A fast adaptive milling method for large thin-walled blade tips

Abstract

The present invention belongs to the technical field of blade processing and relates to a method for rapid adaptive milling of large thin-walled blade tips, comprising the following steps: Step 1: compiling a blade tip milling program based on a theoretical blade model; Step 2: compiling a machining program for a certain section of the blade body near the blade tip based on the theoretical blade model as an on-machine detection program; Step 3: installing a dial indicator on the spindle, running the on-machine detection program, and detecting the machining status of the section using the dial indicator; Step 4: calculating the torsion angle and offset of the blade section based on the detected machining status, and adjusting the blade tip milling program; Step 5: running the adjusted blade tip milling program to complete the adaptive machining of the blade tip. This machining method can smoothly transition the blade tip machining area to the original blade body. It can also be applied to the local adaptive machining process of any complex curved surface part, demonstrating strong versatility and practicality.

Description

Technical Field

[0001] The invention belongs to the technical field of blade processing and relates to a fast adaptive milling method for the tip of a large thin-walled blade. Background Art

[0002] As we all know, the turbofan engine, widely used in fighter jets, generates thrust primarily by drawing air in through the intake, compressing it in the compressor, and thoroughly mixing it with fuel in the combustion chamber. After ignition, the air then expands through the turbine and is expelled through the exhaust nozzle. The reaction force generated by this high-temperature, high-velocity air is the turbofan engine's thrust. Understanding this principle of turbofan engine thrust generation reveals that increasing engine thrust and further improving engine performance requires reducing airflow leakage and endwall loss in the flow channel. Tip clearance loss, a major contributor to endwall loss, is primarily caused by insufficient clearance between the blade tip and the mating element. To ensure superior and stable engine performance, tip clearance must be minimized during critical operating conditions and prevent interference or scratching with the base in other conditions. Therefore, in-depth research into rotor blade tip machining and repair processes, and improving their efficiency and precision, is a process of strengthening the foundation and addressing weaknesses. This has far-reaching implications for improving engine quality, precision, and performance.

[0003] The biggest problem restricting the machining quality and efficiency of large thin-walled rotor blade tips is that the low stiffness and complex structure will cause deformation during machining, making it difficult to ensure machining accuracy. The blade surface has a large twist angle, and in order to reduce weight, the structure adopts a thin-walled structure; the rotor blade has a cantilever structure, which makes positioning and clamping difficult during machining. The error caused by clamping is large, and machining accuracy is difficult to ensure. The structure of large thin-walled rotor blades and the blade tip wall thickness are similar. Figure 1 As shown. Affected by the above-mentioned blade structure and clamping factors, if programming and processing are performed according to the theoretical model, there will be large cutting marks between the blade tip profile and the processed blade profile, or the blade tip processing will be unqualified, and adaptive processing technology needs to be introduced. Traditional adaptive processing technology requires first detecting the parts, reconstructing the model based on the measurement data, and then compiling the CNC processing program based on the reconstructed model to complete the adaptive processing. In this process, it is necessary to introduce special detection software and probes, model reconstruction, adaptive processing software, etc., which require high costs, long processing and debugging time, and low processing efficiency. Therefore, the invention of an effective process method for rapid and precise processing of large quantities of blade tips has very important engineering application value. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a method for rapid adaptive milling of blade tips of large thin-walled blades. When adjusting the blade tip milling program according to the on-machine measurement results, there is no need to reconstruct the processing model, which shortens the processing debugging time and improves efficiency.

[0005] The present invention provides a method for rapid adaptive milling of a large thin-walled blade tip, comprising:

[0006] Step 1: Prepare the blade tip milling program based on the blade theoretical model;

[0007] Step 2: Prepare a machining program for a certain section of the blade near the blade tip based on the blade theoretical model as an on-machine inspection program;

[0008] Step 3: Install the dial indicator on the spindle, run the on-machine detection program, and use the dial indicator to detect the machining status of the section;

[0009] Step 4: Calculate the torsion angle and offset of the blade section based on the detected machining status and adjust the blade tip milling program;

[0010] Step 5: Run the adjusted blade tip milling program to complete the adaptive machining of the blade tip.

[0011] In the fast adaptive milling method for large thin-walled blade tips of the present invention, step 1 is specifically as follows:

[0012] Step 1.1: Use UG software to compile the blade tip milling program based on the blade theoretical model;

[0013] Step 1.2: Export the blade tip milling program after UG post-processing.

[0014] In the rapid adaptive milling method for large thin-walled blade tips of the present invention, step 2 is specifically as follows:

[0015] Step 2.1: Use UG software to compile a machining program for a certain section of the blade near the blade tip based on the blade theoretical model;

[0016] Step 2.2: Set the tool diameter used in the machining program to be consistent with the dial indicator head diameter used for on-site inspection. Use this machining program as the on-machine inspection program to inspect the status of the machined blade section near the blade tip.

[0017] In the rapid adaptive milling method for large thin-walled blade tips of the present invention, step 3 is specifically as follows:

[0018] Step 3.1: Remove the machining tool from the spindle and install the dial indicator on the spindle;

[0019] Step 3.2: Enter the distance from the spindle zero point to the dial indicator head into the length compensation option in the machine tool parameter library;

[0020] Step 3.3: Run the on-machine detection program and use the dial indicator to detect the processing status of the section.

[0021] In the fast adaptive milling method for large thin-walled blade tips of the present invention, step 4 specifically calculates the torsion angle or offset of the blade cross section based on the change in the dial indicator reading, including:

[0022] Step 4.1: When the dial indicator reading is uniform a during the on-machine inspection program, that is, when the blade tip is only offset, the Z axis of the blade coordinate system in the blade tip milling program is translated a, and the blade tip milling program is moved to the actual part position to achieve adaptive machining of the blade tip, a>0;

[0023] Step 4.2: When running the on-machine test program, the dial indicator reading is -a to +b, that is, the blade tip is only twisted. Calculate the twist angle of the blade section according to the following formula:

[0024]

[0025] Where α is the section twist angle, L is the blade width at the section, α is compensated into the blade tip milling program, and the blade tip milling program is rotated to the actual part position to achieve adaptive machining of the blade tip;

[0026] Step 4.3: When the dial indicator reading is a~b during the on-machine inspection program, the blade tip has both offset and twist. Shift the Z axis of the blade coordinate system in the blade tip milling program. The torsion angle of the blade section is then calculated according to the following formula:

[0027]

[0028] The torsion angle is compensated in the blade tip milling program, and the blade tip milling program is moved and rotated to the actual part position to achieve adaptive machining.

[0029] In the rapid adaptive milling processing method for large thin-walled blade tips of the present invention, when there is an offset in the blade cross section in steps 4.1 and 4.3, the Z axis of the blade coordinate system is not translated in the blade tip milling processing program, and the offset compensation is achieved by directly moving the zero point of the blade coordinate system toward the Z axis by the corresponding offset in the machine tool system.

[0030] The invention provides a method for rapid adaptive milling of large thin-walled blade tips, which has at least the following beneficial effects:

[0031] (1) This method does not require the use of specialized high-precision probe systems and adaptive machining software, thus saving costs. When adjusting the blade tip milling program based on the measurement results, there is no need to reconstruct the machining model, which shortens machining debugging time and improves efficiency.

[0032] (2) This method successfully applied the relevant technology to the CNC machining process of the blade tip of a certain type of fan of the company, and successfully controlled the cutting mark between the original machining surface and the blade tip machining surface within 0.03mm, shortened the machining and debugging time by about 50%, and effectively reduced the machining cost.

[0033] (3) This method can smoothly transition the blade tip processing area to the original blade shape. It can also be applied to the local adaptive processing of any complex curved surface parts, and has strong versatility and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of a large thin-walled blade structure and blade tip wall thickness of the present invention;

[0035] Figure 2 This is a schematic diagram of calculating the offset when the blade tip is only offset in the present invention;

[0036] Figure 3 This is a schematic diagram of calculating the twist angle when the blade tip of the present invention is only twisted;

[0037] Figure 4 This is a schematic diagram of calculating the offset and twist angle when the blade tip of the present invention has both offset and twist. DETAILED DESCRIPTION

[0038] like Figure 1 As shown, the machining quality of aeroengine blade tips can impact engine performance. Large rotor blades have large blade torsion angles and low rigidity, making deformation more likely during machining. Furthermore, the cantilever structure of rotor blades makes positioning and clamping difficult during machining, leading to significant errors and difficulty in ensuring machining accuracy. Due to these blade structure and clamping factors, programming according to theoretical models can lead to problems such as large tool marks between the tip profile and the machined blade, or unqualified blade tip machining. This requires the adaptive machining method of the present invention, which measures the machined blade profile on-board, calculates the torsion angle or offset, and adjusts the CNC machining program to achieve adaptive machining.

[0039] A fast adaptive milling method for a large thin-walled blade tip according to the present invention specifically comprises the following steps:

[0040] Step 1: Prepare a blade tip milling program based on the blade theoretical model. Step 1 is specifically as follows:

[0041] Step 1.1: Use UG software to compile the blade tip milling program based on the blade theoretical model;

[0042] Step 1.2: Export the blade tip milling program after UG post-processing.

[0043] Step 2: Compile a machining program for a certain section of the blade near the blade tip on the blade theoretical model as an on-machine detection program. Step 2 is specifically as follows:

[0044] Step 2.1: Use UG software to compile a machining program for a certain section of the blade near the blade tip based on the blade theoretical model;

[0045] Step 2.2: Set the tool diameter used in the machining program to be consistent with the dial indicator head diameter used for on-site inspection. Use this machining program as the on-machine inspection program to inspect the status of the machined blade section near the blade tip.

[0046] Step 3: Install the dial indicator on the spindle, run the on-machine detection program, and use the dial indicator to detect the machining status of the section. Step 3 is specifically as follows:

[0047] Step 3.1: Remove the machining tool from the spindle and install the dial indicator on the spindle;

[0048] Step 3.2: Enter the distance from the spindle zero point to the dial indicator head into the length compensation option in the machine tool parameter library;

[0049] Step 3.3: Run the on-machine detection program and use the dial indicator to detect the processing status of the section.

[0050] Step 4: Calculate the torsion angle and offset of the blade section based on the detected machining status and adjust the blade tip milling program;

[0051] In specific implementation, the torsion angle or offset of the blade section is calculated based on the change in the dial indicator reading, including:

[0052] Step 4.1: When the dial indicator reading is uniform a during the on-machine inspection program, that is, when the blade tip is only offset, the Z axis of the blade coordinate system in the blade tip milling program is translated a, and the blade tip milling program is moved to the actual part position to achieve adaptive machining of the blade tip, a>0; Figure 2 shown.

[0053] Step 4.2: When running the on-machine test program, the dial indicator reading is -a to +b, that is, the blade tip is only twisted. Calculate the twist angle of the blade section according to the following formula:

[0054]

[0055] Among them, α is the section twist angle, L is the blade width at the section, α is compensated into the blade tip milling program, and the blade tip milling program is rotated to the actual part position to achieve adaptive machining of the blade tip; Figure 3 shown.

[0056] Step 4.3: When the dial indicator reading is a~b during the on-machine inspection program, the blade tip has both offset and twist. The blade coordinate system in the blade tip milling program is translated in the Z-axis direction. The torsion angle of the blade section is then calculated according to the following formula:

[0057]

[0058] Compensate the torsion angle into the blade tip milling program, move and rotate the blade tip milling program to the actual part position, and realize adaptive machining, such as Figure 4 shown.

[0059] In specific implementation, when there is an offset in the blade cross section, the offset compensation can also be achieved by directly moving the zero point of the blade coordinate system toward the Z axis by a corresponding offset in the machine tool system.

[0060] Step 5: Run the adjusted blade tip milling program to complete the adaptive machining of the blade tip.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the concept of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fast adaptive milling method for large thin-walled blade tips, characterized in that: include: Step 1: Prepare the blade tip milling program based on the blade theoretical model; Step 2: Prepare a machining program for a certain section of the blade near the blade tip based on the blade theoretical model as an on-machine inspection program; Step 3: Install the dial indicator on the spindle, run the on-machine detection program, and use the dial indicator to detect the machining status of the section; Step 4: Calculate the torsion angle and offset of the blade section based on the detected machining status and adjust the blade tip milling program; Step 5: Run the adjusted blade tip milling program to complete the adaptive machining of the blade tip; The step 3 is specifically as follows: Step 3.1: Remove the machining tool from the spindle and install the dial indicator on the spindle; Step 3.2: Enter the distance from the spindle zero point to the dial indicator head into the length compensation option in the machine tool parameter library; Step 3.3: Run the on-machine inspection program and use the dial indicator to check the machining status of the section; The step 4 specifically calculates the torsion angle or offset of the blade section according to the change in the dial indicator reading, including: Step 4.1: When the dial indicator reading is uniform a during the on-machine inspection program, that is, when the blade tip is only offset, the Z axis of the blade coordinate system in the blade tip milling program is translated a, and the blade tip milling program is moved to the actual part position to achieve adaptive machining of the blade tip, a>0; Step 4.2: When running the on-machine test program, the dial indicator reading is -a to +b, that is, the blade tip is only twisted. Calculate the twist angle of the blade section according to the following formula: Where α is the section twist angle, L is the blade width at the section, α is compensated into the blade tip milling program, and the blade tip milling program is rotated to the actual part position to achieve adaptive machining of the blade tip; Step 4.3: When the dial indicator reading is a~b during the on-machine inspection program, the blade tip has both offset and twist. Shift the Z axis of the blade coordinate system in the blade tip milling program. The torsion angle of the blade section is then calculated according to the following formula: The torsion angle is compensated into the blade tip milling program, and the blade tip milling program is moved and rotated to the actual part position to achieve adaptive machining.

2. The rapid adaptive milling method for large thin-walled blade tips according to claim 1, characterized in that: The step 1 is specifically as follows: Step 1.1: Use UG software to compile the blade tip milling program based on the blade theoretical model; Step 1.2: Export the blade tip milling program after UG post-processing.

3. The rapid adaptive milling method for large thin-walled blade tips according to claim 1, characterized in that: The step 2 is specifically as follows: Step 2.1: Use UG software to compile a machining program for a certain section of the blade near the blade tip based on the blade theoretical model; Step 2.2: Set the tool diameter used in the machining program to be consistent with the dial indicator head diameter used for on-site inspection. Use this machining program as the on-machine inspection program to inspect the status of the machined blade section near the blade tip.

4. The rapid adaptive milling method for large thin-walled blade tips according to claim 1, characterized in that: When there is an offset in the blade cross section in steps 4.1 and 4.3, the Z axis of the blade coordinate system is not translated in the blade tip milling program. Instead, the offset compensation is achieved by directly moving the zero point of the blade coordinate system toward the Z axis by the corresponding offset in the machine tool system.

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