Helicopter composite blade root thickness and length digital detection method

Abstract

The present application belongs to the technical field of digital testing of helicopter rotor system, and relates to a kind of digital detection method for thickness and length of helicopter composite blade root.The method comprises: determining the measurement area of the blade root or length;according to different measurement areas, using a helicopter composite blade digital comprehensive detection system to measure the corresponding blade root thickness or blade length;the helicopter composite blade digital comprehensive detection system comprises: a special positioning tool, a mobile rail, a line laser measuring instrument, a measurement system and a robot auxiliary device.

Description

Technical Field

[0001] This invention belongs to the field of digital testing technology for helicopter rotor systems, and relates to a digital detection method for the root thickness and span of helicopter composite rotor blades. Background Technology

[0002] After helicopter rotor blades are molded, it is necessary to inspect the blade span and the thickness of the root region. The measurement accuracy requirements are relatively high. Currently, manual measurement using traditional materials and tools mainly has the following problems:

[0003] 1. The measurement work is extensive and highly repetitive, requiring manual operation, which is arduous, inefficient, and cannot meet the batch production requirements of various models.

[0004] 2. Manual inspection results in poor consistency and makes it difficult to guarantee product quality, affecting the pass rate of parts and the assembly cycle;

[0005] 3. In terms of data collection, manual recording and paper-based media are still the main methods, which affects data management and transmission and results in poor traceability. Summary of the Invention

[0006] Purpose of the invention: To study a robot-based intelligent inspection technology for digital measurement of blade span and thickness of the blade root defined area, in order to solve the problems of manual inspection of large components and mass-produced parts, improve measurement accuracy and efficiency, and reduce measurement deviations caused by human factors.

[0007] Technical solution:

[0008] A method for digitally detecting the thickness and span of the root of a helicopter composite rotor blade is provided, the method comprising:

[0009] Determine the measurement area for the blade root or span;

[0010] Depending on the measurement area, the corresponding blade root thickness or blade span is measured using a digital integrated inspection system for helicopter composite blades.

[0011] The digital integrated inspection system for helicopter composite rotor blades includes: a dedicated positioning fixture, a moving ground rail, a line laser measuring instrument, a measuring system, and a robot-assisted device.

[0012] The specialized positioning fixture and the mobile ground rail are rigidly connected to form an integrated platform; the robot auxiliary device is installed on the mobile ground to achieve precise long-distance movement; the line laser measuring instrument is used to scan the surface of the object's blade, and in conjunction with the measurement system, the measured data is converted into a planar graphic and the required relevant parameters are calculated; the line laser measuring instrument is installed on the robot auxiliary device, and in conjunction with the mobile ground rail, it can achieve long-distance or multi-directional scanning.

[0013] Furthermore, the measurement area at the blade root is the triangular region formed near the root of the blade at the midpoint between the two bushing holes; the triangular region is a hard plate, and the flatness of the data is relatively high.

[0014] Furthermore, a digital integrated inspection system for helicopter composite rotor blades is used to measure the corresponding blade root thickness or blade span, including:

[0015] The blade to be measured is placed on a special positioning fixture, the measurement system is started, and the moving ground rail carries the measuring body laser measuring instrument to move horizontally at a constant speed to continuously measure the blade root part: during the measurement, point data from position a to position b on the blade root plane and point data of the two bushing holes at the blade root are collected; where position a is the blade root position and position b is the blade tip position.

[0016] Furthermore, continuous measurements were performed on the blade root section, including:

[0017] ① Obtain point data of blade profile: After arranging the blade shape at equal intervals under the vertical laser beam, obtain the corresponding values ​​in the coordinate system.

[0018] The purpose of point data on the blade profile:

[0019] b. Based on the collected contour point data, place them into the spatial coordinate system determined in the detection system, connect these points to form a connecting line, and find the spatial base coordinates corresponding to the connecting line.

[0020] b. Using the formed line, compare the angle formed by the approach line segment and the normal of the measuring body laser measuring instrument. This angle is the angle formed between the Z0 position of the blade and the measuring body laser measuring instrument after the blade is placed in the special positioning fixture. The Z0 position is the 0° position of the blade with higher precision and no deflection.

[0021] c. Determine the data threshold for the propeller root: When the bushing hole convex edge position is not reached, the process of using the formed connection will be continuously recorded, and the corresponding change amplitude value will be obtained from the record. From this, an acceptable range can be selected.

[0022] e. Before reaching the edge of the bushing hole, find an average value from the values ​​in segment ab and use it to calculate the position inside the bushing hole;

[0023] Determine the bushing edge value: median value + height of a protrusion dx, where dx is a fixed value in blade production;

[0024] ② Determine the value of the bushing edge collapse zone: When a value of 0 or non-existent appears in the measurement data area, it indicates that there may be irregular values ​​in the measurement data. Compare it with the result of bushing edge zone + bushing outer radius to accurately determine the Z0 position, and record the ground rail value X at this position.

[0025] ③ After the ground track reaches position X, collect data from the blade's AB surface. Simultaneously, combine the above transformation process and threshold to filter out the constituent data within the triangle; the mean value of the data within the A surface forms (x1, y1, z1) and the mean value of the data within the B surface forms (x2, y2, z2). Finally, use the formula [(x1-x2)] to calculate the mean value of the data within the A surface. 2 +(y1-y2) 2 +(z1-z2) 2 The thickness value is calculated using 1 / 2;

[0026] ④ Based on the above content and for ease of use in subsequent calculations, the following data needs to be saved: Z0 ground rail position, deflection angle of the blade after it is placed in the fixture, basic data of linear transformation, threshold, and blade root thickness value.

[0027] Furthermore, the measurement methods include fixed-point static measurement and dynamic measurement.

[0028] Furthermore, a digital integrated inspection system for helicopter composite rotor blades is used to measure the corresponding blade root thickness or blade span, including:

[0029] The midpoint of the blade is set as a fixed point, and the measurement process becomes dynamic when the ground rail reaches the blade tip transition position Z3.

[0030] Static measurement: The measurement begins when the ground rail stops at the position where the blade needs to be measured, allowing the measurement system to transition from a dynamic to a static and stable state.

[0031] Dynamic measurement: A measurement method in which the measuring object moves horizontally and continuously at a constant speed along a ground rail;

[0032] The dynamic measurement moves from Z3 to the blade tip Z4. The data from the detection system will have a process where the range of data values ​​continuously decreases until the data disappears completely. The moment when the data disappears is when the blade reaches its final end.

[0033] Based on the above data, calculate the ground rail value of blade span = Z0 - final end ground rail value.

[0034] Furthermore, the location data of the ground track changes in real time as the measurement location changes.

[0035] Furthermore, the accuracy of position measurement data is determined by the PWM duty cycle, the number of rotating teeth of the mechanical gear, and the unit tooth linear distance.

[0036] Beneficial effects: This testing method requires simple positioning and fixing of the product (blade), eliminating the need for high-precision clamping and positioning. Simply place the product on a dedicated positioning fixture. The entire measurement process is a one-button operation, reducing human contact with the product, improving operational efficiency, and avoiding inaccuracies caused by human factors. Attached Figure Description

[0037] Figure 1 This is an axial view of a digital integrated testing system for helicopter composite rotor blades.

[0038] Figure 2 This is a top view of the blades;

[0039] Figure 3 This is a cross-sectional view of the propeller root;

[0040] Figure 4 This is a diagram of a bushing. Figure 1 ;

[0041] Figure 5 This is a diagram of a bushing. Figure 2 ;

[0042] Figure 6 This is a schematic diagram of the blade test coordinate position. Detailed Implementation

[0043] like Figure 1 As shown, a digital integrated inspection system for helicopter composite rotor blades is provided, comprising: a dedicated positioning fixture 1, a mobile ground rail 2, a line laser measuring instrument 3, a measuring system 4, and a robot auxiliary device 5.

[0044] The dedicated positioning fixture 1 and the moving ground rail 2 are rigidly connected to form an integral platform; the robot auxiliary device 5 is installed on the moving ground rail 2 to achieve precise long-distance movement; the line laser measuring instrument 3 is used to scan the surface of the object's blade, and in conjunction with the measuring system 4, converts the measured data into a planar graphic and calculates the required relevant parameters; the line laser measuring instrument 3 is installed on the robot auxiliary device 5, and in conjunction with the moving ground rail 2, it can achieve long-distance or multi-directional scanning.

[0045] The dedicated positioning fixture 1 consists of a first leveling foot 11, a fixture platform 12, and contour positioning blocks 13. By adjusting the nuts on the first leveling foot, the height of the multiple contour positioning blocks on the fixture platform can be adjusted to be on the same horizontal plane. This ensures that after the blade of the product being tested is placed on the positioning blocks, the product is placed horizontally and remains in a free state, preventing bending of the product surface after placement. The contour positioning blocks are specially customized according to the shape of the product's outer surface, and the parts in contact with the product are made of "soft" material to avoid scratching the product's outer surface.

[0046] The mobile track 2 consists of a second leveling foot 21, a platform 22, a gear transmission mechanism 23, and a servo system 24. The entire platform is manufactured using a one-piece welded frame to prevent a decrease in the overall accuracy of the mobile track due to segmented splicing. Simultaneously, the gear and rack in the gear transmission mechanism employ helical gear meshing, reducing the meshing clearance between the gear and rack, thereby providing repeatability accuracy for movement. The platform's levelness can be adjusted by adjusting the nuts on the leveling feet. Furthermore, it is rigidly connected to the dedicated positioning fixture 1, ensuring that the adjustment planes of both are parallel and on the same horizontal level through the leveling feet.

[0047] The line laser measuring instrument 3 is a mature standard product on the market, capable of simultaneously scanning and measuring a certain length. For example, if the maximum length of a single cross-section of a product's blade is 580mm, the selected line laser measurement length must be greater than 580mm to measure a section of the cross-section in one go and collect relevant data for the entire cross-section. Conversely, if the measurement length is less than 580mm, multiple data acquisitions and stitching are required, which increases the cumulative error from multiple acquisitions.

[0048] Measurement system 4 is a customized measurement software used in conjunction with line laser measuring instrument 3. This system employs two sets of line lasers, each capable of simulating half of the shape. The measurement system collects data from each light source in the line lasers, combining and simulating the measured shape. Then, an algorithm calculates the relevant parameters required for the shape.

[0049] The robot-assisted device 5 is used to hold the line laser measuring instrument 3 and is mounted on the moving ground rail 2. It can measure any position of the product to be measured, as needed.

[0050] The measurement steps of this invention are as follows:

[0051] Step 1: Product installation and positioning: Use a crane or similar method to place the product (blade) onto the contour positioning block on the tooling along the guide block, thus completing the positioning and clamping of the product.

[0052] Step Two: On the computer interface, open the customized measurement software, click the "One-Click Measurement" button, and then wait for the system to automatically complete the measurement. During the automatic measurement process, the measurement software will display the required data values ​​and results.

[0053] Step 3: After the equipment completes the automatic measurement, the measurement data can be automatically stored. Manual personnel can export the measurement data (EXCEL spreadsheet data) from the measurement software and observe and analyze the measurement data.

[0054] Step 4: Use a crane or similar method to remove the product (blade) to complete this measurement task.

[0055] Methods for measuring blade root thickness and span in a research and development measurement system:

[0056] • Method for measuring the thickness of the paddle root

[0057] 1. Determining the measurement area at the paddle root:

[0058] The measurement area is generally the part near the root of the blade, located between the two bushing holes (e.g.) Figure 6 The triangular area shown is a hard plate with relatively high flatness.

[0059] 2. Method for measuring the thickness of the impeller root:

[0060] The blade to be measured is placed on a special positioning fixture 1. The measurement system is started, and the moving ground rail 2 moves horizontally and uniformly with the measuring body laser measuring instrument 3 to perform continuous measurement of the blade root section (from position a on the blade root plane to position b on the blade root plane). During the measurement, point data ① of the blade ab contour and point data ② of the two bushing holes at the blade root are collected:

[0061] ① The point data of the blade profile, i.e., the blade shape, is arranged at equal intervals under a vertical laser beam.

[0062] Then correspond to the corresponding values ​​in the coordinate system.

[0063] The main function of point data for blade profile:

[0064] a. Based on the collected contour point data, place them into the spatial coordinate system determined in the measurement body, connect these points to form a line, and find the spatial base coordinates corresponding to the line.

[0065] b. Using the formed line, compare the angle formed by the approximate line segment and the normal of the measuring equipment. This angle is the angle after the blade is placed in the special positioning fixture 1. Figure 2 The angle formed between the blade Z0 position (Z0 position is the high-precision undeflected 0° position in the blade) and the measuring body line laser measuring instrument 3;

[0066] c. Determination of the data threshold for the propeller root (when the bushing hole convex edge position is not reached, the process in a will continue to be recorded, and the corresponding change amplitude value will be obtained from the record, from which an acceptable range will be selected).

[0067] d. Use the generated connections to display the graphics on the PC in real time;

[0068] e. Before reaching the edge of the bushing hole, find an average value from the values ​​in segment ab and use it to calculate the position inside the bushing hole.

[0069] Determination of bushing edge values: average value + height of a protrusion dx (fixed value in blade production)

[0070] (Constant value) (This data can be reliably collected)

[0071] ② Determination of the value of the bushing edge collapse zone: When a value of 0 or non-existent appears in the measurement data area.

[0072] Determining the Z0 baseline: f. When the data region contains the maximum range of 0 or a non-existent value.

[0073] g, Bushing edge area + r (outer diameter radius of the bushing) (determined value)

[0074] h. Compare and analyze f and g above (irregular values ​​may appear in f, which need to be compared with the data in g to accurately determine the Z0 position), and record the ground orbit value X at that position;

[0075] ③ After the ground track reaches position X, collect data from surfaces A and B. Simultaneously, combine the aforementioned transformation process and threshold to filter out the constituent data within the triangle. The mean value of the data within surface A forms (x1, y1, z1), and the mean value of the data within surface B forms (x2, y2, z2). Finally, use the formula [(x1-x2)] to calculate the mean value of the data within surface A. 2 +(y1-y2) 2 +(z1-z2) 2 ]1 / 2 calculate the thickness value

[0076] ④ Based on the above content and for ease of use in subsequent calculations, the following data needs to be saved: Z0 ground rail position, deflection angle of the blade after it is placed in the fixture, basic data of linear transformation, threshold, and blade root thickness value.

[0077] • Method for calculating span

[0078] 1. The measurement of the midpoint is a fixed-point static measurement. When the ground rail reaches the Z3 position of the blade, it will become a dynamic measurement process.

[0079] Static measurement: The measurement begins when the ground rail stops at the position where the blade needs to be measured, allowing the measurement system to transition from a dynamic to a static and stable state.

[0080] Dynamic measurement: A measurement method in which the measuring object moves horizontally and continuously at a constant speed along a ground rail;

[0081] Conversion between blade position and actual track position:

[0082] Assume that the blade extension value increases from the front end to the rear end after being fixed in the special positioning fixture 1, and the ground rail movement value increases from the rear end to the front end (the directionality of the ground rail position is fixed).

[0083] like Figure 6As shown, the position value of the propeller blade at position Z0 → the ground rail [X(mm)]

[0084] The blade position description (Z****), where **** represents the distance extended backward in a straight line from position Z0. Example: Transformation of blade Z3 with the actual position of the ground track:

[0085] Let the position of the propeller blade at position Z0 be the value of the ground rail (7338mm).

[0086] Therefore, the value of the ground rail position corresponding to blade Z3 is 7100, and 7338 - 7100 = 238 (mm).

[0087] The position data of the ground rail changes in real time as the measurement position changes and is displayed on the PC window interface. Meanwhile, the accuracy of the position measurement data is determined by the PWM duty cycle, the number of teeth of the mechanical gear, and the unit tooth straight distance.

[0088] 2. Dynamic measurement moves from Z3 to Z4. The data of the measuring body will have a process of continuously decreasing data value range until the data disappears completely (determined by the intuitive characteristics of the blade shape). When the data disappears, it means that the blade has reached the final end.

[0089] Z0 ground rail value - final end ground rail value = blade span.

Claims

1. A method for digitally detecting the thickness of the root of a helicopter composite rotor blade, characterized in that, The method includes: Determine the measurement area for the blade root thickness; the measurement area for the blade root thickness is the triangular area formed near the root of the blade at the midpoint between the two bushing holes. Based on the measurement area of ​​the rotor root thickness, the corresponding rotor root thickness is measured using a digital integrated inspection system for helicopter composite rotor blades. The helicopter composite rotor blade digital integrated inspection system includes: a dedicated positioning fixture, a mobile ground rail, a line laser measuring instrument, a measuring system, and a robot-assisted device; The dedicated positioning fixture and the moving ground rail are rigidly connected to form an integral platform; the robot auxiliary device is installed on the moving ground rail to achieve precise long-distance movement; the line laser measuring instrument is used to scan the blade surface, and in conjunction with the measuring system, converts the measured data into a planar graphic and calculates the required relevant parameters; the line laser measuring instrument is installed on the robot auxiliary device, and in conjunction with the moving ground rail, it can achieve long-distance or multi-directional scanning. The corresponding rotor root thickness was measured using a digital integrated inspection system for helicopter composite rotor blades, including: The blade to be measured is placed on a special positioning fixture, the measurement system is started, and the moving ground rail carries the measuring body line laser measuring instrument to move horizontally at a constant speed to continuously measure the blade root part. During the measurement, point data from position a on the blade root plane to position b on the blade root plane, as well as point data from the two bushing holes at the blade root, were collected. Continuous measurements were performed on the blade root section, including: ① Obtain point data of the blade profile and form a line based on the profile point data to determine the deflection angle, blade root data threshold, bushing hole position, and bushing edge value after the blade is placed in a special positioning fixture. ② When a value of 0 or non-existent appears in the measurement data area, the bushing edge collapse area is determined. When a value of 0 or non-existent appears in the maximum range, the Z0 baseline is determined. The Z0 baseline is compared with the sum of the bushing edge area and the bushing outer diameter radius to accurately determine the Z0 position, and the ground rail value X at that position is recorded. ③ After the ground rail reaches position X, collect the data of the blade AB surface, filter out the composition data within the triangular area, and calculate the thickness value; ④ Save the ground rail position of Z0, the deflection angle of the blade after it is placed in the special positioning fixture, the blade root data threshold, and the blade root thickness value.

2. The method according to claim 1, characterized in that, The triangular area is a hard plate with relatively high flatness of data.

3. The method according to claim 1, characterized in that, The digital integrated testing system for helicopter composite rotor blades can also measure blade span. Methods for measuring blade span include: Determine the measurement area for blade span; Based on the measurement area of ​​the blade span, the corresponding blade span is measured using a digital integrated testing system for helicopter composite blades. The methods for measuring blade span include fixed-point static measurement and dynamic measurement.

4. The method according to claim 3, characterized in that, The corresponding blade span was measured using a digital integrated testing system for helicopter composite rotor blades, including: The midpoint of the blade is set as a fixed point, and the measurement switches to dynamic measurement when the ground rail reaches the blade tip transition position Z3. The dynamic measurement moves from Z3 to the blade tip Z4, and when the data completely disappears, it is recorded as the final end of the blade. Calculate the blade span = Z0 ground rail value - final end-rail value.

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