Method for processing guide vane split key pin hole of water turbine by drilling machine

Abstract

The application discloses a method for processing guide vane split key pin holes of a water turbine by a drilling machine. The main steps are as follows: assembling, aligning and pressing the guide vane, the guide vane arm and the connecting plate, aligning the drilling machine according to the processing line position of the guide vane split key pin holes, processing the split key pin holes by using a trial processing, twice drilling, twice hole expanding and once reaming process. Usually, the number of guide vane split key pin holes of one hydroelectric generator set can reach 50 on average, and the processing period is long when a numerical control boring machine is used. The application provides a method for processing the guide vane split key pin holes of the water turbine by using the drilling machine instead of the boring machine, which can relieve the production scheduling pressure of the numerical control boring machine in the workshop, save the processing and using cost of the numerical control machine under the premise of ensuring the processing precision of the split key pin holes, and has the characteristics of simple operation, strong universality and the like, and can be suitable for processing the guide vane split key pin holes of the hydroelectric generator set.

Description

Technical Field

[0001] This invention relates to the field of machining of hydro-generator sets, and in particular to a method for machining the key pin holes of hydro-turbine guide vanes using a drilling machine. Background Technology

[0002] The guide vane split key of a hydro turbine is a key component in the water guiding mechanism used to connect the guide vane shaft diameter and the guide vane arm to transmit the torque of the relay mechanism and realize the opening and closing action of the movable guide vane. Typically, a hydro turbine unit has 16-24 guide vanes, and each guide vane has 2-3 split key pin holes, meaning that on average, each unit has 50 split key pin holes. When machining with a CNC boring machine, the large number of pin holes, the high surface precision requirements, and the fact that the split key pin holes are slender holes with a length-to-diameter ratio greater than 4.5 times make machining difficult and result in a long machining cycle on the CNC boring machine. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method for high-precision machining of key pin holes for turbine guide vanes using a drilling machine instead of a boring machine, which is simple to operate, highly versatile, and reduces costs. The technical solution of this invention is as follows:

[0004] S1. When machining individual parts such as guide vanes, guide vane arms, and connecting plates, engrave lines on the workpiece surface according to the center line position of the design drawings. This serves as the basis for assembling the guide vanes, guide vane arms, and connecting plates at relative angles when machining the split key pin holes later.

[0005] S2. The guide vane, guide vane arm, and connecting plate are assembled according to the center lines engraved on each piece to form an assembly.

[0006] S3. According to the drawing, mark the key pin hole positions and mark the key hole machining lines on the assembly.

[0007] S4. Place the jig on the drilling machine processing platform;

[0008] S5. Lift the assembly above the jig;

[0009] S6. Align the lower shaft diameter of the guide vane with the shaft hole of the jig and assemble vertically.

[0010] S7, pressure plate I, support tube I, lock nut I, and T-screw I constitute pressure plate tool I;

[0011] S8, pressure plate II, support tube II, lock nut II, and T-screw II constitute pressure plate tool II;

[0012] S9, pressure plate Ⅲ, support tube Ⅲ, lock nut Ⅲ, and T-screw Ⅲ constitute pressure plate tool Ⅲ;

[0013] S10. Use pressure plate tool I and pressure plate tool II to press the guide vane on both sides of the guide vane body;

[0014] S11. Use pressure plate tool Ⅲ to press the adjusting plate onto the plane of the connecting plate;

[0015] S12. Use adjusting screw I and adjusting screw II to adjust the angle between the connecting plate, the guide vane arm and the center line of the guide vane body to the theoretical angle required by the design drawings.

[0016] S13. Use a level to adjust the upper surface of the guide vane to be within 0.02mm horizontal;

[0017] S14. Lock the adjusting screws I and II on both sides;

[0018] S15. Use clamping tool III to press the assembly on the plane of the connecting plate;

[0019] S16. Check that the upper end face of the guide vane is level until it meets the requirements;

[0020] S17. Align the drilling machine according to the position of the key pin hole machining line of the guide vane segment;

[0021] S18. Trial machining of the split key pin hole: Drill a shallow pit according to the position of the pin hole machining line, and check that the position of the shallow pit is consistent with the line.

[0022] S19. Machining the bottom hole of the split key pin hole;

[0023] S20, Enlarge the hole for the split key pin;

[0024] S21. Machining the split key pin hole and reaming the hole;

[0025] S22. Clean the split key pin hole, and clean the surface of the guide vane, guide vane arm and connecting plate.

[0026] S23. Check the surface roughness of the split key pin hole and measure the pin hole diameter with an inside micrometer.

[0027] S24. Remove pressure plate tool I, pressure plate tool II, and pressure plate tool III; loosen adjusting screw I and adjusting screw II; and lift the assembly away from the work station.

[0028] Furthermore, in S13, the upper end face of the guide vane is leveled by using a leveling instrument to adjust the level of the upper end face to within 0.02mm.

[0029] Furthermore, in S19, the bottom hole is drilled in two stages. The first stage uses a drill bit with a diameter of 0.5 to 0.7 times that of the split key hole. The second stage uses a drill bit with a diameter of 0.87 to 0.93 times that of the split key hole. At this time, the surface roughness of the bottom hole reaches 12.5 μm to 6.3 μm.

[0030] Furthermore, in S20, the hole expansion is performed in two stages. The first stage of hole expansion leaves a margin of 0.2mm-0.3mm on one side, and the second stage of hole expansion leaves a margin of 0.1mm-0.15mm on one side. At this time, the surface roughness of the expanded hole reaches 3.2μm.

[0031] Furthermore, in S21, the diameter of the pin hole required by the drawing is obtained from the first reaming, and the surface roughness of the pin hole can reach 1.6μm.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. By creating simple tooling, a conventional drilling machine can be used to replace a CNC boring machine to complete the machining of the key pin holes for the guide vanes of a water turbine. In the early stages of testing, the machining process and cutting parameters for the key pin holes were continuously optimized, and a relatively complete machining process for the drilling machine to handle the key pin holes was summarized. In subsequent practical applications, the results were significant. Under the premise of ensuring the machining quality and efficiency of difficult slender holes with a length-to-diameter ratio greater than 4.5, the diameter tolerance and surface roughness of the key pin holes can meet the high-precision requirements of the drawings. This effectively solves the problem of the workshop's machining of guide vane key pin holes occupying the CNC boring machine's usage cycle and alleviates the production scheduling pressure of the workshop's CNC boring machines.

[0034] 2. This invention is simple to operate, highly versatile, saves on the cost of CNC machine tool processing, and can be widely applied to the processing of guide vane key pin holes in all types of hydropower units. Attached Figure Description

[0035] Figure 1 This is a front view schematic diagram of the drilling machine used in this invention to process the key pin holes for the guide vanes of a water turbine.

[0036] Figure 2 This is a cross-sectional view (AA) of the front view of the drilling machine machining of the key pin hole for the guide vane of the water turbine according to the present invention.

[0037] The following are the labels in the diagram: 1-Drilling machine; 2-Platform; 3-Support rod I; 4-T-screw I; 5-Pressure plate I; 6-Locking nut I; 7-Jig; 8-Guide vane; 9-T-screw II; 10-Support rod II; 11-Pressure plate II; 12-Locking nut II; 13-T-screw III; 14-Support rod III; 15-Pressure plate III; 16-Adjusting plate; 17-Locking nut III; 18-Connecting plate; 19-Split key pin hole; 20-Guide vane arm; 21-Adjusting screw I; 22-Adjusting screw II. Detailed Implementation

[0038] Taking the machining of the split key pin holes of the guide vanes of a pumped-storage hydroelectric generator unit in a hydropower station as an example, the machining process using the method of this invention is explained: The turbine guide vanes, guide vane arms, and connecting plates of this unit have been precision machined individually. The next step is assembly, which involves drilling and reaming the split key pin holes of the guide vanes and guide vane arms. The guide vanes weigh 2140KG, are 2.86M long, and are made of ZG04Cr13Ni5Mo material. The guide vane arms are made of ZG20Mn material. The total weight after assembly with the guide vane arms and connecting plates is approximately 2700KG. Each set of guide vane split key pin holes consists of 2-Φ70 (+0.03,0), with an effective hole depth of 320mm and a surface roughness of 1.6μm. These are typical slender holes with a length-to-diameter ratio greater than 4.5, which are relatively difficult to machine.

[0039] Specific implementation method one: Refer to Figure 1 and Figure 2 This embodiment describes a method for machining keyway pin holes for split sections of turbine guide vanes using a drilling machine. The method is implemented through the following steps:

[0040] When machining individual pieces of S1, guide vane 8, guide vane arm 20, and connecting plate 18, lines are engraved on the workpiece surface according to the center line position of the design drawing. This serves as the basis for assembling guide vane 8, guide vane arm 20, and connecting plate 18 at relative angles when machining the split key pin holes later.

[0041] S2, guide vane 8, guide vane arm 20, and connecting plate 18 are assembled according to the center lines engraved on each piece to form an assembly;

[0042] S3. According to the theoretical division of the key pin hole 19 position in the drawing, mark the pin hole machining line and check the line on the assembly;

[0043] S4. Place the jig 7 on the machining platform 2 of the drilling machine 1;

[0044] S5. Lift the assembly above the jig 7;

[0045] S6. Align the lower shaft diameter of guide vane 8 with the shaft hole of jig 7 and assemble vertically.

[0046] S7, pressure plate I5, support tube I3, lock nut I6, and T-screw I4 constitute pressure plate tool I;

[0047] S8, pressure plate II11, support tube II10, lock nut II12, and T-screw II9 constitute pressure plate tool II;

[0048] S9, pressure plate Ⅲ15, support tube Ⅲ14, lock nut Ⅲ17, and T-screw Ⅲ13 constitute pressure plate tool Ⅲ;

[0049] S10. Use pressure plate tool I and pressure plate tool II to press the guide vane on both sides of the guide vane body;

[0050] S11. Use the pressure plate tool III to press the adjusting plate 16 onto the plane of the connecting plate 18;

[0051] S12. Use adjusting screw I 21 and adjusting screw II 22 to adjust the angle between the connecting plate 18, the guide vane arm 20 and the center line of the guide vane 8 to the theoretical angle required by the design drawings.

[0052] S13. Use a level to adjust the upper surface of guide vane 8 to be within 0.02mm.

[0053] S14, Lock the adjusting screws I 21 and II 22 on both sides;

[0054] S15. Use the clamping tool III to press the assembly on the plane of the connecting plate 18;

[0055] S16. Check that the upper end face of guide vane 8 is level until it meets the requirements;

[0056] S17. Align the drilling machine with the machining line position of guide vane 8 split key pin hole 19.

[0057] S18, Trial machining of split key pin hole 19: Drill a shallow pit according to the pin hole machining line position, visually check whether the position of the shallow pit is correct, and continuously correct it until the position of the shallow pit is concentric with the line. The feed rate during trial drilling is less than the normal feed rate to ensure that the drill bit does not deviate.

[0058] S19, Machining the bottom hole of the split key pin hole 19;

[0059] S20, enlarge the 19-hole of the split key pin;

[0060] S21. Machining the split key pin hole 19 reamed hole;

[0061] S22. Clean the split key pin hole 19, and clean the surfaces of guide vane 8, guide vane arm 20 and connecting plate 18.

[0062] S23. Check the surface roughness of the split key pin hole 19 and measure the diameter of the pin hole with an inside micrometer.

[0063] S24. Remove pressure plate tool I, pressure plate tool II, and pressure plate tool III; loosen adjusting screw I 21 and adjusting screw II 22; and lift the assembly away from the work station.

[0064] This embodiment demonstrates a method for high-precision machining of guide vane split key pin holes in hydroelectric turbines using a drilling machine instead of a boring machine. This method effectively solves the problem of machining guide vane split key pin holes constantly occupying the usage cycle of CNC boring machines, alleviating the production scheduling pressure on CNC boring machines in the workshop. Furthermore, it saves on the machining cost of CNC machine tools while ensuring the machining accuracy of the split key pin holes. It features simple operation and strong versatility, and can be applied to the machining of guide vane split key pin holes in all types of hydroelectric units.

[0065] Specific Implementation Method Two: Refer to Figure 1 and Figure 2 This embodiment further defines S13 as described in Specific Embodiment 1. In this embodiment, the upper end face of the leveling guide vane 8 in S13 is horizontal, and the horizontal level is adjusted to within 0.02mm using a leveling instrument.

[0066] In this embodiment, leveling the upper end face of the guide vane is a key process before the subsequent machining of the split key pin hole. The leveling accuracy is high, ensuring the perpendicularity of the split key pin hole, which is more conducive to the drilling, reaming, and boring of the pin hole.

[0067] Specific Implementation Method Three: Refer to Figure 1 and Figure 2 This embodiment further defines S19 as described in Specific Embodiment 1. In this embodiment, the bottom hole in S19 is drilled in two stages. The first stage uses a Φ46 high-speed steel drill bit to drill the bottom hole to a depth of 335mm, with cutting parameters: Vc < 20m / min, F = 0.2-0.3mm / r. The second stage uses a Φ64 high-speed steel drill bit to drill the bottom hole to a depth of 335mm, with cutting parameters: Vc < 15m / min, F = 0.2-0.3mm / r. At this time, the surface roughness of the bottom hole is 6.3μm. When drilling the deep hole, the drill bit reaches a drilling depth of twice the diameter, withdraws once for chip removal, and adds cooling and lubrication.

[0068] Specific Implementation Method Four: Refer to Figure 1 and Figure 2 This embodiment further defines S20 as described in Specific Embodiment 1. In this embodiment, the hole expansion in S20 is performed in two steps. The first expansion is performed to Φ69.5mm with a hole depth of 335mm. The cutting parameters are: Vc = 8m / min-14m / min, F = 0.5-0.6mm / r. The second expansion is performed to Φ69.7mm with a hole depth of 335mm. The cutting parameters are: Vc = 8m / min-14m / min, F = 0.5-0.6mm / r. At this point, the surface roughness of the expanded hole is 3.2μm.

[0069] In embodiments three and four, by drilling and reaming twice, the cutting parameters are strictly controlled to keep the allowance before reaming within a suitable range and to ensure that the surface has a small roughness, thus providing good processing conditions for the final reaming process and ensuring the surface quality after reaming.

[0070] Specific Implementation Method Five: Refer to Figure 1 and Figure 2This embodiment further defines S21 as described in Specific Embodiment 1. In this embodiment, the hole in S21 is reamed once to 70 (+0.03,0) the diameter of the pin hole required by the drawing, the hole depth is 320mm, the cutting parameters are: Vc = 1.2m / min-5m / min, F = 0.8-0.9mm / r, and the surface roughness of the pin hole is 1.6μm.

[0071] In Implementation Methods 1 to 5, the specified cutting parameters are a set of cutting parameters suitable for drilling, reaming, and boring slender pin holes, obtained through multiple processing tests conducted using a fixed drilling machine and similar workpiece materials. If the machine tool, workpiece material, or hole diameter is changed, this implementation method can be used as a reference for testing, and slight adjustments can be made based on the actual pin hole processing situation to obtain the most suitable process flow and cutting parameters for one's own equipment and products.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for machining key pin holes for split sections of turbine guide vanes using a drilling machine, characterized by the following steps: When machining individual pieces of S1, guide vane (8), guide vane arm (20), and connecting plate (18), lines are engraved on the workpiece surface according to the center line position of the design drawing. This serves as the basis for assembling the guide vane (8), guide vane arm (20), and connecting plate (18) at relative angles when machining the split key pin holes later. S2, guide vane (8), guide vane arm (20), and connecting plate (18) are assembled according to the center lines engraved on each piece to form an assembly; S3. According to the drawing, mark the key pin hole (19) position and mark the pin hole machining line and inspection line on the assembly; S4. Place the jig (7) on the machining platform (2) of the drilling machine (1); S5. Lift the assembly above the jig (7); S6. Align the lower shaft diameter of the guide vane (8) with the shaft hole of the fixture (7) and assemble vertically. S7, pressure plate I (5), support tube I (3), locking nut I (6), and T-screw I (4) form pressure plate tool I; S8, pressure plate II (11), support tube II (10), locking nut II (12), and T-screw II (9) constitute pressure plate tool II; S9, pressure plate Ⅲ (15), support tube Ⅲ (14), locking nut Ⅲ (17), and T-screw Ⅲ (13) constitute pressure plate tool Ⅲ; S10. Use pressure plate tool I and pressure plate tool II to press the guide vane on both sides of the guide vane body; S11. Use the pressure plate tool III to press the adjusting plate (16) onto the plane of the connecting plate (18); S12. Use adjusting screw I (21) and adjusting screw II (22) to adjust the angle between the connecting plate (18), the guide vane arm (20) and the center line of the guide vane (8) to the theoretical angle required by the design drawings. S13, the upper end face of the leveling guide vane (8) is horizontal; S14, lock the adjusting screws I (21) and II (22) on both sides; S15. Use the clamping tool III to press the assembly on the plane of the connecting plate (18); S16. Check that the upper surface of the guide vane (8) is level and meets the requirements; S17. The drilling machine is aligned with the machining line position of the key pin hole (19) of the guide vane (8); S18, Trial machining of split key pin hole (19), drill a shallow pit according to the position of the pin hole machining line, and check that the position of the shallow pit should be consistent with the line. S19, Machining the bottom hole of the split key pin hole (19); S20, Machining the split key pin hole (19) and enlarging it; S21. Machining the split key pin hole (19) and reaming the hole; S22. Clean the split key pin hole (19), and clean the surfaces of the guide vane (8), guide vane arm (20) and connecting plate (18); S23. Check the surface roughness of the split key pin hole (19) and measure the diameter of the pin hole with an inside micrometer. S24. Remove pressure plate tool I, pressure plate tool II, and pressure plate tool III, loosen adjusting screw I (21) and adjusting screw II (22), and lift the assembly away from the work station.

2. The method for machining keyway holes for guide vanes of a water turbine using a drilling machine according to claim 1, characterized in that: In S13, the upper surface of the guide vane (8) is leveled. Using a leveling instrument, the upper surface is adjusted to be within 0.02mm.

3. The method for machining keyway holes for guide vanes of a water turbine using a drilling machine according to claim 1, characterized in that: In S19, the bottom hole is drilled twice. The first time, a drill bit with a diameter of 0.5 to 0.7 times that of the split keyhole (19) is used to drill the bottom hole. The second time, a drill bit with a diameter of 0.87 to 0.93 times that of the split keyhole (19) is used to drill the bottom hole. At this time, the surface roughness of the bottom hole reaches 12.5 μm to 6.3 μm.

4. The method for machining keyway holes for split sections of turbine guide vanes using a drilling machine according to claim 1, characterized in that: In step S20, the hole is expanded in two steps. The first expansion leaves a margin of 0.2mm-0.3mm on one side, and the second expansion leaves a margin of 0.1mm-0.15mm on one side. At this time, the surface roughness of the expanded hole reaches 3.2μm.

5. The method for machining keyway holes for guide vanes of a water turbine using a drilling machine according to claim 1, characterized in that: In S21, the diameter of the pin hole is required to be adjusted from the diameter specified in the drawing, and the surface roughness of the pin hole reaches 1.6μm.

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