobed, flangeless structure according to claim 7, characterized in that: In step 4, the already machined joint surfaces are rough and finish milled, and the joint surface machining lines are redrawn.

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