A double key groove machining process for a Francis turbine runner

Abstract

The application relates to the technical field of water turbine runner installation, and discloses a Francis horizontal water turbine runner double-key groove machining process, which comprises the following steps: providing a runner group welding blank; polishing the runner to meet roughness requirements; semi-finishing machining of each part of an upper crown and a lower ring; adjusting a surface; processing casting defects; finishing machining of each part of the upper crown and the lower ring; drawing a center cross line and all machining lines; rotating a horizontal static balance tool, performing a horizontal static balance test, redrawing a center cross line and double-key groove machining lines; aligning and performing numerical control programming to coarsely and finely mill a double-key groove at a runner upper crown key groove; taking the processed double-key groove as a positioning reference, correcting a plane reference side surface, rechecking the size and geometric tolerance of the runner double-key groove; taking the processed double-key groove as the positioning reference, correcting the plane reference side surface, and precisely inserting the runner double-key groove into place, so that the process has the advantage of high machining precision.

Description

Technical Field

[0001] This invention relates to the field of turbine runner installation technology, specifically a double keyway processing technology for a mixed-flow horizontal turbine runner. Background Technology

[0002] As the core component of the mixed-flow horizontal turbine, the runner mainly consists of an upper crown and a lower ring. The surface of the upper crown needs to be machined with a double keyway for mounting the runner.

[0003] The conventional method for machining the keyway on a rotary wheel is to directly draw a central crosshair and keyway machining line on the crown plane of the rotary wheel, align the keyway line and keyway pattern punch marks using a slotting machine, and then rough and fine insert the keyway into place.

[0004] The shortcomings of existing technologies: Traditional processing methods are not only inefficient, but also fail to guarantee the dimensional accuracy and geometric tolerances of double keyways in accordance with design requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a machining process for double keyways in the runner of a mixed-flow horizontal turbine, so as to solve the problems of dimensional accuracy and geometric tolerance in the machining of double keyways.

[0006] To achieve the above objectives, the present invention provides a machining process for a double keyway in a mixed-flow horizontal turbine runner, characterized by comprising the following steps: 1. Supply of welding blanks for the turbine assembly; 2. Grind the weld seams and flow channel surfaces of the blades, upper crown, and lower ring, and polish them to the required roughness. 3. Semi-finished machining of the upper crown and lower ring parts; 4. Adjust the surface, use a dial indicator to calibrate the outer circle of the lower ring, with an error ≤0.03mm. Semi-finish machine all planes of the upper crown, including the inner and outer circles, stepped planes, sealing grooves, inner conical surfaces, and recessed parts, leaving a margin of 1mm-2mm on each side. 5. Address casting defects and perform welding repairs; 6. Finely machine the upper crown and lower ring parts; 7. Draw the center crosshair, all hole machining lines, and double keyway machining lines; 8. Drill all the bottom holes and countersunk holes according to the guide line, and lift up the tapping thread; 9. Tap the remaining threads, remove all burrs, rough edges, and bevels; 10. Transfer to the horizontal static balancing tool and perform a horizontal static balancing test. Record the unbalanced weight and orientation. 11. Handling unbalanced weights; 12. Recalibrate the horizontal static balance; 13. Redraw the center crosshair and double keyway machining line; 14. Using the tapered inner hole as a reference, align the machine and use CNC programming to rough and finish mill the double keyway on the keyway of the rotating wheel. 15. Using the machined flat double keyway as the positioning datum, correct the side of the flat datum, leave a 1mm allowance on each side for rough inserting the double keyway of the roller, and re-inspect whether the dimensions and geometric tolerances of the double keyway of the roller meet the requirements. 16. Using the machined flat double keyway as the positioning reference, correct the side of the flat reference and insert the double keyway into position.

[0007] Preferably, in order to improve the machining accuracy, in step 3, the outer circle of the upper crown of the clamping wheel is clamped, the upper crown plane is aligned, the inner end face of the upper crown is precision machined to the required position, the lower ring end face, the outer circles of each level, the inclined surface and the R arc are semi-precision machined, leaving a allowance of 1mm-2mm on each side, and the opening plane of the machining wheel is machined to the required position.

[0008] Preferably, in order to improve the machining accuracy, in step 6, the outer circle of the lower ring is clamped, the outer circle and flange plane are calibrated with a dial indicator with a tolerance of 0.03mm, and the planes, inner circle, outer circle, recessed part, R fillet, inner conical surface, degassing, sealing groove, degassing groove and chamfer are precision machined to the dimensions shown in the drawing. The outer circle of the lower ring is machined and the chamfer is also made to the dimensions shown in the drawing.

[0009] To facilitate handling of unbalanced weight, in step 11, the excess portion is removed by offset turning or CNC milling at the upper crown recess.

[0010] To facilitate handling the unbalanced weight, in step 11, an unbalanced hole is drilled on the lower ring end face of the wheel and sealed with a sealing plate and then ground smooth.

[0011] To facilitate the installation of the rotary wheel, the following steps are also included: 17. Deburring, removing burrs and chamfering; 18. Taking out the rotary wheel and motor spindle, cleaning the mating surfaces, and performing pre-installation, keying, and taper inner hole fitting; 19. Polishing the entire surface of the rotary wheel to meet the roughness requirements of the drawing, and removing any surface bumps and scratches.

[0012] The beneficial effects are as follows: The rotary wheel adopts a double keyway structure, which has extremely high requirements for the form and position tolerances and dimensions of the keyway. First, before machining, a center cross line and double keyway machining lines are drawn on the crown plane of the rotary wheel as a reference. Then, the double keyway is rough and finish milled on the crown keyway of the rotary wheel using CNC programming as a positioning reference. Then, the two reference sides of the plane keyway are aligned by a slotting machine, and the double keyway is rough and finish inserted into place, ensuring the dimensional and form and position tolerances of the double keyway and high machining accuracy. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of Embodiment 1; Figure 2 for Figure 1 Top view.

[0014] Reference numerals: 1. Upper crown; 2. Lower ring; 3. Step; 4. Cut sealing groove; 5. Inner conical surface; 6. Degassing; 7. Degassing groove; 8. Double keyway; 9. Reference side. Detailed Implementation

[0015] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. However, the present invention is not limited to these embodiments. Any improvements made to the present invention without departing from the principle of the present invention also fall within the protection scope of the claims of the present invention.

[0016] Example 1 like Figure 1 and Figure 2 As shown, a machining process for a double keyway in a mixed-flow horizontal turbine runner includes the following steps: 1. Supply of welding blanks for the turbine assembly; 2. The fitter grinds the weld seams and flow channel surfaces of the blades, upper crown 1, and lower ring 2, and polishes them to the required roughness. 3. Semi-finish turning: Clamp the outer circle of the upper crown of the wheel, align the upper crown plane, finish turn the inner end face of the upper crown to the desired position, semi-finish turn the lower ring end face, the outer circles of each level, the bevel and the R arc, leaving a allowance of 1mm-2mm on each side, and machine the wheel opening plane to the desired position. 4. Adjust the surface, use a dial indicator to calibrate the outer circle of the lower ring, with an error ≤0.03mm. Semi-finish machine all planes of the upper crown 1, including the inner and outer circles, the stepped plane, the sealing groove 4, the inner conical surface 5, and the recessed part, leaving a margin of 1mm-2mm on each side. 5. The fitter repairs casting defects and assists with welding repairs; 6. Finish machining: Clamp the outer circle of the lower ring, calibrate the outer circle and flange plane with a dial indicator, tolerance 0.03mm, finish machine all planes, inner circle, outer circle, recessed part and R fillet, inner conical surface 5, degassing surface 6, cut sealing groove 4, degassing groove 7, chamfer to the drawing dimensions, machine the outer circle of the lower ring and chamfer to the drawing dimensions; Degassing surface 6: the middle dimension of inner conical surface 5 is larger than the upper and lower inner conical surfaces 5; 7. Draw the center crosshair, all hole machining lines, and double keyway machining lines; 8. Drill all the bottom holes and countersunk holes according to the guide line, and lift up the tapping thread; 9. The fitter taps the remaining threads, removes all burrs, flash, and chamfers; 10. The fitter switches to a horizontal static balancing tool and performs a horizontal static balancing test, recording the unbalanced weight and orientation. 11. Handling unbalanced weight: Choose either a or b. a. The excess part can be removed by offset turning or CNC milling at the recess of the upper crown 1; b. Drill unbalanced holes on the end face of the lower ring of the wheel and seal them with a sealing plate and grind them smooth. 12. Recalibrate the horizontal static balance; 13. Redraw the center crosshair and double keyway machining line; 14. Using the tapered inner hole as a reference, align and CNC program the rough and finish milling of the double keyway 8 at the crown keyway on the rotary wheel; 15. Using the machined flat double keyway 8 as the positioning datum, correct the side of the flat datum 9, roughly insert the wheel double keyway 8, leaving a 1mm allowance on each side, and re-inspect whether the dimensions and geometric tolerances of the wheel double keyway 8 meet the requirements. 16. Using the machined flat double keyway 8 as the positioning reference, correct the side surface of the flat reference 9, and insert the double keyway 8 into place; 17. The fitter removes burrs, flash, and chamfers the edges, weighs the wheel, and prints the weight in kilograms on the wheel's surface. 18. The fitter takes out the rotary wheel and motor spindle, cleans the mating surfaces, and performs pre-assembly, keying, and taper inner hole fitting; 19. Polish the entire surface of the rotary wheel to meet the roughness requirements of the drawing, and clean away any bumps, scratches, etc. on the surface.

Claims

1. A machining process for a double keyway in a mixed-flow horizontal turbine runner, characterized in that, Includes the following steps: Step 1: Supply the welding blank for the turbine assembly; Step 2: Grind the weld seams and flow channel surfaces of the blades, upper crown, and lower ring, and polish them to the required roughness. Step 3: Clamp the outer circle of the crown on the wheel, align the upper crown plane, finish machine the inner end face of the upper crown to the desired position, semi-finish machine the lower ring end face, the outer circles of each level, the bevel and the R arc, leaving a allowance of 1mm-2mm on each side, and machine the wheel opening plane to the desired position. Step 4: Adjust the surface. Use a dial indicator to calibrate the outer circle of the lower ring. The error should be ≤0.03mm. Semi-finish machine all planes of the upper crown, including the inner and outer circles, the stepped plane, the sealing groove, the inner conical surface, and the recessed part, leaving a margin of 1mm-2mm on each side. Step 5: Address casting defects and perform welding repairs; Step 6: Clamp the outer circle of the lower ring, use a dial indicator to check the outer circle and flange plane, tolerance 0.03mm, finish machine all planes, inner circle, outer circle, recessed part, R fillet, inner conical surface, degassing, cut sealing groove, degassing groove and chamfer to the dimensions shown in the drawing, and machine the outer circle of the lower ring and chamfer to the dimensions shown in the drawing. Step 7: Draw the center crosshair, all hole machining lines, and double keyway machining lines; Step 8: Drill the bottom holes and countersink holes according to the guide line, and lift up the tapping thread; Step 9: Tap the remaining threads, remove all burrs, flash, and chamfers; Step 10: Transfer to the horizontal static balancing tool, perform a horizontal static balancing test, and record the unbalanced weight and orientation; Step 11: Handle the unbalanced weight; Step 12: Recalibrate the horizontal static balance; Step 13: Redraw the center crosshair and double keyway machining line; Step 14: Using the tapered inner hole as a reference, align the machine and use CNC programming to rough and finish mill the double keyway on the keyway of the rotating wheel. Step 15: Using the machined flat double keyway as the positioning datum, correct the side of the flat datum, rough insert the double keyway of the roller with a 1mm allowance on each side, and re-inspect whether the dimensions and geometric tolerances of the double keyway of the roller meet the requirements. Step 16: Using the machined flat double keyway as the positioning reference, correct the side of the flat reference and insert the double keyway into position.

2. The double keyway machining process for the runner of a mixed-flow horizontal turbine according to claim 1, characterized in that: In step 11, the excess portion is removed by offset turning or CNC milling at the upper crown recess.

3. The double keyway machining process for the runner of a mixed-flow horizontal turbine according to claim 2, characterized in that: In step 11, an imbalance hole is drilled on the lower ring end face of the impeller and sealed with a sealing plate and then ground smooth.

4. The machining process for the double keyway of the runner of a mixed-flow horizontal turbine according to any one of claims 1-3, characterized in that, It also includes: Step 17, deburring, trimming, and chamfering; Step 18: Take out the rotary wheel and motor spindle, clean the mating surfaces, and perform pre-assembly, keying, and taper inner hole fitting; Step 19: Polish the entire surface of the rotary wheel to meet the roughness requirements of the drawing, and clean off any bumps and scratches on the surface.

Images