Method for processing high-precision high-temperature alloy slender shaft

Abstract

This invention discloses a method for machining slender high-precision high-temperature alloy shafts. The method includes the following steps: a. aligning the tailstock and center rest of the CNC lathe with the rotation center of the spindle of the slender shaft to be machined; b. drilling center holes on the end face of the slender shaft and using the tailstock center to hold the center holes while turning the outer diameter of the slender shaft; c. rotating the slender shaft and repeating step b; d. grinding the outer diameters at both ends of the slender shaft; e. re-grinding the center holes on both ends of the slender shaft whose outer diameters were ground in step d; f. turning to initially remove excess material from the slender shaft; g. clamping and aligning one end of the slender shaft whose outer diameter was ground in step d, and then using the tailstock center to hold the other end; then using a general turning method to remove excess material a second time; finally, finish turning to complete the journal machining. This invention solves the technical problems of low efficiency due to the complexity of the high-precision long shaft machining process and unstable process due to the high skill requirements of the operators.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to a method for machining slender shafts of high-precision high-temperature alloys. Background Technology

[0002] Machining slender shafts has always been a challenge in the field of machining, especially those with a length-to-diameter ratio greater than 30. This particular slender tie rod is 682mm long, with a minimum outer diameter of 12.3mm, resulting in a length-to-diameter ratio of 55. Furthermore, it is made of the difficult-to-machine GH4169 material, requiring extremely high machining precision. The runout of the finest part relative to the center hole is within 0.013 mm, making the accuracy extremely difficult to guarantee (see...). Figure 1 , 2 The center tie rod is manufactured using traditional processes. During turning, the machining method is mostly segmented machining, and the clamping method adopts the tensioning method used in most slender rod machining applications. A special tensioning device is designed to prevent the part from bending caused by the center hole holding method, and at the same time to prevent bending and the waist-drum-shaped size distribution caused by the extension and contraction of the tie rod during the turning process. However, in actual machining, the tensioning method creates tensile stress on the part material, making machining difficult between the tool and the material, causing tool bounce, and making the tool prone to chipping. Moreover, when the tension is released, the stress in the tie rod is released, and the material springs back, causing bending and changes, which cannot meet the runout tolerance requirements. Segmented turning, using a follow post segmented cutting method, cannot achieve the 0.013 runout tolerance requirement at all, and can only barely reach 0.05. During the machining process, high-alloy materials are very difficult to machine, and the tools wear out quickly. The original plan used carbide-mounted turning tools on a conventional lathe, but the tools have poor wear resistance, and they need to be re-sharpened after two passes, which is very time-consuming. After turning, multiple segmented grinding processes are required to ensure the final machining accuracy, which requires very high technical skills from the lathe operators and grinding operators. The pass rate can only reach 30%, and the processing cycle is as long as 30 days, which is difficult to meet production requirements. Summary of the Invention

[0003] The purpose of this invention is to provide a method for machining slender, high-precision alloy shafts. This invention solves the technical problems of low efficiency due to the complexity of the high-precision long shaft machining process and instability caused by the excessively high skill requirements for workers.

[0004] The technical solution of this invention is: a method for machining slender high-precision high-temperature alloy shafts, comprising the following steps:

[0005] a. Adjust the tailstock and center rest of the CNC lathe to coincide with the rotation center of the spindle of the slender shaft to be machined;

[0006] b. Drill a center hole on the end face of the slender shaft to be machined, and use a tailstock center to hold the center hole and machine the outer diameter of the slender shaft to be machined;

[0007] c. After turning the slender shaft to be processed, repeat step b;

[0008] d. Grind the outer diameter at both ends of the slender shaft to be machined;

[0009] e. Grind the center holes on both ends of the slender shaft to be machined, whose outer diameter has been ground in step d;

[0010] f. Use PVJBL2525-M12 tool holder and VCGT110304-UM 1115 special high temperature alloy machining inserts for turning to initially remove the excess material from the slender shaft to be machined.

[0011] g. Clamp and align one end of the slender shaft that has been ground in step d on its outer diameter. After alignment, use a tailstock center to hold the other end in place. Then, use a general turning method to remove excess material a second time. Finally, finish turn the journal to complete the machining.

[0012] In step a of the aforementioned high-precision high-temperature alloy slender shaft machining method, the overlap ratio is controlled within 0.01 mm.

[0013] In the aforementioned high-precision high-temperature alloy slender shaft machining method, after steps b and c, the tool marks on the surface of the slender shaft to be machined are no greater than 0.05mm.

[0014] In step d of the aforementioned high-precision high-temperature alloy slender shaft machining method, the runout of the two ends of the slender shaft to be machined relative to the center hole after the outer diameter is ground is no more than 0.005mm.

[0015] The grinding process of step e in the aforementioned high-precision high-temperature alloy slender shaft machining method is as follows: on the center hole grinding machine, the shaft diameter and center hole are respectively ground and positioned, and the other center hole is ground; when the V-shaped frame of the center hole grinding machine is fixed, ensure that the slender shaft to be machined can rotate freely and is positioned sufficiently; rotate the part evenly during grinding to ensure grinding quality; after machining one end, machine the other end center hole in the same way.

[0016] In the aforementioned high-precision high-temperature alloy slender shaft machining method, the ground top hole is inspected by coloring, and the colored area is not less than 90% and is uninterrupted along the circumference.

[0017] In step f of the aforementioned high-precision high-temperature alloy slender shaft machining method, the two ends of the slender shaft to be machined are aligned before machining to ensure that the runout is no greater than 0.005mm.

[0018] The turning parameters for the secondary removal of allowances in step f of the aforementioned high-precision high-temperature alloy slender shaft machining method are as follows:

[0019]

[0020] In step f of the aforementioned high-precision high-temperature alloy slender shaft machining method, the parameters for precision turning are as follows:

[0021]

[0022] In the aforementioned high-precision high-temperature alloy slender shaft machining method, if the runout of the slender shaft does not meet the requirements after step f is completed, it is corrected by grinding the center hole.

[0023] The advantages of this invention are: the processing technology of this invention greatly shortens the processing cycle, requires less skill from workers, and the process is stable. After the improvement, the processing steps are reduced from the traditional 22 to 10, and the processing time is optimized from 30 working days per piece to 6 working days, increasing efficiency by 5 times. Furthermore, it requires less skill from machine tool operators, the process is stable, dimensional and runout tolerances meet the design requirements of the drawings, and the processing satisfies production needs. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the machining process requirements for slender shafts;

[0025] Figure 2 This is a schematic diagram of the structure of the slender shaft to be constructed;

[0026] Figure 3 This is a diagram illustrating the drilling of a center hole;

[0027] Figure 4 This is a schematic diagram of drilling a top hole at the other end;

[0028] Figure 5 This is a schematic diagram of the outer diameter of the two grinding wheels;

[0029] Figure 6 This is a schematic diagram of grinding the center hole;

[0030] Figure 7 This is a schematic diagram of the initial removal of excess material;

[0031] Figure 8 This is a schematic diagram of the machining of the first journal section;

[0032] Figure 9 This is a schematic diagram of the machining of the two-section journal;

[0033] Figure 10 This is a schematic diagram of the machining of three journal sections;

[0034] Figure 11 This is a schematic diagram of the machining of four journal sections;

[0035] Figure 12 This is the final step of grinding the center hole. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0037] Example 1. A method for machining a high-precision, high-temperature alloy slender shaft, taking a φ40*701 bar stock as an example, includes the following steps:

[0038] • Select a CNC lathe with a tailstock and a high-precision center rest, and adjust the center of the tailstock and center rest to coincide with the spindle rotation center, controlling the coincidence degree within 0.01.

[0039] • Lathe operator: Drill a center hole at the flat end of the lathe, and machine the outer diameter of the center hole at the tail end (e.g., ...). Figure 3 );

[0040] • Lathe work: Turn the machine around and turn the end face, drill the center hole, and turn the outer diameter (e.g., at the tail top center) Figure 4 );

[0041] • Grinding: Two grinding heads grind the outer diameter (e.g.) Figure 5 )

[0042] • Grinding the center holes: On a center hole grinding machine, grind the center holes at both ends separately, using the shaft diameter and center hole as positioning points (e.g., ...). Figure 6 When fixing the V-block, ensure it can be freely rotated by hand and is properly positioned. Wear gloves and rotate the part evenly by hand during grinding to ensure grinding quality; after machining one end, machine the center hole at the other end in the same way. After grinding, check the center hole with coloring; the colored area should be no less than 90% and continuous along the circumference.

[0043] • CNC lathe: according to Figure 7 To minimize radial force and prevent bending of the slender shaft during turning, and to reduce cutting force and improve tool life and sharpness, PVJBL2525-M12 tool holder and VCGT110304-UM 1115 special high-temperature alloy machining inserts were selected.

[0044] • CNC lathe: according to Figure 8 Processing

[0045] Insert the end with the ground outer diameter (φ23.8) into the spindle tapered hole behind the spindle chuck. The exposed length of the chuck end face should be 142±2 mm. Align the spindle within approximately 10 mm of the chuck, ensuring the runout is no greater than 0.002 mm. After alignment, use a tailstock center to hold the spindle in place. In programming, set the end face as the working coordinate system Z0. First, use a general turning method to remove excess material, leaving a 0.2 mm allowance on each side of the contour. Machining parameters are as follows:

[0046]

[0047]

[0048] Then, precision turning is performed to complete the machining process. The machining parameters are as follows:

[0049]

[0050] • CNC lathe: according to Figure 9 conduct.

[0051] • CNC lathe: according to Figure 10 conduct.

[0052] • CNC lathe: according to Figure 11 conduct.

[0053] • Grinding the center hole: After machining, if the runout of ①~⑤ does not meet the requirement of 0.013, proceed as follows Figure 12 Grinding the center hole can achieve the required runout.

[0054] The traditional processing techniques are as follows:

[0055] • Machining: Flatten the end face, ensure the total length is 688, drill the center hole, drill the center hole on the tail, machine the outer diameter to φ23, and the length is 350;

[0056] • Machining: Machin the other end face to 682.13, drill the center hole, place the center hole on the tail, machine the outer diameter to φ23, and the length to the tool-joining position. The tool-joining mark should not be greater than 0.1.

[0057] • Grinding: Grind one end's outer diameter to φ22.7, grind the end face, turn around and grind the other end to φ22.7, grind the end face, ensuring the total length is 682±0.04;

[0058] • Lathe work: Rough turning journals ④ to ③ on a conventional lathe, φ12.3 to φ13.2, and journals ③ and ④ to φ21.25;

[0059] • Lathe work: Rough turning journals ③ to ② on a conventional lathe, φ12.3 to φ13.2, and journals ② to φ21.25;

[0060] • Lathe work: Rough turning journals ② to ① on a conventional lathe, φ12.3 to φ13.2, and journals ① to φ18.6;

[0061] • Machining: Align the journal with the right-side transition arc R25;

[0062] • Machining: Align the journal with the right-side transition arc R25;

[0063] • Lathe work: Rough turn journals ④ to ⑤ on a conventional lathe, φ12.3 to φ13.2, and journals ⑤ to φ18.6;

[0064] • Grinding: Grind the Φ12.3 journal between ③④⑤ to φ13.05, journal ④ to φ21.1, and journal ⑤ to φ18.4;

[0065] • Grinding: Grind the Φ12.3 journals between ① and ②, and between ② and ③ to φ13.05; grind the journals ② and ③ to φ21.1; grind the journal ① to φ18.4.

[0066] • Lathe work: Semi-finish machining of journals ③ to ④ on a conventional lathe, journal ③ is machined to φ20.47, and journal Φ12.3 is machined to φ12.45;

[0067] • Lathe work: Semi-finish machining of journals ② to ③ using a conventional lathe; journal ② is machined to φ20.47, and journal Φ12.3 is machined to φ12.45.

[0068] • Lathe work: Semi-finish machining of journals ① and ② on a conventional lathe, journal ① is machined to φ17.85, and journal Φ12.3 is machined to φ12.45;

[0069] • Lathe work: Ordinary lathe finishes machining the right-side transition arc R25 on the journal ②;

[0070] • Lathe work: Ordinary lathe finishes machining the right-side transition arc R25 on the journal ③;

[0071] • Machining: Perform semi-finish machining on journals ④ and ⑤ using a conventional lathe. Machining journal ⑤ to φ17.85 and journal Φ12.3 to φ12.45. After machining, check that the runout of all surfaces relative to the center hole is no greater than 0.05.

[0072] • Grinding: Grind the journals between ③, ④ and ⑤, the two Φ12.3 journals to the final size, the journal ④ to φ20.39, and the journal ⑤ to the final size φ17.7; the surface runout relative to the center hole after grinding is 0.02.

[0073] • Grinding: Grind the journals between ①②③, the two Φ12.3 journals to the final size, the journals ②③ to φ20.39, and the journal ① to φ17.7; the surface runout relative to the center hole after grinding is 0.02.

[0074] • Machining: Tool marks at the polished corners of ordinary lathes;

[0075] • Grinding: Fine grind journals ④ and ⑤ to the final dimensions, ensuring a runout of 0.013 for the center hole;

[0076] • Grinding: Fine grind journals ①②③ to the final dimensions, ensuring a runout of 0.013 for the center hole;

[0077] The process is very complex, with extremely strict requirements for intermediate process control. A single part requires 22 steps and up to 30 working days to complete the processing.

[0078] The above comparison shows that after adopting the process of this invention, the number of processes is reduced from 22 to 10, the processing time is optimized from 30 working days per piece to 6 working days, the efficiency is increased by 5 times, the requirements for machine tool operators are low, the process is stable, the dimensions and runout tolerances meet the design requirements of the drawings, and the processing meets the production needs.

Claims

1. A method for machining slender shafts of high-precision high-temperature alloys, characterized in that: Includes the following steps: a. Adjust the tailstock and center rest of the CNC lathe to coincide with the rotation center of the spindle of the slender shaft to be machined, and control the coincidence degree within 0.01mm; b. Drill a center hole on the end face of the slender shaft to be machined, and use a tailstock center to hold the center hole and machine the outer diameter of the slender shaft to be machined; c. After turning the slender shaft to be machined, repeat step b; after turning, the tool marks on the surface of the slender shaft to be machined should not be greater than 0.05mm; d. Grind the outer diameter of both ends of the slender shaft to be machined. After grinding the outer diameter, the runout of both ends of the slender shaft to be machined relative to the center hole should not exceed 0.005mm. e. Grind the center holes on both ends of the slender shaft to be machined, whose outer diameter has been ground in step d; f. Use PVJBL2525-M12 tool holder and VCGT110304-UM 1115 special high-temperature alloy machining inserts for turning to initially remove the excess material from the slender shaft to be machined; before machining, align both ends of the slender shaft to be machined so that the runout is no more than 0.005mm. g. Clamp and align one end of the slender shaft that has been ground in step d on its outer diameter. After alignment, use a tailstock center to hold the other end in place. Then, use a general turning method to remove excess material a second time. Finally, finish turn the journal to complete the machining.

2. The method for machining slender high-precision high-temperature alloy shafts according to claim 1, characterized in that: The grinding process in step e is as follows: On the center hole grinding machine, the shaft diameter and center hole are positioned separately, and the other center hole is ground; when the V-block of the center hole grinding machine is fixed, ensure that the slender shaft to be processed can rotate freely and is positioned sufficiently; rotate the part evenly during grinding to ensure grinding quality; after processing one end, process the other end center hole in the same way.

3. The method for machining slender high-precision high-temperature alloy shafts according to claim 2, characterized in that: After grinding, the top hole is inspected by dyeing, and the dyed area is not less than 90% and is uninterrupted along the circumference.

4. The method for machining slender high-precision high-temperature alloy shafts according to claim 1, characterized in that: In step f, the turning parameters for the second removal of allowance are as follows: 。 5. The method for machining slender high-precision high-temperature alloy shafts according to claim 1, characterized in that: In step f, the parameter table for precision machining is as follows: 。 6. The method for machining slender high-precision high-temperature alloy shafts according to claim 1, characterized in that: If the runout of the slender shaft does not meet the requirements after step f is completed, it can be corrected by grinding the center hole.

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