Precise positioning method for main blade root bushing

Abstract

The embodiment of the invention discloses a precise positioning method for a main paddle root bushing. The precise positioning method comprises the following steps: step 1, processing a paddle positioning reference on a paddle forming die; step 2, processing an auxiliary positioning reference on the paddle root bushing, wherein the processed auxiliary positioning reference is consistent with a paddle positioning reference on the paddle forming die in position; 3, a laser level meter is adopted to project a laser line on the paddle forming die to serve as a paddle datum line, and the projected paddle datum line and the paddle positioning datum on the paddle forming die are completely overlapped; and step 4, mounting the paddle root bushing: projecting a paddle datum line which is completely overlapped with the paddle positioning reference on the basis of the paddle forming die, and mounting the paddle root bushing, so that the auxiliary positioning reference of the paddle root bushing is completely overlapped with the laser line projected on the paddle forming die. The problems that in an existing positioning mode, the preparation period of the main blade is long, and the manufacturing cost is increased are solved.

Description

Technical Field

[0001] This invention relates to, but is not limited to, the field of composite material blade manufacturing technology, and particularly to a method for precise positioning of the root bushing of a main blade. Background Technology

[0002] The helicopter composite main rotor blade uses a root bushing with continuous fiber winding to form the blade root joint. The blade is then connected and fixed to the rotor hub via metal bushings. Two metal bushings are embedded in the joint filler block, ensuring smooth winding of the roving fibers around the blade, thus enabling a long overall blade life. The blade root bushing is a crucial component at the blade-hull connection, protecting the blade root and reducing friction and wear. The composite rotor blade roving fibers are wound around the outside of the joint bushing to form the connection joint between the blade and the hub.

[0003] The metal bushings at the blade root are typically fixed in a closed mold via pre-embedding, and the blades are manufactured using a thermoforming process. During the molding of the blades, the metal bushings at the blade root are usually positioned using tooling. This tooling ensures the accuracy of the placement of the two blade root bushings. Figure 1 The diagram shows the assembly angle between the main blade root bushing and the main blade. The blade root bushing has a 6° assembly angle with the blade, therefore, the installation and positioning method of the metal bushing must be considered.

[0004] Traditional methods for locating metal bushings typically employ either a datum positioning method or a pin positioning method. The datum positioning method generally uses the inner hole of the metal bushing as the positioning datum, or the outer diameter of the metal bushing for positioning. The pin positioning method, through the design of appropriately shaped locating pin holes and pins, achieves precise positioning of the bushing relative to the surrounding structure. There are various methods for fixing the locating pins, including internal thread screw fixing, external thread screw fixing, and interference fits.

[0005] The aforementioned traditional positioning and installation methods for metal bushings cannot achieve the pre-set angle assembly between the blade root metal bushing and the blade. Because the blade root metal bushing has a certain assembly angle with the blade, the existing positioning method for the main blade root bushing uses both internal hole positioning and pin positioning to ensure the positional accuracy of the two root bushings in multiple directions. While the existing positioning method for the main blade root bushing can achieve synchronous positioning of the two root bushings, it requires the additional fabrication of connecting fixtures. For different models of main blades, fixtures need to be fabricated separately according to the internal hole and installation angle of the root bushings, resulting in a long manufacturing cycle and increased manufacturing costs for the main blades. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems. This invention provides a precise positioning method for the root bushing of the main blade, which solves the problem that existing positioning methods for the root bushing of the main blade require the separate preparation of tooling according to the inner hole and installation angle of the root bushing for different models of main blades, resulting in long manufacturing cycles and increased manufacturing costs for the main blades.

[0007] The technical solution of the present invention: An embodiment of the present invention provides a method for precise positioning of the main blade root bushing, comprising: Step 1: Machining the blade positioning reference on the blade forming mold; Step 2, machining auxiliary positioning references on the blade root bushing, including: machining auxiliary positioning references on the inner wall of the blade root bushing digital mold, wherein the machined auxiliary positioning references are aligned with the blade positioning references on the blade forming mold. Step 3: Use a laser level to project a laser line onto the blade forming mold as the blade reference line, and the projected blade reference line completely overlaps with the blade positioning reference on the blade forming mold. Step 4, Install the blade root bushing, including: Based on the blade reference line projected on the blade forming mold that completely overlaps with the blade positioning reference, install the blade root bushing so that the auxiliary positioning reference of the blade root bushing completely coincides with the laser line projected on the blade forming mold.

[0008] Optionally, in the precise positioning method of the main blade root bushing as described above, in step 1, the Z0 position mark of the blade is machined on the blade forming mold. In step 2, the auxiliary positioning references machined on the inner wall of the propeller root bushing digital model include the Z0 reference line and the direction marking line.

[0009] Optionally, in the precise positioning method for the main blade root bushing as described above, step 1 includes: The Z0 position of the blade is marked on both sides of the front and rear edges of the blade forming mold by machining, thus marking the Z0 position on both sides of the front and rear edges of the blade forming mold.

[0010] Optionally, in the precise positioning method for the main blade root bushing as described above, the Z0 datum line machined on the inner wall of the root bushing digital model in step 1 is completely consistent with the Z0 datum of the blade forming mold; step 1 includes: Step 11: Draw two symmetrical and parallel marking lines on the inner wall of the rotor root bushing CAD model as the Z0 reference lines of the rotor root bushing. This is used to ensure that the two Z0 reference lines on the rotor root bushing CAD model coincide with the Z0 position of the rotor blade during the subsequent positioning process. Step 12: By engraving directional marking lines on the inner wall of the blade root bushing, the directional marking lines are directed toward the blade root or blade tip during the installation and positioning process; the directional marking lines are parallel to the blade spanwise direction.

[0011] Optionally, in the precise positioning method for the main blade root bushing as described above, step 3 includes: A laser level is placed on one side of the blade forming mold, and the Z0 position line of the blade is used as the projection target. A laser line that completely overlaps with the Z0 position line of the blade is projected by the laser level, and the light passes through the Z0 position marks engraved on both sides of the front and rear edges of the blade forming mold.

[0012] Optionally, in the precise positioning method for the main blade root bushing as described above, step 4 includes: Step 41, determine the orientation of the propeller root bushing: based on the direction marking lines on the propeller root bushing, design all the direction marking lines of the propeller root bushing to face the same direction as the propeller blade. Step 42: Place the propeller root bushing with the Z0 reference line engraved into the propeller forming mold, and during the placement process, make the two Z0 reference lines of the propeller root bushing completely coincide with the laser lines projected on the propeller forming mold. Step 43: After confirming that the installation position of the propeller root bushing is correct, check and confirm that the lower end face of the propeller root bushing is completely in contact with the lower end face of the propeller forming mold.

[0013] Optionally, in the precise positioning method of the main blade root bushing as described above, for the same type of blade, the direction marking lines engraved on the root bushing in step 12 are all directed toward the root or toward the tip. In step 41, during the process of determining the orientation of the blade root bushing, the direction marking lines on the blade root bushings of the same model blade are simultaneously oriented towards the blade root direction or simultaneously towards the blade tip direction.

[0014] Optionally, the precise positioning method for the main blade root bushing as described above further includes: Step 5: For multiple blade root bushings of the same model, perform the positioning and installation operation for each blade root bushing by repeating steps 2 to 4 above; and during the installation of each blade root bushing, check the direction marking line and Z0 reference line.

[0015] The beneficial effects of this invention are as follows: This invention provides a precise positioning method for the main blade root bushing. On one hand, by machining auxiliary positioning references and blade positioning references, whose positions coincide with the blade reference positions, on the root bushing and the blade forming mold respectively, a laser level is used to project a laser line onto the blade forming mold that completely overlaps with the blade positioning reference on the blade forming mold, serving as the blade reference line for installation. This ensures that the auxiliary positioning reference of the root bushing completely coincides with the projected laser line on the blade forming mold. This achieves a correspondence between the blade positioning reference on the blade forming mold and the auxiliary positioning reference on the root bushing through the projected laser line, utilizing the straight-line propagation characteristic of laser lines to form an accurate root bushing installation reference. On the other hand, by using the direction marking lines on the root bushing to clearly define its orientation, the uncertainty of the root bushing's rotation in the Z-axis can be effectively eliminated, thereby improving the accuracy and stability of positioning. On the other hand, by using process methods to process auxiliary positioning references on the blade root bushing and blade positioning references on the blade forming mold, there is no need to make additional connecting tooling, which greatly reduces production costs and shortens the preparation cycle time. Attached Figure Description

[0016] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0017] Figure 1 A schematic diagram of the assembly angle between the root bushing of the main blade and the main blade. Figure 2 This is a schematic diagram illustrating the principle of the existing positioning method for the main blade root bushing. Figure 2 Figure a is a cross-sectional view, and Figure b is an external schematic diagram; Figure 3 This is a flowchart illustrating a method for precise positioning of the main blade root bushing, as provided in an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of the Z0 datum line and direction marking line machined in the inner wall of the blade root bushing using the precise positioning method for the main blade root bushing provided in this embodiment of the invention. Figure 5 This is a positioning diagram illustrating the installation of the propeller root bushing using the precise positioning method provided in this embodiment of the invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0020] As explained in the background section, the blade root bushing has a 6° assembly angle with the blade. Therefore, when assembling the metal bushing at the blade root, the installation and positioning method of the metal bushing must be considered. Figure 2 The diagram shown is a schematic representation of the existing positioning method for the main blade root bushing. Figure 2 Figure a shows a cross-sectional view, and Figure b shows an external schematic diagram. Currently, the existing positioning method for the main blade root bushing uses both internal hole positioning and pin positioning. First, the individual root bushing is installed on the blade forming mold using internal hole positioning. However, since the internal hole of the root bushing is circular, as shown in Figure b... Figure 2 As shown, the bushing with inner hole positioning on one side of the propeller root is rotatable, meaning the inner hole positioning is insufficient. Therefore, a groove needs to be provided on the propeller root bushing, such as... Figure 2 By using the boss of the connecting fixture to hold the groove of the bushing, two propeller root bushings can be positioned simultaneously by a set of connecting fixtures, which can prevent the bushings from rotating and at the same time ensure the relative positional relationship of the two bushings.

[0021] However, the existing positioning method for the main blade root bushing requires the additional fabrication of connecting fixtures. For different models of main blades, fixtures need to be fabricated separately according to the inner hole and installation angle of the root bushing, which leads to a long manufacturing cycle and increased manufacturing costs for the main blades.

[0022] To address the aforementioned problems, embodiments of the present invention provide a precise positioning method for the main blade root bushing. The precise positioning method provided by the present invention effectively solves the problem of metal bushing position deviation in the prior art by introducing process means to increase auxiliary positioning reference.

[0023] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they may not be described again in some embodiments.

[0024] In the rotor systems of aircraft such as helicopters and drones, the connection between the blades and the rotor hub is crucial. A metal bushing (hereinafter referred to as the root bushing) is typically installed at the blade root to enhance structural strength and ensure stable operation of the transmission system. However, during actual assembly, due to the complex three-dimensional spatial relationship between the blade forming mold and the root bushing, relying solely on traditional positioning methods often makes it difficult to accurately determine the bushing's position, easily leading to installation deviations.

[0025] Figure 3 This is a flowchart illustrating a method for precisely positioning the root bushing of a main blade, as provided in an embodiment of the present invention. Figure 3 As shown, the precise positioning method for the main blade root bushing provided in this embodiment of the invention includes the following steps: Step 1: Machining the blade positioning reference on the blade forming mold; Step 2, machining auxiliary positioning references on the blade root bushing, including: machining auxiliary positioning references on the inner wall of the blade root bushing digital mold, wherein the machined auxiliary positioning references are aligned with the blade positioning references on the blade forming mold. Step 3: Use a laser level to project a laser line onto the blade forming mold as the blade reference line, and the projected blade reference line completely overlaps with the blade positioning reference on the blade forming mold. Step 4, Install the blade root bushing, including: Based on the blade reference line projected on the blade forming mold that completely overlaps with the blade positioning reference, install the blade root bushing, and make the auxiliary positioning reference of the blade root bushing completely coincide with the laser line projected on the blade forming mold.

[0026] This invention provides a method for precise positioning of the main blade root bushing. On one hand, auxiliary positioning references and blade positioning references, whose positions coincide with the blade reference positions, are machined on the root bushing and the blade forming mold, respectively. A laser level is used to project a laser line onto the blade forming mold that completely overlaps with the blade positioning reference on the mold, serving as the blade reference line. The root bushing is then installed, ensuring that the auxiliary positioning reference of the root bushing perfectly coincides with the projected laser line on the blade forming mold. This achieves a correspondence between the blade positioning reference on the blade forming mold and the auxiliary positioning reference on the root bushing through the projected laser line, utilizing the straight-line propagation characteristic of laser lines to form an accurate root bushing installation reference. On the other hand, the orientation of the root bushing is clearly defined using directional marking lines on it, effectively eliminating the uncertainty of the root bushing's rotation in the Z-axis, thereby improving the accuracy and stability of positioning. On the other hand, by using process methods to process auxiliary positioning references on the blade root bushing and blade positioning references on the blade forming mold, there is no need to make additional connecting tooling, which greatly reduces production costs and shortens the preparation cycle time.

[0027] In one implementation of the present invention, in step 1, the Z0 position mark of the blade is machined on the blade forming mold; in step 2, the auxiliary positioning reference machined on the inner wall of the blade root bushing digital mold includes the Z0 reference line and the direction marking line.

[0028] In this implementation method, step 2 includes: marking the Z0 position of the blade on both sides of the front and rear edges of the blade forming mold by machining, thereby marking the Z0 position on both sides of the front and rear edges of the blade forming mold.

[0029] It should be noted that the line connecting the Z0 position mark on both sides of the front and rear edges of the blade forming mold is the Z0 position of the blade.

[0030] In this implementation method, the Z0 datum line machined on the inner wall of the propeller root bushing die must be completely consistent with the Z0 datum of the propeller forming die. Step 1 includes the following steps: Step 11: Draw two symmetrical and parallel marking lines on the inner wall of the rotor root bushing CAD model as the Z0 reference lines of the rotor root bushing. This is used to ensure that the two Z0 reference lines on the rotor root bushing CAD model coincide with the Z0 position of the rotor blade during the subsequent positioning process. Step 12: By engraving directional marking lines on the inner wall of the blade root bushing, the directional marking lines are directed toward the blade root or blade tip during the installation and positioning process; the directional marking lines are parallel to the blade spanwise direction.

[0031] In one implementation of this invention, step 3 is further described as follows: A laser level is placed on one side of the blade forming mold, and the Z0 position line of the blade is used as the projection target. A laser line that completely overlaps with the Z0 position line of the blade is projected by the laser level, and the light passes through the Z0 position marks engraved on both sides of the front and rear edges of the blade forming mold.

[0032] In one implementation of this invention, step 4 may include: Step 41, determine the orientation of the propeller root bushing: based on the direction marking lines on the propeller root bushing, design all the direction marking lines of the propeller root bushing to face the same direction as the propeller blade. Step 42: Place the propeller root bushing with the Z0 reference line engraved into the propeller forming mold, and during the placement process, make the two Z0 reference lines of the propeller root bushing completely coincide with the laser lines projected on the propeller forming mold. Step 43: After confirming that the installation position of the propeller root bushing is correct, check and confirm that the lower end face of the propeller root bushing is completely in contact with the lower end face of the propeller forming mold.

[0033] It should be noted that, for the same type of blade, the direction markings engraved on the blade root bushing in step 12 all point towards the blade root or towards the blade tip. Correspondingly, in step 41, during the process of determining the orientation of the blade root bushing, the direction markings on the blade root bushings of the same type of blade simultaneously point towards the blade root or simultaneously towards the blade tip.

[0034] In one implementation of this invention, the installation process from steps 1 to 4 above only involves the installation of one blade root bushing. For the installation of blade root bushings of the same model, the operation of machining the blade positioning reference on the blade forming mold only needs to be performed once. Therefore, the repeated positioning and installation method for multiple blade root bushings of the same model blade is as follows: For each blade with multiple root bushings, the positioning and installation operation of each root bushing is carried out by repeating steps 2 to 4 above; and during the installation of each root bushing, the direction marking line and Z0 reference line need to be checked.

[0035] The following is an illustrative description of the implementation method for the precise positioning of the main blade root bushing provided in this embodiment of the invention, through an example.

[0036] Implementation Example 1 Example 1 provides a precise positioning method for the main blade root bushing. By adding specific process markings and combining precision measuring tools and standardized operating procedures, the installation accuracy of the metal bushing can be significantly improved, thereby ensuring a reliable connection between the blade and the hub. The precise positioning method for the main blade root bushing provided in this embodiment includes the following steps: Step 1: Machining the blade positioning reference on the blade forming mold The core objective of this step is to ensure that the Z0 reference line on the blade root bushing is completely aligned with the Z0 reference line in the blade forming mold. Machining is used to ensure the accurate positioning of the Z0 reference line between the blade forming mold and the blade root bushing, and the Z0 position of the blade is marked on both sides of the leading and trailing edges of the blade forming mold.

[0037] It should be noted that this step ensures that the blade root bushing to be installed and the mounting carrier (i.e., the blade forming mold) have the same positioning reference, thereby realizing the transfer of the installation reference.

[0038] Step 2: Machining auxiliary positioning datum on the propeller root bushing In this embodiment of the invention, the first step is to add positional markings to the inner wall of the digital model (i.e., the three-dimensional digital model) of the propeller root bushing according to design requirements. These positional markings include, but are not limited to, the Z0 datum line and direction marking lines. To ensure the accuracy of the positional markings, this embodiment of the invention uses computer-aided design software for precise calculations and sets relevant parameters based on actual processing requirements.

[0039] It should be noted that the Z0 position is one of the key reference positions of the blade. When marking the Z0 reference line on the blade root bushing CAD model, it must be ensured that the marked Z0 reference line is completely consistent with the Z0 reference of the blade forming mold. Considering the convenience of subsequent processing and measurement, two symmetrical parallel marking lines are selected on the inner wall of the blade root bushing CAD model as the Z0 reference lines of the blade root bushing; during the positioning process of the blade root bushing, these two Z0 reference lines are made to coincide with the Z0 position of the blade.

[0040] To ensure the correct and unique installation angle of the propeller root bushing, a directional marking line is engraved on the inner wall of the bushing. During installation and positioning, this directional marking line should face either the propeller root or the propeller tip. It should be noted that for a given model of propeller blade, the direction of this directional marking line should be consistent, and specifically, this directional marking line should be a marking line parallel to the spanwise direction of the propeller blade.

[0041] like Figure 4 The diagram shows the Z0 datum line and direction marking line machined in the inner wall of the blade root bushing using the precise positioning method provided in this embodiment of the invention.

[0042] Step 3: Project the Z0 baseline onto the blade forming die using a laser level. To facilitate subsequent installation, a clearly visible Z0 reference line needs to be projected onto the blade forming mold. The specific steps for this are as follows: A laser level is placed on one side of the blade forming mold, with the Z0 position line of the blade as the projection target. A laser line that completely overlaps with the Z0 position line of the blade is projected by the laser level. This laser line passes through the Z0 position marks engraved on both the front and rear edges of the blade forming mold. By placing the blade root bushing using the laser line projected onto the surface of the blade forming mold, the Z0 reference line on the blade root bushing can be made to overlap with the laser line. This achieves the association between the Z0 position on the blade forming mold and the Z0 reference line on the blade root bushing through the laser line.

[0043] This step uses the laser line of a laser projector to associate the Z0 position mark on the blade forming mold with the Z0 reference line on the blade root bushing, thus utilizing the characteristic of laser lines to propagate in a straight line to form an accurate bushing installation reference.

[0044] Step 4: Install the propeller root bushing After the first three steps of preparation, this step involves the actual installation of the propeller root bushing, such as... Figure 5 The diagram shown illustrates the positioning of the propeller root bushing using the precise positioning method provided in this embodiment of the invention. The installation process of the propeller root bushing includes the following specific steps: S1. Determine the orientation of the propeller root bushing: The first step in installing the propeller root bushing is to determine its orientation. Because the propeller blade structure requires high accuracy, ensuring the correct orientation of the propeller root bushing is crucial. To ensure correct installation, the following methods should be used: Application of directional marking lines: The directional marking lines on the propeller root bushing should point towards the root or tip of the propeller blade profile. Operators can confirm this by visual inspection or using angle measuring tools.

[0045] S2, Reference Alignment: Place the machined blade root bushing with the Z0 reference line into the blade forming mold. During placement, the Z0 reference line of the blade root bushing must be completely aligned with the laser line on the blade forming mold (i.e., the Z0 position of the blade).

[0046] S3, Fixing measures: After confirming that the installation position of the blade root bushing is correct, check whether the lower end face of the blade root bushing is completely in contact with the blade forming mold.

[0047] After the blade root bushing is positioned and installed, the assembly of internal blade parts and the shaping of unidirectional prepreg tape can be carried out. Since these operations will involve contact with the blade root bushing, the accuracy of the blade root bushing installation position needs to be further checked after the internal operations are completed.

[0048] Step 5: Repeat the installation process For the installation of multiple root bushings in each blade, the above steps must be followed independently. Although the steps are the same, the direction marking line and Z0 datum line must be checked again before each installation to avoid cumulative errors.

[0049] It should be noted that for multiple blade root bushings of the same model, during repeated installation, steps 2 to 4 only need to be repeated, that is, the step of machining the blade positioning reference on the blade forming mold only needs to be performed once; for multiple blade root bushings of different models, step 1 needs to be performed during the first installation, that is, each model of blade corresponds to a set of blade forming molds, and the operation of machining the blade positioning reference on the blade forming mold only needs to be performed once.

[0050] Implementation Example 2 During the installation of the propeller root bushing for a certain aircraft model, the precise positioning method for the main propeller root bushing provided in this embodiment of the invention is adopted, specifically including the following steps: This Example 2 details a novel process for installing rotor root bushings on a certain type of helicopter rotor blade. This method effectively improves the assembly accuracy of the rotor root bushings by introducing precise marking and positioning techniques. The entire installation process includes six key steps, each meticulously designed and rigorously controlled to ensure that the final product quality meets design requirements.

[0051] Step 1: Machining the Z0 position mark on the blade forming die Accurately locating and marking the Z0 position on the blade forming mold is a crucial step in the entire installation process. Specific operations include: using a coordinate measuring machine or other precision measuring equipment to determine the Z0 reference point position of the blade forming mold according to design requirements. After confirming that the position is correct, marking lines are made on both sides of the leading and trailing edges of the blade forming mold. Leading edge side markings: Use scribing lines with a depth of 0.5 mm; Trailing edge markings: also using scribing lines of the same depth; After marking, the Z0 position lines need to be checked one by one using a high-precision detection tool, and the measurement data should be recorded.

[0052] Step 2: Marking lines on the inner wall of the impeller bushing In this step, the first step is to precisely machine the marking lines on the inner wall of the propeller root bushing. The specific operation is as follows: Based on the assembly position requirements provided in the design drawings, determine the specific position of the inner wall of the propeller root bushing's digital model. After confirmation, use a laser engraving machine or mechanical engraving tool to precisely machine the marking lines on the inner wall. Special attention should be paid to the parallel line of the Z0 coordinate (this line is used to determine the Z-axis zero point position during subsequent installation) and the direction line towards the spanwise direction (used to determine the correct rotation angle of the propeller root bushing during installation).

[0053] In practice, the depth of the marking line is controlled to be below 0.5mm, and this depth has been rigorously verified. The markings should be shallow enough to allow for easy removal during subsequent CNC machining, yet deep enough to ensure they are clearly visible for later positioning. After this step, check the integrity of the markings to ensure all marks are clearly legible.

[0054] Step 3: Projection of Z0 direction and spanwise straight lines on the blade forming mold This step achieves precise positioning using optical projection methods: First, fix the blade forming mold and ensure it is level. Using a laser projector or level, project a reference straight line onto the surface of the blade forming mold. This line must perfectly coincide with the Z0 reference lines marked in step two. Then, project a ray perpendicular to this projection, which is the blade spanwise marking line. By adjusting the angle and position of the projector, ensure that the projected line coincides with the tooling marking line, thus ensuring the accuracy of the Z0 and spanwise marking lines. This process requires repeated measurements and fine-tuning until all marking points are precisely aligned. After completion, use a level again to check the flatness of the entire projected surface and record the relevant data.

[0055] Step 4: Determining and fixing the orientation of the propeller root bushing In this step, it is crucial to ensure the correct orientation of the propeller root bushing. Based on the direction lines marked in step two, determine the rotation direction of the propeller root bushing: the side with the direction marking line must face the propeller root direction, and this directional deviation should be controlled within ±0.5°. During installation, we adopted the following auxiliary measures to ensure correct orientation: real-time monitoring using an angle measuring instrument and reconfirming the orientation after each adjustment.

[0056] After confirming everything is correct, use a special clamp to secure the propeller root bushing. During the securing process, maintain slight pressure to prevent any displacement. Once secured, double-check the position of all marked lines and record the relevant data.

[0057] Step 4: Installation and positioning of the propeller root bushing This step is crucial for accurately installing the prepared propeller root bushing into the propeller forming mold. The CNC-machined propeller root bushing, marked with a Z0 line, is placed inside the propeller forming mold. It is essential to ensure that the Z0 position of the bushing is precisely aligned with the Z0 reference point of the forming mold, with the bushing's positional deviation controlled within ±0.05mm. To achieve precise positioning, the following auxiliary measures are employed: high-precision locating pins are used for initial fixing, and a three-dimensional coordinate measuring machine is used to monitor positional changes in real time during the installation process.

[0058] Special attention must be paid to the rotation direction of the bushing during installation. It is essential to ensure that the Z0 mark line is pointing in the correct direction. After initial positioning, the installation angle of the bushing must be checked again using an electronic level, and any necessary adjustments made.

[0059] Step 6: Repeating and Quality Control of Propeller Root Bushing Installation Following the same method, we completed the installation of all propeller root bushings for this aircraft model. In each step, the following quality control measures were strictly implemented: 1. After completing the installation of the propeller root bushing, conduct a quality inspection: use an electronic level to check the angular deviation. 2. All data must meet the design requirements: 3. A strict rework process has been established for any substandard installation results: Problems should be recorded promptly and their causes analyzed. Reinstallation should only proceed after ensuring that corrective measures are effective.

[0060] 4. After installation, a final overall inspection is required. The inspection method is as follows: A laser scanner was used to detect the relative positions between each propeller root bushing.

[0061] Through the above six standardized operating procedures, high-precision installation of the propeller root bushing of this model was successfully achieved; each step underwent strict quality control to ensure the high quality and high reliability of the product.

[0062] Throughout the process, a comprehensive testing system and traceability mechanism were established. All key parameters were recorded in detail and could be retrieved for analysis at any time. This not only ensured the quality of the current batch of products but also provided valuable data support for subsequent improvements.

[0063] While the embodiments disclosed in this invention are as described above, they are merely illustrative of the embodiments to facilitate understanding of the invention and are not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for precise positioning of the main blade root bushing, characterized in that, include: Step 1: Machining the blade positioning reference on the blade forming mold; Step 2, machining auxiliary positioning references on the blade root bushing, including: machining auxiliary positioning references on the inner wall of the blade root bushing digital mold, wherein the machined auxiliary positioning references are aligned with the blade positioning references on the blade forming mold. Step 3: Use a laser level to project a laser line onto the blade forming mold as the blade reference line, and the projected blade reference line completely overlaps with the blade positioning reference on the blade forming mold. Step 4, Install the blade root bushing, including: Based on the blade reference line projected on the blade forming mold that completely overlaps with the blade positioning reference, install the blade root bushing so that the auxiliary positioning reference of the blade root bushing completely coincides with the laser line projected on the blade forming mold.

2. The precise positioning method for the main blade root bushing according to claim 1, characterized in that, In step 1, the Z0 position mark of the blade is machined on the blade forming mold; In step 2, the auxiliary positioning references machined on the inner wall of the propeller root bushing digital model include the Z0 reference line and the direction marking line.

3. The method for precise positioning of the main blade root bushing according to claim 2, characterized in that, Step 1 includes: The Z0 position of the blade is marked on both sides of the front and rear edges of the blade forming mold by machining, thus marking the Z0 position on both sides of the front and rear edges of the blade forming mold.

4. The precise positioning method for the main blade root bushing according to claim 3, characterized in that, In step 1, the Z0 datum line machined on the inner wall of the blade root bushing die is completely consistent with the Z0 datum of the blade forming die; step 1 includes: Step 11: Draw two symmetrical and parallel marking lines on the inner wall of the rotor root bushing CAD model as the Z0 reference lines of the rotor root bushing. This is used to ensure that the two Z0 reference lines on the rotor root bushing CAD model coincide with the Z0 position of the rotor blade during the subsequent positioning process. Step 12: By engraving directional marking lines on the inner wall of the blade root bushing, the directional marking lines are directed toward the blade root or blade tip during the installation and positioning process; the directional marking lines are parallel to the blade spanwise direction.

5. The precise positioning method for the main blade root bushing according to claim 4, characterized in that, Step 3 includes: A laser level is placed on one side of the blade forming mold, and the Z0 position line of the blade is used as the projection target. A laser line that completely overlaps with the Z0 position line of the blade is projected by the laser level, and the light passes through the Z0 position marks engraved on both sides of the front and rear edges of the blade forming mold.

6. The method for precise positioning of the main blade root bushing according to claim 5, characterized in that, Step 4 includes: Step 41, determine the orientation of the propeller root bushing: based on the direction marking lines on the propeller root bushing, design all the direction marking lines of the propeller root bushing to face the same direction as the propeller blade. Step 42: Place the propeller root bushing with the Z0 reference line engraved into the propeller forming mold, and during the placement process, make the two Z0 reference lines of the propeller root bushing completely coincide with the laser lines projected on the propeller forming mold. Step 43: After confirming that the installation position of the propeller root bushing is correct, check and confirm that the lower end face of the propeller root bushing is completely in contact with the lower end face of the propeller forming mold.

7. The method for precise positioning of the main blade root bushing according to claim 6, characterized in that, For the same type of blade, the directional markings engraved on the blade root bushing in step 12 all point towards the blade root or towards the blade tip. In step 41, during the process of determining the orientation of the blade root bushing, the direction marking lines on the blade root bushings of the same model blade are simultaneously oriented towards the blade root direction or simultaneously towards the blade tip direction.

8. The method for precise positioning of the main blade root bushing according to any one of claims 1 to 7, characterized in that, Also includes: Step 5: For multiple blade root bushings of the same model, perform the positioning and installation operation for each blade root bushing by repeating steps 2 to 4 above; and during the installation of each blade root bushing, check the direction marking line and Z0 reference line.

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