A method for processing a stepped hole of a thin-walled structure of a high-temperature alloy

Abstract

The application provides a high-temperature alloy thin-wall structure step hole machining method, general tools are selected for processing in batches, and the tool life is improved by reducing the cutting layer thickness of single feeding through multiple cutting. In the parameter selection aspect, the existing general tool recommended cutting parameters can be referred for adjustment, so that the cost increase and cycle extension caused by parameter test are avoided.

Description

Technical Field

[0001] This application belongs to the field of cutting and machining technology, and in particular relates to a method for machining stepped holes in thin-walled structures of high-temperature alloys. Background Technology

[0002] Stepped holes are a common hole system manufacturing feature, referring to holes segmented with different diameters. They play a crucial role in connection structures in aerospace and other fields, especially in applications requiring complex loads, lightweight design, and interchangeability. Due to their unique structural characteristics, they serve to distribute loads across different levels, preventing stress concentration. Furthermore, their structure is adaptable to various parts, offering strong interchangeability. In aerospace connections, stepped holes represent more than just simple geometric design; they integrate key technologies such as mechanical optimization and functional adaptation.

[0003] In traditional machining methods, stepped holes, especially irregular stepped holes, are machined using a drilling-reaming process. This involves designing and manufacturing a special stepped drill to machine the hole system. While this method ensures the certainty of hole machining, it also has drawbacks such as long design and machining cycles, procurement cycle risks, the need for special tools to be adapted to specific parameters, and high manufacturing costs. In particular, when machining new parts and new features, a special stepped drill needs to be designed for each stepped hole feature, which greatly increases the machining cost. Summary of the Invention

[0004] The objective of this invention is to provide a method for machining stepped holes in thin-walled structures of high-temperature alloys, enabling the machining of stepped holes in weakly rigid thin-walled structures while ensuring the surface roughness and dimensional accuracy of the hole system features.

[0005] This application provides a method for machining stepped holes in thin-walled structures of high-temperature alloys, the method comprising:

[0006] S1: Analyze the component structure and design support for locations with weak structural rigidity in the system. S2: Fabricate tooling fixtures according to the tooling drawings; S3: Select the tool coating, material, and size based on the part material and the dimensions and characteristics of the stepped hole; S4: Compile CNC machining programs for drilling; S5: Clean the contact surface between the tool and the machine tool table, and place it on the machine tool table; S6: Use a lever dial indicator to align the straightened edge of the tooling; S7: Place the workpiece on the fixture and tighten it with a wrench; S8: Use a lever dial indicator to align the parts and make the machine tool coordinate system coincide with the machining coordinate system; S9: Use a tool holder and clamp to clamp the tool; S10: Set the zero point of the surface Z value according to the program for tool setting; S11: Use centering drill T1 to machine the centering hole of the stepped hole; S12: Use drill bit T2 to machine the bottom hole of the stepped hole; S13: Enlarge the stepped hole with drill bit T3; S14: Use drill bit T4 to machine the stepped portion of the stepped hole; S15: Use a forming cutter or flat-bottomed cutter T5 to shape the stepped part and complete the finishing process; S16: Size inspection.

[0007] Preferably, in S1, when designing the part support, the rigidity of the tooling-part system structure is enhanced by using an over-positioning method; In S2, the tooling positioning components are made of steel, with a hollow structure for weight reduction and surface oxidation treatment to prevent rust. The clamping and other parts are made of aluminum to reduce the weight of the tooling and make it easy to use.

[0008] Preferably, in S3, for machining Ni-based superalloys, the tool material should be a fine-grained / ultra-fine-grained cemented carbide with added TaC / NbC, the tool coating should be TiAlN or AlCrN coating, and the tool size should be selected according to the part design size requirements; In S4, different cutting parameters need to be selected for different machining steps. When machining the bottom hole, the cutting speed is 20m / min-30m / min and the feed rate is 0.1 mm / rev-0.15mm / rev. When reaming and forming, the cutting speed is 30 m / min-50m / min and the feed rate is 0.05 mm / rev-0.1mm / rev. The parameters required for compiling the CNC program are the X and Y coordinates of the hole system feature group and the Z value of the cutting depth for different drill bits. The X and Y coordinates are determined by the design drawings.

[0009] Preferably, in step S5, compressed air is first used to clean the machine tool table and the contact surface between the tooling and the table to ensure that there are no iron filings or cutting fluid. Then, a clean white cloth or wiping paper is used to wipe the surface to ensure that there are no oil stains or dirt.

[0010] Preferably, in step S6, a lever dial indicator is used to align the straight edge of the fixture. This step directly affects the positional accuracy of the hole system features. The accuracy of the lever dial indicator must be ensured, and the alignment runout must be within 1 / 5 of the positional accuracy required by the drawing, not exceeding 0.03 mm.

[0011] Preferably, in step S7, when placing the part on the fixture and tightening it with a wrench, it is sufficient to ensure that the part is pressed firmly without excessive force, so as to avoid deformation of the part due to clamping force. In step S8, a lever dial indicator is used to align the axis reference of the part. This step directly affects the positional accuracy of the hole system features. The accuracy of the lever dial indicator must be ensured. The alignment runout is required to be within 1 / 5 of the positional accuracy required by the drawing, and not exceed 0.03mm. After alignment, the coordinates should be carefully checked when inputting the mechanical coordinate system coordinates to avoid errors.

[0012] Preferably, in step S9, the required cutting tools are clamped using 1-7 collets and tool holders, and the clamping is ensured to be in place and reliable during clamping. In S10, the tool is installed on the machine tool spindle, moved to the tool magazine according to the CNC program tool number, the tool number is called, and the tool tip and gauge block are used to perform tool setting in the Z0 plane of the part machining coordinate system; In step S11, a centering hole with a depth of 0.5 mm is machined using a centering drill.

[0013] Preferably, in steps S12 to S15, the machining is completed by running the CNC program, and the size of the stepped hole is measured by a digital caliper / micrometer after machining is completed. In step S16, templates can be used to improve measurement efficiency for stepped hole profiles. The hole diameter and step depth are measured using digital calipers / micrometers. MSA measurement system analysis is performed on the part measurement system to ensure the stability and accuracy of the measurement system.

[0014] The beneficial technical effects of this application are as follows: By replacing the traditional, custom-sized step drill with a universal tool combination machining solution, the limitations of single-specification dedicated drill bits have been successfully overcome. This innovative approach shortens the design and manufacturing cycle of dedicated step drills to an immediately usable combination of universal tools. Through a modular tool configuration strategy, high-precision machining of thin-walled stepped holes is achieved.

[0015] In actual machining, custom-made step drills of specific dimensions are expensive and may cause significant tool wear during the process technology development phase, leading to increased development costs. The modular machining method using universal tools of this invention can significantly reduce tool costs during the process technology development phase; in the embodiments, tool costs are reduced by more than 60%, effectively alleviating the manufacturing cost pressure on high-value parts.

[0016] When using a dedicated step drill for machining, it is a one-step process with a large cutting volume. This often requires parameter testing to match the machining parameters for different materials and structures, resulting in a lengthy testing cycle. This invention uses a general-purpose tool for multi-step machining, reducing the cutting layer thickness per feed and improving tool life through multiple cuts. Parameter selection can be adjusted by referring to recommended cutting parameters for existing general-purpose tools, avoiding the increased costs and longer cycle times associated with parameter testing.

[0017] Currently, due to the flexible production model of small batches and multiple types, most parts processing requires a rapid response production rhythm. The design, manufacturing, and testing cycle of special tools is relatively long, with the entire process cycle generally taking about 4-5 weeks. If inventory is depleted or unexpectedly unavailable during production, an additional procurement cycle is required. Such situations bring uncertainty to the production cycle. The present invention uses general-purpose tools for the entire processing process. The market is mature and the procurement cycle is fixed. Actual processing verification shows that it can shorten the corresponding processing cycle by more than 40%, which is more in line with the modern flexible production concept and has significant industry promotion value and technological leadership role. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Appendix Figure 1 Schematic diagram of Z-value calculation in CNC programming for irregular stepped holes; Wherein, 1 is the base and 2 is the support rod. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0022] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0024] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] The following is a description of the embodiments and appendices. Figure 1 The present invention will be described in further detail, but the embodiments of the present invention are not limited thereto.

[0026] This application provides a method for machining stepped holes in thin-walled structures of high-temperature alloys, comprising the following steps: S1: Select the design datum as the process datum, design the stop positioning structure for positioning, and use the pressure plate to press the back of the positioning surface feature. S2: Design and manufacture tooling. Steel is selected for the positioning straight opening, and aluminum is selected for parts that need to be lifted and operated, such as pressure plates. Circular hollowing is used to reduce weight in each structure where permissible. S3: Tool selection: Select Kennametal, Sandvik, or equivalent domestic manufacturers with corresponding specifications. In this example, the tool sizes are selected as follows: T01: φ1 centering drill for machining centering holes, T02: φ5.5*118° carbide drill for machining pilot holes, T03: φ6*118° carbide drill for reaming, T04: φ7*118° carbide drill for reaming, and T05: φ7*60° carbide chamfering tool for forming. S4: Compile the CNC program according to the center coordinates of the feature group of the hole system in the design drawing. According to the formula in the attached figure, the Z values ​​of the CNC program in this example are calculated as follows: Z1=10.53, Z2=3.873, Z3=7.877; S5: After rinsing the machine tool table with a high-pressure water gun, blow away the cutting fluid, iron filings, etc. with compressed air. Then wipe the machine tool table and tooling surface with wiping paper to ensure that there is no rust, oil or dirt. S6: Use a lever dial indicator to align the clamp and straighten the edge; the runout should be 0.02. S7: Tighten the pressure plate and nut with an adjustable wrench to a torque of 50 N·m; S8: Use a lever dial indicator to align the coordinate system reference for part machining, with a runout of 0.01mm; S9: Clamp tools T01 to T05 on the tool clamping worktable; S10: Load the aforementioned tools into positions T01 to T05 according to the machine tool tool magazine positions, and insert them into the tool magazine. On the upper surface of the part (machining coordinate system Z), perform tool setting on tool tips T01 to T05 in sequence, and input the tool setting values ​​at the tool setting value positions h01 to h05 on the machine tool in sequence; S11: Use a T01 centering drill to machine the centering hole to a depth of 0.5mm using a CNC program.

[0027] S12~S15: Run the CNC program for machining. After each program segment is completed, observe the tool status. If coating wear, tool edge wear, or other issues occur, replace the tool. S16: Use a dial indicator to measure the diameter of the stepped hole and a template to measure the profile of the stepped hole. Perform MSA analysis on the measurement system. The gauge R&R is 13.86% ≤ 30%, the number of distinguishable categories is 20 ≥ 4, the measurement system is acceptable, the data is available, and the measurement system is reliable.

[0028] Appendix Figure 1 Note 1: The drill bit angle should be greater than α°. For economic reasons, a 118° carbide drill bit is selected.

[0029]

[0030]

[0031] In the formula: L, L1, Φ1, Φ2, α are the design dimensions of the stepped hole required by the drawing, (3~5) are the empirical dimensions for through hole machining, and Z1, Z2, Z3 are the Z values ​​of CNC programming for different drill bits.

[0032] In other embodiments of this application, a method for machining stepped holes in a thin-walled structure of a high-temperature alloy is provided, comprising the following steps: S1: Analyze the component structure and design support for locations with weak structural rigidity in the system. S2: Fabricate tooling fixtures according to the tooling drawings; S3: Select the tool coating, material, and size based on the part material and the dimensions and characteristics of the stepped hole; S4: Compile CNC machining programs for drilling; S5: Clean the contact surface between the tool and the machine tool table, and place it on the machine tool table; S6: Use a lever dial indicator to align the straightened edge of the tooling; S7: Place the workpiece on the fixture and tighten it with a wrench; S8: Use a lever dial indicator to align the parts and make the machine tool coordinate system coincide with the machining coordinate system; S9: Use a tool holder and clamp to clamp the tool; S10: Set the zero point of the surface Z value according to the program for tool setting; S11: Use centering drill T1 to machine the centering hole of the stepped hole; S12: Use drill bit T2 to machine the bottom hole of the stepped hole; S13: Enlarge the stepped hole with drill bit T3; S14: Use drill bit T4 to machine the stepped portion of the stepped hole; S15: Use a forming cutter or flat-bottomed cutter T5 to shape the stepped part and complete the finishing process; S16: Size inspection.

[0033] In one possible embodiment, during the part support design in step S1, the rigidity of the tooling-part system structure is enhanced by employing an over-positioning method. In one possible embodiment, in step S2, the tooling positioning components are made of steel, with a hollow structure for weight reduction, and surface oxidation treatment to prevent corrosion. The clamping and other parts are made of aluminum to reduce the tooling weight and facilitate use. In one possible embodiment, in step S3, for machining Ni-based superalloys, the tool material should be a fine-grained / ultra-fine-grained cemented carbide with added TaC / NbC, and the tool coating should be TiAlN or AlCrN coating. The tool size is selected according to the part design size requirements; In one possible embodiment, in step S4, different cutting parameters need to be selected for different machining steps. When machining the bottom hole, the cutting speed is 20 m / min - 30 m / min and the feed rate is 0.1 mm / rev - 0.15 mm / rev. When reaming and forming, the cutting speed is 30 m / min - 50 m / min and the feed rate is 0.05 mm / rev - 0.1 mm / rev. The parameters needed for compiling the CNC program include the X and Y coordinates of the hole system feature group and the Z-value of the cutting depth for different drill bits. The X and Y coordinates are determined by the design drawings, and the calculation method for the Z-value is shown in the appendix. Figure 1 ; In one possible embodiment, in step S5, compressed air is first used to clean the machine tool table and the contact surface between the tooling and the table to ensure that there are no iron filings or cutting fluid. Then, a clean white cloth or wiping paper is used to wipe it to ensure that there are no oil stains or dirt. In one possible embodiment, in step S6, the straight edge of the fixture is aligned using a lever dial indicator. This step directly affects the positional accuracy of the hole system features. The accuracy of the lever dial indicator must be ensured, and the alignment runout is required to be within 1 / 5 of the positional accuracy required by the drawing, generally not exceeding 0.03 mm. In one possible embodiment, in step S7, when placing the part on the fixture and tightening it with a wrench, it is sufficient to ensure that the part is pressed firmly without excessive force, so as to avoid deformation of the part due to clamping force.

[0034] In one possible embodiment, in step S8, the axis reference of the part is aligned using a lever dial indicator. This step directly affects the positional accuracy of the hole system features. The accuracy of the lever dial indicator must be ensured. The alignment runout is required to be within 1 / 5 of the positional accuracy required by the drawing, generally not exceeding 0.03mm. After alignment, the coordinates should be carefully checked when inputting the mechanical coordinate system coordinates to avoid input errors. In one possible embodiment, in step S9, the required tools are clamped using 1-7 collets and tool holders, and the clamping is ensured to be in place and reliable. In one possible embodiment, in step S10, the tool is mounted on the machine tool spindle, moved to the tool magazine according to the CNC program tool number, the tool number is called, and the tool tip and gauge block are used to perform tool setting in the Z0 plane of the part machining coordinate system; In one possible embodiment, in step S11, a centering hole with a depth of 0.5 mm is machined using a centering drill. In one possible embodiment, in steps S12 to S15, the CNC program is run to complete the machining, and the size of the stepped hole is measured with a digital caliper / micrometer after the machining is completed. In one possible embodiment, in step S16, a template can be used to improve the measurement efficiency for stepped hole profiles with shaped surfaces. The hole diameter and step depth are measured using a digital caliper / micrometer. The part measurement system is subjected to MSA measurement system analysis to ensure the stability and accuracy of the measurement system.

[0035] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A method for machining stepped holes in thin-walled structures of high-temperature alloys, characterized in that, The method includes: S1: Analyze the component structure and design support for locations with weak structural rigidity in the system. S2: Fabricate tooling fixtures according to the tooling drawings; S3: Select the tool coating, material, and size based on the part material and the dimensions and characteristics of the stepped hole; S4: Compile CNC machining programs for drilling; S5: Clean the contact surface between the tool and the machine tool table, and place it on the machine tool table; S6: Use a lever dial indicator to align the straightened edge of the tooling; S7: Place the workpiece on the fixture and tighten it with a wrench; S8: Use a lever dial indicator to align the parts and make the machine tool coordinate system coincide with the machining coordinate system; S9: Use a tool holder and clamp to clamp the tool; S10: Set the zero point of the surface Z value according to the program for tool setting; S11: Use centering drill T1 to machine the centering hole of the stepped hole; S12: Use drill bit T2 to machine the bottom hole of the stepped hole; S13: Enlarge the stepped hole with drill bit T3; S14: Use drill bit T4 to machine the stepped portion of the stepped hole; S15: Use a forming cutter or flat-bottomed cutter T5 to shape the stepped part and complete the finishing process; S16: Size inspection.

2. The method according to claim 1, characterized in that, In S1, when designing the part support, the rigidity of the tooling-part system structure is enhanced by using an over-positioning method; In S2, the tooling positioning components are made of steel, with a hollow structure for weight reduction and surface oxidation treatment to prevent rust. The clamping and other parts are made of aluminum to reduce the weight of the tooling and make it easy to use.

3. The method according to claim 1, characterized in that, In S3, for machining Ni-based superalloys, the tool material should be a fine-grained / ultra-fine-grained cemented carbide with added TaC / NbC, the tool coating should be TiAlN or AlCrN coating, and the tool size should be selected according to the part design size requirements. In S4, different cutting parameters need to be selected for different machining steps. When machining the bottom hole, the cutting speed is 20m / min-30m / min and the feed rate is 0.1 mm / rev-0.15mm / rev. When reaming and forming, the cutting speed is 30 m / min-50m / min and the feed rate is 0.05 mm / rev-0.1mm / rev. The parameters required for compiling the CNC program are the X and Y coordinates of the hole system feature group and the Z value of the cutting depth for different drill bits. The X and Y coordinates are determined by the design drawings.

4. The method according to claim 1, characterized in that, In step S5, compressed air is first used to clean the machine tool table and the contact surface between the tooling and the table to ensure that there are no iron filings or cutting fluid. Then, a clean white cloth or wiping paper is used to wipe the surface to ensure that there are no oil stains or dirt.

5. The method according to claim 1, characterized in that, In step S6, a lever dial indicator is used to align the straight edge of the fixture. This step directly affects the positional accuracy of the hole system features. The accuracy of the lever dial indicator must be ensured, and the alignment runout must be within 1 / 5 of the positional accuracy required by the drawing, not exceeding 0.03mm.

6. The method according to claim 1, characterized in that, In S7, when placing the part on the fixture and tightening it with a wrench, it is sufficient to ensure that the part is pressed firmly, without excessive force, to avoid deformation of the part due to clamping force. In step S8, a lever dial indicator is used to align the axis reference of the part. This step directly affects the positional accuracy of the hole system features. The accuracy of the lever dial indicator must be ensured. The alignment runout is required to be within 1 / 5 of the positional accuracy required by the drawing, and not exceed 0.03mm. After alignment, the coordinates should be carefully checked when inputting the mechanical coordinate system coordinates to avoid errors.

7. The method according to claim 1, characterized in that, In S9, the required tools are clamped using 1-7 collets and tool holders, and it is ensured that the clamping is in place and reliable during clamping. In S10, the tool is installed on the machine tool spindle, moved to the tool magazine according to the CNC program tool number, the tool number is called, and the tool tip and gauge block are used to perform tool setting in the Z0 plane of the part machining coordinate system; In step S11, a centering hole with a depth of 0.5 mm is machined using a centering drill.

8. The method according to claim 1, characterized in that, In steps S12 to S15, the CNC program is run to complete the machining. After machining is completed, the size of the stepped hole is measured with a digital caliper / micrometer. In step S16, templates can be used to improve measurement efficiency for stepped hole profiles. The hole diameter and step depth are measured using digital calipers / micrometers. MSA measurement system analysis is performed on the part measurement system to ensure the stability and accuracy of the measurement system.

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