Method for high-precision iterative detection of propeller by three-coordinate measuring machine

Abstract

The invention relates to a method for high-precision iterative detection of a propeller by a three-coordinate measuring machine. The method comprises a positioning reference establishment module, a propeller overall evaluation module and an iterative measurement module. The positioning reference establishing module establishes a precise coordinate system of the propeller through three stages of coarse positioning, semi-precise positioning and precise positioning, and precise positioning of the reference is achieved. The propeller overall evaluation module measures blade section line data under a precise coordinate system, and evaluates the blade position offset error and the forward and backward inclination state. And the iterative measurement module is used for carrying out iterative measurement on the rotation angle error of the guide edge and each radius blade based on the measurement data. The method effectively solves the problems that in propeller manufacturing, the benchmark is difficult to accurately determine, the paddle assembly distribution uniformity difference is large, and the paddles incline front and back, the manufacturing precision and stability are improved, and technical support is provided for batch production of propellers.

Description

Technical Field

[0001] The present invention relates to the technical field of propeller measurement, in particular to a method for high-precision iterative detection of a propeller using a three-coordinate measuring machine. Background Art

[0002] The current three-dimensional coordinate measurement process first performs a detailed measurement of the blade's outer contour, followed by positioning measurement based on this. This process results in each blade being evaluated as an independent entity, while ignoring the propeller's overall structural status. Specifically, during the complex processing and assembly process, due to various factors, the positioning of each blade on the rotating surface is likely to be inconsistent, which further leads to unstable performance of the propeller during mass production.

[0003] Furthermore, during the machining process, there is often a significant gap between the actual generated surface and the initially designed surface. When this gap exceeds a certain range, it can lead to a significant increase in the measurement error of the guide edge, thus affecting the overall measurement accuracy and product quality.

[0004] To address this issue, an innovative method has been proposed and applied in practice: iterative calculations to accurately measure and adjust the actual blade position. This method not only effectively reduces measurement errors caused by large surface variations, but also improves the precision and stability of propeller manufacturing, providing strong technical support and assurance for mass production.

[0005] To this end, we propose a method for high-precision iterative inspection of propellers using a three-dimensional coordinate measuring machine. Summary of the Invention

[0006] To address the shortcomings of the aforementioned existing production technologies, the applicant has developed a method for high-precision iterative propeller inspection using a three-dimensional coordinate measuring machine. This method establishes a precise propeller coordinate system through three stages: coarse positioning, semi-precise positioning, and precise positioning, achieving precise positioning of the propeller's reference. Furthermore, a propeller overall assessment module evaluates blade position offset error and fore-aft tilt, ensuring overall propeller performance. Furthermore, an iterative measurement module iteratively measures leading edge and blade rotation angle errors, improving measurement accuracy and machining quality.

[0007] The technical solutions adopted in the present invention are as follows:

[0008] A method for high-precision iterative detection of a propeller using a three-coordinate measuring machine, comprising:

[0009] Positioning reference establishment module, used to establish the precise coordinate system of the propeller through three stages: coarse positioning, semi-precise positioning and precise positioning;

[0010] A propeller overall evaluation module, connected to the positioning reference establishment module, is used to measure the profile data of the blade in a precise coordinate system and evaluate the blade position offset error and fore-aft tilt state;

[0011] an iterative measurement module, connected to the propeller overall evaluation module, for iteratively measuring the leading edge and measuring the rotation angle error of blades of each radius based on the measurement data;

[0012] In the rough positioning stage, the digital model and the actual workpiece are preliminarily aligned by fitting the approximate position of the propeller in the three-coordinate basic coordinate system;

[0013] In the semi-precise positioning stage, the pressure surface and suction surface profile values at a specific radius of the blade are scanned to construct a curvilinear coordinate system consisting of the suction surface curve and the pressure surface curve, thereby determining the Z-axis height and circumferential direction.

[0014] In the precise positioning stage, the propeller shaft hole is measured and combined with a semi-precise positioning coordinate system to determine the X and Y axis positions and limit the rotational freedom to form a precise positioning coordinate system.

[0015] As a further improvement of the above technical solution:

[0016] In the coarse positioning stage, the point fitting is performed by selecting spatial points on the digital model to align with the actual workpiece blade, and the established coordinate system can only achieve rough alignment of the propeller position.

[0017] During the semi-precise positioning stage, when scanning and measuring the profile values of the pressure and suction surfaces at a specific radius of the blade (e.g., 0.7R), the actual Z-axis height is calculated by aligning the machining allowances of the pressure and suction surfaces with the theoretical model values.

[0018] During the precise positioning stage, the measurement data of the propeller shaft hole is used to determine the X and Y axis coordinates and limit the rotational freedom around the X and Y axes, while the curve data of the semi-precise positioning coordinate system is used to determine the Z axis height and the circumferential distribution around the Z axis.

[0019] The propeller overall evaluation module includes:

[0020] A blade position offset error evaluation unit is used to infer the rotation characteristics of the blades in a circumferentially uniformly distributed state by measuring profile data at a specific radius;

[0021] The blade fore-aft tilt assessment unit quantifies the blade's installed tilt status by comparing the Z value differences at different radii.

[0022] The output data of the blade position offset error evaluation unit is used to guide assembly processing and dynamic balancing adjustment.

[0023] The measurement of the guide edge in the iterative measurement module includes:

[0024] Fitting the surface coordinate system based on the actual data of the pressure surface and suction surface;

[0025] The guide edge is remeasured in the curved surface coordinate system and the result is mapped to the precise positioning coordinate system for error evaluation.

[0026] The fitting process of the surface coordinate system includes iterative alignment of actual measurement data and theoretical models to approximate the actual processing state of the guide edge.

[0027] The blade rotation angle error measurement includes:

[0028] Actual data of the profile is measured at each target radius;

[0029] The rotation angle deviation at each radius is calculated based on the precise positioning coordinate system to provide data support for processing stress release.

[0030] The method also includes a unified evaluation benchmark system module for mapping the measurement data of all blades to a precise positioning coordinate system for overall evaluation, replacing the independent evaluation method of a single blade. The output data of the unified evaluation benchmark system module is used to analyze the cavitation uniformity and dynamic balance performance of the propeller.

[0031] The beneficial effects of the present invention are as follows:

[0032] The present invention has a compact and reasonable structure and is easy to operate. It establishes the precise coordinate system of the propeller through three stages of coarse positioning, semi-precise positioning and precise positioning, thereby achieving precise positioning of the propeller benchmark. On this basis, the propeller overall evaluation module is used to evaluate the position offset error and the fore-and-aft tilt state of the blades, thereby ensuring the overall performance of the propeller. At the same time, the guide edge and blade rotation angle error are iteratively measured through the iterative measurement module, thereby improving the measurement accuracy and processing quality. Finally, all blades are evaluated as a whole through a unified evaluation benchmark system module, providing strong support for the performance evaluation and improvement of the propeller. This method effectively solves the problems existing in the propeller manufacturing process, such as the difficulty in accurately determining the benchmark, the large differences in the uniformity of the blade assembly distribution, and the fore-and-aft tilt of the blades, thereby improving the manufacturing accuracy and stability of the propeller and providing strong technical support and guarantee for the mass production of the propeller. In addition, this method has the advantages of simple operation, high measurement accuracy, and comprehensive evaluation, providing an innovative measurement and evaluation method for the propeller manufacturing field.

[0033] At the same time, the present invention also has the following advantages:

[0034] This embodiment establishes a precise coordinate system for the propeller through three stages of coarse positioning, semi-precise positioning, and precise positioning, thereby achieving precise positioning of the propeller benchmark. The coarse positioning coordinate system quickly aligns the digital model with the actual workpiece by dot fitting, providing a reference for subsequent precise positioning. The semi-precise positioning coordinate system constructs a curvilinear coordinate system by scanning and measuring the key position values of the blades, which more accurately reflects the actual state of the propeller. The precise positioning coordinate system combines the measurement data of the shaft hole with the semi-precise positioning coordinate system to comprehensively limit the translation and rotational degrees of freedom of the propeller, greatly improving the accuracy and reliability of the benchmark positioning. This process effectively solves the problem of difficult to accurately determine the benchmark in traditional measurement methods, and provides a more stable benchmark for the processing and assembly of propellers.

[0035] The propeller overall evaluation module in this embodiment includes a blade position offset error evaluation and a blade fore-aft tilt evaluation, which can comprehensively evaluate the performance status of the propeller. The blade position offset error evaluation measures the profile data of each blade at a specific radial position to infer the rotation characteristics of the blade under a circumferentially uniform distribution state, providing data support for assembly processing technology and dynamic balancing adjustment. The blade fore-aft tilt evaluation quantifies the forward or backward tilt state of the blade during the installation process by measuring the Z value of the blade at different radial positions, thereby avoiding adverse conditions such as decreased efficiency and increased noise in the propeller during operation. These evaluation results provide strong support for the performance optimization and improvement of the propeller.

[0036] The iterative measurement module in this embodiment includes iterative measurement of the guide edge and blade rotation angle error measurement, which improves the measurement accuracy and processing quality through repeated iterative precision algorithms. The iterative measurement of the guide edge is based on the actual result data of the pressure surface and the suction surface, fitting the curved surface coordinate system, re-measuring the guide edge, and mapping the result to the precise positioning coordinate system for error evaluation to obtain more accurate measurement results. The blade rotation angle error measurement calculates the rotation angle deviation at each radius by measuring the actual data of the cross-sectional profile at each target radius, providing important data support for the fine processing and performance optimization of the propeller. These iterative measurement processes effectively reduce the measurement errors caused by excessive surface differences and improve the manufacturing accuracy and stability of the propeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the propeller structure under coarse positioning measurement in the present invention.

[0038] Figure 2 Schematic diagram of the propeller structure under semi-precise positioning measurement in the present invention.

[0039] Figure 3 Schematic diagram of the propeller structure under precise positioning measurement in the present invention. DETAILED DESCRIPTION

[0040] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0041] In propeller manufacturing, traditional measurement processes often focus on detailed measurement of the outer contour of individual blades, followed by positioning measurement. However, this approach evaluates each blade as an independent entity, ignoring the propeller's position within the overall structure. This can lead to inconsistent blade positioning and unstable performance during processing and assembly. Furthermore, the gap between the actual generated surface and the initial design surface can increase measurement errors of the guide edge, affecting overall measurement accuracy and product quality.

[0042] To address these issues, this embodiment proposes an innovative, comprehensive method for measuring the entire propeller. This method leverages the unique advantages of three-dimensional coordinate measurement technology and incorporates a sophisticated, iterative algorithm to accurately locate the propeller's true reference. Furthermore, the method is further extended to include detailed measurement and evaluation of each propeller blade, effectively addressing issues such as the difficulty in accurately determining the propeller reference, wide variations in blade assembly distribution, and blade tilt.

[0043] Specifically, this embodiment includes: a positioning reference establishment module, a propeller overall evaluation module, an iterative measurement module and a unified evaluation reference system module, and the measurement of the entire propeller is achieved through the mutual cooperation of each module.

[0044] Specifically, the positioning reference establishment module in this embodiment includes the following steps:

[0045] 1.1 Establishment of coarse positioning coordinate system

[0046] During the propeller measurement process, the coarse positioning coordinate system must be established first. Figure 1 As shown, the approximate position is determined by dotting. This step is performed within the three-dimensional base coordinate system, using a point-fitting method to accurately locate the propeller's approximate position. Specifically, the spatial points on the digital model are used to align the digital model position with the actual workpiece blade. However, due to the limited use of points and the deviations in the actual workpiece blade machining, the coordinate system established in this manner can only achieve a rough alignment of the propeller position, resulting in a certain degree of error.

[0047] The establishment of the coarse positioning coordinate system provides the basis for subsequent measurement work. Although there are certain errors, it can quickly align the digital model with the actual workpiece, providing a reference for subsequent precise positioning.

[0048] 1.2 Establishment of semi-precise positioning coordinate system

[0049] On the basis of the coarse positioning coordinate system, the semi-precise positioning coordinate system is established. Figure 2 As shown in the figure, by adding curves, the accuracy is improved. This step is to scan and measure the pressure surface and suction surface values of each blade at the 0.7R radius position under coarse positioning, and then establish a curve coordinate system consisting of the suction surface curve and the pressure surface curve of multiple blades with a radius of 0.7R. 0.7R is usually the design radius of the propeller, which refers to the radius of a propeller defined in the design book. It usually uses the place where the propeller has good rigidity, and then the fluid performance is usually calculated with this radius.

[0050] Scanning measurement: Use a three-dimensional coordinate measuring machine to scan the 0.7R radius position of each blade to obtain the profile data of the pressure surface and suction surface.

[0051] Curve Construction: Based on the scanned profile data, the suction and pressure curves are constructed. These curves are composed of multiple points, and the more points there are, the closer they are to the actual state.

[0052] Coordinate System Establishment: After measuring the two surfaces, the Z value of the design centerline can be calculated along the Z axis. Since machining the two surfaces will produce machining allowances, aligning the two surfaces to the theoretical model value yields a Z value that more closely approximates the actual workpiece state. Based on these curves and Z values, a semi-precise positioning coordinate system is established.

[0053] The establishment of a semi-precise positioning coordinate system further improves the accuracy of positioning. By scanning and measuring the key position values of the blades and constructing a curved coordinate system, the actual state of the propeller can be more accurately reflected, providing more accurate data support for subsequent precise positioning.

[0054] 1.3 Establishment of precise positioning coordinate system

[0055] On the basis of the semi-precise positioning coordinate system, the precise positioning coordinate system is established. Figure 3 As shown in FIG, this step is to measure the matching cylindrical shaft hole of the propeller in a semi-precise coordinate system, and then use the shaft hole and the semi-precise positioning coordinate system to restrict each other to form a precise positioning coordinate system.

[0056] Shaft hole measurement: Use a three-dimensional coordinate measuring machine to measure the propeller's matching cylindrical shaft hole and obtain the geometric parameters of the shaft hole.

[0057] Coordinate System Integration: The measured data from the shaft hole is combined with the semi-precise positioning coordinate system, constraining each other to form a precise positioning coordinate system. The cylindrical shaft hole determines the propeller's X and Y coordinates, while also constraining the rotational degrees of freedom in both directions. A curvilinear coordinate system, formed by the suction and pressure surface curves of multiple blades at a 0.7R radius, determines the propeller blade's Z value relative to the overall propeller and precisely defines the blade's circumferential orientation.

[0058] The establishment of a precise positioning coordinate system enables precise positioning of the propeller datum. By combining the measurement data of the shaft hole with the semi-precise positioning coordinate system, the propeller's translational and rotational degrees of freedom can be fully constrained, significantly improving the accuracy and reliability of the datum positioning.

[0059] The propeller overall evaluation module in this embodiment includes:

[0060] 2.1 Blade position offset error evaluation

[0061] In a precise positioning coordinate system, the blade offset error is evaluated by measuring the specific cross-section data of each blade at a radius of 0.7R, and then extrapolating and evaluating based on this data.

[0062] Profile line measurement: Use a three-coordinate measuring machine to remeasure the specific profile line data of each blade at the 0.7R radius position under a precise positioning coordinate system.

[0063] Data inference: Based on the measured profile data, the specific state and characteristics of each blade around the Z-axis rotation axis are inferred when the blade is uniformly distributed in the circumferential direction.

[0064] By measuring and inferring the profile data of the blades at specific radial positions, it is possible to evaluate the rotational characteristics of the blades when they are uniformly distributed circumferentially, providing data support for assembly processing and dynamic balancing adjustments, and ensuring the overall performance of the propeller.

[0065] 2.2 Blade Fore-and-aft Tilt Assessment

[0066] The blades' fore-aft tilt is assessed in a precisely positioned coordinate system by precisely measuring the Z value of each blade at specific radii (0.4R and 0.9R) and then comparing these two values.

[0067] Z value measurement: Use a three-coordinate measuring machine to measure the Z value of each blade at the 0.4R and 0.9R radius positions in a precise positioning coordinate system.

[0068] Comparative Analysis: Compare and analyze the measured Z values and calculate the difference. This difference can quantify the forward or backward tilt of the blade during installation.

[0069] By measuring and comparing the Z values of the blades at different radial positions, the fore-aft tilt of the blades can be evaluated, providing strong support for subsequent adjustments and optimizations, and avoiding adverse situations such as decreased propeller efficiency and increased noise during operation.

[0070] The iterative measurement module in this embodiment includes:

[0071] 3.1 Iterative measurement of guide edge

[0072] In the precise positioning coordinate system, iterative measurement of the guide edge is performed. This step is based on the actual result data of the pressure and suction surfaces, fitting the surface coordinate system, then re-measuring the guide edge in this coordinate system and mapping the results to the precise positioning coordinate system for error evaluation.

[0073] Data acquisition: The actual result data of the pressure surface and suction surface are obtained through measurement.

[0074] Surface fitting: Fitting the surface coordinate system based on the actual result data. The fitting process involves iteratively aligning the actual measurement data with the theoretical model to approximate the actual processing state of the guide edge.

[0075] Guide edge measurement: Remeasure the guide edge in the fitted surface coordinate system.

[0076] Error evaluation: The measured guide edge results are mapped to a precise positioning coordinate system for error evaluation.

[0077] Iterative measurement of the guide edge can more closely reflect the actual machining state and obtain more accurate measurement results. This is of great significance for improving the machining accuracy and performance of propellers.

[0078] 3.2 Blade rotation angle error measurement

[0079] The blade rotation angle error is measured in a precise positioning coordinate system. This step is done by measuring the actual data of the cross-section profile at each target radius and then calculating the rotation angle deviation at each radius based on the precise positioning coordinate system.

[0080] Profile measurement: Use a three-dimensional coordinate measuring machine to measure the actual data of the profile at each target radius.

[0081] Angle calculation: Based on the precise positioning coordinate system, calculate the rotation angle deviation at each radius.

[0082] The blade rotation angle error measurement can accurately measure the blade rotation angle error at each radius of the propeller, providing important data support for the fine processing and performance optimization of the propeller.

[0083] In this embodiment, the unified evaluation benchmark system module includes the establishment of a unified evaluation benchmark system based on a precise positioning coordinate system. This unified evaluation benchmark system maps the measurement data of all blades to the precise positioning coordinate system for integrated evaluation, replacing the independent evaluation method for each blade.

[0084] Data mapping: Map the measurement data of all blades to a precise positioning coordinate system.

[0085] Overall evaluation: Based on the mapped data, the propeller is evaluated as a whole.

[0086] The unified evaluation benchmark system makes the evaluation results more holistic and objective, providing strong support for propeller performance evaluation and improvement. Through holistic evaluation, a more comprehensive understanding of the propeller's performance status can be achieved, providing data support for subsequent optimization and improvement.

[0087] The method for high-precision iterative propeller inspection using a three-dimensional coordinate measuring machine proposed in this invention establishes a precise coordinate system for the propeller through three stages: coarse positioning, semi-precise positioning, and precise positioning, thereby achieving precise positioning of the propeller benchmark. On this basis, the propeller overall evaluation module is used to evaluate the position offset error and fore-aft tilt state of the blades, ensuring the overall performance of the propeller. At the same time, the iterative measurement module is used to iteratively measure the guide edge and blade rotation angle errors, improving measurement accuracy and processing quality. Finally, a unified evaluation benchmark system module is used to conduct an integrated evaluation of all blades, providing strong support for propeller performance evaluation and improvement.

[0088] This method effectively solves problems existing in the propeller manufacturing process, such as the difficulty in accurately determining the benchmark, large differences in the uniformity of blade assembly distribution, and the forward and backward tilt of the blades. It improves the manufacturing accuracy and stability of the propeller and provides strong technical support and guarantee for the mass production of propellers.

[0089] The method of the present invention for iteratively detecting propellers with a three-dimensional coordinate measuring machine is mainly based on the working principle of three-dimensional coordinate measurement technology and a precise algorithm of repeated iterations. First, the precise coordinate system of the propeller is established through three stages of coarse positioning, semi-precise positioning, and precise positioning to achieve precise positioning of the propeller benchmark. Then, the propeller is measured and evaluated as a whole in the precise coordinate system, including key parameters such as the position offset error of the blades, the fore-and-aft tilt state, and the guide edge and blade rotation angle errors. Finally, all measurement data are evaluated as a whole through a unified evaluation benchmark system to provide data support for the performance evaluation and improvement of the propeller.

[0090] During the measurement process, a CMM acquires workpiece geometric data through probe contact or laser scanning. This data is processed and analyzed to establish a coordinate system, measure key parameters, and perform error evaluation. Simultaneously, iterative, sophisticated algorithms continuously optimize measurement paths and data processing methods to improve measurement accuracy and efficiency.

[0091] In summary, the method for high-precision iterative detection of propellers using a three-dimensional coordinate measuring machine of the present invention has the advantages of high measurement accuracy, comprehensive evaluation, and simple operation, and provides an innovative measurement and evaluation method for the propeller manufacturing field.

[0092] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any modifications may be made within the scope of protection of the present invention.

Claims

1. A method for high-precision iterative detection of propellers using a three-dimensional coordinate measuring machine, characterized in that: include: Positioning reference establishment module, used to establish the precise coordinate system of the propeller through three stages: coarse positioning, semi-precise positioning and precise positioning; A propeller overall evaluation module, connected to the positioning reference establishment module, is used to measure the profile data of the blade in a precise coordinate system and evaluate the blade position offset error and fore-aft tilt state; an iterative measurement module, connected to the propeller overall evaluation module, for iteratively measuring the leading edge and measuring the rotation angle error of blades of each radius based on the measurement data; In the rough positioning stage, the digital model and the actual workpiece are preliminarily aligned by fitting the approximate position of the propeller in the three-coordinate basic coordinate system; In the semi-precise positioning stage, the pressure surface and suction surface profile values at a specific radius of the blade are scanned to construct a curvilinear coordinate system consisting of the suction surface curve and the pressure surface curve, thereby determining the Z-axis height and circumferential direction. In the precise positioning stage, the propeller shaft hole is measured and combined with a semi-precise positioning coordinate system to determine the X and Y axis positions and limit the rotational freedom to form a precise positioning coordinate system.

2. The method according to claim 1, characterized in that In the coarse positioning stage, the point fitting is performed by selecting spatial points on the digital model to align with the actual workpiece blade, and the established coordinate system can only achieve rough alignment of the propeller position.

3. The method according to claim 1, characterized in that In the semi-precise positioning stage, when scanning and measuring the profile values of the pressure surface and the suction surface at a specific radius of the blade, the actual Z-axis height is calculated by aligning the machining allowances of the pressure surface and the suction surface with the theoretical model value.

4. The method according to claim 1, wherein During the precise positioning stage, the measurement data of the propeller shaft hole is used to determine the X and Y axis coordinates and limit the rotational freedom around the X and Y axes, while the curve data of the semi-precise positioning coordinate system is used to determine the Z axis height and the circumferential distribution around the Z axis.

5. The method according to claim 4, characterized in that The propeller overall evaluation module includes: A blade position offset error evaluation unit is used to infer the rotation characteristics of the blades in a circumferentially uniformly distributed state by measuring profile data at a specific radius; The blade fore-aft tilt assessment unit quantifies the blade's installed tilt status by comparing the Z value differences at different radii.

6. The method according to claim 5, characterized in that The output data of the blade position offset error evaluation unit is used to guide assembly processing and dynamic balancing adjustment.

7. The method according to claim 1, characterized in that The measurement of the guide edge in the iterative measurement module includes: Fitting the surface coordinate system based on the actual data of the pressure surface and suction surface; The guide edge is remeasured in the curved surface coordinate system and the result is mapped to the precise positioning coordinate system for error evaluation.

8. The method according to claim 7, characterized in that The fitting process of the surface coordinate system includes iterative alignment of actual measurement data and theoretical models to approximate the actual processing state of the guide edge.

9. The method according to claim 1, characterized in that The blade rotation angle error measurement includes: Actual data of the profile is measured at each target radius; The rotation angle deviation at each radius is calculated based on the precise positioning coordinate system to provide data support for processing stress release.

10. The method according to claim 1, characterized in that The method also includes a unified evaluation benchmark system module for mapping the measurement data of all blades to a precise positioning coordinate system for overall evaluation, replacing the independent evaluation method of a single blade. The output data of the unified evaluation benchmark system module is used to analyze the cavitation uniformity and dynamic balance performance of the propeller.

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