A precision end slot turning method for a nickel-based superalloy

Abstract

The present application relates to a kind of nickel-based superalloy precision end slot turning processing method.The present application includes providing special tool and general tool;Turbine disk long axis end is divided into end surface area, outer diameter area, outer diameter slot area, inner diameter area, end surface slot area and inner diameter slot area;Special tool and general tool are used in sequence according to above-mentioned order to carry out rough machining;After rough machining is completed, special tool and general tool are used in sequence according to above-mentioned order to carry out finish machining;Special tool is used to the end surface slot area is rough machined and finished machined;Using external turning tool to the end surface area and outer diameter area is rough machined and finished machined;Using first external slotting tool to the outer diameter slot area is rough machined and finished machined;Using second external slotting tool to the outer diameter slot area is rough machined and finished machined;Using internal turning tool to the inner diameter area is rough machined and finished machined;Using internal slotting tool to the inner diameter slot area is rough machined and finished machined.The present application improves the stability of processing quality and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of aero-engine manufacturing technology, and in particular to a method for precision end-groove machining of nickel-based superalloys. Background Technology

[0002] Turbine disks are core load-bearing rotating components of aero engines and gas turbines, operating under extreme conditions of high temperature, high pressure, and high speed. This places stringent requirements on the high-temperature strength, creep resistance, and oxidation resistance of the materials used. Nickel-based superalloys, possessing these excellent properties, have become the preferred material for turbine disk manufacturing. However, nickel-based superalloys are also typical difficult-to-machine materials, exhibiting high hardness, high strength, low thermal conductivity, and a strong tendency for work hardening, posing numerous technical challenges to CNC turning.

[0003] In the turning of turbine disks, the narrow end groove (groove width 12mm, depth 15-30mm) at the long shaft end is a difficult part of the machining process. Traditional machining uses general-purpose end-face grooving tools, but due to the limitations of the tool structure design, a series of problems are exposed during the machining process: First, the tool rigidity is insufficient. The tool holder is a single support structure, which easily causes tool deflection under the action of cutting force, resulting in low end groove profile accuracy. The measured profile is generally 0.06-0.15mm, with an error rate of up to 80%, requiring 3-5 manual reworks to meet the design requirements. Second, the tool has poor clearance capability. Traditional tool heads are large, and the minimum clearance between the head side and the workpiece groove wall is only 0.3mm. During machining, interference and collision between the tool and the workpiece are easily caused by cutting vibration. Third, the cutting parameters are poorly adapted to the groove shape. The cutting edge angle is not reasonably designed, the cutting resistance is high, and the chip removal space is insufficient, which easily causes chip accumulation. Moreover, the tool vibration causes obvious surface texture on the workpiece, with a surface roughness Ra>3.2μm, which cannot meet the requirements of precision assembly.

[0004] Meanwhile, existing turning methods for nickel-based superalloy turbine disks lack systematic process planning, have no clear specifications for the machining sequence, rely on experience in selecting roughing and finishing parameters, and lack effective process monitoring and compensation mechanisms. On the one hand, the machining area planning is chaotic and does not follow the stress release law, resulting in concentrated internal stress and large deformation of the workpiece after machining, and uneven distribution of subsequent finishing allowance. On the other hand, the roughing and finishing toolpath strategies are simplistic, mostly using unidirectional linear cutting. Sudden changes in cutting force can easily aggravate tool vibration and workpiece deformation. Furthermore, there is no online measurement link after key processes, resulting in delayed tool compensation. In mass production, the consistency of part dimensions is poor, and the machining qualification rate is only about 20%. In addition, there are no clear standards for the matching and use of special tools and general tools in traditional machining. Tool selection is arbitrary, which further reduces machining efficiency and accuracy, resulting in long turbine disk machining cycles and high costs, which cannot meet the urgent needs of the aero-engine manufacturing industry for efficient and high-precision manufacturing of core components.

[0005] To address the aforementioned issues, existing technologies mostly improve the process from a single dimension, either by simply optimizing tool cutting parameters or adjusting the machining sequence. They fail to achieve synergistic optimization of tool structure and machining methods, making it difficult to fundamentally solve the core problems of interference, tool deflection, low precision, and poor efficiency in machining narrow end slots of nickel-based superalloy turbine disks. Therefore, it is urgent to design a special tool suitable for machining narrow end slots and to develop a systematic and high-precision turbine disk turning method that matches it. Summary of the Invention

[0006] To address this, the present invention provides a method for precision end-groove turning of nickel-based superalloys. By combining customized optimization of the tool structure with systematic planning of the machining method, this method solves the problems of insufficient tool rigidity, machining interference, tool deformation, low precision, and poor efficiency in traditional machining. It enables precision, high efficiency, and batch turning of nickel-based superalloy turbine disks, especially narrow end-grooves, thereby improving machining quality stability and production efficiency, and reducing machining costs.

[0007] To solve the above technical problems, the present invention provides a method for precision end-groove machining of nickel-based superalloys, comprising: Special-purpose cutting tools and general-purpose cutting tools are provided. The special-purpose cutting tools include a connected cutting head and a cutting shank. The cutting head has a flat structure, with one end of the cutting head having a thickness of 7.6-7.8 mm and the other end having a thickness of 10-12 mm. The back of the cutting head has a 26-28° conical bevel clearance structure. The cutting edge inclination angle towards the cutting shank is -4° to -2°. The rake angle of the cutting edge of the cutting blade on the cutting head is 4-6°, the clearance angle is 7-9°, the radius of the cutting tip arc is R0.2-R0.8, and the minimum clearance between the side of the cutting head and the workpiece groove wall is 1.1-1.3 mm. The general-purpose cutting tools include external turning tools, first external grooving tools, second external grooving tools, end face grooving tools, internal turning tools, and internal grooving tools. The long shaft end of the turbine disk is divided into the end face region, outer diameter region, outer diameter groove region, inner diameter region, end face groove region, and inner diameter groove region. The special-purpose tool and the general-purpose tool are used to perform roughing in the above order. The cutting parameters for roughing are: linear speed 45-55 m / min, feed rate 0.10-0.14 mm / rev, depth of cut 0.8-1.2 mm, and the roughing process uses a constant depth of cut contour following the toolpath. After roughing, the reserved machining allowance is 0.3-0.6 mm. After roughing is completed, the special tool and the general tool are used to perform finishing in the above order. The cutting parameters for finishing are: linear speed 30-150 m / min, feed rate 0.08-0.12 mm / rev, and finishing allowance controlled at 0.3-0.5 mm. When the blank allowance is greater than 1.0-1.2 mm, pre-machining is performed to remove part of the allowance before finishing. The end face groove area is roughed and finished using the end face grooving tool and a special tool. The external turning tool is used to perform roughing and finishing on the end face area and the outer diameter area; The outer diameter groove area is roughed and finished using the first outer circular groove cutter. The second external grooving cutter is used to perform roughing and finishing on the outer diameter groove area; The inner diameter region is roughed and finished using the aforementioned internal turning tool. The inner diameter groove area is roughed and finished using the aforementioned inner grooving cutter.

[0008] In one embodiment of the present invention, the tool holder is a square shank tool holder.

[0009] In one embodiment of the present invention, the tool holder is made of 40CrNiMoA alloy material with a hardness of HRC35-40.

[0010] In one embodiment of the present invention, the tool holder and the tool post are connected by a right-angle surface fit, and the contact area between the two is not less than 250mm². In one embodiment of the present invention, the cutting head and the cutting shank are integrally formed.

[0011] In one embodiment of the present invention, when finishing the end face groove area, a layered circumferential cutting and contour finishing strategy is adopted. The layered circumferential cutting is to remove the excess material layer by layer in the depth direction of the end face groove area, with each layer having a cutting depth of no more than 0.5 mm. The contour finishing is performed after the layered circumferential cutting is completed, and the finishing tool uses a unidirectional continuous tool path to avoid machining errors caused by repeated tool paths.

[0012] The technical solution of the present invention has the following advantages compared with the prior art: 1) Significantly Improved Tool Performance: The dedicated tool of this invention adopts a flat and compact tool head structure, combined with a conical clearance design, giving the tool better spatial adaptability during narrow end-groove machining and effectively reducing the risk of interference between the tool head and the groove wall. Simultaneously, the tool shank is made of 40CrNiMoA alloy material, improving the overall rigidity of the tool from both structural design and material performance perspectives. Verification shows that the tool rigidity is increased by approximately 80% compared to traditional solutions. Under a radial cutting force of 150N, the maximum deflection is only 0.04mm, and the vibration amplitude can be controlled within 0.01mm, thus significantly suppressing tool deflection during machining and ensuring the stable posture of the tool throughout the entire cutting process. Based on the above structural optimization, the fit between the tool cutting path and the end-groove profile is no less than 98%, providing a reliable guarantee for high-precision end-groove machining.

[0013] 2) Significantly Improved Machining Accuracy: This invention significantly improves the machining accuracy of the end grooves of nickel-based high-temperature alloy turbine disks by specifically optimizing the structural parameters of the dedicated cutting tools, combining a machining sequence planning from the outside to the inside, surface-first and cavity-later, a constant depth-of-cut contour-following roughing strategy, and a layered circumferential cutting and contour finishing strategy for the end grooves. The profile of the machined end groove can be stably controlled within 0.02mm, an improvement of approximately 70% to 87% compared to traditional processes; the surface roughness can be controlled below Ra1.6μm, effectively eliminating surface defects such as vibration marks; the machining pass rate increases from approximately 20% to over 95%, and the dimensional variation of key parts is reduced to within ±0.02mm, meeting the stringent requirements of precision assembly for dimensional accuracy and surface quality.

[0014] 3) Significantly Improved Production Efficiency: This invention achieves one-time machining of the end groove through the synergistic combination of specialized cutting tools and regionalized machining methods, avoiding the multiple rework issues caused by tool deflection, interference, and insufficient precision in traditional machining. Compared with traditional processes, the machining time for each region of the turbine disk's long shaft end is significantly reduced. Specifically, the simulation time for outer diameter machining is reduced from 56 minutes and 47 seconds to 21 minutes and 7 seconds, the simulation time for end face groove machining is reduced from 42 minutes and 2 seconds to 10 minutes and 42 seconds, and the simulation time for inner diameter machining is reduced from 45 minutes and 7 seconds to 22 minutes and 3 seconds. The machining cycle for a single workpiece can be reduced to approximately 40% of that of traditional processes, and the effective machining time of the equipment increases from 40% to 85%.

[0015] 4) Effectively Reduced Processing Costs: Because this invention significantly improves the machining accuracy of end slots and reduces rework, it effectively controls the tool wear, raw material waste, and manual rework costs caused by repeated finishing in traditional processes. The near-complete elimination of rework not only reduces tool consumption but also reduces raw material waste due to rework by approximately 30 kg per month, while simultaneously reducing the time spent by quality control and rework personnel. Furthermore, the increased overall rigidity of the specialized cutting tools helps extend tool life, reducing tool and labor costs per unit, thus resulting in excellent overall economic benefits.

[0016] 5) Strong operability and versatility: This invention clearly divides the machining areas of the turbine disk's long shaft end and systematically designs and quantifies the roughing parameters, finishing parameters, toolpath strategies, and tool matching relationships. This makes the entire machining process highly operable and repeatable, reducing reliance on operator experience. The specialized tools are suitable for machining narrow end grooves with a width of 12mm and a depth of 15-30mm. Furthermore, this machining method can also be extended to the machining of precision parts with similar narrow spaces and high precision requirements, such as hydraulic valve core ring grooves and aero-engine casings, demonstrating strong engineering promotion value and application prospects. Attached Figure Description

[0017] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the machining area of ​​the outer diameter of the long shaft end of the turbine disk, where A, B, and C are the end face areas, D, E, and F are the outer diameter areas, and G and H are the outer diameter groove areas.

[0019] Figure 2 This is a schematic diagram of the toolpath planning for the machining area of ​​the outer diameter of the long shaft end of the turbine disk. Red represents the retraction trajectory, and green represents the feed path.

[0020] Figure 3 This is a schematic diagram of the machining area I on the end face groove of the long shaft of the turbine disk.

[0021] Figure 4 This is a schematic diagram of the tool path planning for the end face groove machining area of ​​the turbine disk long shaft end face groove. Red represents the tool infeed trajectory, and green represents the cut-off area.

[0022] Figure 5 This is a schematic diagram of the tool path planning for the special tool for machining the end face groove of the turbine disk long shaft. Red represents the tool entry trajectory, and green represents the area to be removed.

[0023] Figure 6 This is a schematic diagram of the machining area of ​​the inner diameter at the long shaft end of the turbine disk, where J is the inner diameter area and K is the inner diameter groove area.

[0024] Figure 7 This is a schematic diagram of the toolpath planning for the machining area of ​​the inner diameter of the long shaft end of the turbine disk. Red represents the infeed trajectory, and green represents the cut-off area.

[0025] Figure 8 This is a schematic diagram of the structure of an external turning tool.

[0026] Figure 9 This is a schematic diagram of the first outer circular groove tool structure.

[0027] Figure 10 This is a schematic diagram of the second outer circular groove tool structure.

[0028] Figure 11 This is a schematic diagram of the end face grooving tool structure.

[0029] Figure 12 This is a top view of the special cutting tool of this invention.

[0030] Figure 13 This is a schematic diagram of the main structure of the special cutting tool of this invention.

[0031] Figure 14 This is a schematic diagram of an internal turning tool.

[0032] Figure 15This is a schematic diagram of an internal turning tool. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0034] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0035] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0036] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0037] Example 1 Reference Figure 1 , Figures 8 to 15 As shown, this embodiment provides a method for precision turning of end grooves in nickel-based superalloys, used for precision turning of the long shaft end region of a nickel-based superalloy turbine disk for a certain type of aero-engine. The machining equipment is a CNC lathe, equipped with an online measuring device. The turbine disk blank material is a nickel-based superalloy, and the long shaft end has multiple regions including the end face to be machined, outer diameter, outer diameter groove, inner diameter, end face groove, and inner diameter groove. The method is suitable for narrow end grooves in the long shaft end region of nickel-based superalloy turbine disks with a groove width of 12mm and a depth of 15-30mm. The method includes the following steps: S1. Provide special-purpose cutting tools and general-purpose cutting tools. The special-purpose cutting tool includes a connected cutting head and a cutting shank, which are integrally formed. By designing the cutting head and cutting shank as an integral structure, the stiffness reduction at the connection transition can be reduced, the deflection under cutting load can be reduced, and the posture stability of the tool during cutting in narrow end grooves can be improved, thereby helping to suppress tool deflection.

[0038] The cutting head has a flat structure, with one end of the head having a thickness of 7.6–7.8 mm, preferably 7.7 mm, and the other end having a thickness of 10–12 mm, preferably 11 mm. The back of the cutting head has a tapered bevel structure with a clearance of 26–28°, preferably 27°. The cutting edge inclination angle towards the tool shank is -4° to -2°, preferably -3°; the rake angle of the tapered cutting edge of the cutting blade is 4–6°, preferably 5°; the clearance angle is 7–9°, preferably 8°; and the tip radius is R0.2–R0.8, preferably R0.4. The minimum clearance between the side of the cutting head and the workpiece groove wall is 1.1–1.3 mm, preferably 1.2 mm.

[0039] By combining the above geometric parameters, the cutter head has both a smaller front end thickness to improve obstacle avoidance capability and a larger rear end thickness to ensure sufficient rigidity; the conical bevel clearance structure can reduce the probability of interference between the back of the cutter head and the adjacent areas of the groove wall and bottom; appropriate negative cutting edge inclination angle, rake angle, clearance angle and cutting tip radius are beneficial to balance cutting sharpness, cutting edge strength, chip removal capability and end groove contour forming accuracy.

[0040] The tool holder is a square shank tool holder, preferably a 20×20 square shank 90° right-hand precision turning tool holder, with an overall length preferably of 125mm. The tool holder is made of 40CrNiMoA alloy material with a hardness of HRC35~40. The tool holder and the tool post are connected by a right-angle surface fit, and the contact area between the two is not less than 250mm². This structure and material combination can improve the bending and torsional resistance of the tool holder, expand the stress support area between it and the tool post, reduce local contact deformation, and help improve cutting stability and repeatability accuracy.

[0041] The tapered and compact structure of the cutter head is suitable for machining narrow end grooves of nickel-based high-temperature alloy turbine disks with a groove width of 12mm and a depth of 15-30mm.

[0042] The specialized cutting tool features a flat and compact tip structure combined with a conical clearance design, providing better spatial adaptability during the machining of narrow end grooves and effectively reducing the risk of interference between the tip and the groove wall. Simultaneously, the tool shank is made of 40CrNiMoA alloy, enhancing the overall rigidity of the tool through both structural design and material properties. Verification shows that the tool rigidity is approximately 80% higher than traditional solutions. Under a radial cutting force of 150N, the maximum deflection is only 0.04mm, and the vibration amplitude can be controlled within 0.01mm, significantly suppressing tool deflection during machining and ensuring stable tool posture throughout the entire cutting process. Based on these structural optimizations, the fit between the tool cutting path and the end groove profile is no less than 98%, providing a reliable guarantee for high-precision end groove machining.

[0043] The general-purpose cutting tools include external turning tools, first external grooving tools, second external grooving tools, end-face grooving tools, internal turning tools, and internal grooving tools. In actual machining, the external turning tools are used for roughing and finishing of the end-face areas (A, B, C) and the outer diameter areas (D, E, F); the first external grooving tool is used for roughing and finishing of the outer diameter groove area (G); the second external grooving tool is used for roughing and finishing of the outer diameter groove area (H); the internal turning tools are used for roughing and finishing of the inner diameter area (J); the internal grooving tools are used for roughing and finishing of the inner diameter groove area (K); and the end-face grooving tools and special-purpose tools are used for roughing and finishing of the end-face groove area (I).

[0044] Mount the special-purpose cutting tool onto the CNC lathe tool post and adjust the tool installation accuracy to ensure that the coaxiality error between the tool tip and the workpiece rotation center is controlled within 0.01mm. At the same time, check the fit between the tool holder and the tool post to ensure that there are no obvious gaps or warping on the contact surfaces. Then, assemble the aforementioned general-purpose cutting tools into their corresponding tool positions to complete the preparation of all cutting tools.

[0045] S2. Based on the structural characteristics of the long shaft end of the turbine disk, the long shaft end is divided into end face area (A, B, C), outer diameter area (D, E, F), outer diameter groove area (G, H), inner diameter area (J), end face groove area (I), and inner diameter groove area (K). Machining is performed from the outside in, and from the surface to the cavity; that is, the outermost areas and planar reference areas are completed first, and then the groove and cavity areas are gradually transitioned to.

[0046] By adopting the above processing sequence, on the one hand, the residual stress and initial internal stress formed during the workpiece cutting process can be gradually released, avoiding the local warping or dimensional drift caused by internal stress concentration; on the other hand, a relatively stable external process reference can be established first, and then the groove and inner diameter can be processed step by step, which is conducive to improving the positional accuracy and dimensional consistency between different areas.

[0047] S3. Reference Figures 2 to 7As shown, roughing is performed sequentially using the aforementioned general-purpose tool in the above order. Roughing employs a constant depth-of-cut contour-following toolpath. A constant depth-of-cut contour-following toolpath means that the tool approaches the target contour in layers or in stages, keeping the single cutting load within a relatively stable range, thereby avoiding drastic fluctuations in radial cutting force caused by sudden changes in the toolpath.

[0048] In this embodiment, the roughing cutting parameters are set as follows: linear speed 45–55 m / min, preferably 50 m / min; feed rate 0.10–0.14 mm / rev, preferably 0.12 mm / rev; depth of cut 0.8–1.2 mm, preferably 1.0 mm. After roughing, the reserved machining allowance is between 0.3 and 0.6 mm, preferably 0.5 mm.

[0049] The aforementioned roughing parameters, combined with the toolpath strategy, enable the tool to achieve a balance between cutting efficiency and tool load stability when machining nickel-based superalloys. Using a more stable depth of cut and feed rate helps reduce vibration, mitigate the adverse effects of work hardening, and provide a uniform and controllable allowance distribution for subsequent finishing.

[0050] S4. After rough machining is completed, the special tool and the general tool are used to perform finishing in the above order.

[0051] The end face groove area (I) is finished using the aforementioned end face grooving cutter and special tool. During the finishing of the end face groove area (I), a layered circumferential cutting and contour finishing strategy is employed. The layered circumferential cutting involves removing excess material layer by layer along the depth direction of the end face groove area (I), with each layer having a cutting depth of no more than 0.5 mm, preferably 0.3–0.5 mm, and more preferably 0.4 mm. After the layered circumferential cutting is completed, contour finishing is performed. The finishing tool uses a unidirectional continuous tool path to reduce the reverse force changes and local extrusion deformation caused by repeated tool paths. Simultaneously, the tool retraction path is optimized to ensure that the tool avoids sensitive parts of the groove wall as much as possible when exiting the machining area, thereby preventing the tool from rubbing against the workpiece.

[0052] The finishing cutting parameters are set as follows: linear speed 30–150 m / min, preferably 60–100 m / min, more preferably about 80 m / min; feed rate 0.08–0.12 mm / rev, preferably 0.10 mm / rev. The finishing allowance is controlled between 0.3 and 0.5 mm; when the blank allowance is greater than 1.0–1.2 mm, pre-machining is performed first to remove part of the allowance before finishing.

[0053] The end face groove area (I) is roughed and finished using end face grooving cutters and special tools, such as... Figure 4 and Figure 5The images show the toolpath paths for the end face grooving cutter and the special tool, respectively. The end face grooving cutter mainly processes the lower half of the end face grooving area (I), while the special tool mainly processes the upper half of the end face grooving area (I).

[0054] By employing the aforementioned strategy of combining layered circumferential cutting with contour finishing, the end face groove region (I) can remain in a relatively stable material removal state throughout the finishing process. Layered circumferential cutting helps to gradually reduce the cutting load, minimizing vibration and heat accumulation caused by a large depth of cut in a single step; unidirectional continuous finishing helps to ensure contour consistency and surface quality. Pre-machining workpieces with abnormally large blank allowances can avoid bearing excessive material removal during the finishing stage, thereby further improving dimensional control and surface integrity.

[0055] For the end face areas (A, B, C) and outer diameter areas (D, E, F), external turning tools are used for roughing and finishing. For the outer diameter groove area (G), a first external grooving tool is used for roughing and finishing. For the outer diameter groove area (H), a second external grooving tool is used for roughing and finishing. For the inner diameter area (J), an internal turning tool is used for roughing and finishing. For the inner diameter groove area (K), an internal grooving tool is used for roughing and finishing. By matching tool types according to the area, various tools can work under their most suitable geometric and stress conditions, improving overall machining efficiency and the forming quality of each area.

[0056] S5. After roughing and finishing, online measurement points are set up respectively. The contour, groove width, and other dimensional data of the end face groove area (I) are collected in real time using an online measurement device. The measurement data is then imported into the control system for statistical analysis to construct a tool deflection compensation library. The tool compensation value is then fine-tuned using the tool deflection compensation library.

[0057] Through the aforementioned online measurement and feedforward compensation mechanism, the tool compensation value can be corrected based on the actual cutting deviation obtained before the start of the next machining cycle. Compared with the traditional method that relies on manual experience and rework afterward, this method can more promptly correct dimensional deviations caused by factors such as tool elastic deformation, tool tip wear, and material batch differences, thereby improving the consistency and stability of batch processing.

[0058] By employing the dedicated tool structure, tool matching relationship, machining sequence, roughing and finishing parameters, and compensation strategy of this embodiment, the end face groove region (I) can achieve relatively stable one-time precision forming, significantly reducing tool deflection, interference, and vibration phenomena. The profile of the machined end face groove can be stably controlled to no higher than 0.02mm, the surface roughness Ra can be controlled to below 1.6μm, and the machining pass rate can be increased to over 95%. Compared with direct machining with traditional general-purpose end face groove tools, this embodiment shows significant advantages in end face groove profile accuracy, surface quality, machining efficiency, and rework control, and can meet the high-precision batch machining requirements of narrow end face grooves on the long shaft end of nickel-based high-temperature alloy turbine disks for aero-engines.

[0059] Example 2 This embodiment takes the precision turning of the long shaft end of a nickel-based superalloy turbine disk for a certain type of aero-engine as an example. The turbine disk blank is made of nickel-based superalloy, with a single-sided allowance of 2mm. The machining equipment is a CNC lathe equipped with an online measuring device. The narrow end groove to be machined has a width of 12mm and a depth of 18mm in this specific machining test. The design requirements are that the end groove profile is no greater than 0.02mm and the surface roughness Ra is no greater than 1.6μm.

[0060] In this embodiment, the cutting tool and the tool holder are integrally formed. The cutting tool has a flat structure, with a thickness of 7.7 mm at one end and 11 mm at the other. A 27° tapered bevel is provided on the back of the cutting tool to create a clearance structure. The cutting edge inclination angle towards the tool holder is -3°. The rake angle of the cutting edge on the cutting tool is 5°, the clearance angle is 8°, the tip radius is R0.4, and the minimum clearance between the side of the cutting tool head and the workpiece groove wall is 1.2 mm.

[0061] The tool holder is a 20×20 square shank 90° right-hand precision turning tool holder with an overall length of 125mm. The tool holder is made of 40CrNiMoA alloy material with a hardness of HRC35~40. The tool holder and tool post are connected by a right-angle surface fit, with a contact area of ​​over 250mm². Through this specific structural parameter configuration, the tool in this embodiment exhibits high overall rigidity and good clearance capability, without significant interference or abnormal vibration when cutting into the deep part of a narrow end groove.

[0062] Assemble the special-purpose cutting tool onto the CNC lathe tool post, adjust the tool installation accuracy to ensure that the coaxiality error between the tool tip and the workpiece rotation center is no greater than 0.01mm, and check the fit between the tool holder and the tool post to ensure there is no gap. Simultaneously, assemble the general-purpose cutting tools corresponding to each area into their respective tool positions. Specifically, the external turning tool is used to machine the end face areas (A, B, C) and the outer diameter areas (D, E, F); the first external grooving tool is used to machine the outer diameter groove area (G); the second external grooving tool is used to machine the outer diameter groove area (H); the internal turning tool is used to machine the inner diameter area (J); the internal grooving tool is used to machine the inner diameter groove area (K); and the special-purpose cutting tool is used to machine the end face groove area (I).

[0063] In this embodiment, the external turning tool is model DWLNL-2525M08; the first external grooving tool is model RF123T06-2525BM; the second external grooving tool is model HGHL-25-4A34; the end face grooving tool is model GFHL25-100-4T25; the internal turning tool is model A25R SVUNL-12; and the internal grooving tool is model GEHIR 16-20-3-T8.

[0064] Based on the structural characteristics of the long shaft end of the turbine disk, following the cutting principle of from the outside to the inside and from the surface to the cavity, its machining area is divided into end face area (A, B, C), outer diameter area (D, E, F), outer diameter groove area (G, H), inner diameter area (J), end face groove area (I), and inner diameter groove area (K), and machining is carried out in the above order.

[0065] In the roughing stage, dedicated or general-purpose tools corresponding to each area are used sequentially in the order described above. Roughing employs a constant depth of cut contour following the toolpath to avoid sudden changes in radial cutting force. The specific roughing cutting parameters are set as follows: linear speed 50 m / min, feed rate 0.12 mm / rev, depth of cut 1 mm. After roughing, a finishing allowance of 0.5 mm is reserved.

[0066] In the specific test of this embodiment, the toolpath length for machining the outer diameter region was 878.08 mm, the simulated machining time was 21 minutes and 7 seconds, and the actual machining time was 22 minutes and 10 seconds; the toolpath length for machining the inner diameter region was 904.38 mm, the simulated machining time was 22 minutes and 3 seconds, and the actual machining time was 23 minutes and 5 seconds. After rough machining, no obvious machining deformation or tool interference was observed in any of the machining areas.

[0067] After rough machining is completed, finishing machining is performed sequentially using the corresponding tools in the order described above. Specifically, the end face groove area (I) is finished using an end face grooving tool and the special tool of this invention, while the remaining areas are finished using the corresponding general-purpose tools.

[0068] The finishing of the end face groove area (I) employs a combination of layered circumferential cutting and contour finishing. The excess material is removed layer by layer along the groove depth direction, with each layer having a cutting depth of 0.4 mm. After the layered circumferential cutting is completed, contour finishing is performed. The finishing tool path uses a unidirectional continuous feed, while optimizing the tool retraction path to avoid interference between the tool and the groove wall. The finishing cutting parameters are set as follows: linear speed 80 m / min, feed rate 0.10 mm / rev, and finishing allowance controlled at 0.5 mm. In this embodiment, since the allowance is relatively uniformly distributed after roughing, no additional pre-machining is required.

[0069] In the specific test of this embodiment, the machining toolpath length for the end face groove area (I) was 221.015 mm, the simulated machining time was 7 minutes and 29 seconds, and the actual machining time was 8 minutes and 15 seconds. No vibration occurred during the machining process, the chips were discharged smoothly, and there was no obvious accumulation or blockage of chips.

[0070] After rough machining and finish machining are completed, online measurement points are set up respectively, and the contour and groove width data of the end face groove area (I) are collected in real time by online measurement device.

[0071] The measurement results after rough machining are as follows: the actual width of the end groove is 11.98 mm, and the profile is 0.045 mm. Based on the analysis results of the tool deflection compensation library, the tool compensation value is finely adjusted by +0.02 mm feedforward.

[0072] The measurement results after finishing are as follows: the actual width of the end groove is 12.002mm, and the contour is 0.018mm, which meets the design requirements and does not require rework.

[0073] Statistical analysis was performed on the processing results of this embodiment, and compared with traditional processing methods, as shown in Table 1. The results show that, using the special tool and processing method of this invention, the end groove profile can be improved from 0.06–0.15 mm in traditional processing to no more than 0.02 mm, the surface roughness Ra can be improved from more than 3.2 μm to less than 1.6 μm, the actual processing time for the outer diameter is shortened to 22 minutes and 10 seconds, the actual processing time for the end face groove is shortened to 8 minutes and 15 seconds, the actual processing time for the inner diameter is shortened to 23 minutes and 5 seconds, and the number of reworks is reduced from 2–3 times / piece in the traditional method to 0 times / piece. The test results show that the special tool and processing method of this invention work synergistically to fully meet the design and processing requirements of a certain type of aero-engine nickel-based high-temperature alloy turbine disk. The end groove processing accuracy, surface quality, and production efficiency are all significantly improved, while effectively reducing tool consumption and processing costs. Batch processing exhibits strong stability with no significant dimensional fluctuations.

[0074] Table 1 Comparison of processing results between traditional processing methods and the processing method of this invention

[0075] Therefore, this embodiment, through the synergistic cooperation of dedicated tool structure optimization, regionalized machining sequence, constant depth of cut contour following roughing strategy, end face groove layered circumferential cutting and contour finishing strategy, and online measurement and tool deflection compensation library feedforward fine adjustment mechanism, can significantly improve the machining accuracy, surface quality and production efficiency of narrow end grooves on the long shaft end of nickel-based superalloy turbine disks, and reduce rework rate and machining cost, and has good engineering application value and batch machining stability.

[0076] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for precision turning of end grooves in nickel-based superalloys, characterized in that, include: Special-purpose cutting tools and general-purpose cutting tools are provided. The special-purpose cutting tools include a connected cutting head and a cutting shank. The cutting head has a flat structure, with a thickness of 7.6-7.8 mm at one end and 10-12 mm at the other end. The back of the cutting head has a 26-28° conical bevel clearance structure. The cutting edge inclination angle towards the cutting shank is -4° to -2°. The rake angle of the cutting edge of the cutting blade on the cutting head is 4-6°, the clearance angle is 7-9°, the radius of the cutting tip arc is R0.3-R0.5, and the minimum clearance between the side of the cutting head and the workpiece groove wall is 1.1-1.3 mm. The general-purpose cutting tools include external turning tools, first external grooving tools, second external grooving tools, end face grooving tools, internal turning tools, and internal grooving tools. The long shaft end of the turbine disk is divided into end face region (A, B, C), outer diameter region (D, E, F), outer diameter groove region (G, H), inner diameter region (J), end face groove region (I), and inner diameter groove region (K). The special-purpose tool and the general-purpose tool are used to perform roughing in the above order. The cutting parameters for roughing are: linear speed 45-55 m / min, feed rate 0.10-0.14 mm / rev, depth of cut 0.8-1.2 mm, and the roughing process uses a constant depth of cut contour following the toolpath. After roughing, the reserved machining allowance is 0.3-0.6 mm. After roughing is completed, the special tool and the general tool are used to perform finishing in the above order. The cutting parameters for finishing are: linear speed 30-150 m / min, feed rate 0.08-0.12 mm / rev, and finishing allowance controlled at 0.3-0.5 mm. When the blank allowance is greater than 1.0-1.2 mm, pre-machining is performed to remove part of the allowance before finishing. The end face groove area (I) is roughed and finished using the end face grooving cutter and special cutting tool. The external turning tool is used to perform roughing and finishing on the end face areas (A, B, C) and the outer diameter areas (D, E, F); The outer diameter groove region (G) is roughed and finished using the first outer circular groove cutter; The second external grooving tool is used to perform roughing and finishing on the outer diameter groove area (H); The inner diameter region (J) is roughed and finished using the aforementioned internal turning tool; The inner diameter groove area (K) is roughed and finished using the inner grooving cutter.

2. The method for precision turning of nickel-based superalloy end grooves according to claim 1, characterized in that, The tool holder is a square shank tool holder.

3. The method for precision turning of nickel-based superalloy end grooves according to claim 1, characterized in that, The tool holder is made of 40CrNiMoA alloy material with a hardness of HRC35-40.

4. The method for precision turning of nickel-based superalloy end grooves according to claim 1, characterized in that, The tool holder and the tool post are connected by a right-angle surface fit, and the contact area between the two is not less than 250mm².

5. The method for precision turning of end grooves in nickel-based superalloys according to claim 1, characterized in that, The cutter head and the cutter shank are integrally formed.

6. The method for precision turning of nickel-based superalloy end grooves according to claim 1, characterized in that, When finishing the end face groove area (I), a layered circumferential cutting and contour finishing strategy is adopted. The layered circumferential cutting is to remove the excess material layer by layer in the depth direction of the end face groove area (I), and the cutting depth of each layer is no more than 0.5mm. The contour finishing is performed after the layered circumferential cutting is completed. The finishing tool uses a unidirectional continuous tool path to avoid repeated tool path and machining errors.

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